bluuebunny/crossref_metadata_2025_split huggingface dataset:
Numerical modelling of aeolian erosion over a surface with non‐uniformly distributed roughness elements
Authors: Furieri B. , Harion J. L. , Milliez M. , Russeil S. , Santos J. M. 
Published: May 2013

ABSTRACTThe present study is focused on the analysis of the mean wall friction velocity on a surface including roughness elements exposed to a turbulent boundary layer. These roughness elements represent non‐erodible particles over an erodible surface of an agglomeration of granular material on industrial sites. A first study has proposed a formulation that describes the evolution of the friction velocity as a function of geometrical parameters and cover rate with different uniform roughness distributions. The present simulations deal with non‐uniform distributions of particles with a random sampling of diameters, heights, positions and arrangements. The evolution (relative to geometrical parameters of the roughness elements) of the friction velocity for several non‐uniform distributions of roughness elements was analysed by the equation proposed in the literature and compared to the results obtained with the numerical simulations. This comparison showed very good agreement. Thus, the formulation developed for uniform particles was found also to be valid for a larger spectrum of particles noted on industrial sites. The present work aims also to investigate in detail the fluid mechanics over several roughness particles. Copyright © 2013 John Wiley & Sons, Ltd.
Evaluation of trenching, ground penetrating radar (GPR) and electrical resistivity tomography (ERT) for sinkhole characterization
Authors: Carbonel Domingo , Rodríguez Verónica , Gutiérrez Francisco , McCalpin James P. , Linares Rogelio , Roqué Carles , Zarroca Mario , Guerrero Jesús , Sasowsky Ira 
Published: May 2013

ABSTRACTThis paper explores the suitability and advantages of combining the trenching technique with geophysical surveys [ground penetrating radar (GPR) and electrical resistivity tomography (ERT)] for sinkhole characterization in a mantled karst area. The approach is applied to two active sinkholes concealed by anthropogenic deposits and formed by contrasting subsidence mechanisms; collapse and sagging. The ERT section acquired across the collapse sinkhole images the clayey fill of the depression as an obvious low resistivity area, showing the approximate location of the sinkhole edges. Spatially dense GPR surveys provide information on the position of the boundaries of the concealed subsidence structures and their three‐dimensional (3D) internal geometry, revealing the dominant subsidence mechanism. We illustrate the impact of several factors on the quality of the GPR data such as sinkhole size, nominal frequency of the antennas, antenna shielding, and the presence of backfilled excavations and above‐surface objects. Trenches provided detailed information on the subsurface structure of the sinkhole, subsidence magnitude, partitioning of the strain, and the position of the sinkhole edges, especially when they are deep enough and excavated across the central sector and perpendicular to the boundaries. The stratigraphic and structural relationships observed in the trench were then used to infer the spatial evolution of the sinkholes (e.g. enlargement), their kinematic behavior (episodic versus progressive), and to differentiate discrete subsidence events and their associated magnitude. Numerical dates were used to estimate average subsidence rates and the recurrence of subsidence events. Such integrated data sets may be used as an objective basis to forecast the future behavior of potentially damaging sinkholes and to assess the associated hazard and risk. Copyright © 2013 John Wiley & Sons, Ltd.
GNSS observations of deep convective time scales in the Amazon
Authors: Adams D. K. , Gutman Seth I. , Holub Kirk L. , Pereira Dulcineide S. 
Published: May 2013

AbstractIn the tropics, understanding the shallow‐to‐deep transition and organization of convection on the mesoscale is made difficult due the paucity of long‐term high spatial/temporal resolution data. In this paper, data from the world's first long‐term equatorial Global Navigational Satellite System meteorological station in Manaus (Central Amazon) is used to create a new metric, a water vapor convergence time scale, to characterize the temporal evolution of deep convection over a tropical continental region. From 3.5 years of data, 320 convective events were analyzed using a compositing analysis. Results reveal two characteristic time scales of water vapor convergence; an 8 h time scale of weak convergence and 4 h timescale of intense water vapor convergence associated with the shallow‐to‐deep convection transition. The 4 h shallow‐to‐deep transition time scale is particularly robust, regardless of convective intensity, seasonality, or nocturnal versus daytime convection. This new result provides a useful metric for both high resolution and global climate models to replicate.
Ketamine attenuates cytochrome p450 aromatase gene expression and estradiol‐17β levels in zebrafish early life stages
Authors: Trickler William J. , Guo Xiaoqing , Cuevas Elvis , Ali Syed F. , Paule Merle G. , Kanungo Jyotshna 
Published: May 2013

ABSTRACTKetamine, a dissociative anesthetic, is a noncompetitive antagonist of N‐methyl‐D‐aspartate‐type glutamate receptors. In rodents and non‐human primates as well as in zebrafish embryos, ketamine has been shown to be neurotoxic. In cyclic female rats, ketamine has been shown to decrease serum estradiol‐17β (E2) levels. E2 plays critical roles in neurodevelopment and neuroprotection. Cytochrome p450 (CYP) aromatase catalyzes E2 synthesis from androgens. Although ketamine down‐regulates a number of CYP enzymes in rodents, its effect on the CYP aromatase (CYP19) is not known. Zebrafish have been used as a model system for examining mechanisms underlying drug effects. Here, using wild‐type (WT) zebrafish (Danio rerio) embryos, we demonstrate that ketamine significantly reduced E2 levels compared with the control. However, the testosterone level was elevated in ketamine‐treated embryos. These results are concordant with data from mammalian studies. Ketamine also attenuated the expression of the ovary form of CYP aromatase (cyp19a1a) at the transcriptional level but not the brain form of aromatase, cyp19a1b. Exogenous E2 potently induced the expression of cyp19a1b and vtg 1, both validated biomarkers of estrogenicity and endocrine disruption, but not cyp19a1a expression. Attenuation of activated ERK/MAPK levels, reportedly responsible for reduced human cyp19 transcription, was also observed in ketamine‐treated embryos. These results suggest that reduced E2 levels in ketamine‐treated embryos may have resulted from the suppression of cyp19a1a transcription. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Inhibition of cytochrome P450s enhances (+)‐usnic acid cytotoxicity in primary cultured rat hepatocytes
Authors: Shi Qiang , Greenhaw James , Salminen William F. 
Published: May 2013

ABSTRACT(+)‐Usnic acid (UA) is consumed as a dietary supplement to promote weight loss; however, dietary supplements containing UA have been associated with clinical cases of severe liver injury. UA has been shown to be hepatotoxic in rats and is extensively metabolized by hepatic cytochrome P450s (CYPs); therefore, we examined if UA metabolism results in the formation of cytotoxic metabolites or if metabolism is a detoxification process in primary rat hepatocytes. When CYP activity was suppressed by the non‐isoenzyme‐selective inhibitor SKF‐525A (20 μM), or the CYP1A inhibitor alpha‐naphthoflavone (10 μM), or the CYP3A inhibitor ketoconazole (25 μM), the cytotoxicity of UA at 3 ~ 6 μM after 3 ~ 20 h of exposure was significantly increased as measured by lactate dehydrogenase (LDH) leakage. At 2 h after UA exposure, an earlier time point prior to LDH release, these CYP inhibitors potentiated UA‐induced inhibition of cellular respiration as determined by the Clark type oxygen electrode. Cellular adenosine triphosphate (ATP) depletion by UA was also exacerbated by these CYP inhibitors. The CYP2B/2C inhibitor, ticlopidine at 20 μM, showed no effects in parallel experiments. These data demonstrate that UA is bio‐transformed to less toxic metabolites in rat primary hepatocytes, probably mainly by CYP1A and 3A, but not 2B/2C. Published 2013. This article is a U.S. Government work and is in the public domain in the USA.
Longitudinal modulation of the brightness of Io's auroral footprint emission: Comparison with models
Authors: Wannawichian S. , Clarke J. T. , Bagenal F. , Smyth W. H. , Peterson C. A. , Nichols J. D. 
Published: May 2013

AbstractThe auroral emission close to the foot of Io's magnetic flux tube has been known for over a decade to be one of the key parameters characterizing the electrodynamic interaction between the satellite and Jupiter's magnetosphere. Ten years of observations of Io's magnetic footprint brightness have been conducted via far ultraviolet imaging by two instruments, the Space Telescope Imaging Spectrograph and the Advanced Camera for Surveys, on board the Hubble Space Telescope. The variation of Io's magnetic footprint brightness was found to have a strong correlation with the satellite's location in system III longitude. The persistent pattern of the variation of the brightness of the auroral emission at Io's magnetic footprint with longitude over 10 years of observations implies that the footprint emissions are primarily determined by processes other than temporal variations of the plasma torus. The changing location of Io in the plasma torus with longitude corresponds to changes in centrifugal latitude and to the plasma density in the vicinity of Io, likely affecting the electrodynamic interaction at the satellite. To test this, quantitative models of electron density and the generated power near Io are applied to simulate the observed footprint brightness variation pattern. We find, however, that the longitudinal variations in plasma conditions needed to produce changes in the electrodynamic interaction comparable to the observed modulation of the footprint emissions would require an unrealistically colder plasma torus than previously measured. We quantify the additional energy needed to produce the asymmetric emission peaks at 110° and 270° longitudes.
A seasonal trend of single scattering albedo in southern African biomass‐burning particles: Implications for satellite products and estimates of emissions for the world's largest biomass‐burning source
Authors: Eck T. F. , Holben B. N. , Reid J. S. , Mukelabai M. M. , Piketh S. J. , Torres O. , Jethva H. T. , Hyer E. J. , Ward D. E. , Dubovik O. , Sinyuk A. , Schafer J. S. , Giles D. M. , Sorokin M. , Smirnov A. , Slutsker I. 
Published: May 2013

AbstractAs a representative site of the southern African biomass‐burning region, sun‐sky data from the 15 year Aerosol Robotic Network (AERONET) deployment at Mongu, Zambia, was analyzed. For the biomass‐burning season months (July–November), we investigate seasonal trends in aerosol single scattering albedo (SSA), aerosol size distributions, and refractive indices from almucantar sky scan retrievals. The monthly mean single scattering albedo at 440 nm in Mongu was found to increase significantly from ~0.84 in July to ~0.93 in November (from 0.78 to 0.90 at 675 nm in these same months). There was no significant change in particle size, in either the dominant accumulation or secondary coarse modes during these months, nor any significant trend in the Ångström exponent (440–870 nm; r2 = 0.02). A significant downward seasonal trend in imaginary refractive index (r2 = 0.43) suggests a trend of decreasing black carbon content in the aerosol composition as the burning season progresses. Similarly, burning season SSA retrievals for the Etosha Pan, Namibia AERONET site also show very similar increasing single scattering albedo values and decreasing imaginary refractive index as the season progresses. Furthermore, retrievals of SSA at 388 nm from the Ozone Monitoring Instrument satellite sensor show similar seasonal trends as observed by AERONET and suggest that this seasonal shift is widespread throughout much of southern Africa. A seasonal shift in the satellite retrieval bias of aerosol optical depth from the Moderate Resolution Imaging Spectroradiometer collection 5 dark target algorithm is consistent with this seasonal SSA trend since the algorithm assumes a constant value of SSA. Multi‐angle Imaging Spectroradiometer, however, appears less sensitive to the absorption‐induced bias.
Quality assessment and assimilation of Megha‐Tropiques SAPHIR radiances into WRF assimilation system
Authors: Singh Randhir , Ojha Satya P. , Kishtawal C. M. , Pal P. K. 
Published: May 2013

AbstractThis study presents an initial assessment of the quality of radiances measured from SAPHIR (Sounder for Probing Vertical Profiles of Humidity) on board Megha‐Tropiques (Indo‐French joint satellite), launched by the Indian Space Research Organisation on 12 October 2011. The radiances measured from SAPHIR are compared with those simulated by the radiative transfer model (RTM) using radiosondes measurements, Atmospheric Infrared Sounder retrievals, and National Centers for Environmental Prediction (NCEP) analyzed fields over the Indian subcontinent, during January to November 2012. The radiances from SAPHIR are also compared with the similar measurements available from Microwave Humidity Sounder (MHS) on board MetOp‐A and NOAA‐18/19 satellites, during January to November 2012. A limited comparison is also carried out between SAPHIR measured and the RTM computed radiances using European Centre for Medium‐Range Weather Forecasts analyzed fields, during May and November 2012. The comparison of SAPHIR measured radiances with RTM simulated and MHS observed radiances reveals that SAPHIR observations are of good quality. After the initial assessment of the quality of the SAPHIR radiances, these radiances have been assimilated within the Weather Research and Forecasting (WRF) three‐dimensional variational data assimilation system. Analysis/forecast cycling experiments with and without SAPHIR radiances are performed over the Indian region during the entire month of May 2012. The assimilation of SAPHIR radiances shows considerable improvements (with moisture analysis error reduction up to 30%) in the tropospheric analyses and forecast of moisture, temperature, and winds when compared to NCEP analyses and radiances measurement obtained from MHS, Advanced Microwave Sounding Unit‐A, and High Resolution Infrared Sounder. Assimilation of SAPHIR radiances also resulted in substantial improvement in the precipitation forecast skill when compared with satellite‐derived rain. Overall, initial results show the usefulness of SAPHIR radiances in the numerical weather prediction data assimilation systems.
The Role of Credit, Currency and Debt Crises in Trade Performance: A Product‐Disaggregated Panel Data Analysis
Authors: Prasada D. V. Pahan 
Published: May 2013

AbstractThe impacts of financial crisis shocks on trade performance are investigated for a sample of Asian countries that experienced financial crises during the 1980–2006 period. Credit, currency appreciation, currency depreciation and external debt shocks are considered. The focus is to look beyond aggregates into sub‐sector level exports using disaggregated data for 27 industries. We look at how the shocks affect bilateral exports in general and fluctuation of exports in terms of creation and diversion in particular. Further, the impact of each crisis shock on the level of competitiveness and the degree of diversification of exports is assessed. Copyright © 2013 John Wiley & Sons, Ltd.
Ultrastructure of the male genital tract, spermatogenesis and spermatozoa of hattena cometis domrow (Acari: Gamasida: Ameroseiidae)
Authors: Alberti Gerd , Seeman Owen D. , Di Palma Antonella 
Published: May 2013

ABSTRACTThe ameroseiid mite Hattena cometis has a male genital system that consists of an unpaired, u‐shaped testis and paired deferent ducts leading into an unpaired accessory genital gland and ejaculatory duct. The genital opening is located anteriorly immediately in front of the sternal shield. Spermatogenesis is simple, probably due to the haploid nature of the male. Eight stages of spermatogenesis could be roughly distinguished. Mature spermatozoa as found in the deferent duct lumen are peculiar in having a bisected nucleus and numerous peripheral flat chambers, which were formed from indentations of the plasmalemma. In inseminated females, spermatozoa were observed in the syncytial tissue of the sperm access system and in the somatic cells of the ovary. These spermatozoa have achieved a new structure, i.e., an electron‐dense plate dividing the cell into two unequal halves. The dense plate has an intricate substructure. Its function is unknown. These sperm cells are considered to represent capacitated spermatozoa. The peripheral chambers are reduced in number inside the female. Similar sperm cells, containing a dense plate, were seen in vacuoles within the epithelium of the deferent duct of one male. These cells are evidently under destruction, but before being completely dissolved had undergone a development leading beyond that of the mature sperm cells found in the deferent duct. Apparently, entering the cell of the deferent duct epithelium or the syncytium tissue triggers the production of the dense plate (or the capacitation process). Our observations are compared with results obtained from other anactinotrichid Acari, mainly Gamasida, and confirm and complete the interpretation of the correlated evolution of components of gamasid reproductive systems. J. Morphol. 274:1010–1025, 2013. © 2013 Wiley Periodicals, Inc.
The filter pads and filtration mechanisms of the devil rays: Variation at macro and microscopic scales
Authors: Paig‐Tran E.W. Misty , Kleinteich Thomas , Summers Adam P. 
Published: May 2013

ABSTRACTThree lineages of cartilaginous fishes have independently evolved filter feeding (Lamniformes: Megachasma and Cetorhinus, Orectolobiformes: Rhincodon, and Mobulidae: Manta and Mobula); and the structure of the branchial filters is different in each group. The filter in Rhincodon typus has been described; species within the Lamniformes have simple filamentous filters, but the anatomy and ultrastructure of the branchial filter in the mobulid rays varies and is of functional interest. In most fishes, branchial gill rakers are elongated structures located along the anterior ceratobranchial and/or epibranchial arches; however, mobulid gill rakers are highly modified, flattened, lobe‐like structures located on the anterior and posterior epibranchial elements as well as the ceratobranchials. The ultrastructure of the filter lobes can be smooth or covered by a layer of microcilia, and some are denticulated along the dorsal and ventral lobe surface. Flow through the mobulid oropharyngeal cavity differs from other filter‐feeding fishes in that water must rapidly deviate from the free stream direction. There is an abrupt 90° turn from the initial inflowing path to move through the laterally directed branchial filter pores, over the gill tissue, and out the ventrally located gill slits. The deviation in the flow must result in tangential shearing stress across the filter surface. This implies that mobulids can use cross‐flow filtration in which this shearing force serves as a mechanism to resuspend food particles initially caught by sieving or another capture mode. These particles will be transported by the cross filter flow toward the esophagus. We propose that species with cilia on the rakers augment the shear mediated movement of particles along the filter with ciliary transport. J. Morphol. 274:1026–1043, 2013. © 2013 Wiley Periodicals, Inc.
Pigments accumulation via light and oxygen in Rhodobacter capsulatus strain XJ‐1 isolated from saline soil
Authors: Lin Zhihua , Cui Xiaohua , Zhao Chungui , Yang Suping , Imhoff Johannes F. 
Published: May 2013

AbstractA Rhodobacter capsulatus strain, designated XJ‐1, isolated from saline soil, accumulated almost only one kind of bacteriochlorophyll a anaerobically in the light, aerobically in the light and dark, and the relative contents of the bacteriochlorophyll a were 44.61, 74.89, and 77.53% of the total pigments, respectively. A new purple pigment appeared only in aerobic‐light grown cells, exhibited absorption maxima at 355, 389, 520, 621, and 755 nm, especially distinctly unusual peak at 621 nm, whereas vanished in anaerobic‐light and in aerobic‐dark culture. Spheroidene and OH–spheroidene predominated in anaerobic phototrophic cultures. Spheroidenone was the sole carotenoid when exposed to both light and oxygen. The second keto‐carotenoids, OH–spheroidenone, presented only in aerobic‐dark culture in addition to spheroidenone. Strain XJ‐1 would be a good model organism for the further illustration of the regulation of bacteriochlorophyll biosynthesis gene expression in response to unique habitat.
Stress and development in Dictyostelium discoideum: the involvement of the catalytic calcineurin A subunit
Authors: Thewes Sascha , Schubert Sebastian K. , Park Kyuhyeon , Mutzel Rupert 
Published: May 2013

AbstractCalcium signaling is one of the most important signaling‐pathways in all eukaryotes. One important target activated by an increased intracellular calcium concentration via calmodulin is the protein phosphatase calcineurin, which is composed of a catalytic subunit (calcineurin A) and a regulatory subunit (calcineurin B). The importance of calcium and calcineurin for the differentiation and development of the social amoeba Dictyostelium discoideum has already been shown by pharmacological approaches. However, so far only a RNAi‐silenced calcineurin B mutant has been investigated on a molecular level. Here, we describe the construction and phenotypic investigation of a RNAi‐silenced calcineurin A mutant. Phenotypic aberrations during development resemble those produced by silencing of calcineurin B with ectopic tip formation of the fruiting bodies. Additionally, we tested the response of the mutants under various stress conditions in liquid culture as well as during development. Both, calcineurin A and B RNAi‐mutants, are hypersensitive during development towards cation stress. Besides its role in development, calcineurin is thus also involved in the stress response in D. discoideum. Further, our data imply that many functions of calcineurin are conserved among the eukaryotes.
Peptide profiling of the route from Mahoney to Sabin, and return
Authors: Kanduc Darja , Fasano Candida , Bavaro Simona Lucia , Novello Giuseppe , Lucchese Guglielmo , Capone Giovanni 
Published: May 2013

ABSTRACTIn order to define poliovirus (PV) neurovirulence at the molecular level, we comparatively analyze the primary amino acid sequence of Mahoney, a neurovirulent PV strain, versus (i) Sabin, an attenuated PV strain, and (ii) IS1, a PV isolate obtained in temporal association to a paralysis event from a polio vaccinated subject. We identify and describe 12 pentapeptides that, originally present in the Mahoney sequence, are changed in the non‐neurovirulent Sabin strain, and, successively, restored in IS1 strain.