bluuebunny/crossref_metadata_2025_split huggingface dataset:
Quantifying wintertime boundary layer ozone production from frequent profile measurements in the Uinta Basin, UT, oil and gas region
Authors: Schnell Russell C. , Johnson Bryan J. , Oltmans Samuel J. , Cullis Patrick , Sterling Chance , Hall Emrys , Jordan Allen , Helmig Detlev , Petron Gabrielle , Ahmadov Ravan , Wendell James , Albee Robert , Boylan Patrick , Thompson Chelsea R. , Evans Jason , Hueber Jacques , Curtis Abigale J. , Park Jeong‐Hoo 
Published: August 2016

AbstractAs part of the Uinta Basin Winter Ozone Study, January–February 2013, we conducted 937 tethered balloon‐borne ozone vertical and temperature profiles from three sites in the Uinta Basin, Utah (UB). Emissions from oil and gas operations combined with snow cover were favorable for producing high ozone‐mixing ratios in the surface layer during stagnant and cold‐pool episodes. The highly resolved profiles documented the development of approximately week‐long ozone production episodes building from regional backgrounds of ~40 ppbv to >165 ppbv within a shallow cold pool up to 200 m in depth. Beginning in midmorning, ozone‐mixing ratios increased uniformly through the cold pool layer at rates of 5–12 ppbv/h. During ozone events, there was a strong diurnal cycle with each succeeding day accumulating 4–8 ppbv greater than the previous day. The top of the elevated ozone production layer was nearly uniform in altitude across the UB independent of topography. Above the ozone production layer, mixing ratios decreased with height to ~ 400 m above ground level where they approached regional background levels. Rapid clean‐out of ozone‐rich air occurred within a day when frontal systems brought in fresh air. Solar heating and basin topography led to a diurnal flow pattern in which daytime upslope winds distributed ozone precursors and ozone in the Basin. NOx‐rich plumes from a coal‐fired power plant in the eastern sector of the Basin did not appear to mix down into the cold pool during this field study.
Multiyear study of the dependence of sea salt aerosol on wind speed and sea ice conditions in the coastal Arctic
Authors: May N. W. , Quinn P. K. , McNamara S. M. , Pratt K. A. 
Published: August 2016

AbstractThinning of Arctic sea ice gives rise to ice fracturing and leads (areas of open water surrounded by sea ice) that are a potential source of sea salt aerosol. Atmospheric particle inorganic ion concentrations, local sea ice conditions, and meteorology at Barrow, AK, from 2006 to 2009, were combined to investigate the dependence of submicron (aerodynamic diameter < 1 µm) and supermicron (aerodynamic diameter 1–10 µm) sea salt mass concentrations on sea ice coverage and wind speed. Consistent with a wind‐dependent source, supermicron sea salt mass concentrations increased in the presence of nearby leads and wind speeds greater than 4 m s−1. Increased supermicron and submicron sea salt chloride depletion was observed for periods of low winds or a lack of nearby open water, consistent with transported sea salt influence. Sea salt aerosol produced from leads has the potential to alter cloud formation, as well as the chemical composition of the Arctic atmosphere and snowpack.
Atmospheric benzene observations from oil and gas production in the Denver‐Julesburg Basin in July and August 2014
Authors: Halliday Hannah S. , Thompson Anne M. , Wisthaler Armin , Blake Donald R. , Hornbrook Rebecca S. , Mikoviny Tomas , Müller Markus , Eichler Philipp , Apel Eric C. , Hills Alan J. 
Published: August 2016

AbstractHigh time resolution measurements of volatile organic compounds (VOCs) were collected using a proton‐transfer‐reaction quadrupole mass spectrometry (PTR‐QMS) instrument at the Platteville Atmospheric Observatory (PAO) in Colorado to investigate how oil and natural gas (O&NG) development impacts air quality within the Wattenburg Gas Field (WGF) in the Denver‐Julesburg Basin. The measurements were carried out in July and August 2014 as part of NASA's “Deriving Information on Surface Conditions from Column and Vertically Resolved Observations Relevant to Air Quality” (DISCOVER‐AQ) field campaign. The PTR‐QMS data were supported by pressurized whole air canister samples and airborne vertical and horizontal surveys of VOCs. Unexpectedly high benzene mixing ratios were observed at PAO at ground level (mean benzene = 0.53 ppbv, maximum benzene = 29.3 ppbv), primarily at night (mean nighttime benzene = 0.73 ppbv). These high benzene levels were associated with southwesterly winds. The airborne measurements indicate that benzene originated from within the WGF, and typical source signatures detected in the canister samples implicate emissions from O&NG activities rather than urban vehicular emissions as primary benzene source. This conclusion is backed by a regional toluene‐to‐benzene ratio analysis which associated southerly flow with vehicular emissions from the Denver area. Weak benzene‐to‐CO correlations confirmed that traffic emissions were not responsible for the observed high benzene levels. Previous measurements at the Boulder Atmospheric Observatory (BAO) and our data obtained at PAO allow us to locate the source of benzene enhancements between the two atmospheric observatories. Fugitive emissions of benzene from O&NG operations in the Platteville area are discussed as the most likely causes of enhanced benzene levels at PAO.
Wave reflection from randomly inhomogeneous ionospheric layer: 1. The method of describing the wavefield in a reflecting layer with random irregularities
Authors: Tinin Mikhail 
Published: August 2016

AbstractIt has been previously proposed to describe wave propagation in inhomogeneous media in a small‐angle approximation with the aid of a double weighted Fourier transform (DWFT) method. This method agrees with the methods of geometrical optics, smooth perturbations, and phase screen in domains of their applicability; therefore, it can be employed to solve direct and inverse problems of radio wave propagation in multiscale inhomogeneous ionospheric plasma. In this paper, for the DWFT wide‐angle generalization a wave equation is preliminary reduced using the Fock proper‐time method to a parabolic equation that then is solved by the DWFT method. The resulting solution is analyzed for the case of wave reflection and scattering by a layer with random irregularities and linear profile of average permittivity. We show the transformation of this solution into strict results in the absence of irregularities and in the single‐scatter approximation, including backscattering, during weak phase fluctuations. Under certain conditions, the solution takes the form of the small‐angle DWFT with respect to refraction in the layer and backscatter effects. Spatial processing in source and observer coordinates brings a beam of received waves into one wave without amplitude fluctuations, which allows an increase in resolution of vertical ionospheric sounding systems.
Adaptive backstepping trajectory tracking controller for a miniature helicopter
Authors: Zou Yao 
Published: August 2016

SummaryAn adaptive backstepping controller is proposed to achieve the asymptotically stable trajectory tracking for a miniature helicopter. The helicopter model is firstly decomposed into a cascaded structure between the position and attitude loops with unmodeled dynamics. The backstepping technique is applied to exploit this cascaded structure and to streamline the controller design procedure. Hyperbolic tangent functions, instead of traditional sign functions, are adopted to complete adaptive algorithms for adjusting the upper bounds of the unmodeled dynamics. Further, the controller introduces an auxiliary dynamic system to ensure the thrust constraint and to obviate singularity during the command attitude extraction. The stability analysis demonstrates that, the asymptotical stability of the auxiliary dynamic system warrants the asymptotically stable tracking of the miniature helicopter system. Simulations verify the theoretical results and analyze the tracking performance. Copyright © 2016 John Wiley & Sons, Ltd.
Catalytic reduction of 4‐nitrophenol using silver nanoparticles‐engineered poly(N‐isopropylacrylamide‐co‐acrylamide) hybrid microgels
Authors: Begum Robina , Farooqi Zahoor H. , Ahmed Ejaz , Naseem Khalida , Ashraf Sania , Sharif Ahsan , Rehan Rida 
Published: August 2016

Nearly monodisperse poly(N‐isopropylacrylamide‐co‐acrylamide) [P(NIPAM‐co‐AAm)] microgels were synthesized using precipitation polymerization in aqueous medium. These microgels were used as microreactors to fabricate silver nanoparticles by chemical reduction of silver ions inside the polymer network. The pure and hybrid microgels were characterized using Fourier transform infrared and UV–visible spectroscopies, dynamic light scattering, X‐ray diffraction, thermogravimetric analysis, differential scanning calorimetry and transmission electron microscopy. Results revealed that spherical silver nanoparticles having diameter of 10–20 nm were successfully fabricated in the poly(N‐isopropylacrylamide‐co‐acrylamide) microgels with hydrodynamic diameter of 250 ± 50 nm. The uniformly loaded silver nanoparticles were found to be stable for long time due to donor–acceptor interaction between amide groups of polymer network and silver nanoparticles. Catalytic activity of the hybrid system was tested by choosing the catalytic reduction of 4‐nitrophenol as a model reaction under various conditions of catalyst dose and concentration of NaBH4 at room temperature in aqueous medium to explore the catalytic process. The progress of the reaction was monitored using UV–visible spectrophotometry. The pseudo first‐order kinetic model was employed to evaluate the apparent rate constant of the reaction. It was found that the apparent rate constant increased with increasing catalyst dose due to an increase of surface area as a result of an increase in the number of nanoparticles.
Carbon nanotubes‐polymer nanocomposites for controlled heating materials
Authors: Januszko Adam , Peszke Jerzy , Jaworska Urszula , Pawlicka Agnieszka 
Published: August 2016

ABSTRACTNanocomposites of modified carbon nanotubes (CNT) and either polyurethane (PU), poly(vinyl acetate) (PVAc), or silicone materials were synthetized and characterized for thermal mat application. The obtained results revealed that the polymer used as a matrix had an impact on the electrical resistance of the mats. The lowest results of 32 Ω of resistance was registered with silicone‐based mats containing 5 wt % of CNT. For the same CNT content the mats based on PVAc and PU displayed values of 55 and 60 Ω, respectively. The low resistance properties of silicone‐based materials were due principally to the good compatibility of both polymer and functionalized CNT. Because of the low resistance values, this mat was subjected to thermovision analysis revealing that the samples reached temperature of about 60 °C in 9 min and 70 °C after 27 min of 27 V of applied potential. The results showed an almost uniform temperature distribution in the samples’ surface with some high and low temperature spots, which were attributed to nonuniform distribution of CNT in the polymer matrix. In summary, all the obtained results confirm that silicone‐CNT are very promising materials that can be used as low‐voltage heating mats. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 44194.
Dietary habits of polar bears in Foxe Basin, Canada: possible evidence of a trophic regime shift mediated by a new top predator
Authors: Galicia Melissa P. , Thiemann Gregory W. , Dyck Markus G. , Ferguson Steven H. , Higdon Jeff W. 
Published: August 2016

AbstractPolar bear (Ursus maritimus) subpopulations in several areas with seasonal sea ice regimes have shown declines in body condition, reproductive rates, or abundance as a result of declining sea ice habitat. In the Foxe Basin region of Nunavut, Canada, the size of the polar bear subpopulation has remained largely stable over the past 20 years, despite concurrent declines in sea ice habitat. We used fatty acid analysis to examine polar bear feeding habits in Foxe Basin and thus potentially identify ecological factors contributing to population stability. Adipose tissue samples were collected from 103 polar bears harvested during 2010–2012. Polar bear diet composition varied spatially within the region with ringed seal (Pusa hispida) comprising the primary prey in northern and southern Foxe Basin, whereas polar bears in Hudson Strait consumed equal proportions of ringed seal and harp seal (Pagophilus groenlandicus). Walrus (Odobenus rosmarus) consumption was highest in northern Foxe Basin, a trend driven by the ability of adult male bears to capture large‐bodied prey. Importantly, bowhead whale (Balaena mysticetus) contributed to polar bear diets in all areas and all age and sex classes. Bowhead carcasses resulting from killer whale (Orcinus orca) predation and subsistence harvest potentially provide an important supplementary food source for polar bears during the ice‐free period. Our results suggest that the increasing abundance of killer whales and bowhead whales in the region could be indirectly contributing to improved polar bear foraging success despite declining sea ice habitat. However, this indirect interaction between top predators may be temporary if continued sea ice declines eventually severely limit on‐ice feeding opportunities for polar bears.
Geomorphic monitoring and response to two dam removals: rivers Urumea and Leitzaran (Basque Country, Spain)
Authors: Ibisate Askoa , Ollero Alfredo , Ballarín Daniel , Horacio Jesús , Mora Daniel , Mesanza Amaia , Ferrer‐Boix Carles , Acín Vanesa , Granado David , Martín‐Vide Juan Pedro 
Published: August 2016

AbstractDam removal has been demonstrated to be one of the most frequent and effective fluvial restoration actions but at most dam removals, especially of small dams, there has been little geomorphological monitoring. The results of the geomorphological monitoring implemented in two dams in the rivers Urumea and Leitzaran (northern Spain) are presented. The one from the River Urumea, originally 3.5 m high and impounding 500 m of river course, was removed instantaneously whereas that in the River Leitzaran, 12.5 m high, and impounding 1500 m of river course, is in its second phase of a four‐stage removal process. Changes in channel morphology, sediment size and mobility and river bed morphologies were assessed. The monitoring included several different techniques: topographical measurements of the channel, terrestrial laser scanner measurements of river bed and bars, sediment grain size and transport; all of them repeated in four (May, August, November 2011 and May 2012) and five (July and September 2013, April and August 2014 and June 2015) fieldwork campaigns in the River Urumea and River Leitzaran, respectively. Geomorphic responses of both dam removals are presented, and compared. Morphological channel adjustments occurred mainly shortly after dam removals, but with differences among the one removed instantaneously, that was immediate, whereas that conducted by stages took longer. Degradational processes were observed upstream of both dams (up to 1.2 m and 4 m in the River Urumea and River Leitzaran, respectively), but also aggradational processes (pool filling), upstream of Inturia Dam (2.85 m at least). Less evident aggradational processes were observed downstream of the dams (up to 0.37 m and 0.50 m in the River Urumea and River Leitzaran, respectively). Flood events, especially a 100 year flood registered during the monitoring period of Mendaraz Dam removal, reactivated geomorphological processes as incision and bank erosion, whereas longitudinal profile recovery, grain‐size sorting and upstream erosion took longer. Copyright © 2016 John Wiley & Sons, Ltd.
Free water elimination improves test–retest reproducibility of diffusion tensor imaging indices in the brain: A longitudinal multisite study of healthy elderly subjects
Authors: Albi Angela , Pasternak Ofer , Minati Ludovico , Marizzoni Moira , Bartrés‐Faz David , Bargalló Núria , Bosch Beatriz , Rossini Paolo Maria , Marra Camillo , Müller Bernhard , Fiedler Ute , Wiltfang Jens , Roccatagliata Luca , Picco Agnese , Nobili Flavio Mariano , Blin Oliver , Sein Julien , Ranjeva Jean‐Philippe , Didic Mira , Bombois Stephanie , Lopes Renaud , Bordet Régis , Gros‐Dagnac Hélène , Payoux Pierre , Zoccatelli Giada , Alessandrini Franco , Beltramello Alberto , Ferretti Antonio , Caulo Massimo , Aiello Marco , Cavaliere Carlo , Soricelli Andrea , Parnetti Lucilla , Tarducci Roberto , Floridi Piero , Tsolaki Magda , Constantinidis Manos , Drevelegas Antonios , Frisoni Giovanni , Jovicich Jorge ,   The PharmaCog Consortium
Published: August 2016

AbstractFree water elimination (FWE) in brain diffusion MRI has been shown to improve tissue specificity in human white matter characterization both in health and in disease. Relative to the classical diffusion tensor imaging (DTI) model, FWE is also expected to increase sensitivity to microstructural changes in longitudinal studies. However, it is not clear if these two models differ in their test–retest reproducibility. This study compares a bi‐tensor model for FWE with DTI by extending a previous longitudinal‐reproducibility 3T multisite study (10 sites, 7 different scanner models) of 50 healthy elderly participants (55–80 years old) scanned in two sessions at least 1 week apart. We computed the reproducibility of commonly used DTI metrics (FA: fractional anisotropy, MD: mean diffusivity, RD: radial diffusivity, and AXD: axial diffusivity), derived either using a DTI model or a FWE model. The DTI metrics were evaluated over 48 white‐matter regions of the JHU‐ICBM‐DTI‐81 white‐matter labels atlas, and reproducibility errors were assessed. We found that relative to the DTI model, FWE significantly reduced reproducibility errors in most areas tested. In particular, for the FA and MD metrics, there was an average reduction of approximately 1% in the reproducibility error. The reproducibility scores did not significantly differ across sites. This study shows that FWE improves sensitivity and is thus promising for clinical applications, with the potential to identify more subtle changes. The increased reproducibility allows for smaller sample size or shorter trials in studies evaluating biomarkers of disease progression or treatment effects.Hum Brain Mapp 38:12–26, 2017. ©2016 Wiley Periodicals, Inc.
Non‐invasive monitoring of branched Au nanoparticle‐mediated photothermal ablation
Authors: Zhao Ken , Cho Soojeong , Procissi Daniel , Larson Andrew C. , Kim Dong‐Hyun 
Published: August 2016

AbstractNanoparticle‐mediated photothermal therapy for treatment of different types of tumors has attracted tremendous attention in recent years. One major factor that drives this therapy is the ability to carefully control and prevent inadvertent damage to local tissues, while focusing therapeutic heating to specific regions of the tumor tissues. To this end, it is critical to generate efficient heating in the targeted tumors while monitoring the extent and distribution of heating. In our study, we demonstrated the photothermal heating properties of our synthesized branched Au nanoparticles (b‐AuNPs) using non‐invasive MR thermometry (MRT) techniques to assess its effects both in vitro and in vivo. 75 nm b‐AuNPs were synthesized; these b‐AuNPs demonstrated strong near infrared (NIR) absorption and high heat transducing efficiency. Proton resonance frequency MRT approaches for monitoring b‐AuNPs mediated heating were validated using in vitro agar phantoms and further evaluated during in vivo animal model tumor ablation studies. In vitro phantom studies demonstrated a strong linear correlation between MRT and reference‐standard thermocouple measurements of b‐AuNPs‐mediated heating upon NIR laser irradiation; temperatures increased with both an increase in laser power and increased exposure duration. Localized photothermal heating in regions containing the b‐AuNPs was confirmed through MRT generated temperature maps acquired serially at increasing depths during both phantom and in vivo studies. Our results suggested that b‐AuNPs exposed to NIR radiation produced highly efficient localized heating that can be accurately monitored dynamically using non‐invasive MRT measurements. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 105B: 2352–2359, 2017.
Biexponential diffusion alterations in the normal‐appearing white matter of glioma patients might indicate the presence of global vasogenic edema
Authors: Horváth Andrea , Perlaki Gábor , Tóth Arnold , Orsi Gergely , Nagy Szilvia , Dóczi Tamás , Horváth Zsolt , Bogner Péter 
Published: August 2016

PurposeTo investigate normal‐appearing white matter (NAWM) microstructure of glioma patients with biexponential diffusion analysis in order to reveal the nature of diffusion abnormalities and to assess whether they are region‐specific or global.Materials and MethodsTwenty‐four newly diagnosed glioma patients (grade II–IV) and 24 matched control subjects underwent diffusion‐weighted imaging at 3T. Diffusion parameters were calculated using monoexponential and biexponential models. Apparent diffusion coefficient (ADC) values were measured in the entire NAWM of the hemisphere contralateral and ipsilateral to the tumor. In the contralateral NAWM, regional ADC values were assessed in the frontal, parietal, occipital, and temporal NAWM.ResultsADCmono and ADCfast were significantly higher than control values in all investigated regions except the temporal NAWM (P < 0.04). ADCslow was significantly increased in the total contralateral, frontal, and parietal NAWM (P < 0.03), while pslow was decreased in both total hemispheric NAWM and the parietal NAWM of glioma patients compared to controls (P < 0.04). ADCmono, ADCfast, ADCslow, and pslow were significantly different among the NAWM of the four lobes of the contralateral hemisphere in both groups (P < 0.0001), and these regional differences were similar in patients and controls (P > 0.05). Hemispheric ADCmono and pslow differences were different between groups (P < 0.05).ConclusionGlobally altered diffusion parameters suggest the presence of global vasogenic edema in the NAWM of glioma patients, which is further supported by the finding that regional differences in patients follow those found in controls. Alternatively, some tumor infiltration might contribute to diffusion abnormalities in the NAWM, especially in the tumor‐affected hemisphere. J. Magn. Reson. Imaging 2016;44:633–641.