bluuebunny/crossref_metadata_2025 huggingface dataset:
Can we explain the observed methane variability after the Mount Pinatubo eruption?
Authors: Bândă N. , Krol M. , van Weele M. , van Noije T. , Le Sager P. , Röckmann T.
Published: July 2015

Abstract. The CH4 growth rate in the atmosphere showed large variations after the Pinatubo eruption in June 1991. A decrease of more than 10 ppb yr-1 in the growth rate over the course of 1992 was reported and a partial recovery in the following year. Although several reasons have been proposed to explain the evolution of CH4 after the eruption, their contributions to the observed variations are not yet resolved. CH4 is removed from the atmosphere by the reaction with tropospheric OH, which in turn is produced by O3 photolysis under UV radiation. The CH4 removal after the Pinatubo eruption might have been affected by changes in tropospheric UV levels due to the presence of stratospheric SO2 and sulfate aerosols, and due to enhanced ozone depletion on Pinatubo aerosols. The perturbed climate after the eruption also altered both sources and sinks of atmospheric CH4. Furthermore, CH4 concentrations were influenced by other factors of natural variability in that period, such as ENSO and biomass burning events. Emissions of CO, NOX and NMVOCs also affected CH4 concentrations indirectly by influencing tropospheric OH levels. Potential drivers of CH4 variability are investigated using the TM5 global chemistry model. The contribution that each driver had to the global CH4 variability during the period 1990 to 1995 is quantified. We find that a decrease of 8–10 ppb yr-1 CH4 is explained by a combination of the above processes. However, the timing of the minimum growth rate is found 6–9 months later than observed. The long-term decrease in CH4 growth rate over the period 1990 to 1995 is well captured and can be attributed to an increase in OH concentrations over this time period. Potential uncertainties in our modelled CH4 growth rate include emissions of CH4 from wetlands, biomass burning emissions of CH4 and other compounds, biogenic NMVOC and the sensitivity of OH to NMVOC emission changes. Two inventories are used for CH4 emissions from wetlands, ORCHIDEE and LPJ, to investigate the role of uncertainties in these emissions. Although the higher climate sensitivity of ORCHIDEE improves the simulated CH4 growth rate change after Pinatubo, none of the two inventories properly captures the observed CH4 variability in this period.
A process-based model for ammonia emission from urine patches, GAG (Generation of Ammonia from Grazing): description, validation and sensitivity analysis
Authors: Móring A. , Vieno M. , Doherty R. M. , Laubach J. , Taghizadeh-Toosi A. , Sutton M. A.
Published: July 2015

Abstract. In this paper a new process-based, weather-driven model for ammonia (NH3) emission from a urine patch has been developed and its sensitivity to various factors assessed. This model, the GAG model (Generation of Ammonia from Grazing) was developed as a part of a suite of weather-driven NH3 exchange models, as a necessary basis for assessing the effects of climate change on NH3 related atmospheric processes. GAG is capable of simulating the TAN (Total Ammoniacal Nitrogen) content, pH and the water content of the soil under a urine patch. To calculate the TAN budget, GAG takes into account urea hydrolysis as a TAN input and NH3 volatilization as a loss. In the water budget, in addition to the water content of urine, precipitation and evaporation are also considered. In the pH module we assumed that the main regulating processes are the dissociation and dissolution equilibria related to the two products of urea hydrolysis: ammonium and bicarbonate. Finally, in the NH3 exchange flux calculation we adapted a canopy compensation point model that accounts for exchange with soil pores and stomata as well as deposition to the leaf surface. We validated our model against measurements, and carried out a sensitivity analysis. The validation showed that the simulated parameters (NH3 exchange flux, soil pH, TAN budget and water budget) are well captured by the model (r > 0.5 for every parameter at p < 0.01 significance level). We found that process-based modelling of pH is necessary to reproduce the temporal development of NH3 emission. In addition, our results suggested that more sophisticated simulation of CO2 emission in the model could potentially improve the modelling of pH. The sensitivity analysis highlighted the vital role of temperature in NH3 exchange; however, presumably due to the TAN limitation, the GAG model currently provides only a modest overall temperature dependence in total NH3 emission compared with the values in the literature. Since all the input parameters can be obtained for study at larger scales, GAG is potentially suitable for larger scale application, such as in regional atmospheric and ecosystem models.
Modeling micro-topographic controls on boreal peatland hydrology and methane fluxes
Authors: Cresto Aleina F. , Runkle B. R. K. , Kleinen T. , Kutzbach L. , Schneider J. , Brovkin V.
Published: July 2015

Abstract. Small-scale surface heterogeneities can influence land–atmosphere fluxes and therefore carbon, water and energy budgets on larger scale. This effect is of particular relevance for high-latitude ecosystems, because of the great amount of carbon stored in their soils. We introduce a novel micro-topographic model, the Hummock–Hollow (HH) model, which explicitly represents small-scale surface elevation changes. By computing the water table at the small scale, and by coupling the model with a process-based model for soil methane processes, we are able to model effects of micro-topography on hydrology and methane emissions in a typical boreal peatland. In order to assess the effect of micro-topography on water balance and methane emissions of the peatland we compare two versions of the model, one with a representation of micro-topography and a classical single-bucket model version, and show that the temporal variability in the model version with micro-topography performs better if compared with local data. Accounting for micro-topography almost triples the cumulative methane flux over the simulated time-slice. We found that the single-bucket model underestimates methane emissions because of its poor performance in representing hydrological dynamics. The HH model with micro-topography captures the spatial dynamics of water and methane fluxes, being able to identify the hotspots for methane emissions. The model also identifies a critical scale (0.01 km2) which marks the minimal resolution for the explicit representation of micro-topography in larger-scale models.
Co-occurrence patterns in aquatic bacterial communities across changing permafrost landscapes
Authors: Comte J. , Lovejoy C. , Crevecoeur S. , F. Vincent W.
Published: July 2015

Abstract. Permafrost thaw ponds and lakes are widespread across the northern landscape and may play a central role in global biogeochemical cycles, yet knowledge about their microbial ecology is limited. We sampled a set of thaw ponds and lakes as well as shallow rock-basin lakes that are located in distinct valleys along a North–South permafrost degradation gradient. We applied high-throughput sequencing of the 16S rRNA gene to determine co-occurrence patterns among bacterial taxa, and then analyzed these results relative to environmental variables to identify factors controlling bacterial community structure. Network analysis was applied to identify possible ecological linkages among the bacterial taxa and with abiotic and biotic variables. The results showed an overall high level of shared taxa among bacterial communities within each valley, however the bacterial co-occurrence patterns were non-random, with evidence of habitat preferences. There were taxonomic differences in bacterial assemblages among the different valleys that were statistically related to dissolved organic carbon concentration, conductivity and phytoplankton biomass. Co-occurrence networks revealed complex interdependencies within the bacterioplankton communities and showed contrasting linkages to environmental conditions among the main bacterial phyla. The thaw pond networks were composed of a limited number of highly connected taxa. This "small world network" property would render the communities more robust to environmental change but vulnerable to the loss of microbial keystone species.
Reviews and Syntheses: Effects of permafrost thaw on arctic aquatic ecosystems
Authors: Vonk J. E. , Tank S. E. , Bowden W. B. , Laurion I. , Vincent W. F. , Alekseychik P. , Amyot M. , Billet M. F. , Canário J. , Cory R. M. , Deshpande B. N. , Helbig M. , Jammet M. , Karlsson J. , Larouche J. , MacMillan G. , Rautio M. , Walter Anthony K. M. , Wickland K. P.
Published: July 2015

Abstract. The Arctic is a water-rich region, with freshwater systems covering 16 % of the northern permafrost landscape. The thawing of this permafrost creates new freshwater ecosystems, while at the same time modifying the existing lakes, streams, and rivers that are impacted by thaw. Here, we describe the current state of knowledge regarding how permafrost thaw affects lentic and lotic systems, exploring the effects of both thermokarst (thawing and collapse of ice-rich permafrost) and deepening of the active layer (the surface soil layer that thaws and refreezes each year). Within thermokarst, we further differentiate between the effects of thermokarst in lowland areas, vs. that on hillslopes. For almost all of the processes that we explore, the effects of thaw vary regionally, and between lake and stream systems. Much of this regional variation is caused by differences in ground ice content, topography, soil type, and permafrost coverage. Together, these modifying variables determine the degree to which permafrost thaw manifests as thermokarst, whether thermokarst leads to slumping or the formation of thermokarst lakes, and the manner in which constituent delivery to freshwater systems is altered by thaw. Differences in thaw-enabled constituent delivery can be considerable, with these modifying variables determining, for example, the balance between delivery of particulate vs. dissolved constituents, and inorganic vs. organic materials. Changes in the composition of thaw-impacted waters, coupled with changes in lake morphology, can strongly affect the physical and optical properties of thermokarst lakes. The ecology of thaw-impacted systems is also likely to change, with thaw-impacted lakes and streams having unique microbiological communities, and showing differences in respiration, primary production, and food web structure that are largely driven by differences in sediment, dissolved organic matter and nutrient delivery. The degree to which thaw enables the delivery of dissolved vs. particulate organic matter, coupled with the composition of that organic matter and the morphology and stratification characteristics of recipient systems will play an important role in determining the balance between the release of organic matter as greenhouse gases (CO2 and CH4), its burial in sediments, and its loss downstream. The magnitude of thaw impacts on northern aquatic ecosystems is increasing, as is the prevalence of thaw-impacted lakes and streams. There is therefore an urgent need to address the key gaps in understanding in order to predict the full effects of permafrost thaw on aquatic ecosystems throughout the Arctic, and their consequential feedbacks to climate.
Comparing models of microbial-substrate interactions and their response to warming
Authors: Sihi D. , Gerber S. , Inglett P. W. , Inglett K. S.
Published: July 2015

Abstract. Recent developments in modelling soil organic carbon decomposition include the explicit incorporation of enzyme and microbial dynamics. A characteristic of these models is a positive feedback between substrate and consumers which is absent in traditional first order decay models. Under sufficient large substrate, this new feedback allows an unconstrained growth of microbial biomass. A second phenomenon incorporated in the microbial decomposition models is decreased carbon use efficiency (CUE) with increasing temperature. Here, first we analyse microbial decomposition models by parameterising changes in CUE based on the differentiation between growth and maintenance respiration. We then explore mechanisms that curb unrestricted microbial growth by including finite potential sites where enzymes can bind and by allowing microbial scavenging for enzymes. Finally, we propose a model where enzyme synthesis is associated with a respiratory cost and microbial population adjusts enzyme production in order to optimise their growth. When applying a step increase in temperature, we find fast responses that reflect adjustments to enzyme dynamics and maintenance respiration, a short-term adjustment in microbial growth, and the long-term change in carbon storage. We find that mechanisms that prevent unrestricted microbial growth lead to a similar response to warming as traditional first order decomposition models.
Assessment of environmental soil quality around Sonepur Bazari mine of Raniganj coalfield, India
Authors: Masto R. E. , Sheik S. , Nehru G. , Selvi V. A. , George J. , Ram L. C.
Published: July 2015

Abstract. Assessment of soil quality is one of the key parameters for evaluation of environmental contamination in the mining ecosystem. To investigate the effect of coal mining on soil quality, opencast and underground mining sites were selected in the Raniganj coalfield area, India. The physical, chemical, and biological parameters of the soils, and trace metals and PAHs (polycyclic aromatic hydrocarbons) in the soils were evaluated. Soil dehydrogenase (+79 %) and fluorescein (+32 %) activities were significantly higher in underground mine (UGM) soil, whereas peroxidase activity (+57 %) was higher in opencast mine (OCM) soil. Content of As, Be, Co, Cr, Cu, Mn, Ni, and Pb was significantly higher in OCM soil, whereas Cd was higher in UGM. In general, the PAHs contents were higher in UGM soils, probably due to the natural coal burning at these sites. The observed values for the above properties were converted into a unitless score (0–1.00) and the scores were integrated into an environmental soil quality index (ESQI). In the unscreened index (ESQI-1) all the soil parameters were included and the results showed that the quality of the soil was better for UGM (0.539) than the OCM (0.511) soils. Principal component analysis was employed to derive ESQI-2 and accordingly, total PAHs, loss on ignition, bulk density, Be, Co, Cr, Ni, Pb, and microbial quotient (respiration: microbial biomass ratio) were found to be the most critical properties. The ESQI-2 was also higher for soils near UGM (+10.1 %). The observed indicators and the ESQI results revealed that soil quality assessment for these coal mining soils is largely depended on soil PAHs and potentially toxic trace metals. The proposed ESQI may be further refined by incorporating specific parameters related to human exposure risks and exposure pathways.
Ecoturismo en comunidades rurales: análisis de los impactos negativos para la población local. Un estudio de caso
Authors: Orgaz-Agüera Francisco , Cañero Morales Pablo
Published: July 2015

En los últimos años han aparecido nuevas formas de turismo más sostenibles, donde existen elementos relacionados con el descanso, el disfrute y la protección del medio ambiente o el conocimiento de la cultura local, a través de políticas que favorecen la sostenibilidad del destino. En este sentido, el ecoturismo se configura como una tipología turística que se desarrolla en contacto con la naturaleza. Este turismo ayuda a mejorar el desarrollo socioeconómico de las comunidades locales, a la vez, que fomenta la conservación de los recursos naturales y el respeto hacia el medio ambiente. Aunque, esta tipología de turismo también genera importantes impactos negativos. El objetivo principal de esta investigación es analizar los impactos socioeconómicos, culturales y medioambientales percibidos por el ecoturismo por parte de los residentes de comunidades rurales de República Dominicana. La técnica de recolección de datos utilizada ha consistido en un cuestionario. Entre las principales conclusiones, cabe destacar que actualmente no se perciben impactos negativos, pero si hay una serie de elementos que hay que ir considerando, con la finalidad de que no se conviertan en un impacto a corto plazo para la comunidad rural.
With or without you: Connected viewing and co-viewing Twitter activity for traditional appointment and asynchronous broadcast television models
Authors: Pittman Matthew , Tefertiller Alec C.
Published: July 2015

Social networking services like Twitter have changed the way people engage with traditional broadcast media. But how social is “second screen” activity? The purpose of this study is to determine if patterns of connected viewing (augmenting television consumption with a second screen) and co-viewing (watching television together) are different for traditionally broadcast, “appointment” television shows versus streaming, asynchronous television releases. This study explores this phenomena of “co-connected viewing” — a combination of connected and co-viewing — on Twitter for four programs that were all released within seven days of each other: Parks and Recreation, Downton Abbey, House of Cards, and Unbreakable Kimmy Schmidt. Complete datasets (over 200,000 tweets) from 72 hours’ worth of Twitter activity for four television programs, two traditional and two streaming, were collected and analyzed. In terms of co-connected viewing, the study found that despite radically different broadcast models and corresponding shapes in Twitter activity, the ratios of social to non-social tweets were nearly identical. Additionally, the study found that the asynchronous, streaming Netflix shows saw more engagement from active Twitter users. Finally, implications are discussed for viewers, fans, advertisers, and the television industry, as well as directions for future research.
YouTube pranking across cultures
Authors: Hobbs Renee , Grafe Silke
Published: July 2015

Online pranking videos are common online and popular among middle-school students, teens and young adults. When we examined 200 YouTube examples of the Scary Maze Game prank, we explored the relationship between perpetrator, victim and witness, finding that while American children under age 12 were commonly featured as victims in Scary Maze Game prank videos, only rarely were German children represented as victims. U.S. videos also lingered on the pain of prank victims, even looping the emotional response of the victim to create an instant replay effect and using post-production techniques, including editing, music and title credits. As an expression of the schadenfreude that people experience when both enacting and viewing bad pranks, online pranking is a dimension of the dark side of participatory culture.
Exchange Rate Pass-Through to Import Prices, Inflation and Monetary Policy in Nigeria
Authors: Fatai M. O. , Akinbobola T. O.
Published: July 2015

The study investigates the impact of Exchange Rate Pass-through (ERPT) to import prices, Inflation, and monetary policy in Nigeria. Secondary data were used. The data covered the period of 1986-2012. Annual data on Nominal Effective Exchange Rate Index (NEER), Import Prices (IMP), Interest Rate (ITR), Money Supply (MS) and Inflation (INF) were sourced from the publication of the Central Bank of Nigeria (CBN) and Oil Price Index (OPI) were sourced from the World Development Indicators (WDI) published by the World Bank. The study applied Six-Variable VAR Model to estimate the Impulse Response Function (IRFs) and Variance Decomposition (VDCs). Based on SVAR analysis the study found that ERPT in Nigeria during the period under review is moderate, significant and persistent in the case of import prices and low and short lived in the case of inflation. The fact is that, ERPT was found to be incomplete and has useful implication to policymakers, especially in the design and implementation of exchange rate and monetary policy. Thus policy makers should take into account the incomplete response of import prices when they decide to devalue the currency so as to improve trade balance irrespective of several other factors which might determine the effectiveness of exchange rate policy (such as supply factors, elasticity of foreign and domestic demand, availability of substitutes etc ). To achieve this, the increased role of CBN will definitely require a carefully developed monetary policy and a strengthening of its institutional capacity.
Agency Cost in India Banks
Authors: Acharya Sanjeev , Dupatti Geeta , Locke Stuart
Published: July 2015

Agency cost in Indian banks for the period 2005 to 2013, covering pre-financial crisis, crisis and post-crisis period is empirically examined in the article. It is found that the agency costs, using two measures, vary from one bank to another and change over time. The likelihood of agency cost differing between types of banks indicates that there is a low level of consistency in the results. The choice of metric used is observed to be important as different measures produce different results. The findings also indicate there is low time invariance with respect to agency costs. The source of the agency cost is attributed, at least in part, to the governance of banks during the period analysed.
Thirty Years of Sense-Making: Richard Schacht's Nietzsche in Germany
Authors: Heit Helmut
Published: July 2015

In this article, I investigate the reception of Richard Schacht's Nietzsche in Germany. Despite the fact that his later work was widely acknowledged in Germany, his 1983 monograph did not receive much attention. I suggest that this is due in part to the significantly differing landscapes in the United States and in Germany during the 1980s and in part to different methodological approaches. Schacht's incentive to introduce Nietzsche to an analytically minded and generally quite hostile American audience by means of extracting his arguments, not the least through extensive use of The Will to Power, did not contribute much to the contemporary focus of the founders of Nietzsche-Studien, who aimed to establish a professionalized reconstructive Nietzsche-research based on the critical edition of Colli and Montinari. However, in my concluding remarks I argue that Schacht's balancing approach and his notion of discourse-relative truth might serve intercontinental dispute about Nietzsche better than some currently more striking alternatives.
On Richard Schacht's Nietzsche
Authors: Richardson John
Published: July 2015

Schacht's 1983 book remains a valuable resource for thinking philosophically about Nietzsche. In this article, I examine the book's treatment of two fundamental interpretive issues regarding (respectively) how Nietzsche values, and what he values. I argue that Schacht misinterprets Nietzsche as a value realist, by failing to see that Nietzsche means his descriptive use of value to refer not to “so-called values,” but to genuine or full-fledged values. Moral values are just as much values as Nietzsche's own. And regarding Nietzsche's own values, I argue here for a different relation among the values of affirmation, power, and truth than the one Schacht attributes to them.
Genealogy and the Structure of Interpretation
Authors: Prescott-Couch Alexander
Published: July 2015

In this article, I consider how Nietzsche's history of morality in On the Genealogy of Morality is relevant to his critique of morality. I argue that, on Nietzsche's view, morality's history is a guide to whether and where we should expect to find coherence in our current moral practice. It helps us “structure our interpretation” of morality. History is relevant to critique because it reveals that morality is unlikely to have the kind of coherence required by many of its defenders. After defending this account of how Nietzsche's historical claims are relevant to his critique, I use the account to explain why Nietzsche's genealogy mixes fact and fiction.
Palabras del Rector de la Universidad de Chile, Doctor Ennio Vivaldi Vejar
Authors: Vivaldi Véjar Ennio
Published: July 2015

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Hidrelétrica de Belo Monte e o município de Altamira: processo de mudança social ou morfogênese?
Authors: Vidal Josep Pont
Published: July 2015

A construção da mega Hidrelétrica de Belo Monte comporta impactos em toda a região do Xingu (estado do Pará). Este artigo descreve a primeira fase de observação realizada no município de Altamira durante o espaço temporal compreendido entre os anos de 2011 a 2013. Com base em uma perspectiva sociológica proveniente da teoria de sistemas sociais complexos, nesta fase, são observadas as transformações que estão ocorrendo no sistema administrativo do município, assim como os primeiros resultados da observação das dinâmicas de mudança e diferenciação. Esta observação é feita  em dois níveis. O primeiro focaliza as políticas públicas como formas comunicativas, e o segundo, as estruturas que compõem o sistema político-administrativo.
Convivência com o semiárido: nas fronteiras entre o novo que se legitima e o antigo que teima em ficar
Authors: Neto Mariana Moreira
Published: July 2015

Este artigo analisa como o discurso da convivência com o semiárido é compreendido e ressignificado no contexto da vivência de entidades, organizações e agricultores do Alto Sertão Paraibano que trabalham com esta ideia, buscando apreender quais associações são estabelecidas entre convivência, desenvolvimento sustentável, sertão, autonomia e assujeitamento. Apreende-se que o discurso da convivência está entrelaçado a um diálogo conflituoso entre discursos, com outros olhares que, muitas vezes, acabam restringindo suas fronteiras, intervindo em suas ações e alterando o curso de sua institucionalização.
« Les animaux obéissent aussi à la religion »
Authors: Crépeau Robert R.
Published: July 2015

La récente Cambridge Declaration on Conciousness, de juillet 2012, qui affirme que les animaux sont dotés de conscience et de la capacité de comportements intentionnels, relance à nouveau la question : qu’est-ce que l’espèce humaine possède de spécifique ? Cette contribution explore la conception amérindienne de la condition animale en s’attardant à celle des Kaingang du Brésil, et plus particulièrement à leur concept de maîtres des animaux. La relation des humains au monde animal et végétal est pensée et agie par les Kaingang comme s’inscrivant dans une hiérarchie de puissances, plus précisément de confrontation et/ou de mise en commun des forces ou des puissances tant humaines que non-humaines par l’intermédiaire des entités-maîtres. Ce dernier concept est lié à une conception largement répandue dans les Amériques. L’article propose en conclusion une brève analyse comparative de ce concept à partir de quelques cas sud-américains.
L'exotisme et le fruit de l'imagination
Authors: Mariani Léo
Published: July 2015

Il est ici question du durian, un fruit particulièrement prisé en Asie du Sud-Est mais dont l’odeur fait l’objet de descriptions pour le moins univoques de la part des Occidentaux (odeur de cadavre, odeur de putréfaction, etc.). Comme l’observe l’anthropologue Jacques Dournes, c’est un fait bien établi que le durian « partage l’humanité en deux ». Plutôt que d’expliquer cette différence, comme il est d’usage, par l’existence d’un « long apprentissage culturel », je m’attache à replacer dans cet article le-durian-qui-partage-l’humanité-en-deux dans le jeu beaucoup plus complexe de rapports tout à la fois culturels, sociaux, cognitifs et historiques qui le font advenir.
Impact of geolocations of validation data on the evaluation of surface incident shortwave radiation from Earth System Models
Authors: Ma Qian , Wang Kaicun , Wild Martin
Published: July 2015

Ground‐based observations of surface incident solar radiation (Rs) have been used to evaluate simulations of global climate models. Existing studies have shown that biases in simulated clouds have a significant spatial pattern, which may be transferred to the simulated Rs. Therefore, the evaluation results of Rs simulations may depend on the locations of the ground‐based observations. In this study, Rs simulations of 48 models participating in the fifth phase of the Coupled Model Intercomparison Project (CMIP5) were first evaluated with ground‐based observations from different networks (446 stations in total) from 2000 to 2005. The global mean biases of the CMIP5 Rs simulations were found to vary from 4.8 to 11.9 W m−2 when Rs observations from different networks were used as reference data. To reduce the location impact on the evaluation results, CMIP5 simulated Rs was then evaluated with the latest satellite Rs retrieval at 1° × 1° spatial resolution by the Clouds and the Earth's Radiant Energy System, Energy Balanced and Filled (CERES EBAF). It was found that the CMIP5 simulated multimodel mean Rs has a small bias of 2.6 W m−2 compared with CERES EBAF over the globe, 4.7 W m−2 and 1.7 W m−2 over land and oceans, respectively. CERES EBAF Rs was found to have a positive bias of 1.3 W m−2 compared with ground‐based observations. After removing this bias of CERES EBAF Rs, global mean Rs was estimated to be 185 W m−2.
Multimodel analysis of anisotropic diffusive tracer‐gas transport in a deep arid unsaturated zone
Authors: Green Christopher T. , Walvoord Michelle A. , Andraski Brian J. , Striegl Robert G. , Stonestrom David A.
Published: July 2015

Gas transport in the unsaturated zone affects contaminant flux and remediation, interpretation of groundwater travel times from atmospheric tracers, and mass budgets of environmentally important gases. Although unsaturated zone transport of gases is commonly treated as dominated by diffusion, the characteristics of transport in deep layered sediments remain uncertain. In this study, we use a multimodel approach to analyze results of a gas‐tracer (SF6) test to clarify characteristics of gas transport in deep unsaturated alluvium. Thirty‐five separate models with distinct diffusivity structures were calibrated to the tracer‐test data and were compared on the basis of Akaike Information Criteria estimates of posterior model probability. Models included analytical and numerical solutions. Analytical models provided estimates of bulk‐scale apparent diffusivities at the scale of tens of meters. Numerical models provided information on local‐scale diffusivities and feasible lithological features producing the observed tracer breakthrough curves. The combined approaches indicate significant anisotropy of bulk‐scale diffusivity, likely associated with high‐diffusivity layers. Both approaches indicated that diffusivities in some intervals were greater than expected from standard models relating porosity to diffusivity. High apparent diffusivities and anisotropic diffusivity structures were consistent with previous observations at the study site of rapid lateral transport and limited vertical spreading of gas‐phase contaminants. Additional processes such as advective oscillations may be involved. These results indicate that gases in deep, layered unsaturated zone sediments can spread laterally more quickly, and produce higher peak concentrations, than predicted by homogeneous, isotropic diffusion models.
Four‐dimensional electrical conductivity monitoring of stage‐driven river water intrusion: Accounting for water table effects using a transient mesh boundary and conditional inversion constraints
Authors: Johnson Tim , Versteeg Roelof , Thomle Jon , Hammond Glenn , Chen Xingyuan , Zachara John
Published: July 2015

This paper describes and demonstrates two methods of providing a priori information to the surface‐based time‐lapse three‐dimensional electrical resistivity tomography (ERT) problem for monitoring stage‐driven or tide‐driven surface water intrusion into aquifers. First, a mesh boundary is implemented that conforms to the known location of the water table through time, thereby enabling the inversion to place a sharp bulk conductivity contrast at that boundary without penalty. Second, a nonlinear inequality constraint is used to allow only positive or negative transient changes in EC to occur within the saturated zone, dependent on the relative contrast in fluid electrical conductivity between surface water and groundwater. A 3‐D field experiment demonstrates that time‐lapse imaging results using traditional smoothness constraints are unable to delineate river water intrusion. The water table and inequality constraints provide the inversion with the additional information necessary to resolve the spatial extent of river water intrusion through time.
General mechanism and dynamics of the solar wind interaction with lunar magnetic anomalies from 3‐D particle‐in‐cell simulations
Authors: Deca Jan , Divin Andrey , Lembège Bertrand , Horányi Mihály , Markidis Stefano , Lapenta Giovanni
Published: July 2015

We present a general model of the solar wind interaction with a dipolar lunar crustal magnetic anomaly (LMA) using three‐dimensional full‐kinetic and electromagnetic simulations. We confirm that LMAs may indeed be strong enough to stand off the solar wind from directly impacting the lunar surface, forming a so‐called “minimagnetosphere,” as suggested by spacecraft observations and theory. We show that the LMA configuration is driven by electron motion because its scale size is small with respect to the gyroradius of the solar wind ions. We identify a population of back‐streaming ions, the deflection of magnetized electrons via the E × B drift motion, and the subsequent formation of a halo region of elevated density around the dipole source. Finally, it is shown that the presence and efficiency of the processes are heavily impacted by the upstream plasma conditions and, on their turn, influence the overall structure and evolution of the LMA system. Understanding the detailed physics of the solar wind interaction with LMAs, including magnetic shielding, particle dynamics and surface charging is vital to evaluate its implications for lunar exploration.
The near‐global mesospheric potassium layer: Observations and modeling
Authors: Dawkins E. C. M. , Plane J. M. C. , Chipperfield M. P. , Feng W.
Published: July 2015

The meteoric metal layers act as unique tracers of chemistry and dynamics in the upper atmosphere. Existing lidar studies from a few locations show that K exhibits a semiannual seasonality (winter and summer maxima), quite unlike the annual seasonality (winter maximum and summer minimum) seen with Na and Fe. This work uses spaceborne observations made with the Optical Spectrograph and InfraRed Imager System instrument on the Odin satellite to retrieve the near‐global K layer for the first time. The satellite data (2004 to mid‐2013) are used to validate the implementation of a recently proposed potassium chemistry scheme in a whole atmosphere chemistry climate model, which provides a chemical basis for this semiannual seasonal behavior. The satellite and model data show that this semiannual seasonality is near global in extent, with the strongest variation at middle and high latitudes. The column abundance, centroid layer height, and root‐mean‐square width of the K layer are consistent with the limited available lidar record. The K data set is then used to investigate the impact of polar mesospheric clouds on the metal layers at high latitudes during summer. Finally, the occurrence frequency of sporadic K layers and their possible link to sporadic E layers are examined.
Kinetic energy‐conserving hyperdiffusion can improve low resolution atmospheric models
Authors: Zurita‐Gotor Pablo , Held Isaac M. , Jansen Malte F.
Published: July 2015

Motivated by findings that energetically consistent subgrid dissipation schemes can improve eddy‐permitting ocean simulations, this work investigates the impact of the subgrid dissipation scheme on low‐resolution atmospheric dynamical cores. A kinetic energy‐conserving dissipation scheme is implemented in the model adding a negative viscosity term that injects back into the eddy field the kinetic energy dissipated by horizontal hyperdiffusion. The kinetic energy‐conserving scheme enhances numerical convergence when horizontal resolution is changed with fixed vertical resolution and gives superior low‐resolution results. Improvements are most obvious for eddy kinetic energy but also found in other fields, particularly with strong or little scale‐selective horizontal hyperdiffusion. One advantage of the kinetic energy‐conserving scheme is that it reduces the sensitivity of the model to changes in the subgrid dissipation rate, providing more robust results.
Plasmonic‐Induced Photon Recycling in Metal Halide Perovskite Solar Cells
Authors: Saliba Michael , Zhang Wei , Burlakov Victor M. , Stranks Samuel D. , Sun Yao , Ball James M. , Johnston Michael B. , Goriely Alain , Wiesner Ulrich , Snaith Henry J.
Published: July 2015

Organic–inorganic metal halide perovskite solar cells have emerged in the past few years to promise highly efficient photovoltaic devices at low costs. Here, temperature‐sensitive core–shell Ag@TiO2 nanoparticles are successfully incorporated into perovskite solar cells through a low‐temperature processing route, boosting the measured device efficiencies up to 16.3%. Experimental evidence is shown and a theoretical model is developed which predicts that the presence of highly polarizable nanoparticles enhances the radiative decay of excitons and increases the reabsorption of emitted radiation, representing a novel photon recycling scheme. The work elucidates the complicated subtle interactions between light and matter in plasmonic photovoltaic composites. Photonic and plasmonic schemes such as this may help to move highly efficient perovskite solar cells closer to the theoretical limiting efficiencies.
Allergen stability of testing/treatment boards and immunotherapy vials with various diluents
Authors: Nida Andrew , Leatherman Bryan , Plunkett Greg , Mire Brad
Published: July 2015

Background

Otolaryngologists commonly use glycerin and normal saline with phenol (NSP) in diluting solutions to help preserve allergenicity in immunotherapy vials. Studies have shown that diluting with human serum albumin (HSA) may provide better allergen stability. The purpose of this study was to assess the ability of various diluents to preserve allergen content in testing/treatment boards (TTBs) and immunotherapy treatment vials (ITVs) at multiple time points.

Methods

TTBs with 4 allergens were prepared with HSA, NSP, 10% glycerin, and 50% glycerin. The major allergen content of the TTBs was measured at creation (time 0), 3 days, 8 weeks, and 18 weeks. Multiallergen ITVs containing the 4 allergens were prepared from the NSP board (diluted to 10% glycerin) and the HSA board (diluted in HSA) at the time of making the freshly prepared TTBs and again 8 weeks later, simulating the creation of ITVs from a “new” and an “old” TTB. The major allergen content of these ITVs was determined at creation and at interval time points thereafter.

Results

TTBs and ITVs showed a substantial loss of allergen at day 3. The loss of allergen was more pronounced in the more dilute (#4, #5, and #6) vials. HSA and 50% glycerin showed superior allergen preservation compared to NSP and 10% glycerin in TTBs. HSA showed superior allergen preservation compared to 10% glycerin‐NSP in ITVs.

Conclusion

The use of HSA as a diluent in TTBs and ITVs showed superior allergen preservation compared to NSP and 10% glycerin, particularly for more dilute vials.
Study on the properties of polyethylene/montmorillonite nanocomposites prepared by a novel vane mixer
Authors: Huang Zhao‐Xia , Zhou Li‐Ying , Zhang Gui‐Zhen , Qu Jin‐Ping , He He‐Zhi
Published: July 2015

A novel mixer‐vane mixer which is based on elongation flow was used to prepare high‐density polyethylene (HDPE)/montmorillonite (MMT) nanocomposites without any additives. The effect of elongation flow on MMT intercalating in HDPE matrix was studied in terms of rotor speed and mixing time. X‐ray diffraction and transmission electron microscope analyses showed that exfoliated and intercalated nanostructures were obtained when the rotor speed was 40 and 50 rpm, and mixing time was 6 minutes. For all samples prepared by vane mixer, MMT layers showed fine intercalation in the nanocomposites. Differential scanning calorimetry and thermogravimetric analysis were used to study the thermal properties of the nanocomposites. The results showed that the addition of MMT can improve the crystallization of the HDPE. Tensile test revealed the relationships between the mechanical properties and process parameters. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42600.
Characterization of polyhydroxyalkanoate blends incorporating unpurified biosustainably produced poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate)
Authors: Martínez‐Abad Antonio , Cabedo Luis , Oliveira Catarina S. S. , Hilliou Loic , Reis Maria , Lagarón José María
Published: July 2015

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) produced by mixed bacterial cultures derived from a cheese whey (CW) industrial by‐product (unpurified PHBV; u‐PHBV) was incorporated into commercial PHBV without previous purification or isolation processes. The presence of certain impurities was evident as investigated by scanning electron microscopy. The crystallinity of the polymer fraction was decreased by about 3% compared to the commercial PHBV. The onset of thermal degradation was not substantially affected by the incorporation of the u‐PHBV fraction. A higher flexibility and elongation at break was mostly attributed to the increased contents in 3‐hydroxyvalerate in the blends with increasing u‐PHBV content. Water and D‐limonene vapor permeability were not affected up to u‐PHBV contents of 15 wt %. This study puts forth the potential use of unpurified PHBV obtained from mixed microbial cultures and grown from industrial by‐products as a cost‐effective additive to develop more affordable and waste valorized packaging articles. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42633.
Physicochemical characterization of lignin recovered from microwave‐assisted delignified lignocellulosic biomass for use in biobased materials
Authors: Xie Jiulong , Hse Chung‐Yun , Shupe Todd F. , Hu Tingxing
Published: July 2015

Lignocellulosic biomass (Moso Bamboo, Chinese tallow tree wood, switchgrass, and pine wood) was subjected to a novel delignification process using microwave energy in a binary glycerol/methanol solvent. The physicochemical properties of the recovered lignin were analyzed prior to its application in the fabrication of polylactic acid (PLA)–lignin composites. The results showed that the samples had a high Klason lignin content (>75%) and retained their natural structure. Thermogravimetric analysis revealed that the recovered lignin exhibited a different thermal decomposition pattern from that of commercial lignins. All the recovered lignins had good solubility in common organic solvents (acetone, 1,4‐dioxane, THF, DMSO, and ethanol/water) and 1 mol/L NaOH solution. The addition of lignin into the PLA matrix resulted in the improvement in tensile properties of PLA–lignin composites. PLA films with low lignin content had good UV light‐resistant properties, indicating that the recovered lignin has potential in packaging of light‐sensitive products. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42635.
Faulty Plant Reconfiguration Based on Disturbance Decoupling Methods
Authors: Kaldmäe A. , Kotta Ü. , Jiang B. , Shumsky A. , Zhirabok A.
Published: July 2015

The disturbance decoupling problem by dynamic measurement feedback (DDDPM) for discrete‐time nonlinear control systems is considered in this paper. The mathematical approach known under the name “the algebra of functions” is used to derive an algorithm that finds, whenever possible, a measurement feedback which solves the DDDPM. Finally, the applicability of the DDDPM in fault tolerant control (FTC) is discussed.
Molecular Modeling and Simulation in Fluid Process Engineering
Authors: Horsch Martin , Hasse Hans
Published: July 2015

Molecular simulation has reached a high degree of versatility due to the advance of massively‐parallel high performance computing. On the basis of physically realistic models of the intermolecular interactions, thermodynamic properties can be described and predicted with a high accuracy. Transport processes and heterogeneous systems can today be reliably simulated as well. This requires robust molecular models and simulation methods with a rigorous foundation on statistical mechanics. The state of the art is discussed here with a focus on applications in process engineering.
Safety and clinical effectiveness of drug‐eluting stents for saphenous vein graft intervention in older individuals: Results from the medicare‐linked National Cardiovascular Data Registry® CathPCI Registry® (2005–2009)
Authors: Brennan J. Matthew , Sketch Michael H. , Dai David , Trilesskaya Marina , Al‐Hejily Wesam , Rao Sunil V. , Brilakis Emmanouil , Messenger John C. , Shaw Richard E. , Anstrom Kevin J. , Peterson Eric D. , Douglas Pamela S.
Published: July 2015

Objectives

To evaluate the safety of drug‐eluting stents (DES) when treating patients with failing saphenous vein grafts (SVG).

Background

DES reduce target vessel revascularization in patients with failing SVGs; however, compared with bare metal stents (BMS), DES have been variably associated with increased mortality.

Methods

Clinical records from National Cardiovascular Data Registry® CathPCI Registry® (49,325 older individuals [≥65 years] who underwent SVG stenting 2005–2009) were linked to Medicare claims to create a longitudinal record. Death, myocardial infarction (MI), and urgent revascularization with DES versus BMS were evaluated to 3 years using propensity matching (PM). Results were stratified by clinical presentation (acute coronary syndrome [ACS], non‐ACS), previous lesion treatment (in‐stent, de novo), and graft segment (aortic, body, distal anastomosis).

Results

In this older cohort (median age, 75 years), acute presentations were prevalent (ACS, 69%; TIMI flow <3, 45%), and adverse clinical outcomes were common by 3 years (death, 24.5%; MI, 14.6%; urgent revascularization, 29.5%). Among DES patients (n = 31,403), 3‐year mortality was lower (vs. BMS) (22.7% vs. 28.0%, P < 0.001; PM hazard ratio [HR] 0.87, 95% confidence interval 0.83–0.91), and no difference was observed in the adjusted risk for MI (PM HR 0.97, 0.91 to 1.03) or urgent revascularization (PM HR 1.04, 0.99–1.08). These findings were independent of clinical presentation, previous lesion treatment, and graft segment (P interaction, ns).

Conclusions

In this large SVG PCI cohort, all‐cause mortality was lower among those receiving DES, and no difference in MI or urgent revascularization was observed to 3 years. © 2015 Wiley Periodicals, Inc.