bluuebunny/crossref_metadata_2025 huggingface dataset:
Inverse modelling of cloud-aerosol interactions – Part 2: Sensitivity tests on liquid phase clouds using a Markov chain Monte Carlo based simulation approach
Authors: Partridge D. G. , Vrugt J. A. , Tunved P. , Ekman A. M. L. , Struthers H. , Sorooshian A.
Published: March 2012

Abstract. This paper presents a novel approach to investigate cloud-aerosol interactions by coupling a Markov chain Monte Carlo (MCMC) algorithm to an adiabatic cloud parcel model. Despite the number of numerical cloud-aerosol sensitivity studies previously conducted few have used statistical analysis tools to investigate the global sensitivity of a cloud model to input aerosol physiochemical parameters. Using numerically generated cloud droplet number concentration (CDNC) distributions (i.e. synthetic data) as cloud observations, this inverse modelling framework is shown to successfully estimate the correct calibration parameters, and their underlying posterior probability distribution. The employed analysis method provides a new, integrative framework to evaluate the global sensitivity of the derived CDNC distribution to the input parameters describing the lognormal properties of the accumulation mode aerosol and the particle chemistry. To a large extent, results from prior studies are confirmed, but the present study also provides some additional insights. There is a transition in relative sensitivity from very clean marine Arctic conditions where the lognormal aerosol parameters representing the accumulation mode aerosol number concentration and mean radius and are found to be most important for determining the CDNC distribution to very polluted continental environments (aerosol concentration in the accumulation mode >1000 cm−3) where particle chemistry is more important than both number concentration and size of the accumulation mode. The competition and compensation between the cloud model input parameters illustrates that if the soluble mass fraction is reduced, the aerosol number concentration, geometric standard deviation and mean radius of the accumulation mode must increase in order to achieve the same CDNC distribution. This study demonstrates that inverse modelling provides a flexible, transparent and integrative method for efficiently exploring cloud-aerosol interactions with respect to parameter sensitivity and correlation.
The global aerosol-climate model ECHAM-HAM, version 2: sensitivity to improvements in process representations
Authors: Zhang K. , O'Donnell D. , Kazil J. , Stier P. , Kinne S. , Lohmann U. , Ferrachat S. , Croft B. , Quaas J. , Wan H. , Rast S. , Feichter J.
Published: March 2012

Abstract. This paper introduces and evaluates the second version of the global aerosol-climate model ECHAM-HAM. Major changes have been brought into the model, including new parameterizations for aerosol nucleation and water uptake, an explicit treatment of secondary organic aerosols, modified emission calculations for sea salt and mineral dust, the coupling of aerosol microphysics to a two-moment stratiform cloud microphysics scheme, and alternative wet scavenging parameterizations. These revisions extend the model's capability to represent details of the aerosol lifecycle and its interaction with climate. Sensitivity experiments are carried out to analyse the effects of these improvements in the process representation on the simulated aerosol properties and global distribution. The new parameterizations that have largest impact on the global mean aerosol optical depth and radiative effects turn out to be the water uptake scheme and cloud microphysics. The former leads to a significant decrease of aerosol water contents in the lower troposphere, and consequently smaller optical depth; the latter results in higher aerosol loading and longer lifetime due to weaker in-cloud scavenging. The combined effects of the new/updated parameterizations are demonstrated by comparing the new model results with those from the earlier version, and against observations. Model simulations are evaluated in terms of aerosol number concentrations against measurements collected from twenty field campaigns as well as from fixed measurement sites, and in terms of optical properties against the AERONET measurements. Results indicate a general improvement with respect to the earlier version. The aerosol size distribution and spatial-temporal variance simulated by HAM2 are in better agreement with the observations. Biases in the earlier model version in aerosol optical depth and in the Ångström parameter have been reduced. The paper also points out the remaining model deficiencies that need to be addressed in the future.
Eddy covariance measurements of CO2 and energy fluxes in the city of Beijing
Authors: Liu H. Z. , Feng J. W. , Järvi L. , Vesala T.
Published: March 2012

Abstract. Long-term measurement of carbon dioxide flux (Fc) was performed using the eddy covariance (EC) method in the Beijing megacity over a 4-yr period in 2006–2009. The EC setup was installed at a height of 47 m on the Beijing 325-m meteorological tower in the northwest part of the city. Latent heat flux dominated the energy exchange between the urban surface and the atmosphere in summer, while sensible heat flux was the main component in the spring. The source area of the measurements of CO2 is highly heterogeneous, which consists of buildings, parks, and highways. It is valuable for global carbon budget research to study the temporal and spatial variability of Fc in this urban environment of a developing country. Both on a diurnal and monthly scale, the urban surface acted as a net source for CO2 and downward fluxes were only occasionally observed. The diurnal pattern of Fc showed dependence on automobile traffic and the typical two peak traffic pattern appeared in Fc diurnal cycle. Also, the Fc was higher on weekdays than on weekends due to the higher traffic volumes on weekdays. On seasonal scale, Fc was generally higher in winter than during other seasons, likely due to domestic heating during colder months. Total annual average CO2 emissions were estimated to be 4.90 kg C m−2 y−1 over the 4-yr period.
European summer surface ozone 1990–2100
Authors: Langner J. , Engardt M. , Andersson C.
Published: March 2012

Abstract. The impact of climate change and changes in ozone precursor emissions on summer surface ozone in Europe were studied using a regional CTM over the period 1990 to 2100. Two different climate simulations under the SRES A1B scenario together with ozone precursor emission changes from the RCP4.5 scenario were used as model input. In southern Europe regional climate change leads to increasing surface ozone concentrations during April–September, but projected emission reductions in Europe have a stronger effect, resulting in net reductions of surface ozone concentrations. In northern Europe regional climate change decreases surface O3 and reduced emissions acts to further strengthen this trend also when including increasing hemispheric background concentrations, although on the British Isles the combined effect is an increase. Due to substantial decadal variability in the simulations it is important to study averages over sufficiently long time periods in order to be able to extract robust signals of climate change impacts on surface O3 concentrations.
A plasma flow vortex in the magnetotail and its related ionospheric signatures
Authors: Tang C. L.
Published: March 2012

Abstract. We presented a large-scale plasma flow vortex event that occurred on 1 March 2009 observed by Time History of Events and Macroscale Interactions during Substorms (THEMIS) satellites. During the interval, THEMIS satellites were located in the premidnight region between 11 and 16 RE downtail. Dawnward-earthward plasma flows were seen initially in the magnetotail, followed by duskward-tailward flows. This suggests that a clockwise plasma flow vortex (seen from above the equatorial plane) was observed on the dawn side of the plasma sheet. Furthermore, high energy (>1 keV) electrons were observed. Auroral images at 427.8 nm and THEMIS white light all-sky imager (ASI) at Fort Smith showed a discrete auroral patch formed at the poleward of the auroral oval, it then intensified. It extended eastward and equatorward first and followed by westward motion to form the clockwise auroral vortex. The auroral feature corresponded to the ionospheric signatures of the plasma flow vortex in the magnetotail when the Alfvén transit time between the magnetotail and the ionosphere was taken into account. We suggest that the large-scale clockwise plasma flow vortex in association with the high energy (>1 keV) electrons on the dawn side of the plasma sheet generated a downward field-aligned current (FAC) that caused the related ionospheric signatures. The plasma flow vortex had rotational flow speeds of up to 300 km s−1. The current density associated with the plasma flow vortex was estimated at 2.0 μA m−2, mapped to the ionosphere.
Environmental control on the variability of DMS and DMSP in the Mauritanian upwelling region
Authors: Zindler C. , Peeken I. , Marandino C. A. , Bange H. W.
Published: March 2012

Abstract. Dimethylsulphide (DMS) and dissolved and particulate dimethylsulfoniopropionate (DMSPd, DMSPp) were measured in near-surface waters along the Mauritanian coast, Northwest Africa, during the upwelling season in February 2008. DMS, DMSPd and DMSPp surface concentrations of up to 10 nmol L−1, 15 nmol L−1 and 990 nmol L−1, respectively, were measured. However, the DMS concentrations measured are in the low range compared to other upwelling regions. The maximum DMSPp concentration is the highest reported from upwelling regions so far, which might indicate that the Mauritanian upwelling is a hot spot for DMSP. Within the phytoplankton groups, dinoflagellates were identified as important contributors to DMS concentrations, while other algae seemed to have only a minor or no influence on DMS and DMSP concentrations. A pronounced switch from high DMSP to high DMS concentrations was observed when the nitrogen to phosphorus ratio (N:P) was below 7. The high DMS/DMSP ratios at N:P ratios <7 indicate that nitrogen limitation presumably triggered a switch from DMSP to DMS independent of the species composition. Our results underline the importance of coastal upwelling regions as a local source for surface seawater sulphur.
Nutrient limitation reduces land carbon uptake in simulations with a model of combined carbon, nitrogen and phosphorus cycling
Authors: Goll D. S. , Brovkin V. , Parida B. R. , Reick C. H. , Kattge J. , Reich P. B. , van Bodegom P. M. , Niinemets Ü.
Published: March 2012

Abstract. Terrestrial carbon (C) cycle models applied for climate projections simulate a strong increase in net primary productivity (NPP) due to elevated atmospheric CO2 concentration during the 21st century. These models usually neglect the limited availability of nitrogen (N) and phosphorus (P), nutrients that commonly limit plant growth and soil carbon turnover. To investigate how the projected C sequestration is altered when stoichiometric constraints on C cycling are considered, we incorporated a P cycle into the land surface model JSBACH, which already includes representations of coupled C and N cycles. The model reveals a distinct geographic pattern of P and N limitation. Under the SRES A1B scenario, the accumulated land C uptake between 1860 and 2100 is 13% (particularly at high latitudes) and 16% (particularly at low latitudes) lower in simulations with N and P cycling, respectively, than in simulations without nutrient cycles. The combined effect of both nutrients reduces land C uptake by 25% compared to simulations without N or P cycling. However, the quantification of P limitation remains challenging as the poorly constrained processes of soil P sorption and biochemical mineralization strongly influence the strength of P limitation. After 2100, increased temperatures (+5 K) and high CO2 (700 ppm) concentrations cause a shift from N to P limitation at high latitudes, while nutrient limitation in the tropics declines. The increase in P limitation at high-latitudes is induced by a strong increase in NPP and the low P sorption capacity of soils, while a decline in tropical NPP due to high autotrophic respiration rates alleviates N and P limitation. These findings indicate that global land C uptake in the 21st century is likely overestimated in models that neglect P and N limitation. In the long-term, insufficient P availability might become an important constraint on C cycling at high latitudes. Accordingly, we argue that the P cycle must be included in global models used for C cycle projections.
Individual- and stand-level Stem CO2 efflux in a subtropical Schima superba plantation
Authors: Zhu L. W. , Zhao P. , Ni G. Y. , Cao Q. P. , Zhou C. M. , Zeng X. P.
Published: March 2012

Abstract. Stem CO2 efflux was investigated with an open gas exchange system while stand microclimate and stem temperature were continuously monitored in a Schima superba plantation in South China for several days in August and December, 2010. The temperature response of respiration over the different seasons, the vertical variation in stem CO2 efflux along the stem and the stand-level stem CO2 efflux were examined. Stem volume was identified as the better correlate for stem CO2 efflux and was used as scaling scalar for the stand-level estimates of stem CO2 efflux in this S. superba plantation. Volume-based stem CO2 efflux was higher at 2 m than at 1.3 m. Mean stem CO2 efflux was 268.9 and 104.6 μmol m−3 s−1 in August and December, respectively, indicating a dramatic seasonal variation of stem CO2 efflux. The temperature response of stem CO2 efflux was constant during our study period with Q10 values of 1.9 and 1.8. In this subtropical S. superba plantation, the averaged stem CO2 efflux per unit ground area was 3.36 and 1.26 μmol m−2 s−1 in August and December, respectively, which was underestimated due to the vertical variation of stem CO2 efflux along the stem. Our results suggest that stem CO2 efflux has a constant temperature response on the stand scale, and the seasonal variation in stem CO2 efflux is mainly controlled by stem temperature, and the vertical variation in stem CO2 efflux needs to be considered at the stand-level estimation.
Constraining a global ecosystem model with multi-site eddy-covariance data
Authors: Kuppel S. , Peylin P. , Chevallier F. , Bacour C. , Maignan F. , Richardson A. D.
Published: March 2012

Abstract. Assimilation of in situ and satellite data in mechanistic terrestrial ecosystem models helps to constrain critical model parameters and reduce uncertainties in the simulated energy, water and carbon fluxes. So far the assimilation of eddy covariance measurements from flux-tower sites has been conducted mostly for individual sites ("single-site" optimization). Here we develop a variational data assimilation system to optimize 21 parameters of the ORCHIDEE biogeochemical model, using net CO2 flux (NEE) and latent heat flux (LE) measurements from twelve temperate deciduous broadleaf forest sites. We assess the potential of the model to simulate, with a single set of inverted parameters, the carbon and water fluxes at these 12 sites. We compare the fluxes obtained from this "multi-site" (MS) optimization to those of the prior model, and of the "single-site" (SS) optimizations. The model-data fit analysis shows that the MS approach decreases the daily root mean square difference (RMS) to observed data by 22%, which is close to the SS optimizations (25% on average). We also show that the MS approach distinctively improves the simulation of the ecosystem respiration (Reco), and to a lesser extent the gross carbon flux (GPP), although we only assimilated net CO2 flux. A process-oriented parameter analysis indicates that the MS inversion system finds a unique combination of parameters which is not the simple average of the different SS set of parameters. Finally, in an attempt to validate the optimized model against independent data, we observe that global scale simulations with MS optimized parameters show an enhanced phase agreement between modeled leaf area index (LAI) and satellite-based measurements of normalized difference vegetation index (NDVI).
On the importance of appropriate rain-gauge catch correction for hydrological modelling at mid to high latitudes
Authors: Stisen S. , Højberg A. L. , Troldborg L. , Refsgaard J. C. , Christensen B. S. B. , Olsen M. , Henriksen H. J.
Published: March 2012

Abstract. An existing rain gauge catch correction method addressing solid and liquid precipitation was applied both as monthly mean correction factors based on a 30 yr climatology (standard correction) and as daily correction factors based on daily observations of wind speed and temperature (dynamic correction). The two methods resulted in different winter precipitation rates for the period 1990–2010. The resulting precipitation data sets were evaluated through the comprehensive Danish National Water Resources model (DK-Model) revealing major differences in both model performance and optimized model parameter sets. Simulated stream discharge is improved significantly when introducing a dynamic precipitation correction, whereas the simulated hydraulic heads and multi-annual water balances performed similarly due to recalibration adjusting model parameters to compensate for input biases. The resulting optimized model parameters are much more physically plausible for the model based on dynamic correction of precipitation. A proxy-basin test where calibrated DK-Model parameters were transferred to another region without site specific calibration showed better performance for parameter values based on the dynamic correction. Similarly, the performances of the dynamic correction method were superior when considering two single years with a much dryer and a much wetter winter, respectively, as compared to the winters in the calibration period (differential split-sample tests). We conclude that dynamic precipitation correction should be carried out for studies requiring a sound dynamic description of hydrological processes and it is of particular importance when using hydrological models to make predictions for future climates when the snow/rain composition will differ from the past climate. This conclusion is expected to be applicable for mid to high latitudes especially in coastal climates where winter precipitation type (solid/liquid) fluctuate significantly causing climatological mean correction factors to be inadequate.
Partitioning of evaporation into transpiration, soil evaporation and interception: a combination of hydrometric measurements and stable isotope analyses
Authors: Sutanto S. J. , Wenninger J. , Coenders-Gerrits A. M. J. , Uhlenbrook S.
Published: March 2012

Abstract. Best practice agriculture is the key to overcome the food security problem through improvement of water use efficiency. Therefore, knowledge of the water fluxes within the soil-vegetation-atmosphere system is crucial. Many studies have tried to quantify these fluxes, but they encountered difficulties in quantifying the relative contribution of evaporation and transpiration. In this study, we compared four different methods to estimate evaporation fluxes during simulated summer conditions in a grassland lysimeter in the UNESCO-IHE laboratory. Only two of these methods can be used to partition total evaporation into transpiration, soil evaporation and interception. A water balance calculation (whereby rainfall, soil moisture and percolation was measured) and the Penman-Monteith equation were applied to determine total evaporation. A HYDRUS-1D model and isotope measurements were used for the partitioning of total evaporation. The average total evaporation was 3.2 mm d−1 calculated with the water balance, 3.4 mm d−1 for the Penman-Monteith equation, 3.4 mm d−1 calculated with HYDRUS-1D, and 3.1 mm d−1 with the isotope mass balance. By use of the isotopes, we separated the total evaporation on average into 2.4 mm d−1 transpiration (77.7%), 0.4 mm d−1 soil evaporation (12.2%), and 0.3 mm d−1 interception (10.1%).
Ground-penetrating radar insight into a coastal aquifer: the freshwater lens of Borkum Island
Authors: Igel J. , Günther T. , Kuntzer M.
Published: March 2012

Abstract. Freshwater lenses within islands are an important resource for drinking water. The aim of the GPR investigation was to map the shape of the groundwater table and sedimentary structures on Borkum island as input parameters for hydrogeological simulation. In total, 20 km of constant offset (CO) radar profiles were measured with centre frequencies of 80 and 200 MHz. Wave velocities were determined by common midpoint (CMP) measurements and vertical radar profiling (VRP) in a monitoring well. The 80 MHz CO data show a clear reflection at the groundwater table, whereas the reflection is blurry and shifted to lower frequencies for the 200 MHz data. This is caused by the gradual increase of water content above the capillary fringe. The GPR-derived water tables are in good accordance with the observation of the monitoring wells in the area. In the centre of the island, the groundwater table is found up to 3.5 m above sea level, however it is lower towards the coast line. Some local depressions are observed in the region of dune valleys and around pumping stations of the local water supplier. GPR also reveals details within the sediments and highly-permeable aeolian sands can be distinguished from less-permeable marine sediments. A sharp horizontal reflection below the water table can be seen on many profiles and is identified as a hydraulically-tight silt loam layer by hand-drilled boreholes. Moreover, GPR data indicate scattered erosion channels in this layer that cause it to be an aquitard with some leakage. GPR provides a high resolution map of the groundwater table and insight into the stratigraphy of the sediments that are a valuable complementary information to the observation of monitoring wells.
What Drives States to Support Renewable Energy?
Authors: Jenner Steffen , Chan Gabriel , Frankenberger Rolf , Gabel Mathias
Published: March 2012

Why do states support electricity generation from renewable energy sources? Lyon/Yin (2010), Chandler (2009), and Huang et al. (2007) have answered this question for the adoption of renewable portfolio standards (RPS) at the U.S. state level. This article supplements their work by testing the core hypotheses on the EU27 sample between 1990 and 2010. Furthermore, the article asks why the majority of EU states rely on feed-in-tariffs (FIT). The study conducts logistic time series cross-section regression analyses that run on a hazard model.

Evidence in support of private interest theory and public interest theory is provided. (a) The existence of a solar energy association increases the probability of a state to adopt regulation. (b) Solar radiation, and(c) the unemployment rate also increase the odds. (d) Electricity market concentration decreases the probability of transition.
The Weak Tie Between Natural Gas and Oil Prices
Authors: Ramberg David J. , Parsons John E.
Published: March 2012

Several recent studies establish that crude oil and natural gas prices are cointegrated. Yet at times in the past, and very powerfully in the last two years, many voices have noted that the two price series appear to have “decoupled”. We explore the apparent contradiction between these two views. We find that recognition of the statistical fact of cointegration needs to be tempered with two additional points. First, there is an enormous amount of unexplained volatility in natural gas prices at short horizons. Hence, any simple formulaic relationship between the prices will leave a large portion of the natural gas price unexplained. Second, the cointegrating relationship does not appear to be stable through time. The prices may be tied, but the relationship can shift dramatically over time. Therefore, although the two price series may be cointegrated, the confidence intervals for both short and long time horizons are large.
Split Incentives in Residential Energy Consumption
Authors: Gillingham Kenneth , Harding Matthew , Rapson David
Published: March 2012

We explore two split incentive issues between owners and occupants of residential dwellings: heating or cooling incentives are suboptimal when the occupant does not pay for energy use, and insulation incentives are suboptimal when the occupant cannot perfectly observe the owner’s insulation choice. We empirically quantify the effect of these two market failures and how they affect behavior in California. We find that those who pay are 16 percent more likely to change the heating setting at night and owner-occupied dwellings are 20 percent more likely to be insulated in the attic or ceiling. However, in contrast to common conception, we find that only small overall energy savings may be possible from policy interventions aimed at correcting the split incentive issues.
Composite fast‐slow MPC design for nonlinear singularly perturbed systems
Authors: Chen Xianzhong , Heidarinejad Mohsen , Liu Jinfeng , Christofides Panagiotis D.
Published: March 2012

The design of a composite control system for nonlinear singularly perturbed systems using model predictive control (MPC) is described. Specifically, a composite control system comprised of a “fast” MPC acting to regulate the fast dynamics and a “slow” MPC acting to regulate the slow dynamics is designed. The composite MPC system uses multirate sampling of the plant state measurements, i.e., fast sampling of the fast state variables is used in the fast MPC and slow‐sampling of the slow state variables is used in the slow MPC. Using singular perturbation theory, the stability and optimality of the closed‐loop nonlinear singularly perturbed system are analyzed. A chemical process example which exhibits two‐time‐scale behavior is used to demonstrate the structure and implementation of the proposed fast–slow MPC architecture in a practical setting. © 2012 American Institute of Chemical Engineers AIChE J, 58: 1802–1811, 2012
A novel and facile liquid whistle hydrodynamic cavitation reactor to produce submicron multiple emulsions
Authors: Tang Siah Ying , Sivakumar Manickam
Published: March 2012

Ferrous fumarate, [C4H2FeO4] is widely utilized in the effective treatments and prevention of iron deficiency anemia. But, its administration has been oftentimes linked with quite a few side effects than ferric products. To overcome the side effects, multiple water‐in‐oil‐in‐water (W/O/W) emulsion formulations had been proposed as a new drug delivery system for the controlled release of entrapped active iron compound. In this study, high‐pressure liquid whistle hydrodynamic cavitation reactor has been developed to produce highly stable W/O/W multiple emulsions containing Ferrous Fumarate in submicron scale (∼600 nm) with the droplet‐size distribution polydispersity index in the narrow regime (0.35–0.40). The microscopic observations confirmed that that the physical stability of the W/O/W emulsions was increased significantly with operating pressure and number of emulsification passes. Looking at the potential for scale‐up, this could be a promising technique to produce multiple emulsions incorporated with active constituents. © 2012 American Institute of Chemical Engineers AIChE J, 59: 155–167, 2013
General framework and modeling approach classification for chemical production scheduling
Authors: Maravelias Christos T.
Published: March 2012

Despite the increased number of publications in the area during the last two decades, there is no unified notation and systematic framework for chemical production scheduling. In this article, we first develop a framework for the description of scheduling problems in the chemical industries. While building upon ideas used in discrete manufacturing, the proposed framework accounts for features such as material handling restrictions which are critical in chemical production scheduling. Second, we present a classification of the various modeling approaches that have been presented in the process systems engineering literature. Our classification is broader than previous schemes because it accounts for more attributes, and it also offers a broader discussion of the modeling of time. We believe that our analysis will enhance the understanding of chemical production scheduling and lead to further advances in the area. © 2012 American Institute of Chemical Engineers AIChE J, 58: 1812–1828, 2012
A century of miners' compensation in South Africa
Authors: Ehrlich Rodney
Published: March 2012

The year 2011 marked the centenary of compensation legislation for miners' lung disease in South Africa. This commentary aims to demonstrate that the current compensation system does not serve its intended beneficiaries, particularly the large population of former gold miners affected by high rates of silicosis and tuberculosis. The system has a complex legislative history, reflecting contending political, and economic forces, and characterized by racial discrimination. The financial basis of the system is currently in crisis owing to historical underfunding and failure to take into account the mounting burden of disease among black former miners. The real value of compensation awards fell sharply between 1973 and 1993, only partly recovering in recent years. Barriers to claiming benefits, particularly by black former miners who know little about the process, have been extensively documented. Integration of miners' compensation into general workers' compensation has been mooted since the 1980s but has stalled, owing to the high cost of closing the gap between the mostly inferior financial benefits under the mining legislation and those available under workers' compensation legislation. A recent constitutional court decision has opened the way for unprecedented civil litigation against the gold mining industry for silicosis, adding to the pressure for reform. A number of changes are called for: harmonization of financial benefits with retention of certain of the special arrangements for miner claims, a regional cross‐border system of medical examination points for former miners, education of miners about the system, and some degree of privatization of claims processing. Am. J. Ind. Med. 55:560–569, 2012. © 2012 Wiley Periodicals, Inc.
Real time quaking‐induced conversion analysis of cerebrospinal fluid in sporadic Creutzfeldt–Jakob disease
Authors: McGuire Lynne I. , Peden Alexander H. , Orrú Christina D. , Wilham Jason M. , Appleford Nigel E. , Mallinson Gary , Andrews Mary , Head Mark W. , Caughey Byron , Will Robert G. , Knight Richard S. G. , Green Alison J. E.
Published: March 2012

Objective:

Current cerebrospinal fluid (CSF) tests for sporadic Creutzfeldt–Jakob disease (sCJD) are based on the detection of surrogate markers of neuronal damage such as CSF 14‐3‐3, which are not specific for sCJD. A number of prion protein conversion assays have been developed, including real time quaking‐induced conversion (RT‐QuIC). The objective of this study is to investigate whether CSF RT‐QuIC analysis could be used as a diagnostic test in sCJD.

Methods:

An exploratory study was undertaken that analyzed 108 CSF samples from patients with neuropathologically confirmed sCJD or from control patients. Of the 108 CSF samples, 56 were from sCJD patients (30 female, 26 male; aged 31–84 years; mean age, 62.3 ± 13.5 years), and 52 were from control patients (26 female, 26 male; aged 43–84 years; mean age, 67.8 ± 10.4 years). A confirmatory group of 118 patients was subsequently examined that consisted of 67 cases of neuropathologically confirmed sCJD (33 female, 34 male; aged 39–82 years; mean age, 67.5 ± 9.0 years) and 51 control cases (26 female, 25 male; aged 36–87 years; mean age, 63.5 ± 11.6 years).

Results:

The exploratory study showed that RT‐QuIC analysis had a sensitivity of 91% and a specificity of 98% for the diagnosis of sCJD. These results were confirmed in the confirmatory study, which showed that CSF RT‐QuIC analysis had a sensitivity and specificity of 87% and 100%, respectively.

Interpretation:

This study shows that CSF RT‐QuIC analysis has the potential to be a more specific diagnostic test for sCJD than current CSF tests. ANN NEUROL 2012;72:278–285.
Organotin catalysts in organosilicon chemistry
Authors: Cervantes Jorge , Zárraga Ramón , Salazar‐Hernández Carmen
Published: March 2012

Organotin compounds are best known in the chemical industry as PVC stabilizers, polyurethane foam formers and antifungal agents. However, they have also been widely used in the silicon industry for decades for curing organosilicon polymers, despite the fact that neither the mechanism through which the siloxane bonds are formed nor their inherent toxicity are completely understood. This review gives an account of the use of organotin compounds in the preparation of diverse polysiloxane‐containing materials via cross‐linking with either organic or inorganic polymers. As they are common ingredients for this application, a brief outline of the preparation of relevant silicon‐containing compounds, as well as their reactivity, are given. In addition, since there is some evidence that stannasiloxanes formed in situ during the reaction play a determinant role as intermediates in the reaction mechanism, an overview of the synthesis and reactivity of Sn‐O‐Si‐containing compounds is also presented. Copyright © 2012 John Wiley & Sons, Ltd.
Adaptive fault‐tolerant control based on hybrid redundancy
Authors: Takahashi Masanori , Takagi Taro
Published: March 2012

This paper presents a new actuator fault accommodation based on a hybrid of static and dynamic redundancies. Introduction of the activation functions for the actuators makes it possible to switch the redundancy modes appropriately. These functions are switched among the two values, 0 and 1, by monitoring only the input and output signals, and they determine the power supplies for the actuators. Furthermore, in this paper, the adaptively switching high‐gain feedback controller is developed to achieve the λ‐tracking in the presence of unknown perturbations. The adaptive tracker is modified to suit the switching mechanism for tuning the activation‐functions. Thus, the proposed adaptive fault‐tolerant control system with a hybrid redundancy has the advantages of both static and dynamic redundancies, and has high robustness with regard to actuator failures and variations in dynamics. In addition, a practical application to a chemical reactor is shown to confirm the effectiveness of the overall adaptive fault‐tolerant control system. © 2012 Curtin University of Technology and John Wiley & Sons, Ltd.
Metal‐Ion Permeation in Congested Nanochannels: The Exposure Effect of Ag+ Ions on the Phosphorescent Properties of a Gold(I)–Pyrazolate Complex that is Confined in the Nanoscopic Channels of Mesoporous Silica
Authors: Lintang Hendrik O. , Kinbara Kazushi , Yamashita Takashi , Aida Takuzo
Published: March 2012

An organometallic/silica nanocomposite of a 1D cylindrical assembly of a trinuclear gold(I)–pyrazolate complex ([Au3Pz3]) that was confined inside the nanoscopic channels of hexagonal mesoporous silica ([Au3Pz3]/silicahex), emitted red light with a luminescence center at 693 nm upon photoexcitation at 276 nm owing to a AuIAuI metallophilic interaction. When a film of [Au3Pz3]/silicahex was dipped into a solution of Ag+ in tetrahydrofuran (THF), the resulting nanocomposite material (Ag@[Au3Pz3]/silicahex) emitted green light with a new luminescence center at 486 nm, which was characteristic of a AuIAgI heterometallic interaction. Changes in the emission/excitation and XPS spectra of Ag@[Au3Pz3]/silicahex revealed that Ag+ ions permeated into the congested nanochannels of [Au3Pz3]/silicahex, which were filled with the cylindrical assembly of [Au3Pz3].
Simultaneous determination of four shanzhiside methylester derivatives in rabbit plasma by liquid chromatography/tandem mass spectrometry
Authors: Fan Peng‐Cheng , Li Mao‐Xing , Ma Hui‐Ping , Jing Lin‐lin , Qiu Jian‐guo , Jia Zheng‐Ping
Published: March 2012

A simple and sensitive high‐performance liquid chromatography/tandem mass spectrometry (LC/MS/MS) method was developed and validated for simultaneous determination of shanzhiside methylester and its three derivatives in rabbit plasma. The method showed good linearity and no endogenous material interfered with the marked compounds and internal standard (IS) capatol peaks. Samples were processed by acetonitrile precipitation. Chromatography was performed using a C18 column (150 × 3.9 mm i.d., 4 µm). The mobile phase consisted of methanol and water (60:40, v/v) during a total run time of 7 min. The main mass parent ions and daughter ions pairs (m/z) for monitoring were: shanzhiside methylester, 429.0/267.4; 8‐O‐acetyl shanzhiside methylester, 470.9/411.3; loganin, 413.2/251.4; phloyoside II, 479.2/281.3; and IS 385.2/203.3. Finally, the method was applied to a pharmacokinetic study of rabbits following intravenous administration of iridoid glycosides extracted from traditional herb Lamiophlomis rotata. Copyright © 2012 John Wiley & Sons, Ltd.
Antifeedant Activity of Fatty Acid Esters and Phytosterols from Echium wildpretii
Authors: Santana Omar , Reina Matias , Fraga Braulio M. , Sanz Jesús , González‐Coloma Azucena
Published: March 2012

Crude extracts and fractions from Echium wildpretii H. Pearson ex Hook. f. subsp. wildpretii (Boraginaceae) have been tested against insect species Spodoptera littoralis, Leptinotarsa decemlineata, and the aphids Myzus persicae, Diuraphis noxia, Metopolophium dirhodum, Rhopalosiphum maidis, and Rhopalosiphum padi. The EtOH extract and the lipid and steroidal fractions of E. wildpretii exhibited significant antifeedant activities against the aphids and L. decemlineata. Two bioactive mixtures composed of fatty acid esters and n‐alkanes were obtained from the lipid fraction. The bioguided fractionation of the steroidal fraction resulted in the isolation of glutinol, β‐sitosterol, (3β,7α)‐stigmast‐5‐ene‐3,7‐diol, and (3β,7α)‐7‐methoxystigmast‐5‐en‐3‐ol. The latter two compounds exhibited potent antifeedant activities against L. decemlineata indicating that the presence of an O‐bearing C(7) was responsible for the activities of these molecules.
Composition and Antibacterial Activity of the Essential Oils of Four Commercial Grades of Omani Luban, the Oleo‐Gum Resin of Boswellia sacraFlueck.
Authors: Al‐Saidi Salim , Rameshkumar K. B. , Hisham Abdulkhader , Sivakumar Nallusamy , Al‐Kindy Salma
Published: March 2012

The essential oil compositions of four botanically certified and commercially available samples of Omani lubans (oleo‐gum resins of Boswellia sacra Flueck.), locally known as Hoojri, Najdi, Shathari, and Shaabi in Jibali Arabic, obtained from plants growing in four different geographic locations of the Dhofar region of Oman, were analyzed by GC‐FID, GC/MS, and 13C‐NMR spectroscopy. The market price of these four grades of lubans differed considerably, according to their color, clump size, and texture. However, this study revealed that Hoojri, the first grade luban, and Shaabi, the fourth grade luban, which greatly differed in their price, closely resembled each other in their essential oil composition, yield, and physicochemical characteristics, except the color and texture. The composition, yield, and specific rotation of the oils of Najdi and Shathari, the second and the third grade lubans, respectively, were different from those of Hoojri and Shaabi, but they both had high limonene contents. Najdi oil was different from the other three oils in terms of its high myrcene content. α‐Pinene was the principal component in all the oils and can be considered as a chemotaxonomical marker that confirms the botanical and geographical source of the resins. All the oils showed pronounced activity against a panel of bacteria, and the trend in their bioactivity and their mode of action are discussed.
Defensive Sesquiterpenes from Senecio candidans and S. magellanicus, and Their StructureActivity Relationships
Authors: Reina Matías , Santana Omar , Domínguez Dulce M. , Villarroel Luis , Fajardo Víctor , Rodríguez Matías L. , González‐Coloma Azucena
Published: March 2012

Eleven eremophilanolides, 1–3 and 6–13, and two eremophilanes, 24 and 25, were isolated from Senecio candidans and S. magellanicus from the Magallanes Region (Chile). Compounds 2, 3, 9, and 10 have not been previously reported as natural products. Their structures were established by NMR spectroscopic analysis and chemical transformations. The X‐ray analysis of compounds 11, 13, and 17 were also performed. Different semisynthetic analogs from eremophilanolide 11 were generated to carry out a structureactivity relationship study. Their possible plant defensive role was tested against herbivorous insects (Spodoptera littoralis, Rhopalosiphum padi, and Myzus persicae) and plants (Lactuca sativa). Additionally, their effects on insect (Sf9) and mammalian (CHO) cell lines were tested.
A virtual histology intravascular ultrasound analysis of coronary chronic total occlusions
Authors: Guo Jun , Maehara Akiko , Mintz Gary S , Ashida Kazuhiro , Pu Jun , Shang Yunpeng , Leon Martin B. , Stone Gregg W. , Moses Jeffrey W. , Ochiai Masahiko
Published: March 2012

Objectives

We used virtual histology intravascular ultrasound (VH‐IVUS) to investigate plaque composition of chronic total occlusions (CTO).

Background

There are limited data on the composition of CTOs, especially in vivo.

Methods

VH‐IVUS was performed in 50 CTO lesions (49 patients) after guidewire crossing or pre‐dilation using a 1.5–2 mm balloon. Plaque composition in the proximal reference, distal reference, and CTO segment (subsequently divided into proximal, middle, and distal subsegments) was analyzed and reported as median and interquartile range. VH‐IVUS phenotype was also assessed. The definition of a fibroatheroma was >10% confluent necrotic core (NC) in more than three consecutive frames.

Results

Overall, the maximum NC within the CTO [35.5% (28.7, 44.3%)] was similar to the proximal reference [35.6% (24.1, 42.1%)] and greater than the distal reference [31.5% (22.6, 35.2%), P < 0.01]. There was no difference in maximum NC observed among proximal [31.4% (25.2, 10.4%)], middle [31.0% (23.3, 38.3%)], and distal CTO subsegments [30.4% (22.0, 39.5%)]. Overall, 42/50 CTOs contained a VH‐fibroathroma; and 8/50 did not. CTOs containing a VH‐fibroatheroma had more NC and dense calcium while CTOs not containing a fibroatheroma had more fibrotic and fibrofatty plaque. Importantly, 60.5% of VH‐fibroatheroma‐containing CTOs had a thin‐cap fibroatheroma (NC abutted to the lumen) in the proximal reference.

Conclusions

Using VH‐IVUS, CTO morphology can be divided into two patterns: (1) CTO with VH‐fibroatheroma or (2) CTO without VH‐fibroatheroma. This suggests two mechanisms of CTO formation—the majority evolving from acute coronary syndrome and thrombosis and the minority from atherosclerosis progression. © 2012 Wiley Periodicals, Inc.
Quantification of temporal, procedural, and hardware‐related factors influencing radiation exposure during pediatric cardiac catheterization
Authors: Smith Benjamin G. , Tibby Shane M. , Qureshi Shakeel A. , Rosenthal Eric , Krasemann Thomas
Published: March 2012

Purpose

To quantify the impact of relocation to a purpose built pediatric cardiac catheterization laboratory, on patient radiation dose and fluoroscopy time. To provide guide values for radiation exposure during common structural interventions.

Material and methods

Design: A retrospective review of common structural cardiac interventions performed over 10‐years. The era comprised two 5‐year periods before and after relocation using different catheter laboratories. Multivariable analysis adjusted for the following variables: era (pre‐ and post‐move), year, operator seniority, patient age, procedure type. Setting: A quaternary referral congenital cardiac centre. Patients: All patients <18 yrs (n = 756) in whom one of 6 common structural interventions were undertaken between 2000 and 2009. Main outcome measures: Radiation dose and fluoroscopy time.

Results

The move to the new laboratory (latter era) was associated with a dramatic reduction in multivariable‐adjusted radiation dose, ranging from 64% (aortic coarctation stenting) to 87% (patent arterial duct closure). There was also a year upon year increase in radiation dose of 5.2% [95% confidence interval (CI): 0.6–10.0%], which persisted after the relocation. However, this was associated with a 5.1% yearly decrease in fluoroscopy time (95% CI: −7.9 to −2.2%).

Conclusion

Use of state‐of‐the‐art catheter equipment is associated with a dramatic reduction in radiation exposure. However, the surprising finding of year upon year increase in exposure (despite the new equipment) combined with decreased fluoroscopy time suggests a temporal decrease in hardware efficiency. This has major implications for hardware replacement. © 2012 Wiley Periodicals, Inc.
Late contained aortic root rupture and ventricular septal defect after transcatheter aortic valve implantation
Authors: Aminian Adel , Lalmand Jacques , Dolatabadi Dariouch
Published: March 2012

Transcatheter aortic valve implantation (TAVI) is a highly specialized technique offering a new therapeutic option to patients at high risk for conventional surgery. However, despite continuous improvements in operators' expertise and device technology, complications associated with this catheter procedure are not uncommon. We report an unusual case of late contained rupture of the aortic annulus, combining a para‐aortic false aneurysm and a ventricular septal defect, after the placement of an Edwards Sapien prosthesis. © 2012 Wiley Periodicals, Inc.
Infective endocarditis following transcatheter aortic valve replacement—: Diagnostic and management challenges
Authors: Loh Poay Huan , Bundgaard Henning , S⊘ndergaard Lars
Published: March 2012

Transcatheter aortic valve replacement (TAVR) can improve the symptoms and prognosis of patients with severe aortic stenosis who, due to a high expected operative risk, would not have otherwise been treated surgically. If these patients develop prosthetic valve endocarditis, their presentations may be atypical causing a delay in the diagnosis and treatment. The management is also complicated by their comorbidities, and surgical treatment may not be feasible leading to a significant morbidity and mortality. We describe a case of an 85‐year‐old man with TAVI prosthetic valve endocarditis successfully treated medically, discuss the challenges in the diagnosis and management of such patients, and review available literature on the incidence and outcome of the condition. © 2012 Wiley Periodicals, Inc.