bluuebunny/crossref_metadata_2025 huggingface dataset:
Stabilization of unknown nonlinear systems using a cognition‐based framework
Authors: Shen Xi , Zhang Fan , Söffker Dirk
Published: December 2011

This paper considers an adaptive control method based on a cognition‐based framework to stabilize unknown nonlinear systems. In order to fulfill the task of stabilization, neither the information about the systems dynamical structure nor the knowledge about system physical behaviors, but the system states, which are assumed as measurable, are required. The structure of the proposed controller consists of three parts. The first part is based on a recurrent neural network (RNN) to be used for local identification of the unknown nonlinear system in real time. The network can be utilized as system characteristics, which is further used to design the controller within the third part. In the second part, the set of the given input values leading to stable behavior of the closed‐loop system will be calculated numerically with a geometrical criterion based on a suitable definition of quadratic stability. In the third part, a suitable control input value is chosen accordingly to a time‐relevant criteria from the set of input values generated in the second part of the controller. These three parts and their internal connections are arranged within a so‐called cognition framework. The proposed cognitive controller is able to gain useful knowledge (with local validity) and define autonomously a suitable control input with respect to the requirements of the time‐relevant criteria. Numerical examples are shown to demonstrate the successful application and performance of the method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Short communication: Dimensionality reduction of curvelet sparse regularizations in limited angle tomography
Authors: Frikel Jürgen
Published: December 2011

We investigate the reconstruction problem for limited angle tomography. Such problems arise naturally in applications like digital breast tomosynthesis, dental tomography, etc. Since the acquired tomographic data is highly incomplete, the reconstruction problem is severely ill‐posed and the traditional reconstruction methods, such as filtered backprojection (FBP), do not perform well in such situations. To stabilize the inversion we propose the use of a sparse regularization technique in combination with curvelets. We argue that this technique has the ability to preserve edges. As our main result, we present a characterization of the kernel of the limited angle Radon transform in terms of curvelets. Moreover, we characterize reconstructions which are obtained via curvelet sparse regularizations at a limited angular range. As a result, we show that the dimension of the limited angle problem can be significantly reduced in the curvelet domain. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Multiscale total variation regularization in image restoration
Authors: Dong Yiqiu , Hintermüller Michael , Rincon‐Camacho M. Monserrat
Published: December 2011

A total variation model for image restoration is introduced. The model utilizes a spatially dependent regularization parameter in order to enhance image regions containing details while still sufficiently smoothing homogeneous features. A local variance estimator is used to automatically adjust the regularization parameter. A generalized hierarchical decomposition of the restored image is integrated to the algorithm in order to speed‐up the performance of the update scheme. The corresponding subproblems are solved by a superlinearly convergent algorithm based on Fenchel‐duality and inexact semismooth Newton techniques. Numerical tests illustrate the performance of the algorithm. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Multi‐level Voting Scheme of Kernel Fisher Discriminant Classifiers for Liver Fibrosis Identification in Ultrasound Images
Authors: Salca Victor‐Eugen , Gordan Mihaela , Vlaicu Aurel
Published: December 2011

Ultrasound imaging remains important for computer aided medical diagnosis. The assessment of hepatic fibrosis from ultrasound images has been investigated in recent works. Fibrosis modifies the liver texture; this is reflected in the hepatic ultrasound image. The existing works report the extraction of different texture features from small regions of interest (ROIs) in the hepatic ultrasound image used as inputs to machine learning classifiers. As the obtained accuracies are generally moderate (85‐90%), new texture descriptors and classifier schemes are still investigated. Here we assess the performance of the Kernel Fisher Discriminant (KFD) due to its success in other similar tasks. KFD allows an implicit texture discrimination learning from a set of texture samples. The novelty of our solution is its use in a multi‐level scheme. With a training set of ultrasound liver image ROIs of 64×64 pixels, we generate 3 training image sets, one at full size and the others by the decomposition of ROIs into 32×32 and 16×16 pixels blocks. Three KFD classifiers are trained. In the classification phase, each test ROI is classified and the result is obtained by a majority voting scheme. The accuracy of the proposed solution is 89%, on the level of the state of the art, and it can probably be improved by increasing the training set. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
An hp‐Efficient Residual‐Based A Posteriori Error Estimator for Maxwell's Equations
Authors: Bürg Markus
Published: December 2011

We present a residual‐based a posteriori error estimator for Maxwell's equations in the electric field formulation. The error estimator is formulated in terms of the residual of the considered problem and we state upper and lower bounds in terms of the energy error of the computed solution for the estimator. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cellular Automata (CA) for Simulations of Complex Geothermal Reservoirs
Authors: Srisupattarawanit Tarin , Ostermeyer George‐Peter
Published: December 2011

The exploitation of geothermal power is a renewable energy source with great potential in future. But the exploration and development of deep geothermal energy is connected with high cost and risk. These require a reliable functionality of geological heat exchanger. However the geothermal reservoirs are really complicated as phenomena and concrete downhole data are not completely discovered at present. In order to simulate them, complex modelings combined with different time scale are necessary. Recently, the cellular automata (CA) method is being developed and widely used for solving many complex problems in different fields. Here we introduced CA method combined with Navier‐Stoke equation and heat transfer; the domains of reservoirs are initially discretized into many lattice cells. The different cell type and their physical properties (e.g. water cell, porous cell, etc.) are introduced. Thermodynamically correct computation and computing fluid flow in different formations are performed. The paper will give some computational results, showing the efficiency and accuracy of this method, in order to complete the phenomena of complex geothermal problem. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Selfadjoint Schrödinger operators on the half‐space with compactly supported Robin boundary conditions
Authors: Behrndt Jussi , Kühn Christian , Rohleder Jonathan
Published: December 2011

Schrödinger differential operators on a half‐space with compactly supported Robin boundary conditions are studied. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Note on Homogenization of Ordinary Differential Equations with Delay Term
Authors: Waurick Marcus , Kaliske Michael
Published: December 2011

An approach to homogenization of delay differential equations is proposed. Assuming some dependence between the delay and the micro‐scale, the effective equation is explicitly computed. The effective equations of homogenization of delay equations and the respective equations without delay are compared. In either cases, the effective equation is of integro‐differential‐type. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Expansion of random field gradients using hierarchical matrices
Authors: Busch Ingolf , Ernst Oliver G. , Ullmann Elisabeth
Published: December 2011

We present two expansions for the gradient of a random field. In the first approach, we differentiate its truncated Karhunen‐Loève expansion. In the second approach, the Karhunen‐Loève expansion of the random field gradient is computed directly. Both strategies require the solution of dense, symmetric matrix eigenvalue problems which can be handled efficiently by combining hierachical matrix techniques with a thick‐restart Lanczos method. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dynamic analysis of dielectric elastomer actuators
Authors: Xu Bai‐Xiang , Müller Ralf , Klassen Markus , Gross Dietmar
Published: December 2011

Dielectric elastomer actuators (DEAs) with a typical sandwich structure of electrode‐elastomer‐electrode arrangement provide large deformation. DEAs outperform most large displacement actuators in terms of light weight, low cost, and high efficiency. The actuation mechanism of DEAs relies primarily on the electrostatic force or the Maxwell stress which is due to the reaction of material polarization in an electric field. By a dynamic nonlinear electromechanical continuum model implemented with the finite element method, the dynamic response of a homogeneous DEA is studied. Results show that the actuation magnitudes can be increased when the frequency of the applied electric field approaches to the eigenfrequency of the DEAs. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Simulation of Two‐Phase Steels based on Statistically Similar Representative Volume Elements
Authors: Balzani Daniel , Schröder Jörg , Brands Dominik
Published: December 2011

An increasing number of engineering structures in the fields of light weight constructions or automotive applications makes use of advanced high‐strength steels. To optimize the overall mechanical behavior computer simulations taking into account the micro‐heterogeneity of these materials have been becoming the major tool. Direct micro‐macro‐transition procedures, also known as the FE2‐method, provide a suitable numerical framework. The main problem of these methods applied to large random microstructures turns out to be the high computational cost with respect to both, the amount of memory and the computation time. In this context the definition of a representative volume element (RVE) plays an important role. Therefore, we focus on the construction of statistically similar RVEs (SSRVEs), which are characterized by a much less complexity than usual random RVEs and which represent still the mechanical response of the real material. For the construction of these SSRVEs we select several statistical measures of the microstructure of a two‐phase steel and assume them to be as similar as possible to the ones computed for the SSRVE. These measures are included in a least‐square functional, which has to be minimized. The accuracy of this method is presented by some representative numerical simulations, where the response of the real microstructure of the considered two‐phase steel and the SSRVEs is compared to each other. (© 2011 Wiley‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Spatial dispersion and binomial sequential sampling for the potato psyllid (Hemiptera: Triozidae) on potato
Authors: Butler Casey D , Trumble John T
Published: December 2011

BACKGROUND: The potato psyllid is a serious pest of potatoes. Sampling plans on potatoes for the potato psyllid have yet to be developed, thus the authors' objectives were (1) to determine the most efficient within‐plant sampling unit, (2) to determine the spatial dispersion of potato psyllids in potato fields and (3) to develop a binomial sequential sampling plan for this pest.

RESULTS: Significantly more potato plants were infested with potato psyllids on the edges of the field, and significantly more plants were infested with psyllids on the ‘top’ and ‘middle’ of the potato plant. Significantly more psyllids were also found on the undersides of leaves. The potato psyllid has an aggregated distribution in potato fields. Binomial sequential sampling plans were developed for three action thresholds representing 0.5, 1 and 5 psyllids per plant. The average sample numbers for these action thresholds were between 12 and 16 samples, depending on the action thresholds. However, based on the shape of the operating characteristic curve, the 0.5 and 1 sampling plans were more reliable than the 5 psyllids per plant plan.

CONCLUSION: The binomial sequential sampling plans are useful for detecting potato psyllids at low levels of infestation, which will be useful for pest management purposes. Copyright © 2011 Society of Chemical Industry
Designer repellents: combining olfactory, visual or taste cues with a secondary repellent to deter free‐ranging house sparrows from feeding
Authors: Clapperton Barbara Kay , Porter Richard ER , Day Tim D , Waas Joseph R , Matthews Lindsay R
Published: December 2011

BACKGROUND: Repellents may prevent bird pests from eating crops or protect non‐target birds from eating harmful substances. The feeding behaviour of free‐ranging house sparrows (Passer domesticus) presented with wheat treated with the secondary repellent anthraquinone (AQ), paired with visual and/or olfactory and taste cues, was recorded in a series of trials. The aim was to determine the suitability of repellent combinations for preventing birds from consuming pest baits.

RESULTS: Anthraquinone significantly reduced wheat consumption. The addition of cinnamon oil did not reduce consumption further, but the addition of either a blue colour or d‐pulegone enhanced repellency. Green wheat was consumed more than blue wheat. In a multichoice test, the sparrows did not differentiate between low and high concentrations of AQ on blue‐dyed wheat. With treatments on separate tables, the higher concentration was more repellent. Additional olfactory/gustatory cues palatable to pest mammals did not make the AQ‐treated wheat more or less acceptable to sparrows. AQ‐treated blue wheat with/without cinnamon oil was more repellent than green wheat with cinnamon oil, a colour/odour combination typically used for pest baits in New Zealand.

CONCLUSIONS: These data demonstrate the potential of combining the secondary repellent AQ with additional salient cues for modifying the feeding behaviour of sparrows. Copyright © 2011 Society of Chemical Industry
Modelling and simulation in the pharmaceutical industry—some reflections
Authors: Burman Carl‐Fredrik , Wiklund Stig Johan
Published: December 2011

Modelling and simulation (M&S) is increasingly being applied in (clinical) drug development. It provides an opportune area for the community of pharmaceutical statisticians to pursue. In this article, we highlight useful principles behind the application of M&S. We claim that M&S should be focussed on decisions, tailored to its purpose and based in applied sciences, not relying entirely on data‐driven statistical analysis. Further, M&S should be a continuous process making use of diverse information sources and applying Bayesian and frequentist methodology, as appropriate. In addition to forming a basis for analysing decision options, M&S provides a framework that can facilitate communication between stakeholders. Besides the discussion on modelling philosophy, we also describe how standard simulation practice can be ineffective and how simulation efficiency can often be greatly improved. Copyright © 2011 John Wiley & Sons, Ltd.
Neurotransmitter Metabolic Enzymes and Antioxidant Status on Alzheimer's Disease Induced Mice Treated with Alpinia galanga (L.) Willd
Authors: Hanish Singh J. C. , Alagarsamy V. , Sathesh Kumar S. , Narsimha Reddy Y.
Published: December 2011

Amyloid β(25‐35) (Aβ) peptide may be neurotoxic during the progression of Alzheimer's disease by eliciting reactive oxygen species. The use of folklore medicine is prevalent and plants which possess a rejuvenating property are a large source of natural antioxidants that might afford leads for the development of novel drugs in neurodegenerative disorders. The study was designed to investigate the effect of an ethanol extract of Alpinia galanga (L.) Willd (EAG) on oxidative stress induced Alzheimer's type amnesia in mice. Mice were treated with an experimental extract at 200 mg/kg and 400 mg/kg dose for 14 days and injected with neurotoxic Aβ and the doses were continued for 21 days. Behavioural studies with open field, step‐down inhibitory avoidance and a water maze after treatment indicated the acceleration in cognitive function. The elevated levels of acetylcholinesterase and monoamine oxidase enzymes in amnesia induced mice were attenuated by treatment with EAG. The generation of free radicals was decreased due increased activity of antioxidant enzymes after treatment with EAG. These findings suggested that EAG exerts an antiamnesiac effect in Aβ induced neurodegeneration through an antioxidant property. Copyright © 2011 John Wiley & Sons, Ltd.
In Vitro and In Vivo Inhibition of Glucocorticoid‐induced Osteoporosis by the Hexane Extract of Poncirus trifoliata
Authors: Kim Bo‐Young , Yoon Hyung‐Young , Yun Sun‐Il , Woo Eun‐Rhan , Song Nan‐Kyu , Kim Hyun‐Gyu , Jeong Seon‐Yong , Chung Yoon‐Sok
Published: December 2011

This study was performed to discover a novel herbal therapeutic for effective glucocorticoid‐induced osteoporosis (GIO) treatment and further to clarify its molecular mechanism of action. Ethanol or methanol extracts of 68 edible Korean native plants were screened to find effective natural plant sources for the treatment of GIO, and Poncirus trifoliata (L.) (Rutaceae, PT) was selected as a final candidate because of its high inhibitory activity plus its novelty. The hexane extract of PT (PT‐H) inhibited apoptotic cell death in dexamethasone‐induced osteoblastic cell lines, C3H10T1/2 and MC3T3‐E1. In vivo mouse results indicated that PT‐H not only had an inhibitory effect on the bone loss caused by glucocorticoid, but also promoted bone formation. The molecular mechanisms behind the effect of PT‐H on GIO were further clarified by screening of differentially expressed genes (DEGs) between dexamethasone (Dex)‐induced osteoblastic cells with or without PT‐H treatment. Finally, it was found that the expression level of AnxA6 in Dex‐induced osteoblastic cells and prednisolone (PD)‐treated GIO‐model mice was significantly decreased by PT‐H treatment. These findings suggest that PT‐H has a strong in vitro and in vivo inhibitory effect on GIO, and decreased expression of AnxA6 may play a key role in this inhibition. Copyright © 2011 John Wiley & Sons, Ltd.
Antidiabetic Effect of Oleanolic Acid: A Promising Use of a Traditional Pharmacological Agent
Authors: Wang Xin , Li Yu‐Liang , Wu Hao , Liu Jiang‐Zheng , Hu Jun‐Xia , Liao Nai , Peng Jie , Cao Pei‐Pei , Liang Xin , Hai Chun‐Xu
Published: December 2011

Diabetes mellitus (DM) is a metabolic disorder characterized by chronic hyperglycemia. Although the clear mechanisms of DM and insulin resistance are still to be cleared, it has been well documented that reactive oxygen species (ROS) play a pivotal role in DM and multiple types of insulin resistance. For the past few years, natural substances have been shown to have the potential to treatment DM. Attention has been especially focused on plants rich in triterpenoids, which generally show antioxidant and antiglycation effect. In our previous studies, it was shown that oleanolic acid (OA), a natural triterpenoid and an aglycone of many saponins, is a potent antioxidant acting as not only a free radical‐scavenger through direct chemical reactions but also as a biological molecule, which may enhance the antioxidant defenses. The present study aimed to investigate the potential antidiabetic effect of OA. Oleanolic acid showed a significant blood glucose‐lowering and weight‐losing effect in diabetic animals induced by streptozotocin (STZ). In the insulin resistant model, it was also shown that OA may promote insulin signal transduction and inhibit oxidative stress‐induced hepatic insulin resistance and gluconeogenesis, in which process the phosphorylation of ERK and the protective effect on mitochondrial function may be involved. These findings may significantly better the understanding of the pharmacological actions of OA and advance therapeutic approaches to DM. Copyright © 2011 John Wiley & Sons, Ltd.
Isolation of Diacyl Glycerol Acyl Transferase (DGAT) Inhibitors from Pachydictyon coriaceum
Authors: Choi Byoung Wook , Lee Hyun Sun , Lee Kyung Bok , Lee Bong Ho
Published: December 2011

The pharmacological inhibition of acyl CoA:diacylglycerol acyltransferase (DGAT, EC 2.3.1.20) has emerged as a target for the treatment of obesity and type 2 diabetes. Chromatographic analysis of the brown alga, Pachydictyon coriaceum, led to the isolation of diterpene dictyol E and hydroxyisocrenulatin. Pharmacological assay of these compounds demonstrated DGAT inhibitory activity with IC50 values of 46.0 μm and 23.3 μm, respectively. Copyright © 2011 John Wiley & Sons, Ltd.
Genistein Mitigates Radiation‐induced Testicular Injury
Authors: Kim Joong‐Sun , Heo Kyu , Yi Joo‐Mi , Gong Eun Ji , Yang Kwangmo , Moon Changjong , Kim Sung‐Ho
Published: December 2011

The present study investigated the radioprotective effect of a multifunctional soy isoflavone, genistein, with the testicular system. Genistein was administered (200 mg/kg body weight) to male C3H/HeN mice by subcutaneous injection 24 h prior to pelvic irradiation (5 Gy). Histopathological parameters were evaluated 12 h and 21 days post‐irradiation. Genistein protected the germ cells from radiation‐induced apoptosis (p < 0.05 vs vehicle‐treated irradiated mice at 12 h post‐irradiation). Genistein significantly attenuated radiation‐induced reduction in testis weight, seminiferous tubular diameter, seminiferous epithelial depth and sperm head count in the testes (p < 0.05 vs vehicle‐treated irradiated mice at 21 days post‐irradiation). Repopulation and stem cell survival indices of the seminiferous tubules were increased in the genistein‐treated group compared with the vehicle‐treated irradiation group at 21 days post‐irradiation (p < 0.01). The irradiation‐mediated decrease in the sperm count and sperm mobility in the epididymis was counteracted by genistein (p < 0.01), but no effect on the frequency of abnormal sperm was evident. Reactive oxygen species (ROS) were evaluated using DCFDA method and exposure to irradiation elevated ROS levels in the testis and genistein treatment resulted in a significant attenuation of radiation‐induced ROS production. The results indicate that genistein protects from testicular dysfunction induced by gamma‐irradiation by an antiapoptotic effect and recovery of spermatogenesis. Copyright © 2011 John Wiley & Sons, Ltd.
Second Moment Reliability Evaluation vs. Monte Carlo Simulations for Weld Fatigue Strength
Authors: Lorén Sara , Svensson Thomas
Published: December 2011

Monte Carlo simulations have become very popular in industrial applications as a tool to study variational influences on reliability assessments. The method is appealing because it can be done without any statistical knowledge and produces results that appear very informative. However, in most cases, the information gathered is no more than a complicated transformation of initial guesses because the statistical distributions of the dominating variational influences are unknown. The seemingly informative result may then be highly misleading, in particular, when the user lacks sufficient statistical knowledge. Instead, in cases where the input knowledge of the distributional properties is vague, it may be better to use a reliability method based on the actual knowledge, often not more than second moment characteristics. This can easily be done by using a method, based on variances, covariances, and sensitivity coefficients.

Here, a specific problem of fatigue life of a welded structure is studied by (i) a Monte Carlo simulation method and (ii) a second moment method. Both methods are evaluated on a fatigue strain–life approach and use experimental data showing variation in weld geometry and material strength parameters.

The two methods are compared and discussed in view of the engineering problem of reliability with respect to fatigue damage. Copyright © 2011 John Wiley & Sons, Ltd.
Strongly reduced fragmentation and soft emission processes in sputtered ion formation from amino acid films under large Arn+ (n ≤ 2200) cluster ion bombardment
Authors: Gnaser Hubert , Ichiki Kazuya , Matsuo Jiro
Published: December 2011

The analysis of organic and biological substances by secondary‐ion mass spectrometry (SIMS) has greatly benefited from the use of cluster ions as primary bombarding species. Thereby, depth profiling and three‐dimensional (3D) imaging of such systems became feasible. Large Arn+ cluster ions may constitute a further improvement in this direction. To explore this option, size‐selected Arn+ cluster ions with 300 ≤ n ≤ 2200 (bombarding energies 5.5 and 11 keV) were used to investigate the emission of positive secondary ions from four amino acid specimens (arginine, glycine, phenylalanine, and tyrosine) by time‐of‐flight SIMS. For all cluster sizes, the protonated molecule of the respective amino acid is observed in the mass spectra. With increasing cluster size the number of fragment ions decreases strongly in relation to the intact molecules, to the extent that the fraction of fragment ions amounts to less than 10% in some cases. Such ‘soft’ emission processes also lead the ejection of dimers and even multimers of the amino acid molecules. In the case of the phenylalanine, secondary ion species composed of up to at least seven phenylalanine moieties were observed. Tentatively, the ionization probability of the emitted molecules is envisaged to depend on the presence of free protons in the emission zone. Their number can be expected to decrease concurrently with the decreasing amount of fragmentation for large Arn+ cluster ions (i.e. for low energies per cluster atom). Copyright © 2011 John Wiley & Sons, Ltd.
Stable isotope analysis of organic carbon in small (µg C) samples and dissolved organic matter using a GasBench preparation device
Authors: Lang Susan Q. , Bernasconi Stefano M. , Früh‐Green Gretchen L.
Published: December 2011

The stable isotopes of organic matter can provide valuable information on carbon cycling dynamics, microbial metabolisms, and past climates. Since bulk measurements may mask dynamic changes to critical portions of the organic pool, researchers are increasingly isolating individual compounds for isotopic analysis. The amount of carbon isolated is frequently small, requiring specialized equipment for its analysis. We present a simple and accurate method to measure the δ13C values of µg‐amounts of organic compounds and dissolved organic matter in freshwaters using wet oxidation and a GasBench II preparation device. Samples containing 3 µg C can be analyzed with a precision of <0.4‰. For samples containing 1.2 µg C, the precision is <0.8‰. The blank is estimated to be ~0.2 µg C. The accuracy of the method is demonstrated for a wide range of compounds including those that are difficult to oxidize such as humic acid and phthalic acid. The δ13C values of DOC from river and riparian ground water determined by this method are comparable with those determined with an elemental analyzer on freeze‐dried samples of DOC. The low detection limit and the ease with which it can be combined with isolation techniques such as liquid chromatography make this technique attractive for the off‐line analysis of organic compounds, and open new possibilities for the development of methodologies for compound‐specific carbon isotope analysis of complex mixtures separated by HPLC. Copyright © 2011 John Wiley & Sons, Ltd.
Characterization and identification of chemical compositions in the extract of Artemisia rupestris L. by liquid chromatography coupled to quadrupole time‐of‐flight tandem mass spectrometry
Authors: Gu Dongyu , Yang Yi , Abdulla Rahima , Aisa Haji Akber
Published: December 2011

Liquid chromatography coupled to negative electrospray ionization (ESI) tandem mass spectrometry (MS/MS) employing a time‐of‐flight tandem mass spectrometer was used in the structural determination of phenolic compounds and sesquiterpenoids occurring in the extract from Artemisia rupestris L. A total of 91 compounds including chlorogenic acid derivatives, flavonoids (aglycone, O‐glycosyl, C‐glycosyl and C,O‐glycosyl), 2‐phenoxychromones and guaiane sesquiterpenoids were identified by comparing the retention time and fragmentation behavior with reference standards or according to accurate mass measurement and the characteristic fragmentation at low and high collision energy. Most of these compounds were reported in Artemisia rupestris L. for the first time. Meanwhile, the proposed pathway and the major diagnostic fragmentation of 2‐phenoxychromone and rupestonic acid were investigated to trace 2‐phenoxychromone and rupestonic acid derivatives in crude plant extracts. According to these rules, we have successfully characterized five potential novel compounds including three 2‐phenoxychromones (6‐demethoxy‐4′‐O‐methylcapillarisin‐O‐hexosylglucuronide, 6‐demethoxy‐4′‐O‐methylcapillarisin‐O‐pentosylhexoside and 6‐demethoxy‐4′‐O‐methylcapillarisin‐O‐deoxyhexosylhexoside) and two sesquiterpenoids (hexosyl‐glycurinide‐rupestonic acid and hexoside‐rupestonic acid). Copyright © 2011 John Wiley & Sons, Ltd.
Pressurized laboratory experiments show no stable carbon isotope fractionation of methane during gas hydrate dissolution and dissociation
Authors: Lapham Laura L. , Wilson Rachel M. , Chanton Jeffrey P.
Published: December 2011

The stable carbon isotopic ratio of methane (δ13C‐CH4) recovered from marine sediments containing gas hydrate is often used to infer the gas source and associated microbial processes. This is a powerful approach because of distinct isotopic fractionation patterns associated with methane production by biogenic and thermogenic pathways and microbial oxidation. However, isotope fractionations due to physical processes, such as hydrate dissolution, have not been fully evaluated. We have conducted experiments to determine if hydrate dissolution or dissociation (two distinct physical processes) results in isotopic fractionation. In a pressure chamber, hydrate was formed from a methane gas source at 2.5 MPa and 4°C, well within the hydrate stability field. Following formation, the methane source was removed while maintaining the hydrate at the same pressure and temperature which stimulated hydrate dissolution. Over the duration of two dissolution experiments (each ~20–30 days), water and headspace samples were periodically collected and measured for methane concentrations and δ13C‐CH4 while the hydrate dissolved. For both experiments, the methane concentrations in the pressure chamber water and headspace increased over time, indicating that the hydrate was dissolving, but the δ13C‐CH4 values showed no significant trend and remained constant, within 0.5‰. This lack of isotope change over time indicates that there is no fractionation during hydrate dissolution. We also investigated previous findings that little isotopic fractionation occurs when the gas hydrate dissociates into gas bubbles and water due to the release of pressure. Over a 2.5 MPa pressure drop, the difference in the δ13C‐CH4 was <0.3‰. We have therefore confirmed that there is no isotope fractionation when the gas hydrate dissociates and demonstrated that there is no fractionation when the hydrate dissolves. Therefore, measured δ13C‐CH4 values near gas hydrates are not affected by physical processes, and can thus be interpreted to result from either the gas source or associated microbial processes. Copyright © 2011 John Wiley & Sons, Ltd.
Chemical and isotopic compositions of bottled waters sold in Korea: chemical enrichment and isotopic fractionation by desalination
Authors: Kim Go‐Eun , Ryu Jong‐Sik , Shin Woo‐Jin , Bong Yeon‐Sik , Lee Kwang‐Sik , Choi Man‐Sik
Published: December 2011

A total of 54 Korean bottled waters were investigated to characterize their origins and types using elemental and isotopic composition, as well as to identify elemental and isotopic changes in desalinated marine water that arise due to desalination. The different types of bottled water displayed a wide pH range (3.42 to 7.21). The elemental compositions of still and sparkling waters were quite similar, whereas desalinated marine water was clearly distinguished by its high concentrations of Ca, Mg, B, and Cl. In addition, desalinated marine water had much higher isotope ratios of oxygen and hydrogen (−0.5 and −2‰, respectively) than still and sparkling waters (−8.4 and −57‰). The elemental composition of desalinated marine water was adjusted through post‐treatment procedures; in particular, boron was greatly enriched during desalination processes. The carbon isotope compositions of dissolved inorganic carbon (δ13CDIC values) varied widely according to the origins of the bottled waters (−25.6 to −13.6‰ for still water, –31.2 to −26.7‰ for sparkling water, and −24.1 to −6.3‰ for desalinated marine water). This indicates that carbon isotopes in dissolved inorganic carbon are significantly fractionated by desalination processes and re‐modified through post‐treatment procedures. The results suggest that combined elemental and stable isotopic tracers are useful for identifying the origin of bottled water, verifying elemental and isotopic modifications during desalination processes, and characterizing various water types of bottled waters. Copyright © 2011 John Wiley & Sons, Ltd.
An unusual intramolecular transfer of the fluorobenzyl cation between two remote amidic nitrogen atoms induced by collision in the gas phase
Authors: Yan Zhengyin , Tounge Brett , Caldwell Gary W.
Published: December 2011

A highly unusual rearrangement in collision‐induced dissociation mass spectrometry is reported that involves intramolecular transfer of the fluorobenzyl cation between two remote amidic nitrogen atoms separated by five chemical bonds. The same intramolecular transfer was also observed for two related analogs. It is postulated that the ionic reactions are initiated by protonation of the first amidic nitrogen, resulting in formation of the fluorobenzyl cation and a neutral partner that are maintained together in the gas phase by electrostatic interactions as an intermediate ion‐neutral complex. In the ion‐neutral complex, the nascent fluorobenzyl cation approaches geometrically to the second amidic nitrogen atom on the neutral partner, and subsequently forms a new C–N bond and an isomeric precursor ion as the charge is retained on the amidic nitrogen. The newly formed isomeric precursor ion eventually undergoes the final fragmentation by amide bond cleavage. Alternatively, the ionic reactions proceed through a direct intramolecular transfer mechanism by which the molecular ion adopts to a ring‐like configuration in the gas phase, so that both the donor and recipient nitrogens are geometrically close to each other within a bonding distance to permit a direct transfer between two sites even though they are separated by multiple chemical bonds. Copyright © 2011 John Wiley & Sons, Ltd.
Finite mixture varying coefficient models for analyzing longitudinal heterogenous data
Authors: Lu Zhaohua , Song Xinyuan
Published: December 2011

This paper aims to develop a mixture model to study heterogeneous longitudinal data on the treatment effect of heroin use from a California Civil Addict Program. Each component of the mixture is characterized by a varying coefficient mixed effect model. We use the Bayesian P‐splines approach to approximate the varying coefficient functions. We develop Markov chain Monte Carlo algorithms to estimate the smooth functions, unknown parameters, and latent variables in the model. We use modified deviance information criterion to determine the number of components in the mixture. A simulation study demonstrates that the modified deviance information criterion selects the correct number of components and the estimation of unknown quantities is accurate. We apply the proposed model to the heroin treatment study. Furthermore, we identify heterogeneous longitudinal patterns. Copyright © 2011 John Wiley & Sons, Ltd.
Service selection and horizontal multi‐sourcing in process‐oriented capability outsourcing
Authors: Ukor Roland , Carpenter Andy
Published: December 2011

Process‐oriented capability outsourcing is a type of B2B collaboration in which one organisation outsources parts of its business process to other organisations known as service providers. Current models and solution approaches for service selection in process‐oriented capability outsourcing do not provide support for horizontal multi‐sourcing—the ability to dynamically outsource a business capability to multiple independent service providers. This paper presents a new problem model for service selection based on the notion of request tokens, and evaluates three solution approaches to the problem: integer programming, tree‐search heuristic and genetic algorithm. Copyright © 2011 John Wiley & Sons, Ltd.
Flex‐eWare: a flexible model driven solution for designing and implementing embedded distributed systems
Authors: Jan Mathieu , Jouvray Christophe , Kordon Fabrice , Kung Antonio , Lalande Jimmy , Loiret Frédéric , Navas Juan , Pautet Laurent , Pulou Jacques , Radermacher Ansgar , Seinturier Lionel
Published: December 2011

The complexity of modern embedded systems increases as they incorporate new concerns such as distribution and mobility. These new features need to be considered as early as possible in the software development life cycle. Model driven engineering promotes an intensive use of models and is now widely seen as a solution to master the development of complex systems such as embedded ones. Component‐based software engineering is another major trend that gains acceptance in the embedded world because of its properties such as reuse, modularity, and flexibility.

This article proposes the Flex‐eWare component model (FCM) for designing and implementing modern embedded systems. The FCM unifies model driven engineering and component‐based software engineering and has been evaluated in several application domains with different requirements: wireless sensor networks, distributed client/server applications, and control systems for electrical devices. This approach highlights a new concept: flexibility points that arise at several stages of the development process, that is, in the model (design phase), in the execution platform, and during the execution itself. This flexibility points are captured with model libraries that can extend the FCM. Copyright © 2011 John Wiley & Sons, Ltd.
Catalytically propelled micro‐/nanomotors: how fast can they move?
Authors: Gao Wei , Sattayasamitsathit Sirilak , Wang Joseph
Published: December 2011

Synthetic micro‐/nanomotors represent one of the most exciting challenges facing nanotechnology and hold considerable promise for diverse future applications. This review discusses different strategies to improve the speed of the catalytic nanomotors, summarizing and comparing the maximum absolute and relative speeds obtained with different catalytically propelled micro‐/nanomotors. Remarkably ultrafast nanowires and microtube engines, with speeds of 60 and 375 body lengths s−1, respectively, have been developed recently. Achieving such amazingly high speed and power has been accomplished through rational optimization of key factors governing the propulsion behavior, including composition of the motor and fuel, the motor morphology and various external stimuli. We hope that our discussion will serve as a guide to the rational design of even faster and more powerful catalytically propelled fuel‐efficient micro‐/nanomotors, with speed limits that are limited only by our imagination. DOI 10.1002/tcr.201100031
Short‐circuit analysis of a doubly fed induction generator wind turbine with direct current chopper protection
Authors: Sulla F. , Svensson J. , Samuelsson O.
Published: December 2011

Modern doubly fed induction generator (DFIG) wind turbines can ride through a symmetrical fault in the network by using a chopper protection on the direct current (DC) link without triggering a crowbar protection. A novel method to model the DC link system of such wind turbines as an equivalent resistance during symmetrical faults is presented in this paper. The method allows looking at the DFIG with chopper protection as to one with an equivalent crowbar protection and, hence, to apply to the former type of DFIG short‐circuit calculation methods developed for a DFIG with crowbar protection. This may be a valid help in short‐circuit calculations, for example, for protection settings. It also allows simulating for short‐circuit studies a DFIG with chopper protection, often not available in a standard power system simulation software, by using an equivalent DFIG with crowbar protection, which is a standard model in power system simulation software. The results for the short‐circuit current obtained through the proposed method are compared with simulations of a detailed model of a DFIG with chopper protection under different conditions, which showed good agreement. It is also shown that the DFIG with chopper protection delivers lower short‐circuit current than a DFIG with standard crowbar protection, especially for low initial loading. Copyright © 2011 John Wiley & Sons, Ltd.
So Whaddya Think? Consumers Create Ads and Other Consumers Critique Them
Authors: Ertimur Burçak , Gilly Mary C.
Published: December 2011

With the availability of online creative tools, consumers create ad-like communications on their own or in response to company contests. These consumer-generated ads (CGA) are like word-of-mouth (WOM) in that they are consumer-to-consumer communications, yet they have the look and feel of traditional advertising. We examine consumer responses to both contest and unsolicited CGA and company ads using data gathered from consumers via netnography and depth interviews. Content analysis is used to compare the three ad types and reveals that the contest rules frame CGA so that they resemble company ads while unsolicited CGA differ from both ad types. Findings show that consumers respond to both types of CGA by engaging with the ad rather than the brand, much like an ad critic, while company ads elicit brand associations. Unsolicited CGA are seen as authentic, but not credible, while contest ads are seen as credible, but not authentic, revealing a boundary condition to the conventional view that authenticity leads to credibility.
Safety profile of Alzheimer's disease populations in Alzheimer's Disease Neuroimaging Initiative and other 18‐month studies
Authors: Henley David B. , Sundell Karen L. , Sethuraman Gopalan , Siemers Eric R.
Published: December 2011

Background

Demonstration of a disease‐modifying effect of a therapeutic agent on Alzheimer's disease (AD) requires a trial lasting for at least 18 months. An understanding of expected rates of adverse events (AEs), overall discontinuations, and discontinuations due to AEs, serious AEs, and deaths would be useful in planning such trials.

Methods

We examined safety information for patients taking placebo from five published 18‐month AD trials and for patients from the Alzheimer's Disease Neuroimaging Initiative study.

Results

AEs reported consistently across multiple studies were dyspnea (occurring in 5.3%–5.8% of patients), headache (4.0%–5.5%), constipation (4.3%–4.7%), nausea (2.0%–5.8%), joint swelling (3.6%–3.7%), vomiting (3.6%–3.7%), and anxiety (3.2%–3.6%). Larger multinational studies, as compared with smaller studies with fewer sites and geographies, demonstrated greater overall discontinuations (24.6%–33.0% vs 8.2%–21.0%) and greater discontinuations due to AEs (9.5%–11.6% vs 2.7%–3.2%). Rates of death (1.8%–2.4%) and SAEs (19.9%–21.2%) were consistent across 18 month published studies and in ADNI; fall was the most common SAE (2.6%–4.0%) where SAEs were reported.

Conclusions

In general, comparable types of AEs, frequency of deaths, and serious AEs were seen for patients taking placebo in five randomized, controlled 18‐month AD trials and in Alzheimer's Disease Neuroimaging Initiative, whereas rates of discontinuations were more variable. Evaluation across studies was complicated by inconsistent methods of reporting safety information. Evaluation of large databases of placebo patients from therapeutic AD trials is needed to further enhance the understanding of expected safety outcomes in clinical trials of AD patients.
uPA and uPAR shRNA inhibit angiogenesis via enhanced secretion of SVEGFR1 independent of GM‐CSF but dependent on TIMP‐1 in endothelial and glioblastoma cells
Authors: Raghu Hari , Nalla Arun Kumar , Gondi Christopher S. , Gujrati Meena , Dinh Dzunh H. , Rao Jasti S.
Published: December 2011

The uPA/uPAR system is known to play a critical role in angiogenesis of glioblastoma. Previously, we have shown that shRNA against uPA and uPAR attenuates angiogenesis by blocking nuclear translocation of angiogenin, inhibition of angiopoietin/Tie2 signaling, and regulating several other pro‐angiogenic, angiostatic and anti‐angiogenic molecules. Further analysis revealed that GM‐CSF, a pleiotropic cytokine, was significantly inhibited in U87MG and 4910 co‐cultures with endothelial cells transfected with shRNA against uPA and uPAR. The role of the uPA/uPAR system in this process is not completely understood. Analysis of tumor conditioned medium of U87MG, 4910 and HMECs transfected with shRNA against uPA or uPAR alone or in combination (pU2) revealed inhibition of GM‐CSF‐enhanced secretion of SVEGFR1 as shown by Western blotting and ELISA. Moreover, phosphorylation of JAK2 and STAT5, the downstream effectors of GM‐CSF signaling, was also inhibited in all three cell lines. Phosphorylation at Tyr 166 position of the GM‐CSFRβ subunit, the signal activating subunit of the GM‐CSF receptor, was inhibited in HMEC, U87MG and 4910 cells. Further analysis revealed that shRNA against uPA and/or uPAR increased secretion of TIMP‐1, which is known to enhance SVEGFR1 secretion in endothelial cells. Moreover, addition of purified uPA (with and without GM‐CSF) activated JAK2/STAT5 signaling in HMEC. Exogenous addition of SVEGFR1 to pU2 tumor conditioned medium enhanced inhibition of VEGF‐induced endothelial capillary tube formation as assessed by an in vitro angiogenesis assay. To determine the significance of these events in vivo, nude mice with pre‐established tumors treated with shRNA against uPA and/or uPAR showed decreased levels of GM‐CSF and increased levels of SVEGFR1 and TIMP‐1 when compared with controls. Enhanced secretion of SVEGFR1 by puPA, puPAR and pU2 in endothelial and GBM cells was mediated indirectly by MMP‐7 and augmented by ectodomain shedding of VEGFr1 by tyrosine phosphorylation at the 1213 position. Taken together, these results suggest that the uPA/uPAR system could prove beneficial as an indirect target for inhibition of angiogenesis in glioblastoma.