bluuebunny/crossref_metadata_2025_split huggingface dataset:
Extension of the notion of a gap to differential operators defined on different open sets
Authors: Burenkov Victor I. , Feleqi Ermal 
Published: March 2012

AbstractIn this paper the notion of a gap between two linear operators is extended to the case of linear differential operators defined on different open sets. Estimates of the gap between second order uniformly elliptic partial differential operators subject to homogeneous Dirichlet boundary conditions defined on different open sets Ω1 and Ω2 are obtained in terms of the geometrical characteristics of vicinity of Ω1 and Ω2. These estimates can be used for obtaining spectral stability estimates for the eigenvalues and eigenfunctions of the aforementioned operators.
Suggested immobilization test for diagnosis of restless legs syndrome in Parkinson's disease
Authors: De Cock Valérie Cochen , Bayard Sophie , Yu Huan , Grini Magda , Carlander Bertrand , Postuma Ron , Charif Mahmoud , Dauvilliers Yves 
Published: March 2012

AbstractDiagnosis of restless leg syndrome (RLS) in Parkinson's disease (PD) is difficult because of clinical confounds. The suggested immobilization test (SIT) is validated for diagnosis of primary RLS. This study evaluated the usefulness of the SIT for diagnosis of RLS in PD. We compared SIT scores, as well as polysomnography measures in 50 patients with PD (25 with RLS, 25 without), 25 patients with primary RLS, and 25 age/sex matched controls. Mean leg discomfort score was increased in patients with PD and RLS compared to PD without RLS, and also in patients with primary RLS compared to controls. Leg discomfort was significantly higher at the end of the test in patients with RLS compared to patients without RLS. Intensity of leg discomfort was similar between patients with RLS, with or without PD. Using a mean leg discomfort cutoff of 11, we showed sensitivity of 91% and specificity of 72% for RLS diagnosis in PD during symptomatic time intervals. Periodic leg movements index during the SIT did not differ between groups. Periodic leg movements index during sleep and wakefulness was increased in patients with primary RLS compared to controls, but did not differ between patients with PD, with and without RLS. The sensory SIT is a simple test that may help diagnose RLS in patients with PD. © 2012 Movement Disorder Society
Hexafluorobenzene in comparison with perfluoro‐15‐crown‐5‐ether for repeated monitoring of oxygenation using 19F MRI in a mouse model
Authors: Mignion Lionel , Magat Julie , Schakman Olivier , Marbaix Etienne , Gallez Bernard , Jordan Bénédicte F. 
Published: March 2012

AbstractHexafluorobenzene (HFB) and perfluoro‐15‐crown‐5‐ether (15C5) were compared as fluorine reporter probes of tissue oxygenation using 19F MRI for dynamic assessment of muscle oxygenation, with special focus on muscle tissue toxicity of the probes, and consecutive alteration of animal behavior. The latter were also compared in terms of sensitivity to changes in oxygenation as well as of signal‐to‐noise ratio for accurate pO2 measurements. For that purpose, mouse muscles were imaged at 11.7 T, at 2‐ and 36‐h after intramuscular injection of HFB or 15C5. Histological analysis of the muscle tissue revealed a lack of toxicity for 15C5 from 2 up to 36‐h postinjection, whereas HFB induced tissue necrosis, blood clots and thrombosis as soon as 24‐h postinjection. This muscle toxicity led to a limitation in mice mobility 24‐h after injection of HFB as evidenced by behavioral testing (open‐field, grip strength, and catwalk tests), which was not the case after 15C5 intramuscular injection. Finally, pO2 measurements assessed 2‐h postinjection showed consistent values with both probes, evidencing cross‐validation of the 19F MRI oximetry technique for acute measurements. However, the measurement at 36‐h was hampered for HFB, which showed significant lower values of muscle pO2, whereas 15C5 was able to reliably assess muscle pO2 at 36‐h postinjection. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
In vivo measurement of gadolinium diffusivity by dynamic contrast‐enhanced MRI: A preclinical study of human xenografts
Authors: Koh T. S. , Hartono S. , Thng C. H. , Lim T. K. H. , Martarello L. , Ng Q. S. 
Published: March 2012

AbstractCompartmental tracer kinetic models currently used for analysis of dynamic contrast‐enhanced MRI data yield poor fittings or parameter values that are unphysiological in necrotic regions of the tumor, as these models only describe microcirculation in perfused tissue. In this study, we explore the use of Fick's law of diffusion as an alternative method for analysis of dynamic contrast‐enhanced MRI data in the necrotic regions. Xenografts of various human cancer cell lines were implanted in 14 mice that were subjected to dynamic contrast‐enhanced MRI performed using a spoiled gradient recalled sequence. Tracer concentration was estimated using the variable flip angle technique. Poorly perfused and necrotic tumor regions exhibiting delayed and slow enhancement were identified using a k‐means clustering algorithm. Tracer behavior in necrotic regions was shown to be consistent with Fick's diffusion equation and the in vivo gadolinium diffusivity was estimated to be 2.08 (±0.88) × 10−4 mm2/s. This study proposes the use of gadolinium diffusivity as an alternative parameter for quantifying tracer transport within necrotic tumor regions. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
Simultaneous noncontrast angiography and intraPlaque hemorrhage (SNAP) imaging for carotid atherosclerotic disease evaluation
Authors: Wang Jinnan , Börnert Peter , Zhao Huilin , Hippe Daniel S. , Zhao Xihai , Balu Niranjan , Ferguson Marina S. , Hatsukami Thomas S. , Xu Jianrong , Yuan Chun , Kerwin William S. 
Published: March 2012

AbstractA simultaneous noncontrast angiography and intraplaque hemorrhage (SNAP) MR imaging technique is proposed to detect both luminal stenosis and hemorrhage in atherosclerosis patients in a single scan. Thirteen patients with diagnosed carotid atherosclerotic plaque were admitted after informed consent. All scans were performed on a 3T MR imaging system with SNAP, 2D time‐of‐flight and magnetization‐prepared 3D rapid acquisition gradient echo sequences. The SNAP sequence utilized a phase sensitive acquisition, and was designed to provide positive signals corresponding to intraplaque hemorrhage and negative signals corresponding to lumen. SNAP images were compared to time‐of‐flight images to evaluate lumen size measurements using linear mixed models and the intraclass correlation coefficient. Intraplaque hemorrhage identification accuracy was evaluated by comparing to magnetization‐prepared 3D rapid acquisition gradient echo images using Cohen's Kappa. Diagnostic quality SNAP images were generated from all subjects. Quantitatively, the lumen size measurements by SNAP were strongly correlated (intraclass correlation coefficient = 0.96,P< 0.001) with those measured by time‐of‐flight. For intraplaque hemorrhage detection, strong agreement (κ = 0.82,P< 0.001) was also identified between SNAP and magnetization‐prepared 3D rapid acquisition gradient echo images. In conclusion, a SNAP imaging technique was proposed and shows great promise for imaging both lumen size and carotid intraplaque hemorrhage with a single scan. Magn Reson Med, 2013. © 2012 Wiley Periodicals, Inc.
An efficient analyse phase for element problems
Authors: Hogg Jonathan D. , Scott Jennifer A. 
Published: March 2012

SUMMARYThe analyse phase of a sparse direct solver for symmetrically structured linear systems of equations is used to determine the sparsity pattern of the matrix factor. This allows the subsequent numerical factorisation and solve phases to be executed efficiently. Many direct solvers require the system matrix to be in assembled form. For problems arising from finite element applications, assembling and then using the system matrix can be costly in terms of both time and memory. This paper describes and implements a variant of the work of Gilbert, Ng and Peyton for matrices in elemental form. The proposed variant works with an equivalent matrix that avoids explicitly assembling the system matrix and exploits supervariables. Numerical experiments using problems from practical applications are used to demonstrate the significant advantages of working directly with the elemental form. Copyright © 2012 John Wiley & Sons, Ltd.
Granular control of photovoltaic arrays by means of a multi‐output Maximum Power Point Tracking algorithm
Authors: Petrone Giovanni , Ramos‐Paja Carlos Andrés , Spagnuolo Giovanni , Vitelli Massimo 
Published: March 2012

ABSTRACTIn this paper, a Distributed Maximum Power Point Tracking (D‐MPPT) approach in photovoltaic (PV) applications is discussed. The proposed control method is suitable for the granular control of the PV generator at a module level or even at a sub‐module level. D‐MPPT is usually implemented by means of independent converters, each one of them running its own MPPT algorithm. Instead, the architecture proposed in this paper consists of only one digital controller, implementing a multivariable MPPT algorithm based on the Perturb and Observe approach, acting on a number of dc/dc converters, each one of them dedicated to a single PV module. The proposed control strategy reduces the number of current sensors with respect to the classical D‐MPPT architecture and tracks the maximum power evaluated at the dc/dc converters' output. Planar solid immersion mirror simulations and experimental results confirm the validity of the approach and of the design guidelines proposed in the paper. Copyright © 2012 John Wiley & Sons, Ltd.
Assessment of domestic photovoltaic systems based on real options theory
Authors: Martinez‐Cesena Eduardo Alejandro , Azzopardi Brian , Mutale Joseph 
Published: March 2012

ABSTRACTIn the last decade, the financial attractiveness of photovoltaic (PV) systems has been increasing due to the rapid and constant improvements of PV technologies and the introduction of renewable energy support mechanisms. Under these circumstances, residential electricity consumers can benefit from investments in domestic PV systems. Investment decisions in PV systems can be assessed with well‐known discounted cash flows criteria such as the cost of energy and the net present value. These types of analyses either recommend abandoning the project or investing immediately. However, due to fast improvements in PV technologies, especially in the last few years, options to postpone investments in PV systems can be valuable. These options can be assessed with real options theory. This paper proposes a real options methodology for the assessment of domestic PV systems, considering the expected evolution of PV technologies and the option to delay investment. The methodology employs a normalization technique to illustrate, in a simple and intuitive manner, the convenience of the delay option. Two case studies based on real aggregated data for the UK are presented. The first case study illustrates the methodology, whereas the second is an extensive study meant to provide insights about investments in domestic PV systems in the UK. The results indicate the circumstances that drive and disincentivize investments in different PV technologies. Additionally, it is shown that the option to delay investment is a potential driver for investments in emerging organic‐based PV technologies. Copyright © 2012 John Wiley & Sons, Ltd.
Analysis of the Mean Diameters and Particle‐Size Distribution in Powders
Authors: González‐Tello Pedro , Camacho Fernando , Vicaria José. M. , González Pedro A. 
Published: March 2012

AbstractThe granulometric characterization of a pulverulent material requires quantification of the particle size and its distribution frequency. From these primary data, the mean size (mean diameters) of the pulverulent material is calculated and the data are adjusted to the distribution functions. In this study, the most frequent mean diameters are defined and calculated, and the application of the distribution functions to the experimental results is discussed. It is concluded that the Rosin‐Rammler distribution function and a modified Nukiyama‐Tanasawa function are the most suitable equations to fit the differential and the cumulative undersize distribution frequencies. This review is accompanied by calculations that illustrate the application of the equations related to this work.
Formation of a disorderd hetero‐junction by diffusion of CuI from CuSCN into In2S3 layers: A surface photovoltage study
Authors: Juma Albert , Kavalakkatt Jaison , Pistor Paul , Latzel Björn , Schwarzburg Klaus , Dittrich Thomas 
Published: March 2012

AbstractCharge‐selective disordered hetero‐junctions were formed in evaporated In2S3 layers by diffusing at 200 °C CuI from a CuSCN source. The thicknesses of In2S3 layers and diffusion times were varied between 5 and 80 nm and between 2 and 19 min, respectively. In some cases CuSCN layers were etched back with pyridine. Spectral and time‐dependent surface photovoltage measurements were carried out in the capacitor arrangement. It was observed that a competing process of charge separation and relaxation was initiated together with the formation of the charge‐selective In2S3/In2S3:Cu hetero‐junction.Modulated SPV amplitude for different annealing times and thicknesses of the evaporated In2S3 layers. magnified image
Vertically stacked and laterally ordered InP and In(Ga)As quantum dots for quantum gate applications
Authors: Koroknay Elisabeth , Schulz Wolfgang‐Michael , Richter Daniel , Rengstl Ulrich , Reischle Matthias , Bommer Moritz , Kessler Christian Alexander , Roßbach Robert , Schweizer Heinz , Jetter Michael , Michler Peter 
Published: March 2012

AbstractWe report on the epitaxial growth of vertically stacked InP and In(Ga)As quantum dot (QD) layers to realize a triple dot quantum gate structure consisting of an asymmetric control double dot and a single target dot suitable for a CNOT gate structure. Structural analysis as well as studies on the optical properties are presented. For studies on control dot structures we analyze the growth of InP islands in a GaInP barrier on (100) GaAs substrates. By stacking InP QD layers with intentional asymmetric design in QD size of each layer and adjustment of the barrier width between the double dots, coupling and control of the coupling via barrier layer width‐design can be demonstrated. For defined gate action single dot spectra of aligned dots are indispensable. Therefore QD density reduction is studied. We study two possibilities to affect the QD density and control the dot site by manipulating the surface potential of InP island nucleation. (i) Growth of InP islands on top of a low density In(Ga)As QD seed layer (ii) Growth of InP islands on patterned (100) GaAs substrates. We present microsphere photolithography in combination with wet chemical etching as a fast and low‐cost method to produce regular hole arrays in a GaAs surface, which are suitable for controlled nucleation of self‐assembled InP islands.
A bias‐corrected decomposition of the Brier score
Authors: Ferro C. A. T. , Fricker T. E. 
Published: March 2012

AbstractThe Brier score is a widely used measure of performance for probabilistic forecasts of event occurrences and is often decomposed additively into three terms that quantify the reliability and resolution of the forecasts and the uncertainty of the forecast events. The standard decomposition yields biased estimates of the large‐sample values of these three quantities: reliability is overestimated and uncertainty is underestimated, while resolution may be either overestimated or underestimated. An unbiased decomposition is shown to be unattainable but a new decomposition is proposed that has smaller biases and therefore provides a more accurate measure of forecast performance. The implications for the Brier skill score and the attributes diagram are discussed and results are illustrated with seasonal forecasts of sea‐surface temperatures. Copyright © 2012 Royal Meteorological Society
Gas‐phase reactivity of protonated 2‐oxazoline derivatives: mass spectrometry and computational studies
Authors: Vessecchi Ricardo , Tomaz José Carlos , Santos Guilherme Purcote dos , de Oliveira Alfredo R. Marques , Lopes Norberto Peporine , Clososki Giuliano Cesar 
Published: March 2012

RATIONALEOxazolines have attracted the attention of researchers worldwide due to their versatility as carboxylic acid protecting groups, chiral auxiliaries, and ligands for asymmetric catalysis. Electrospray ionization tandem mass spectrometric (ESI‐MS/MS) analysis of five 2‐oxazoline derivatives has been conducted, in order to understand the influence of the side chain on the gas‐phase dissociation of these protonated compounds under collision‐induced dissociation (CID) conditions.METHODSMass spectrometric analyses were conducted in a quadrupole time‐of‐flight (Q‐TOF) spectrometer fitted with electrospray ionization source. Protonation sites have been proposed on the basis of the gas‐phase basicity, proton affinity, atomic charges, and a molecular electrostatic potential map obtained on the basis of the quantum chemistry calculations at the B3LYP/6‐31 + G(d,p) and G2(MP2) levels.RESULTSAnalysis of the atomic charges, gas‐phase basicity and proton affinities values indicates that the nitrogen atom is a possible proton acceptor site. On the basis of these results, two main fragmentation processes have been suggested: one taking place via neutral elimination of the oxazoline moiety (99 u) and another occurring by sequential elimination of neutral fragments with 72 u and 27 u. These processes should lead to formation of R+.CONCLUSIONSThe ESI‐MS/MS experiments have shown that the side chain could affect the dissociation mechanism of protonated 2‐oxazoline derivatives. For the compound that exhibits a hydroxyl at the lateral chain, water loss has been suggested to happen through an E2‐type elimination, in an exothermic step. Copyright © 2012 John Wiley & Sons, Ltd.
Gas chromatography/isotope ratio mass spectrometry of recalcitrant target compounds: performance of different combustion reactors and strategies for standardization
Authors: Reinnicke Sandra , Juchelka Dieter , Steinbeiss Sibylle , Meyer Armin , Hilkert Andreas , Elsner Martin 
Published: March 2012

RATIONALECompound‐specific isotope analysis (CSIA) relies on continuous flow combustion of organic substances to CO2 and N2 in a miniature reactor to measure 13 C/12 C and 15 N/14 N stable isotope ratios. Accurate analysis is well established for many volatile hydrocarbons. In contrast, compounds which contain hetero and halogen atoms are less volatile and may be more recalcitrant to combustion.METHODSThis study tested carbon and nitrogen isotope analysis of atrazine, desethylatrazine (DEA), dichlobenil and 2,6‐dichlorobenzamide (BAM) by gas chromatography/isotope ratio mass spectrometry (GC/IRMS) with multiple reactor tubes of two different kinds (conventional CuO/NiO/Pt and a NiO tube/CuO‐NiO reactor prototype).RESULTSThe advantages of the NiO tube/CuO‐NiO reactor were the absence of an additional reduction reactor, the possibility of routine reoxidation in nitrogen isotope analysis, and reliable atrazine and DEA measurements over several hundred injections. In contrast, BAM analysis showed good accuracy for carbon, but notable variations in the trueness of nitrogen isotope ratios. Accurate carbon and nitrogen analysis was nevertheless possible by bracketing samples with external compound‐specific standards and subsequent offset correction.CONCLUSIONSWe conclude that instrument data should never be taken at its 'face value', but must consistently be validated with compound‐specific standards of the respective analytes. Copyright © 2012 John Wiley & Sons, Ltd.
Contribution of antibody production against neuraminidase to the protection afforded by influenza vaccines
Authors: Marcelin Glendie , Sandbulte Matthew R. , Webby Richard J. 
Published: March 2012

SUMMARYVaccines are instrumental in controlling the burden of influenza virus infection in humans and animals. Antibodies raised against both major viral surface glycoproteins, hemagglutinin (HA) and neuraminidase (NA), can contribute to protective immunity. Vaccine‐induced HA antibodies have been characterized extensively, and they generally confer protection by blocking the attachment and fusion of a homologous virus onto host cells. Although not as well characterized, some functions of NA antibodies in influenza vaccine‐mediated immunity have been recognized for many years. In this review, we summarize the case for NA antibodies in influenza vaccine‐mediated immunity. In the absence of well‐matched HA antibodies, NA antibodies can provide varying degrees of protection against disease. NA proteins of seasonal influenza vaccines have been shown in some instances to elicit serum antibodies with cross‐reactivity to avian‐origin and swine‐origin influenza strains, in addition to HA drift variants. NA‐mediated immunity has been linked to (i) conserved NA epitopes amongst otherwise antigenically distinct strains, partly attributable to the segmented influenza viral genome; (ii) inhibition of NA enzymatic activity; and (iii) the NA content in vaccine formulations. There is a potential to enhance the effectiveness of existing and future influenza vaccines by focusing greater attention on the antigenic characteristics and potency of the NA protein. Copyright © 2012 John Wiley & Sons, Ltd.
Rapid Magnetophoretic Separation of Microalgae
Authors: Lim Jit Kang , Chieh Derek Chan Juinn , Jalak Selah A. , Toh Pey Yi , Yasin Nur Hidayah Mat , Ng Bee Wah , Ahmad Abdul Latif 
Published: March 2012

AbstractMagnetic collection of the microalgae Chlorella sp. from culture media facilitated by low‐gradient magnetophoretic separation is achieved in real time. A removal efficiency as high as 99% is accomplished by binding of iron oxide nanoparticles (NPs) to microalgal cells in the presence of the cationic polyelectrolyte poly(diallyldimethylammonium chloride) (PDDA) as a binder and subsequently subjecting the mixture to a NdFeB permanent magnet with surface magnetic field ≈6000 G and magnetic field gradient <80 T m−1. Surface functionalization of magnetic NPs with PDDA before exposure to Chlorella sp. is proven to be more effective in promoting higher magnetophoretic removal efficiency than the conventional procedure, in which premixing of microalgal cells with binder is carried out before the addition of NPs. Rodlike NPs are a superior candidate for enhancing the magnetophoretic separation compared to spherical NPs due to their stable magnetic moment that originates from shape anisotropy and the tendency to form large NP aggregates. Cell chaining is observed for nanorod‐tagged Chlorella sp. which eventually fosters the formation of elongated cell clusters.