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Alternating
Kinds of Alternating Terms modified by Alternating Selected AbstractsPAIRED PREFERENCE TESTS: "50:50" AND "ALTERNATING" NO PREFERENCESJOURNAL OF SENSORY STUDIES, Issue 6 2008HAYDE ALFARO-RODRÍGUEZ ABSTRACT Because the concept of "No Preference" is ambiguous, two types of "No Preference" are defined: a "50:50" No Preference, defined operationally as consumers presented with both products having a 50% chance of choosing either, and an "Alternating" No Preference, where the probability is not 50%. The consumer would be more likely to choose one of the products. However, later, he or she might choose the other product. To investigate this, paired preference tests were performed with and without the "No Preference" option for various products. No discernible trend was noted for consumers who had chosen the "No Preference" option and distributed their votes among the preference options. These consumers and those who changed their preferences were classified according to the "50:50" No Preference and "Alternating" No Preference dichotomy accordingly. PRACTICAL APPLICATIONS Besides the tendency of consumers to report false preferences, paired preference tests have another problem: the concept of "No Preference" is ambiguous. It could mean that consumers liked both products equally and so would always have a 50% chance of choosing either. It could also mean that the probability is not 50% on any one occasion but varies so that one product is chosen on one occasion and the other product on another occasion. To avoid confusing the consumer so as to obtain more valid data, it is important to specify these two meanings of "No Preference." This study is a first step in that direction and should help consumers understand better the instructions for preference tests. [source] Application of Multivariate curve resolution-alternating least square methods on the resolution of overlapping CE peaks from different separation conditionsELECTROPHORESIS, Issue 20 2007Fang Zhang Abstract Discussed in this paper is the development of a new strategy to improve resolution of overlapping CE peaks by using second-order multivariate curve resolution with alternating least square (second-order MCR-ALS) methods. Several kinds of organic reagents are added, respectively, in buffers and sets of overlapping peaks with different separations are obtained. Augmented matrix is formed by the corresponding matrices of the overlapping peaks and is then analyzed by the second-order MCR-ALS method in order to use all data information to improve the precision of the resolution. Similarity between the resolved unit spectrum and the true one is used to assess the quality of the solutions provided by the above method. 3,4-Dihydropyrimidin-2-one derivatives (DHPOs) are used as model components and mixed artificially in order to obtain overlapping peaks. Three different impurity levels, 100, 20, and 10% relative to the main component, are used. With this strategy, the concentration profiles and spectra of impurities, which are no more than 10% of the main component, can be resolved from the overlapping peaks without pure standards participant in the analysis. The effects of the changes in the components spectra in the buffer with different organic reagents on the resolution are also evaluated, which are slight and can thus be ignored in the analysis. Individual data matrices (two-way data) are also analyzed by using MCR-ALS and heuristic evolving latent projections (HELP) methods and their results are compared with those when MCR-ALS is applied to augmented data matrix (three-way data) analysis. [source] Carbon Nanotube Composites: Hierarchical Composites of Single/Double-Walled Carbon Nanotubes Interlinked Flakes from Direct Carbon Deposition on Layered Double Hydroxides (Adv. Funct.ADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Mater. On page 677, M. Q. Zhao et al. report the fabrication of a hierarchical composite combining one-dimensional single/double walled carbon nanotubes (CNTs) and two-dimensional flakes through direct carbon deposition on layered double hydroxides. The composites can be easily transformed into continuously interlinked CNT layers alternating with calcined lamellar flakes structure. They are found to have the potential for applications in a number or areas, including as an excellent filler for strong polyimide film. [source] Hierarchical Composites of Single/Double-Walled Carbon Nanotubes Interlinked Flakes from Direct Carbon Deposition on Layered Double HydroxidesADVANCED FUNCTIONAL MATERIALS, Issue 4 2010Meng-Qiang Zhao Three-dimensional hierarchical nanocomposites consisting of one-dimensional carbon nanotubes (CNTs) and two-dimensional lamellar flakes (such as clay, layered double hydroxides) show unexpected properties for unique applications. To achieve a well-designed structure with a specific function, the uniform distribution of CNTs into the used matrix is a key issue. Here, it is shown that a hierarchical composite of single/double-walled CNTs interlinked with two-dimensional flakes can be constructed via in-situ CNT growth onto layered double hydroxide (LDH) flakes. Both the wall number and diameter of the CNTs and the composition of the flakes can be easily tuned by changing the proportion of the transition metal in the LDH flakes. Furthermore, a structure with continuously interlinked CNT layers alternating with lamellar flakes is obtained after compression. The hierarchical composite is demonstrated to be an excellent filler for strong polyimide films. This study indicates that LDH is an extraordinary catalyst for the fabrication of hierarchical composites with high-quality single/double-walled CNTs. The as-obtained CNTs/calcined LDHs nanocomposite is a novel structural platform for the design of mechanically robust materials, catalysts, ion-transportation, energy-conversion, and other applications. [source] Electric Field-Directed Convective Assembly of Ellipsoidal Colloidal Particles to Create Optically and Mechanically Anisotropic Thin FilmsADVANCED FUNCTIONAL MATERIALS, Issue 20 2009Manish Mittal Abstract A method of simultaneous field- and flow-directed assembly of anisotropic titania (TiO2) nanoparticle films from a colloidal suspension is presented. Titania particles are oriented by an alternating (ac) electric field as they simultaneously advect towards a drying front due to evaporation of the solvent. At high field frequencies (,,>,,25,kHz) and field strengths (E,>,300,V cm,1), the particles orient with their major axis along the field direction. As the front recedes, a uniform film with thicknesses of 1,10,µm is deposited on the substrate. The films exhibit a large birefringence (,n,,,0.15) and high packing fraction (,,=,0.75,±,0.08), due to the orientation of the particles. When the frequency is lowered, the particle orientation undergoes a parallel,random,perpendicular transition with respect to the field direction. The orientation dependence on field frequency and strength is explained by the polarizability of ellipsoidal particles using an interfacial polarization model. Particle orientation in the films also leads to anisotropic mechanical properties, which are manifested in their cracking patterns. In all, it is demonstrated that the field-directed assembly of anisotropic particles provides a powerful means for tailoring nanoparticle film properties in situ during the deposition process. [source] Red Ear Syndrome and Migraine: Report of Eight CasesHEADACHE, Issue 2 2002Vincenzo Raieli MD We describe eight idiopathic cases of red ear syndrome in seven children and one adult. All were migraineurs with a history of paroxysmally painful and red ear, unilateral or alternating, in isolation or associated with migraine attacks. The reported duration of these episodes varied from 30 minutes to 1 hour. Neurologic examination, brain MRI and CT scans, and x-rays of the cervical spine were normal. The close temporal relationship between the "red ear episodes" and migraine attacks suggests an association between the two conditions. [source] pH-Independent Recognition of the dG,,,dC Base Pair in Triplex DNA: 9-Deazaguanine N7 -(2,-Deoxyribonucleoside) and Halogenated Derivatives Replacing Protonated dCHELVETICA CHIMICA ACTA, Issue 4 2006Frank Seela Abstract Triplex-forming oligonucleotides (TFOs) containing 9-deazaguanine N7 -(2,-deoxyribonucleoside) 1a and halogenated derivatives 1b,c were synthesized employing solid-phase oligonucleotide synthesis. For that purpose, the phosphoramidite building blocks 5a,c and 8a,c were synthesized. Multiple incorporations of 1a,c in place of dC were performed within TFOs, which involved the sequence of five consecutive 1a,c,,,dG,,,dC triplets as well as of three alternating 1a,c,,,dG,,,dC and dT,,,dA,,,dT triplets. These TFOs were designed to bind in a parallel orientation to the target duplex. Triplex forming properties of these oligonucleotides containing 1a,c in the presence of Na+ and Mg2+ were studied by UV/melting-curve analysis and confirmed by circular-dichroism (CD) spectroscopy. The oligonucleotides containing 1a in the place of dC formed stable triplexes at physiological pH in the case of sequence of five consecutive 1a,,,dG,,,dC triplets as well as three alternating 1a,c,,,dG,,,dC and dT,,,dA,,,dT triplets. The replacement of 1a by 9-halogenated derivatives 1b,c further enhanced the stability of DNA triplexes. Nucleosides 1a,c also stabilized duplex DNA. [source] Marine and human activity influences on the groundwater quality of southern Korinthos area (Greece)HYDROLOGICAL PROCESSES, Issue 12 2003G. Stamatis Abstract In this paper the groundwater quality of the southern part of Korinthos region (north-east Peloponnese) is discussed. The geology is characterized by a thick sequence of Neogene marls alternating with sandstones, overlain by superficial Quaternary deposits. The latter consist of a mixture of loose materials such as conglomerates, marly sandstones, sands and clay to silty sands. The area is crossed by a fault system parallel to the coastline, and the Quaternary sediments have formed extended Tyrrhenian marine terraces. Two aquifers have been identified in the area. The first is unconfined and occurs within the Quaternary sediments whereas the other is a deep confined aquifer occurring within the underlying Neogene marl series. Analysis of hydrochemical evolution over the past 30 years has indicated significant deterioration of quality owing to seawater intrusion and nitrate pollution. The various sources of pollution have rendered, to a large extent, shallow groundwater unsuitable not only for potable water supply but also for irrigation purposes. However, this is not the case for the deeper confined aquifer. Statistical analysis was used to explore the evolution of salinization during the years 1968 and 1998. In view of the alarming conditions caused by the documented groundwater quality deterioration, the need for integrated water resources management is stressed to maintain the socio-economic growth of the region studied. Copyright © 2003 John Wiley & Sons, Ltd. [source] A reconfigurable DCS1800/W-CDMA LNA: Design and implementation issuesINTERNATIONAL JOURNAL OF RF AND MICROWAVE COMPUTER-AIDED ENGINEERING, Issue 1 2009Cristian Pavão Moreira Abstract The authors present in this article a dual-standard dual-mode low-noise amplifier (LNA) for DCS1800/W-CDMA-FDD applications. To save die area compared to conventional parallel LNAs, the authors have employed an alternative circuit configuration. It consists of sharing the most die consuming elements (inductances) in both operation standards, enabling a more compact solution. The standard selection is performed through a bias scheme (MOS switches) that allows alternating between the two involved standards. The LNA die area is 1.0 × 1.2 mm2 and it consumes 6.8 mW (3.8 mA under 1.8 V), including bias circuitry. © 2008 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2009. [source] In situ X-ray diffraction analysis of (CFx)n batteries: signal extraction by multivariate analysisJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 6 2007Mark A. Rodriguez (CFx)n cathode reaction during discharge has been investigated using in situ X-ray diffraction (XRD). Mathematical treatment of the in situ XRD data set was performed using multivariate curve resolution with alternating least squares (MCR,ALS), a technique of multivariate analysis. MCR,ALS analysis successfully separated the relatively weak XRD signal intensity due to the chemical reaction from the other inert cell component signals. The resulting dynamic reaction component revealed the loss of (CFx)n cathode signal together with the simultaneous appearance of LiF by-product intensity. Careful examination of the XRD data set revealed an additional dynamic component which may be associated with the formation of an intermediate compound during the discharge process. [source] Effect of an organic dicarboxylic acid salt on fractionated crystallization of polypropylene dropletsJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2007Y. Jin Abstract The effect of a particulate nucleating agent on fractionated crystallization of polypropylene (PP) was studied. A novel method utilizing breakup of PP nanolayers was used to obtain a dispersion of PP droplets in a polystyrene (PS) matrix. An assembly with hundreds of PP nanolayers alternating with thicker PS layers was fabricated by layer-multiplying coextusion. The concentration of an organic dicarboxylic acid salt (HPN) nucleating agent in the coextruded PP nanolayers was varied up to 2 wt %. When the assembly was heated into the melt, interfacial driven breakup of the thin PP layers produced a dispersion of PP particles in a PS matrix. Analysis of optical microscope images and atomic force microscope images indicated that layer breakup produced a bimodal particle size distribution of submicron particles and large, micron-sized particles. Almost entirely submicron particles were obtained from breakup of 12 nm PP layers. The fraction of PP as submicron particles dropped dramatically as the PP nanolayer thickness increased to 40 nm. Only large, micron-sized particles were obtained from 200 nm PP nanolayers. The crystallization behavior of the particle dispersions was characterized by thermal analysis and wide angle X-ray diffraction. Only part of the PP was nucleated by HPN. It was found that HPN was not effective in nucleating the population of submicron particles. The particulate HPN was too large to be accommodated in the submicron PP particles. On the other hand, the amount of nucleated crystallization qualitatively paralleled the fraction of PP in the form of large, micron-sized particles. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2007 [source] Why are maximizers less happy than satisficers?JOURNAL OF BEHAVIORAL DECISION MAKING, Issue 2 2010Because they maximize positive, negative outcomes Abstract Although extant research suggests maximizing is related to objectively positive outcomes (e.g., job offers), I propose maximizing may be simultaneously and positively related to objectively negative outcomes (e.g., job rejections). Specifically, I argue maximizers bear more instances of positive and negative outcomes than satisficers, and that in spite of their positive outcomes,yet because of their negative outcomes,maximizers are less happy than satisficers. In Study 1, participants took the alternate uses test; as expected, maximizing was related to seeking alternatives, yet, maximizing was also related to seeking low-quality alternatives. Moreover, the number of low-quality alternatives partially mediated the relationship between maximizing and negative affect. In Study 2, the impact of maximizing on experiencing negative affect was further assessed by examining whether maximizing is related to seeking and choosing low-quality alternatives. Participants played the Iowa Gambling Task; it was found maximizing was related to alternating among decks, and in particular, sampling bad decks; ultimately, maximizing was related to winning less money, and experiencing more negative affect. Finally, in Study 3, participants responded to questionnaires about positive and negative life outcomes; it was found that maximizing was simultaneously related to experiencing more positive and more negative outcomes, and that negative outcomes predicted happiness to a greater degree than positive outcomes. These findings suggest an irony of maximizing: It produces both positive and negative outcomes, contributing to literature explaining why maximizers are less happy than satisficers, and ultimately whether happiness is a matter of choice. Copyright © 2009 John Wiley & Sons, Ltd. [source] Patterns of Accelerated Junctional Rhythm During Slow Pathway Catheter Ablation for Atrioventricular Nodal Reentrant Tachycardia: Temperature Dependence, Prognostic Value, and Insights into the Nature of the Slow PathwayJOURNAL OF CARDIOVASCULAR ELECTROPHYSIOLOGY, Issue 3 2000ALAN B. WAGSHAL M.D. Slow Pathway Accelerated Junctional Rhythm. Introduction: Although accelerated junctional rhythm (AJR) is a knuwn marker for successful slow pathway (SP) ablation sites. AJR may just be a regional effect of the anisotropic conduction properties of this area of the heart. We believe that detailed assessment of the AJR might provide insight into the SP specificity of this AJR and perhaps the nature of the SP itself. Methods and Results: Our ablation protocol consisted of 30-second, 70°C temperature-controlled ablation pulses with assessment after each pulse. Serial booster ablations were performed at the original successful site and at least 2 to 3 nearby sites to assess for residual AJR after the procedure in 50 consecutive SP ablations. We defined three distinct patterns of AJR: continuous AJR that persisted until the end of energy delivery (group 1, 25 patients); alternating or "stuttering" AJR that persisted throughout energy delivery (group II, 9 patients); and AJR that ended abruptly during energy delivery (group III, 16 patients). Mean ablation temperatures in the three groups was 57°± 5°C, 54°± 5°C, and 63°± 5°C, respectively (P = 0.0002 for groups I and II vs group III). Ten of 34 (29%) patients in groups I and II ("low-temperature ablation") exhibited residual SP (jump and/or single echo heats) despite tachycardia noninducibility, and 25 of 34 (73%) patients had residual AJR during the booster ablations, but neither of these was seen in any group III patients. Conclusion: Ablation temperature correlates with the pattern of AJR produced during SP ablation. That higher temperature lesions simultaneously abolish all SP activity as well as the focus of AJR suggests that this AJR is specific for the SP and is not a nonspecific regional effect. [source] Flow and mass transfer in aerated viscous Newtonian liquids in an unbaffled agitated vessel having alternating forward,reverse rotating impellersJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 11 2001Masanori Yoshida Abstract Flow and mass transfer characteristics in aerated viscous Newtonian liquids were studied for an unbaffled aerated agitated vessel with alternating rotating impellers (AAVAI), ie with multiple forward,reverse rotating impellers having four delta blades. The effects of operating conditions such as gas sparging rate, agitation rate and the number of impeller stages, and the liquid physical properties (viscosity) on the gas hold-up, ,gD, and volumetric oxygen transfer coefficient, kLaD were evaluated experimentally. The dependences of ,gD and kLaD on the specific total power input and superficial gas velocity differed, depending on the ranges of liquid viscosity. Empirical relationships are presented for each viscosity range to predict ,gD and kLaD as a function of the specific total power input, superficial gas velocity and viscosity of liquid. Based on a comparative investigation of the volumetric coefficient in terms of the specific total power input between the AAVAI and conventional aerated agitated vessels (CAAVs) having unidirectionally rotating impellers, the usefulness of AAVAI as a gas,liquid agitator treating viscous Newtonian liquids is also discussed. © 2001 Society of Chemical Industry [source] A fully robust PARAFAC method for analyzing fluorescence dataJOURNAL OF CHEMOMETRICS, Issue 3 2009Sanne Engelen Abstract Parallel factor analysis (PARAFAC) is a widespread method for modeling fluorescence data by means of an alternating least squares procedure. Consequently, the PARAFAC estimates are highly influenced by outlying excitation,emission landscapes (EEM) and element-wise outliers, like for example Raman and Rayleigh scatter. Recently, a robust PARAFAC method that circumvents the harmful effects of outlying samples has been developed. For removing the scatter effects on the final PARAFAC model, different techniques exist. Newly, an automated scatter identification tool has been constructed. However, there still exists no robust method for handling fluorescence data encountering both outlying EEM landscapes and scatter. In this paper, we present an iterative algorithm where the robust PARAFAC method and the scatter identification tool are alternately performed. A fully automated robust PARAFAC method is obtained in that way. The method is assessed by means of simulations and a laboratory-made data set. Copyright © 2009 John Wiley & Sons, Ltd. [source] Fast algorithm for the solution of large-scale non-negativity-constrained least squares problemsJOURNAL OF CHEMOMETRICS, Issue 10 2004Mark H. Van Benthem Abstract Algorithms for multivariate image analysis and other large-scale applications of multivariate curve resolution (MCR) typically employ constrained alternating least squares (ALS) procedures in their solution. The solution to a least squares problem under general linear equality and inequality constraints can be reduced to the solution of a non-negativity-constrained least squares (NNLS) problem. Thus the efficiency of the solution to any constrained least square problem rests heavily on the underlying NNLS algorithm. We present a new NNLS solution algorithm that is appropriate to large-scale MCR and other ALS applications. Our new algorithm rearranges the calculations in the standard active set NNLS method on the basis of combinatorial reasoning. This rearrangement serves to reduce substantially the computational burden required for NNLS problems having large numbers of observation vectors. Copyright © 2005 John Wiley & Sons, Ltd. [source] Noise propagation and error estimations in multivariate curve resolution alternating least squares using resampling methodsJOURNAL OF CHEMOMETRICS, Issue 7-8 2004Joaquim Jaumot Abstract Different approaches for the calculation of prediction intervals of estimations obtained in multivariate curve resolution using alternating least squares optimization methods are explored and compared. These methods include Monte Carlo simulations, noise addition and jackknife resampling. Obtained results allow a preliminary investigation of noise effects and error propagation on resolved profiles and on parameters estimated from them. The effect of noise on rotational ambiguities frequently found in curve resolution methods is discussed. This preliminary study is shown for the resolution of a three-component equilibrium system with overlapping concentration and spectral profiles. Copyright © 2004 John Wiley & Sons, Ltd. [source] Monitoring of a second-order reaction by electronic absorption spectroscopy using combined chemometric and kinetic modelsJOURNAL OF CHEMOMETRICS, Issue 6 2003Tom J. Thurston Abstract This paper reports the application of 11 methods for obtaining kinetic constants from a second-order reaction, that between phenylhydrazine and benzophenone. In this type of reaction the number of absorbing species is lower than the number of steps in the reaction minus one, resulting in a rank-deficient response matrix. The methods used include traditional univariate curve fitting, classical least squares using previously recorded pure spectra, alternating least squares methods with both kinetic and non-negativity constraints, and target-testing methods using principal component scores. An additional recently proposed method based on difference spectra is also examined, suitable for any single-step closed reaction. The methods that performed best were difference spectra, kinetically constrained alternating least squares, and target-testing approaches. Limitations of the traditional methods are described. Copyright © 2003 John Wiley & Sons, Ltd. [source] Application of equality constraints on variables during alternating least squares proceduresJOURNAL OF CHEMOMETRICS, Issue 12 2002Mark H. Van Benthem Abstract We describe several methods of applying equality constraints while performing procedures that employ alternating least squares. Among these are mathematically rigorous methods of applying equality constraints, as well as approximate methods, commonly used in chemometrics, that are not mathematically rigorous. The rigorous methods are extensions of the methods described in detail in Lawson and Hanson's landmark text on solving least squares problems, which exhibit well-behaved least squares performance. The approximate methods tend to be easy to use and code, but they exhibit poor least squares behaviors and have properties that are not well understood. This paper explains the application of rigorous equality-constrained least squares and demonstrates the dangers of employing non-rigorous methods. We found that in some cases, upon initiating multivariate curve resolution with the exact basis vectors underlying synthetic data overlaid with noise, the approximate method actually results in an increase in the magnitude of residuals. This phenomenon indicates that the solutions for the approximate methods may actually diverge from the least squares solution. Copyright © 2002 John Wiley & Sons, Ltd. [source] Pseudo alternating least squares algorithm for trilinear decompositionJOURNAL OF CHEMOMETRICS, Issue 3 2001Zeng-Ping Chen Abstract In chemistry, PARAFAC is one of the most widely used algorithms for trilinear decomposition. However, the problem of PARAFAC requiring an accurate estimation of the number of factors in the system under study limits its applications to some extent. This troublesome problem has been tackled by the pseudo alternating least squares (PALS) algorithm designed in this paper. PALS is a unique algorithm which tries to alternately optimize three different objective functions to obtain the solutions for the trilinear decomposition model. It has the outstanding feature of being resistant to the influence of N (the number of factors chosen in calculation), which has been proved mathematically under some mild conditions. Although the optimization procedure of PALS is different from that of PARAFAC, an alternating least squares scheme, and hinders a straightforward analysis of its convergence properties, studies on simulated as well as real data arrays reveal that PALS can often converge to satisfactory results within a reasonable computation time, even if excess factors are used in calculation. Copyright © 2001 John Wiley & Sons, Ltd. [source] TEXTURE STABILITY OF HYDROGEL COMPLEX CONTAINING CURDLAN GUM OVER MULTIPLE FREEZE,THAW CYCLESJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 1 2009PATRICK D. WILLIAMS ABSTRACT The texture stability of hydrogel complexes containing curdlan gum over multiple freeze,thaw cycles (FTCs) was investigated. The hydrogels formed by curdlan and xanthan gum, locust bean gum, carrageenan or guar gum at various combinations were stored at 4C for 24 h before subjected to five FTCs alternating between,16 (18 h) and 25C (6 h). Xanthan/curdlan hydrogels showed the highest freeze,thaw stability in terms of syneresis, heat stability and adhesiveness. The viscosity of xanthan/curdlan combination was the lowest among all samples studied yet the most stable over the five FTCs, whereas significant changes were observed with locust bean/curdlan hydrogels. The guar/curdlan combination before freeze,thaw treatments exhibited predominant elasticity; however, as the cycles progressed the elasticity decreased. The most stable gel strength was achieved when curdlan was combined with guar or xanthan at 2% (w/v) total concentration, while carrageenan/curdlan gels were the least stable. PRACTICAL APPLICATIONS Texture instability remains the most significant challenge for frozen food products, especially with inevitable post-production temperature fluctuations. Loss of moisture and changes in textural attributes often results in significant reduction of product quality. Precise control of hydrogel complexes that provide texture stabilization over multiple freeze,thaw cycles will enhance the quality of existing products while enabling the development of new ones. [source] fMRI studies of sensitivity and habituation effects within the auditory cortex at 1.5 T and 3 TJOURNAL OF MAGNETIC RESONANCE IMAGING, Issue 4 2006Kerstin Rabe MD Abstract Purpose To assess habituation effects in relation to field strength by fMRI at 1.5 vs. 3.0 T within the auditory cortex of healthy subjects. Materials and Methods fMRI experiments were performed on 19 healthy subjects at 1.5 T (N = 12) and 3 T (N = 12). The auditory cortex was stimulated binaurally by digitally generated pulsed (, = 5 Hz) 800 Hz sine tones with three alternating on and off periods. Results The mean activation after stimulation (4.4% ± 1.2% (1.5 T) and 5.3% ± 2.3% (3 T)) and number of activated pixels (96.7 ± 49.8 (1.5 T) and 139.9 ± 101 (3 T)) were higher at 3 T compared to 1.5 T; however, that difference did not reach statistical significance. A characteristic signal decay with repeated stimuli was revealed at both 1.5 and 3 T, and the response to the second and third stimulation blocks was significantly lower compared to the first. The habituation pattern was the same, independently of field strength and age. Conclusion The mean activation and number of pixels were only modestly higher at 3 T, probably due to higher physiologic noise and higher local macroscopic susceptibility gradients within the temporal lobes at 3 T. Our data reveal that measured auditory habituation is independent of field strength, and data obtained at two different field strengths do not differ fundamentally in this context. J. Magn. Reson. Imaging 2006. © 2006 Wiley-Liss, Inc. [source] Multi-component analysis: blind extraction of pure components mass spectra using sparse component analysisJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 9 2009Ivica Kopriva Abstract The paper presents sparse component analysis (SCA)-based blind decomposition of the mixtures of mass spectra into pure components, wherein the number of mixtures is less than number of pure components. Standard solutions of the related blind source separation (BSS) problem that are published in the open literature require the number of mixtures to be greater than or equal to the unknown number of pure components. Specifically, we have demonstrated experimentally the capability of the SCA to blindly extract five pure components mass spectra from two mixtures only. Two approaches to SCA are tested: the first one based on ,1 norm minimization implemented through linear programming and the second one implemented through multilayer hierarchical alternating least square nonnegative matrix factorization with sparseness constraints imposed on pure components spectra. In contrast to many existing blind decomposition methods no a priori information about the number of pure components is required. It is estimated from the mixtures using robust data clustering algorithm together with pure components concentration matrix. Proposed methodology can be implemented as a part of software packages used for the analysis of mass spectra and identification of chemical compounds. Copyright © 2009 John Wiley & Sons, Ltd. [source] Protein identification by peptide mass fingerprinting and peptide sequence tagging with alternating scans of nano-liquid chromatography/infrared multiphoton dissociation Fourier transform ion cyclotron resonance mass spectrometryJOURNAL OF MASS SPECTROMETRY (INCORP BIOLOGICAL MASS SPECTROMETRY), Issue 12 2003Toshiyuki Kosaka Abstract We have developed a method for protein identification with peptide mass fingerprinting and sequence tagging using nano liquid chromatography (LC)/Fourier transform ion cyclotron resonance mass spectrometry (FTICR-MS). To achieve greater sensitivity, a nanoelectrospray (nano-ES) needle packed with reversed-phase medium was used and connected to the nano-ES ion source of the FTICR mass spectrometer. To obtain peptide sequence tag information, infrared multiphoton dissociation (IRMPD) was carried out in nano-LC/FTICR-MS analysis. The analysis involves alternating nano-ES/FTICR-MS and nano-ES/IRMPD-FTICR-MS scans during a single LC run, which provides sets of parent and fragment ion masses of the proteolytic digest. The utility of this alternating-scan nano-LC/IRMPD-FTICR-MS approach was evaluated by using bovine serum albumin as a standard protein. We applied this approach to the protein identification of rat liver diacetyl-reducing enzyme. It was demonstrated that this enzyme was correctly identified as 3-,-hydroxysteroid dehydrogenase by the alternating-scan nano-LC/IRMPD-FTICR-MS approach with accurate peptide mass fingerprinting and peptide sequence tagging. Copyright © 2003 John Wiley & Sons, Ltd. [source] Health-related quality of life and symptom classification in patients with irritable bowel syndromeJOURNAL OF NURSING AND HEALTHCARE OF CHRONIC ILLNE SS: AN INTERNATIONAL INTERDISCIPLINARY JOURNAL, Issue 1 2010Graeme D Smith smith gd, steinke dt, penny ki, kinnear m & penman id (2010) Journal of Nursing and Healthcare of Chronic Illness2, 4,12 Health- related quality of life and symptom classification in patients with irritable bowel syndrome Background., Previous research has established that health-related quality of life can be adversely affected by irritable bowel syndrome IBS. Irritable bowel syndrome has been classified to subgroups by predominant bowel symptom: constipation, diarrhoea or alternating between the two. Little is presently known about the specific impact of irritable bowel syndrome on health-related quality of life within disease sub-groups across time. Aims., To examine the health-related quality of life in a cohort of individuals with irritable bowel syndrome to explore the association between quality of life and disease subtype classification. Setting., The general population of the UK. Design., Longitudinal cohort survey was conducted. Methods., Individuals with symptoms of irritable bowel syndrome were recruited via a UK-wide newspaper advertisement. The health-related quality of life was measured using a battery of validated questionnaires. Results., Data on 494 participants with a Rome II confirmed diagnosis of irritable bowel syndrome were examined. Measurement of generic health-related quality of life revealed lower median scores (poorer quality of life) in anxiety/depression and pain/discomfort domains of health. Conclusion., Health-related quality of life is impaired in community based individuals with IBS. Patients appear to fluctuate between sub-groups when irritable bowel syndrome is classified across time. This study suggests that the impact of irritable bowel syndrome may be greatly underestimated. Relevance for clinical practice., The use of sub-group classification and understanding of predictive factors may allow for a more flexible and efficient approach to healthcare assessment and patient care for people with irritable bowel syndrome. [source] TEMPESTITE DEPOSITS ON A STORM-INFLUENCED CARBONATE RAMP: AN EXAMPLE FROM THE PABDEH FORMATION (PALEOGENE), ZAGROS BASIN, SW IRANJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2004H. Mohseni The Pabdeh Formation is part of a thick carbonate-siliciclastic succession in the Zagros Basin of SW Iran which includes carbonate reservoirs of Cretaceous and Cenozoic ages. From field observations and petrographic and facies analysis of exposures in the type section of the Pabdeh Formation, four lithofacies were recognized. These are from oldest to youngest: (i) a mottled, bioturbated bioclastic wackestone/mudstone facies; (ii) a wackestone/packstone facies with horizontal burrows on bedding planes; (iii) a thin-bedded bioclastic wackestone/mudstone facies alternating with thin bioclastic-oolitic-intraclastic intervals; and (iv) a bioclastic foraminiferal / algal / peloidal packstone facies. These observations indicate that facies evolved upwards from deep outer-ramp deposits to inner-ramp deposits within a shoal complex, suggesting progradation of the ramp depositional system. Storm events significantly influenced the ramp system. Storm-generated surges transported sediments from nearshore to the deeper outer-ramp environment where they were deposited as shell-lags, composed mostly of bioclastic packstones, rich in pelagic microfauna with sharp, undulatory erosional basal contacts. The packstones rest on outer ramp mudstones deposited below storm base level. Sedimentary structures in the Pabdeh Formation are those typical of storm deposits, such as hummocky cross-stratification, ripple cross-lamination, ripple marks, escape burrows on the tops of the beds, couplets of fine- and coarse-grained laminae and mixed fauna, as well as intraclasts derived from underlying facies. These distinctive sequences are interpreted to have been generated by waning storm-generated currents. The dominance of fine-grained sediments (medium to fine sand); the lack of large- scale hummocky cross-stratification; the minor amounts of intraclasts derived from underlying facies; the paucity of amalgamated tempestite beds; and the finely-laminated (mm to cm scale) couplets of coarse and fine lamina all suggest a distal tempestite facies. Palaeogeographic reconstruction of the Zagros Basin during the Eocene indicates that the study area was situated in tropical, storm-dominated palaeolatitudes. [source] Multivariate chemometric approach to thermal solid-state FT-IR monitoring of pharmaceutical drug compoundJOURNAL OF PHARMACEUTICAL SCIENCES, Issue 8 2008Wei Jian Tan Abstract The study of thermal-related solid-state reaction monitored by spectroscopic method needs the use of advanced multivariate chemometric approach. It is because visual inspection of spectral data on particular functional groups or spectral bands is difficult to reveal the complete physical and chemical information. The spectral contributions from various species involved in the solid-state changes are generally highly overlapping and the spectral differences between reactant and product are usually quite minute. In this article, we demonstrate the use of multivariate chemometric approach to resolve the in situ thermal-dependent Fourier-transform infrared (FT-IR) mixture spectra of lisinopril dihydrate when it was heated from 24 to 170°C. The collected FT-IR mixture spectra were first subjected to singular value decomposition (SVD) to obtain the right singular vectors. The right singular vectors were rotated into a set of pure component spectral estimates based on entropy minimization and spectral dissimilarity objective functions. The resulting pure component spectral estimates were then further refined using alternating least squares (ALS). In current study, four pure component spectra, that is, lisinopril dihydrate, monohydrate, anhydrate, and diketopiperazine (DKP) were all resolved and the relative thermal-dependent contributions of each component were also obtained. These relative contributions revealed the critical temperature for each transformation and degradation. This novel approach provides better interpretation of the pathway of dehydration and intramolecular cyclization of lisinopril dihydrate in the solid state. In addition, it can be used to complement the information obtained from differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). © 2007 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 97: 3379,3387, 2008 [source] Intensity and Duration of Chronic Ethanol Exposure Is Critical for Subsequent Escalation of Voluntary Ethanol Drinking in MiceALCOHOLISM, Issue 11 2009William C. Griffin III Background:, Excessive alcohol drinking continues to be an important health problem. Recent studies from our laboratory and others have demonstrated that animal models of ethanol dependence and relapse can contribute to understanding factors that contribute to excessive drinking. In this study, we tested the hypothesis that the amount and duration of ethanol exposure is critical for promoting the escalation in drinking by mice given access to ethanol in a limited access paradigm. Methods:, We used several methods of chronic intermittent ethanol exposure in male C57BL/6J mice that would vary in the amount and duration of exposure to ethanol as indicated by blood ethanol concentrations (BEC). After establishing baseline drinking in the mice using a 2 hours, 2 bottle choice drinking paradigm, each study involved alternating between periods of ethanol exposure and periods of limited access to ethanol (1 cycle) for a total of 3 cycles. In Study 1, mice were allowed extended access (16 hours) to ethanol for oral consumption or remained in the home cage. In Study 2, the ethanol exposure consisted of intragastric gavage of increasing doses of ethanol or isocaloric sucrose as the control. Study 3 compared intragastric gavage combined with pyrazole, an alcohol dehydrogenase inhibitor, with vapor inhalation of ethanol using procedures known to lead to increased drinking in mice. Finally, Study 4 was a retrospective review of several studies conducted in our laboratory using inhalation procedures. The retrospective review encompassed a range of postvapor chamber BEC values and ethanol intakes that would allow a relationship between increased drinking and BEC to be examined. Results:, Allowing mice to drink for longer periods of time did not cause increased drinking in subsequent limited access sessions. Likewise, gastric intubation of ethanol which produced high BEC (>300 mg/dl) with or without pyrazole did not increase drinking. Only the vapor inhalation procedure, which was associated with sustained BEC above 175 mg/dl for the entire exposure period resulted in increased drinking. The retrospective study provided further evidence that sustained BEC levels above 175 mg/dl was critical to the escalation in drinking. Conclusions:, We found that the intensity (amount) and duration of ethanol exposure, indexed by BEC, is critical to produce increased drinking in mice. Specifically, BEC must regularly exceed 175 mg/dl for the escalation in drinking to occur. Future studies will examine neurobiological adaptations that may underlie the increased drinking behavior caused by chronic intermittent ethanol exposure. [source] Synthesis and properties of poly(carbonate-urethane) consisting of alternating carbonate and urethane moietiesJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2006Bungo Ochiai Abstract Poly(carbonate-urethane) consisting of alternating carbonate and urethane moieties (poly(HC-MDI)) was prepared by polyaddition of 4,4,-diphenylmethane diisocyanate (MDI) and a monocarbonate diol bis(3-hydroxypropyl)carbonate (HC), prepared by hydrolysis of a six-membered spiroorthocarbonate 1,5,7,11-tetraoxa-spiro[5.5]undecane. The polyaddition proceeds without concomitant side reactions including carbonate exchange reaction and affords the desired poly(carbonate-urethane). The hydrolysis and thermal behaviors of poly(HC-MDI) were compared with those of the analogous polyurethane carrying no carbonate structure (poly(ND-MDI)) prepared from MDI and 1,9-nonanediol (ND). Although the glass transition behaviors are almost identical, poly(HC-MDI) is less crystalline than poly(ND-MDI). Poly(HC-MDI) is more susceptible to hydrolysis than poly(ND-MDI) probably due to the higher polarity and the lower crystallinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 2802,2808, 2006 [source] Synthesis and characterization of new alternating, amphiphilic, comblike copolymers of poly(ethylene oxide) macromonomer and N -phenylmaleimideJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 3 2005Luminita Cianga Abstract A surface-active p -vinyl benzyloxy-,-hydroxy-poly(ethylene oxide) macromonomer containing 22 pendant structural units of ethylene oxide (St,PEO22) was synthesized with an initiation method. Because of its solubility in a large variety of solvents, the free-radical copolymerization with electron-acceptor N -phenylmaleimide (NPMI) was performed at 60 °C in benzene and tetrahydrofuran (THF) as isotropic media and in a water,THF mixture or water as a heterogeneous medium. Oil-soluble 2,2,-azobisisobutyronitrile and water-soluble 4,4,-azobis(4-cyanovaleric acid) were used as the initiators at fixed concentrations. Two different St,PEO22/NPMI comonomer ratios (1/1 and 3/7) at a fixed total comonomer concentration in the polymerization system were used. The structures, compositions, and microstructure peculiarities of the obtained alternating, amphiphilic, comblike copolymers were determined by NMR analysis. For the copolymers synthesized in hydrophilic media, differential scanning calorimetry showed, near the endothermic peak attributed to the melting of the poly(ethylene oxide) side chains, the presence of a second peak due to the partially ordered phase that could exist between the crystalline state and the isotropic melt. Also, the thermal stability of the obtained copolymers was studied with thermogravimetric analysis. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 479,492, 2005 [source] | ||||||||||||||||||||||||||||||||||||||||