bluuebunny/crossref_metadata_2025 huggingface dataset:
Molybdate Sulfuric Acid/NaNO2: A Novel Heterogeneous System for the N‐Nitrosation of Secondary Amines under Mild Conditions
Authors: Montazerozohori Morteza , Karami Bahador
Published: December 2006

Wet molybdate sulfuric acid (= dioxo[bis(sulfato‐κO)]molybdenum; MSA), a new solid acid, can be used in combination with sodium nitrite (NaNO2) to transform a variety of secondary amines to the corresponding N‐nitroso compounds under mild, heterogeneous conditions (Table). The process has several advantages: the reagents are inexpensive and non‐hazardous, the reaction is clean, fast, and high‐yielding, and MSA can be readily removed by filtration and re‐used (after treatment with HCl) without loss of activity. Further, only N‐nitrosation was observed, but no C‐ or O‐nitrosation.
Voltammetry as Virtual Potentiometric Sensor in Modelling of a Metal/Ligand System and Refinement of Stability Constants. Part 5
Authors: Cukrowski Ignacy , Magampa Philemon , Mkwizu Tumaini Samuel
Published: December 2006

The concept of virtual potential (employed here in modelling operations), a unique experimental setup designed and built in our laboratories, and new regression equations derived for nonlinear fitting of quasi‐reversible direct‐current polarograms were combined with the existing rigorous treatment and refinement of polarographic data to establish reliable metal/ligand models and accurate stability constants for the lead(II)/glycine/OH− and lead(II)/sarcosine/OH− systems (sarcosine = N‐methylglycine). In the case of glycine, the complexes [M(HL)], [ML], [ML2], and [ML3] were identified, and their stability constants (as log β) were established to be 10.51 ± 0.06, 4.58 ± 0.02, 7.19 ± 0.10, and 9.27 ± 0.02, respectively, the complex [ML3] being reported here for the first time (Table 2). The system with sarcosine involving [M(HL)], [ML], [ML2], [ML3], and [ML2(OH)2], with the stability constants (as log β) 11.01 ± 0.04, 4.18 ± 0.03, 7.23 ± 0.03, 9.1 ± 0.3, and 15.97 ± 0.07, respectively, is reported for the first time (Table 3). The log K1 value for PbII with sarcosine is a fraction of a log unit smaller when compared with the PbII complex with glycine, in agreement with the literature data for CuII, NiII, and ZnII showing the same trend for these two ligands. The proposed nonlinear curve‐fitting operations expand the applicability of polarography to study reliably and conveniently quasi‐reversible, on the polarographic time scale, metal/ligand systems (systems with involved heterogeneous kinetics).
Three New Triterpenoids from Dracocephalum forrestii
Authors: Li Gan‐Peng , Zhao Jing‐Feng , Yang Li‐Juan , Yang Xiao‐Dong , Li Liang
Published: December 2006

From the whole plant of Dracocephalum forrestii (Labiatae), three new and nine known triterpenoids were isolated. The new compounds were identified as (3β,18β)‐20,28‐epoxy‐3‐hydroxyurs‐21‐en‐28‐one (1), (3β,18β)‐urs‐21‐ene‐3,20,28‐triol (2), and (3β,18α,19α)‐ursane‐3,20,28‐triol (3) by means of in‐depth spectroscopic analysis.
A New Robust and Highly Sensitive FRET Donor–Acceptor Pair: Synthesis, Characterization, and Application in a Thrombin Assay
Authors: Kainmüller Eva K. , Bannwarth Willi
Published: December 2006

The synthesis of a new, robust fluorescence‐resonance‐energy‐transfer (FRET) system is described. Its donor chromophore is derived from an N‐allyl‐substituted quinolinone attached to 4‐bromophenylalanine via Heck cross‐coupling. The resulting Fmoc‐protected derivative 11 was used as building block in solid‐phase peptide synthesis (SPPS). As FRET acceptor, a sulfonylated ruthenium(II)–bathophenanthroline complex with a peripheral COOH function was prepared for covalent attachment to target molecules. The UV/VIS absorption and emission spectra of peptides bearing only the donor (D) or acceptor (A) dye showed a good overlap of the emission band of the donor with the absorption band of the acceptor. The fluorescence spectra of a peptide bearing both dyes revealed an additional emission after excitation of the donor, which is due to indirect excitation of the acceptor via FRET. The long fluorescence lifetime of the RuII complex (0.53 μs) makes it well‐suited for time‐resolved measurements. As a first application of this new FRET system, the peptide 18, with the recognition sequence for the protease thrombin, flanked by the two dyes, was synthesized and successfully cleaved by the enzyme. The change in the ratio of the fluorescence intensities could be determined.
Use of experimental design method to investigate metal ion effects in yeast fermentations
Authors: Tosun Ayşe , Ergun Mübeccel
Published: December 2006

The dependence of ethanol production by fermentation using Saccharomyces cerevisiae 251 TP(3‐2) on zinc, sodium and potassium ion concentration was studied with the use of a statistical experimental design. The parameters of the ethanol concentration model proposed on the basis of the Box–Wilson experimental design method were evaluated using the experimental data. Comparison of the predicted values from the model with the experimentally observed values showed that the model is a good fit. From analysis of the model equation it was seen that zinc, sodium and potassium ion concentrations have significant main effects on ethanol production but there were no interactive effects of the ions. Using the developed model, the maximum ethanol concentration of 4.19% (v/v) was obtained when potassium, sodium and zinc concentrations were 7900, 930 and 3.04 mg L−1, respectively. Copyright © 2007 Society of Chemical Industry
Kinetics of phenylurea herbicides oxidation by Fenton and photo‐Fenton processes
Authors: Benitez F Javier , Real Francisco J , Acero Juan L , Garcia Carolina , Llanos Eva M
Published: December 2006

The chemical oxidation of four selected phenylurea herbicides (linuron, chlortoluron, diuron, and isoproturon) was studied by means of the Fenton system. The influence of the initial concentrations of hydrogen peroxide and ferrous ions, the pH and the type of buffer (perchloric acid/perchlorate, acetic acid/acetate, or phosphoric acid/phosphate) was established according to the degradation levels obtained. In the kinetic study, the general decomposition reaction was divided into two stages with different reaction rates, which was justified by considering the whole reaction mechanism for this system. In this kinetic study, a competition kinetics model, which usedp‐chlorobenzoic acid as a reference compound, was applied for the evaluation of the rate constants for each reaction between the herbicides and the hydroxyl radical. The proposed values for these rate constants are: 7.5 × 109L mol−1s−1for chlortoluron, 5.6 × 109L mol−1s−1for linuron, 7.1 × 109L mol−1s−1for diuron and 5.7 × 109L mol−1s−1for isoproturon. Finally, some experiments with the photo‐Fenton system reveal increases in the decomposition levels of the herbicides, due to additional generation reactions of hydroxyl radicals. Copyright © 2007 Society of Chemical Industry
Microbial fuel cells utilising carbohydrates
Authors: Scott Keith , Murano Cassandro
Published: December 2006

The paper reports results of a mediatorless microbial fuel cell (MFC), utilising waste carbohydrate (manure) as a fuel, which did not use a catalyst or a proton exchange membrane and is thus environmentally friendly (by using no toxic substances) in treating waste. The cell used a manure sludge in the anode compartment and an aqueous salt solution (seawater) containing dissolved oxygen. The influence of the geometric position of the anode and cathode, both made of carbon cloth, had a major effect on the fuel cell power performance. The maximum power density obtained with the cell was 4.21 mW m−2. The paper also reports results of a mediated MFC using a yogurt bacteria and methylene blue as mediator. This cell produced a maximum power density of over 13 mW m−2. This power output compares quite favourably with that achieved with the same cell using glucose as fuel with E. coli (peak power density of 180 mW m−2). Copyright © 2007 Society of Chemical Industry
Comparison of diverged Hoxc8 early enhancer activities reveals modification of regulatory interactions at conserved cis‐acting elements
Authors: Shashikant Cooduvalli S. , Bolanowsky Stacey A. , Anand Sanjay , Anderson Shawn M.
Published: December 2006

The Hoxc8 early enhancer that controls the initiation and establishment of Hoxc8 expression in the developing mouse embryo is found in different vertebrate lineages including mammals, birds and fish. Mouse and Fugu Hoxc8 early enhancers (200 bp) have diverged in the composition of elements located towards the 3′ region. However, they share cis‐acting elements A–E located in the 5′ region. Mutations at these elements in the context of the mouse Hoxc8 early enhancer affect reporter gene expression in the posterior neural tube, somites and lateral plate mesoderm of day 9.5 mouse embryos. Here, we demonstrate that mutations introduced at the same elements but in the context of the Fugu Hoxc8 early enhancer had different consequences on the reporter gene expression in transgenic mouse embryos. Furthermore, in contrast to the mouse enhancer the Fugu enhancer does not utilize elements D and E in achieving posterior neural tube and somite expression. These results suggest that the diverged sequences prevent regulatory interactions at conserved cis‐acting elements. We propose that divergent sequences modify regulatory interactions at conserved elements by providing a “contextual change”. Our finding that the enhancer elements do not act in a unitary fashion but function in the context of the surrounding sequence brings a new dimension to the study of cis‐regulatory evolution. J. Exp. Zool. (Mol. Dev. Evol.) 308B:242–249, 2007. © 2006 Wiley‐Liss, Inc.
Characterization of breast lesions using the 3D FIESTA sequence and contrast‐enhanced magnetic resonance imaging
Authors: Klifa Catherine S. , Shimakawa Ann , Siraj Zaker , Gibbs Jessica E. , Wilmes Lisa J. , Partridge Savannah C. , Proctor Evelyn , Hylton Nola M.
Published: December 2006

Purpose

To determine whether combining 3D fast imaging employing steady‐state acquisition (FIESTA) and T1‐weighted contrast‐enhanced (CE) sequences could help characterize lesions in 32 women with benign, in situ, or invasive breast lesions. Since FIESTA provides both T1 and T2 information on the same three‐dimensional (3D) matrix as high‐resolution T1‐weighted dynamic data, we aimed to verify whether invasive lesions could be separated from in situ and/or benign lesions using quantitative FIESTA measures of tissue intensity and homogeneity.

Material and Methods

With the use of CE‐MRI data, regions of interest (ROIs) were manually delineated in enhancing lesions and on surrounding normal tissue. These ROIs were then applied to 3D FIESTA data. Quantitative measures between lesion and normal tissue were compared among the lesion groups.

Results

On FIESTA most invasive cancer lesions were hypointense compared to surrounding normal tissue (mean lesion intensity was 89% of normal tissue intensity), whereas most ductal and benign lesions appeared hyperintense compared to surrounding normal tissue (lesions at 100.9% and 121.9% of normal tissue intensity, respectively). Measures obtained from resampled T2‐weighted data showed no significant differences between the invasive and benign lesion groups.

Conclusion

We detected significant differences between invasive and noninvasive lesions by quantifying intensity differences between the lesions and surrounding normal tissue on FIESTA. J. Magn. Reson. Imaging 2007. © 2006 Wiley‐Liss, Inc.
In vivo brain edema classification: New insight offered by large b‐value diffusion‐weighted MR imaging
Authors: Schwarcz Attila , Ursprung Zsuzsa , Berente Zoltan , Bogner Peter , Kotek Gyula , Meric Philippe , Gillet Brigitte , Beloeil Jean‐Claude , Dóczi Tamás
Published: December 2006

Purpose

To assess the role of large b‐value diffusion weighted imaging (DWI) in the characterization of the physicochemical properties of the water in brain edema under experimental and clinical conditions.

Materials and Methods

Vasogenic brain edema was induced in mice by means of cold injury. A total of 17 patients with extensive peritumoral brain edema were also investigated. The longitudinal relaxation time (T1) and apparent diffusion coefficient (D) were measured in the edematous area both in humans and in mice. D was calculated by using both mono‐ (Dmono) and biexponential (Dfast and Dslow) approaches in the low and overall range of b‐values, respectively. The D values were correlated with the T1 values.

Results

A strong linear correlation was found between T1 and Dmono in vasogenic brain edema, both in humans and in mice. After breakdown of Dmono into fast and slow diffusing components, only Dfast exhibited a strong correlation with T1; Dslow was unchanged in vasogenic brain edema.

Conclusion

Large b‐value DWI can furnish a detailed characterization of vasogenic brain edema, and may provide a quantitative approach for the differentiation of edema types on the basis of the physicochemical properties of the water molecules. Application of the DWI method may permit prediction and follow‐up of the effects of antiedematous therapy. J. Magn. Reson. Imaging 2007. © 2006 Wiley‐Liss, Inc.
Dynamic contrast‐enhanced MRI study of male pelvic perfusion at 3T: Preliminary clinical report
Authors: Hou Ping , De Elise J.B. , Kramer Larry A. , Westney O. Lenaine
Published: December 2006

Purpose

To detect male pelvic perfusion in patients with coronary artery disease (CAD) vs. controls by dynamic contrast‐enhanced magnetic resonance imaging (DCE‐MRI) at 3T.

Materials and Methods

Eighteen male patients were studied with T1‐weighted (T1W) DCE‐MRI to measure perfusion, phase‐contrast (PC) imaging to measure bulk flow, and contrast‐enhanced (CE)‐MRA to detect stenosis. Regions of interest (ROIs) in prostate, corpus cavernosal, and spongiosal tissues were analyzed. Two‐compartment pharmacokinetic modeling was employed to fit the signal enhancement. Perfusion parameters were analyzed by curve‐fitting and utilized to compare the CAD and control groups. Validated questionnaires measuring urinary and erectile function were used to evaluate pelvic symptomatology in both groups.

Results

Mean perfusion analysis confirmed weaker and slower enhancement in CAD patients vs. controls despite equivalent cardiac output values. The mean maximum enhancement was 26.33 ± 0.12 (controls) vs. 22.38 ± 0.44 (CAD) for prostate. The mean wash‐in rate in units of minute–1 was 62.10 ± 1.74 (controls) vs. 34.44 ± 1.08 (CAD) for prostate, 16.68 ± 0.72 (controls) vs. 8.04 ± 0.36 (CAD) for spongiosal, and 8.34 ± 0.54 (controls) vs. 3.48 ± 0.24 (CAD) for cavernosal tissues (all with P < 0.0001).

Conclusion

This preliminary study demonstrates that perfusion parameters differ between CAD and control patients, and the findings mirror the differences in pelvic symptoms in these groups. J. Magn. Reson. Imaging 2007. © 2006 Wiley‐Liss, Inc.
Glutamatergic synaptic depression by synthetic amyloid β‐peptide in the medial septum
Authors: Santos‐Torres Julio , Fuente Antonio , Criado Jose Maria , Riolobos Adelaida Sanchez , Heredia Margarita , Yajeya Javier
Published: December 2006

The medial septum/diagonal band region, which participates in learning and memory processes via its cholinergic and GABAergic projection to the hippocampus, is one of the structures affected by beta amyloid (βA) deposition in Alzheimer's disease (AD). The acute effects of βA (25–35 and 1–40) on action potential generation and glutamatergic synaptic transmission in slices of the medial septal area of the rat brain were studied using current and patch‐clamp techniques. The βA mechanism of action through M1 muscarinic receptors and voltage‐dependent calcium channels was also addressed. Excitatory evoked responses decreased (30–60%) in amplitude after βA (2 μM) perfusion in 70% of recorded cells. However, the firing properties were unaltered at the same concentration. This depression was irreversible in most cases, and was not prevented or reversed by nicotine (5 μM). In addition, the results obtained using a paired‐pulse protocol support pre‐ and postsynaptic actions of the peptide. The βA effect was blocked by calcicludine (50 nM), a selective antagonist of L‐type calcium channels, and also by blocking muscarinic receptors with atropine (5 μM) or pirenzepine (1 μM), a more specific M1‐receptor blocker. We show that in the medial septal area this oligomeric peptide acts through calcium channels and muscarinic receptors. As blocking any of these pathways blocks the βA effects, we propose a joint action through both mechanisms. These results may contribute to a better understanding of the pathophysiology at the onset of AD. This understanding will be required for the development of new therapeutic agents. © 2006 Wiley‐Liss, Inc.
Fischer decomposition and special solutions for the parabolic Dirac operator
Authors: Cerejeiras P. , Sommen F. , Vieira N.
Published: December 2006

In this paper we study a Fischer decomposition for the parabolic Dirac operator which factorizes the heat equation. Since the standard construction techniques are not valid in our case, due to the non‐homogeneity of the positive parabolic Dirac operator, we first establish and study the Fischer decomposition for the homogeneous part of the parabolic Dirac operator. Finally, we construct null‐solutions of the parabolic Dirac operator by means of series expansions in terms of cylindrical co‐ordinates. Copyright © 2006 John Wiley & Sons, Ltd.
A comparative study of multilayer perceptron neural networks for the identification of rhubarb samples
Authors: Zhang Zhuoyong , Wang Yamin , Fan Guoqiang , Harrington Peter De B.
Published: December 2006

Artificial neural networks have gained much attention in recent years as fast and flexible methods for quality control in traditional medicine. Near‐infrared (NIR) spectroscopy has become an accepted method for the qualitative and quantitative analyses of traditional Chinese medicine since it is simple, rapid, and non‐destructive. The present paper describes a method by which to discriminate official and unofficial rhubarb samples using three layer perceptron neural networks applied to NIR data. Multilayer perceptron neural networks were trained with back propagation, delta‐bar‐delta and quick propagation algorithms. Results obtained using these methods were all satisfactory, but the best outcomes were obtained with the delta‐bar‐delta algorithm. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis of macromonomers of acrylic acid by telomerization: Application to the synthesis of polystyrene‐g‐poly(acrylic acid) copolymers
Authors: Boyer Cyrille , Boutevin Gilles , Robin Jean‐Jacques , Boutevin Bernard
Published: December 2006

The synthesis of macromonomers of acrylic acid was performed by telomerization in a three‐step process. The first step was the telomerization of tert‐butyl acrylate in the presence of thioglycolic acid. Different molecular weights were obtained with different ratios of the monomer to the transfer agent. Good control of the molecular weights and architectures of the oligomers (e.g., the presence of an acid function on the chain end) was observed. The transfer constant of tert‐butyl acrylate with thioglycolic acid was assessed (chain‐transfer constant = 0.6). In the second step, the terminal unsaturation of the oligomers was obtained by the reaction of the terminal acid groups with 2‐isocyanatoethyl methacrylate to yield the macromonomers of tert‐butyl acrylate. In the last step, the tert‐butyl acrylate groups were hydrolyzed in the presence of trifluoroacetic acid at room temperature. The macromonomers were copolymerized with styrene to obtain graft copolymers, and the reactivity ratios were evaluated. Finally, the copolymers were characterized with surface electron microscopy and atom force microscopy. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 395–415, 2007
Synthesis of poly(vinyl acetate)‐graft‐polystyrene by a combination of cobalt‐mediated radical polymerization and atom transfer radical polymerization
Authors: Kaneyoshi Hiromu , Matyjaszewski Krzysztof
Published: December 2006

Vinyl acetate and vinyl chloroacetate were copolymerized in the presence of a bis(trifluoro‐2,4‐pentanedionato)cobalt(II) complex and 2,2′‐azobis(4‐methoxy‐2,4‐dimethylvaleronitrile) at 30 °C, forming a cobalt‐capped poly(vinyl acetate‐co‐vinyl chloroacetate). The addition of 2,2,6,6‐tetramethyl‐1‐piperidinyloxy after a certain degree of copolymerization was reached afforded 2,2,6,6‐tetramethyl‐1‐piperidinyloxy‐terminated poly(vinyl acetate‐co‐vinyl chloroacetate) (PVOAc–MI; number‐average molecular weight = 31,000, weight‐average molecular weight/number‐average molecular weight = 1.24). A 1H NMR study of the resulting PVOAc–MI revealed quantitative terminal 2,2,6,6‐tetramethyl‐1‐piperidinyloxy functionality and the presence of 5.5 mol % vinyl chloroacetate in the copolymer. The atom transfer radical polymerization (ATRP) of styrene (St) was studied with ethyl chloroacetate as a model initiator and five different Cu‐based catalysts. Catalysts with bis(2‐pyridylmethyl)octadecylamine (BPMODA) or tris(2‐pyridylmethyl)amine (TPMA) ligands provided the highest initiation efficiency and best control over the polymerization of St. The grafting‐from ATRP of St from PVOAc–MI catalyzed by copper complexes with BPMODA or TPMA ligands provided poly(vinyl acetate)‐graft‐polystyrene copolymers with relatively high polydispersity (>1.5) because of intermolecular coupling between growing polystyrene (PSt) grafts. After the hydrolysis of the graft copolymers, the cleaved PSt side chains had a monomodal molecular weight distribution with some tailing toward the lower number‐average molecular weight region because of termination. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 447–459, 2007
Preparation of poly(styrene‐co‐acrylonitrile)‐grafted multiwalled carbon nanotubes via surface‐initiated atom transfer radical polymerization
Authors: Shanmugharaj A. M. , Bae J. H. , Nayak Rati Ranjan , Ryu Sung Hun
Published: December 2006

The in situ grafting‐from approach via atom transfer radical polymerization was successfully applied to polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile grafted onto the convex surfaces of multiwalled carbon nanotubes (MWCNTs) with (2‐hydroxyethyl 2‐bromoisobutyrate) as an initiator. Thermogravimetric analysis showed that effective functionalization was achieved with the grafting approach. The grafted polymers on the MWCNT surface were characterized and confirmed with Fourier transform infrared spectroscopy and nuclear magnetic resonance. Raman and near‐infrared spectroscopy revealed that the grafting of polystyrene, poly(styrene‐co‐acrylonitrile), and polyacrylonitrile slightly affected the side‐wall structures. Field emission scanning electron microscopy showed that the carbon nanotube surface became rough because of the grafting of the polymers. Differential scanning calorimetry results indicated that the polymers grafted onto MWCNTs showed higher glass‐transition temperatures. The polymer‐grafted MWCNTs exhibited relatively good dispersibility in an organic solvent such as tetrahydrofuran. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 460–470, 2007
Synthesis of optically active poly(N‐propargylsulfamides) with helical conformation
Authors: Zhang Zhigang , Deng Jianping , Zhao Weiguo , Wang Jianmin , Yang Wantai
Published: December 2006

A novel chiral N‐propargylsulfamide monomer (1a) and its enantiomer (1b) were synthesized and polymerized with (nbd)Rh+B−(C6H5)4 as a catalyst providing poly(1) (poly(1a) and poly(1b)) in high yields (≥99%). Poly(1) could take stable helices in less polar solvents (chloroform and THF), demonstrated by strong circular dichroism signals and UV–vis absorption peaks at about 415 nm and the large specific rotations; but in more polar solvents including DMF and DMSO, poly(1) failed to form helix. Quantitative evaluation with anisotropy factor showed that the helical screw sense had a relatively high thermal stability. These results together with the IR spectra measured in solvents showed that hydrogen bonding between the neighboring sulfamide groups is one of the main driving forces for poly(1) to adopt stable helices. In addition, copolymerization of monomer 1a and monomer 2 was conducted, the solubility of poly(1) was improved drastically. However, the copolymerization had adverse effects on the formation of stable helices in the copolymers. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 500–508, 2007
Stability control of the electrooptic effect with new maleimide copolymers containing photoreactive tricyanopyrrolidene‐based chromophores
Authors: Lee Sang Kyu , Cho Min Ju , Jin Jung‐Il , Choi Dong Hoon
Published: December 2006

New photocrosslinkable maleimide copolymers have been synthesized by the attachment of a tricyanopyrrolidene‐based chromophore. The 2‐(3‐cyano‐4‐(2‐{4‐[hexyl‐(6‐hydroxy‐hexyl)‐amino]‐phenyl}‐vinyl)‐5‐oxo‐1‐{4‐[4‐(3‐oxo‐3‐phenyl‐propenyl)‐ phenoxy]‐butyl}‐1,5‐dihydro‐pyrrol‐2‐ylidene)‐malononitrile chromophore exhibits nonlinear optical activity and contains a chalcone moiety that is sensitive to UV light (λ = 330–360 nm) for crosslink formation. The maleimide monomers have also been functionalized with chalcone moieties. The resultant copolymers exhibit great processability, and one of them shows a maximum electrooptic coefficient of 90 pm/V at 1300 nm. We could control the thermal stability of the electrooptic coefficient with the newly synthesized photoreactive copolymers successfully. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 531–542, 2007
Interaction of malaria parasite‐inhibitory antibodies with the merozoite surface protein MSP119 by computational docking
Authors: Autore Flavia , Melchiorre Sara , Kleinjung Jens , Morgan William D. , Fraternali Franca
Published: December 2006

Merozoite surface protein 1 (MSP1) of the malaria parasite Plasmodium falciparum is an important vaccine candidate antigen. Antibodies specific for the C‐terminal maturation product, MSP119, have been shown to inhibit erythrocyte invasion and parasite growth. Specific monoclonal antibodies react with conformational epitopes contained within the two EGF‐like domains that constitute the antigen MSP119. To gain greater insight into the inhibitory process, the authors selected two strongly inhibitory antibodies (designated 12.8 and 12.10) and modeled their structures by homology. Computational docking was used to generate antigen–antibody complexes and a selection filter based on NMR data was applied to obtain plausible models. Molecular Dynamics simulations of the selected complexes were performed to evaluate the role of specific side chains in the binding. Favorable complexes were obtained that complement the NMR data in defining specific binding sites. These models can provide valuable guidelines for future experimental work that is devoted to the understanding of the action mechanism of invasion‐inhibitory antibodies. Proteins 2007. © 2006 Wiley‐Liss, Inc.
Sublinear‐time approximation algorithms for clustering via random sampling
Authors: Czumaj Artur , Sohler Christian
Published: December 2006

We present a novel analysis of a random sampling approach for four clustering problems in metric spaces:k‐median,k‐means,min‐sum k‐clustering, and balancedk‐median. For all these problems, we consider the following simple sampling scheme: select a small sample set of input points uniformly at random and then run some approximation algorithm on this sample set to compute an approximation of the best possible clustering of this set. Our main technical contribution is a significantly strengthened analysis of the approximation guarantee by this scheme for the clustering problems.

The main motivation behind our analyses was to design sublinear‐time algorithms for clustering problems. Our second contribution is the development of new approximation algorithms for the aforementioned clustering problems. Using our random sampling approach, we obtain for these problems the first time approximation algorithms that have running time independent of the input size, and depending onkand the diameter of the metric space only. © 2006 Wiley Periodicals, Inc. Random Struct. Alg., 2006
Density profile unfolding from Compton scattering measurements in reflection geometry
Authors: Fernández Jorge E. , Badiali Marco , Guidetti Alessandro , Scot Viviana
Published: December 2006

In this article, we report a mathematical procedure that allows the unfolding of the density profile from the measurement of an integrated scattering signal containing predominantly the Compton component. An experimental device (patent claimed) has been used for the measurements. It uses a radiation source with white x‐ray spectrum (unpolarized) and the reflection geometry to maximize the Compton signal. The algorithm has been tested on light‐element, inhomogeneous samples of uniform and non‐uniform densities. Incomplete primary volume and multiple scattering corrections are also discussed. The resulting density profiles are in good agreement with direct measurements of profiles performed with other means. Copyright © 2006 John Wiley & Sons, Ltd.
On assertion-based encapsulation for object invariants and simulations
Authors: Naumann David A.
Published: December 2006

In object-oriented programming, reentrant method invocations and shared references make it difficult to achieve adequate encapsulation for sound modular reasoning. This tutorial paper surveys recent progress using auxiliary state (ghost fields) to describe and achieve encapsulation. It also compares this technique with encapsulation in the forms provided by separation logic. Encapsulation is assessed in terms of modular reasoning about invariants and simulations.
Cognitive impairment in heart failure: A systematic review of the literature
Authors: Vogels Raymond L.C. , Scheltens Philip , Schroeder‐Tanka Jutta M. , Weinstein Henry C.
Published: December 2006

Background

Heart failure (HF) and cognitive impairment are common medical conditions that are becoming increasingly prevalent in the aging Western population. They are associated with frequent hospitalisation and increased mortality, particularly when they occur simultaneously. Evidence from a number of studies suggests that HF is independently associated with impairment in various cognitive domains.

Aims

This systematic literature review evaluates the relation between cognitive deterioration and heart failure.

Methods

We searched electronic databases from 1966 to May 2006 for studies that investigated cognitive function in HF patients. Twenty‐two controlled studies that met the inclusion criteria were selected for analysis. Study characteristics and data on global cognitive performance, memory scores, psychomotor speed and depression scores were extracted and analysed using the Cochrane Review Manager software.

Results

Pooled analysis shows diminished neuropsychological performance in HF patients, as compared to control subjects. In a pooled sample of 2937 heart‐failure patients and 14,848 control subjects, the odds ratio for cognitive impairment was 1.62 (95% confidence interval:1.48–1.79, p<0.0001) among subjects with HF.

Conclusion

This review confirms the relationship between HF and cognitive impairment, but it also stresses the need for additional systematic neuropsychological data and adequate neuro‐imaging from representative populations of HF patients.
Behavioral and sensory changes after direct ischemia‐reperfusion injury in rats
Authors: Ludwig Janne , Gorodetskaya Natalia , Schattschneider Jörn , Jänig Wilfrid , Baron Ralf
Published: December 2006

Complex regional pain syndromes (CRPS) are disabling pain syndromes that can develop after trauma or minor tissue injury affecting a limb. Characteristics of CRPS are sensory signs and symptoms, autonomic abnormalities, trophic changes and an impaired motor function. Pathophysiological mechanisms for the development of CRPS are still a matter of investigation. Based on clinical data and investigations of CRPS patients it is hypothesized that tissue hypoxia and inflammation are important for the development of CRPS. The aim of the current study was therefore to examine if direct ischemia‐reperfusion injury can induce behavior in rats with symptoms present in patients with CRPS.

After baseline behavior measurements the femoral artery of Wistar rats was ligated for 3 h with consecutive reperfusion. Sham‐operated rats underwent the same preparation except ligation of the artery. Subsequent behavioral testing (observations of spontaneous pain behavior, paw withdrawal to mechanical, noxious mechanical, cold and heat stimuli) was performed up to two months after surgery. Both in rats that underwent ischemia and in sham‐operated rats no obvious changes of hindpaw tissue were observed after ischemia‐reperfusion injury (trophic changes, edema, differences in skin color or temperature). In behavioral tests only minor changes were observed, these being not different between postischemic rats and sham‐operated rats. Using Wistar rats, our data do not support the idea that an ischemia‐reperfusion injury can play a major role in the development of CRPS.
Differential requirement of MKK4 and MKK7 in JNK activation by distinct scaffold proteins
Authors: Zou Haiying , Li Qinxi , Lin Sheng-Cai , Wu Zhenguo , Han Jiahuai , Ye Zhiyun
Published: December 2006

Different scaffold proteins play distinct roles in various signaling pathways by recruiting different downstream molecules. Here, using MKK4−/− and MKK4−/−/7−/− murine embryonic fibroblast cells, we examined differential employment of MKK4 and MKK7 by scaffold proteins Axin, Dvl, and Epstein–Barr virus latent membrane protein‐1 (LMP‐1) in mediating JNK activation. We present evidence that Axin depends mainly on MKK7 for activation of JNK, while Dvl depends almost equally on MKK4 and MKK7 for JNK activation, In contrast, LMP‐1‐induced JNK activation is primarily dependent on MKK4. Our results demonstrate that Axin, Dvl, and LMP‐1 differentially utilize MKK4 and MKK7 for JNK activation.
States of Ethnography: Colonialism, Resistance, and Cultural Transcription in Malaya and the Philippines, 1890s–1930s
Authors: Goh Daniel P. S.
Published: December 2006

The metaphoric reading of native life as an unopened book by two ranking colonial administrators and authoritative ethnographers in Malaya and the Philippines cannot be a simple coincidence. Clifford and Barrows represent two empires, one conservative and peaking, the other liberal and ascendant, meeting in “the Malay Archipelago.” Clifford was a product of the rugged and cultured education demanded of British aristocratic scions, while Barrows exemplified the rising American professional classes, holding graduate degrees in education and anthropology. Both men served well the metropolitan ideologies that guided the imperial hand: British Providence to provide good government to the Malay states; American manifest destiny to replace Spain as the agent of civilization in the Philippines. Using their ethnographic readings, Clifford helped perfect the art of British “indirect rule” Malaya, while Barrows established the Philippine mass education system, the main thrust of the United States' “benevolent assimilation.” Both men retired as decorated officers and established literati, Barrows as the President of the University of California and Clifford a literary figure after Joseph Conrad and Rudyard Kipling.
Diel variation in sea grass dwelling shrimp: when to sample at night?
Authors: De Grave S. , Livingston D. , Speight M.R.
Published: December 2006

The present study investigates hourly variation in nocturnal abundance fluctuations in a tropical, Caribbean sea grass bed. As expected, results indicate that significant diel variation is present. In addition all dominant species show an abundance peak shortly after sunset, with numbers gradually declining throughout the night. It is therefore suggested that nocturnal samples are not only incorporated into any sampling regime, but that nocturnal samples are taken within two hours after sunset.
A new species of Ophiomisidium (Echinodermata: Ophiuroidea) from the continental shelf and slope off southern Brazil
Authors: Borges Michela , Monteiro Ana Maria G. , Amaral A. Cecília Z.
Published: December 2006

A new species of Ophiomisidium is described and regards about reproduction are presented. It is the first species in the genus to posses, apparently, a brooding development. Very few specimens of species of Ophiomisidium have previously been collected, but over 3000 specimens of the new species were collected on the continental shelf and slope (60–810 m depth) off southern Brazil. They were obtained during the REVIZEE Programme, the first extensive surveys to examine Brazilian ophiuroids from depths greater than 200 m.
ADMISSION CONTROL WITH INCOMPLETE INFORMATION TO A FINITE BUFFER
QUEUE
Authors: Honhon Dorothée , Seshadri Sridhar
Published: December 2006

We consider the problem of admission control to a multiserver finite
buffer queue under partial information. The controller cannot see the
queue but is informed immediately if an admitted customer is lost due to
buffer overflow. Turning away (i.e., blocking) customers is costly and so
is losing an admitted customer. The latter cost is greater than that of
blocking. The controller's objective is to minimize the average cost
of blocking and rejection per incoming customer. Lin and Ross [11] studied this problem for multiserver loss
systems. We extend their work by allowing a finite buffer and the arrival
process to be of the renewal type. We propose a control policy based on a
novel state aggregation approach that exploits the regenerative structure
of the system, performs well, and gives a lower bound on the optimal cost.
The control policy is inspired by a simulation technique that reduces the
variance of the estimators by not simulating the customer service process.
Numerical experiments show that our bound varies with the load offered to
the system and is typically within 1% and 10% of the optimal cost. Also,
our bound is tight in the important case when the cost of blocking is low
compared to the cost of rejection and the load offered to the system is
high. The quality of the bound degrades with the degree of state
aggregation, but the computational effort is comparatively small.
Moreover, the control policies that we obtain perform better compared to a
heuristic suggested by Lin and Ross. The state aggregation technique
developed in this article can be used more generally to solve problems in
which the objective is to control the time to the end of a cycle and the
quality of the information available to the controller degrades with the
length of the cycle.
BLOCK AND BASU'S BIVARIATE EXPONENTIAL DISTRIBUTION WITH APPLICATION TO DROUGHT DATA
Authors: Nadarajah Saralees , Kotz Samuel
Published: December 2006

Motivated by hydrological applications, the exact distributions ofR=X+Y,P=XY, andW=X/(X+Y) and the corresponding moment properties are derived whenXandYfollow Block and Basu's bivariate exponential distribution. An application of the results is provided to drought data from Nebraska.
Development of a Radionavigation Plan for General Lighthouse Authorities of the United Kingdom and Ireland
Authors: Basker Sally
Published: December 2006

A version of this paper was first presented at the European Navigation Conference 2006, held under the auspices of the RIN at Manchester on 8–10 May 2006.

This paper reviews the need for the GLAs to develop a strategy for the integration of radionavigation services around the British Isles. After investigating the recent trends and forecasts for shipping and with a view towards the need for e-Navigation, the strategy formation process and initial findings for the development of a radionavigation plan are outlined.
A Fuzzy Logic Method for Collision Avoidance in Vessel Traffic Service
Authors: Kao Sheng-Long , Lee Kuo-Tien , Chang Ki-Yin , Ko Min-Der
Published: December 2006

Currently Vessel Traffic Service (VTS) does not have enough technical capability to monitor a crowded surveillance area to maintain safety. Without an efficient alerting system, many marine accidents have occurred due to operator oversight. In this article, a new fuzzy logic method is proposed to add vessel collision avoidance capability to VTS/AIS systems for all potential collision ships in the surveillance area. Starting from the VTS standpoint and integrating AIS data into the Marine Geographic Information System (MGIS) as a platform, the calculations of ship domain and ship inertial force are utilized to generate models of a guarding ring and danger index. By this means, a precise prediction of collision time and position can be achieved using a marine GIS spatial analyst module. The proposed method is able to enhance the VTS operator's decision-making abilities by providing a collision avoidance alerting system.
Test and Integration of Location Sensors for a Multi-sensor Personal Navigator
Authors: Retscher Günther
Published: December 2006

In the work package “Integrated Positioning” of the research project NAVIO (Pedestrian Navigation Systems in Combined Indoor/Outdoor Environments) we are dealing with the navigation and guidance of visitors to our University. The start points are the public transport stops in the surroundings of the Vienna University of Technology and the system users should be guided to certain office rooms or persons. For the user's position determination different location sensors are employed, i.e., for outdoor positioning GPS and dead reckoning sensors, such as a digital compass and gyro for heading determination, accelerometers for the determination of the distance travelled, a barometric pressure sensor for altitude determination and, for indoor areas, location determination using WiFi fingerprinting. All sensors and positioning methods are combined and integrated using a Kalman filter. An optimal estimate of the current location of the user is obtained using the filter. To perform an adequate weighting of the senors in the stochastic filter model, the sensor characteristics and performance were investigated in several tests. The tests were performed in different environments either with free satellite visibility, in urban canyons or inside buildings. The tests have shown that it is possible to determine the user's location continuously with the required precision and that the selected sensors provide a good performance and high reliability. Selected tests results and our approach are presented in the paper.
AIS Implementation – Success or Failure?
Authors: Norris Andy
Published: December 2006

A version of this paper was first presented at the European Navigation Conference 2006, held under the auspices of the RIN at Manchester on 8–10 May 2006.

AIS is the most recent example of a major globally-introduced maritime navigation system. During its evolution, introduction and early in-service life, it has aroused a lot of negative comment. The basis for this negativity is examined, particularly in the light of the real experience that is now being gained by users of the system. The evolution of the AIS concept through the relevant international bodies – IMO, ITU, IALA and IEC – is discussed, together with the type of problems encountered during its introduction. Many of the problems would have been ameliorated if there had been better communication to users of the system. It is argued that the complexity of the system really required mandatory training to be undertaken, in parallel with the installation of the new equipment.
Code Multipath Modelling in the Urban Environment Using Large Virtual Reality City Models: Determining the Local Environment
Authors: Bradbury J. , Ziebart M. , Cross P.A. , Boulton P. , Read A.
Published: December 2006

Positioning in the urban environment using GNSS is hampered by poor satellite availability due to signal obstruction created by both man-made and natural features of the urban environment. In addition, range measurement to satellites for positioning and for navigation is severely degraded by the multipath effect. The arrival and continuous enhancement of computerised geometric city models makes it possible to tackle these problems through modelling. In this paper description is given of a method for determining the local multipath environment, defined by the surfaces within a city model that will cause disruptive signal reflections to be presented to a receiver. An example simulation is performed, and graphical and numerical results are produced.
The frictional and micromechanical effects of grain comminution in fault gouge from distinct element simulations
Authors: Guo Yonggui , Morgan Julia K.
Published: December 2006

Natural fault zones undergo pervasive grain comminution during faulting and shearing, producing progressive changes in fault gouge properties. We simulate the comminution process of quartz gouge using the distinct element method (DEM) to examine the influences of grain comminution and associated dynamic changes in grain characteristics on the frictional and micromechanical behavior of granular shear zones. Rounded and triangular grains are constructed from clusters of circular particles, connected by some breakable bonds, allowing for grain fracture and comminution. DEM experiments are conducted by shearing identical granular assemblages composed of either rounded or triangular grains of different strengths over a range of normal stresses from 5 to 100 MPa. The results show that grain comminution with strain changes the partitioning of different deformation mechanisms, mainly by changing grain shape and size. Grain comminution may decrease or increase gouge strength, depending on the direction and degree of change in grain shape. Increases in grain angularity lead to significant increases in frictional strength of fault gouges, while increases in grain elongation tend to decrease in frictional strength. The final strength results from the competition between strength reduction by fracturing and strength variation by changes in grain shape and grain size distribution. Our simulations also demonstrate that the intensity and probability of grain comminution in narrow grain size gouges is affected by shape, strength (e.g., due to mineralogy), and normal stress.
Surface drifter derived circulation in the northern and middle Adriatic Sea: Response to wind regime and season
Authors: Ursella Laura , Poulain Pierre‐Marie , Signell Richard P.
Published: December 2006

More than 120 satellite‐tracked drifters were deployed in the northern and middle Adriatic (NMA) Sea between September 2002 and November 2003, with the purpose of studying the surface circulation at mesoscale to seasonal scale in relation to wind forcing, river runoff, and bottom topography. Pseudo‐Eulerian and Lagrangian statistics were calculated from the low‐pass‐filtered drifter velocity data between September 2002 and December 2003. The structure of the mean circulation is determined with unprecedented high horizontal resolution by the new data. In particular, mean currents, velocity variance, and kinetic energy levels are shown to be maximal in the Western Adriatic Current (WAC). Separating data into seasons, we found that the mean kinetic energy is maximal in fall, with high values also in winter, while it is significantly weaker in summer. High‐resolution Local Area Model Italy winds were used to relate the drifter velocities to the wind fields. The surface currents appear to be significantly influenced by the winds. The mean flow during the northeasterly bora regime shows an intensification of the across‐basin recirculating currents. In addition, the WAC is strongly intensified both in intensity and in its offshore lateral extension. In the southeasterly sirocco regime, northward flow without recirculation dominates in the eastern half of the basin, while during northwesterly maestro the WAC is enhanced. Separating the data into low and high Po River discharge rates for low‐wind conditions shows that the WAC and the velocity fluctuations in front of the Po delta are stronger for high Po River runoff. Lagrangian covariance, diffusivity, and integral time and space scales are larger in the along‐basin direction and are maximal in the southern portion of the WAC.