bluuebunny/crossref_metadata_2025 huggingface dataset:
Ionomers based on copolymers of alkyl methacrylates with 2‐methacryloylamino‐3‐naphthalene carboxylic acid: Association in solutions studied by steady‐state and time‐resolved fluorescence
Authors: Výprachtický Drahomír , Cimrová Vĕra , Yang Yu , Mikeš František
Published: February 2004

Methyl, butyl, and octadecyl methacrylate copolymers with 3‐methacryloylamino‐2‐naphthoic acid (MANA) carrying alkali counterions exhibit two emission bands in highly dilute dioxane, heptane, and toluene solutions. One band (α) has a maximum around 400 nm, and the other (β) has a maximum around 500 nm. The ratio of the intensity of the α band to the intensity of the β band depends on the counterion (Na+, Li+, and Cs+) and the solvent. Varying the MANA content of the copolymer with Na+ counterions increases the relative intensity of the α emission in proportion to the density of MANA residues in the ionomer chain, whereas in chains containing only 0.1% MANA residues, only a β emission can be seen. The α emission is due to associated ion pairs, and the β emission is due to unassociated ion pairs. The shorter the alkyl chain pendant is of the copolymer, the larger the fraction is of the associated ion pairs. The half‐bandwidth of the β emission is much larger than that of the α‐emission band in all cases. The half‐bandwidth decreases in the order Li+ > Na+ > Cs+. The fluorescence anisotropy decays for the α‐ and β‐emission bands are double‐exponential. The longer rotational correlation time and its fractional contribution to the β emission increase with an increasing content of the MANA monomer in the copolymer. The decay anisotropy data are consistent with the shell–core model of ionomers in nonpolar solvents. The fluorescence anisotropy decay of the copolymer of butyl methacrylate with a low content of the nonneutralized MANA (∼ 0.1 mol %) is single‐exponential, and the rotational correlation time of the MANA fluorophore is eight times longer than that of 3‐acetyl‐2‐naphthoic acid methyl ester (0.3 ns) in the same solvent. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 1243–1254, 2004
Synthesis of an 8‐Benzyl‐4‐(p‐substituted‐benzyl)‐1,4,8‐triazaspiro[4.5]decan‐2‐one Library on SynPhase TMLanterns
Authors: Feliu Lidia , Martinez Jean , Amblard Muriel
Published: February 2004

Based on a spiropiperidine motif, a 120 discrete compound library with the general structure 8‐benzyl‐4‐(p‐substituted‐benzyl)‐1,4,8‐triazaspiro[4.5]decan‐2‐one (5) was prepared on SynPhaseTM Lanterns. The spiroimidazolidinone system was formed in one step from N‐benzyl‐4‐piperidone and amino acid amides attached to the solid support through their Nα‐amino group.
A Combination of Different Spectroscopic Techniques to Monitor the “in situ” Solid‐phase Synthesis of Organic Molecules
Authors: Cironi Pablo , Álvarez Mercedes , Albericio Fernando
Published: February 2004

The efficacy, limitations and scope of different spectroscopic techniques to monitor solid‐phase syntheses are discussed. The total solid‐phase synthesis of a natural product derivative, 3,17‐di‐O‐acetyllamellarin U, has been monitored by gel‐phase NMR and HR‐MAS NMR as appropriate. FT‐IR and colorimetric tests also proved to be valuable tools for monitoring the progress of reactions. While the data obtained by FT‐IR provided valuable information on some functional groups, the NMR data provided more specific structural information that allowed the progress of reactions to be monitored. After several reaction steps the “aging” of the resin only allowed the product covalently anchored to the resin to be investigated using an HR‐MAS probe, a situation that severely limited the depth of analysis available.
CoMFA/CoMSIA/HQSAR and Docking Study of the Binding Mode of Selective Cyclooxygenase (COX‐2) Inhibitors
Authors: Chen Haifeng , Li Qiang , Yao Xiaojun , Fan BoTao , Yuan Shengang , Panaye A. , Doucet J. P.
Published: February 2004

The intermolecular interaction between four types of anti‐inflammatory inhibitors (oxazoles, pyrazoles, pyrroles and imidazoles) and COX‐2 receptor was studied. The results of docking suggest that they have similar interaction mechanism. The most active compounds of these four types of inhibitors could both form several hydrogen bonds with residues His90, Arg513, Leu352 and Arg120, and develop hydrophobic interaction with residues Phe518, Leu352 and Leu359. This is consistent with the investigation reported by R. G. Kurumbail et al. (Nature. 1996, 384, 644‐648). A common 3D‐QSAR model could be constructed with these four categories of COX‐2 inhibitors using the method of docking‐ guided conformer selection. The cross‐validated q2 values are found as 0.741 and 0.632 for CoMFA and CoMSIA respectively. And the non‐cross‐validated r2 values are 0.887 and 0.885. 54 inhibitors constitute the test set used to validate the model. The results show that this model possesses good predictive ability for diverse COX‐2 inhibitors. Furthermore, a HQSAR model was used to evaluate the influence of substituents on anti‐inflammatory activity. Compared with the results of previous works, our model possesses significantly better prediction ability. It could help us to well understand the interaction mechanism between inhibitors and COX‐2 receptor, and to make quantitative prediction of their inhibitory activities.
Classical QSAR Modeling of HIV‐1 Reverse Transcriptase Inhibitor 2‐Amino‐6‐arylsulfonylbenzonitriles and Congeners
Authors: Leonard J. Thomas , Roy Kunal
Published: February 2004

Considering the recent interests in the development of novel and potent non‐nucleoside reverse transcriptase inhibitors for the treatment of HIV‐1 infection, anti‐HIV‐1 activity (assayed in MT‐4 cell line) and HIV‐1 reverse transcriptase (RT) binding affinity of 2‐amino‐6‐arylsulfonylbenzonitriles and their thio and sulfinyl congeners (Chanet al., J. Med. Chem.,2001,44, 1866–1882) have been modeled using classical Quantitative Structure‐Activity Relationship (QSAR) tools in an attempt to explore the quantitative contribution pattern of different substituents in the aryl ring to the activities. Different physico‐chemical parameters like hydrophobicity (π), electronic (Hammett σ) and steric (molar refractivityMR) terms have been used along with appropriate indicator and/or integer variables to develop linear free energy related (LFER) model. Additionally, electrostatic potential point charges at different common atoms of the molecules calculated from AM1 optimized energy minimized geometry have also been tried as predictor variables. The models generated were of acceptable statistical quality and predictive potential. The results show that for both response variables, presence of sulfone moiety contributes significantly to the activities. Further, molar refractivity ofmetasubstituents plays a significant role in both the cases: secondmetasubstituents potentiate the activities probably due to enhanced binding (presumably through dispersion interaction) of the ligand with the binding site. Again, presence ofmeta‐trifluoromethyl group at the aryl ring is detrimental for both the activities. Additionally, the anti‐HIV‐1 model shows negative contribution of the steric parameter ofparasubstituents and positive contribution of theortho‐methoxy group.
COREPA‐M: A Multi‐Dimensional Formulation of COREPA
Authors: Mekenyan Ovanes , Nikolova Nina , Schmieder Patricia , Veith Gilman
Published: February 2004

Recently, the COmmon REactivity PAttern (COREPA) approach was developed as a probabilistic classification method which was formalized specifically to advance mechanistic QSAR development by addressing the impact of molecular flexibility on stereoelectronic properties of chemicals. In the initial version of COREPA, the probability distributions for only one stereoelectronic parameter at a time were analyzed for the series of chemicals under analysis. To go beyond considering probability distributions of one parameter at a time requires the capability of analyzing a suite of parameters simultaneously for each chemical. This work creates that capability for a multi‐dimensional formulation of the COREPA which is expected to enhance the reliability of the method to discriminate complex patterns. Using probability distance measures such as Kullback‐Leibler divergence and Hellinger distance, the set of parameters are defined that best discriminate activity. The COREPA‐M system automatically identifies the parameters that best discriminates chemicals in groups defined by comparable reactivity endpoints. A detailed Bayesian decision tree is then used for classifying untested chemicals with measures of “goodness of fit” criteria. COREPA‐M is illustrated using the example of modelling binding affinity of chemicals at the aryl hydrocarbon receptor.
Optimization of a Pharmacophore‐based Correlation Vector Descriptor for Similarity Searching
Authors: Fechner Uli , Schneider Gisbert
Published: February 2004

The usefulness of a correlation‐vector based, topological pharmacophore descriptor for similarity searching was examined in matters of three different scaling methods and a fuzzy binning scheme. “Retrospective screening” using twelve different datasets was performed to evaluate the influence of these parameters by means of the enrichment factor. Significant enrichment of active compounds was yielded in this study. Whereas the application of the fuzzy binning scheme did not substantially influence the enrichment factor, we observed significant higher enrichment for individual ligand families with the employment of a specific descriptor scaling method. These results indicate that optimization of individual critical parameters of a well‐established descriptor may be crucial for improved performance in similarity searching and focused library design.
Ionization process of the hydrogen atom in intense laser fields: Non–Born‐Oppenheimer 1D model calculations
Authors: Ohta Yasuhito , Maki J. , Nagao Hidemi , Nishikawa Kiyoshi
Published: February 2004

The ionization process of the hydrogen atom in two‐color laser field is investigated based on non–Born‐Oppenheimer one‐dimensional model. In this model, both electron and nucleus are described by the time‐dependent Hartree equations. By numerically solving the equations, the influence of the relative phase ϕ of the laser field with the spatial distribution of electron and nucleus is investigated. For ϕ = 0, the electron is moved to the direction in which the maximum of the asymmetric combined electric field pointed. For ϕ = π/2, the electron is shown to be pulled in the opposite direction. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Expansion(s) of r
Authors: Harris Frank E.
Published: February 2004

The expansion for r claimed by Lüchow and Kleindienst to be “new” is shown to be algebraically identical to that reported some years previously by Pauli and Kleindienst but with the coefficients of the expansion brought to a far more convenient form. The demonstration presented here also reveals some previously unreported relationships connecting these coefficients. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Antioxidant activity of flavonols
Authors: Ghiotto R. C. T. , Lavarda F. C. , Ferreira F. J. B.
Published: February 2004

In this work we use a single new electronic index to describe the antioxidant activity of the flavonols, a special class of flavonoids. We also try to predict theoretically the antioxidant activity of some yet nonisolated flavonols. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Tunneling through a fluctuating barrier in the presence of a periodically driving field
Authors: Saha Aparna , Sarkar Pranab
Published: February 2004

The zero and finite temperature tunneling dynamics of a periodically driven particle moving in a bistable potential with a fluctuating barrier is studied. We have focused on the influence of barrier fluctuation and thermal modulation on the tunneling processes in the presence of a driving field. At zero temperature, for a fixed strength of the driving field, both the tunneling probability and rate passes through a well‐defined minimum when plotted as a function of fluctuation frequency while it reveals a clear maximum as a function of driving frequency. However, at T > 0 the tunneling probability and rate show two maxima as a function of both fluctuation frequency and driving frequency. In both zero and finite temperature, the tunneling rate constant decreases with increasing fluctuation strength. So, the barrier fluctuation may enhance the stability of a periodically driven system. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Role of resonances in building collision cross‐sections: Mittag‐Leffler‐based study
Authors: Alferova Tatjana , Elander Nils
Published: February 2004

The method of complex dilation is used to define the partial wave S‐matrix in the sector of the fourth quadrant of the complex energy plane. Two ways of obtaining the expansion coefficients—the partial wave S‐matrix residues—are studied. The Mittag‐Leffler decomposition of the partial wave S‐matrix as a sum of residue terms and an integral contribution is used to define the contributions of a number of the partial wave S‐matrix poles, related to a 1‐D potential, to the corresponding S‐wave cross‐section. The obtained expansion demonstrates a way of describing the contribution from a single pole to the partial wave S‐matrix and thereby to various types of cross‐sections. Our model study shows how peaks in a cross‐section not only can be attributed to so‐called isolated resonances but also to a set of overlapping barrier‐type resonances. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Construction of unique canonical coefficients for antisymmeterized geminal power states
Authors: Weiner B. , Ortiz J. V.
Published: February 2004

Coefficients often defined to be canonical for a given geminal may not be unique. In this article we show by carefully examining a theorem by B. Zumino how to construct unique canonical coefficients for a geminal. This result leads to expansions of antisymmeterized geminal power states solely in terms of natural generalized spin orbitals and positive geminal occupation numbers. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Polynitrogen clusters containing five‐membered rings
Authors: Cheng Li Ping , Li Se , Li Qian Shu
Published: February 2004

Possible structures of N15 cluster were examined by ab initio (MP2) and density functional theory (DFT) methods with the 6‐31G* basis set. Their stabilities were compared together with other polynitrogen clusters Nn (n = 8, 10–14) reported in the literature. The order of stability was made respectively according to even or odd numbers of the total nitrogen atoms in clusters. It is found that both for even‐numbered clusters N2n (n = 4–7) and odd‐numbered clusters N2n + 1 (n = 5–7) the thermodynamically most stable isomers are all based on pentazole units; for each one of Nn (n = 8, 10–15) clusters, the more conjugated the five‐membered ring the more stable is the isomer; and, the more side‐chains the N5 ring links the less stable is the isomer. Another finding is that the larger the cluster the less stable is the cluster for every series of clusters of (a) containing two five‐membered rings with an even number of total nitrogen atoms [N10 (D2d), N12 (C2h), N14 (C2h)], (c) containing one five‐membered ring and a side‐chain with an even number of total nitrogen atoms [N8 (CS), N10 (CS), N12 (CS), N14 (CS)], (d) containing one five‐membered ring and a side‐chain with an odd number of total nitrogen atoms [N11 (CS), N13 (CS), N15 (CS)], (e) chain clusters with an even number of total nitrogen atoms [N8 (C2h), N10 (C2h), N12 (C2h), N14 (C2h)], and (f) chain clusters with an odd number of total nitrogen atoms [N11 (C2v), N13 (C2v), N15 (C2v)]. For another series of clusters with two five‐membered ring units [N11 (C2), N13 (C2v), and N15 (C2v)] (series b) the N13 (C2v) shows the best stability. It is also found that the even‐numbered nitrogen clusters are more stable than the odd‐numbered ones in comparison of series (a) with (b), (c) with (d), and (e) with (f). © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Quantum interference effects in the Br2 electronic predissociation: Dependence upon the molecular properties
Authors: Farias Patricia M. A. , Longo Ricardo L.
Published: February 2004

The occurrence of quantum interference in the Br2 electronic predissociation has been observed for the first time. It is also shown that the quantum interference effects are strongly dependent upon the representation of the molecular properties, such as the kinetic coupling and the transition dipole moment. The fast Fourier transform method implemented within the wave packet formalism was used to simulate the time evolution of the molecular system under the influence of single monochromatic ultrashort laser pulses. The quantum interference has been inferred from the oscillatory behavior of the autocorrelation functions, which have also been used to calculate the cross‐sections, the branching ratios, and the selectivity. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Key fragmentation patterns of aporphine alkaloids by electrospray ionization with multistage mass spectrometry
Authors: Stévigny Caroline , Jiwan Jean‐Louis Habib , Rozenberg Raoul , de Hoffmann Edmond , Quetin‐Leclercq Joëlle
Published: February 2004

This work reports a detailed study of the fragmentations of aporphine alkaloids by electrospray ionization with multistage mass spectrometry (ESI‐MSn) in positive mode. In a first step the loss of the amino group and its substituent is observed. Further steps display the loss of the peripheral groups. Losses of methanol and CO are observed if an OH is vicinal to an OCH3 on the aromatic ring. Otherwise the spectra show radical losses of CH3. or CH3O. as the main fragmentations. If a methylenedioxy group is present losses of formaldehyde followed by CO are observed. These fragmentations yield important information on the structures of aporphines. Copyright © 2004 John Wiley & Sons, Ltd.
Screening method for pesticides in air by gas chromatography/tandem mass spectrometry
Authors: Egea Gonzalez F. J. , Mena Granero A. , Glass C. R. , Garrido Frenich A. , Martinez Vidal J. L.
Published: February 2004

A multiresidue method for determining more than 70 pesticides in air has been validated using a single injection with gas chromatography/tandem mass spectrometry (GC/MS/MS). The method validation considered both stages of sampling and analysis. The sampling method, based on active sampling using sorption in sorbent cartidges, was validated by generating standard atmospheres. Performance parameters of the method were evaluated, with a reduction in the limits of quantification by injecting a higher volume of sample extract, and increase of selectivity by the use of MS/MS detection mode. The method was based on solid‐phase extraction, which permits a degree of automation. The best adsorbents were found to be Chromosorb 106 and Tenax TA. The retention capacity of these sampling sorbents allows up to 1440 L of air to be sampled without any breakthrough for most of the compounds. Data were generated for assessing the potential exposure of bystanders. The application of the method to the analysis of the air in urban locations near agricultural areas showed that pesticides were present in most of the samples. Copyright © 2004 John Wiley & Sons, Ltd.
Negative ion mass spectra of Cys‐containing peptides. The characteristic Cys γ backbone cleavage: a joint experimental and theoretical study
Authors: Bilusich Daniel , Brinkworth Craig S. , Bowie John H.
Published: February 2004

The Cys residue initiates characteristic backbone cleavages of [M−H]− anions of Cys‐containing peptides. A combination of experiment and theory suggests that these processes are initiated by molecular recognition between the C‐terminal CONH− group (in this study all peptides have C‐terminal CONH2 groups) and the SH in the Cys side chain to form an SH ··· OC hydrogen bond. This process is exothermic by 60 kJ mol−1 (calculations at the HF/6‐31G(d)//AM1 level of theory). The structure of this reactive intermediate has the NH− of the amide group and the central CH of the Cys residue locked into position such that these groups effect an SN2 process to form an intermediate which can either (i) dissociate to give an RNH− species [the δ ion (process endothermic by 37 kJ mol−1 with a barrier of 132 kJ mol−1)], or (ii) effect deprotonation within the intermediate to eliminate RNH2 to give the γ backbone cleavage anion in a reaction exothermic by 40 kJ mol−1 with a barrier of 132 kJ mol−1. Collision‐induced mass spectra of the [MH]− anions of five selected Cys‐containing peptides all contain γ and (γ‐H2S) anions. Three of these spectra also show the less favoured δ cleavage anions. Copyright © 2004 John Wiley & Sons, Ltd.
Characterisation of new pyridazinofurocoumarins by electron ionisation and multiple stage tandem mass spectrometry using an ion trap mass spectrometer
Authors: Begala Michela , González‐Gómez Jose Carlos , Podda Gianni , Santana Lourdes , Tocco Graziella , Uriarte Eugenio
Published: February 2004

The inverse electron‐demand Diels‐Alder reaction between furocoumarinones and 3,6‐bis(methoxycarbonyl)‐1,2,4,5‐tetrazine was used to give pyridazinofurocoumarins in good yields. The structural characterisation of the synthesised compounds was achieved by NMR spectroscopy. The mass spectrometric behaviour was studied under electron ionisation conditions via sequential product ion fragmentation experiments (MSn). This study allowed the evaluation of the role played by the methyl substituent on the benzene ring of pyridazinofurocoumarins in their fragmentation pathways. Copyright © 2004 John Wiley & Sons, Ltd.
Evaluation of three ionisation modes for the analysis of chlorinated paraffins by gas chromatography/ion‐trap mass spectrometry
Authors: Castells P. , Santos F. J. , Galceran M. T.
Published: February 2004

The applicability of three ionisation modes to the analysis of short‐chain chlorinated paraffins (SCCPs) using gas chromatography coupled with mass spectrometry (GC/MS) was evaluated. MS conditions for electron ionisation (EI), positive chemical ionisation (PCI) and electron‐capture negative ionisation (ECNI) were optimised using commercially available individual tetra‐, penta‐ and hexachlorodecanes. In addition, mass spectra were studied and fragmentation pathways were proposed for each individual congener. Different fragment ions were evaluated for quantification, and ECNI‐MS using [HCl2]− and [Cl2]−. ions was selected for the determination of SCCPs. Quality parameters (repeatability, limits of detection and calibration range) were established for the proposed method, which was then applied to the analysis of SCCPs in river sediments. Copyright © 2004 John Wiley & Sons, Ltd.
Gas chromatography/mass spectrometric identification of dopaminergic metabolites in striata of rats treated with L‐DOPA
Authors: Loutelier‐Bourhis C. , Legros H. , Bonnet J.‐J. , Costentin J. , Lange C. M.
Published: February 2004

The ex vivo identification of dopaminergic metabolites present in rat striata after (L‐DOPA + benserazide) treatment is reported. The different metabolites have been identified as the trimethylsilyl derivatives in the striatal extracts by gas chromatography/mass spectrometry. Copyright © 2004 John Wiley & Sons, Ltd.
Qualitative analysis of phenolic compounds in apple pomace using liquid chromatography coupled to mass spectrometry in tandem mode
Authors: Sánchez‐Rabaneda Ferran , Jáuregui Olga , Lamuela‐Raventós Rosa Maria , Viladomat Francesc , Bastida Jaume , Codina Carles
Published: February 2004

The occurrence of phenolic compounds in apple residues resulting from the juice industry was investigated to provide an alternative use for this raw material. For the identification of these compounds, liquid chromatography coupled to ionspray mass spectrometry in tandem mode (LC/MS/MS) with negative ion detection was used. The residues were first extracted and then chromatographed on Sephadex LH‐20 to yield 13 fractions. Positive identification of the compounds was based on their retention times and mass spectra in full scan mode (MS), and in different MS/MS modes (product ion scan, precursor ion scan and neutral loss scan). In this way, 60 compounds, including cinnamic and benzoic acid derivatives and flavonoids, were identified, some of them not previously reported in apple waste. Copyright © 2004 John Wiley & Sons, Ltd.
Quantitative measurement of different ceramide species from crude cellular extracts by normal‐phase high‐performance liquid chromatography coupled to atmospheric pressure ionization mass spectrometry
Authors: Pettus Benjamin J. , Kroesen Bart‐Jan , Szulc Zdizslaw M. , Bielawska Alicia , Bielawski Jacek , Hannun Yusuf A. , Busman Mark
Published: February 2004

Normal‐phase high‐performance liquid chromatography (NP‐HPLC) coupled to atmospheric pressure ionization mass spectrometry (APCI‐MS) allows quantitative analysis of endogenous ceramide and dihydroceramide species from crude lipid extracts. Qualitative information for the species comes from observation of differences in chromatographic and mass spectrometric behavior between species (Pettus et al. Rapid Commun. Mass Spectrom. 2003; 17: 1017–1026). Quantitative analysis is achieved by (1) use of a synthetic internal standard as an extraction and injection control, (2) lack of salt adduction, ion suppression, or other matrix effects in APCI mode, and (3) consistent fragmentation and ionization of external standards across the physiologically relevant concentration range found in endogenous lipid samples. Application to the analysis and quantitation of ceramide and dihydroceramide from various cell lines is demonstrated. The results from APCI‐MS analysis corroborate and enhance information acquired from use of the diacylglycerol kinase assay for total ceramide measurement. This technique readily allows simultaneous quantitation of ceramide and dihydroceramide species. Copyright © 2004 John Wiley & Sons, Ltd.
m‐ary Search trees when m ≥ 27: A strong asymptotics for the space requirements
Authors: Chauvin Brigitte , Pouyanne Nicolas
Published: February 2004

It is known that the joint distribution of the number of nodes of each type of an m‐ary search tree is asymptotically multivariate normal when m ≤ 26. When m ≥ 27, we show the following strong asymptotics of the random vector Xn = t(X, … , X), where X denotes the number of nodes containing i − 1 keys after having introduced n − 1 keys in the tree: There exist (nonrandom) vectors X, C, and S and random variables ρ and φ such that (Xn − nX)/n − ρ(C cos(τ2log n + φ) + S sin(τ2log n + φ)) →n→∞ 0 almost surely and in L2; σ2 and τ2 denote the real and imaginary parts of one of the eigenvalues of the transition matrix, having the second greatest real part. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Functions that have read‐twice constant width branching programs are not necessarily testable
Authors: Fischer Eldar , Newman Ilan , Sgall Jiří
Published: February 2004

We construct a property on 0/1‐strings that has a representation by a collection of width‐3 read‐twice oblivious branching programs, but for which any two‐sided ϵ‐testing algorithm must query at least Ω(nδ) many queries for some fixed ϵ and δ. This shows that Newman's result [Testing of functions that have small width branching programs, SIAM J Comput 31 (2002), 1557–1570] cannot be generalized to read‐k‐times functions fork> 1. In addition, we exhibit a property that has also a representation by a CNF formula of constant clause size. Hence, the nontestability results extend to properties that in addition have small (constant size) 0‐witnesses. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
The rotation correspondence is asymptotically a dilatation
Authors: Marckert Jean‐François
Published: February 2004

The rotation correspondence is a map that sends the set of plane trees onto the set of binary trees. In this paper, we first show that when n goes to +∞, the image by the rotation correspondence of a uniformly chosen random plane tree τ with n nodes is close to 2τ (in a sense to be defined). The second part of the paper is devoted to the right and left depth of nodes in binary trees. We show that the empiric measure (suitably normalized) associated with the difference of the right depth and the left depth processes converges to the integrated super Brownian excursion. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Adding random edges to dense graphs
Authors: Bohman Tom , Frieze Alan , Krivelevich Michael , Martin Ryan
Published: February 2004

This paper investigates the addition of random edges to arbitrary dense graphs; in particular, we determine the number of random edges required to ensure various monotone properties including the appearance of a fixed size clique, small diameter and k‐connectivity. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Divide and conquer martingales and the number of triangles in a random graph
Authors: Kim J. H. , Vu V. H.
Published: February 2004

The goal of this paper is to present a novel application of a recent and useful martingale inequality. As an illustration, we prove an essentially sharp bound for the probability that a random graph contains significantly more triangles than expected. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Counting the onion
Authors: Dalal Ketan
Published: February 2004

Iteratively computing and discarding a set of convex hulls creates a structure known as an “onion.” In this paper, we show that the expected number of layers of a convex hull onion for n uniformly and independently distributed points in a disk is Θ(n2/3). Additionally, we show that in general the bound is Θ(n2/(d+1)) for points distributed in a d‐dimensional ball. Further, we show that this bound holds more generally for any fixed, bounded, full‐dimensional shape with a nonempty interior. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
K5‐free subgraphs of random graphs
Authors: Gerke S. , Schickinger T. , Steger A.
Published: February 2004

We consider a conjecture by Kohayakawa, Łuczak, and Rödl, which, if true, would allow the application of Szemerédi's regularity lemma to show Turán‐type results for all random graphs and any fixed graph H. We deal with 5‐partite graphs such that each part contains n vertices, and any two parts form an ε‐regular pair with m edges. Here, two sets of vertices U and W of size n form an ε‐regular pair with m edges if all subsets U′ ⊆ U and W′ ⊆ W with |U′|, |W′| ≥ εn satisfy ||E(U′, W′)| − |U′| |W′|m/n2| ≤ ε|U′| |W′|m/n2. We show that for each β > 0, there exists at most βm()10 such graphs that do not contain a K5 as a subgraph if m ≥ Cn5/3 for a constant C = C(β), ε is sufficiently small, and n is sufficiently large. This proves the special case of the conjecture when H equals the complete graph on five vertices. © 2004 Wiley Periodicals, Inc. Random Struct. Alg., 2004
Extraction and quantitative analysis of aneurysmal aorta for aiding endovascular stent grafting
Authors: Imamura Hiroshi , Sugimoto Naozo , Eiho Shigeru , Urayama Shin‐ichi , Ueno Katsuya , Inoue Kanji
Published: February 2004

In performing interventions including stent grafting, the suitability for stent grafting must be checked and the devices to be used must be designed preoperatively. For these purposes, the three‐dimensional shapes of the blood vessels in lesions or the paths of device placement must be measured accurately and quickly. In this paper, a method for measuring the aortal shape from CT angiogram (CTA) and for detecting lesions from the shape characteristics of these is presented. Specifically, this method extracts the blood flow area of the aorta by using a three‐dimensional edge‐preserving smoothing filter and a region growing method. Extracted blood vessels are classified by using their anatomical characteristics. After initial setting of the medial axis in a blood vessel, it determines the aneurysmal area based on the diameter of the blood vessel and modifies the medial axis. In addition, it detects lesions such as thrombi and calcifications near the blood flow borderline. Application of the method to 30 clinical cases has confirmed that the proposed method is effective in obtaining the shape of blood vessels. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 58–67, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10223
Speech recognition in a noisy environment using a speech signal estimation method based on the Kalman filter
Authors: Fujimoto Masakiyo , Ariki Yasuo
Published: February 2004

This paper proposes a speech signal estimation method based on the Kalman filter, as preprocessing for speech recognition in a noisy environment. Hitherto, the Kalman filter has been considered unsuited to real‐time processing, since it requires a tremendous amount of computation. Consequently, the purpose of this paper is to reduce the amount of computation in the Kalman filter and to propose a speech signal estimation method for real‐time processing, using high‐speed operation. In order to evaluate the proposed method, a word recognition experiment was performed, using a speech signal extracted from speed with superposed noise. The accuracy of the word recognition tests is compared to the conventional spectral subtraction method and the parallel model combination method in order to demonstrate that the proposed method can deal automatically with various kinds of stationary noise without manual adjustment of the filter parameters for the conditions, such as the speaker, the kind of noise, and the SNR. For this purpose, the range of noise compensation by the proposed method is investigated. It is verified that the proposed method achieves a high word recognition rate, even in the presence of noise that degraded the recognition rate in the conventional method. In particular, the proposed method is effective in environments with a low SNR. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 46–57, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10257
Designing a distributed algorithm for bandwidth allocation with a genetic algorithm
Authors: Kobayashi Hidehiro , Munetomo Masaharu , Akama Kiyoshi , Sato Yoshiharu
Published: February 2004

When stream communications which requires a certain bandwidth during a certain time is to be realized on an existing network, a bandwidth allocation algorithm that efficiently allocates network resources is crucial to satisfying user service requirements. In the optimization of allocation in a small‐scale network, the most efficient approach is to have one node manage network information and perform allocation in a concentrated scheme. However, in bandwidth allocation the computation time required for optimization increases in proportion to the network scale, and distribution of the algorithm becomes necessary in the implementation. Another advantage of the distributed scheme is that allocations can be continued even if a fault arises in the network, which improves the fault tolerance of the algorithm. This paper investigates distribution of the bandwidth allocation algorithm by using a genetic algorithm. An improved algorithm is proposed which can cope with the fault when it occurs in the network by the reallocation of all communications. The proposed algorithm includes both local optimization to optimize the allocation at each node to reduce the computation time, and global optimization to optimize the whole network by the tournament method while performing local optimization in each node. Simulation experiments comparing the performance of the concentrated algorithm and the proposed algorithm are described. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 37–45, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10350
An algorithm for localizing branch points of pulmonary vessels for nonrigid registration of the lungs
Authors: Shikata Hidenori , Yin Zhiming , Park Yongsup , Kitaoka Hiroko , Sato Yoshinobu , Johkou Takeshi , Nakamura Hironobu , Tamura Shinichi
Published: February 2004

Analyzing three‐dimensional image data based on time series plays an important role in analyzing the functions of human organs that function with periodic changes in their shapes. Our final goal is to analyze the breathing movement of the lungs by nonrigid registration of the volume data between different time phases with vascular branch points spanning the lungs as characteristic points and obtaining positional vectors of each point. This paper presents a method for accurately detecting the locations of the branch points using graph representations of the blood vessels as an essential technique for such analyses. The method proposed obtains graph representations of an object using a method previously published, obtains approximately a product set region by taking each branch as a cylinder by local distance transforms in the neighborhood of a branching point obtained from the graph representations, and takes the centroid of this region as the branching point. The accuracy and reproducibility of determination of the position of a branch point are very important for nonrigid registration using the branch points. The authors have shown the efficacy of the proposed method by constructing a model simulating a blood vessel system by combining the cylinders, evaluating the accuracy using the differences from the axial intersection points of the cylinders constituting the branch as a measure. The authors have confirmed experimentally that the proposed method detects a branch point at a branch point position defined without being significantly influenced by conditions of rotations etc. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 24–36, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10478
Lipreading method using color extraction method and eigenspace technique
Authors: Nakata Yasuyuki , Ando Moritoshi
Published: February 2004

This paper describes a lipreading system using a color extraction method and several eigenspace techniques. To detect a precise mouth position, the system first finds the rough position of the mouth by the color extraction method and then determines the precise position using an eigentemplate technique. To describe the mouth shape change, we developed an eigen waveform technique. The detected precise mouth position improves the accuracy of the eigen waveform, which results in a high recognition rate. We constructed an automatic lipreading system and an experiment revealed that this system recognizes 85% of 35 words and 69% of 100 words. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 12–23, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10508
A recommendation for IT‐driven knowledge sharing
Authors: Inuzuka Atsushi , Nakamori Yoshiteru
Published: February 2004

In this paper, the authors propose a scheme for using simulation techniques to evaluate organizational knowledge sharing. Currently, trials for sharing knowledge within the organization have been undertaken at various corporations, but their effects are not sufficiently understood. Although the objectives for knowledge sharing vary from company to company, if attention is focused only on the reuse of knowledge, its effectiveness can be evaluated from an efficiency standpoint. In this paper, the authors limit the purpose of knowledge sharing to the reuse of knowledge and represent knowledge sharing within an organization hypothetically by modeling the acquisition, storage, and reuse of knowledge. Using this model, they introduce conditions for the superiority of the codification strategy or personalization strategy, which are forms of knowledge sharing. In addition, they propose an application model in which organization‐specific conditions are represented and add a detailed analysis to it. Finally, they extend the discussion by taking into consideration the properties of knowledge, and from the results that are obtained, they refer to points that should be considered when looking at IT‐driven knowledge sharing, which has been popularized in recent years. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 1–11, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.10560
Nonlinear principal component analysis by learning nerve fields united by inhibitory connections
Authors: Shirakura Jun , Kurata Koji
Published: February 2004

The authors propose a model with feedforward and a recurrent self‐organizing maps model which can extract nonlinear principal components. This model consists of several learning nerve fields that are mutually inhibiting each other, and is an extension of the self‐organizing overlapping maps model proposed previously by the authors. The feedforward model is sufficient for nonlinear principal component analysis, but the recurrent model with symmetrical inhibitory connections between nerve fields has additional interesting characteristics. © 2004 Wiley Periodicals, Inc. Syst Comp Jpn, 35(3): 68–78, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/scj.1230
Modeling, Simulation, and Experimentation of a Promising New Packaging Technology: Parallel Fluidic Self‐Assembly of Microdevices
Authors: Lienemann J. , Greiner A. , Korvink J. G. , Xiong X. , Hanein Y. , Böhringer K. F.
Published: February 2004

The parallel fluidic self‐assembly of microdevices is a new technology that promises to speed up the production of complex microsystems made up of many separate parts. The technology brings many advantages. First, it enables a mix of chipmaking technologies for each of the component parts, with each technology selected for its particular technical or financial benefits. Second, it eliminates the need for pick‐and‐place assembly that would unnecessarily slow down any manual assembly technique. Third, it enables massively parallel assembly, almost independent of the number of parts involved, and thereby mimics the elegant parallelism inherent in microchip circuit manufacture.

In this chapter we explore this new technology with the ultimate goal of discovering the practical limits for its practical use in manufacturing real microsystems. The driving force of the assembly process is interface surface tension, and our approach is to find the simplest models that correctly describe the attachment, orientation, and bonding of parts to a suitably prepared substrate. We follow both an analytical and a numerical approach in describing the surface tension effects, the latter mainly to gain geometrical generality, and we couple modeling and simulation with suitable laboratory experiments. The ultimate goal of this work is to find practical design rules with which to select bond site geometries and the properties of participating liquids, and to find practical tolerances for all required geometrical and rheological parameters. This chapter extensively documents all results found to date, and carefully cites other work in this area.
Fluorescent Ion‐Sensing Microspheres for Multiplexed Chemical Analysis of Clinical and Biological Samples
Authors: Peper Shane , Bakker Eric
Published: February 2004

This review summarizes recent advances in the development of chemically selective microspheres with a view to developing new, attractive methodologies in clinical and biomedical analysis. In particular, the development of fluorescent ion‐selective microspheres that function analogously to established bulk optodes is discussed. The fluorescent signal is dependent on a selective ion extraction process into a hydrophobic bulk phase doped with selective complexing agents. A mild preparation process for making large numbers of such microspheres is reported. Among a multitude of different applications, these beads may be applied in analytical flow cytometry in order to form part of a total bead‐based suspension array analysis system. Applications toward low detection limit measurements, as well as advances in polymer chemistry to develop plasticizer‐free ion sensing beads, are also discussed.
Optical Sensors in Medical Care
Authors: Öberg P. Åke
Published: February 2004

Optical assessment of physiological parameters constitutes a group of measurement principles, which are very attractive because they often provide simple, non‐invasive, continuous physiological monitoring conditions.

Optical principles have been used in medical diagnosis since the dawn of the medical sciences. Well‐known examples are the typical pallor of an anaemic patient or the yellowish skin of a baby with jaundice. Skin colours, and changes in skin colours, are typical for a number of infectious diseases.

The interest for diagnosis, based on optical principles, has increased in recent years, partly because of the availability of new instruments and methods utilizing new optical technology.

For a long time optical instruments have been used for analysis of samples taken from the patient in the laboratory. In these types of instruments, an optical beam typically passes a cuvette containing the sample and properties of the sample can be extracted by analysing absorption or scattering of light from the sample. A newer trend is that data are collected directly from a patient, thereby eliminating the need of sample collection.

This paper discusses the principles of three such optical diagnostic measurements:

Near infrared spectroscopy, pulse oximetry, laser Doppler flowmetry/imaging.

These three methods have been chosen as examples of bio‐optical progress and because they represent technologies at various stages of introduction into use in health care.
Chemical Composition, Starch Bioavailability and Indigestible fraction of Common Beans (Phaseolus Vulgaris L.)
Authors: Vargas‐Torres Apolonio , Osorio‐Díaz Perla , Tovar Juscelino , Paredes‐López Octavio , Ruales Jenny , Bello‐Pérez Luis A.
Published: February 2004

In Mexico, consumption of beans represents 15% of the normal diet of the population in rural zones. Four common bean varieties cultivated in Mexico were studied regarding their chemical composition, starch digestibility and indigestible fraction. The protein level in the samples Huasteco, Tacana and TLP 19 was not different (α = 0.05), but Veracruz cultivar had the highest protein and ash content, and the lowest lipid level. Differences in chemical composition were determined in the cultivars studied. Total starch (TS) ranged between 33.6 and 36.7%, and the cultivars Tacana, TLP 19 and Veracruz were not different in starch content (α = 0.05). The available starch (AS) determined represented between 74 and 87% of TS, due to the resistant starch content and perhaps some complex formed between starch and protein or starch and polyphenols, by the high level of the indigestible fraction determined in the beans. The in vitro α‐amylolysis rate was similar for the different varieties, except for Veracruz cultivar which presented a slightly lower hydrolysis rate.