bluuebunny/crossref_metadata_2025 huggingface dataset:
Look‐up tables for protein solvent accessibility prediction and nearest neighbor effect analysis
Authors: Wang Jung‐Ying , Ahmad Shandar , Gromiha M. Michael , Sarai Akinori
Published: July 2004

We developed dictionaries of two‐, three‐, and five‐residue patterns in proteins and computed the average solvent accessibility of the central residues in their native proteins. These dictionaries serve as a look‐up table for making subsequent predictions of solvent accessibility of amino acid residues. We find that predictions made in this way are very close to those made using more sophisticated methods of solvent accessibility prediction. We also analyzed the effect of immediate neighbors on the solvent accessibility of residues. This helps us in understanding how the same residue type may have different accessible surface areas in different proteins and in different positions of the same protein. We observe that certain residues have a tendency to increase or decrease the solvent accessibility of their neighboring residues in C‐ or N‐terminal positions. Interestingly, the C‐terminal and N‐terminal neighbor residues are found to have asymmetric roles in modifying solvent accessibility of residues. As expected, similar neighbors enhance the hydrophobic or hydrophilic character of residues. Detailed look‐up tables are provided on the web at www.netasa.org/look‐up/. © 2004 Wiley Periodicals, Inc. Biopolymers, 2004
Identification of differentially methylated CpG islands in prostate cancer
Authors: Yamada Yasushi , Toyota Minoru , Hirokawa Yoshifumi , Suzuki Hiroyoshi , Takagi Akimitsu , Matsuzaki Takeshi , Sugimura Yoshiki , Yatani Ryuichi , Shiraishi Taizo , Watanabe Masatoshi
Published: July 2004

Epigenetic change such as DNA methylation is one important mechanism for regulating gene expression as genetic change, such as mutation or loss of heterozygosity. Methylation of cancer‐related genes has been shown to play an important role in carcinogenesis and tumor progression. Using methylated CpG island amplification (MCA)/representational difference analysis (RDA), we identified four CpG islands in neurotrophin tyrosine kinase receptor type 2 (NTRK2), Protocadherine Flamingo1 and MFPC (Methylated Fragments in Prostate Cancer) 7 and 8. Bisulfite sequencing revealed that 2 regions of NTRK2 as well as MFPC7 and MFPC8 were aberrantly methylated in prostate cancer cell lines, and COBRA showed that 48 (76.24%), 37 (58.7%) and 14 (22.2%) of 63 prostate cancer tissues were methylated, respectively, for these sites. On the other hand, none of 13 benign prostate samples were methylated, except for 1 (7.7%) with NTRK2. For NTRK2, mRNA expression was negative in prostate cancer cell lines (LNCaP and DU145) but was recovered on a methyltransferase inhibitor (5‐Aza‐CdR) treatment. The role of NTRK2 within NTRK remains unclear. Our results suggest that these 3 hypermethylated DNA fragments also may be markers of prostate cancer detection. © 2004 Wiley‐Liss, Inc.
Levodopa in the treatment of Parkinson's disease: Current controversies
Authors: Olanow C. Warren , Agid Yves , Mizuno Yoshi , Albanese Alberto , Bonucelli U. , Damier Philip , De Yebenes Justo , Gershanik Oscar , Guttman Mark , Grandas F. , Hallett Mark , Hornykiewicz Ole , Jenner Peter , Katzenschlager R. , Langston William J. , LeWitt Peter , Melamed Eldad , Mena M.A. , Michel P.P. , Mytilineou Catherine , Obeso Jose A. , Poewe Werner , Quinn Niall , Raisman‐Vozari R. , Rajput Ali H. , Rascol Olivier , Sampaio Christina , Stocchi Fabrizio
Published: July 2004

Levodopa is the most effective symptomatic agent in the treatment of Parkinson's disease (PD) and the “gold standard” against which new agents must be compared. However, there remain two areas of controversy: (1) whether levodopa is toxic, and (2) whether levodopa directly causes motor complications. Levodopa is toxic to cultured dopamine neurons, and this may be a problem in PD where there is evidence of oxidative stress in the nigra. However, there is little firm evidence to suggest that levodopa is toxic in vivo or in PD. Clinical trials have not clarified this situation. Levodopa is also associated with motor complications. Increasing evidence suggests that they are related, at least in part, to the short half‐life of the drug (and its potential to induce pulsatile stimulation of dopamine receptors) rather than to specific properties of the molecule. Treatment strategies that provide more continuous stimulation of dopamine receptors provide reduced motor complications in MPTP monkeys and PD patients. These studies raise the possibility that more continuous and physiological delivery of levodopa might reduce the risk of motor complications. Clinical trials to test this hypothesis are underway. We review current evidence relating to these areas of controversy. © 2004 Movement Disorder Society
Comparing three different formulas for the internal impedance of a circular wire
Authors: Knockaert Luc
Published: July 2004

We derive rigorous expressions for the internal impedance of a circular wire in the quasi‐static and general cases and compare them with the classical formula. A comparison between the three formulas clearly indicates large discrepancies, even at relatively low frequencies. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 1–3, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20356
Low‐profile ultra‐wideband antenna for mobile phone applications
Authors: Wong Kin‐Lu , Tseng Ting‐Chih , Teng Pey‐Ling
Published: July 2004

A novel low‐profile ultra‐wideband (UWB) antenna suitable for mobile‐phone applications as an internal antenna is presented. The proposed antenna mainly comprises a planar metal‐plate monopole folded into a low‐profile structure and a matching tuning portion for achieving a very wide operating bandwidth (about 1.89–10.14 GHz in this study). With the very wide bandwidth obtained, the proposed antenna can easily cover the UMTS (1920–2170 MHz) band for mobile communications and the 2.4‐GHz (2400–2484 MHz) and 5.2/5.8‐GHz (5150–5350/5725–5875 MHz) bands for WLAN communications. Characteristics of the proposed UWB antenna applied to a UMTS/WLAN mobile phone are presented. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 7–9, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20358
Accurate and efficient analysis of stripline structures
Authors: Lucido M. , Panariello G. , Schettino F.
Published: July 2004

The aim of this paper is the analysis of the propagation parameters of stripline and boxed stripline structures. The solution method is based upon the use of the Neumann series to factorize the right‐edge behavior of the current, and hence lead to an accurate and quickly converging solution to the problem. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 14–21, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20361
Characteristic impedance of a microstrip line using a DGS cell
Authors: Yang Ru Yuan , Weng Min Hung , Wu Hung Wei , Huang Tsung Hui , Houng Mau‐Phon
Published: July 2004

In this paper, we study the size effects of an H‐shaped defected ground structure (DGS) cell upon the characteristic impedance of a microstrip line, by using a simple circuit‐analysis method. An LC model of an equivalent circuit can represent the proposed H‐shaped DGS cell. It is found that the characteristic impedance of a 50Ω microstrip line can be controlled easily in a wide range by using the H‐shaped DGS cell. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 34–37, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20367
An efficient finite‐difference frequency‐domain method including thin layers
Authors: Arft Carl M. , Knoesen André
Published: July 2004

A method is presented to incorporate thin, lossy layers into a finite‐difference frequency‐domain model while retaining a coarse grid‐spacing. This approach significantly reduces computational effort. The new method is validated by a comparison with analytical solutions. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 40–44, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20369
A fast wideband analysis of radiation and scattering problems by impedance‐matrix interpolation combined with progressive numerical method
Authors: Zhai Huiqing , Liang Changhong
Published: July 2004

It has been shown that impedance‐matrix interpolation is a very direct and effective technique to speed up the wide‐band analysis of radiation and scattering problems. In view of the time‐costing problem of solving the large impedance matrix using impedance‐matrix interpolation and the good performance of the progressive numerical method (PNM) for dealing with large electromagnetic problems, a fast and effective wideband analysis of radiation and scattering problems by impedance‐matrix interpolation combined with a progressive numerical method is presented in this paper. Some numerical results are given to illustrate the effectiveness and the accuracy of the proposed method. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 56–59, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20374
Frequency‐agile microstrip patch antenna using a reconfigurable mems ground plane
Authors: Al‐Dahleh R. , Shafai C. , Shafai L.
Published: July 2004

A frequency‐agile microstrip patch antenna is presented. A micromachined membrane is used as the ground plane below the antenna patch. Actuation of this membrane introduces an air gap between above the ground plane, and enables control of the antenna‐resonant frequency from 16.8 to 17.82 GHz (approximately 6% variation). © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 64–67, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20376
Wideband hexagonal‐shape stacked‐patch antenna array with L‐probe feed
Authors: Yang Steven S. L. , Luk K. M.
Published: July 2004

A two‐element hexagonal‐shape stacked‐patch antenna array fed by an L‐shaped probe is designed and measured. Experimental results show that the array achieves an impedance bandwidth of 34% (SWR < 1.5)/44% (SWR < 2) and a gain of 11.5 dBi. The far‐field radiation pattern is stable across the operation band. The antenna is attractive for modern mobile‐communications covering several frequency bands. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 77–79, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20379
WDM optical‐source generation using wavelength‐locked FP‐LDs with a spectrally sliced FP‐LD
Authors: Choi Woo‐Jun , Han Sang‐Jin , Kwon Hyuk‐Choon , Han Sang‐Kook
Published: July 2004

A downstream transmission using a wavelength‐locked Fabry–Perot laser diode (FP‐LD) with a spectrally sliced FP‐LD as a WDM optical source is presented and experimentally demonstrated for application to a WDM passive optical network (PON) link. A side‐mode suppression ratio (SMSR) of better than 40 dB is achieved by using an amplified and spectrally sliced FP‐LD as an external‐injection optical source. As a result, a downstream transmission of 622 Mb/s using a wavelength‐locked FP‐LD is successfully performed over 25 km. We can verify the feasibility of this method by its characteristics of simplicity, operational ease, and wavelength tunability. © 2004 Wiley Periodicals, Inc. Microwave Opt Technol Lett 43: 84–87, 2004; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.20382
Single machine parallel batch scheduling subject to precedence constraints
Authors: Cheng T.C.E. , Ng C.T. , Yuan J.J. , Liu Z.H.
Published: July 2004

We consider the single machine parallel batch scheduling problems to minimize makespan and total completion time, respectively, under precedence relations. The complexities of these two problems are reported as open in the literature. In this paper, we settle these open questions by showing that both problems are strongly NP‐hard, even when the precedence relations are chains. When the processing times of jobs are directly agreeable or inversely agreeable with the precedence relations, there is an O(n2) time algorithm to minimize the makespan. © 2004 Wiley Periodicals, Inc. Naval Research Logistics, 2004
An efficient numerical method for the resolution of the Kirchhoff‐Love dynamic plate equation
Authors: Bécache Eliane , Derveaux Grégoire , Joly Patrick
Published: July 2004

We solve numerically the Kirchhoff‐Love dynamic plate equation for an anisotropic heterogeneous material using a spectral method. A mixed velocity‐moment formulation is proposed for the space approximation allowing the use of classical Lagrange finite elements. The benefit of using high order elements is shown through a numerical dispersion analysis. The system resulting from this spatial discretization is solved analytically. Hence this method is particularly efficient for long duration experiments. This time evolution method is compared with explicit and implicit finite differences schemes in terms of accuracy and computation time. © 2004 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2005
Primary and secondary crystallization kinetic analysis of nylon 1212
Authors: Ren Minqiao , Song Jianbin , Zhao Qingxiang , Li Yuesheng , Chen Qingyong , Zhang Hongfang , Mo Zhishen
Published: July 2004

The isothermal and non‐isothermal melt‐crystallization kinetics of nylon 1212 were investigated by differential scanning calorimetry. Primary and secondary crystallization behaviors were analysed based on different approaches. The results obtained suggested that primary crystallization under isothermal conditions involves three‐dimensional spherulite growth initiated by athermal nucleation, while under non‐isothermal conditions, the mechanism of primary crystallization is more complex. Secondary crystallization displays a lower‐dimensional crystal growth, both in the isothermal and non‐isothermal processes. The crystallite morphology of nylon 1212, isothermally crystallized at various temperatures, was observed by polarized optical microscopy. The activation energies of crystallization under isothermal and non‐isothermal conditions were also calculated based on different approaches. Copyright © 2004 Society of Chemical Industry
Thermal analysis of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) irradiated under vacuum
Authors: Yang Huili , Liu Jingjiang
Published: July 2004

Poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) was irradiated by 60Co γ‐rays (doses of 50, 100 and 200 kGy) under vacuum. The thermal analysis of control and irradiated PHBV, under vacuum was carried out by thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The tensile properties of control and irradiated PHBV were examined by using an Instron tensile testing machine. In the thermal degradation of control and irradiated PHBV, a one‐step weight loss was observed. The derivative thermogravimetric curves of control and irradiated PHBV confirmed only one weight‐loss step change. The onset degradation temperature (To) and the temperature of maximum weight‐loss rate (Tp) of control and irradiated PHBV were in line with the heating rate (°C min−1). To and TP of PHBV decreased with increasing radiation dose at the same heating rate. The DSC results showed that 60Co γ‐radiation significantly affected the thermal properties of PHBV. With increasing radiation dose, the melting temperature (Tm) of PHBV shifted to a lower value, due to the decrease in crystal size. The tensile strength and fracture strain of the irradiated PHBV decreased, hence indicating an increased brittleness. Copyright © 2004 Society of Chemical Industry
Investigation on odd‐odd nylons based on undecanedioic acid: 1. Synthesis and characterization
Authors: Cui Xiaowen , Li Weihua , Yan Deyue
Published: July 2004

A series of odd‐odd polyamides were prepared through step‐heating melt‐polycondensation of undecanedioic acid with various diamines. The synthesized nylons were characterized comprehensively by means of elemental analysis, fourier‐transform infrared (FTIR) spectroscopy, nuclear magnetic resonance (NMR), Raman spectra, intrinsic viscosity, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The intrinsic viscosities of the prepared polyamides except nylon 3 11 are 0.70 to 0.87 dl g−1. The melting temperatures of the odd‐odd nylons range from 182 to 209 °C. In addition, the thermal mechanical properties of nylons 5 11, 7 11, 9 11 and 11 11 were analyzed using dynamic mechanical analysis (DMA). Nylon 3 11 could not undergo DMA due to its low molecular weight. The glass transition temperatures obtained from DMA are in the range 22–39 °C. Copyright © 2004 Society of Chemical Industry
Why biphenyl configuration still matters
Authors: Kahr Bart , Kaminsky Werner , Claborn Kacey
Published: July 2004

More than 40 years ago, Kurt Mislow synthesized restrained biphenyl derivatives, classically resolved them and correlated their absolute configuration with the sign of the Cotton effect. We have encountered biphenyl dyes in mixed crystals and crystalline tissues that were presumably resolved by interaction with chiral crystal facets or by adsorption to biopolymers. Understanding association mechanisms required that we likewise determine the absolute configuration, but inside organized media which traditionally do not reveal optical rotation or circular dichroism because of the dominance of linear anisotropies. We therefore recently invented the first circular extinction imaging microscope that can detect circular dichroism in low‐symmetry media, and also a new effect in crystal optics that we call anomalous circular extinction. Here, we show what information can be obtained from dyed, organized substances containing biphenyl derivatives by exploiting this new tool. Copyright © 2004 John Wiley & Sons, Ltd.
Time‐resolved IR studies of α‐lactones
Authors: Showalter Brett M. , Toscano John P.
Published: July 2004

A series of α‐lactones were generated from the reaction of phenylchlorocarbene, 4‐nitrophenylchlorocarbene, diphenylcarbene, bis(4‐nitrophenyl)carbene and bis(4‐methoxyphenyl)carbene with carbon dioxide and examined by nanosecond time‐resolved infrared (TRIR) spectroscopy. Estimated second‐order rate constants for the reaction of these carbenes with carbon dioxide indicate that more nucleophilic carbenes react at faster rates, in agreement with previous low‐temperature matrix experiments. Spectral TRIR data confirms that the structure of α‐lactones is dependent both on substituents at the α‐carbon and on solvent polarity, with electron‐donating substituents and polar solvents favoring a zwitterionic ring‐opened structure as opposed to the three‐membered ring oxiranone form. B3LYP calculations using self‐consistent reaction field (SCRF) methods also provide support for these experimental investigations. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and spectroscopic characterization of the first chiral molecular ‘hamburger’
Authors: Consiglio Giuseppe A. , Failla Salvatore , Finocchiaro Paolo
Published: July 2004

The incorporation of the common tetrasubstituted benzene ring II between two rigid bisphosphonate spirobiindane units gives rise to two diastereoisomers macrobicyclophanes VA and VB in high yield. The structures of these two diastereomers were assigned by 1‐D and 2‐D NMR. Both products shown a structure were the benzene ring is sandwiched between the cyclic frames to form a chiral molecular ‘hamburger’. Copyright © 2004 John Wiley & Sons, Ltd.
Structure, polymorphism and thermal properties of phenyliminoisoindolines
Authors: Zhang Zhi‐Qin , Uth Samnang , Sandman Daniel J. , Foxman Bruce M.
Published: July 2004

The crystal and molecular structures of (a) 1‐imino‐3‐phenyliminoisoindoline (2), (b) two polymorphs (3Mono and 3Tric) and a hexane solvate (3Hex) of 1,3‐bis(phenylimino)isoindoline (3) and (c) 3‐phenyliminoisoindolinone (4) were determined via single‐crystal x‐ray diffraction. The two polymorphs and solvate of 3 were all obtained by crystallization from hexane. In the solid state, 2 is found as the anti isomer of the amino tautomer, and all forms of 3 exist as either the syn,anti or anti,anti isomers of the diimino tautomer. The 3Tric and 3Mono polymorphs represent a rare example in which the phenomena of conformational polymorphism and conformational isomorphism occur for the same substance. Compound 4 crystallizes as the anti isomer of the keto form. Differential scanning calorimetry and thermogravimetric analysis were performed to characterize the thermal properties of samples of 2–4. X‐ray powder diffraction studies on 2, 3 and 4 reveal that, whereas specimens of 2 are a single phase, none of the samples of 3 and 4 crystallize as single phases under the conditions of the experiments. Copyright © 2004 John Wiley & Sons, Ltd.
Kinetic analysis of a reactive model enediyne
Authors: Semmelhack M. F. , Sarpong R.
Published: July 2004

A model framework related to the calcheamicin family of enediyne toxins was evaluated in its reactivity toward cycloaromatization through the arene 1,4‐diyl intermediates and hydrogen atom abstractions. The keto version 9 is relatively unreactive, with t1/2 = 1.5 h at 60°C. The product from hydride reduction of the ketone, alcohol 13b, is much more reactive, with t1/2=50 min at 0°C. In both cases, the rate of rearrangement is independent of the hydrogen atom donor, consistent with a rate‐determining first step (cyclization). Copyright © 2004 John Wiley & Sons, Ltd.
Cation–π complexes of a bowl‐shaped polycyclic aromatic hydrocarbon
Authors: Ansems Ronald B. M. , Scott Lawrence T.
Published: July 2004

Circumtrindene (1), a C36H12 geodesic polyarene that represents 60% of fullerene‐C60, forms cation–π complexes with both silver ion (1·Ag+) and tetramethylammonium ion [(Me)4N+·1] in chloroform solution at room temperature (Ka>20 M−1 for both cations). Preferential binding in the concave pocket of 1 is predicted by DFT calculations for both cations; however, this stereochemical assignment has not yet been confirmed experimentally. Copyright © 2004 John Wiley & Sons, Ltd.
Metallo‐supramolecular block copolymer micelles: Improved preparation and characterization
Authors: Mayer Gottfried , Vogel Vitali , Lohmeijer Bas G. G. , Gohy Jean‐François , Van Den Broek Jacomina A. , Haase Winfried , Schubert Ulrich S. , Schubert Dieter
Published: July 2004

Micelles prepared from amphiphilic block copolymers in which a poly(styrene) segment is connected to a poly(ethylene oxide) block via abis‐(2,2′:6′,2″‐terpyridine‐ruthenium) complex have been intensely studied. In most cases, the micelle populations were found to be strongly heterogeneous in size because of massive micelle/micelle aggregation. In the study reported in this article we tried to improve the homogeneity of the micelle population. The variant preparation procedure developed, which is described here, was used to prepare two “protomer”‐type micelles: PS20‐[Ru]‐PEO70and PS20‐[Ru]‐PEO375. The dropwise addition of water to a solution of the compounds in dimethylformamide was replaced by the controlled addition of water by a syringe pump. The resulting micelles were characterized by sedimentation velocity and sedimentation equilibrium analyses in an analytical ultracentrifuge and by transmission electron microscopy of negatively stained samples. Sedimentation analysis showed virtually unimodal size distributions, in contrast to the findings on micelles prepared previously. PS20‐[Ru]‐PEO70micelles were found to have an average molar mass of 318,000 g/mol (corresponding to 53 protomers per micelle, which is distinctly less than after micelle preparation by the standard method) and an average hydrodynamic diameter (dh) of 18 nm. For PS20‐[Ru]‐PEO375micelles, the corresponding values wereM= 603,000 g/mol (31 protomers per micelle) anddh= 34 nm. The latter particles were found to be identical to the “equilibrium” micelles prepared in pure water. Both micelle types had a very narrow molar mass distribution but a much broader distribution ofsvalues and thus of hydrodynamic diameters. This indicates a conformational heterogeneity that is stable on the time scale of sedimentation velocity analysis. The findings from electron microscopy were in disagreement with those from the sedimentation analysis both in average micelle diameter and in the width of the distributions, apparently because of imperfections in the staining procedure. The preparation procedure described also may be useful in micelle formation from other types of protomers. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4458–4465, 2004
Influence of ortho‐substituents on the synthesis and properties of poly(phenylacetylene)s
Authors: Mayershofer Martin G. , Wagner Martin , Anders Udo , Nuyken Oskar
Published: July 2004

The phenylacetylene derivatives (4‐decyloxyphenyl)acetylene (M1), (4‐decyloxy‐2‐methylphenyl)acetylene (M2), and (4‐decyloxy‐2,6‐dimethylphenyl)acetylene (M3) were polymerized by the well‐defined Schrock‐type initiator Mo[N‐2,6‐i‐Pr2C6H3)(CHCMe2Ph)[OCMe(CF3)2]2 (I1) and by the ill‐defined quaternary system MoOCl4–n‐Bu4Sn–EtOH–quinuclidine (1:1:2:1) (I2). Comparison of the compatibility of the initiators with the different monomers revealed a correlation of the size of the ortho‐substituents and the polymerizability of the monomers. M1 and M2 readily polymerized employing I1, but conversion of the sterically demanding monomer M3 remained incomplete. However, the use of I2 led to high monomer conversions and polymer yields only in case of M2 and M3. The steric bulkiness of the ortho‐substituents also decisively affected the maximum effective conjugation length (Neff) of the polymers and hence their absorption maximum (λmax) as well as their solution stability as shown by UV–vis and GPC studies, respectively. © 2004 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 42: 4466–4477, 2004
Structures and properties of (H2GaN3)n (n = 1–4) clusters: A DFT study
Authors: Xia Qi Ying , Xiao He Ming , Ju Xue Hai , Gong Xue Dong
Published: July 2004

Computations on the systems of (H2GaN3)n (n = 1–4) are performed using the density functional theory (DFT)/B3LYP method with different basis sets. (H2GaN3)2 possessing D2h symmetry is found to exhibit the planar Ga2N2 ring structure. (H2GaN3)3 involving a six‐membered Ga3N3 ring is found to exhibit two minima with very similar binding energies (ca. −235 ∼ −231 kJ · mol−1). One minimum is the newly found boat‐like conformation possessing Cs symmetry. Another minimum possessing C3v symmetry is the chair‐like conformation. (H2GaN3)4 occurs in several structures with Ga4N4 eight‐membered ring structures that correspond to minima with slight energy differences among them. The structural changes of the clusters are large compared with the monomer. Frequency calculations are carried out on each optimized structure, and their infrared (IR) spectra are discussed. Thermodynamic properties demonstrate that the systems of H2GaN3 occur at dimer–trimer–tetramer equilibrium, and the trimer is the main component. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Tests of perturbative DFT total energy estimates implemented in a Gaussian basis
Authors: Zhu Wuming , Trickey S. B.
Published: July 2004

We derive and test an approximate expression for the Kohn–Sham eigenfunctions and total energy associated with a given exchange‐correlation functional. The expression is closely related to the approximation given by Benoit et al. (Phys Rev Lett 2001, 87, 226401) but differs by removing an overly stringent orthogonality constraint. Tests on the Li, F, Ne, and Cr atoms done in Gaussian basis sets suggest that the approach is promising, particularly as an alternative to conventional self‐consistent field or to the Harris scheme (Phys Rev B 1985, 31, 1770). © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Simultaneous selected reaction monitoring, MS/MS and MS3 quantitation for the analysis of pharmaceutical compounds in human plasma using chip‐based infusion
Authors: Leuthold Luc Alexis , Grivet Chantal , Allen Mark , Baumert Mark , Hopfgartner Gérard
Published: July 2004

An assay method with mass spectrometric detection was developed for the quantitative analysis of a pharmaceutical compound and its major metabolite in human plasma using chip‐based infusion. Liquid‐liquid extraction sample preparation was found to be essential to minimize matrix suppression and to achieve a limit of quantitation (LOQ) of 2.5 ng/mL using a 100 μL plasma aliquot. The potential for simultaneous quantitation in selected reaction monitoring (SRM), tandem mass spectrometry (MS/MS) (enhanced product ion), and MS3 was investigated and found to be very beneficial in improving assay selectivity. A novel concept for monitoring quantitative assay performance using a SRM/MS3 ratio is proposed. Copyright © 2004 John Wiley & Sons, Ltd.
Black knight: An autonomous vehicle for competition
Authors: Gonzalez Fernando G. , Andres Richard , Deal David , Goergen Frank , Rhodes Matt , Roberts Tim , Stein Gary , Wilson Josh , Wong Sarah
Published: July 2004

Black Knight, the University of Central Florida's vehicle in the 11th Intelligent Ground Vehicle Competition (IGVC) competed in 2003. Completing in 5th place in the navigational challenge and 10th in the autonomous challenge in its first competition has proven our vehicle to be a strong competitor in this competition. The vehicle has many interesting features that allow it to achieve its success. The vehicle's 300 lb. capacity allows for two onboard full‐sized computers and two 12 V marine batteries that power the computers for up to 2 h. The vision system is not a simple reactive system but rather it classifies its view into objects and builds a map of the territory as it learns of its features while traveling. Two transformations and the location data from the GPS and other sensors are used to associate the locations in the image to locations in the map. The operations of the vehicle are modeled after the typical operations of a ship. We have programs that perform the functions of the captain, the helm, the navigator, and the engineer. In addition we have a program performing sensor data fusion from the GPS, compass, and wheel encoder data. The navigation uses an adapted two‐dimensional approximate cell decomposition method that satisfies the nonholononic constraints of our vehicle and allows it to find the shortest path to the goal while avoiding all obstacles. © 2004 Wiley Periodicals, Inc.
Vasilius: The design of an autonomous ground robotic vehicle
Authors: Snider Jarrod M. , Snider Amy E. , Riggins Robert N.
Published: July 2004

This paper presents the design and provides a partial analysis of the performance of an autonomous ground robotic vehicle called Vasilius. Applications for Vasilius include autonomous navigation on a somewhat marked path with obstacles, leader following, and waypoint navigation. The paper focuses on three aspects of Vasilius: the design, the performance, and a technique for filtering, mapping, and learning. The design of Vasilius embodies a novel idea of modeling an autonomous vehicle after human senses and the human decision‐making process. For instance, Vasilius integrates information from seven types of independent sensors, and categorizes them into either short‐range reaction sensors and/or long‐range planning sensors, analogous to what the human brain does. The paper also analyzes the performance of Vasilius, relating theoretical predictions to actual behavior. Some of these analyses, especially for the filtering, mapping, and learning, are still in progress. Performance measures that have been measured include speed, ramp climbing, turn reaction time, battery life, stop reaction time, object detection, and waypoint accuracy. Finally, the paper discusses Vasilius' use of a new approach to filtering, mapping, and learning to enhance its performance. © 2004 Wiley Periodicals, Inc.
Perceptions of child support and sexual activity of adolescent males
Authors: Huang Chien‐Chung , Han Wen‐Jui
Published: July 2004

Using the 1995 new cohort of the National Survey of Adolescent Males, this paper examines the association between perceptions of child support and adolescent males’ sexual activity. The results indicate that adolescent males who expect the chance of being required to pay child support is high if one becomes a non‐resident father or who has a family member who paid child support before are more likely to have the same female sexual partner and less likely to have had two or more female partners. Additionally, expectations of being required to pay child support and history of a family member paying child support are positively associated with contraceptive use, especially for Black adolescents.
Retrospective and prospective cognitions in adolescents: anxiety, depression, and positive and negative affect
Authors: Miles Helen , MacLeod Andrew K. , Pote Helen
Published: July 2004

Research with anxious and depressed adults has suggested that anxiety is related to an increased anticipation of both negative memories and negative expectancies whereas depression is related to a reduction in positive memories and expectancies. The present study examined whether anxiety and depression in 123 school‐aged adolescents would show the same pattern. Small groups completed a memory and future thinking task in which they were asked to generate future and past, positive and negative events. Adolescents with higher levels of depression and those with higher levels of anxiety reported significantly more negative events relative to controls, but neither group generated fewer positive events. The results provide support for the involvement of cognitions in mood disturbance although do not support the idea that these cognitions are different in anxiety and depression.
Influence and selection processes in friendships and adolescent smoking behaviour: the role of parental smoking
Authors: Engels Rutger C.M.E. , Vitaro Frank , Blokland Endy Den Exter , de Kemp Raymond , Scholte Ron H.J.
Published: July 2004

Concerning the role of parental smoking on development of adolescent smoking, most studies have exclusively focused on the direct effects of parents’ smoking on youths’ smoking. However, parental smoking may also play an indirect role by affecting youths’ susceptibility to peer influences and by affecting friendship selection. Data were from a three‐wave short‐term longitudinal study of 1595 adolescents. Findings showed high similarities in smoking between reciprocal friends. Additionally, friend's smoking and parents’ smoking were moderately related to adolescent smoking onset, but parents’ smoking did not moderate the prospective association between best friend's smoking and adolescent smoking. Finally, parental smoking seemed to affect the selection of new friends: In particular, adolescents with smoking parents were most likely to become affiliated with smoking friends. There was no evidence that parental smoking affected termination of friendships.
Prooxidative effects of TEMPO on human erythrocytes
Authors: Balcerczyk Aneta , Łuczak Katarzyna , Soszyński Mirosław , Bartosz Grzegorz
Published: July 2004

The prooxidative effects of 2,2,6,6‐tetramethylpiperidine‐1‐oxyl (TEMPO) were observed in human erythrocytes. Incubation of red blood cells with the membrane‐permeable TEMPO leads to a decrease in the concentration of intracellular reduced glutathione, accompanied by the reduction of TEMPO. Extracellular ferricyanide inhibited the loss of glutathione and reduction of TEMPO. TEMPO induced glutathione release from the cells and oxidation of hemoglobin to methemoglobin; ferricyanide prevented these effects. These results indicate that TEMPO may act as an oxidant to erythrocytes, whilst extracellular ferricyanide protects against its effects.
Impact of hypotonic solutions on the stromal swelling, lactate dehydrogenase and aldehyde dehydrogenase activity of the keratocytes of the bovine cornea
Authors: Doughty Michael J.
Published: July 2004

The present studies were designed to explore the relationship between the swelling‐related changes of the collagen—cell (keratocyte) matrix of the corneal stroma, and the integrity of the cells. From recent postmortem eyes of adult cattle, complete stroma preparations were dissected out and allowed to swell in solution (free swelling) or enclosed within a 12 kDa cut‐off dialysis membrane with or without spacers. The swelling was at 4 °C with either water, a hypotonic phosphate‐buffered saline (PBS, pH 7.0), a hypotonic mixed salt (MS) solution (pH 7.5), or an isotonic mixed salt solution with glucose (pH 7.5). Measures of tissue wet mass and thickness and analyses of the soluble protein, LDH and ALDH activity in the solutions were made. The relative swelling of the stroma preparations was greatest in water (to 624% of the original wet mass) > dilute PBS (to 404%) > dilute MS (to 381%) > MS with glucose (to 356%). The relative swelling was in the same order, but slightly less if the stroma preparations were enclosed in a dialysis tube with spacers, and substantially reduced when enclosed in a dialysis bag without spacers. With the use of hypotonic solutions, substantial quantities of proteinaceous material and enzyme activity were lost from the preparations, with the loss being proportional to the extent of swelling (p<0.001). Swelling of an isolated corneal stroma, especially in hypotonic solutions, is associated with substantial loss of soluble protein and cytoplasmic enzyme activities, and so these solutions must be considered as cytotoxic to the keratocytes.
B‐type natriuretic peptide and its precursor in cardiac venous blood from failing hearts
Authors: Goetze Jens Peter , Rehfeld Jens F. , Videbaek Regitze , Friis‐Hansen Lennart , Kastrup Jens
Published: July 2004

Background:

Plasma concentrations of B‐type natriuretic peptide (BNP‐32) and its precursor (proBNP) are increased in chronic heart failure. Accordingly, BNP‐32 and proBNP are both being implemented as clinical markers.

Aim:

To determine the molar relation of BNP‐32 and proBNP in different cardiovascular regions.

Methods and results:

Blood samples were obtained from different cardiovascular regions during right heart catheterization in heart failure patients, and from normal subjects. Plasma BNP‐32 and proBNP concentrations were measured using sequence‐specific radioimmunoassays. Patients with severe left ventricular dysfunction (n=21) displayed increased peripheral plasma concentrations of both BNP‐32 (four‐fold, P=0.0008) and proBNP (seven‐fold, P=0.0002) compared with normal subjects. Moreover, the peripheral concentrations were highly correlated with the corresponding concentrations in the coronary sinus (BNP‐32: r=0.97, P<0.0001; proBNP: r=0.94, P<0.0001). Despite comparable peripheral concentrations of BNP‐32 and proBNP, the BNP‐32 concentration was higher than the proBNP concentration in the coronary sinus (median 126 pmol/l (21–993) vs. 103 pmol/l (16–691), P=0.035).

Conclusions:

The BNP‐32 and proBNP concentrations are closely related in venous cardiac blood. The findings suggest an overall constitutive secretion of processed proBNP, i.e. an N‐terminal precursor fragment and BNP‐32, in chronic heart failure.
An exploratory study of the nature of cumulative capabilities
Authors: Flynn Barbara B. , Flynn E.James
Published: July 2004

This research sets out to test some yet unanswered questions from the literature on cumulative capabilities, as well as addressing some of the shortcomings in prior research on cumulative capabilities. Multiple regression analysis is used to test hypotheses using an existing data set of 165 plants in five countries and three industries. The findings indicate substantial differences in patterns of cumulative capabilities between countries and limited evidence of industry differences. Cumulative capabilities were found to be related to plant performance, with no difference in this relationship by industry. Support for sequential progression of cumulative capabilities was not evident, leading to the notion that development of cumulative capabilities is a complex endeavor, affected by many interrelated contingencies, not limited to sequence of development. A sequence of strategic initiative development was proposed and tested, finding support for a common foundation of practices related to cumulative capabilities, with limited support for the relationship between specific strategic initiatives and higher‐level cumulative capabilities.
Suspended sediment and hydrodynamics above mildly sloped long wave ripples
Authors: Chang Yeon S. , Hanes Daniel M.
Published: July 2004

We investigate the spatial and temporal distribution of suspended sediment and the associated hydrodynamics over mildly sloped long wave ripples on the inner shelf. These bedforms had wavelengths of approximately 1 m and heights of approximately 5 cm, in a mean water depth of 4 m. The vertical and temporal structures of the suspended sediment concentration (SSC) are consistent with the entrainment of sediment on the offshore flank of the ripple, and rapid vertical mixing at the time of flow reversal, followed by advection onshore by the onshore fluid motion. This work confirms that the mechanism for sediment suspension above low‐amplitude, long wave ripples is similar to the vortex formation process expected over steeper vortex ripples. Numerical simulations of the flow using the Dune2d model indicate that a separated rotational flow structure is generated at the flank of the ripple on the seaward side of the ripple crest, near the time of flow reversal. The simulations indicate that only one vortex is formed during each wave period, in agreement with the field observations. This asymmetry is due mainly to the presence of an offshore mean near‐bed current of approximately 6 to 8 cm/s. The SSC is calculated by the model and compared to the field observations. A hydraulic bed roughness of 10 to 15 median grain diameters (d50) was used in order to match the model prediction to the observed SSC approximately 1 cm above the seabed (cab). However, the modeled SSC and turbulent kinetic energy were significantly lower than the field observations at elevations exceeding approximately 2 cab.
Advective spreading of storm‐induced inertial oscillations in a model of the northwest Atlantic Ocean
Authors: Zhai Xiaoming , Greatbatch Richard J. , Sheng Jinyu
Published: July 2004

The spreading of inertial oscillations induced by the passage of Hurricane Juan (2003) across the Gulf Stream and the Scotian Shelf is examined using a regional model of the northwest Atlantic Ocean. It is found that surface‐intensified inertial oscillations develop at locations remote from the storm track after a period of 5–10 days. A diagnostic technique reveals the importance of advection by the background geostrophic flow for explaining this effect. The results suggest that advection by mean circulation can play a role in redistributing near‐inertial energy in the ocean. We argue that advective redistribution could have important consequences for understanding diapycnal mixing in the ocean.
First‐Ever European Space Weather Week
Authors: Simpson Sarah
Published: July 2004

Conference organizers emphasize the science and applications of space weather with a special effort to involve European agencies
Memory effects in collective dynamics of Brownian suspensions
Authors: Szymczak P. , Cichocki B.
Published: July 2004

We obtain macroscopic equations for average suspension velocity and particle current in a Brownian suspension valid on long time scales for which the memory effects are important. The coefficients in these equations depend solely on local properties of the medium. This formalism allows one to obtain well-defined theoretical expressions for transport coefficients, free of the integrals diverging with the size of the system. As an example, the expression for long-time collective diffusion coefficient is derived and the memory contribution to this coefficient is estimated.
Anisotropic colloidal particles in critical fluids
Authors: Eisenriegler E.
Published: July 2004

We consider anisotropic colloidal particles with dumbbell or lens shapes that are immersed in a critical binary fluid mixture. The orientation-dependent long-ranged universal interactions mediated by the critical solvent between a particle and a wall or between two particles are investigated for mesoscopic particle sizes small compared to the correlation length and interparticle distances. Exact results are obtained using a “small particle operator expansion.” The amplitudes of the isotropic and anisotropic operators in the expansion depend on the size and aspect ratio of the dumbbell or lens and are determined by density profiles in the Ising model at the critical point in a wedge geometry with symmetry-breaking fixed-spin boundary conditions. Dumbbells and ellipsoids with a symmetry preserving surface are also considered.
Hydrodynamics of bacterial colonies: Phase diagrams
Authors: Lega J. , Passot T.
Published: July 2004

We present numerical simulations of a recent hydrodynamic model describing the growth of bacterial colonies on agar plates. We show that this model is able to qualitatively reproduce experimentally observed phase diagrams, which relate a colony shape to the initial quantity of nutrients on the plate and the initial wetness of the agar. We also discuss the principal features resulting from the interplay between hydrodynamic motions and colony growth, as described by our model.
Structures of HCN-Mgn (n=2–6) complexes from rotationally resolved vibrational spectroscopy and ab initio theory
Authors: Stiles P. L. , Moore D. T. , Miller R. E.
Published: July 2004

High-resolution infrared laser spectroscopy has been used to determine the structures of HCN-Mgn complexes formed in helium nanodroplets. The magnesium atoms are first added to the droplets to ensure that the magnesium complexes are preformed before the HCN molecule is added. The vibrational frequencies, structures, and dipole moments of these complexes are found to vary dramatically with cluster size, illustrating the nonadditive nature of the HCN-magnesium interactions. All of the complexes discussed here have the nitrogen end of the HCN pointing towards the magnesium clusters. For Mg3, the HCN binds to the “threefold” site, yielding a symmetric top spectrum. Although the HCN-Mg4 complex also has C3v symmetry, the HCN sits “on-top” of a single magnesium atom. These structures are confirmed by both ab initio calculations and measurements of the dipole moments. Significant charge transfer is observed in the case of HCN-Mg4, indicative of charge donation from the lone pair on the nitrogen of HCN into the lowest unoccupied molecular orbital of the Mg4.
Spectroscopic implications of the coupling of unquenched angular momentum to rotation in OH-containing complexes
Authors: Marshall Mark D. , Lester Marsha I.
Published: July 2004

A model is developed for the rotational energy levels and electric dipole transition intensities of nonlinear OH-containing complexes in which the OH is hydrogen bonded to its partner. Both the 2A′ and 2A″ electronic states arising from the lifting of the OH monomer electronic orbital degeneracy are explicitly included. Consequently, the model smoothly spans the entire range of the difference potential associated with the separation between these two states, and the model accounts for the partial quenching of the OH monomer electronic angular momentum in such complexes. The more familiar cases of completely unquenched and completely quenched electronic angular momentum are recovered in the limits of zero and very large difference potential, respectively. The sensitivity of rovibrational spectra to the value of the difference potential is investigated, and it is shown that spectra of reactant complexes reveal the extent of quenching, which must occur along the reaction coordinate as the system evolves from weakly interacting partners to addition product. The model is successfully applied to the analysis of the OH overtone spectrum of the OH-acetylene complex.