bluuebunny/crossref_metadata_2025 huggingface dataset:
Levodopa treatment does not affect low‐dose apomorphine test in patients with Parkinson's disease
Authors: Happe Svenja , Tings Tobias , Helmschmied Kathrin , Neubert Karin , Wuttke Wolfgang , Paulus Walter , Trenkwalder Claudia
Published: July 2004

Challenge with low‐dose apomorphine causes a significant rise in growth hormone (GH) in patients with Parkinson's disease (PD) compared to controls and patients with multiple system atrophy (MSA) who have not previously received dopaminergic treatment. To date, it has not been demonstrated whether an apomorphine‐induced rise in GH can still be detected in PD patients who are currently treated with levodopa. We investigated whether an ongoing treatment with levodopa influences the GH response to subcutaneously applied low‐dose apomorphine in PD patients. We studied 44 patients with idiopathic PD using the low‐dose apomorphine test. Twenty‐three patients were under treatment with levodopa and 21 patients were without any dopaminergic therapy. GH and cortisol levels were analyzed at time of injection and 45 minutes and 60 minutes after subcutaneous apomorphine injection. Forty‐five minutes after apomorphine injection, there was no significant difference between the mean rise in plasma GH in untreated PD patients compared with levodopa‐treated patients (P = 0.235). There was no increase of cortisol levels in each treatment group. Age, sex, duration, and severity of the disease did not show a covariate effect with GH levels. A small group of PD patients (n = 8) treated with dopamine agonists and a small group of patients with MSA (n = 5) as well as patients with vascular parkinsonism (n = 5) did not show any increase of GH. Our data suggest that the apomorphine‐induced rise in GH does not depend on previous levodopa treatment in PD patients but, as expected, is blocked by dopamine agonists and is not present in patients with other than idiopathic parkinsonian syndrome. Thus, the low‐dose apomorphine test may also be a useful biological marker in the early differential diagnosis of PD patients who have already received levodopa treatment. © 2004 Movement Disorder Society
Dopamine receptor gene polymorphisms in Parkinson's disease patients reporting “sleep attacks”
Authors: Rissling Ida , Geller Frank , Bandmann Oliver , Stiasny‐Kolster Karim , Körner Yvonne , Meindorfner Charlotte , Krüger Hans‐Peter , Oertel Wolfgang H. , Möller J. Carsten
Published: July 2004

Genes encoding proteins involved in dopaminergic transmission are potential candidate genes for the induction of somnolence in Parkinson's disease (PD) because dopaminergic agents have been shown to be associated with sudden onset of sleep (SOS) in PD. We conducted an association study on dopamine D2, D3, and D4 receptor gene polymorphisms comparing 137 PD patients with SOS and 137 PD patients without SOS matched according to drug therapy, disease duration, sex, and age. Our results show a significant association between the dopamine D2 receptor gene polymorphism Taq IA and SOS in PD. No significant association between two other investigated polymorphisms and the phenomenon of “sleep attacks” in PD was observed. © 2004 Movement Disorder Society
Nurr1 mutational screen in Parkinson's disease
Authors: Tan Eng‐King , Chung Henry , Chandran Vandana R. , Tan Chris , Shen Hui , Yew Kenneth , Pavanni Ratnagopal , Puvan Kathi‐avelu , Wong Meng‐Cheong , Teoh Mei‐Lin , Yih Yuan , Zhao Yi
Published: July 2004

We performed sequence analysis of all the exons and exon–intron boundaries in familial and young‐onset Parkinson's disease (PD) in an Asian cohort. None of the patients carried any pathogenic mutations in the Nurr1 gene. We demonstrated a 5 to 10% prevalence of the intron 7 +33 C→T variant among Malay and Indian PD and healthy controls, suggesting that this variant, which was previously described only in 1 Chinese patient, was not a silent mutation but a common polymorphic variant in some ethnic races. © 2004 Movement Disorder Society
Patch application of the dopamine agonist rotigotine to patients with moderate to advanced stages of restless legs syndrome: A double‐blind, placebo‐controlled pilot study
Authors: Stiasny‐Kolster Karin , Kohnen Ralf , Schollmayer Erwin , Möller J. Carsten , Oertel Wolfgang H. ,   The Rotigotine Sp 666 Study Group
Published: July 2004

Efficacy and safety of the dopamine agonist rotigotine (RTG) was investigated in patients with moderate to severe idiopathic restless legs syndrome (RLS), including daytime symptoms. Three fixed doses of rotigotine (1.125 mg, 2.25 mg, and 4.5 mg) and placebo were applied by patches (size, 2.5 cm2 per 1.125 mg) in a double‐blind, randomized, parallel‐group, multicenter, 1‐week, proof‐of‐principle trial. The primary efficacy measure was the total score on the International Restless Legs Syndrome Scale (IRLS). Additionally, the RLS‐6 scale, the Clinical Global Impressions (CGI), and a sleep diary were used. Of 68 enrolled patients, 63 (mean age, 58±; 9 years; 64% women) were randomly assigned. RLS severity improved related to dose by 10.5 (1.125 mg RTG/die; P = 0.41), 12.3 (2.25 mg RTG/die; P = 0.18), and 15.7 points (4.5 mg RTG/die; P < 0.01) on the IRLS compared to placebo (8 points). According to the RLS‐6 scales, daytime symptoms significantly improved with all rotigotine doses. The CGI items supported the favorable efficacy of the 4.5‐mg dose. Skin tolerability of the patches and systemic side effects were similar between rotigotine and placebo. This pilot study suggests that continuous delivery of rotigotine by means of a patch may provide an effective and well‐tolerated treatment of RLS symptoms both during night and day. © 2004 Movement Disorder Society
Attractor for a conserved phase‐field system with hyperbolic heat conduction
Authors: Grasselli Maurizio , Pata Vittorino
Published: July 2004

We consider a conserved phase‐field system of Caginalp type, characterized by the assumption that both the internal energy and the heat flux depend on the past history of the temperature and its gradient, respectively. The latter dependence is a law of Gurtin–Pipkin type, so that the equation ruling the temperature evolution is hyperbolic. Thus, the system consists of a hyperbolic integrodifferential equation coupled with a fourth‐order evolution equation for the phase‐field. This model, endowed with suitable boundary conditions, has already been analysed within the theory of dissipative dynamical systems, and the existence of an absorbing set has been obtained. Here we prove the existence of the universal attractor. Copyright © 2004 John Wiley & Sons, Ltd.
Interaction of faults under slip‐dependent friction. Non‐linear eigenvalue analysis
Authors: Ionescu Ioan R. , Wolf Sylvie
Published: July 2004

We analyse the evolution of a system of finite faults by considering the non‐linear eigenvalue problems associated to static and dynamic solutions on unbounded domains. We restrict our investigation to the first eigenvalue (Rayleigh quotient). We point out its physical significance through a stability analysis and we give an efficient numerical algorithm able to compute it together with the corresponding eigenfunction.

We consider the anti‐plane shearing on a system of finite faults under a slip‐dependent friction in a linear elastic domain, not necessarily bounded. The static problem is formulated in terms of local minima of the energy functional. We introduce the non‐linear (static) eigenvalue problem and we prove the existence of a first eigenvalue/eigenfunction characterizing the isolated local minima. For the dynamic problem, we discuss the existence of solutions with an exponential growth, to deduce a (dynamic) non‐linear eigenvalue problem. We prove the existence of a first dynamic eigenvalue and we analyse its behaviour with respect to the friction parameter. We deduce a mixed finite element discretization of the non‐linear spectral problem and we give a numerical algorithm to approach the first eigenvalue/eigenfunction. Finally we give some numerical results which include convergence tests, on a single fault and a two‐faults system, and a comparison between the non‐linear spectral results and the time evolution results. Copyright © 2004 John Wiley & Sons, Ltd.
Projecting the flow variables for hub location problems
Authors: Labbé Martine , Yaman Hande
Published: July 2004

We consider two formulations for the uncapacitated hub location problem with single assignment (UHL), which use multicommodity flow variables. We project out the flow variables and determine some extreme rays of the projection cones. Then we investigate whether the corresponding inequalities define facets of the UHL polyhedron. We also present two families of facet defining inequalities that dominate some projection inequalities. Finally, we derive a family of valid inequalities that generalizes the facet defining inequalities and that can be separated in polynomial time. © 2004 Wiley Periodicals, Inc. NETWORKS, Vol. 44(2), 84–93 2004
Solving the Hub location problem in telecommunication network design: A local search approach
Authors: Carello G. , Della Croce F. , Ghirardi M. , Tadei R.
Published: July 2004

This article deals with a Hub Location Problem arising in Telecommunication Network Design. The considered network presents two different kinds of nodes: access nodes, that represent source and destination of traffic demands but cannot be directly connected, and transit nodes, that have no own traffic demand but collect traffic from access nodes and route it through the network. Transit nodes are supposed to be fully connected. Given a set of access nodes and a set of potential locations for the transit nodes, the problem is to decide number and positions of the transit nodes to guarantee that all access nodes are allocated to a transit node, satisfying capacity constraints. The goal is to minimize the total cost of the network, which is the sum of connection costs and nodes fixed costs. The problem is a Hub Location Problem, which is known to be NP‐hard. A local search approach is proposed, and different metaheuristic algorithms, such as tabu search, iterated local search and random multistart, have been developed, based on such local search. [A preliminary procedure has been developed in a research project joint with Telecom Italia (Turin Research & Innovation Laboratories) and a patent application has been filed to cover this issue.] © 2004 Wiley Periodicals, Inc. NETWOEKS, Vol. 44(2), 94–105 2004
A hierarchic 3D finite element for laminated composites
Authors: Kuhlmann Guido , Rolfes Raimund
Published: July 2004

In this paper a new 3D multilayer element is presented for analysis of thick‐walled laminated composites. This element uses two steps to calculate the full stress tensor. In the first step the in‐plane stresses are computed from the material law using a displacement approximation, and then the transverse stresses are calculated from the 3D equilibrium equations. Since the 3D equilibrium equations require high‐order interpolation functions, a hierarchic interpolation of displacements is used. The new element is compared with existing ones, e.g. from MSC.MARC. Copyright © 2004 John Wiley & Sons, Ltd.
Numerical analysis of a three‐dimensional super‐elastic constitutive model
Authors: Auricchio Ferdinando , Stefanelli Ulisse
Published: July 2004

This note deals with the efficient approximation of a non‐linear constitutive relation arising in the study of the three‐dimensional mechanical behaviour of shape memory alloys at constant temperature. In particular, a variable time‐step discretization is investigated. For such an algorithm we prove sharp error estimates of optimal order and exactness for a class of experimentally relevant situations. We also report numerical results relative to proportional and non‐proportional loading tests which fully confirm the theoretical analysis. Copyright © 2004 John Wiley & Sons, Ltd.
LayTracks: a new approach to automated geometry adaptive quadrilateral mesh generation using medial axis transform
Authors: Quadros W. R. , Ramaswami K. , Prinz F. B. , Gurumoorthy B.
Published: July 2004

A new mesh generation algorithm called ‘LayTracks’, to automatically generate an all quad mesh that is adapted to the variation of geometric feature size in the domain is described. LayTracks combines the merits of two popular direct techniques for quadrilateral mesh generation—quad meshing by decomposition and advancing front quad meshing. While the MAT has been used for the domain decomposition before, this is the first attempt to use the MAT, for the robust subdivision of a complex domain into a well defined sub‐domain called ‘Tracks’, for terminating the advancing front of the mesh elements without complex interference checks and to use radius function for providing sizing function for adaptive meshing. The process of subdivision of a domain is analogous to, formation of railway tracks by laying rails on the ground. Each rail starts from a node on the boundary and propagates towards the medial axis (MA) and then from the MA towards the boundary. Quadrilateral elements are then obtained by placing nodes on these rails and connecting them inside each track, formed by adjacent rails. The algorithm has been implemented and tested on some typical geometries and the quality of the output mesh obtained are presented. Extension of this technique to all hexahedral meshing is discussed. Copyright © 2004 John Wiley & Sons, Ltd.
Achieving minimum length scale in topology optimization using nodal design variables and projection functions
Authors: Guest J. K. , Prévost J. H. , Belytschko T.
Published: July 2004

A methodology for imposing a minimum length scale on structural members in discretized topology optimization problems is described. Nodal variables are implemented as the design variables and are projected onto element space to determine the element volume fractions that traditionally define topology. The projection is made via mesh independent functions that are based upon the minimum length scale. A simple linear projection scheme and a non‐linear scheme using a regularized Heaviside step function to achieve nearly 0–1 solutions are examined. The new approach is demonstrated on the minimum compliance problem and the popular SIMP method is used to penalize the stiffness of intermediate volume fraction elements. Solutions are shown to meet user‐defined length scale criterion without additional constraints, penalty functions or sensitivity filters. No instances of mesh dependence or checkerboard patterns have been observed. Copyright © 2004 John Wiley & Sons, Ltd.
Atypical mycobacterial infections in children with cancer
Authors: Reilly Anne F. , McGowan Karin L.
Published: July 2004

Atypical mycobacteria are seen more frequently as a cause of serious infection in children with cancer. Thirteen pediatric cancer patients with blood or tissue cultures positive for atypical mycobacteria were identified by review of records over a 5‐year period at one center. All had central venous catheters and were lymphopenic at the time of infection. Eleven children had rapidly growing mycobacteria and two children had M. avium‐intracellulare. Nine patients had positive blood cultures. Three were treated with catheter removal as sole therapy, five had catheter removal plus antibiotics, and one had antibiotics alone. Two patients with pulmonary M. avium‐intracellulare infection received antibiotic therapy alone. It is concluded that infection with rapidly growing mycobacteria in children with cancer is associated with presence of a central venous catheter and lymphopenia. Some children with uncomplicated catheter‐associated infection with rapidly growing mycobacteria may be sufficiently treated with removal of the catheter alone. © 2004 Wiley‐Liss, Inc.
Natural history of moderate aplastic anemia in children
Authors: Howard Scott C. , Naidu Paula E. , Hu X. Joan , Jeng Michael R. , Rodriguez‐Galindo Carlos , Rieman Martha D. , Wang Winfred C.
Published: July 2004

Background

Moderate aplastic anemia (MAA) in children is a rare, idiopathic condition of bone marrow insufficiency that can resolve spontaneously, persist for months or years, or progress to severe aplastic anemia (SAA). We evaluated the rate of progression to SAA.

Methods

We reviewed the records of 136 children referred for evaluation of bone marrow failure from 1978 to 2002 at St. Jude Children's Research Hospital. MAA was defined by a hypocellular bone marrow (<50%) and 2 or 3 cytopenias (absolute neutrophil count <1,500/mm3, absolute reticulocyte count <40,000/mm3, platelet count <100,000/mm3) lasting at least 6 weeks.

Results

Twenty‐four patients met the criteria for MAA. At a median follow‐up of 66 months (range, 10–293), 16 patients (67%) progressed to SAA, 5 (21%) had persistent MAA, and 3 (12%) had complete resolution of MAA. No risk factors for progression could be identified.

Conclusions

When childhood MAA is treated with supportive care alone, 2/3 of patients progress to SAA. © 2004 Wiley‐Liss, Inc.
Rhabdomyosarcoma, osteosarcoma, and adrenocortical carcinoma in a child with a germline p53 mutation
Authors: Khayat Catherine M. , Johnston Donna L.
Published: July 2004

A child with an unusual association of cancers is described. The patient first presented with a rhabdomyosarcoma of the right scapular muscle, and was successfully treated with chemotherapy. Six years after diagnosis of the first malignancy, the child presented with two synchronous malignancies: osteosarcoma of the jaw and adrenocortical carcinoma. Genetic mutation analysis was performed and revealed a germline p53 mutation of CGT > CAT at codon 273. The family history was negative for any other cancer consistent with the Li–Fraumeni syndrome. This case highlights the need for close surveillance of patients with p53 mutation for malignancy and describes the occurrence of two malignancies synchronously. © 2004 Wiley‐Liss, Inc.
Late effects on renal glomerular and tubular function in childhood cancer survivors
Authors: Bárdi Edit , Oláh Anna V. , Bartyik Katalin , Endreffy Emőke , Jenei Csaba , Kappelmayer János , Kiss Csongor
Published: July 2004

Background

Late nephrotoxicity among childhood cancer survivors is poorly documented.

Methods

We investigated 115 patients and 86 controls assessing serum cystatin C concentration (CysC), urinary N‐acetyl‐β‐d‐glucosaminidase activity (NAG), and microalbuminuria. Protenuria was quantified and electrophoresis performed. Polymorphism of the angiotensin convertase enzyme (ACE) gene was determined by genomic PCR.

Results

CysC was elevated in Wilms tumor (WT) patients. Gross proteinuria was observed in 30 patients including three patients with progressive proteinuria who improved on ACE‐inhibitor treatment. Neither patients with proteinuria nor the entire study population differed from controls with respect to ACE polymorphism. Pathologically elevated urinary NAG was noted in 38% of leukemia/lymphoma, 54% of solid tumor, 20% of WT survivors. A similar distribution of pathological microalbuminuria was found.

Conclusions

Mild‐to‐moderate subclinical glomerular and tubular damage can be identified in many childhood cancer survivors. However, most patients experience some spontaneous recovery from acute nephrotoxicity. © 2004 Wiley‐Liss, Inc.
Towards developing a protein infrared spectra databank (PISD) for proteomics research
Authors: Hering Joachim A. , Innocent Peter R. , Haris Parvez I.
Published: July 2004

Fourier transform infrared (FTIR) spectroscopy is an attractive tool for proteomics research as it can be used to rapidly characterize protein secondary structure in aqueous solution. Recently, a number of secondary structure prediction methods based on reference sets of FTIR spectra from proteins with known structure from X‐ray crystallography have been suggested. These prediction methods, often referred to as pattern recognition based approaches, demonstrated good prediction accuracy using some error measure, e.g., the standard error of prediction (SEP). However, to avoid possible adverse effects from differences in recording, the analysis has been mostly based on reference sets of FTIR spectra from proteins recorded in one laboratory only. As a result, these studies were based on reference sets of FTIR spectra from a limited number of proteins. Pattern recognition based approaches, however, rely on reference sets of FTIR spectra from as many proteins as possible representing all possible band shape variation to be related to the diversity of protein structural classes. Hence, if we want to build reliable pattern recognition based systems to support proteomics research, which are capable of making good predictions from spectral data of any unknown protein, one common goal should be to build a comprehensive protein infrared spectra databank (PISD) containing FTIR spectra of proteins of known structure. We have started the process of developing a comprehensive PISD composed of spectra recorded in different laboratories. As part of this work, here we investigate possible effects on prediction accuracy achieved by a neural network analysis when using reference sets composed of FTIR spectra from different laboratories. Surprisingly low magnitude of difference in SEPs throughout all our experiments suggests that FTIR spectra recorded in different laboratories may be safely combined into one reference set with only minor deterioration of prediction accuracy in the worst case.
Characterization of a digested protein complex with quantitative aspects: An approach based on accurate mass chromatographic analysis with Fourier transform‐ion cyclotron resonance mass spectrometry
Authors: Nakamura Takemichi , Dohmae Naoshi , Takio Koji
Published: July 2004

We describe a new approach for the characterization of a digested protein complex with quantitative aspects. Accurate masses of tryptic peptides in the digested complex were acquired by nano‐liquid chromatography Fourier transform‐ion cyclotron resonance mass spectrometry (MS). The conditions of the electrospray ion source were alternated to acquire normal and fragment‐ion‐rich mass spectra concurrently. This, alternating‐scan method, which includes no tandem mass spectrometry (MS/MS), allowed us to retain the integrity of the mass chromatograms and averted missed peptides due to MS and MS/MS switching. Tentative assignments of accurate peptide masses were verified with the concurrently acquired fragment‐ion‐rich spectra, and the identities of the protein components were established. For each identified protein component, mass chromatograms attributable to the validated accurate peptide masses were extracted, and the peak areas of multiple mass chromatograms were standardized. The standardized peak areas appeared to reasonably reflect the molar ratio of the protein components in standard mixtures. This new approach was successfully applied to the characterization of a cyanobacterial photosystem II complex preparation. A clear difference in the standardized peak areas was observed between the two groups of identified components, namely eight stoichiometric photosystem II proteins and two minor copurified phycobiliproteins.
New targets of Arabidopsis thioredoxins revealed by proteomic analysis
Authors: Marchand Christophe , Le Maréchal Pierre , Meyer Yves , Miginiac‐Maslow Myroslawa , Issakidis‐Bourguet Emmanuelle , Decottignies Paulette
Published: July 2004

Proteomics was used to search for putative thioredoxin (TRX) targets in leaves of the model plant, Arabidopsis thaliana. About forty different proteins have been found to be reduced by TRX, after TRX itself has been specifically reduced by its NADPH‐dependent reductase. Twenty‐one of the identified proteins were already known or recently proposed to be TRX‐dependent and nineteen of the proteins were new potential targets. The identified proteins are involved in a wide variety of processes, including the Calvin cycle, metabolism, photosynthesis, folding, defense against oxidative stress and amino acid synthesis. Two proteins from the glycine cleavage complex were also identified as putative TRX targets, and a new role can be postulated in leaves for TRX in defense against herbivores and/or pathogens.
A human proteome project with a beginning and an end
Authors: Humphery‐Smith Ian
Published: July 2004

Research activities centered on the ensemble of and individual human proteins have taken on numerous guises, some of which fall under the banner of what could be defined as a Human Proteome Project (HPP). However, the latter has yet to take‐on the apparent global focus of its predecessor, the Human Genome Project. The reasons for this are both financial and technical. The disparate properties afforded to each protein by a 20‐letter code render a single unifying approach difficult to implement, while the current limit of analytical detection has yet to deliver an entire proteome for even the simplest of microbes. The situation is complicated further by the fact that low abundance proteins dominate within any living cell. Thus, enhancement of signal‐to‐noise ratio by affinity ligands becomes of paramount importance if whole‐organism proteomics is to be realized. The generation of such ligands (molecules exhibiting desirable affinity and selectivity for target) could provide the necessary focus and a task list with a definable beginning and end. Such a finite task list is considered essential if an HPP might one day deliver global coverage on a scale seen currently for the total DNA sequence of some 200 living organisms.
The influence of phonon drag by diffusion carrier flux on the photoacoustic effect in semiconductors
Authors: Konin A.
Published: July 2004

A theory of the photoacoustic effect in semiconductors is developed for the region of fundamental absorption, taking into account phonon drag by the electron–hole pair diffusion flux. The temperature on the illuminated surface of a semiconductor is calculated in a general form. It is shown that the phase–frequency characteristics of the variable temperature on the illuminated surface depend essentially on the drag coefficient, sample thickness and light wavelength. The method of phonon‐defect collision frequency determination is proposed. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of temperature on the product of bulk modulus and volume thermal expansion coefficient, and its application to the thermal expansion of MgO and other minerals
Authors: Fang Ming‐xing , Ye Pin , Yan Zu‐tong
Published: July 2004

A particularly simple two‐parameter relation for the variation of the product of bulk modulus and volume thermal expansion coefficient of solids with changing temperature has been found. The relation, although empirical, fits all minerals tested. We used this relation for the isobaric equation of state and compared with other equations of state. The excellent results show that it can be successfully applied to study the temperature behavior of minerals from room temperature to high temperature. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Diffusion in silicon and the predictive power of ab‐initio calculations
Authors: Windl Wolfgang
Published: July 2004

In a recent paper, Leung et al. [Phys. Rev. Lett. 83, 2351 (1999)] reported a theoretical study where they calculated the formation energy for a neutral silicon self‐interstitial to be 4.9 eV using the diffusion quantum Monte Carlo (DMC) method, 50% (30%) higher than the LDA (GGA) result of “usual” ab‐initio calculations. In this paper, we show that gap and finite‐size corrections that have been proposed in the past might be able to explain this difference, as long as the defect levels for point defects are well known. We show that B‐interstitial systems are more difficult in that sense, which seriously questions the generality of the approach. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystallization in hafnia‐ and zirconia‐based systems
Authors: Ushakov S. V. , Navrotsky A. , Yang Y. , Stemmer S. , Kukli K. , Ritala M. , Leskelä M. A. , Fejes P. , Demkov A. , Wang C. , Nguyen B.‐Y. , Triyoso D. , Tobin P.
Published: July 2004

Crystallization of hafnia and zirconia and their alloys with silica and lanthana was studied in bulk and thin film samples by thermal analysis, X‐ray diffraction and electron microscopy. Crystallization temperatures of hafnia and zirconia increase by more than 300 °C with increase of surface/interface area of the amorphous phase. Crystallization temperatures of zirconia and hafnia alloys with silica and lanthana increase with dopant content and exceed 900 °C for 50 mol% SiO2 and LaO1.5. Energies for tetragonal HfO2 and ZrO2 interfaces with amorphous silica were derived from their crystallization enthalpies from silicates as 0.25 ± 0.08 and 0.13 ± 0.07 J/m2, respectively. The crystallization pathways in bulk powders and films of zirconia and hafnia can be interpreted as resulting from thermodynamic stabilization by the surface energy term of tetragonal and amorphous phases over monoclinic. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐pressure polymorphism in phosphorus nitrides
Authors: Dong Jianjun , Kinkhabwala A. A. , McMillan P. F.
Published: July 2004

Based on first‐principles density functional calculations, we have investigated the high‐pressure polymorphism of phosphorus nitrides (P3N5). In addition to the recently‐determined α and γ phases, our study predicts three new meta‐stable high pressure phases existing in the 5 to 35 GPa range, with structures related to the Al2SiO5 mineral polymorphs sillimanite, andalusite, and kyanite, and a new thermodynamically stable phase with a structure related to V3O5, that should form above 35.5 GPa. All these phases contain octahedrally coordinated phosphorus. By providing new insights on the different P–N bonding coordination within different pressure ranges and on the structural connection between isoelectronic oxides and nitrides, our predictive theoretical study will serve as a guideline for future experiments to explore synthesis of novel dense main group nitrides under high‐pressure conditions. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Investigations of conductance of photochromic switching molecules
Authors: Speyer Gil , Li Jun , Sankey Otto F.
Published: July 2004

Recent experimental work has confirmed a dramatic conductance enhancement of more than two orders of magnitude after the optical switching between two molecular isomers of a dithienylethene‐derivative on gold. To determine which dithienylethene‐derivative may be the optimal candidate for use as an optical molecular switch, it is necessary to understand the nature of the conductance switching. To this end, a variety of theoretical tools were employed to study the critical aspects of this unique metal‐molecule‐metal junction. A plane wave based density functional method revealed marked differences between the two isomers with regard to the line‐up of the molecular states and the contact states. A local orbital based density functional method was used to generate a tractable Hamiltonian for a Landauer based transport calculation. Three different derivatives are analyzed to determine which may be an appropriate candidate in a molecular electronic device. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Crystalline oxides on semiconductors: a future for the nanotransistor
Authors: Buongiorno Nardelli M. , Walker F. J. , McKee R. A.
Published: July 2004

In this paper we will broadly review the promises and advantages that crystalline‐oxides‐on‐semiconductors will bring to semiconductor technology. The central issue in the epitaxial oxide semiconductor system is the role of the interface. Preparation of the semiconductor surface is essential to successful, high quality, crystalline oxide formation. Furthermore, the chemical nature of the surface then controls such fundamental properties of the system as band offsets, band bending and transport. Drawing on recent accomplishments in determining key features in the structural and electronic properties of prototype Si/(Sr,Ba)O interfaces [R. A. McKee, F. J. Walker, M. Buongiorno Nardelli, W. A. Shelton, and G. M. Stocks, Science 300, 1726 (2003)], we will then illustrate how high‐performance simulations combined with experiments have been able to characterize an interface phase whose structure‐specific chemical bonding is fundamental in determining the properties of the semiconductor/crystalline oxide system. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analytic–numerical approach to calculate electronic nonadiabatic coupling terms: Study of the C2H molecule and the H2 + H system
Authors: Vibók Á. , Halász G. , A. M. Mebel  , Hu S. , Baer M.
Published: July 2004

The Curl equations (Baer, M. Chem Phys Lett 1975, 35, 112) are applied to calculate the nonadiabatic coupling terms, τij, subject to ab initio boundary conditions. As an example we consider a two‐state, planar system characterized by two (polar) coordinates, θ and q, and treat the corresponding components of τ, namely, τθ(q, θ) and τq(q, θ). The main difficulty that we encounter is that the vectorial Curl equation supplies, for this case, only one differential equation although we have two unknown functions. To overcome this difficulty we employ a gauge transformation that leads to a divergence equation—the missing equation. Next, the two Curl–divergence equations are treated with the aim of forming two decoupled second‐order differential equations for the two components of a vector potential A(q, θ) [which is related to τ(q, θ) through a gauge transformation], namely, one for Aθ(q, θ) [related to τθ(q, θ)] and one for Aq(q, θ) [related to τq(q, θ)]. The main achievement of the theory is a relation, for a given q1, between the Fourier coefficients of τq(q, θ) and those of τθ(q, θ). This approach is applied to three cases: an analytic model and two ab initio treatments—one for the C2H molecule and one for the H + H2 molecular system. In all three cases encouraging agreements were obtained between the ab initio‐calculated values of τq(q, θ) values and the ones that follow from the present approach. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Double‐electron capture processes in charge transfer reactions
Authors: Tergiman Y. S. , Bacchus‐Montabonel M. C.
Published: July 2004

Double‐electron capture processes may be important in some collisions of multiply charged ions with atomic or molecular targets and have thus to be taken into account carefully. An illustration of these mechanisms is presented in parallel with single‐electron capture on two examples involving the quadruply charged ions B4+ and N4+ in collision with a helium target. A complete ab initio molecular treatment of the potential energy curves and couplings followed by a semiclassic collision dynamics has been performed for these systems. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Density functional theory study of point defects in the SiSiO2 system and in substoichiometric titanium dioxide TiO2−x
Authors: Capron N. , Boureau G.
Published: July 2004

Density functional theory allows us now to calculate structural and energetic quantities related to nonstoichiometric oxides. Using as examples solutions of oxygen in silicon, substoichiometric titanium dioxide TiO2−x, and vacancies in silica, we show that, despite severe requirements in terms of computational effort, these calculations give insights into the nature of defects and their contribution to the macroscopic properties of nonstoichiometric oxides. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Tight‐binding parameterization of transition and noble metal clusters
Authors: Fortunelli Alessandro , Velasco Ana Marìa
Published: July 2004

The possibility of a tight‐binding (TB) parameterization of transition metal (TM) and noble metal clusters is investigated. An original procedure is proposed that allows one to derive the values of orthogonal‐TB matrix elements reproducing the exact one‐electron spectrum from an analysis of first‐principles density functional calculations. The procedure is applied to selected small metals clusters: Ni2, Pt2, Au2, Pt3, Ni13, Pt13, and Au13. Ni, Pt, and Au are taken as examples of first‐row TM and third‐row transition and noble metals. The diatomic molecules are chosen as the simplest examples of TM clusters, Pt3 allows one to compare closed‐shell and spin‐symmetry‐broken configurations, and the 13‐atom clusters are representative of larger systems. With respect to the current TB parameterizations, it is found that the p‐orbitals lie at higher energies (especially for third‐row TMs) than usually assumed, the diagonal matrix elements among d‐functions also depend on the bond directionality, and an s‐orbital relaxation effect is present for third‐row elements (especially Pt). The validity of the TB approach is substantially confirmed, as well as the possibility of a TB treatment of transition and noble metal clusters, provided that these effects are taken into account (e.g., more than one s‐orbital should be included in the TB parameterization for platinum). © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Theoretical study of hydrogenation of thiouracils and their base pairs with adenine
Authors: Eriksson Leif A. , Kryachko Eugene S. , Nguyen Minh T.
Published: July 2004

The purpose of the present work is to employ theoretical chemical tools to explore the subtle features of the hydrogenation of uracil and its related thioderivatives. The reactions of hydrogenation are followed for the free uracil, 2‐thiouracil, 4‐thiouracil, and 2,4‐dithiouracil as well as for adenine–thiouracil base pairs. It is shown for the first time that, in contrast to the hydrogenation pathways to the carbon atoms C5 and C6 of the studied molecules, characterized by the transition states, the hydrogenations at the sulphur atoms for thiouracils are barrierless and thus the latter are the kinetically most favorable pathways for hydrogenation. As also shown, these features are retained under the hydrogenation of the adenine–thiouracil base pairs. The present study clearly demonstrates that the base pairing destruction is the key radiation‐induced lesion in the adenine–4‐thiouracil and adenine–2,4‐dithiouracil base pairs when the hydrogen radical H·, as one of the primary radiation products, resides at the sulphur atom S4. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Rotational and alignment effects in a wave packet calculation for the Cl + H2 reaction
Authors: Skouteris Dimitris , Laganà Antonio , Capecchi Gabriella , Werner Hans‐Joachim
Published: July 2004

Time‐dependent quantum mechanical calculations have been carried out for a total angular momentum J = 0 to determine the distribution among product rovibrational states for the reaction Cl + H2 using product Jacobi coordinates. Calculations have been performed for the ground vibrational state of H2 (v = 0) and its rotational states j = 0–3. Moreover, calculations for the negative parity block of the J = 1, j = 1, K = 1 state have been carried out to get a picture of the geometry of approach dependence of reactivity. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
First‐principles calculation of formation energy of neutral point defects in perovskite‐type BaTiO3
Authors: Moriwake Hiroki
Published: July 2004

Quantitative analysis of the formation energy of neutral point defects in perovskite‐type BaTiO3 was carried out by first‐principles calculation. A 40‐atom supercell was employed and relaxation of atoms within the second‐nearest‐neighbor shell of the vacancy was taken into account. The formation energy was calculated as a function of the atomic chemical potential of the constituent atoms. The theoretical formation energy of the O vacancy in BaTiO3 shows negative values in the case of the reduction limit of BaTiO3, which is in good agreement with experimental results showing an abundance of O vacancies when annealed in reducing atmosphere and n‐type electrical conduction. On the other hand, the formation energies of the Ba vacancy and Ti vacancy in BaTiO3 even under the oxidizing condition are as large as 2.21 and 5.65 eV, respectively. This also well corresponds to the experimental fact that the Ba and Ti vacancies are not formed alone in BaTiO3. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Computations of the catalytic effects in the stone–wales fullerene isomerizations: N and CN agents
Authors: Slanina Zdenĕk , Uhlík Filip , Adamowicz Ludwik , Lee Shyi‐Long
Published: July 2004

The Stone–Wales rearrangement has long been considered as a plausible, albeit hypothetical, mechanism for fullerene annealing and isomerizations. In the view of a recently applied new catalyst, KCN, for incorporation of noble gases in fullerenes, the CN radical is studied here computationally as a possible catalytic species acting in kinetics of the Stone–Wales fullerene transformation, and a possible role of K+ is also investigated. The computations are performed on the PM3‐optimized bowl‐shaped model C34H12 to which the CN radical is attached by its C or N atom. The activation energies are evaluated at the UPM3, UHF/6‐31G*, UB3LYP/6‐31G*, ROB3LYP/6‐31G*, ROHF/6‐31G**, and ROB3LYP/6‐31G** levels. However, the reduction of the kinetic barrier owing to the catalyst action is modest so that a free N atom, neutral or charged, still remains a more efficient option. Effects of negatively charged CN species and of K+ are also found insufficient. Small amounts of nitrogen are indeed always present during fullerene synthesis, especially from He gas. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Distributed Gaussian basis sets: Variationally optimized s‐type sets for the open‐shell systems HeH and BeH
Authors: Glushkov V. N. , Wilson S.
Published: July 2004

Distributed basis sets of s‐type Gaussian functions are determined by invoking the variation principle for the restricted open‐shell matrix Hartree–Fock ground states of the open‐shell molecular systems HeH and BeH for nuclear separations of 1.500 bohr and 2.500 bohr, respectively. The calculated energy expectation values supported by these distributed basis sets are compared with the energies obtained from finite difference open‐shell Hartree–Fock calculations. The restricted open‐shell matrix Hartree–Fock calculations are performed by means of the asymptotic method. The accuracy of the approximations to the energy expectation values supported by the distributed basis sets of s‐type Gaussian functions is comparable with that attained in previous studies of closed‐shell systems. The parameters, that is, the exponents and positions defining the variationally optimized distributed basis sets, are presented and discussed. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Alternatives to multireference methods for the molecular electronic structure problem
Authors: Wilson S.
Published: July 2004

The development of robust many‐body methods for the molecular electronic structure problem with respect to multireference functions has attracted much attention over the past two decades. In recent years, multireference methods based on the Brillouin–Wigner expansion have been shown to overcome the intruder state problems which have plagued similar approaches based on the Rayleigh–Schrödinger series. However, there are some problems in molecular electronic structure theory, which may be handled by means of multireference methods, but can be treated by methods that avoid the use of multireference functions. We consider two examples of alternatives to multireference methods for the molecular electronic structure problem. The study of excited states having the same symmetry as the ground state or some lower lying excited state often involves the use of a multireference function. We describe an alternative procedure based on the generalized Rayleigh–Ritz variation principle. Gidopoulos, Glushkov, and Wilson have termed this the optimized trace method. The generalized Rayleigh–Ritz principle for the relativistic formulation of the molecular electronic structure problem is briefly also considered. Molecular dissociative processes are frequently described by quantum chemical methods based on multireference functions. Single‐reference Hartree–Fock methods usually provide a qualitatively incorrect description of such processes even in the simplest of molecules, H2. However, approximate single configuration wave functions constructed from nonorthogonal orbitals can often afford a useful approximation to bond‐breaking processes. Each occupied nonorthogonal orbital is then an eigenfunction of a different Fock‐like operator. Each of these Fock‐like operators supports a spectrum of M single particle states, where M is the size of the basis set, and only the lowest of these is occupied. We briefly consider the relativistic formulation of the molecular electronic structure problem based on approximations involving products of nonorthogonal functions within the Furry bound state interaction picture of quantum electrodynamics. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
Calculation of states of an ion Fe3 in crystal FeBO3
Authors: Filippov D. A. , Nikiforov I. S.
Published: July 2004

Method of the calculation of the energy levels and wave function of the S‐state ions is presented. Using the second order of the perturbation theory, the split of the ground term 6S by the spin‐orbit interaction with higher states is determined. Energy levels and wave function of the ion Fe3+ in the crystalline field model is obtained. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
ONIOM study of one‐carbon unit transfer from imidazolidine to dUMP analogue
Authors: Qi C. S. , Feng D. C. , Cai Z. T.
Published: July 2004

The ONIOM quantum mechanics method is used in this article to study one‐carbon unit transfer from an imidazolidine to 6‐aminouracil derivates. The computation results show that this reaction can be completed via three paths, owing to the three different proton transfer modes. Each path experiences three processes of nucleophile attacking, proton transferring, and bond rupturing. The focus of discussion falls on the proton transfer process. By analyzing the calculation results, we find that the direct proton transfer is the preferable pathway. © 2004 Wiley Periodicals, Inc. Int J Quantum Chem, 2004
A generational approach to understanding students
Authors: Coomes Michael D. , DeBard Robert
Published: July 2004

This chapter establishes the conceptual framework for understanding the Millennial generation by presenting a theoretical model of generational succession that demonstrates the value of studying how the values of one generation interact with and are influenced by others.
Millennials coming to college
Authors: DeBard Robert
Published: July 2004

This chapter demonstrates how literature about Millennial students offers a view of some of the thematic elements that bring this generation into focus for educators who would appeal to these characteristics to help students learn, develop, and grow.
Teaching, learning, and millennial students
Authors: Wilson Maureen E.
Published: July 2004

Literature on teaching and learning in college classrooms is reviewed and findings are discussed through a generational lens. From assumptions about generations of students, recommendations for enhancing student learning‐especially for Millennial students‐are provided.
Beispiele für verglaste Vertikalseilfassaden
Authors: Sobek Werner , Rehle Norbert
Published: July 2004

Verglaste Fassaden, deren tragende Konstruktion ausschließlich aus vertikal verlaufenden vorgespannten Seilen oder Zugstangen besteht, eröffnen die Möglichkeit einer weitestgehenden Minimierung des Materialverbrauchs bei gleichzeitiger Maximierung der Transparenz. Durch ihre Konstruktionsweise bedingt, weisen diese Fassaden unter Horizontalbelastung große Verformungen auf, welche durch Einbau von Federpaketen und Stoppern beeinflußt werden können. Unterschiedliche Glashaltesysteme und unterschiedliche Glasarten, bis hin zu explosionssicheren Isolierverglasungen, sind mit der Konstruktionsweise möglich. Der Aufsatz beschreibt die Entwicklung und die Charakteristika derartiger Fassaden anhand einer Reihe ausgeführter Beispiele.