bluuebunny/crossref_metadata_2025 huggingface dataset:
Classic ionic crystals and quantal Wigner electron solids: Role of electron correlation
Authors: March N. H.
Published: January 2003

Motivated by the pioneering studies of Löwdin on ionic crystals like NaCl and CsCl, and on electron correlation, recent work on the polarizability of the anion in such materials, and its relation to the free‐space polarizability, will first be reported. The essential role of electron correlation in treating negative ions will be emphasized. The Madelung energy, crucial for the stability of such classic ionic crystals, is then pointed out, within the framework of the jellium model of strongly interacting electrons, to lead to quantal Wigner electron crystals. Work will be summarized first on such an electron solid in three dimensions and in particular its melting curve will be discussed. Attention will then be focused on the freezing of the 2‐D liquid in a GaAs–AlGaAs heterojunction in a transverse magnetic field. Finally, it is stressed that electron–electron repulsion plus localization due to the applied magnetic field order the low‐density electrons into such a magnetically induced Wigner electron solid. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Quantum chemical study of the hydrogen‐bonded patterns in A · T base pair of DNA: Origins of tautomeric mispairs, base flipping, and Watson–Crick ⇒ Hoogsteen conversion
Authors: Kryachko Eugene S. , Sabin John R.
Published: January 2003

The current work aims to thoroughly investigate a variety of facets of the hydrogen‐bond pattern of the Watson–Crick A · T base pair of DNA. It offers a novel mechanism of the origin of the hydrogen‐bonded mispairing in the A · T base pair based on the analysis of the lower‐energy portion of the total potential energy surface of all possible rearrangements of the hydrogen‐bond patterns in this pair, performed at the Hartree–Fock (HF), second‐order Moller–Plesset (MP2)//HF, and B3LYP computational levels in conjunction with 6‐31+G(d) basis set. The specific novelty of this mechanism is that the primary step consists of a single proton transfer along the N3(T)–H … N1(A) hydrogen bond, thus leading to a transition state that is not directly related to the proton transfer. Rather, it governs the interbase shift within the A · T pair switching the hydrogen‐bonded pattern and then separating the normal A · T pair from the mispairing valley on its potential energy surface. The latter comprises three mismatched base pairs, easily converted to each other because of lower barriers (≈1 kcal/mol) of the corresponding proton transfers. It is demonstrated that, in terms of the Gibbs free energy taken at room T = 298.15 K, the most stable mispair in such valley is predicted to be less stable by 9.7 ± 2 kcal/mol than the Watson–Crick pair, thus implying that the spontaneous point mutations of this type occur as infrequently as to be characterized by an equilibrium constant of 10−6to 10−9. This estimate falls into the well‐known experimental range of mutation frequency per base pair. The structure of a so‐called “base flipping” of the A · T base pair, originated from a breaking of its N3(T)‐H … N1(A) hydrogen bond, is also found and reported in the current work for the first time. The transition state A · T, which governs the conversion of the Watson–Crick pair of adenine · thymine into the Hoogsteen one and is related to a breaking of the N6(A)–H … O4(T), is also obtained and its energetical and geometrical features are discussed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Molecular mechanics, quantum mechanics, potentiometric, and conductometric studies on the complexes of some rare earth metals with 5‐azorhodanine derivatives
Authors: El‐Gogary T. M. , El‐Dissouky A. , Hilali A. S.
Published: January 2003

The geometry of metal ions (La3+, Ce3+, UO, and Th4+) complexes with 5‐azorhodanine derivatives was optimized at the level of molecular mechanics. Two stoichiometric ratios of metal to ligand (i.e., 1:1 and 1:2) were investigated. Tetracoordinate and hexacoordinate of each stoichiometric ratio have been studied. Effect of substitution in the ligand on the geometry of the complexes was discussed in the light of electron donating–accepting properties of these substituents. The influence of the nuclear effective charge of the central metal ions on the metal–ligand (M–L) bonding was discussed and the effect of the number of ligands on the M–L bond length was also discussed and correlated to the experimental results. The total energies of the different metal complexes were computed using the extended Huckel method. The effect of substituents in ligand, metal type, and stoichiometry of the complexes on the complex total energies were discussed. Stability constant of (La3+, Ce3+, UO, and Th4+) metal ions with 5‐azorhodanine derivaties have been determined potentiometrically in 0.1 M KCl and 50% (v/v) ethanol–water mixture. The order of the stability constants of the formed complexes was found to be La3+ < Ce3+ < UO < Th4+. The influence of substituents on the stability of the complexes was examined on the basis of electron‐repelling property of the substituent. The effect of temperature on the stability of the complexes formed was studied and the corresponding thermodynamic parameters (ΔG, ΔH, and ΔS) were derived and discussed. The stoichiometries of these complexes were determined conductometrically and indicated the formation of 1:1 and 1:2 (metal:ligand) complexes. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Evolution of defect states in doped polythiophene: A study based on the method of simulated annealing
Authors: Chaudhury Pinaki , Bhattacharyya S. P.
Published: January 2003

A modified Su–Schrieffer–Heeger Hamiltonian‐based model is used to compute the electronic and geometric structures of fairly long polythiophene (PT) chains, neutral as well as doped. The geometry optimization is carried out by the simulated annealing method. Both Metropolis and Glauber functions are used for sampling. It is shown that a bipolaron can be structurally represented by a fragment of the PT chain containing 14 thiophene units. As a series of bipolaronic defects are introduced in a long PT chain (50–100 rings), the highest occupied molecular orbital (HOMO)–lowest unoccupied molecular orbital (LUMO) gap energy (Δ) becomes vanishingly small, a feature not present in the PT chains of similar sizes containing polaronic defects. The Fermi energy level (EF) also moves into the valency band and nonzero density of states at ϵ = EF are created. Once again, this feature is shown to be missing in PT chains containing polaronic defects. Implications of these findings are analyzed. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Cracking the genetic code(s) with a modular determinative degree: An algebraic approach
Authors: Négadi Tidjani
Published: January 2003

We introduce a new “modular” (compositional and positional) determinative degree for the four bases U, C, A, and G to define a “Dinucleotide charge number” for the dinucleotides, which discriminates between the two octets of dinucleotides: M1 and M2. These two components are exchanged under a transformation, which, we show, implements the Rumer symmetry. We invoke also the base “size index” of Rosen as a complementary determinative degree for the third‐base component of a codon. Next, we define the address functions for the 64 codons (amino acids), which are functions only of the composition and position of these codons in the genetic table. With these ingredients, we build an algebraic classification of the amino acids in the genetic code and some of its nonstandard versions as a preliminary application. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Origin of cis preference among the three isomers of 1,4‐difluorobutadiene
Authors: Hu Hai‐Rong , Gong Mao‐Chu , Tian Anmin , Wong Ning‐Bew
Published: January 2003

The slight energy differences among the three isomers of 1,4‐difluorobutadiene have been investigated by Gaussian‐3 (G3) theory. The computational results suggest that the Gaussian‐3–Becke's three‐parameter functional (G3B3) theoretical estimates are in good agreement with experimental data. Mulliken population analysis also has been performed to interpret the anomalous equilibrium relationship among these three isomers. Wire mesh contours of the highest occupied molecular orbital (HOMO) orbitals of these isomers help to illustrate the cis effect visually. Natural bond orbital (NBO) analysis indicates that the origin of cis preference among the three isomers may lie in the configurational orientation and the n‐π conjugative interaction between fluorine atom and CC double bond. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Improving the accuracy of ab initio methods with summation approximants and singularity analysis
Authors: Goodson David Z.
Published: January 2003

The accuracy of Møller–Plesset (MP) perturbation theory and coupled‐cluster (CC) theory can be significantly improved, at essentially no increase in computational cost, by using summation approximants that model the way in which these theories converge to the full configuration interaction limit. Approximants for MP4 and CCSD(T) are presented, their size scaling is analyzed, and the functional analysis of the MP energy, on which the MP4 approximant is based, is discussed. The MP approximants are shown to have a form that is appropriate for describing resonance energies. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
N‐band Hubbard models II: Cooperative mechanisms of electron–phonon, electron correlation, and many‐band effects toward high‐Tc superconductors
Authors: Yamaguchi Kizashi , Yamaki Daisuke , Kitagawa Yasutaka , Takahata Masahiro , Kawakami Takashi , Ohsaku Tadafumi , Nagao Hidemi
Published: January 2003

Discoveries of superconductivity of MgB2 by Akimitsu et al. and high‐Tc cupurate superconductors by Bednorz and Muller have raised great interest for elucidation of the superconducting mechanism from both experimental and theoretical grounds. The transition temperature (Tc) was found to be 40 K for MgB2, while the very high‐Tc over 130 K was reported for doped copper oxides with layer structures. A crucial role of the electron–phonon (EP) interaction was pointed out as a common mechanism of the superconductivity of both materials. However, such high‐Tc superconductivity may indicate the possibility of cooperative mechanism of the EP interaction with others such as electron correlation (EC) and multiband (MB) effects discussed in part I (Int J Quantum Chem 1990, 37, 167) of this series. Here, as a continuation of part I, theoretical backgrounds are briefly described to select active orbital space for superconductivity and elucidate the nature of EP, EC, and MB effects for cooperative mechanisms. Next, molecular orbital calculations of MgmBn and cage‐type carbon cluster are carried out to elucidate contributions of the EP interaction using McMillan equation. The relative contributions of the EP and EC interactions are also discussed in relation to the screening of the Coulomb repulsion. Pair binding energies are calculated for cage‐type carbon clusters. Finally, the cooperative mechanisms of the EP, EC, and MB effects are discussed to realize the high‐Tc superconductivity in molecule‐based materials such as cage compounds and nanotubes. Several possible candidates are proposed on both experimental and theoretical grounds. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Molecular similarity of potential endocrine disruptors: Structural index control of pharmacological clustering
Authors: King James W. , Molnar Stephen P.
Published: January 2003

A series of 37 substituted indoles for which estrogen receptor binding data had been reported were studied from a quantitative structure–activity relationship (QSAR) viewpoint. The structures were represented by an established unitary mathematical index, the molecular transform (FTm), whose derivation is entirely from the geometry‐optimized structure. Data clusters were generated by a primary numerically descending sort of the structure indices and a concurrent secondary numerically descending sort of the binding data. Reversal of numerical descent of the latter served to generate the cluster boundaries. Analysis within and across the clusters permitted a definitive and detailed picture of the influence of substituents and substituent positions on the molecule, and their effect on the biodata, and suggested the structure of a molecule of greater binding ability than any in the database. The relationship of the electronic and charge nature of the molecules to their binding ability was considered. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Ab initio fragment orbital‐based theory
Authors: Das G. P. , Yeates A. T. , Dudis D. S.
Published: January 2003

A new formulation of ab initio theory is presented that treats a large molecule in terms of wave functions of its constituent molecular subunits (to be called fragments). The method aims to achieve near conventional ab initio accuracy but using a truncated set of fragment orbitals with a consequent drastic reduction of computing time and storage requirement. Illustrative calculations are presented for the molecule amino‐nitro‐stilbene. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Charge exchange in C6++ H (1s) collisions at low energies
Authors: Saha Bidhan C.
Published: January 2003

The low‐energy single electron capture cross‐sections by C6+from H atoms have been evaluated employing the semiclassical, impact parameter, close‐coupling method based on a molecular expansion augmented with the plane‐wave translation factor. Using the method of Bates and Carson, the exact Born–Oppenheimer eigenfunctions and eigenvalues are calculated. Eight‐state coupled equations are solved to obtain transition probabilities and thereby evaluate capture cross‐sections. Our calculated capture cross‐sections agree well with other theoretical and experimental results. At these energies it is found that the capture into then= 4 manifold of the C5+remains the main contributor to the charge exchange process. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
Influence of hydrogen bonding on the properties of water molecules adsorbed in zeolite frameworks
Authors: Larin A. V. , Trubnikov D. N. , Vercauteren D. P.
Published: January 2003

Three hydrated aluminosilicate frameworks—LiABW, NaNAT, and BaEDI—are partly optimized with the periodic Hartree–Fock CRYSTAL95 code. In particular, we optimized the positions of the adsorbed water molecules including the positions of the framework cations (ABW, NAT) or part of the framework atomic positions (ABW). This allowed us to compare cation–water clusters in the gas and adsorbed states and discuss the influence of hydrogen bonding to the framework oxygen atoms or to the neighbor water molecules on the atomic properties (quadrupole coupling constant, anisotropy of electric field gradient) of the adsorbed water molecules. The LiBIK structure obtained from X‐ray diffraction is also considered to illustrate the hydrogen bonds occurring between adsorbed water molecules. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003
The shortest disjunctive normal form of a random Boolean function
Authors: Pippenger Nicholas
Published: January 2003

This paper gives a new upper bound for the average length ℓ(n) of the shortest disjunctive normal form for a random Boolean function of n arguments, as well as new proofs of two old results related to this quantity. We consider a random Boolean function of n arguments to be uniformly distributed over all 2 such functions. (This is equivalent to considering each entry in the truth‐table to be 0 or 1 independently and with equal probabilities.) We measure the length of a disjunctive normal form by the number of terms. (Measuring it by the number of literals would simply introduce a factor of n into all our asymptotic results.) We give a short proof using martingales of Nigmatullin's result that almost all Boolean functions have the length of their shortest disjunctive normal form asymptotic to the average length ℓ(n). We also give a short information‐theoretic proof of Kuznetsov's lower bound ℓ(n) ≥ (1 + o(1)) 2n/log n log log n. (Here log denotes the logarithm to base 2.) Our main result is a new upper bound ℓ(n) ≤ (1 + o(1)) H(n) 2n/log n log log n, where H(n) is a function that oscillates between 1.38826 … and 1.54169 … . The best previous upper bound, due to Korshunov, had a similar form, but with a function oscillating between 1.581411 … and 2.621132 … . The main ideas in our new bound are (1) the use of Rödl's “nibble” technique for solving packing and covering problems, (2) the use of correlation inequalities due to Harris and Janson to bound the effects of weakly dependent random variables, and (3) the solution of an optimization problem that determines the sizes of “nibbles” and larger “bites” to be taken at various stages of the construction. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 161–186, 2003
Simple analysis of graph tests for linearity and PCP
Authors: Håstad Johan , Wigderson Avi
Published: January 2003

We give a simple analysis of the PCP with low amortized query complexity of Samorodnitsky and Trevisan [16]. The analysis also applies to the linearity testing over finite fields, giving a better estimate of the acceptance probability in terms of the distance of the tested function to the closest linear function. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 139–160, 2003
Minors in graphs of large girth
Authors: Kühn Daniela , Osthus Deryk
Published: January 2003

We show that for every odd integer g ≥ 5 there exists a constant c such that every graph of minimum degree r and girth at least g contains a minor of minimum degree at least cr(g+1)/4. This is best possible up to the value of the constant c for g = 5, 7, and 11. More generally, a well‐known conjecture about the minimal order of graphs of given minimum degree and large girth would imply that our result gives the correct order of magnitude for all odd values of g. The case g = 5 of our result implies Hadwiger's conjecture for C4‐free graphs of sufficiently large chromatic number. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 213–225, 2003
Random channel assignment in the plane
Authors: McDiarmid Colin
Published: January 2003

In the model for random radio channel assignment considered here, points corresponding to transmitters are thrown down independently at random in the plane, and we must assign a radio channel to each point but avoid interference. In the most basic version of the model, we assume that there is a threshold d such that, in order to avoid interference, points within distance less than d must be assigned distinct channels. Thus we wish to color the nodes of a corresponding scaled unit disk graph. We consider the first n random points, and we are interested in particular in the behavior of the ratio of the chromatic number to the clique number. We show that, as n → ∞, in probability this ratio tends to 1 in the “sparse” case [when d = d(n) is such that the average degree grows more slowly than ln n] and tends to $2\sqrt{3}/\pi$ ∼ 1.103 in the “dense” case (when the average degree grows faster than ln n). We also consider related graph invariants, and the more general channel assignment model when assignments must satisfy “frequency‐distance” constraints. © 2003 Wiley Periodicals, Inc. Random Struct. Alg., 22: 187–212, 2003
Joint multi‐user detection and intersymbol interference cancellation for WCDMA satellite UMTS
Authors: da Silva Mário Marques , Correia Américo M. C.
Published: January 2003

In this work we present two different intersymbol interference (ISI) cancellation systems, namely the commutation signaling (CS) and orthogonal code‐division transmit diversity (O‐CDTD) in combination with satellite path diversity, which leads to a high diversity order. The ISI is due to the use of satellite path diversity (in order to introduce multipath diversity artificially). This work combines the proposed ISI cancellation systems with subtractive multi‐user detectors—a variation of the conventional parallel interference cancellation (PIC) and successive interference cancellation (SIC) for the downlink channel of S‐UMTS. The blind detection is also considered without knowledge of spreading sequences or the channel state information (CSI) of the interfering users with a noise whitening matched filter (NWMF) that combats the MAI through the whitening of the interfering power spectrum, also with and without the ISI cancellation systems—CS and O‐CDTD. It is shown that the proposed PIC is a very promising detector to be used for the downlink of S‐UMTS, especially when combined with CS or O‐CDTD, the NWMF being efficient only when we consider jointly any of the proposed ISI cancellation systems for low number of interfering users. Copyright © 2003 John Wiley & Sons, Ltd.
The pervasiveness of evolution in GRUMPS software
Authors: Evans Huw , Atkinson Malcolm , Brown Margaret , Cargill Julie , Crease Murray , Draper Steve , Gray Phil , Thomas Richard
Published: January 2003

This paper describes the evolution of the design and implementation of a distributed run‐time system that itself is designed to support the evolution of the topology and implementation of an executing, distributed system. The three different versions of the run‐time architecture that have been designed and implemented are presented, together with how each architecture addresses the problems of topological and functional evolution. In addition, the reasons for the rapid evolution of the design and implementation of the architecture are also described.

From the lessons learned in both evolving the design of the architecture and in trying to provide a run‐time system that can support run‐time evolution, this paper discusses two generally applicable observations: evolution happens all the time, and it is not possible to anticipate how systems will evolve as designs; and large, run‐time systems do not follow a predictable path. In addition to this, rapid prototyping has proved to be extremely useful in the production of the three architectures; this kind of prototyping has been made much easier by designing the core set of Java abstractions in terms of interfaces; and building an architecture that allows as many decisions as possible to be made at run‐time which has produced a support system that is more responsive to the user as well as the distributed environment in which it is executing. Copyright © 2003 John Wiley & Sons, Ltd.
Noradrenergic modulation of ephedrine‐induced hypophagia
Authors: Wellman Paul J. , Miller Dennis K. , Ho Dao H.
Published: January 2003

The hypophagic action of the sympathomimetic amine ephedrine (EPH) in the rat may reflect actions on central dopaminergic (DA) and noradrenergic (NE) systems. EPH indirectly facilitates DA and NE activity and acts as a partial agonist at α1‐adrenergic receptors. Two approaches were used to assess the possible contribution of NE and DA pathways to EPH‐induced hypophagia. In the first, regression analyses of published archival data were computed to characterize the relation between the hypophagic potency values of (−)‐(EPH) and related sympathomimetic drugs, including (+)‐amphetamine, aminorex, mazindol, and phentermine (data derived from Blosser JC et al., 1987) and the most potent action of these drugs on facilitating NE activity or DA activity in rat brain (data derived from Rothman RB et al., 2001). In the NE analyses, the ED50 values for these drugs for the inhibition of eating in rats were significantly related (r = 0.91, P = 0.03) to the potency of each drug in facilitating NE activity (either release or inhibition of [3H]NE reuptake), whereas in the DA analyses the correlation between ED50 values and DA activity for these drugs was also significant (r = 0.98, P = 0.003). The regression analyses are thus supportive of a role for NE or DA in the hypophagic capacity of EPH. Although an earlier study noted that administration of the putative DA antagonist pimozide in rats attenuated EPH hypophagia, pimozide exerts similar potency in antagonizing DA receptors and α1‐adrenergic receptors. To clarify the role of α1‐adrenoceptors in EPH‐induced hypophagia, adult male rats were pretreated with the α1‐adrenergic receptor antagonist prazosin (0.0.5 and 2 mg/kg) prior to the administration of (−)‐EPH (0, 5, 10, or 20 mg/kg, IP). Prazosin pretreatment at 2.0 mg/kg significantly attenuated the hypophagia, but not the hypodipsia, induced by administration of 10 mg/kg and by 20 mg/kg (−)‐EPH. Collectively, these results confirm a critical contribution of of α1‐adrenoceptors to the hypophagic action of (−)‐EPH in rats. Synapse 48:18–24, 2003. © 2003 Wiley‐Liss, Inc.
Performance prediction of networked information systems via Petri nets and queuing nets
Authors: Shin Insub , Levis Alexander H.
Published: January 2003

An approach is presented for generating a performance prediction model so that both qualitative (logical correctness) and quantitative (timeliness) properties of a real‐time system can be evaluated. The architecture of a system is layered into a functional layer and a physical one. Both architectural layers are developed as executable models: the executable functional model is a Petri net and the executable physical model is a queuing net. The two‐layered executable models are then connected to develop a performance prediction model. A message‐passing pattern is generated from the Petri net using a state space analysis technique. Then, the queuing net model processes these messages preserving the pattern. Once the network delays are obtained from the queuing model, their values are inserted back into the Petri net model. Since the communication service demands are isolated from the executable functional model, the communications network can be specified independently at any preferred level of detail. This enables the executable functional model to be invariant with respect to the executable physical model resulting in additional flexibility in designing a large‐scale information system. This property, together with the synthesis technique, enables both formal and simulation methods to be used together, when each one utilizes a different self‐contained commercial‐off‐the‐shelf software application. © 2002 Wiley Periodicals, Inc. Syst Eng 6: 1–18, 2003
A Model of System Coherence
Authors: Aslaksen Erik W.
Published: January 2003

Modeling of system behavior is an important part of the systems engineering methodology. One characteristic of system behavior that is common to a large class of systems is coherence, and we propose a simple model of coherent behavior, which at the same time gives an operational definition of system coherence. Results of simulation of system behavior obtained using this model are presented, and they display all the features normally associated with cooperative behavior. This indicates that with the proposed definition, coherence could become a useful system parameter. © 2002 Wiley Periodicals, Inc. Syst Eng 6, 19–27, 2003
Using objected‐oriented and UML tools for hardware design: A case study
Authors: Bahill Terry , Daniels Jesse
Published: January 2003

This paper argues for the adoption of object‐oriented design and UML tools for nonsoftware designs, i.e., systems, hardware and algorithms: This is a controversial position. It presents a case study, the design of a heating, ventilation, and air conditioning system, using UML tools. This case study also shows the incremental elaboration used to progress from the requirements model, to the analysis model, to the design model, etc. The paper finally discusses some difficulties that must be overcome in order to apply UML tools to system designs. © 2002 Wiley Periodicals, Inc. Syst Eng 6: 28–48, 2003.
On customer value and improvement in product development processes
Authors: Browning Tyson R.
Published: January 2003

In an effort to improve company operations and their results, more firms are applying the principles of “Lean”—not only to manufacturing but also to systems engineering processes. Too often, however, this is done with a shallow understanding of Lean and/or without a systems view, in which case Lean creates new problems and tensions and may not deliver expected results. Lean is not about just minimizing cost, cycle time, or waste. Lean is about maximizing value. In systems engineering or product development (PD), maximizing value may require doing more activities, not fewer. Since a process is a kind of system, a systems view and systems engineering principles are helpful. As the value of a system is more than the value of its individual components, the value of a process is more than the value of its individual activities. Value is driven not only by the presence of necessary (value‐adding) activities in the PD process but also by the way those activities work together to ensure that they use and produce the right work products, services, and information at the right time. This paper discusses how value is added in PD through work on activities and the production of deliverables. It integrates findings from several streams of research and provides bases upon which to build improved value models. It shows how the concept of Lean can broaden from asking “What wasteful activities can we stop doing?” to include insights from asking “What helpful activities can we start doing, and when?” © 2003 Wiley Periodicals, Inc. Syst Eng 6: 49–61, 2003. DOI 10.1002/sys.10034
Redox catalysts as sensitisers towards oxidative stress
Authors: Giles Niroshini M , Gutowski Nick J , Giles Gregory I , Jacob Claus
Published: January 2003

The predominance of oxidative stress in many tumour cell environments provides a means to selectively target these cells via protein oxidation. The zinc fingers of transcription factors utilise cysteine thiols for structural zinc coordination. Redox control of DNA binding regulates transcription and therefore the overall rates of proliferation, apoptosis and necrosis in the carcinoma. We report here the adverse effects of glutathione peroxidase (GPx) mimics towards zinc finger motifs and PC12 cell survival. Nanomolar catalyst concentrations facilitated H2O2‐induced oxidation of an Sp1 transcription factor fragment. In PC12 cells GPx catalysis triggered a significant increase in cell death, correlating with severity of oxidative stress. As a consequence, we conclude that GPx mimics are potential chemotherapeutic agents.
Candidate markers for stem and early progenitor cells, Musashi‐1 and Hes1, are expressed in crypt base columnar cells of mouse small intestine
Authors: Kayahara Takahisa , Sawada Mitsutaka , Takaishi Shigeo , Fukui Hirokazu , Seno Hiroshi , Fukuzawa Hiroaki , Suzuki Katsumasa , Hiai Hiroshi , Kageyama Ryoichiro , Okano Hideyuki , Chiba Tsutomu
Published: January 2003

Musashi‐1, a neural RNA‐binding protein, is important for maintaining neural stem cells. Both Musashi‐1 and Hes1, a transcriptional factor regulated by Musashi‐1, are expressed in the small intestine. Here we show that Musashi‐1 is present in a few epithelial cells just above the Paneth cells in the small intestinal crypt, the putative position of stem cells, whereas Hes1 is expressed in lower crypt cells just above the Paneth cells, including Musashi‐1‐positive cells. Musashi‐1 and Hes1 were not expressed in Paneth cells. Notably, Musashi‐1 and Hes1 were coexpressed in the crypt base columnar cells located between the Paneth cells. These findings suggest that not only the cells just above Paneth cells but also the crypt base columnar cells between the Paneth cells have stem cell characteristics.
Adolescent resilience: a concept analysis
Authors: Olsson Craig A , Bond Lyndal , Burns Jane M , Vella‐Brodrick Dianne A , Sawyer Susan M
Published: January 2003

There is need for greater clarity around the concept of resilience as it relates to the period of adolescence. Literature on resilience published between 1990 and 2000 and relevant to adolescents aged between 12‐ and 18‐years of age was reviewed with the aim of examining the various uses of the term, and commenting on how specific ways of conceptualizing of resilience may help develop new research agendas in the field. By bringing together ideas on resilience from a variety of research and clinical perspectives, the purpose of the review is to explicate core elements of resilience in more precise ways, in the hope that greater conceptual clarity will lead to a range of tailored interventions that benefit young people.
Prognostic value of serial cardiac assessment and familial screening in patients with dilated cardiomyopathy
Authors: Grünig Ekkehard , Benz Andreas , Mereles Derliz , Unnebrink Kristina , Kücherer Helmut , Haass Markus , Kübler Wolfgang , Katus Hugo A.
Published: January 2003

Objectives:

This prospective study was performed to analyse whether routine clinical follow‐up investigations at 12±6 months add to risk stratification and improve survival rates in patients with a first diagnosis of dilated cardiomyopathy (DCM).

Methods:

Four hundred and eighty consecutive patients (mean age 53.4±12.3 years, 369 males, mean NYHA class 2.4±0.8) with invasively confirmed DCM were included and followed for 3.9±3.5 years. Patients were requested to adhere to a follow up investigation within 6–18 months either at the referring physicians or at our out patient department. Two hundred and eighty‐one of the 480 patients presented for follow up which consisted of a detailed evaluation of symptoms, standardized physical examination, 12‐lead‐electrocardiogram recording and echocardiography. Seventeen patients were lost for follow up, 182 did not seek specialized medical follow up. Patients outcome was assessed by structured telephone interviews.

Results:

Independent predictors of death or transplantation at initial diagnosis were LV–ejection fraction <30% (P=0.0001, risk ratio 2.25), LV–end diastolic pressure ≥15 mmHg (P=0.002, risk ratio 2.0), age ≥54 years, (P=0.04, risk ratio 1.55), and presence of left bundle branch block (P=0.046, risk ratio 1.53). On follow up investigations only deterioration of clinical status by at least one NYHA‐class (P=0.001, risk ratio 2.6) and new onset or worsening of mitral regurgitation (P=0.02, risk ratio 1.8), remained independent prognostic factors for cardiac death. Patients who presented for routine follow up revealed significant better 5‐year survival rates (n=281, 70%) than those who did not (n=153, 55%, P=0.005).

Conclusions:

Routine clinical follow up investigations within 6–18 months after first diagnosis of DCM adds to risk stratification and improves survival rates.
Neurohormonal effects of furosemide withdrawal in elderly heart failure patients with normal systolic function
Authors: van Kraaij Dave J.W. , Jansen René W.M.M. , Sweep Fred C.G.J. , Hoefnagels Willibrord H.L.
Published: January 2003

Background:

In heart failure patients, diuretics cause renin–angiotensin–aldosterone system (RAS) activation, which may lead to increased morbidity and mortality despite short‐term symptomatic improvement.

Aim:

To determine changes in RAS activation and clinical correlates following furosemide withdrawal in elderly heart failure patients without left ventricular systolic dysfunction.

Methods and results:

We performed clinical assessments and laboratory determinations of aldosterone, plasma renin activity (PRA), atrial natriuretic peptide (ANP), norepinephrine, and endothelin in 29 heart failure patients [aged 75.1±0.7 (mean±S.E.M.) years], before, 1 and 3 months after placebo‐controlled furosemide withdrawal. Recurrent congestion occurred in 2 of 19 patients withdrawn, and in 1 of 10 patients continuing on furosemide. Three months after withdrawal, PRA had decreased −1.61±0.71 nmol/l/h (P<0.05). Decreases in aldosterone levels did not reach significance (−0.17±0.38 nmol/l). The decreases in PRA after withdrawal correlated with decreases in systolic (rs=0.61, P=0.020) and diastolic blood pressure (rs=0.80, P=0.01). Successful withdrawal was associated with increases in norepinephrine (+0.58±0.22 nmol/l) and ANP (+3.5±1.3 pmol/l) (P<0.05) after 1 month, but these changes did not persist after 3 months. Endothelin levels did not change in both groups.

Conclusion:

Successful furosemide withdrawal in elderly heart failure patients causes persistent decreases in RAS activation.
Scalar and spin-12 particle creation in gravitational and constant electric field backgrounds
Authors: Mendy J. E. B.
Published: January 2003

By considering the quantum vacuum states in the asymptotic regions of the gravitational background, the production rates of scalar and spin-12 particles created by gravitational fields in specific geometries are computed, with energy distributions shown to be of the Bose–Einstein and Fermi–Dirac types. The analysis is extended in the case of scalar particles to include a constant electric field.
Photoacoustic infrared spectroscopy of industrial materials (invited)
Authors: Michaelian Kirk H.
Published: January 2003

The infrared analysis of many industrial samples presents a series of significant difficulties to the experimentalist. Photoacoustic (PA) infrared spectroscopy provides a means for dealing with these problems, primarily because the technique requires minimal sample preparation and is capable of the analysis of opaque materials. Five examples of the use of PA spectroscopy for the characterization of industrial materials are described, with particular emphasis on hydrocarbon production in western Canada.
Laser-based surface acoustic wave spectrometer for industrial applications
Authors: Maznev A. A. , Mazurenko Alex , Zhuoyun Li , Gostein Michael
Published: January 2003

A compact, robust, and fully automated optical system for laser generation and heterodyne detection of surface acoustic waves (SAWs) in the frequency range 0.1–1.3 GHz is presented. SAWs are generated by two short laser pulses forming an interference pattern at the sample surface, and detected via diffraction of a quasi-cw probe beam off the surface ripples produced by the SAWs. The detection is enhanced by optical heterodyning achieved through the introduction of a fourth (reference) beam. Both excitation and probe/reference beam pairs are produced by a phase grating optimized to provide maximum efficiency for the desirable diffraction orders at the two different optical wavelengths used for excitation and probing. The heterodyne arrangement has an excellent phase stability and provides a number of advantages compared to a conventional transient grating setup. These include enhanced signal level and suppression of “parasitic heterodyning” due to scattered light. The system provides reproducibility of SAW frequency measurements of ∼0.01% with measurement time of ∼1 s. Measurements can be performed on small test structures such as 50×50 μm boxes, with an integrated vision system helping position the measurement spot on the sample.
Periodic line heat source at the interface
Authors: Shendeleva M. L. , Molloy J. A. , Ljepojevic N. N.
Published: January 2003

Thermal waves generated by a time-periodic line heat source located at the boundary between two different heat conducting media are studied theoretically. An analytical solution has been obtained by the application of the Fourier transform with respect to the spatial variable parallel to the interface with a consequent modification of the integration contour into the Cagniard–de Hoop hyperbola. Here, some physical implementations of the obtained solution are studied. First, wave diagrams are introduced that represent the decomposition of temperature fields into the spherical waves and head waves. Second, high-frequency approximations have been derived, which resemble Fresnel’s formulas in geometrical optics. Third, for a certain choice of thermal parameters a two-peak shape of the amplitude of the reflected thermal wave versus coordinate parallel to the interface has been found. The results have been confirmed by finite difference modeling.
Trace gas monitoring by laser photoacoustic spectroscopy and related techniques (plenary)
Authors: Sigrist Markus W.
Published: January 2003

Trace gas sensing systems have to meet several requirements like high detection sensitivity and selectivity, multicomponent capability, field suitability, etc. In this respect devices based on tunable lasers combined with appropriate detection schemes are attracting great interest. This report reviews recent developments demonstrating the potential of such systems. The performance of various spectroscopic systems with different lasers (gas lasers, nonlinear optical sources like optical parametric oscillators and difference frequency generation, near-infrared external cavity diode lasers, quantum cascade lasers) and different detection schemes (photoacoustic, multipass transmission, cavity ringdown) is discussed and illustrated with examples from various areas. Applications include laboratory analyses of multicomponent samples with isotopic selectivity, field measurements in ambient urban and rural air or even at volcanic sites, as well as investigations in the area of biology and medical diagnostics.
Photothermal configuration applied to the study of water vapor permeability in biodegradable films under several water activities
Authors: Lopez-Bueno G. , Martı́n-Martı́nez E. San , Cruz-Orea A. , Tomas S. A. , Tufiño M. , Sanchez F.
Published: January 2003

A photothermal configuration was used to determine the water vapor permeability of biodegradable films (nixtamalized corn pericarps). The films were obtained from corn grains boiled in an alkaline solution containing water and Ca(OH)2. Samples were exposed to saturated salt solutions with relative humidity in the range 7%–97%. The water vapor diffusion coefficient was determined as a function of relative humidity. The obtained coefficients agreed with data available in the literature. It was also found that the photoacoustic amplitude shows a linear dependence on the water activity, in agreement with our theoretical model.
Photoacoustic absorption spectra of biofilms
Authors: Schmid T. , Panne U. , Haisch C. , Niessner R.
Published: January 2003

Biofilms are aggregates of microorganisms which occur at the interfaces of natural and engineered aqueous systems. In this article, the use of photoacoustic spectroscopy (PAS) as a new technique for online and in situ monitoring of biofilms is demonstrated. Former studies revealed that PAS allows the monitoring of growth, detachment, and thickness of biofilms. Here, first photoacoustic absorption spectra of biofilms in the visible and near infrared range and corresponding depth-resolved measurements are presented.
Photoacoustic spectroscopy to evaluate the penetration of sunscreens into human skin in vivo: A statistic treatment
Authors: Sehn E. , Silva K. C. , Retuci V. S. , Medina A. N. , Bento A. C. , Baesso M. L. , Storck A. , Gesztesi J. L.
Published: January 2003

The penetration rates of three different sunscreens into the human skin in vivo have been investigated using photoacoustic spectroscopy. A statistic treatment of the data obtained in a group of 15 healthy volunteers with constitutively light white skin is made using a nonparametric test. The results showed the discrimination between the times of propagation of the used products, evidencing the sensitivity of this technique to evaluate the penetration of topically applied substances through human skin in vivo.
Atmospheric pollution profiles in Mexico City in two different seasons
Authors: Altuzar V. , Tomás S. A. , Zelaya-Angel O. , Sánchez-Sinencio F. , Arriaga J. L.
Published: January 2003

A CO2-laser-based photoacoustic spectrometer was used to determine the temporal concentration profile of atmospheric ethene in Mexico City. Ethene measurements were conducted at the facilities of our institute, which is located in the north of the city and next to an avenue with heavy traffic density. Ambient air from outside our laboratory was continuously pumped into the spectrometer. This campaign was performed for 24 h a day, from November 24–30, 2001. The maximum ethene levels ranged between 26 and 81 ppbV. As expected, the lowest concentrations were monitored on weekends. These data were analyzed in combination with ozone and nitrogen oxides profiles, which were permanently monitored by an air-pollution-monitoring government network. Information on the seasonal variability of ethene was obtained by comparing the results of this campaign with data obtained in the winter of 2001. In general, the ethene concentration in November was about 30% higher than in February. On weekdays, the mean dose of human exposure to ethene was 13.7 and 15.2 ppbV per hour in February and November, respectively. On weekends, corresponding values were 7.8 and 14.7 ppbV.
Photoacoustic study of airborne and model aerosols
Authors: Alebić-Juretić A. , Zetzsch C. , Dóka O. , Bicanic D.
Published: January 2003

Airborne particulates of either natural or anthropogenic origin constitute a significant portion of atmospheric pollution. Environmental xenobiotics, among which are polynuclear aromatic hydrocarbons (PAHs) and pesticides, often adsorb to aerosols and as such are transported through the atmosphere with the physicochemical properties of the aerosols determining the lifetime of these organic compounds. As an example, the resistance of some PAHs against the photolysis is explained by the effect of the aerosol’s “inner filter” that reduces the intensity of incident light reaching the mineral particles. On the other hand, some constituents of the aerosols can act as catalytic and/or stoichiometric reagents in atmospheric reactions on the solid surfaces. In the study described here the photoacoustic (PA) spectroscopy in the UV-Vis was used to investigate natural and model aerosols. The PA spectra obtained from coal and wood ashes and of Saharan sand, all three representatives of airborne aerosols, provide the evidence for the existence of the “inner filter.” Furthermore, valuable information about the different nature of the interaction between the model aerosols and adsorbed organics (e.g., PAH-pyranthrene and silica, alumina, and MgO) has been obtained. Finally, the outcome of the study conducted with powdered mixtures of chalk and black carbon suggests that the PA method is a candidate method for determination of carbon content in stack ashes.
Photothermal characterization of grind-hardened steel
Authors: Prekel H. , Ament Ch. , Goch G.
Published: January 2003

Grind hardening is a promising production process which combines grinding and hardening within one step. Due to the fact that many material and process parameters partially influence the properties of the workpieces in a nonlinear way, it is difficult to predict for instance the surface hardness and hardness penetration depth. In this study, photothermal radiometry is used as an approach to determine the hardness penetration depth. Photothermal phase signals have been measured as a function of frequency. First measurements showed a strong influence of surface roughness, causing phase signal maxima at unexpected high frequencies (f>60 Hz). After finishing of the surfaces, the maxima of phase signals shifted toward lower frequencies (f<10 Hz). In an attempt to extract a preliminary calibration curve, the measured phase values of each sample were added and correlated to the hardness penetration depth. The resulting curve reveals a good correlation between phase sum and the hardness penetration depth. Further research is necessary to collect more experimental data and to support the current results by theoretical models.
Photoacoustic waves at reflecting interfaces
Authors: Diebold Gerald J.
Published: January 2003

The properties of photoacoustic waves generated outside acoustically reflecting boundaries can be found using Green’s function solutions to the wave equation for pressure. Here, Green’s functions are used to calculate the time profiles of photoacoustic waves generated in the fluid surrounding an incompressible sphere with a vanishing thermal expansivity. The Green’s function method is also applied to determination of the properties of the photoacoustic wave generated in the atmosphere of a planet caused by rotation of the planet in the radiation emitted by the sun.