bluuebunny/crossref_metadata_2025_split huggingface dataset:
Accurate model of InxGa1−xAsyP1−y/InP active waveguides for optimal design of switches
Authors: Petruzzelli V. 
Published: March 2003

AbstractBoth the longitudinal and transverse charge diffusion terms in the rate equations as well as the spreading effect of the injected charge in the active layer are taken into account for a complete model of active twin ridge InGaAsP/InP‐waveguides. A dedicated computer code, relying on an optimized beam propagation method (BPM) based on the method of lines (MoL–BPM), is written. The computer code is used for the optimal design of a travelling‐wave switch and to simulate the bidirectional propagation for the design of a Fabry–Perot switch. This last switch version is more compact with respect to the travelling wave (TW) version because a reduction of the switch length of about 20% is gained. Copyright © 2003 John Wiley & Sons, Ltd.
A uniformly stable conformal FDTD‐method in Cartesian grids
Authors: Zagorodnov I.A. , Schuhmann R. , Weiland T. 
Published: March 2003

AbstractA conformal finite‐difference time‐domain algorithm for the solution of electrodynamic problems in general perfectly conducting 3D geometries is presented. Unlike previous conformal approaches it has the second‐order convergence without the need to reduce the maximal stable time step of conventional staircase approach. A novel proof for the local error rate for general geometries is given, and the method is verified and compared to other approaches by means of several numerical 2D examples. Copyright © 2003 John Wiley & Sons, Ltd.
Quasi‐analytic steady‐state solution of VCSEL rate equations including spatial hole burning and carrier diffusion losses
Authors: Jungo Marc , Erni Daniel , Baechtold Werner 
Published: March 2003

AbstractWe propose a new set of equations describing a cylindrical vertical cavity surface emitting laser (VCSEL) cavity under CW operation, based on the rate equations including lateral carrier diffusion. The only numerical step in the calculation consists in finding the roots of a polynomial expression. This model enables a quasi‐instantaneous calculation of the laser's light‐current characteristic, including such effects as spatial hole burning, current spreading, inhomogeneous optical intensity distribution, and diffusion losses. An analysis of the VCSELs threshold current and differential quantum efficiency is proposed, which illustrates the interplay between injected current profile and diffusion coefficient. Copyright © 2003 John Wiley & Sons, Ltd.
A simple Nyström approach for the analysis of 3D arbitrarily shaped conducting and dielectric bodies
Authors: Burghignoli P. , Di Nallo C. , Frezza F. , Galli A. 
Published: March 2003

AbstractIn this work, an original boundary‐integral‐equation (BIE) approach is developed for an efficient and accurate electromagnetic analysis of arbitrarily shaped three‐dimensional (3D) conducting and dielectric structures. A suitable analytical pre‐processing on the field integral representation leads to a reduction of the singularity degree of the kernels and allows a straightforward implementation of the Nyström method, based on a direct discretization of the surface integrals by means of two‐dimensional (2D) quadrature formulas. This approach presents attractive computational advantages, mainly related to the very simple determination of the matrix elements in the resulting linear system. Various numerical results have been derived for canonical 3D shapes to validate the proposed implementation, confirming the excellent features of versatility and accuracy of this numerical tool. Copyright © 2003 John Wiley & Sons, Ltd.
Estrogen receptor‐α is required for estrogen‐induced μ‐opioid receptor internalization
Authors: Micevych Paul E , Rissman Emilie F. , Gustafsson Jan‐Åke , Sinchak Kevin 
Published: March 2003

AbstractEndogenous opioid circuits are pivotal for the regulation of sexual receptivity. Treatment of mice with morphine, a preferential μ‐opioid receptor (MOR) agonist, severely attenuates lordosis. Estrogen induces internalization of MOR in cell groups of the limbic‐hypothalamic lordosis‐regulating circuit. Because rapid MOR internalization is mediated by estrogen release of endogenous opioid peptides, internalization has been used as a neurochemical signature of estrogen action in the central nervous system. Together these results indicate that estrogen induces a MOR mediated inhibition of sexual receptivity. To determine which estrogen receptor, estrogen receptor‐α (ERα) or estrogen receptor‐β (ERβ), mediates MOR internalization, ERα knockout (ERαKO), ERβ knockout (ERβKO) and wild‐type (WT) mice were used in the present study. WT, ERαKO and ERβKO mice had similar MOR distributions in the limbic‐hypothalamic lordosis‐regulating circuit. Estrogen treatment internalized MOR in the medial preoptic nucleus of ovariectomized WT and ERβKO, but not ERαKO mice. Treatment of ERαKO mice with the selective endogenous MOR ligand, endomorphin‐1, induced levels of MOR internalization similar to WT mice suggesting that MOR in ERαKO mice could be activated and were probably functional. The results of the present experiments indicate that ERα is required for estrogen‐induced MOR internalization and suggest that ERα can mediate rapid actions of estrogen. © 2002 Wiley‐Liss, Inc.
Monoaminergic control of vasopressin and VIP expression in the mouse suprachiasmatic nucleus
Authors: Vacher C. M. , Frétier P. , Créminon C. , Seif I. , De Maeyer E. , Calas A. , Hardin‐Pouzet H. 
Published: March 2003

AbstractWe studied the effects of serotonin and noradrenaline on the expression of arginine‐vasopressin (AVP) and vasoactive intestinal peptide (VIP) in the suprachiasmatic nucleus (SCN). We used transgenic Tg8 mice knockout for the MAO‐A (monoamine oxidase A) gene, which are characterized by increased amounts of serotonin and noradrenaline in brain compared to wild‐type mice (C3H). The MAO‐A deficiency caused an increase in AVP and VIP expression (determined by immunohistochemistry, enzyme immunoassay, and in situ hybridization) compared to C3H mice. The number of peptidergic neurons was also increased. Inhibiting serotonin or noradrenaline synthesis in Tg8 mice by the administration of parachlorophenylalanine or α‐methylparatyrosine, respectively, the amounts of AVP, VIP and their mRNAs were decreased, but not the number of peptidergic neurons. This study indicates that serotonin and noradrenaline stimulate AVP and VIP expression, and could participate in the differentiation of the neurochemical phenotype in the mouse SCN. © 2002 Wiley‐Liss, Inc.
Tumor suppressor gene BRCA‐1 is expressed by embryonic and adult neural stem cells and involved in cell proliferation
Authors: Korhonen L. , Brännvall K. , Skoglösa Y. , Lindholm D. 
Published: March 2003

AbstractBRCA‐1 is a tumor suppressor gene that plays a role in DNA repair and cellular growth control. Here we show that BRCA‐1 mRNA is expressed by embryonic rat brain and is localized to the neuroepithelium containing neuronal precursor cells. The expression of BRCA‐1 decreases during rat brain development, but BRCA‐1 is expressed postnatally by proliferating neuronal precursor cells in the developing cerebellum. Neural stem cells (NSC) prepared from embryonic rat brain and cultured in the presence of epidermal growth factor were positive for BRCA‐1. Induction of NSC differentiation resulted in down‐regulation of BRCA‐1 expression as shown by RNA and protein analyses. In addition to embryonic cells, BRCA‐1 is also present in NSC prepared from adult rat brain. In adult rats, BRCA1 was expressed by cells in the walls of brain ventricles and in choroid plexus. The results show that BRCA‐1 is present in embryonic and adult rat NSC and that the expression is linked to NSC proliferation. © 2003 Wiley‐Liss, Inc.
Pressure‐ and temperature‐dependent Raman studies of KNbW2O9 hexagonal tungsten bronze
Authors: Mączka M. , Souza Filho A. G. , Freire P. T. C. , Mendes Filho J. , Kojima S. , Hanuza J. , Majchrowski A. 
Published: March 2003

AbstractPressure‐ and temperature‐dependent Raman studies were performed on KNbW2O9 ferroelectric hexagonal tungsten bronze single crystal. The results suggest that some structural changes, possibly phase transitions, connected with tilting of the WO6 octahedra occur in this material at around 290–350 K and 1.0–1.4 GPa. No changes in the spectra could be observed at the 523 and 543–553 K phase transitions. The data indicate that these phase transitions lead to only weak changes in the vibrational properties of KNbW2O9, which were not observed owing to the large bandwidth of the Raman bands. The Raman studies suggest, therefore, that the structure of the unknown phase, existing below 553 K, differs slightly form the orthorhombic structure present above 553 K. The pressure‐dependent study revealed that the 52 cm−1 band, assigned to external vibrations of the WO6 octahedron, consists at ambient temperature and pressure of two overlapping bands. These bands become well separated at high pressure. Copyright © 2003 John Wiley & Sons, Ltd.
Raman identification of materials used for jewellery and mosaics in Ifriqiya
Authors: Colomban Philippe , March Grégory , Mazerolles Léo , Karmous Tijani , Ayed Naceur , Ennabli Abdelmajid , Slim Hédi 
Published: March 2003

AbstractBeads, rings and mosaic tessarae from Tunisia (Carthage and Utica, 1st centuries BC and AD, El Djem, 2nd–3rd centuries and Mahdia, 10th century) were analysed by Raman spectroscopy for non‐destructive differentiation of various types of glasses (most have Si‐ and Na/Ca‐rich compositions, some others are lead‐containing glass) and identification of synthetic or natural minerals (crystal or stone). The results are discussed in the light of chemical analyses. A green glass is coloured by a Cr‐based nanosized pigment and a red mosaic tesserae is obtained by a colloidal dispersion of gold (Cassius purple). Cassiterite (SnO2) is used as an opacifier or fluxing agent. The examination of glass mosaic and jewellery microstructure shows that some pieces are made of sintered glass, i.e. using a paste technology. Copyright © 2003 John Wiley & Sons, Ltd.
The role of quantitative and qualitative research in industrial studies of tourism
Authors: Davies Brian 
Published: March 2003

AbstractMany areas of research in tourism concentrate on quantitative or qualitative studies. Some even discuss the complementarity between the two types of studies. Hardly considered are the possibilities for combining such works within an integrated framework that also considers the business environment in which tourism operates. The purpose of this paper is to return to long neglected possibilities by reinvestigating areas of methodology and epistemology concerned with the generation of a framework that embraces both quantitative and qualitative research. A hypothetical example, in terms of industrial organisation and strategic decision making, is introduced discussing the possibilities for the triangulation of methods and paradigms and the role of the business environment. The conclusion is that an improved understanding of the tourism business requires a broader research methodology than presently exists. Both types of research and the dynamic context of tourism are important and need to be combined within an integrated framework. It has been concerned with the construction of integrating frameworks that embrace an alternative logic of inference and the context of the tourism business environment. This requires refinements of existing approaches together with a broader research methodology. Only by establishing such frameworks will an improved understanding of the tourism industry be achieved. The suggested framework presented here, with particular reference to industrial organisation and strategic decision making by tourism suppliers, is not offered as a panacea. For future work, the validity and choice of framework rest squarely on how the world and ‘truth’ are viewed. However, within this, the contribution of triangulated quantitative and qualitative research should help understanding by studying phenomena in their natural setting and in terms of the meanings people have of them. This should lead to a ‘truer analysis’ of business behaviour and hence a more purposeful investigation of hotels, tour operators, travel agents and the business of tourism in general. It is in seeking to produce this ‘truer analysis’ that future research activities need to concentrate. Copyright © 2003 John Wiley & Sons, Ltd.
Kinetics and mechanism of the gas‐phase OH hydrogen abstraction reaction from methionine: A quantum mechanical approach
Authors: Galano Annia , Alvarez‐Idaboy J. Raúl , Cruz‐Torres Armando , Ruiz‐Santoyo Ma. Esther 
Published: March 2003

AbstractUnrestricted density functional theory (BHandHLYP) calculations have been performed, using the 6‐311G(d,p) basis sets, to study the gas‐phase OH hydrogen abstraction reaction from methionine. The structures of the different stationary points are discussed. Ring‐like structures are found for all the transition states. Reaction profiles are modeled including the formation of prereactive complexes, and negative net activation energy is obtained for the gamma H‐abstraction channel. A complex mechanism is proposed, and the rate coefficients are calculated using transition state theory over the temperature range 250–350 K. The rate coefficients are proposed for the first time and it was found that in gas phase the hydrogen abstraction occurs almost exclusively from the gamma site. The large overall rate coefficient for the methionine + OH reaction compared to other free amino acids could explain the significant role of methionine in the oxidative processes. The following expressions in [L/(mol s)] are obtained for the alpha, beta, and gamma H‐abstraction channels, and for the overall temperature‐dependent rate constants, respectively: kα = (3.42 ± 0.11) × 108 exp[(−1118 ± 9)/T], kβ = (1.13 ± 0.03) × 108 exp[(−1070 ± 8)/T], kγ = (2.11 ± 0.26) × 107 exp[(2049 ± 34)/T], and ktot = (2.12 ± 0.26) × 107 exp[(2047 ± 34)/T]. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 212–221, 2003
Kinetics of the reaction of OH radicals with acetylene in 25–8000 torr of air at 296 K
Authors: Sørensen M. , Kaiser E. W. , Hurley M. D. , Wallington T. J. , Nielsen O. J. 
Published: March 2003

AbstractRelative rate techniques were used to study the kinetics of the reaction of OH radicals with acetylene at 296 K in 25–8000 Torr of air, N2/O2, or O2 diluent. Results obtained at total pressures of 25–750 Torr were in good agreement with the literature data. At pressures >3000 Torr, our results were substantially (∼35%) lower than that reported previously. The kinetic data obtained over the pressure range 25–8000 Torr are well described (within 15%) by the Troe expression using ko = (2.92 ± 0.55) × 10−30 cm6 molecule−2 s−1, k∞ = (9.69 ± 0.30) × 10−13 cm3 molecule−1 s−1, and Fc = 0.60. At 760 Torr total pressure, this expression gives k = 8.49 × 10−13 cm molecule−1 s−1. © 2003 Wiley Periodicals, Inc. Int J Chem Kinet 35: 191–197, 2003
Factors affecting the antibacterial effects of Nd:YAG laser in vivo
Authors: Meral Gökçe , Tasar Ferda , Kocagöz Sesin , Sener Cem 
Published: March 2003

AbstractBackground and ObjectivesOne of the main advantages of laser surgery is it's bactericidal effect which reduces the risk of postoperative infections. Several study designs have been set to investigate this effect. Aim of this study was to research if the bactericidal effect of laser tool was affected from several factors in vitro studies.Study Design/Materials and MethodsTo determinate and investigate the bactericidal effect of laser in an original model, α‐hemolytic streptococcus, Bacterioides fragilis, Neisseria, Streptococcus salivarius, Staphylococcus aureus, and Candida albicans were prepared in 104, 106 and 108 inoculum and placed in Mueller‐Hinton Broth which have five different proportions of sheep blood. Samples which exposed with various energy levels of Nd:YAG laser were spread on agar plates, and at the end of an incubation time the colonization counted comparatively. The lowest energy level without colonization was accepted as minimal bactericidal energy level.ResultsHighest minimum bactericidal energy level is used for α‐hemolytic streptococcus and lowest values for neisseria. Bactericidal effect decreased on suspensions, of which population of microorganisms are high and hemoglobin concentration was high in the broth.ConclusionsThese findings suggest that the Nd:YAG laser has a higher bactericidal effect when sheep blood is added to the media. Factors like population and type of bacteria in the irradiated suspension affect minimum bactericidal energy level. Lasers Surg. Med. 32:197–202, 2003. © 2003 Wiley‐Liss, Inc.
Efficacy of NaOCl/H2O2 irrigation and GaAlAs laser in decontamination of root canals in vitro
Authors: Kreisler M. , Kohnen W. , Beck M. , Al Haj H. , Christoffers A.B. , Götz H. , Duschner H. , Jansen B. , d'Hoedt B. 
Published: March 2003

AbstractBackground and ObjectivesTo investigate the bactericidal effect of an 809 nm semiconductor laser alone, and in combination with NaOCl/H2O2 irrigation in root canals in vitro.Study Design/Materials and MethodsA total of 72 human single‐rooted teeth extracted for periodontal reasons were included. The crowns were removed, the roots shortened to a length of 12 mm, and the canals enlarged up to an apical size of #50 file. The specimens were autoclaved and incubated with a suspension of Streptococcus sanguinis (ATCC 10556). Laser irradiation was performed on a PC‐controlled XY translation stage. A 200 micron optic fiber was used. Twelve specimens were irradiated at a power output of 1.5, 3.0, and 4.5 W in the cw‐mode. The total irradiation time was 60 seconds per canal. Twelve specimens were rinsed with NaOCl and H2O2 only, 12 were rinsed and laser treated, and 12 served as untreated controls. After laser treatment, the specimens were sonicated and the bacterial growth was examined by counting colony forming units on blood agar plates. Temperature changes at the outer root surface during irradiation were registered by means of thermocouples. Treated and control specimens were investigated by means of scanning electron microscopy.ResultsMean bacterial reductions of 0.35 log steps at a power output of 1.5 W, 1.44 at 3.0 W, and 2.84 at 4.5 W were calculated. Bacterial reduction by the NaOCl/H2O2 solution alone was 1.48 and comparable to that achieved by irradiation at 3.0 W. With a log kill 2.85, the combination of rinsing and laser irradiation at 3.0 W resulted in a further significant bacterial reduction as compared to rinsing alone (P = 0.004). Irradiation did not result in excessive heat generation at the root surface. Carbonization of the root canal wall was observed in single teeth at 3.0 and 4.5 W and no controlled sealing of the dentinal tubules could be achieved in the root canal.ConclusionsThe application of the diode laser might be an adjunct to conventional endodontic treatment when used in combination with a NaOCl/H2O2 solution. Lasers Surg. Med. 32:189–196, 2003. © 2003 Wiley‐Liss, Inc.
Independence results for weak systems of intuitionistic arithmetic
Authors: Moniri Morteza 
Published: March 2003

AbstractThis paper proves some independence results for weak fragments of Heyting arithmetic by using Kripke models. We present a necessary condition for linear Kripke models of arithmetical theories which are closed under the negative translation and use it to show that the union of the worlds in any linear Kripke model of HA satisfies PA. We construct a two‐node PA‐normal Kripke structure which does not force iΣ2. We prove i∀1⊬ i∃1, i∃1⊬ i∀1, iΠ2⊬ iΣ2and iΣ2⊬ iΠ2. We use Smorynski's operation Σ′ to show HA ⊬ lΠ1.
Sensing Behavior of Fluorescent Cyclodextrin/Peptide Hybrids Bearing a Macrocyclic Metal Complex
Authors: Furukawa Shuntaro , Mihara Hisakazu , Ueno Akihiko 
Published: March 2003

AbstractTwo kinds of cyclodextrin/peptide (CD/peptide) hybrids bearing ZnII‐cyclen or cyclen, dansyl and β‐cyclodextrin (β‐CD) units have been synthesized as chemosensors for organic anionic molecules. ZnII‐cyclen serves as a ligand site and β‐CD is a receptor site for guest molecules, while the dansyl unit acts as a fluorescent probe. Examination of the fluorescence behaviors of these CD/peptides suggest that the hybrid containing Zn2+ has larger binding constants with respect to anionic molecules than that without Zn2+.
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Insulin‐like growth factor binding protein‐1 over‐expression in transgenic mice inhibits hepatic preneoplasia
Authors: Lu Suying , Archer Michael C. 
Published: March 2003

AbstractInsulin‐like growth factor binding protein‐1 (IGFBP‐1) is synthesized in the liver and regulates the mitogenic effects of the insulin‐like growth factors (IGFs). The evidence that IGFBP‐1 plays a role in hepatocarcinogenesis, however, is equivocal. We have, therefore, investigated the development of preneoplastic hepatic lesions in transgenic mice in which the human IGFBP‐1 gene is under the control of the mouse metallothionein promoter. The lesions were induced by treating 15‐d‐old male mice with a single intraperitoneal injection of 5 mg/kg diethylnitrosamine (DENA). Lesions were scored when the mice were 28 wk of age. Quantitative microscopy of liver sections revealed that significantly fewer transgenic mice treated with zinc to activate the transgene had focal lesions compared to either transgenic mice not treated with zinc or wild‐type mice treated with zinc (36.4% versus 85.7% and 83.3%, respectively, P < 0.05 in each case). Zinc‐treated transgenic mice also had significantly fewer lesions per liver (11.5 ± 5.0 versus 74.7 ± 18.4 and 59.4 ± 15.6, respectively, P < 0.01 in each case) and a smaller percentage of liver volume occupied by lesions (0.2 ± 0.1 versus 1.4 ± 0.3 and 1.1 ± 0.4 respectively, P < 0.05 in each case). Immunohistochemical staining showed that both IGF‐I and IGF‐II were overexpressed in most of the lesions. These results show that expression of the IGFBP‐1 transgene leads to a marked inhibition of hepatic preneoplasia, possibly by decreasing the mitogenic activity of IGF‐I and/or IGF‐II. This study adds new evidence to the notion that the IGF axis plays an important role in liver cancer development. © 2003 Wiley‐Liss, Inc.