bluuebunny/crossref_metadata_2025 huggingface dataset:
Phase‐relaxation processes of excitons in semiconducting single‐walled carbon nanotubes
Authors: Ichida Masao , Kiyohara Yumie , Saito Shingo , Miyata Yasumitsu , Kataura Hiromichi , Ando Hiroaki
Published: October 2008

We have investigated the phase‐relaxation process of excitons in semiconducting single‐walled carbon nanotubes (SWNTs) by a time‐resolved degenerate four‐wave mixing (DFWM) method. The phase‐relaxation time (T2) estimated from the time evolution of the diffracted DFWM signals strongly depends on the temperature and excitation intensity, shorter T2 with higher temperature and excitation intensity. The experimental trend can be explained by the enhancement of phase‐relaxation rate due to frequent exciton–phonon scattering at high temperature and exciton–exciton scattering under high‐density excitation conditions. The T2 value at the weak excitation limit measured for semiconducting SWNT with a tube diameter of 1.1 nm at 2 K is estimated to be 350 fs. This T2 value is in good agreement with the homogeneous width estimated from microluminescence measurements. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Exciton energy transfer in mixed J‐aggregates
Authors: Lemaistre J. P.
Published: October 2008

A computational method to analyze the exciton energy transfer and trapping mechanisms in mixed J‐aggregates featuring a donor–acceptor system is provided. For a given geometrical configuration, the intermolecular interactions are calculated using the extended dipole method. Numerical diagonalization of the aggregate Hamiltonian is performed taking into account the static disorder. The density of states, the absorption lineshapes and the relative number of coherently coupled molecules within the donor and acceptor bands are obtained. The excitation energy transfer processes among the excited states of the donor–acceptor system (intraband and interband scatterings) are described through an exciton‐phonon coupling model. The scattering rates are calculated and used in a Master Equation to obtain the time evolution of the exciton populations after initial excitation. Our simulation method is used to analyze the excitation energy transfer between two kinds of closely spaced linear parallel chains featuring the so‐called blue (donor) and red (acceptor) structures of pseudoisocyanine molecules (PIC). It is also applied to describe the energy transfer in the mixed J‐aggregate of oxacyanine (donor) and thiacyanine (acceptor) molecules. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Low‐temperature excitons produced by two‐photon excitation in high‐purity diamond crystals
Authors: Naka N. , Kitamura T. , Omachi J. , Kuwata‐Gonokami M.
Published: October 2008

We have observed edge emission due to free excitons and electron–hole droplets in diamond by two‐photon excitation using subpicosecond laser pulses at 257 nm. We find that excitonic temperatures under two‐photon excitation are much lower than the case of one‐photon excitation. A minimum excitonic temperature of 3.4 K is extracted by spectral analysis. In order to understand the difference of the excitonic temperatures under two‐photon and one‐photon excitations, we discuss a heating mechanism which depends on the density distribution of the electron–hole pairs in the crystal along the laser beam. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
s‐polarization Brewster's angle of stratified metal–dielectric metamaterial in optical regime
Authors: Watanabe Ryosuke , Iwanaga Masanobu , Ishihara Teruya
Published: October 2008

We demonstrate that the optical reflectivity for s‐polarized light vanishes at a certain angle in a stratified metal–dielectric metamaterial numerically and experimentally. The metamaterial consists of a unit cell where a Ag layer of 30 nm thickness is sandwiched by Al2O3 layers of 60 nm thickness. In order to understand the phenomenon in terms of effective permittivity and permeability, we extended a field‐sampling method. The permeability is found to be significantly different from unity, which is the origin of Brewster's angle for s‐polarization. The microscopic field distribution is readily coarse grained with the effective optical parameters. The present result is a manifestation of the magnetic response in the optical regime. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Analysis of transmission line meta‐materials at optical wavelength
Authors: Baba Takeshi , Ishihara Teruya
Published: October 2008

Following the transmission line formalism, we design a metamaterial structure that exhibts negative refraction in the red part of the visible spectrum.The structure is a waveguide consisting of an Al2O3 top layer, 2D array of Au dots, an Al2O3 spacer and a Ag ground plane. The Au dot array with period of 250 nm were patterned by an electron beam lithography technique. We confirm experimentally and numerically that threre is a mode shifting to the lower energy side as the wavevector increases. Both permittivity and permeability are found to be negative in that region. Focussing effect of a flat structure, which is a characteristic feature of a negative index metamaterial, is also confirmed with FDTD caculation. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Influence of co‐deposited active layers on carrier transport and luminescent properties in organic light emitting diodes
Authors: Murata Masaya , Yamamoto Takayuki , Haishi Motoki , Ando Taro , Ohtani Naoki
Published: October 2008

We have investigated the influence of a co‐deposited active layer in organic light‐emitting diodes (OLEDs) on carrier transport and optical properties to improve radiative characteristics of OLEDs. The co‐deposited layer consists of two organic materials; one is a hole transport material (TPD) and the other is an electron transport/emissive material (Alq3). We evaluated current‐voltage characteristics and electroluminescence (EL) properties of various samples in which the thicknesses and compound ratios of the co‐deposited layers are different. The results indicate that the devices consisting of TPD:Alq3 co‐deposited layer sandwiched between TPD and Alq3 layers exhibit lower starting voltages for the light emission than the sample of simple TPD/Alq3 heterojunction structure. In addition, the starting voltage is independent of the thickness of TPD:Alq3 co‐deposited layer. These samples have two interfaces at both surfaces of TPD:Alq3 co‐deposited layer. Thus, we estimated the radiative recombination occurs at the interfaces. Nevertheless, we found that the radiative recombination occurs only at the interface of TPD:Alq3 co‐deposited layer and Alq3 layer. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Propagation dynamics of exciton spins in a high‐density semiconductor quantum dot system
Authors: Murayama A. , Furuta T. , Oshino S. , Hyomi K. , Sakuma M. , Souma I. , Dagnelund D. , Buyanova I. A. , Chen W. M.
Published: October 2008

We study propagation dynamics of exciton spins in a system composed of high‐density self‐assembled quantum dots (QDs) of CdSe and a diluted magnetic semiconductor (DMS) layer of ZnMnSe, where spin‐polarized excitons are generated in the DMS layer and are subsequently injected into the QDs. The degree of circular polarization, P, of excitonic photoluminescence at 5 T in the coupled QDs shows a rapid increase with increasing delay time after a linearly polarized pulsed excitation, indicating the exciton‐spin injection from the ZnMnSe to CdSe‐QDs. The P value tends to decay gradually because of the exciton‐spin relaxation in the QDs after the injection. The spin‐polarized excitons in the QD ensemble migrate simultaneously from the QDs with higher exciton energies to those with lower exciton energies, where the exciton‐spins relax inside each dot during the migration. Therefore, the observed P values in the QD emission band are affected by this feeding of the relaxed spins. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Unusual features of the quaterthiophene electro‐absorption spectrum
Authors: Petelenz Piotr , Slawik Michał , Kulig Waldemar
Published: October 2008

A previously used model describing the coupling between Frenkel and charge‐transfer (CT) excited states in a crystal with molecules arranged in close‐packed planes of herringbone pattern, is generalized to include some CT states engaging the molecules from the different planes. The corresponding Hamiltonian is parametrized for quaterthiophene and numerically diagonalized, to yield ultimately the electro‐absorption (EA) spectrum. Contrary to our recent expectations, the contribution from the newly introduced CT states is only minor. It turns out that the high‐energy EA signal of quaterthiophene is dominated by the contributions from the CT states with the electron transferred along the longer lattice period in the close‐packed plane, in contrast to the more familiar case of sexithiophene, where these states barely contribute. The reasons of this difference are pinpointed and discussed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Radiative emission from triplet excitations in light emitting devices
Authors: Singh Jai
Published: October 2008

Using the recently derived time‐dependent spin‐orbit‐photon interaction operator and first order perturbation theory the rate of spontaneous radiative emission from triplet excitations in molecular solids and polymers is calculated within the two‐level approximation. The rate depends on the square of the atomic number of the constituting atoms. The calculated rates and corresponding radiative lifetimes agree very well with the known experimental results in conjugated polymers incorporated with platinum atoms. Present results are compared with the known results obtained from the traditional theory for naphthalene and anthracene and found in better agreement with experiments. The traditional theory is briefly reviewed. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Beyond the strong vibronic coupling approximation – sexithiophene single crystal
Authors: Stradomska Anna , Petelenz Piotr
Published: October 2008

A new approach to vibronic coupling in molecular crystals is proposed. The underlying model describes an infinite 3‐dimensional crystal with two or four molecules in the unit cell. One Frenkel state and one vibrational mode per molecule is taken into account. The approach is rooted in the approximation of strong vibronic coupling, which is extended by taking into account the 2‐particle and 3‐particle contributions in order to cover the intermediate‐coupling region. The results of numerical calculations are presented for sexithiophene; they are discussed in the context of finite cluster models and their validity. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Polarized photoluminescence study of whispering gallery mode polaritons in ZnO microcavity
Authors: Sun Liaoxin , Chen Zhanghai , Ren Qijun , Yu Ke , Zhou Weihang , Bai Lihui , Zhu Z. Q. , Shen Xuechu
Published: October 2008

Polariton effect and its polarization dependence were studied in ZnO tapered whispering gallery (WG) microcavity at room temperature. By scanning the excitation along the tapered arm of ZnO tetrapod with different polarizations, the photo‐exciton coupling strength were continuingly tuned and thus the resonant interaction between the WG optical modes and the excitons with different dipole orientation are clearly resolved. The experimental observations were well described by the plane wave model with excitonic polariton dispersions. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Auger recombination process of biexciton in semiconducting carbon nanotubes
Authors: Watanabe Kouta , Asano Kenichi , Ogawa Tetsuo
Published: October 2008

We calculated the T‐matrix for the Auger recombination process of the biexciton in semiconducting carbon nanotubes (s‐CNTs) within the first Born approximation and clarified the difference between s‐CNTs and GaAs quantum wires (QWRs). The wavefunction and the binding energy of the biexciton, EXX, are given by the dynamics controlled truncation (DCT) scheme. We find that the Auger recombination rate is ħ/τ ∼ 0.1EXX. This means that the Auger recombination process doesn't prevent the biexciton formation. In addition, the Auger recombination rate is much larger than that of the QWR. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman scattering spectra of CdS nanocrystals fabricated by a reverse micelle method
Authors: Yamamoto Aishi , Endo Hiroki , Matsuura Norihiro , Ishizumi Atsushi , Kanemitsu Yoshihiko
Published: October 2008

Raman scattering (RS) spectra of CdS nanocrystals (NCs) fabricated by a reverse micelle method were studied and were analysed using a phonon confinement model. One broad and red‐shifted RS peak due to the LO phonon confined in CdS NCs was observed. The RS spectra were calculated using a phonon confinement model with the NC sizes estimated from the optical absorption spectra. The calculated RS spectra as suming that the NCs have the wurtzite structure reproduce the experimental spectra better than those assuming zincblende structure, which is consistent with the result of transmission electron microscope (TEM) observations. Our finding indicates that the crystal structure of the nanocrystal can be determined by the analyses of Raman scattering spectral shape. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Quasi‐equilibrium emission of excited semiconductors
Authors: Richter F. , Manzke G. , Henneberger K.
Published: October 2008

As a first detailed study on the basis of a recently found basic law for the non‐equilibrium energy flow in bounded media, we examine the absorption spectra of an excited semiconductor slab and present detailed calculations for its emission spectra in quasi‐equilibrium. The density of excited carriers is varied from the excitonic regime up to densities where gain appears.

Different slab lengths are regarded, and the dependence on the angle of incidence is studied. The absorption and emission spectra follow the Fabry‐Perot resonances in the slab. Depending on its length, excitation, and the position of the resonances, the formation of sharp and strong emission lines is observed, and degeneracy effects become apparent. (© 2009 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The Kirchhoff index and the matching number
Authors: Zhou Bo , Trinajstić Nenad
Published: October 2008

The Kirchhoff index of a connected (molecular) graph is the sum of the resistance‐distances between all unordered pairs of vertices and may also be expressed by its Laplacian eigenvalues. We determine the minimum Kirchhoff index of connected (molecular) graphs in terms of the number of vertices and matching number and characterize the unique extremal graph. The results on the Kirchhoff index are compared with the corresponding results on the Wiener index. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009
Computer‐assisted implant surgery; a flapless surgical/immediate loaded approach with 1 year follow‐up
Authors: Nikzad Sakineh , Azari Abbas
Published: October 2008

Background

It has been suggested that for success with immediate loaded dental implants it is necessary that, prior to their placement, bone quantity and quality as well as the biomechanical environment in which the implants are to function be evaluated. However, conventional techniques currently used for immediate implant placement lack sufficient precision and are usually accomplished by opening flap procedures. The purpose of this paper is to report the benefit of sophisticated pre‐operative diagnostic implant planning and a flapless surgical approach with immediate loading.

Methods

The report describes the use of computed tomography (CT) for three‐dimensional (3D) evaluations of bone implant sites, an interactive software program for 3D planning and the fabrication of stereolithographic models as custom surgical templates. The degree of patient satisfaction was evaluated by periodic recall and by adopting a specially designed analogue scale in each visit.

Results

The mean amount of bone loss around the implants was 0.5 ± 0.1 mm and the satisfactoriness scale was rated high (i.e. 81), at the end of 1 year.

Conclusion

The use of stereolithographic appliances in accordance with flapless surgery makes immediate placement of the implants more predictable. Copyright © 2008 John Wiley & Sons, Ltd.
Urban environmental performance in China: a sustainability divide?
Authors: Liu Lee
Published: October 2008

This paper explores a sustainability divide in urban environmental protection in China with its 72 Model Cities, 113 key cities, and 43 most polluted cities. It investigates factors that help understand such a divide, the applicability of the environmental Kuznets curve (EKC), and policies for sustainable urban development. Geographic information systems (GIS) and statistical analyses used data derived from documents, statistical records, publications, on‐site inspections and field research. The key cities were divided into seven groups based on eight environmental indicators. The research found a sustainability gap between eastern and western cities, or between Model Cities and other key cities. Oddly, environmental spending was not found to be an explanation. The paper argues that sustainability studies needs to move beyond the EKC to consider the role of nature. Chinese policy makers should not use the Model Cities to support the ‘grow first and clean up later’ approach. Instead they should promote sustainability in all parts of China. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Challenges in operating sustainability initiatives in Northwest Mexico
Authors: Velázquez Luis , Munguía Nora , Zavala Andrea , Navarrete Maria de los Ángeles
Published: October 2008

This paper is aimed at describing the evolutive strategy that the University of Sonora is following to promote regional sustainable development initiatives in Northwest Mexico as well as debating the challenges in implementing it effectively. The institutional partnership and outreach efforts with local industries, community groups, governmental agencies, educational institutions and non‐governmental organizations comprise the provision of technical assistance, advising services, performance of demonstration projects and capacity building.

There are both significant challenges and opportunities for industry facing the dilemma of compliance with environmental and occupational pressures. These challenges have serious practical and theoretical implications not only for conducting sustainability research studies but also for implementing cleaner production and pollution prevention interventions. Slowly but surely, regional sustainability leaders have increased their capacity to better respond to awkward sustainability situations; capacity building has been a central task in ensuring the use of the resources and in ensuring an adequate performance.

As outlined in this paper, adequate conditions for the successful implementation of regional sustainability initiatives are not present. Low levels of awareness, lack of external drives, data uncertainty and lack of capacity have emerged as main barriers preventing success. Additional challenges to sustainability progress include lack of time, lack of interest, lack of funding and lack of training. Copyright © 2008 John Wiley & Sons, Ltd and ERP Environment.
Applying permutation tests with adjustment for covariates and attrition weights to randomized trials of health‐services interventions
Authors: Tang Lingqi , Duan Naihua , Klap Ruth , Asarnow Joan Rosenbaum , Belin Thomas R.
Published: October 2008

Using a health‐services study as an illustrative example of longitudinal randomized field research with the potential for participants to be lost to follow‐up, we apply a permutation test where the treatment indicator variable is randomly permuted in the context of regression models with covariates and attrition weighting. The test is applied to a multi‐site randomized intervention trial of a quality‐improvement program for adolescent depression treatment in primary‐care settings, in which regression models were used to assess intervention effects with weights used to adjust for attrition bias. The foundation and motivation for this approach to the analysis are considered with attention to the demands associated with implementing such a strategy. The results from the permutation tests were qualitatively similar to the results obtained from conventional parametric models, and in fact suggested that the significance level from the conventionalt‐test was understated in this application. Copyright © 2008 John Wiley & Sons, Ltd.
Maximum likelihood, multiple imputation and regression calibration for measurement error adjustment
Authors: Messer Karen , Natarajan Loki
Published: October 2008

In epidemiologic studies of exposure–disease association, often only a surrogate measure of exposure is available for the majority of the sample. A validation sub‐study may be conducted to estimate the relation between the surrogate measure and true exposure levels. In this article, we discuss three methods of estimation for such a main study/validation study design: (i) maximum likelihood (ML), (ii) multiple imputation (MI) and (iii) regression calibration (RC). For logistic regression, we show how each method depends on a different numerical approximation to the likelihood, and we adapt standard software to compute both MI and ML estimates. We use simulation to compare the performance of the estimators for both realistic and extreme settings, and for both internal and external validation designs. Our results indicate that with large measurement error or large enough sample sizes, ML performs as well as or better than MI and RC. However, for smaller measurement error and small sample sizes, either ML or RC may have the advantage. Interestingly, in most cases the relative advantage of RC versus ML was determined by the relative variance rather than the bias of the estimators. Software code for all three methods in SAS is provided. Copyright © 2008 John Wiley & Sons, Ltd.
Guidelines for effective eridging in global software engineering
Authors: Milewski Allen E. , Tremaine Marilyn , Köbler Felix , Egan Richard , Zhang Suling , O'Sullivan Patrick
Published: October 2008

Globally distributed software engineering involves one or more of geographic, temporal or cultural distances, which empirical studies find have deleterious effects on the efficiency of the software engineering process. There have been some successful examples where one ‘bridge’ location has facilitated collaboration and coordination across the other locations. Managers might want to use this bridging as a tactic for future projects, even when future collaborations may be composed of very different participants and in different locations and contexts than current successfully bridged teams. However, group behaviour is complicated and establishing an effective bridge is neither a simple nor a straightforward step. We propose a set of guidelines, based on empirical findings, to help managers understand what to expect from the bridging tactic. These include cultural, organizational, individual and temporal factors as well as insights into the costs and benefits of bridging. Copyright © 2008 John Wiley & Sons, Ltd.
Association of lifetime cadmium intake or drinking Jinzu River water with the occurrence of renal tubular dysfunction
Authors: Kobayashi Etsuko , Suwazono Yasushi , Dochi Mirei , Honda Ryumon , Kido Teruhiko
Published: October 2008

This study was performed to clarify whether lifetime cadmium (Cd) intake (LCd) calculated from consumption of Cd‐polluted rice and other foods, or drinking and/or cooking with Jinzu River water is associated with the occurrence of renal tubular dysfunction and to estimate the threshold level of LCd using a benchmark dose procedure. From participants in the 1967 and 1968 health examinations, the 2607 subjects (1430 men and 1177 women) who were aged 50 years or more, and who had either resided in the current hamlet since birth or moved there from a nonpolluted area and resided for a total of 30 years or longer were chosen as the target population. Based on a multiple logistic regression analysis performed for abnormal urinary findings (proteinuria, glucosuria, or proteinuria with glucosuria) using LCd as the explanatory variable with or without consideration of use of the river water for drinking and/or cooking, it was inferred that both factors of LCd and use of the river water influenced the occurrence of renal tubular dysfunction, with LCd appearing to exert a greater impact compared to drinking/cooking with the river water. Moreover, the threshold values of LCd for proteinuria with glucosuria were estimated to be 2.91 g in men and 1.79 g in women, without adjustment for use of the river water. After adjustment for its use, the values of proteinuria were calculated to be 0.93 g in women. When assuming user/nonuser status of the river water, the threshold level was calculated as 0.75/0.93 g in women. The difference of 0.18 g was interpreted as representing the influence of drinking/cooking with the river water. © 2008 Wiley Periodicals, Inc. Environ Toxicol, 2009.
Homonymous role in role‐based discretionary access control
Authors: Chu Xiaowen , Ouyang Kai , Chen Hsiao‐Hwa , Liu Jiangchuan , Jiang Yixin
Published: October 2008

The access control model is a core aspect of trusted information systems. Based on the role based access control (RBAC) model, we put forward the concept of thehomonymous role, which extends the role control categories in RBAC, balances the control granularity and the storage space requirements, and executes the fine‐grained access control. Instead of the traditional global access control policies (GACP), we propose thehomonymous control domain(HCD) mechanism to enable the coexistence of multiple types of access control policies in a single system, thereby improving the control granularity and flexibility. The HCD mechanism facilitates the discretionary supporting of independent access control policies for its homonymous user. The HCD mechanism and the traditional access control mechanism can be linked to construct a two‐layer access control policy mechanism for a system. Notably, we also consider the temporal characteristic in HCD, which is a critical feature of modern access control models. Furthermore, we analyze the conflicts between the HCD and GACP mechanisms. Finally, we design and implement our HCD on FreeBSD to demonstrate the advantages of the two‐layer access control mechanism. Copyright © 2008 John Wiley & Sons, Ltd.
Eulerian and Lagrangian formulations of steady rotating annuli
Authors: Shum Wai Sun , Lin Zhang
Published: October 2008

It is interesting to ask if there are any fundamental differences between Eulerian and Lagrangian formulations in structural dynamics problems. Steady rotating annuli formulated in both Eulerian and Lagrangian coordinates are exemplified for the present study. Nonlinear strain‐displacement relationships for radial vibration only without circumferential motion in polar coordinates are derived. Linear and nonlinear strain‐displacement relationships are implemented to form the governing equations and are compared to check for the validity of small strain analysis. By including the Poisson's effect, the resulting governing equations are nonlinear equations with material density redistribution and plate thickness variation. Analytical solutions of the linearized versions of nonlinear Eulerian and Lagrangian governing equations by keeping material density and plate thickness constant are offered. Fundamental issues in existence and uniqueness of analytical solutions are discussed between linear Eulerian and linear Lagrangian formulations. Furthermore, the fundamental difference of imposing free edge boundary conditions in Eulerian and Lagrangian coordinates is emphasized. Results show that there are in general insignificant differences between Eulerian and Lagrangian descriptions for circular plate problems, although the approaches to solve the problems in the two formulations are quite different.
A Brazilian galactosialidosis patient given renal transplantation: A case report
Authors: Kiss A. , Zen P. R. G. , Bittencourt V. , Paskulin G. A. , Giugliani R. , d'Azzo A. , Schwartz I. V.
Published: October 2008

We report a Brazilian girl who was diagnosed as having galactosialidosis (deficiency of protective protein/cathepsin A; PPCA deficiency; GS) at the age of 2 years 6 months during an extensive investigation for renal failure. She was found to have low levels of both β‐galactosidase and α‐neuraminidase in fibroblasts and to be a carrier of two novel mutations in thePPGBgene (p.G57V and p.R396W). She received a renal allograft at the age of 3 years 4 months. Transplantation was successful and graft function remains excellent after 6 years. However, the patient shows signs of progression of her primary disease. To our knowledge, she is the first GS patient to be given renal transplantation worldwide. We propose that renal transplantation should be considered as a therapeutic option for the treatment of severe renal complications of GS.
Enzyme replacement therapy stabilizes obstructive pulmonary Fabry disease associated with respiratory globotriaosylceramide storage
Authors: Wang R. Y. , Abe J. T. , Cohen A. H. , Wilcox W. R.
Published: October 2008

Fabry disease is an X‐linked glycosphingolipidosis caused by a deficiency of α‐galactosidase A, a lysosomal enzyme. Symptoms in hemizygous males and heterozygous females are due to lysosomal storage of globotriaosylceramide in the central and peripheral nervous system, vascular endothelium, cardiac valves and myocytes, gastrointestinal tract, and renal epithelium. Pulmonary involvement is also a recognized manifestation of Fabry disease, but histopathological evidence of pulmonary lysosomal storage is scant. We report a 51‐year‐old woman with a G43R α‐galactosidase A mutation and normal spirometry testing 2.5 years prior to presentation, who experienced a dry, nonproductive cough that persisted despite treatment with antibiotics and bronchodilators. Spirometry demonstrated a mixed restrictive/obstructive pattern as well as impaired gas exchange. Patchy ground‐glass pulmonary interstitial infiltrates were found on plain radiography and computerized tomography. She underwent an open lung biopsy that demonstrated peribronchiolar fibrosis and smooth‐muscle hyperplasia. Prominent inclusion bodies of the bronchiolar/arteriolar smooth muscle and endothelium were present. Electron microscopy indicated the inclusion bodies were lamellated zebra bodies consistent with globotriaosylceramide storage. Enzyme replacement therapy (ERT) with agalsidase‐beta was instituted. Since initiation of therapy, she occasionally has a dry cough but markers of obstructive lung disease have remained stable in the past 4 years. This report demonstrates that pulmonary involvement in Fabry disease is due to lysosomal storage, and suggests that ERT is capable of stabilizing pulmonary Fabry disease. However, progressive worsening of her total lung capacity indicates that ERT cannot reverse the ongoing process of fibrosis also seen in Fabry disease.
Biochemical characterization of mutant phenylalanine hydroxylase enzymes and correlation with clinical presentation in hyperphenylalaninaemic patients
Authors: Dobrowolski S. F. , Pey A. L. , Koch R. , Levy H. , Ellingson C. C. , Naylor E. W. , Martinez A.
Published: October 2008

The biochemical properties of mutant phenylalanine hydroxylase (PAH) enzymes and clinical characteristics of hyperphenylalaninaemic patients who bear these mutant enzymes were investigated. Biochemical characterization of mutant PAH enzymes p.D143G, p.R155H, p.L348V, p.R408W and p.P416Q included determination of specific activity, substrate activation, Vmax, Km for (6R)‐l‐erythro‐5,6,7,8‐tetrahydrobiopterin (BH4), Kd for BH4, and protein stabilization by BH4. Clinical data from 22 patients either homozygous, functionally hemizygous, or compound heterozygous for the mutant enzymes of interest were correlated with biochemical parameters of the mutant enzymes. The p.L348V and p.P416Q enzymes retain significant catalytic activity yet were observed in classic and moderate PKU patients. Biochemical studies demonstrated that BH4 rectified the stability defects in p.L348V and p.P416Q; additionally, patients with these variants responded to BH4 therapy. The p.R155H mutant displayed low PAH activity and decreased apparent affinity for l‐Phe yet was observed in mild hyperphenylalaninaemia. The p.R155H mutant does not display kinetic instability, as it is stabilized by BH4 similarly to wild‐type PAH; thus the residual activity is available under physiological conditions. The p.R408W enzyme is dysfunctional in nearly all biochemical parameters, as evidenced by disease severity in homozygous and hemizygous patients. Biochemical assessment of mutant PAH proteins, especially parameters involving interaction with BH4 that impact protein folding, appear useful in clinical correlation. As additional patients and mutant proteins are assessed, the utility of this approach will become apparent.
Long‐term compliance with a novel vitamin and mineral supplement in older people with PKU
Authors: MacDonald A. , Lee P. , Davies P. , Daly A. , Lilburn M. , Gokmen Ozel H. , Preece M. A. , Hendriksz C. , Chakrapani A.
Published: October 2008

Background:

The long‐term efficacy of vitamin and mineral preparations in dietary‐treated adult patients with phenylketonuria (PKU) is unreported. Aim: In an open, intervention trial, the acceptability, safety and impact on biochemical and haematological micronutrient status of a new vitamin and mineral tablet (Phlexy Vits, SHS International) was investigated.

Methods:

Fifteen subjects with PKU (median age 21 years, range 8–33 years) on low‐phenylalanine diet from two PKU centres were recruited. No vitamins or minerals were added to their protein substitute and for 12 months they took their full daily requirements of vitamin and minerals from Phlexy Vits (5 tablets/daily). All but two subjects had taken alternative vitamin and mineral supplements before the trial. Fasting bloods were taken at baseline (week −2 and at week 0), 4 and 12 months for a range of biochemical and nutritional measurements.

Results:

By 4 months, serum vitamin B12 (p = 0.003), serum manganese (p=0.03) and plasma (p=0.03) and red blood cell (p=0.004) glutathionine peroxidase (GSHPx) all significantly increased but remained within normal reference ranges. By 12 months, serum vitamin B12 (p<0.05) and plasma GSHPx (p<0.05) remained increased. The Phlexy Vits tablets scored better than conventional vitamin and mineral supplements for overall acceptability (p<0.05), and ease of swallowing (p=0.1) at 4 months, although swallowing score deteriorated by 12 months (p<0.05). There was a small but significant deterioration in compliance with taking the vitamin and mineral supplements between 4 and 12 months (p<0.05).

Conclusion:

In the long term, these comprehensive vitamin and mineral tablets appeared acceptable and improved biochemical nutritional status, although there were long‐term compliance and swallowing issues.
Tools for Assessing Readability and Quality of Health‐Related Web Sites
Authors: Shedlosky‐Shoemaker Randi , Sturm Amy Curry , Saleem Muniba , Kelly Kimberly M.
Published: October 2008

With the Internet becoming a growing source of information on genetics, genetic counselors and other health‐care providers may be called upon to guide their patients to appropriate material, which is written at a suitable reading level for the individual and contains quality information. Given that many health‐related Web sites are written at a high school or higher reading level, without direction from a genetic counselor or health‐care provider, many Internet users may currently be turning to health‐related Web sites that they do not understand. Additionally, Internet users may not know how to evaluate the quality of information they find, which could lead to them access inaccurate or irrelevant information. To aid in the process of finding and designing Web sites that are appropriate for patients, the current article provides guidelines for assessing readability and quality of health‐related content. Additionally, a demonstration of an assessment is provided. Finally, limitations of these assessments are discussed.
Transpiration of Cyclobalanopsis glauca (syn. Quercus glauca) stand measured by sap‐flow method in a karst rocky terrain during dry season
Authors: Huang Yuqing , Zhao Ping , Zhang Zhongfeng , Li Xiankun , He Chengxin , Zhang Ruiquan
Published: October 2008

Seasonal drought may have a high impact on the karst ecosystem. The transpiration from Cyclobalanopsis glauca (syn. Quercus glauca) stand on a rocky hilly slope in South China was measured during the dry period of 2006 by using the Granier's sap‐flow method. During the experimental period, maximum sap flux density (Js) ranged from 20 to 40 g H2O m−2 s−1 according to diameter of breast height (DBH) of individual trees. On sunny days, daily transpiration varied between 3.4 and 1.8 mm day−1. Transpiration of C. glauca was closely correlated to the radiation, air temperature, and vapor pressure deficit (VPD). Soil moisture was a very important factor influencing transpiration. The very low soil water content might result in low stand transpiration even when VPD is high, but high soil water content might also result in low transpiration if it was low VPD. However, VPD rather than soil moisture, affected largely the stand transpiration under high soil water content. The amount of transpiration was much more than that of the total soil moisture loss during the continuous sunny days, indicating that the dry shallow soils were probably not the only source for root‐uptake water. C. glauca grows deep roots through the rock fissures of epikarst, indicating that epikarst might be another main source for sustaining transpiration in response to dry demand in autumn. Therefore, a large amount of deep roots of karst species would be a very important hydraulic connecting from the epikarst to above ground by transpiration, which would promote the biogeochemical process in a karst system.
Food selection in Microtus arvalis: the role of plant functional traits
Authors: Lantová Petra , Lanta Vojtěch
Published: October 2008

We offered captive common voles (Microtus arvalis) a choice of 11 plant species (representing four ecological groups) growing in vivaria. Selection was evaluated by measuring (1) the biomass of each plant species consumed and (2) functional and life‐history plant traits. The legume Trifolium pratense, known for its high nutrient level, and well accessible rosette forbs creating the highest biomass at the soil ground level, were mostly preferred. Voles avoided mainly grasses and the creeping forb Thymus pulegioides. The experiment showed that foraging was strongly plant species‐specific. We assessed whether plant functional traits explain selective foraging in common voles. To explore this, we reanalyzed Holišová's (1959) data about common vole stomach contents and plant trait databases. Regression tree analysis indicated that plant guild and life span were the best predictors of dietary selection, with a probability exceeding 0.5 that voles would eat more grasses and/or legumes than forbs. These results do not correspond with the feeding trial. We suggest that the voles usually consume grasses in the field because grasses are abundant and readily available, but prefer protein‐rich forbs when possible.
Effects of Shape and Strain Distribution of Quantum Dots on Optical Transition in the Quantum Dot Infrared Photodetectors
Authors: Yang X-F , Chen X-S , Lu W , Fu Y
Published: October 2008

We present a systemic theoretical study of the electronic properties of the quantum dots inserted in quantum dot infrared photodetectors (QDIPs). The strain distribution of three different shaped quantum dots (QDs) with a same ratio of the base to the vertical aspect is calculated by using the short-range valence-force-field (VFF) approach. The calculated results show that the hydrostatic strain ɛHvaries little with change of the shape, while the biaxial strain ɛBchanges a lot for different shapes of QDs. The recursion method is used to calculate the energy levels of the bound states in QDs. Compared with the strain, the shape plays a key role in the difference of electronic bound energy levels. The numerical results show that the deference of bound energy levels of lenslike InAs QD matches well with the experimental results. Moreover, the pyramid-shaped QD has the greatest difference from the measured experimental data.
Investigation of Semiconductor Quantum Dots for Waveguide Electroabsorption Modulator
Authors: Ngo CY , Yoon SF , Loke WK , Cao Q , Lim DR , Wong Vincent , Sim YK , Chua SJ
Published: October 2008

In this work, we investigated the use of 10-layer InAs quantum dot (QD) as active region of an electroabsorption modulator (EAM). The QD-EAM is a p-i-n ridge waveguide structure with intrinsic layer thickness of 0.4 μm, width of 10 μm, and length of 1.0 mm. Photocurrent measurement reveals a Stark shift of ~5 meV (~7 nm) at reverse bias of 3 V (75 kV/cm) and broadening of the resonance peak due to field ionization of electrons and holes was observed for E-field larger than 25 kV/cm. Investigation at wavelength range of 1,300–1320 nm reveals that the largest absorption change occurs at 1317 nm. Optical transmission measurement at this wavelength shows insertion loss of ~8 dB, and extinction ratio of ~5 dB at reverse bias of 5 V. Consequently, methods to improve the performance of the QD-EAM are proposed. We believe that QDs are promising for EAM and the performance of QD-EAM will improve with increasing research efforts.
Desorption of Fructose from a Packed Column to an Oleic Acid/Fructose Oleate Mixture for Employment in a Bioreactor System
Authors: Pyo Sang‐Hyun , Hayes Douglas G.
Published: October 2008

Adsorption isotherms for a packed column consisting of fructose and silica gel in contact with a liquid phase consisting of oleic acid and fructose mono‐ and di‐oleate at 65 °C were determined to assist the column’s utilization in a bioreactor system for the solvent‐free lipase‐catalyzed synthesis of saccharide ester biosurfactants. The liquid‐phase fructose content was very low, ranging from 0.005 to 0.1% (w/w), with the higher values obtained for a higher fructose concentration in the column and a higher ester content in the liquid phase. The desorption behavior of fructose followed the Freundlich isotherm. An increase in the liquid phase space velocity increased the initial rate of fructose desorption linearly. Dynamic light scattering measurements demonstrate solutions obtained by mechanical stirring of crystalline fructose and oleic acid/fructose oleate contained 50–250 μm sized aggregates, even after centrifugation at 12,000 rpm, but that the aggregates were absent from the desorption column effluent stream. Therefore, employment of a desorption column will lead to a low saccharide concentration in the liquid phase, but will reduce suspension‐induced fouling of lipase in a bioreactor downstream of the column, which could improve the retention of lipase activity.
Comparison of nociceptive behavior in prostaglandin E, F, D, prostacyclin and thromboxane receptor knockout mice
Authors: Popp Laura , Häussler Annett , Olliges Anke , Nüsing Rolf , Narumiya Shuh , Geisslinger Gerd , Tegeder Irmgard
Published: October 2008

Antagonist at specific prostaglandin receptors might provide analgesia with a more favourable toxicity profile compared with cyclooxygenase inhibitors. We analyzed nociceptive responses in prostaglandin D, E, F, prostacyclin and thromboxane receptor knockout mice and mice deficient of cyclooxygenase 1 or 2 to evaluate the contribution of individual prostaglandin receptors for heat, mechanical and formalin‐evoked pain. None of the knockouts was uniformly protected from all of these pain stimuli but COX‐1 and EP4 receptor knockouts presented with reduced heat pain and EP3 receptor and COX‐2 knockout mice had reduced licking responses in the 2nd phase of the formalin assay. This was accompanied with reduced c‐Fos immunoreactivity in the spinal cord dorsal horn in EP3 knockouts. Oppositely, heat pain sensitivity was increased in FP, EP1 and EP1+3 double mutant mice possibly due to a loss of FP or EP1 receptor mediated central control of thermal pain sensitivity. Deficiency of either EP2 or DP1 was associated with increased formalin‐evoked flinching responses and c‐Fos IR in dorsal horn neurons suggesting facilitated spinal cord pain reflex circuity. Thromboxane and prostacyclin receptor knockout mice showed normal pain behavior in all tests. The results suggest a differential, pain‐stimulus and site‐specific contribution of specific PG‐receptors for the processing of the nociceptive stimuli, a differential modulation of nociceptive responses by COX‐1 and COX‐2 derived prostaglandins and compensatory and/or developmental adaptations in mice lacking specific PG receptors.
Trans-Zab Jewish Neo-Aramaic
Authors: Mutzafi Hezy
Published: October 2008

The present article seeks to describe a major group of Jewish North-Eastern Neo-Aramaic (NENA) dialects located across the Great Zab river in the eastern and south-eastern parts of the dialectological map of NENA, hence the term “Trans-Zab Jewish Neo-Aramaic” (“Trans-Zab”, for short) chosen for this dialect group. A large set of phonological, morphophonological, morphological and lexical innovations, shared by all members of this group, is presented. Each of the Trans-Zab features is compared with contrastive parallel features in other, selected NENA varieties. Finally, an internal classification of Trans-Zab into three subdivisions is proposed, based on a comparison of three respective paradigms of the positive present copula.
The organs of Han imperial government: zhongdu guan, duguan, xianguan and xiandao guan
Authors: Loewe Michael
Published: October 2008

Passages in received texts and in recently found legal documents show the different ways in which four terms refer to offices of Han imperial government; zhongdu guan indicates offices of the central government in the capital city; duguan signifies offices controlled by the central government but posted to work in the commanderies and counties; xianguan refers to just those offices but it is often used of “the government” in general, and in exceptional cases it specifies the emperor in person; xiandao guan were the offices of provincial government established in the counties (xian) and marches (dao).
On the nature of phonological structure in sign language
Authors: Corina David , Sandler Wendy
Published: October 2008

The study of phonological structure and patterns across languages is seen by contemporary phonologists as a way of gaining insight into language as a cognitive system. Traditionally, phonologists have focused on spoken languages. More recently, we have observed a growing interest in the grammatical system underlying signed languages of the deaf. This development in the field of phonology provides a natural laboratory for investigating language universals. As grammatical systems, in part, reflect the modality in which they are expressed, the comparison of spoken and signed languages permits us to separate those aspects of grammar which are modality-dependent from those which are shared by all human languages. On the other hand, modality-dependent characteristics must also be accounted for by a comprehensive theory of language. Comparing languages in two modalities is therefore of theoretical importance for both reasons: establishing modality-independent linguistic universals, and accounting for modality-dependent structure and organisation.