bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermal‐diffusion and diffusion‐thermo effects on convective heat and mass transfer in a visco‐elastic fluid flow through a porous medium over a stretching sheet
Authors: Salem A. M.
Published: March 2006

An analysis has been carried out to obtain the thermal‐diffusion and diffusion‐thermo effects on the mixed free forced convective and mass transfer in a visco‐elastic fluid flow through a porous medium over a stretching sheet. Here, the driving force for the flow is provided by an impermeable sheet stretched with a velocity proportional to the distance from a slit and buoyancy effects due to both temperature and concentration gradient. The partial differential equations governing the problem under consideration have been transformed by a similarity transformation into a system of ordinary differential equations which are solved numerically by applying the shooting method. The effects of Soret number, Dufour number, visco‐elastic parameter, Porosity parameter, Grashof number and modified Grashof number on the velocity, temperature and concentration have been discussed. Numerical results for the problem considered are given and illustrated graphically. Copyright © 2006 John Wiley & Sons, Ltd.
ASOM applied to dynamic analysis
Authors: Ranjbaran A.
Published: March 2006

The fundamental mode shape and frequency of structural systems are important quantities in all codes of practice for earthquake resistance design. Computation of these quantities is based on the concept of generalized coordinates and/or Rayleigh's method. In these methods the frequency is computed in terms of a chosen shape so is approximate. The exact result corresponds to the exact shape which is not known in advance. Here the method of analysis of structures by the optimization methods (ASOM) is used to obtain the actual shape and so the exact fundamental frequency and mode shape of structural systems. The maximum frequency and corresponding mode shape is obtained as well. The presented algorithm can be a good complement of codes for analysis of fundamental modes of structures. Copyright © 2006 John Wiley & Sons, Ltd.
Mean field dynamics of boson stars
Authors: Elgart Alexander , Schlein Benjamin
Published: March 2006

We consider a quantum mechanical system of N bosons with relativistic dispersion interacting through a mean field Coulomb potential (attractive or repulsive). We choose the initial wave function to describe a condensate where the N bosons are all in the same one‐particle state. Starting from the N‐body Schrödinger equation, we prove that, in the limit N → ∞, the time evolution of the one‐particle density is governed by the relativistic nonlinear Hartree equation. This equation is used to describe the dynamics of boson stars (Chandrasekhar theory). The corresponding static problem was rigorously solved in [10]. © 2005 Wiley Periodicals, Inc.
MOCVD and ALD of High‐k Dielectric Oxides Using Alkoxide Precursors
Authors: Jones A. C. , Aspinall H. C. , Chalker P. R. , Potter R. J. , Manning T. D. , Loo Y. F. , O'Kane R. , Gaskell J. M. , Smith L. M.
Published: March 2006

A number of high‐permittivity (κ) dielectric oxides are currently being investigated as alternatives to SiO2 as the dielectric insulating layer in sub‐0.1 μm CMOS technology. Metal‐organic (MO)CVD and atomic layer deposition (ALD) are promising techniques for the deposition of these high‐κ dielectric oxides. In this paper it is shown how the use of “designed” metal alkoxide precursors, containing bidentate donor‐functionalized alkoxide ligands, in MOCVD leads to a marked improvement in the physical properties of the MOCVD precursors and process parameters. However, the use of such ligands is not as beneficial in the ALD process, highlighting the very different requirements of MOCVD and ALD precursors.
AVD and ALD as Two Complementary Technology Solutions for Next Generation Dielectric and Conductive Thin‐Film Processing
Authors: Schumacher M. , Baumann P. K. , Seidel T.
Published: March 2006

Further scaling of functional layers for 45 nm technology nodes and below will reach the physical limits of conventional materials. It is expected that, for CMOS devices, silicon oxide and poly‐silicon will need to be replaced with alternative high‐k dielectrics, and electrode materials. Additionally for DRAM it appears that 100 % step coverage of deep‐trench structures with aspect ratios approaching 100:1 is going to be necessary. Advanced processing technologies will be needed to overcome the challenges to produce high quality films with high throughput. In this review article, two complementary advanced deposition technologies are described: Atomic vapor deposition (AVD), as a special metal‐organic (MO)CVD process mode, and atomic layer deposition (ALD). The operational principles and deposition results are described for a wide range of dielectric and conductive materials.
Atomic Layer Deposited High‐κ Films and Their Role in Metal‐Insulator‐Metal Capacitors for Si RF/Analog Integrated Circuit Applications
Authors: Zhu C. , Cho B.‐J. , Li M.‐F.
Published: March 2006

In this paper, we present an extensive evaluation of metal‐insulator‐metal (MIM) capacitors by comparing various high‐κ dielectric structures based on atomic layer deposited HfO2 and Al2O3 films at two thicknesses. The results indicate that laminate‐structured MIM capacitors provide superior performance to their sandwiched/stacked counterparts in both thin (∼13 nm) and thick (∼55 nm) dielectric films. Benefits include low leakage current, good polarity‐independent electrical characteristics, high‐breakdown electrical field (voltage), and long time‐to‐breakdown while maintaining comparable capacitance density and voltage coefficients of capacitance. It is noted, however, that the benefits of the laminate structure become less significant when the dielectric thickness decreases. The advantages of the laminate structure are mainly attributed to the alternate insertions of Al2O3 into bulk HfO2, thereby preventing crystallization of HfO2.
Sustainable development ‘outside’ the European Union: what role for impact assessment?
Authors: Adelle Camilla , Hertin Julia , Jordan Andrew
Published: March 2006

Sustainable development is a cross‐cutting issue par excellence that necessitates a very high degree of policy coordination. This is especially true considering that the European Union's 2001 Sustainable Development Strategy demands that all European Union (EU) policies actively support the sustainable development of other countries, particularly those in the developing world. In order to fulfil this ambitious obligation, the EU has pledged to consider the impacts that all new policies have within and outside the EU as part of a new impact assessment (IA) regime. This paper aims to evaluate how well the new IA regime has helped address the ‘external’ dimensions of sustainability through the analysis of potential effects of EU policies on non‐EU countries. It finds that the IA procedure does not currently function as an effective instrument for the implementation of the Union's commitment to promoting sustainability in the developing world. Other coordination mechanisms need to be considered, given the horizontal and vertical complexity of this challenge. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Public attitudes towards the environmental impact of salmon aquaculture in Scotland
Authors: Whitmarsh David , Wattage Premachandra
Published: March 2006

This paper reports the results of a survey of public attitudes towards aquaculture, using salmon farming in Scotland as a case study. The aims have been to identify the priority that people attach to the environmental performance of the salmon aquaculture industry, relative to other objectives, and to measure the economic benefits to society from salmon farmed using methods that cause less organic pollution. The results indicate that the public attach a relatively high importance to minimizing environmental damage from aquaculture, and this has its parallel in the finding that people are willing to pay a price premium for salmon produced in a more environmentally benign way. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
‘Sustainable development’ as a criterion for the interpretation of Article 6 of the Habitats Directive
Authors: Unnerstall Herwig
Published: March 2006

Article 6(4) of the Habitats Directive requires a weighing up of environmental and economic interests in order to allow for deviation from valid environmental standards. This provision has to be interpreted in the light of the tasks and aims of the European treaties, especially in the light of sustainable development (SD). It is not only a political aim, but was also introduced in the European treaties in 1997 as both legally binding task and goal. This paper develops a comprehensive interpretative understanding of these provisions and their consequences for the application of European environmental law. SD is usually understood as being one aim amongst others and having three dimensions of SD (ecological, social and economic) of equal weight. This concept of equal weight contradicts the idea of a common but differentiated responsibility (CBDR), which is an essential part of SD. The CBDR requires that ‘SD’ has de facto different meanings in different member states according to their economic development. Therefore, Article 6 of the Habitats Directive may only be applied in those areas of the Community having a development lag. Copyright © 2006 John Wiley & Sons, Ltd and ERP Environment.
Diamagnetic versus Paramagnetic Structure of SPS‐Type Pincer‐Based CoI, RhI, and IrIComplexes
Authors: Doux Marjolaine , Le Floch Pascal , Jean Yves
Published: March 2006

The lowest singlet and triplet states of SPS‐type pincer‐based [M(SPS)(PPh3)] complexes (M = Co, Rh, and Ir) were studied by means of DFT/B3PW91 calculations on the model complexes in which the nine phenyl substituents were replaced by H atoms. Although the Rh and Ir compounds were found to be diamagnetic with a square‐planar geometry, the yet unknown Co complex was predicted to be paramagnetic(ΔES/T= –22.4 kcal·mol–1) with two unpaired electrons localized on the metal center. Three minima were actually located on the triplet potential energy surface that differ by the arrangement of the ligands (nearly tetrahedral or butterfly geometries), two of them being close in energy (ΔE= 2.5 kcal·mol–1). Finally, the paramagnetism of the Co complex was confirmed by calculations on the real complex at the B3PW91//ONIOM(B3PW91:UFF) level of theory (ΔES/T= –29.6 kcal·mol–1). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Multielectron Storage and Photo‐Induced Electron Transfer in Oligonuclear Complexes Containing Ruthenium(II) Terpyridine and Ferrocene Building Blocks
Authors: Heinze Katja , Hempel Klaus , Beckmann Manuela
Published: March 2006

The heteroleptic complex [(HOOC‐tpy)Ru(tpy‐NH2)](PF6)2 (tpy = 2,2′;6′,2″‐terpyridine) has been incorporated into a multicomponent system with ferrocene moieties attached on either the N‐terminal end or the C‐terminal end and on both ends of the ruthenium complex. Electrochemical studies reveal almost noninteracting subunits in the oligonuclear systems, whereas ground‐state and excited‐state optical properties are shown to strongly depend on the site of ferrocene attachment. Interpretation of the experimental results is supported by DFT calculations. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
On the Staudinger Reaction of SP(N3)3 with PPh3 and(Me3Si)2N–(Me3Si)N–PPh2
Authors: Götz Nadine , Herler Sebastian , Mayer Peter , Schulz Axel , Villinger Alexander , Weigand Jan J.
Published: March 2006

The Staudinger reactions of SP(N3)3 (1) with 1, 2 and 3 equiv. of triphenylphosphane PPh3 and (TMS)2N–(TMS)N–PPh2 (2) have been investigated (TMS = Me3Si). Reaction with PPh3 yields the single and double Staudinger products SP(N3)2NPPh3 (3) and SP(N3)(NPPh3)2 (4), but not the triple, while the reaction with 2 results only in the formation of the single Staudinger product SP(N3)2NPPh2[N(TMS)N(TMS)]2 (5). Compound 5 is air‐ and moisture‐sensitive but stable under argon over a long period in the solid state and in common organic solvents. Although there are covalently bound azide groups in 3, 4 and 5, these Staudinger products are neither shock‐ nor heat‐sensitive in contrast to 1. Furthermore 3, 4 and 5 are easily prepared in bulk (yield > 95 %), and unlimitedly stable when cooled and stored in the dark. Compound 5 is thermally stable up to over 150 °C while 3 and 4 are stable only up to 96 °C. However, when a solution of 5 is heated, a new surprising eight‐membered ring (6) is formed in an intermolecular TMS–N3 elimination reaction. The structure and bonding is discussed on the basis of experimental X‐ray data and theoretical B3LYP calculations (thermodynamics, energy landscape and charge distribution). (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Synthesis of Enantiomerically Pure 2,3,4,6‐Tetrasubstituted Tetrahydropyrans by Prins‐Type Cyclization of Methyl Ricinoleate and Aldehydes
Authors: Biermann Ursula , Lützen Arne , Metzger Jürgen O.
Published: March 2006

The AlCl3‐catalyzed Prins‐type cyclization of methyl ricinoleate (1), an enantiomerically pure renewable compound, with aldehydes such as heptanal (2a), isobutyraldehyde (2b), pivaldehyde (2c) and benzaldehyde (2d) is a simple reaction for the diastereoselective synthesis of enantiomerically pure 2,3,6‐trialkyl‐substituted 4‐chlorotetrahydropyrans. The respective 4‐hydroxytetrahydropyrans are obtained e.g. with aldehydes 2a and 2d using montmorillonite KSF/O as the catalyst. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Nucleophilicity Parameters for Carbanions in Methanol
Authors: Binh Phan Thanh , Mayr Herbert
Published: March 2006

The kinetics of the reactions between eleven carbanions 2a–k (nitronates and malonic acid derivatives) and benzhydrylium ions 1a–g were investigated photometrically in methanol/acetonitrile (91:9, v/v) at 20 °C. Since the competing reactions of the benzhydrylium ions with methanol and methoxide ions are generally slower, the second‐order rate constants of the reactions between the benzhydrylium ions 1a–g and the carbanions 2a–k can be determined with high precision. The second‐order rate constants (log k) correlate linearly with the electrophilicity parameters E of the benzhydrylium ions, allowing us to determine the nucleophilicity parameters N and s of the carbanions in methanol/acetonitrile (91:9, v/v). The nucleophilic reactivities do not correlate with the acidity constants of the conjugate CH acids, and from the poor correlation of the reactivities of the substituted α‐nitrobenzyl anions 2d–h with Hammett’s σ– constants it can be inferred that the nucleophilic reactivities are strongly controlled by solvation. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Diels–Alder Reactions of 2′‐Hydroxychalcones with ortho‐Benzoquino‐dimethane: A New Synthesis of 3‐Aryl‐2‐naphthyl 2‐Hydroxyphenyl Ketones
Authors: Brito Cristela M. , Pinto Diana C. G. A. , Silva Artur M. S. , Silva Ana M. G. , Tomé Augusto C. , Cavaleiro José A. S.
Published: March 2006

Diels–Alder reactions of the 2′‐hydroxychalcones 1a–e with ortho‐benzoquinodimethane (3) yielded the 3‐aryl‐1,2,3,4‐tetrahydro‐2‐naphthyl 2‐hydroxyphenyl ketones 4a–e in good yields. The dehydrogenation of the cycloadducts 4a–e to 3‐aryl‐2‐naphthyl 2‐hydroxyphenyl ketones 5a–e was studied. Good results were obtained when DDQ was used as oxidant and microwave irradiation as energy source. Several benzoxanthone derivatives were also obtained as minor products. Structures of all new compounds were established by extensive NMR studies. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006)
Estimating soil properties in heterogeneous land‐use patches: a Bayesian approach
Authors: Oleson Jacob J. , Hope Diane , Gries Corinna , Kaye Jason
Published: March 2006

Cities provide unique opportunities for integrating humans into ecology. Using data from a socio‐ecological inventory of metropolitan Phoenix, Arizona, we explore the contribution of human‐related variables to explaining observed variation in soil nitrate‐N (NO3N) and total carbon (C) concentrations across the city, agricultural fields, surrounding desert, and mixed regions. Conventional modeling approaches in such a setting would lead to examination of spatial relationships over the entire study area or on subsets of the data independently. However, the spatial relationships for NO3N and C may be different in each of these regions. Here we estimate the correlation coefficients for influential variables toward soil NO3N and C across the entire region, while at the same time accounting for potentially differing spatial patterns in each of these regions. Soil NO3N shows markedly greater spatial autocorrelation in the desert regions, while the soil C shows varying amounts of spatial relationships in the different regions. Copyright © 2006 John Wiley & Sons, Ltd.
Effects of riparian vegetation on stream bank subaerial processes in southwestern Virginia, USA
Authors: Wynn T. M. , Mostaghimi S.
Published: March 2006

Riparian vegetation is frequently used for stream bank stabilization, but the effects of vegetation on subaerial processes have not been quantified. Subaerial processes, such as soil desiccation and freeze–thaw cycling, are climate‐related phenomena that deliver soil directly to the stream and make the banks more vulnerable to fluvial erosion by reducing soil strength. This study compares the impact of woody and herbaceous vegetation on subaerial processes by examining soil temperature and moisture regimes in vegetated stream banks.

Soil temperature and water tension were measured at six paired field sites in southwestern Virginia, USA, for one year. Results showed that stream banks with herbaceous vegetation had higher soil temperatures and a greater diurnal temperature range during the summer compared to forested stream banks. Daily average summer soil water tension was 13 to 57 per cent higher under herbaceous vegetation than under woody vegetation, probably due to evapotranspiration from the shallow herbaceous root system on the bank.

In contrast to summer conditions, the deciduous forest buffers provided little protection for stream banks during the winter: the forested stream banks experienced diurnal temperature ranges two to three times greater than stream banks under dense herbaceous cover and underwent as many as eight times the number of freeze–thaw cycles. During the winter, the stream banks under the deciduous forests were exposed to solar heating and night time cooling, which increased the diurnal soil temperature range and the occurrence of freeze–thaw cycling.

Study results also indicated that freeze–thaw cycling and soil desiccation were greater on the upper stream bank due to thermal and moisture regulation of the lower bank by the stream. Therefore, subaerial erosion and soil weakening may be greater on the upper stream banks. Additional research is needed on the influence of subaerial processes on both subaerial and fluvial erosion. Copyright © 2006 John Wiley & Sons, Ltd.
Grain‐size distribution patterns of a point bar system in the Usri River, India
Authors: Purkait Barendra
Published: March 2006

Grain‐size distribution patterns in a point bar system of the Usri River, India, were critically analysed in the light of log‐normal, log‐hyperbolic and log‐skew‐Laplace distribution models. Sand samples were collected from the cross‐bedding foreset of different sizes of bedform; the objectives were to (i) study whether bedform heights have any role in grain‐size distribution patterns, (ii) offer a best‐fit statistical model, (iii) study the downstream variation of size‐sorting in a point bar system, and (iv) study the mechanism of grain sorting.

The results indicate that the bedform heights have no role in grain‐size distribution patterns. Quantitatively when the errors in three distribution models were analysed, it was observed that the log‐normal distribution is the best‐fit statistical model and the next one is the log‐skew‐Laplace. However, in the upper reaches of the river, log‐normal distribution is the best‐fit model in the case of large bedforms, whereas in the lower reaches the log‐normal model is the best‐fit one in the case of small bed forms.

It is also observed that within a point bar, for large and small bedforms, there is a tendency for mean grain size to decrease downstream. Between point bars for large bedforms there is no consistency in decreasing grain size downstream, whereas for small bed forms the decrease of grain size downstream is observed except near the confluence at Palkia.

With distance of transport, the coarser and finer fractions of sediments are gradually chopped off. The coarser fractions are buried below the advancing bedforms on the lee sides and the finer ones are transported further downstream. Thus the finer admixture giving rise to the fining‐upward sequence overlies a carpet of coarser materials. This mechanism provides a clue to the process of grain sorting in the fluvial environment.

An interpretation has been offered for the log‐normality of the grain‐size distribution pattern. During prolonged transportation in a fluvial environment, the larger grain‐size fractions are gradually chopped off and buried below the advancing bedforms on their lee sides. On the other hand, the finer fractions are transported further downstream in suspension. Thus the narrow, intermediate size fraction takes active part in the distribution patterns leading to the generation of unimodality and a symmetric distribution pattern downstream, which are the main criteria for log‐normality. Similarly, increase of bedform size is the effect of increase of stream power and Froude number leading to the selective segregation of bed materials. Thus the intermediate size fractions take a more active part than the coarser and the finer size fractions in developing log‐normality.

Besides the hydrodynamic parameters of the Usri, coarsening of grain size downstream has been attributed to (i) the aggrading nature of the Usri downstream, and (ii) the contribution of coarser materials to the Usri by its tributaries and bank erosion. Copyright © 2006 John Wiley & Sons, Ltd.
Soil detachment and transport on field‐ and laboratory‐scale interrill areas: erosion processes and the size‐selectivity of eroded sediment
Authors: Issa O. Malam , Bissonnais Y. Le , Planchon O. , Favis‐Mortlock David , Silvera Norbert , Wainwright John
Published: March 2006

Field‐ and laboratory‐scale rainfall simulation experiments were carried out in an investigation of the temporal variability of erosion processes on interrill areas, and the effects of such variation upon sediment size characteristics. Poorly aggregated sandy soils from the semi‐arid environment of Senegal, West Africa, were used on both a 40 m2 field plot and a 0·25 m2 laboratory plot; rainfall intensity for all experiments was 70 mm h−1 with a duration of 1 to 2 hours. Time‐series measurements were made of the quantity and the size distribution of eroded material: these permitted an estimate of the changing temporal balance between the main erosion processes (splash and wash). Results from both spatial scales showed a similar temporal pattern of runoff generation and sediment concentration. For both spatial scales, the dominant erosional process was detachment by raindrops; this resulted in a dynamic evolution of the soil surface under raindrop impact, with the rapid formation of a sieving crust followed by an erosion crust. However, a clear difference was observed between the two scales regarding the size of particles detached by both splash and wash. While all measured values were lower than the mean weight diameter (MWD) value of the original soil (mean 0·32 mm), demonstrating the size‐selective nature of wash and splash processes, the MWD values of washed and splashed particles at the field scale ranged from 0·08 to 0·16 mm and from 0·12 to 0·30 mm respectively, whereas the MWD values of washed and splashed particles at the laboratory scale ranged from 0·13 to 0·29 mm and from 0·21 to 0·32 mm respectively. Thus only at the field scale were the soil particles detached by splash notably coarser than those transported by wash. This suggests a transport‐limited erosion process at the field scale. Differences were also observed between the dynamics of the soil loss by wash at the two scales, since results showed wider scatter in the field compared to the laboratory experiments. This scatter is probably related to the change in soil surface characteristics due to the size‐selectivity of the erosion processes at this spatial scale. Copyright © 2006 John Wiley & Sons, Ltd.
Viscous flow computations of aircraft with changing control surface deflection using unstructured dynamic meshes
Authors: Murayama Mitsuhiro , Ito Yasushi , Nakahashi Kazuhiro , Matsushima Kisa , Iwamiya Toshiyuki
Published: March 2006

A three‐dimensional unstructured dynamic mesh method for viscous flow computations is presented to simulate aircraft performance when control surface deflection is changed. The method includes an efficient surface mesh movement algorithm for unstructured hybrid meshes comprised of tetrahedra, prisms and pyramids. The method is applied to numerical simulations of the static longitudinal stability control of an experimental supersonic airplane designed at the Japan Aerospace Exploration Agency (previously known as the National Aerospace Laboratory of Japan). The deflection angles of the horizontal tail wings are changed at freestream Mach numbers of 2.0 and 0.95. The results are validated by comparison with experimental results, and the differences in the flow characteristics at the given flow conditions are estimated. Copyright © 2006 John Wiley & Sons, Ltd.
Evolution of novelty in the cichlid dentition
Authors: Streelman Jeffrey Todd , Albertson R. Craig
Published: March 2006

The shape of teeth occupies a central position in various biological disciplines, from paleo‐ecology to molecular biology to cosmetic and reconstructive dentistry. Despite a long tradition of study in mammals, important questions remain regarding the genetic and developmental basis of differences in tooth shape. Here, we use natural mutants of cichlid fish from East Africa, which exhibit tremendous dental diversity, to help fill the gaps in our understanding of vertebrate odontogenesis. We employ an expanded genetic linkage map to demonstrate that cusp number segregates as a gene of major effect, which explains ∼40% of the phenotypic variance, on cichlid chromosome 5. Furthermore, we examine patterns of Bmp4 expression in early odontogenesis to address and refine predictions of models linking tooth shape and tooth number. Mutations in the Bmp4 cistron do not control tooth shape in this mapping cross. Our data suggest that the evolution of novelty in the cichlid dentition is galvanized by a small number of genetic changes, echoing similar conclusions from recent studies of other vertebrate adaptive morphologies. J. Exp. Zool. (Mol. Dev. Evol.) 306B, 2006. © 2006 Wiley‐Liss, Inc.
Accurate quantification of visceral adipose tissue (VAT) using water‐saturation MRI and computer segmentation: Preliminary results
Authors: Armao Diane , Guyon Jean‐Philippe , Firat Zeynep , Brown Mark A. , Semelka Richard C.
Published: March 2006

Purpose

To describe and evaluate the accuracy of water‐saturation MRI and a computer segmentation program for quantification of visceral adipose tissue (VAT).

Materials and Methods

MRI was performed on five patients with whole‐volume coverage of the abdomen using two different sequences: 1) a T1‐weighted spoiled gradient‐echo breath‐hold sequence (non‐water‐saturation) and 2) a T1‐weighted spoiled gradient‐echo water‐saturation breath‐hold sequence (water‐saturation). The computer segmentation program analyzed the data and calculated VAT volumes (cm3) from both sequences. The data from one patient were additionally processed with the use of a manual technique. The intrastudy reproducibility of the proposed method using the water‐saturation MRI sequence and the computer segmentation technique was tested by repeated measures of the automated system analysis (×10) on MRI data from a single subject to calculate variability.

Results

VAT volumes measured by the water‐saturation MRI sequences were consistently greater than those measured by the non‐water‐saturation sequences. Comparison of VAT volumes derived from the water‐saturation images and measured by the computer segmentation technique vs. the manual technique showed good correlation (K = 0.8), with a significant time‐saving benefit associated with the automated method (5 minutes vs. 1 hour). There was poor correlation between VAT volume measurement calculated by the manual technique and the computer segmentation technique using non‐water‐saturation images. The reproducibility of the computer segmentation technique using data derived from water‐saturation images was high, with a low variability (±5%).

Conclusion

The results obtained demonstrate that the proposed method may be able to provide accurate quantification of VAT in a highly reproducible and efficient manner. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Diffusion tensor imaging (DTI) of rodent brains in vivo using a 1.5T clinical MR scanner
Authors: Lee Francis K.H. , Fang Ma‐Rong , Antonio Gregory E. , Yeung David K.W. , Chan Edward T.Y. , Zhang Li‐Hong , Yew David T. , Ahuja Anil T.
Published: March 2006

Purpose

To evaluate the feasibility of using a clinical 1.5T MR scanner to perform magnetic resonance (MR) diffusion tensor imaging (DTI) on in vivo rodent brains and to trace major rodent neuronal bundles with anatomical correlation.

Materials and Methods

Two normal adult Sprague Dawley (SD) rats were anesthetized and imaged in a 1.5T MR scanner with a microscopic coil. DTI was performed at a resolution of 0.94 mm × 0.94 mm × 0.5 mm (reconstructed to 0.47 mm × 0.47 mm × 0.5 mm, with b‐factors of 600 seconds/mm2 and 1000 seconds/mm2) and a higher resolution of 0.63 mm × 0.63 mm × 0.5 mm (reconstructed to 0.235 mm × 0.235 mm × 0.5 mm, with a b‐factor of 1500 seconds/mm2). The fiber‐tracking results were correlated with corresponding anatomical sections stained to visualize neuronal fibers. The apparent diffusion coefficient (ADC) and fractional anisotropy (FA) of the neuronal fibers were measured and compared with results in published reports.

Results

Several major neuronal fiber tracts, including the corticospinal cord, corpus callosum, and anterior commissure, were identified in all DTI data sets. Stained anatomical sections obtained from the rats confirmed the location of these fibers. The ADC values (0.6–0.8 ± 10−3 mm2/second) of the fibers were similar to published figures. However, the FA values (0.3–0.35) were lower than those obtained in previous studies of white matter in rodent spinal cord.

Conclusion

We have demonstrated the feasibility of using a 1.5T clinical MR scanner for neuronal fiber tracking in rodent brains. The technique will be useful in rodent neuroanatomy studies. Further investigation is encouraged to verify the FA values generated by DTI with such techniques. J. Magn. Reson. Imaging 2006. © 2006 Wiley‐Liss, Inc.
Pathological effects of glyoxalase I inhibition in SH‐SY5Y neuroblastoma cells
Authors: Kuhla Björn , Lüth Hans‐Joachim , Haferburg Dietrich , Weick Michael , Reichenbach Andreas , Arendt Thomas , Münch Gerald
Published: March 2006

In Alzheimer's disease (AD), in aging, and under conditions of oxidative stress, the levels of reactive carbonyl compounds continuously increase. Accumulating carbonyl levels might be caused by an impaired enzymatic detoxification system. The major dicarbonyl detoxifying system is the glyoxalase system, which removes methylglyoxal in order to minimize cellular impairment. Although a reduced activity of glyoxalase I was evident in aging brains, it is not known how raising the intracellular methylglyoxal level influences neuronal function and the phosphorylation pattern of tau protein, which is known to be abnormally hyperphosphorylated in AD. To simulate a reduced glyoxalase I activity, we applied an inhibitor of glyoxalase I, p‐bromobenzylglutathione cyclopentyl diester (pBrBzGSCp2), to SH‐SY5Y neuroblastoma cells to induce chronically elevated methylglyoxal concentrations. We have shown that 10 μM pBrBzGSCp2 leads to a fourfold elevation of the methylglyoxal level after 24 hr. In addition, glyoxalase I inhibition leads to reduced cell viability, strongly retracted neuritis, increase in [Ca2+]i, and activation of caspase‐3. However, pBrBzGSCp2 did not lead to tau “hyper”‐phosphorylation despite activation of p38 mitogen‐activated protein kinase and c‐Jun NH2‐terminal kinase but rather activated protein phosphatases 2 and induced tau dephosphorylation at the Ser202/Thr205 and Ser396/Ser404 epitopes. Preincubation with the carbonyl scavenger aminoguanidine prevented tau dephosphorylation, indicating the specific effect of methylglyoxal. Also, pretreatment with the inhibitor okadaic acid prevented tau dephosphorylation, indicating that methylglyoxal activates PP‐2A. In summary, our data suggest that a reduced glyoxalase I activity mimics some changes associated with neurodegeneration, such as neurite retraction and apoptotic cell death. © 2006 Wiley‐Liss, Inc.
Enhanced endocrine response to novel environment stress and lack of corticosterone circadian rhythm in staggerer (Rora sg/sg) mutant mice
Authors: Frédéric Florence , Chianale Colette , Oliver Charles , Mariani Jean
Published: March 2006

The staggerer (Rora sg/sg) mutation is a deletion in the retinoid‐related orphan receptor (RORα) gene that prevents translation of the ligand‐binding domain (LBD), leading to the loss of RORα activity. RORα is a transcription factor that belongs to the nuclear receptor superfamily. In the brain, RORα is expressed in specific areas, including the cerebellum and suprachiasmatic nucleus (SCN). The homozygous Rora sg/sg mutant mouse, of which the most obvious phenotype is ataxia associated with cerebellar degeneration, also overproduces inflammatory cytokines. Here we compared the response to novelty stress of staggerer and wild‐type mice as well as their diurnal cycles of adrenocorticotropic hormone and corticosterone secretion. We show that the staggerer mouse displays an enhanced endocrine response to novelty stress, which is not due to the enhanced production of interleukin‐1 (IL‐1), insofar as it is not blocked by pretreatment with IL‐1ra and lacks the diurnal shift in corticosterone nonstressed levels; this last feature might be related to the expression of RORα in the SCN, a structure that maintains the circadian clock and plays a role in timing rhythmic physiology and behavior. © 2006 Wiley‐Liss, Inc.
Developmental changes in Ca2+‐regulated functions of early postnatal Purkinje neurons
Authors: Gruol D.L. , Quina L.A. , Netzeband J.G. , Nguyen D. , Gullette C.E.
Published: March 2006

Ca2+ influx through L‐type Ca2+ channels regulates several different cellular processes in developing Purkinje neurons, including activation of transcription factors and expression of cellular proteins. In the current studies, we examined the age dependence of these actions of Ca2+ during the early developmental period. Purkinje neurons acutely isolated from postnatal day 4–8 rat pups were studied. We also examined the sensitivity of the Ca2+‐regulated processes to a toxic environmental factor (ethanol) known to show age‐dependent actions on developing Purkinje neurons. Results show that Ca2+ activation of the transcription factor cAMP‐responsive element binding protein (CREB) and Ca2+‐induced alterations in the level of the apoptotic enzyme caspase 3 show both dose and age dependence in the early‐developing Purkinje neurons. Interestingly, the age dependence was opposite for the two proteins. Ca2+ regulation of calbindin, a Ca2+ binding protein, was dose dependent but showed little age dependence. Exposure to ethanol altered Ca2+ activation of pCREB in an age‐dependent manner but did not alter Ca2+ regulation of caspase 3 or calbindin levels. Taken together, these results show that the downstream effects of Ca2+ signaling have age‐dependent components during early Purkinje neuron development. This age dependence may play an important role in the normal developmental program and could contribute to the critical window of sensitivity observed for certain toxic agents during early development. © 2006 Wiley‐Liss, Inc.
Local land use strategies in a globalizing world—managing social and environmental dynamics
Authors: Wadley R. L. , Mertz O. , Christensen A. E.
Published: March 2006

This special issue deals with local rural people's economic, social and cultural responses to external and internal pressures generated by processes of global and regional change. The contributions deal with issues of resource‐base degradation and stable land management, with special emphases on market integration and increased vulnerability of natural resources and local livelihoods in Lao DPR; land‐use change in a Malaysian swidden system under varied patterns of migration and off‐farm labour; occupational multiplicity and agricultural specialization in the Philippines; land degradation and environmental perceptions in peri‐urban Nigeria; food security, gendered labour and shifting cultural‐economic values in Uganda; and the rehabilitation of environment and social institutions through neo‐localism in Thailand. All of the articles were originally presented at an International Conference in Copenhagen, Denmark in 2003, under the auspices of the Danish University Consortium on Environment and Development—Sustainable Land Use and Natural Resource Management (DUCED SLUSE). Copyright © 2006 John Wiley & Sons, Ltd.
Forests, marketization, livelihoods and the poor in the Lao PDR
Authors: Rigg J. D.
Published: March 2006

The Lao PDR is making the transition from subsistence to cash, and command to market. Rural communities are being drawn ever more tightly into the embrace of the market economy and of the central state. The construction of roads, schools and health centres, the provision of credit and new crops and technologies, and the arrival of traders and the panoply of the consumer economy are all, in their different ways, remoulding rural economy and society. This paper looks at one aspect of this multi‐stranded process of agrarian transformation: the role and place of forests and, in particular, non‐timber forest products, in rural people's lives and livelihoods. The paper highlights the contradictory and uneven livelihood‐eroding/enhancing effects of these transformations. In many upland areas of Laos livelihoods are being squeezed from ‘below’ by environmental degradation and from ‘above’ by the operation of government policies and, more generally, by evolving market relations. While market pessimists see market integration as a largely destructive process, the paper highlights the opportunities that market integration can provide through diversification and livelihood reorientation. The challenge is that these opportunities are unequally available and are likely to promote social differentiation. Some households find themselves in a position to embrace new opportunities while others are forced to continue to rely on a declining and degrading forest resource. Copyright © 2006 John Wiley & Sons, Ltd.
Land use and economic change in the post‐frontier upland Philippines
Authors: Eder J. F.
Published: March 2006

Changes in land use and in the nature of farm enterprises in the upland Philippines are examined through the lens of household economic strategies, using data obtained on Palawan Island and with particular attention to non‐agricultural employment diversification. Short fallow intervals and small farm sizes are today common throughout upland Palawan. In addition, as upland farming has become more of an occupation of specific household members and less the way of life of entire households, many upland farms are specialized in particular crops. Such specializations, however, change over time as households undergo growth and domestic cycling and some members establish new income sources and residential bases in the lowlands. Meanwhile, restrictions on new forest clearance and other developments that make it difficult for upland households to secure an adequate living from farming alone have greatly increased collection pressures on non‐timber forest products. These and other changes are reconfiguring the role of women in household economy and generating new axes of regional economic integration. Despite considerable land and other resource degradation in the uplands, some causes for optimism are found in the spontaneous adoption of agroforestry practices and in the emergence of new identities configured in part around notions of environmental well‐being. Copyright © 2006 John Wiley & Sons, Ltd.
Living donor liver transplantation for hepatitis C-related cirrhosis: No difference in histological recurrence when compared to deceased donor liver transplantation recipients
Authors: Guo Linsheng , Orrego Mauricio , Rodriguez-Luna Hector , Balan Vijiyan , Byrne Thomas , Chopra Kapil , Douglas David D. , Harrison Edwyn , Moss Adyr , Reddy Sudhakar K. , Williams James W. , Rakela Jorge , Mulligan David , Vargas Hugo E.
Published: March 2006

The question of possible earlier and more aggressive recurrence of hepatitis C virus (HCV) infection after living donor liver transplantation (LDLT) compared to deceased donor liver transplantation (DDLT) remains unanswered. To address this issue we retrospectively reviewed virological, histological, and clinical data in 67 patients (52 DDLT and 15 LDLT) who underwent liver transplant for their HCV-related cirrhosis since April 2001. Our data indicate that there is no statistical difference between LDLT and DDLT groups in mean age, Child-Turcotte-Pugh score, model for end-stage liver disease score, and gender distribution. The mean follow-up was 749 ± 371 days in LDLT and 692 ± 347 days in DDLT. The predominant genotype in the LDLT and DDLT are genotype 1 (LDLT, 91%; DDLT, 70%). All patients with histologically confirmed recurrent HCV had detectable HCV-RNA in serum. The histological recurrence rate of hepatitis C was 58% at 4 months, 90% at 1 year, and 100% at 2 years in LDLT patients vs. 71% at 4 months, 94% at 1 year, and 95% at 2 years in DDLT patients (not significant) Comparison of the activity of inflammation and fibrosis score at all time points failed to show a statistical difference. Kaplan-Meier survival analysis showed similar patient and graft survival rates between the 2 groups. Our data indicate that histological recurrence of HCV is an early event and virtually universal 2 years’ posttransplantation, regardless of modality of donor procurement.
Liver Transpl 12:560–565, 2006.

© 2006 AASLD.
Syntheses, Structures and Proton Conductivities of Polyphthalazinone Ionomers Derived from a Direct NC Coupling Reaction
Authors: Chen Yulin , Meng Yuezhong , Wang Shuanjin , Tian Shuanghong , Hay Allan S.
Published: March 2006

Summary: Nafion perfluorinated resins that contain perfluorosulfonic acid groups have outstanding properties as membranes in polymer electrolyte membrane (PEM) fuel cells when used only at temperatures lower than 80 °C. At higher temperatures, dehydration of the membrane occurs with a concomitant loss of conductivity. In this paper, we report a new approach to synthesize polyphthalazinone ionomers via an NC coupling reaction. The sulfonated polymers produced showed excellent thermal and oxidative stability because of their specially designed structure. Membranes cast from solution possessed good water affinity and high proton conductivity. Different bisphthalazinone monomers resulted in varying properties of the corresponding polymers. The membranes exhibited excellent resistance both to hydrolysis and oxidation, demonstrating their promising application as proton exchange membranes in PEM fuel cells. The relationship between the structure and properties for the synthesized polymeric ionomers was discussed.

Polyphthalazinone ionomers.

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Polyphthalazinone ionomers.
A Column By‐Pass System and Its Application in High‐Temperature Size‐Exclusion Chromatography
Authors: Aust Nicolai , O'Donohue Stephen , Yakhoul Amjad Jade , Zash Najib
Published: March 2006

Summary: A new by‐pass system for chromatographic columns is presented and its efficiency in detecting disturbances during the chromatographic run is demonstrated. The system, designed for HT SEC, is based on a ten‐port valve and allows by‐passing without the need of time and work consuming replacement of the column by a capillary and vice versa. In addition, the construction guarantees a continuous low flow of eluent through the column also when by‐passed, which helps substantially to prolong lifetime of the SEC column at high temperature. Combining the chromatograph with “absolute” detectors, e.g. a light‐scattering detector or viscometer, erroneous molecular parameters caused by polymer degradation due to wrong column selection or run conditions can be easily detected by comparing measurements with and without the column. Therefore, using the chromatograph in by‐pass mode, it can be regarded as an additional, independent apparatus, delivering e.g. the $\overline M _{\rm w}$ or [η] of a polymer sample. The by‐pass system enables a reliable calibration of concentration detectors in chromatography. With the aid of a detector calibration curve, even a small amount of polymer adsorbed in the SEC column can be detected by comparing the peak area derived from the concentration detector to the one to be expected from the calibration data. The column by‐pass could find application except for HT SEC also in other fields of HPLC.

Scheme of the by‐pass system.

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Scheme of the by‐pass system.
Loss of p75 neurotrophin receptor expression accompanies malignant progression to human and murine retinoblastoma
Authors: Dimaras H. , Coburn B. , Pajovic S. , Gallie B.L.
Published: March 2006

We studied the expression of pro‐apoptotic neurotrophin receptor p75 (p75NTR) in human and murine retinoblastoma, compared to normal retina, and examined changes in p75NTR expression with the onset of apoptosis in the course of murine retinoblastoma progression, using immunohistochemistry and quantitative real‐time RT‐PCR. The murine retinoblastoma is induced by retinal specific expression of SV40 T‐antigen (TAg), which blocks the function of the retinoblastoma protein (pRB) and related proteins, and is a well‐studied model that closely simulates human retinoblastoma. The majority of human retinoblastoma either lacked or expressed decreased levels of p75NTR mRNA, compared to human retina. Moreover, p75NTR protein was not detected in any tumor studied, unlike normal retina. Like human retinoblastoma, advanced murine retinoblastoma did not express p75NTR. However, before tumors emerged, small clusters of TAg‐positive cells coexpressed p75NTR and activated caspase‐3, a marker of apoptosis. Furthermore, in three rare human eyes containing retinoblastoma adjacent to regions resembling the benign retinal tumor retinoma, both normal retina and retinoma‐like tissue expressed p75NTR protein, while the retinoblastoma did not. We suggest that p75NTR loss accompanies progression from retinoma to retinoblastoma. © 2006 Wiley‐Liss, Inc.