bluuebunny/crossref_metadata_2025 huggingface dataset:
The use of the alkane technique to estimate diet selection of sheep grazing grass–clover/heather–gorse vegetation communities
Authors: Ferreira Luis MM , Oliván Mamen , Celaya Rafael , Garcia Urce , Rodrigues Miguel AM , Osoro Koldo
Published: December 2006

The n‐alkane technique was evaluated for estimating the diet composition of sheep grazing in heathlands. Six dietary treatments, composed by different proportions of herbaceous (Lolium perenne and Trifolium repens) and woody species (Erica umbellata, Erica cinerea, Calluna vulgaris and Ulex gallii) were offered to 24 sheep housed in metabolism crates. Diet composition was estimated from alkane concentrations in diet and faeces, by least‐squares procedures, using all available alkanes (C1) from C25 to C33, or only those with higher concentration (C2): C27, C29, C30, C31 and C33. Additionally, the effect of applying mean treatment faecal recoveries (R1), mean faecal recoveries of all experimental diets (R2) or no faecal recovery correction (R3) was studied in both selections of alkanes (C1 and C2). No significant differences were observed between the use of all alkane information (C1) or limited number of alkanes (C2) in the diet composition calculations. There were no significant differences between measured proportions of dietary components and those estimated with procedures R1 and R2. In contrast, the proportions calculated with R3 procedure differed significantly (P < 0.05) from the measured proportions, overestimating feeds with higher content of long chain n‐alkanes. The results indicate that correction of faecal alkane concentrations to allow for incomplete faecal recovery is necessary in order to obtain accurate estimates of diet composition, using mean treatment faecal recoveries (R1) or mean faecal recoveries of all experimental diets (R2). Copyright © 2006 Society of Chemical Industry
Degradation of malathion in aqueous extracts obtained from different developmental stages of asparagus (Asparagus officinalis)
Authors: Talebi Khalil , Shibamoto Takayuki
Published: December 2006

When malathion was incubated in aqueous extracts obtained from 17 vegetables and fruits at pH 7.4 and 37 °C for 4 h, asparagus extract exhibited the highest malathion degradation. The degradation effects of the extracts ranged from 100% (asparagus) to 0.5% (papaya). The highest malathion‐degradation effects obtained from extracts of asparagus at different growing stages incubated at pH 7.4 and 37 °C for 1 h was 94.4 ± 0.45% (stem length, 5–10 cm), followed by 88.0 ± 0.31% (10–15 cm), 85.1 ± 0.94 (15–20 cm), 82.2 ± 0.52 (20–25 cm), 81.2 ± 1.4% (pre‐emergent), 67.3 ± 0.67% (>25 cm), and 42.7 ± 2.1% (fern). The protein content in an asparagus extract from different growing stages was not consistent with the degradation activity of malathion. Results of time course studies on malathion degradation in asparagus extracts from different growing stages yielded half‐life times of malathion degradation ranging from 51.7 min (fern stage) to 17.3 min (stem length, 5–10 cm). Formation of α‐ and β‐malathion mono acids from malathion was detected in an incubated sample by gas chromatography/mass spectrometry. The results support the presence of carboxylesterases in asparagus extracts. Copyright © 2006 Society of Chemical Industry
Global existence and uniform stability of solutions for a quasilinear viscoelastic problem
Authors: Messaoudi Salim A. , Tatar Nasser‐eddine
Published: December 2006

In this paper the nonlinear viscoelastic wave equation in canonical form
equation image
with Dirichlet boundary condition is considered. By introducing a new functional and using the potential well method, we show that the damping induced by the viscoelastic term is enough to ensure global existence and uniform decay of solutions provided that the initial data are in some stable set. Copyright © 2006 John Wiley & Sons, Ltd.
Well‐posedness, smooth dependence and centre manifold reduction for a semilinear hyperbolic system from laser dynamics
Authors: Lichtner Mark , Radziunas Mindaugas , Recke Lutz
Published: December 2006

We prove existence, uniqueness, regularity and smooth dependence of the weak solution on the initial data for a semilinear, first order, dissipative hyperbolic system with discontinuous coefficients. Such hyperbolic systems have successfully been used to model the dynamics of distributed feedback multisection semiconductor lasers. We show that in a function space of continuous functions the weak solutions generate a smooth skew product semiflow. Using slow fast structure and dissipativity we prove the existence of smooth exponentially attracting invariant centre manifolds for the non‐autonomous model. Copyright © 2006 John Wiley & Sons, Ltd.
3D‐based hp‐adaptive first‐order shell finite element for modelling and analysis of complex structures—Part 2: Application to structural analysis
Authors: Zboiński G.
Published: December 2006

The paper presents a 3D‐based adaptive first‐order shell finite element to be applied to hierarchical modelling and adaptive analysis of complex structures. The main feature of the element is that it is equipped with 3D degrees of freedom, while its mechanical model corresponds to classical first‐order shell theory. Other useful features of the element are its modelling and adaptive capabilities. The element is assigned to hierarchical modelling and hpq‐adaptive analysis of shell parts of complex structures consisting of solid, thick‐ and thin‐shell parts, as well as of transition zones, where h, p and q denote the mesh density parameter and the longitudinal and transverse orders of approximation, respectively. The proposed hp‐adaptive first‐order shell element can be joined with 3D‐based hpq‐adaptive hierarchical shell elements or 3D hpp‐adaptive solid elements by means of the family of 3D‐based hpq/hp‐ or hpp/hp‐adaptive transition elements.

The main objective of the first part of our research, presented in the first part of the paper, was to provide non‐standard information on the original parts of the element algorithm. Here we describe the second part of the research, devoted to the methodology and results of the application of the element to various plate and shell problems. The main objective of this part is to verify algorithms of the element and to show its usefulness in modelling and adaptive analysis of shell and plate parts of complex structures. In order to do that, there is a presentation of the results of a comparative analysis of model plate and shell problems using the classical and our elements, and equidistributed and integrated Legendre shape functions. For the plate problem a comparison of the results obtained from the adaptive and non‐adaptive analysis is also included. Additionally, some advantages of the application of our element are shown through a comparative analysis of p‐convergence of the thin plate problem and an adaptive analysis of the exemplary complex structure. Copyright © 2006 John Wiley & Sons, Ltd.
Quantitative structural damage detection using high‐frequency piezoelectric signatures via the reverberation matrix method
Authors: Yan W. , Chen W. Q. , Cai J. B. , Lim C. W.
Published: December 2006

High‐frequency structural analysis so far has been a major issue in dynamic analysis, for which many conventional methods such as finite element method and transfer matrix method are unable to perform well. Since the electromechanical impedance technique for structural health monitoring (SHM) operates at very high frequencies, the reverberation matrix method (RMM), which was just developed a few years ago, is employed to study dynamics of the monitored structures, which are bonded with piezoelectric lead zirconate titanate (PZT) patches. A piecewisely homogeneous Euler–Bernoulli beam model is introduced to approximate the non‐homogeneous beam and only one‐dimensional axial vibration of PZT wafers is considered. The imperfect interfacial bonding between PZT patches and the host beam is investigated based on a shear lag model. Using a hybrid technique combining electromechanical impedance method and RMM, an analytical expression of impedance (or admittance) related to the response of the coupled model of PZT patch‐bonding layer‐host beam system is derived for SHM. The proposed method is examined by comparing with other theoretical methods as well as by means of a test on an intelligent system using a steel beam with two symmetrically installed PZT wafers. It could be further applied to predicting the dynamics of monitored Timoshenko beams, continuous beams, and framed structures as well. Copyright © 2006 John Wiley & Sons, Ltd.
Construction of shape functions for theh‐ andp‐versions of the FEM using tensorial product
Authors: Bittencourt M. L. , Vazquez M. G. , Vazquez T. G.
Published: December 2006

This paper presents an uniform and unified approach to constructh‐ andp‐shape functions for quadrilaterals, triangles, hexahedral and tetrahedral based on the tensorial product of one‐dimensional Lagrange and Jacobi polynomials. The approach uses indices to denote the one‐dimensional polynomials in each tensorization direction. The appropriate manipulation of the indices allows to obtain hierarchical or non‐hierarchical and inter‐elementC0continuous or non‐continuous bases. For the one‐dimensional elements, quadrilaterals, triangles and hexahedral, the optimal weights of the Jacobi polynomials are determined, the sparsity profiles of the local mass and stiffness matrices plotted and the condition numbers calculated. A brief discussion of the use of sum factorization and computational implementation is considered. Copyright © 2006 John Wiley & Sons, Ltd.
Closed‐form minimax time‐delay filters for underdamped systems
Authors: Singh Tarunraj , Muenchhof Marco
Published: December 2006

This paper derives closed‐form solutions for the parameters of a time‐delay filter designed to be robust to uncertainties in frequencies to be cancelled. It is shown that the slope of the magnitude plot of the two time‐delay filter is zero at the nominal frequency indicating that it is a local maximum. This information is used for deriving the solution of the parameters of the time‐delay filter in closed form. Three time‐delay filters are also designed which force a zero of the filter to be located at the nominal frequency of the system. Uniform and non‐uniform distributions of the penalty over the uncertain regions are permitted in this formulation. The applicability of the proposed technique for the control of multi‐mode systems is also illustrated. Copyright © 2006 John Wiley & Sons, Ltd.
Approximate solutions to convex optimization problems under stochastic uncertainty
Authors: Dabbene Fabrizio , Calafiore Giuseppe
Published: December 2006

In this paper, we survey two standard philosophies for finding minimizing solutions of convex objective functions affected by uncertainty. In a first approach, the solution should minimize the expected value of the objective w.r.t. uncertainty (average approach), while in a second one it should minimize the worst‐case objective (worst‐case, or min‐max approach). Both approaches are however numerically hard to solve exactly, for general dependence of the cost function on the uncertain data. Here, a brief account is given on two techniques based on uncertainty randomization that permit to solve efficiently some suitable probabilistic relaxation of the indicated problems, with full generality with respect to the way in which the uncertainty enters the problem data. A specific application to uncertain least‐squares problems is examined. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Numerical Mountain Pass and its Applications
Authors: Horák Jiří , Lord Gabriel J. , Peletier Mark A.
Published: December 2006

The mountain pass theorem is an important tool in the calculus of variations and in finding solutions to nonlinear PDEs in general. The mountain pass structure can be exploited numerically, as well. We explain the main ideas on an example of buckling of a cylindrical shell. First, we prove existence of an MP‐solution for almost all values of a given load parameter. Then, we find a numerical approximation of such a solution. Finally, we compare the results of a numerical continuation in the load parameter with results of physical experiments and make a few comments about further numerical investigations of the problem. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Cell membranes, Lipid Bilayers, and the Elastica Functional
Authors: Röger Matthias , Peletier Mark A.
Published: December 2006

We study an energy functional that arises in a simplified two‐dimensional model for lipid bilayer membranes. We demonstrate that this functional, defined on a class of spatial mass densities, favours concentrations on ‘thin structures’. Stretching, fracture and bending of such structures all carry an energy penalty. In this sense we show that the models captures essential features of lipid bilayers, namely partial localisation and a solid‐like behaviour.

Our findings are made precise in a Gamma‐convergence result. We prove that a rescaled version of the energy functional converges in the ‘zero thickness limit’ to a functional that is defined on a class of planar curves. Finiteness of the limit value enforces both optimal thickness and non‐fracture; if these conditions are met, then the value of this functional is given by the classical Elastica (bending) energy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Constraint Preserving, Inexact Solution of Implicit Discretizations of Landau–Lifshitz–Gilbert Equations and Consequences for Convergence
Authors: Bartels Sören
Published: December 2006

The Landau‐Lifshitz‐Gilbert equation describes dynamics of ferromagnetism. Nonlinearity of the equation and a non‐convex side constraint make it difficult to design reliable approximation schemes. In this paper, we discuss the numerical solution of nonlinear systems of equations resulting from implicit, unconditionally convergent discretizations of the problem. Numerical experiments indicate that finite‐time blow‐up of weak solutions can occur and thereby underline the necessity of the design of reliable discretization schemes that approximate weak solutions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Coupling 3D and 1D fluid‐structure interaction models for blood flow simulations
Authors: Formaggia L. , Moura A. , Nobile F.
Published: December 2006

Three‐dimensional (3D) simulations of blood flow in medium to large vessels are now a common practice. These models consist of the 3D Navier‐Stokes equations for incompressible Newtonian fluids coupled with a model for the vessel wall structure. However, it is still computationally unaffordable to simulate very large sections, let alone the whole, of the human circulatory system with fully 3D fluid‐structure interaction models. Thus truncated 3D regions have to be considered.

Reduced models, one‐dimensional (1D) or zero‐dimensional (0D), can be used to approximate the remaining parts of the cardiovascular system at a low computational cost. These models have a lower level of accuracy, since they describe the evolution of averaged quantities, nevertheless they provide useful information which can be fed to the more complex model. More precisely, the 1D models describe the wave propagation nature of blood flow and coupled with the 3D models can act also as absorbing boundary conditions.

We consider in this work the coupling of a 3D fluid‐structure interaction model with a 1D hyperbolic model. We study the stability of the coupling and present some numerical results. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Remarks on Duality in Graph Spaces of First‐Order Linear Operators
Authors: Jensen Max
Published: December 2006

Graph spaces provide a setting alternative to Sobolev spaces and BV spaces, which is suitable for the analysis of first‐order linear boundary value problems such as Friedrichs systems. Besides investigations of the well‐posedness of the continuous problem there is also an increasing interest in the error analysis of finite element methods within a graph space framework. In this text we elucidate various methods for an explicit representation of dual spaces of graph spaces. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Wavelet‐based Adaptive Grids for the Simulation of Multirate Partial Differential‐Algebraic Equations
Authors: Bartel Andreas , Knorr Stephanie
Published: December 2006

We present an adaptive method to solve biperiodic problems in chip design with widely separated time scales and steep gradients due to digital‐like signal structures. Motivated from the example of the switched capacitor filter, we explain the multidimensional signal model and the transformation of network equations to the hyperbolic multirate differential‐algebraic system. Then adapted hat‐wavelets are introduced to detect the steep gradients. In this way, an adaptive grid is defined for the efficient application of a finite difference method to solve the limit cycle problem. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A Quadratic Eigenproblem in the Analysis of a Time Delay System
Authors: Jarlebring Elias
Published: December 2006

In this work we solve a quadratic eigenvalue problem occurring in a method to compute the set of delays of a linear time delay system (TDS) such that the system has an imaginary eigenvalue. The computationally dominating part of the method is to find all eigenvalues z of modulus one of the quadratic eigenvalue problem

equation image

where φ 1, …, φ m –1 ∈ ℝ are free parameters and u a vectorization of a Hermitian rank one matrix.

Because of its origin in the vectorization of a Lyapunov type matrix equation, the quadratic eigenvalue problem is, even for moderate size problems, of very large size. We show one way to treat this problem by exploiting the Lyapunov type structure of the quadratic eigenvalue problem when constructing an iterative solver. More precisely, we show that the shift‐invert operation for the companion form of the quadratic eigenvalue problem can be efficiently computed by solving a Sylvester equation. The usefulness of this exploitation is demonstrated with an example. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structured Condition Numbers of Multiple Eigenvalues
Authors: José Peláez María , Moro Julio
Published: December 2006

We analyze the influence of matrix structure on the condition number of multiple, possibly defective eigenvalues. We show that the structured and unstructured Hölder condition numbers coincide for multiple eigenvalues of matrices belonging to certain classes of structured matrices, which can be characterized as either Jordan or Lie Algebras. We do this by explicitly finding a specific perturbation matrix, analogous to the classical Wilkinson perturbation, which attains the maximal variation within the class of structured matrices. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Micromechanics‐Supported Conversion of Computer Tomographic (CT) Images into Anisotropic and Inhomogeneous Finite Element Models of Organs: the Case of a Human Mandible
Authors: Hellmich Christian , Kober Cornelia
Published: December 2006

We here present a strategy for reliable prediction of elastic properties from X‐ray attenuation coefficients visualized in Computer Tomographic images, as basis for Finite Element models. By example, we show the distribution of the axial normal stress throughout a human mandible, due to a bite on the leftmost premolar. Remarkably, this distribution is not heavily altered if we replace the inhomogeneous material distribution by one discerning merely cortical and trabecular bone, but it is strongly affected by the consideration of material anisotropy. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Homogenization approach to the multi‐compartment model of perfusion
Authors: Rohan Eduard
Published: December 2006

The paper deals with modelling of the coupled diffusion‐deformation processes in biological tissues with potential applications in describing the blood perfusion, or fluid filtration phenomena in general. The micromodel to be homogenized is based on the Biot type model for the incompressible medium. Due to the strong heterogeneity in the permeability coefficients associated with three compartments of the representative microstructural cell (RMC), the homogenization of the model leads to the double diffusion phenomena. The resulting homogenized equations, involving the stress‐equilibrium equation and other two equations governing the mass redistribution, describe the parallel diffusion in two high‐conducting compartments (arterial and venous sectors) separated by the low conducting matrix which represents the perfused tissue. To obtain the homogenized model, the method of two scale convergence is applied. The homogenized coefficients are defined in terms of the characteristic response of the RMC. It is possible to identify the instantaneous and fading memory viscoelastic coefficients; other effective parameters, controlling the fluid redistribution between the compartments, are involved also in time convolutions. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Prediction of diffusion length in multicrystalline silicon solar cells from trapping images on starting material
Authors: Schubert Martin C. , Warta Wilhelm
Published: December 2006

Areas with high crystal defect density are known to have a strong impact on the performance of silicon solar cells. Trapping has been reported to be correlated with crystal defects. We compare spatially resolved measurements of the trapping effect on unprocessed wafers with diffusion length measurements on solar cells. An excellent correlation is found between these two measurements. This allows a prediction of diffusion length for the processed solar cell directly from the trap image, for a given cell process and comparable material. This technique has thus a great potential for inline process control of starting material in solar cell production. Copyright © 2006 John Wiley & Sons, Ltd.
Synthesis and properties of novel poly(arylene ether)s and poly(arylene thioether)s based on a pyridazine biphenol or a phthalazine biphenol
Authors: Xu J. , Meng Y. Z. , Wang S. J. , Hay A. S.
Published: December 2006

Novel sulfur‐containing biphenol monomers were prepared in high yields by the reaction of 4‐mercaptophenol with chloropyridazine or chlorophthalazine compounds. High‐molecular‐weight poly(arylene ether)s were synthesized by a nucleophilic substitution reaction between these sulfur‐containing monomers and activated difluoro aromatic compounds. The inherent viscosities of these polymers ranged from 0.34 to 0.93 dL/g. The poly(pyridazine)s exhibited glass‐transition temperatures greater than 165 °C. The poly(phthalazine)s showed higher glass‐transition temperatures than the poly(pyridazine)s. A polymer synthesized from a bisphthalazinebiphenol and bis(4‐fluorophenyl)sulfone had the highest glass‐transition temperature (240 °C). The thermal stabilities of the poly(pyridazine)s and poly(phthalazine)s showed similar patterns of decomposition, with no significant weight loss below 390 °C. The poly(phthalazine)s were soluble in chlorinated solvents such as chloroform, and the poly(pyridazine)s were soluble in dipolar aprotic solvents such as N,N′‐dimethylacetamide. The soluble poly(pyridazine)s and poly(phthalazine)s could be cast into flexible films from solution. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 262–268, 2007
Luminescent copolyethers containing isolated 1,4‐distyrylbenzene derivatives backbone and 7‐oxy‐4‐methylcoumarin side group: Synthesis and characterization
Authors: Tsai Cheng‐Jang , Yeh Kun‐Ming , Chen Yun
Published: December 2006

Four new copolyethers (P1–P4) consisting of two isolated emitting chromophores [2,5‐dihexyloxy‐1,4‐distyrylbenzene (HODSB) and 2,5‐dihexyloxy‐1,4‐di(4‐methylenestyryl)benzene (HOMDSB) for P1 and P2, 2,5‐dihexyl‐1,4‐distyrylbenzene (HDSB) and HOMDSB for P3 and P4] in the backbone, in which P2 and P4 further contain electron‐transporting chromophores [7‐oxy‐4‐methylcoumarin (OMC)] in the side chain, were successfully prepared by the Heck coupling reaction. The photoluminescence spectra and quantum yields of the copolymers depended mainly on compositions of the isolated fluorophores. Their highest occupied molecular orbital and lowest unoccupied molecular orbital energy levels were estimated from their cyclic voltammograms. Electrochemical investigations proved that the oxidation started at hole‐transporting DSB segments, whereas reduction began at electron‐transporting OMC groups in P2 and P4. The electron affinity of P2 and P4 was enhanced by introducing electron‐transporting OMC chromophores. Double‐layer light‐emitting diodes (ITO/PEDOT:PSS/polymer/Al) of P1 and P2 revealed green electroluminescence, and those of P3 and P4 emitted blue light. Moreover, incorporation of OMC side groups effectively reduced turn‐on electric field and enhanced luminance efficiency of the EL devices due to increased electron affinity. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 211–221, 2007
Phase separation and polymer crystallization in a poly(4‐methyl‐1‐pentene)–dioctylsebacate–dimethylphthalate system via thermally induced phase separation
Authors: Tao Haijun , Zhang Jun , Wang Xiaolin , Gao Jiali
Published: December 2006

The effects of the polymer concentration and quenching temperature on the phase separation, the membrane morphology and polymer crystallization behavior in a poly(4‐methyl‐1‐pentene) (TPX)‐dioctylsebacate (DOS)‐dimethylphthalate (DMP) system via thermally induced phase separation were studied with a pseudobinary phase diagram, with the weight ratio of DOS:DMP = 1:1. SEM was used to observe the membrane morphology and structure, whereas the TPX crystallization behavior was studied with DSC and WAXD. Liquid‐liquid phase separation occurred, although quenching under the crystallization temperature. As the quenching temperature decreased, the pore size decreased, with better connected pore structure formed. The membranes quenched at 333 and 363 K showed good cellular structures, with an average pore size of about 2.3μm, whereas the pores of the membranes quenched at 393 and 423 K were not well formed, with some lamellar crystals on the inner side. The diluent assisted the mobility of the polymer chain, which improved the polymer crystallization. Dual‐melting‐peak behavior occurred for all the samples studied here. As the quenching temperature increased, the first peak of the melting trace moved to a higher temperature, whereas the second one stayed almost the same. The flexibility of the TPX main chain was restricted by the side groups, which allowed liquid‐liquid phase separation to occur first when quenched below the equilibrium crystallization temperature. This allowed primary and secondary crystallization, which was responsible for the dual‐melting‐peak behavior. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 45: 153–161, 2007
Antiinflammatory activity of ethanol extracts of Hypericum perforatum L., H. barbatum Jacq., H. hirsutum L., H. richeri Vill. and H. androsaemum L. in rats
Authors: Šavikin Katarina , Dobrić Silva , Tadić Vanja , Zdunić Gordana
Published: December 2006

Ethanol extracts of the aerial parts of six Hypericum species, H. barbatum, H. androsaemum, H. richerii, H. hirsutum, H. perforatum and H. perforatum cultivated on mountain Tara were tested for antiinflammatory activity in comparison with indomethacin (IND) using the carrageenan‐induced rat paw edema test. It was found that all examined extracts produced antiinflammatory activity, particularly those from H. hirsutum, and both wild and cultivated H. perforatum. A dose‐dependent antiinflammatory effect was especially pronounced in extracts showing some lower antiinflammatory activity. There was no correlation between the amount of hypericin in the extracts and their antiinflammatory activity. Copyright © 2006 John Wiley & Sons, Ltd.
NKCC1 activity modulates formation of functional inhibitory synapses in cultured neocortical neurons
Authors: Nakanishi Keiko , Yamada Junko , Takayama Chitoshi , Oohira Atsuhiko , Fukuda Atsuo
Published: December 2006

Intracellular Cl− concentration ([Cl−]i) in immature neurons is higher than that expected for a passive distribution, therefore the equilibrium potential for chloride is more positive than the resting membrane potential, and the resulting GABA renders immature neurons depolarization. The higher [Cl−]i in immature neurons is thought to be attributed to the uptake of Cl− mediated by NKCC1 (Na+, K+‐2Cl− cotransporter). Thus, a dysfunction of this transporter could affect synaptic development through a GABAA receptor‐mediated pathway. To test this possibility, we examined the effects of a Cl−‐uptake inhibitor on the development of synaptic activities of rat neocortical neurons in culture. Chronic treatment with bumetanide at 10 μM during the culture diminished the amplitude of synaptically‐driven rhythmic depolarizing potentials (RDPs) in neurons and also decreased the frequency of spontaneous inhibitory postsynaptic currents (sIPSCs) but not of spontaneous excitatory postsynaptic currents (sEPSCs). Chronic treatment with bumetanide decreased vesicular GABA transporter (VGAT)‐immunopositive particles without affecting paired‐pulse ratio of evoked IPSCs (eIPSCs), indicating decrease in the number of functional GABAergic synapses. Acute treatment with bumetanide (10 μM) decreased neuronal [Cl−]i, the amplitude of RDPs, and neuronal excitability, while bumetanide had no effect on RDPs and neuronal excitability in the presence of bicuculline. These results suggest that the uptake of Cl− by NKCC1 affects the development of inhibitory synapses by promoting a depolarizing GABA‐mediated response. Synapse 61:138–149, 2007. © 2006 Wiley‐Liss, Inc.
Acute sublethal global hypoxia induces transient increase of GAP‐43 immunoreactivity in the striatum of neonatal rats
Authors: Valdez Susana R. , Patterson Sean I. , Ezquer Marcelo E. , Torrecilla Mariana , Lama M. Cristina , Seltzer Alicia M.
Published: December 2006

We assessed immunoreactivity (IR) in the cerebral cortex (CC), hippocampus (Hipp), and striatum (ST) of a growth‐associated protein, GAP‐43, and of proteins of the synaptic vesicle fusion complex: VAMP‐2, Syntaxin‐1, and SNAP‐25 (SNARE proteins) throughout postnatal development of rats after submitting the animals to acute global postnatal hypoxia (6.5% O2, 70 min) at postnatal day 4 (PND4). In the CC only the IR of the SNARE protein SNAP‐25 increased significantly with age. The hypoxic animals showed the same pattern of IR for SNAP‐25, although with lower levels at PND11, and also a significant increase of VAMP‐2. SNAP‐25 (control): PND11 P < 0.001 vs. PND18, 25, and 40, SNAP‐25 (hypoxic): P < 0.001 vs. PND18, 25, and 40; VAMP‐2 (hypoxic): P < 0.05 PND11 vs. PND18, and P < 0.01 vs. PND25 and PND40; one‐way ANOVA and Bonferroni post‐test. In the Hipp, SNAP‐25 and syntaxin‐1 increased significantly with age, reaching a plateau at PND25 through PND40 in control animals (one‐way ANOVA: syntaxin‐1: P = 0.043; Bonferroni: NS; SNAP‐25: P = 0.013; Bonferroni: P < 0.01 PND11 vs. PND40). Hypoxic rats showed higher levels of significance in the one‐way ANOVA than controls (syntaxin‐1: P = 0.009; Bonferroni: P < 0.05 PND11 vs. PND25 and P < 0.001 PND11 vs. PND40). In the ST, GAP‐43 differed significantly among hypoxic and control animals and the two‐way ANOVA revealed significant differences with age (F = 3.23; P = 0.037) and treatment (F = 4.84; P = 0.036). VAMP‐2 expression also reached statistical significance when comparing control and treated animals (F = 6.25, P = 0.018) without changes regarding to age. Elevated plus maze test performed at PND40 indicated a lower level of anxiety in the hypoxic animals. At adulthood (12 weeks) learning, memory and locomotor abilities were identical in both groups of animals. With these results, we demonstrate that proteins of the presynaptic structures of the ST are sensitive to acute disruption of homeostatic conditions, such as a temporary decrease of the O2 concentration. Modifications in the activity of these proteins could contribute to the long term altered responses to stress due to acute hypoxic insult in the neonatal period. Synapse 61:124–137, 2007. © 2006 Wiley‐Liss, Inc.
Glutamate receptors in nucleus accumbens mediate regionally selective increases in cortical acetylcholine release
Authors: Zmarowski Amy , Sarter Martin , Bruno John P.
Published: December 2006

The basal forebrain cortical cholinergic system (BFCS) is critical for the regulation of attentional information processing. BFCS activity is regulated by several cortical and subcortical structures, including the nucleus accumbens (NAC) and prefrontal cortex (PFC). GABAergic projection neurons from NAC to basal forebrain are modulated by Glu receptors within NAC. We previously reported that intra‐NAC perfusions of NMDA or its antagonist CPP stimulate ACh release in PFC. In this experiment we determined whether this trans‐synaptic modulation of cortical ACh release is evident in multi‐sensory associational areas like the posterior parietal cortex (PPC). Artificial cerebrospinal fluid (aCSF, control), NMDA (250 or 400 μM), or CPP (200 or 400 μM) were perfused into the NAC shell and ACh was measured in the ipsilateral PPC. Amphetamine (2.0 mg/kg, i.p), was systemically administered as a positive control in a fourth session, since it also stimulates cortical ACh release but via mechanisms known to not necessitate transmission within the NAC. Neither NMDA nor CPP increased ACh efflux in the PPC, yet both drugs increased ACh release in PFC, suggesting that NMDA receptor modulation in the NAC increases ACh in the cortex in a regionally‐specific manner. Systemic amphetamine administration significantly increased (100–200%) ACh in the PPC, suggesting that levels of ACh in the PPC can be increased following certain pharmacological manipulations. The cortical region‐specific modulation of ACh by NAC may underlie the linkage of motivational information with top‐down controls of attention as well as guide appropriate motor output following exposure to salient and behaviorally relevant stimuli. Synapse 61:115–123, 2007. © 2006 Wiley‐Liss, Inc.
Seasonal patterns of egg production in field colonies of the termite Reticulitermes speratus (Isoptera: Rhinotermitidae)
Authors: Matsuura Kenji , Kobayashi Norimasa , Yashiro Toshihisa
Published: December 2006

This is the first report on the annual egg production patterns in mature termite colonies in the field. Data on the seasonal patterns of egg production in field colonies are very important for understanding the annual colony growth schedule, resource allocation, and population dynamics of the termites. However, collecting the eggs from a sufficient number of colonies is extremely difficult in Reticulitermes termites because their multiple‐site nesting makes it difficult to find the reproductive center of the colonies. Here, we first show the seasonal pattern of egg production in the subterranean termite Reticulitermes speratus by collecting the reproductive center of ten colonies each month from April through October. We had to destructively examine dozens of nests to find eggs from enough field colonies each month. Mature field colonies began to produce eggs in late May, soon after the swarming season, and the egg production rate (EPR) reached its maximum in early July. The eggs hatched until late October. The EPR was significantly correlated with the average monthly temperature. Additional investigation of the egg distributions in the nests showed that most eggs were kept around the royal cell, which contained the reproductives. The largest colony had 109 supplemental queens and 94,023 eggs, suggesting that each queen produced an average of 24.7 eggs per day, based on the known mean hatching period of an inseminated egg of 34.95±0.12 (SE) days.
Morphological differences between guinea pig aortic and venous endothelial cells in situ
Authors: Katoh Kazuo , Kano Yumiko , Ookawara Shigeo
Published: December 2006

Endothelial cells (ECs) respond to fluid shear stress. They reveal shear stress related morphological changes in both their cell shape and cytoskeletal organization. Little is known about the cytoskeletal organization of ECs in situ. We studied, together with the living ultrasound high resolution imaging system, the distribution of stress fibers (SFs), certain focal adhesion (FA) and signal transduction associated proteins in guinea pig aortic and venous ECs. Although SFs present in the basal portion of venous ECs ran along the direction of the blood flow, their size was smaller and their number was fewer than those of aortic ECs. Venous ECs were elongated to the direction of flow than in aortic ECs exposed over normal shear stress (SS). Since fluid SS in the vein is low, a sustained and uni‐directional low SS over a long period might thus cause these structural features observed in venous ECs.
Effect of nitric oxide on phagocytic activity of lipopolysaccharide‐induced macrophages: Possible role of exogenous l‐arginine
Authors: Tümer Cemil , Bilgin Hakkı Murat , Obay Basra Deniz , Diken Hüda , Atmaca Mukadder , Kelle Mustafa
Published: December 2006

Among the antimicrobial mechanisms associated with macrophages, NO produced by iNOS plays a major role in intracellular killing, but the relationship between NO and phagocytic activity after injection of inflammatory agents into the peritoneal cavity is not clear. The aim of the present study was to investigate the effect of nitric oxide (NO) on macrophage function after treatment with intraperitoneal lipopolysaccharide (LPS) and the role of exogenous l‐arginine administration in this event. Six experimental groups and one control group, each consisting of seven Wistar rats were used: Group I: Control; Group II: LPS; Group III: LPS + l‐arginine; Group IV: LPS + l‐arginine + Aminoguanidine; Group V: LPS + Aminoguanidine; Group VI: l‐arginine; Group VII: Aminoguanidine. Macrophage phagocytic activity and total plasma nitrite levels were increased in the LPS group. In the LPS + l‐arginine group, both the phagocytic activity and total plasma nitrite levels showed large increases. Administration of aminoguanidine (AG), a specific iNOS inhibitor, abolished macrophage phagocytic activity and total plasma nitrite levels in the LPS and LPS + l‐arginine groups. As a result, we showed that NO produced by macrophages has a role not only in intracellular killing, but also in phagocytic activity.
The effect of age on the structure and composition of rat tendon fibrocartilage
Authors: Esquisatto M.A.M. , Joazeiro P.P. , Pimentel E.R. , Gomes L.
Published: December 2006

Biochemical and morphological aspects of fibrocartilages of calcaneal and deep digital flexor tendons in rats aged 30, 180 and 730 days were analyzed. In both tendons a stronger staining with Alcian blue, indicating the presence of proteoglycans, was detected in rats of 30 and 180 days. In animals 730 days old, it was restricted to the pericellular area. Ultrastructural analysis showed a more prominent pericellular matrix in calcaneal tendon compared to the deep digital flexor tendon. The biochemical analysis showed higher levels of proteins and glycosaminoglycans in the calcaneal tendon of 30‐day‐old rats compared to older rats. In the deep digital flexor tendon, no significant differences were observed between ages. The small proteoglycan, fibromodulin, was detected in both tendons of all ages, but in young rats it appeared to be running as a 210 kDa component, probably due to the association with collagen chains or self‐association.
BLOOD ENEMIES: EXPLOITATION AND URBAN CITIZENSHIP IN THE NATIONALIST POLITICAL THOUGHT OF TANZANIA, 1958–75
Authors: BRENNAN JAMES R.
Published: December 2006

The major concepts of nationalist political thought in Tanzania formed at the meeting point between local and international understandings of exploitation, and prescriptions for its removal. These ideas were given social form through a politics of enmity concerned with defining enemies of the nation and creating corresponding purge categories. Acquiring urban citizenship in Tanzania required the demonstrated commitment to fight exploitation for a party and state hostile to urban growth. While such ideas formed the boundaries of legitimate political debate, Africans struggling to lay claim to urban life appropriated nationalist idioms to lampoon official pieties and make sense of class differentiation in a socialist country.
ELITE WOMEN IN THE KINGDOM OF KONGO: HISTORICAL PERSPECTIVES ON WOMEN'S POLITICAL POWER
Authors: THORNTON JOHN K.
Published: December 2006

Discussions of women’s power in Africa often focus on how much the role of senior women is symbolic and how much is real. Studying the Kingdom of Kongo reveals that in the sixteenth and seventeenth centuries women initially exercised power indirectly through influence on male relatives. However, following the beginning of the civil war after 1665 women began to exercise more open and overt power, taking effective control of some sections of the country and working less through male relatives. However, elite Kongo women never took formal control of the state as they did in Ndongo and Matamba.
THE MODERN GIRL AND RACIAL RESPECTABILITY IN 1930S SOUTH AFRICA
Authors: THOMAS LYNN M.
Published: December 2006

This essay rethinks the gender history and historiography of interwar sub-Saharan Africa by deploying the heuristic device of the ‘modern girl’ to consider how global circuits of representation and commerce informed this period of gender tumult. This device has been developed by a research group at the University of Washington to understand the global emergence during the 1920s and 1930s of female figures identified by their cosmopolitan look, their explicit eroticism and their use of specific commodities. Previous scholarship has suggested that a black modern girl imbricated in international circuits of images, ideologies and commodities only became visible in southern Africa in the post-Second World War period. Yet, analysis of the black newspaper Bantu World reveals the emergence of such a figure by the early 1930s. The modern girl heuristic helps to situate race as a key category of analysis in scholarship on women and gender in interwar Africa as contemporaries consistently debated her in racial terms. In South Africa, some social observers saw African young women’s school education, professional careers and cosmopolitan look as contributing to ‘racial uplift’. Others accused the African modern girl of ‘prostituting’ her sex and race by imitating white, coloured or Indian women, and by delaying or avoiding marriage, dressing provocatively and engaging in premarital and inter-racial sex. Cosmetics use was one of the most contentious issues surrounding the black modern girl because it drew attention to the phenotypic dimensions of racial distinctions. By analysing a beauty contest in Bantu World together with articles and letters on, and advertisements for, cosmetics, this essay demonstrates how, in white-dominated segregationist South Africa, the modern girl emerged through and posed challenges to categories of race and respectability.
Sino-nasal assessment questionnaire: a specific outcome measure for rhinosinusitis, but what is the range in the asymptomatic population?
Authors: Younis F , Duvvi S , Walker T , Kumar B Nirmal
Published: December 2006

The sino-nasal assessment questionnaire is a system used for scoring the symptoms of chronic rhinosinusitis. However, the range of scores for this questionnaire in the healthy adult population is unknown. We aimed to establish this by recruiting 100 healthy volunteers and comparing their sino-nasal assessment questionnaire scores with those of 100 individuals who had undergone sinus surgery for rhinosinusitis. The difference in mean scores in the symptomatic group (44.62) and the asymptomatic group (8.46) was statistically significant. However, there was substantial overlap between the scores of the two groups. Factors such as age, gender and smoking did not have a statistically significant impact on the eventual score in the asymptomatic group. We believe that symptom scores can only be used effectively when the range in the asymptomatic population is known. This is so that disease severity can be gauged in the context of the normal population and post-operative improvements can be forecast.
Traumatic facial nerve neuroma following mastoid surgery: a case report and literature review
Authors: Rainsbury J W , Whiteside O J H , Bottrill I D
Published: December 2006

Traumatic facial nerve neuroma is rare. There are only 10 reported cases in the literature, caused either by physical trauma or chronic inflammation. Traumatic facial neuromata differ from true facial nerve neoplasms in radiological, macroscopic and microscopic appearance, but clinical presentation is less reliable in differentiating the two. Management depends on the pre-operative grade of facial palsy, as this is a benign condition and surgical management carries a risk of further affecting facial nerve function. We present a further case of traumatic facial nerve neuroma following surgery for cholesteatoma. We also review the literature and discuss the management of this condition.
Patterns of presentation and diagnosis of patients with Wegener's granulomatosis: ENT aspects
Authors: Srouji I A , Andrews P , Edwards C , Lund V J
Published: December 2006

Design: a cross-sectional study.

Participants: One hundred and ninety-nine patients with Wegener's granulomatosis belonging to a patient self-help group.

Main outcome measures: Mode of initial presentation; diagnosis timescales and delay; rhinologic involvement; and treatment.

Results: Sixty-three per cent of patients initially presented with ENT-related symptoms. Ninety-two per cent faced a delay in their diagnosis of more than one month, a pattern which has not improved over the last few decades and which compares unfavourably with North American figures. Rhinologic and otologic symptoms are a common occurrence in up to 85 and 50 per cent of Wegener's granulomatosis patients, respectively, attracting varying degrees of targeted treatment.

Conclusions: As sinonasal and other ENT symptoms are so common at the presentation of Wegener's granulomatosis, it is clear that the otolaryngologist has an important role in its diagnosis and treatment. There are long delays in the diagnosis and possible under-treatment of the ENT symptoms of this condition, highlighting the need for greater awareness, particularly in the ENT community.
Common carotid artery pseudoaneurysm after neck dissection: colour Doppler ultrasound and multidetector computed tomography findings
Authors: Flor N , Sardanelli F , Ghilardi G , Tentori A , Franceschelli G , Felisati G , Cornalba G P
Published: December 2006

Common carotid artery pseudoaneurysm is a rare disease, which has been previously unreported in association with neck dissection. We describe the Doppler ultrasound and multidetector computed tomography (CT) findings of a case of carotid pseudoaneurysm, one month after pharyngolaryngectomy with bilateral neck dissection. Multidetector CT confirmed the diagnosis made on the basis of Doppler ultrasound; the high image quality of axial and three-dimensional reconstructions avoided the need for pre-operative conventional angiography. In the presence of a pulsatile cervical mass after neck surgery, pseudoaneurysm of the carotid artery should be included in the differential diagnosis, and multidetector CT can be the sole pre-operative diagnostic imaging modality.