bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural characterization reveals that a PilZ domain protein undergoes substantial conformational change upon binding to cyclic dimeric guanosine monophosphate
Authors: Shin Jae‐Sun , Ryu Kyoung‐Seok , Ko Junsang , Lee Arum , Choi Byong‐Seok
Published: November 2010

PA4608 is a single PilZ domain protein from Pseudomonas aeruginosa that binds to cyclic dimeric guanosine monophosphate (c‐di‐GMP). Although the monomeric structure of unbound PA4608 has been studied in detail, the molecular details of c‐di‐GMP binding to this protein are still uncharacterized. Hence, we determined the solution structure of c‐di‐GMP bound PA4608. We found that PA4608 undergoes conformational changes to expose the c‐di‐GMP binding site by ejection of the C‐terminal 310 helix. A dislocation of the C‐terminal tail in the presence of c‐di‐GMP implies that this region acts as a lid that alternately covers and exposes the hydrophobic surface of the binding site. In addition, mutagenesis and NOE data for PA4608 revealed that conserved residues are in contact with the c‐di‐GMP molecule. The unique structural characteristics of PA4608, including its monomeric state and its ligand binding characteristics, yield insight into its function as a c‐di‐GMP receptor.
Optical and scintillation properties of Pr3+‐doped Ca3(BO3)2 single crystals
Authors: Fujimoto Y. , Yanagida T. , Yokota Y. , Kawaguchi N. , Fukuda K. , Totsuka D. , Watanabe K. , Yamazaki A. , Chani V. , Yoshikawa A.
Published: November 2010

Optical and scintillation properties of Pr3+‐activated Ca3(BO3)2 (CBO) single crystals for neutron scintillator applications were examined. The crystals were grown by the micro‐pulling down (µ‐PD) method. In transmittance spectra, two absorption lines at 210 and 245 nm were observed and they were identified as Pr3+ transition from the ground state 3H to 5d state. The both of photo‐ and radio‐luminescence spectra of Pr3+‐doped CBO crystals demonstrated intense peak at 260 and 310 nm which was ascribed to the transition from the lowest 5d excited state to the 4f ground state levels of 3H. The main decay component was about 16–17 ns under 245 nm excitation wavelength. The relative scintillation light yield of 1.0% Pr3+‐doped CBO was about 90% when compared with that of reference Li‐glass scintillator (GS20) under 241Am 5.5 MeV α‐ray excitation, while that measured under 252Cf neutron irradiation was about 20%. It was concluded that this difference originated from the difference of energy released from the neutron reactions.
First‐principles calculation of vibrational properties of B12As2 crystal
Authors: Fan Zhaochuan , Wang Bin , Xu Xiaoxuan , Cao Xuewei , Wang Yufang
Published: November 2010

We use density functional perturbation theory (DFPT) to simulate the 26 vibrational modes of B12As2 crystal at the Γ point. All the 12 Raman‐active modes are in good agreement with experimental Raman spectra of B12As2. We explain several controversial modes of the past, such as the predicted Raman‐active mode with a low frequency and the Raman‐active mode at 503 cm−1. We also plot the dispersion curves of B12As2 from Brillouin zone center to Z (0.5, 0.5, 0.5) and to A (0.5, 0.0, 0.0). We determine the acoustic branch speeds to be in the range 9850–10 980 m/s for LA and 6940–7220 m/s for TA modes. Finally, we give the predicted physical properties, including the phonon entropy, the phonon heat capacity, elastic constants, and bulk modulus.
First‐principles study on the electronic structure of dilute magnetic semiconductor Ga1−xCrxP in zinc‐blende phase
Authors: Huang H. M. , Luo S. J. , Yao K. L.
Published: November 2010

We employ the full potential linearized augmented plane wave (FP‐LAPW) method based on spin‐polarized density functional theory (DFT) in order to investigate the structural, electronic, and magnetic properties of ordered dilute magnetic semiconductor (DMS) Ga1−xCrxP in zinc‐blende phase. The calculated electronic band structures and density of states of these DMSs are discussed. The results show that the ferromagnetic states are more favorable in energy than antiferromagnetic states. Ga1−xCrxP for x = 0.125, 0.25, and 0.50 exhibits half‐metallic (HM) characteristic with integral magnetic moment, and the sensitivity of half‐metallicity of Ga1−xCrxP as a function of lattice constant is also discussed.
Calculation of dissociation constants and chemical hardness of some biologically important molecules: A theoretical study
Authors: Vyas Nidhi , Ojha Animesh K.
Published: November 2010

The gas‐phase geometries of neutral, protonated, and deprotonated forms of some biologically important molecules, alanine (Ala), glycine (Gly), phenylalanine (Phe), and tyrosine (Tyr), were optimized using density functional theory at B3LYP/6‐311++G(d) and the ab initio HF/6‐311++G(d) level of theories. The neutral and different stable ionic states of Ala, Gly, Phe, and Tyr have also been solvated in aqueous medium using polarizable continuum model for the determination of solvation free energies in the aqueous solution. The gas‐phase acidity constants of above four molecules have been also calculated at both levels of theories and found that the values calculated at HF/6‐311++G(d) method are in good agreement with experimental results. A thermodynamic cycle was used to determine the solvation free energies for the proton dissociation process in aqueous solution and the corresponding pKa values of these molecules. The pKa values calculated at B3LYP/6‐311++G(d) method are well supported by the experimental data with a mean absolute deviation 0.12 pKa units. Additionally, the chemical hardness and the ionization potential (IP) for these molecules have been also explored at both the level of theories. The Tyr has less value of chemical hardness and IP at both levels of theories compared with other three molecules, Ala, Gly, and Phe. The calculated values of chemical hardness and IP are decreasing gradually with the substitution of the various functional groups in the side chain of the amino acids. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Prediction of microscopic protonation constants of polybasic molecules via computational methods: A complete microequilibrium analysis of spermine
Authors: Salehzadeh Sadegh , Gholiee Yasin , Bayat Mehdi
Published: November 2010

For the first time, a simple methodology is reported for theoretical calculation of microscopic protonation constants of polybasic molecules in solution. Density functional theory study was used for complete microequilibrium analysis of spermine, H2N(CH2)3NH(CH2)4NH(CH2)3NH2, a linear tetraamine with 16 known microspecies. A general thermodynamic cycle is proposed to calculate protonation microconstants of polybasic molecules using calculated micro‐ΔG values in aqueous solution. The microscopic protonation constants were determined with considering both the most abundant and most stable conformers for all microspecies. The results show that the microscopic protonation constants derived from the most abundant conformers (i.e., linear conformers in which the intramolecular hydrogen bonding does not exist) are in good agreement with the corresponding available experimental data. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
Theoretical investigations on the weak nonbonded CS···CH2 interactions: Chalcogen‐bonded complexes with singlet carbene as an electron donor
Authors: Zhao Qiang , Feng Dacheng , Sun Youmin , Hao Jingcheng , Cai Zhengting
Published: November 2010

In this article, we explored the noncovalent bonding interactions between OCS, SCS, F2CS, Cl2CS, and singlet carbene. Six chalcogen‐bonded complexes were obtained. It is found that all the vibrational frequencies of CS bond presented a red shift character. Interaction energy, topology property of the electron density and its Laplacian, and the donor–acceptor interaction have been investigated. All these results show that there exists a weak nonbonded interaction between the chalcogen bond donor and CH2. An energy decomposition analysis was performed to disclose that the electrostatic interaction is the main stabilized factor in these nonbonded complexes. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011
In‐gel protein N‐ and C‐termini identification and its application for transgenic protein characterization
Authors: Xiang Bosong , Macisaac Susan , Lardizabal Kathryn , Li Bin
Published: November 2010

A new method for the determination of N‐ and C‐termini of a protein isolated in a polyacrylamide gel is introduced. In‐gel partial protein hydrolysis by hydrochloric acid is used to generate N‐ and C‐terminal peptides for identification. This new method is complementary to existing techniques. The application of the in‐gel protein termini identification technique to the characterization of the transgenic protein diacylglycerol acyltransferase (UrDGAT2A) purified from soybean seeds is also reported here. Both N‐ and C‐termini of UrDGAT2A were successfully identified and the N‐terminus was found to be blocked by acetylation. The analysis results of UrDGAT2A and two commercial proteins (bovine serum albumin (BSA) and alcohol dehydrogenase) are used to demonstrate the effectiveness of the method in identifying actual N‐ and C‐termini, terminal truncation and blocking. Copyright © 2010 John Wiley & Sons, Ltd.
A suite of sensitive chemical methods to determine the δ15N of ammonium, nitrate and total dissolved N in soil extracts
Authors: Lachouani Petra , Frank Alexander H. , Wanek Wolfgang
Published: November 2010

Natural 15N abundances (δ15N values) of different soil nitrogen pools deliver crucial information on the soil N cycle for the analysis of biogeochemical processes. Here we report on a complete suite of methods for sensitive δ15N analysis in soil extracts. A combined chemical reaction of vanadium(III) chloride (VCl3) and sodium azide under acidic conditions is used to convert nitrate into N2O, which is subsequently analyzed by purge‐and‐trap isotope ratio mass spectrometry (PTIRMS) with a cryo‐focusing unit. Coupled with preparation steps (microdiffusion for collection of ammonium, alkaline persulfate oxidation to convert total dissolved N (TDN) or ammonium into nitrate) this allows the determination of the δ15N values of nitrate, ammonium and total dissolved N (dissolved organic N, microbial biomass N) in soil extracts with the same basic protocol. The limits of quantification for δ15N analysis with a precision of 0.5‰ were 12.4 µM for ammonium, 23.7 µM for TDN, 16.5 µM for nitrate and 22.7 µM for nitrite. Copyright © 2010 John Wiley & Sons, Ltd.
Effect of solvent and electrospray mass spectrometer parameters on the charge state distribution of peptides – a case study using liquid chromatography/mass spectrometry method development for beta‐endorphin assay
Authors: Hewavitharana A. K. , Herath H. M. D. R. , Shaw P. N. , Cabot P. J. , Kebarle P.
Published: November 2010

Beta‐endorphin was used as a model peptide to study the effect of solvent and electrospray mass spectrometer parameters in the optimisation of an assay method for multiply charged compounds using liquid chromatography/mass spectrometry (LC/MS). Unlike with singly charged compounds, the charge state distribution has a significant impact in the method development of multiply charged compounds such as peptides. Using a 50% acetonitrile/water solvent mixture, we found that the ion spray voltage had no influence on the charge state distribution. However, increasing declustering potential led to deprotonation of the higher charge states of the peptide thus causing a shift to lower charge states. The mechanism leading to the deprotonation was examined. It was concluded that the deprotonation is due to endoergic proton transfer from the peptide to solvent molecules clustered to the peptide that occurs in the declustering region. The extent of deprotonation increases with increasing proton affinity of the molecules of the non‐aqueous solvent component used. Thus, if desired, deprotonation can be avoided by selecting a low proton affinity solvent such as methanol. The focusing potential was also found to have a great influence on the charge state distribution observed. The results of this study enabled us to select the optimum ion to be used in single ion/reaction monitoring mode. They also provided the most favourable parameter values to be used in the method to obtain the best sensitivity for the ion of choice. The results demonstrate the importance of considering the charge state distribution in the optimisation of electrospray LC/MS methods for multiply charged compounds. Copyright © 2010 John Wiley & Sons, Ltd.
Determination of polymer electrolyte membrane (PEM) degradation products in fuel cell water using electrospray ionization tandem mass spectrometry
Authors: Zedda Marco , Tuerk Jochen , Peil Stefan , Schmidt Torsten C.
Published: November 2010

Within the scope of research of membrane degradation phenomena during fuel cell operation a reliable analytical procedure for the extraction, detection and quantification of possible membrane oxidation products has been developed. These oxidation products originate from the attack of hydroxyl or peroxyl radicals on the membrane polymer. Such radicals are formed in situ (during fuel cell operation) or ex situ (Fenton test as oxidative stress simulation). The analysis of membrane oxidation products was carried out by electrospray ionization tandem mass spectrometry. Five potential membrane oxidation products (4‐hydroxybenzoic acid (4‐HBA), 4‐hydroxybenzaldehyde (4‐HBAD), 4,4‐biphenol (4,4‐BP), 4‐hydroxybenzenesulfonate (4‐HBS), and 4,4‐sulfonylbiphenol (4,4‐SBP)) were selected based on the molecular structure of the sulfonated polyarylether membrane used. In conjunction with the development of a multiple reaction monitoring (MRM) method, the ionization and fragmentation of the selected compounds were investigated. For 4,4‐BP a molecular ion (M+•) was observed in the positive ionization mode and used for MRM method development. Reproducible extraction of the model compounds was achieved using a mixed‐mode sorbent material with both weak anion‐exchange and reversed‐phase retention properties. By using the developed analytical procedure, the identities of two membrane degradation products (4‐HBA and 4‐HBAD) were determined in situ and ex situ. In addition to the investigation of membrane degradation phenomena, the combination of extraction on a mixed‐mode sorbent material and tandem mass spectrometric detection is attractive for the analysis of aromatic sulfonic acids, phenolic acids and phenols. Copyright © 2010 John Wiley & Sons, Ltd.
Concentration effects on laser‐based δ18O and δ2H measurements and implications for the calibration of vapour measurements with liquid standards
Authors: Schmidt Markus , Maseyk Kadmiel , Lett Céline , Biron Philippe , Richard Patricia , Bariac Thierry , Seibt Ulli
Published: November 2010

Recently available isotope ratio infrared spectroscopy can directly measure the isotopic composition of atmospheric water vapour (δ18O, δ2H), overcoming one of the main limitations of isotope ratio mass spectrometry (IRMS) methods. Calibrating these gas‐phase instruments requires the vapourisation of liquid standards since primary standards in principle are liquids. Here we test the viability of calibrating a wavelength‐scanned cavity ring‐down spectroscopy (CRDS) instrument with vapourised liquid standards. We also quantify the dependency of the measured isotope values on the water concentration for a range of isotopic compositions. In both liquid and vapour samples, we found an increase in δ18O and δ2H with water vapour concentration. For δ18O, the slope of this increase was similar for liquid and vapour, with a slight positive relationship with sample δ‐value. For δ2H, we found diverging patterns for liquid and vapour samples, with no dependence on δ‐value for vapour, but a decreasing slope for liquid samples. We also quantified tubing memory effects to step changes in isotopic composition, avoiding concurrent changes in the water vapour concentration. Dekabon tubing exhibited much stronger, concentration‐dependent, memory effects for δ2H than stainless steel or perfluoroalkoxy (PFA) tubing. Direct vapour measurements with CRDS in a controlled experimental chamber agreed well with results obtained from vapour simultaneously collected in cold traps analysed by CRDS and IRMS. We conclude that vapour measurements can be calibrated reliably with liquid standards. We demonstrate how to take the concentration dependencies of the δ‐values into account. Copyright © 2010 John Wiley & Sons, Ltd.
Variations in science teaching modalities and students' pedagogic subject positioning through the discourse register and language code
Authors: Maeng Seungho , Kim Chan‐Jong
Published: November 2010

This study investigated the modalities of science teaching practice and students' pedagogic subject positioning through the linguistic features of science classroom discourse and the discursive interaction. For this purpose, this study sought to develop a methodology for classroom discourse analysis, the TMARC (Triangular Model of Analyzing discourse Register and language Code). Applied to a middle school science classroom, the TMARC revealed that there were six types of teaching modalities during the classroom practices in spite of the teacher's predominant didactic teaching and that there existed the diverse variation types of the teaching modalities according to a temporal order. In addition, we found four types of pedagogic subject positioning through the application of TMARC. We also argued that the pedagogic subject positioning of a successful science learner was implemented in the discourse language codes of personal collaborative open discourse, positional collaborated open discourse, and personal collaborative controlled discourse. Each of these related to the science teaching modality in which student centeredness was emphasized. Thus, this study suggests that a science teacher's competency related to managing classroom discourse can control students' pedagogic subject position and, by extension, contribute to students' science learning. © 2010 Wiley Periodicals, Inc.Sci Ed95:431–457, 2011
Transient and steady‐state magnetic fields induce increased fluorodeoxyglucose uptake in the rat hindbrain
Authors: Frilot Clifton , Carrubba Simona , Marino Andrew A.
Published: November 2010

We inquired into the biophysical basis of the ability of weak electromagnetic fields (EMFs) to trigger onset and offset evoked potentials, and to produce steady‐state changes in the electroencephalogram (EEG). Rats were exposed to a 2.5‐G, 60‐Hz magnetic field and the neuroanatomical region of glucose activation associated with the effect of the field on the EEG was identified by positron emission tomography (PET) using fluorodeoxyglucose (FDG). Paired emission scans from the same animal with and without field treatment were differenced and averaged, and t values of the brain voxels computed using the pooled standard deviation were compared with a calculated critical t value to identify the field‐activated voxels. Increased glucose utilization occurred in hindbrain voxels when the field was applied orthogonally to the sagittal plane, but not when the angle between the field and the sagittal plane varied randomly. Distinct FDG activation effects were observed in response to transient (both onset and offset) and steady‐state magnetic stimuli. Observations of increased glucose utilization induced by magnetic stimuli and its dependence on the direction of the field suggested that signal transduction was mediated by a force detector and that the process and/or early posttransduction processing occurred in the hindbrain. Synapse, 2011. © 2010 Wiley‐Liss, Inc.
The efficacy of n-3 fatty acids DHA and EPA (fish oil) for perinatal depression
Authors: Jans Linda A. W. , Giltay Erik J. , Willem Van der Does A. J.
Published: November 2010

Depressive symptoms are common during pregnancy and the post-partum period. Although essential n-3 PUFA may have beneficial effects on depression, it remains unclear whether they are also effective for perinatal depression. The purpose of the present study was to assess the efficacy of n-3 supplementation for perinatal depression, by performing a meta-analysis on currently available data. After a thorough literature search, we included seven randomised controlled trials in the meta-analysis, all with EPA and/or DHA supplementation. Most studies were judged to be of low-to-moderate quality, mainly due to small sample sizes and failure to adhere to Consolidated Standards of Reporting Trials guidelines. Some studies were not primarily designed to address perinatal depression. A total of 309 women on n-3 fatty acid supplementation were compared with 303 women on placebo treatment. n-3 Supplementation was not found to be significantly more effective than placebo at post-treatment with a pooled effect size (Hedges's g) of − 0·03 (95 % CI − 0·18, 0·13; P = 0·76) using a fixed-effects model. Heterogeneity was low-to-moderate (I2 = 30 %). In a subgroup analysis of three small studies of pregnant women with major depression, there was some indication of effectiveness (effect size 0·17; 95 % CI − 0·21, 0·55). In conclusion, the question of whether EPA and DHA administration is effective in the prevention or treatment of perinatal depression cannot be answered yet. Future research should focus on women who are clinically depressed (or at risk). The quality of research in this area needs to improve.
The antioxidant role ofSideritis caesareainfusion against TCA toxicity in rats
Authors: Celik Ismail , Kaya Mehmet Salih
Published: November 2010

Sideritis caesarea(SC) Duman, Aytac&Baser is a member of the Lamiaceae family. The present study was designed to investigate the antioxidant properties of the aerial parts of island green tea SC against TCA effects in rats. Biomarkers selected for monitoring antioxidant capacity were the activities of glutathione reductase (GR), superoxide dismutase (SOD), glutathione-S-transferase, catalase (CAT), GSH level and malondialdehyde (MDA) content in various organs of rats. Three experimental groups, A (untreated = control), B (only TCA-treated) and C (TCA+SC-treated), were studied. At the end of the 50 d experiment, the MDA content in tissues increased significantly in group B, whereas no significant changes were observed in group C as compared with that of the control group. Antioxidant enzyme activities such as SOD and CAT increased significantly in the brain, liver and kidneys of group B but decreased significantly in group C as compared with group B. The GSH level and GR activity increased significantly in the brain and liver of group C as compared with the control and TCA-exposed rats. Hence, the study reveals that the constituents present in SC impart protection against chemical-induced oxidative injury that may result in the development of cancer.
Curcumin induces paraoxonase 1 in cultured hepatocytes in vitro but not in mouse liver in vivo
Authors: Schrader Charlotte , Schiborr Christina , Frank Jan , Rimbach Gerald
Published: November 2010

Paraoxonase 1 (PON1) is an enzyme that is mainly synthesised in the liver and protects LDL from oxidation, thereby exhibiting antiatherogenic properties. Using a luciferase reporter gene assay, we tested curcumin for its ability to induce PON1 in Huh7 hepatocytes in culture. Curcumin ( ≥ 10 μmol/l) dose-dependently induced PON1 transactivation in Huh7 cells. However, dietary supplementation of female B6C3F1 mice with curcumin (500 mg/kg diet) for 2 weeks did not increase the hepatic PON1 mRNA and protein levels. No curcumin was detectable in the plasma of the 12 h fasted mice. In conclusion, curcumin may be a potent PON1 inducer in cultured cells in vitro, but not in the liver of curcumin-fed mice because of its low concentrations in vivo.
Weakly nonlinear theory of shear-banding instability in a granular plane Couette flow: analytical solution, comparison with numerics and bifurcation
Authors: SHUKLA PRIYANKA , ALAM MEHEBOOB
Published: November 2010

A weakly nonlinear theory, in terms of the well-known Landau equation, has been developed to describe the nonlinear saturation of the shear-banding instability in a rapid granular plane Couette flow using the amplitude expansion method. The nonlinear modes are found to follow certain symmetries of the base flow and the fundamental mode, which helped to identify analytical solutions for the base-flow distortion and the second harmonic, leading to an exact calculation of the first Landau coefficient. The present analytical solutions are used to validate a spectral-based numerical method for the nonlinear stability calculation. The regimes of supercritical and subcritical bifurcations for the shear-banding instability have been identified, leading to the prediction that the lower branch of the neutral stability contour in the (H, φ0)-plane, where H is the scaled Couette gap (the ratio between the Couette gap and the particle diameter) and φ0 is the mean density or the volume fraction of particles, is subcritically unstable. The predicted finite-amplitude solutions represent shear localization and density segregation along the gradient direction. Our analysis suggests that there is a sequence of transitions among three types of pitchfork bifurcations with increasing mean density: from (i) the bifurcation from infinity in the Boltzmann limit to (ii) subcritical bifurcation at moderate densities to (iii) supercritical bifurcation at larger densities to (iv) subcritical bifurcation in the dense limit and finally again to (v) supercritical bifurcation near the close packing density. It has been shown that the appearance of subcritical bifurcation in the dense limit depends on the choice of the contact radial distribution function and the constitutive relations. The scalings of the first Landau coefficient, the equilibrium amplitude and the phase diagram, in terms of mode number and inelasticity, have been demonstrated. The granular plane Couette flow serves as a paradigm that supports all three possible types of pitchfork bifurcations, with the mean density (φ0) being the single control parameter that dictates the nature of the bifurcation. The predicted bifurcation scenario for the shear-band formation is in qualitative agreement with particle dynamics simulations and the experiment in the rapid shear regime of the granular plane Couette flow.
Overtopping a truncated planar beach
Authors: HOGG ANDREW J. , BALDOCK TOM E. , PRITCHARD DAVID
Published: November 2010

Run-up on a truncated impermeable beach is analysed theoretically and experimentally to find the volume of fluid, associated with a single wave event, that flows over the end of the beach. The theoretical calculations investigate the motion using the shallow-water equations and the fluid is allowed to flow freely over the end of the beach. Two models of wave events are considered: dam-break initial conditions, in which fluid collapses from rest to run-up and overtop the beach, and a waveform that models swash associated with the collapse of a long solitary bore. The calculations are made using quasi-analytical techniques, following the hodograph transformation of the governing equations. They yield predictions for the volume of fluid per unit width that overtops the beach, primarily as a function of the dimensionless length of the beach. These predictions are often far in excess of previous theoretical calculations. New experimental results are also reported in which the overtopping volumes due to flows initiated from dam-break conditions are studied for a range of reservoir lengths and heights and for a range of lengths and inclinations of the beach. Without the need for any empirically fitted parameters, good agreement is found between the experimental measurements and the theoretical predictions in regimes for which the effects of drag are negligible.
The laminar generalized Stokes layer and turbulent drag reduction
Authors: QUADRIO MAURIZIO , RICCO PIERRE
Published: November 2010

This paper considers plane channel flow modified by waves of spanwise velocity applied at the wall and travelling along the streamwise direction. Both laminar and turbulent regimes for the streamwise flow are studied. When the streamwise flow is laminar, it is unaffected by the spanwise flow induced by the waves. This flow is a thin, unsteady and streamwise-modulated boundary layer that can be expressed in terms of the Airy function of the first kind. We name it the generalized Stokes layer because it reduces to the classical oscillating Stokes layer in the limit of infinite wave speed. When the streamwise flow is turbulent, the laminar generalized Stokes layer solution describes well the space-averaged turbulent spanwise flow, provided that the phase speed of the waves is sufficiently different from the turbulent convection velocity, and that the time scale of the forcing is smaller than the life time of the near-wall turbulent structures. Under these conditions, the drag reduction is found to scale with the Stokes layer thickness, which renders the laminar solution instrumental for the analysis of the turbulent flow. A classification of the turbulent flow regimes induced by the waves is presented by comparing parameters related to the forcing conditions with the space and time scales of the turbulent flow.
On the generation of large-scale structures in a homogeneous eddy field
Authors: RADKO TIMOUR
Published: November 2010

An analytical theory is developed which illustrates dynamics of the spontaneous generation of large-scale structures in the unforced two-dimensional eddying flows. The eddy field is represented by the closely packed array of standing coherent vortices whose intensity is weakly modulated by the long-wavelength perturbations introduced into the system. The asymptotic multiscale analysis makes it possible to identify instabilities resulting from the positive feedback of the background eddies on large-scale perturbations. Initially, these instabilities amplify at a rate proportional to the square root of their wavenumber. Linear growth is arrested when the amplitude of the long-wavelength perturbations reaches the level of background eddies. The subsequent evolutionary pattern is characterized by the emergence of relatively sharp features in the large-scale streamfunction field – features suggestive of the coherent jets commonly observed in eddying geophysical flows. The proposed solutions differ substantially from their counterparts in forced-dissipative systems, exemplified by the canonical model of Kolmogorov flow. The asymptotic model is successfully tested against numerical simulations.
Protective effects of brain-derived neurotrophic factor on the noise-damaged cochlear spiral ganglion
Authors: Zhai S-Q , Guo W , Hu Y-Y , Yu N , Chen Q , Wang J-Z , Fan M , Yang W-Y
Published: November 2010

Objective:

To explore the protective effects of brain-derived neurotrophic factor on the noise-damaged cochlear spiral ganglion.

Methods:

Recombinant adenovirus brain-derived neurotrophic factor vector, recombinant adenovirus LacZ and artificial perilymph were prepared. Guinea pigs with audiometric auditory brainstem response thresholds of more than 75 dB SPL, measured seven days after four hours of noise exposure at 135 dB SPL, were divided into three groups. Adenovirus brain-derived neurotrophic factor vector, adenovirus LacZ and perilymph were infused into the cochleae of the three groups, variously. Eight weeks later, the cochleae were stained immunohistochemically and the spiral ganglion cells counted.

Results:

The auditory brainstem response threshold recorded before and seven days after noise exposure did not differ significantly between the three groups. However, eight weeks after cochlear perfusion, the group receiving brain-derived neurotrophic factor had a significantly decreased auditory brainstem response threshold and increased spiral ganglion cell count, compared with the adenovirus LacZ and perilymph groups.

Conclusion:

When administered via cochlear infusion following noise damage, brain-derived neurotrophic factor appears to improve the auditory threshold, and to have a protective effect on the spiral ganglion cells.
Bronchoscopy versus multi-detector computed tomography in the diagnosis of congenital vascular ring
Authors: Gaafar A H , El-Noueam K I
Published: November 2010

Background:

Vascular rings are congenital vascular anomalies of the aortic arch complex which cause compression of the trachea and/or oesophagus. A variety of investigations may lead to diagnosis of these anomalies, including bronchoscopy and computed tomography. During the latter, image acquisition and processing use the multi-detector row technique and new reconstruction algorithms, producing high-resolution images which can be visualised as complex, three-dimensional renditions.

Objective:

This study aimed to assess and compare the roles of bronchoscopy and multi-detector row computed tomography in the diagnosis of congenital vascular ring.

Patients and methods:

We included infants and children below the age of 16 years who presented with congenital vascular ring. All patients underwent rigid bronchoscopy under general anaesthesia, with spontaneous respiration. All computed tomography scans were obtained using a 16 multi-detector row computed tomography system, followed by data reconstruction on a three-dimensional workstation.

Results:

Ten patients with congenital vascular ring were identified (six boys and four girls). Fifty per cent of cases presented within the first year of life. Double aortic arch was the most common anomaly (40 per cent). Bronchoscopy detected external tracheal compression in nine cases (90 per cent). Associated airway lesions were detected endoscopically in three cases. In contrast, multi-detector row computed tomography detected the vascular ring in all cases, with accurate detection of the compressing vessel; however, it did not detect any associated airway lesions.

Conclusion:

Bronchoscopy and radiological evaluation are essential for the diagnosis and pre-operative evaluation of congenital vascular ring. Multi-detector row computed tomography can provide more information about the nature of the disease, and can facilitate better communication between clinicians, compared with conventional computed tomography.
Parapharyngeal cerebrospinal fluid collection: an unusual complication of temporal bone fracture
Authors: Kirton C , Guidera A
Published: November 2010

Objective:

We present an unusual case of parapharyngeal cerebrospinal fluid collection causing upper airway obstruction following a temporal bone fracture.

Method:

Case report and literature review of temporal bone fracture associated with parapharyngeal cerebrospinal fluid collection.

Results:

A 19-year-old man presented with cerebrospinal fluid otorrhoea and temporal bone fracture following a head injury. He was discharged after 48 hours of observation. The patient returned within 6 hours with sudden unilateral neck swelling and stridor after blowing his nose. Flexible nasendoscopy and computed tomography showed extrinsic compression of the pharynx, with partial upper airway obstruction. A literature review using Pubmed™ and Medline™ identified no previously reported cases of parapharyngeal cerebrospinal fluid collection associated with temporal bone fracture.

Conclusion:

This case illustrates a previously undescribed complication of temporal bone fracture. Raised intracranial pressure in the presence of a cerebrospinal fluid fistula may lead to airway obstruction, following temporal bone fracture.
Larval morphologies and potential developmental modes of eight sea spider species (Arthropoda: Pycnogonida) from the southern Oregon coast
Authors: Burris Z.P.
Published: November 2010

Larvae of eight sea spiders from three families (Ammotheidae, Pycnogonidae and Phoxichilidiidae) are described for the first time. The external morphology of the first larval stage of each species is presented in detail using scanning electron microscopy photographs in order to determine the mode of postembryonic development. Three types of larval development are apparent in the species examined. The speciesAchelia gracilipes, Eurycyde spinosa, Pycnogonum rickettsiandPycnogonum stearnsi(families Ammotheidae and Pycnogonidae) have larval morphologies indicative of an ‘ectoparasitic’ development. Morphological characteristics ofAchelia simplissimaandAchelia chelata(family Ammotheidae) larvae suggest an ‘endoparasitic’ development, while larvae of the speciesAnoplodactylus viridintestinalis(family Phoxichilidiidae) have traits implying an ‘encysting’ postembryonic mode of development. Larvae of the speciesNymphopsis spinosissimahave unusual morphological characteristics that may be indicative of a new developmental mode.
Seasonal variation in the effect of climate on the biology of Rhipicephalus sanguineus in southern Europe
Authors: DANTAS-TORRES FILIPE , FIGUEREDO LUCIANA A. , OTRANTO DOMENICO
Published: November 2010

Objective.Rhipicephalus sanguineus is the most widespread tick in the world and a vector of many pathogens infecting dogs and humans. To date, there have been no investigations on the biology of R. sanguineus under natural Mediterranean climatic conditions. Methods. The biology of R. sanguineus was studied under laboratory and natural climatic conditions in southern Italy. Several biological parameters were compared in different seasons, and their correlation with climatic data was assessed. Results. The life cycle of R. sanguineus lasted for a mean of 101·4 and 116·2 days under laboratory and environmental conditions respectively. Reproductive parameters of wild-collected females kept in the environment in May were significantly different from first-generation females maintained in September–October, and the correlation between reproductive parameters and climate data varied according to season. Conclusion. These results indicate that the Mediterranean climate affects the biology of R. sanguineus, which compensates its losses during the initial phases of its cycle in spring with high feeding and moulting rates of larvae and nymphs during summer as well as with high egg production during autumn. These results advance our knowledge of the biology of R. sanguineus and will be useful for the understanding of the eco-epidemiology of tick-borne diseases that this tick transmits.
Molecular approaches for a better understanding of the epidemiology and population genetics ofLeishmania
Authors: SCHÖNIAN G. , KUHLS K. , MAURICIO I. L.
Published: November 2010

Molecular approaches are being used increasingly for epidemiological studies of visceral and cutaneous leishmaniases. Several molecular markers resolving genetic differences betweenLeishmaniaparasites at species and strain levels have been developed to address key epidemiological and population genetic questions. The current gold standard, multilocus enzyme typing (MLEE), needs cultured parasites and lacks discriminatory power. PCR assays identifying species directly with clinical samples have proven useful in numerous field studies. Multilocus sequence typing (MLST) is potentially the most powerful phylogenetic approach and will, most probably, replace MLEE in the future. Multilocus microsatellite typing (MLMT) is able to discriminate below the zymodeme level and seems to be the best candidate for becoming the gold standard for distinction of strains. Population genetic studies by MLMT revealed geographical and hierarchic population structure inL. tropica, L. majorand theL. donovanicomplex. The existence of hybrids and gene flow betweenLeishmaniapopulations suggests that sexual recombination is more frequent than previously thought. However, typing and analytical tools need to be further improved. Accessible databases should be created and sustained for integrating data obtained by different researchers. This would allow for global analyses and help to avoid biases in analyses due to small sample sizes.
Voxel-based meta-analysis of regional white-matter volume differences in autism spectrum disorderversushealthy controls
Authors: Radua J. , Via E. , Catani M. , Mataix-Cols D.
Published: November 2010

Background

We conducted a meta-analysis of voxel-based morphometry (VBM) studies in autism spectrum disorder (ASD) to clarify the changes in regional white-matter volume underpinning this condition, and generated an online database to facilitate replication and further analyses by other researchers.

Method

PubMed, ScienceDirect, Web of Knowledge and Scopus databases were searched between 2002 (the date of the first white-matter VBM study in ASD) and 2010. Manual searches were also conducted. Authors were contacted to obtain additional data. Coordinates were extracted from clusters of significant white-matter difference between patients and controls. A new template for white matter was created for the signed differential mapping (SDM) meta-analytic method. A diffusion tensor imaging (DTI)-derived atlas was used to optimally localize the changes in white-matter volume.

Results

Thirteen datasets comprising 246 patients with ASD and 237 healthy controls met inclusion criteria. No between-group differences were found in global white-matter volumes. ASD patients showed increases of white-matter volume in the right arcuate fasciculus and also in the left inferior fronto-occipital and uncinate fasciculi. These findings remained unchanged in quartile and jackknife sensitivity analyses and also in subgroup analyses (pediatricversusadult samples).

Conclusions

Patients with ASD display increases of white-matter volume in tracts known to be important for language and social cognition. Whether the results apply to individuals with lower IQ or younger age and whether there are meaningful neurobiological differences between the subtypes of ASD remain to be investigated.
Effects of aCACNA1Cgenotype on attention networks in healthy individuals
Authors: Thimm M. , Kircher T. , Kellermann T. , Markov V. , Krach S. , Jansen A. , Zerres K. , Eggermann T. , Stöcker T. , Shah N. J. , Nöthen M. M. , Rietschel M. , Witt S. H. , Mathiak K. , Krug A.
Published: November 2010

Background

Recent genetic studies found the A allele of the variant rs1006737 in the alpha 1C subunit of the L-type voltage-gated calcium channel (CACNA1C) gene to be over-represented in patients with psychosis, including schizophrenia, bipolar disorder and major depressive disorder. In these disorders, attention deficits are among the main cognitive symptoms and have been related to altered neural activity in cerebral attention networks. The particular effect ofCACNA1Con neural function, such as attention networks, remains to be elucidated.

Method

The current event-related functional magnetic resonance imaging (fMRI) study investigated the effect of theCACNA1Cgene on brain activity in 80 subjects while performing a scanner-adapted version of the Attention Network Test (ANT). Three domains of attention were probed simultaneously: alerting, orienting and executive control of attention.

Results

Risk allele carriers showed impaired performance in alerting and orienting in addition to reduced neural activity in the right inferior parietal lobule [Brodmann area (BA) 40] during orienting and in the medial frontal gyrus (BA 8) during executive control of attention. These areas belong to networks that have been related to impaired orienting and executive control mechanisms in neuropsychiatric disorders.

Conclusions

Our results suggest thatCACNA1Cplays a role in the development of specific attention deficits in psychiatric disorders by modulation of neural attention networks.
Observations on extraction from V2 clauses in Scandinavian
Authors: Hrafnbjargarson Gunnar Hrafn , Bentzen Kristine , Wiklund Anna-Lena
Published: November 2010

This short communication presents a general overview of facts concerningwh-extraction from V2 clauses in the Scandinavian languages. While extraction from V2 clauses with a fronted non-subject is impossible in all of these languages, three classes can be distinguished with regard to extraction from subject-initial V2 clauses.
Prenatal diagnosis of left ventricular aneurysm in association with interruption of the aortic arch
Authors: Jowett Victoria , Miller Owen
Published: November 2010

Left ventricular aneurysms in the foetus are a rare abnormality that can occur in isolation or associated with pentalogy of Cantrell. Here, we report a case of a foetus with a left ventricular aneurysm in association with interruption of the aortic arch, and no features of pentalogy of Cantrell. To our knowledge, this is the first report of such an association.
Usefulness of ambulatory blood pressure monitoring and head-up tilt test in the evaluation of paediatric syncope
Authors: Giordano Ugo , Meta Roberta , Fintini Danilo , Turchetta Attilio , Brufani Claudia , Calzolari Armando
Published: November 2010

Objectives

The aim of this study was to investigate the usefulness of ambulatory blood pressure monitoring versus head-up tilt test in the evaluation of children with a history of syncope.

Study design

We considered 146 consecutive children with more than one episode of syncope. All patients had a normal electrocardiogram at rest and were otherwise considered to be healthy. Forty-six patients,19 male, with a mean age of 13.6 plus or minus 5.6 years, were studied with a head-up tilt test and 100 patients, 41 male with a mean age of 9.4 plus or minus 5.6 years, were studied with ambulatory blood pressure monitoring. Twelve patients underwent both procedures. Hypotension during ambulatory blood pressure monitoring was defined when mean blood pressure values were lower than the 50th centile and the head-up tilt test was positive when syncope occurred. All patients were followed for 10 plus or minus 2 months.

Results

Ambulatory blood pressure monitoring showed postural hypotension in 91% children, while head-up tilt test was positive for 54%. In the group of children having both tests, two of them were negative for both, 10 of 12 children had a positive ambulatory blood pressure monitoring while only five of 10 children had a positive response to head-up tilt test.

Conclusions

When a child with a normal resting electrocardiogram is referred with a typical history of syncope, the use of ambulatory blood pressure monitoring as a non-invasive first step for diagnosis of postural hypotension may be more sensitive than the head-up tilt test. Behavioural adjustments resolved the continued syncope in most cases. If episodes persist then the head-up tilt test is indicated.
A family with a newelastingene mutation: broad clinical spectrum, including sudden cardiac death
Authors: Jakob André , Unger Sheila , Arnold Raoul , Grohmann Jochen , Kraus Cornelia , Schlensak Christian , Stiller Brigitte
Published: November 2010

Supravalvular aortic stenosis is associated with the Williams–Beuren syndrome, but it also occurs in a non-syndromatic congenital form. Anelastingene mutation of chromosome 7q11.23 is responsible in both cases. The vascular features are identical. These patients have a higher risk of sudden death, particularly when undergoing diagnostic or surgical procedures. We report the account of a family with a new mutation in theelastingene. Screening over three generations revealed eight affected individuals. The cardiac and vascular malformations ranged from mild asymptomatic supravalvular aortic stenosis and isolated dysplastic atrioventricular valves to diffuse arterial hypoplasia. Two infants presented arteries affected at multiple locations, including the left coronary artery. Both died of sudden cardiac death and myocardial ischaemia, one while under general anaesthesia for cardiac catheterisation, and the other perioperatively. We discuss the pathophysiological aspects in these patients that deserve consideration before any general anaesthesia is administered.