bluuebunny/crossref_metadata_2025 huggingface dataset:
Structural comparison of oxidized and reduced FKBP13 from Arabidopsis thaliana
Authors: Gopalan Gayathri , He Zengyong , Battaile Kevin P. , Luan Sheng , Swaminathan Kunchithapadam
Published: October 2006

AtFKBP13, an immunophilin in the chloroplast thylakoid lumen, participates in redox‐regulatory processes via a pair of conserved disulfide bonds that are present at the N‐ and C‐termini of the protein. Characterization of this protein by structural and biochemical analysis has revealed a novel mechanism of redox regulation in the thylakoid lumen. The protein is active in its oxidized form but is inactivated after reduction by the thioredoxin system. This is in sharp contrast with the regulation of biosynthetic enzymes in the stroma of the chloroplast, where reduction of enzymes by thioredoxin activates their function. To understand how the reduced form of AtFKBP13 is stabilized and how reduction of the cysteine residues affects the molecular properties of the enzyme, we determined the crystal structure of reduced AtFKBP13 at 1.88 Å. Comparison of the reduced structure and the oxidized form that we published earlier shows rearrangements in redox site regions, readjustments of hydrogen‐bonding interactions and the secondary structure of the active site residues 50–53, and reduced accessibility of the catalytic residues involved in the peptidyl proline isomerase (PPIase) activity of this enzyme. We propose that redox‐linked changes in the secondary structure of the PPIase domain are responsible for significant functional differences in this protein in the reduced and oxidized states. Proteins 2006. © 2006 Wiley‐Liss, Inc.
n‐Type doping of diamond
Authors: Koizumi Satoshi , Suzuki Mariko
Published: October 2006

n‐Type diamond formation is one of the most important issues for the electronic application of diamond. Phosphorus is the best n‐type dopant candidate at the moment. We have succeeded in growing high‐quality phosphorus‐doped diamond thin films on {111} diamond substrates. Although the ionization energy of the phosphorus donor is large (0.57 eV), the n‐type conductivity is clearly observed by Hall measurements. The Hall mobility is as high as 660 cm2/(V s) at room temperature. In this paper, the current status of n‐type diamond research is mentioned with focus mainly on the growth of high‐mobility n‐type diamond and its electrical properties. The Hall measurements performed over a wide temperature range give detailed information about the nature of the n‐type conductivity. Current–voltage and capacitance–voltage measurements of a Schottky diode formed by nickel contacts on an n‐type diamond layer show unique characteristics of semiconducting diamond. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Emission properties from dense exciton gases in diamond
Authors: Okushi Hideyo , Watanabe Hideyuki , Yamasaki Satoshi , Kanno Shokichi
Published: October 2006

A systematic study of cathodoluminescence (CL) emission arising from free exciton recombination in diamond is given. CL spectra of free exciton emission from diamond under high excitation conditions were used to characterize properties of ultradense exciton gases at quasi‐thermal equilibrium. Theoretical spectra of excitonic emission from diamond were calculated based on Bose–Einstein (BE) statistics, taking into account collision of excitons in an indirect semiconductor like diamond. The calculated spectra agreed well with the observed spectra over a wide temperature range for high‐quality homoepitaxial chemical vapor deposition diamond thin films. The analysis showed that a high density of excitons of over 1018 cm−3 could be achieved under thermodynamic quasi‐equilibrium by continuous electron beam excitation, at which BE condensation can be expected at low temperature. These results indicate that diamond is a perfect material for the generation and detection of BE condensation which is the most characteristic features of BE statistics. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The transformation of open picotubes to a closed molecular configuration
Authors: Schaman Christoph , Pfeiffer Rudolf , Zólyomi Viktor , Kuzmany Hans , Ajami Daniel , Herges Rainer , Dubay Orest , Sloan Jeremy
Published: October 2006

Starting with the open picotube, we studied the interaction of the picotube with carbon nanotubes. The picotube is easily produced at low cost, and therefore an ideal candidate for filling CNTs. The observed spectra are in good agreement with the spectra predicted by Gaussian'03 for the closed picotube. The stability of the molecule in two different environments, the inside and the outside of the nanotubes, were investigated in local density approximation and inter‐molecular Hückel calculations. We conclude that the closed picotube was formed, and is located on the outside of bundles of nanotubes. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Structural and electronic properties of Ptn (n = 3, 7, 13) clusters on metallic single wall carbon nanotube
Authors: Cuong Nguyen Thanh , Chi Dam Hieu , Kim Yong‐Tae , Mitani Tadaoki
Published: October 2006

A systematic study of Ptn (n = 3, 5, 7) clusters adsorbed on the metallic (5, 5) single wall carbon nanotube was carried out using theoretical calculations within Density Functional Theory. The geometrical and electronic structure and interaction between the Pt clusters and the single wall carbon nanotube were investigated. The bridge adsorption sites on the outer wall of the carbon nanotube are found favorable for Pt atom. We found that the average C–Pt and Pt–Pt bond length, binding energy, and the amount of charge transfers from the Pt cluster toward the nanotube increase with the size of cluster. The calculated density‐of‐states suggest a mixing of ionic and covalent character for the binding nature of this system. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The study of the interaction of human mesenchymal stem cells and monocytes/macrophages with single‐walled carbon nanotube films
Authors: Kalbacova M. , Kalbac M. , Dunsch L. , Kataura H. , Hempel U.
Published: October 2006

The influence of single‐walled carbon nanotube (SWCNT) films on two different human cell types was investigated: primary mesenchymal stem cells (MSC) and the monocytes/macrophages cell line THP‐1, the focus being on the metabolic activity of these cells. The SWCNT were free of impurity as was confirmed by Raman and VIS‐NIR spectroscopy. No surfactant was used to minimize the effect of other agents on the behavior of the cells. The results obtained on SWCNT films were compared to those measured on carbon fibers (CF). The metabolic activity of the investigated cell types cultured on SWCNT film was only slightly reduced (about 20%), while carbon fibers led to a much stronger decrease (about 40%). The reaction of the cells depended on the cell number, with more cells showing less metabolic inhibition. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Synthesis of single‐walled carbon nanotubes with the laser vaporization method: Ex situ and in situ measurements
Authors: Cau M. , Dorval N. , Attal‐Trétout B. , Cochon J. L. , Pigache D. , Loiseau A. , Arutyunyan N. R. , Obraztsova E. D. , Krüger V. , Tsurikov M.
Published: October 2006

In situ measurements were executed in the continuous wave CO2‐laser vaporization synthesis of single‐walled carbon nanotubes (SWCNTs). The results were compared with the findings of the ex situ analysis of the product. Different catalysts (Co, Ni, Co/Ni, Ni/Y and Co/Y) were used and the temperature of the target surface (T s) changed to compare the efficiency of the synthesis process. Our main results are related to the SWCNTs diameter which is depending on T s and on the catalysts nature. The targets containing Y with Co or Ni atoms produce more and larger SWCNTs than Co/Ni targets. The SWCNTs' diameter is seen to increase with T s. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
NMR study of spin excitations in carbon nanotubes
Authors: Singer P. M. , Wzietek P. , Alloul H. , Simon F. , Kuzmany H.
Published: October 2006

The spin dynamics of 13C isotope enriched inner‐walls in double‐wall carbon nanotubes (DWCNT) has been studied using 13C nuclear magnetic resonance (NMR). Contrary to expectations, the spin–lattice relaxation time (T 1) has the same temperature (T) and magnetic field (H) dependence for most of the inner‐wall nanotubes detected by NMR. In the high temperature regime (T ≳ 150 K), we find that the T and H dependence of 1/T 1T is consistent with a 1D metallic chain. For T ≲ 150 K the data clearly indicates the formation of a gap in the spin excitation spectrum, where the gap value 2Δ ≃ 40 K (≡ 3.7 meV) is H independent. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
The effect of molecular oxygen on the thermal conductance of multi‐walled nanotubes – a preliminary investigation
Authors: Brown E. , Hao L. , Gallop J. C. , Macfarlane J. C. , Josephs‐Franks P. W. , Cohen L. F.
Published: October 2006

Whilst the effect of oxygen adsorption on the electrical properties of carbon nanotubes has been investigated extensively, little is known about how oxygen changes the thermal properties of nanotubes.

Here we present a preliminary investigation on the effect of molecular oxygen on the electrical and thermal conductance of multi‐walled nanotubes (MWNTs) measured simultaneously.

The nanotubes were placed in a vacuum chamber (pressures <1 × 10–5 mbar) for a prolonged period of time (>7 days) and continuously heated above 100 °C to ensure oxygen desorption. Then pure oxygen was introduced in the chamber using a needle valve (the pressure in the chamber was always <3 × 10–4 mbar) and the heating of the nanotube was stopped to allow oxygen adsorption.

Thermal and electrical conductance measurements were taken simultaneously on the nanotubes when degassed and in the presence of oxygen.

The thermal conductance of the nanotubes increased by a maximum of about 20% upon addition of oxygen. The percentage increase was initially linearly dependent on the amount of oxygen added then at oxygen pressures >1 × 10−4 mbar saturation of the effect was observed.

The reasons for these changes are proposed to be: (i) oxygen adsorption caused a change in the nanotubes' phonon modes; (ii) the presence of oxygen molecules facilitated the inter‐shell transfer of heat in the nanotube. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Raman intensities of the first optical transitions in carbon nanotubes
Authors: Telg H. , Maultzsch J. , Reich S. , Hennrich F. , Thomsen C.
Published: October 2006

We performed resonant Raman spectroscopy on the lowest optical transition E S11 of separated single‐walled carbon nanotubes by studying the radial‐breathing mode (RBM) spectra for excitation energies between 1.15 and 1.48 eV. We were able to extend the experimental Kataura plot to these energies by adding the E S11 transition energies of 11 nanotube chiralities. We discuss also the relative Raman intensities; they are more similar for different family index ν than those of the corresponding transitions of the E S22 [1]. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
High‐density selective excitation effect on excitons in semimagnetic semiconductor CdMnTe
Authors: Katayama K. , Miyajima K. , Ashida M. , Itoh T.
Published: October 2006

Many body effects among electron–hole pairs and exchange interaction of spins between electron/hole and Mn2+ ions have been investigated in a semimagnetic semiconductor of CdMnTe under the selective excitation of high‐density localized excitons with use of a picosecond pulse laser. A new nonlinear luminescence band (X band) has been found on the high‐energy side of conventional exciton magnetic polaron band and its peak energy shows a pronounced red shift with the increase of excitation power and/or with the application of magnetic field. Time‐resolved luminescence without magnetic field has revealed the characteristic behaviour of the X band with a longer rise time for the higher energy side. However, this tendency disappears with the application of magnetic field. As the origin of the X band, we propose the high‐density spin‐polarized electron–hole pairs interacting with microscopic Mn2+‐ion spins aligned through the exchange interaction. (© 2006 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Complexity analysis of BPEL Web processes
Authors: Cardoso Jorge
Published: October 2006

Several organizations have already realized the potential of using WS‐BEPL, the Process Execution Language for Web Services, to model the behavior of Web services in business processes. WS‐BPEL provides a model for describing simple or complex interactions between business partners. In some cases, WS‐BPEL process designs can be highly complex, due, for example, to the vast number of Web services carried out in global markets. High complexity in a process has several undesirable drawbacks; it may result in poor understandability, more errors, defects, and exceptions, leading to processes requiring more time to be developed, tested, and maintained. Therefore, excessive complexity should be avoided. Processes that are highly complex tend be less flexible, since it is more complicated to make changes to the process. The major goal of this article is to present two metrics to analyze the control‐flow complexity (CFC) of WS‐BPEL Web processes. The metrics are to be used at design‐time to evaluate the complexity of a process design before implementation actually takes place. Copyright © 2006 John Wiley & Sons, Ltd.
An iterative improvement process for agile software development
Authors: Salo Outi , Abrahamsson Pekka
Published: October 2006

Agile software development of short iterative cycles offers an opportunity for rapid, visible and motivating software process improvement (SPI). The agile principles suggest the regular reflections of agile project teams for improving the efficiency and adaptation of the process. However, current literature provides little support or empirical evidence for conducting such improvement efficiently, systematically and in a validated manner. Thus, this article proposes an Iterative Improvement Process for conducting SPI within individual agile project teams, which aims at increasing the ability of software developers to improve the development process based on their experiences and context knowledge. The approach has been trialed within a multiple case study of five consecutive case projects where both qualitative and quantitative research data has been systematically collected. The empirical data confirms the positive effects of the Iterative Improvement Process on the software development projects and reveals the willingness of software developers to participate in the Iterative Improvement activities due to the rapid and visible changes in their working practices. Copyright © 2006 John Wiley & Sons, Ltd.
Structures and Functional Properties of Starch From Seeds of Three Soybean (Glycine max (L.) Merr.) Varieties*
Authors: Stevenson David G. , Doorenbos Russell K. , Jane Jay‐lin , Inglett George E.
Published: October 2006

Structures and functional properties of starch from high‐protein, lipoxygenase‐free and low‐linolenic acid soybean variety seeds collected 20 d prior to harvest were investigated. Soybean starches exhibit CB‐type X‐ray diffraction patterns, and granule diameters were very small (0.7 to 4 µm). Soybeans, 20 d prior to harvest contained 10.9–11.7% starch (dry basis). Apparent amylose content was 19–22% and absolute amylose content was 11.8–16.2%. Amylopectin weight‐average molar mass ranged from 5.1 to 11.3×108 g/mol. Amylopectin average branch chain‐length, determined by anion‐exchange chromatography with an amyloglucosidase post‐column and pulsed amperometric detector, was very short relative to other starches (20.4–20.9). Onset gelatinization temperature ranged from 52–54°C, and ΔH was 12–13 J/g. Paste viscosity was low relative to other starches, especially peak (81–93 RVU) and final (93–106 RVU) viscosity. The apparent amylose content of the low‐linolenic acid soybean starch was significantly higher than that of high‐protein soybean starch, and absolute amylose content of low‐linolenic acid soybean starch was significantly higher than that of lipoxygenase‐free soybean starch. Based on our results, investigations on whether soybeans with different fatty acid oil composition have different starch structures would be worthwhile. Field replicates for each soybean variety exhibited high variation in starch characteristics, with further differences in starch structures and functional properties likely to be determined once variation is minimized.
Acylation of Starch using Trifluoroacetic Anhydride Promoter
Authors: Yang Byung Y. , Montgomery Rex
Published: October 2006

The use of trifluoroacetic anhydride as a promoter for the acylation of granular starch is reported. Efficient acylation in a homogeneous solution is attained when the carboxylic acid of interest and trifluoroacetic anhydride are added, the latter in at least twice molar excess to the hydroxyl groups of the anhydroglucose residues. The reaction necessitates prior heating of granular starch in acetic acid before the acylation reagent is added. The product is an acylated starch with degrees of substitution (DS) of 2 to 3, as analyzed by gas‐liquid chromatography or high‐pressure liquid chromatography. Lower molar ratios of trifluoroacetic anhydride to the anhydroglucose residue gave lower degree of substitution. Additionally, starch acetates with different degree of substitution are prepared by addition of limited amounts of the acylation reagent or by partial de‐acetylation of starch triacetate with sodium methoxide. Starch esters are prepared from acetic, butanoic, hexanoic, octanoic, palmitic and benzoic acids.
Modulation of Antigenic Phenotype in Cultured Human Osteoblast-like Cells by FGFb, TGFβ1, PDGF-BB, IL-2, IL-1β, LPS and IFNγ
Authors: Pérez E. , García-Martínez O. , Arroyo-Morales M. , Reyes-Botella C. , Ruiz C.
Published: October 2006

Background/Aims

Recent reports demonstrated that osteoblast-like cells can also exert activities directly associated with the immune system (cytokine synthesis, antigen presentation, phagocytosis and stimulation of T lymphocytes). The present study aimed to analyze the effect of Transforming growth factorβ1 (TGFβ1), Fibroblast growth factor basic (FGFb), Platelet-derived growth factor-BB (PDGF-BB), Interleukin-1β (IL-1β), Interleukin-2 (IL-2), Lipopolysaccharide (LPS) and Interferon-γ (IFNγ) on the expression on osteoblast-like cells of antigens involved in antigen presentation.

Methods

Flow cytometry was used to investigate whether the growth factors FGFb, TGFβ1, PDGF-BB, IL-2, IL-1β, LPS and IFNγ modulate the expression on cultured human osteoblast-like cells of different antigens involved in antigen-presentation and T cell activation.

Results

TGFβ1 treatment significantly reduced the expression of CD54 and CD86. IL-1β treatment significantly enhanced the expression of CD54, CD86 and HLA-DR. LPS and IFNγ treatments produced a major increase in CD54, CD80, CD86 and HLA-DR expression. Expression of these antigen-presenting molecules was not significantly modified by FGFb, PDGF-BB or IL-2 treatment.
Sleep‐disordered breathing in patients with symptomatic heart failure A contemporary study of prevalence in and characteristics of 700 patients
Authors: Oldenburg Olaf , Lamp Barbara , Faber Lothar , Teschler Helmut , Horstkotte Dieter , Töpfer Volker
Published: October 2006

Aim:

Evaluation of the prevalence and nature of sleep‐disordered breathing (SDB) in patients with symptomatic chronic heart failure (CHF) receiving therapy according to current guidelines.

Methods and results:

We prospectively screened 700 patients with CHF (NYHA class≥II, LV‐EF≤40%) for SDB using cardiorespiratory polygraphy (Embletta™). Furthermore, echocardiography, cardiopulmonary exercise and 6‐min walk testing were performed. Medication included ACE‐inhibitors and/or AT1‐receptor blockers in at least 94%, diuretics in 87%, β‐blockers in 85%, digitalis in 61% and spironolactone in 62% of patients.

SDB was present in 76% of patients (40% central (CSA), 36% obstructive sleep apnoea (OSA)). CSA patients were more symptomatic (NYHA class 2.9±0.5 vs. no SDB 2.57±0.5 or OSA 2.57±0.5; p<0.05) and had a lower LV‐EF (27.4±6.6% vs. 29.3±2.6%, p<0.05) than OSA patients. Oxygen uptake (VO2) was lowest in CSA patients: predicted peak VO2 57±16% vs. 64±18% in OSA and 63±17% in no SDB, p<0.05. 6‐min walking distances were 331±111m in CSA, 373±108m in OSA and 377±118m in no SDB (p<0.05).

Conclusions:

This study confirms the high prevalence of SDB, particularly CSA in CHF patients. CSA seems to be a marker of heart failure severity.
Effects of combined deferiprone and desferrioxamine iron chelating therapy in β‐thalassemia major end‐stage heart failure
Authors: Porcu Maurizio , Landis Novella , Salis Stefano , Corda Marco , Orrù Pierpaolo , Serra Emanuela , Usai Barbara , Matta Gildo , Galanello Renzo
Published: October 2006

Despite usual iron chelating therapy based on desferrioxamine, patients affected by β‐thalassemia major (β‐TM) often develop progressive heart failure caused by myocardial iron overload, which is the leading cause of mortality within the third decade of life. Heart transplantation is a limited therapeutic option, as very often these patients have multi‐organ iron deposits and infective complications (particularly hepatitis C), secondary to frequent blood transfusions. We report the case of a 26‐year‐old male affected by β‐TM with end‐stage heart failure, who showed a dramatic improvement in symptoms and myocardial function when a new oral iron chelating agent, deferiprone, was added to standard therapy with desferrioxamine.
Computational analysis of plasmepsin IV bound to an allophenylnorstatine inhibitor
Authors: Gutiérrez-de-Terán Hugo , Nervall Martin , Dunn Ben M. , Clemente Jose C. , Åqvist Johan
Published: October 2006

The plasmepsin proteases from the malaria parasite Plasmodium falciparum are attracting attention as putative drug targets. A recently published crystal structure of Plasmodium malariae plasmepsin IV bound to an allophenylnorstatine inhibitor [Clemente, J.C. et al. (2006) Acta Crystallogr. D 62, 246–252] provides the first structural insights regarding interactions of this family of inhibitors with plasmepsins. The compounds in this class are potent inhibitors of HIV‐1 protease, but also show nM binding affinities towards plasmepsin IV. Here, we utilize automated docking, molecular dynamics and binding free energy calculations with the linear interaction energy LIE method to investigate the binding of allophenylnorstatine inhibitors to plasmepsin IV from two different species. The calculations yield excellent agreement with experimental binding data and provide new information regarding protonation states of active site residues as well as conformational properties of the inhibitor complexes.
Phosphoinositide synthesis and degradation in isolated rat liver peroxisomes
Authors: Jeynov Boyan , Lay Dorothee , Schmidt Frank , Tahirovic Sabina , Just Wilhelm W.
Published: October 2006

Analyzing peroxisomal phosphoinositide (PId#) synthesis in highly purified rat liver peroxisomes we found synthesis of phosphatidylinositol 4‐phosphate (PtdIns4P), PtdIns(4,5)P
2 and PtdIns(3,5)P
2. PtdIns3P was hardly detected in vitro, however, was observed in vivo after [32P]‐phosphate labeling of primary rat hepatocytes. In comparison with other subcellular organelles peroxisomes revealed a unique PId pattern suggesting peroxisomal specificity of the observed synthesis. Use of phosphatase inhibitors enhanced the amount of PtdIns4P. The results obtained provide evidence that isolated rat liver peroxisomes synthesize PIds and suggest the association of PId 4‐kinase and PId 5‐kinase and PId 4‐phosphatase activities with the peroxisomal membrane.
Regulation of phosphorylation of tau by cyclin‐dependent kinase 5 and glycogen synthase kinase‐3 at substrate level
Authors: Sengupta Amitabha , Novak Michal , Grundke-Iqbal Inge , Iqbal Khalid
Published: October 2006

Microtubule associated protein tau, which is expressed in six alternatively spliced molecular isoforms in human brain, is abnormally hyperphosphorylated in Alzheimer disease and related tauopathies. Here, we show (i) that GSK‐3α and neither GSK‐3β nor cdk5 can phosphorylate tau at Ser262 and phosphorylation at Ser235 by cdk5 primes phosphorylation at Thr231 by GSK‐3α/β; (ii) that tau isoforms with two N‐terminal inserts (τ4L, τ3L) are phosphorylated by cdk5 plus GSK‐3 at Thr231 markedly more than isoforms lacking these inserts (τ4, τ3); and (iii) that Thr231 is phosphorylated ∼50% more in free tau than in microtubule‐bound tau, and the phosphorylation at this site results in the dissociation of tau from microtubules. These findings suggest that the phosphorylation of tau at Thr231 and Ser262 by cdk5 plus GSK‐3, which inhibits its normal biological activity, is regulated both by its amino terminal inserts and its physical state.
αB‐crystallin competes with Alzheimer's disease β‐amyloid peptide for peptide–peptide interactions and induces oxidation of Abeta‐Met35
Authors: Narayanan Saravanakumar , Kamps Bram , Boelens Wilbert C. , Reif Bernd
Published: October 2006

We find – using solution state NMR spectroscopy – that αB‐crystallin competes efficiently for Aβ monomer–monomer interactions. Interactions between Aβ and αB‐crystallin involve the hydrophobic core residues 17–21 as well as residues 31–32 of Aβ, and thus the same chemical groups which are important for Aβ aggregation. In the presence of αB‐crystallin, Met35 in Aβ becomes efficiently oxidized. In order to quantify the redox properties of the different complexes consisting of Aβ/αB‐crystallin/copper, we suggest an NMR assay which allows to estimate the electrochemical properties indirectly by monitoring the rate of glutathion (GSH) auto‐oxidation. The oxidation of the side chain Met35 in Aβ might account for the increased neurotoxicity and the inability of Aβ to form fibrillar structures, which has been observed previously in the presence of αB‐crystallin [Stege, G.J. et al. (1999) The molecular chaperone αB‐crystallin enhances amyloid‐beta neurotoxicity. Biochem. Biophys. Res. Commun. 262, 152–156.].
Last glacial maximum equilibrium-line altitude and paleo-temperature reconstructions for the Cordillera de Mérida, Venezuelan Andes
Authors: Stansell Nathan D. , Polissar Pratigya J. , Abbott Mark B.
Published: October 2006

The pattern and magnitude of glacier equilibrium-line altitude (ELA) lowerings in the tropics during the last glacial maximum (LGM) are topics of current debate. In the northern tropics, paleo-ELA data are particularly limited, inhibiting the ability to make regional and large-scale paleoclimatic inferences. To improve these records, nine paleo-glaciers in the Venezuelan Andes were reconstructed based on field observations, aerial photographs, satellite imagery and high-resolution digital topographic data. Paleo-glacier equilibrium-line altitudes (ELAs) were estimated using the accumulation-area ratio (AAR) and the area-altitude balance ratio (AABR) methods. During the local LGM in Venezuela (∼ 22,750 to 19,960 cal yr BP), ELAs were ∼ 850 to 1420 m lower than present. Local LGM temperatures were are at least 8.8 ± 2°C cooler than today based on a combined energy and mass-balance equation to account for an ELA lowering. This is greater than estimates using an atmospheric lapse rate calculation, which yields a value of 6.4 ± 1°C cooler. The paleo-glacial data from the Venezuelan Andes support other published records that indicate the northern tropics experienced a greater ELA lowering and possibly a greater cooling than the Southern Hemisphere tropics during the LGM.
A 6000-year record of ecological and hydrological changes from Laguna de la Leche, north coastal Cuba
Authors: Peros Matthew C. , Reinhardt Eduard G. , Davis Anthony M.
Published: October 2006

Laguna de la Leche, north coastal Cuba, is a shallow (≤ 3 m), oligohaline (∼ 2.0–4.5‰) coastal lake surrounded by mangroves and cattail stands. A 227-cm core was studied using loss-on-ignition, pollen, calcareous microfossils, and plant macrofossils. From ∼6200 to ∼ 4800 cal yr BP, the area was an oligohaline lake. The period from ∼ 4800 to ∼ 4200 cal yr BP saw higher water levels and a freshened system; these changes are indicated by an increase in the regional pollen rain, as well as by the presence of charophyte oogonia and an increase in freshwater gastropods (Hydrobiidae). By ∼ 4000 cal yr BP, an open mesohaline lagoon had formed; an increase in salt-tolerant foraminifers suggests that water level increase was driven by relative sea level rise. The initiation of Laguna de la Leche correlates with a shift to wetter conditions as indicated in pollen records from the southeastern United States (e.g., Lake Tulane). This synchronicity suggests that sea level rise caused middle Holocene environmental change region-wide. Two other cores sampled from mangrove swamps in the vicinity of Laguna de la Leche indicate that a major expansion of mangroves was underway by ∼ 1700 cal yr BP.
World Englishes and the American tongue
Authors: Anchimbe Eric A.
Published: October 2006

Are the other varieties of English under threat from the United States? This paper reviews the place of the United States of America (her English and culture) in the contemporary world, especially with regard to the spread and use of the English language. World War II and its aftermath raised America to the height of political, economic, commercial, technological strength which saw the transformation of English from being a reserve of the British Isles and their queen, to a code of international linguistic transaction. English today is no longer just spreading world-wide, but is overwhelmingly adopting a predominant American touch, given the pride and prestige of the American lifestyle and pop culture. This paper therefore observes that in a quite foreseeable future the world Englishes will gradually subsume their heterogeneous identities into the sweeping current of the American variety of English.
An understanding of ‘China English’ and the learning and use of the English language in China
Authors: Xiaoxia Cui
Published: October 2006

Some perspectives from an English educator. Since the implementation of the policy of reform and opening up, and China's entry into the World Trade Organization (WTO), China has been gaining strength quickly in the international, political, and economic arena. Globalization has led to China taking part in varous kinds of international cooperation and exchange. At the same time, globalization and the Internet have been providing a novel context in which to use English as an international language. Under such circumstances, the Chinese are using more English than ever before, and China English is being simultaneously localized and globalized. Like any other language, China English is a living entity or organism that is not only growing and progressing in the ‘Information Age’, but is also making a contribution that is enriching and developing world Englishes at large. Indeed, China English now plays a significant role in increasing international understanding and cooperation within the WTO and in the whole world.
Hiring native-speaking English teachers in East Asian countries
Authors: Jeon Mihyon , Lee Jiyoon
Published: October 2006

ENGLISH is the most commonly used language in the world. As it has become the language that provides access to higher education and job opportunities, and has become almost exclusively the language of diplomatic discussion and business negotiation (cf. English APEC Strategic Plan, 2004), there has been a growing interest in hiring native-speaking English Teachers (NSETs) in Asian countries. The aim of this paper is to report policies and practices that invite NSETs to Asian countries, including China and Hong Kong, Taiwan, Japan, and South Korea, with emphasis on public education sectors. Through surveying both similar policies and the implementation of policies in several Asian countries, we seek to find practical suggestions for hiring NSETs. We survey policy goals, recruitment procedures, and the qualifications of NSETs. The analysis will be based on the premise that ‘language planning cannot be understood without reference to its social contexts’ (Cooper, 1989:3).
Maintaining Neutrality between the Two German States: Finland and Divided Germany until 1973
Authors: HENTILÄ SEPPO
Published: October 2006

After the end of the Second World War, when Finland sought to redefine its position vis-à-vis Germany, negotiations were dogged by the fact that Finland had been a close ally of Hitler's Germany in 1941–4 in the war against the USSR. In April 1948 Finland signed a Treaty of Friendship, Co-operation and Mutual Assistance (FCMA) with the USSR, in which the military articles were based on the need to counter a potential German attack on the Soviets via Finland's territory. Finland's international position was so difficult that it became the only country in the world that did not establish full diplomatic relations with either of the German states. It was also the only country in the world to pursue a policy of absolute neutrality vis-à-vis both Germanys. When the Finnish government offered to host the Conference on Security and Co-operation in Europe (CSCE) in May 1969, its main preoccupation was the German question, and it succeeded in fending off Soviet pressure to recognise the GDR. In 1973, with West German Federal Chancellor Willy Brandt's Neue Ostpolitik easing tensions with regard to the German question, Finland was able to establish full diplomatic relations with both German states simultaneously.
Wirksamkeit verhaltenstherapeutischer Gruppenprogramme bei Kindern mit Aufmerksamkeitsdefizit- und Hyperaktivitätsstörungen (ADHS)
Authors: Dreisörner Thomas
Published: October 2006

Zusammenfassung. In der Studie wurde die Wirksamkeit von kognitiv-verhaltenstherapeutischen Programmen für Kinder mit Aufmerksamkeitsdefizit- und Hyperaktivitätsstörungen (ADHS) untersucht. 96 Kinder zwischen sieben und 13 Jahren nahmen in drei Zentren an der Untersuchung teil. 31 Kinder absolvierten gemeinsam mit ihren Eltern ein 15-wöchiges THOP-Training (Therapieprogramm für Kinder mit hyperkinetischem und oppositionellem Trotzverhalten), 34 ein 15-wöchiges Training für aufmerksamkeitsgestörte Kinder, 15 Kinder das Basistraining. 16 Kinder bildeten eine Wartegruppe. Für das Training mit aufmerksamkeitsgestörten Kindern konnten nur leichte Verbesserungen bei der kognitiven Hemmungskontrolle und der Nutzung des phonologischen Arbeitsgedächtnisses nachgewiesen werden, die ADHS-Symptome verminderten sich kaum. Die Verbesserungen durch das Basistraining waren stärker als durch das kombinierte Basis- und Strategietraining. Mit dem THOP-Training konnten tendenziell die Aufmerksamkeitsleistungen gesteigert werden. Insbesondere ließ sich die familiäre Interaktion verbessern. Die besten Erfolge erzielten Kinder, die gleichzeitig mit Methylphenidat behandelt wurden.
Acoustic emission and velocities associated with the formation of compaction bands in sandstone
Authors: Fortin Jérôme , Stanchits Sergei , Dresen Georg , Guéguen Yves
Published: October 2006

A series of laboratory experiments has been conducted in which three‐dimensional (3‐D) locations of acoustic emissions (AE) were recorded and used to analyze the development of compaction bands in Bleurswiller sandstone, which has a porosity of 25%. Results were obtained for saturated samples deformed under triaxial compression at three different confining pressures (60, 80, and 100 MPa), a pore pressure of 10 MPa, and room temperature. We recorded acoustic emissions, compressional and shear wave velocities, and porosity reduction under hydrostatic condition and under triaxial loading conditions at a constant axial strain rate. Our results show that seismic velocities and their amplitude increased during hydrostatic pressure build up and during initial axial loading. During shear‐enhanced compaction, axial and radial velocities decreased progressively, indicating an increase of stress‐induced damage in the rock. In experiments performed at confining pressures of 80 and 100 MPa during triaxial loading, acoustic emissions were localized in clusters. During progressive loading, AE clusters grow horizontally, perpendicular to the maximum principal stress direction, indicating formation of compaction bands throughout the specimens. Microstructural analysis of deformed specimens confirmed a spatial correspondence of AE clusters and compaction bands. For the experiment performed at a confining pressure of 60 MPa, AE locations and microstructural observations show symmetric compaction bands inclined to the cylinder axis of the specimen, in agreement with predictions from recent theoretical models.
Sensitivity of the North Pacific oxygen minimum zone to changes in ocean circulation: A simple model calibrated by chlorofluorocarbons
Authors: van Geen A. , Smethie W. M. , Horneman A. , Lee H.
Published: October 2006

Chlorofluorocarbon (CFC) data collected in 1999 at 11 stations along the western margin of Baja California indicate that the oxygen‐minimum zone (OMZ) of the area is ventilated from the far North Pacific on decadal timescales. The new data are combined with existing CFC data to constrain a one‐dimensional advection‐diffusion model that simulates changes in water column properties on the σΘ = 26.80 density surface along the path of ventilation. The results show that the penetration of CFCs into the OMZ off Baja California can be explained by slow advection and rapid isopycnal mixing from the southern margin of the Alaskan Gyre. The deficit in dissolved oxygen along the same path relative to conservative behavior is modeled with a consumption term that is the product of a single rate constant and the dissolved oxygen concentration. The model is used to show that very different oceanographic conditions must have prevailed in the North Pacific between 15 and 13 kyr ago, when water containing less than 5 μmol kg−1 oxygen impinged on a portion of the western margin of North America that was considerably expanded compared to today. To match the distribution of oxygen from the presence of laminations in a series of sediment cores, the least extreme scenario combines a 2.5‐fold decrease in advection and diffusion along the current flow path, a 2.5‐fold reduction in the oxygen content of ventilated waters of the central North Pacific, and a 2.5‐fold increase in the rate constant for oxygen consumption rate, presumably linked to a proportional increase in surface productivity.
Thermochronology of mineral grains in the Red and Mekong Rivers, Vietnam: Provenance and exhumation implications for Southeast Asia
Authors: Clift Peter D. , Carter Andrew , Campbell Ian H. , Pringle Malcolm S. , Van Lap Nguyen , Allen Charlotte M. , Hodges Kip V. , Tan Mai Thanh
Published: October 2006

Sand samples from the mouths of the Red and Mekong Rivers were analyzed to determine the provenance and exhumation history of their source regions. U‐Pb dating of detrital zircon grains shows that the main sources comprise crust formed within the Yangtze Craton and during the Triassic Indosinian Orogeny. Indosinian grains in the Mekong are younger (210–240 Ma) than those in the Red River (230–290 Ma), suggesting preferential erosion of the Qiangtang Block of Tibet into the Mekong. The Red River has a higher proportion of 700–800 Ma grains originally derived from the Yangtze Craton. 40Ar/39Ar dating of muscovite grains demonstrates that rocks cooled during the Indosinian Orogeny are dominant in both rivers, although the Mekong also shows a grain population cooling at 150–200 Ma that is not seen in the Red River and which is probably of original Qiangtang Block origin. Conversely, the Red River contains a significant mica population (350–500 Ma) eroded from the Yangtze Craton. High‐grade metamorphic rocks exposed in the Cenozoic shear zones of southeast Tibet‐Yunnan are minority sources to the rivers. However, apatite and zircon fission track ages show evidence for the dominant sources, especially in the Red River, only being exhumed through the shallowest 5–3 km of the crust since ∼25 Ma. The thermochronology data are consistent with erosion of recycled sediment from the inverted Simao and Chuxiong Basins, from gorges that incise the eastern flank of the plateau. Average Neogene exhumation rates are 104–191 m/Myr in the Red River basin, which is within error of the 178 ± 35 m/Myr estimated from Pleistocene sediment volumes. Sparse fission track data from the Mekong River support the Ar‐Ar and U‐Pb ages in favoring tectonically driven rock uplift and gorge incision as the dominant control on erosion, with precipitation being an important secondary influence.
Observation of Luzon Strait transport
Authors: Tian Jiwei , Yang Qingxuan , Liang Xinfeng , Xie Lingling , Hu Dunxin , Wang Fan , Qu Tangdong
Published: October 2006

Using recently collected current and hydrographic data, we provide a high resolution picture of the subinertial flow and estimate the volume transport through the Luzon Strait. The distribution of the subinertial flow shows a strong westward flow around 100 m in the northern part of the Luzon Strait, while the eastward flow is confined to the deeper layers, mostly at depths around 1000 m. The total volume transport is estimated to be 6 ± 3 Sv during the period of observations from October 4 to 16, 2005. The observations also confirm that the Luzon Strait transport has a sandwiched vertical structure. The net westward volume transport in the deep (>1500 m) layer of the Luzon Strait reaches 2 Sv.
Time evolutions of various radiative forcings for the past 150 years estimated by a general circulation model
Authors: Takemura Toshihiko , Tsushima Yoko , Yokohata Tokuta , Nozawa Toru , Nagashima Tatsuya , Nakajima Teruyuki
Published: October 2006

Time series of the instantaneous radiative forcings for main anthropogenic and natural forcing agents from the year 1850 to 2000 are evaluated at the Earth's surface as well as at the tropopause with an atmospheric general circulation model. This evaluation corresponds to a simulation of 20th century climate with a synthetic coupled atmosphere‐ocean general circulation model. The evaluation indicates that the positive radiative forcing at the tropopause rapidly increases from 1910 to 1950 and after 1970 principally due to long‐lived greenhouse gases, while the negative radiative forcing at the surface sharply increases between 1955 and 1965 mainly due to the aerosol direct and indirect effects. This study suggests that a simultaneous analysis of changing rates of the radiative forcing both at the tropopause and surface can explain tendencies of changes in the surface air temperature.
Climate change and interannual variability of precipitation in South America
Authors: Grimm Alice M. , Natori Angela A.
Published: October 2006

We analyze the interannual variability of the summer monsoon rainy season in South America and its relationship with SST as simulated by the ocean‐atmosphere coupled model ECHAM5‐OM for present‐day conditions (1961–1990) and future A2 emission scenario (2071–2100). The first mode of model precipitation variability, both in spring and summer, is associated with El Niño‐Southern Oscillation (ENSO). In both seasons it features a dipole of anomalies between northern and southeastern South America. These modes correspond, with some differences, to the first variability mode of observed spring precipitation, and to the third variability mode of observed summer precipitation, which are also associated with ENSO. The relationship between ENSO events and precipitation variability in southeastern South America weakens for the A2 scenario, especially in spring, which is presently the season with strongest ENSO‐related impact. The weakened teleconnection is probably due to the reduction of the SST subtropical latitudinal gradient in the ENSO mode.
Green's function retrieval by cross‐correlation in case of one‐sided illumination
Authors: Wapenaar Kees
Published: October 2006

The cross‐correlation of acoustic wave fields at two receivers yields the exact Green's function between these receivers, provided the receivers are surrounded by sources on a closed surface. In most practical situations the sources are located on an open surface and as a consequence the illumination of the receivers is one‐sided. In this Letter we discuss the conditions for accurate Green's function retrieval for the situation of one‐sided illumination. It appears that the Green's function retrieval method benefits from the fact that the earth is inhomogeneous, without relying on assumptions about disorder.
Dynamics of ionization of H2 by Ne*(P3) investigated by electron spectroscopy
Authors: Noroski Joseph H. , Siska P. E.
Published: October 2006

The Penning ionization reaction Ne*(2p53sP3)+H2→[NeH2]++e− has been studied in crossed supersonic molecular beams with electron-energy analysis at four collision energies E=1.83, 2.50, 3.16, and 3.89kcal∕mol. The electron kinetic-energy spectra, which directly reflect the ionizing transition region, show resolved peaks assignable to v′=0–4 of H2+. The vibrational populations deviate systematically from Franck-Condon behavior, suggesting that the discrete-continuum coupling increases with H2 bond stretching. Each peak displays both increasing breadth and increasing blueshift with increasing E, and the blueshift also increases with increasing v′. The first two properties are consistent with a predominantly repulsive excited-state potential-energy surface, while the last is speculated to be a reflection of the rHH dependence of the ionic surface. Quantum scattering calculations based on ab initio potential surfaces for the excited and ionic states in spherical and infinite-order-sudden rigid rotor approximations are in semiquantitative agreement with the measurements. Discrepancies suggest changes in the imaginary, absorptive part of the excited surface, which probably can be best effected by multiproperty fitting calculations.
Recent advances in crossed-beam studies of bimolecular reactions
Authors: Liu Kopin
Published: October 2006

A critical overview of the recent progress in crossed-beam reactive scattering is presented. This review is not intended to be an exhaustive nor a comprehensive one, but rather a critical assessment of what we have been learning about bimolecular reaction dynamics using crossed molecular beams since year 2000. Particular emphasis is placed on the information content encoded in the product angular distribution—the trait of a typical molecular beam scattering experiment—and how the information can help in answering fundamental questions about chemical reactivity. We will start with simple reactions by highlighting a few benchmark three-atom reactions, and then move on progressively to the more complex chemical systems and with more sophisticated types of measurements. Understanding what cause the experimental observations is more than computationally simulating the results. The give and take between experiment and theory in unraveling the physical picture of the underlying dynamics is illustrated throughout this review.
Negative index of refraction: A subclass of electromagnetically metamorphic materials
Authors: Liu Yunhong , Alexópoulos Nicólaos G.
Published: October 2006

Electromagnetic metamorphism is defined as the complete transformation of a scattering object of fixed shape and dimensions from one electromagnetic state such as from a perfect electric conductor (PEC) to a distinctly different state such as a perfect magnetic conductor. At a single frequency every scatterer has five metamorphic states. All smooth scattering objects regardless of shape exhibit a similar universal metamorphic response in the backscattering direction. The effective parameters ne and ze are examined on the composite which is constructed by layered actively loaded PEC circular ring medium for certain metamorphic states. The structure shows a negative index of refraction.