bluuebunny/crossref_metadata_2025 huggingface dataset:
Target recognition and synaptogenesis by motor axons: responses to the sidestep protein
Authors: de Jong Samanta , Cavallo Jaime A. , Rios Carl D. , Dworak Heather A. , Sink Helen
Published: December 2004

Sidestep (Side) is a pivotal molecular player in embryonic motor axon pathfinding. But questions about its functional repertoire remain: (i) can Side permanently overturn targeting preferences? (ii) does it promote synaptogenesis, and (iii) can Side facilitate synaptic stabilization? To address these questions, Side was temporally and spatially misexpressed and the visible consequences for neuromuscular junction morphology were assessed. When Side was misexpressed either broadly or selectively in muscles during targeting in a wildtype background motor axon targeting preferences were permanently overturned. However the misexpression of Side in all muscles post‐targeting neither changed synapse morphology, nor compensated for a lack of the synapse‐stabilizing protein Fasciclin II (FasII). Rather Side appears to be dependent on FasII, instead of on intrinsic ability, for sustaining targeting changes. We propose that Side helps to bring motor axons to their correct muscle targets and promotes synaptogenesis, then FasII serves to stabilize the synaptic contacts.
Radical versus conservative surgery for vulvar carcinoma
Authors: Arvas M. , Köse F. , Gezer A. , Demirkiran F. , Tulunay G. , Kösebay D.
Published: December 2004

Objective

The comparison of the radical and conservative surgical approaches for vulvar carcinoma in relation to the rate of recurrence and complications.

Methods

The records of invasive vulvar carcinoma cases were retrospectively reviewed in İstanbul University, Cerrahpaşa School of Medicine, Gynecologic Oncology Division and Social Insurance Institution, Ankara Maternity Hospital, Gynecologic Oncology Department. Surgically treated cases with squamous histology were divided into radical vulvectomy and conservative procedures groups and were compared with respect to recurrence, complications, and disease‐free survival.

Results

One hundred thirteen cases of invasive vulvar carcinoma cases were of squamous histopathology and 92 of these were surgically treated. The rate of local recurrence was lower in the radical vulvectomy group (25%) compared to conservative procedures groups (42.5%; p>0.05). The complication rates were comparable between the radical vulvectomy and conservative procedures groups (32.7% versus 35%, respectively; p>0.05). At the end of five years of the follow‐up, the disease‐free survival rates were 51.5% in radical vulvectomy group versus 35.7% in conservative procedures group (p>0.05).

Conclusion

The rate of recurrence, complication, and disease‐free survival are similar for the radical vulvectomy and the conservative procedures. Deciding the surgical strategy for vulvar carcinoma should depend on the experience of the surgeon for the short‐term adequate results.
Effects of age on the repair ability of mesenchymal stem cells in rabbit tendon
Authors: Dressler M. R. , Butler D. L. , Boivin G. P.
Published: December 2004

Successful tissue engineered repair in the aging adult requires an abundant source of autologous, multipotent mesenchymal stem cells (MSCs). Although the number of bone marrow‐derived MSCs declines dramatically with aging, their effectiveness in repair with increasing age has not been studied. We tested the hypothesis that MSCs harvested from geriatric rabbits would not repair patellar tendon defects as well as MSCs harvested from younger adult rabbits. In a novel within‐subjects experiment, autologous MSCs were isolated from 1‐year old rabbits, culture expanded, and cryogenically preserved. After housing the rabbits for 3 years, MSCs were re‐harvested from the 4‐year old rabbits and expanded. Five hundred thousand thawed and fresh MSCs were each separately mixed with type I collagen gel (333.3 × 103 cells/mg collagen) 24 h before surgery, and the resulting constructs implanted in bilateral full‐length central third tendon defects. Twelve weeks post‐surgery, the bone‐tendon repair‐bone units were failed in tension. Intra‐animal (paired) comparisons between repair tissue treated with 1‐year old MSCs and repair tissue treated with 4‐year old MSCs resulted in no significant differences (α = 0.05) in material properties including maximum stress (10.8 MPa vs. 9.9 MPa; p = 0.762), modulus (139.8 MPa vs. 146.2 MPa; p = 0.914), and strain energy density (0.52 Nmm/mm3 vs. 0.53 Nmm/mm3; p = 0.966). Despite an age‐related trend, there were also no significant differences in structural properties including maximum force (62.9 N vs. 27.0 N; p = 0.070), stiffness (24.9 N/mm vs. 12.0 N/mm; p = 0.111), and strain energy (87.2 Nmm vs. 31.4 Nmm; p = 0.061). A subset of the rabbits (n = 4 1 yrMSC, n = 2 4 yrMSC) showed the presence of ectopic bone in the repair region and were not included in the mechanical analyses. We conclude that in the rabbit model MSCs do not lose their benefit as a tendon repair therapy with aging and that MSCs can be cryogenically stored for 3 years and still effectively repair soft tissue injuries. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Healing of reamed glenoid bone articulating with a metal humeral hemiarthroplasty: A canine model
Authors: Matsen Frederick A. , Clark John M. , Titelman Robert M. , Gibbs Kristi M. , Boorman Richard S. , Deffenbaugh Daren , Korvick Donna L. , Norman Anthony G. , Ott Susan M. , Parsons Ira M. , Sidles John A.
Published: December 2004

This study characterizes the healing response of the glenoid after spherical reaming and prosthetic humeral head replacement in a canine model of glenohumeral hemiarthroplasty. The right glenoid of twelve skeletally mature female dogs was reamed to a uniform radius of curvature, removing all cartilage down to bleeding subchondral bone. The glenoid was not resurfaced. The humeral head was replaced with a stemmed metal prosthesis. Post‐surgery, the operated limbs were immobilized for seven days, with motion allowedad libitumthereafter. Fluorescent bone labels were administered to identify bone formation. These procedures were not complicated by instability, infection or death. Six animals were euthanized at 10 week and six more at 24 week. The intact gleno‐humeral joints were evaluated by gross examination, assessment of glenoid concavity, and light microscopy of methylmethacrylate sections. At 10 week, vascular fibrous tissue partially covered the glenoid, maintaining a concave surface congruent with the prosthetic humeral head. New bone formed at the margin of the glenoid, and the density of the periarticular trabecular bone increased. At 24 week, the healing was more advanced; thick fibrocartilaginous tissue covered the entire glenoid surface.

The results demonstrate that spherical glenoid reaming produced a consistent healing response characterized by remodelling of the reamed bony concavity to a congruent, living, smooth, securely attached interface articulating with the humeral prosthesis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Increase in sensory neuropeptides surrounding the Achilles tendon in rats with adjuvant arthritis
Authors: Bring Daniel K.‐I. , Heidgren Marie‐Louise , Kreicbergs Andris , Ackermann Paul W.
Published: December 2004

The Achilles tendon in rats with adjuvant arthritis was analyzed by radioimmunoassay (RIA) and semi‐quantitative immunohistochemistry for the occurrence of two sensory neuropeptides, substance P (SP) and calcitonin gene related peptide (CGRP), and a sensory modulating peptide, galanin (GAL). The tissue concentration of SP and CGRP in the Achilles tendon and its envelope, i.e. the paratenon and bony insertion, as assessed by RIA was increased by 22% and 71%, respectively, compared to normal controls, whereas the level of GAL was unchanged.

Semi‐quantitative immunohistochemistry applied to different regions of the tendon in arthritic rats disclosed an increased occurrence of SP and CGRP positive nerve fibers in the paratenon and bone tendinous junction, whereas GAL fibers were only increased at the bone tendinous junction. Notably, neither neuropeptides nor inflammatory cells were seen in the tendon proper. The increased occurrence of SP and CGRP in the tendon envelope presumably reflects inflammatory actions, whereas that of GAL implies an endogenous anti‐inflammatory response.

The observed SP and CGRP upregulation in the paratenon and bony insertion suggests a pathophysiological role in paratenonitis and enthesitis often seen in patients with rheumatoid arthritis. Presumably Achillodynia originates in the tendon envelope rather than the tendon proper. The observations could be used to define new pharmacological targets for mitigating symptoms from tendons in rheumatoid arthritis and possibly also in other disorders. Whether a neuronal pathogenic mechanism underlies tendon overuse disorders in non‐arthritic tendinopathies and the development of degeneration, i.e. tendinosis, remains to be studied. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Lymphocyte responses in patients with total hip arthroplasty
Authors: Hallab Nadim James , Anderson Shelley , Stafford Tiffany , Glant Tibor , Jacobs Joshua J.
Published: December 2004

How lymphocyte‐mediated metal sensitivity affects orthopaedic implant performance remains poorly understood. Do patients with implants exhibit elevated lymphocyte reactivity to metals and is this reactivity more generalized or more implant‐alloy specific? We investigated these questions by measuring lymphocyte responses to implant metals (Cr+3, Co+2, Ni+2 at 0.1 mM, and Ti+4 at 0.001 mM) in six subject groups: Group 1a = young controls, Group 1b = age matched controls, Group 2a = subjects with osteoarthritis (OA) and no history of metal sensitivity, Group 2b = OA subjects with history of metal sensitivity, Group 3a = total hip arthroplasty (THA) subjects with no to mild radiographic osteolysis, and Group 3b = THA subjects with moderate osteolysis. Lymphocyte proliferation, using Lymphocyte Transformation Testing (LTT), and cytokine release provided quantitative reactivity measurement, where a stimulation index of >2 indicated metal sensitivity. OA subjects with a history of metal sensitivity (Group 2b) were more metal reactive to Ni than any other group, as expected (66% incidence and Stimulation Index >20). However, THA subjects (Groups 3a & b) were >3 fold more reactive to Cr (p < 0.04), than were controls (Groups 1a & b) or OA subjects (Groups 2a & b). THA subjects with moderate vs mild osteolysis (Group 3b vs 3a) were more reactive to Co (43% vs 0% incidence). Only osteolytic THA subjects demonstrated increased cytokine responses with >two‐fold (p <0.05) increases in soluble interferon‐γ (IFN‐γ) and interleukin‐2 (IL‐2) levels in response to Cr challenge. This elevated incidence and averaged level of lymphocyte reactivity supports a metal‐specific adaptive immune response and suggests involvement in the pathogenesis of poor implant performance, e.g. aseptic osteolysis. © 2004 Orthopaedic Research Society. Published by Elsevier Ltd. All rights reserved.
Relative sea-level history from the Lambert Glacier region, East Antarctica, and its relation to deglaciation and Holocene glacier readvance
Authors: Verleyen Elie , Hodgson Dominic A. , Milne Glenn A. , Sabbe Koen , Vyverman Wim
Published: December 2004

We present a relative sea-level (RSL) history, constrained by AMS radiocarbon-dated marine–freshwater transitions in isolation basins from a site adjacent to the Lambert Glacier, East Antarctica. The RSL data suggest an initial ice retreat between c. 15,370 and 12,660 cal yr B.P Within this period, meltwater pulse IA (mwp IA, between c. 14,600–14,200 and 14,100–13,700 cal yr B.P.) occurred; an exceptionally large ice melting event, inferred from far-field sea-level records. The RSL curve shows a pronounced highstand of approximately 8 m between c. 7570–7270 and 7250–6950 cal yr B.P. that is consistent with the timing of the RSL highstand in the nearby Vestfold Hills. This is followed by a fall in RSL to the present. In contrast to previous findings, the isolation of the lakes in the Larsemann Hills postdates the isolation of lakes with similar sill heights in the Vestfold Hills. An increase in RSL fall during the late Holocene may record a decline in the rate of isostatic uplift in the Larsemann Hills between c. 7250–6950 and 2847–2509 cal yr B.P., that occurred in response to a documented mid-Holocene glacier readvance followed by a late-Holocene retreat.
Fluorimetric estimation of the concentration of NADH from human blood samples
Authors: Uppal Abha , Ghosh Nirmalya , Datta Anindya , Gupta Pradeep Kumar
Published: December 2004

We report the quantitative fluorimetric estimation of the concentration of NADH in human blood samples. To measure both free and bound NADH, the 340‐nm‐excited fluorescence spectra was recorded from blood samples to which SDS was added. Diffuse reflectance and the transmittance spectra of the same sample were also recorded over the wavelength range 340–650 nm. These measurements were used to correct the measured fluorescence spectra for the wavelength‐dependent reduction in fluorescence due to absorption and scattering in the blood sample. NADH concentrations estimated using the corrected fluorescence spectra were found to be in reasonable agreement with the concentrations estimated by the biochemical method.
Biological effect of irradiated chitosan on plants in vitro
Authors: Luan Le Q. , Ha Vo T. T. , Nagasawa Naotsugu , Kume Tamikazu , Yoshii Fumio , Nakanishi Tomoko M.
Published: December 2004

For degradation of chitosan, chitosan with an 80% degree of deacetylation and a weight‐average molecular mass (Mw) of approx. 48 kDa was irradiated with γ‐rays at doses up to 200 kGy in a 10% (w/v) solution. The Mw of chitosan was reduced from 48 to 9.1 kDa by irradiation. The characteristics of irradiated chitosan were analysed by using Fourier‐transform IR spectroscopy and an elemental analyser. The amino group was found to be stable, whereas the C‐O‐C group decreased with increase in the dose. The product of chitosan irradiated at 100 kGy with an Mw of approx. 16 kDa showed the strongest growth promotion effect on plants in vitro. For shoot culture, supplementation with irradiated chitosan increased the fresh biomass of shoot clusters (7.2–17.0%) as well as the shoot multiplication rate (17.9–69.0%) for Chrysanthemum morifolium (florist's chrysanthemum), Limonium latifolium (limonium or sea‐lavender), Eustoma grandiflorum (lisianthus, tulip gentian or Texas bluebell) and Fragaria ananassa (modern garden strawberry). The optimum concentrations of irradiated chitosan were found to be approx. 70–100 mg/l for chrysanthemum, 50–100 mg/l for lisianthus and 30–100 mg/l for limonium. For the plantlet culture, the optimum concentrations were found to be approx. 100 mg/l for chrysanthemum, 30 mg/l for lisianthus, 40 mg/l for limonium and 50 mg/l for strawberry. Supplementation with optimum concentrations of irradiated chitosan resulted in a significant increase in the fresh biomass (68.1% for chrysanthemum, 48.5% for lisianthus, 53.6% for limonium and 26.4% for strawberry), shoot height (19.4% for chrysanthemum, 16.5% for lisianthus, 33.9% for limonium and 25.9% for strawberry) and root length (40.6% for chrysanthemum, 66.9% for lisianthus, 23.4% for limonium and 22.6% for strawberry). In addition, treatment with irradiated chitosan enhanced the activity of chitosanase in treated plants and also improved the survival ratio and growth of the transferred plantlets acclimatized for 10–30 days under greenhouse conditions.
Influence of culture conditions on the N‐glycosylation of a monoclonal antibody specific for recombinant hepatitis B surface antigen
Authors: Cabrera Gleysin , Cremata José A. , Valdés Rodolfo , García Rossana , González Yanelys , Montesino Raquel , Gómez Héctor , González Marcos
Published: December 2004

MAbs (monoclonal antibodies) are becoming increasingly important as diagnostic tools for pharmaceutical biotechnology, and hence it is crucial that they are produced under controlled conditions to assure their consistency and reproducibility, not only in terms of protein sequence and bioactivity, but also in terms of post‐translational modifications, e.g. for N‐glycosylation. Hybridoma CB.Hep‐1, which secretes an IgG2b mAb, was cultured in vivo in ascites and in vitro in static‐flask, spinner‐flask, dialysis‐membrane and perfusion systems using protein‐free, low‐serum‐containing medium (1% foetal‐calf serum) and high‐serum‐containing medium (8% foetal‐calf serum). These CB.Hep‐1 mAbs were fully characterized, and insignificant differences in the affinity constant were observed. Glycosylation profiling was performed by labelling the N‐glycans released by peptide N‐glycosidase F with either of the fluorophore tags 8‐aminonaphthalene‐1,3,6‐trisulphonic acid and 4‐aminobenzoic acid. The mAb produced in vivo showed two major biantennary‐complex‐type N‐glycans: monogalactosylated, core‐fucosylated and agalactosylated, core‐fucosylated. The mAbs produced in vitro in static flasks and spinner flasks were not significantly influenced by the serum content in the culture media and showed a higher degree of N‐glycan galactosylation compared with those produced in mouse‐ascites, hollow‐fibre and membrane systems. The monogalactosylated, core‐fucosylated structure was the most abundant N‐glycan except for those produced in ascites and hollow fibres, where the agalactosylated, core‐fucosylated glycoform was the major specie. MAbs produced in high‐cellular‐yield systems displayed greater galactosylation heterogeneity influenced by changes in culture media.
The coenzyme specificity of Candida tenuis xylose reductase (AKR2B5) explored by site-directed mutagenesis and X-ray crystallography
Authors: PETSCHACHER Barbara , LEITGEB Stefan , KAVANAGH Kathryn L. , WILSON David K. , NIDETZKY Bernd
Published: December 2004

CtXR (xylose reductase from the yeast Candida tenuis; AKR2B5) can utilize NADPH or NADH as co-substrate for the reduction of D-xylose into xylitol, NADPH being preferred approx. 33-fold. X-ray structures of CtXR bound to NADP+ and NAD+ have revealed two different protein conformations capable of accommodating the presence or absence of the coenzyme 2′-phosphate group. Here we have used site-directed mutagenesis to replace interactions specific to the enzyme–NADP+ complex with the aim of engineering the co-substrate-dependent conformational switch towards improved NADH selectivity. Purified single-site mutants K274R (Lys274→Arg), K274M, K274G, S275A, N276D, R280H and the double mutant K274R–N276D were characterized by steady-state kinetic analysis of enzymic D-xylose reductions with NADH and NADPH at 25 °C (pH 7.0). The results reveal between 2- and 193-fold increases in NADH versus NADPH selectivity in the mutants, compared with the wild-type, with only modest alterations of the original NADH-linked xylose specificity and catalytic-centre activity. Catalytic reaction profile analysis demonstrated that all mutations produced parallel effects of similar magnitude on ground-state binding of coenzyme and transition state stabilization. The crystal structure of the double mutant showing the best improvement of coenzyme selectivity versus wild-type and exhibiting a 5-fold preference for NADH over NADPH was determined in a binary complex with NAD+ at 2.2 Å resolution.
Ribosomal protein L7a binds RNA through two distinct RNA-binding domains
Authors: RUSSO Giulia , CUCCURESE Monica , MONTI Gianluca , RUSSO Annapina , AMORESANO Angela , PUCCI Pietro , PIETROPAOLO Concetta
Published: December 2004

The human ribosomal protein L7a is a component of the major ribosomal subunit. We previously identified three nuclear-localization-competent domains within L7a, and demonstrated that the domain defined by aa (amino acids) 52–100 is necessary, although not sufficient, to target the L7a protein to the nucleoli. We now demonstrate that L7a interacts in vitro with a presumably G-rich RNA structure, which has yet to be defined. We also demonstrate that the L7a protein contains two RNA-binding domains: one encompassing aa 52–100 (RNAB1) and the other encompassing aa 101–161 (RNAB2). RNAB1 does not contain any known nucleic-acid-binding motif, and may thus represent a new class of such motifs. On the other hand, a specific region of RNAB2 is highly conserved in several other protein components of the ribonucleoprotein complex. We have investigated the topology of the L7a–RNA complex using a recombinant form of the protein domain that encompasses residues 101–161 and a 30mer poly(G) oligonucleotide. Limited proteolysis and cross-linking experiments, and mass spectral analyses of the recombinant protein domain and its complex with poly(G) revealed the RNA-binding region.
Zinc- and iron-dependent cytosolic metallo-β-lactamase domain proteins exhibit similar zinc-binding affinities, independent of an atypical glutamate at the metal-binding site
Authors: SCHILLING Oliver , VOGEL Andreas , KOSTELECKY Brenda , NATAL da LUZ Hugo , SPEMANN Daniel , SPÄTH Bettina , MARCHFELDER Anita , TRÖGER Wolfgang , MEYER-KLAUCKE Wolfram
Published: December 2004

ZiPD (zinc phosphodiesterase; synonyms are ElaC, ecoZ, RNaseZ and 3′ tRNase) and the iron-dependent redox enzyme FlRd (flavorubredoxin) from Escherichia coli represent prototypical cases of proteins sharing the metallo-β-lactamase fold that require strict metal selectivity for catalytic activity, yet their metal selectivity has only been partially understood. In contrast with hydrolytic metallo-β-lactamase proteins, iron-dependent FlRd-like enzymes have an atypical glutamate ligand, which replaces one otherwise conserved histidine ligand. X-ray absorption spectroscopy revealed that the FlRd metallo-β-lactamase domain is capable of incorporating two zinc ions into the binuclear metal-binding site. Zinc dissociation constants, determined by isothermal titration calorimetry are similar for zinc binding to E. coli ZiPD (Kd1=2.2±0.2 μM and Kd2=23.0±0.6 μM) and to the E. coli FlRd metallo-β-lactamase domain (Kd1=0.7±0.1 μM and Kd2=26.0±0.1 μM). In good correspondence, apo-ZiPD requires incubation with 10 μM zinc for full reconstitution of the phosphodiesterase activity. Accordingly, metal selectivity of ZiPD and FlRd only partially relies on first shell metal ligands. Back mutation of the atypical glutamate in FlRd to a histidine unexpectedly resulted in an increased first zinc dissociation constant (Kd1=30±4 μM and Kd2=23±2 μM). In combination with a recent mutational study on ZiPD [Vogel, Schilling and Meyer-Klaucke (2004) Biochemistry 43, 10379–10386], we conclude that the atypical glutamate does not guide metal selectivity of the FlRd metallo-β-lactamase domain but suppresses possible hydrolytic cross-activity.
The Nramp orthologue of Cryptococcus neoformans is a pH-dependent transporter of manganese, iron, cobalt and nickel
Authors: AGRANOFF Daniel , COLLINS Lauren , KEHRES David , HARRISON Tom , MAGUIRE Michael , KRISHNA Sanjeev
Published: December 2004

Cryptococcus neoformans is an important human opportunistic pathogen and a facultative intracellular parasite, particularly in HIV-infected individuals. Little is known about metal ion transport in this organism. C. neoformans encodes a single member of the Nramp (natural resistance-associated macrophage protein) family of bivalent cation transporters, known as Cramp, which we have cloned and expressed in Xenopus laevis oocytes and Spodoptera frugiperda Sf 21 insect cells. Cramp induces saturable transport of a broad range of bivalent transition series cations, including Mn2+, Fe2+, Co2+ and Ni2+. Maximal cation transport occurs at pH 5.5–6.0, consistent with the proton gradient-based energetics of other Nramp orthologues. Mn2+ transport is diminished in the presence of 140 mM Na+, compatible with a Na+ slippage mechanism proposed for the Saccharomyces cerevisiae Nramp orthologue Smf1p. Cramp resembles Smf1p with respect to predicted membrane topology, substrate specificity and pH dependence, but differs in terms of its apparent affinity for Mn2+ and negligible inhibition by Zn2+. Cramp is the first Nramp orthologue from a fungal pathogen to be functionally characterized. Insights afforded by these findings will allow the formulation of new hypotheses regarding the role of metal ions in the pathophysiology of cryptococcosis.
Impact of marathon running on cardiac structure and function in recreational runners
Authors: WHYTE Gregory , GEORGE Keith , SHAVE Robert , DAWSON Ellen , STEPHENSON Claire , EDWARDS Ben , GAZE David , OXBOROUGH David , FORSTER Jan , SIMSPON Rickie
Published: December 2004

The present study examined the relationship between LV (left ventricular) function, markers of cardiac-specific damage and markers of oxidative stress in recreational runners following a marathon. Runners (n=52; 43 male and nine female; age, 35±10 years; height, 1.74±0.08 m; body mass, 75.9±8.9 kg) were assessed pre- and immediately post-marathon. LV function was assessed using standard M-mode two-dimensional Doppler echocardiography and TDI (tissue-Doppler imaging) echocardiography. Serum was analysed for cTnT (cardiac troponin-T), TEAC (Trolox equivalent antioxidant capacity; a measure of total antioxidant capacity), MDA (malondealdehyde) and 4-HNE (4-hydroxynonenal). A strong relationship was observed between standard and TDI echocardiography for all functional measures. Diastolic function was altered post-marathon characterized by a reduction in E (peak early diastolic filling: 0.79±0.11 compared with 0.64±0.16 cm/s; P<0.001), an increase in A (peak late diastolic filling: 0.48±0.11 compared with 0.60±0.12 cm/s; P<0.001) and a resultant decrease in E/A (ratio of E to A; 1.71±0.48 compared with 1.10±0.31; P<0.001). Ejection fraction remained unchanged post-marathon. Thirty-two runners presented with cTnT values above the lower limit of detection for the assay (0.01 μg/l), and 20 runners presented post-marathon with cTnT values above the acute myocardial infarction cut-off value (0.05 μg/l). No significant correlations were observed between cTnT and any functional measurements. MDA (2.90±1.58 compared with 3.59±1.47 μmol/l) and TEAC (1.80±0.12 compared with 1.89±0.21 mmol/l) were significantly increased post-marathon, but were unrelated to changes in function or cTnT. In conclusion, the present study demonstrated a reduction in diastolic function and widespread evidence of minimal cardiac damage following a marathon in recreational runners. The mechanism(s) underpinning the altered function and appearance of cTnT appear unrelated to reactive oxygen species.
Homogeneous nucleation rates of 1-pentanol
Authors: Iland Kristina , Wedekind Jan , Wölk Judith , Wagner Paul E. , Strey Reinhard
Published: December 2004

We have measured isothermal homogeneous nucleation rates J for 1-pentanol vapor in two different carrier-gases, argon, and helium, using a two-valve nucleation pulse chamber. The nucleation rates cover a range of 105<J/cm−3 s−1<109 at temperatures between 235<T/K<265. We observed no influence of the carrier gas on location and slope of the nucleation rate isotherms. These measurements are part of an international effort to examine 1-pentanol using various experimental techniques, which was initiated in Prague in 1995. In the present paper nucleation rate data obtained by several groups are compared to each other and to the classical nucleation theory. As expected, the classical theory is not able to quantitatively predict the experimental results. Nevertheless, relating the experimental data to the classical theory provides a suitable way to compare data of widely differing nucleation rates obtained by different experimental techniques. This comparison helps judging mutual support of the data and, at the same time, provides a rather interesting insight into the accuracy of the individual experimental techniques.
Intramolecular energy transfer between oriented chromophores: High-resolution infrared spectroscopy of HCl trimer
Authors: Fárnı́k Michal , Nesbitt David J.
Published: December 2004

Detailed dynamical and structural information has been obtained for hydrogen-bonded (HCl)3 clusters via high-resolution IR laser absorption spectroscopy in a supersonic slit expansion. Multiple rovibrational bands in an ≈3000 cm−1 HCl stretch region have been assigned and analyzed for H 35Cl/H 37Cl isotopomeric contributions, corresponding to excitation of (i) the degenerate antisymmetric HCl stretch in isotopically pure (H 35Cl)3, (ii) high- and low-frequency components of the nearly degenerate HCl stretch in H 37Cl (H 35Cl)2, (iii) the low-frequency component of the corresponding HCl stretch in (H 37Cl)2 H 35Cl. The isotopically pure (H 35Cl)3 results are in good agreement with earlier diode-laser efforts. A simple exciton model for vibrational coupling between HCl subunits is presented that indicates rapid intramolecular energy flow (β ≈−1.89 cm−1, τ ≈ 2.8 ps) in the trimer ring, which is in good agreement with vibrationally mediated tunneling rates observed in the HCl dimer. Spectral analysis at slit jet resolution indicates a Δν≈120 MHz homogeneous line broadening and an excited-state lifetime of ≈1.3 ns. The data is consistent with intramolecular vibrational redistribution-induced opening of the trimer followed by true predissociation to either (HCl)2+HCl or 3HCl on a longer time scale.
Monte Carlo versus molecular dynamics simulations in heterogeneous systems: An application to the n-pentane liquid-vapor interface
Authors: Goujon Florent , Malfreyt Patrice , Simon Jean-Marc , Boutin Anne , Rousseau Bernard , Fuchs Alain H.
Published: December 2004

The Monte Carlo (MC) and molecular dynamics (MD) methodologies are now well established for computing equilibrium properties in homogeneous fluids. This is not yet the case for the direct simulation of two-phase systems, which exhibit nonuniformity of the density distribution across the interface. We have performed direct MC and MD simulations of the liquid-gas interface of n-pentane using a standard force-field model. We obtained density and pressure components profiles along the direction normal to the interface that can be very different, depending on the truncation and long range correction strategies. We discuss the influence on predicted properties of different potential truncation schemes implemented in both MC and MD simulations. We show that the MD and MC profiles can be made in agreement by using a Lennard-Jones potential truncated via a polynomial function that makes the first and second derivatives of the potential continuous at the cutoff distance. In this case however, the predicted thermodynamic properties (phase envelope, surface tension) deviate from experiments, because of the changes made in the potential. A further readjustment of the potential parameters is needed if one wants to use this method. We conclude that a straightforward use of bulk phase force fields in MD simulations may lead to some physical inconsistencies when computing interfacial properties.
Time-dependent density functional theory based on a noncollinear formulation of the exchange-correlation potential
Authors: Wang Fan , Ziegler Tom
Published: December 2004

In this study we have introduced a formulation of time-dependent density functional theory (TDDFT) based on a noncollinear exchange-correlation potential. This formulation is a generalization of conventional TDDFT. The form of this formulation is exactly the same as that of the conventional TDDFT for the excitation energies of transitions that do not involve spin flips. In addition, this noncollinear TDDFT formulation allows for spin-flip transitions. This feature makes it possible to resolve more fully excited state spin multiplets, while for closed-shell systems, the spin-flip transitions will result in singlet-triplet excitations and this excitation energy calculated from this formulation of TDDFT is exactly the same as that from ordinary TDDFT. This formulation is applied to the dissociation of H2 in its Σg+1 ground state and Σu+1 and Σu-3 excited states with Σu-3 (Ms=+1) as the reference state and the multiplets splitting of some atoms.
An Alfvén wave maser in the laboratory
Authors: Maggs J. E. , Morales G. J. , Carter T. A.
Published: December 2004

A frequency selective Alfvén wave resonator results from the application of a locally nonuniform magnetic field to a plasma source region between the cathode and anode in a large laboratory device. When a threshold in the plasma discharge current is exceeded, selective amplification produces a highly coherent (δω∕ω<5×10−3), large amplitude shear Alfvén wave that propagates out of the resonator, through a semitransparent mesh anode, into the adjacent plasma column where the magnetic field is uniform. This phenomenon is similar to that encountered in the operation of masers∕lasers at microwave and optical frequencies. The current threshold for maser action is found to depend upon the confinement magnetic field strength B0. Its scaling is consistent with the condition for matching the drift speed of the bulk plasma electrons with the phase velocity of the mode in the resonator. The largest spontaneously amplified signals are obtained at low B0 and large plasma currents. The magnetic fluctuations δB associated with the Alfvén maser can be as large as δB∕B0≈1.5% and are observed to affect the plasma current. Steady-state behavior leading to coherent signals lasting until the discharge is terminated can be achieved when the growth conditions are well-above threshold. The maser is observed to evolve in time from an initial m=0 mode to an m=1 mode structure in the transition to the late steady state. The laboratory phenomenon reported is analogous to the Alfvén wave maser proposed to exist in naturally occurring, near-earth plasmas.
A study of the adiabatic connection for two-electron systems
Authors: Katriel Jacob , Roy Sudip , Springborg Michael
Published: December 2004

Some aspects of the adiabatic connection method are studied for two-particle spherically symmetric systems. Ground-state wave functions that are constrained by means of a set of moments to have the same density as a corresponding fully interacting system are obtained for noninteracting or partially interacting systems. Local one-body potentials that support these constrained wave functions are generated using a simple method. We examine an interacting two-particle system with a parameter-dependent one-body potential, which for a particular value of that parameter exhibits an intersection between the S3 and the P3 states, whereas the 2s and 2p eigenvalues of the corresponding Kohn–Sham potentials do not intersect along with the total energies. These results show that there do exist cases where occupying the orbitals from below in energy may not lead to the ground state, and that the inherent assumptions behind the adiabatic connection can sometimes be violated.
Protein phase diagrams: The physics behind their elliptic shape
Authors: Lesch Harald , Hecht Christoph , Friedrich Josef
Published: December 2004

We relate the condition for the elliptic shape of the phase diagram of proteins to the degree of correlation in the fluctuations of the changes of enthalpy and volume at the denaturing-refolding transition. Since this degree cannot be larger than 1, hyperbolically shaped diagrams are not likely to exist. Experiments show that the correlation factor is actually quite low for proteins implying that one-order parameter is not enough to describe the folding-denaturing transition. These findings seem to be the thermodynamic manifestation of the glasslike properties of proteins despite the fact that the transition itself is of first order.
Bubble nucleation in micellar solution: A density functional study
Authors: Apte Pankaj A. , Kusaka Isamu
Published: December 2004

We explore the free energetics of bubble nucleation in the micellar solution subjected to a negative pressure using a density functional model of a non-ionic surfactant solution. In this two-component model, the solvent is represented by a single hard-core sphere and the surfactant is represented by two tangent hard-core spheres connected by a rigid bond. The attractive interactions between the particles are modeled by the simple 1/R6 form. Under all conditions of pressure and interparticle interactions we studied, the free energy barrier of bubble nucleation is found to be lower in the binary surfactant solution than that in a pure solvent and to continue to decrease as the mole fraction of the surfactant in the solution increases. We analyze the free energy surface of the model system under the conditions where both the critical bubble nucleus and the stable micelle exist in equilibrium with the same metastable solution. Our study shows that at moderately low pressures, bubbles can nucleate from the stable micelle and that the resulting free energy barrier of bubble nucleation is expected to be lower than that in the absence of this mechanism. However, as the spinodal is approached at lower pressures, the mechanism of micelle-assisted bubble nucleation becomes less effective. The liquid–liquid miscibility of the model system correlates well with the mechanism of bubble nucleation from the stable micelle.
Gyrokinetic δf simulation of the collisionless and semicollisional tearing mode instability
Authors: Wan W. , Chen Y. , Parker S. E.
Published: December 2004

The evolution of collisionless and semicollisional tearing mode instabilities is studied using an electromagnetic gyrokinetic δf particle-in-cell simulation model. Drift-kinetic electrons are used. Linear eigenmode analysis is presented for the case of fixed ions and there is excellent agreement with simulation. A double peaked eigenmode structure is seen indicative of a positive Δ′. Nonlinear evolution of a magnetic island is studied and the results compare well with existing theory in terms of saturation level and electron bounce oscillations. Electron-ion collisions are included to study the semicollisional regime. The algebraic growth stage is observed and compares favorably with theory. Nonlinear saturation following the algebraic stage is observed.
Taylor vortices in annular heated spherical flow at medium and large aspect ratios
Authors: Loukopoulos V. C.
Published: December 2004

The annular spherical flow is numerically studied with a view to obtaining Taylor vortices at medium and large aspect ratios σ such as 0.18 and 0.42 in the presence of heat convection. We find Taylor vortices and we show for the first time that for a given aspect ratio and Reynolds number their form and number depends on the Grashof (Gr) number of the flow. We also show that with increasing Gr the flow is associated to various bifurcation branches that complicate the bifurcation diagram.
Experimental evidence for Plotkin model of shock unsteadiness in separated flow
Authors: Poggie Jonathan , Smits Alexander J.
Published: December 2004

Experimental evidence is presented in support of a model of separation shock unsteadiness developed by Plotkin [AIAA J. 13, 1036 (1975)]. Under this model, the position of the separation shock follows linearly damped Brownian motion. The model describes the manner in which relatively broad-band perturbations in the incoming flow lead to relatively low-frequency motion of the separation shock. Close agreement was found between the predictions of the model and the autospectra and autocorrelations of wall pressure fluctuations and shock position fluctuations for several blunt fin flows at Mach 3 and Mach 5. Given the similarity of the power spectra of wall-pressure fluctuations for a variety of separated, supersonic flows, this description may have broad applicability.
The influence of the time-of-flight mobility on the efficiency of solid-state dye-sensitized TiO2 solar cells
Authors: Jäger C. , Haarer D. , Peng B. , Thelakkat M.
Published: December 2004

The dependence of zero field charge carrier mobilities obtained from time-of-flight (TOF) measurements for a series of doped triphenyldiamines on trap depth and concentration were determined. The influence of these mobilities on the solar cell characteristics have been studied by measuring I–V characteristics and IPCE values using the same doped hole conductors in solid-state dye-sensitized TiO2 solar cells. The traps exhibit only a weak influence on the solar cell characteristics, because the traps which are responsible for low charge transport mobilities in the TOF experiment are filled under steady state illumination conditions. In consequence the effective mobility is raised almost to that of the pristine hole conductor, thus allowing the use of doped hole conductor systems in solar cells without any adverse effects.
Application of modified transmission line model to measure p-type GaN contact
Authors: Chen N. C. , Tseng C. Y. , Chiu A. P. , Shih C. F. , Chang P. H.
Published: December 2004

This work presented a procedure for extending the modified transmission line model to measure non-ohmic contact. This method was applied to the p-type GaN contact with the resulting sheet resistance similar to that determined by the Hall measurement. The voltage–current density (V–J) curve obtained using this procedure was also similar to that by directly analyzing the current–voltage curve of a light-emitting diode. Both results revealed the validity of this procedure. Rather than yielding a specific contact resistance for an ohmic contact, this procedure yielded a V–J curve to describe the non-ohmic contact characteristics. Similarly, this procedure could also extend the linear transmission line model to the analysis of non-ohmic contacts.
A microfluidic 2×2 optical switch
Authors: Campbell Kyle , Groisman Alex , Levy Uriel , Pang Lin , Mookherjea Shayan , Psaltis Demetri , Fainman Yeshaiahu
Published: December 2004

A 2×2 microfluidic-based optical switch is proposed and demonstrated. The switch is made of an optically clear silicon elastomer, Polydimethylsiloxane (PDMS), using soft lithography. It has insertion loss smaller than 1dB and extinction ratio on the order of 20dB. The device is switching between transmission (bypass) and reflection (exchange) modes within less than 20ms.
Orientation dependence of transverse piezoelectric properties of 0.70Pb(Mg1∕3Nb2∕3)O3-0.30PbTiO3 single crystals
Authors: Peng Jue , Luo Hao-su , Lin Di , Xu Hai-qing , He Tian-hou , Jin Wei-qing
Published: December 2004

In this letter, we present our investigation of transverse piezoelectric performance in 0.70Pb(Mg1∕3Nb2∕3)O3-0.30PbTiO3 (0.70PMN-0.30PT) single crystals with different cuts using a resonance technique. We give the report on the finding of ultrahigh k31 and d31 values of 95.4% and −2517pC∕N, respectively. However, this unusual transverse piezoelectric property is only obtained in crystals with the polarization (thickness) and vibration (length) directions along the ⟨110⟩ and ⟨001⟩ directions, respectively. The 0.70PMN-0.30PT crystal with this cut shows significantly great potential for applications in high-performance transverse-mode piezoelectric devices, such as medical array ultrasonic transducers and actuators.
Room-temperature demonstration of low-voltage and tunable static memory based on negative differential conductance in silicon single-electron transistors
Authors: Saitoh Masumi , Harata Hidehiro , Hiramoto Toshiro
Published: December 2004

A static memory based on negative differential conductance (NDC) in silicon single-electron transistors is proposed. We fabricate a room-temperature (RT) operating single-hole transistor (SHT) in the form of an ultranarrow wire channel metal-oxide-semiconductor field-effect transistor (MOSFET), and observe clear NDC due to large quantum level spacing of an ultrasmall dot at RT. By serially connecting an SHT showing NDC and a p-type MOSFET acting as a load on a single chip, gate-controllable memory operation is demonstrated at the supply voltage of 0.2V at RT. The proposed memory features high compatibility with the existing very-large-scale integrated circuits, compact size, low-voltage, and tunable operation.
Direct optoelectronic generation and detection of sub-ps-electrical pulses on sub-mm-coaxial transmission lines
Authors: Jeon Tae-In , Grischkowsky D.
Published: December 2004

We report efficient direct optoelectronic generation of sub-ps-THz pulses on 50Ω coaxial transmission lines with a 330μm diameter solid copper outer tube filled with Teflon containing the 80μm diameter inner conductor. The transmitted pulses after propagating as much as 105mm were measured at the end of the line with an optoelectronic antenna having sub-ps-time resolution. We observed low-loss, single transverse electromagnetic mode propagation with very little group velocity dispersion. The experimentally derived values for the frequency-dependent absorption are consistent with the theoretical predictions.
Atomic strings of group IV, III–V, and II–VI elements
Authors: Tongay S. , Durgun E. , Ciraci S.
Published: December 2004

A systematic first-principles study of atomic strings made by group IV, III–V, and II–VI elements has revealed interesting mechanical, electronic, and transport properties. The double bond structure underlies their unusual properties. We found that linear chain of C, Si, Ge, SiGe, GaAs, InSb, and CdTe are stable and good conductor, although their parent diamond (zincblende) crystals are covalent (polar) semiconductors but, compounds SiC, BN, AlP, and ZnSe are semiconductors. First row elements do not form zigzag structures.
Guiding 1.5 μm light in photonic crystals based on dielectric rods
Authors: Assefa Solomon , Rakich Peter T. , Bienstman Peter , Johnson Steven G. , Petrich Gale S. , Joannopoulos John D. , Kolodziejski Leslie A. , Ippen Erich P. , Smith Henry I.
Published: December 2004

Photonic-crystal structures consisting of dielectric rods were designed, fabricated, and optically characterized. The combination of the high refractive-index-contrast GaAs∕AlxOy material system with electron-beam lithography enabled the fabrication of structures suitable for the optical propagation of 1.5 μm light. Experimental transmission spectra were obtained for structures consisting of a two-dimensional array of rods and line-defect waveguides. Optical measurements confirmed the presence of a photonic band gap, as well as band gap guidance in the line-defect waveguide. A two-stage coupling scheme facilitated efficient optical coupling into the line-defect waveguide.
Persistent photocurrent spectroscopy of GaN metal–semiconductor–metal photodetectors on long time scale
Authors: Potì B. , Passaseo A. , Lomascolo M. , Cingolani R. , De Vittorio M.
Published: December 2004

Some of the trapping mechanisms responsible for the persistent photocurrent effects in GaN metal–semiconductor–metal photodetectors have been studied on a time scale of several hours by analyzing the photocurrent decay kinetic as a function of temperature. The analysis of the Arrhenius plot of the decay kinetic on a long time scale shows two activation energies of about 140meV and 1eV. Such values are in good agreement with two slope changes observed in the room temperature photocurrent spectrum around 2.40 and 3.25eV, in the GaN energy band gap. According to the Lucovsky theory the 140meV activation energy was interpreted as due to the transition from a deep localized state to the conduction band edge, whereas the 1eV activation energy was interpreted as due to the transition from the valence band edge to a deep localized state. Therefore, the persistent photocurrent on long time scale is primarily due to the presence of donor deep and acceptor deep states generated by gallium vacancies, gallium antisites, and carbon impurities.