bluuebunny/crossref_metadata_2025 huggingface dataset:
Vitellogenin dynamics during egg‐laying: daily variation, repeatability and relationship with egg size
Authors: Salvante Katrina G. , Williams Tony D.
Published: March 2005

Daily variation in circulating levels of the avian yolk precursor, vitellogenin (VTG), throughout the laying cycle was investigated in female zebra finches Taeniopygia guttata and compared with predicted ovarian follicle demand (based on a model of follicular development for this species). In general, the pattern of variation in plasma VTG matched the predicted demand from the developing ovarian follicle hierarchy. Plasma VTG was non‐detectable in non‐breeders, but increased rapidly with onset of yolk development, remaining high (1.43–1.82 μg/ml, zinc) through to the 3‐egg stage. Plasma levels then declined at the 5‐egg stage (to 0.78±0.32 μg/ml) and were undetectable at clutch completion. This result is consistent with the hypothesis that yolk precursor production is costly and that selection has matched supply and demand. While inter‐individual variation in plasma VTG was marked (e.g. 0.47–4.26 μg/ml at the 1‐egg stage), it also exhibited high intra‐individual repeatability (r=0.87–0.93). Finally, we examined the relationship between plasma VTG and primary reproductive effort. While individual variation in plasma VTG was independent of clutch size, laying interval and laying rate, there was a complex, diet‐dependent relationship between VTG and egg size, with low plasma VTG levels being associated with both very small (<0.90 g) and very large (>1.15 g) egg sizes.
Density‐dependent decline of breeding success in an introduced, increasing mute swanCygus olorpopulation
Authors: Nummi Petri , Saari Lennart
Published: March 2005

An increasing population of the mute swanCygnusolor, was studied from its very establishment in 1976 until 1998. As the number of pairs increased, there was a decline in all production parameters, including the average number of clutches per pair, the average number of broods per clutch, and the average number of fledged young per brood. In a multiple regression analysis covering the whole breeding season, the number of pairs and the average number of clutches per pair explained 71% of the variation in the average number of fledglings per pair. During the brood season, the average number of fledglings per brood was an additionally important parameter in explaining fledgling production. Habitat quality seemed to affect breeding: in places occupied earlier more cygnets fledged from a clutch than in habitats inhabited later. The decreased production of young very likely reflects density‐dependent effects on reproduction. This density dependence seems to operate on the breeding grounds, since winter harshness did not affect breeding success. Density‐dependent processes started acting already when pairs were beginning to nest, and continued during the brood period. Density dependence has apparently not been detected at the pair stage in earlier studies of bird populations.
Variability in diapause duration in the chestnut weevil: mixed ESS, genetic polymorphism or bet‐hedging?
Authors: Soula Bertrand , Menu Frédéric
Published: March 2005

Within‐generation variability in diapause duration can be viewed either as a mixed Evolutionary Stable Strategy (ESS), a genetic polymorphism of pure strategies, or as bet‐hedging. Diapause variability expressed by a single genotype that maximizes mean geometric fitness at the cost of mean arithmetic fitness is a bet‐hedging strategy. Bet‐hedging differs from mixed ESS and stable genetic polymorphism of pure strategies because in these latter the expected pay‐offs for all phenotypes are equal. In insects, individuals with a prolonged diapause (long cycle) lose at least one reproductive opportunity and suffer lower survival before reproduction than those with a short diapause (short cycle). If long‐cycle individuals compensate this cost by better adult performance, the compensation leads to a trade‐off which could result in mixed ESS or genetic polymorphism of pure strategies since the overall fitness of the two morphs may be similar. In this paper, we show that in the chestnut weevil Curculio elephas adult performance, measured as sex ratio, longevity, weight, and realized fecundity of females, are similar in individuals emerged after one and two years. Long‐cycle morphs emerge slightly before short‐cycle ones but this eventual advantage for fertility probably does not compensate higher larval mortality and missed reproductive opportunity in long‐cycle phenotypes. Therefore, the cost associated with prolonged diapause cannot be completely compensated for by a better adult performance. From these results, and previous data, we conclude that variability in diapause duration cycle is better explained as bet‐hedging than mixed ESS or genetic polymorphism of pure strategies.
Opposing effects of grazing and nutrients on diversity
Authors: Hillebrand Helmut
Published: March 2005

Conceptual models predict counteractive effects of herbivores and nutrient enrichment on plant diversity and reversed effects of grazers under different nutrient regimes. I tested these hypotheses in 11 field experiments with periphyton communities in three different aquatic habitats (a highly eutrophic lake, an meso‐eutrophic lake, and an meso‐eutrophic part of the Baltic Sea coast) and in different seasons. Grazer access and nutrient supply were manipulated in a factorial design. Species richness and evenness were chosen as response variables. Both manipulated factors had significant and contrasting effects on diversity, with variable effect strength between sites and seasons. From the two aspects of diversity, evenness well reflected the changes in community composition. Fertilization tended to increase the dominance of few species and thus to decrease evenness, whereas grazers counteracted these effects by removing dominant life forms. The response of species richness was not as expected, since grazers decreased richness throughout, whereas nutrients had weaker effects but tended to increase richness. Species richness rather reflected changes in periphyton architecture. Grazers reduced algal richness presumably by co‐consumption of rare species in the tightly connected periphyton assemblages, whereas enrichment may increase richness by providing more structure via increased dominance of filamentous species. Although grazer and nutrient effects on richness and evenness were opposing, there was no change in the effect of one factor by manipulation of the other.
Rab1 Interaction with a GM130 Effector Complex Regulates COPII Vesicle cis‐Golgi Tethering
Authors: Moyer Bryan D. , Allan Bernard B. , Balch William E.
Published: March 2005

Members of the Rab family of small molecular weight GTPases regulate the fusion of transport intermediates to target membranes along the biosynthetic and endocytic pathways. We recently demonstrated that Rab1 recruitment of the tethering factor p115 into a cis‐SNARE complex programs coat protein II vesicles budding from the endoplasmic reticulum (donor compartment) for fusion with the Golgi apparatus (acceptor compartment) (Allan BB, Moyer BD, Balch WE. Science 2000; 289: 444–448). However, the molecular mechanism(s) of Rab regulation of Golgi acceptor compartment function in endoplasmic reticulum to Golgi transport are unknown. Here, we demonstrate that the cis‐Golgi tethering protein GM130, complexed with GRASP65 and other proteins, forms a novel Rab1 effector complex that interacts with activated Rab1‐GTP in a p115‐independent manner and is required for coat protein II vesicle targeting/fusion with the cis‐Golgi. We propose a ‘homing hypothesis’ in which the same Rab interacts with distinct tethering factors at donor and acceptor membranes to program heterotypic membrane fusion events between transport intermediates and their target compartments.
Hodgkin's lymphoma after post‐transplant lymphoproliferative disease in a renal transplant recipient
Authors: Dharnidharka Vikas R. , Douglas Vonda K. , Hunger Stephen P. , Fennell Robert S.
Published: March 2005

Abstract:  Lymphoid malignancies such as post‐transplant lymphoproliferative disease (PTLD) are a major complication of solid organ transplantation. Hodgkin's lymphoma (HL) is not part of the typical spectrum of PTLD, but has rarely been reported as a separate complication. We report a case of HL occurring after previous PTLD in a renal transplant recipient. A 9‐yr‐old girl with end‐stage autosomal recessive polycystic kidney disease received a cadaveric renal transplant at 1 yr of age. She developed polymorphic PTLD localized to the bone marrow at 6 yr post‐transplant. She was treated with reduction of immunosuppression and alpha‐interferon. No chemotherapy or anti‐B cell antibody was administered. The PTLD resolved and kidney graft function remained stable. At 9 yr post‐transplant, she presented again with fever of 2 wk duration, associated with enlarged lymph nodes at multiple sites. A lymph node biopsy revealed the presence of classic Reed Sternberg cells positive for CD15, CD30 and EB RNA. She was treated with standard combination chemotherapy for HL with COPP/ABV. All immunosuppressive agents were discontinued except for low dose prednisone. The patient had an excellent response, with resolution of her lymphadenopathy and maintenance of stable graft function. RS like cells have been reported in the setting of PTLD, but these cells possess an activated B cell phenotype, are EBV negative and CD15 negative. True HL following PTLD has been reported in only three previous cases, with good response to standard chemotherapy in each.
The yield of surveillance endomyocardial biopsies as a screen for cellular rejection in pediatric heart transplant patients
Authors: Levi Daniel S. , DeConde Adam S. , Fishbein Michael C. , Burch Caron , Alejos Juan C. , Wetzel Glenn T.
Published: March 2005

Abstract: Endomyocardial biopsy is commonly used to screen for cellular rejection in pediatric heart transplant patients. The yield of EMBs when combined with newly developed immunohistochemical techniques and modern immunosuppression in pediatric heart transplant patients is unknown. After OHT, surveillance biopsies were performed on a routine basis on all pediatric patients. EMBs were also performed on symptomatic OHT patients suspected to have rejection. All positive results (greater than ISHLT grade 1B) were confirmed with immunohistochemical staining. A retrospective review of consecutive EMBs performed in this institution from January 1995 to January 2003 was performed. The echocardiographic results, clinical history and treatment changes at the time of every biopsy were also catalogued. Of the 1093 EMB results from 136 pediatric heart transplant grafts (127 patients, 64 male) reviewed, 825 biopsies were performed on patients managed with tacrolimus and 268 were performed on patients managed with cyclosporine. The patients managed with tacrolimus had an incidence of 0.85% (7/825) for significant rejection (greater than ISHLT grade 1B rejection) vs. an incidence of 4.1% (11/268) for the patients on cyclosporine (p < 0.0005). In the asymptomatic tacrolimus patients, only two screening biopsies (0.26%) manifest significant rejection, and both of these were performed within the first month after transplantation. Of the symptomatic tacrolimus patients, 9.1% (n = 5) had findings on biopsy consistent with significant cellular rejection. There were 25 patients with grade 1B rejection. Twenty‐two of these patients were not treated, and all cases of grade 1B rejection resolved without clinical sequelae. For pediatric patients more than 30 days after OHT, EMB has failed to reveal significant episodes of cellular rejection in asymptomatic patients managed with tacrolimus.
Modulation of activity of NADH oxidase from Thermus thermophilus through change in flexibility in the enzyme active site induced by Hofmeister series anions
Authors: Žoldák Gabriel , Sprinzl Mathias , Sedlák Erik
Published: March 2005

The conformational dynamics of NADH oxidase from Thermus thermophilus was modulated by the Hofmeister series of anions (H2PO4–, SO42–, CH3COO–, Cl–, Br–, I–, ClO4–, SCN–) in the concentration range 0–3 M. Both chaotropic and kosmotropic anions, at high concentration, inhibit the enzyme by different mechanisms. Chaotropic anions increase the apparent Michaelis constant and decrease the activation barrier of the reaction. Kosmotropic anions have the opposite effect. Anions from the middle of the Hofmeister series do not significantly affect the enzyme activity even at high concentration. We detected no significant changes in ellipticity of the aromatic region in the presence of the anions studied. There is a decreased Stern–Volmer quenching constant for FAD fluorescence quenching in the presence of kosmotropic anions and an increased quenching constant in the presence of chaotropic anions. All of this indicates that active site flexibility is important in the function of the enzyme. The data demonstrate that both the high rigidity of the active site in the presence of kosmotropic anions, and its high flexibility in the presence of chaotropic anions have a decelerating effect on enzyme activity. The Hofmeister series of anions proved to be suitable agents for altering enzyme activity through changes in flexibility of the polypeptide chain, with potential importance in modulating extremozyme activity at room temperature.
Cloning and expression of murine enzymes involved in the salvage pathway of GDP‐l‐fucose
Authors: Niittymäki Jaana , Mattila Pirkko , Roos Christophe , Huopaniemi Laura , Sjöblom Solveig , Renkonen Risto
Published: March 2005

In the salvage pathway of GDP‐l‐fucose, free cytosolic fucose is phosphorylated by l‐fucokinase to form l‐fucose‐1‐phosphate, which is then further converted to GDP‐l‐fucose in the reaction catalyzed by GDP‐l‐fucose pyrophosphorylase. We report here the cloning and expression of murine l‐fucokinase and GDP‐l‐fucose pyrophosphorylase. Murine l‐fucokinase is expressed as two transcripts of 3057 and 3270 base pairs, encoding proteins of 1019 and 1090 amino acids with predicted molecular masses of 111 kDa and 120 kDa respectively. Only the longer splice variant of l‐fucokinase was enzymatically active when expressed in COS‐7 cells. Murine GDP‐l‐fucose pyrophosphorylase has an open reading frame of 1773 base pairs encoding a protein of 591 amino acids with a predicted molecular mass of 65.5 kDa. GDP‐l‐fucose, the reaction product of GDP‐l‐pyrophosphorylase, was identified by HPLC and MALDI‐TOF MS analysis. The tissue distribution of murine l‐fucokinase and GDP‐l‐fucose pyrophosphorylase was investigated by quantitative real time PCR, which revealed high expression of l‐fucokinase and GDP‐l‐fucose pyrophosphorylase in various tissues. The wide expression of both enzymes can also be observed from the large amount of data collected from a number of expressed sequence tag libraries, which indicate that not only the de novo pathway alone, but also the salvage pathway, could have a significant role in the synthesis of GDP‐l‐fucose in the cytosol.
Determination of modulation of ligand properties of synthetic complex‐type biantennary N‐glycans by introduction of bisecting GlcNAc in silico, in vitro and in vivo
Authors: André Sabine , Unverzagt Carlo , Kojima Shuji , Frank Martin , Seifert Joachim , Fink Christian , Kayser Klaus , von der Lieth Claus‐Wilhelm , Gabius Hans‐Joachim
Published: March 2005

We have investigated the consequences of introducing a bisecting GlcNAc moiety into biantennary N‐glycans. Computational analysis of glycan conformation with prolonged simulation periods in vacuo and in a solvent box revealed two main effects: backfolding of the α1–6 arm and stacking of the bisecting GlcNAc and the neighboring Man/GlcNAc residues of both antennae. Chemoenzymatic synthesis produced the bisecting biantennary decasaccharide N‐glycan and its α2–3(6)‐sialylated variants. They were conjugated to BSA to probe the ligand properties of N‐glycans with bisecting GlcNAc. To assess affinity alterations in glycan binding to receptors, testing was performed with purified lectins, cultured cells, tissue sections and animals. The panel of lectins, including an adhesion/growth‐regulatory galectin, revealed up to a sixfold difference in affinity constants for these neoglycoproteins relative to data on the unsubstituted glycans reported previously [André, S., Unverzagt, C., Kojima, S., Dong, X., Fink, C., Kayser, K. & Gabius, H.‐J. (1997) Bioconjugate Chem. 8, 845–855]. The enhanced affinity for galectin‐1 is in accord with the increased percentage of cell positivity in cytofluorimetric and histochemical analysis of carbohydrate‐dependent binding of labeled neoglycoproteins to cultured tumor cells and routinely processed lung cancer sections. Intravenous injection of iodinated neoglycoproteins carrying galactose‐terminated N‐glycans into mice revealed the highest uptake in liver and spleen for the bisecting compound compared with the unsubstituted or core‐fucosylated N‐glycans. Thus, this substitution modulates ligand properties in interactions with lectins, a key finding of this report. Synthetic glycan tailoring provides a versatile approach to the preparation of newly substituted glycans with favorable ligand properties for medical applications.
Active‐site residues and amino acid specificity of the bacterial 4′‐phosphopantothenoylcysteine synthetase CoaB
Authors: Kupke Thomas
Published: March 2005

In bacteria, coenzyme A is synthesized in five steps from d‐pantothenate. The Dfp flavoprotein catalyzes the synthesis of the coenzyme A precursor 4′‐phosphopantetheine from 4′‐phosphopantothenate and cysteine using the cofactors CTP and flavine mononucleotide via the phosphopeptide‐like compound 4′‐phosphopantothenoylcysteine. The synthesis of 4′‐phosphopantothenoylcysteine is catalyzed by the C‐terminal CoaB domain of Dfp and occurs via the acyl‐cytidylate intermediate 4′‐phosphopantothenoyl‐CMP in two half reactions. In this new study, the molecular characterization of the CoaB domain is continued. In addition to the recently described residue Asn210, two more active‐site residues, Arg206 and Ala276, were identified and shown to be involved in the second half reaction of the (R)‐4′‐phospho‐N‐pantothenoylcysteine synthetase. The proposed intermediate of the (R)‐4′‐phospho‐N‐pantothenoylcysteine synthetase reaction, 4′‐phosphopantothenoyl‐CMP, was characterized by MALDI‐TOF MS and it was shown that the intermediate is copurified with the mutant His‐CoaB N210H/K proteins. Therefore, His‐CoaB N210H and His‐CoaB N210K will be of interest to elucidate the crystal structure of CoaB complexed with the reaction intermediate. Wild‐type His‐CoaB is not absolutely specific for cysteine and can couple derivatives of cysteine to 4′‐phosphopantothenate. However, no phosphopeptide‐like structure is formed with serine. Molecular characterization of the temperature‐sensitive Escherichia coli dfp‐1 mutant revealed that the residue adjacent to Ala276, Ala275 of the strictly conserved AAVAD(275–279) motif, is exchanged for Thr.
Ambiguities and Ambivalences in Making the Nation: Women and Politics in 20th-Century Mexico
Authors: Craske Nikki
Published: March 2005

By comparing two time periods, the early and late 20th century, this article examines the ambiguities and ambivalences in the state promotion of women in the nation-building projects of Mexico. I argue that in both cases, the state was keen to promote itself as modern and progressive and used women's status in society to these ends. Despite the explicit focus on women, there were many ambiguities and ambivalences resulting from the competing state projects in the political, socio-economic and cultural arenas offering women both privileged spaces and constraints in the development of gendered citizenship. The contradictions arise from simultaneously promoting women's rights, extolling traditional gender roles and fearing women's political activism – both conservative and more radical. Although these ambivalences and ambiguities remain a constant feature, there is a key difference in the two time periods: in one the regime is inward looking, economically protectionist and corporatist, while in the other a new vision of Mexico has attempted to dismantle the corporatist structures and state development project with private economic initiatives and political individualism. In both periods, women gained important rights but romanticized imagery of the self-sacrificing mother was mobilized to underpin change: women were expected both to change and remain the same.
Mössbauer evaluation of cobalt ferrite nanoparticles synthesized by forced hydrolysis
Authors: Hamdeh H. H. , Hikal W. M. , Taher S. M. , Ho J. C. , Thuy N. P. , Quy O. K. , Hanh N.
Published: March 2005

Spinel cobalt ferrite in the form of nearly spherical particles, having a narrow range of particle size around 7.6nm, was produced by forced hydrolysis. Between the magnetization blocking temperature of 180K and the Mössbauer blocking temperature of 270K, the magnetic anisotropy energy decreases rapidly with temperature. The occupancy of the octahedral sites by only half of the Co2+ cations may have weakened the crystalline anisotropy. Significant spin canting was also observed at these sites.
Spectral signatures of the diffusional anomaly in water
Authors: Mudi Anirban , Chakravarty Charusita , Ramaswamy Ramakrishna
Published: March 2005

Power spectra for various tagged particle quantities in bulk extended simple point charge model water [H. J. C. Berendsen, J. R. Grigera, and T. P. Straatsma, J. Phys. Chem. 91, 6269 (1987)] are shown to have a regime with 1∕fα dependence on frequency f with α lying between 1 and 1.5 if the dynamical changes in the particular observable are sensitive to the multiple time-scale behavior of the hydrogen-bond network. The variations in mobility associated with the diffusional anomaly are mirrored in the scaling exponent α associated with this multiple time-scale behavior, suggesting that monitoring of 1∕fα behavior is a simple and direct method for linking phenomena on three distinctive length and time scales: the local molecular environment, hydrogen-bond network reorganizations, and the diffusivity. Our results indicate that experimental studies of supercooled water to probe the density dependence of 1∕fα spectral features, or equivalent stretched exponential behavior in time-correlation functions, will be of interest.
A coarse-grained explicit solvent simulation of rheology of colloidal suspensions
Authors: Pryamitsyn Victor , Ganesan Venkat
Published: March 2005

We use a simple extension of the dissipative particle dynamics (DPD) model to address the dynamical properties of macrosolutes immersed in complex fluid solvents. In this approach, the solvent particles are still represented as DPD particles, thereby retaining the time and length scale advantages offered by the DPD approach. In contrast, the solute particles are represented as hard particles of the appropriate size. We examine the applicability of this simulation approach to reproduce the correct hydrodynamical characteristics of the mixture. Our results focus on the equilibrium dynamics and the steady-state shear rheological behaviors for a range of volume fractions of the suspension, and demonstrate excellent agreement with many published experimental and theoretical results. Moreover, we are also able to track the glass transition of our suspension and the associated dynamical signatures in both the diffusivities and the rheological properties of our suspension. Our results suggest that the simulation approach can be used as a one-parameter model to examine quantitatively the rheological properties of colloidal suspensions in complex fluid solvents such as polymeric melts and solutions, as well as allied dynamical phenomena such as phase ordering in mixtures of block copolymers and particles.
Evaluation of bridge-function diagrams via Mayer-sampling Monte Carlo simulation
Authors: Kwak Sang Kyu , Kofke David A.
Published: March 2005

We report coefficients of the h-bond expansion of the bridge function of the hard-sphere system up to order ρ4 (where ρ is the density in units of the hard-sphere diameter), which in the highest-order term includes 88 cluster diagrams with bonds representing the total correlation function h(r). Calculations are performed using the recently introduced Mayer-sampling method for evaluation of cluster integrals, and an iterative scheme is applied in which the h(r) used in the cluster integrals is determined by solution of the Ornstein–Zernike equation with a closure given by the calculated clusters. Calculations are performed for reduced densities from 0.1 to 0.9 in increments of 0.1. Comparison with molecular simulation data shows that the convergence is very slow for the density expansion of the bridge function calculated this way.
Spectral analysis and energy-level structure of Er3+(4f11) in polycrystalline ceramic garnet Y3Al5O12
Authors: Gruber John B. , Nijjar Anmol S. , Sardar Dhiraj K. , Yow Raylon M. , Russell Charles C. , Allik Toomas H. , Zandi Bahram
Published: March 2005

Absorption spectra obtained between 1550 and 440nm and fluorescence spectra obtained between 1700 and 1500nm are reported in a comparative spectroscopic study of polycrystalline ceramic Y3Al5O12 (YAG) and single-crystal laser rod YAG, both containing 50at.% Er3+ as a dopant in the garnet host. The spectra are observed in both samples at temperatures between 8K and room temperature. The detailed splitting of individual multiplet manifolds, LJ2S+1, Er3+(4f11), by the crystalline electric field is similar in both the ceramic sample and the single-crystal laser rod. With few exceptions, there is little shift in energy (few wave numbers) of individual Stark levels within a manifold, between dilute and concentrated Er3+ samples. This is not too surprising since Y3Al5O12 and Er3Al5O12 form a solid solution with the majority of Er3+ ions occupying cation sites having D2 symmetry in the garnet lattice over the entire solid solution range. As a check on the observed manifold splittings of Er3+ in ceramic YAG, we compared the present results to the calculated splitting that several of us reported earlier for Er3+ in single-crystal YAG. To within the standard deviation reported earlier, the present results agree with that calculation. Thus, one set of atomic and crystal-field parameters describes the splitting of the Er3+ energy levels in either the ceramic or single-crystal host for Er3+ in D2 sites.
Conduction mechanisms in ion-irradiated InGaAs layers
Authors: Joulaud L. , Mangeney J. , Chimot N. , Crozat P. , Fishman G. , Bourgoin J. C.
Published: March 2005

The electrical and optical properties of H+- and Au+-irradiated InGaAs layers were studied using Hall-effect, van der Pauw, and relaxation-time measurements. Comparing the different results allows us to obtain information on the nature of the defects created by these two irradiations. Proton irradiation introduces donor-acceptor paired defects. Gold-ion irradiation creates neutral defect clusters and ionized point defects. The carrier mobilities in all of the irradiated materials are degraded, decreasing with increasing irradiation dose. A scattering model taking into account the paired defects is developed and the mobility evolution calculated from this model agrees with the experimental data of both annealed and unannealed samples. The photocurrent spectra reveal a metallic conduction in the band gap in the case of light-ion irradiation, while such type of conduction does not appear for heavy-ion irradiation. This metallic conduction is a consequence of band tailing induced by shallow defects and vanishes when the material is annealed at 400°C. The proton irradiation-induced defects appear to be related to the EL-2-like defects.
White organic light-emitting diode comprising of blue fluorescence and red phosphorescence
Authors: Qin Dashan , Tao Ye
Published: March 2005

A white organic light-emitting diode with the structure of ITO∕NPB30nm∕TCTA+2%TPP20nm∕BCP+0.4%Ir(piq)320nm∕Alq340nm∕Mg:Ag was fabricated and characterized, where 2,5,7,10-tetra-phenylpyrene and tris(1-phenylisoquinoline) iridium (III) [Ir(piq)3] were used as a blue fluorescent dye and a red phosphorescent dye respectively. The I–V characteristics of the device showed a turn-on voltage of 2.6 V. The electroluminescent spectra of the device consisted of blue fluorescent and red phosphorescent emissions. The intensity of the blue emission increased gradually relative to the red emission with increasing voltage. The emissions of the device were in the white-light region between 10 and 15 V. A maximum white light luminance of 1076cd∕m2 with CIE coordinates of (x, y=0.27, 0.24) was reached at 15 V with an efficiency of 1.35cd∕A. The white light emission is related to the simultaneous exciton formation on both sides of the TCTA/BCP interface.
Highly rectifying Pr0.7Ca0.3MnO3∕SrTi0.9998Nb0.0002O3 p-n junction
Authors: Sawa A. , Fujii T. , Kawasaki M. , Tokura Y.
Published: March 2005

We have fabricated epitaxial Pr0.7Ca0.3MnO3∕SrTi0.9998Nb0.0002O3 (PCMO∕Nb:STO) junctions and characterized the interface electronic properties. The PCMO∕Nb:STO junctions show highly rectifying current density–voltage (J–V) characteristics without an apparent breakdown in the reverse bias up to 100V at room temperature. The J–V characteristics of the diodes agree well with the conventional diffusion theory for a p-n diode. The forward bias J–V and reverse bias capacitance-voltage characteristics result in an identical built-in potential of ∼0.7eV. Based on the experimental results, a plausible band diagram of the PCMO∕Nb:STO p-n diode is proposed.
On the formation and stability of p-type conductivity in nitrogen-doped zinc oxide
Authors: Barnes Teresa M. , Olson Kyle , Wolden Colin A.
Published: March 2005

The behavior of nitrogen in ZnO thin films grown by high-vacuum plasma-assisted chemical vapor deposition is examined. Highly oriented (002) films doped with 0–2at.% N were characterized by x-ray photoelectron spectroscopy, x-ray diffraction (XRD), Seebeck, and Hall measurements. XRD measurements revealed that the zinc oxide lattice constant decreased systematically with nitrogen doping. The as-deposited films were p-type at high doping levels, as confirmed by both Seebeck and Hall measurements. However, it was observed that hole conduction decreased and films reverted to n-type conductivity in a period of several days. This change was accompanied by a simultaneous increase in the lattice constant. The transient electrical behavior may be explained by compensation caused either by hydrogen donors or through defect formation processes common to analogous II-VI semiconductors.
Correlation between scanning-probe-induced spots and fixed positive charges in thin HfO2 films
Authors: Miyata Noriyuki , Ota Hiroyuki , Ichikawa Masakazu
Published: March 2005

Scanning tunneling microscopy observations revealed unstable species that likely act as fixed positive charges in thin HfO2 films. The density of these species can be practically reduced by low-temperature postdeposition annealing (∼550°C). The results of various annealing conditions suggest that hydrogenous species created by the reaction of moisture with as-deposited HfO2 films causes this type of fixed positive charges in the films.
External-cavity tunable mid-infrared laser using off-band surface-emitting Bragg grating coupler
Authors: Zhang H. L. , Peng C. , Seetharaman A. , Luo G. P. , Le Han Q. , Gmachl C. , Sivco D. L. , Cho A. Y.
Published: March 2005

An external-cavity laser using an integrated two-segment design allows broad and continuous wavelength tuning with independent control of power and wavelength. The laser has a gain segment and a surface-emitting Bragg grating segment that was designed to be off-band for zero reflection inside the cavity, and with a strong free-space coupling to an external mirror to form a linear cavity. Wavelength control was achieved with a combination of coarse and broad wavelength tuning (140nm) with the external mirror, and continuous, fine wavelength tuning via current-induced phase shift in the Bragg grating. Separate controls of the two segments allowed wavelength fine tuning without power variation and vice versa. The concept was applied to a 7μm laser, and is applicable to other wavelength.
Effects of ferroelectric fatigue on the piezoelectric properties (d33) of tetragonal lead zirconate titanate thin films
Authors: Gerber P. , Kügeler C. , Ellerkmann U. , Schorn P. , Böttger U. , Waser R.
Published: March 2005

The fatigue of the electromechanical properties of tetragonal PbZrx, Ti1−xO3 thin films is investigated. The decrease of electromechanical small-signal response is compared to the fatigue of the electric properties and examined in detail. Property fatigue is attributed mainly to switching-failure of the unit cells.
The neurotrophin-3 receptor TrkC directly phosphorylates and activates the nucleotide exchange factor Dbs to enhance Schwann cell migration
Authors: Yamauchi Junji , Chan Jonah R. , Miyamoto Yuki , Tsujimoto Gozoh , Shooter Eric M.
Published: March 2005

During the development of the peripheral nervous system, Schwann cells, the myelin-forming glia, migrate along axons before initiating myelination. We previously demonstrated that endogenous neurotrophin-3 (NT3) acting through the TrkC tyrosine kinase receptor enhances migration of premyelinating Schwann cells. This signaling pathway is mediated by the c-Jun N-terminal kinase (JNK) cascade regulated by the Rho GTPases Rac1 and Cdc42. However, missing is the link between TrkC and the GTPases. Here, we show that a guanine-nucleotide exchange factor (GEF), Dbl's big sister (Dbs), couples with TrkC to activate Cdc42 in Schwann cells. Furthermore, TrkC directly phosphorylates Dbs, thereby inducing the Cdc42-GEF activity. Taken together, activation of TrkC triggers Schwann cell migration by regulating Dbs upon direct tyrosine phosphorylation, providing a mechanism whereby a membrane receptor tyrosine kinase can induce the activation of Rho GTPase-GEFs.
DSM‐IV Diagnostic Criteria for Pathological Gambling: Reliability, Validity, and Classification Accuracy
Authors: Stinchfield Randy , Govoni Richard , Frisch G. Ron
Published: March 2005

The purpose of this study was to examine the reliability, validity, and classification accuracy of the DSM‐IV diagnostic criteria for pathological gambling. Given the lack of a laboratory test to diagnose pathological gambling, two groups were recruited in order to test DSM‐IV diagnostic classification accuracy, one which likely had the disorder and the other which likely did not have the disorder (121 men and women clients at a gambling treatment facility) (138 men and women selected at random from the Windsor, Ontario, community who had gambled in the past twelve months). The Gambling Behavior Interview was administered to both groups. The Gambling Behavior Interview includes items that measure the ten DSM‐IV diagnostic criteria for pathological gambling as well as other gambling problem severity measures and scales that served as tests of convergent validity. The ten DSM‐IV diagnostic criteria were found to exhibit satisfactory reliability, validity, and classification accuracy; however, lowering the cut score to four and using item weights yielded improved classification accuracy over the standard cut score of five. Some diagnostic criteria were found to have greater discriminatory power than other criteria. The results of this study suggest that the classification accuracy of DSM‐IV diagnostic criteria can be improved upon with a lower cut score or using weighted criteria.
Cisternal Rab Proteins Regulate Golgi Apparatus Redistribution in Response to Hypotonic Stress
Authors: Jiang Shu , Storrie Brian
Published: March 2005

We show that a physiological role of the extensively studied cisternal Golgi rab protein, rab6, is modulation of Golgi apparatus response to stress. Taking exposure of cells to hypotonic media as the best-known example of mammalian Golgi stress response, we found that hypotonic-induced tubule extension from the Golgi apparatus was sensitive to GDP-rab6a expression. Similarly, we found that Golgi tubulation induced by brefeldin A, a known microtubule-dependent process, was inhibited by GDP-restricted rab6a, rab6a′, and rab33b, the most commonly studied cisternal rab proteins. These GDP-rab levels were sufficient to inhibit rab-induced redistribution of Golgi glycosyltransferases into the endoplasmic reticulum (ER), also a microtubule-dependent process, and to depress Golgi membrane association of the GTP-conformer of rab6. Nocodazole-induced Golgi scattering, a microtubule-independent process, also was inhibited by GDP-rab6a expression. In comparison, we found similar GDP-rab expression levels had little inhibitory effect on another microtubule-independent process, constitutive recycling of Golgi resident proteins to the ER. We conclude that Golgi cisternal rabs, and in particular rab6a, are regulators of the Golgi response to stress and presumably the molecular targets of stress-activated signaling pathway(s). Moreover, we conclude that rab6a can regulate select microtubule-independent processes as well as microtubule-dependent processes.
High Mobility of Flap Endonuclease 1 and DNA Polymerase η Associated with Replication Foci in Mammalian S-Phase Nucleus
Authors: Solovjeva Lioudmila , Svetlova Maria , Sasina Lioudmila , Tanaka Kyoji , Saijo Masafumi , Nazarov Igor , Bradbury Morton , Tomilin Nikolai
Published: March 2005

Originally detected in fixed cells, DNA replication foci (RFi) were later visualized in living cells by using green fluorescent protein (GFP)-tagged proliferating cell nuclear antigen (PCNA) and DNA ligase I. It was shown using fluorescence redistribution after photobleaching (FRAP) assay that focal GFP-PCNA slowly exchanged, suggesting the existence of a stable replication holocomplex. Here, we used the FRAP assay to study the dynamics of the GFP-tagged PCNA-binding proteins: Flap endonuclease 1 (Fen1) and DNA polymerase η (Polη). We also used the GFP-Cockayne syndrome group A (CSA) protein, which does associate with transcription foci after DNA damage. In normal cells, GFP-Polη and GFP-Fen1 are mobile with residence times at RFi (tm) ∼2 and ∼0.8 s, respectively. GFP-CSA is also mobile but does not concentrate at discrete foci. After methyl methanesulfonate (MMS) damage, the mobile fraction of focal GFP-Fen1 decreased and tmincreased, but it then recovered. The mobilities of focal GFP-Polη and GFP-PCNA did not change after MMS. The mobility of GFP-CSA did not change after UV-irradiation. These data indicate that the normal replication complex contains at least two mobile subunits. The decrease of the mobile fraction of focal GFP-Fen1 after DNA damage suggests that Fen1 exchange depends on the rate of movement of replication forks.
Myosin-1a Is Critical for Normal Brush Border Structure and Composition
Authors: Tyska Matthew J. , Mackey Andrew T. , Huang Jian-Dong , Copeland Neil G. , Jenkins Nancy A. , Mooseker Mark S.
Published: March 2005

To develop our understanding of myosin-1a function in vivo, we have created a mouse line null for the myosin-1a gene. Myosin-1a knockout mice demonstrate no overt phenotypes at the whole animal level but exhibit significant perturbations and signs of stress at the cellular level. Among these are defects in microvillar membrane morphology, distinct changes in brush-border organization, loss of numerous cytoskeletal and membrane components from the brush border, and redistribution of intermediate filament proteins into the brush border. We also observed significant ectopic recruitment of another short-tailed class I motor, myosin-1c, into the brush border of knockout enterocytes. This latter finding, a clear demonstration of functional redundancy among vertebrate myosins-I, may account for the lack of a whole animal phenotype. Nevertheless, these results indicate that myosin-1a is a critical multifunctional component of the enterocyte, required for maintaining the normal composition and highly ordered structure of the brush border.
Unlimited Taxation, Public Credit, and the Strength of Government
Authors: Edling Max. M
Published: March 2005

Provides the layout of the Federalist argument that Congress had to possess an unlimited power to raise men and money from American society without any intervention from the states. While the following chapter looks in greater depth at Antifederalist objections to the federal fiscal powers of the US Constitution, here the concern is solely with the restrictions to this power that they suggested in the form of amendments. The reasons are discussed as to why the Federalists refused to accept these Antifederalist amendments (and indeed any restrictions on the fiscal power of Congress other than those already written into the Constitution), repeatedly and forcefully making it clear why it was crucial that no restrictions be placed on the right of Congress to extract money from society by means of taxation. The different sections of the chapter argue that the need for an unbridled federal right to raise tax revenue arose from the conviction that Congress had to have full command over all the resources of the nation in times of crisis. Primarily, this was needed so that the government could borrow money abroad and at home, which suggests that the Federalists designed the Constitution as much for future challenges as for present problems, and that for this reason, they refused to let the powers of the national government be defined by the demands on the union existing in the late 1780s, but instead strove to create a government with powers sufficiently extensive to safeguard the union's future existence, in peace as well as in war.
A Government for Free
Authors: Edling Max. M
Published: March 2005

Shows how the Federalists responded to the Antifederalist objections to a stronger national government in the “fiscal‐military” sphere, thereby creating an understanding of the kind of state that was proper to American conditions. In the debate over ratification of the US Constitution there was little discussion about the exact way in which the Federalists intended to organize the revenue administration, but nevertheless, it is the argument of this chapter that with the important exception of the assumption of the state debts, the general outline of Hamiltonian public finance was in place in 1787, and widely shared by the supporters of the Constitution. Thus, the idea that the least oppressive tax was also the most productive, the claim that adoption of the Constitution would mean a change in the structure of taxation from direct to indirect taxes and a reliance on the impost (customs duties), and the ideal of the federal government as a “waterfront state” hardly noticed by the people, were all among the most important points made in Federalist rhetoric on the fiscal powers of the Constitution. In the ratifying debate, the Federalists presented a solution to the equation of how to create a sufficiently powerful government without making unacceptable demands on society: the federal government had the right to mobilize the full resources of society at will, but in peacetime it would keep a very low profile while assuming the payment of the union's debts and the cost of defense using money raised by taxation. This federal assumption of expenses that had earlier been carried by the states, and the mode of raising the taxes to pay for it ensured that overall taxation would not increase, as the Antifederalists claimed, but would become less burdensome to the majority of the people.
Eucalyptus
foliar chemistry explains selective feeding by koalas
Authors: Moore Ben D , Foley William J , Wallis Ian R , Cowling Ann , Handasyde Kathrine A
Published: March 2005

The koala is the quintessential specialist herbivore, feeding almost exclusively on
Eucalyptus
foliage. Consequently, the limitations imposed on the koala's diet by plant defences indicate the extent to which evolutionary adaptations allow mammalian herbivores to circumvent such defences. We tested whether a recently discovered group of plant secondary metabolites, the formylated phloroglucinol compounds (FPCs), deters koalas from feeding on some eucalypt foliage. We found that captive koalas ate less foliage in a single night from trees with high FPC concentrations. Individual trees also differ in the types of FPC they possess, but for a given eucalypt species, most FPCs were similarly effective deterrents. Two closely related and sympatric eucalypt species could be clearly separated by the amounts that koalas ate from each; however, this difference could not be explained by total FPC concentrations alone. We suggest, that in this case, the presence of a distinct type of FPC deters koala herbivory on the less palatable species, and may have facilitated the evolutionary divergence of these species. We conclude that plant defences probably play an important role in determining the distribution and abundance of koalas.
Identification of the DNA-binding site of the Rgg-like regulator LasX within the lactocin S promoter region
Authors: Rawlinson Elizabeth L. Andersen , Nes Ingolf F. , Skaugen Morten
Published: March 2005

LasX regulates the transcription of the divergent operonslasXYandlasA–W, which specify the production of lactocin S inLactobacillus sakeiL45. Using histidine-tagged LasX, and a DNA fragment containing the complete intergeniclasA–lasXregion, electrophoresis mobility-shift (EMSA) analyses were employed to demonstrate that LasX binds to thelasA–lasXintergenic DNA. Two direct heptanucleotide motifs directly upstream of PlasA–W, and a third imperfect copy of this motif, overlapping the −10 element of PlasA–W, were identified as possible LasX-binding sites. To assess the role of the direct repeats in the binding of LasX to the intergeniclasA–lasXregion, binding experiments were performed using DNA probes with different combinations of the repeats, and with arbitrarily chosen repeat substitutions. The result of these experiments demonstrated that only the middle repeat was required for the binding of LasX to thelas-promoter region. This observation correlated with the results of subsequent reporter-gene analyses, thereby weakening the hypothesis of the involvement of the direct repeats in LasX-mediated transcription regulation. By analysing the ability of LasX to bind successively shortened derivatives of the original intergenic fragment, a tentative 19 bp minimum LasX-binding site was identified.
The pel genes of the Pseudomonas aeruginosa PAK strain are involved at early and late stages of biofilm formation
Authors: Vasseur Perrine , Vallet-Gely Isabelle , Soscia Chantal , Genin Stéphane , Filloux Alain
Published: March 2005

Pseudomonas aeruginosais a Gram-negative bacterium associated with nosocomial infections and cystic fibrosis. Chronic bacterial infections are increasingly associated with the biofilm lifestyle in which microcolonies are embedded in an extracellular matrix. Screening procedures for identifying biofilm-deficient strains have allowed the characterization of several key determinants involved in this process. Biofilm-deficientP. aeruginosaPAK strains affected in a seven-gene cluster calledpelwere characterized. Thepelgenes encode proteins with similarity to components involved in polysaccharide biogenesis, of which PelF is a putative glycosyltransferase. PelG was also identified as a putative component of the polysaccharide transporter (PST) family. Thepelgenes were previously identified in theP. aeruginosaPA14 strain as required for the production of a glucose-rich matrix material involved in the formation of a thick pellicle and resistant biofilm. However, in PA14, thepelmutants have no clear phenotype in the initiation phase of attachment. It was shown thatpelmutations in the PAK strain had little influence on biofilm initiation but, as in PA14, appeared to generate the least robust and mature biofilms. Strikingly, by constructingpelmutants in a non-piliatedP. aeruginosaPAK strain, an unexpected effect of thepelmutation in the early phase of biofilm formation was discovered, since it was observed that these mutants were severely defective in the attachment process on solid surfaces. Thepelgene cluster is conserved in other Gram-negative bacteria, and mutation in aRalstonia solanacearum pelGhomologue,ragG, led to an adherence defect.