bluuebunny/crossref_metadata_2025 huggingface dataset:
Preparation of Whisker β‐Spodumene Glass–Ceramics
Authors: Anmin Hu , Ming Li , Dali Mao
Published: September 2005

β‐spodumene glass–ceramics with a whisker‐like microstructure were prepared from the following materials (in wt%): 64.5 SiO2, 18.0 Al2O3, 4.2 Li2O, 4 ZrO2, and 8 MgF2. Scanning electron microscope (SEM) analysis showed that phase separation in the base glass leads to the formation of a primary crystal phase of MgF2 that promotes the formation of spherical β‐spodumene. Whisker spodumene crystals surrounded by spherical crystals are observed at 720°C after 1 h, and the whisker crystals grow at the cost of spherical crystals with increasing temperature and time. The flexural strengths of the glass–ceramics reach a maximum of 228 MPa after heat treatment at 850°C for 1 h.
Fabrication and Characterization of Carbon Nanotube–Titanium Nitride Composites with Enhanced Electrical and Electrochemical Properties
Authors: Jiang Linqin , Gao Lian
Published: September 2005

This work reports the fabrication and the characterization of a new composite consisting of multiwalled carbon nanotubes (CNTs) and conducting titanium nitride (TiN) with a higher specific surface area (SBET), enhanced electrical conductivity (σ), and specific capacitance. With increasing CNT content, the electrical conductivity and electrochemical performance of the CNT–TiN composites gradually increase. In the presence of 5 wt% (12.0 vol%) CNTs, the electrical conductivity and the weight‐specific capacitance of CNT–TiN composite are increased by 3.6 times and 54.8% compared with pure TiN, respectively.
Influence of Li2O Doping on Non‐Isothermal Evolution of Phases in K–Na‐Containing Aluminosilicate Matrix
Authors: Tulyaganov Dilshat U. , Agathopoulos Simeon , Fernandes Hugo R. , Ferreira José M. F. , Fabrichnaya Olga
Published: September 2005

The phase transformations in Li2O‐doped model formulations (using 1–7% Li2CO3), which comprised 50% kaolin, 25% feldspar, and 25% quartz (in wt%), were investigated experimentally and with the aid of thermodynamic calculations between 900° and 1350°C. Experimental and theoretical approaches agree fairly well with another and indicated that the presence of Li2O and other alkalis, such as K2O, in aluminosilicate matrices plays an important role in the phase transformations that occur at different temperatures during firing. Discrepancies in experimental results from thermodynamics have been attributed to slow kinetics, also likely because of the nature of the raw materials used.
Highly Creep‐Resistant Silicon Nitride/Silicon Carbide Nano–Nano Composites
Authors: Wan Julin , Duan Ren‐Guan , Gasch Matthew J. , Mukherjee Amiya K.
Published: September 2005

A high creep resistance at specified temperature and compressive stress was obtained in this investigation in the silicon nitride/silicon carbide composite with a nano–nano structure (nanosized SiC and Si3N4 in dual‐phase mixture) by a novel synthesis method. Starting from an amorphous Si–C–N powder derived from pyrolysis of a liquid polymer precursor, nanocomposites with varied grain size were achieved. With yttria additive amount decreasing from 8 to 1 wt% and eventually to zero, the structure underwent a transition from micro‐nano (nano‐sized SiC included in sub‐micron Si3N4) to nano–nano type. Nanocrystalline silicon nitride/silicon carbide ceramic composite with 30–50 nm grain size was synthesized without using sintering additive.
Solidification Behavior of Calcium Aluminosilicate Melts Containing Magnesia and Fluorspar
Authors: Park Joo Hyun
Published: September 2005

The details of the microstructural characteristics of the CaO–SiO2–MgO–Al2O3 (–CaF2) systems solidified during slow cooling from 1600°C, which are critical to understanding the fundamentals of inclusion formation in the stainless steelmaking processes, were investigated using scanning electron microscope and energy‐dispersive X‐ray spectrometer. Especially, the effect of fluorspar on the solidification behavior of the melts was studied. In addition, the phase equilibria at a specific temperature and composition during cooling cycles were computed using commercial thermodynamic software based on the Gibbs energy minimization principles and were compared with the measured results. In the slag of B=0.6 containing 30 wt% Al2O3, the relative fractions of spinel and anorthite continuously increase with decreasing temperature from about 1300° to 1150°C, followed by constant values at temperatures less than about 1100°C. In the liquid slag of B=1.0, the spinel phase appears at temperatures greater than about 1350°C, followed by the formation of melilite and their relative fractions increase with decreasing temperatures from about 1300° to 1200°C. The anorthite appears at temperatures less than about 1200°C. The calculated results could explain the observed phenomena. In the system of B=0.6 containing 10 wt% CaF2 and 30 wt% Al2O3, the spinel phase was calculated to be in equilibrium with anorthite and merwinite. However, anorthite was not observed in the experiments. This could be understood from the changes in melt composition because of formation of gaseous fluoride SiF4. The observed phenomena and the calculated results commonly indicated that the amount and the size of spinel crystallized in the slag (B=1.0, 5 wt% CaF2) increased on increasing the content of alumina from 10 to 30 wt%. The size of spinel in the slag of B=1.0 containing 30 wt% Al2O3 decreased, and thus the number of spinel per unit volume increased with increasing content of fluorspar up to 10 wt%. The shape of spinel changed from polygonal to irregular (or broken) type on increasing the content of fluorspar.
Interstitial Oxygen in Tin‐Doped Indium Oxide Transparent Conductors
Authors: Warschkow Oliver , Miljacic Lj. , Ellis D. E. , González G. B. , Mason T. O.
Published: September 2005

We report first‐principles density functional theory calculations of interstitial oxygen in tin‐doped indium oxide (ITO), a transparent conducting oxide. Interstitial oxygen plays a critical role in the defect of ITO because it is by removal of interstitial oxygen that n‐type charge carriers are produced. The Frank and Köstlin defect model successfully rationalizes the observed conductivity, Sn‐doping, and oxygen partial pressure dependencies of ITO by postulating that tin atoms, which substitute for indium, are clustered with interstitial oxygen. Structural evidence for such a clustering, however, remains ambiguous. Recently published Rietveld refinement results of X‐ray and neutron diffraction data found interstitial oxygen to be significantly displaced (0.4 Å) from the ideal fourfold position. Our calculations show that the experimental position is plausible only if interstitial oxygen is clustered with SnIn defects at any of the three d‐type cation sites nearest to the interstitial, thereby providing direct structural confirmation of the Frank and Köstlin defect model.
Interpreting Impedance Response of Silicon Carbide Whisker/Alumina Composites Through Microstructural Simulation
Authors: Mebane David S. , Gerhardt Rosario A.
Published: September 2005

A three‐dimensional, object‐defined Monte Carlo simulation is applied to alumina‐silicon carbide whisker ceramic matrix composites. The simulation takes whisker orientation and size distributions into account simultaneously, and calculates a connectivity factor that relates whisker conductivity to macroscopic conductivity. Simulation results are compared with electrical measurements taken on real samples via impedance spectroscopy. Results show that the effect of whisker clumping can be seen in the impedance response as a decrease in the overall measured conductivity. Results also show that interfacial resistance influences the overall resistivity strongly relative to connectivity at volume fractions far above the percolation threshold. The possible mechanisms for interfacial resistance in the composite and their effect on the impedance response are discussed.
Synthesis of Nanocrystalline Aluminum Nitride by Nitridation of δ‐Al2O3 Nanoparticles in Flowing Ammonia
Authors: Zhang Qinghong , Gao Lian
Published: September 2005

Nanocrystalline aluminum nitride (AlN) with surface area more than 30 m2/g was synthesized by nitridation of nanosized δ‐Al2O3 particles using NH3 as a reacting gas. The resulting powders were characterized by CHN elemental analysis, X‐ray diffraction (XRD), Fourier transform infrared spectra, X‐ray photoelectron spectra, field‐emission scanning electron microscopy, transmission electron microscopy, and Brunauer–Emmett–Teller surface area techniques. It was found that nanocrystalline δ‐Al2O3 was converted into AlN completely (by XRD) at 1350°–1400°C within 5.0 h in a single‐step synthesis process. The complete nitridation of nanosized alumina at relatively lower temperatures was attributed to the lack of coarsening of the initial δ‐Al2O3 powder. The effect of precursor powder types on the conversion was also investigated, and it was found that α‐Al2O3 was hard to convert to AlN under the same conditions.
Mechanical Failure of Bent Optical Fiber Subjected to High Power
Authors: Glaesemann G. Scott , Winningham Michael J. , Clark Donald A. , Coon Jeffrey , DeMartino Steven E. , Logunov Stephan L. , Chien Ching‐Kee
Published: September 2005

As optical fiber penetrates further into the communications infrastructure and comes closer to the home or business, higher optical power levels are expected. Several studies have shown that sharply bent optical fiber will fail prematurely when exposed to high optical power levels. In an extreme case, where the fiber is bent to a maximum bend stress on the order of 2 GPa and subjected to a power level of 1–2 W in the near‐infrared wavelength window, optical fiber will fail in minutes. Time to failure decreases with increasing bend stress and optical power. A recent report suggests that power levels in the range of a few hundred milliwatts may be enough to induce delayed failure in bent fiber. This study explores the progression of events leading to failure. Light that escapes the core of bent fiber passes into the coating, where a small amount is absorbed and converted to heat. The coating heats to a stable temperature and visually darkens with time. This is followed by an abrupt rise in temperature, which occurs as the coating transforms to a highly absorptive material, consistent with thermal runaway. The abrupt rise in coating temperature stimulates viscoelastic deformation of the glass. Glass deformation is explained in terms of the ability of highly quenched glass to experience viscous flow at temperatures well below the glass transition range (i.e. sub‐Tg aging or relaxation). As the glass portion of the fiber moves toward a “kinked” configuration, it concentrates more power on a smaller region of coating, resulting in further temperature increase. There is no evidence of the fiber fuse effect in the lower viscosity glass core. The final kinked configuration of the glass fiber leads to complete attenuation of the light and failure is complete. Coating decomposition is self‐limiting with no visible flame. A coating with a refractive index near or below that of silica was found to virtually eliminate this failure mode.
Enhancement of Magnetization and Curie Temperature in Sr2FeMoO6 by Ni Doping
Authors: Li Chen , Cailei Yuan , Junmin Xue , Wang John
Published: September 2005

Doping Ni in Sr2(Fe1−xNix)MoO6 (SFNMO) (0.00≤x≤0.20) significantly affects its magnetic behaviors. Having successfully synthesized the double perovskite structure using MoO2 as the starting material via a mechanical activation route, we have investigated the effects of Ni doping on the long‐range B‐site order and magnetic behaviors of (SFNMO), in which the long‐range B‐site order between B and B′ cations is progressively enhanced by an increasing level of Ni doping. Accordingly, both magnetization and the Curie temperature of Sr2FeMoO6 are enhanced, where they both depend almost linearly on the degree of long‐range B‐site order.
Direct Evidence of Temperature Variation Within Ceramic Powder Compact During Pulse Electric Current Sintering
Authors: Zhang Dongming , Zhang Lianmeng , Guo Jingkun , Tuan Wei‐Hsing
Published: September 2005

Pulse electric current sintering (PECS) is a powerful technique for the preparation of nanoceramics. However, the temperature distribution within the ceramic powder compact during PECS is not uniform. In the present study, aluminum hydroxide powder is used as an in situ temperature indicator to determine the temperature uniformity. The phase evolution within the powder compact is taken to estimate its temperature distribution. The temperature is highest near the top surface of the compact; it then reduces with increasing distance away from the top surface of the compact. The temperature variation can be significantly reduced by inserting a carbon paper in between graphite punches and graphite mold and also by reducing the heating rate.
Intravitreal triamcinalone acetonide for refractory uveitic cystoid macular oedema: longterm management and outcome
Authors: Angunawela R. I. , Heatley C. J. , Williamson T. H. , Spalton D. J. , Graham E. M. , Antcliffe R. J. , Stanford M. R.
Published: September 2005

Purpose:  To establish the role of intravitreal triamcinalone acetonide (TA) in the long term management of refractory uveitic cystoid macular oedema (CMO) and to determine the long term visual outcome in these patients.

Method:  This is a retrospective observational case series. All patients had resistant CMO and active inflammation. The primary outcome measure was complete resolution of CMO on ocular coherence tomography. Visual acuity and intraocular pressure were also monitored. Twelve eyes of twelve patients received 2 (n = 10) to 4 (n = 2) mg of intravitreal TA. All had previously been unresponsive to orbital floor steroids. Fluorescein angiography was performed where indicated.

Results:  There was complete resolution of CMO in all patients. Nine patients had improvement in acuity at there final follow up (mean follow up 40.5 months). Seven had improved by 2 lines (58%). In 3 patients there was no visual improvement. These 3 failed to respond to re‐treatment. Five other patients were re‐treated because of recurring CMO and deteriorating VA (median time to re‐treatment 4 mths). The mean number of re‐treatments for this group with orbital floor TA was three. 41.6% of patients developed ocular hypertension (33.8 mhg mean). One required a trabeculectomy.

Conclusions:  2 mg of intravitreal TA is effective even in cases of resistant uveitic CMO. Although re‐treatment is often required, the initial response to treatment can be maintained by subsequent orbital floor steroid injections.
The expression pattern of the subunit of chaperonin containing T‐complex polypeptide 1 and its substrate, α‐smooth muscle actin, during corneal wound healing
Authors: Koulikovska Marina , Podskochy Alexander , Fagerholm Per
Published: September 2005

Purpose:  This study was designed to demonstrate the expression of the chaperonin containing T‐complex polypeptide 1 (CCT) and α‐smooth muscle actin (α‐SMA), in normal corneas and corneas treated with ultraviolet radiation (UVR). The wound model chosen is previously characterized, the injury is mild and the cornea heals to transparency.

Methods:  Rabbit corneas were exposed to UVR at the dose producing keratitis. The corneas were allowed to heal for up to 5 days and the paraffin‐embedded tissue specimens were double stained and examined morphologically and immunohistochemically. Expression of CCT and α‐SMA genes was investigated by semiquantitative reverse transcription‐polymerase chain reaction (RT‐PCR).

Results:  There was a front of repopulating keratocytes that showed positive staining for α‐SMA after 3 days. The α‐SMA mRNA was already strongly expressed after 1 day, whereas the expression level of CCT was increased after 2 days. After 5 days the levels were decreased. By this time the stroma was partly repopulated by keratocytes.

Conclusion:  In a mild wound, the expression of α‐SMA mRNA is followed by expression of mRNA of at least one subunit of the complex folding α‐SMA. At protein level, α‐SMA is detected in the front line of repopulating keratocytes. Expression levels for both mRNAs decline as the stroma repopulation process progresses.
Quantitative grading of preretinal neovascularization in adult rats
Authors: Lai Chi‐Chun , Wu Wei‐Chi , Chuang Lan‐Hsin , Yeung Ling , Wei William , Yang Ko‐Jen
Published: September 2005

Purpose:  To quantify photodynamic venous occlusion‐induced preretinal neovascularization with fluorescein isothiocyanate‐dextran (FITC‐dextran) angiography in adult Sprague‐Dawley rats.

Methods:  Argon green laser was used to ablate retinal veins in the experimental group (24 rats), and applied between the vessels in the control group (10 rats) after systemic injection of rose bengal. Animals were systemically infused with FITC‐dextran and killed 14 days after laser treatment. Retinal flat‐mounts were observed under a fluorescence microscope. The number and area of neovascular tufts were measured. Confocal microscopy and histological study were performed to rule out possible artifacts, and to confirm FITC‐dextran angiography findings.

Results:  Out of the entire group of 34 albino rats, no preretinal neovascularization was found in the control group (total 20 eyes, 10 rats). In the experimental group (total 48 eyes, 24 rats) 43 eyes (90%) developed well demarcated neovascular tufts revealed by FITC‐dextran angiography. This well demarcated boundary of neovascular tufts was reconfirmed by confocal microscopy and histological study. There were no significant differences in the number or area of neovascular tufts between the right and left eyes.

Conclusion:  FITC‐dextran angiography provides a time‐ and labour‐efficient basis for quantifying both the number and area of preretinal neovascularization induced by photodynamic venous occlusion in adult rats. This model is suitable for angiostatic study in the adult animals.
Phacoemulsification in trabeculectomized eyes
Authors: Ehrnrooth Pia , Lehto Ilkka , Puska Päivi , Laatikainen Leila
Published: September 2005

Purpose:  To evaluate retrospectively risk indicators for cataract surgery and the effect of phacoemulsification on intraocular pressure (IOP) control in eyes that have undergone trabeculectomy.

Methods:  We undertook a retrospective analysis of 138 eyes with primary open‐angle glaucoma (POAG) or exfoliation glaucoma (EG) in 138 consecutive patients over the age of 40 years undergoing trabeculectomy with no antimetabolites performed by one surgeon. Of the 48 eyes (35%) undergoing a cataract operation during the follow‐up period of 2–5 years, 46 were included in this analysis. Their IOP, glaucoma medication and best corrected visual acuity (BCVA) before cataract surgery and at the last follow‐up were compared. Risk indicators for cataract surgery were analysed.

Results:  Cataract operations were performed 5.1–58.1 months (median 14.4 months) after trabeculectomy. The mean length of follow‐up after cataract surgery was 25.3 months (SD 12.9, median 24.8 months). Before cataract surgery, the mean IOP was 16.2 mmHg (SD 4.9) and the mean number of topical antiglaucoma medicines 0.8 (SD 1.0). At the most recent visit, mean IOP was 17.3 mmHg (SD 6.4) (p = 0.35), and the mean number of medicines was 1.3 (SD 1.1) (p = 0.0007). Of the 22 eyes in which treatment had been categorized as completely successful (IOP ≤ 21 mmHg without other therapy) before cataract surgery, 13 (59%) had remained so. The number of failures (IOP > 21 mmHg, or more than one medication needed or further surgery performed) increased from 14 (30%) before surgery to 28 (61%) afterwards. The proportion of failures in the cataract surgery group was twice that in the no cataract surgery group (61% versus 31%). In a proportional hazards regression, only age (73.9 years [SD 9.4] and 68.1 years [SD 9.8] in patients with and without cataract surgery, respectively) proved to be a significant (p = 0.001) indicator for surgery.

Conclusion:  The results of this retrospective study on consecutive clinical cases of trabeculectomy indicate that cataract progression after trabeculectomy is mainly an age‐related process. In more than half the eyes with good preoperative IOP control, this good control was maintained after cataract surgery. On the other hand, in some eyes cataract surgery may compromise IOP control even when surgery avoids the area of the bleb.
Photo‐induced foveal injury after viewing a solar eclipse
Authors: Källmark Fredrik P. , Ygge Jan
Published: September 2005

Purpose:  To study the injury to and possible recovery of the visual function and foveal morphology in patients with photo‐induced foveal injury due to watching the solar eclipse of August 11th, 1999 in Stockholm, Sweden.

Methods:  Fifteen patients, all of whom viewed the solar eclipse, were followed for 1 year, during which their visual symptoms were recorded and visual acuity (VA) was tested, and ophthalmoscopy and scanning laser ophthalmoscopy were performed.

Results:  Photo‐induced foveal injury gave rise to subjective visual disturbances, reduced VA and morphological changes in the fovea. Central scotomas could still be seen in all patients 1 year after the foveal injury.

Conclusion:  Photo‐induced foveal injury gave rise to subjective visual disturbances, reduced VA and morphological changes in the fovea. Scanning laser ophthalmoscopy offers the possibility of detailed examination of small retinal lesions, which can sometimes be difficult to localize with ophthalmoscopy.
Central visual field changes using flicker perimetry in type 2 diabetes mellitus
Authors: Stavrou Efty P. , Wood Joanne M.
Published: September 2005

Purpose:  To evaluate the efficacy of flicker perimetry compared with that of static perimetry in determining central visual field losses in participants with type 2 diabetes mellitus.

Methods:  Flicker and static perimetry were performed using the Medmont field analyser on 20 participants with type 2 diabetes mellitus and 24 age‐matched control participants.

Results:  Flicker, but not static, perimetry demonstrated significant reductions in thresholds in those participants who had a recent diagnosis of diabetes or who had no or only minimal diabetic retinopathy compared to the control group at eccentricities close to fixation.

Conclusion:  Flicker perimetry is recommended for the evaluation of visual field losses in participants with recent onset of diabetes and minimal diabetic retinopathy.
Characterization of novel sequence motifs within N‐ and C‐terminal extensions of p26, a small heat shock protein from Artemia franciscana
Authors: Sun Yu , MacRae Thomas H.
Published: September 2005

The small heat shock proteins function as molecular chaperones, an activity often requiring reversible oligomerization and which protects against irreversible protein denaturation. An abundantly produced small heat shock protein termed p26 is thought to contribute to the remarkable stress resistance exhibited by encysted embryos of the crustacean, Artemia franciscana. Three novel sequence motifs termed G, R and TS were individually deleted from p26 by site‐directed mutagenesis. G encompasses residues G8–G29, a glycine‐enriched region, and R includes residues R36–R45, an arginine‐enhanced sequence, both in the amino terminus. TS, composed of residues T169–T186, resides in the carboxy‐extension and is augmented in threonine and serine. Deletion of R had more influence than removal of G on p26 oligomerization and chaperoning, the latter determined by thermotolerance induction in Escherichia coli, protection of insulin and citrate synthase from dithiothreitol‐ and heat‐induced aggregation, respectively, and preservation of citrate synthase activity upon heating. Oligomerization of the TS and R variants was similar, but the TS deletion was slightly more effective than R as a chaperone. The extent of p26 structural perturbation introduced by internal deletions, including modification of intrinsic fluorescence, 1‐anilino‐8‐naphthalene‐sulphonate binding and secondary structure, paralleled reductions in oligomerization and chaperoning. Three‐dimensional modeling of p26 based on wheat Hsp16.9 crystal structure indicated many similarities between the two proteins, including peptide loops associated with secondary structure elements. Loop 1 of p26 was deleted in the G variant with minimal effect on oligomerization and chaperoning, whereas loop 3, containing β‐strand 6 was smaller than the corresponding loop in Hsp16.9, which may influence p26 function.
Histones in functional diversification
Authors: Pusarla Rama‐Haritha , Bhargava Purnima
Published: September 2005

Recent research suggests that minor changes in the primary sequence of the conserved histones may become major determinants for the chromatin structure regulating gene expression and other DNA‐related processes. An analysis of the involvement of different core histone variants in different nuclear processes and the structure of different variant nucleosome cores shows that this may indeed be so. Histone variants may also be involved in demarcating functional regions of the chromatin. We discuss in this review why two of the four core histones show higher variation. A comparison of the status of variants in yeast with those from higher eukaryotes suggests that histone variants have evolved in synchrony with functional requirement of the cell.
Mid-infrared imaging of NGC 1068 with VISIR at the Very Large Telescope
Authors: Galliano E. , Pantin E. , Alloin D. , Lagage P. O.
Published: September 2005

High-resolution mid-infrared (MIR) images of the central region of NGC 1068 have been obtained with VISIR, the multi-mode MIR instrument recently installed at the European Southern Observatory Very Large Telescope on Paranal. A map of the emission at 12.8 μm with increased sensitivity over the central 8 × 8 arcsec2 area is discussed. It shows a central core (unresolved along the east—west direction) and extended emission which has a spiral pattern similar to that observed in near-infrared images. Patches of MIR emission can be detected up to a distance of 4 arcsec from the core. The deconvolved 12.8-μm map is fully consistent with previous high-resolution MIR observations. It highlights the structure of the extended emission, already seen in the un-deconvolved image, and allows us to identify a set of MIR sources: seven in the north-eastern quadrant and five in the south-western quadrant. The MIR emission map is compared with those obtained at comparable angular resolution in the near-infrared and in [O iii] line emission. The very good correlation between the VISIR map and the Hubble Space Telescope optical map supports the idea that the MIR emission not associated with the torus arises from dust associated with the narrow-line-region clouds. The north—south extension of the MIR core (0.44 arcsec) is then probably simply due to the mixing of the MIR emission from the dusty torus and the MIR emission from narrow-line-region cloud B, located only 0.1 arcsec to the north.
Dynamical virial masses of Lyman-break galaxy haloes at z = 3
Authors: Weatherley Stephen J. , Warren Stephen J.
Published: September 2005

We improve on our earlier dynamical estimate of the virial masses of the haloes of Lyman-break galaxies (LBGs) at redshift z= 3 by accounting for the effects of seeing, slit width and observational uncertainties. From an analysis of the small number of available rotation curves for LBGs we determine a relation Vc7= (1.9 ± 0.2)σ between circular velocity at a radius of 7 kpc, Vc7, and central line velocity width, σ. We use this relation to transform the measured velocity widths of 32 LBGs to the distribution of circular velocities, Vc7, for the population of LBGs brighter than . We compare this distribution against the predicted distribution for the ‘massive-halo’ model in which LBGs pinpoint all of the highest mass dark matter haloes at that epoch. The observed LBG circular velocities are smaller than the predicted circular velocities by a factor of >1.4 ± 0.15. This is a lower limit, as we have ignored any increase of circular velocity caused by baryonic dissipation. The massive-halo model predicts a median halo virial mass of 1012.3 M⊙, and a small spread of circular velocities, Vc7. Our median estimated dynamical mass is <1011.6±0.3 M⊙, which is significantly smaller; furthermore, the spread of our derived circular velocities is much larger than the massive-halo prediction. These results are consistent with a picture which leaves some of the most massive haloes available for occupation by other populations which do not meet the LBG selection criteria. Our new dynamical mass limit is a factor of 3 larger than our earlier estimate which neglected the effects of seeing and slit width. The median halo mass recently estimated by Adelberger et al. from the measured clustering of LBGs is 1011.86±0.3 M⊙. Our dynamical analysis appears to favour lower masses and to be more in line with the median mass predicted by the collisional starburst model of Somerville et al., which is 1011.3 M⊙.
Winter energetics of Virginia opossumsDidelphis virginianaand implications for the species’ northern distributional limit
Authors: Kanda L. Leann
Published: September 2005

While climatic limitations are widely recognized as primary factors determining the distributions of many species, the physiological link between climate and species’ persistence is poorly understood. The Virginia opossumDidelphis virginianais a species for which winter energetics have been evaluated and a northern geographical limit has been hypothesized. Expansion of opossum populations beyond this limit, however, suggests that a previous winter energetics model requires modification. I update this energetics model by incorporating random foraging success to estimate the probability of opossum survival under varying winter temperature regimes. Estimation of opossum “success” for winters in Amherst, Massachusetts, since 1926 showed that juvenile females, the key breeding component of the population, would survive at a rate high enough to maintain a stable population in only 4 of the 77 yr. The model correctly predicted the fate of 13 of 14 opossums monitored in the Amherst area during the winters of 2000–2003. The current energetics model does not correctly predict autumn weight gain, but it does accurately estimate opossum winter survival. However, the model predicts that opossums should be winter‐limited in areas such as Amherst, Massachusetts, where in fact they are well established. This discrepancy may be explained in three ways: weather station data do not adequately reflect available microclimates, opossums show high levels of flexibility in cold‐weather foraging behavior, and most likely, humans provide food and shelter that mitigate the effect of winter.
What is a patch in a dynamic metapopulation? Mobility of an endangered woodland butterfly,Euphydryas maturna
Authors: Cizek Oldrich , Konvicka Martin
Published: September 2005

In metapopulations of butterflies inhabiting transient forest openings, the dynamic character of biotopes prevents unequivocal delimitation of habitat patches, complicating analyses of inter‐patch dispersal. We analyse mobility of one such metapopulation, using mark‐recapture data on an endangered butterfly, the scarce fritillaryEuphydryas maturna, at its last site in the Czech Republic. The butterfly inhabits woodland clearings, its population numbered 190 individuals in 2002. We modelled movements in eight habitat patchworks delimited according to different criteria and superimposed over the forest, using the Virtual Migration model. Resulting mobility parameters were generally robust against patchwork definitions, the main distinction was between patchworks based on presence of adults and consisting of small patches and patchworks based on distributions of larval nests and consisting of large patches. Emigration constant decreased towards the latter, whereas males suffered higher migration mortality than females in the former. Patchworks delimited according to presence of adults performed better than patchworks based on distribution of larval nests. A comparison of our parameters with those found for the species in Finland showed that the Czech butterflies were more prone to leave individual patches and suffered higher migration mortality, which combined into considerably shorter survival. We conclude that transferring dispersal parameters among different regions and populations is more risky than using less suitable definitions of habitat patches within single region.
Effect of Ribavirin on Intracellular and Plasma Pharmacokinetics of Nucleoside Reverse Transcriptase Inhibitors in Patients with Human Immunodeficiency Virus-Hepatitis C Virus Coinfection: Results of a Randomized Clinical Study
Authors: Rodriguez-Torres M. , Torriani F. J. , Soriano V. , Borucki M. J. , Lissen E. , Sulkowski M. , Dieterich D. , Wang K. , Gries J.-M. , Hoggard P. G. , Back D.
Published: September 2005

The intracellular triphosphorylation and plasma pharmacokinetics of lamivudine (3TC), stavudine (d4T), and zidovudine (ZDV) were assessed in a pharmacokinetic substudy, in 56 human immunodeficiency virus-hepatitis C virus (HIV-HCV) coinfected patients receiving peginterferon alfa-2a (40KD) 180 μg/week plus either placebo or ribavirin (RBV) 800 mg/day in the AIDS PEGASYS Ribavirin International Coinfection Trial. There were no significant differences between patients treated with RBV and placebo in plasma pharmacokinetics parameters for the nucleoside reverse transcriptase inhibitors (NRTIs) at steady state (weeks 8 to 12): ratios of least squares mean of area under the plasma concentration-time curve (AUC0-12 h) were 1.17 (95% confidence interval, 0.91 to 1.51) for 3TC, 1.44 (95% confidence interval, 0.58 to 3.60) for d4T and 0.85 (95% confidence interval, 0.50 to 1.45) for ZDV, and ratios of least squares mean plasmaCmaxwere 1.33 (95% confidence interval, 0.99 to 1.78), 1.06 (95% confidence interval, 0.68 to 1.65), and 0.84 (95% confidence interval, 0.46 to 1.53), respectively. Concentrations of NRTI triphosphate (TP) metabolites in relation to those of the triphosphates of endogenous deoxythymidine-triphosphate (dTTP) and deoxcytidine-triphosphate (dCTP) were similar in the RBV and placebo groups. Differences (RBV to placebo) in least squares mean ratios of AUC0-12 hat steady state were 0.274 (95% confidence interval, −0.37 to 0.91) for 3TC-TP:dCTP, 0.009 (95% confidence interval, −0.06 to 0.08) for d4T-TP:dTTP, and −0.081 (95% confidence interval, −0.40 to 0.24) for ZDV-TP:dTTP. RBV did not adversely affect HIV-1 replication. In summary, RBV 800 mg/day administered in combination with peginterferon alfa-2a (40KD) does not significantly affect the intracellular phosphorylation or plasma pharmacokinetics of 3TC, d4T, and ZDV in HIV-HCV-coinfected patients.
Evaluating Ciprofloxacin Dosing for
Pseudomonas aeruginosa
Infection by Using Clinical Outcome-Based Monte Carlo Simulations
Authors: Zelenitsky Sheryl , Ariano Robert , Harding Godfrey , Forrest Alan
Published: September 2005

Pseudomonas aeruginosa
causes serious infections whose outcome is highly dependent on antimicrobial therapy. The goal of this study was to predict the relative efficacies of three ciprofloxacin dosing regimens for
P. aeruginosa
infection using clinical outcome-based Monte Carlo simulations (MCS) with “real patient” demographics, pharmacokinetics, MICs, and pharmacodynamics (PDs). Each cohort consisted of 1,000 simulated study subjects. Three ciprofloxacin dosing regimens were studied, including (i) the recommended standard dose of 400 mg given intravenously (i.v.) every 12 h (q12h), (ii) the recommended high dose of 400 mg i.v. q8h, and (iii) a novel, PD-targeted regimen to attain a ƒAUC/MIC value of >86. Probability of target attainment (PTA) and probability of cure (POC) were determined for each regimen. POC with the standard dose was at least 0.90 if pathogen MICs were ≤0.25 μg/ml but only 0.59 or 0.27 if MICs were 0.5 or 1 μg/ml, respectively. Predicted cure rates in these MIC categories were significantly higher at 0.72 and 0.40 with the high dose and 0.91 and 0.72 with the PD-targeted regimen(
P
< 0.0001). Analyses based on the local susceptibility profile produced PTA and POC estimates of 0.44 and 0.74 with the standard ciprofloxacin dose, 0.58 and 0.81 with the high dose, and 0.84 and 0.93 with the PD-targeted regimen, respectively. In conclusion, as demonstrated by clinical outcome-based MCSs, the highest recommended ciprofloxacin dose of 400 mg i.v. q8h should be used in the treatment of
P. aeruginosa
infection to improve PD target attainment and clinical cure. However, even this appears ineffective if pathogen MICs are 1 μg/ml, warranting the consideration of a lower MIC breakpoint, ≤0.5 μg/ml.
Efficient Intermittent Rifapentine-Moxifloxacin-Containing Short-Course Regimen for Treatment of Tuberculosis in Mice
Authors: Veziris N. , Lounis N. , Chauffour A. , Truffot-Pernot C. , Jarlier V.
Published: September 2005

Long-half-life drugs raise the hope of once-a-week administration of antituberculous treatment. In a previous study with the murine model of tuberculosis, the most active intermittent regimen which contained rifapentine (RFP), isoniazid (INH), and moxifloxacin (MXF) given once a week during 5.5 months, preceded by 2 weeks of daily treatment with INH, rifampin (RIF), pyrazinamide (PZA), and MXF, was less active than the standard 6-month daily RIF-INH-PZA regimen. We evaluated with the same model similar regimens in which we increased the dosing of rifapentine from 10 to 15 mg/kg of body weight and of moxifloxacin from 100 to 400 mg/kg. Mice infected intravenously by 6.2 ×10
6
CFU of
Mycobacterium tuberculosis
H37Rv were treated 2 weeks later when infection was established. After 6 months of treatment, all mice had negative lung culture. After 3 months of follow-up, no relapse occurred in the two groups that received moxifloxacin at 400 mg/kg, whatever the dosage of RFP, and in the group receiving the standard RIF-INH-PZA control regimen. In contrast, in the two groups receiving moxifloxacin at a lower dosage, the relapse rate was significantly higher (13% in mice receiving RFP at 15 mg/kg and 27% in those receiving RFP at 10 mg/kg). Finally, the fully intermittent once-a-week regimen (26 drug ingestions) of INH, RFP (15 mg/kg), and MXF (400 mg/kg) led to a relapse rate of 11%. In conclusion, when used at high dosage, rifapentine and moxifloxacin are very efficient when combined with isoniazid in a once-a-week treatment in mouse tuberculosis.
Open-Label Randomized Trial of Oral Trimethoprim-Sulfamethoxazole, Doxycycline, and Chloramphenicol Compared with Trimethoprim-Sulfamethoxazole and Doxycycline for Maintenance Therapy of Melioidosis
Authors: Chaowagul Wipada , Chierakul Wirongrong , Simpson Andrew J. , Short Jennifer M. , Stepniewska Kasia , Maharjan Bina , Rajchanuvong Adul , Busarawong Duangkaew , Limmathurotsakul Direk , Cheng Allen C. , Wuthiekanun Vanaporn , Newton Paul N. , White Nicholas J. , Day Nicholas P. J. , Peacock Sharon J.
Published: September 2005

Melioidosis (infection caused by
Burkholderia pseudomallei
) requires a prolonged course of oral antibiotics following initial intravenous therapy to reduce the risk of relapse after cessation of treatment. The current recommendation is a four-drug regimen (trimethoprim [TMP], sulfamethoxazole [SMX], doxycycline, and chloramphenicol) and a total treatment time of 12 to 20 weeks. Drug side effects are common; the aim of this study was to compare the efficacy and tolerance of the four-drug regimen with a three-drug regimen (TMP-SMX and doxycycline). An open-label, randomized trial was conducted in northeast Thailand. A total of 180 adult Thai patients were enrolled, of which 91 were allocated to the four-drug regimen and 89 to the three-drug regimen. The trial was terminated early due to poor drug tolerance, particularly of the four-drug regimen. The culture-confirmed relapse rates at 1 year were 6.6% and 5.6% for the four- and three-drug regimens, respectively (
P
= 0.79). The three-drug regimen was better tolerated than the four-drug regimen; 36% of patients receiving four drugs and 19% of patients receiving three drugs required a switch in therapy due to side effects (
P
= 0.01). The duration of oral therapy was significantly associated with relapse; after adjustment for confounders, patients receiving less than 12 weeks of oral therapy had a 5.7-fold increase of relapse or death. A combination of TMP-SMX and doxycycline is as effective as and better tolerated than the conventional four-drug regimen for the oral treatment phase of melioidosis.
Susceptibility Patterns and Molecular Identification of
Trichosporon
Species
Authors: Rodriguez-Tudela Juan L. , Diaz-Guerra Teresa M. , Mellado Emilia , Cano Virginia , Tapia Cecilia , Perkins Alexander , Gomez-Lopez Alicia , Rodero Laura , Cuenca-Estrella Manuel
Published: September 2005

The physiological patterns, the sequence polymorphisms of the internal transcriber spacer (ITS), and intergenic spacer regions (IGS) of the rRNA genes and the antifungal susceptibility profile were evaluated for their ability to identify
Trichosporon
spp. and their specificity for the identification of 49 clinical isolates of
Trichosporon
spp. Morphological and biochemical methodologies were unable to differentiate among the
Trichosporon
species. ITS sequencing was also unable to differentiate several species. However, IGS1 sequencing unambiguously identified all
Trichosporon
isolates. Following the results of DNA-based identification,
Trichosporon asahii
was the species most frequently isolated from deep sites (15 of 25 strains; 60%). In the main, other
Trichosporon
species were recovered from cutaneous samples. The majority of
T. asahii
,
T. faecale
, and
T. coremiiforme
clinical isolates exhibited resistance in vitro to amphotericin B, with geometric mean (GM) MICs >4 μg/ml. The other species of
Trichosporon
did not show high MICs of amphotericin B, and GM MICs were <1 μg/ml. Azole agents were active in vitro against the majority of clinical strains. The most potent compound in vitro was voriconazole, with a GM MIC ≤0.14 μg/ml. The sequencing of IGS correctly identified
Trichosporon
isolates; however, this technique is not available in many clinical laboratories, and strains should be dispatched to reference centers where these complex methods are available. Therefore, it seems to be more practical to perform antifungal susceptibility testing of all isolates belonging to
Trichosporon
spp., since correct identification could take several weeks, delaying the indication of an antifungal agent which exhibits activity against the infectious strain.
Comparative Efficacies of Quinupristin-Dalfopristin, Linezolid, Vancomycin, and Ciprofloxacin in Treatment, Using the Antibiotic-Lock Technique, of Experimental Catheter-Related Infection Due to
Staphylococcus aureus
Authors: Giacometti Andrea , Cirioni Oscar , Ghiselli Roberto , Orlando Fiorenza , Mocchegiani Federico , Silvestri Carmela , Licci Alberto , De Fusco Matteo , Provinciali Mauro , Saba Vittorio , Scalise Giorgio
Published: September 2005

We performed in vitro studies to elucidate the bactericidal activity of the antibiotics in an adherent-cell biofilm model. Efficacy studies were performed in a staphylococcal central venous catheter (CVC) infection rat model. Silastic catheters were implanted into the superior cava. Via the CVC the rats were challenged with 1.0 × 10
6
CFU of a live
Staphylococcus aureus
strain. Twenty-four hours later, the antibiotic-lock technique was started. All animals were randomized to receive daily isotonic sodium chloride solution, quinupristin-dalfopristin (Q/D), linezolid, vancomycin, or ciprofloxacin at the minimal bactericidal concentration (MBC) and at 1,024 μg/ml in a volume of 0.1 ml that filled the CVC. The main outcome measures were MICs and MBCs for both planktonic and adherent cells, quantitative culture of the catheters and surrounding venous tissues, and quantitative peripheral blood cultures. The killing activities of all antibiotics against the adherent bacteria were at least fourfold lower than those against freely growing cells, with the exception of Q/D, which showed comparable activities against both adherent and planktonic organisms. Overall, Q/D at 1,024 μg/ml produced the greatest reduction in the number of cells recovered from the catheters, while at the same concentration, Q/D and vancomycin demonstrated higher activities than ciprofloxacin or linezolid in reducing the number of organisms recovered from the blood cultures. This study points out that treatment outcome of device-related infections cannot be predicted by the results of a standard susceptibility test such as the MIC. Our findings suggest that the clinically used antibiotics cannot eradicate the CVC infection through the antibiotic-lock technique, even at a concentration of 1,024 μg/ml.
Antiviral Activity of GW678248, a Novel Benzophenone Nonnucleoside Reverse Transcriptase Inhibitor
Authors: Ferris Robert G. , Hazen Richard J. , Roberts Grace B. , St. Clair Marty H. , Chan Joseph H. , Romines Karen R. , Freeman George A. , Tidwell Jeffrey H. , Schaller Lee T. , Cowan Jill R. , Short Steven A. , Weaver Kurt L. , Selleseth Dean W. , Moniri Kelly R. , Boone Lawrence R.
Published: September 2005

The compound GW678248 is a novel benzophenone nonnucleoside reverse transcriptase inhibitor (NNRTI). Preclinical assessment of GW678248 indicates that this compound potently inhibits wild-type (WT) and mutant human immunodeficiency virus type 1 (HIV-1) reverse transcriptase in biochemical assays, with 50% inhibitory concentrations (IC
50
s) between 0.8 and 6.8 nM. In HeLa CD4 MAGI cell culture virus replication assays, GW678248 has an IC
50
of ≤21 nM against HIV-1 isogenic strains with single or double mutations known to be associated with NNRTI resistance, including L100I, K101E, K103N, V106A/I/M, V108I, E138K, Y181C, Y188C, Y188L, G190A/E, P225H, and P236L and various combinations. An IC
50
of 86 nM was obtained with a mutant virus having V106I, E138K, and P236L mutations that resulted from serial passage of WT virus in the presence of GW678248. The presence of 45 mg/ml human serum albumin plus 1 mg/ml α-1 acid glycoprotein increased the IC
50
approximately sevenfold. Cytotoxicity studies with GW678248 indicate that the 50% cytotoxicity concentration is greater than the level of compound solubility and provides a selectivity index of >2,500-fold for WT, Y181C, or K103N HIV-1. This compound exhibits excellent preclinical antiviral properties and, as a prodrug designated GW695634, is being developed as a new generation of NNRTI for the treatment of HIV-1 in combination with other antiretroviral agents.