bluuebunny/crossref_metadata_2025 huggingface dataset:
Supercurrent density above 106A∕cm2 at 77K in a single-crystal film conductor of the cuprate high-Tc superconductor YBa2Cu3O7−δ—dream or reality?
Authors: Pan V. M.
Published: October 2006

Supercurrent transport phenomena in c-oriented epitaxial thin films of the the high-Tc superconducting (HTS) cuprate YBa2Cu3O7−δ (YBCO) with a high critical current density Jc(77K)⩾2×106A∕cm2 are investigated by four-probe transport measurements, low-frequency magnetic susceptibility studies, and SQUID magnetometry. The film samples are deposited on a single-crystal sapphire (r-cut) substrates with a CeO2 or LaAlO3(100) buffer layer by off-axis dc magnetron sputtering or pulsed laser ablation. A model of the mechanisms of Abrikosov vortex pinning and supercurrent limitation is developed and discussed by comparing its predictions with the results of measurements of the critical current and its dependence on applied magnetic fields of different strength and orientation and also with nanostructure data obtained by high-resolution transmission electron microscopy and electron diffraction in a backscattering geometry. It is shown that the low-angle subboundaries (LABs) formed between domains with a slight azimuthal misorientation during the epitaxial growth of the film play a key role in the phenomena observed in the transport of supercurrent. The tilt LABs form equidistant ordered rows of edge dislocations with nonsuperconducting cores about 3–4nm in diameter. The dislocation lines in the LABs are parallel to each other and perpendicular to the film plane. The average density of dislocations over the area of the film depends on the real statistics of the random system of LABs and can reach 1011cm−2. Since the diameter of the “normal” core of a dislocation is close to the diameter of the core of an Abrikosov vortex, the elementary pinning force of the vortex to the core of the dislocation is close to the maximum possible. The pinning on dislocation subboundaries has the following characteristics: 1) the achievement of high values Jc(77K)⩾2×106A∕cm2 and Jc(20K)>107A∕cm2 in epitaxial films and conductors; 2) the existence of a “plateau” on the Jc(H) curve, i.e., Jc(H)=const for HHm, i.e., at the transition from the single-particle pinning regime to the collective pinning of the vortex lattice on the statistical ensemble of randomly distributed dislocation subboundaries; 4) the existence of a threshold field Hp that determines the limit up to which the vortices in a thin film (d⩽λ) remain rectilinear and perpendicular to the film even in a field inclined at a large angle; 5) the evolution of the angle dependence of Jc(θ) with a change of field strength is in complete agreement with the model of dominant pinning on “threading” edge dislocations. A new “peak effect”—an increase of Jc(H‖ab) with increasing longitudinal field—is observed for the first time for H>Hm, i.e, after the end of the “plateau” Jc(H‖ab)=const.
Temperature-carrier-concentration phase diagram of a two-dimensional doped d-wave superconductor
Authors: Loktev V. M. , Turkowski V. M.
Published: October 2006

The finite-temperature properties of a two-dimensional d-wave superconductor with the Lifshitz disorder, introduced by dopants, are studied. The doping dependence of the mean-field critical temperature TcMF and of the superconducting critical temperature Tc defined by the Berezinskii-Kosterlitz-Thouless transition are calculated at different values of coupling, dopant potential, and intermediate boson energy. It is shown that superconductivity tends to disappear with increasing doping when the dopant potential is large enough, though the metallic properties of the system are preserved.
Pseudogap effects in strongly correlated electron systems
Authors: Boyarsky L. A.
Published: October 2006

An analytical survey of pseudogap effects in the electron spectra of strongly correlated systems is presented. The relationship of these effects with the Friedel virtual levels model is discussed.
Velocity fluctuation analysis via dynamic programming
Authors: Schlossberg D. J. , Gupta D. K. , Fonck R. J. , McKee G. R. , Shafer M. W.
Published: October 2006

A new method of calculating one-dimensional velocity fluctuations from spatially resolved density fluctuation measurements is presented. The algorithm uses vector-matching methods of dynamic programming that match structures, such as turbulent fluctuations, in two data sets. The associated time delay between data sets is estimated by determining an optimal path to transform one vector to another. This time-delay-estimation (TDE) method establishes a new benchmark for velocity analysis by achieving higher sensitivity and frequency response than previously developed methods, such as time-resolved cross correlations and wavelets. TDE has been successfully applied to beam emission spectroscopy measurements of density fluctuations to obtain poloidal flow fluctuations associated with such phenomena as the geodesic acoustic mode. The dynamic programming algorithm should allow extension to high frequency velocity fluctuations associated with underlying electrostatic potential and resulting E×B fluctuations.
How many metal atoms are needed to dehydrogenate an ethylene molecule on metal clusters?: Correlation between reactivity and electronic structures of Fen+, Con+, and Nin+
Authors: Ichihashi Masahiko , Hanmura Tetsu , Kondow Tamotsu
Published: October 2006

The absolute cross section for dehydrogenation of an ethylene molecule on Mn+ [Fen+ (n=2–28), Con+ (n=8–29), and Nin+ (n=3–30)] was measured as a function of the cluster size n in a gas-beam geometry at a collision energy of 0.4eV in the center-of-mass frame in an apparatus equipped with a tandem-type mass spectrometer. It is found that (1) the dehydrogenation cross section increases rapidly above a cluster size of ≈18 on Fen+, ≈13 and ≈18 on Con+, and ≈10 on Nin+ and (2) the rapid increase of the cross section for Mn+ occurs at a cluster size where the 3d electrons start to contribute to the highest occupied levels of Mn+. These findings lead us to conclude that the 3d electrons of Mn+ play a central role in the dehydrogenation on Mn+.
Atomic modeling and instrumentation for measurement and analysis of emission in preparation for the ITER-like wall in JET
Authors: O’Mullane M. G. , Summers H. P. , Whiteford A. D. , Meigs A. G. , Lawson K. D. , Zastrow K.-D. , Barnsley R. , Coffey I. H. ,   JET-EFDA Contributors
Published: October 2006

In the near future the interior materials of JET will be changed to a beryllium wall and tungsten divertor so as to resemble the ITER design. Initially there will be no carbon strike plates in the divertor but there is the possibility of adding these later for an exact match. Such a change requires upgraded spectroscopic diagnostics in order to measure the spatially dependent influx of these impurities and their concentrations in the confined plasma. With 74 ionization stages (many of them very complex) the high Z of tungsten also places new demands on the atomic physics required to model its behavior which in turn informs the design of potential diagnostic systems. Modeled emission patterns from the upgraded JET are used as part of the diagnostic specification. We describe a suite of spectroscopic diagnostics in the visible, extreme ultraviolet, vacuum ultraviolet, and x-ray spectral regions suitable for these tasks.
The collimation angle shift of desorbing product N2 in a steady-state N2O+CO reaction on Rh(110)
Authors: Matsushima Tatsuo , Nakagoe Osamu , Shobatake Kosuke , Kokalj Anton
Published: October 2006

The angular distribution of desorbing product N2 was studied in N2O decompositions on Rh(110) in the temperature range of 60–700K. The N2 desorption collimates along 62°–68° off normal toward either the [001] or [001¯] direction in a transient N2O decomposition below ca. 470K or in the steady-state N2O+CO reaction above 540K. In the steady-state reaction at the temperature from ca. 470to540K, however, the collimation angle shifts from 62° to 45° with decreasing surface temperature. This angle shift is ascribed to the steric hindrance by coadsorbed CO because the N2 collimation in transient N2O decomposition at around 65° is recovered in the range of 380–500K by an abrupt CO pressure drop followed by the decrease in CO coverage. N2O is oriented along the [001] direction before dissociation. A scattering model of the nascent N2 by adsorbed CO is proposed, yielding smaller collimation angles.
State-to-state reaction dynamics: A selective review
Authors: Teslja Alexey , Valentini James J.
Published: October 2006

A selective review of state-to-state reaction dynamics experiments is presented. The review focuses on three classes of reactions that exemplify the rich history and illustrate the current state of the art in such work. These three reactions are (1) the hydrogen exchange reaction, H+H2→H2+H and its isotopomers; (2) the H+RH→H2+R reactions, where RH is an alkane, beginning with H+CH4→H2+CH3 and extending to much larger alkanes; and (3) the Cl+RH→HCl+R reactions, principally Cl+CH4→HCl+CH3. We describe the experiments, discuss their results, present comparisons with theory, and introduce heuristic models.
Theory of the residual resistivity of dilute alloys of nonmagnetic 3d–5d transition metals
Authors: Tsiovkin Yu. Yu. , Voloshinskii A. N. , Gapontsev V. V. , Ustinov V. V.
Published: October 2006

The residual resistivity of dilute alloys of nonmagnetic transition metals is calculated by the kinetic equation method with allowance for the two-band character of the conduction at low impurity concentrations. It is shown that for all dilute nonmagnetic binary alloys of the substitution type the value of the residual resistivity is a linear function of the square modulus of the off-diagonal s-d matrix element of the scattering T-matrix.
Alignment Effect: Primary – Secondary Learning and Cognitive Styles
Authors: Nori Raffaella , Grandicelli Sonia , Giusberti Fiorella
Published: October 2006

The degree to which the way of learning spatial information (primary/secondary learning) and spatial cognitive style (landmark/route/survey) affect orientation specificity (alignment effect) is studied. We think that the most important factor explaining the absence of the alignment effect is the spatial cognitive style. We hypothesise that while landmark participants show an alignment effect after both primary and secondary learning, route participants show this effect only after secondary learning, and survey participants do not show it at all. Participants performed three tasks in order to distinguish their cognitive style; they were then randomly assigned to primary or secondary learning and submitted to directional judgment tasks to verify whether the alignment effect was present. The results confirm our hypothesis.
Lightness of an Object under Two Illumination Levels
Authors: Zdravković Sunčica , Economou Elias , Gilchrist Alan
Published: October 2006

Anchoring theory (Gilchrist et al, 1999 Psychological Review106 795 – 834) predicts a wide range of lightness errors, including failures of constancy in multi-illumination scenes and a long list of well-known lightness illusions seen under homogeneous illumination. Lightness values are computed both locally and globally and then averaged together. Local values are computed within a given region of homogeneous illumination. Thus, for an object that extends through two different illumination levels, anchoring theory produces two values, one for the patch in brighter illumination and one for the patch in dimmer illumination. Observers can give matches for these patches separately, but they can also give a single match for the whole object. Anchoring theory in its current form is unable to predict these object matches. We report eight experiments in which we studied the relationship between patch matches and object matches. The results show that the object match represents a compromise between the match for the patch in the field of highest illumination and the patch in the largest field of illumination. These two principles are parallel to the rules found for anchoring lightness: highest luminance rule and area rule.
Errors in Judging Information about Reflections in Mirrors
Authors: Lawson Rebecca , Bertamini Marco
Published: October 2006

We investigated people's perception and knowledge of planar mirror reflections. People were accurate at deciding when they could first see their reflection as they approached a mirror from the side, but only if their reflection was visible. Most people stopped too early if the mirror was covered up. People also overestimated the size of the reflection of their face on the surface of a mirror if they were shown a covered mirror. Their accuracy improved somewhat if their reflection was visible but, unlike the first task, they still made striking errors. Perceptual feedback thus improved performance at predicting the behaviour of mirror reflections in both tasks but failed to eliminate errors in the second task. The overestimation of reflection size was not face-specific as it generalised to novel stimuli (paper ellipses) and it was found with both a matching response and for verbal size estimations. The early error in the first task appears to be due to an inaccurate belief that can be overridden by perceptual feedback. The overestimation in the second task is primarily caused by a powerful size-constancy effect.
Galvanostatic deposition of thin films of cadmium and tellurium
Authors: Danaher WJ , Lyons LE
Published: October 2006

Thin films containing
cadmium and tellurium, not necessarily present as the compound cadmium
telluride, were electrodeposited galvanostatically
onto a titanium rotating disc electrode from an aqueous solution containing
CdS04, TeO2 and H2SO4. The films
were analysed by atomic absorption spectroscopy and the dependence of the film
composition on the deposition current density determined. The cadmium and the
tellurium deposited independently of each other, and the deposition system can
be classified as a regular alloy plating system. Films of widely varying
composition were deposited.
Reactions of aryl diazonium salts and alkyl arylazo ethers. XI. Further evidence for the mechanism of dediazoniation in basic alcoholic solution
Authors: Broxton TJ , Mcleish MJ
Published: October 2006

A comparison of the
relative amounts of dediazoniation, SNAr and aryne
reactions of 4-chloro-3- nitrobenzenediazonium ion
with methoxide ion in CH3OH and in CD3OH
confirms that the dediazoniation reaction involves
hydride abstraction from the alkoxide ion by the
electrophilic terminal nitrogen atom of the diazonium
ion. Furthermore, the relative amounts of anionic and free-radical dediazoniation are the same in CH3OH and in CD3OH.
This confirms that the partitioning between the free-radical and anionic pathways
for dediazoniation is on the aryl diimide
and not on the free diazonium ion. Some previously
reported results on the solvent effect (methanol against ethanol) for the
reaction have been reinterpreted in the light of the above conclusions.
The absolute configuration of Λ-[Co(sen)] [(R,R)(+)tart] C1.6H2O and of Δ-[Co(sen)] [(R,R)(+)tart] C1.4. 5H2O (sen is 5-Methyl-5-(4-amino-2-azabutyl)-3,7-diazanonane-1,9-diamine): A comment on the mode of chiral resolutions by (R,R)(+)Tartrate on the antipodal cations of cobalt(III) salts
Authors: Bernal I , Korp JD , Creaser II
Published: October 2006

The X-ray crystal
structures of the Λ and ∆ diastereoisomeric pair of [Co(sen)] [(R,R)(+)tart] ClnH2O
(sen is
5-methyl-5-(4-amino-2-azabutyl)-3,7-diazanonane-1,9-diamine, tart is tartrate) have been determined. Crystals of the less
soluble Λ isomer, (Λ-(1); n
= 6), are othorhombic, space group P212121,
with a 10.817(8), b 13.626(8), c 17.724(6)
�, while those of the non-preferred Λ isomer, (Λ-(1); n = 4.5), are
monoclinic, space group P21, with a 9,469(8), b 12.116(9), c 12.132(7) �, β 95.94(6)�. Both
structures were solved by the Patterson method, and refined to R 3.8% (Λ-(1))
and 10.8% (Λ-(1)). In ∆-(1) the waters of hydration are partly
disordered in the unit cell. Both crystal structures exhibit extensive hydrogen
bonding; however, the mode of contact between the cation and the tartrate dianion in the two
compounds is slightly different. In Λ-(1) the three amino hydrogens
involved each have only one close contact to a tartrate
oxygen, whereas in ∆-(1) each hydrogen has two close contacts. The mode
of chiral resolution thus seems to depend on the strength of the hydrogen
bonding found in this 'local block', and not simply on its ability to form such
a block, since both enantiomers do so.
The influence of snow cover on home range and activity of the bush-rat (Rattus fuscipes) and the dusky antechinus (Antechinus swainsonii)
Authors: Sanecki Glenn M. , Green Ken , Wood Helen , Lindenmayer David , Sanecki Karen L.
Published: October 2006

Radio-telemetry was used to investigate changes in home-range sizes and activity patterns of Rattus fuscipes and Antechinus swainsonii in a subalpine heathland at Perisher Creek, Kosciuszko National Park, southern New South Wales, in response to the accumulation of snow during the winter. We estimated home-range area for each animal during the autumn and winter using two methods, minimum convex polygon and 95% and 50% utilisation contours using the kernel method. With both methods, the home ranges of R. fuscipes and A. swainsonii were significantly smaller (P < 0.001) during the winter than in the autumn. In winter, both species were restricted to areas of dense wet heath close to the main drainage line. R. fuscipes showed signs of social interaction during both seasons, as indicated by location fixes and gnawing damage to radio-collars, in contrast to A. swainsonii, which appeared to remain solitary. In winter, R. fuscipes apparently nested at a single location, whereas during autumn it appeared to use several nest sites. There was no significant change in daily activity patterns between autumn and winter in either species. R. fuscipes remained primarily nocturnal during both prenival and nival periods whereas A. swainsonii continued to be active throughout the diel cycle, although there was a slight shift in its peak activity time from around sunset in autumn to early morning in winter.
Colony growth and pup condition of the New Zealand fur seal (Arctocephalus forsteri) on the Kaikoura coastline compared with other east coast colonies
Authors: Boren L. J. , Muller C. G. , Gemmell N. J.
Published: October 2006

Abstract.Since its near extermination by sealing, the New Zealand fur seal (Arctocephalus forsteri) has been recolonising areas of its former range throughout New Zealand and Australia. This study examined fur seal population growth over four breeding seasons spanning 2002–05 at the Ohau Point and Lynch’s Reef colonies in Kaikoura and the Horseshoe Bay and Te Oka Bay colonies on Banks Peninsula, on the east coast of New Zealand. Estimates of pup numbers were made using mark–recapture techniques and condition indices were used to assess the body condition of pups in each colony. We found that the Ohau Point and Te Oka Bay colonies are growing exponentially (32% and 47% per annum respectively), reaching nearly 600 pups at Ohau Point and 300 pups at Te Oka Bay, whereas Horseshoe Bay appears stable. Pups born at Ohau Point are consistently heavier and in better condition than their Banks Peninsula counterparts despite the faster rate of growth observed at Te Oka Bay. An El Niño event in 2003 coincided with a drop in mass and condition at the Banks Peninsula colonies, but not at the Kaikoura colony. This discrepancy between colonies in response to environmental conditions suggests that colony-specific variables at Kaikoura may provide more favourable conditions for rearing pups than on Banks Peninsula.
Rapid assessment for a new invasive species threat: the case of the Gambian giant pouched rat in Florida
Authors: Engeman Richard , Woolard John W. , Perry Neil D. , Witmer Gary , Hardin Scott , Brashears Lawrence , Smith Henry , Muiznieks Britta , Constantin Bernice
Published: October 2006

The Gambian giant pouched rat (Cricetomys gambianus) is a large rodent that has established a breeding population in the Florida Keys. Should it successfully disperse to mainland Florida, it could continue spreading through much of North America where significant negative ecological and agricultural consequences could result. We rapidly developed the information for implementing an efficient and successful eradication program before dispersal to the mainland occurs. This included development of monitoring and indexing methods and their application to define the animal’s range, the development of baits attractive to Gambian giant pouched rats, efficacy testing of toxicants, and development of bait-delivery devices that exclude native animals. Gambian giant pouched rats appeared confined to the western two-thirds of Grassy Key, but have dispersed across a soil-filled causeway west to Crawl Key. We identified preferred habitat characteristics and potential dispersal pathways. We developed photographic and tracking tile methods for detecting and indexing Gambian giant pouched rats, both of which work well in the face of high densities of non-target species. We identified a commercial anticoagulant bait and we developed a zinc phosphide (an acute toxicant) bait matrix that were well accepted and effective for controlling Gambian giant pouched rats. We also developed a bait station for delivering toxic bait to Gambian giant pouched rats without risk to native species. We consider that the criteria are met for a successful eradication to commence.
A molecular neuroethological approach for identifying and characterizing a cascade of behaviorally regulated genes
Authors: Wada Kazuhiro , Howard Jason T. , McConnell Patrick , Whitney Osceola , Lints Thierry , Rivas Miriam V. , Horita Haruhito , Patterson Michael A. , White Stephanie A. , Scharff Constance , Haesler Sebastian , Zhao Shengli , Sakaguchi Hironobu , Hagiwara Masatoshi , Shiraki Toshiyuki , Hirozane-Kishikawa Tomoko , Skene Pate , Hayashizaki Yoshihide , Carninci Piero , Jarvis Erich D.
Published: October 2006

Songbirds have one of the most accessible neural systems for the study of brain mechanisms of behavior. However, neuroethological studies in songbirds have been limited by the lack of high-throughput molecular resources and gene-manipulation tools. To overcome these limitations, we constructed 21 regular, normalized, and subtracted full-length cDNA libraries from brains of zebra finches in 57 developmental and behavioral conditions in an attempt to clone as much of the brain transcriptome as possible. From these libraries, ≈14,000 transcripts were isolated, representing an estimated 4,738 genes. With the cDNAs, we created a hierarchically organized transcriptome database and a large-scale songbird brain cDNA microarray. We used the arrays to reveal a set of 33 genes that are regulated in forebrain vocal nuclei by singing behavior. These genes clustered into four anatomical and six temporal expression patterns. Their functions spanned a large range of cellular and molecular categories, from signal transduction, trafficking, and structural, to synaptically released molecules. With the full-length cDNAs and a lentiviral vector system, we were able to overexpress, in vocal nuclei, proteins of representative singing-regulated genes in the absence of singing. This publicly accessible resource
http://songbirdtranscriptome.net
can now be used to study molecular neuroethological mechanisms of behavior.
ProtBuD: a database of biological unit structures of protein families and superfamilies
Authors: Xu Qifang , Canutescu Adrian , Obradovic Zoran , Dunbrack Roland L.
Published: October 2006

Motivation: Modeling of protein interactions is often possible from known structures of related complexes. It is often time-consuming to find the most appropriate template. Hypothesized biological units (BUs) often differ from the asymmetric units and it is usually preferable to model from the BUs.

Results: ProtBuD is a database of BUs for all structures in the Protein Data Bank (PDB). We use both the PDBs BUs and those from the Protein Quaternary Server. ProtBuD is searchable by PDB entry, the Structural Classification of Proteins (SCOP) designation or pairs of SCOP designations. The database provides the asymmetric and BU contents of related proteins in the PDB as identified in SCOP and Position-Specific Iterated BLAST (PSI–BLAST). The asymmetric unit is different from PDB and/or Protein Quaternary Server (PQS) BUs for 52% of X-ray structures, and the PDB and PQS BUs disagree on 18% of entries.

Availability: The database is provided as a standalone program and a web server from .

Contact:  Roland.Dunbrack@fccc.edu
A Novel algorithm for identifying low-complexity regions in a protein sequence
Authors: Li Xuehui , Kahveci Tamer
Published: October 2006

Motivation: We consider the problem of identifying low-complexity regions (LCRs) in a protein sequence. LCRs are regions of biased composition, normally consisting of different kinds of repeats.

Results: We define new complexity measures to compute the complexity of a sequence based on a given scoring matrix, such as BLOSUM 62. Our complexity measures also consider the order of amino acids in the sequence and the sequence length. We develop a novel graph-based algorithm called GBA to identify LCRs in a protein sequence. In the graph constructed for the sequence, each vertex corresponds to a pair of similar amino acids. Each edge connects two pairs of amino acids that can be grouped together to form a longer repeat. GBA finds short subsequences as LCR candidates by traversing this graph. It then extends them to find longer subsequences that may contain full repeats with low complexities. Extended subsequences are then post-processed to refine repeats to LCRs. Our experiments on real data show that GBA has significantly higher recall compared to existing algorithms, including 0j.py, CARD, and SEG.

Availability: The program is available on request.

Contact:  xli@cise.ufl.edu, tamer@cise.ufl.edu
Fracture Criterion for Alumina Ceramics Subjected to Triaxial Stresses
Authors: IKEDA KIYOHIKO , IGAKI HISASHI
Published: October 2006

Triaxial stress tests of alumina ceramics were conducted by pure bending under hydrostatic pressure, and by internal pressurization of an open‐end thin‐walled tube under hydrostatic pressure. The fracture stresses plotted in the principal stress space did not conform to existing fracture criteria. So, for fracture of the material, the flaw model consisting of randomly oriented penny‐shaped cracks was assumed. The fracture criterion obtained from a statistical viewpoint by taking account of flaw distributions could explain well the experimental results.
Properties of Metallic Glasses in the System Pd‐Ni‐P and in Related Systems
Authors: Dietrichs Joachim , Frischat Gunther H.
Published: October 2006

Glasses in the metallic alloy system Pd10‐7,Ni10‐70P14‐26 were prepared by a melt‐spinning technique. Glasses could also be obtained by substituting Pt for Pd, Mn, Fe, or Co for Ni, and B for P. Densities, molar volumes, melting temperatures, glass transition temperatures, and reduced temperatures were determined. The results are discussed from a structural point of view.
Field‐Assisted Ion Exchange in Type III Silica
Authors: el Leil Mahmoud Abou , Snitzer Elias
Published: October 2006

Field‐assisted ion exchange of protons in type III silica for Cs or Nu ions from a molten salt was investigated. Although electrolysis occurred, infrared measurements showed no change in hydroxyl content after ion exchange for extended periods. Scanning electron microprobe studies of cesium‐exchanged specimens revealed a high‐cesium‐content layer =2,μm thick; this layer is believed to result from surface reaction with the molten salt.
High‐Temperature Failure of Polycrystalline Alumina: I, Crack Nucleation
Authors: DALGLEISH B. J. , JOHNSON S. M. , EVANS A. G.
Published: October 2006

A combination of techniques has been used to compare the compositional and microstructural characteristics of two commercially hot‐pressed aluminas. Second‐phase material containing Ni was observed in one material, mainly as small intergranular particles. Thermal treatment in air caused Ni to concentrate at the surfaces, in small precipitates. Large‐grained heterogeneities, with Ti at the core, were identified in the same material. Hot‐pressing flaws were observed in the second material. The large‐scale heterogeneities act as crack nucleation sites during creep. Stress concentrations associated with these heterogeneities are considered to contribute to the premature crack nucleation, in conjunction with the presence of localized regions of amorphous second phase.
High‐Temperature Failure of Polycrystalline Alumina: II, Creep Crack Growth and Blunting
Authors: BLUMENTHAL W. , EVANS A. G.
Published: October 2006

Creep crack growth in fine‐grain alumina is measured by using surface cracks. A narrow power‐law crack growth regime occurs at both 1300° and 1400°C, wherein the power‐law exponent and activation energy are comparable to steady‐state creep values. Asymptotic crack velocity behavior is exhibited near both the critical stress intensity factor, KC, and the crack growth threshold, Kth. The threshold occurs near 0.4 K1C at both 1300° and 1400°C and is associated with a transition in the size and distribution of damage. Displacement measurements indicate that crack tip damage exerts a strong influence on the displacement field, as predicted by recent theories. Furthermore, use of the stress intensity factor as a loading parameter does not produce adequate correlation with displacement measurements and is, therefore, not strictly suitable for nonlinear creeping ceramic poly crystals.
Gibbs Free Energies of Formations of the Magnesium and Calcium Germanates at High Temperatures
Authors: PYUN SU‐IL
Published: October 2006

The relative chemical potentials and partial molar solution enthalpies of the quasi‐binary systems MgO‐GeO2 and CaO‐GeO2, were determined by means of solid‐state galvanic cells and high‐temperature solution calorimetry, respectively. The standard free energies of formation of the corresponding germanates, MgGeO3, CaGeO3, CaGe4O9, are presented as a function of temperature.
Thermochemistry of Charge‐Coupled Substitutions in Silicate Glasses: The Systems Ml/nn+ AlO2‐SiO2 (M = Li, Na, K, Rb, Cs, Mg, Ca, Sr, Ba, Pb)
Authors: ROY BIMALENDU N. , NAVROTSKY ALEXANDRA
Published: October 2006

Enthalpies of solution of framework aluminosilicate glasses xMl/nn+ AlO2‐(1‐x)SiO2 (M = Cs, Rb, K, Na, Li, Ba, Pb, Sr, Ca, Mg) in molten 2PbO.B2O3 near 973 K were measured. The sequence above represents increasing ability of the nonframework cation M to bond to the bridging oxygen. In that sequence, the enthalpy of the substitution Si4+→+ Al3++ 1/nMn+ in the glass becomes less exothermic, the enthalpy of vitrification increases, and the tendency toward glass‐glass immiscibility becomes more pronounced. These parameters correlate smoothly with the ionic potential, z/r, of the substituting cation.
Microcrack Nucleation in Ceramics Subject to a Phase Transformation
Authors: FU Y. , EVANS A. G. , KRIVEN W. M.
Published: October 2006

The nucleation of microcracks from twins formed in mono‐clinic ZrO2 was analyzed. The twin formation was shown to result in large tensile stress concentrations capable of spontaneous microcrack nucleation. The role of interface dislocations in microcrack nucleation was also considered.
Measurement of Small Concentrations of Cr and Mn in MgO Using Electron Spin Resonance
Authors: DE BIASI R. S. , FERNANDES A. A. R.
Published: October 2006

Electron spin resonance line widths of Cr3+ and Mn2+ were measured in MgO samples doped with <1 mol% of Cr and Mn. The line width was found to change in a predictable way with Cr and Mn concentration. The experimental results show that this technique can be used to measure, rapidly and nondestructively, small concentrations of Cr and Mn in commercial MgO. Nomograms are provided to facilitate interpretation of the results.
Tribological Properties of Glass‐Ceramics
Authors: CRANMER DAVID C.
Published: October 2006

Tribological properties of five glass‐ceramics are reported. The materials were tested unlubricated against themselves. Testing was performed using a simulated inertial sample dynamometer. Sliding speeds were between 0.5 and 1.8 m /S with an applied load of 225 N. Average friction coefficients were in the range 0.07 to 0.5. The wear rate of a lithium aluminosilicate was 43 ×10–14 m3/N.m, in good agreemen2 with previous pin‐on‐disk results. Wear surfaces exhibited cracking, ploughing, delamination, and viscous flow or plastic deformation.
Fiberizable Si(OC2H5)4‐H20‐C2H5OH Sols with Stabilized Viscosity
Authors: LACOURSE William C. , DAHAR STEVEN , AKHTAR MD. AUMASYOOD
Published: October 2006

Sols in which the viscosity changes by only 4%/h in the range 1.5 to 150 Pa.s were produced, and fibers with diameters between 20 and 500 pm were hand‐drawn from them. Sols remain fiberizable for <140 h at room temperature. Periodic additions of alcohol increase the time available for fiberizing to ≥ 300 h.
Effect of Cracks on Water Sorption of Glass
Authors: HOWES VICTOR R. , SZAMEITAT ARMIN
Published: October 2006

Water sorption on glass surfaces was measured by recording the weight gain of specimens exposed to a controlled‐humidity environment. The difference between water sorption on glass surfaces with and without cracks introduced by controlled loading of a disk cutter is described. The increased sorption is explained in terms of condensation within the cracks.
Photoelastic Effects in Silicate Glasses
Authors: MATUSITA KAZUMASA , IHARA CHIKASHI , KOMATSU TAKAYUKI , YOKOTA RYOSUKE
Published: October 2006

The photoelasticity of RnOmSiO2(RnOm=Li2O, Na2O, K2O, and ZnO), Li2O‐Al2O3‐SiO2, Na2O‐Al2O3‐SiO2, and Na2O‐ZnO‐SiO2 glasses was analyzed on the basis of the following equation relating the stress‐optical coefficient and the strain‐optical coefficient:

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where C is the stress‐optical coefficient, n is the refractive index, G is the shear modulus, pI2and pI1are the Pockels strain‐optical coefticients, and p and q are the Neumann strain‐optical coefficients. No simple relation was found between the stress‐optical coefficient and the shear modulus, and the factor (p−q) was found to be an essential factor deter‐ mining the stress‐optical coefficient of silicate glasses. It was found that (p−q) decreases markedly with increasing content of modifier oxide, and that the change of (p − q) with composition is governed by the change of the atomic effect, while the lattice effect does not change as much. It is argued that the bridging oxygen with covalent bonds increases the atomic effect and the nonbridging oxygen with ionic bonds reduces the atomic effect.
Impacts of introduced brown and rainbow trout on benthic invertebrate communities in shallow New Zealand lakes
Authors: WISSINGER SCOTT A. , MCINTOSH ANGUS R. , GREIG HAMISH S.
Published: October 2006

1. Brown and rainbow trout have been introduced to many inland waters in New Zealand, but research on the impacts on native communities has focused mainly on streams. The purpose of this study was to compare the benthic communities of trout and troutless lakes. Based on previous studies in North America and Europe, we predicted that the benthic biomass, and especially the abundance of large invertebrates, would be lower in lakes with trout as compared to those without. We surveyed the invertebrate fauna of 43 shallow, high‐elevation lakes (26 with and 17 without trout) in four geographic clusters on the central South Island and then conducted a detailed quantitative study of invertebrate biomass and community structure in 12 of these lakes.

2. Benthic community composition and diversity of lakes with and without trout were nearly identical and biomass was as high or higher in the lakes with as without trout. There was no evidence that trout have caused local extinctions of benthic invertebrates. Although the proportional abundance of large‐bodied aquatic was slightly lower in lakes with than without trout, the abundance of several groups of large‐bodied benthic taxa (dragonflies, caddisflies and water bugs) did not differ.

3. Our findings are in contrast to those in North American and Europe where trout introductions into previously troutless lakes have led to declines in the abundance of benthic invertebrates, especially large‐bodied taxa. We propose that the modest effects of trout in New Zealand could be explained by (i) the high areal extent of submergent vegetation that acts as a benthic refuge, (ii) low intensity of trout predation on benthic communities and/or (iii) characteristics of the benthic invertebrates that make them relatively invulnerable to fish predation.

4. Regardless of the relative importance of these hypotheses, our results emphasise that the same invertebrates occurred in all of the lakes, regardless of size, elevation and presence of trout, suggesting habitat generalists dominate the benthic fauna in shallow New Zealand lakes.
Eukaryotic diversity associated with carbonates and fluid–seawater interface in Lost City hydrothermal field
Authors: López‐García Purificación , Vereshchaka Alexander , Moreira David
Published: October 2006

Lost City is a unique off‐axis hydrothermal vent field characterized by highly alkaline and relatively low‐temperature fluids that harbours huge carbonate chimneys. We have carried out a molecular survey based on 18S rDNA sequences of the eukaryotic communities associated with fluid–seawater interfaces and with carbonates from venting areas and the chimney wall. Our study reveals a variety of lineages belonging to eight major taxa: Metazoa, Fungi, Heterokonta (Stramenopiles), Alveolata, Radiolaria, Cercozoa, Heterolobosea and Euglenozoa. We detected one fungal lineage that appears to be widespread in hydrothermal systems both submarine and continental. Alveolates were the most abundant and diverse group in Lost City samples, although their distribution was very different in carbonate, where ciliates dominated, and in fluid–seawater libraries, where dinoflagellates, Group I and Group II (Syndiniales) marine alveolates were profuse. Similarly, Euglenozoa also displayed a differential distribution, kinetoplastids being present on carbonates and a novel group of diplonemids so far exclusively observed in the deep sea being dominant in fluid–seawater libraries. Protist lineages identified in this ecosystem likely correspond to grazers, decomposers and parasites, playing key roles in the food web of the Lost City ecosystem.
The unauthorized city: Late colonial Lusaka and postcolonial geography
Authors: Myers Garth A.
Published: October 2006

This paper uses a case study of Lusaka, Zambia, to interrogate several aspects of the literature on postcolonial geography. I deploy two concepts from African postcolonial studies – the idea of exclusionary democracy and the concept of the domestication of difference – and assess the continuity in their applicability to Lusaka. More specifically, I examine the contention that both the political and the planning dynamics of the last years of colonialism are foundational to state–society relationships in contemporary Lusaka. Distinguishing two spheres for in‐depth discussion – urban government and housing policy – I concentrate on the final years of colonialism, moving through to the contemporary setting, to examine if the roots still show for the processes creating exclusionary democracy and domesticating difference. I also examine the ambivalent and incomplete character of those processes. I close with an assessment of the broader meaning inherent in understanding Lusaka in postcolonial terms.
Redefining the ‘Rural Question’: The New ‘Politics of the Rural’ and Social Policy
Authors: Woods Michael
Published: October 2006

Politics in the countryside has undergone a significant shift in emphasis in recent decades, which may be characterized as a transition from ‘rural politics’ to ‘a politics of the rural’. Whereas ‘rural politics’ refers broadly to politics located in rural space, or relating to ‘rural issues’, the ‘politics of the rural’ is defined by the centrality of the meaning and regulation of rurality itself as the primary focus of conflict and debate. However, far from marginalizing social issues – as early work on the new rural conflicts by Mormont implied – the paper argues that the new politics of the rural has liberated rural social policy from the shadow of agricultural policy, providing a new language and context through which rural social issues can be placed on the political agenda. Three examples of this are discussed, drawing on illustrations from Britain, Australia, New Zealand and North America – conflicts over the rationalization of public and commercial services in rural communities; campaigns around the closure of rural schools and their symbolic place at the heart of rural communities; and issues of difference and discrimination in the countryside, including responses to travellers and asylum‐seekers.
Older People ‘on the Edge’ in the Countrysides of Europe
Authors: Giarchi George Giacinto
Published: October 2006

Relatively few comparative studies have focused specifically upon the socio‐economic conditions affecting the welfare of older rural Europeans. Such publications as exist are usually confined to single studies. In presenting a European overview of their ‘life‐world’ this paper focuses upon the general conditions of older rural Europeans, living in different types of countryside within a centre–periphery framework. These conditions are largely dependent upon the interconnectivity (nexus) between regional urban centres and the older people's types of settlement. The extent of the global socio‐economic flows between urban centres and countrysides is critical, especially for those living in less accessible and remote European areas. Older people's positive and negative outcomes are seen to occur within four possible urban–rural parameters. The first consists of two‐way socio‐economic urban–rural flows that are more likely to be of benefit to significant numbers of older persons, especially in urban fringe and accessible countrysides. The second parameter arises when there is a long‐standing impasse, where the lack of communication between the rural locality and urban centre hampers socio‐economic urban–rural flows, isolating older people, particularly in less accessible and remote countrysides. The third occurs when regional and local urban centres block or cut back socio‐economic flows to the countryside. The fourth takes place when the rural communities resist socio‐economic urban flows that they regard as a threat to their rural idyll. Exemplars within each of the four urban–rural alternatives help to show the applicability and workability of this four‐way exploratory approach.
Treatment of Infantile Spasms: Results of a Population‐Based Study with Vigabatrin as the First Drug for Spasms
Authors: Granström Marja‐Liisa , Gaily Eija , Liukkonen Elina
Published: October 2006

Summary: Purpose: The efficacy of a protocol consisting of vigabatrin (VGB) as the first and adrenocorticotropic hormone (ACTH) or valproate (VPA) as the second drug was studied in the treatment of newly diagnosed infantile spasms (IS) during 1994 to 1997 in a population‐based design.

Methods: Only total disappearance of the spasms with a minimal duration of 1 month was accepted as a response. The treatment response was confirmed by video‐EEG study. All infants were studied by magnetic resonance imaging (MRI) or computed tomography (CT) for etiology.

Results: Altogether 42 infants, 10 with cryptogenic and 32 with symptomatic etiology, were treated. Eleven (26%) responded to VGB, five (50%) with cryptogenic, and six (19%) with symptomatic etiology; 91% of infants responded to a dose of 50–100 mg/kg/day, and 82% of them within 1 week. ACTH was offered in combination with VGB to 22 and VPA to four infants for whom VGB failed. Eleven responded to ACTH and one to VPA. In total, 26 (62%) infants responded to the treatment protocol; all (100%) with cryptogenic etiology and 16 (50%) with symptomatic etiology. ACTH treatment was associated with more severe side effects than VGB or VPA. Only one infant relapsed after a spasm‐free period with VGB of >4 months, but none after ACTH was combined with VGB.

Conclusions: We suggest VGB as a first drug to all infants with IS. After a treatment trial of 10–14 days with increasing dose from 50 to 150 mg/kg, ACTH should be considered.
Prothrombin and PIVKA‐II Levels in Cord Blood from Newborn Exposed to Anticonvulsants During Pregnancy
Authors: Howe A. M. , Oakes D. J. , Woodman P. D. C. , Webster W. S.
Published: October 2006

Summary: Purpose: To determine whether anticonvulsant exposure during human pregnancy caused an increase of the abnormal form of prothrombin, known as PIVKA‐II (prothrombin induced by vitamin K absence for factor II), and a decrease in total prothrombin, in the blood of the newborn.

Methods: Cord blood was collected from the placenta at the time of parturition from 12 women who had received anticonvulsant therapy during pregnancy and from 11 control women.

Results: PIVKA‐II was present in cord blood from control mothers at low or nondetectable levels. In the same samples, total prothrombin concentrations were −50% of adult levels, but there was wide variation between individuals. Exposure to carbamazepine (CBZ) alone during pregnancy was associated with markedly increased PIVKA‐II levels in four of six samples and decreased total prothrombin levels for the whole group. High PIVKA‐II levels also were recorded in one cord blood sample from a mother who received phenytoin (PHT) and vigabatrin (VGB). Two cases of PHT alone and one of valproic acid (VPA) alone were not associated with increased PIVKA‐II levels.

Conclusions: These results are consistent with the hypothesis that some anticonvulsants (particularly CBZ) interfere with vitamin K metabolism during pregnancy and may result in hematologic signs of vitamin K deficiency in the newborn.
Overview of Pharmacology and Clinical Trials Program with the Zotarolimus‐Eluting Endeavor Stent
Authors: KANDZARI DAVID E. , LEON MARTIN B.
Published: October 2006

Despite considerable benefits associated with current drug‐eluting stents (DES), continued attention to the safety, efficacy, and deliverability of first‐generation DES has led to the development of new antiproliferative agents with alternative stent platforms and different drug carrier systems. Zotarolimus is a recently developed pharmacologic agent with both antiproliferative and anti‐inflammatory properties. The Endeavor drugeluting stent (Medtronic Vascular, Santa Rosa, CA) represents the combination of zotarolimus, a low‐profile cobalt alloy stent platform, and a biocompatible phosphorylcholine drug carrier system. At present, four clinical trials examining the safety and efficacy of the Endeavor stent have been performed. Although these studies have enrolled patients with similar clinical and angiographic characteristics, they have differed in trial design and study population size and have been performed across a broad geographic and physician distribution. Despite these differences, the results of these trials demonstrate consistently low rates of angiographic restenosis and repeat revascularization in addition to a favorable safety profile, with no occurrences of late stent thrombosis through 1 year of follow‐up. This review describes the pharmacology and design on the Endeavor stent, summarizes results from recent clinical trials evaluating the Endeavor stent, and provides an overview of ongoing and future directions for clinical investigation.