bluuebunny/crossref_metadata_2025 huggingface dataset:
Cell model of inflammation
Authors: Franchi Jocelyne , Marteau Clarisse , Crola Da Silva Claire , Mitterrand Michèle , André Patrice , Kieda Claudine
Published: February 2008

Chemical and physical stimuli trigger a cutaneous response by first inducing the main epidermal cells, keratinocytes, to produce specific mediators that are responsible for the initiation of skin inflammation. Activation modulates cell communication, namely leucocyte recruitment and blood-to-skin extravasation through the selective barrier of the vascular ECs (endothelial cells). In the present study, we describe an in vitro model which takes into account the various steps of human skin inflammation, from keratinocyte activation to the adhesion of leucocytes to dermal capillary ECs. Human adult keratinocytes were subjected to stress by exposure to UV irradiation or neuropeptides, then the conditioned culture medium was used to mimic the natural micro-environmental conditions for dermal ECs. A relevant in vitro model must include appropriate cells from the skin. This is shown in the present study by the selective reaction of dermal ECs compared with EC lines from distinct origins, in terms of leucocyte recruitment, sensitivity to stress and nature of the stress-induced secreted mediators. This simplified model is suitable for the screening of anti-inflammatory molecules whose activity requires the presence of various skin cells.
Simulations of structure II H2 and D2 clathrates: Potentials incorporating quantum corrections
Authors: Alavi Saman , Klug D. D. , Ripmeester J. A.
Published: February 2008

Molecular dynamics simulations are used to study the stability of structure II H2 and D2 clathrates with different large and small guest occupancies at 160 and 250K and 2.0kbars. Simulations are performed with the recently proposed anisotropic site-site potentials of Wang for H2 and D2 [J. Quant. Spectrosc. Radiat. Transf. 76, 23 (2003)] which are parameterized to account for quantum corrections of order ℏ2 in the second virial coefficient. Occupancies of 0–2 in the small cages and 2–5 in the large cages are considered. Thermodynamic integration is used to determine the most stable guest occupancy at each temperature. Since lattice free energy and configurational energy differences are small for a number of different combinations of cage occupancies, one must expect that in bulk samples various combinations will indeed be observed. Special attention is given to the differences between H2 and D2 guests and implications on the hydrogen storage capacity of the clathrates are discussed.
Fourier transform infrared observation of the ν3(σu) vibration of NiC3Ni in solid Ar
Authors: Kinzer R. E. , Rittby C. M. L. , Graham W. R. M.
Published: February 2008

The Fourier transform infrared spectrum of linear NiC3Ni was observed by trapping the vapor produced from the dual ablation of nickel and carbon rods with Nd:YAG (yttrium aluminum garnet) lasers in solid Ar at ∼10K. Measurements of C13 isotopic shifts have enabled the identification of the ν3(σu) vibrational fundamental at 1950.8±0.2cm−1, an asymmetric carbon stretching mode. Experimental results are in good agreement with the predictions of density functional theory at the B3LYP∕6-311G* level. Theoretical results suggest that the molecule is slightly floppy. Although other nickel carbide clusters have been studied theoretically or observed by photoelectron spectroscopy or mass spectrometry, this is the first report on the structure of NiC3Ni and its vibrational spectrum.
Quantum and electromagnetic propagation with the conjugate symmetric Lanczos method
Authors: Acevedo Ramiro , Lombardini Richard , Turner Matthew A. , Kinsey James L. , Johnson Bruce R.
Published: February 2008

The conjugate symmetric Lanczos (CSL) method is introduced for the solution of the time-dependent Schrödinger equation. This remarkably simple and efficient time-domain algorithm is a low-order polynomial expansion of the quantum propagator for time-independent Hamiltonians and derives from the time-reversal symmetry of the Schrödinger equation. The CSL algorithm gives forward solutions by simply complex conjugating backward polynomial expansion coefficients. Interestingly, the expansion coefficients are the same for each uniform time step, a fact that is only spoiled by basis incompleteness and finite precision. This is true for the Krylov basis and, with further investigation, is also found to be true for the Lanczos basis, important for efficient orthogonal projection-based algorithms. The CSL method errors roughly track those of the short iterative Lanczos method while requiring fewer matrix-vector products than the Chebyshev method. With the CSL method, only a few vectors need to be stored at a time, there is no need to estimate the Hamiltonian spectral range, and only matrix-vector and vector-vector products are required. Applications using localized wavelet bases are made to harmonic oscillator and anharmonic Morse oscillator systems as well as electrodynamic pulse propagation using the Hamiltonian form of Maxwell’s equations. For gold with a Drude dielectric function, the latter is non-Hermitian, requiring consideration of corrections to the CSL algorithm.
Element-specific recoil loops in Sm–Co∕Fe exchange-spring magnets
Authors: Choi Y. , Jiang J. S. , Pearson J. E. , Bader S. D. , Liu J. P.
Published: February 2008

In two-phase nanocomposite magnets, open recoil loops have shown to be sensitive to interphase interfacial conditions and have been often used to characterize the interphase exchange coupling. Typically, the open recoil loops are attributed to the soft phase volume that is decoupled from the hard phase. Our element-specific magnetic measurements on bilayer Sm–Co∕Fe exchange-spring magnets reveal that open recoil loops are present not only in the soft Fe layer but also in the hard Sm–Co layer and that the Fe- and Sm-specific remanence curves are similar to each other. The experimental results and micromagnetic modeling reveal that the observed open recoil loops can originate from the anisotropy variations in the hard Sm–Co layer.
Spin disorder and magnetic properties of Bi3∕4Ca1∕4MnO3
Authors: García–Muñoz J. L. , Frontera C.
Published: February 2008

We present a study on the magnetic and electronic properties of Bi0.75Ca0.25MnO3, investigated by means of magnetometry, diffraction, and muon spin relaxation techniques. The anisotropic changes of cell parameters across the structural transition in Bi0.75Ca0.25MnO3 (275K) differ markedly from the lattice anomalies not only in Bi0.75Sr0.25MnO3 (600K) but also in Bi0.50Ca0.50MnO3 (325K). We have confirmed the absence of a ferromagnetic component under zero field in Bi0.75Ca0.25MnO3. The application of magnetic fields produces a continuous progressive polarization of Mn moments. The ground state of Bi0.75Ca0.25MnO3 is characterized by a high degree of spin disorder and frustrated interactions. A well-developed long-range magnetic order is not observed. Our results indicate a ground state in Bi0.75Ca0.25MnO3 distinct to Bi0.75Sr0.25MnO3.
Effects of intermolecular interaction on inelastic electron tunneling spectra
Authors: Kula Mathias , Luo Yi
Published: February 2008

We have examined the effects of intermolecular interactions on the inelastic electron tunneling spectroscopy (IETS) of model systems: a pair of benzenethiol or a pair of benzenedithiol sandwiched between gold electrodes. The dependence of the IETS on the mutual position of and distance between the paired molecules has been predicted and discussed in detailed. It is shown that, although in most cases, there are clear spectral fingerprints present which allow identification of the actual structures of the molecules inside the junction. Caution must be exercised since some characteristic lines can disappear at certain symmetries. The importance of theoretical simulation is emphasized.
Finite size effects on spin-torque driven ferromagnetic resonance in spin valves with a Co∕Ni synthetic free layer
Authors: Chen W. , de Loubens G. , Beaujour J.-M. L. , Kent A. D. , Sun J. Z.
Published: February 2008

Spin-torque driven ferromagnetic resonance (ST-FMR) is used to study magnetic excitations in Co∕Ni synthetic layers confined in nanojunctions. Field swept ST-FMR measurements were conducted with a magnetic field applied perpendicular to the layer surface. The resonance lines were measured under low amplitude excitation in a linear response regime. The resulting resonance fields were compared with those obtained using conventional rf field driven FMR on extended films with the same Co∕Ni layer structure. A lower resonance field is found in confined structures. The effect of both dipolar fields acting on the Co∕Ni layer emanating from other magnetic layers in the device and finite size effects on the spin wave spectrum are discussed.
Magnetic resonance in porous media: Recent progress
Authors: Song Yi-Qiao , Cho H. , Hopper Tim , Pomerantz Andrew E. , Sun Phillip Zhe
Published: February 2008

Recent years have seen significant progress in the NMR study of porous media from natural and industrial sources and of cultural significance such as paintings. This paper provides a brief outline of the recent technical development of NMR in this area. These advances are relevant for broad NMR applications in material characterization.
Quantitative investigation of the magnetic anisotropy in GaMnAs film by using Hall measurement
Authors: Son Hyunji , Chung Sun-jae , Yea Sun-young , Lee Sanghoon , Liu X. , Furdyna J. K.
Published: February 2008

We have performed a systematic Hall measurement on the GaMnAs ferromagnetic films. The angular dependences of the Hall effects were obtained by changing the magnetic field angle in two different crystal planes [i.e., (001) and (110)]. The in-plane and out-of-plane anisotropy fields were obtained by analyzing the angular dependence of planar Hall resistance and anomalous Hall resistance based on the magnetic free energy model. While the cubic anisotropy fields both for in-plane and out-of-plane showed strong temperature dependence, the uniaxial anisotropy fields were insensitive to the temperature.
Decomposition pathways of methanol on the PtAu(111) bimetallic surface: A first-principles study
Authors: Yuan Dingwang , Gong Xingao , Wu Ruqian
Published: February 2008

Systematic density functional studies revealed that PtAu(111) significantly alters the reaction kinetics of methanol oxidation from that on Pt(111). PtAu(111) facilitates the reaction path that starts from cleavage of the OH bond. Furthermore, it prevents CH2O from immediate decomposition as on the clean Pt(111) surface. This indicates that proper arrangement of Au and Pt sites offers great opportunities for non-COad paths for high H productivity in fuel cells.
Surface ferromagnetism and exchange bias in vacuum annealed Co3−yZnyO4 films
Authors: Sudakar C. , Kharel P. , Lawes G. , Suryanarayanan R. , Naik R. , Naik V. M.
Published: February 2008

We report on the structural and the magnetic properties of spin coated Co3−yZnyO4 thin films. The microstructure of high vacuum annealed films exhibit a crystalline Zn:CoO core with a disordered oxygen deficient amorphous Co:ZnO surface. Weak ferromagnetism (m∼15mμB∕Co) and an exchange bias (HE∼500Oe) are observed at 10K despite the absence of any Co metal clusters. HE is smaller for samples with smaller Zn fractions (for Co3O4-HV, HE∼250Oe). Adding Zn significantly enhances HE. The exchange anisotropy in an antiferromagnetic material due to surface disordered weak ferromagnetism and its overall implications to dilute magnetic semiconducting oxides are discussed.
Extremely low temperature growth of ZnO by atomic layer deposition
Authors: Guziewicz E. , Kowalik I. A. , Godlewski M. , Kopalko K. , Osinniy V. , Wójcik A. , Yatsunenko S. , Łusakowska E. , Paszkowicz W. , Guziewicz M.
Published: February 2008

We report on the zinc oxide (ZnO) thin films obtained by the atomic layer deposition (ALD) method using diethyl zinc and water precursors, which allowed us to lower deposition temperature to below 200 °C. The so-obtained “as grown” ZnO layers are polycrystalline and show excitonic photoluminescence (PL) at room temperature, even if the deposition temperature was lowered down to 100 °C. Defect-related PL bands are of low intensity and are absent for layers grown at 140−200 °C. This is evidence that extremely low temperature growth by ALD can result in high quality ZnO thin films with inefficient nonradiative decay channels and with thermodynamically blocked self-compensation processes.
Interface termination and band alignment of epitaxially grown alumina films on Cu–Al alloy
Authors: Yoshitake Michiko , Song Weijie , Libra Jiří , Mašek Karel , Šutara František , Matolín Vladimír , Prince Kevin C.
Published: February 2008

Epitaxial ultrathin alumina films were grown on a Cu−9 at. % Al(111) substrate by selective oxidation of Al in the alloy in ultrahigh vacuum. The photoelectron spectra of Al 2p and valence band were measured in situ during oxidation. By analyzing multiple peaks of Al 2p, the interface atomic structure was discussed. The energy difference between the Fermi level of the substrate and the valence band maximum of alumina (band offset) was obtained. The relation between the interface atomic structure and the band offset was compared with the reported first-principles calculations. A novel method for controlling the band offset was proposed.
Spin-orbit ab initio investigation of the photolysis of o-, m-, and p-bromotoluene
Authors: Liu Ya-Jun , Tian Yan-Cong , Fang Wei-Hai
Published: February 2008

The photodissociations of o-, m-, and p-bromotoluene were investigated by ab initio and spin-orbit ab initio calculations. The possible photodissociation mechanisms at 266 and 193nm were clarified by multistate second order multiconfigurational perturbation theory (MS-CASPT2) calculated potential energy curves, vertical excitation energies, and oscillator strengths of low-lying states. The dissociation products with spin-orbit-coupled states of Br*(P1∕22) and Br(P3∕22) were identified by the MS-CASPT2 method in conjunction with spin-orbit interaction through complete active space state interaction (MS-CASPT2/CASSI-SO) calculations. The effects of methyl rotation and substituent on the photodissociation mechanism were discussed.
Formation of the CH fragment in the 193nm photodissociation of CHCl
Authors: Shin Seung Keun , Dagdigian Paul J.
Published: February 2008

The CH fragment from the 193nm photodissociation of CHCl is observed in a molecular beam experiment. This fragment is formed in the higher-energy dissociation pathway, the lower pathway involving formation of CCl. Both the CHCl parent molecule and the CH fragment were detected by laser-induced fluorescence. The 193nm CHCl absorption cross section was estimated from the reduction of the CHCl signal as a function of the photolysis laser fluence. The CH internal state distribution was derived from the analysis of laser-induced fluorescence spectra of the A-X Δv=0 sequence. A modest degree of rotational excitation was found in the CH fragment; the most probable rotational level is N=1, but the distribution has a tail extending to N>25. Also observed is a slight preference for formation of Λ-doublets of A″ symmetry, which appears to increase with increasing rotational angular momentum N. Vibrationally excited CH was observed, and the degree of vibrational excitation was found to be low. The energy available to the photofragments is predominantly released as translational excitation. The preferential formation of A″ Λ-doublets suggests that dissociation occurs through a nonlinear excited state.
Size-dependent enhancement of nonlinear optical properties in nanocolloids of ZnO
Authors: Irimpan Litty , Nampoori V. P. N. , Radhakrishnan P. , Krishnan Bindu , Deepthy A
Published: February 2008

We have investigated the third-order nonlinearity in ZnO nanocolloids with particle sizes in the range 6–18 nm by the z-scan technique. The third-order optical susceptibility χ(3) increases with increasing particle size (R) within the range of our investigations. In the weak confinement regime, an R2 dependence of χ(3) is obtained for ZnO nanocolloids. The optical limiting response is also studied against particle size.
The crystallinity and surface morphology of zinc octaethylporphyrin thin films on an indium-tin-oxide substrate
Authors: Ryuzaki S. , Onoe J.
Published: February 2008

The crystallinity and surface morphology of zinc octaethylporphyrin, Zn(OEP), thin films (20 nm thick) deposited on an indium-tin-oxide substrate have been investigated using x-ray diffraction (XRD) and scanning electron microscopy (SEM). XRD and SEM results show that the Zn(OEP) film formed at room temperature (RT) was amorphous and its surface morphology was smooth, whereas the film deposited at 473 K was crystalline and its surface morphology became rough compared to that formed at RT. On the other hand, when the Zn(OEP) film formed at RT was subsequently annealed at 473 K for 1 min, the film was crystallized as well as formed at 473 K but its surface morphology was maintained to be smooth.
Proton irradiation of germanium isotope multilayer structures at elevated temperatures
Authors: Schneider S. , Bracht H. , Petersen M. C. , Hansen J. Lundsgaard , Larsen A. Nylandsted
Published: February 2008

Irradiation of germanium (Ge) isotope heterostructures with 2.5 MeV protons have been performed at 550 °C. The applied proton flux was varied between 1.0 and 1.5 μA leading to various rates of Frenkel pair production. After irradiation, concentration profiles of the Ge isotopes were recorded by means of secondary ion mass spectrometry (SIMS). An inhomogeneous broadening of the isotope structure was observed. In addition to the effect of irradiation enhanced self-diffusion, an influence of the formation of microscopic defects on the detected broadening was ascertained. Atomic force and scanning electron microscopy show that the microscopic defects are most probably resulting from an aggregation of vacancies formed during irradiation. Numerical analysis of Ge profiles not disturbed by microdefect formation indicates a significant contribution of self-interstitials to self-diffusion under irradiation.
Oxygen incorporation in Ti2AlC thin films
Authors: Rosen J. , Persson P. O. Å. , Ionescu M. , Kondyurin A. , McKenzie D. R. , Bilek M. M. M.
Published: February 2008

Thin films of Ti2AlC MAX phase have been deposited using a multiple cathode pulsed cathodic arc. Evidence for substantial oxygen incorporation in the MAX phase is presented, likely originating from residual gas present in the vacuum chamber during deposition. The characteristic MAX phase crystal structure is maintained, in agreement with ab initio calculations, supporting substitutional O in C lattice positions. On the basis of these results, we propose the existence of a MAX phase-like material with material properties tuned by the incorporation of oxygen. Additionally, possible unintentional O incorporation in previously reported MAX phase materials is suggested.
Criteria for improved open-circuit voltage in a-Si:H(N)∕c-Si(P) front heterojunction with intrinsic thin layer solar cells
Authors: Nath Madhumita , Chatterjee P. , Damon-Lacoste J. , Roca i Cabarrocas P.
Published: February 2008

Hydrog enated amorphous∕crystalline silicon “heterojunction with intrinsic thin layer (HIT)” solar cells have gained popularity after it was demonstrated by Sanyo that they can achieve stable conversion efficiencies, as high as crystalline silicon (c-Si) cells, but where the cost may be reduced with the help of amorphous silicon (a-Si:H) low temperature deposition technology. In this article, we study N-a-Si:H∕P-c-Si front HIT structures, where light enters through the N-a-Si:H layer. The aim is to examine ways of improving the open-circuit voltage, using computer modeling in conjunction with experiments. We also assess under which conditions such improvements in Voc actually occur. Modeling indicates that for a density of states Nss⩾1013cm−2 on the surface of the P-c-Si wafer facing the emitter layer, Voc is entirely limited by this parameter and is lower than 0.5V. We also learn that it is possible to increase the Voc to ∼0.73V by reducing this defect density to ∼1010cm−2, by reducing the surface recombination speed of the electrons at the back P-c-Si∕aluminum contact (SnL), and by improving the lifetime of the carriers (τ) in the P-c-Si wafer to ∼5ms. Modeling further indicates that when τ⩽0.1ms, the sensitivity of Voc to SnL vanishes, as very few back-diffusing electrons can reach the back contact. Improvements in Voc by decreasing both the defect density on the surface of the P-c-Si wafer facing the emitter layer and SnL have been achieved in practice by (a) improved passivation thanks to a thin intrinsic polymorphous silicon layer deposited on the c-Si wafer (instead of a-Si:H) and (b) using localized aluminum and back surface field layers to attain a lower SnL. Experimentally, a Voc of 0.675V has already been attained. Simulations indicate that the lifetime of carriers inside the P-c-Si wafer of these cells is ∼366μs and needs to be improved to achieve a higher Voc.
A diagonal cut through the SiC bulk unit cell: Structure and composition of the 4H-SiC(11¯02) surface
Authors: Virojanadara C. , Hetzel M. , Starke U.
Published: February 2008

The atomic and electronic structure of 4H-SiC(11¯02) surfaces was investigated using low-energy electron diffraction, scanning tunneling microscopy, and photoelectron spectroscopy. Three well ordered phases can be prepared by Si deposition and annealing. The (2×1) phase is Si enriched and terminated by an ordered array of Si-adatom chains which contribute an anisotropic electronic surface state. The c(2×2) phase has a surface composition close to SiC bulk and possesses adatoms in the periodicity of the superlattice. At high temperatures, a (1×1) phase develops with a graphitelike composition.
High light extraction efficiency of gallium nitride light emitting diode with silicon oxide hemispherical microlens
Authors: Lee M. K. , Ho C. L. , Fan C. H.
Published: February 2008

Silicon oxide hemispherical microlens with the density of 9.5×108cm−2 was formed on gallium nitride light emitting diode to enhance the light extraction efficiency by liquid phase deposition. The light output power exhibits 1.29 times enhancement compared to that without microlens. After the thermal annealing with nitrous oxide, the output power is further improved to 1.44 times due to higher silicon oxide quality and gallium nitride surface passivation.
On the eigensolutions of the one-dimensional Duffin–Kemmer–Petiau oscillator
Authors: Boumali A.
Published: February 2008

The one-dimensional eigenfunctions and the eigenvalues of massive spin-0 and spin-1 particles have been found by using the Duffin–Kemmer–Petiau equation. Following Greiner [Quantum Mechanics: An introduction, 4th ed. (Springer-verlag, Berlin, 2001)], we have shown that the eigensolutions in both cases are decoupled in two sets.
Producing well aligned in situ composites in peritectic systems by directional solidification
Authors: Luo L. S. , Su Y. Q. , Guo J. J. , Li X. Z. , Yang H. M. , Fu H. Z.
Published: February 2008

Recently, it was found that cellular peritectic coupled growth (CPCG) can be a candidate method to grow well aligned in situ composites in peritectic alloys. In this letter, we experimentally show that there is a narrow growth region in which CPCG can be stable to avoid the influences of peritectic reaction around the trijunctions and the sidebranching instability to produce well aligned in situ composites. A simplified model was developed to predict the growth region of stable CPCG. Good agreement was obtained between the theoretical predictions and the experimental observations.
Enhanced magnetoelectric effect in nanostructured magnetostrictive thin film resonant actuator with field induced spin reorientation transition
Authors: Tiercelin Nicolas , Preobrazhensky V. , Pernod P. , Ostaschenko A.
Published: February 2008

We report the use of a magnetic instability of the spin reorientation transition type to enhance the magnetoelectric sensitivity in magnetostrictive-piezoelectric structures. We present the theoretical study of a clamped beam resonant actuator composed of a piezoelectric element on a nonpiezo substrate actuated by a magnetostrictive layer. The experiments are made on a polished 150μm thick 18×3mm2 lead zirconate titanate (PZT) plate glued to a 50μm silicon plate and coated with a giant magnetostrictive nanostructured Nx(TbCo25nm∕FeCo5nm) layer. Another set of experiments was done with PZT substrate only. Results agree with analytical theory.
Selective etching of independent contacts in a double quantum-well structure: Quantum-gate transistor
Authors: Lang S. , Worschech L. , Emmerling M. , Strauß M. , Höfling S. , Forchel A.
Published: February 2008

Double GaAs quantum wells (QWs) embedded between modulation-doped AlGaAs barriers with different aluminium (Al) contents were grown by molecular beam epitaxy. Independent electric contacts to each well were realized by applying different etching techniques without substrate removal. In particular, the lower quantum well was electrically pinched off by a local undercut of the lower AlGaAs barrier exploiting an Al selective etching process. In contrast, the upper quantum well was locally depleted by top etched trenches. Transistor operation of quantum wires defined in such bilayers is demonstrated at room temperature with one GaAs layer used as conducting channel controlled by the other nearby GaAs layer as efficient quantum gate.
Impact of lattice strain on the phase formation, polarization, and dielectric constant of PbZr1−xTixO3 films
Authors: Yan W. S. , Zhang R. , Xiu X. Q. , Xie Z. L. , Han P. , Jiang R. L. , Gu S. L. , Shi Y. , Zheng Y. D.
Published: February 2008

A phenomenological thermodynamic theory of ferroelectric thin films on noncubic substrates is developed using a nontraditional form of the thermodynamic potential. For single-domain PbZr1−xTixO3 50∕50 film, the “lattice strain-temperature” phase diagram is constructed. It is found that the lattice strain induces a shift of the Curie temperature of the ferroelectric transition. The unusual r phase that is forbidden in single crystals and bulk ceramics appears in thin film. The “lattice strain-polarization” diagram and “lattice strain-dielectric constant” diagram at room temperature are also predicted. They all show discontinuous at the transition interface.
Improvement of ferroelectric fatigue endurance in multiferroic (Ba0.5Sr0.5)TiO3∕(Bi1.05La0.05)FeO3∕(Ba0.5Sr0.5)TiO3 sandwich structures
Authors: Miao Jun , Zhang Bo Ping , Chew Khian Hooi , Wang Yu
Published: February 2008

We report the improved ferroelectric properties in dielectric/multiferroic/dielectric sandwich structures composed of Ba0.5Sr0.5TiO3 (BST) and Bi1.05La0.05FeO3 (BLF). Compared with the single BLF film, the trilayer structures exhibit a lower dielectric loss and weaker frequency dependence of dielectric properties. At room temperature, the remnant polarization and saturation polarization of the trilayer structures are 34.3 and 46.9μC∕cm2, respectively. More interestingly, the polarization of BST/BLF/BST trilayer exhibits a fatigue-free characteristic of up to 109 switching cycles. Applying Dawber’s model, the concentration of oxygen vacancies and barrier energy of oxygen vacancies migration in BST/BLF/BST trilayer are calculated as 6.1×1017cm−3 and 1.33eV, respectively.
The Redistribution of Residential Property Values in Montreal, Toronto, and Vancouver: Examining Neoclassical and Marxist Views on Changing Investment Patterns
Authors: Skaburskis Andrejs , Moos Markus
Published: February 2008

This study examines the changes in residential property value in Canada's three largest metropolitan areas by using shift-share and regression analysis with census tract data. The results show that the tracts that increased their share of the metropolitan areas' real estate value in one decade tend to lose that share during the next decade. After accounting for the effect of new additions, the main transfer of wealth is from the older suburban ring to both the inner city and the new suburbs. The largest variation in the growth of property value is not between the new suburbs and the inner city but across the inner-city census tracts. The shifts and cycles of investment across broad city sectors predicted by neoclassical and Marxist theory are overwhelmed by local factors.
Society, Technology, and Region: Contributions from the Social Study of Technology to Economic Geography
Authors: Truffer Bernhard
Published: February 2008

Recent debates in economic geography have emphasized the need for a more explicit analysis of innovation processes at a sectoral or technological level. A great deal of attention has furthermore been devoted to connect the internal disciplinary debate with the wider discourse of the social sciences that deal with economic development in general and with the role of innovation in particular. In the present paper I argue that the field of the social study of technology (SST) can inspire research in economic geography in important respects: SST research has an explicit focus on the genesis of sociotechnical configurations; it has developed sector-related and technology-related multilevel theories of sociotechnical change; it has a strong emphasis on innovation dynamics and sector transformations; and finally, it has a focus on strategic planning in multiactor settings and thus favors foresight and participatory planning approaches in science, technology, and innovation policy. SST-inspired research could thus be an interesting partner for those approaches within economic geography that share some ontological starting positions with regard to actors, the role of institutions, and a revolutionary and multilevel analysis of sociotechnical transformation processes.
Practice, Space, and the Duality of Meaning
Authors: Netto Vinicius
Published: February 2008

The paper aims at a rewriting of the concept of meaning as a connection between the social and the material, a multiple connection, perhaps the only possible intrinsic connection between things as different as ‘practice’ and ‘space’, and a major condition of what has been recently addressed as ‘inherent relatedness’. Drawing mainly on Niklas Luhmann's theory of self-referentiality, I propose a reinterpretation of relatedness as a property of meaning. That property is defined as a duality of meaning—ie meaning as an event in our experience, yet in itself an experience of reference to acts, places, and other meanings. It implies that the very definition of meaning is referential—it is never self-contained or centred; it, rather, alludes always already to other meanings, acts, and spaces, referentially crossing boundaries while reasserting sensual and perceptive qualities. This renewed concept of meaning is proposed as a way to unveil relationality while actively keeping the subject's experience of identities and different materialities at work in the relation between practice and space. The paper places this key ontological problem and the quest for a relation between the social and the material into a particular, overlooked aspect of the society–space relation: the moment of sociation of practice and its informational, linguistic, and material conditions—a turn to communication and a ‘referential approach’ to the materiality of the social world.
Notch and bone morphogenetic protein differentially act on dermomyotome cells to generate endothelium, smooth, and striated muscle
Authors: Ben-Yair Raz , Kalcheim Chaya
Published: February 2008

We address the mechanisms underlying generation of skeletal muscle, smooth muscle, and endothelium from epithelial progenitors in the dermomyotome. Lineage analysis shows that of all epithelial domains, the lateral region is the most prolific producer of smooth muscle and endothelium. Importantly, individual labeled lateral somitic cells give rise to only endothelial or mural cells (not both), and endothelial and mural cell differentiation is driven by distinct signaling systems. Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells. On the other hand, bone morphogenetic protein signaling is required for endothelial cell differentiation and/or migration but inhibits striated muscle differentiation and fails to impact smooth muscle cell production. Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system. Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium.
The Hsp90 chaperone controls the biogenesis of L7Ae RNPs through conserved machinery
Authors: Boulon Séverine , Marmier-Gourrier Nathalie , Pradet-Balade Bérengère , Wurth Laurence , Verheggen Céline , Jády Beáta E. , Rothé Benjamin , Pescia Christina , Robert Marie-Cécile , Kiss Tamás , Bardoni Barbara , Krol Alain , Branlant Christiane , Allmang Christine , Bertrand Edouard , Charpentier Bruno
Published: February 2008

RNA-binding proteins of the L7Ae family are at the heart of many essential ribonucleoproteins (RNPs), including box C/D and H/ACA small nucleolar RNPs, U4 small nuclear RNP, telomerase, and messenger RNPs coding for selenoproteins. In this study, we show that Nufip and its yeast homologue Rsa1 are key components of the machinery that assembles these RNPs. We observed that Rsa1 and Nufip bind several L7Ae proteins and tether them to other core proteins in the immature particles. Surprisingly, Rsa1 and Nufip also link assembling RNPs with the AAA + adenosine triphosphatases hRvb1 and hRvb2 and with the Hsp90 chaperone through two conserved adaptors, Tah1/hSpagh and Pih1. Inhibition of Hsp90 in human cells prevents the accumulation of U3, U4, and telomerase RNAs and decreases the levels of newly synthesized hNop58, hNHP2, 15.5K, and SBP2. Thus, Hsp90 may control the folding of these proteins during the formation of new RNPs. This suggests that Hsp90 functions as a master regulator of cell proliferation by allowing simultaneous control of cell signaling and cell growth.
Auslander Regularity of 𝑝-adic Distribution Algebras
Authors: Schmidt Tobias
Published: February 2008

Given a compactpp-adic Lie group over an arbitrary base field we prove that its distribution algebra is Fréchet-Stein with Auslander regular Banach algebras whose global dimensions are bounded above by the dimension of the group. As an application, we show that nonzero coadmissible modules coming from smooth or, more generally, U(g)U(\mathfrak {g})-finite representations have a maximal grade number (codimension) equal to the dimension of the group.
Model Specification in Instrumental-Variables Regression
Authors: Dunning Thad
Published: February 2008

In many applications of instrumental-variables regression, researchers seek to defend the plausibility of a key assumption: the instrumental variable is independent of the error term in a linear regression model. Although fulfilling this exogeneity criterion is necessary for a valid application of the instrumental-variables approach, it is not sufficient. In the regression context, the identification of causal effects depends not just on the exogeneity of the instrument but also on the validity of the underlying model. In this article, I focus on one feature of such models: the assumption that variation in the endogenous regressor that is related to the instrumental variable has the same effect as variation that is unrelated to the instrument. In many applications, this assumption may be quite strong, but relaxing it can limit our ability to estimate parameters of interest. After discussing two substantive examples, I develop analytic results (simulations are reported elsewhere). I also present a specification test that may be useful for determining the relevance of these issues in a given application.
Caesarean delivery and risk of atopy and allergic disesase: meta‐analyses
Authors: Bager P. , Wohlfahrt J. , Westergaard T.
Published: February 2008

Background
Studies of delivery by caesarean section (c‐section) and the offspring's risk of allergic diseases are of current interest due to concerns about the increased use of c‐section in many countries. However, previous studies have reported inconsistent findings.

Objective
We investigated whether delivery by c‐section is associated with an increased risk of atopy and allergic disease by reviewing the literature, performing a meta‐analysis, and assessing publication bias.

Methods
We used a systematic literature search of MEDLINE (1966 to May 2007). Six common allergic outcomes were included: food allergy/food atopy, inhalant atopy, eczema/atopic dermatitis, allergic rhinitis, asthma, and hospitalization for asthma. For each outcome a meta‐analysis was performed, where a summary odds ratio (OR) was calculated taking into account heterogeneity between the study‐specific relative risks. Publication bias was assessed using the funnel plot method.

Results
We identified 26 studies on delivery by c‐section and one or more of the six allergic outcomes. C‐section was associated with an increased summary OR of food allergy/food atopy (OR 1.32, 95% CI 1.12–1.55; six studies), allergic rhinitis (OR 1.23, 95% CI 1.12–1.35; seven studies), asthma (OR 1.18, 95% CI 1.05–1.32; 13 studies), and hospitalization for asthma (OR 1.21, 95% CI 1.12–1.31; seven studies), whereas there was no association with inhalant atopy (OR 1.06, 95% CI 0.82–1.38; four studies) and eczema/atopic dermatitis (OR 1.03, 95% CI 0.98–1.09; six studies). Funnel plots indicated that the association with food allergy/food atopy could be difficult to interpret due to publication bias. For each significant association with an allergic outcome, only 1–4% of cases were attributable to c‐section.

Conclusion
Delivery by c‐section is associated with a moderate risk increase for allergic rhinitis, asthma, hospitalization for asthma, and perhaps food allergy/food atopy, but not with inhalant atopy or atopic dermatitis. The increased use of c‐section during the last decades is unlikely to have contributed much to the allergy epidemic observed during the same period.
Simulated glacial and interglacial vegetation across Africa: implications for species phylogenies and trans‐African migration of plants and animals
Authors: COWLING SHARON A. , COX PETER M. , JONES CHRIS D. , MASLIN MARK A. , PEROS MATHEW , SPALL STEVEN A.
Published: February 2008

The paleoenvironmental context of plant and animal species evolution (including glacial migrations and population separations) is based on a very patchy and incomplete paleo‐phytogeographic record. It was our objective, therefore, to provide an additional source for paleovegetation comparison by presenting simulations from a state‐of‐the‐art fully coupled earth system model (HadCM3LC). We simulated potential paleovegetation distributions following pre‐Industrial and last glacial maximum (LGM) climate forcing for the continent of Africa. Our LGM simulations indicate that tropical broadleaf forest was not severely displaced by expanding grasslands within central Africa, although the outer extent of closed forest decreases, particularly in the north. Our simulations indicate that the structure of glacial forests may have been much different from today, in that LGM simulations indicate that forests were likely characterized by lower leaf area indexes, lower tree heights and lower vegetation carbon content. On the other hand, warmer interglacial climate (like our pre‐Industrial climate scenario) results in simulated expansion of tropical forest from coast to coast across central Africa that we postulate could have acted as a barrier to plant and animal species migrations. We suggest that our modeling experiments have implications for the interpretation of phylogenetic data, including that of our own species, Homo sapiens sapiens.
Modelling the concentrations of nitrogen and water‐soluble carbohydrates in grass herbage ingested by cattle under strip‐grazing management
Authors: Hoekstra N. J. , Schulte R. P. O.
Published: February 2008

There is scope of increasing the nitrogen (N) efficiency of grazing cattle through manipulation of the energy and N concentrations in the herbage ingested. Because of asymmetric grazing by cattle between individual plant parts, it has not yet been established how this translates into the concentrations of N and water‐soluble carbohydrates (WSC) in the herbage ingested. A model is described with the objective of assessing the efficacy of individual tools in grassland management in manipulating the WSC and N concentrations of the herbage ingested by cattle under strip‐grazing management throughout the growing season. The model was calibrated and independently evaluated for early (April), mid‐ (June, regrowth phase) and late (September) parts of the growing season. There was a high correlation between predicted and observed WSC concentrations in the ingested herbage (R2 = 0·78,P < 0·001). The correlation between predicted and observed neutral‐detergent fibre (NDF) concentrations in the ingested herbage was lower (R2 = 0·49,P < 0·05) with a small absolute bias. Differences in the N concentration between laminae and sheaths, and between clean patches and fouled patches, were adequately simulated and it was concluded that the model could be used to assess the efficacy of grassland management tools for manipulating the WSC and N concentrations in the ingested herbage. Model application showed that reduced rates of application of N fertilizer and longer rotation lengths were effective tools for manipulating herbage quality in early and mid‐season. During the later part of the growing season, the large proportion of area affected by dung and urine reduced the effect of application rate of N fertilizer on herbage quality. In contrast, relative differences between high‐sugar and low‐sugar cultivars of perennial ryegrass were largest during this period. This suggests that high‐sugar cultivars may be an important tool in increasing N efficiency by cattle when risks of N losses to water bodies are largest. The model output showed that defoliation height affects the chemical composition of the ingested herbage of both the current and the subsequent grazing period.
Effect of ensiling field bean, field pea and common vetch in different proportions with whole‐crop wheat using formic acid or an inoculant on fermentation characteristics
Authors: Pursiainen P. , Tuori M.
Published: February 2008

Whole‐crop field bean (FB), field pea (FP) and common vetch (CV) [155, 213 and 238 g dry matter (DM) kg−1] were ensiled in 1·5 L laboratory silos with whole‐crop wheat as mixtures of 0, 0·25, 0·50, 0·75 and 1·00 of fresh weight (FW). Silages were ensiled (i) without additive, and (ii) with formic acid (FA) (4 L t−1) or (iii) an inoculant (Lactobacillus plantarum, 106 colony‐forming units g−1 FW) as additives. The concentrations of water‐soluble carbohydrates in herbage of whole‐crop FB, FP, CV and wheat were 93, 157, 67 and 114 g kg−1 DM and the buffering capacities were 588, 710, 755 and 429 mEq kg−1 DM respectively. Field bean and FP silages were mainly well preserved with low pH values and moderate fermentation losses, except for FB‐only silage without additive which had a high butyric acid concentration. Common vetch silages had higher pH values and were less well fermented compared to the silages of the other legumes. For all legumes, FA reduced ammonia‐N concentrations more effectively compared to other additive treatments. In conclusion, in FB and FP silages the use of FA or an inoculant, as additives, ensured good preservation up to a proportion of legume in the herbage of 0·75. With all legume silages, and with those containing CV, only FA, as an additive, adequately restricted protein breakdown.
Relationships between expanding pinyon–juniper cover and topography in the central Great Basin, Nevada
Authors: Bradley Bethany A. , Fleishman Erica
Published: February 2008

Aim  Increasing geographical range and density of conifers is a major form of land‐cover change in the western United States, affecting fire frequency, biogeochemistry and possibly biodiversity. However, the extent and magnitude of the change are uncertain. This study aimed to quantify the relationship between changing conifer cover and topography.

Location  The central Great Basin in the state of Nevada, USA.

Methods  We used a series of Landsat Thematic Mapper satellite images from 1986, 1995 and 2005 to map change in pinyon–juniper woodlands (Pinus monophylla, Juniperus spp.) in the montane central Great Basin of Nevada. We derived fractional greenness for each year using spectral mixture analysis and identified all areas with an above average increase in greenness from 1986 to 1995 and 1995 to 2005.

Results  Areas with high fractional greenness in 2005 were most likely to occur at elevations between 2200 and 2600 m a.s.l. Increases in fractional greenness between 1986 and 2005 were most likely to occur at elevations below 2000 m a.s.l. and on south‐facing slopes. However, relationships between elevation and increasing greenness for individual mountain ranges varied considerably from the average trend. Fractional greenness values measured by Landsat suggest that the majority of pinyon–juniper woodlands have not reached their maximum potential tree cover.

Main conclusions  Expansion of pinyon–juniper at low elevations and on south‐facing slopes probably reflects increasing precipitation in the 20th century, higher water use efficiency caused by increasing atmospheric CO2 in the late 20th century and livestock grazing at the interface between shrubland and woodland. Identification of the spatial relationships between changing fractional greenness of pinyon–juniper woodland and topography can inform regional land management and improve projections of long‐term ecosystem change.
The effect of preoperative uncertainty and anxiety on short‐term recovery after elective arthroplasty
Authors: Kagan Ilya , Bar‐Tal Yoram
Published: February 2008

Aims and objectives.  This study examined the effect of preoperative anxiety and uncertainty on short‐term physical and mental recovery after elective arthroplasty.

Background.  Uncertainty and anxiety accompany all medical procedures. Although preoperative uncertainty plays a central role in the development of stress, only a few studies explicitly examine this issue in terms of its impact on postoperative recovery.

Design.  Quazi‐experimental study.

Methods.  Two self‐administered questionnaires were used to collect data, before and five to six days after surgery. Participants (n = 87) admitted for elective arthroplasty completed the study.

Results.  Preoperative anxiety negatively affected postoperative recovery variables and preoperative uncertainty negatively affected mental and physical recovery after surgery. Furthermore, postoperative symptoms were related to the patients’ subjective readiness to be discharged.

Conclusions.  Separately, reduction of preoperative anxiety and uncertainty could have a positive impact on postoperative recovery and on perceived readiness to be discharged.

Relevance to clinical practice.  The unique contribution of each preoperative variable (uncertainty and anxiety) to postoperative recovery emphasizes the need for clinical and educational interventions that separately relieve uncertainty and anxiety.