bluuebunny/crossref_metadata_2025 huggingface dataset:
Sf‐Caspase‐1‐repressed stable cells: resistance to apoptosis and augmentation of recombinant protein production
Authors: Lin Chih‐Chien , Hsu John T.‐A. , Huang Kai‐Ling , Tang Hung‐Kuan , Shu Chih‐Wen , Lai Yiu‐Kay
Published: August 2007

Sf‐Caspase‐1 [Spodoptera frugiperda (fall armyworm) caspase‐1] is the most studied effector caspase of Lepidoptera and its activation may lead cells to apoptosis (programmed cell death) when under UV irradiation or baculovirus infection. In the present study, we repressed the expression of Sf‐caspase‐1 in Sf9 (S. frugiperda 9) cells using constitutive RNA interference, and evaluated the effects of stress responses and the production of proteins in recombinant baculovirus‐infected cells. The Sf‐caspase‐1‐repressed stable cells, Sf9/pIBdsCasp‐1 and Sf9/pIBdsCasp‐2, showed a significant increase in resistance to UV‐ and baculovirus‐induced apoptosis. These cells produced higher levels of both intracellular (luciferase) and extracellular [SEAP (secreted alkaline phosphatase)] recombinant proteins than the parental cells when infected with recombinant baculovirus. Thus Sf‐caspase‐1‐repressed stable cells have a greater ability to adapt to various culture conditions, and also to provide the benefits of high‐level protein production.
The diverse biofunctions of LIM domain proteins: determined by subcellular localization and protein—protein interaction
Authors: Zheng Quanhui , Zhao Yong
Published: August 2007

The LIM domain is a cysteine‐ and histidine‐rich motif that has been proposed to direct protein—protein interactions. A diverse group of proteins containing LIM domains have been identified, which display various functions including gene regulation and cell fate determination, tumour formation and cytoskeleton organization. LIM domain proteins are distributed in both the nucleus and the cytoplasm, and they exert their functions through interactions with various protein partners.
A trilinear method for finding null points in a three-dimensional vector space
Authors: Haynes A. L. , Parnell C. E.
Published: August 2007

Null points are important locations in vector fields, such as a magnetic field. A new technique (a trilinear method for finding null points) is presented for finding null points over a large grid of points, such as those derived from a numerical experiment. The method was designed so that the null points found would agree with any field lines traced using the commonly used trilinear interpolation. It is split into three parts: reduction, analysis, and positioning, which, when combined, provide an efficient means of locating null points to a user-defined subgrid accuracy. We compare the results of the trilinear method with that of a method based on the Poincaré index, and discuss the accuracy and limitations of both methods.
Do coupling exciton and oscillation of electron-hole pair exist in neutral and charged π-dimeric quinquethiophenes?
Authors: Sun Mengtao , Liu Liwei , Ding Yong , Xu Hongxing
Published: August 2007

Optical physical properties of neutral and charged quinquethiophene monomer, and neutral and cationic π-dimeric quinquethiophenes were investigated with density functional theory as well as the two dimensional (2D) site (transition density matrix) and three dimensional (3D) cube (transition density and charge difference density) representations, stimulated by the recent experimental report [T. Sakai et al., J. Am. Chem. Soc. 127, 8082 (2005)]. Transition density shows the orientation and strength of the transition dipole moment of neutral and charged quinquethiophene monomer, and charge difference density reveals the orientation and result of the charge transfer in neutral and charged quinquethiophene monomer. To study if coupling exciton and oscillation of electron-hole pair exist in neutral and cationic π-dimeric quinquethiophenes, the coupling constants J (coupling exciton of electron-hole pair) and K (coupling oscillation of electron-hole pair) were introduced to the exciton coordinate and momentum operators, respectively, and the 2D and 3D analysis methods were further developed by extending our previous theoretical methods [M. T. Sun, J. Chem. Phys. 124, 054903 (2006)]. With the new developed 2D and 3D analysis methods, we investigated the excited state properties of neutral and cationic π-dimeric quinquethiophenes, especially on the coupling exciton and oscillation of electron-hole pair between monomers. The 2D results show that there is neither coupling exciton (J=0) nor oscillation (K=0) of electron-hole pair in neutral π-dimeric quinquethiophenes. For some excited states of cationic π-dimeric quinquethiophenes, there is no coupling exciton (J=0), but there is coupling oscillation (K≠0); while for some excited states, there are both coupling exciton and coupling oscillator simultaneously (J≠0 and K≠0). The strength of transition dipole moments of π-dimeric quinquethiophenes were interpreted with 3D transition density, which reveals the orientations of their two subtransition dipole moments. The 3D charge transition density reveals the orientation and result of intermonomer and/or intramonomer charge transfer. The calculated results reveal that excited state properties of neutral π-dimeric quinquethiophene are significantly different from those of the cationic π-dimeric quinquethiophenes.
Large-eddy simulations of the turbulent Hartmann flow close to the transitional regime
Authors: Sarris I. E. , Kassinos S. C. , Carati D.
Published: August 2007

A series of large-eddy simulations (LES) of turbulent and transitional channel flows of a conductive fluid under the effect of a uniform magnetic field applied in the wall-normal direction, usually referred to as Hartmann flows, are performed using the dynamic Smagorinsky model. The flow is characterized by the hydrodynamic Reynolds number Re and the Hartmann number Ha that is related to the strength of the external magnetic field. Previous measurements and works on stability analysis have shown that a critical modified Reynolds number, based on the Hartmann layer thickness R=Re∕Ha, exists at approximately R=380. Here, the LES are used to investigate the laminarization of flow when decreasing R. Also, similarities of the turbulent flows are explored for different values of Re and Ha but the same values of R or of the interaction parameter N=Ha2∕Re. The LES confirm that R is the relevant parameter that describes the transition and a critical Reynolds number for relaminarization is observed at R≈500. However, for turbulent flows at moderate values of the Ha and Re as considered in this study, the similarity with respect to N appears to be better than for R, especially for the first order statistics. Finally, the importance of the dynamic Smagorinsky model as the Hartmann number increases is discussed.
Evaluation of electronic correlation contributions for optical tensors of large systems using the incremental scheme
Authors: Yang Jun , Dolg Michael
Published: August 2007

A new method is developed to calculate the optical tensors of large systems based on available wave function correlation approaches (e.g., the coupled cluster ansatz) in the framework of the incremental scheme. The convergence behaviors of static first- and second-order polarizabilities with respect to the order of the incremental expansion are examined and discussed for the model system Ga4As4H18. The many-body increments of optical tensors originate from the dipole-dipole coupling effects and the corresponding contributions to the incremental expansion are compared among local domains with different distances and orientations. The weight factors for increments of optical tensors are found to be tensorial in accordance with the structural symmetry as well as the polarization and the external electric field directions. The long-term goal of the proposed approach is to incorporate the sophisticated molecular correlation methods into the accurate wave function calculation of optical properties of large compounds or even crystals.
Elucidation of conformational hysteresis on a giant DNA
Authors: Shew Chwen-Yang , Higuchi Yuji , Yoshikawa Kenichi
Published: August 2007

The conformational behavior of a giant DNA mediated by condensing agents in the bulk solution has been investigated through experimental and theoretical approaches. Experimentally, a pronounced conformational hysteresis is observed for folding and unfolding processes, by increasing and decreasing the concentration of condensing agent (polyethylene glycol) (PEG), respectively. To elucidate the observed hysteresis, a semiflexible chain model is studied by using Monte Carlo simulations for the coil-globule transition. In the simulations, the hysteresis loop emerges for stiff enough chains, indicating distinct pathways for folding and unfolding processes. Also, our results show that globular state is thermodynamically more stable than coiled state in the hysteresis loop. Our findings suggest that increasing chain stiffness may reduce the chain conformations relevant to the folding pathway, which impedes the folding process.
Phase equilibria and interfacial tension of fluids confined in narrow pores
Authors: Hamada Yoshinobu , Koga Kenichiro , Tanaka Hideki
Published: August 2007

Correlation between phase behaviors of a Lennard-Jones fluid in and outside a pore is examined over wide thermodynamic conditions by grand canonical Monte Carlo simulations. A pressure tensor component of the confined fluid, a variable controllable in simulation but usually uncontrollable in experiment, is related with the pressure of a bulk homogeneous system in equilibrium with the confined system. Effects of the pore dimensionality, size, and attractive potential on the correlations between thermodynamic properties of the confined and bulk systems are clarified. A fluid-wall interfacial tension defined as an excess grand potential is evaluated as a function of the pore size. It is found that the tension decreases linearly with the inverse of the pore diameter or width.
Current injection and transport in polyfluorene
Authors: Yang Chieh-Kai , Yang Chia-Ming , Liao Hua-Hsien , Horng Sheng-Fu , Meng Hsin-Fei
Published: August 2007

A comprehensive numerical model is established for the electrical processes in a sandwich organic semiconductor device with high carrier injection barrier. The charge injection at the anode interface with 0.8eV energy barrier is dominated by the hopping among the gap states of the semiconductor caused by disorders. The Ohmic behavior at low voltage is demonstrated to be not due to the background doping but the filaments formed by conductive clusters. In bipolar devices with low work function cathode it is shown that near the anode the electron traps significantly enhance hole injection through Fowler-Nordheim tunneling, resulting in rapid increases of the hole carrier and current in comparison with the hole-only devices.
Tensor product approximation with optimal rank in quantum chemistry
Authors: Chinnamsetty Sambasiva Rao , Espig Mike , Khoromskij Boris N. , Hackbusch Wolfgang , Flad Heinz-Jürgen
Published: August 2007

Tensor product decompositions with optimal separation rank provide an interesting alternative to traditional Gaussian-type basis functions in electronic structure calculations. We discuss various applications for a new compression algorithm, based on the Newton method, which provides for a given tensor the optimal tensor product or so-called best separable approximation for fixed Kronecker rank. In combination with a stable quadrature scheme for the Coulomb interaction, tensor product formats enable an efficient evaluation of Coulomb integrals. This is demonstrated by means of best separable approximations for the electron density and Hartree potential of small molecules, where individual components of the tensor product can be efficiently represented in a wavelet basis. We present a fairly detailed numerical analysis, which provides the basis for further improvements of this novel approach. Our results suggest a broad range of applications within density fitting schemes, which have been recently successfully applied in quantum chemistry.
Fluorescence excitation spectra of the bΠu1, b′Σu+1, cnΠu1, and cn′Σu+1 states of N2 in the 80–100nm region
Authors: Wu C. Y. Robert , Fung Hok-Sum , Chang Kuang-Yu , Singh Thounaojam S. , Mu Xiao-Lan , Nee Jan B. , Chiang Su-Yu , Judge D. L.
Published: August 2007

Fluorescence excitation spectra produced through photoexcitation of N2 using synchrotron radiation in the spectral region between 80 and 100nm have been studied. Two broadband detectors were employed to simultaneously monitor fluorescence in the 115–320nm and 300–700nm regions, respectively. The peaks in the vacuum ultraviolet fluorescence excitation spectra are found to correspond to excitation of absorption transitions from the ground electronic state to the bΠu1, b′Σu+1, cnΠu1 (with n=4–8), cn′Σu+1 (with n=5–9), and c4′(v′)Σu+1 (with v′=0–8) states of N2. The relative fluorescence production cross sections for the observed peaks are determined. No fluorescence has been produced through excitation of the most dominating absorption features of the b-X transition except for the (1,0), (5,0), (6,0), and (7,0) bands, in excellent agreement with recent lifetime measurements and theoretical calculations. Fluorescence peaks, which correlate with the long vibrational progressions of the c4′Σu+1 (with v′=0–8) and the b′Σu+1 (with v′ up to 19), have been observed. The present results provide important information for further unraveling of complicated and intriguing interactions among the excited electronic states of N2. Furthermore, solar photon excitation of N2 leading to the production of c4′(0) may provide useful data required for evaluating and analyzing dayglow models relevant to the interpretation of c4′(0) in the atmospheres of Earth, Jupiter, Saturn, Titan, and Triton.
Effects of nanotube alignment and measurement direction on percolation resistivity in single-walled carbon nanotube films
Authors: Behnam Ashkan , Guo Jing , Ural Ant
Published: August 2007

We have used Monte Carlo simulations to study the effects of nanotube alignment and measurement direction on the resistivity in single-walled carbon nanotube films. These films consist of multiple layers of conductive nanotube networks with percolative transport as the dominant conduction mechanism. We find that minimum resistivity occurs for a partially aligned rather than a perfectly aligned nanotube film. When nanotubes are strongly aligned, the film resistivity becomes highly dependent on the measurement direction. We also find that aligning the nanotubes too strongly or measuring the resistivity in a direction which is very different from the alignment direction causes the film to approach the percolation threshold, as evidenced by the inverse power law increase in resistivity. Furthermore, the location of the resistivity minimum and the values of the inverse power law critical exponents are not universal, but depend strongly on other nanotube and device parameters. To illustrate this explicitly, we have studied the effect of three parameters, namely, nanotube length, nanotube density per layer, and device length on the scaling of nanotube film resistivity with nanotube alignment and measurement direction. We find that longer nanotubes, denser films, and shorter device lengths decrease the alignment critical exponent and the alignment angle at which minimum resistivity occurs, but increase the measurement direction critical exponent. However, the amount of increase or decrease in the critical exponents or the minima locations is different for each parameter. We explain these results by simple physical and geometrical arguments. Characterizing and understanding the effects of alignment and measurement direction on the percolation resistivity in films and composites made up of one-dimensional conductors, such as nanotubes, give valuable insights into the optimal way to arrange these nanomaterials for potential applications in optoelectronics, sensors, and flexible microelectronics.
Comment on “Magnetic field effects on gas discharge plasmas” [Phys. Plasmas 13, 063511 (2006)]
Authors: Simon Albert
Published: August 2007

In their paper, the authors assume ambipolar diffusion across a magnetic field. This is not true in a strong field and in most practical applications. The actual ion transport may be much larger and entirely different from that calculated by the authors.
Extraordinary Hall effect in Co-Pd bilayers
Authors: Shaya O. , Karpovski M. , Gerber A.
Published: August 2007

This work is devoted to the study of the extraordinary Hall effect (EHE) in ferromagnet/normal-metal bilayers with a particular focus on surface and interface scattering. Systems selected are Co monolayers and series of Co-Pd bilayers, differing in the order of the materials deposition and the total and relative thicknesses. The extraordinary Hall coefficient was calculated using two models which we named “black box” and “two channels,” and compared them with Co monolayers. The EHE coefficient of bilayers with uniform Co layers was found to be independent of Pd thickness. Furthermore, contribution of Co-Pd interfaces to the effect is significantly weaker than Co-vacuum interface. In bilayers, as in monolayers, we find a linear correlation between the surface scattering contributions to resistivity and the EHE, which indicates that the skew scattering mechanism is the dominant source of the effect in these films.
Mode-specific tunneling dynamics in the ground electronic state of tropolone
Authors: Murdock Daniel , Burns Lori A. , Vaccaro Patrick H.
Published: August 2007

The mode specificity of proton-transfer dynamics in the ground electronic state (X̃A11) of tropolone has been explored at near-rotational resolution by implementing a fully coherent variant of stimulated emission pumping within the framework of two-color resonant four-wave mixing spectroscopy. Three low-lying (Evib≈550–750cm−1) vibrational features, assigned to ν30(a1), ν32(b2), and ν31ν38(a1), have been interrogated under ambient, bulk-gas conditions, with term energies determined for the symmetric and antisymmetric (tunneling) components of each enabling the attendant tunneling-induced bifurcations of 1.070(9), 0.61(3), and 0.07(2)cm−1 to be extracted. The dependence of tunneling rate (or hydron migration efficiency) on vibrational motion is discussed in terms of corresponding atomic displacements and permutation-inversion symmetries for the tropolone skeleton.
Ab initio study of single-molecule rotation switch based on nonequilibrium Green’s function theory
Authors: Liang Y. Y. , Jiang F. , Zhou Y. X. , Chen H. , Note R. , Mizuseki H. , Kawazoe Y.
Published: August 2007

The bistable molecular switches have been studied theoretically based on the first-principles calculation. The geometry structures of the switches studied in this paper can be triggered between two symmetrical structures by using an external applied electric field. I-V characteristic curves of the different molecule configurations have been calculated, and distinguishability of these characteristic curves indicates a switching behavior, the performance of which can be improved significantly by some suitable donors and acceptors.
Ultrafast anisotropy dynamics of water molecules dissolved in acetonitrile
Authors: Cringus Dan , Jansen Thomas l. C. , Pshenichnikov Maxim S. , Wiersma Douwe A.
Published: August 2007

Infrared pump-probe experiments are performed on isolated H2O molecules diluted in acetonitrile in the spectral region of the OH stretching vibration. The large separation between water molecules excludes intermolecular interactions, while acetonitrile as a solvent provides substantial hydrogen bonding. Intramolecular coupling between symmetric and asymmetric modes results in the anisotropy decay to the frequency-dependent values of ∼0–0.2 with a 0.2ps time constant. The experimental data are consistent with a theoretical model that includes intramolecular coupling, anharmonicity, and environmental fluctuations. Our results demonstrate that intramolecular processes are essential for the H2O stretching mode relaxation and therefore can compete with the intermolecular energy transfer in bulk water.
Surface plasmon polariton mediated energy transfer in organic photovoltaic devices
Authors: Heidel T. D. , Mapel J. K. , Singh M. , Celebi K. , Baldo M. A.
Published: August 2007

The performance of a phthalocyanine-based photovoltaic is boosted in the absorption gap between the phthalocyanine Q and Soret bands. Light absorption is decoupled from exciton diffusion using a light absorbing “antenna” layer external to the conventional charge generating layers. Radiation absorbed by the antenna is transferred into the charge generating layers via surface plasmon polaritons in an interfacial thin silver contact. The peak efficiency of energy transfer is measured to be at least (51±10)%.
Tuneable visible resonances in crescent shaped nano-split-ring resonators
Authors: Clark A. W. , Sheridan A. K. , Glidle A. , Cumming D. R. S. , Cooper J. M.
Published: August 2007

Electron beam lithography was used to fabricate gold crescent shaped split-ring resonators with 30nm minimum feature size. By varying the crescent’s arc length over a range of nanometer-scale dimensions the authors demonstrate the tuneability of visible resonances within such structures. Results, which correlate closely with those predicted using finite-difference time-domain modeling, open the way for these devices to be used in near-field biological sensing.
High-pressure phase transition observed in barium hydride
Authors: Smith Jesse S. , Desgreniers Serge , Tse John S. , Klug Dennis D.
Published: August 2007

The pressure-dependent structural and vibrational properties of barium hydride have been studied up to 22 GPa at room temperature by means of powder x-ray diffraction, Raman spectroscopy, and first-principles calculations. At ambient conditions, BaH2 crystallizes in the cotunnite structure (Pnma). A reversible, first-order structural phase transition is observed at 1.6 GPa. The high-pressure phase can be indexed by a hexagonal unit cell with a proposed Ni2In structure (P63∕mmc), with the Ba and H atoms in special positions. The experimental volume compression of the high-pressure phase yields an isothermal bulk modulus B0=24(1) GPa (B0′ fixed at 4.13). This compares favorably with the results of the first-principles calculations, which reproduce the first-order nature of the transition. The relevance of these results is discussed in the contexts of metal hydrides in particular and ionic AX2(A=metal) compounds in general.
Arsenic-induced etched nanovoids on GaSb (100)
Authors: Huang S. H. , Balakrishnan G. , Mehta M. , Dawson L. R. , Huffaker D. L. , Li P.
Published: August 2007

We describe in situ nanoscale etch-pit formation on GaSb (100) surfaces as a result of exposure to an As2 flux in molecular beam epitaxy. The pits form as a result of an Sb-displacement reaction that occurs between the GaSb substrate and the impinging As adatoms. The nanoscale surface features are highly crystallographic with a strong preference for {111} planes, similar to other etching techniques. Nanopit dimensions and density increase with As exposure time. For the 60 s exposure analyzed in this article, the pits vary in both size and shape with average dimensions ∼25 nm wide and 50–80 nm long and 10–70 nm deep, with density of ∼1×109/cm2. Subsequent GaAs overgrowth proceeds by a coalescence mechanism leaving interfacial nanovoids and finally highly planar bulk layers.
Nitrogen-related recombination mechanisms in p-type ZnO films grown by plasma-assisted molecular beam epitaxy
Authors: Sun J. W. , Lu Y. M. , Liu Y. C. , Shen D. Z. , Zhang Z. Z. , Yao B. , Li B. H. , Zhang J. Y. , Zhao D. X. , Fan X. W.
Published: August 2007

The recombination mechanisms of nitrogen-related emissions in p-type ZnO films were investigated by photoluminescence (PL) measurements. The enhanced peak at 3.260 eV was confirmed as a donor-acceptor pair (DAP) transition and the emission around 3.310 eV was assigned to the free electron to acceptor (FA) recombination by studying the temperature evolution of DAP and FA luminescence, calculating the energy level of the corresponding nitrogen acceptor, and measuring the decay time of DAP transition. By comparing the PL spectra of the samples with various hole concentrations, it can be found that as the hole concentration increases, the DAP peak significantly dominates the spectra. In addition, the acceptor binding energy is estimated to be about 120 meV from the FA transition, which is in good agreement with the value calculated by a hydrogenic acceptor model.
Theory of volume phase transitions of side-chain liquid crystalline gels
Authors: Matsuyama Akihiko
Published: August 2007

We present a mean field theory to describe volume phase transitions of side-chain liquid crystalline gels. Three different uniaxial nematic phases (N1, N2, and N3) are defined by using orientational order parameter Sm of side-chain liquid crystals (mesogens) and Sb of backbone chains. We derive the free energy for the three nematic phases of side-chain liquid crystalline gels dissolved in isotropic solvents and calculate the swelling curve of the gel, the order parameters of a backbone chain and of side-chain liquid crystals, and the deformation of the gel as a function of temperature and an electric field. We find isotropic-nematic (N1, N2, and N3) and N1N2 phase transitions of the gels, depending on the interaction between a backbone chain and a side-chain liquid crystal.
Influence of the flow on the orientational dynamics induced by temperature gradient in nematic hybrid-oriented cells
Authors: Zakharov A. V. , Vakulenko A. A.
Published: August 2007

The numerical study of the system of hydrodynamic equations that include the director motion, fluid flow, and the temperature field redistribution across the hybrid-oriented liquid crystal (LC) cell under influence of the temperature gradient has been investigated. Calculations show that the horizontal LC layer being initially in the rest, if heated both from below or above, due to the temperature gradient, starts moving in the horizontal direction. It has been shown that the magnitude and direction of the hydrodynamic flow, excited by the temperature gradient, influence both the direction of the heat flow and the character of the preferred anchoring of the average molecular direction to the restricted surfaces. The role of the hydrodynamic flow in the relaxation processes, for a number of dynamic regime in 4-n-pentyl-4′-cyanobiphenyl hybrid-oriented LC cell, also has been investigated.
Resonant optical in-well pumping of an (AlGaIn)(AsSb)-based vertical-external-cavity surface-emitting laser emitting at 2.35μm
Authors: Schulz Nicola , Rattunde Marcel , Ritzenthaler Christian , Rösener Benno , Manz Christian , Köhler Klaus , Wagner Joachim , Brauch Uwe
Published: August 2007

The semiconductor heterostructure design and lasing characteristics of an optically in-well pumped (AlGaIn)(AsSb)-based vertical-external-cavity surface-emitting laser (VECSEL) emitting at 2.35μm are presented. The pump absorption in the active quantum wells at 1.96μm has been enhanced by a higher-order microcavity resonance. VECSEL operation in-well pumped by a thulium-doped fiber laser has been demonstrated. Compared to a VECSEL barrier pumped at 1μm, the in-well pumped device reaches a significantly higher power efficiency, and thus a higher output power at a given pump power, due to the smaller quantum deficit and hence reduced internal heat generation. Using an intracavity SiC heat spreader, a cw output power in excess of 3W has been achieved at a heat sink temperature of −15°C, and still more than 2W at +15°C.
Controlling bistability in tapping-mode atomic force microscopy using dual-frequency excitation
Authors: Thota Phanikrishna , MacLaren Scott , Dankowicz Harry
Published: August 2007

This letter discusses an experimental method to suppress spontaneous transitions between low- and high-amplitude oscillatory responses in tapping-mode atomic force microscopy in the absence of feedback control. Here, the cantilever is excited at two frequencies and the dynamic force curves for different excitation amplitudes are recorded. Experimental observations of the dual-frequency excitation strategy are reported for three different cantilevers. These suggest that such transitions may indeed be eliminated from a region of interest of separations between the sample surface and the average position of the cantilever support even with relatively small secondary excitation amplitudes.
Spatial-frequency multiplication via absorbance modulation
Authors: Tsai Hsin-Yu , Wallraff Gregory M. , Menon Rajesh
Published: August 2007

The absorbance of a thin film of photochromic material can be reversibly modified by exposure to two different wavelengths, λ1 and λ2. When such a film is illuminated by both wavelengths simultaneously, and the longer wavelength λ2 possesses a node in its intensity distribution, then the absorbance of the layer can be made high except at an arbitrarily small region near the node. By exploiting the large nonlinearity introduced by this mechanism, combined with the reversibility of the absorbance of the photochromic layer, the authors demonstrate that spatial frequencies larger than those present in incident intensity distributions may be generated. They show photoresist exposures to demonstrate this technique.
Giant Kerr nonlinearities and solitons in a crystal of molecular magnets
Authors: Wu Ying , Yang Xiaoxue
Published: August 2007

The authors show the formation of microwave solitons in a crystal of molecular magnets via an electromagnetically induced transparency and have the giant cross-phase modulation phase shifts with the advantages of low pump powers, low absorptions, high sensitivities, and certain frequency tunability.
Effect of crystallinity and nonstoichiometric region on dielectric properties of SrTiO3 films formed on Ru
Authors: Kim Ja-Yong , Ahn Ji-Hoon , Kang Sang-Won , Kim Jin-Hyock , Roh Jae-Sung
Published: August 2007

The dielectric constant depending on the film thickness for SrTiO3 films formed on Ru was investigated after an annealing step at 600°C, which shows that the dielectric constant increased abruptly with the film thickness up to 20nm and then increased slightly, remaining relatively constant at a value of about 65. The abrupt increase was due to the crystallinity of SrTiO3 films. On the other hand, the slight increase was related to the existence of nonstoichiometric region near the interface of SrTiO3 film and Ru, which was intermixed with SrTiO3 and Ti–O phases having an equivalent oxide thickness over 0.32nm.
Mechanism of surface conduction in the vicinity of Schottky gates on AlGaN∕GaN heterostructures
Authors: Kotani Junji , Tajima Masafumi , Kasai Seiya , Hashizume Tamotsu
Published: August 2007

Lateral surface leakage current (Is) on an AlGaN∕GaN heterostructure was systematically investigated by using a two-parallel gate structure with a gap distance (LGG) of 200nm–5μm. The surface current Is systematically increased as LGG decreased. A simple resistive layer conduction that should show 1∕LGG dependence failed to account for the drastic increase in Is when LGG was reduced to less than 1μm. However, no dependence on LGG was seen in vertical current that flows in the Schottky interface. The Is showed a clear temperature dependence proportional to exp(−T−1∕3), indicating two-dimensional variable-range hopping through high-density surface electronic states in AlGaN. A pronounced reduction in surface current of almost four orders of magnitude was observed in a sample with SiNx passivation.
Correlating electrical resistance to growth conditions for multiwalled carbon nanotubes
Authors: Lan Chun , Amama Placidus B. , Fisher Timothy S. , Reifenberger Ronald G.
Published: August 2007

A correlation between growth temperature and electrical resistance of multiwalled carbon nanotubes (MWNTs) has been established by measuring the resistance of individual MWNTs grown by microwave plasma-enhanced chemical vapor deposition (PECVD) at 800, 900, and 950°C. The lowest resistances were obtained mainly from MWNTs grown at 900°C. The MWNT resistance is larger on average at lower (800°C) and higher (950°C) growth temperatures. The resistance of MWNTs correlated well with other MWNT quality indices obtained from Raman spectra. This study identifies a temperature window for growing higher-quality MWNTs with fewer defects and lower resistance by PECVD.
Capacitive micromachined ultrasonic transducers for chemical detection in nitrogen
Authors: Park K. K. , Lee H. J. , Yaralioglu G. G. , Ergun A. S. , Oralkan Ö. , Kupnik M. , Quate C. F. , Khuri-Yakub B. T. , Braun T. , Ramseyer J.-P. , Lang H. P. , Hegner M. , Gerber Ch. , Gimzewski J. K.
Published: August 2007

The authors present the prototype of a chemical sensor using a capacitive micromachined ultrasonic transducer array. Each element in the array consists of a large number of resonating membranes connected in parallel. A five-channel oscillator circuit operates at the resonant frequency around 6MHz in this prototype. The surface of the elements in the array is coated by polymers such as polyallylamine hydrochloride, polyethylene glycol, and polyvinyl alcohol to detect different chemicals. By measuring shift in oscillation frequencies due to the mass-loading effect, analytes, e.g., water and isopropanol, with concentrations around 20ppbv (parts per 109 by volume) range can be detected.
High brightness stable white and yellow light-emitting diodes from ambipolar polyspirofluorenes with high charge carrier mobility
Authors: Peng Kang-Yung , Huang Chih-Wei , Liu Ching-Yang , Chen Show-An
Published: August 2007

We have used two polyspirofluorenes, spirodiethylhexyloxylpolyfluorene (spiro-diEHPF) and triphenylamine-grafted spirodiethylhexyloxylpolyfluorene (spiro-TPA50-diEHPF), which exhibit rather high charge mobilities in the order of 10−3–10−4cm2∕Vs. The light-emitting devices with rubrene-doped spiro-diEHPF show maximal luminances of 36 000 and 70000cd∕m2 with maximal efficiencies 3.5 and 9cd∕A for the white and yellow emissions, respectively. For rubrene-doped triphenylamine-grafted polymer, spiro-TPA50-diEHPF, the maximal luminances and efficiencies are 56000cd∕m2 and 9cd∕A for white-emitting devices and 72000cd∕m2 and 14cd∕A for yellow emission. Furthermore, the electroluminescence profiles of the investigated devices show nearly independent of the applied voltages.
Hybrid cross-linkable polymer/sol-gel waveguide modulators with 0.65V half wave voltage at 1550nm
Authors: Enami Y. , Mathine D. , DeRose C. T. , Norwood R. A. , Luo J. , Jen A. K.-Y. , Peyghambarian N.
Published: August 2007

The authors report on a hybrid cross-linked electro-optic (EO) polymer/sol-gel Mach-Zehnder waveguide modulator with a half wave voltage (Vπ) of 0.65V at 1550nm. The low Vπ was achieved by a design that (1) combines both physical vertical tapers in the sol-gel core and photobleached index tapers in the EO polymer and (2) reduces the thickness of the device to 8μm. These combined physical and index tapers result in improved optical mode confinement in the EO polymer with low adiabatic optical transition loss. The reduced thickness results in a larger field across the EO polymer for the same voltage, enabling a lower Vπ.
Corporeal Remains: Vulnerability, Proximity, and Living on after the End of the World
Authors: Harrison Paul
Published: August 2007

This paper offers a sustained reflection on the nature of corporeal vulnerability as an inherent and noneliminable aspect of corporeal existence. One of the many remarkable things about the recent interest in embodiment, emotion, practice, and performance, in the body-in-action, in the social sciences is the general lack of thought that has been given to the fact of vulnerability. The paper suggests that thinking through the nature of vulnerability could have a considerable effect on how we think about embodiment as well as on wider processes of subjectification, signification, and sociality. However, because of the persistence of a primary role being given to intentional or auto-affective action in the theorisation of embodiment across a number of theoretical perspectives, vulnerability remains largely unthought of within much current work on the body within Anglo-American social science. Drawing on the writing of Emmanuel Levinas and reflecting on experiences of corporeal expropriation such as insomnia and exhaustion, I suggest how we may begin to think sensibility and the sensuous beyond their almost exclusive interpretation in terms of comprehension, purpose, or intention while retaining the irreducibility of corporeal life to a matter of social construction or contextual epiphenomenon. Thus, the paper develops an account of corporeal life as inherently susceptible, receptive, exposed, as inherently open beyond its capacities, and reflects on the implications of this realisation for thinking about the genesis of meaning and signification and the social relation.
Investigating Differences in Electoral Turnout: The Influence of Ward-Level Context on Participation in Local and Parliamentary Elections in Britain
Authors: Orford Scott , Rallings Colin , Thrasher Michael , Borisyuk Galina
Published: August 2007

Electoral turnout is an important measure of the health of a liberal democracy. Although research identifies factors that affect electoral participation, we still know little about how electors in a specific location respond to opportunities to vote for different kinds of local, national, and supranational institutions. This paper addresses this issue by analysing the relative rates of turnout at local, parliamentary, and European elections within three time periods for the London Borough of Brent. It uses turnout data for individual polling districts to investigate whether relative differences in turnout are sustained across time, whether polling districts perform consistently or not for different types of elections and whether variations in turnout are related to marginality. The results indicate that turnout at different types of elections is not stable even within tightly constrained time periods and that there are statistically significant differences in the relative rates of participation between polling districts. Geographically, the differences in relative rates of turnout appear to be spatially clustered, particularly with respect to local elections and this may reflect an increase in the concentration of party campaigning in marginal wards.
Destination Choice of the 1995–2000 Immigrants to Japan: Salient Features and Multivariate Explanation
Authors: Liaw Kao-Lee , Ishikawa Yoshitaka
Published: August 2007

The purpose of this paper is to identify the salient features of the destination choices made by new immigrants who entered Japan in the 1995–2000 period, and to provide a multivariate explanation for their choice behaviors. The salient features can be summarized as follows; first, destination-choice patterns differed markedly by ethnicity; second, the higher the educational qualification of the immigrants, the greater the attraction of the Tokyo prefecture and the less dispersed the destination-choice pattern; and third, among female immigrants, those with the household status of daughter in law were more prone to go to the Tohoku region, where the maintenance of the traditional stem-family system was a serious concern. Our multivariate analysis has revealed that the destination choices made by the new immigrants were indeed subject to the selective effects of labor-market conditions, the distributions of coethnics, and the spatial patterns of marital opportunities in theoretically meaningful ways, and that labor-market conditions were most important, whereas marital opportunities were least important.
Social and Environmental Shareholder Activism in the Public Spotlight: US Corporate Annual Meetings, Campaign Strategies, and Environmental Performance, 2001–04
Authors: Clark Gordon L , Salo James , Hebb Tessa
Published: August 2007

Held in abeyance by the Cold War and the preeminence of the nation-state over the past fifty years, the legitimacy of the corporation is once again in dispute. New kinds of private agencies and social actors have emerged to raise questions and, in some cases, intervene directly in the governance of major corporations. Often, corporate engagement is out of the public view—being a conversation amongst financial elites about common interests. In other cases, however, shareholder activism is a public affair played out in the full glare of the media at annual general meetings. In this paper social activists' corporate engagement strategies are evaluated utilizing three proprietary databases which enable analysis of the patterns of activists' shareholder resolutions with respect to the financial structure and environmental performance of target corporations. An analytical framework is introduced, referencing two models of the firm, the nature of corporate assets (tangible and intangible), and public expectations of corporate performance. Utilizing Interfaith Center for Corporate Responsibility data on social activists' shareholder resolutions it is shown that these types of resolutions can be differentiated according to the nature and volume of activists' resolutions and the motive forces driving intervention. It is also shown that, for all the differences between institutional investors and social activists, they may share the same approach to realizing shareholder value depending on the nature of the corporation.
Rescaling Employment Relations: Key Outcomes of Change in the Privatised Rail Industry
Authors: MacKinnon Danny , Cumbers Andrew , Shaw Jon
Published: August 2007

The past decade has witnessed a revival of interest in the role of labour in political and economic restructuring. Following a period in the 1980s and early 1990s when trade unions and employees were routinely portrayed as passive victims of corporate restructuring, the past ten years have seen a resurgence of work by geographers highlighting the continued agency of labour. Despite this ‘new labour geography’, however, there has been little empirical research examining the uneven development of employment relations at a broad industry level. We address this issue by examining the changing geography of employment regulation in the UK's privatised rail industry. A major shift in the scale at which industrial relations are organised has taken place under privatisation, away from national collective bargaining to a system of localised company bargaining. On the basis of secondary data gathered from industry sources, we provide an initial assessment of key outcomes of employment change in the rail industry. Our analysis indicates that considerable disparities in pay and conditions exist between different groups of workers, companies, and regions, although these are perhaps less extreme than suggested by the unions. In addition, the number of industrial disputes has escalated in the aftermath of privatisation. Moreover, instead of the set piece national strikes that took place in the nationalised industry, the majority of this strike action has been conducted against particular operators at the local and regional scales, reflecting the logic of company-level bargaining. At the same time, the membership of the three main unions has actually increased in recent years against a backdrop of long-term decline, suggesting that the decentralisation of collective bargaining presents unions with opportunities as well as challenges.
Modeling Spatial Dimensions of Housing Prices in Milwaukee, WI
Authors: Yu Danlin , Wei Yehua Dennis , Wu Changshan
Published: August 2007

In this study we investigate spatial dimensions of housing-market dynamics in the City of Milwaukee by modeling the determinants of housing prices. From the 2003 Master Property data file of the city, two sets of owner-occupied single-family houses were randomly selected (one to construct the models, and the other to rest the models). Besides conventional housing attributes, remote-sensing information, in particular the fractions of soil and impervious surface representing degraded neighborhood environment conditions, is added to improve the model. Spatial regression and geographically weighted regression approaches are employed to examine spatial dependence and heterogeneity. Results reveal that these spatial models tend to perform better, especially in terms of model performance and predictive accuracy, than the ordinary least squares estimates.
Judgments of Visually Perceived Eye Level (VPEL) in Outdoor Scenes: Effects of Slope and Height
Authors: O'Shea Robert P , Ross Helen E
Published: August 2007

When one looks up a hill from below, its peak appears lower than it is; when one looks at a hill across a valley from another peak, the peak of that hill appears higher than it is. These illusions have sometimes been explained by assuming that the subjective horizontal is assimilated to the nearby slope: when looking up a slope, the subjective horizontal is raised, diminishing the height of the peak above the subjective horizontal, and making the peak appear lower than it is. When looking down a slope towards another hill, the subjective horizontal is lowered, increasing the height of that hill above the subjective horizontal, and making its peak appear higher than it is. To determine subjective horizontals we measured visually perceived eye levels (VPELs) in 21 real-world scenes on a range of slopes. We found that VPEL indeed assimilates by about 40% to slopes between 7° downhill and 7° uphill. For larger uphill slopes up to 23°, VPEL asymptotes at about 4.5°. For larger downhill slopes, the assimilation of VPEL diminishes, and at 23° is raised by about 1°. These results are consistent with the assimilation explanation of the illusions if we assume that steep downhill slopes lose their effectiveness by being out of view. We also found that VPEL was raised when viewing from a height, in comparison with ground-level views, perhaps because the perceived slope increases with viewing height.
Ambiguity in Pictorial Depth
Authors: Battu Balaraju , Kappers Astrid M L , Koenderink Jan J
Published: August 2007

Pictorial space is the 3-D impression that one obtains when looking ‘into’ a 2-D picture. One is aware of 3-D ‘opaque’ objects. ‘Pictorial reliefs’ are the surfaces of such pictorial objects in ‘pictorial space’. Photographs (or any pictures) do in no way fully specify physical scenes. Rather, any photograph is compatible with an infinite number of possible scenes that may be called ‘metameric scenes’. If pictorial relief is one of these metameric scenes, the response may be considered ‘veridical’. The conventional usage is more restrictive and is indeed inconsistent. Thus the observer has much freedom in arriving at such a ‘veridical’ response. To address this ambiguity, we determined the pictorial reliefs for eight observers, six pictures, and two psychophysical methods. We used ‘methods of cross-sections’ to operationalise pictorial reliefs. We find that linear regression of the depths of relief at corresponding locations in the picture for different observers often lead to very low (even insignificant) R2s. Thus the responses are idiosyncratic to a large degree. Perhaps surprisingly, we also observed that multiple regression of depth and picture coordinates at corresponding locations often lead to very high R2s. Often R2s increased from insignificant up to almost 1. Apparently, to a large extent ‘depth’ is irrelevant as a psychophysical variable, in the sense that it does not uniquely account for the relation of the response to the pictorial structure. This clearly runs counter to the bulk of the literature on pictorial ‘depth perception’. The invariant core of interindividual perception proves to be of an ‘affine’ rather than a Euclidean nature; that is to say, ‘pictorial space’ is not simply the picture plane augmented with a depth dimension.