bluuebunny/crossref_metadata_2025 huggingface dataset:
The west Andaman fault and its influence on the aftershock pattern of the recent megathrust earthquakes in the Andaman‐Sumatra region
Authors: Kamesh Raju K. A. , Murty G. P. S. , Amarnath Dileep , Kumar M. L. Mohan
Published: February 2007

Distinctly different rupture patterns of December 2004 and March 2005 megathrust earthquakes occurred in the Andaman‐Sumatra region suggest strong influence of tectonic and structural elements. We have analysed the shipboard gravity, bathymetry and seismic data across the West Andaman Fault (WAF), a major tectonic feature in the Andaman Sea, to infer the crustal structure and to examine its influence in controlling the aftershock pattern. Our results support the idea of Singh et al. (2005) that WAF forms a lithospheric scale boundary and together with other tectonic elements modulate the occurrence of large earthquakes and their rupture pattern. The active strike‐slip motion along the WAF, presence of backarc spreading coupled with increased obliquity of subduction in the Andaman Sector reduce the probability of occurrence of major or great earthquakes north of 10°N.
Radiation transfer in ocean water: Average penetration depth of a photon flux in a fixed time interval
Authors: Kirk John T. O.
Published: February 2007

It has been shown that for a set of photons emitted, initially as a parallel flux, within the water, the average distance traversed along the original direction by the surviving photons in time interval Δt is = d exp(− bd) or, = d F(b, s, d) where d is cwΔt (cw being the speed of light in water), b is the scattering coefficient, s is the average cosine (or asymmetry factor) of the scattering phase function and F(b, s, d) may be referred to as the penetration function. The average depth traversed in time interval Δt by those photons which are emitted from a thin layer of the ocean at depth z, but not absorbed, is = cwΔtF(b, s, cwΔt) (z) where (z) is the average cosine of the light field at that depth. Computer calculations based on these equations can readily be implemented, and the validity of the calculations has been confirmed by Monte Carlo modeling.
Temporal variations of the atmospheric nitrous oxide concentration and its δ15N and δ18O for the latter half of the 20th century reconstructed from firn air analyses
Authors: Ishijima Kentaro , Sugawara Satoshi , Kawamura Kenji , Hashida Gen , Morimoto Shinji , Murayama Shohei , Aoki Shuji , Nakazawa Takakiyo
Published: February 2007

Histories of atmospheric N2O concentration and its δ15N and δ18O were reconstructed for the period 1952–2001 on the basis of the analyses of firn air collected at the North Greenland Ice Core Project (NGRIP), Greenland, and Dome Fuji and H72, Antarctica. The N2O concentration increased from 290 ppbv in 1952 to 316 ppbv in 2001, which agrees well with the results from atmospheric observations and polar ice core analyses. The δ15N and δ18O showed a secular decrease, the respective values being 8.9 and 21.5‰ in 1952 and 7.0 and 20.5‰ in 2001. Their rates of change also varied, from about −0.02‰ yr−1 in the 1950s to about −0.04‰ yr−1 in 1960–2001 for δ15N, and from about 0‰ yr−1 to −0.02‰ yr−1 for δ18O. The isotopic budgetary calculations using a two‐box model indicated that anthropogenic N2O emission from soils played a main role in the atmospheric N2O increase after industrialization, as well as that the average isotopic ratio of anthropogenic N2O has potentially been changed temporally.
Measurement of HO2NO2 in the free troposphere during the Intercontinental Chemical Transport Experiment–North America 2004
Authors: Kim S. , Huey L. G. , Stickel R. E. , Tanner D. J. , Crawford J. H. , Olson J. R. , Chen G. , Brune W. H. , Ren X. , Lesher R. , Wooldridge P. J. , Bertram T. H. , Perring A. , Cohen R. C. , Lefer B. L. , Shetter R. E. , Avery M. , Diskin G. , Sokolik I.
Published: February 2007

The first direct in situ measurements of HO2NO2 in the upper troposphere were performed from the NASA DC‐8 during the Intercontinental Chemical Transport Experiment–North America 2004 with a chemical ionization mass spectrometer (CIMS). These measurements provide an independent diagnostic of HOx chemistry in the free troposphere and complement direct observations of HOx, because of the dual dependency of HO2NO2 on HOx and NOx. On average, the highest HO2NO2 mixing ratio of 76 pptv (median = 77 pptv, σ = 39 pptv) was observed at altitudes of 8–9 km. Simple steady state calculations of HO2NO2, constrained by measurements of HOx, NOx, and J values, are in good agreement (slope = 0.90, R2 = 0.60, and z = 5.5–7.5 km) with measurements in the midtroposphere where thermal decomposition is the major loss process. Above 8 km the calculated steady state HO2NO2 is in poor agreement with observed values (R2 = 0.20) and is typically larger by a factor of 2.4. Conversely, steady state calculations using model‐derived HOx show reasonable agreement with the observed HO2NO2 in both the midtroposphere (slope = 0.96, intercept = 7.0, and R2 = 0.63) and upper troposphere (slope = 0.80, intercept = 32.2, and R2 = 0.58). These results indicate that observed HO2 and HO2NO2 are in poor agreement in the upper troposphere but that HO2NO2 levels are consistent with current photochemical theory.
Timescale dependence of environmental and plant‐mediated controls on CH4 flux in a temperate fen
Authors: Treat Claire C. , Bubier Jill L. , Varner Ruth K. , Crill Patrick M.
Published: February 2007

This study examined daily, seasonal, and interannual variations in CH4 emissions at a temperate peatland over a 5‐year period. We measured net ecosystem CO2 exchange (NEE), CH4 flux, water table depth, peat temperature, and meteorological parameters weekly from the summers (1 May to 31 August) of 2000 through 2004 at Sallie's Fen in southeastern New Hampshire, United States. Significant interannual differences, driven by high variability of large individual CH4 fluxes (ranging from 8.7 to 3833.1 mg CH4 m−2 d−1) occurring in the late summer, corresponded with a decline in water table level and an increase in air and peat temperature. Monthly timescale yielded the strongest correlations between CH4 fluxes and peat and air temperature (r2 = 0.78 and 0.74, respectively) and water table depth (WTD) (r2 = 0.53). Compared to daily and seasonal timescales, the monthly timescale was the best timescale to predict CH4 fluxes using a stepwise multiple regression (r2 = 0.81). Species composition affected relationships between CH4 fluxes and measures of plant productivity, with sedge collars showing the strongest relationships between CH4 flux, water table, and temperature. Air temperature was the only variable that was strongly correlated with CH4 flux at all timescales, while WTD had either a positive or negative correlation depending on timescale and vegetation type. The timescale dependence of controls on CH4 fluxes has important implications for modeling.
Surface electrons above liquid helium in porous media
Authors: Zueva T. I. , Kovdrya Yu. Z. , Sokolov S. S.
Published: February 2007

The energy spectrum of electrons localized near the surface of liquid helium in porous media is investigated theoretically. In the situation considered, an electron is brought up from the outside to a fine wire coated with a helium film. The localization of the particle in a spherical pore whose walls are coated with helium is investigated. A variational method is used to find the values of the ground-state energy and the corresponding wave functions for an electron above a cylindrical wire. For an electron localized in a spherical cavity, the energy eigenvalues and wave functions are calculated by numerical solution of the wave equation. The results, supplemented by existing information about the energy spectrum of an electron inside a nanotube, expand our understanding of the properties of electrons in porous media partially filled with helium.
Quantum detector based on a superposition of macroscopic states in a phase qubit
Authors: Shnyrkov V. I. , Melnik S. I.
Published: February 2007

A quantum detector whose working principle is based on magnetic-field modulation of a circulating supercurrent in the quantum ground state of a macroscopic superconducting loop with a Josephson junction. Under the influence of an external magnetic flux equal to Φ0∕2 (or Φ0), two (or three) classical states are coupled to each other by quantum tunneling through a potential barrier, and therefore the detector is a two-level (or three-level) system. In the low-temperature region and under the condition of very weak damping, the mean value of the circulating supercurrent reflects the character of the variation of the quantum superposition of macroscopic states, which is sensitive to the symmetry of the potential. The variations of the current are amplified and detected in a measurement scheme similar to the signal registration in a nonhysteretic rf SQUID. It is shown by a numerical analysis that in comparison with a qubit detector based on an SIS junction, a detector with an ScS junction is faster and has much larger amplitudes of energy splitting at the same parameters. The results presented for double- and triple-well potentials clearly indicate that a qubit with an ScS junction can act as a detector with a sensitivity determined by the quantum noise of the amplifier.
On the theory of Bose–Einstein condensation of quasiparticles: On the possibility of condensation of ferromagnons at high temperatures
Authors: Bugrij A. I. , Loktev V. M.
Published: February 2007

The Bose condensation of magnons in physical systems of finite size is considered for the case of ferromagnetic thin films. It is shown that in accordance with present-day experimental capabilities, which permit one to achieve densities of long-wavelength spin excitations of ∼1018–1019cm−3 in such films, the formation of a coherent condensate of such quasiparticles begins at temperatures T∼102K (including room temperature). It is found that Bose condensation is accompanied by a scaling phenomenon, according to which the main thermodynamic variable is not the number of particles N but the ratio N∕T. This indicates that the Bose condensation of magnons can be observed at relatively low magnon densities (and, accordingly, low pumping). The roles played by the shape of the spectrum of spin excitations and by the film thickness for observation of the phase transition to the state with the Bose condensate are analyzed, and the partial contributions of different groups of quasiparticles to the total spectral distribution of magnons over energies are discussed.
State diagram of an antiferromagnet with a predominant Dzyaloshinskii interaction
Authors: Zavrazhnaya E. M. , Chepurnykh G. K.
Published: February 2007

A phase diagram in the variables Hz, Hy is constructed for an easy-axis tetragonal antiferromagnet with a predominant Dzyaloshinskii interaction. On this diagram the lines of second-order phase transitions between the canted phase and a phase in which the antiferromagnetic vector l is perpendicular to the easy axis begin and end at the fields of spin-flip transitions (i.e., at the exchange field). These lines of second-order phase transitions have the feature that each of them has two tricritical points, at which a transition occurs to a line of first-order phase transitions. The critical angle between the magnetic field direction and the basal plane, within which a first-order phase transition occurs, is determined. The value of this angle is temperature dependent. The position of the tricritical point on the Hz–Hy (or, equivalently, the Hz–Hy phase diagram is also temperature dependent.
Manifestation of the spin-orbit interaction in bismuth films in a parallel magnetic field
Authors: Komnik Yu. F. , Andrievskii V. V. , Berkutov I. B.
Published: February 2007

The magnetic field dependence of the resistance of bismuth thin films (100–700Å thick) at low temperatures (1.5–77K) are analyzed in the conceptual framework of quantum corrections to the conductivity due to weak localization and electron interaction effects. It is shown that the diversity and variability of the magnetoresistance curves in a parallel field upon variations of the thickness and temperature are due to the fact that the spin-orbit interaction time τso increases with increasing field, altering the relationship between τso and the phase relaxation time τφ. This result supports the hypothesis that the strong spin-orbit interaction manifested in the surface scattering of electrons is due to the existence of a potential gradient near the metal surface, and a parallel magnetic field alters the orientation of the spins, accompanied by a decrease of the rate of spin-orbit processes.
Optical properties and crystal lattice parameters of TlGa1−xFexSe2 solid solutions
Authors: Gasanov N. Z. , Kerimova E. M. , Gasanov A. I. , Asadov Yu. G.
Published: February 2007

Semiconductor solid solutions of the system TlGaSe2–TlFeSe2 are investigated. The parameters of the crystal lattice of the compounds of this system are established with the aid of an x-ray structural analysis. Experimental studies of the absorption spectra of single crystals of the solid solutions TlGa1−xFexSe2 (x=0, 0.005, 0.01) are carried out in the temperature interval 10–120K, and the energy positions and coefficients of the temperature shift of the excitons at the edge and deep inside the optical absorption region are determined.
Redistribution of carriers in oxygen-underdoped Y1Ba2Cu3O7−δ at high hydrostatic pressure
Authors: Vovk R. V. , Obolenskii M. A. , Bondarenko A. V.
Published: February 2007

The influence of high hydrostatic pressure up to 7kbar on the conductivity and charge transport in the ab plane is investigated in Y1Ba2Cu3O7−δ single crystals with an oxygen deficiency δ≈0.55 and a critical temperature Tc≈45K. It is shown that the pressure-induced redistribution of the labile oxygen leads to a change of the value of the activation energy for charge transport and to enhancement of phase separation in the sample. It is found that the relaxation behavior of the electrical resistance of a sample during a hold at room temperature after application and removal of pressure exhibits substantial asymmetry.
Analytical and Monte Carlo study of two antidots in magnetic nanodisks with vortex-like magnetization
Authors: Pereira A. R. , Moura A. R. , Moura-Melo W. A. , Carneiro D. F. , Leonel S. A. , Coura P. Z.
Published: February 2007

How stable vortex-like magnetization in magnetic nanodisks with small aspect ratio (L/R≪1) is affected by two antidots is investigated analytically and by Monte Carlo simulations. For suitable ranges of the physical parameters this vortex presents bistable states when pinned around the antidots. The hysteresis loop obtained shows a central loop associated to the pinning mechanism of the vortex at the antidots. Our results agree qualitatively well with those provided by experiments and micromagnetic simulations.
Deficiencies of the kinetics order method for the study of thermoluminescence
Authors: Xu Zheng , Zhang Fujun , Zhao Suling , Wang Liwei , Georgobiani A. N. , Xu Xurong
Published: February 2007

Luminescence is a widespread fundamental physical phenomenon. It has a broad application in the field of illumination, display, dosimeter, mining, archaeology, various analyses, etc. Trap and decay are two important, inseparable factors in luminescence dynamic processes, and thermoluminescence, in particular. Of the two most popular techniques of studying the dynamics of this process, the method based on kinetics order has serious deficiencies: (1) a fixed parameter to represent an evolving process and (2) an assumed value, instead of an experimental value, disagrees with reality. We proposed a method of simultaneous determination of trap depth and decay parameters from the glow curve of ZnS:Cu,Co, obtaining the trap depth ε=0.86eV and decay parameter n0¯=2.6 simultaneously. From these data, we have shown dependence of trap depth ε on decay parameter, which clearly shows the error of ε for any assumed decay parameter. If we treat the case of kinetics order α=1 as α=2, the error might be as large as 100%.
Plasma expansion of ZnO-coated surface barrier discharge in open air and its optical analysis
Authors: Choi Jai Hyuk , Han Man Hyeop , Baik Hong Koo , Song Kie Moon
Published: February 2007

Characteristics of the ZnO-coated surface barrier discharge in open air were diagnosed optically. Highly conductive ZnO film was deposited on the dielectric surface. We found that the increase of the surface conductivity induces wider discharge area. Moreover we analyzed the optical behavior of plasma transition of two barrier discharges by optical emission spectroscopy. Discharge characteristic of the normal dielectric barrier discharge is divided into only two modes: streamer and glow discharge. But in the case of ZnO-coated dielectric barrier discharge, pd range of glowlike discharge exists widely and this can be also an evidence of the enhancement of plasma uniformity.
Scaled Born cross sections for excitations of H2 by electron impact
Authors: Kim Yong-Ki
Published: February 2007

This article describes the scaling of plane-wave Born cross sections for the excitation of the H2 molecule to four low-lying electronic states (BΣu+1, CΠu1, B′Σu+1, and DΠu1) by electron impact. The same BE and BEf scaling methods used on atoms were found to be equally effective for H2 in converting Born cross sections into cross sections in good agreement with available experiments. These scaling methods are applicable only to dipole-allowed excitations. The possibility of using these scaling methods, as was done in atoms, to estimate the contribution of inner-shell excitations to the total ionization cross section via the excitation-autoionization mechanism is discussed, though this type of indirect ionization in molecules is not as common as in atoms.
Seven-dimensional quantum dynamics study of the O(P3)+CH4 reaction
Authors: Yang Minghui , Lee Soo-Y. , Zhang Dong H.
Published: February 2007

The initial state selected time-dependent wave packet calculations have been carried out to study the title reaction with seven degrees of freedom included by restricting the nonreacting CH3 group under C3V symmetry and the CH bond length in the group. Total reaction probabilities as well as integral cross sections were calculated for the ground and four vibrationally excited reagent states. Our calculation shows that the reactivity is very small for the reaction for collision energy up to 1.0eV for all the initial states. Initial vibration excitation of CH4, in particular, the CH stretch excitation, enhances the reactivity, but only part of the excitation energy deposited can be used to reduce the reaction threshold. The rate constant for the ground initial state agrees rather well with that from a recent quasiclassical trajectory study and is larger than that from the semirigid vibrating rotor target calculations, in particular, in the low temperature region. On the other hand, the thermal rate constant calculated from the integral cross sections for these five vibrational states is about a factor of 20 smaller than that from the multiconfiguration time-dependent Hartree study.
Superposition of quantum and classical rotational motions in Sc2C2@C84 fullerite
Authors: Michel K. H. , Verberck B. , Hulman M. , Kuzmany H. , Krause M.
Published: February 2007

The superposition of the quantum rotational motion (tunneling) of the encapsulated Sc2C2 complex with the classical rotational motion of the surrounding C84 molecule in a powder crystal of Sc2C2@C84 fullerite is investigated by theory. Since the quantum rotor is dragged along by the C84 molecule, any detection method which couples to the quantum rotor (in casu the C2 bond of the Sc2C2 complex) also probes the thermally excited classical motion (uniaxial rotational diffusion and stochastic meroaxial jumps) of the surrounding fullerene. The dynamic rotation-rotation response functions in frequency space are obtained as convolutions of quantum and classical dynamic correlation functions. The corresponding Raman scattering laws are derived, and the overall shape of the spectra and the width of the resonance lines are studied as functions of temperature. The results of the theory are confronted with experimental low-frequency Raman spectra on powder crystals of Sc2C2@C84 [M. Krause et al., Phys. Rev. Lett. 93, 137403 (2004)]. The agreement of theory with experiment is very satisfactory in a broad temperature range.
Productions of I, I*, and C2H5 in the A-band photodissociation of ethyl iodide in the wavelength range from 245to283nm by using ion-imaging detection
Authors: Tang Ying , Lee Wei-Bin , Hu Zhengfa , Zhang Bing , Lin King-Chuen
Published: February 2007

Photodissociation dynamics of ethyl iodide in the A band has been investigated at several wavelengths between 245 and 283nm using resonance-enhanced multiphoton ionization technique combined with velocity map ion-imaging detection. The ion images of I, I*, and C2H5 fragments are analyzed to yield corresponding speed and angular distributions. Two photodissociation channels are found: I(5pP3∕22)+C2H5 (hotter internal states) and I*(5pP1∕22)+C2H5 (colder). In addition, a competitive ionization dissociation channel, C2H5I++hν→C2H5+I+, appears at the wavelengths <266nm. The I∕I* branching of the dissociation channels may be obtained directly from the C2H5+ images, yielding the quantum yield of I* about 0.63–0.76, comparable to the case of CH3I. Anisotropy parameters (β) determined for the I* channel remain at 1.9±0.1 over the wavelength range studied, indicating that the I* production should originate from the Q03 state. In contrast, the β(I) values become smaller above 266nm, comprising two components, direct excitation of Q13 and nonadiabatic transition between the Q03 and Q11 states. The curve crossing probabilities are determined to be 0.24–0.36, increasing with the wavelength. A heavier branched ethyl group does not significantly enhance the I(5pP3∕22) production from the nonadiabatic contribution, as compared to the case of CH3I.
Molecular dynamics of a short-range ordered smectic phase nanoconfined in porous silicon
Authors: Guégan R. , Morineau D. , Lefort R. , Moréac A. , Béziel W. , Guendouz M. , Zanotti J.-M. , Frick B.
Published: February 2007

4-n-octyl-4-cyanobiphenyl has been recently shown to display an unusual sequence of phases when confined into porous silicon (PSi). The gradual increase of oriented short-range smectic (SRS) correlations in place of a phase transition has been interpreted as a consequence of the anisotropic quenched disorder induced by confinement in PSi. Combining two quasielastic neutron scattering experiments with complementary energy resolutions, the authors present the first investigation of the individual molecular dynamics of this system. A large reduction of the molecular dynamics is observed in the confined liquid phase, as a direct consequence of the boundary conditions imposed by the confinement. Temperature fixed window scans reveal a continuous glasslike reduction of the molecular dynamics of the confined liquid and SRS phases on cooling down to 250K, where a solidlike behavior is finally reached by a two-step crystallization process.
Enhanced laser shutter using a hard disk drive rotary voice-coil actuator
Authors: Scholten R. E.
Published: February 2007

Rotary voice-coil motors from computer hard disk drives make excellent mechanical shutters for light beams. However, the complexity of the necessary electronic driving circuit can hinder their application. A new design is presented here, using a single integrated circuit originally intended for controlling dc motors. A digital input signal switches a unipolar power supply bidirectionally through the voice coil. Short high-current pulses are generated on the transitions to ensure rapid shutter action, while a low holding current reduces the power requirement and heating of the actuator. The circuit can reverse the current to brake the shutter and reduce the impact at the end of its travel. With a focused laser beam, the shutter achieves rise times below 500 ns. A method for producing variable length pulses is also described, demonstrating durations as short as 700 ns.
Extrinsic photonic crystals: Photonic band structure calculations of a doped semiconductor under a magnetic field
Authors: Xu Chun , Han Dezhuan , Wang Xin , Liu Xiaohan , Zi Jian
Published: February 2007

Doped semiconductors are intrinsically homogeneous media. However, by applying an external magnetic field that has a spatially periodic variation, doped semiconductors can behave extrinsically like conventional photonic crystals. The authors show this possibility theoretically by calculating the photonic band structures of a doped semiconductor under an external, spatially periodic magnetic field. Homogeneous media, behaving like conventional photonic crystals under some external, spatially periodic fields, define another kind of photonic crystals: extrinsic photonic crystals.
Electroluminescence from surface oxidized silicon nanoparticles dispersed within a polymer matrix
Authors: Ligman Rebekah K. , Mangolini Lorenzo , Kortshagen Uwe R. , Campbell Stephen A.
Published: February 2007

In this work electrically induced light emission from crystalline silicon nanoparticles randomly dispersed within a polymer matrix was obtained. The observed polymer/silicon nanoparticle device electroluminescence (EL) was composed of simultaneous emission from the polymer and the silicon nanoparticles. The device emission was nonscalar and shifted from a polymer to a silicon nanoparticle dominant emission with increased current density. The device JV characteristics were bulk dominated independent of the nanoparticle loading. The nonscalar field dependence and bulk dominated carrier transport properties strongly suggest that the observed silicon nanoparticle emission was produced by an EL energy transfer process.
Experimental analysis of surface plasmon behavior in metallic circular slits
Authors: Chang Chin-Kai , Lin Ding-Zheng , Yeh Chau-Shioung , Lee Chih-Kung , Chang Yu-Chia , Lin Ming-Wei , Yeh Ji-Tian , Liu Jung-Ming
Published: February 2007

Using a focused ion beam, the authors fabricated metallic circular slits onto a glass substrate coated with silver film. The influence of the number of slits and the focusing light phenomena was investigated by capturing the light transmitted through the circular slits. They demonstrate experimentally that the circular grating formed by a set of periodical slits can excite both stronger surface plasmon (SP) and localized surface plasmon as the number of slits increases. They found that the SP tended to congregate at the center of the circular grating, and that the reemitted light could be used to achieve a focusing phenomenon.
Intermolecular elastic and plastic characteristics of organic phthalocyanine thin films evaluated by nanoindentation
Authors: Kanari Moriyasu , Kawamata Hirotaka , Wakamatsu Takashi , Ihara Ikuo
Published: February 2007

Although small molecule organic thin films have been applied to electronics, very few experimental results have been reported in respect to their mechanical properties. Here the authors report experimental results in which three types of phthalocyanine (Pc) thin films were investigated for mechanical characteristics using a nanoindentation. Indentation hardness of zinc Pc(ZnPc) thin films was significantly higher than those of metal-free Pc(H2Pc) and copper Pc(CuPc) thin films by a factor of approximately 1.7 times. From the mechanical prarameters, the critical bending radius is evaluated in the range of 4.0–5.7mm for the Pc films on a polymer base film.
Comment on “Large negative lateral shifts from the Kretschmann-Raether configuration with left-handed materials” [Appl. Phys. Lett. 87, 221102 (2005)]
Authors: Moreau Antoine , Felbacq Didier
Published: February 2007

The negative shifts seen by Wang and Zhu [Appl. Phys. Lett. 87, 221102 (2005)] are not due to the excitation of surface plasmons but to leaky modes of the slab propagating backward. Provided the characteristics of the left-handed material slab are chosen correctly, it is shown that a leaky surface plasmon can actually be excited using the Kretschmann-Raether configuration.
Evaluation of UV absorption coefficient in laser-modified fused silica
Authors: Negres R. A. , Burke M. W. , Sutton S. B. , DeMange P. , Feit M. D. , Demos S. G.
Published: February 2007

Laser-induced damage in transparent dielectrics leads to the formation of laser-modified material as a result of exposure to extreme localized temperatures and pressures. In this work, an infrared thermal imaging system in combination with a fluorescence microscope is used to map the dynamics of the local surface temperature and fluorescence intensity under cw, UV excitation of laser-modified fused silica within a damage site. The energy deposited via linear absorption mechanisms and the absorption coefficient of the modified material are estimated based on a thermal diffusion model. In addition, irreversible changes in the absorption following extended laser exposure were observed.
Master-equation approach to understanding multistate phase-change memories and processors
Authors: Wright C. David , Blyuss Konstantin , Ashwin Peter
Published: February 2007

A master-equation approach is used to perform dynamic modeling of phase-transformation processes that define the operating regimes and performance attributes of electronic (and optical) processors and multistate memory devices based on phase-change materials. The predictions of the so-called energy accumulation and direct-overwrite regimes, prerequisites for processing and memory functions, respectively, emerge in detail from the model, providing a theoretical framework for future device design and evaluation.
Ionization and fragmentation of solid C60 by femtosecond laser ablation
Authors: Kobayashi T. , Kato T. , Matsuo Y. , Kurata-Nishimura M. , Kawai J. , Hayashizaki Y.
Published: February 2007

Ionization and fragmentation of solid C60 dispersed on a silicon plate are investigated by femtosecond laser ablation. Bimodal mass distribution with large fragment ions C60−2n+ (0⩽n⩽11) and small fragment ions Cn+ (13⩽n⩽28), formation of dimer ion (C60)2+, and delayed ionization of C60 have been observed as reported in gas phase experiments with nanosecond laser excitation. Metastable dissociation of small fragment ions Cn+ has been observed for the first time, which suggests different structures of fragment ions compared with those of well-studied carbon cluster ions. From these observations, strong coupling of laser energy to electronic degrees of freedom of solid C60 has been revealed for femtosecond laser ablation as compared with excitation in the gas phase.
Crossing Conventions in Localized Food Networks: Insights from Southern Italy
Authors: Trabalzi Ferruccio
Published: February 2007

In this paper I demonstrate the analytical potential of the concept of hybridity for understanding localized agrofood networks, that is, production systems whose products are embedded in the history, geography, and culture of a particular place and community. I use the notion of hybridity as a way of describing how local producers do not necessarily follow one specific production logic, whether of scale or variety. The research shows that they exchange, borrow, absorb, and appropriate practices, technologies, knowledge, and conventions from all available models of production. The nature and the extent of the exchange, and thus of hybridization, vary according to the nature of the product, to the position a particular firm occupies within the network, and ultimately, to individual and collective conceptions of how production can and should be organized. The specific ways that firms coordinate transactions between one another and how they develop relations with markets also reflect the producers' choices among different models of organization. Hybridity matters in relation to rural development policies. The entry of local food products into modern marketplaces through a series of intermediate steps, some modern, some traditional, opens up an opportunity to rethink the alleged opposition between industrial and artisan production within localized food networks. As I will show, between industrial and artisan producers, objectives may diverge, but there can also be strong positive exchange. Although industrial producers link up with buyers by serving increasingly wide, even global, markets, artisan producers help retain expertise within the territory of production, anchoring the product deeper into the culture, history, and geography of the area. Institutional actors should recognize and enhance such synergies apart and beyond the technical aspects of production.
Reading Rival Union Responses to the Localization of Technical Work in the US Telecommunications Industry
Authors: Wolf-Powers Laura
Published: February 2007

Between the early 1970s and the late 1990s, state-sponsored deregulation and its market repercussions, combined with technological change, sparked profound changes for employees in the heretofore highly unionized US telecommunications sector. In this paper I examine the responses that this industry-wide restructuring of technical labor has prompted within two unions—the International Brotherhood of Electrical Workers (IBEW) and the Communications Workers of America (CWA). With some success, the CWA has ‘scaled up’, employing innovative national bargaining and organizing tactics in the centralized workplaces of the companies once affiliated with the AT&T Bell System and developing transnational relationships with other countries' telecommunications unions. However, these strategies have not prevented the CWA from losing ground. In contrast, the IBEW's inherent capacity to represent workers on a labor-market or ‘geographic’ scale, and thus to take advantage of the localization of technical work in the industry, has created new opportunities for that union and helped its construction division to reverse a decades-long trend of decline. However, the IBEW has not deliberately ‘constructed scale’ in this environment. Rather, the union has embraced an opportunity presented by a shift in industrial structure which favors its traditional strengths. Thus, the pursuit of the geographic or ‘horizontal’ approach does not align the IBEW with the progressive social movements that many labor geographers associate with localized activism. The case study of the two unions suggests that the existence of distinct traditions in the American labor movement—a craft tradition linked to multiemployer bargaining at the local level and an industrial tradition linked with a strong focus on workplace-based bargaining, national norms, and an active national state—has important implications for the understanding of how labor organizations relate to scale.
Governing Nature Conservation: The European Union Habitats Directive and Conflict around Estuary Management
Authors: Gibbs David , While Aidan , Jonas Andrew E G
Published: February 2007

Demands for increased levels of protection for species and ecosystems are being translated into new modes of spatial governance at national, regional, and local scales. As part of this, new ways of analysing and representing ecological systems are leading to qualitatively different treatment of the (time) spaces of nature conservation. In this paper we explore what happens when the land-use demands of new paradigms of nature conservation collide with preestablished modes of spatial regulation, taking as our focus the implementation of the European Union Habitats Directive in estuary spaces in the United Kingdom. We provide evidence of the ways in which ecological regulation is reshaping political–economic landscapes and offer insights into the direction of ‘postmodern’ nature conservation practice, including the extent to which theoretical notions of hybrid and nonequilibrium systems have become absorbed into conflicts around ecological regulation.
Connecting Gender and Economic Competitiveness: Lessons from Cambridge's High-Tech Regional Economy
Authors: Gray Mia , James Al
Published: February 2007

Although recognition of the significance of gender divisions continues to transform economic geography, the discipline nevertheless remains highly uneven in its degree of engagement with gender as a legitimate focus of analysis. In particular, although social institutions are now widely regarded as key determinants of economic success, the regional learning and innovation literature remains largely gender blind, simultaneously subordinating the female worker voice and making invisible distinctively gendered patterns of work in the face of an increasingly feminised labour force. Focusing on the industrial agglomeration of information and communication technology firms in Cambridge, England, we first outline the nature of the inequalities in patterns of work and social interaction among female versus male employees within Cambridge's high-tech regional economy. Second, we demonstrate how these inequalities in turn constrain female employees' abilities to contribute to key processes widely theorised to underpin firms' innovative capacities and economic competitiveness. Specifically, these self-identified constraints centre on female workers' abilities to: (a) act as agents of information and knowledge diffusion between firms; and (b) use new information and knowledge once they enter the firm. Overall, our results suggest that gender issues of social equity at the level of the individual worker need to be explicitly integrated with issues of economic competitiveness at the levels of the firm and the region. This is a case not simply of female employees being socially excluded at work, but of their simultaneous exclusion from key elements of firms' productive processes.
Materialising Memory at Angel Island Immigration Station, San Francisco
Authors: Hoskins Gareth
Published: February 2007

This paper presents an object-centred account of the politics of memory at a National Historic Landmark: Angel Island Immigration Station, San Francisco. Once a port of entry and detention for Chinese immigrants arriving in the United States, the Immigration Station exists today as a historic site managed by California State Parks who are in the midst of implementing a new interpretive programme with a mission to: ‘turn a history of exclusion into a future of inclusion’. The discussion fixes on three objects located within the park which play an important role in the representation of the site's past despite being labelled as ‘noncontributing’ in the site's National Historic Landmark's nomination. The biographies of a bronze bell, a granite monument, and a group of wax mannequins as sketched out here suggest novel ways to be sensitive to the many and often unexpected contributions brought by the materiality of an object in practices of remembrance.
Planning as Urban Therapeutic
Authors: Gunder Michael , Hillier Jean
Published: February 2007

In this paper we seek to present a challenge to the normative prescriptive role of strategic urban planning practice. In effect, we challenge what has traditionally been regarded as the essence of strategic or ‘forward’ planning: the plan as a statement of what the city ought to become. Using Lacanian-inspired analysis we seek to understand how urban issues may be identified as metaphorical deficiencies or illnesses, to which planners apply a therapeutic salve in the form of strategic policies. Turning to the psychological utopianism of Ernst Bloch, a Freudian-inspired predecessor of Lacan, we suggest a way forward in Bloch's immanent transcendent conceptualisation of hope. We suggest replacement of the transcendent term ‘utopian’ by ‘utopic’, as a practice which is critical, inclusive, and dynamic; performative rather than normative.
Ethical Trading and Socioeconomic Transformation: Critical Reflections on the South African Wine Industry
Authors: Bek David , McEwan Cheryl , Bek Karen
Published: February 2007

Newly emerging ethical trade practices in the South African wine industry are examined as a way of engaging with debates about the ability of alternative trade approaches to facilitate meaningful opportunities for socioeconomic development in the global South. The South African wine industry has undergone rapid restructuring since the end of apartheid in order to meet the demands of international markets. However, transforming racially skewed ownership and skill patterns is proving a particular challenge. In this paper we outline some of the initiatives that have been introduced to stimulate socioeconomic change within the industry. By utilising analytical tools such as commodity chains, networks, and cultural approaches we demonstrate that a complex array of forces is driving change on the ground. Such forces include national imperatives derived from the legacy of apartheid and the concerns of consumers in the global North. We conclude by considering the types of local and global constraints that need to be challenged if these initiatives are to be successful in facilitating meaningful socioeconomic transformation within the wine industry.
Lengths of geodesics between two points on a Riemannian manifold
Authors: Nabutovsky Alexander , Rotman Regina
Published: February 2007

Let

x
x

and

y
y

be two (not necessarily distinct) points on a closed Riemannian manifold

M
n

M^n

. According to a well-known theorem by J.-P. Serre, there exist infinitely many geodesics between

x
x

and

y
y

. It is obvious that the length of a shortest of these geodesics cannot exceed the diameter of the manifold. But what can be said about the lengths of the other geodesics? We conjecture that for every

k
k

there are

k
k

distinct geodesics of length

≤
k
diam
⁡
(

M
n

)

\le k \operatorname {diam}(M^n)

. This conjecture is evidently true for round spheres and is not difficult to prove for all closed Riemannian manifolds with non-trivial torsion-free fundamental groups. In this paper we announce two further results in the direction of this conjecture. Our first result is that there always exists a second geodesic between

x
x

and

y
y

of length not exceeding

2
n
diam
⁡
(

M
n

)

2n\operatorname {diam}(M^n)

. Our second result is that if

n
=
2

n=2

and

M
2

M^2

is diffeomorphic to

S
2

S^2

, then for every

k
k

every pair of points of

M
2

M^2

can be connected by

k
k

distinct geodesics of length less than or equal to

(
4

k
2

−
2
k
−
1
)
diam
⁡
(

M
2

)

(4k^2-2k-1)\operatorname {diam}(M^2)

.
Striving for normality: whole body regeneration through a series of abnormal generations
Authors: Voskoboynik Ayelet , Simon-Blecher Noa , Soen Yoav , Rinkevich Baruch , De Tomaso Anthony W. , Ishizuka Katherine J. , Weissman Irving L.
Published: February 2007

Embryogenesis and asexual reproduction are commonly considered to be coordinated developmental processes, which depend on accurate progression through a defined sequence of developmental stages. Here we report a peculiar developmental scenario in a simple chordate, Botryllus schlossenri, wherein a normal colony of individuals (zooids and buds) is regenerated from the vasculature (vascular budding) through a sequence of morphologically abnormal developmental stages. Vascular budding was induced by surgically removing buds and zooids from B. schlossenri colonies, leaving only the vasculature and the tunic that connects them. In vivo imaging and histological sections showed that the timing and morphology of developing structures during vascular budding deviated significantly from other asexual reproduction modes (the regular asexual reproduction mode in this organism and vascular budding in other botryllid species). Subsequent asexual reproduction cycles exhibited gradual regaining of normal developmental patterns, eventually leading to regeneration of a normal colony. The conversion into a normal body form suggests the activation of an alternative pathway of asexual reproduction, which involves gradual regaining of normal positional information. It presents a powerful model for studying the specification of the same body plan by different developmental programs.—Voskoboynik A., Simon‐Blecher, N., Soen, Y., Rinkevich, B., De Tomaso A. W., Ishizuka, K. J., Weissman I. L., Striving for normality: whole body regeneration through a series of abnormal generations. FASEB J. 21, 1335–1344 (2007)
Mechanism of Cav1.2 channel modulation by the amino terminus of cardiac β2‐subunits
Authors: Herzig Stefan , Khan Ismail F. Y. , Gründemann Dirk , Matthes Jan , Ludwig Andreas , Michels Guido , Hoppe Uta C. , Chaudhuri Dipayan , Schwartz Arnold , Yue David T. , Hullin Roger
Published: February 2007

L‐type calcium channels are composed of a pore, α1c (CaV1.2), and accessory β‐ and α2δ‐subunits. The β‐subunit core structure was recently resolved at high resolution, providing important information on many functional aspects of channel modulation. In this study we reveal differential novel effects of five ß2‐subunits isoforms expressed in human heart ( β 2a‐e) on the single L‐type calcium channel current. These splice variants differ only by amino‐terminal length and amino acid composition. Single‐channel modulation by β2‐subunit isoforms was investigated in HEK293 cells expressing the recombinant L‐type ion conducting pore. All β2‐subunits increased open probability, availability, and peak current with a highly consistent rank order (ß2a≈ ß2b>ß2e≈ ß2c>ß2d). We show graded modulation of some transition rates within and between deep‐closed and inactivated states. The extent of modulation correlates strongly with the length of amino‐terminal domains. Two mutant ß2‐subunits that imitate the natural span related to length confirm this conclusion. The data show that the length of amino termini is a relevant physiological mechanism for channel closure and inactivation, and that natural alternative splicing exploits this principle for modulation of the gating properties of calcium channels.—Herzig, S., Khan, I. F. Y., Gründemarin, D., Matthes, J., Ludwig, A., Michels, G., Hoppe, U. C., Chaudhuri, D., Schwartz, A., Yue, D. T., Hullin, R. Mechanism of Cav1.2 channel modulation by the amino terminus of cardiac ß2‐sub‐units. FASEB J. 21, 1527–1538 (2007)
A Liberal Theory of Secession
Authors: Beran Harry
Published: February 2007

Separatism is a major contemporary socio-political problem and a basic but neglected problem of political philosophy. An attempt is made here to rescue the topic of secession from philosophical neglect and to demonstrate its theoretical importance by developing a liberal normative theory of secession. The claim is made that liberalism requires that secession be permitted if it is effectively desired by a territorially concentrated group and is morally and practically possible. This, it is argued, is required by the value liberalism places on freedom, by a liberal theory of popular sovereignty and by a presupposition of legitimate majority rule. The argument is put that the permissive principle of secession asserted is neither theoretically nor practically unacceptable and some of the conditions which may make secession impossible are specified.
Human Rights under State Socialism
Authors: Lane David
Published: February 2007

The paper is in four parts. The first outlines the debate that has occurred in the West about whether human rights, and about what human rights, are desirable and possible in socialist states. In the second it is contended that the normative approach to rights in socialist states has been influenced but not determined by the theory and practice of the USSR. Human rights under Marxism–Leninism are ambiguously defined: there is an unresolved tension between individual (and group) rights, on the one hand, and class and collective rights on the other. Socialist states, it is claimed, have different units, types of claims and priorities of rights. In the third section, it is argued that the Soviet model of rights has a particular correspondence with Russian culture. Its impact on other socialist countries (Poland is considered, as an illustration) depends on the internal social structure (the strength of interest groups) and the degree of legitimacy of the state. Finally, some prognostications are offered concerning the dynamics and likely developments of rights claims under socialism.