bluuebunny/crossref_metadata_2025 huggingface dataset:
On the phase biases of multiple‐frequency radar returns of mesosphere‐stratosphere‐troposphere radar
Authors: Chen Jenn‐Shyong
Published: October 2004

The frequency domain interferometry (FDI) technique uses two or more frequencies to measure the positions and thicknesses of the atmospheric thin layers embedded in the radar volume, in which the cross‐correlation analyses of the radar echoes for the pairs of carrier frequencies are performed and the resultant amplitudes and phases (FDI phase) are both employed. However, in light of the possibility that the characteristics of radar system, mean refractivity gradient, and other factors that would significantly affect the FDI phase, calibration of the FDI phase is required to improve the measurement. In this study we employed three methods in measuring the phase bias in the FDI observation using the Chung‐Li VHF radar; namely, (1) histogram of the FDI phases, (2) relationship between echo power and FDI phase, and (3) the FDI phase of aircraft. Both methods 1 and 2 are based on the range weighting effect on the radar echoes returned from the atmospheric scatterers; however, the first produced smaller FDI phase bias than the second. To examine such discrepancy in the results of methods 1 and 2, method 3 was exploited and provided more consistent values of phase biases with those of method 2. Considering that the radar echoes reflected from aircrafts are not related to uncertain conditions of the atmosphere such as mean reflectivity gradients and statistical characteristics, the results of methods 2 and 3 may be more reliable. Besides, the first two methods demonstrated that the FDI phase bias was quasi‐linearly dependent on the separation of frequency pair, which not only consolidates the existence of the FDI phase bias but also indicates that a systematic phase compensation for the FDI analysis is possible. For example, considering 0.1‐, 0.4‐, and 0.8‐μs time delays of signals for the returns of 1‐, 2‐, and 4‐μs pulse lengths, respectively, the FDI phase biases can be removed effectively. Same methods and procedures can be applied to other radar systems.
Thermochronology of the modern Indus River bedload: New insight into the controls on the marine stratigraphic record
Authors: Clift Peter D. , Campbell Ian H. , Pringle Malcolm S. , Carter Andrew , Zhang Xifan , Hodges Kip V. , Khan Ali Athar , Allen Charlotte M.
Published: October 2004

The Indus River is the only major drainage in the western Himalaya and delivers a long geological record of continental erosion to the Arabian Sea, which may be deciphered and used to reconstruct orogenic growth if the modern bedload can be related to the mountains. In this study we collected thermochronologic data from river sediment collected near the modern delta. U‐Pb ages of zircons spanning 3 Gyr show that only ∼5% of the eroding crust has been generated since India‐Asia collision. The Greater Himalaya are the major source of zircons, with additional contributions from the Karakoram and Lesser Himalaya. The39Ar/40Ar dating of muscovites gives ages that cluster between 10 and 25 Ma, differing from those recorded in the Bengal Fan. Biotite ages are generally younger, ranging 0–15 Ma. Modern average exhumation rates are estimated at ∼0.6 km/m.y. or less, and have slowed progressively since the early Miocene (∼20 Ma), although fission track (FT) dating of apatites may indicate a recent moderate acceleration in rates since the Pliocene (∼1.0 km/m.y.) driven by climate change. The39Ar/40Ar and FT techniques emphasize the dominance of high topography in controlling the erosional flux to the ocean. Localized regions of tectonically driven, very rapid exhumation (e.g., Nanga Parbat, S. Karakoram metamorphic domes) do not dominate the erosional record.
Potential availability of sedimentary phosphorus to sediment resuspension in Florida Bay
Authors: Zhang Jia‐Zhong , Fischer Charles J. , Ortner Peter B.
Published: October 2004

Several studies have suggested that phosphorus is a limiting nutrient for seagrass and phytoplankton growth in much of Florida Bay. In fact, soluble reactive phosphate concentrations in Florida Bay waters can be as low as a few nM. Sediments represent the largest phosphorus reservoir because Florida Bay sediments are dominated by carbonate, which has a strong capacity to retain phosphorus. The supply of phosphorus to the water column from sediment resuspension is potentially important in providing the nutrients required for phytoplankton production. Applying an improved sequential extraction technique to sediments collected from 40 geographically representative stations in Florida Bay, this study provides the first detailed spatial distribution of total sedimentary phosphorus (TSP) and its partitioning into five chemically distinguishable pools in the surface, fine‐grained sediments of the bay. A strong gradient of decreasing TSP concentration was observed from the west (14.6 μmol g−1) to east (1.2 μmol g−1) across the central bay. The spatial pattern of TSP is consistent with distribution of both seagrass and phytoplankton that are limited by available phosphorus in Florida Bay. Among the five pools, the authigenic carbonate fluorapatite, biogenic apatite and CaCO3‐bound phosphorus account for the largest fraction (45%) of TSP, of which inorganic phosphorus is the dominant form, and organic phosphorus accounts for about 30% in the western and north central regions and less than 10% in other areas of Florida Bay. The second largest pools are the refractory organic phosphorus (24% of TSP) and reductant‐soluble inorganic phosphorus (19% of TSP). Readily exchangeable phosphorus accounts for 8% of TSP, of which organic phosphorus is 60%. Detrital apatite phosphorus of igneous or metamorphic origin represents the smallest fraction, only 5% of TSP. Spatial distribution of phosphorus and iron in sediments indicates that external sources of these two essential plant nutrients to Florida Bay are spatially separated with phosphorus introduced by west coast waters across the western margin of Florida Bay and iron from freshwater flow into the eastern region.
Lack of a significant temperature influence on the incorporation of Cd into benthic foraminiferal tests
Authors: Marchitto Thomas M.
Published: October 2004

Benthic foraminiferal Cd/Ca is an important proxy for seawater paleonutrient concentrations and therefore deep ocean paleocirculation. Although previous work suggests that the incorporation of Cd into benthic foraminiferal calcite is insensitive to temperature, at least one species of planktonic foraminifer appears to be strongly influenced. The present study provides a closer look at the relationship between benthic Cd partition coefficients and temperature, using new and previously published data from the Bahama Banks. Neither calcitic taxa nor the aragonitic Hoeglundina elegans exhibits any consistent changes in partition coefficients over the range 4 to 18°C.
Multi‐spacecraft observations of diffuse ions upstream of Earth's bow shock
Authors: Kis A. , Scholer M. , Klecker B. , Möbius E. , Lucek E. A. , Rème H. , Bosqued J. M. , Kistler L. M. , Kucharek H.
Published: October 2004

We report on simultaneous measurements of energetic ions upstream of Earth's quasi‐parallel bow shock by Cluster during a 10 hour time period when the inter‐spacecraft separation distance was between ∼1 and ∼1.5 Re. Using a bow shock model we determined for each 32 s averaged data set the distance of the Cluster 1 and Cluster 3 spacecraft from the bow shock along the magnetic field. Using the differences of the partial energetic ion densities observed on the two spacecraft we determined the spatial gradient of partial densities at various distances from the bow shock in 4 energy channels ranging from 10 to 32 keV. The gradients in all four energy channels decrease exponentially with distance. The e‐folding distance of the gradients depends approximately linearly on energy and increases from ∼0.5 Re at ∼11 keV to ∼2.8 Re at ∼27 keV. These values are about half of the values obtained on a statistical basis by Ipavich et al. [1981] and by Trattner et al. [1994].
Penetration of the 1990s warm temperature anomaly of Atlantic Water in the Canada Basin
Authors: Shimada Koji , McLaughlin Fiona , Carmack Eddy , Proshutinsky Andrey , Nishino Shigeto , Itoh Motoyo
Published: October 2004

Penetration of the 1990s warm temperature anomaly (WTA) of the Fram Strait branch of Atlantic Water (FSBW) in the Canada Basin is described using available temperature, salinity, and velocity data. The core temperatures of FSBW show distinct pathways. Over the Chukchi Borderland advective velocities of the FSBW are well‐correlated with bottom topography. The resulting multifarious pathways over the Chukchi Borderland act to modulate and substantially increase the time scale of WTA spreading and advancement. Further downstream two WTA tongues are observed. One tongue followed the Beaufort Slope and, along this pathway, the core temperatures of FSBW decreased rapidly. The depth integrated value of heat content remained near constant however, suggesting enhanced vertical mixing. The second tongue debouched from the northern tip of the Northwind Ridge and spread eastward into the deep Canada Basin, suggesting a complex recirculation structure within the Beaufort Gyre.
Anisotropy of the flexural response of the lithosphere in the Canadian Shield
Authors: Audet Pascal , Mareschal Jean‐Claude
Published: October 2004

We show that the two‐dimensional coherence between topography and Bouguer gravity is anisotropic throughout most of the Canadian Shield, excepted Hudson Bay Basin. We interpret the axis of maximum coherence as the direction where the lithosphere is weakest. In the southeastern Shield and the Appalachians, the azimuthally averaged coherence cannot be fitted by the thin elastic plate model. In the other regions, it yields the effective elastic thickness. The average coherence increases in the direction perpendicular to the main tectonic boundaries, the axis of high electrical conductivity, and the seismic fast axis. This consistency suggests that the same stress field affected the entire lithosphere during the last tectonic event.
Regional variations in the uppermost 100 km of the Earth's inner core
Authors: Stroujkova Anastasia , Cormier Vernon F.
Published: October 2004

The structure of the uppermost 100 km of the inner core was examined from PKIKP and PKiKP waveforms in the distance range of 118°–140°. We found evidence of a low‐velocity layer in the uppermost inner core in the equatorial region predominantly located between longitude 20°W to 140°E. In the latitudinal direction the anomaly is detectable from 35°S beneath the Indian Ocean to 60°N underneath Asia. The maximum thickness of the low‐velocity layer inferred from waveform modeling is 40 km with velocity jump of about 3%. We speculate that this layer may represent newly solidified core in the area where vigorous compositional convection in the outer core coincides with new crystal growth in the inner core.
Modeling long‐term volcanic hazards through Bayesian inference: An example from the Tohoku volcanic arc, Japan
Authors: Martin Andrew J. , Umeda Koji , Connor Charles B. , Weller Jennifer N. , Zhao Dapeng , Takahashi Masaki
Published: October 2004

The need to quantitatively estimate future locations of volcanoes in the long‐term is of increasing importance, partly as a result of the requirement of constructing certain types of installations in regions of low geologic risk. The complex geological factors and natural processes controlling the locations of volcanoes make it problematic to estimate future patterns deterministically. Instead, the probabilistic approach can be developed with quite high levels of confidence; however, for regions with few or no volcanoes, there is a need to include additional geological and geophysical data that may indicate the likelihood of future volcanism. We achieve this using Bayesian inference in the Tohoku volcanic arc, Japan, in order to combine one or more sets of geophysical information to a priori assumptions of volcano spatiotemporal distributions yielding modified a posteriori probabilities. The basic a priori assumption is that new volcanoes will not form far from existing ones and that such a distribution ranges from Gaussian (not so conservative) to Cauchy (conservative). Seismic tomographs are used as an indirect clue, and from this geophysical data a likelihood function is generated in the Bayesian context that updates or fine tunes the initial Gaussian or Cauchy kernels to better reflect the distribution of future volcanism. These models are evaluated using pre‐100 ka volcanic events to forecast locations of subsequent events that actually formed from 100 kyr ago to present. Probabilities in Tohoku region range from 10−10/yr between clusters and up to 9.8 × 10−6/yr near the centers of clusters.
Ice and brine production in Storfjorden from four winters of satellite and in situ observations and modeling
Authors: Skogseth R. , Haugan P. M. , Haarpaintner J.
Published: October 2004

Manual classification of fast ice, pack ice, and polynya (open water and thin ice) in Storfjorden from ERS‐2 SAR images during winters 1998 to 2001 was used to determine model parameters in a wind‐driven polynya width model. Production of ice in the classified areas was then calculated from surface heat balance. The modeled open water area occupied on average 10% of the total area and produced 58% of the total ice (Tice). The volume of brine‐enriched shelf water (BSW; Vbsw) was estimated to be in the range 0.9–1.1 × 1012 m3 or 0.06–0.07 Sv (freezing period average) and 0.03–0.04 Sv (annual average). The strength of the northerly wind component seemed to dominate over net heat flux as cause of variability in Tice. Salinity of BSW (Sbsw) was found to be primarily governed by frazil ice production, whereas Vbsw was mostly determined from Tice and surface salinity (initial and change during winter). Correlation studies of modeled time series of winter mean polynya area and Tice in winters 1970 to 2001 showed that interannual variability could partly be explained by variability in regional ice and ocean conditions, and partly by the strength of the southwesterlies from the North Atlantic or the North Atlantic Oscillation (NAO). Strong southerly winds (high NAO) may give less Arctic ice import and ice production in the western Barents Sea, resulting in a higher surface salinity in Storfjorden in fall. The resulting weak stability in the water column may give favorable conditions for producing large Vbsw the following winter. If strong northerly winds over Storfjorden are associated with low NAO, rapid transitions from high to low NAO would give high Vbsw and Sbsw. The link to NAO seems to vary in time. However, the transition from weak northerly winds in winter 1999 to strong northerly winds in winter 2000 was accompanied by high observed Sbsw winter 2000 in agreement with expectations.
Proteinase‐activated receptor pharmacology: trickier and trickier
Authors: Moffatt James D
Published: October 2004

Proteinase‐activated receptors (PARs) are G‐protein‐coupled receptors for serine and other proteinases. Peptide agonists of these receptors are frequently used to characterise the presence and role of PARs in cells and organ systems. However, the specificity of these peptides is questionable in some assay systems. In this issue, Hollenberg et al. report very different effects of PAR4 receptors in various assays. Their results suggest the existence of unknown receptors and further highlight the need to use peptide PAR agonists with due caution.

British Journal of Pharmacology (2004) 143, 441. doi:10.1038/sj.bjp.0705949
Changes in endocannabinoid contents in reward‐related brain regions of alcohol‐exposed rats, and their possible relevance to alcohol relapse
Authors: González Sara , Valenti Marta , de Miguel Rosario , Fezza Filomena , Fernández‐Ruiz Javier , Di Marzo Vincenzo , Ramos José A
Published: October 2004

Chronic alcohol exposure modifies endocannabinoid levels in different brain regions, while pharmacological targeting of the endocannabinoid system has been reported to influence ethanol intake in laboratory animals.

The present study was aimed at evaluating the pattern of changes of endocannabinoids and their receptors, with emphasis on reward‐related brain areas, in Wistar rats subjected to consecutive phases of alcoholization, alcohol deprivation (abstinence), and voluntary consumption of alcohol (relapse).

We observed that, in the limbic forebrain, anandamide (AEA) and 2‐arachidonoylglycerol (2‐AG) contents increased after 7 days of alcoholization, then to dramatically decrease after 48 h of alcohol deprivation and, in the case of 2‐AG, to further decrease when rats were allowed to relapse to alcohol consumption. By contrast, in the midbrain, there was a marked reduction in AEA, but not 2‐AG, content, after alcoholization. This decrease was not affected during alcohol abstinence, but both AEA and 2‐AG contents were then significantly reduced when rats were allowed to relapse to alcohol consumption.

Based on these data, we examined whether pharmacological activation/blockade of endocannabinoid transmission might influence ethanol intake in rats allowed to relapse to alcohol consumption after subsequent periods of alcoholization and alcohol deprivation.

Treatment with either Δ9‐tetrahydrocannabinol or CP55,940, two cannabinoid agonists, reduced both total liquid and ethanol intake but did not affect ethanol preference. Treatment with SR141716, a selective cannabinoid CB1 receptor antagonist, also produced a significant reduction in both total liquid and ethanol intake without affecting ethanol preference. Accordingly, none of these effects on ethanol intake were accompanied by changes in dopamine and GABA in limbic structures.

In summary, the levels of endocannabinoids underwent significant changes in reward‐related areas during alcoholization, alcohol deprivation, and relapse, showing the lowest values in this latter phase. Treatment with cannabinoid agonists or a selective CB1 receptor antagonist resulted in a reduction of ethanol intake by rats allowed to relapse to alcohol consumption after periods of alcoholization and alcohol deprivation, but these effects did not appear to be due to changes in neurobiological substrates currently involved in alcohol reinforcement/relapse.

British Journal of Pharmacology (2004) 143, 455–464. doi:10.1038/sj.bjp.0705963
Cholesteric liquid-crystal laser as an optic fiber-based temperature sensor
Authors: Moreira M. F. , Carvalho I. C. S. , Cao W. , Bailey C. , Taheri B. , Palffy-Muhoray P.
Published: October 2004

In this work, we have studied the temperature dependence of a cholesteric liquid-crystal laser coupled to an optical fiber, with a view towards optical fiber sensor applications. To stabilize the laser emission, we developed a procedure to align the liquid crystal placed in the fiber. Unexpected oscillations in the laser emission were observed as the temperature was varied, which can be understood in terms of the competition between bulk and surface anchoring torques.
Magnetocurrent in a bipolar spin transistor at room temperature
Authors: Huang Y. W. , Lo C. K. , Yao Y. D. , Hsieh L. C. , Ju J. J. , Huang D. R. , Huang J. H.
Published: October 2004

A spin transistor which consists of a metallic giant magnetoresistance emitter, a copper base, and a p-n junction was prepared on a Si(100) wafer. The emitter current changes from 1mA at a magnetically parallel state to 0.968mA at a magnetically antiparallel state. At the same states the base currents were 29.3μA and 333nA, respectively, which gave a magnetocurrent ratio of ∼8600% and a transfer ratio of 3×10−2 at room temperature for a common collector configuration. The sensitivity of this spin device is higher than 4000%∕Oe. The memory effect and the high performance make it possible for practical usage. The working principle of this kind of three-terminal spin device can be simply described by circuit theory.
Competing terahertz radiation mechanisms in semi-insulating InPat high-density excitation
Authors: Nakajima M. , Oda Y. , Suemoto T.
Published: October 2004

The excitation density dependence of the terahertz radiation from a semi-insulating InP surface was investigated in detail. By changing the excitation density, substantial changes were observed in the wave form with a reversal of the polarity of the radiation field. Different azimuthal angle dependence was also observed for low- and high-density excitations. These facts indicate that three different radiation mechanisms coexist and that the dominant radiation mechanism changes with increasing the excitation density from the drift current, for low-excitation density, to the diffusion current and the optical rectification, for high-excitation density.
Short cladding-pumped Er∕Yb phosphate fiber laser with 1.5W output power
Authors: Li L. , Morrell M. , Qiu T. , Temyanko V. L. , Schülzgen A. , Mafi A. , Kouznetsov D. , Moloney J. V. , Luo T. , Jiang S. , Peyghambarian N.
Published: October 2004

We report experimental results on a high-power, cladding-pumped, heavily Er∕Yb co-doped phosphate fiber laser of very short length. Up to 1.5W cw laser power was obtained from an11-cm-long multimode-core active fiber with optimized input and output couplers, when pumped by a 15W diode laser at 975nm. The fiber laser was demonstrated at 1535nm with a linewidth <1.2nm, and a good beam quality of M2<3.
Control of flatband voltage of Si-based metal–oxide–semiconductor diodes by inclusion of cesium ions in silicon dioxide
Authors: Kobayashi Takuya , Tanaka Kazuki , Maida Osamu , Kobayashi Hikaru
Published: October 2004

The flatband voltage of Si-based metal–oxide–semiconductor diodes can be controlled by the inclusion of cesium (Cs) in SiO2 layers. The inclusion of Cs can be achieved by two methods: (1) spin-on of cesium chloride aqueous solutions, and (2) evaporation of Cs. The maximum flatband voltage shift of ∼0.8V is achieved by the Cs evaporation method and, in this case, the Cs concentration is estimated to be ∼1013atoms∕cm2 from total reflection x-ray fluorospectroscopy measurements. Even when the Cs concentration is as low as ∼1010atoms∕cm2, ∼0.1V flatband voltage shift can be achieved. The net positive charge of Cs decreases with the Cs concentration.
Near-field optical microscopy and scanning Kelvin microscopy studies of V-defects on AlGaN∕GaN films
Authors: Ku C. S. , Peng J. M. , Ke W. C. , Huang H. Y. , Tang N. E. , Chen W. K. , Chen W. H. , Lee M. C.
Published: October 2004

Al x Ga 1 − x N thin film was grown on undoped GaN∕sapphire (0001) substrate by metalorganic chemical vapor deposition. V-defects were directly observed by atomic force microscopy (AFM) with various size of 0.5–2μm in diameter. In a previous study, the microphotoluminescence spectra showed an extra peak (Iv=350nm) inside the V-defect besides the near-band-edge emission (Inbe=335nm). To achieve better spatial resolution, we used near-field scanning optical microscopy (NSOM) and scanning Kelvin-force microscopy (SKM) to probe the V-defect in detail. The NSOM spectra showed that the intensity of the Iv band increased gradually from V-defect edges to its center, while Inbe remained unchanged. Besides, the SKM measurements revealed that the Fermi level decreased from the flat region to V-defect center by about 0.2eV. These results suggest that the Iv band could be related to shallow acceptor levels, likely resulting from VGa defects.
Theoretical study of the single-walled gold (5,3) nanotube
Authors: Yang Chih-Kai
Published: October 2004

Total energy calculations based on first principles reveal that a (5,3) gold nanotube has a helical pitch of 10.05nm or a natural length of 20.1Å per unit cell at the minimum total energy. The figure is about 9.5% shorter than the experimental pitch of 11nm under stress from the experimental setup. Energy bands for both pitches are similar, giving five units of quantum conductance. The calculations indicate that the single-walled gold (5,3) nanotube is a robust and stable conducting wire suitable for nanoelectronic applications.
1.55
μ
m
Ge
islands resonant-cavity-enhanced detector with high-reflectivity bottom mirror
Authors: Li C. B. , Mao R. W. , Zuo Y. H. , Zhao L. , Shi W. H. , Luo L. P. , Cheng B. W. , Yu J. Z. , Wang Q. M.
Published: October 2004

A 1.55μmGe islands resonant-cavity-enhanced (RCE) detector with high-reflectivity bottom mirror was fabricated by a simple method. The bottom mirror was deposited in the hole formed by anisotropically etching in a basic solution from the back side of the sample with the buried SiO2 layer in silicon-on-insulator substrate as the etch-stop layer. Reflectivity spectrum indicates that the mirror deposited in the hole has a reflectivity as high as 99% in the range of 1.2–1.65μm. The peak responsivity of the RCE detector at 1543.8nm is 0.028mA∕W and a full width at half maximum of 5nm is obtained. Compared with the conventional p-i-n photodetector, the responsivity of RCE detector has a nearly threefold enhancement.
Nature of high-energy ions in the cathode plasma jet of a vacuum arc with high rate of current rise
Authors: Beilis I. I.
Published: October 2004

The production mechanism of extremely high-energy (up to 10keV) ions observed in vacuum arcs having only a few tens of volts of arc voltage was considered. A model was developed for the plasma acceleration in a high-current (≥1kA) short pulsed (<1μs) vacuum arc, taking into account the high rate of rise of the spot current (dI∕dt>100MA∕s). A system of equations, including equations for the cathode spot and the plasma jet, was solved self-consistently with dI∕dt in the range of 0.1–10GA∕s. It was shown that the plasma could be accelerated to the measured energy in the near spot region due to a gas dynamic mechanism and that the ion energy depends on the ratio of the ion flux to the electron flux. This ratio is determined by the cathode erosion rate. The calculated cathode erosion rate varies from 200 to 10μg∕C when the ion energy increases from 0.1 to 10keV and well agrees with measurements.
Unusual diamagnetic response in PrAlNiCuFe metallic glass
Authors: Wang Y. T. , Pan M. X. , Zhao D. Q. , Wang W. H. , Wang W. L.
Published: October 2004

An unusual diamagnetic response is observed in a Pr60Al10Ni10Cu16Fe4 bulk metallic glass (BMG) during the zero-field-cooled (ZFC) magnetization measurement. The ZFC magnetization of the BMG is found to reverse its direction at low temperature and becomes diamagnetic, whereas the field-cooled branch remains positive. This apparent diamagnetism is ascribed to the specific couple between the ferromagnetic nanoparticles and the amorphous matrix in low fields. Besides, in superconductors, a giant diamagnetic response is unusual in magnetic materials. Therefore, it may simulate scientific and technological interest.
Visualizing charge transport in silicon nanocrystals embedded in SiO2 films with electrostatic force microscopy
Authors: Ng C. Y. , Chen T. P. , Lau H. W. , Liu Y. , Tse M. S. , Tan O. K. , Lim V. S. W.
Published: October 2004

In this work, we report a mapping of charge transport in silicon nanocrystals (nc-Si) embedded in SiO2 dielectric films with electrostatic force microscopy. The charge diffusion from chargednc-Si to neighboring uncharged nc-Si in the SiO2 matrix is found to be the dominant mechanism for the decay of the trapped charge in the nc-Si. The trapped charge and the charge decay have been determined quantitatively from the electrical force measurement. An increase in the area of the charge cloud due to the charge diffusion has been observed clearly. In addition, the blockage and acceleration of charge diffusion by the neighboring charges with the same and opposite charge signs (i.e., positive or negative), respectively, have been observed.
The microprocesses of the quasicrystalline transformation in Zr65Ni10Cu7.5Al7.5Ag10 bulk metallic glass
Authors: Liu L. , Chan K. C. , Pang G. K. H.
Published: October 2004

The microprocesses of the amorphous-to-quasicrystalline transformation in Zr65Ni10Cu7.5Al7.5Ag10 bulk metallic glass were studied in detail by transmission electron microscopy (TEM) and high-resolution TEM (HRTEM). It was found that the amorphous-to-quasicrystalline transformation in the present system undergoes a series of interprocesses and follows the sequence of the phase transformation of amorphous →FCCZr2Ni→Tetragonal Zr2Ni→Tetragonal Zr2Ni with a domain structure →Quasicrystals. HRTEM indicated that a domain structure with a high density of stacking faults was formed in the sample at the stage just prior to the formation of quasicrystals. This special structure seems to possess the structural symmetries similar to those of icosahedral quasicrystals. Nanobeam energy dispersive x-ray spectrum revealed that atomic diffusion was involved in all interprocesses of the phase transformations. This suggests that the amorphous-to-quasicrystalline transformation in the present bulk metallic glass is a nonpolymorphous reaction.
Total internal reflection scattering
Authors: Potenza Marco A. C. , Brogioli D. , Giglio M.
Published: October 2004

We show that the wave front of a total internal reflected beam is perturbed by fluctuations in the region probed by the evanescent wave, and light is scattered both above and below the critical angle. While singly scattered light is related to the two-dimensional Fourier transform at the boundary, multiply scattered light originating from very turbid samples can appear only below the critical angle. We show that the very weak scattered light above the critical angle is due to a double tunnel effect, and it is solely due to single scattering at the surface. Applications are discussed.
Thermoelectric PbTe thin film for superresolution optical data storage
Authors: Lee Hyun Seok , Cheong Byung-ki , Lee Taek Sung , Lee Kyeong Seok , Kim Won Mok , Lee Jae Won , Cho Sung Ho , Youl Huh Joo
Published: October 2004

To find its practical use in ultrahigh density optical data storage, superresolution (SR) technique needs a material that can render a high SR capability at no cost of durability against repeated readout and write. Thermoelectric materials appear to be promising candidates due to their capability of yielding phase-change-free thermo-optic changes. A feasibility study was carried out with PbTe for its large thermoelectric coefficient and high stability over a wide temperature range as a crystalline single phase. Under exposure to pulsed red light, the material was found to display positive, yet completely reversible changes of optical transmittance regardless of laser power, fulfilling basic requirements for SR readout and write. The material was also shown to have a high endurance against repeated static laser heating of up to 106–107 cycles tested. A read only memory disk with a PbTe SR layer led to the carrier to noise ratio value of 47dB at 3.5mW for 0.25μm pit; below the optical resolution limit (∼0.27μm) of the tester.
Coevaporation of CoPt nanoparticles
Authors: Castaldi L. , Giannakopoulos K. , Travlos A. , Niarchos D.
Published: October 2004

Co 50 Pt 50 nanoparticles were codeposited on thermally oxidized Si substrates by electron beam evaporation, at a temperature of the substrate of 700to750°C. The codeposition led to a perfect mixture of the Co and Pt elements within the three-dimensional nanoislands, which exhibit a mean diameter between ∼18 and ∼20nm. The postannealing treatment of the CoPt nanograins resulted in the progressive crystallization of the L10 ordered phase and, consequently, in the progressive magnetic hardening of the samples with a maximum coercivity of ∼5.6kOe.
Superconductivity in diamond thin films well above liquid helium temperature
Authors: Takano Yoshihiko , Nagao Masanori , Sakaguchi Isao , Tachiki Minoru , Hatano Takeshi , Kobayashi Kensaku , Umezawa Hitoshi , Kawarada Hiroshi
Published: October 2004

We report unambiguous evidence for superconductivity in a heavily boron-doped diamond thin film grown by microwave plasma-assisted chemical vapor deposition (MPCVD). An advantage of the MPCVD-deposited diamond is that it can contain boron at high concentration, especially in (111)-oriented films. Superconducting transition temperatures are determined by transport measurements to be 7.4 K for TC onset and 4.2 K for zero resistance. The upper critical field is estimated to be 7 T. Magnetization as a function of magnetic fields shows typical type-II superconducting properties.
Photomechanical effect in films of polyvinylidene fluoride
Authors: Sarkisov Sergey S. , Curley Michael J. , Fields Aisha , Sarkisov Sergey S. , Adamovsky Grigory
Published: October 2004

Photothermal bending of strips of polyvinylidene fluoride was initiated by a laser beam with a power of a few milliwatts. A bending strip generated a force of 10−4N that propelled a 1 g oscillating wheel of a mechanical clock. The frequency of photomechanical resonance at pulsed illumination was inversely proportional to the length of the strip. The proposed model explained bending as a result of uneven thermal expansion on opposite sides of the strip. The model predicted, in agreement with experiment, that the force is proportional to beam power and does not depend on the shape or position of the beam in the strip.
Photogenerated hole carrier injection to YBa2Cu3O7−x in an oxide heterostructure
Authors: Muraoka Y. , Muramatsu T. , Yamaura J. , Hiroi Z.
Published: October 2004

We have fabricated a YBa2Cu3O7−x∕SrTiO3:Nb heterostructure and measured the current–voltage and photovoltaic properties under ultraviolet light irradiation at room temperature. A large photovoltage of 0.8V is observed and is positive to the film. The photovoltage appears under illumination of light with photon energy larger than 3.2eV. These results indicate that photogenerated hole carriers in the SrTiO3:Nb substrate are injected to the film. The maximum surface hole density is attained to be 3.5×1013cm−2 at a light power of 44mW∕cm2. The present photocarrier injection technique could apply to many transition metal oxides to control the hole carrier density externally.
Formation of Ga interstitials in (Al,In)yGa1−yNxP1−x alloys and their role in carrier recombination
Authors: Thinh N. Q. , Vorona I. P. , Izadifard M. , Buyanova I. A. , Chen W. M. , Hong Y. G. , Xin H. P. , Tu C. W.
Published: October 2004

Formation of complex defects involving a Ga interstitial (Gai) in (Al,In)yGa1−yNxP1−x alloys and their effects on optical quality are studied by photoluminescence (PL) and optically detected magnetic resonance spectroscopies. Introduction of these defects is shown to be largely promoted by incorporation of N. In quaternary alloys, concentrations of the defects are found to critically depend on the group III atoms that replace Ga, i.e., it is largely enhanced by the presence of Al in alloys, but is only marginally affected by In incorporation. The effect is attributed to differences in surface adatom mobilities of the group III atoms involved and their bonding strength with N. The revealed Gai complexes are shown to act as efficient nonradiative recombination centers degrading the PL efficiency. The defects exhibit high thermal stability and can only be partially removed by postgrowth rapid thermal annealing.
Opto-electronic versus electro-optic modulation
Authors: Passian A. , Lereu A. L. , Arakawa E. T. , Ritchie R. H. , Thundat T. , Ferrell T. L.
Published: October 2004

We present a nonlinear modulation scheme based on coupling between optically excited surface plasmons in a thin gold film and the heating of the film by a pulsed direct current, and also for the reverse process. The reflected surface-plasmon excitation beam is shown to undergo a spatial deformation as a function of a pulsed current through the foil. Similarly, the current through the thin film is modulated by the action of periodic excitation of surface plasmons using infrared photons.
Atom chips: Fabrication and thermal properties
Authors: Groth S. , Krüger P. , Wildermuth S. , Folman R. , Fernholz T. , Schmiedmayer J. , Mahalu D. , Bar-Joseph I.
Published: October 2004

Neutral atoms can be trapped and manipulated with surface mounted microscopic current carrying and charged structures. We present a lithographic fabrication process for such atom chips based on evaporated metal films. The size limit of this process is below 1 μm. At room temperature, thin wires can carry current densities of more than 107A∕cm2 and voltages of more than 500 V. Extensive test measurements for different substrates and metal thicknesses (up to 5 μm) are compared to models for the heating characteristics of the microscopic wires. Among the materials tested, we find that Si is the best suited substrate for atom chips.
Suppression of antiphase domain boundary formation in Ba0.5Sr0.5TiO3 films grown on vicinal MgO substrates
Authors: Zheng H. , Salamanca-Riba L. , Ramesh R. , Li H.
Published: October 2004

Ba 0.5 Sr 0.5 TiO 3 (BST) thin films were epitaxially grown on MgO vicinal substrates by pulsed-laser deposition and molecular-beam epitaxy. [001] oriented MgO substrates with 2° and 5° miscut toward [010] were selected. The nucleation of antiphase domain boundaries in the direction parallel to the step edges is greatly reduced in BST films grown on the vicinal substrates compared to the films grown on flat substrates. The reduction in antiphase domain boundaries gives rise to a higher dielectric constant when the electrodes are parallel to the direction of the steps, by about 280–460, than in the perpendicular direction.
Transmission electron microscopy and transistor characteristics of the same carbon nanotube
Authors: Meyer Jannik C. , Obergfell Dirk , Roth Siegmar , Yang Shihe , Yang Shangfeng
Published: October 2004

A technique is presented which allows one to combine TEM investigations with transport measurements and potentially a wide range of other investigations on the same nanoobject. Using this technique, we have obtained high-resolution transmission electron microscopy images and transport investigations including transfer characteristics on the same single-walled carbon nanotube. The transfer characteristics show ambipolar transport. This observation is discussed taking into account TEM information on tube diameter, number of tubes in the bundle, and possible tube filling with fullerenes (peapods).
The Location of New Residential Areas and the Preservation of Open Space: Experiences in the Netherlands
Authors: Rietveld Piet , Wagtendonk Alfred J
Published: October 2004

As a consequence of the ongoing growth in demand for houses in the Netherlands over recent decades, the fraction of the total surface used for residential purposes has expanded rapidly. The location patterns of new residential construction are the result of various forces: government intervention aiming at the preservation of open space via zoning, new-town, and ‘compact-city’ policies, and market forces reflecting preferences on the demand side (households and real-estate developers). The main factors influencing the location of residential construction are analysed by means of a statistical analysis. The most significant variables appear to be the proximity of a location to existing residential areas, location in new towns receiving government support, the accessibility of workplaces, distance to railway stations, and, to a lesser extent, the accessibility of nature, surface water, and recreational areas.
Evaluating the Effects of Place-Marketing Campaigns on Interregional Migration in Sweden
Authors: Niedomysl Thomas
Published: October 2004

During the last few years, Swedish municipalities have become increasingly engaged in competition to attract in-migrants. An important element of these efforts has been the use of place-marketing campaigns and promotion. Very little is known, however, about these attempts in terms of the number of municipalities involved, economic efforts, ways of marketing, target groups, etc. Furthermore, and more importantly, as for place-marketing studies in general, there have been few attempts at evaluation. The author's purpose is to provide an overview and to evaluate the effects of place-marketing efforts made by municipalities in Sweden to attract in-migrants. The empirical material is based largely on survey responses from 220 municipalities, and provides data for a general overview as well as for the evaluative approaches employed in the study. Among other findings, the results suggest that, although this kind of marketing has definitely become more important over the last few years, there is little evidence of any significant effects on interregional migration flows.
The Economic (in)Efficiency of Devolution
Authors: Rodríguez-Pose Andrés , Bwire Adala
Published: October 2004

The recent devolutionary trend across the world has been in part fuelled by claims of a supposed ‘economic dividend’ associated with the decentralization of authority and resources. The capacity of devolved administrations with greater autonomous powers to tailor policies to local preferences, to generate innovation in the provision of policies and public services, and to encourage greater participation and be more accountable is supposed to deliver greater economic efficiency. There is, however, little empirical evidence to substantiate these claims. In this paper we assess the horizontal link between devolution and regional economic growth in six national contexts (Germany, India, Italy, Mexico, Spain, and the USA). Regression analyses are used in order to test whether changes in cross-regional differences in growth patterns within each country can be attributed to changes in levels of regional autonomy. The results suggest that, contrary to the expectations of devolutionists, the degree of devolution is in most cases irrelevant for economic growth and, when it matters—as in the cases of Mexico and the USA—it is linked to lower rather than greater economic efficiency.
Impacts of Privatising Britain's Rail Passenger Services—Franchising, Refranchising, and Ten Year Transport Plan targets
Authors: Knowles Richard D
Published: October 2004

Britain's passenger rail services were privatised in 1996/97 to reduce public subsidies and produce customer benefits through the private sector competing for medium or long-term franchises. Private sector franchisees were committed to investment in rolling stock, services, and infrastructure and were expected to deliver more market-oriented and cost-effective services whilst subsidies decreased on an annual sliding scale. The author analyses why some franchisees have been unable to achieve the annual financial improvement required to match tapering subsidies. The greatest challenges are identified in Regional franchises outside southeast England, where contracts were let towards the end of rail privatisation when competition was fiercest. Some contracts have been terminated or renegotiated. Reasons are investigated for record levels of passenger traffic across the rail network, privatisation's major, and unexpected, achievement. Traffic growth slowed, and was confined to the London and South East sector, after the Hatfield accident in October 2000. Reasons are identified for delays in refranchising and the sudden policy change from long-term investment-led franchises to short or medium-term contracts. The comparative financial and customer benefits of refranchising are analysed. Finally, the achievability of the government's Ten Year Transport Plan target of 50% growth in passenger traffic is questioned.
De novo
design of defined helical bundles in membrane environments
Authors: Bilgiçer Başar , Kumar Krishna
Published: October 2004

Control of structure and function in membrane proteins remains a formidable challenge. We report here a new design paradigm for the self-assembly of protein components in the context of nonpolar environments of biological membranes. An incrementally staged assembly process relying on the unique properties of fluorinated amino acids was used to drive transmembrane helix–helix interactions. In the first step, hydrophobic peptides partitioned into micellar lipids. Subsequent phase separation of simultaneously hydrophobic and lipophobic fluorinated helical surfaces fueled spontaneous self-assembly of higher order oligomers. The creation of these ordered transmembrane protein ensembles is supported by gel electrophoresis, circular dichroism spectroscopy, equilibrium analytical ultracentrifugation, and fluorescence resonance energy transfer.
Neuronal nitric oxide synthase negatively regulates xanthine oxidoreductase inhibition of cardiac excitation-contraction coupling
Authors: Khan Shakil A. , Lee Kwangho , Minhas Khalid M. , Gonzalez Daniel R. , Raju Shubha V. Y. , Tejani Ankit D. , Li Dechun , Berkowitz Dan E. , Hare Joshua M.
Published: October 2004

Although interactions between superoxide (

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) and nitric oxide underlie many physiologic and pathophysiologic processes, regulation of this crosstalk at the enzymatic level is poorly understood. Here, we demonstrate that xanthine oxidoreductase (XOR), a prototypic superoxide

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-producing enzyme, and neuronal nitric oxide synthase (NOS1) coimmunoprecipitate and colocalize in the sarcoplasmic reticulum of cardiac myocytes. Deficiency of NOS1 (but not endothelial NOS, NOS3) leads to profound increases in XOR-mediated

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production, which in turn depresses myocardial excitation–contraction coupling in a manner reversible by XOR inhibition with allopurinol. These data demonstrate a unique interaction between a nitric oxide and an

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-generating enzyme that accounts for crosstalk between these signaling pathways; these findings demonstrate a direct antioxidant mechanism for NOS1 and have pathophysiologic implications for the growing number of disease states in which increased XOR activity plays a role.