bluuebunny/crossref_metadata_2025 huggingface dataset:
Internal tide spatial variability off western Portugal detected by current meter observations
Authors: Dias Joaquim
Published: March 2006

Long‐term (10–12 months) current meter observations from the western Iberian continental margin are analyzed focusing on oscillations in the internal gravity wave band. Kinetic energy spectra are characterized by background falloff rates with frequency ω ranging from ω−1 to ω−2, superposed by energetic narrow bands at specific frequencies. Significant spectral peaks are found at some of the inertial‐tidal nonlinear interaction frequencies (M2 + f and M4 + f) and at higher semidiurnal harmonics (M4, M6 and M8). Semidiurnal internal tide kinetic energy reveals a spatial distribution with a maximum coherent contribution (44 cm2 s−2) at 1200‐m depth on the mid continental slope and a maximum relative incoherent signal (>60% of the total semidiurnal tidal band energy) at intermediate levels (650 to 1200 m depth and 30 to 130 km from the shelf break).
Extracting coherent coda arrivals from cross‐correlations of long period seismic waves during the Mount St. Helens 2004 eruption
Authors: Sabra Karim G. , Roux Philippe , Gerstoft Peter , Kuperman W. A. , Fehler Michael C.
Published: March 2006

We computed cross‐correlations of seismic waves generated by Long‐Period (LP) events in the frequency band [0.8–2.2 Hz]. The data were recorded in the vicinity of Mount St Helens (MSH) during an eruptive period from September to December 2004. The time symmetric coherent coda arrivals of the time‐derivative of the cross‐correlation function (DCF), resulting from scattering and topographic effects in MSH area, correspond to arrivals of the Green's function (GF) between the two stations. The DCF waveforms computed on an hourly basis show a remarkable consistency over time periods of several hours but show temporal variations on longer time‐scales. We investigated the emergence rate of the symmetric arrivals of the DCF and discussed their potential applications for volcano monitoring.
Dayside and nightside reconnection rates inferred from IMAGE FUV and Super Dual Auroral Radar Network data
Authors: Hubert B. , Milan S. E. , Grocott A. , Blockx C. , Cowley S. W. H. , Gérard J.‐C.
Published: March 2006

The spectrographic imager at 121.8 nm (SI12) of the far ultraviolet (FUV) experiment onboard the IMAGE spacecraft produces global images of the Doppler‐shifted Lyman α emission of the proton aurora. This emission is solely due to proton precipitation and is not contaminated by dayglow, allowing us to monitor the auroral oval on the dayside as well as on the nightside. Remote sensing of the polar aurora can be advantageously supplemented by use of ground‐based data from the Super Dual Auroral Radar Network (SuperDARN) that monitors the ionospheric convective flow pattern in the polar region. In the present study, the SI12 images are used to determine the location of the open/closed field line boundary and to monitor its movement. The SuperDARN data are then used to compute the ionospheric electric field at the location of the open/closed boundary. The total electric field is then computed along the boundary accounting for its movement via Faraday's law so that the dayside and nightside reconnection voltages can be derived. This procedure is applied to several substorm intervals observed simultaneously with IMAGE FUV and SuperDARN. The dayside reconnection voltage feeds the magnetosphere with open flux, which is later closed by nightside reconnection. The calculated dayside reconnection rate is consistent with the solar wind properties measured by the Geotail, Wind, and ACE satellites. We identify the presence of nightside reconnection due to pseudobreakups taking place during the growth phase. In several cases, we establish that the nightside reconnection rate is maximum at the time of the substorm expansion phase onset or shortly after, reaching ∼120 kV, and then slowly returns to undisturbed values of ∼30 kV. The flux closure rate can also start intensifying prior to expansion phase onset, producing pseudobreakups.
Stress, strain, and mountain building in central Japan
Authors: Townend John , Zoback Mark D.
Published: March 2006

The work described here has two key objectives: to investigate the geometric relationships between the principal directions of crustal stress and crustal strain rate in central Japan and to evaluate how crustal stresses are related to the rates of horizontal strain produced by different tectonic processes. Specifically, we consider the extent to which tectonic stress directions reflect transient deformation produced by interseismic subduction thrust locking. The axis of maximum horizontal compressive stress obtained from focal mechanism inversion agrees well with the axis of greatest contractional strain rate in central and southwest Japan only after the effects of interseismic strain accumulation on geodetic observations have been accounted for according to an elastic dislocation model of subduction thrust locking. The residual deformation, which is presumed to represent net upper plate deformation, is broadly confined to the area of pronounced topography in central Japan and is consistent with the deformation expected for horizontal motion of the Amurian plate with respect to northeastern Honshu. These observations suggest that part of the apparent discrepancy between crustal stress and strain rate directions reported by previous authors stems from a comparison of parameters representing processes occurring on different timescales. In this case, the strain rates associated with cyclic subduction zone locking are not reflected in the crustal stress field; conversely, long‐term horizontal motion between northeast and southwest Japan exerts a stronger influence on the crustal stress field and neotectonic mountain‐building processes in central Japan than do intermittent subduction zone earthquakes.
Formation of submarine lava channel textures: Insights from laboratory simulations
Authors: Garry W. Brent , Gregg Tracy K. P. , Soule S. Adam , Fornari Daniel J.
Published: March 2006

Laboratory simulations using polyethylene glycol (PEG) extruded at a constant rate and temperature into a tank with a uniform basal slope and filled with a cold sucrose solution generate channels that are defined by stationary levees and mobile flow interiors. These laboratory channels consistently display the following surface textures in the channel: smooth, folded, lineated, and chaotic. In the simulations, we can observe specific local conditions including flow rate, position within the channel, and time that combine to develop each texture. The textures in PEG flows form due to relative differences in shear forces between the PEG crust and the underlying liquid wax. Minimal shear forces form smooth crust, whereas folded crust forms when the shear is sufficiently high to cause ductile deformation. Brittle deformation of solid PEG creates a chaotic texture, and lineated crust results from shear forces along the channel‐levee margin. We observe similar textures in submarine lava channels with sources at or near the Axial Summit Trough of the East Pacific Rise between 9° and 10°N. We mapped the surface textures of nine submarine lava channels using high‐resolution digital images collected during camera tows. These textural maps, along with observations of the formation of similar features in analog flows, reveal important information about the mechanisms occurring across the channel during emplacement, including relative flow velocity and shear stress.
Evaluation and correction of subresolved particles by the optical plankton counter in three Australian estuaries with pristine to highly modified catchments
Authors: Moore Stephanie K. , Suthers Iain M.
Published: March 2006

High concentrations of subresolved particles smaller than the 250 μm equivalent spherical diameter (ESD) detection limit of the optical plankton counter (OPC) have hampered its use in turbid estuarine waters. Coincidence of these subresolved particles produced erroneous counts of up to 58 L−1 for 100 μm mesh filtered water samples from three subtropical east Australian estuaries using the laboratory OPC‐1L. The influence of these erroneous counts on in situ OPC‐2T measurements was assessed by comparison with measurements of simultaneously collected net zooplankton using the laboratory OPC‐1L. The total zooplankton abundance from the in situ OPC‐2T measurements could be corrected for erroneous counts of subresolved particles using OPC‐1L measurements of 100 μm mesh filtered water sampled from the same site but with large error. No such corrections were possible for OPC‐2T measurements of total zooplankton biomass or normalized biomass size spectra (NBSS). No meaningful or significant correlations were found between the abundance or biomass of subresolved particles and in situ light attenuance, probably due to tannin‐rich waters with low subresolved particle concentrations. NBSS of simultaneously collected net zooplankton from OPC‐1L measurements indicated higher biomass in the disturbed Manning and Wallamba rivers, whose catchments support intensive livestock agriculture and some residential development, compared to the forested Wallingat River. NBSS may therefore be a useful indicator of nutrient enrichment in estuaries. The slope of NBSS may respond to both production of small particles and the predation and loss of large particles.
Impact craters on regional plains on Venus: Age relations with wrinkle ridges and implications for the geological evolution of Venus
Authors: Basilevsky Alexander T. , Head James W.
Published: March 2006

A global assessment of impact craters on Venus ≥30 km in diameter shows that 146 craters are completely or partially superposed on the regional plains that dominate the surface and typically are deformed by wrinkle ridges. In this study, we found that 10 of these craters are deformed by wrinkle ridges (pre‐WR), 93 craters are superposed on wrinkle ridges (post‐WR), and 43 craters were found to be ambiguous cases. We compared our findings with the results of a similar study by McGill (2004) done for craters of all sizes but for ∼1/3 of the surface of Venus. We found that the percentage of pre‐WR craters found by McGill (2004) among the unambiguous cases (15%) is close to our percentage (10%), but we are in disagreement on the classification of a significant number of specific craters and in this analysis we describe the major reason for the disagreements. We then summarize published data on the crater densities for different plains on Venus. We assess Monte Carlo modeling of volcanic resurfacing, which competed with the ongoing formation of impact craters. On the basis of these data and analyses, we conclude that the mean age of the regional plains is close to the mean global surface age of Venus and that the potential time span of regional plains emplacement was relatively short. We interpret our results as evidence that wrinkle ridging on Venus was a distinct tectonic phase that occurred rather early in post‐regional‐plains time, probably within the first 10%. Although the exact duration remains uncertain, regional and global stratigraphic relationships strongly support the hypothesis that wrinkle ridging on Venus predominantly occurred during a specific phase of history. The geologic record of wrinkle ridging and post‐plains tectonic evolution of volcanic plains on the Moon and Mars show interesting similarities to those of Venus.
Physics of nearshore bed pattern formation under regular or random waves
Authors: van Leeuwen Sonja M. , Dodd Nicholas , Calvete Daniel , Falqués Albert
Published: March 2006

We present an investigation into the growth of nearshore, rhythmic patterns. A comprehensive linear stability model of the surf and shoaling zones is used to examine which type of pattern, transverse or crescentic bar, is likely to form under different wave conditions. In contrast to earlier studies we examine normal and near‐normal incidence on a plane beach. In doing so we reproduce results of earlier, more restricted studies and thereby identify the physical mechanisms leading to the growth of different patterns. This paper also focuses on the role of random wave height distribution compared with regular waves and identifies conditions likely to lead to pattern growth. To this end, an amended wave height dissipation function is presented, which allows us to move between random and regular regimes. It is found that a sharply defined surf breakpoint leads to larger growth rates and crescentic‐bar‐type features. In contrast, a large spread in breaking gives rise to transverse bar patterns with reduced growth rates. Transverse bar alongshore spacing is typically about 1/4 to 1/2 the width of the surf zone, while crescentic bar spacing is larger, up to twice this width. It is also shown that pattern types are influenced by the wave height to depth ratio in the surf zone. This indicates that sites with substantial inner surf zone wave energy and thus greater energy available to move sediment will give rise to transverse bar patterns. A new, propagating mode is identified in such cases, which exists for normal wave incidence. Finally, the role of wave shoaling and wave refraction, either on the bed or on the currents is examined. Crescentic bars seem to be a very robust feature as they stem from the model even if those three effects are ignored. Thus the only essential feedback for their formation is the coupling between depth‐controlled breaking and the evolving bathymetry. In contrast, transverse bar formation is very sensitive to wave refraction being enhanced by refraction over the bed and weakened by refraction over the current.
Hydrologic controls on nitrous oxide production and consumption in a forested headwater catchment in central Japan
Authors: Osaka Ken'ichi , Ohte Nobuhito , Koba Keisuke , Katsuyama Masanori , Nakajima Takuo
Published: March 2006

To clarify the mechanisms of N2O production and consumption in a humid temperate forest, we measured concentrations of gaseous N2O in unsaturated soil and dissolved N2O in groundwater in a forested headwater catchment. We especially focused on the hydrological controls on supplies of electron donors and acceptors for nitrification and denitrification, and their effects on N2O production and consumption. N2O concentrations were higher in the groundwater (0.6–148.0 times higher than water equilibrated with atmospheric N2O) than in the soil gas (1.0–5.4 times higher than atmospheric N2O), suggesting that N2O was mainly produced in the groundwater. Moreover, N2O production was greatest at the periphery of the groundwater body where both DOC and NO3− were readily available from shallower soils upstream. In contrast, N2O was reduced to N2 in the deeper layer of the groundwater body where DO and NO3− were not readily available. N2O concentrations in the unsaturated soil layer were remarkably low despite high N2O concentrations in the groundwater. N2O flux from the spring out point was about 100 times higher than at any other observation site, and there was a decrease in dissolved N2O concentrations from springwater to streamwater. This indicates that N2O produced in the groundwater body did not readily diffuse into the unsaturated soil layer above the groundwater surface, but was transported by groundwater flow to the spring out point and then emitted into the atmosphere, implying the possible mechanism of N2O production, consumption and emission in forested catchments.
Sea surface temperature pattern reconstructions in the Arabian Sea
Authors: Dahl Kristina A. , Oppo Delia W.
Published: March 2006

Sea surface temperature (SST) and seawater δ18O (δ18Ow) were reconstructed in a suite of sediment cores from throughout the Arabian Sea for four distinct time intervals (0 ka, 8 ka, 15 ka, and 20 ka) with the aim of understanding the history of the Indian Monsoon and the climate of the Arabian Sea region. This was accomplished through the use of paired Mg/Ca and δ18O measurements of the planktonic foraminifer Globigerinoides ruber. By analyzing basin‐wide changes and changes in cross‐basinal gradients, we assess both monsoonal and regional‐scale climate changes. SST was colder than present for the majority of sites within all three paleotime slices. Furthermore, both the Indian Monsoon and the regional Arabian Sea mean climate have varied substantially over the past 20 kyr. The 20 ka and 15 ka time slices exhibit average negative temperature anomalies of 2.5°–3.5°C attributable, in part, to the influences of glacial atmospheric CO2 concentrations and large continental ice sheets. The elimination of the cross‐basinal SST gradient during these two time slices likely reflects a decrease in summer monsoon and an increase in winter monsoon strength. Changes in δ18Ow that are smaller than the δ18O signal due to global ice volume reflect decreased evaporation and increased winter monsoon mixing. SSTs throughout the Arabian Sea were still cooler than present by an average of 1.4°C in the 8 ka time slice. These cool SSTs, along with lower δ18Ow throughout the basin, are attributed to stronger than modern summer and winter monsoons and increased runoff and precipitation. The results of this study underscore the importance of taking a spatial approach to the reconstruction of processes such as monsoon upwelling.
Blockade of IKs by HMR 1556 increases the reverse rate‐dependence of refractoriness prolongation by dofetilide in isolated rabbit ventricles
Authors: So Petsy Pui‐Sze , Hu Xu‐Dong , Backx Peter H , Puglisi José Luis , Dorian Paul
Published: March 2006

The rate‐dependent contributions of the rapid and slow components of the cardiac delayed rectifier K+ current (IKr and IKs, respectively) to repolarization are not fully understood. It is unclear whether the addition of IKs block will attenuate reverse rate‐dependence seen after IKr block.

The individual and combined electrophysiological effects of selective IKr and IKs blockers, dofetilide and HMR 1556, respectively, were evaluated using Langendorff‐perfused rabbit hearts. Monophasic action potential duration at 90% repolarization (MAPD90) and ventricular effective refractory period (VERP) were determined at cycle lengths (CLs) of 200–500 ms (at 50 ms intervals).

Dofetilide (1–100 nM) prolonged MAPD90 in a concentration‐dependent manner (P<0.001, n=6) with reverse rate‐dependence (P<0.0001). In contrast, HMR 1556 (10–240 nM) alone did not prolong MAPD90. However, in the presence of 7.5 nM dofetilide, HMR 1556 (100 nM) increased the extent of reverse rate‐dependence by further prolonging MAPD90 at CLs of 400, 450 and 500 ms (P<0.05, n=9) and, to a lesser extent, at shorter CLs (e.g. by 17±4 ms at CL 500 vs 2±3 ms at CL 200 ms).

Effects of dofetilide and HMR 1556 on VERP were similar to those on MAPD90. The slope of the VERP vs CL relation was steeper after the combination (0.081±0.013) than after dofetilide alone (0.028±0.018, P<0.01, n=9).

Blockade of rabbit IKs increased reverse rate‐dependence of IKr block.

British Journal of Pharmacology (2006) 148, 255–263. doi:10.1038/sj.bjp.0706721
Platelets accelerate gastric ulcer healing through presentation of vascular endothelial growth factor
Authors: Wallace John L , Dicay Michael , McKnight Webb , Dudar Genevieve K
Published: March 2006

Platelets contain an array of growth factors that can modulate healing processes, including both pro‐ (e.g., vascular endothelial growth factor (VEGF)) and antiangiogenic (e.g., endostatin) factors. Previous studies have shown that circulating platelets contribute significantly to gastric ulcer healing, acting as a delivery system for these growth factors to the site of injury. In this study, we examined the effects of orally administered human platelets on the healing of gastric ulcers in rats, and determined the contribution of VEGF and endostatin to healing in this model.

Twice‐daily administration of human platelets significantly accelerated ulcer healing, but platelet‐poor plasma (PPP), lysed platelets and serum failed to produce this effect. There was no correlation between ulcer healing and the levels of VEGF or endostatin in serum, PPP or platelet‐rich plasma (PRP).

Accelerated ulcer healing could not be produced by oral administration of the angiogenic factors themselves, at concentrations matching those in PRP.

The accelerated healing induced by platelets could be reversed by immuno‐neutralization of VEGF. In contrast, immuno‐neutralization of endostatin did not affect PRP‐induced ulcer healing.

These studies indicate that VEGF released from platelets accounts for the accelerated healing of gastric ulcers. However, as intact (rather than lysed) platelets were required for the accelerated healing, the presentation of VEGF by the platelet at the site of injury appears to be crucial for enhancement of the healing process.

British Journal of Pharmacology (2006) 148, 274–278. doi:10.1038/sj.bjp.0706722
Pharmacological assessment of the duration of action of glycopyrrolate vs tiotropium and ipratropium in guinea‐pig and human airways
Authors: Villetti Gino , Bergamaschi Marco , Bassani Franco , Bolzoni Pier Tonino , Harrison Selena , Gigli Paolo M , Janni Alberto , Geppetti Pierangelo , Civelli Maurizio , Patacchini Riccardo
Published: March 2006

Our study was aimed at investigating the duration of the bronchodilator action of the antimuscarinc drug glycopyrrolate compared to tiotropium and ipratropium.

In the guinea‐pig isolated trachea, the time (t1/2) necessary for a contractile response to carbachol (0.3 μM) to return to 50% recovery after washout of the antagonist was studied. The offset of the antagonist effect of glycopyrrolate, tiotropium and ipratropium (10 nM each) was t1/2=4.0±0.5, >4.5 and 0.5±0.1 h, respectively. At 4.5 h from the washout of the antagonist, the recovery of the response to carbachol was 50±8, 10±4 and 70±7%, respectively.

In the human isolated bronchus, the offset of the bronchodilator effects of glycopyrrolate (3 nM), tiotropium (1 nM) and ipratropium (10 nM) was t1/2=3.7±0.2; >6 and 3.0±0.2 h, respectively. At 6.0 h from the washout of the antagonist, the recovery of the response to carbachol (1 μM) was 101±10, 27±3 and 110±10%, respectively.

In anaesthetized guinea‐pigs, acetylcholine‐induced bronchoconstriction was markedly reduced by intratracheal instillation of glycopyrrolate (3 nmol kg−1; 88.1±4% inhibition), tiotropium (1.3 nmol kg−1; 86.2±5% inhibition) or ipratropium (1.45 nmol kg−1; 88.1±10% inhibition). These inhibitory effects assessed 3 or 24 h after antagonist administration were reduced to 69.9±5 and 29.7±6%; 28.3±5 and 14.2±5% for glycopyrrolate and ipratropium, respectively, whereas they remained stable (83.5±4; 70.6±6) for tiotropium. The residual inhibitory effect of glycopyrrolate was also assessed at 16 h from administration, and proved to be as low as that found at 24 h (31.2±10 vs 29.7±6%, respectively).

In conclusion, glycopyrrolate‐induced bronchodilation has a longer duration than that of ipratropium, but less than that of tiotropium. The efficacy of a possible glycopyrrolate‐based therapy for asthma or chronic obstructive pulmonary disease given once‐a‐day is not guaranteed by the present investigation.

British Journal of Pharmacology (2006) 148, 291–298. doi:10.1038/sj.bjp.0706724
Nuclear quantum effects on an enzyme-catalyzed reaction with reaction path potential: Proton transfer in triosephosphate isomerase
Authors: Wang Mingliang , Lu Zhenyu , Yang Weitao
Published: March 2006

Nuclear quantum mechanical effects have been examined for the proton transfer reaction catalyzed by triosephosphate isomerase, with the normal mode centroid path integral molecular dynamics based on the potential energy surface from the recently developed reaction path potential method. In the simulation, the primary and secondary hydrogens and the C and O atoms involving bond forming and bond breaking were treated quantum mechanically, while all other atoms were dealt classical mechanically. The quantum mechanical activation free energy and the primary kinetic isotope effects were examined. Because of the quantum mechanical effects in the proton transfer, the activation free energy was reduced by 2.3kcal∕mol in comparison with the classical one, which accelerates the rate of proton transfer by a factor of 47.5. The primary kinetic isotope effects of kH∕kD and kH∕kT were estimated to be 4.65 and 9.97, respectively, which are in agreement with the experimental value of 4±0.3 and 9. The corresponding Swain-Schadd exponent was predicted to be 3.01, less than the semiclassical limit value of 3.34, indicating that the quantum mechanical effects mainly arise from quantum vibrational motion rather than tunneling. The reaction path potential, in conjunction with the normal mode centroid molecular dynamics, is shown to be an efficient computational tool for investigating the quantum effects on enzymatic reactions involving proton transfer.
Gifford-McMahon/Joule-Thomson cryocooler with high-flow-conductance counterflow heat exchanger for use in resistance thermometer calibration
Authors: Shimazaki Takeshi , Toyoda Keishi , Tamura Osamu
Published: March 2006

A cryocooler that consists of a two-stage Gifford-McMahon (GM) mechanical refrigerator and a Joule-Thomson (JT) expansion circuit is developed for use in resistance thermometer calibration. The cryocooler is designed to attain a lower temperature rather than to produce a higher cooling power. A simple but high-performance counterflow heat exchanger is developed for the cryocooler. The heat exchanger has a high flow conductance while maintaining a high heat exchange efficiency. It is an improved type of counterflow heat exchanger composed of a spiral capillary and a thin-wall straight outer tube. The developed cryocooler uses a single counterflow heat exchanger not like a conventional GM/JT cryocooler, which usually has two or three counterflow heat exchangers. He4 is used as the working fluid for the JT expansion circuit. The pot where the condensed He4 collects after the JT expansion can reach 1.3K in the continuous operation mode and 1.0K in the single-cycle operation mode. The cooling power of the cryocooler is 580μW at 1.34K with a molar flow rate of 300μmol∕s. Temperature control of the pot was demonstrated from 1.4to12K using two control methods. One method involves controlling the evacuation speed in the JT circuit and the other involves controlling the heat input from a heater to the pot. The temperature of the pot is controlled within the order of magnitude of 2mK from peak to peak with either method.
Development of a two-degree-of-freedom piezoelectric rotary-linear actuator with high driving force and unlimited linear movement
Authors: Zhang Y. , Zhang W. J. , Hesselbach J. , Kerle H.
Published: March 2006

Piezoelectric actuators are considered as standard structural elements in Microsystems Technology. A piezoelectric transducer conventionally works as a pure linear motor (piezotranslator). If a rotation is required from the piezoelectric transducer, a transmission mechanism must be designed. This article presents a study on the development of a novel two-degree-of-freedom piezoelectric rotary-linear actuator system, including (1) conceptual design, (2) dynamic modeling, (3) control, and (4) prototype. The experimental validation of these concepts was performed. The preliminary result of the experiment has shown that the proposed concept works very well; in particular, the system has achieved (1) the linear displacement resolutions: 26nm, (2) the angular displacement resolution: 0.019°, (3) the maximum driving force: 2.09N, and (4) the maximum driving torque: 12.20Nmm.
Size reduction of nanoparticle ink patterns by fluid-assisted dewetting
Authors: Dockendorf Cedric P. R. , Choi Tae-Youl , Poulikakos Dimos , Stemmer Andreas
Published: March 2006

A novel method is proposed to considerably reduce the size of partially wetting patterns of nanopaticle solutions (nanoinks) on a substrate. A nanoink prepared by suspending gold nanoparticles in toluene was deposited on a glass substrate by writing a thin line with the width of 70μm. A water droplet of about 100μl covering the pattern was employed to shrink the pattern by transport of the toluene from the nanoink to the water region triggered by controlled heat addition from the substrate, which increased the solubility of toluene into water (these two liquids are practically immiscible at room temperature). During the dewetting phase, the three-phase-contact line is pulled by the uncompensated Young’s force. The dewetting dynamics is explained by the action of thermocapillarity enhanced by the convection microflow generated in the water layer.
Two-way indent depth recovery in a NiTi shape memory alloy
Authors: Zhang Yijun , Cheng Yang-Tse , Grummon David S.
Published: March 2006

Controlled reversible changes in surface texture and topography are of interest to many applications, including information storage, optical communication devices, micro-fluidic instruments for drug delivery, and smart tribological surfaces for friction and wear control. Here, we demonstrate a method of inducing two-way reversible changes in an indentation made on the surface of a shape memory NiTi alloy. The two-way indent shape change is accomplished by thermomechanical training of spherical indents in NiTi shape memory alloy. After training, spherical indents exhibit two-way depth recovery: Shallow indent depth at high temperature and deep indent depth at low temperature. The reversible depth change is about 45% of the total indent depth and is stable over many cycles. The reversible depth change can have a wide range of engineering applications.
Subnanometer-equivalent-oxide-thickness germanium p-metal-oxide-semiconductor field effect transistors fabricated using molecular-beam-deposited high-k/metal gate stack
Authors: Ritenour A. , Khakifirooz A. , Antoniadis D. A. , Lei R. Z. , Tsai W. , Dimoulas A. , Mavrou G. , Panayiotatos Y.
Published: March 2006

Metal-oxide-semiconductor field effect transistors (MOSFET) with a thin high-k dielectric were fabricated on bulk n-type germanium substrates. Surface oxides were thermally desorbed in situ by heating the substrates under ultrahigh vacuum conditions. First an ultrathin passivating layer was formed by evaporating germanium in the presence of atomic oxygen and nitrogen supplied from a remote radio frequency plasma source. Subsequently, the HfO2 dielectric was deposited by evaporating hafnium in the presence of atomic oxygen. An in situ TaN metal gate was similarly deposited. Long channel devices were fabricated using a standard process flow. These devices exhibited a low equivalent oxide thickness (EOT) of 0.7nm with gate leakage less than 15mA∕cm2 at VFB+1V. Device mobility was extracted from Is-Vg and split C-V characteristics. Results indicate a 2× mobility enhancement in Ge p-MOSFET devices compared to Si control devices. The demonstration of subnanometer EOT suggests that high-k gate dielectrics on germanium are scalable to low EOT and suitable for use in ultrascaled MOSFET devices.
Molecular beam epitaxy growth of In0.52Al0.48As∕In0.53Ga0.47As metamorphic high electron mobility transistor employing growth interruption and in situ rapid thermal annealing
Authors: Ihn Soo-Ghang , Jo Seong June , Song Jong-In
Published: March 2006

We investigated the effects of high temperature (∼700°C) in situ rapid thermal annealing (RTA) carried out during growth interruption between spacer and δ-doping layers of an In0.52Al0.48As∕In0.53Ga0.47As metamorphic high electron mobility transistor (MHEMT) grown on a compositionally graded InGaAlAs buffer layer. The in situ RTA improved optical and structural properties of the MHEMT without degradation of transport property, while postgrowth RTA improved the structural property of the MHEMT but significantly degraded mobility due to the defect-assisted Si diffusion. The results indicate the potential of the in situ RTA for use in the growth of high-quality metamorphic epitaxial layers for optoelectronic applications requiring improved optical and electrical properties.
Raman spectroscopy of pressure-induced amorphous boron carbide
Authors: Yan X. Q. , Li W. J. , Goto T. , Chen M. W.
Published: March 2006

We report low- and high-temperature Raman spectroscopy of pressure-induced amorphous boron carbide (a-B4C). Coarsening of carbon clusters in a-B4C was characterized during heating, whereas unusual temperature coefficients of a-B4C Raman peak shifts were observed during cooling. These results experimentally evidence that the amorphization of B4C is associated with the destruction of the C–B–C chains and a-B4C is composed of sp2 carbon aromatic rings and boron clusters. This disordered structure with relatively weak carbon sp2 bonds is believed to be responsible for the loss of B4C shear strength at high pressures.
Influence of annealing temperature on the band structure of sol-gel Ba0.65Sr0.35TiO3 thin films on n-type Si(100)
Authors: Lu H. , Pan J. S. , Chen X. F. , Zhu W. G. , Tan O. K.
Published: March 2006

The annealing temperature effect on the band structure of Ba0.65Sr0.35TiO3 (BST) thin films coated on n-type Si(100) substrate was investigated by ellipsometry and x-ray photoelectron spectroscopy. The band energy shifts of sol-gel BST films annealed at different temperatures are dependent on their developed microstructure. Related to the amorphous BST films annealed at 600°C, the polycrystalline BST film annealed at 700°C exhibits narrow band gap, upwards-moved Fermi level, and downwards-moved conduction band minimum, which are believed to contribute the enhanced field emission of BST-coated Si field emitter arrays.
Excellent soft-ferromagnetic bulk glassy alloys with high saturation magnetization
Authors: Shen Baolong , Akiba Masahiro , Inoue Akihisa
Published: March 2006

The development of Fe-based bulk glassy alloys (BGAs) with high glass-forming ability has become a very hot research topic, not only because of the soft-magnetic properties, but also of the high fracture strength. Here we report the discovery of excellent soft-ferromagnetic BGAs in FeMoPCBSi system, without the expensive element Ga, which can be cast into glassy alloy rods with diameters range up to 4mm by copper mold casting. These low cost Fe-based ferromagnetic BGAs exhibit high saturation magnetization of 1.27–1.44T and superhigh initial permeability of 13 400–25 000 at 1kHz under a field of 1A∕m.
Intersubband spectroscopy of quantum cascade lasers under operating conditions
Authors: Revin D. G. , Wilson L. R. , Cockburn J. W. , Krysa A. B. , Roberts J. S. , Airey R. J.
Published: March 2006

A technique is described that enables the mid infrared spectroscopic study of the intersubband electron distribution in quantum cascade lasers under operating conditions. By measuring the transmission of a broadband thermal source through the waveguide of a λ∼7.4μm InGaAs∕AlInAs∕InP quantum cascade laser, the redistribution of the electrons in the active region confined levels has been investigated for a wide range of operating currents and temperatures. This technique also allows direct determination of key parameters such as the temperature of the core region under operating conditions, the modal gain coefficient, and the waveguide loss.
Microstructural refinement mechanism by controlling heating process in multiphase materials with particular reference to γ-TiAl
Authors: Zhu Hanliang , Maruyama K. , Matsuda J.
Published: March 2006

The microstructural refinement mechanism by controlling heating rate was investigated in TiAl alloys as an example of multiphase materials. During heating in the α+γ dual phase field of TiAl alloys, the phase transformation of γ to α takes place. The increase in heating rate raises the extent of superheating, leading to increases in driving force and the nucleation rate of the α phase. At higher heating rate, numerous α nuclei form and lengthen, resulting in a fine α2∕γ lamellar microstructure after subsequent cooling. The theoretical prediction was demonstrated by the experimental results obtained on a fully lamellar Ti-48Al alloy.
Behavior of antimony in ZnSe grown by a closed Bridgman method
Authors: Wang J. F. , Isshiki M.
Published: March 2006

High-quality and large-size p-ZnSe single crystals doped with antimony (Sb) have been grown by a Bridgman method using a closed double crucible. Photoluminescence spectra at low temperatures indicate that Sb works as both a shallow acceptor and a deep complex donor. By studying the temperature and excitation intensity dependences of the free-to-acceptor and donor-acceptor pair emissions, we estimated that the ionization energy of Sb as a shallow acceptor in ZnSe is (112–114)meV above the valence band, and that of the deep complex donor related to Sb is 37 ±1meV below the conduction band.
Transport properties of low angle grain boundaries in Y1−xCaxBa2Cu3O7−δ films at high magnetic fields
Authors: Weber A. , Schneider C. W. , Hembacher S. , Schiller Ch. , Thiel S. , Mannhart J.
Published: March 2006

The critical current density of grain boundaries and grains in Y1−xCaxBa2Cu3O7−δ films has been measured in magnetic fields up to 10T. As a function of temperature the critical current densities across 8° [001]-tilt boundaries display a maximum at ≈15–20K for 0.04⩽x⩽0.2 and fields of several teslas. Opposite to the behavior of large angle grain boundaries, calcium doping is found not to enhance the critical current densities of low angle grain boundaries (θ⩽8°).
Dopant profile engineering by near-infrared femtosecond laser activation
Authors: Wang Yi-Chao , Pan Ci-Ling , Shieh Jia-Min , Dai Bau-Tong
Published: March 2006

Femtosecond laser annealing (FLA) was employed for activation of phosphorus (P)- and boron (B)-implanted silicons with negligible dopant diffusion. Preamorphizing implantation is not required. We found that the dopant profiles in FLA-activated samples essentially duplicate those of as-implanted ones even for junctions as deep as 100nm below the surface. The measured sheet resistances and activation efficiencies of P- and B-implanted samples were in the range of 100–400Ω∕◻ and 28%–35%, respectively. Moreover, thermal-energy-assisted dopant diffusion by heating was observed for substrate temperature as low as 100°C. The shallow activated-depth feature associated with FLA reduces the separation between end-of-range defects and high-concentration portion of dopants. This generates a steep interstitial gradient responsible for observed B and P uphill diffusions at a depth of about 60nm below the surface.
Landscape Analysis as a Tool for Surface Mining Design
Authors: Menegaki Maria E , Kaliampakos Dimitris C
Published: March 2006

Surface mining operations constitute one of the most visible and significant landscape offenders because of their geomorphologic and aesthetic effects. In recent years, the disturbance of the landscape owing to surface mining activities seems to be one of the most significant issues to deal with, as it raises serious conflicts between the public and the extractive industry. Therefore, it is necessary to adopt an environmentally friendly design for an excavation of any possible degree. Thus far, existing visual-impact assessment methodologies provide little support towards this direction as a consequence of their, mainly, qualitative character. In this paper we describe a new, more quantitative, methodological approach which is based on the measurement of topographic relief alteration caused by mining and quarrying works, and which makes use of modern mining software and geographic information systems tools. The methodology provides the means to adjust the excavation design in a way that minimizes visual impacts caused by the landform reprofiling. It can be applied in every stage of the life of a mine project. Moreover, if modified, it can also be used for the estimation of topographic relief alteration in projects within the construction sector that involve significant earthmoving works.
Visual Privacy and Family Intimacy: A Case Study of Malay Inhabitants Living in Two-Storey Low-Cost Terrace Housing
Authors: Hashim Ahmad Hariza , Rahim Zaiton Abdul , Rashid Sharifah Norazizan Syed Abdul , Yahaya Nurizan
Published: March 2006

The authors report on a study of visual privacy, family intimacy, and building elements of two-storey low-cost terrace housing in an urban area in Malaysia. They examine behavioural and physical regulating mechanisms used to achieve privacy among Malay Muslim inhabitants of the housing units studied. They also look at the consequences of the lack of privacy on the inhabitants over a period of time. Their findings support the premise that cultural values influence housing and that religious understanding influences mechanisms used to regulate visual privacy and intimacy.
A Review of Rural Land-Use Planning Models
Authors: Riveira Inés Santé , Maseda Rafael Crecente
Published: March 2006

In this paper, different land-use planning models have been reviewed; within this review, techniques and methodologies with different objectives, applications, and land uses have been identified. The existing literature in this field is dispersed throughout different subjects, such as planning, geographical information systems (GIS), decisionmaking, or computer systems. The compilation, analysis, and comparison of the different models have allowed us to draw a series of conclusions for the development and implementation of strategic plans for rural land use. Because GIS have become an essential tool in rural land-use planning, special attention has been paid to the models and methods integrated into GIS.
The Dynamics of the Tel Aviv Morphology
Authors: Benguigui Lucien , Blumenfeld-Lieberthal Efrat , Czamanski Daniel
Published: March 2006

In this paper we suggest an approach for understanding the spatial behavior and structure of cities. It views cities as physical objects and is based on urban morphology alone. The units of examination are urban clusters instead of municipalities defined by politically determined boundaries. Clusters are defined as contiguous built-up urban areas. We present characteristics of clusters, including their morphology. Previous work that analyzed urban clusters focused on the Pareto distribution of clusters and on the behavior of the biggest cluster. Our work presents a more thorough description of the characteristics of urban clusters. By means of historic data of the Tel Aviv metropolis we present cluster statistics and we study their dynamics. We present characteristics of the clusters from 1935 to 2000, including their number, rank-size distribution, and morphology through the area–perimeter relation. These indicators present important anomalies in 1964 and 1985. Our study suggests that the urban cluster approach can be used as a tool to study urban phenomena and we hope that through them we shall be able to investigate economic and social phenomena as well.
An Interdisciplinary Argument for Natural Morphologies in Architectural Design
Authors: Joye Yannick
Published: March 2006

Humans have evolved in natural environments, a process which has resulted in the development of a neural system specialized in the processing of information about the natural world (for example, plants and animals). To a certain extent, the existence of such a system can explain the perennial interest of the architectural field in applying conceptual ideas about nature to architectural theory and in integrating natural form in architecture. Yet, owing to the decreasing contact with natural form in the modern world, this system is becoming less stimulated and, ultimately, underdeveloped. A probable effect of this trend is that the architectural field will become increasingly disinterested in adopting natural morphologies. It is argued that this can lead to three interrelated types of impoverishment. These underscore the importance of integrating natural form in architectural design.
Knowledge of the Environment and Spatial Cognition: JRS as a Technique for Improving Comparisons between Social Groups
Authors: Ramadier Thierry , Bronner Anne-Christine
Published: March 2006

In this paper we compare the sketch-map technique with a spatial modelling task based on a set of eight separate items. The aim of the comparison is to verify, thanks to a special spatial reconstruction set, Jeu de reconstruction spatiale (JRS), whether the difficulties often encountered by unskilled persons when asked to draw a sketch map can be avoided. If so, the JRS could help to improve comparisons between different social groups. Thirty university students majoring in geography and twenty-one unskilled staff members were asked to represent the centre of Strasbourg both by drawing a sketch and with the JRS. The results show that, on one hand, the difference between the two groups regarding the number of items mentioned is smaller with the JRS than with the sketch map. On the other hand, in both groups, the same proportion of respondents increased the number of urban elements produced in the second trial with the JRS. This was not the case with the sketch map. Also, the JRS is more stable than the sketch map from one trial to the next. Furthermore, the respondents preferred the JRS to the sketch map. However, the JRS is more suggestive than the sketch map, but only for elements which are more rarely represented (railway tracks, etc). Thus, in terms of scientific research, the JRS makes it possible to improve comparisons between social groups. In terms of applications, it offers interesting possibilities for promoting citizen participation in urban planning.
From Organism to Commodity: Gender, Class, and the Development of Soil Science in Hungary 1900–89
Authors: Engel-Di Mauro Salvatore A
Published: March 2006

Through a succession of liberal and state-socialist regimes in Hungary, the interconnections of gender, class, and soil management established much of the social framework within which soil scientists produced constructs that affected scientific explanations of and prescriptions to soil-degradation problems. Various metaphors, analogies, conflations, and externalisations shaped notions of soil productivity, the producing subject, and the nature of soils. Their legitimacy and justification emerged from the evolving interplay of rural processes, the economic policies of succeeding regimes, and capitalist world-system dynamics. The results of the study suggest that physical scientists have actively promoted regime ideologies, that gendered scientific constructs need not be grounded in dualistic syllogisms, and that industrialised state-socialist scientific practices largely conformed to bourgeois principles.
Local Community, Legitimacy, and Cultural Authenticity in Postconflict Natural Resource Management: Ethiopia and Mozambique
Authors: Black Richard , Watson Elizabeth
Published: March 2006

In this paper we explore the way in which ‘local community’ has been conceptualised in initiatives to promote natural resource management (NRM) in postconflict Ethiopia and Mozambique in the late 1990s. Both countries have seen a shift towards policy discourses that stress ‘participatory’ approaches to NRM, and a search for legitimate and authentic cultural institutions at a local level that can act as a vehicle for implementation of this new policy approach. Yet, engagement with a range of local institutions has often conflated terms such as ‘indigenous’ and ‘traditional’ with ‘local’, ‘community’, and ‘communal’, missing contestation over their social and cultural authenticity and making mistaken assumptions about the rootedness of institutions in geographical space. Examples of forest management initiatives in Manica Province, Mozambique, and land and water management in Borana, southern Ethiopia, are contrasted to consider the differences and similarities in the nature and outcomes of such external interventions.