bluuebunny/crossref_metadata_2025 huggingface dataset:
Suppression of the von Kármán vortex street behind a circular cylinder by a travelling wave generated by a flexible surface
Authors: WU CHUI-JIE , WANG LIANG , WU JIE-ZHI
Published: February 2007

An advanced moving-wall control strategy to manage the unsteady separated flow over a circular cylinder is developed. A two-dimensional numerical simulation of the flow over the cylinder atRe=500 based on diameter indicates that, when the downstream half of the cylinder surface is made flexible to form an appropriate travelling transverse wave, a ‘fluid roller bearing’ (FRB) is produced consisting of a row of vortices trapped by each wave trough, which can keep the global flow attached against a strong adverse pressure gradient, eliminating the vortex shedding and reducing the average drag by 85%. Physically, the FRB serves as a sheath to effectively inhibit the momentum–energy exchange between the thin fluid layer adjacent to the wall and the main stream, so that the wall layer is scaled only to the local wavelength and frequency and is independent of the global scales. Therefore, the global adverse pressure gradient on the lee side of the cylinder no longer influences the near-wall flow, and the common root cause of flow separation is removed. The input power for actuating the flexible wall is found to be 94% of the power saving due to drag reduction.
Clothing, age and the body: a critical review
Authors: TWIGG JULIA
Published: February 2007

Clothes are central to the ways older bodies are experienced, presented and understood within culture, so that dress forms a significant, though neglected, element in the constitution and experience of old age. Drawing on a range of secondary literature, this article traces how clothing intersects with three key debates in social gerontology, concerning the body, identity and agency. It examines the part played by clothing in the expression of social difference, and explores the role of age-ordering in determining the dress choices of older people, and its enforcement through moral discourses that discipline their bodies. Dress is, however, also an arena for the expression of identity and exercise of agency, and the article discusses how far older people are able to use clothing to resist or redefine the dominant meanings of age. Lastly the paper addresses questions of the changing cultural location of older people, and the role of consumer culture in the production of Third Age identities.
The European Union and WTO law: a nexus of reactive, coactive, and proactive approaches
Authors: ANTONIADIS ANTONIS
Published: February 2007

Ranging from the denial of direct effect to WTO law by the Court of Justice to a WTO-friendly legislative culture currently booming in the EU's political institutions, different approaches towards WTO law have been adopted within the EU. This article classifies the different approaches into reactive, coactive, and proactive by drawing on their common characteristics. The principal aim is to explore the considerations shaping the development of the different approaches and to argue that these stem from the interaction between the judiciary and the legislature. In doing so, this article purports to provide a comprehensive view of the application of WTO law within the Community legal order.
WTO Case Law: The American Law Institute Reporter's Studies United States - Definitive Safeguard Measures on Imports of Certain Steel Products
Authors: GROSSMAN GENE M. , SYKES ALAN O.
Published: February 2007

The Appellate Body decision in the steel dispute is the latest in a line of unsatisfactory decisions in the safeguards area. The problem stems from the fact that the treaty text regarding the preconditions for the use of safeguard measures is badly deficient. The Appellate Body with its usual emphasis on textualism has done little to resolve the puzzles that the text creates. WTO members are left with little guidance about the proper use of safeguards beyond some confusing and sometimes incoherent standards. We review these issues as they have arisen in prior decisions, and then discuss the details of the steel dispute. Our emphasis there is on the panel decision more than the Appellate Body report, as the latter breaks little new ground.
Gütekriterien einer deutschen Adaptation des Transformational Leadership Inventory (TLI) von Podsakoff
Authors: Heinitz Kathrin , Rowold Jens
Published: February 2007

Zusammenfassung. Geprüft wurde, ob das Transformational Leadership Inventory (TLI; Podsakoff, MacKenzie & Bommer, 1996 ; Podsakoff, MacKenzie, Moorman & Fetter, 1990 ) mit sieben Inhaltsskalen zur Erfassung transformationaler und transaktionaler Führung für die Beurteilung deutscher Führungskräfte geeignet ist. In Testanalysen wurden die Gütekriterien der deutschen Adaptation anhand zweier Stichproben (N1 = 404, N2 = 267) ermittelt. Konfirmatorische Faktorenanalysen bestätigten das siebenfaktorielle Modell des TLI. Hohe Zusammenhänge zwischen den transformationalen Skalen und erstens subjektiven Zufriedenheits- und Leistungsmaßen sowie zweitens dem Commitment der Mitarbeiter werden als Belege für die Konstruktvalidität gewertet. Lediglich eine Skala des TLI erscheint aufgrund ihrer geringen internen Konsistenz als verbesserungswürdig. Insgesamt steht mit der hier vorgestellten deutschen Adaptation des TLI ein ökonomisches Instrument mit ansprechenden Gütekriterien für den Einsatz bereit. Bezogen auf die Konstrukt- und Kriterienvalidität des Instrumentes zeigen sich jedoch auch beim TLI vergleichbare Probleme wie etwa beim Multifactor Leadership Questionnaire.
Numerical modeling of mixed sediment resuspension, transport, and deposition during the March 1998 episodic events in southern Lake Michigan
Authors: Lee Cheegwan , Schwab David J. , Beletsky Dmitry , Stroud Jonathan , Lesht Barry
Published: February 2007

A two‐dimensional sediment transport model capable of simulating sediment resuspension of mixed (cohesive plus noncohesive) sediment is developed and applied to quantitatively simulate the March 1998 resuspension events in southern Lake Michigan. Some characteristics of the model are the capability to incorporate several floc size classes, a physically based settling velocity formula, bed armoring, and sediment availability limitation. Important resuspension parameters were estimated from field and laboratory measurement data. The model reproduced the resuspension plume (observed by the SeaWIFS satellite and field instruments) and recently measured sedimentation rate distribution (using radiotracer techniques) fairly well. Model results were verified with field measurements of suspended sediment concentration and settling flux (by ADCPs and sediment traps). Both wave conditions and sediment bed properties (critical shear stress, fine sediment fraction, and limited sediment availability or source) are the critical factors that determine the concentration distribution and width of the resuspension plume. The modeled sedimentation pattern shows preferential accumulation of sediment on the eastern side of the lake, which agrees with the observed sedimentation pattern despite a predominance of particle sources from the western shoreline. The main physical mechanisms determining the sedimentation pattern are (1) the two counter‐rotating circulation gyres producing offshore mass transport along the southeastern coast during northerly wind and (2) the settling velocity of sediment flocs which controls the deposition location.
Fragmentation in the Val Pola rock avalanche, Italian Alps
Authors: Crosta Giovanni B. , Frattini Paolo , Fusi Nicoletta
Published: February 2007

Grain size data from the deposit of the 1987 Val Pola rock avalanche (central Italian Alps) are compared with data concerning rock avalanching, rock fragmentation, and comminution. The Weibull distribution fits a small part of the entire particle‐size distribution of debris samples, with a mean value of the curve shape factor of 0.54 ± 0.28. This is typical of multiple comminution, or fragmentation with much shearing. A fractal distribution fits over a greater size range. Computed fractal dimensions range between 1.3 and 3.2 within the deposit, with average values of about 2.6–2.7. These values cover the range between the theoretical values of the plane‐of‐weakness model (1.97) and the pillar‐of‐strength model (2.84) and are close to the theoretical value for the constrained comminution model (2.58). These suggest that both texturally mature and immature deposits are present and that more than a single comminution process acted during the rock avalanche motion. Variation of the grain size distribution within the deposit and grain size segregation show as trends in the fractal dimension and arise from variation in the fragmentation process. A variety of different physical and empirical laws suggest that 1–30% of the energy expended in the rock avalanche was consumed in fragmentation.
Wavelet analysis of GPS amplitude scintillation: A case study
Authors: Materassi Massimo , Mitchell Cathryn N.
Published: February 2007

Amplitude scintillations on GPS links due to diffraction by ionospheric irregularities are traditionally described, in their strength, via the standard deviation of the signal power normalized to its average within 1 min, the S4 index. One should be very careful in using S4 and always remember that this quantity contains useful information when the signal is stationary for 60 s. In this work, amplitude scintillations are described in a multiscale approach; a wavelet decomposition of the amplitude time series is performed, and the evolution of the signal is studied through its scalogram. What is found is that sudden turbulent events in the amplitude time series, potentially very harmful for the stability and reliability of the radio link, are singled out very clearly in scalograms and cannot be confused with segments of quiet signals. This technique is found to be very useful in those cases in which the signal cannot be considered as stationary over a minute. This new approach is a powerful technique for identifying events that are particularly disruptive to GPS operations. Applications of the new approach in identifying short‐duration fading and rapid phase fluctuations are discussed.
Range‐imaging observations of cumulus convection and Kelvin‐Helmholtz instabilities with the MU radar
Authors: Luce H. , Hassenpflug G. , Yamamoto M. , Crochet M. , Fukao S.
Published: February 2007

In the present work, we report observations of cumulus convection and Kelvin‐Helmholtz (KH) instabilities in the troposphere at high vertical and time resolution with the middle and upper atmosphere (MU) radar (46.5 MHz, 34.85°N, 136.10°E, Japan). A detailed morphology of the structures could be obtained through application of range‐imaging technique (called frequency radar interferometric imaging (FII) or range imaging (RIM)) with the Capon processing method. The usefulness of this work lies in the demonstration of the performance of the MU radar in range‐imaging mode for investigating various atmospheric phenomena at small scales. As one case study, we describe the high‐resolution echo pattern during a convective event. It is found that the convective cells formed in the early afternoon and reached a maximum altitude of about 3.5 km. The high‐resolution images revealed thin layers above this altitude, unresolved at the standard 150‐m low‐resolution mode, associated with vertical oscillations possibly due to gravity waves generated by the convective cells through the mechanism of “obstacle effects.” As a second case study, two clear images of KH billows and waves are shown. The KH billows were observed in the troposphere in regions of strong vertical shear of the horizontal wind and persisted for at least 20 min in both cases. The horizontal wavelengths of the KH waves were estimated to be about 2.5 and 5.7 km, according to the magnitude of the horizontal wind in the altitude range where the dynamic shear instabilities were observed.
Advective and diffusive contributions to reactive gas transport during pyrite oxidation in the unsaturated zone
Authors: Binning P. J. , Postma D. , Russell T. F. , Wesselingh J. A. , Boulin P. F.
Published: February 2007

Pyrite oxidation in unsaturated mine waste rock dumps and soils is limited by the supply of oxygen from the atmosphere. In models, oxygen transport through the subsurface is often assumed to be driven by diffusion. However, oxygen comprises 23.2% by mass of dry air, and when oxygen is consumed at depth in the unsaturated zone, a pressure gradient is created between the reactive zone and the ground surface, causing a substantial advective air flow into the subsurface. To determine the balance between advective and diffusive transport, a one‐dimensional multicomponent unsaturated zone gas transport model is developed. Both advection‐diffusion and Maxwell‐Stefan model formulations are presented. A steady state analytical solution is derived that provides insight into solution behavior and which can be used to test numerical models. A numerical solution is obtained for both the steady and transient cases. At steady state, advection comprises approximately 23% of the total oxygen flux, with the contribution of advection being almost entirely determined by the composition of the atmosphere. Other parameters, such as the permeability, have a negligible effect on the proportion of advective flows at steady state. However, greater pressure gradients are found in low‐permeability soils. In transient cases, advective fluxes depend on the initial conditions and can be far greater than diffusive fluxes. In contrast to steady state conditions the transient case is sensitive to other model parameters; for example, the time to approach steady state depends exponentially on the distance between the soil surface and the subsurface reactive zone.
Arguments against a physical long‐term trend in global ISCCP cloud amounts
Authors: Evan Amato T. , Heidinger Andrew K. , Vimont Daniel J.
Published: February 2007

The International Satellite Cloud Climatology Project (ISCCP) multi‐decadal record of cloudiness exhibits a well‐known global decrease in cloud amounts. This downward trend has recently been used to suggest widespread increases in surface solar heating, decreases in planetary albedo, and deficiencies in global climate models. Here we show that trends observed in the ISCCP data are satellite viewing geometry artifacts and are not related to physical changes in the atmosphere. Our results suggest that in its current form, the ISCCP data may not be appropriate for certain long‐term global studies, especially those focused on trends.”
Two competing pathways of aerosol effects on cloud and precipitation formation
Authors: Takemura Toshihiko , Kaufman Yoram J. , Remer Lorraine A. , Nakajima Teruyuki
Published: February 2007

Aerosols may influence cloud formation through two pathways: One is the effect on cloud microphysics by forming smaller and more numerous cloud droplets reducing precipitation and consequently enhancing cloud lifetime. The second is referred to as the aerosol dynamic‐hydrological effect in which the aerosol direct, semi‐direct, and indirect effects can modulate atmospheric radiation, which perturbs atmospheric circulation, leading to redistributions of clouds and precipitation. Here this study examines climate sensitivities using a general circulation model coupled with an aerosol transport‐radiation model. The model is run first with prescribed meteorology in order to isolate the cloud microphysical effect. It is run in a separate experiment with internally generated meteorology that includes dynamic‐hydrological effect as the aerosols modify clouds and interact with the radiation. We find in some regions that the dynamic‐hydrological effect in the free model runs counteracts the microphysical effects seen in the prescribed runs.
Slowing of the Atlantic meridional overturning circulation: A climate model perspective
Authors: Searl Yvonne , Banks Helene T. , Stark Sheila , Wood Richard A.
Published: February 2007

Analyses of five transatlantic hydrographic sections suggest that the annual average Atlantic meridional overturning circulation was 30% weaker at the beginning of the 21st century compared to the late 1950s. We examine the simulation of the Atlantic meridional overturning in the climate model HadCM3. In both the control experiment and simulations of the 20th century, there is no significant trend in the overturning on the timescales of the observations and a change of 30% in the annual average overturning is very unusual. We use HadCM3 to highlight uncertainties associated with the method used to derive annual average overturning from the five observations. Assuming hydrographic sections to be representative of their respective years, inferring the flow field from density via geostrophy and using constant Ekman and Gulf Stream transport, all introduce uncertainties in both the mean and variability of the reconstructed overturning. Using monthly hydrographic fields rather than annual mean fields increases the variability of the estimated model meridional overturning circulation. Continuous monitoring of the overturning is needed to enable the interannual and seasonal variability to be understood better and to allow detection and attribution studies.
22‐Year survey of tropical convection penetrating into the lower stratosphere
Authors: Rossow William B. , Pearl Cindy
Published: February 2007

A 22‐year survey of tropical convection penetrating into the stratosphere has been conducted using special subsets of the International Satellite Cloud Climatology Project cloud data set. In addition to refined information about the geographic distribution of penetrating convective systems, these results show that penetrating convection occurs predominantly in the larger, organized, mesoscale convective systems, whereas smaller, unorganized convective systems rarely penetrate. Durations of penetrating events are longest for the largest systems, hurricanes and typhoons, generally exceeding one day.
D″ anisotropy beneath Southeast Asia
Authors: Thomas Christine , Wookey James , Simpson Matthew
Published: February 2007

Earthquakes from the Banda Sea and Flores Sea region recorded at the Kyrgyz Network in the Tien Shan region show evidence for anisotropy in the lowermost mantle beneath South East Asia. Shear‐wave splitting is measured for the ScS phase after a receiver‐side correction is applied. Individual results show scatter in measured time lag and fast direction, but stacking these gives a stable estimate of 0.8 ± 0.04 s and 43 ± 4 degrees. This equates to a fast‐shear wave with a polarisation deviation from horizontal (at the bounce point) of around 9 degrees. The simplest model to explain is a transversely isotropic medium with a slight dip to the east, and an inferred anisotropy of ∼0.25%. This is compatible with previous observations of VSH > VSV for this region. Scenarios which might explain the observed anisotropy include sheared melt pockets or aligned post‐perovskite crystals associated with palaeosubduction of the Pacific plate and Indian plate.
Solar activity dependence of geomagnetic field line resonance frequencies at low latitudes
Authors: Vellante M. , Förster M. , Villante U. , Zhang T. L. , Magnes W.
Published: February 2007

ULF field line resonance frequencies (fR) of three different magnetic shells (L = 1.61, 1.71, and 1.83) have been monitored during a 4‐year period (2001–2004) using a cross‐phase analysis of magnetic measurements recorded at the South European Geomagnetic Array (SEGMA). We find that the variations of the daily averages of fR, which reflect changes in plasmaspheric mass density, follow the variations of the daily values of the 10.7‐cm solar radio flux F10.7 with an estimated time delay of 1–2 days. The analysis of selected events indicates that the sensitivity of fR to short‐term (27‐day) variations in the solar flux is the same as that for long‐term (solar cycle related) variations. On the other hand, the results of the overall statistical analysis seem to indicate a lower sensitivity (by a factor of ∼2) of fR to short‐term solar flux variations with respect to long‐term variations. Geomagnetic activity effects and/or different solar variabilities of EUV and 10.7‐cm flux for different timescales are suggested as a possible cause for such a difference. Experimental results are also compared with those provided by a physical‐numerical model of the ionosphere‐plasmasphere system. Last, we find some evidence for a slight annual variation in fR with an estimated summer/winter ratio of ∼1.1–1.2. The inferred corresponding annual variation in the equatorial mass density is in line with previous estimates for the European longitudinal sector as obtained from whistler measurements.
Variability in horizontal current velocities in the central and eastern equatorial Atlantic in 2002
Authors: Bunge Lucia , Provost Christine , Kartavtseff Annie
Published: February 2007

Near‐surface current velocity data from the Pilot Research Moored Array in the Tropical Atlantic at 23°W in the year 2002 were re‐examined and compared to simultaneous unpublished velocity data at 10°W, near the surface. Strong 7‐day‐period fluctuations were observed in the zonal velocity component and in temperature records at 23°W. The large temperature fluctuations near the thermocline depth suggest a vertical velocity component at the same 7‐day period. The 7‐day‐period signals occurred in June/July simultaneously with the seasonal upwelling. The meridional velocity component presented similar spectral contents at 23°W and at 10°W. Two distinguishable quasiperiodic signals were observed in the meridional component at both locations: The first signal occurred in the spring, had a periodicity of about 14 days, was subsurface intensified, and had the characteristics of a mixed Rossby‐gravity wave. The second signal occurred three times in the year (once in winter 2001–2002, another in summer, and another during fall 2002), had a periodicity of about 20 days, was strongest close to the surface, and was the result of the passage of tropical instability waves (TIWs). Satellite sea surface temperature (SST) data show the same periodicities as the meridional velocity records, and present a spatial structure in accordance with the TIW‐SST signature. The summer of 2002 showed different TIW‐SST patterns depending upon location, suggesting the existence of different types of TIWs. Overall, variability in the current meter data for the year 2002 was mainly due to current instabilities, except around boreal spring, where intraseasonal variability in surface winds was strongest.
Interplanetary magnetic field and atmospheric electric circuit influences on ground‐level pressure at Vostok
Authors: Burns G. B. , Tinsley B. A. , Frank‐Kamenetsky A. V. , Bering E. A.
Published: February 2007

The Mansurov effect, which for the Southern Hemisphere consists of a positive association between the By component (east‐west) of the interplanetary magnetic field (IMF) and the ground‐level pressure for stations poleward of ∼80° magnetic latitude, is confirmed for Vostok (78.5°S, 106.9°E; magnetic latitude 83.6°S) using modern data. The magnitude of the association is small (0.19 hP per nT; 1.2% common covariance) but statistically significant (at the 96.1% level). A more substantial association exists, with a slight delay (2–3 days) and a cumulative influence, between the Vostok station pressure and the local vertical electric field, a proxy for the air‐Earth current Jz. A composite series constructed as a weighted sum of vertical electric field values at lags between 1 and 4 days yields a linear regression gradient with respect to Vostok station‐level pressure of 0.10 hP per Vm−1, 10.0% common covariance and is statistically significant at the 99.9% level. We confirm a previously reported Sun‐weather linkage (the Mansurov effect), provide evidence that the mechanism operates via the atmospheric electric circuit and present data supporting an inferred and more substantial surface pressure response to changes in the global atmospheric circuit.
Global spectral classification of Martian low‐albedo regions with Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) data
Authors: Rogers A. Deanne , Bandfield Joshua L. , Christensen Philip R.
Published: February 2007

Martian low‐albedo surfaces (defined here as surfaces with Mars Global Surveyor Thermal Emission Spectrometer (MGS‐TES) albedo values ≤0.15) were reexamined for regional variations in spectral response. Low‐albedo regions exhibit spatially coherent variations in spectral character, which in this work are grouped into 11 representative spectral shapes. The use of these spectral shapes in modeling global surface emissivity results in refined distributions of previously determined global spectral unit types (Surface Types 1 and 2). Pure Type 2 surfaces are less extensive than previously thought, and are mostly confined to the northern lowlands. Regional‐scale spectral variations are present within areas previously mapped as Surface Type 1 or as a mixture of the two surface types, suggesting variations in mineral abundance among basaltic units. For example, Syrtis Major, which was the Surface Type 1 type locality, is spectrally distinct from terrains that were also previously mapped as Type 1. A spectral difference also exists between southern and northern Acidalia Planitia, which may be due in part to a small amount of dust cover in southern Acidalia. Groups of these spectral shapes can be averaged to produce spectra that are similar to Surface Types 1 and 2, indicating that the originally derived surface types are representative of the average of all low‐albedo regions.
Opportunity rover localization and topographic mapping at the landing site of Meridiani Planum, Mars
Authors: Li Rongxing , Arvidson Raymond E. , Di Kaichang , Golombek Matt , Guinn Joe , Johnson Andrew , Maimone Mark , Matthies Larry H. , Malin Mike , Parker Tim , Squyres Steven W. , Watters Wesley A.
Published: February 2007

This paper presents the results of Mars topographic mapping and lander and rover localization for the Opportunity rover at Meridiani Planum during the Mars Exploration Rover (MER) 2003 mission. By Sol 458, the Opportunity rover traversed a distance of 5.20 km. We localized the lander using two‐way Doppler radio positioning and cartographic triangulation of craters visible in both orbital and ground images. Additional high‐resolution orbital images were taken to verify the determined lander position. Visual odometry and bundle adjustment techniques were applied to overcome wheel slippages, azimuthal angle drift, and other navigation errors (as large as 21% within Eagle crater). In addition, orbit‐to‐ground image‐based adjustment was applied to correct rover location errors where bundle adjustment was not applicable. We generated timely topographic products, including orthoimages, digital terrain models (DTMs), three‐dimensional (3‐D) crater models, and rover traverse maps. In particular, detailed 3‐D terrain models of major features, such as Endurance crater, have been generated using multisite panoramic stereo images based on bundle adjustment and wide baseline stereo technique.
Impact of rock uplift on rates of late Cenozoic Rocky Mountain river incision
Authors: Riihimaki Catherine A. , Anderson Robert S. , Safran Elizabeth B.
Published: February 2007

The high relief of the modern Rocky Mountain landscape formed in the late Cenozoic by downcutting of a fluvial network that links a series of easily eroded sedimentary basins across relatively resistant crystalline cores of adjacent ranges. Using a numerical model of fluvial erosion and the flexural isostatic response to the associated unloading, we first calculate the expected pattern and pace of incision caused by rock uplift related to migration of the Yellowstone hot spot and to growth of the northern portion of the Rio Grande rift. Calculated incision rates are <60 m/Myr, and total depth of erosion of sedimentary basins is <300 m, well below the long‐term incision rates and amounts of erosion interpreted from the geologic record. Broad‐scale tilting of the region toward the east, accomplished by a gradient in rock uplift of ∼1 km along the north‐south axis of the central Rockies, declining to zero 1000 km to the east, can account for the additional erosion needed to match observations. In each modeling scenario, stream incision is nonsteady, with rock uplift outpacing erosion for <1 Myr in perimeter basins and 1–5 Myr in interior basins. Three factors dominate the spatial and temporal pattern of regional landscape evolution: (1) the time since uplift began, (2) the uplift pattern, and (3) the distribution of relatively resistant bedrock within the region. Our results suggest that the spatial variability in late Cenozoic exhumation can be explained by a long‐lived transience in the stream network response to these various late Cenozoic geophysical events.
Basin‐scale soil moisture dynamics and the probabilistic characterization of carrier hydrologic flows: Slow, leaching‐prone components of the hydrologic response
Authors: Botter G. , Porporato A. , Rodriguez‐Iturbe I. , Rinaldo A.
Published: February 2007

This paper aims at a first theoretical step toward the probabilistic modeling of nutrient contents in catchment‐scale soil states. To this end, we wish to characterize probabilistically the slow, leaching‐prone component of the hydrologic response, which chiefly determines the export of dissolved nutrients from soil, as a result of interactions between mobile/immobile phases along the pathways of runoff formation. The influence of temporal fluctuations of soil moisture on slow components of the catchment‐scale runoff is thus investigated by means of a stochastic framework, where the intermittency of rainfall is modeled by a marked Poisson process with exponentially distributed intensities. The probability distribution of the relevant runoff components and its moment‐generating function are derived by coupling a stochastic description of soil moisture dynamics with a suitably simplified flow model. New exact solutions are achieved in two different cases, namely, when (1) infiltration rates are assumed proportional to the incoming rainfall depths, i.e., when surface runoff is negligible, and (2) infiltration rates are upwardly bounded by episodical soil saturations (e.g., for shallow soils). In both cases, the derived probability density functions of slow components of runoff are well described by a Gamma distribution, whose shape is controlled by the ratio between the runoff frequency and the inverse of the mean residence time of subsurface flow. The framework developed allows one to link the probabilistic structure of slow components of runoff with simple (pluviometric, soil, vegetation, and geomorphologic) macroscopic parameters, with implications for the ecohydrology of fluvial systems and for drought prediction in ungauged basins. Comparisons with Monte Carlo simulations of a more detailed rainfall‐runoff model to a real catchment located in northeastern Italy suggest the ability of the approach proposed to capture the main features of runoff probability distributions in heterogeneous catchments.
Universal scaling laws in surface water bodies and their zones of influence
Authors: Sagar B. S. Daya
Published: February 2007

Topologically, water bodies are the first‐level topographic regions that get flooded, and as the flood level gets higher, adjacent water bodies merge. The looplike network that forms along all these merging points represents zones of influence of each water body. These two topologically interdependent phenomena follow the universal scaling laws similar to certain other environmental and biological phenomena. Despite morphological variations, water bodies and their influence zones of varied sizes and shapes have different sets of scaling exponents, thereby determining that they belong to different universality classes.
Probing bactericidal mechanisms induced by cold atmospheric plasmas with Escherichia coli mutants
Authors: Perni Stefano , Shama Gilbert , Hobman J. L. , Lund P. A. , Kershaw C. J. , Hidalgo-Arroyo G. A. , Penn C. W. , Deng X. T. , Walsh J. L. , Kong M. G.
Published: February 2007

Mechanisms of plasma-induced microbial inactivation have commonly been studied with physicochemical techniques. In this letter, Escherichia coli K-12 and its ΔrecA, ΔrpoS, and ΔsoxS mutants are employed to discriminate effects of UV photons, OH radicals, and reactive oxygen species produced in atmospheric discharges. This microbiological approach exploits the fact that these E. coli mutants are defective in their resistance against various external stresses. By interplaying bacterial inactivation kinetics with optical emission spectroscopy, oxygen atoms are identified as a major contributor in plasma inactivation with minor contributions from UV photons, OH radicals, singlet oxygen metastables, and nitric oxide.
Length dependence of charge transport in oligoanilines
Authors: He Jin , Chen Fan , Lindsay Stuart , Nuckolls Colin
Published: February 2007

The conductance of aniline trimers, pentamers, and heptamers has been measured in a molecular junction as a function of the oxidation state of the molecules by making measurements under electrochemical potential control. The effective electronic decay length is too small to be consistent with simple tunnel transport in the neutral molecule and is even smaller in the oxidized molecule. Thus these molecules can act as relatively high conductance links even in the absence of the interchain hopping required for metallic behavior.
Spin wave spectroscopy and microwave losses in granular two-phase magnetic nanocomposites
Authors: Lutsev Leonid , Yakovlev Sergey , Brosseau Christian
Published: February 2007

We investigate the composition dependence of microwave properties of a series of cold-pressed powder compacts prepared from nanoparticles of ZnO, Ni, Co, and γ-Fe2O3 using the microstrip line method and spin wave spectroscopy (SWS). The microwave spectra of these magnetic nanocomposites (NCs) are found to possess a double-peak behavior in the losses over the 2–16GHz frequency range. The observed effect is most likely due to oxygen-containg species that were adsorbed at the surface of the NC leading to core/shell structured nanoparticles. The relative change of the SW group velocity induced by the samples, probed by SWS, is observed to depend significantly on the chemical composition and volume fraction of magnetic species contained in the NC. It is argued that the peaks in the losses have a magnetic character and are due to spin excitations of magnetic nanoparticles. Combined, the microwave characteristics of NCs are strongly influenced by the nature of the magnetic species and reveal opportunities for efficient nanomaterials in the realm of microwave magnetoelectric devices.
p
-type transparent conductor: Zn-doped CuAlS2
Authors: Liu Min-Ling , Huang Fu-Qiang , Chen Li-Dong , Wang Yao-Ming , Wang Ying-Hua , Li Gui-Feng , Zhang Qun
Published: February 2007

A series of Zn-doped CuAlS2 bulk samples was synthesized by spark plasma sintering, and the CuAl0.90Zn0.10S2 film was prepared on a glass substrate by channel spark ablation. Their electrical and optical properties were carefully investigated. A sharp increase in conductivity due to the enhancement of both Hall mobility and carrier concentration was observed with the introduction of Zn. p-type conduction was confirmed by both the positive Seebeck coefficient and Hall coefficient. The conductivity of the thin film is as high as 63.5Scm−1 at room temperature, and the average transmittance in the visible region is above 80%.
Structure and properties of epitaxial ferroelectric PbZr0.4Ti0.6O3∕PbZr0.6Ti0.4O3 superlattices grown on SrTiO3 (001) by pulsed laser deposition
Authors: Vrejoiu Ionela , Zhu Yinlian , Le Rhun Gwenaël , Schubert Markus Andreas , Hesse Dietrich , Alexe Marin
Published: February 2007

Ferroelectric epitaxial superlattices combining PbZr0.4Ti0.6O3 and PbZr0.6Ti0.4O3 ultrathin films were grown by pulsed laser deposition onto vicinal SrTiO3 (001) substrates. The superlattices were subjected to structural characterization by means of (high-resolution) transmission electron microscopy and x-ray diffraction, to piezoelectric-force microscopy, and to macroscopic ferroelectric measurements. The thickness of the individual PbZrxTi1−xO3 layers was found to play an important role in the overall structure adopted by the superlattices. Superlattices consisting of 22 bilayers of 5nm thin PbZr0.4Ti0.6O3 layers and 3nm thin PbZr0.6Ti0.4O3 layers involve continuous 90° a–c domains, indicating a uniform tetragonal structure.
Determination of the electron effective mass of wurtzite InN by coherent upper-branch A1(LO) phonon-plasmon coupling mode
Authors: Chang Y.-M. , Chu H. W. , Shen C.-H. , Chen H.-Y. , Gwo S.
Published: February 2007

Coherent A1(LO) phonon and its coupling with photoexcited plasmon in wurtzite InN were generated and detected with time-resolved second-harmonic generation. The experimental results directly reveal that the plasma damping time constant is about 60∼120fs, which depends on the photoexcited plasma density in InN. The frequency of the upper-branch A1(LO) phonon-plasmon coupling mode shifts as a function of the photoexcited plasma density. This frequency shift can be fitted consistently with different InN films by solving the InN dielectric response function and leads to the determination of the electron effective mass m‖*=(0.033±0.003)me, parallel to the c axis of wurtzite InN.
Resistance anomaly in disordered superconducting films
Authors: Hua J. , Xiao Z. L. , Rosenmann D. , Beloborodov I. , Welp U. , Kwok W. K. , Crabtree G. W.
Published: February 2007

The authors report on a resistance anomaly in disordered superconducting films containing arrays of irregularly distributed nanoscale holes. At high driving currents, peaks appear in the resistance as a function of temperature, with peak values up to 2% above the classic normal-state resistance. The authors attribute the observed resistance anomaly to dissipation-induced granularity which enhances the contributions from fluctuation-induced reduction of the density of states of the quasiparticles. The granular feature of a disordered superconducting film originates from the inhomogeneous temperature distribution caused by the variation of the local dissipation and/or heat transfer.
Corrected Article: “Ultraprecise microreproduction of a three-dimensional artistic sculpture by multipath scanning method in two-photon photopolymerization” [Appl. Phys. Lett 90, 013113 (2007)]
Authors: Yang Dong-Yol , Park Sang Hu , Lim Tae Woo , Kong Hong-Jin , Yi Shin Wook , Yang Hyun Kwan , Lee Kwang-Sup
Published: February 2007

Ultraprecise fabrication of three-dimensional (3D) microstructures comes up to be one of the most important issues in two-photon induced photopolymerization. To date, it has been difficult to fabricate 3D microstructures without any deformation due to the surface tension between a rinsing material and solidified microstructures during the developing process: In general, the surface tension significantly affects the precision of the resulting 3D microstructures. To overcome this problem, the authors propose a simple and effective laser scanning method to reinforce the strength of 3D microstructures without loss of precision. Overall, a complex 3D artistic sculpture such as “The Thinker” was reproduced in the controlled ultraprecise form, which shows that the proposed method enables the fabrication of 3D patterns with dramatically improved precision and stability.
How to Keep a Reversible Figure from Reversing: Teasing Out Top — Down and Bottom — Up Processes
Authors: Long Gerald M , Moran Cindy J
Published: February 2007

The nature of processes underlying our perception of reversible figures was examined through two experiments investigating the effects of prior exposure conditions on an observer's report of figural reversal. In experiment 1, observers were adapted over several minutes to an unambiguous version of a rotating Necker cube prior to the presentation of the standard ambiguous figure. Results indicated that adaptation produced an immediate bias to perceive the ambiguous figure in the opposite configuration (ie reverse bias) and to reduce reports of reversal over the test period. The introduction of a brief delay between the adaptation and test periods revealed that this bias is a highly transient effect and is only clearly evident when the adaptation and test figures are matched in size. In experiment 2, observers were primed with an unambiguous figure for a few seconds prior to the presentation of the standard ambiguous figure. In this case, the obtained bias strongly favored the observer's reporting the ambiguous figure to be in the same configuration as the adapting figure (ie positive bias); and neither introducing a delay period nor changing figure size had any effect. We conclude that these experiments reveal the distinct roles of transient, retinally localized neural processes as well as more stable, global processes under specifiable conditions.
Acute toxicity largely reflects the salinity sensitivity of stream macroinvertebrates derived using field distributions
Authors: Horrigan Nelli , Dunlop Jason E. , Kefford Ben J. , Zavahir Farah
Published: February 2007

Two types of salinity tolerance information are commonly used for assessing salinity risk to freshwater organisms. These are data from laboratory experiments, usually acute (≤96-h LC50) values, and field distributions. Both approaches have advantages and limitations, and their applicability to the formation of guidelines and assessment of risks is not clear. In the present study, the acute lethal tolerances (72-h LC50) and acute tolerance scores (ATS) of 37 macroinvertebrate families from Queensland, Australia, were compared with maximum field conductivities and previously derived salinity sensitivity scores (SSS). LC50 values were significantly correlated with maximal field conductivities and SSS. To investigate this relationship further, the changes in community structure related to an increase in salinity were assessed. A salinity index (SI) (based on cumulative SSS) and acute salinity index (ASI) (based on cumulative ATS) were calculated using an independent data set from south-east Queensland (429 samples) and compared with each other and actual conductivity levels. Both indices were significantly correlated with each other and followed a similar trend when plotted against actual conductivity. These results support the notion that salinity sensitivity of macroinvertebrates derived from acute toxicity experiments reflects sensitivities derived using field distributions. Definition of this relationship will allow the two sources of salinity sensitivity to be combined in a weight-of-evidence approach, resulting in a more robust data set with which to estimate safe salinity concentrations.
Immunosuppression in Sydney rock oysters (Saccostrea glomerata) and QX disease in the Hawkesbury River, Sydney
Authors: Butt Daniel , Raftos David
Published: February 2007

This study assessed links between host fitness, environmental change and opportunistic parasite infections in a dynamic estuary system. The Hawkesbury River in New South Wales is the most recent Sydney rock oyster growing area to experience outbreaks of infectious QX disease. This area was used to examine a relationship between the intensity of QX disease and inhibition of the oyster immune system. Oysters were grown at various sites along the river and periodically monitored for general condition, total haemolymph protein content, antibacterial capacity and phenoloxidase activity. Phenoloxidase activity was significantly inhibited during a key period of Marteilia sydneyi infectivity in late summer 2005. The degree to which phenoloxidase was inhibited strongly correlated with the intensity of M. sydneyi infection. The data suggest that the presence of some transient environmental stressor may have affected phenoloxidase activity during a key period of infection and increased the susceptibility of oysters to disease. These results provide further evidence for a specific relationship between decreased phenoloxidase activity and susceptibility to QX infection.
Bilayer deformation by the Kv channel voltage sensor domain revealed by self-assembly simulations
Authors: Bond Peter J. , Sansom Mark S. P.
Published: February 2007

Coarse-grained molecular dynamics simulations are used to explore the interaction with a phospholipid bilayer of the voltage sensor (VS) domain and the S4 helix from the archaebacterial voltage-gated potassium (Kv) channel KvAP. Multiple 2-μs self-assembly simulations reveal that the isolated S4 helix may adopt either interfacial or transmembrane (TM) locations with approximately equal probability. In the TM state, the insertion of the voltage-sensing region of S4 is facilitated via local bilayer deformation that, combined with side chain “snorkeling,” enables its Arg side chains to interact with lipid headgroups and water. Multiple 0.2-μs self-assembly simulations of the VS domain are also performed, along with simulations of MscL and KcsA, to permit comparison with more “canonical” integral membrane protein structures. All three stably adopt a TM orientation within a bilayer. For MscL and KcsA, there is no significant bilayer deformation. In contrast, for the VS, there is considerable local deformation, which is again primarily due to the lipid-exposed S4. It is shown that for both the VS and isolated S4 helix, the positively charged side chains of S4 are accommodated within the membrane through a combination of stabilizing interactions with lipid glycerol and headgroup regions, water, and anionic side chains. Our results support the possibility that bilayer deformation around key gating charge residues in Kv channels may result in “focusing” of the electrostatic field, and indicate that, when considering competing models of voltage-sensing, it is essential to consider the dynamics and structure of not only the protein but also of the local lipid environment.
Single-enzyme conversion of FMNH
2
to 5,6-dimethylbenzimidazole, the lower ligand of B
12
Authors: Gray Michael J. , Escalante-Semerena Jorge C.
Published: February 2007

The synthesis of 5,6-dimethylbenzimidazole (DMB), the lower ligand of coenzyme B
12
, has remained elusive. We report
in vitro
and
in vivo
evidence that the BluB protein of the photosynthetic bacterium
Rhodospirillum rubrum
is necessary and sufficient for catalysis of the O
2
-dependent conversion of FMNH
2
to DMB. The product of the reaction (DMB) was isolated by using reverse-phase high-pressure liquid chromatography, and its identity was established by UV-visible spectroscopy and MS. No metals were detected in homogeneous preparations of BluB, and the enzyme did not affect DMB synthesis from 4,5-dimethylphenylenediamine and ribose-5-phosphate. The effect of the lack of
bluB
function in
R. rubrum
was reflected by the impaired ability of a Δ
bluB
strain to convert Mg-protoporphyrin IX monomethyl ester (MPE) into protochlorophylide, a reaction of the bacteriochlorophyll biosynthetic pathway catalyzed by the MPE-cyclase enzyme present in this bacterium (BchE, EC 1.14.13.81), a predicted coenzyme B
12
-dependent enzyme. The growth defect of the Δ
bluB
strain observed under anoxic photoheterotrophic conditions was corrected by the addition of DMB or B
12
to the culture medium or by introducing into the strain a plasmid encoding the wild-type allele of
bluB
. The findings reported here close an important gap in our understanding of the enzymology of the assembly of coenzyme B
12
.