bluuebunny/crossref_metadata_2025 huggingface dataset:
Dose-dependent effects of docosahexaenoic acid-rich fish oil on erythrocyte docosahexaenoic acid and blood lipid levels
Authors: Milte Catherine M. , Coates Alison M. , Buckley Jonathan D. , Hill Alison M. , Howe Peter R. C.
Published: October 2007

Consumption of long-chainn-3 PUFA, particularly DHA, has been shown to improve cardiovascular risk factors but the intake required to achieve benefits is unclear. We sought to determine the relationship between DHA intake, increases in erythrocyte DHA content and changes in blood lipids. A total of sixty-seven subjects (thirty-six male, thirty-one female, mean age 53 years) with fasting serum TAG ≥ 1·1 mmol/l and BMI>25 kg/m2completed a 12-week, randomized, double-blind, placebo-controlled parallel intervention. Subjects consumed 2, 4 or 6 g/d of DHA-rich fish oil (26 % DHA, 6 % EPA) or a placebo (Sunola oil). Fasting blood lipid concentrations and fatty acid profiles in erythrocyte membranes were assessed at baseline and after 6 and 12 weeks. For every 1 g/d increase in DHA intake, there was a 23 % reduction in TAG (mean baseline concentration 1·9 (sem0·1) mmol/l), 4·4 % increase in HDL-cholesterol and 7·1 % increase in LDL-cholesterol. Erythrocyte DHA content increased in proportion to the dose of DHA consumed (r0·72,P < 0·001) and the increase after 12 weeks was linearly related to reductions in TAG (r− 0·38,P < 0·01) and increases in total cholesterol (r0·39,P < 0·01), LDL-cholesterol (r0·33,P < 0·01) and HDL-cholesterol (r0·30,P = 0·02). The close association between incorporation of DHA in erythrocytes and its effects on serum lipids highlights the importance of erythrocyte DHA as an indicator of cardiovascular health status.
Pensée 2: New Media and Old Agendas: The Internet in the Middle East and Middle Eastern Studies
Authors: ARMBRUST WALTER
Published: October 2007

My thoughts on the Internet were recently jogged by an experience with a slightly older medium, namely, satellite television. In late March 2007 I attended the Third Annual Al-Jazeera Forum, in Doha. Notwithstanding the attendance of a few academics like me, the forum was largely a networking opportunity for professional journalists, just as MESA is for professional Middle East studies academics. However, unlike MESA, forum presenters, as well as the audience, were handpicked. Even the expenses of the attendees were subsidized (my hotel bill was paid by al-Jazeera). This inevitably made the event an exercise in open self-promotion for al-Jazeera.
SHAPING THE SAUDI STATE: HUMAN AGENCY'S SHIFTING ROLE IN RENTIER-STATE FORMATION
Authors: Hertog Steffen
Published: October 2007

There are two established ways of recounting the emergence of the modern Gulf oil monarchies. The social scientific explanation describes anonymous structural forces, the “resource curse” of the “rentier state,” and how these have shaped politics and markets with their inexorable logic. The other narrative, of the popular history variety, offers romantic, personalized accounts of desert shaykhs, their whims, and the sudden riches of their families (complemented, in some less benevolent accounts, by tales of monumental corruption).
ORIGINS AND ARCHITECTS OF YEMEN'S JOINT MEETING PARTIES
Authors: Browers Michaelle
Published: October 2007

In November 2005, the secretary generals of Yemen's largest Islamist party, the Reform Gathering (al-Tajammuʿ al-Yamani li-l-Islah, hereafter Islah); of the Socialist Party (YSP) that ruled the south prior to unification; of the Popular Nasirist Unity Organization; and of a small party consisting largely of liberal Zaydi intellectuals, the Union of Popular Forces (UPF), announced the publication of “The Program of the Joint Meeting for Political and National Reform,” in a joint press conference. The conservative Zaydi Party, al-Haqq, also signed the document. In July 2006, these same five parties upped the ante of their alliance by nominating Faysal bin Shamlan, a former oil minister and independent member of parliament, to oppose President ʿAli ʿAbdullah Salih in the 2006 election. The composition of the oppositional alliance that has come to be known as the Joint Meeting Parties (Ahzab al-Liqaء al-Mushtarak [JMP]) is particularly surprising when one considers that since unification in 1990 the ruling General People's Conference (GPC) and President Salih have sought to pit the JMP's two main parties—the YSP and Islah—against each other through a process of allying with or bolstering one at the expense of the other. As recently as 1994, these two parties were literally killing each other in Yemen's war of succession.
PROBLEMATIZING A PALESTINIAN DIASPORA
Authors: Peteet Julie
Published: October 2007

The year 1948 marks the beginning of al-ghurba (exile or diaspora) and al-nakba (disaster or calamity), words intensely resonant in the Palestinian lexicon. After this decisive date, one can affix “pre-” or “post-” as markers of an apocalyptic moment. In this cultural and political orbit, a new spatial world took shape. Violently crafted and maintained borders that locked Palestinians in and kept them out became features of quotidian life. In 1948, through a combination of expulsion and flight, around 750,000 Palestinians became refugees in neighboring Arab countries. About 100,000 Palestinians remained in their homeland. The core issue, however, is not conditions of departure but denial of an internationally recognized right of return, as elaborated in United Nations General Assembly Resolution 194.
Dynamics of transient cavities
Authors: DUCLAUX V. , CAILLÉ F. , DUEZ C. , YBERT C. , BOCQUET L. , CLANET C.
Published: October 2007

We study the collapse of a transient cavity of air in water created by the impact of a solid body. Experimentally, we characterize the dynamics of the cavity from its creation (t= 0) until it collapses (t= τ) in the limit where inertia dominates viscous and capillary effects. Theoretically, we find in this regime an approximate analytical solution which describes the time evolution of the shape of the cavity. This theoretical solution predicts the existence of two different types of cavities that we also observe experimentally.
Contaminants in ventilated filling boxes
Authors: BOLSTER D. T. , LINDEN P. F.
Published: October 2007

While energy efficiency is important, the adoption of energy-efficient ventilation systems still requires the provision of acceptable indoor air quality. Many low-energy systems, such as displacement or natural ventilation, rely on temperature stratification within the interior environment, always extracting the warmest air from the top of the room. Understanding buoyancy-driven convection in a confined ventilated space is key to understanding the flow that develops with many of these modern low-energy ventilation schemes. In this work we study the transport of an initially uniformly distributed passive contaminant in a displacement-ventilated space. Representing a heat source as an ideal sourced of buoyancy, analytical and numerical models are developed that allow us to compare the average efficiency of contaminant removal between traditional mixing and modern low-energy systems. A set of small-scale analogue laboratory experiments was also conducted to further validate our analytical and numerical solutions.

We find that on average traditional and low-energy ventilation methods are similar with regard to pollutant flushing efficiency. This is because the concentration being extracted from the system at any given time is approximately the same for both systems. However, very different vertical concentration gradients exist. For the low-energy system, a peak in contaminant concentration occurs at the temperature interface that is established within the space. This interface is typically designed to sit at some intermediate height in the space. Since this peak does not coincide with the extraction point, displacement ventilation does not offer the same benefits for pollutant flushing as it does for buoyancy removal.
The effect of mass ratio and tether length on the flow around a tethered cylinder
Authors: RYAN K. , THOMPSON M. C. , HOURIGAN K.
Published: October 2007

A tethered cylinder may be considered an extension of the widely studied problem of a hydro-elastically mounted cylinder. Here we numerically investigate the flow past a positively buoyant tethered cylinder for a range of mass ratios and tether length ratios at a Reynolds numberRe= 200. The results are found to be qualitatively similar to related experimental work performed at significantly higher Reynolds numbers. Two important findings are related in this paper. First, we find that the action of the tethered cylinder oscillating at an angle to the flow induces a mean lift coefficient. Second, a critical mass ratio (m*crit) is found below which large-amplitude oscillations are noted, similar to that previously reported for the case of a hydro-elastically mounted cylinder. For short tether lengths, (m*crit) is significantly greater than that found for a hydro-elastically mounted cylinder. As the tether length increases, the (m*crit) decreases and asymptotes to that of a hydro-elastically mounted cylinder as the tether length approaches infinity.
Gridless simulations of splashing processes and near-shore bore propagation
Authors: LANDRINI M. , COLAGROSSI A. , GRECO M. , TULIN M. P.
Published: October 2007

The generation and evolution of two-dimensional bores in water of uniform depth and on sloping beaches are simulated through numerical solution of the Euler equations using the smoothed particle hydrodynamics (SPH) method, wherein particles are followed in Lagrangian fashion, avoiding the need for computational grids. In water of uniform depth, a piston wavemaker produces cyclically breaking bores in the Froude number range 1.37–1.82, which were shown to move at time-averaged speeds in very good agreement with the requirements of global mass and momentum conservation. A single Strouhal number for the breaking period was discovered. Complex repetitive splashing patterns are observed and described, involving forward jet formation growth, impact and ricochet, and similarly, backward jet formation and impact. Observed consequences were the creation of vortical regions of both signs, dipole creation through pairing, large-scale transport of surface water downward and high tangential scouring velocities on the bed, which are quantified. These bores are further allowed to rise on linear slopes to the shoreline, where they are seen to collapse into a tongue-like flow resembling dam-break evolution.

This essentially inviscid calculation is able to reproduce the development of a highly vortical flow in excellent agreement with experimental observations and theoretical concepts. The turbulent flow behaviour is partially described by the numerical solution.
Continuous parametric families of stationary and translating periodic point vortex configurations
Authors: O'NEIL KEVIN A.
Published: October 2007

The number of periodic arrangements of point vortices – point vortex streets – in two-dimensional fluid flow that are stationary is known to be finite for a generic choice of vortex circulations. When all circulations are the same in absolute value, however, stationary vortex street configurations have been associated with the zeros of certain trigonometric polynomials containing free complex parameters. The presence of these parameters may prove useful in constructing point vortex models of shear layers and wakes. In this paper it is shown that such a continuum of stationary configurations exists in a much wider class of point vortex street systems. The circulations may take on many values, not just two, providing increased flexibility in the modelling context. A simple method for computing these configurations is derived. The effects of symmetries on the solution polynomials are described, and illustrated with examples. In addition, novel translating vortex street configurations are found having arbitrary translation velocity and containing free parameters for vortex circulations ±1 and also for vortex circulations +1, −2.
Ion evaporation from Taylor cones of propylene carbonate mixed with ionic liquids
Authors: GUERRERO I. , BOCANEGRA R. , HIGUERA F. J. , DE LA MORA J. FERNANDEZ
Published: October 2007

A combined experimental and numerical approach is used to extract information on the kinetics of ion evaporation from the region of high electric field around the tip of a Taylor cone of the neutral solvent propylene carbonate (PC) mixed with two ionic liquids. On the numerical side, the electric field on the surface of the liquid is computed in the absence of evaporation by solving the electrohydrodynamic problem in this region within the framework of the leaky dielectric model. These computations justify the approximate (2% max error) scaling Emax = β Ek for the maximum electric field on the surface, with Ek = γ1/2 ϵ0−2/3 (K/Q)1/6 for 0.111 < K < 0.888 S m−1 and a numerical value of β ≈ 0.76. Here γ is the surface tension of PC, ϵ0 is the electrical permittivity of vacuum, and K and Q are the liquid electrical conductivity and flow rate. On the experimental side, 16 different propylene carbonate solutions with either of the ionic liquids 1-ethyl-3-methylimidazolium tetrafluoroborate (EMI-BF4) or EMI-bis(trifluoro-methylsulfonyl)imide (EMI-Im) are electrosprayed in a vacuum from a single Taylor cone, and their emissions of charged drops and ions are analysed by time-of-flight mass spectrometry at varying liquid flow rates Q. The sprays contain exclusively drops at large Q, both for small and for large electrical conductivities K, but enter a mixed ion–drop regime at sufficiently large K and small Q. Interestingly, the mixtures containing 10% and 15% (vol) EMI-Im exhibit no measurable ion currents at high Q, but approach a purely ionic regime (almost no drops) at small Q. The charge/mass ratio for the drops produced in these two mixtures increases continuously with decreasing Q, and gets very close to ionic values. Measured ion currents are represented versus computed maximum electric fields Emax on the liquid surface to infer ion evaporation kinetics. Comparison of measured ion currents with predictions from ion evaporation theory yields an anomalously low activation energy (~1.1 eV). This paradox appears to be due to alteration of the pure conj–eet electric field in the scaling laws used for the pure cone–jet regime, due to the substantial ion current density arising even when the ion current is relatively small. Elimination of this interference would require future ion current measurements in the 10–100 pA level. The electrical propulsion characteristics of the emissions from these liquids are determined and found to be excellent, particularly for 10% and 15% (vol) EMI-Im.
Passive wing pitch reversal in insect flight
Authors: BERGOU ATTILA J. , XU SHENG , WANG Z. JANE
Published: October 2007

Wing pitch reversal, the rapid change of angle of attack near stroke transition, represents a difference between hovering with flapping wings and with a continuously rotating blade (e.g. helicopter flight). Although insects have the musculature to control the wing pitch during flight, we show here that aerodynamic and wing inertia forces are sufficient to pitch the wing without the aid of the muscles. We study the passive nature of wing pitching in several observed wing kinematics, including the wing motion of a tethered dragonfly,Libellula pulchella, hovering fruitfly, hovering hawkmoth and simplified dragonfly hovering kinematics. To determine whether the pitching is passive, we calculate rotational power about the torsion axis owing to aerodynamic and wing inertial forces. This is done using both direct numerical simulations and quasi-steady fluid force models. We find that, in all the cases studied here, the net rotational power is negative, signifying that the fluid force assists rather than resists the wing pitching. To further understand the generality of these results, we use the quasi-steady force model to analyse the effect of the components of the fluid forces at pitch reversal, and predict the conditions under which the wing pitch reversal is passive. These results suggest the pitching motion of the wings can be passive in insect flight.
Accelerated flow past a symmetric aerofoil: experiments and computations
Authors: SENGUPTA T. K. , LIM T. T. , SAJJAN SHARANAPPA V. , GANESH S. , SORIA J.
Published: October 2007

Accelerated flow past a NACA 0015 aerofoil is investigated experimentally and computationally for Reynolds number Re = 7968 at an angle of attack α = 30°. Experiments are conducted in a specially designed piston-driven water tunnel capable of producing free-stream velocity with different ramp-type accelerations, and the DPIV technique is used to measure the resulting flow field past the aerofoil. Computations are also performed for other published data on flow past an NACA 0015 aerofoil in the range 5200 ≤ Re ≤ 35000, at different angles of attack. One of the motivations is to see if the salient features of the flow captured experimentally can be reproduced numerically. These computations to solve the incompressible Navier–Stokes equation are performed using high-accuracy compact schemes. Load and moment coefficient variations with time are obtained by solving the Poisson equation for the total pressure in the flow field. Results have also been analysed using the proper orthogonal decomposition technique to understand better the evolving vorticity field and its dependence on Reynolds number and angle of attack. An energy-based stability analysis is performed to understand unsteady flow separation.
Measuring Corruption: A Critique of Indicators in Eastern Europe and Central Asia
Authors: KNACK STEPHEN
Published: October 2007

Concern about corruption has stimulated the creation of a multiplicity of indicators by a multiplicity of methods by the World Bank, World Economic Forum, Transparency International and commercial rating agencies. However, the construction of indices varies, raising substantive and methodological issues, which are reviewed with particular reference to post-Communist transition societies in Eastern Europe and Central Asia. This paper systematically examines indicators, starting with the definitional distinction between measures of administrative corruption as distinct from state capture. It pays particular attention to problems arising from the aggregation of indicators from multiple sources, and the extent to which the changing composition of cross-country indicators limits trend analysis. It concludes that many of the problems of aggregation may be avoided by using single source and single dimension indexes.
Measuring Adherence in CBT for Psychosis: A Psychometric Analysis of an Adherence Scale
Authors: Rollinson Rebecca , Smith Ben , Steel Craig , Jolley Suzanne , Onwumere Juliana , Garety Philippa A. , Kuipers Elizabeth , Freeman Daniel , Bebbington Paul E. , Dunn Graham , Startup Mike , Fowler David
Published: October 2007

This paper reports the psychometric properties of a CBT for psychosis adherence scale, the Revised Cognitive Therapy for Psychosis Adherence Scale (R-CTPAS). The scale's factor structure, inter-rater reliability and concurrent validity were analysed in a sample of 67 audiotaped sessions of CBT for psychosis. The concurrent validity of the scale was examined through comparison with the Cognitive Therapy Scale (CTS, Young and Beck, 1980). Principal components analysis of the trial data suggested three factors: “engagement/assessment work”, “relapse prevention work” and “formulation/schema work”. Satisfactory levels of inter-rater reliability were established between rater dyads. Moderate correlations with the CTS provided an indication of concurrent validity. The R-CTPAS is concluded to be a reliable and useful instrument that can assess adherence to CBT for psychosis using the Fowler, Garety and Kuipers (1995) therapy model.
Deposition of Lignin Droplets Produced During Dilute Acid Pretreatment of Maize Stems Retards Enzymatic Hydrolysis of Cellulose
Authors: Selig Michael J. , Viamajala Sridhar , Decker Stephen R. , Tucker Melvin P. , Himmel Michael E. , Vinzant Todd B.
Published: October 2007

Electron microscopy of lignocellulosic biomass following high‐temperature pretreatment revealed the presence of spherical formations on the surface of the residual biomass. The hypothesis that these droplet formations are composed of lignins and possible lignin carbohydrate complexes is being explored. Experiments were conducted to better understand the formation of these “lignin” droplets and the possible implications they might have on the enzymatic saccharification of pretreated biomass. It was demonstrated that these droplets are produced from corn stover during pretreatment under neutral and acidic pH at and above 130 °C, and that they can deposit back onto the surface of residual biomass. The deposition of droplets produced under certain pretreatment conditions (acidic pH; T > 150 °C) and captured onto pure cellulose was shown to have a negative effect (5–20%) on the enzymatic saccharification of this substrate. It was noted that droplet density (per unit area) was greater and droplet size more variable under conditions where the greatest impact on enzymatic cellulose conversion was observed. These results indicate that this phenomenon has the potential to adversely affect the efficiency of enzymatic conversion in a lignocellulosic biorefinery.
Seasonal and interannual changes in particulate organic carbon export and deposition in the Chukchi Sea
Authors: Lepore K. , Moran S. B. , Grebmeier J. M. , Cooper L. W. , Lalande C. , Maslowski W. , Hill V. , Bates N. R. , Hansell D. A. , Mathis J. T. , Kelly R. P.
Published: October 2007

Particulate organic carbon (POC) export fluxes were estimated in the shelf‐slope region of the Chukchi Sea using measurements of 234Th−238U disequilibria and the POC/234Th ratio in large (>53‐μm) particles. These export fluxes were used in conjunction with rates of primary productivity and benthic carbon respiration to construct a POC budget for this shelf‐slope region. Samples were collected along a series of shelf‐basin transects in the spring (May–June) and summer (July–August) of 2004. These stations were previously occupied during the ice covered (spring) and open water (summer) seasons of 2002, allowing for an interannual comparison of export flux. In contrast to 2002, when open water POC fluxes were significantly higher than in the ice‐covered period, POC export fluxes in 2004 were similar during the spring (average = 19.7 ± 24.8 mmol C m−2 d−1) and summer (average = 20.0 ± 14.5 mmol C m−2 d−1). The high POC fluxes measured during the spring are attributed to a plankton bloom, as evidenced by exceptionally high rates of primary productivity (average = 124.4 ± 88.1 mmol C m−2 d−1). The shelf‐slope budget of particulate organic carbon indicates that 10–20% of primary productivity was exported below 50 m but was not consumed during benthic carbon respiration or burial and oxidation in underlying sediments. Furthermore, a water column−sediment budget of 234Th indicates that particulate material is retained in shelf sediments on a seasonal basis.
Observation and modeling of surface currents on the Grand Banks: A study of the wave effects on surface currents
Authors: Tang C. L. , Perrie W. , Jenkins A. D. , DeTracey B. M. , Hu Y. , Toulany B. , Smith P. C.
Published: October 2007

We investigate the effects of surface waves on surface currents using surface drifter data from the Grand Banks and a coupled current‐wave‐drifter model. The theoretical basis of the study is Jenkins' theory of wave‐current interaction in which wind‐generated surface currents are modified by wind‐wave and wave‐current momentum transfers. The total surface current is the sum of the wave modified current, the Stokes drift and the tidal current. Jenkins' formulation was incorporated into the Princeton Ocean Model and applied to the Labrador Sea and the adjacent shelves. The wave energy spectrum from Wavewatch III was used to calculate the momentum transfer and the Stokes drift. A series of model experiments were conducted to simulate the drifter trajectories and examine the sensitivity of the simulations to model parameters. The results show that the Stokes drift is the dominant wave effect, which increases the surface drift speeds by 35% and veers the currents toward the wind directions. The net effect of wind‐to‐wave and wave‐to‐current momentum transfers reduces the surface speeds by a few percent. A statistical analysis of the model currents and drifter data shows that the inclusion of the wave effects improves the model simulations significantly. Model errors due to uncertainties in the model parameters including the eddy viscosity, wave spectrum, air drag of the drifters, and bottom friction are investigated. The model surface currents are shown to be most sensitive to the surface eddy viscosity and the wave energy spectra.
Widespread pollution events of carbon monoxide observed over the western North Pacific during the East Asian Regional Experiment (EAREX) 2005 campaign
Authors: Sawa Yousuke , Tanimoto Hiroshi , Yonemura Seiichiro , Matsueda Hidekazu , Wada Akira , Taguchi Shoichi , Hayasaka Tadahiro , Tsuruta Haruo , Tohjima Yasunori , Mukai Hitoshi , Kikuchi Nobuyuki , Katagiri Syuichiro , Tsuboi Kazuhiro
Published: October 2007

Temporal variations of carbon monoxide (CO) were observed simultaneously at seven surface stations located in east Asia/western North Pacific from 24°N to 43°N during the East Asian Regional Experiment (EAREX) 2005 campaign in March 2005. Three major pollution events with enhanced CO levels were recorded around the same time at four stations over the East China Sea and at two northern stations of Japan. These pollution events were also observed 3–4 d later at Minamitorishima, located far from the Asian continent. A synoptic weather analysis showed that all of the major CO enhancements were brought about by the passages of cold fronts associated with the eastward migrating cyclonic development. The CO distribution simulated by a three‐dimensional transport model showed that the polluted air masses exported from the continent were trapped behind the cold fronts and then merged into elongated belts of enriched CO before spreading over the western North Pacific. Transport of regionally tagged CO tracer simulated by the model indicated that the Chinese and Korean emissions were the major contributors to the pollution over the East China Sea, while the Japanese emissions had impacts at relatively higher latitude regions during the campaign. The simulation results also showed that the CO enhancements detected at Minamitorishima were caused by a long‐range transport of pollution emissions from various regions in east Asia. The CO‐enriched plumes from Southeast Asia and south Asia emissions were found above the boundary layer in the frontal zone but not at the surface.
Biases of CO2 storage in eddy flux measurements in a forest pertinent to vertical configurations of a profile system and CO2 density averaging
Authors: Yang Bai , Hanson Paul J. , Riggs Jeffery S. , Pallardy Stephen G. , Heuer Mark , Hosman Kevin P. , Meyers Tilden P. , Wullschleger Stan D. , Gu Lian‐Hong
Published: October 2007

CO2 storage in a 30‐min period in a tall forest canopy often makes significant contributions to net ecosystem exchange (NEE) in the early morning and at night. When CO2 storage is properly measured and taken into account, underestimations of NEE on calm nights can be greatly reduced. Using CO2 data from a 12‐level profile at the Missouri Ozark flux site (an oak‐hickory forest in central Missouri, USA), we demonstrate that the lower canopy layer (below the thermal inversion) is a disproportionately large contributor to the total CO2 storage. This is because time derivative of CO2 density (Δc/Δt) generally shows increasing magnitude of mean and standard deviation with decreasing heights at night and from sunrise to 1000 h in both growing and dormant seasons. Effects of resolution and configuration in a profiling system on the accuracy of CO2 storage estimation are evaluated by comparing subset profiles to the 12‐level benchmark profile. It is demonstrated that the effectiveness of a profiling system in estimating CO2 storage is not only determined by its number of sampling levels but, more importantly, by its vertical configuration. To optimize a profile, one needs to balance the influence of two factors, Δc/Δt and layer thickness, among all vertical sections within a forest. As a key contributor to the total CO2 storage, the lower canopy requires a higher resolution in a profile system than the layers above. However, if the upper canopy is oversparsely sampled relative to the lower canopy, the performance of a profile system might be degraded since, in such a situation, the influence of layer thickness dominates over that of Δc/Δt. We also find that because of different level of complexity in canopy structure, more sampling levels are necessary at our site in order to achieve the same level of accuracy as at a boreal aspen site. These results suggest that in order to achieve an adequate accuracy in CO2 storage measurements, the number of sampling levels in a profile and its design should be subject to the site properties, e.g., canopy architecture and the resulted thermodynamic and flow structures. If CO2 density from a single profile is averaged in time and then used in assessing CO2 storage to reduce random errors, biases associated with this averaging procedure become inevitable. Generally, larger window sizes used in averaging CO2 density generate poorer estimates of CO2 storage. If absolute errors are concerned, it appears that the more significant the CO2 storage is during a period, the larger effects the averaging procedure has.
Geomorphic evidence for post‐10 Ma uplift of the western flank of the central Andes 18°30′–22°S
Authors: Hoke Gregory D. , Isacks Bryan L. , Jordan Teresa E. , Blanco Nicolás , Tomlinson Andrew J. , Ramezani Jahandar
Published: October 2007

The western Andean mountain front forms the western edge of the central Andean Plateau. Between 18.5° and 22°S latitude, the mountain front has ∼3000 m of relief over ∼50 km horizontal distance that has developed in the absence of major local Neogene deformation. Models of the evolution of the plateau, as well as paleoaltimetry estimates, all call for continued large‐magnitude uplift of the plateau surface into the late Miocene (i.e., younger than 10 Ma). Longitudinal river profiles from 20 catchments that drain the western Andean mountain front contain several streams with knickpoint‐bounded segments that we use to reconstruct the history of post‐10 Ma surface uplift of the western flank of the central Andean Plateau. The generation of knickpoints is attributed to tectonic processes and is not a consequence of base level change related to Pacific Ocean capture, eustatic change, or climate change as causes for creating the knickpoint‐bounded stream segments observed. Minor valley‐filling alluvial gravels intercalated with the 5.4 Ma Carcote ignimbrite suggest uplift related river incision was well under way by 5.4 Ma. The maximum age of river incision is provided by the regionally extensive, approximately 10 Ma El Diablo–Altos de Pica paleosurface. The river profiles reveal that relative surface uplift of at least1 km occurred after 10 Ma.
Asymptotic dispersion in 2D heterogeneous porous media determined by parallel numerical simulations
Authors: de Dreuzy Jean‐Raynald , Beaudoin Anthony , Erhel Jocelyne
Published: October 2007

We determine the asymptotic dispersion coefficients in 2D exponentially correlated lognormally distributed permeability fields by using parallel computing. Fluid flow is computed by solving the flow equation discretized on a regular grid and transport triggered by advection and diffusion is simulated by a particle tracker. To obtain a well‐defined asymptotic regime under ergodic conditions (initial plume size much larger than the correlation length of the permeability field), the characteristic dimension of the simulated computational domains was of the order of 103 correlation lengths with a resolution of ten cells by correlation length. We determine numerically the asymptotic effective longitudinal and transverse dispersion coefficients over 100 simulations for a broad range of heterogeneities σ2 ∈ [0, 9], where σ2 is the lognormal permeability variance. For purely advective transport, the asymptotic longitudinal dispersion coefficient depends linearly on σ2 for σ2 < 1 and quadratically on σ2 for σ2 > 1 and the asymptotic transverse dispersion coefficient is zero. Addition of homogeneous isotropic diffusion induces an increase of transverse dispersion and a decrease of longitudinal dispersion.
Objectives of public participation: Which actors should be involved in the decision making for river restorations?
Authors: Junker Berit , Buchecker Mattias , Müller‐Böker Ulrike
Published: October 2007

River restoration as a measure to improve both flood protection and ecological quality has become a common practice in river management. This new practice, however, has also become a source of conflicts arising from a neglect of the social aspects in river restoration projects. Therefore appropriate public involvement strategies have been recommended in recent years as a way of coping with these conflicts. However, an open question remains: Which stakeholders should be involved in the decision‐making process? This, in turn, raises the question of the appropriate objectives of public participation. This study aims to answer these questions drawing on two case studies of Swiss river restoration projects and a related representative nationwide survey. Our findings suggest that public involvement should not be restricted to a small circle of influential stakeholder groups. As restoration projects have been found to have a substantial impact on the quality of life of the local population, avoiding conflicts is only one of several objectives of the involvement process. Including the wider public provides a special opportunity to promote social objectives, such as trust building and identification of people with their local environment.
Observation of similar radio signatures at Saturn and Jupiter: Implications for the magnetospheric dynamics
Authors: Louarn P. , Kurth W. S. , Gurnett D. A. , Hospodarsky G. B. , Persoon A. M. , Cecconi B. , Lecacheux A. , Zarka P. , Canu P. , Roux A. , Rucker H. O. , Farrell W. M. , Kaiser M. L. , Andre N. , Harvey C. , Blanc M.
Published: October 2007

We report on radio signatures observed at Saturn by the Cassini RPWS experiment which are strikingly similar to the Jovian “energetic events” observed by Galileo. They consist of sudden intensifications of the auroral radio emission (SKR) followed by the detection of a periodic narrowband radiation which most likely originates from Saturn's plasma disk. About ten “events” have been observed in 2006, showing on average temporal scales ∼3 times longer than their Jovian counterparts. We analyze the conditions of generation and the visibility of the narrowband radiation and conclude that the Kronian “events” are most likely associated with plasma evacuation from the disk. These observations provide new insights on the role of internal energy releases in Saturn's magnetosphere, known from other observations to be mainly driven by the solar wind.
Demise of a submarine canyon? Evidence for highstand infilling on the Waipaoa River continental margin, New Zealand
Authors: Walsh J. P. , Alexander C. R. , Gerber T. , Orpin A. R. , Sumners B. W.
Published: October 2007

Submarine canyons are major geomorphologic features on the Earth's surface. Their formation has received considerable debate, but their demise has received less attention. Research of modern canyons with cores and moorings has documented active sediment transport and deposition, but extrapolation of these local observations over larger areas is precluded by complex canyon geomorphology. High‐resolution multibeam and chirp data presented here provide convincing evidence of an infilling canyon head on the Waipaoa River margin of New Zealand. Tens of meters of Holocene sediment have accumulated on the outer shelf and in Lachlan canyon as a result of off‐shelf sediment transport. Regardless of the ultimate fate of this system over geological time scales, this research demonstrates highstand sedimentation as a possible mechanism for canyon burial and cause of canyon demise, which has important implications for the evolution of canyons globally.
April 2007 collapse of Piton de la Fournaise: A new example of caldera formation
Authors: Michon Laurent , Staudacher Thomas , Ferrazzini Valérie , Bachèlery Patrick , Marti Joan
Published: October 2007

Collapse calderas are frequent in the evolution of volcanic systems, but very few have formed during historical times. Piton de la Fournaise is one of the world's most active basaltic shield volcanoes. The caldera collapse, which occurred during the April 2007 lateral eruption is one of the few large documented collapse events on this volcano. It helps to understand the mode and origin of caldera collapses in basaltic volcanoes. Field observations, GPS and seismic data show that the collapse occurred at an early stage of the eruption. The cyclic seismic signal suggests a step by step collapse that directly influenced the lateral eruption rate. Likely, the caldera results from the combined effect of (i) the progressive collapse of the plumbing system above the magma chamber since 2000, and (ii) the large amount of magma withdrawal during the early stage of the eruption by both a significant intrusion within the edifice and an important emission rate.
Interhourly variability index of geomagnetic activity and its use in deriving the long‐term variation of solar wind speed
Authors: Svalgaard Leif , Cliver Edward W.
Published: October 2007

We describe the detailed derivation of the interhourly variability (IHV) index of geomagnetic activity. The IHV index for a given geomagnetic element is mechanically derived from hourly values or means as the sum of the unsigned differences between adjacent hours over a 7‐hour interval centered on local midnight. The index is derived separately for stations in both hemispheres within six longitude sectors spanning the Earth using only local night hours. It is intended as a long‐term index and available data allows derivation of the index back well into the 19th century. On a timescale of a 27‐day Bartels rotation, IHV averages for stations with corrected geomagnetic latitude less than 55° are strongly correlated with midlatitude range indices (R2 = 0.96 for the am index since 1959; R2 = 0.95 for the aa index since 1980). We find that observed yearly averages of aa before the year 1957 are ∼3 nT too small compared to values calculated from IHV using the regression constants based on 1980–2004. We interpret this discrepancy as an indication that the calibration of the aa index is in error before 1957. There is no systematic discrepancy between observed and similarly calculated ap values back to 1932. Bartels rotation averages of IHV are also strongly correlated with solar wind parameters (R2 = 0.79 with BV2). On a timescale of a year combining the IHV index (giving BV2 with R2 = 0.93) and the recently developed interdiurnal variability (IDV) index (giving interplanetary magnetic field magnitude, B, with R2 = 0.74) allows determination of solar wind speed, V, from 1890 to present. Over the ∼120‐year series, the yearly mean solar wind speed varied from a low (inferred) of 303 km/s in 1902 to a high (observed) value of 545 km/s in 2003. The calculated yearly values of the product BV using B and V separately derived from IDV and IHV agree quantitatively with (completely independent) BV values derived from the amplitude of the diurnal variation of the horizontal component in the polar caps since 1926 (and sporadically further back).
A Kalman filter technique to estimate relativistic electron lifetimes in the outer radiation belt
Authors: Kondrashov D. , Shprits Y. , Ghil M. , Thorne R.
Published: October 2007

Data assimilation aims to smoothly blend incomplete and inaccurate observational data with dynamical information from a physical model, and has become an increasingly important tool in understanding and predicting meteorological, oceanographic and climate processes. As space‐borne observations become more plentiful and space‐physics models more sophisticated, dynamical processes in the radiation belts can be analyzed using advanced data assimilation methods. We use the Extended Kalman filter and observations from the Combined Release and Radiation Effects Satellite (CRRES) to estimate the lifetime of relativistic electrons during magnetic storms in the Earth's outer radiation belt. The model is a linear parabolic partial differential equation governing the phase‐space density. This equation contains empirical coefficients that are not well‐known and that we wish to estimate, along with the phase‐space density itself. The assimilation method is first verified on model‐simulated data, which allows us to reliably estimate the characteristic lifetime of the electrons. We then apply the methodology to CRRES measurements and show it to be useful in highlighting systematic differences between the parameter estimates for storms driven by coronal mass ejections (CMEs) and by corotating interaction regions (CIRs), respectively. These differences are attributed to the complex, competing effects of acceleration and loss processes during distinct physical regimes. The technique described herein may be applied next to constrain more sophisticated radiation belt and ring current models, as well as in other areas of magnetospheric physics.
Validation and understanding of Moderate Resolution Imaging Spectroradiometer aerosol products (C5) using ground‐based measurements from the handheld Sun photometer network in China
Authors: Li Zhanqing , Niu Feng , Lee Kwon‐Ho , Xin Jinyuan , Hao Wei‐Min , Nordgren Bryce , Wang Yuesi , Wang Pucai
Published: October 2007

The Moderate Resolution Imaging Spectroradiometer (MODIS) currently provides the most extensive aerosol retrievals on a global basis, but validation is limited to a small number of ground stations. This study presents a comprehensive evaluation of Collection 4 and 5 MODIS aerosol products using ground measurements from the Chinese Sun Hazemeter Network (CSHNET). The Collection 5 product uses a new method to determine the surface reflectance and a new aerosol model to retrieve aerosol optical thickness (AOT). Substantial improvement was found in the Collection 5 AOT product relative to the Collection 4 AOT product. Overall, the correlation coefficient of regression with ground measurements increased from 0.66 to 0.84 for all data points. The offset is reduced from 0.179 to 0.047, and the slope is improved from 0.74 to 0.98. At individual sites, the improvement varies with surface and atmospheric conditions. In general, both versions of the MODIS aerosol product tend to overestimate AOT over deserts/semideserts, tend to underestimate AOT over forests, and are more accurate over agricultural and suburban sites. The poorest retrievals occur over urban areas. The land cover dependence of aerosol retrievals was traced to the estimation of surface reflectance. The selection of the aerosol type is another major factor contributing to the discrepancies. Errors caused by both factors are subject to considerable variations with season and location due to land cover changes and varying fractions of coarse and fine mode aerosols, as well as the changing amount of scattering and absorbing aerosols.
A study of lunar contamination and on‐orbit performance of the NOAA 18 Advanced Microwave Sounding Unit–A
Authors: Mo Tsan , Kigawa Seiichiro
Published: October 2007

An algorithm for detection and correction of the lunar contamination in the Advanced Microwave Sounding Unit–A (AMSU‐A) data is applied to study the observed lunar contamination in the NOAA 18 AMSU‐A data. The algorithm is based on a physical model of the lunar surface brightness temperature and the AMSU‐A antenna pattern powers to detect the lunar contamination in cold space calibration counts over a large number of scans. The algorithm performs a scan‐by‐scan detection and correction of the effect of lunar contamination on the AMSU‐A data. It is found that the lunar contamination is significant only when the separation angle between the lunar disk and the antenna space viewing is less than 4°, beyond which no significant lunar contamination is detected, as the AMSU‐A antenna power drops below 40 dB from its peak. The parameters of the AMSU‐A antenna pattern powers are determined from least squares fit to the observed lunar contamination counts extracted from the cold space counts. Using the best fit parameters, we investigated the effect of the lunar contamination on the AMSU‐A scene temperatures. It is found that the differences ΔTS between the near‐nadir (field of view, FOV 16) scene antenna temperatures calculated with and without correction of lunar contamination vary with channels. It is about 1.5 K over ocean at channels 1 and 2 but only 0.38 K at channel 4. This trend in the ΔTS variation as a function of channels is easily understood by examining the two‐point calibration equation. The results presented in this study show that the lunar contamination in the AMSU‐A space calibration counts can be accurately detected and that its effect on the measured scene antenna temperatures can be corrected. The algorithm provides a practical approach for scan‐by‐scan correction of the lunar contamination in AMSU‐A data and improves the accuracy of operational calibration of NOAA Level 1B data. An assessment of the postlaunch instrument performance is also presented.
An improved broadband E patch microstrip antenna for wireless communications
Authors: Bzeih Amer , Chahine Soubhi Abou , Kabalan Karim Y. , El‐Hajj Ali , Chehab Ali
Published: October 2007

A broadband probe‐fed microstrip antenna with E‐shaped patch on a single‐layer air substrate is investigated. Bandwidth enhancement of the antenna is achieved by inserting two parallel slots into its radiating patch. The effects of the antenna parameters are analyzed, and their optimal values for broadband operation are obtained. The design parameters are formulated as a function of the center frequency, and the empirical equations are validated by simulation. A 51.5% enhanced E patch antenna for modern wireless communications (Personal Communications Service, Digital Cellular System, Universal Mobile Telecommunications System, Wireless Local Area Network 802.11 b/g, and Bluetooth) is designed, simulated, fabricated, and measured. A comparison between simulated and measured results is presented, and it showed satisfactory agreement. Moreover, the effect of incorporating more parallel slots into the radiating patch is investigated. The antenna is designed and simulated for different scenarios (four slots, six slots, and eight slots), where a bandwidth of 57% is achieved in the eight‐slot design.