bluuebunny/crossref_metadata_2025 huggingface dataset:
Increased SNR and reduced distortions by averaging multiple gradient echo signals in 3D FLASH imaging of the human brain at 3T
Authors: Helms Gunther , Dechent Peter
Published: December 2008

Purpose

To demonstrate how averaging of multiple gradient echoes can improve high‐resolution FLASH (fast low angle shot) magnetic resonance imaging (MRI) of the human brain.

Materials and Methods

3D‐FLASH with multiple bipolar echoes was studied by simulation and in three experiments on human brain at 3T. First, the repetition time (TR) was increased by the square of the flip angle to maintain contrast as derived by theory. Then the number of echoes was increased at constant TR with bandwidths between 110 and 1370 Hz/pixel. Finally, signals of a 12‐echo acquisition train (echo times 4.9–59 msec) were averaged consecutively to study the increase in SNR.

Results

At unchanged contrast, the signal increased proportionally with flip angle and sqrt(TR). Increasing the bandwidth improved delineation of the basal cortex and vessels, while most of the loss in the signal‐to‐noise ratio (SNR) was recovered by averaging. Consecutive averaging increased the SNR to reach maximum efficiency at an echo train length corresponding roughly to T.

Conclusion

SNR is gained efficiently by acquiring additional echoes and increasing TR (and flip angle accordingly to maintain contrast) until the associated T loss in the averaged signal consumes the sqrt(TR) increase in the steady state. A bandwidth of 350 Hz/pixel or higher and echo trains shorter than T are recommended. J. Magn. Reson. Imaging 2009;29:198–204. © 2008 Wiley‐Liss, Inc.
Aflatoxin occurrence in milk and supplied concentrates of goat farms of north‐eastern Italy
Authors: Saccà Elena , Boscolo Daria , Vallati Alberto , Ventura Walter , Bigaran Federico , Piasentier Edi
Published: December 2008

BACKGROUND:There is little information about the occurrence of aflatoxin M1in goat milk. A survey involving 17 dairy goat farms of north‐eastern Italy was completed during 2005 and 2006, in order to evaluate the prevalence of milk contamination and its relationship with type and level of concentrate supplied.

RESULTS:132 concentrate and 85 milk samples were collected during five farm visits and analysed for aflatoxins. Aflatoxin B1(AFB1) was > 0.1 µg kg−1in two‐thirds of the feeds and > 5 µg kg−1in nine. Contamination was higher in maize than in other pure feeds (median: 0.8versus0.1 µg kg−1); complementary feeds showed intermediate values. Aflatoxin M1(AFM1) was > 3 ng kg−1in one‐third of milks and > 25 ng kg−1in three. All the milk samples were below EU statutory limits. The farm ranks for milk AFM1level and the peak of concentrate AFB1contamination were significantly correlated (0.642).

CONCLUSIONS:Risk to human health was generally found to be absent, with only a few cases involving feed contamination to be monitored. The main aflatoxin risk for goat milk could arise from maize and maize‐based concentrates in the more intensive breeding conditions. Copyright © 2008 Society of Chemical Industry
Risk of acute myocardial infarction in patients treated with thiazolidinediones or other antidiabetic medications
Authors: Stockl Karen M. , Le Lisa , Zhang Shaoang , Harada Ann S.M.
Published: December 2008

Purpose

Controversy surrounds the question whether thiazolidinediones (TZDs) increase the risk of acute myocardial infarction (AMI). This study examined risk of AMI in patients with type 2 diabetes mellitus (T2DM) who were taking TZDs or other antidiabetic medications.

Methods

Using a nested case‐control design, a cohort of patients aged 18–84 years with T2DM and use of an oral antidiabetic medication or exenatide between January 2002 and June 2006 was identified. Cases of AMI were matched with up to four controls based on age, gender, health plan, geography, and diabetes therapy regimen. Over the 1‐year pre‐index period, TZD exposure was compared with no TZD exposure, after adjustment for potential confounders.

Results

Overall, 1681 cases were identified and matched with 6653 controls. Compared with no TZD exposure, an increased risk of AMI was not observed among TZD exposed patients (adjusted OR 1.01; 95%CI, 0.85–1.20; adjusted p = 0.98). When exposure proximity to the event was examined, the risk of AMI was significantly increased with recent rosiglitazone exposure between 1 and 60 days prior to the case date (adjusted OR 1.69; 95%CI, 1.18–2.44; adjusted p = 0.045) and was not significantly increased with current or remote rosiglitazone exposure or current, recent, or remote pioglitazone exposure.

Conclusion

TZD exposure did not increase the risk of AMI when exposure proximity was not considered. However, when evaluating exposure proximity to the event, the risk of AMI was increased with recent rosiglitazone exposure between 1 and 60 days prior to the case date. Copyright © 2008 John Wiley & Sons, Ltd.
The results of performance measurements of field‐aged crystalline silicon photovoltaic modules
Authors: Skoczek Artur , Sample Tony , Dunlop Ewan D.
Published: December 2008

This paper presents the results of electrical performance measurements of 204 crystalline silicon‐wafer based photovoltaic modules following long‐term continuous outdoor exposure. The modules comprise a set of 53 module types originating from 20 different producers, all of which were originally characterized at the European Solar Test Installation (ESTI), over the period 1982–1986. The modules represent diverse generations of PV technologies, different encapsulation and substrate materials. The modules electrical performance was determined according to the standards IEC 60891 and the IEC 60904 series, electrical insulation tests were performed according to the recent IEC 61215 edition 2. Many manufacturers currently give a double power warranty for their products, typically 90% of the initial maximum power after 10 years and 80% of the original maximum power after 25 years. Applying the same criteria (taking into account modules electrical performance only and assuming 2·5% measurement uncertainty of a testing lab) only 17·6% of modules failed (35 modules out of 204 tested). Remarkably even if we consider the initial warranty period i.e. 10% of Pmaxafter 10 years, more than 65·7% of modules exposed for 20 years exceed this criteria. The definition of life time is a difficult task as there does not yet appear to be a fixed catastrophic failure point in module ageing but more of a gradual degradation. Therefore, if a system continues to produce energy which satisfies the user need it has not yet reached its end of life. If we consider this level arbitrarily to be the 80% of initial power then all indications from the measurements and observations made in this paper are that the useful lifetime of solar modules is not limited to the commonly assumed 20 year. Copyright © 2008 John Wiley & Sons, Ltd.
Performance of a mesoscale liquid fuel‐film combustion‐driven TPV power system
Authors: Li Yueh‐Heng , Lien Yung‐Sheng , Chao Yei‐Chin , Dunn‐Rankin Derek
Published: December 2008

Combustion‐driven thermophotovoltaic (TPV) systems have obtained increasing attention in recent decades, but most studies have focused on developing narrowband photovoltaic cells and selective emitters. In terms of the heat source, conventional combustion configurations and light gaseous fuels are extensively utilized in macro‐ or meso‐scale TPV power systems to simplify thermal management and mechanical fabrication. As far as miniaturization is concerned, however, fuelling these systems with liquid hydrocarbons would provide inherent advantages of high energy density and low volatility. Liquid fuels also promise easy and safe fuel recharging for small‐scale power systems. In this paper, a central porous‐medium combustor was employed in a small scale TPV power system. The combustor incorporated an emitting chamber wall and a heat recuperator. The radiant efficiency and overall efficiency were compared using different liquid hydrocarbon fuels in the system. The electric output characteristics of the combustion driven TPV system have been investigated to demonstrate the feasibility of a GaSb cell‐based TPV power system and to provide design guidance for mesoscale liquid‐burning TPV systems. Copyright © 2008 John Wiley & Sons, Ltd.
Approach to peptide decorated micelles via RAFT polymerization
Authors: Liu Jingquan , Liu Huiyun , Boyer Cyrille , Bulmus Volga , Davis Thomas P.
Published: December 2008

Pyridyldisulfide (PDS) functionalized telechelic polymers of oligo(ethyleneglycol) acrylate (PEG‐A) and their amphiphilic triblock copolymers with styrene (St) were synthesized directly by reversible addition‐fragmentation chain transfer (RAFT) polymerization using a new bifunctional RAFT agent, S,S‐bis[α,α′‐dimethyl‐α″‐(2‐pyridyl disulfide) ethyl acetate] trithiocarbonate (BDPET). The homopolymerization of PEG‐A was found to be well controlled using BDPET (PDI < 1.2). The ABA triblock copolymers poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A) with narrow molecular weight distribution (PDI < 1.25) were synthesized using poly(PEG‐A) as a macro‐RAFT agent. UV‐vis spectroscopic analysis revealed that 85 mol % of poly(PEG‐A) and 78 mol % of poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A) retained PDS end group functionality. Micelles were observed to form from poly(PEG‐A)‐b‐poly(St)‐b‐poly(PEG‐A). The presence of PDS groups within the micelle corona was evidenced by UV‐vis spectroscopy and fluorescence spectroscopy. The PDS groups within the corona were then used to functionalize the micelles with a thiol group bearing model peptide, reduced glutathione, and a thiol modified fluorophore, rhodamine B, under mild reaction conditions. UV‐vis and fluorescence spectrocopies revealed that approximately 80% PDS groups from the amphiphilic copolymer were tethered within the micelle coronas and accessible to glutathione and fluorophore attachment. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 899–912, 2009
Homogeneous graft copolymerization and characterization of novel artificial glycoprotein: Chitosan‐poly(L‐tryptophan) copolymers with secondary structural side chains
Authors: Xiang Yan , Si Jiangju , Zhang Qi , Liu Yang , Guo Hong
Published: December 2008

A novel series of artificial glycoprotein, peptide‐chitosan copolymers with secondary structural side chain have been synthesized by ring‐opening polymerization of L‐tryptophan N‐carboxyanhydride under homogeneous conditions. Their chemical structures and polymerization degree (DP) were characterized by IR, 13C NMR, and XRD spectra. Distinctly secondary protein structure has been found in the poly‐L‐tryptophan side chains of copolymers and with the lengthening of side chain (i.e., the increase of DP at the same time), its conformations could transfer from β‐sheet to α‐helix. The content of α‐helix reaches about 41% when DP of polytryptophan is 22. The solubility of graft copolymers in polar solvent strongly depends on the length of poly‐L‐tryptophan side chains. Unique fluorescence emission at 360 nm has been observed in the glycopolymers and the intensity shows the positive‐correlation with the increasing of DP of polytryptophan. Importantly, the fluorescence effect can be quenched easily by the coordination with copper ions which provides the possibility on the biosensor design. In comparison with chitosan, glycopolymers also present impressively enhanced compressive strength and elastic modules when it is blended with epoxy E 44 to form epoxy‐copolymer hybrid resin. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 925–934, 2009
Polymerization and copolymerization of functionalized 2‐alkoxy‐1‐methylenecyclopropanes to form new polymers having alkoxy substituents
Authors: Takeuchi Daisuke , Inoue Akihisa , Ishimaru Fujio , Osakada Kohtaro
Published: December 2008

The polymers with functionalized alkoxy groups and with narrow molecular weight distribution (Mw/Mn < 1.12) are obtained from the living polymerization of 2‐alkoxy‐1‐methylenecyclopropanes using π‐allylpalladium complex, [(PhC3H4)Pd(μ‐Cl)]2, as the initiator. The polymers with oligoethylene glycol groups in the alkoxy substituent are soluble in water, and hydroboration of the CC double bond and ensuing addition of the OH groups to CN bond of alkyl isocyanate produce the polymers with urethane pendant groups. The reaction decreases solubility of the polymer in water significantly. Di‐ and triblock copolymers of the 2‐alkoxy‐1‐methylenecyclopropanes are prepared by consecutive addition of the two or three 2‐alkoxy‐1‐methylenecyclopropane monomers to the Pd initiator. The polymers which contain both hydrophobic butoxy or tert‐butoxy group and hydrophilic oligoethylene glycol group dissolve in water and/or organic solvents, depending on the substituents. The 1H NMR spectrum of poly(1a‐b‐1h) ((CH2C(CH2)CHOBu)n(CH2C(CH2)CH(OCH2CH2)3OMe)m) in D2O solution exhibits peaks because of the butoxy and CH2 hydrogen in decreased intensity, indicating that the polymer forms micelle particles containing the hydrophilic segments in their external parts. Aqueous solution of the polymer with a small amount of DPH (DPH = 1,6‐diphenyl‐1,3,5‐hexatriene) shows the absorbance due to DPH at concentration of the polymer higher than 5.82 × 10−5 g mL−1. Other block copolymers such as poly(1b‐b‐1h) and poly(1a‐b‐1g) also form the micelles that contain DPH in their core. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 959–972, 2009
Synthesis and properties of new dialkoxyphenylene quinoxaline‐based donor‐acceptor conjugated polymers and their applications on thin film transistors and solar cells
Authors: Lai Mei‐Hsiu , Chueh Chu‐Chen , Chen Wen‐Chang , Wu Jyh‐Lih , Chen Fang‐Chung
Published: December 2008

Synthesis, properties, and optoelectronic device applications of four new bis‐[4‐(2‐ethyl‐hexyloxy)‐phenyl]quinoxaline(Qx(EHP))‐based donor‐acceptor conjugated copolymers are reported, in which the donors are thiophene(T), dithiophene(DT), dioctylfluorene(FO), and didecyloxyphenylene(OC10). The optical band gaps (Eg) of PThQx(EHP), PDTQ(EHP), POC10DTQ(EHP), and PFODTQ(EHP) estimated from the onset absorption are 1.57, 1.65, 1.77, and 1.92 eV, respectively. The smallest Eg of PThQx(EHP) among the four copolymers is attributed to the balanced donor/acceptor ratio and backbone coplanarity, leading to a strong intramolecular charge transfer. The hole mobilities obtained from the thin film transistor (TFT) devices of PThQx(EHP), PDTQ(EHP), POC10DTQ(EHP), and PFODTQ(EHP) are 2.52 × 10−4, 4.50 × 10−3, 4.72 × 10−5, and 9.31 × 10−4 cm2 V−1 s−1, respectively, with the on‐off ratios of 2.00 × 104, 1.89 × 103, 4.07 × 103, and 2.30 × 104. Polymer solar cell based on the polymer blends of PFODTQ(EHP), PThQx(EHP), POC10DTQ(EHP), and PDTQ(EHP) with [6, 6]‐phenyl C61‐butyric acid methyl ester (PCBM) under illumination of AM1.5 (100 mW cm−2) solar simulator exhibit power conversion efficiencies of 1.75, 0.92, 0.79, and 0.43%, respectively. The donor/acceptor strength, molecular weight, miscibility, and energy level lead to the difference on the TFT or solar cell characteristics. The present study suggests that the prepared bis[4‐(2‐ethyl‐hexyloxy)‐phenyl]quinoxaline donor‐acceptor conjugated copolymers would have promising applications on electronic device applications. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 973–985, 2009
Morphology control of polyacrylonitrile (PAN) fibers by phase separation technique
Authors: Dong Ruijiao , Zhao Jiongxin , Zhang Youwei , Pan Ding
Published: December 2008

Based on the constructed theoretical ternary phase diagrams of water/dimethyl sulfoxide (DMSO)/polyacrylonitrile (PAN) terpolymer system, the phase separation behavior for PAN fibers preparation was investigated. Theoretical ternary phase diagrams were determined by the extended Flory‐Huggins theory. To investigate the temperature dependence of theoretical ternary phase diagrams, all binary interaction parameters at different temperatures were determined accurately and thoroughly revisited. From numerical calculations, it was found that a small quantity of water was needed to induce phase demixing. Meanwhile, the cloud point data of the system for more dilute PAN terpolymer solutions were determined by cloud point titration, and the cloud point data for more concentrated PAN terpolymer solutions were calculated by Boom's linearized cloud point (LCP) curve correlation. Furthermore, the morphology of PAN fibers was investigated by using scanning electron microscopy (SEM). With increasing the concentration of PAN terpolymer solutions as well as the quenching depth, the morphology of PAN fibers turns from large open channels to small bead‐like structures, accompanying with a reduction of the porosity of PAN fibers. Judging from our investigation, it was clear that the final morphology of PAN fibers was mainly determined by phase separation in fiber‐forming process. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 261–275, 2009
Study of the assembled morphology of aryl amide derivative and its influence on the nonisothermal crystallizations of isotactic polypropylene
Authors: Dong Mu , Guo Zhao‐Xia , Yu Jian , Su Zhi‐Qiang
Published: December 2008

The nonisothermal crystallization behaviors of isotactic polypropylene (iPP) with an aryl amide derivative TMB‐5 as β‐form nucleating agent has been investigated by differential scanning calorimetry, X‐ray diffraction, and polarized optical microscopy. The feature of crystallite morphology depends on concentration and thermal conditions. At low concentrations, TMB‐5 molecules aggregate into fibril structures and presented blunt exothermic peak with a shoulder at high temperature. The surface of these fibrils host active sites tailored for the nucleation of β‐iPP, represented by clusters of microcrystallites. With increasing concentration, αβ‐transcrystalline layer develops on the lateral surface of needle‐shaped TMB‐5. Enhanced multiple endotherms indicate the ensuing crystals are less perfect and easily transformed into more stable forms. © 2008 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 47: 314–325, 2009
Robust fitting for neuroreceptor mapping
Authors: Chang Chung , Ogden R. Todd
Published: December 2008

Among many other uses, positron emission tomography (PET) can be used in studies to estimate the density of a neuroreceptor at each location throughout the brain by measuring the concentration of a radiotracer over time and modeling its kinetics. There are a variety of kinetic models in common usage and these typically rely on nonlinear least‐squares (LS) algorithms for parameter estimation. However, PET data often contain artifacts (such as uncorrected head motion) and so the assumptions on which the LS methods are based may be violated. Quantile regression (QR) provides a robust alternative to LS methods and has been used successfully in many applications. We consider fitting various kinetic models to PET data using QR and study the relative performance of the methods via simulation. A data adaptive method for choosing between LS and QR is proposed and the performance of this method is also studied. Copyright © 2008 John Wiley & Sons, Ltd.
Plasma phospholipid fatty acids and CHD in older men: Whitehall study of London civil servants
Authors: Clarke Robert , Shipley Martin , Armitage Jane , Collins Rory , Harris William
Published: December 2008

Dietary fatty acids (FA) are the major determinants of blood lipids, and measurements of plasma phospholipid FA (PL-FA) composition that reflect the dietary intake of FA may provide insights into the relationships between diet and CHD. We assessed CHD mortality associations with PL-FA (SFA, PUFA and MUFA) levels measured in a nested case–control study of 116 cases of CHD death and 239 controls that were frequency-matched for age and employment grade. The participants had plasma levels of total cholesterol, LDL-cholesterol (LDL-C), HDL-cholesterol, apo B and apo A1, C-reactive protein (CRP) and fibrinogen recorded. SFA levels were significantly positively correlated with total cholesterol, LDL-C, apo B, CRP protein and fibrinogen. By contrast, phospholipid-PUFA were inversely associated with CRP, but not with any of the lipids. A higher SFA content (top v. bottom quarter) was associated with a 2-fold higher risk of CHD (OR and 95 % CI: OR 2·12; 95 % CI: 1·13, 3·99), and an equivalent difference in PUFA was associated with a halving in CHD risk (OR 0·49; 95 % CI: 0·26, 0·94), but MUFA was unrelated to CHD risk. These associations were substantially attenuated, after additional adjustment for lipids and inflammatory markers. Higher levels of saturated fat and lower levels of polyunsaturated fats were each associated with a higher risk of CHD in elderly men, and these associations were partly explained by their effects on blood lipids and biomarkers of inflammation.
School meals in French secondary state schools with regard to the national recommendations
Authors: Dubuisson Carine , Lioret Sandrine , Calamassi-Tran Gloria , Volatier Jean-Luc , Lafay Lionel
Published: December 2008

In 2001, a circular addressing both the composition of school meals and food safety issues was introduced in France to improve the nutrient composition of school meals and provided food-frequency guidelines to guarantee dietary balanced meals. The present study assesses the extent to which secondary state schools are familiar with and implement this circular. In 2005, a nationally representative sample of 1440 secondary state schools received a questionnaire on their catering service and the implementation of the circular's recommendations, and were requested to enclose all menus (lunches and dinners) served over 1 month. Menu analysis shows that progress is still required to achieve a meal composition in accordance with the food-group frequency guidelines appended to the circular. Some recommendations are followed by most of the schools, such as limiting high-fat products and providing plenty of raw fruits and vegetables, cooked vegetables and starchy foods. Other guidelines should be implemented further, especially with regard to the nutritional quality of main courses and dairy products, which are met by less than a third and a half of schools, respectively. Specific efforts are necessary for evening meals to ensure that the nutritional requirements of boarders are covered. Some recommendations, such as the food purchasing manager being trained in nutrition (38 % of schools) and the involvement of dietetic expertise when designing meals (6 %), seem to be linked to better dietary balance of meals. Implementation of the circular must therefore be promoted in schools and may require stronger regulatory nutrition standards and better cooperation between schools.
Influence of fungicide and sowing density on the growth and yield of two groundnut cultivars
Authors: NAAB J. B. , BOOTE K. J. , PRASAD P. V. V. , SEINI S. S. , JONES J. W.
Published: December 2008

Groundnut or peanut (Arachis hypogaea L.) is a valuable food and forage crop in West Africa. It is important to determine yield-limiting factors and to develop suitable management practices to improve groundnut productivity. The objective of the present research was to determine the influence of fungicide application at different sowing densities on growth, biomass and yield of early and late maturing groundnut under rainfed conditions. Two groundnut cultivars (Chinese, 90 days duration and Manipinter, 120 days duration) were grown at low (8 plants/m2), medium (12 plants/m2) and high density (20 plants/m2), with and without fungicide application, for two growing seasons (2004 and 2005). Data on leaf area index (LAI), light interception (LI) and total biomass were measured at different stages of crop development. Haulm (stem and leaf), pod and seed yields were measured at maturity. Fungicide application increased LAI, LI and total biomass of both cultivars from 65 days after sowing (DAS) until maturity. Fungicide application significantly increased pod and seed yields by 95 and 103%, respectively, on average. In both years, the long duration cultivar Manipinter had significantly greater LAI, LI and total biomass at later stages of crop development when compared with the short-duration cultivar Chinese. The growth and yield of both cultivars were significantly less at the lowest population density when compared with medium or high population densities. There was no significant difference between medium and high population densities in haulm, pod and seed yield at maturity. It is concluded that sowing a long-duration cultivar at a density of 12 plants/m2 with fungicide application significantly improved groundnut yields under rainfed conditions in Ghana.
Physical mechanism of the inverse energy cascade of two-dimensional turbulence: a numerical investigation
Authors: XIAO Z. , WAN M. , CHEN S. , EYINK G. L.
Published: December 2008

We report an investigation of inverse energy cascade in steady-state two-dimensional turbulence by direct numerical simulation (DNS) of the two-dimensional Navier–Stokes equation, with small-scale forcing and large-scale damping. We employed several types of damping and dissipation mechanisms in simulations up to 20482resolution. For all these simulations we obtained a wavenumber range for which the mean spectral energy flux is a negative constant and the energy spectrum scales ask−5/3, consistent with the predictions of Kraichnan (Phys. Fluids, vol. 439, 1967, p. 1417). To gain further insight, we investigated the energy cascade in physical space, employing a local energy flux defined by smooth filtering. We found that the inverse energy cascade is scale local, but that the strongly local contribution vanishes identically, as argued by Kraichnan (J. Fluid Mech., vol. 47, 1971, p. 525). The mean flux across a length scale ℓ was shown to be due mainly to interactions with modes two to eight times smaller. A major part of our investigation was devoted to identifying the physical mechanism of the two-dimensional inverse energy cascade. One popular idea is that inverse energy cascade proceeds via merger of like-sign vortices. We made a quantitative study employing a precise topological criterion of merger events. Our statistical analysis showed that vortex mergers play a negligible direct role in producing mean inverse energy flux in our simulations. Instead, we obtained with the help of other works considerable evidence in favour of a ‘vortex thinning’ mechanism, according to which the large-scale strains do negative work against turbulent stress as they stretch out the isolines of small-scale vorticity. In particular, we studied a multi-scale gradient (MSG) expansion developed by Eyink (J. Fluid Mech., vol. 549, 2006a, p. 159) for the turbulent stress, whose contributions to inverse cascade can all be explained by ‘thinning’. The MSG expansion up to second order in space gradients was found to predict well the magnitude, spatial structure and scale distribution of the local energy flux. The majority of mean flux was found to be due to the relative rotation of strain matrices at different length scales, a first-order effect of ‘thinning’. The remainder arose from two second-order effects, differential strain rotation and vorticity gradient stretching. Our findings give strong support to vortex thinning as the fundamental mechanism of two-dimensional inverse energy cascade.
Optimal transient growth and very large–scale structures in turbulent boundary layers
Authors: COSSU CARLO , PUJALS GREGORY , DEPARDON SEBASTIEN
Published: December 2008

The optimal energy growth of perturbations sustained by a zero pressure gradient turbulent boundary is computed using the eddy viscosity associated with the turbulent mean flow. It is found that even if all the considered turbulent mean profiles are linearly stable, they support transient energy growths. The most amplified perturbations are streamwise uniform and correspond to streamwise streaks originated by streamwise vortices. For sufficiently large Reynolds numbers two distinct peaks of the optimal growth exist, respectively scaling in inner and outer units. The optimal structures associated with the peak scaling in inner units correspond well with the most probable streaks and vortices observed in the buffer layer, and their moderate energy growth is independent of the Reynolds number. The energy growth associated with the peak scaling in outer units is larger than that of the inner peak and scales linearly with an effective turbulent Reynolds number formed with the maximum eddy viscosity and a modified Rotta–Clauser length based on the momentum thickness. The corresponding optimal perturbations consist of very large–scale structures with a spanwise wavelength of the order of 8δ. The associated optimal streaks scale in outer variables in the outer region and in wall units in the inner region of the boundary layer, in which they are proportional to the mean flow velocity. These outer streaks protrude far into the near wall region, having still 50% of their maximum amplitude at y+ = 20. The amplification of very large–scale structures appears to be a robust feature of the turbulent boundary layer: optimal perturbations with spanwise wavelengths ranging from 4δ to 15δ can all reach 80% of the overall optimal peak growth.
Visual observation of the bubble dynamics in normal4He, superfluid4He and superfluid3He–4He mixtures
Authors: ABE H. , MORIKAWA M. , UEDA T. , NOMURA R. , OKUDA Y. , BURMISTROV S. N.
Published: December 2008

In order to compare the bubble dynamics of various quantum liquids, we performed the visual observation of a sound-induced bubble in a normal liquid4He, pure superfluid4He, and superfluid3He–4He liquid mixtures of saturated and unsaturated3He concentrations. When an acoustic wave pulse was applied to these liquids under saturated vapour pressure, a macroscopic bubble was generated on the surface of a piezoelectric transducer. For all liquids, the size of the bubble increased, as a higher voltage was applied to the transducer at a fixed temperature. In the normal4He we observed a primary bubble surrounded with many small bubbles which ascended upward together. In contrast to normal phase, only one bubble was generated in the superfluid4He, and its shape proved to be highly irregular with an ill-defined surface. In the3He saturated superfluid mixture, we also observed a solitary bubble but with a nearly perfect spherical shape. The bubble in this mixture expanded on the transducer surface, grew to a maximum size of the order of 1 mm and then started shrinking. As the bubble detached from the transducer with shrinking, we clearly detected an origination of the upward jet flow which penetrated the bubble. The jet velocity in the liquid mixture was approximately 102–103times smaller than in water. At the final stage of the process we could sometimes observe a vortex ring generation. It is interesting that, though the bubble size and time scale of the phenomenon differ from those in water, the behaviour in the collapsing process had much in common with the simulation study of the vortex ring generation in water. In addition, for the mixture with the unsaturated3He concentration of about 25% at 600 mK, the shape of the upward jet was observed distinctly, using more precise measurement with shadowgraph method.
God's self-specification: his being is his electing
Authors: Smith Aaron T.
Published: December 2008

The article considers the relationship between divine will and being as revealed in election, particularly according to Karl Barth's unique formulation of the doctrine. It comes at the salient features of this relationship by way of a public disagreement between Bruce McCormack and Paul Molnar. In agreement with McCormack, the author contends, on the basis of Barth's provocative claim that Jesus Christ is not just object but subject of election, that we cannot speak of God's being apart from his will for humanity, and this from all eternity, or in God's most intimate primordiality. Yet echoing Molnar, this observation does not entail the logical priority of grace to being. The author argues that a thoroughgoing commitment to conceiving of the being of God in the act of electing means affirming the eternal simultaneity and indeed reciprocity of will and being, as Jesus Christ is the full and total revelation of both. One cannot serve as ground for the other. As such, a preferable way of construing election is as the decisive statement of Godself – the primordial, eternal iteration of God for humanity – or the specification of divine being.
‘Before Bloch there was Blumhardt’: a thesis on the origins of the theology of hope
Authors: Winn Christian T. Collins , Heltzel Peter Goodwin
Published: December 2008

When Jürgen Moltmann'sTheology of Hopefirst appeared in 1965, it was seen as ushering in a new era of theological thinking. Karl Barth, however, sharply criticised the work as too heavily dominated by a ‘principle of hope’ that he believed Moltmann had inherited from the Marxist philosopher Ernst Bloch. This interpretation has largely been taken as fact among interpreters of Moltmann's theology of hope. This has caused most interpreters to see his turn to panentheism and ecotheology inGod in Creation(1983) as being less of a shift of emphasis than a total change of trajectory or even break. There is evidence, however, that a different source contributed to the overall orientation of Moltmann's theology – an orientation that has remained throughout his life. This other source is the life and thought of the radical Schwäbean Pietists, Johann Christoph Blumhardt (1805–80) and his son Christoph Blumhardt (1842–1919). In this article the authors flesh out the thesis that the Blumhardts are the prior, deeper and more long-lasting influence on Moltmann by focusing on three key theological motifs that permeate his theology: 1) Christianity as eschatology; 2) the ‘theology of the earth’; and 3) the ethics of hope. Furthermore, they argue that when the ‘hidden’ influence of the Blumhardts is acknowledged, Moltmann's later ‘shift’ can be understood as essentially in continuity, rather than discontinuity, with his earlier thought.
Editorial: State of BLC
Authors: Green David , Li Ping , Meisel Jürgen , Silva-Corvalán Carmen
Published: December 2008

As Bilingualism: Language and Cognition (BLC) enters its 12th year of publication, we the editors of the journal are pleased to report to the BLC readers that the state of the journal is strong.
Perceived access to fruits and vegetables associated with increased consumption
Authors: Caldwell Erin M , Miller Kobayashi M , DuBow WM , Wytinck SM
Published: December 2008

Objective

To examine the association between fruit and vegetable access in the community and change in fruit and vegetable consumption among participants in community-based health promotion programmes.

Design

Fruit and vegetable consumption and perceived access to fresh fruit and vegetables were measured by self-administered questionnaires at programme start, end and 1-year follow-up. Community produce availability was determined by grocery store assessments measuring the display space devoted to fruit and vegetable offerings, as well as price, variety and freshness. A total of nine communities were studied; 130 participants completed the fruit and vegetable portions of the questionnaires and could be linked to grocery store assessments.

Results

Participants made modest but significant increases in fruit and vegetable consumption from programme start to end: the average increase was 2·88 (95 % CI 1·52, 4·25) servings weekly; the average increase from start to follow-up was 2·52 (95 % CI 1·09, 3·95) servings weekly. Greater perceived access to fruits and vegetables was significantly associated with higher increases in fruit and vegetable consumption from programme start to programme end. Greater availability of produce was associated with greater increases in fruit and vegetable servings from programme start to programme end as measured by store assessments.

Conclusions

Environmental factors, such as access to fruits and vegetables, can modify the effects of community interventions. Interventions with the goal of increasing fruit and vegetable consumption should consider focusing on increasing access to fresh fruits and vegetables in target communities. Similarly, researchers may want to study access as an intervention, not just a contextual variable.
Do dietary patterns in older men influence change in homocysteine through folate fortification? The Normative Aging Study
Authors: Knoops Kim TB , Spiro Avron , de Groot Lisette CPGM , Kromhout Daan , van Staveren Wija A , Tucker Katherine L
Published: December 2008

Objective

We aimed to describe the difference in B-vitamin intake and in plasma B-vitamin and homocysteine concentrations before and after folic acid fortification, in relation to dietary patterns.

Design

The Normative Aging Study (NAS) is a longitudinal study on ageing. Between 1961 and 1970, 2280 male volunteers aged 21–80 years (mean 42 years) were recruited. Dietary intake data have been collected since 1987 and assessment of plasma B vitamins and homocysteine was added in 1993.

Setting

Boston, Massachusetts, USA.

Subjects

In the present study, 354 men who had completed at least one FFQ and one measurement of homocysteine, both before and after the fortification period, were included.

Results

Three dietary patterns were identified by cluster analysis: (i) a prudent pattern, with relatively high intakes of fruit, vegetables, low-fat milk and breakfast cereals; (ii) an unhealthy pattern, with high intakes of baked products, sweets and added fats; and (iii) a low fruit and vegetable but relatively high alcohol intake pattern. Dietary intake and plasma concentrations of folate increased significantly (P < 0·05) among all dietary patterns after the fortification period. Homocysteine tended to decrease in supplement non-users and in subjects in the high alcohol, low fruit and vegetable dietary pattern (both P = 0·08).

Conclusions

After fortification with folic acid, folate intake and plasma folate concentration increased significantly in all dietary patterns. There was a trend towards greatest homocysteine lowering in the high alcohol, low fruit and vegetable group.
Multilevel modelling of sociodemographic predictors of various levels of anaemia among women in Mali
Authors: Ngnie-Teta Ismael , Kuate-Defo Barthelemy , Receveur Olivier
Published: December 2008

Objective

Anaemia currently affects 40–80 % of women in Africa. While risk factors for anaemia have been intensively studied, research has rarely compared risk factors between mild anaemia and moderate/severe anaemia. Also, the contribution of neighbourhood to the prevalence of anaemia has been rarely studied. The aim of the present study was to identify and compare individual and contextual factors associated with various levels of anaemia among women.

Design

A multilevel analysis of data from the 2001 Mali Demographic and Health Survey (n3763) was carried out. Outcomes variables were mild anaemia, moderate-to-severe anaemia and any anaemia. Multilevel regression analyses were performed for each outcome.

Setting

Mali, West Africa.

Subjects

Women (n3763) aged 15 to 49 years, including 512 pregnant women.

Results

Among the eleven potential risk factors included in the models, two factors were associated with mild anaemia (BMI and education), three with any anaemia (pregnancy, BMI and education) and six with moderate-to-severe anaemia (pregnancy, BMI, education, wealth, childhood residency and region of residence). Clustering of anaemia within communities was 20 % for moderate-to-severe anaemia and 13 % for mild anaemia. Despite significant differences in the prevalence of anaemia across regions in Mali, no difference between regions in the risk of mild anaemia was found and only the region of Gao showed a significantly higher risk of moderate-to-severe anaemia.

Conclusions

The findings indicate that sociodemographic risk factors as well as clustering of anaemia varies with the severity of anaemia. Specific studies are needed to identify risk factors of mild anaemia as well as its consequences, as mild anaemia accounts for 20–40 % of total prevalence of anaemia in Africa.
Stochastic control of reservoir systems using indicator functions: New enhancements
Authors: Fletcher S. G. , Ponnambalam K.
Published: December 2008

In our previous works, deterministic release policies were considered for the development of approximations of the two lower moments of the storage volume defined by the dynamic equation of the reservoir in discrete time but in continuous state space. Important innovation in that work was the incorporation of the lower and upper bounds of reservoir systems into the dynamic equation for the storage volume using indicator functions. The current work, which also does not use discretization, looks at an extension of previous developments that incorporates standard operating policies, and also a new randomized release policy, both of which make the moments calculations exact under the assumptions that (1) the sum of current random inflow and the previous storage volume can be described by just the two lower moments and (2) only the means and variances of the inflows are known. First‐ and second‐moment expressions are derived for the stochastic storage state variable and include terms for the failure probabilities (probabilities of spills or deficits). Expected values of the storage state, variances of storage, release policies, and failure probabilities are obtained by solving the optimal reservoir operations problem using nonlinear programming. The various statistics thus obtained from this optimization compare extremely well with those obtained from simulation for the single‐reservoir monthly operations problem studied. The exact characterization of the mean and variance of the storage state variable is derived, which is a difficulty in existing formulations based on linear quadratic Gaussian methods. For example, the latter methods have been unable to estimate these moments reasonably accurately, especially for long‐term operations, whereas the traditional storage theory based on discretization brings on the “curse of dimensionality.” The presentation herein is directed to both traditional reservoir storage theorists who are interested in the design of a reservoir where estimating the probabilities of spills and deficits is important and modern reservoir analysts who are interested in multiperiod optimal release decisions in the operations of reservoirs.
Mechanical sensitivity to hydrochemical processes of Monastero Bormida clay
Authors: Musso G. , Chighini S. , Romero E.
Published: December 2008

The paper presents the results of an experimental study on the mechanical behavior of a marly clay, motivated by the recurrent episodes of slope failure induced by intense rainfall events over the area of Langhe (NW Italy). The sensitivity of the material to environmental actions has been systematically explored by reproducing on laboratory samples hydrological and chemical processes similar to those expected to arise on site. Chemomechanical effects due to pore fluid dilution and decalcification have been investigated by testing both reconstituted and intact samples with different degrees of weathering. Pore water salinity was found to have minor consequences on the mechanical behavior of the material at its intact state and at the original calcite content. Decalcification enhanced the chemical sensitivity of the clay minerals constituting the soil matrix, not only by affecting the residual shear strength and the stiffness, but also by magnifying the tendency to swell under chemical loads, inducing a chemical sensitivity over swelling on saturation and enhancing water retention properties. Field observations also support the hypothesis that decalcification followed by interstitial pore water dilution are key factors to take into account to understand the degradation of the mechanical properties and that these phenomena can enhance the instability onset.
A two‐dimensional hybrid method for modeling seismic wave propagation in anisotropic media
Authors: Zhao Liang , Wen Lianxing , Chen Ling , Zheng Tianyu
Published: December 2008

A hybrid method is developed for calculating synthetic seismograms for seismic waves propagating in two‐dimensional localized heterogeneous anisotropic media. The hybrid method is a combination of analytic and numerical methods, with the numerical method (finite difference, or FD) applied in the heterogeneous anisotropic region only and the analytic method (generalized ray theory, or GRT) outside. The GRT solutions from a seismic source are interfaced with the FD calculation at the boundaries of the anisotropic region; and seismic responses at the Earth's surface are obtained from the output of FD calculation. Synthetic experiments on both isotropic and anisotropic models demonstrate the validity of the new method in simulating seismic wave propagation in complex media. We applied the hybrid method to study the SKS wave propagation in the upper mantle. We calculated the synthetics for a series of laterally varying anisotropic models, including a layer with varying anisotropy, two‐layer anisotropy, separated anisotropic body and those may be related to subduction zones. For these laterally varying models, SKS waveforms exhibit higher sensitivity to the spatial variation of anisotropy than the shear wave splitting parameters do. The results of this study demonstrate the potential of the proposed hybrid method for high‐resolution imaging the laterally varying anisotropic structures from seismological observations, when the tectonic structures can be approximated as two‐dimensional.
Tailward flow of energetic neutral atoms observed at Mars
Authors: Galli A. , Wurz P. , Kallio E. , Ekenbäck A. , Holmström M. , Barabash S. , Grigoriev A. , Futaana Y. , Fok M.‐C. , Gunell H.
Published: December 2008

The ASPERA‐3 experiment on Mars Express provides the first measurements of energetic neutral atoms (ENAs) from Mars. These measurements are used to study the global structure of the interaction of the solar wind with the Martian atmosphere. In this study we describe the tailward ENA flow observed at the nightside of Mars. After characterizing energy spectra of hydrogen ENA signals, we present composite images of the ENA intensities and compare them to theoretical predictions (empirical and MHD models). We find that the tailward flow of hydrogen ENAs is mainly generated by shocked solar wind protons. Despite intensive search, no oxygen ENAs above the instrument threshold are detected. The results challenge existing plasma models and constrain the hydrogen exospheric densities and atmospheric hydrogen and oxygen loss rates at low solar activity.