bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of Crosslinking Methods on Structure and Properties of Cellulose/PVA Hydrogels
Authors: Chang Chunyu , Lue Ang , Zhang Lina
Published: May 2008

A series of hydrogels were prepared from cellulose and PVA in NaOH/urea aqueous solution using both physical and chemical crosslinking methods. The hydrogels were secure and biodegradable materials. Their structure and properties were characterized by FTIR spectroscopy, DSC, XRD and SEM. The results indicated that all of the cellulose/PVA hydrogels exhibited homogeneous porous structures and a certain miscibility. The swelling degree and water uptake of the chemical hydrogels were markedly higher than those of the physical hydrogel. This work demonstrates two novel methods to prepare cellulose/PVA hydrogels with different functional properties via a green process.

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The ProteoMiner and the FortyNiners: Searching for gold nuggets in the proteomic arena
Authors: Righetti Pier Giorgio , Boschetti Egisto
Published: May 2008

The present review covers modern aspects of combinatorial peptide ligand libraries (CPLL), as used to analyze the “low‐abundance proteome” in association with mass spectrometry. First, the capturing properties of baits of different lengths (from single amino acid to hexa‐peptides) are described to show that a plateau is rapidly reached above a tetra‐peptide in length, thus confirming the validity of having adopted hexapeptides for the considered application. The mechanism of interaction with proteins from very complex proteomes and the ability to decrease the dynamic concentration range is demonstrated with the help of mass spectrometry analysis. Examples are given on how treatment with CPLLs dramatically improves the detectability of peptides in mass spectrometry analysis, permitting detection of a very large number of proteins as compared with control, untreated samples. The use of complementary libraries is discussed with the aim to discover additional low‐abundance species that escaped the first library. A discussion on the possibility to discover extremely rare gene products, and the quantitative aspect of the technology when associated with mass spectrometry is also provided. Some insights on the applications for hidden, low‐abundance biomarkers are also presented. © 2008 Wiley Periodicals, Inc., Mass Spec Rev 27: 596–608, 2008
Making something of it: one ward's application of evidence into practice
Authors: Hooke Natalie , Lewis Peter , Kelly Margaret , Wilson Valerie , Jones Susan
Published: May 2008

Implementing evidence into practice can be a challenging and time consuming process for clinical teams. We conducted a qualitative study of the experiences of care for children, parents and nurses on an inpatient ward at a tertiary paediatric referral hospital in Sydney, Australia. We considered the conduct of the research to be only one step in a process of change commenced before the initiation of the research project and continuing well after its conclusion. The subsequent step was to share what we had learned with ward staff to enable them to act to improve the experience of care for everybody. This article reports the place of the project in the overall program of change on the ward, the strategies undertaken to share the finding of the research and the ongoing steps being undertaken to translate the research findings into improvements in care. Although the process is incomplete, it continues to gather momentum as the staff celebrate their achievements to date and look for new ways to proceed into the future. Copyright © 2008 John Wiley & Son, Ltd.
Factors affecting product distributions in ethylene/styrene copolymerization by (aryloxo)(cyclopentadienyl)titanium complexes‐MAO catalyst systems
Authors: Nomura Kotohiro , Zhang Hao , Byun Doo‐Jin
Published: May 2008

Ethylene/styrene copolymerizations using Cp′TiCl2(O‐2,6‐iPr2C6H3) [Cp′ = Cp* (C5Me5, 1), 1,2,4‐Me3C5H2 (2), tert‐BuC5H4 (3)]‐MAO catalyst systems were explored under various conditions. Complexes 2 and 3 exhibited both high catalytic activities (activity: 504–6810 kg‐polymer/mol‐Ti h) and efficient styrene incorporations at 25, 40°C (ethylene 6 atm), affording relatively high molecular weight poly (ethylene‐co‐styrene)s with unimodal molecular weight distributions as well as with uniform styrene distributions (Mw = 6.12–13.6 × 104, Mw/Mn = 1.50–1.71, styrene 31.7–51.9 mol %). By‐productions of syndiotactic polystyrene (SPS) were observed, when the copolymerizations by 1–3‐MAO catalyst systems were performed at 55, 70 °C (ethylene 6 atm, SPS 9.0–68.9 wt %); the ratios of the copolymer/SPS were affected by the polymerization temperature, the [styrene]/[ethylene] feed molar ratios in the reaction mixture, and by both the cyclopentadienyl fragment (Cp′) and anionic ancillary donor ligand (L) in Cp′TiCl2(L) (L = Cl, O‐2,6‐iPr2C6H3 or N=CtBu2) employed. Co‐presence of the catalytically‐active species for both the copolymerization and the homopolymerization was thus suggested even in the presence of ethylene; the ratios were influenced by various factors (catalyst precursors, temperature, styrene/ethylene feed molar ratio, etc.). © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4162–4174, 2008
Synthesis and chiral recognition properties of poly(N‐propargylamide) gels derived from ornithine and lysine
Authors: Liu Ruiyuan , Sanda Fumio , Masuda Toshio
Published: May 2008

Copolymerization of ornithine‐ and lysine‐derived N‐propargylamides, N‐α‐tert‐butoxycarbonyl‐N‐δ‐fluorenylmethoxycarbonyl‐L‐ornithine N′‐propargylamide (1), N‐α‐tert‐butoxycarbonyl‐N‐ε‐fluorenylmethoxycarbonyl‐L‐lysine N′‐propargylamide (2), N‐α‐fluorenylmethoxycarbonyl‐N‐δ‐tert‐butoxycarbonyl‐L‐ornithine N′‐propargylamide (3), and N‐α‐fluorenylmethoxycarbonyl‐N‐ε‐tert‐butoxycarbonyl‐L‐lysine N′‐propargylamide (4) with dipropargyl adipate was carried out using (nbd)Rh+[η6‐C6H5B−(C6H5)3] as a catalyst in THF to obtain polymer gels in 80–93% yields. The gels adsorbed N‐benzyloxycarbonyl L‐alanine, N‐benzyloxycarbonyl L‐alanine methyl ester, and (S)‐(+)‐1‐phenyl‐1,2‐ethanediol preferably than the corresponding optical isomers. The order of chiral discrimination was poly(1) > poly(4) > poly(2), poly(3) gels. The fluorenylmethoxycarbonyl groups of the gels could be partly removed by piperidine treatment, leading to increase of adsorptivity but decrease of chiral recognition ability. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4175–4182, 2008
Grafting of hyperbranched cyclotriphosphazene polymer onto silica nanoparticle and carbon black surfaces
Authors: Wei Gang , Sasage Nozomu , Kusanagi Yusuke , Fujiki Kazuhiro , Yamauchi Takeshi , Tsubokawa Norio
Published: May 2008

The surface grafting of hyperbranched cyclotriphosphazene polymer onto silica nanoparticles and carbon black was investigated. The grafting of hyperbranched cyclotriphosphazene polymer onto these surfaces was achieved by the repeated reactions of hexachlorocyclotriphosphazene with hexamethylenediamine from surface amino groups and sodium carboxylate groups, respectively. The percentage of grafting onto silica and carbon black surfaces exceeded 760 and 390%, respectively. However, it proved difficult to achieve the theoretical growth of cyclotriphosphazene polymer from these surfaces because of steric hindrance. The introduction of sulfonic acid groups was successfully achieved by the reaction of terminal chlorophosphazene groups of the hyperbranched polymer‐grafted silica and carbon black with sulfanilic acid. The content of sulfonic acid groups introduced onto silica and carbon black surfaces was 4.98 mmol/g and 5.70 mmol/g, respectively. The sulfonated cyclotriphosphazene polymer‐grafted carbon black was extremely hydrophilic, yielding stable colloidal dispersions in polar solvents. The sulfonated cyclotriphosphazene polymer‐grafted silica and carbon black showed ionic conductivity, with the conductance increasing exponentially with increasing relative humidity and temperature. This study may offer important leads in the application of silica nanoparticles and carbon black in polymeric membranes for fuel cells. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 4218–4226, 2008
Nonequilibrium valley polarization in graphene nanoconstrictions
Authors: Rycerz A.
Published: May 2008

We recently showed, using tight‐binding calculations, that nonequilibrium valley polarization can be realized in graphene, when the current is injected through a “valley filter”: a ballistic point contact with zigzag edges. Here we demonstrate that the effect is surprisingly robust against changing the crystallographic orientation of the filter axis. Namely, the output current remains polarized unless a point contact has perfect armchair edges, at which two sublattices are equally represented. The polarization is inverted when the filter orientation crosses the armchair line and, subsequently, the dominating sublattice index of the terminal atoms changes. In a bent graphene strip, the valley‐polarized current can be directed towards one edge providing a theoretical possibility to observe a zero‐magnetic‐field analogue of the well‐known Hall effect. For the valley valve, built of two valley filters in series and controlled elecrostatically by a gate voltage, the conductance‐to‐gate characteristic is inverted when a π/3 vertex is placed between two filters. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Growth and properties of near‐UV light emitting diodes based on InN/GaN quantum wells
Authors: Dimakis E. , Nikiforov A. Yu. , Thomidis C. , Zhou L. , Smith D. J. , Abell J. , Kao C.‐K. , Moustakas T. D.
Published: May 2008

Near‐ultraviolet light emitting diodes (LEDs), based on one monolayer thick InN/GaN multiple quantum wells, were grown by radio‐frequency plasma‐assisted molecular beam epitaxy. The active region was grown at 685 °C, a temperature where the growth of thick InN layers is not possible. High resolution transmission electron microscopy revealed that the InN well layers were grown pseudomorphically in between the GaN barriers and were characterized by well defined interfaces and uniform thickness. The LED structures exhibited electroluminescence emission at 384 nm, with a FWHM of about 14 nm. The peak emission wavelength was independent of the injection current, indicating the absence of quantum confined Stark effect in these structures. Output optical power of 0.84 mW was measured at 200 mA in a bare die configuration. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Models for the analysis of C‐reactive protein in statin trials
Authors: Southworth Harry , Dane Aaron
Published: May 2008

Elevation in C‐reactive protein (CRP) is an independent risk factor for cardiovascular disease progression and levels are reduced by treatment with statins. However, on‐treatment CRP, given baseline CRP and treatment, is not normally distributed and outliers exist even when transformations are applied. Although classical non‐parametric tests address some of these issues, they do not enable straightforward inclusion of covariate information. The aims of this study were to produce a model that improved efficiency and accuracy of analysis of CRP data. Estimation of treatment effects and identification of outliers were addressed using controlled trials of rosuvastatin. The robust statistical technique of MM‐estimation was used to fit models to data in the presence of outliers and was compared with least‐squares estimation. To develop the model, appropriate transformations of the response and baseline variables were selected. The model was used to investigate how on‐treatment CRP related to baseline CRP and estimated treatment effects with rosuvastatin. On comparing least‐squares and MM‐estimation, MM‐estimation was superior to least‐squares estimation in that parameter estimates were more efficient and outliers were clearly identified. Relative reductions in CRP were higher at higher baseline CRP levels. There was also evidence of a dose–response relationship between CRP reductions from baseline and rosuvastatin. Several large outliers were identified, although there did not appear to be any relationships between the incidence of outliers and treatments. In conclusion, using robust estimation to model CRP data is superior to least‐squares estimation and non‐parametric tests in terms of efficiency, outlier identification and the ability to include covariate information. Copyright © 2008 John Wiley & Sons, Ltd.
Impact of baseline ECG collection on the planning, analysis and interpretation of ‘thorough’ QT trials
Authors: Sethuraman Venkat , Sun Qiankun
Published: May 2008

The current guidelines, ICH E14, for the evaluation of non‐antiarrhythmic compounds require a ‘thorough’ QT study (TQT) conducted during clinical development (ICH Guidance for Industry E14, 2005). Owing to the regulatory choice of margin (10 ms), the TQT studies must be conducted to rigorous standards to ensure that variability is minimized. Some of the key sources of variation can be controlled by use of randomization, crossover design, standardization of electrocardiogram (ECG) recording conditions and collection of replicate ECGs at each time point. However, one of the key factors in these studies is the baseline measurement, which if not controlled and consistent across studies could lead to significant misinterpretation. In this article, we examine three types of baseline methods widely used in the TQT studies to derive a change from baseline in QTc (time‐matched, time‐averaged and pre‐dose‐averaged baseline). We discuss the impact of the baseline values on the guidance‐recommended ‘largest time‐matched’ analyses. Using simulation we have shown the impact of these baseline approaches on the type I error and power for both crossover and parallel group designs. In this article, we show that the power of study decreases as the number of time points tested in TQT study increases. A time‐matched baseline method is recommended by several authors (Drug Saf. 2005; 28(2):115–125, Health Canada guidance document: guide for the analysis and review of QT/QTc interval data, 2006) due to the existence of the circadian rhythm in QT. However, the impact of the time‐matched baseline method on statistical inference and sample size should be considered carefully during the design of TQT study. The time‐averaged baseline had the highest power in comparison with other baseline approaches. Copyright © 2008 John Wiley & Sons, Ltd.
Tropical‐cyclone intensification and predictability in three dimensions
Authors: Van Sang Nguyen , Smith Roger K. , Montgomery Michael T.
Published: May 2008

We present numerical‐model experiments to investigate the dynamics of tropical‐cyclone amplification and its predictability in three dimensions. For the prototype amplification problem beginning with a weak‐tropical‐storm‐strength vortex, the emergent flow becomes highly asymmetric and dominated by deep convective vortex structures, even though the problem as posed is essentially axisymmetric. The asymmetries that develop are highly sensitive to the boundary‐layer moisture distribution. When a small random moisture perturbation is added in the boundary layer at the initial time, the pattern of evolution of the flow asymmetries is changed dramatically, and a non‐negligible spread in the local and azimuthally‐averaged intensity results. We conclude, first, that the flow on the convective scales exhibits a degree of randomness, and only those asymmetric features that survive in an ensemble average of many realizations can be regarded as robust; and secondly, that there is an intrinsic uncertainty in the prediction of maximum intensity using either maximum‐wind or minimum‐surface‐pressure metrics. There are clear implications for the possibility of deterministic forecasts of the mesoscale structure of tropical cyclones, which may have a major impact on the intensity and on rapid intensity changes.

Some other aspects of vortex structure are addressed also, including vortex‐size parameters, and sensitivity to the inclusion of different physical processes or higher spatial resolution. We investigate also the analogous problem on a β‐plane, a prototype problem for tropical‐cyclone motion. A new perspective on the putative role of the wind‐‐evaporation feedback process for tropical‐cyclone intensification is offered also.

The results provide new insight into the fluid dynamics of the intensification process in three dimensions, and at the same time suggest limitations of deterministic prediction for the mesoscale structure. Larger‐scale characteristics, such as the radius of gale‐force winds and β‐gyres, are found to be less variable than their mesoscale counterparts. Copyright © 2008 Royal Meteorological Society
The assimilation of cloud‐affected infrared satellite radiances for numerical weather prediction
Authors: Pavelin E. G. , English S. J. , Eyre J. R.
Published: May 2008

A practical technique for the assimilation of cloud‐affected infrared radiances is presented. The technique is best suited to advanced infrared sounders such as AIRS and IASI. Radiances are first pre‐processed by a one‐dimensional variational analysis (1D‐Var) scheme, where cloud parameters (cloud‐top pressure and effective cloud fraction) are retrieved simultaneously with atmospheric profile variables. The retrieved cloud parameters are then passed to a variational data assimilation system, where they are used to constrain the radiative transfer calculation in the assimilation of a reduced set of channels. The channel selection is chosen to reduce the sensitivity to errors in the forward modelling of radiation originating below the cloud top. The performance of this technique is explored by means of a 1D‐Var study using simulated measurements. It is demonstrated that the technique has the potential to allow the assimilation of a significant proportion of cloud‐affected infrared sounding measurements, possibly bringing valuable benefits to an operational NWP system. © Crown Copyright 2008. Reproduced with the permission of the Controller of HMSO and the Queen's Printer for Scotland. Published by John Wiley & Sons, Ltd.
Dust emissions over the Sahel associated with the West African monsoon intertropical discontinuity region: A representative case‐study
Authors: Bou Karam D. , Flamant C. , Knippertz P. , Reitebuch O. , Pelon J. , Chong M. , Dabas A.
Published: May 2008

Near‐dawn airborne lidar and dropsonde observations acquired on 7 July 2006, during the African Monsoon Multidisciplinary Analysis (AMMA) Special Observing Period 2a1, were used to investigate dust mobilization, lifting and transport in the intertropical discontinuity (ITD) region over western Niger. Atmospheric reflectivity data from the LEANDRE 2 lidar system enabled us to analyse the structure of dust plumes in the context of wind and thermodynamic information provided by the WIND lidar system and dropsondes. Dust mobilization was mainly observed in two locations: (a) within the monsoon flow as the result of the passage of a density current originating from a mesoscale convective system over southwest Niger, and (b) at the leading edge of the monsoon flow where the near‐surface winds and turbulence were strong, because the monsoon flow was behaving as an intrusive density current. The circulation in the head of the monsoon density current lifted the mobilized dust towards the wake, along an isentropic surface. Behind and away from the leading edge, some of the mobilized dust was observed to mix across the monsoon–harmattan interface, due to the existence of mechanical shear above the monsoon layer. The dust thus becomes available for long‐range transport by the harmattan. Because dust sources are widespread over the Sahel and presumably active on many days when the ITD is located in this region during summer, dust emissions associated with the described mechanism may influence the radiation budget over West Africa. Copyright © 2008 Royal Meteorological Society
A backstepping‐based low‐and‐high gain design for marine vehicles
Authors: Bateman Alec , Hull Jason , Lin Zongli
Published: May 2008

A backstepping control design for marine vehicles was described in (Marine Control Systems: Guidance, Navigation and Control of Ships, Rigs, and Underwater Vehicles. Marine Cybernetics AS: Trondheim, Norway, 2002). Under a backstepping feedback law, global asymptotic stability of the closed‐loop system can be shown under the assumption of unlimited actuation. This paper addresses the issues that arise in the implementation of a backstepping feedback law by saturating actuators. First, for a given backstepping feedback law, an estimate of the domain of attraction is given for the resulting closed‐loop system under actuator saturation. A high gain component is then constructed and augmented to the original backstepping feedback law. This additional high gain component is shown not to shrink the estimate of the domain of attraction but to possess the ability to improve the closed‐loop response and to reject disturbance. Copyright © 2008 John Wiley & Sons, Ltd.
Methyl Oct‐cis‐2‐enoate. its synthesis, GLC behaviour and infrared spectra
Authors: Mercuri Osvaldo , Carrazoni N. E. , Brenner R. R.
Published: May 2008

Methyl oct‐cis‐2‐enoate was synthesized by selective hydrogenation of methyl oct‐2‐ynoate at atmospheric pressure with quinoline poisoned palladium as catalyst. The resulting product contained only 7% of thetrans form, as determined by GLC. The structure was confirmed by infrared spectra. Analysis of the infrared spectra is given. The cis andtrans forms of methyl oct‐2‐enoate were separable by GLC in polar or non‐polar columns. GLC runs in polar and non‐polar phases showed that the ॅ position of the double bond of methyl oct‐2‐enoate so affects its properties, that practically no interaction was observed between the double bond and the polar phase. Consequently volatility was the main factor determining the retention times of cis andtrans methyl oct‐2‐enoate in the polar and non‐polar phases studied.
Stearyl monoglycendyl citrate as an emulsifier enhancer
Authors: Geminder J. J.
Published: May 2008

Stearyl monoglyceridyl citrate, a fatty acid ester, is a semisolid compound with a slightly acidic flavor. In its liquid state it is completely miscible with vegetable and animal fats and oils. Although the compound exhibits surfactant activity and reduces interfacial tensions, its major function is emulsifier enhancement and emulsion stabilization when used in shortening systems along with accepted emulsifiers. Very acceptable liquid and plastic shortenings can be prepared through the addition of stearyl monoglyceridyl citrate and primary emulsifiers. Effective levels of stearyl monoglyceridyl citrate in shortenings enhance performance and permit use of lower levels of primary emulsifiers. Shelf‐life stabilities, smoke points, plasticity, and compatibility with primary emulsifiers in finished shortenings are good. Additions to margarines and whip toppings and performance in baked goods, as well as food additives status, are discussed.
Chromatographic analysis of seed oils. II. fatty acid composition of dimorphotheca oil
Authors: Binder R. G. , Applewhite T. H. , Diamond M. J. , Goldblatt L. A.
Published: May 2008

The fatty acid composition ofDimorphotheca sinuata seed oil was determined by use of column and gas‐liquid chromatography (GLC), and UV, IE, and nuclear magnetic resonance (n.m.r.) spectroscopy. The presence of a small amount of epoxy esters was confirmed by n.m.r. spectroscopy in conjunction with GLC and TLC. The presence of ca. 2.5% of 9‐keto‐trans,trans‐ 10,12‐octadeca‐dienoic acid, previously unrecognized as a constituent of dimorphotheca oil, was established. The estimated fatty acid composition of dimorphotheca oil is 66.5% dimorphecolic, 14% linoleic, 10% oleic, 4.5% palmitic and stearic, and 5% miscellaneous acids.
Electrophoretic properties in aqueous detergent systems
Authors: Ginn M. E. , Anderson R. M. , Harris J. C.
Published: May 2008

Electrophoretic mobilities and zeta potentials were developed for triolein, Nujol, and glass particles in aqueous detergent solutions. Zeta potentials in deionized water were: ‐79, ‐69, and ‐62 mv, respectively, for triolein, Nujol, and glass. Electrolyte builders and anionic surfactants markedly increase triolein and Nujol particle mobilities and negative zeta potentials; this effect probably contributes to their detersive action. Nonionic surfactants lower mobility of triolein and glass, and thus show slight cationic character. Significant inflection points are found for nonionic detergents near cmc. A cationic detergent produced high positive charge and zeta potentials with triolein and glass. Data for surfactant‐builder combinations show mobilities are primarily determined by the electrolyte. It was concluded that electrokinetic effects are important for dispersion and emulsification, but are not necessary and sufficient conditions for removing oily soil from glass.
Lipolysis of trivernolin by pancreatic lipase
Authors: Sampugna J. , Jensen R. G. , Parry R. M. , Krewson C. F.
Published: May 2008

Vernolic acid (cis‐12,13‐epoxy‐cis‐9‐oetadece‐noic acid) occurs as the triglyceride in the seed ofVernonia anthelmintica. Incubation of the seed produces a 1,3‐divernolin. To determine whether the structure of trivernolin is responsible for the apparent secondary ester position specificity of the natural enzyme, trivernolin and tri‐olein, were incubated with pancreatic lipase and the free fatty acids and monoglycerides were determined after 5 and 15 min digestion periods. The preponderance of 2‐monoglyceride produced by the action of pancreatic lipase was interpreted to indicate that the structure of trivernolin was not solely responsible for the secondary position specificity of theV. anthelmintica lipase toward trivernolin.
Physical properties of fatty acid methyl esters. I. density and molar volume
Authors: Gouw T. H. , Vlugter J. C.
Published: May 2008

Saturated fatty acid methyl esters from acetate to arachidate, methyl oleate, linoleate, linolenate, and erucate have been prepared in high purity. Densities, refractive indices, dispersions, ultrasonic sound velocities, and dielectric constants have been measured in the liquid state at 20 and 40C. In this first communication, the densities of the saturated compounds have been correlated with the Smittenberg relation. The following relations were derived: d204= 0.85407 + 0.18494/ (n + 0.096) and d404= 0.84225 + 0.12904/(n‐0.408). Molar volumes have been computed and checked for additivity.
Homogeneous catalytic hydrogenation of sorbic acid with pentacyanocobaltate II
Authors: Mabrouk A. F. , Dutton H. J. , Cowan J. C.
Published: May 2008

The homogeneous hydrogenation of sodium sorbate, with pentacyanocobaltate II used as the catalyst, was followed manometrically at room temperature and atmospheric hydrogen pressure. One mole of hydrogen was absorbed by one mole of sorbate. UV and IR analyses demonstrated the reduction of sorbate to hexenoate. Gas liquid chromatography (GLC) of hexenoate indicated 82, 17, and 1% yields of 2‐,3‐, and 4‐hexenoates, respectively, with traces of sorbate. Increasing either the period of hydrogenation or the ratio of catalyst to sorbate, or both, did not cause the formation of caproate or change the ratio of the three isomers. Homogeneous catalytic hydrogenation in methanolic solutions showed higher selectivity since 2‐hexenoate was present in 96% yield. To standardize GLC columns, hexenoic acid isomers were synthesized by the Knoevenagel condensation.Trans‐ 2‐ hexenoic andtrans‐ 3‐ hexe‐ noic acids were prepared in 75 and 85% yields by a condensation ofn‐butanal and malonic acid in the presence of pyridine and triethanolamine, respectively.Trans‐ i‐ h.exea.oic acid was prepared in 70% yield by condensing diethyl malo‐nate with crotyl bromide. Physical properties, including UV and IR spectra, were determined for the purified synthetic acids and methyl esters. Although the absolute specificity of attack at the 4,5‐double bond of sorbic acid was not confirmed, the high degree of selectivity obtained does encourage further study of homogeneous catalysis on higher fatty acids.
The Influence of Maternal Early to Mid‐Gestation Nutrient Restriction on Long Chain Polyunsaturated Fatty Acids in Fetal Sheep
Authors: Zhou Yunhua , Nijland Mark , Miller Myrna , Ford Stephen , Nathanielsz Peter W. , Brenna J. Thomas
Published: May 2008

The early to mid‐gestational period (days 28–78) in sheep is the period of most rapid placental development. Maternal nutrient restriction (MNR) in this phase has negative consequences on fetal growth and development, predisposing the fetus to disease in adult life. The influence of MNR on fetal tissue fatty acids has not been reported. Ewes were fed to 50% (MNR) or 100% (control fed) of total digestible nutrients from days 28 to 78 of gestation. At 78 days, fetuses were sacrificed and the fatty acids in fetal liver, lung and muscle as well as maternal and fetal plasma were analyzed. Most fatty acids were not influenced by MNR. The n‐3 long chain PUFA eicosapentaenoic acid (20:5n‐3, EPA) concentration (μg/mg) was low and more than doubled in the MNR sheep. Similarly, docosapentaenoic acid (22:5n‐3, DPA) increased by 60, 19, and 38% in liver, lung, and muscle, respectively. Neither docosahexaenoic acid (22:6n‐3, DHA) nor any of n‐6 PUFA changed. Arachidonic acid (20:4n‐6; ARA) increased in MNR maternal plasma as a percent of total fatty acids only, while in MNR fetal plasma only EPA increased. These results provide the first indication that MNR in early to mid‐gestation influences the profiles of LCPUFA in fetal tissues, and suggest that metabolic processes involving LCPUFA should be considered in evaluations of the impact of maternal nutriture on perinatal health.
Bounded rigidity of manifolds and asymptotic dimension growth
Authors: Chang Stanley S. , Ferry Steven , Yu Guoliang
Published: May 2008

We provide a bounded rigidity result for uniformly contractible manifolds with bounded geometry and sufficiently slow asymptotic dimension growth. This notion of asymptotic growth is a generalization of Gromov's definition of asymptotic dimension. In particular for these manifolds we prove that the bounded assembly map is an isomorphism. Our result is inspired by the coarse Baum-Connes results of Yu and the development of squeezing structures.
Fixed-point sets of smooth actions on spheres
Authors: Morimoto Masaharu
Published: May 2008

Given a group, it is a basic problem to determine which manifolds can occur as a fixed-point set of a smooth action of this group on a sphere. The current article answers this problem for a family of finite groups including perfect groups and nilpotent Oliver groups. We obtain the answer as an application of a new deleting and inserting theorem which is formulated to delete (or insert) fixed-point sets from (or to) disks with smooth actions of finite groups. One of the keys to the proof is an equivariant interpretation of the surgery theory of S. E. Cappell and J. L. Shaneson, for obtaining homology equivalences.
Toward a More Useful Economic History
Authors: HOHENBERG PAUL M.
Published: May 2008

Torn between divergent disciples, economic history needs to prove its usefulness as well as its scholarly virtuosity. Innovations in method and data have carried the field forward, but perhaps not fulfilled the claims of their champions. To economics in particular, economic history contributes a richer sense of space and time, and the importance of demographic factors. Three vignettes attempt to illustrate that useful economic history can result from confrontations of past and present that improve our understanding of both. Finally, emerging developments in the underlying fields may herald a more central future role for our discipline.
Banks, Credit Markets, and Early American Development: A Case Study of Entry and Competition
Authors: WANG TA-CHEN
Published: May 2008

New England experienced a significant economic transformation after the Revolutionary War. Despite an extensive literature on American development, little is known about the precise role of banks in this process. This article exploits a detailed dataset from Plymouth County, Massachusetts to show that the first bank during its early stage was far more selective in lending than the pre-existing personal credit market. Thus the mere introduction of a single bank did not broaden access to credit. Following the liberalization of chartering policy in the 1820s, however, freer entry and competition drove banks to extend credit to farmers and artisans.
The Baring Crisis and the Great Latin American Meltdown of the 1890s
Authors: MITCHENER KRIS JAMES , WEIDENMIER MARC D.
Published: May 2008

The Baring Crisis is the nineteenth century's most famous sovereign debt crisis. Using a database of more than 15,000 observations, we assess its effect on emerging market borrowers and find empirical evidence of a regional crisis but not a global crisis. During the crisis, Latin American yield spreads increased by more than 200 basis points relative to the rest of the world, even after controlling for macroeconomic, trade, political-institutional factors, and other country-specific effects. Our evidence suggests that European investors may have sold off or reduced their holdings of Latin American securities in the wake of the Baring Crisis.
Advances in Communication Technology and Growth of the American Over-the-Counter Markets, 1876–1929
Authors: FERDERER J. PETER
Published: May 2008

The rapid development of the nationwide telephone network following the expiration of the Bell patents in 1894, along with expansion of private wire telegraph networks, created the “nerve center” necessary for rapid growth in the decentralized, dealer-intermediated, over-the-counter security markets. Using membership roles from the National Quotation Bureau—the predecessor of the NASDAQ—I link growth in the number of dealers to the expansion of these communication networks prior to World War I. Moreover, trading activity on the organized stock exchanges fell during this period, suggesting that these technologies provided a competitive advantage to the over-the-counter markets.
Direct numerical simulations of a rapidly expanding thermal plume: structure and entrainment interaction
Authors: PLOURDE FRÉDÉRIC , PHAM MINH VUONG , KIM SON DOAN , BALACHANDAR S.
Published: May 2008

We examine the development of a thermal plume originating from a localized heat source using direct numerical simulation. The Reynolds number of the plume, based on source diameter and the characteristic buoyancy velocity, is chosen to be 7700, which is sufficiently large so that the flow turns to a fully turbulent state. A highly resolved grid of 622 million points is used to capture the entire range of turbulent scales in the plume. Here at the source, only heat has been added with no mass or momentum addition and accordingly the vertical evolution of the mass, momentum and buoyancy fluxes computed from the simulation have been verified to follow those of a pure thermal plume. The computed vertical evolution of the time-averaged centreline velocity and temperature are in good agreement with available experimental measurements. Investigation of the time evolution of the plume shows periodic formation of vortex ring structure surrounding the main ascending column of hot fluid. The vortex ring forms very close to the heat source and even at formation it is three-dimensional. The vortex ring ascends with the plume and at an elevation of about two diameters it strongly interacts with and destabilizes the central column and subsequently a complex turbulent flow arises. Thus, relatively laminar, transitional and fully turbulent regimes of the plume evolution can be identified. In the fully turbulent regime, complex three-dimensional hairpin-like vortex structures are observed; but vestiges of the coherent vortex rolls that form close to the source can be observed in the turbulent statistics. It is shown that local entrainment consists of contraction and expulsion phases. Such instantaneous mechanisms drive the entrainment process, and the instantaneous entrainment coefficient shows large variation in both time and space with local values up to three times higher than the average entrainment level. Such findings support the view that entrainment mechanisms in plumes should be considered from an unsteady point of view. Movies are available with the online version of the paper.
On the modelling of isothermal gas flows at the microscale
Authors: LOCKERBY DUNCAN A. , REESE JASON M.
Published: May 2008

This paper makes two new propositions regarding the modelling of rarefied (non-equilibrium) isothermal gas flows at the microscale. The first is a new test case for benchmarking high-order, or extended, hydrodynamic models for these flows. This standing time-varying shear-wave problem does not require boundary conditions to be specified at a solid surface, so is useful for assessing whether fluid models can capture rarefaction effects in the bulk flow. We assess a number of different proposed extended hydrodynamic models, and we find the R13 equations perform the best in this case.

Our second proposition is a simple technique for introducing non-equilibrium effects caused by the presence of solid surfaces into the computational fluid dynamics framework. By combining a new model for slip boundary conditions with a near-wall scaling of the Navier--Stokes constitutive relations, we obtain a model that is much more accurate at higher Knudsen numbers than the conventional second-order slip model. We show that this provides good results for combined Couette/Poiseuille flow, and that the model can predict the stress/strain-rate inversion that is evident from molecular simulations. The model's generality to non-planar geometries is demonstrated by examining low-speed flow around a micro-sphere. It shows a marked improvement over conventional predictions of the drag on the sphere, although there are some questions regarding its stability at the highest Knudsen numbers.
Rotating spherical Couette flow in a dipolar magnetic field: experimental study of magneto-inertial waves
Authors: SCHMITT DENYS , ALBOUSSIÈRE T. , BRITO D. , CARDIN P. , GAGNIÈRE N. , JAULT D. , NATAF H.-C.
Published: May 2008

The magnetostrophic regime, in which Lorentz and Coriolis forces are in balance, has been investigated in a rapidly rotating spherical Couette flow experiment. The spherical shell is filled with liquid sodium and permeated by a strong imposed dipolar magnetic field. Azimuthally travelling hydromagnetic waves have been put in evidence through a detailed analysis of electric potential differences measured on the outer sphere, and their properties have been determined. Several types of wave have been identified depending on the relative rotation rates of the inner and outer spheres: they differ by their dispersion relation and by their selection of azimuthal wavenumbers. In addition, these waves constitute the largest contribution to the observed fluctuations, and all of them travel in the retrograde direction in the frame of reference bound to the fluid. We identify these waves as magneto-inertial waves by virtue of the close proximity of the magnetic and inertial characteristic time scales of relevance in our experiment.
The structure of electrospray beams in vacuum
Authors: GAMERO-CASTAÑO MANUEL
Published: May 2008

Electrospray atomization of liquids in the cone-jet mode generates narrow droplet distributions with average diameters as small as a few nanometres. This ability is important for technologies such as colloid thrusters, nanoparticle generation and ion beam processes, and the optimization of these applications requires an understanding of the physics and structure of the associated beams. This paper presents a detailed experimental characterization of electrosprays in vacuum and formulates an analytical model of the beam. A key feature of our model is the use of a simplified expression for the electric field induced by the space charge. This simplification leads to a time-independent Eulerian formulation compatible with an analytical solution, in contrast to the direct simulation of a multitude of droplets which must be simultaneously tracked to account for Coulombic interactions. We find that the beams open up in an initial region relatively insensitive to the external electrodes, a process dominated by the electric repulsion between droplets and the initial droplet inertia. Although the external electric field modifies the trajectories of the droplets downstream of this initial region, the effect is moderate in our typical electrospray source and the analytical solution in the space charge region explains well the far-field beam structure observed experimentally. We also describe a numerical scheme that implements the full effect of the external electric field and provides a more accurate solution.
Dynamics and mixing of vortex rings in crossflow
Authors: SAU RAJES , MAHESH KRISHNAN
Published: May 2008

Direct numerical simulation is used to study the effect of crossflow on the dynamics, entrainment and mixing characteristics of vortex rings issuing from a circular nozzle. Three distinct regimes exist, depending on the velocity ratio (ratio of the average nozzle exit velocity to free-stream crossflow velocity) and stroke ratio (ratio of stroke length to nozzle exit diameter). Coherent vortex rings are not obtained at velocity ratios below approximately 2. At these low velocity ratios, the vorticity in the crossflow boundary layer inhibits roll-up of the nozzle boundary layer at the leading edge. As a result, a hairpin vortex forms instead of a vortex ring. For large stroke ratios and velocity ratio below 2, a series of hairpin vortices is shed downstream. The shedding is quite periodic for very low Reynolds numbers. For velocity ratios above 2, two regimes are obtained depending upon the stroke ratio. Lower stroke ratios yield a coherent asymmetric vortex ring, while higher stroke ratios yield an asymmetric vortex ring accompanied by a trailing column of vorticity. These two regimes are separated by a transition stroke ratio whose value decreases with decreasing velocity ratio. For very high values of the velocity ratio, the transition stroke ratio approaches the ‘formation number’. In the absence of trailing vorticity, the vortex ring tilts towards the upstream direction, while the presence of a trailing column causes it to tilt downstream. This behaviour is explained. In the absence of crossflow, the trailing column is not very effective at entrainment, and is best avoided for optimal mixing and entrainment. However, in the presence of crossflow, the trailing column is found to contribute significantly to the overall mixing and entrainment. The trailing column interacts with the crossflow to generate a region of high pressure downstream of the nozzle that drives crossflow fluid towards the vortex ring. There is an optimal length of the trailing column for maximum downstream entrainment. A classification map which categorizes the different regimes is developed.
From the global to the local? Governance and development at the local level: reflections from Tanzania
Authors: Harrison Graham
Published: May 2008

Governance reform practice has mostly focused on building up and transforming central state institutions. Furthermore, the politics of aid has often constructed a very ‘introverted’ politics based in large cities. This article explores the means through which governance ideas are implemented outside this ‘governance realm’, by looking at the ways in which the Lushoto District government in Tanzania has mediated a range of policy changes that have emanated from the state/donor centre. Identifying three distinct but inter-related repertoires of political practice, it argues that governance at the local level has been largely about financial management, and that this aspect of reform is in tension with local developmentalism and is more starkly opposed to local veranda politics.
New agricultural frontiers in post-conflict Sierra Leone? Exploring institutional challenges for wetland management in the Eastern Province
Authors: Maconachie Roy
Published: May 2008

Sierra Leone has recently emerged from a long period of political instability and civil war, and is ranked among the world's poorest countries. Thousands of displaced people are in the process of returning to their villages to rebuild their mainly farming-based livelihoods, and many are growing food crops for the first time in a decade. With pressure on food production increasing in rural areas, the inland valley swamps have been identified by the government as a vital resource for sustaining rural livelihoods and achieving food security through the production of rice and other commodities. However, previous government policies directed at enhanced wetland production have largely failed to achieve their goals, and have been criticised for neglecting the institutional challenges of development. Drawing on recent fieldwork carried out in two rural communities in the Eastern Province, this paper considers how institutional arrangements function in Sierra Leone's swamp wetlands, and explores how stresses associated with a post-conflict environment are shaping land-use decisions and mediating access to resources in new ways. The findings of the enquiry have implications for Sierra Leone's recently adopted commitment to decentralisation, a move that has, in theory, seen the state strengthen its position at the local level, and will allegedly create new spaces for increased interaction between state agencies, traditional leaders and communities. Two institutional challenges are examined – access to land and access to labour – that must be addressed if decentralised reforms to resource management are to be effective for wetland rice production. The analysis concludes by considering one recent initiative at the forefront of efforts to decentralise the Ministry of Agriculture, the ‘Agricultural Business Unit’ (ABU) initiative, to elucidate some of the challenges faced in post-conflict wetland rehabilitation.
Political corruption, party financing and democracy in Kenya
Authors: Gakuo Mwangi Oscar
Published: May 2008

This article examines political corruption and political party financing in multiparty Kenya. It uses the Goldenberg and Anglo-Leasing mega-scandals to demonstrate the existence of political corruption, particularly campaign financing, arguing that it has increased under multiparty rule and affected the nature of governance. It has adversely affected political participation and competition, the rule of law, transparency and accountability. Illegal funds to finance the Kenya African National Union's elections in the 1990s were raised through the Goldenberg Affair, whereas those aimed at financing the National Rainbow Coalition's elections in December 2007 were to be raised through the Anglo-Leasing scandal. Corrupt campaign financing, therefore, poses a threat to democracy in the country. The democratic space created and expanded by multipartyism has, however, provided new opportunities for waging the war against corruption. It is in the context of these arguments that the conclusion raises broader issues for corruption and democracy in Africa.
Building democracy from below: a case from rural Tanzania
Authors: Snyder Katherine A.
Published: May 2008

Focusing on events in a rural village in Tanzania during 2001–02, this paper examines the changing nature of state/society relations in Tanzania. Drawing on experience from previous years of fieldwork in the early 1990s, it becomes apparent that villagers are beginning to change the way they engage with the state. These new approaches are framed in part by the discourse of democracy, with which Tanzanians have become familiar since the economic and political liberalisation policies of the 1990s. These events reveal a new sense of the right to participate in decision-making on how to use key development resources. They also illustrate how local elites can threaten to capture benefits for their own gain. As Tanzanians begin to demand more rights to participate in the public sphere, their achievements enlarge our understanding of what might constitute civil society.