bluuebunny/crossref_metadata_2025 huggingface dataset:
Efficient numerical methods for pricing American options under stochastic volatility
Authors: Ikonen Samuli , Toivanen Jari
Published: March 2007

Five numerical methods for pricing American put options under Heston's stochastic volatility model are described and compared. The option prices are obtained as the solution of a two‐dimensional parabolic partial differential inequality. A finite difference discretization on nonuniform grids leading to linear complementarity problems with M‐matrices is proposed. The projected SOR, a projected multigrid method, an operator splitting method, a penalty method, and a componentwise splitting method are considered. The last one is a direct method while all other methods are iterative. The resulting systems of linear equations in the operator splitting method and in the penalty method are solved using a multigrid method. The projected multigrid method and the componentwise splitting method lead to a sequence of linear complementarity problems with one‐dimensional differential operators that are solved using the Brennan and Schwartz algorithm. The numerical experiments compare the accuracy and speed of the considered methods. The accuracies of all methods appear to be similar. Thus, the additional approximations made in the operator splitting method, in the penalty method, and in the componentwise splitting method do not increase the error essentially. The componentwise splitting method is the fastest one. All multigrid‐based methods have similar rapid grid independent convergence rates. They are about two or three times slower that the componentwise splitting method. On the coarsest grid the speed of the projected SOR is comparable with the multigrid methods while on finer grids it is several times slower. ©John Wiley & Sons, Inc. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A new alternating‐direction finite element method for hyperbolic equation
Authors: Zhang Zhiyue , Deng Dingwen
Published: March 2007

A modified backward difference time discretization is presented for Galerkin approximations for nonlinear hyperbolic equation in two space variables. This procedure uses a local approximation of the coefficients based on patches of finite elements with these procedures, a multidimensional problem can be solved as a series of one‐dimensional problems. Optimal order H01 and L2 error estimates are derived. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A stabilized method for a secondary consolidation Biot's model
Authors: Gaspar F.J. , Gracia J.L. , Lisbona F.J. , Vabishchevich P.N.
Published: March 2007

This work deals with the numerical solution of a secondary consolidation Biot's model. A family of finite difference methods on staggered grids in both time and spatial variables is considered. These numerical methods use a weighted two‐level discretization in time and the classical central difference discretization in space. A priori estimates and convergence results for displacements and pressure in discrete energy norms are obtained. Numerical examples illustrate the convergence properties of the proposed numerical schemes, showing also a non‐oscillatory behavior of the pressure approximation. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
A remark on the coercivity for a first‐order least‐squares method
Authors: Ku Jaeun
Published: March 2007

This study present a short proof concerning the coercivity of a first‐order least‐squares finite element method for general second‐order elliptic problems proposed by Cai, Lazarov, Manteuffel and McCormick (Cai et al. J Numer Anal 31 (1994), 1785–1799). Our proof is based on a priori estimate and the technique can be applied to prove L2‐norm error estimate for the primary function u. After establishing the coercivity bound from the assumed a priori estimate, we observe that the coercivity bound is actually equivalent to the a priori estimate. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007
Dynamic infrared measurements of poly(vinyl chloride) in the vicinity of the glass transition
Authors: Ogura Katsuyuki
Published: March 2007

The temperature dependences of some selected infrared bands of poly(vinylchloride) in the vicinity of the glass transition were examined. The intensities of 1333 and 1427 cm−1 bands changed discontinuouly at Tg; on the other hand, 2920 cm−1 did not show any significant changes at this temperature. From these results, the nature of the temperature dependence of infrared intensity of the polymer was discussed. The procedure introduced in this work offers a rapid method for the determination of the Tg as compared with the conventional infrared methods.
Effect of formulation on properties and morphology of polyurethane elastomers
Authors: Fulcher Keith U. , Corbett Gerald E.
Published: March 2007

A model polyurethane elastomers system has been used to study the relationships between chemical formulation, polymer physical structure and mechanical properties. The elastomers were made from formulations comprising a polyether polyol blend (diol plus triol), a chain extender blend (1,4 butane diol plus 1,1,1‐trimethylol propane) and 4,4′‐di‐isocyanate diphenylmethane. The morphologies of the elastomers were investigated in detail, mainly by means of small angle X‐ray scattering techniques. It was confirmed that the polyurethane systems examined comprised domains 50 to 100 Å in size and spaced around 100 to 200 Å apart. A complete decription of the polyurethane morphology has been made in terms of the volume fraction of domains present, the average domain size and the average domain–domain separation. The results suggest that, whilst it is possible to correlate, in general, formulation changes with variations in the elastomer morphology, it seems that direct correlations between physical structure and mechanical properties are not very meaningful in the present model system. However, it is clear that knowledge of the morphology is of considerable importance in interpreting the effects of formulation on observed properties.
Ionomer cements
Authors: Wilson Alan D. , Crisp Stephen
Published: March 2007

The chemistry and properties of the ionomer cements are reviewed. These cements are defined by the acid‐base interaction between metal oxides or silicates with aqueous solutions of organic polymeric acids. the cements formed both from ion‐leachable aluminosilicates and from zinc oxide are of practical importance and characterised by their ability to bond to active substrates under moist conditions. The polymer solutions used in these formulations tend to gel slowly over a period of several months. This phenomenon can be avoided by partial methylation of the polymer or by the use of a suitable copolymer. The role of the anoins present in the system and those, such as tartrate, added to improve rheological properties, is discussed. The nature of the bonding in these cement gels is considered in terms of ion‐binding of polyanions of polyvalent cations. The function of water in the cement and hydrolysis of cations is discused. In the final section the long‐term development of surface hardness and compressive strenght is reported. The modulus of elasticity and stress relaxation properties of these cements are compared to those of the brittle dental silicate cement.
Physical and mechanical properties of glass—ionomer cements
Authors: Elliott Joseph , Holliday Leslie , Hornsby Peter R.
Published: March 2007

A comparison is made of the mechanical properties of ionic polymer cements, prepared by reacting an aqueous poly(acrylic acid) solution with ion‐leachable inorganic powders. Out of the wide range of powders investigated, specially formulated aluminosilicate glasses gave the most promising results, and the properties of cements made from them are discussed in greater detail. In particular, the dependence of compressive strength on cement age is described, and the loss of water from the material when exposed to atmospheres of low relative humidity is shown to be related to property changes which occur under these conditions. An interpretation of these detrimental effects is presented in terms of variation in the cement microstructure, and methods of minimising the effects by various modifications to the basic system are reviewed.
Electrical conductivity in ionic complexes of poly(ethylene oxide)
Authors: Wright Peter V.
Published: March 2007

The temperature dependence of d.c. conductivity of poly(ethylene oxide) complexes with sodium iodide and the thiocyanates of sodium, potassium and ammonium has been investigated. In each case a transition to a lower activation energy at higher temperatures was observed. For the sodium complexes this transition occurs at ca 55°C which is well below the crystalline melting points at 200°C. For the potassium and ammonium complexes however, the transitions coincide with the melting points at ca 100 and 70°C respectively. It is proposed that at the transitions, thermal disintegration of complexes in the amorphous regions occurs. The complexes involve coordination of the cations to the ether oxygen atoms in the polymer backbone.
Thermal and mechanical properties of block copolymers of poly(hexamethylene terephthalate) and poly(oxyethylene) units
Authors: Goodman Isaac , Peters Raymond H. , Schenk Victor T. J.
Published: March 2007

Block copolyetheresters of poly(hexamethylene terephthalate) (6GT) with poly(oxyethylene) terephthalate (POET) units have been prepared by polycondensation and certain of their thermal, morphological and mechanical properties have been determined. The copolymers rich in 6GT or POET units show the crystalline characteristics of the single respective homopolymers, whereas in the middle of the composition range crystalline phases of both types coexist. Increase in the proportion of POET units causes a decrease in the melting and glass transition temperatures and in the crystallisation rates whilst concomitantly the mechanical properties change from fibrous to elastomer in type. The results are interpreted in terms of a polycrystallite model in which the compostion‐dependent nature of the crystallites and tie bars determines the overall mechanical properties of the copolymers.
The thermal degradation of some poly(fluorethers)
Authors: Cotter John L. , Knight Graham J. , Wright Walter W.
Published: March 2007

A series of poly(fluoroethers) has been studied by thermogravimetry, pyrolysisgas chromatography–mass spectrometry and fluoride ion analysis. The thermal stabilities are lower than those of a vinylidene fluoride/hexafluoropropene copolymer. Primary chain scission occurs at O—CH2 links. Rearrangement processes giving rise to cyclic compounds are important for polymers containing aromatic or heterocyclic rings in the chain.
Phase equilibria and phase separation proceedings of the 5th polymer meeting point at the university of essex. Phase equilibria and phase separation
Authors: Koningsveld R.
Published: March 2007

Phase separations in condensed systems are reviewed on the basis of the still valid considerations of Gibbs, Van der Waals and Schreinemakers, formulated many years ago. Examples are taken from more recent data on mixtures containing macromolecules, which appear to obey phase‐rule theory in great detail and subtlety. The phase rule sets limits to the maximum possible number of phases, the actual number being governed by the precise dependence of the free enthalpy (Gibbs free energy) of mixing on temperature, concentration, molecular weight, etc. Accurate knowledge of the free enthalpy function allows prediction of phase behaviour with great precision. Methods are described which permit sufficiently accurate determination of the necessary parameters.
Effect of natural ageing on the dielectric properties of natural rubber—channel black mixtures
Authors: Bishai Augenie M. , Hanna Faika F.
Published: March 2007

A systematic dielectric study over the frequency region from 60 Hz to 107 Hz has been carried out on natural rubber samples mixed with channel black after being subjected to natural ageing for nine years. The results are compared with those obtained before8 and the differences are interpreted.
Bis‐4,9‐diazapyrenium dications: synthesis of the methylenedibenzyl‐analogue, interactions with nucleotides, DNA, RNA. The antitumour activity of all till now prepared analogues
Authors: Piantanida Ivo , Žinić Mladen , Marczi Saška , Glavaš‐Obrovac Ljubica
Published: March 2007

Novel bis‐4,9‐diazapyrenium dication has shown reversible pH dependent formation of 4,9‐ diazapyrenium pseudobase in water characteristic for most 4,9‐diazapyrenium derivatives. The compound has formed non‐covalent complexes with nucleotides in water, whose stability is controlled dominantly by aromatic stacking interactions. No cooperativity between two 4,9‐diazapyrenium subunits was observed in binding of nucleotides. Novel bis‐4,9‐diazapyrenium dication formed mono‐intercalative complexes with studied double stranded DNA and RNA. Additional interactions of non‐intercalated part were found to depend significantly on the polynucleotide secondary structure, yielding strong DNA over RNA preference. Appearance of ICD band of3was found to be specific for DNA polynucleotides and together with observed destabilisation of double stranded RNA is attributed to the aggregation of compound in one of the RNA grooves. All bis‐4,9‐diazapyrenium dications prepared till now have shown considerable antiproliferative activity against five human tumour cell lines, which suggested mechanism of action by interacting with cell DNA. Copyright © 2007 John Wiley & Sons, Ltd.
Organocatalysis: quantum chemical modeling of nucleophilic addition to α,β‐unsaturated carbonyl compounds
Authors: Bruvoll Marius , Hansen Tore , Uggerud Einar
Published: March 2007

One of the successful transformations within the field of organocatalysis, the organocatalytic asymmetric addition of nitromethane to α,β‐unsaturated aldehydes and ketones, has been studied by quantum chemical modeling. The level of accuracy of the hybrid density functional theory method B3LYP/6‐31G(d) was compared to a high level ab initio benchmark for this reaction. It is concluded that B3LYP/6‐31G(d) performs very well for this reaction type, giving good estimates of critical energies. The reaction between acrolein and nitromethane was studied in detail. The reaction mechanism revealed an intermediate oxazolidin structure, which is currently unknown. Alkyl substitution in various positions on the amine catalyst or α,β‐unsaturated carbonyl compound influences the reactivity in a predictive fashion. The iminium ion, prop‐2‐en‐iminium, is less activated towards nucleophilic attack compared to protonated acrolein. Copyright © 2007 John Wiley & Sons, Ltd.
Swift hopping gallium over [AlO4]− tetrahedra in Ga/ZSM‐5: A DFT study
Authors: Kusmin Ilya V. , Zhidomirov Georgy M. , Solkan Vitaly N.
Published: March 2007

Density functional theory calculations were carried out to investigate gallium species (Ga+, [GaH2]+, and [GaO]+) stabilization in Ga‐exchanged HZSM‐5, using cluster modeling approach. Three isomeric gallium positions over [AlO4]− zeolite fragment at T12 position were found. These isomers are turning into each over with low activation energy barrier and gallium fragment revolves around [AlO4]− tetrahedron by hopping between cationic positions. Activation energies of gallium fragment hopping were computed and compared for different gallium containing cations. Those barriers were found to be times less than the activation energies of catalytic processes on gallium‐exchanged zeolite. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007
Predictive strength of Jonckheere's test for trend: an application to genotypic scores in HIV infection
Authors: Flandre Philippe , O'Quigley John
Published: March 2007

A problem arising in studies on the human immunodeficiency virus (HIV) infection relate to one‐sided tests with ordered alternatives as opposed to the more classical two‐sided tests. Patients not having a resistance mutation may have a better virologic response to treatment than patients with a single mutation. In turn, those with a single mutation may have a better response to treatment than those patients having two mutations, and so on. In the presence of a continuous outcome, Jonckheere's test for ordered alternatives is well adapted to this situation. Such an analysis does not provide any measure of prediction or explained variation which can complement these results. A measure of strength of effect would be helpful in quantifying the degree of association between the genotypic score (number of mutations) and some continuous virological response. We suggest a simple measure of ‘goodness of split’ for Jonckheere's test for trend. Interestingly, the measure can be related to the non‐parametric measure of association known as gamma. The variance formula for the measure studied here can be seen to differ from the known variance estimate of the gamma measure, and simulations show it to be more accurate. Expectation and variance underH0of the measure are provided and a large simulation study is presented. Methods are applied to a recent clinical data set involving HIV‐1 infected patients where the number of resistance mutations are investigated as potential predictors of the amount of HIV‐1 RNA reduction at week 4. Copyright © 2007 John Wiley & Sons, Ltd.
Sexual recruitment of the corals Favia fragum and Agaricia humilis in a 30‐m3 exhibit aquarium: species‐specific limitations and implications on reproductive ecology
Authors: Petersen Dirk , Laterveer Michaël , Visser Gerard
Published: March 2007

We studied the recruitment of the Caribbean reef building corals Favia fragum (F. fragum) and Agaricia humilis(A. humilis) in captivity. Thirty colonies of each species collected in Curaçao, Netherlands Antilles, reproduced sexually during a temporary stay in a 30‐m3 closed system from November 2001–January 2002. Twelve months later, the F1 generation of F. fragum started reproducing and formed an F2 generation. No reproduction of the F1 recruits of A. humilis was observed. Two years after the introduction of the field colonies, sexual recruits of both species were assessed using two different methods: recruits were estimated using quadrats (quadrat sampling method) and the total number of recruits was counted by creating a map of the artificial rock work divided in distinct areas (area census method). Recruitment rates of F. fragum were highest for the F2 generation on horizontal surfaces (area census method: 137.9±191.7 recruits m−2; quadrat sampling method: 272.0±254.8 recruits m−2; mean±SD) and were overall lowest for the F1 generation on overhanging areas of the tank (area census method: 3.8±4.0 recruits m−2; quadrat sampling method: 4.0±6.1 recruits m−2; mean±SD recruits m−2). The populations of both species showed similar patterns independent of the applied assessment method with highest densities on horizontal surfaces followed by vertical surfaces and lowest densities on overhanging surfaces; however, both methods showed conflicting results when the influence of the surface orientation on the population densities was statistically analyzed. The maximum density of A. humilis (1.4±2.7 recruits m−2 on horizontal surfaces) was much lower than the maximum density of the F1 generation of F. fragum (24.7±18.3 recruits m−2). Colony sizes of recruits within each population (F. fragum F1: 3.12±0.98 cm, F2: 0.83±0.41 cm; A. humilis F1: 3.79±1.35 cm; maximum diameter±SD) did not differ between different orientations (horizontal vs. vertical vs. overhanging). Calculated growth rates in the aquarium reflected those observed for F. fragum in the field, whereas A. humilis showed slower growth in the aquarium than in the field. Factors such as competition, sedimentation, and predation, that generally reduce in situ recruitment may be excluded in captivity resulting in far higher recruitment rates. This study confirms that aquarium exhibits can serve as a comparative model to study the ecology of corals under semi‐controlled conditions. Zoo Biol 0:1–17, 2007. © 2007 Wiley‐Liss, Inc.
The hydrolysis of soap solutions. II. The solubilities of higher fatty acids
Authors: John Lucille M. , McBain James W.
Published: March 2007

The solubilities of capric, lauric, myristic, palmitic, and stearic acids in water at 25° and 50°C. were determined by use of conductivity measurements. Correction was made for carbon dioxide; and total solubilities, together with the concentration of dissociated and of undissociated acid were calculated. Their solubilities range from 359×10−6 M for capric acid to 2.1×10−6 M for stearic acid at 25°C. The solulility of laric and myristic is approximately doubled by an increase of temperature from 25° to 50°C., that of capric, palmitic, and stearic acids increases by 25 to 40%.
A comparison of wesson loss and cup refining loss analyses of crude cottonseed and soybean oils
Authors: King R. R. , Wharton F. W.
Published: March 2007

Wesson loss and cup refining loss were determined on 100 samples of crude cottonseed and soybean oils produced in different sections of the country. The Wesson method gave more reproducible results than the cup method. Wesson loss results were found to be closely indicative of the total neutral oil content of crude oils. The average ratio of cup loss to Wesson loss was 2.3 for crude cottonseed oil and 1.7 for crude soybean oil. The ratio varied considerably for individual crude oils of a given kind, or type within each kind, or a local producing section.

Therefore, no real useful correlation between the results of the two methods was found to exist.
Arylstearic acids from oleic acid. Variables affecting the yield and properties
Authors: Stirton A. J. , Schaeffer B. B. , Stawitzke Anna A. , Weil J. K. , Ault Waldo C.
Published: March 2007

Twenty‐six aromatic compounds were compared in the synthesis of arylstearic acids from oleic acid by the Friedel and Crafts reaction. Xylylstearic acid was the arylstearic acid obtained in the highest yield (92.4%) from technical m‐xylene and commerical oleic acid. The various side reactions are disussed including the possible conversion of oleic acid into products which on vacuum distillation of the crude arylstearic acid appear as a forerun and as a still residue. Oleic acid of about 98% purity did not improve the yield but resulted in nearly colorless, rather than yellow viscous oils.

Crystalline arylstearic acids have for first time been isolated from the reaction products but only in small yields.
Components of “soybean lecithin”
Authors: Scholfield C. R. , Dutton H. J. , Tanner F. W. , Cowan J. C.
Published: March 2007

The acetone‐insoluble material from soybean “lecithin” has been fractionated by submitting alcohol‐soluble and alcohol‐insoluble portions to countercurrent distribution between hexane and methanol. The alcohol‐soluble portion was found to contain lecithin, cephalin, and sugars or glycosides; the alcohol‐insoluble portion was separated into two major inositol‐containing phosphatides and sugars or glycosides. While the commonly accepted value of 30–35% for lecithin in the phosphatides was confirmed, it appears that the accepted value of 65% of cephalin needs revision. The approximate composition for one sample of soybean phosphatides is estimated to be 29% lecithin, 31% cephalin, and 40% inositol‐phosphatides.
Application of the line‐width method to the spectrochemical analysis of oils, fats, and related substances
Authors: O'Connor R. T. , Heinzelman D. C. , Jefferson M. E.
Published: March 2007

The application of the line‐width method to the spectrochemical analysis of oils and fats in conjunction with the use of an improved ashing technique has been shown to permit the quantitative determination of copper, iron, manganese, nickel, and tin in quantities as low as 1 part in 10 million.

The procedure has been critically examined by precision tests on commercial and experimental samples, by accuracy tests on synthetic samples, and by recovery tests.

Results of actual analysis of 30 vegetable oils and fats indicate the use of the procedure as a research tool.

The procedure may be used for the trace element analysis of organic material low in ash content.
Ultraviolet spectrophotometric characteristics of unhydrogenated fish oils
Authors: Lambert Reuben S. , Andrews J. T. R.
Published: March 2007

Typical ultraviolet spectrophotometric absorption curves are presented for unhydrogenated fish oils of commercial importance, before and after alkali isomerization. These curves show the usual maxima for isomerized polyunsaturated fatty acids, including five, and possibly six, double bonds. Tetraene absorption is sufficient to obliterate that of trienes completely. Such a method of analysis affords an easy means of detecting unhydrogenated fish oil contamination in the ordinary vegetable and animal oils and fats as well as a test for the presence of fish oils in admixture with raw linseed oil.
Low‐temperature solvent fractionation of corn oil and calculation of its glyceride structure
Authors: Doerschuk Albert P. , Daubert B. F.
Published: March 2007

Corn oil was subjected to a low‐temperature solventfractionation process and separated into 19 glyceride fractions; the glyceride structures of the fractions were calculated and added to obtain the glyceride structure of the oil. The experimentally obtained glyceride structure was compared to the structures calculated according to the mono‐acid triglyceride, random, even, and partial random schemes and was found to agree most closely with the partial random system.
Changes in a fat with prolonged storage and the palatability of doughnuts cooked in the fat
Authors: Overman Andrea , Lowe Belle , Shannon W. J.
Published: March 2007

The storage for 2.5 years did not appreciably affect the smoke point, nor did storage for 3.5 years cause appreciable changes in the iodine value or the refractive index. There was a perceptible change, in the free fatty acid content after storage for 3.5 years, but none after 2.5 years. The peroxide value was higher after 2.5 years' storage than at 6 months, but unaccountably was lower after 3.5 years than after 2.5 years' storage of the fat.

The chemical and physical constants, of the fats were changed appreciably and, in general, consistently during the use of the fat for cooking 24 lots of doughnuts. The rapidity with which chemical changes took place in the fats during their use for cooking was not influenced by the length of time the fat had been stored previous to use.

In general, the constants of the fat extracted from the doughnuts closely paralleled the corresponding samples of fat in which the doughnuts were cooked. Iodine values of extracted fats tended to be lower than the kettle fats for the first two storage periods and about the same after 3.5 years. The free fatty acid content was slightly higher in the extracted fat than in the kettle fat at the 6‐month period, and slightly lower at the 3.5‐year period. Volatile acids were higher in extracted than in kettle fats.

The desirability of doughnuts fried in the fat was not affected by storage of the fat 2.5 years prior to use, but was lowered after the fat was stored for 3.5 years.
The effect of dielectric heating on storage quality of cottonseed
Authors: Lyman Carl M. , Burda Edward J. , Olschner Paul Q.
Published: March 2007

It was found that the exposure of moist cottonseed to a radio frequency electric field for a period of from two to five minutes effectively reduced the formation of free fatty acids during subsequent storage of the seed. Two primary factors were involved in this action. First, moisture was rapidly removed from the seed and second, the enzymes responsible for free fatty acid formation were destroyed. Cottonseed containing 20% moisture accumulated free fatty acids only very slowly on storage at 38.5°C. after a brief dielectric heat treatment. The temperature inside the cottonseed was measured during the dielectric heat treatment. Temperature above 100°C. were attained in less than one minute.
The state of methods and tools for social systems change
Authors: Parsons Beverly A.
Published: March 2007

The last decade or so has seen an increase in the rate of attention to systems change and the application of multiple theories to study and influence change in systems. This article considers how these theories, described in other articles in this issues, plus theories about complex adaptive systems open opportunities for us to continue to expand our repertoire of tools and methods to address systems change. These conceptual frameworks, tools, and methods are expected to help us increase our capacity to study and influence both planned and self‐organizing systems change. New tools and methods have emerged and others are needed to help us continue to explore and influence the complex social systems within which we operate.
Glycaemic index and glycaemic load values of cereal products and weight-management meals available in the UK
Authors: Henry C. Jeya K. , Lightowler Helen J. , Dodwell Lis M. , Wynne Jacqueline M.
Published: March 2007

There is currently an increased global interest in the published glycaemic index (GI) values of foods. The aim of the present work was to supplement a previous study on the glycaemic response of 140 foods available in the UK by studying a further forty-four foods. One hundred and twenty-two healthy subjects, with a mean age of 32·4 (sd 11·4) years and a mean BMI of 23·6 (sd 3·6) kg/m2, were recruited to the study. Subjects were served equivalent available carbohydrate amounts (50 or 30 g) of test foods (cereal products and weight-management meals) and a standard food (glucose) on separate occasions. Capillary blood glucose was measured from finger-prick samples in fasted subjects (0 min) and at 15, 30, 45, 60, 90 and 120 min after starting to eat each test food. For each test food, the GI value was determined, and the glycaemic load was calculated as the product of the GI and the amount of available carbohydrate in a reference serving size. The GI values of the foods tested ranged from 23 to 83. Of the forty-four foods tested, thirty-three were classified as low-GI, eight as medium-GI and three as high-GI foods. Most GI values of the foods tested compared well with previously published values for similar foods. In summary, this study provides reliable GI and glycaemic load values for a range of foods, further advancing our understanding of the glycaemic response of different foods. The data reported here make an important addition to published GI values.
Impact of high-protein diets with either moderate or low carbohydrate on weight loss, body composition, blood pressure and glucose tolerance in rats
Authors: Lobley Gerald E. , Bremner David M. , Holtrop Grietje , Johnstone Alexandra M. , Maloney Christopher
Published: March 2007

One approach to achieve weight loss and decrease both obesity and associated morbidities involves high-protein, low-carbohydrate (HPLC) diets. This study compares the impact on metabolic health of HPLC and high-protein, medium-carbohydrate (HPMC) diets offered to diet-induced obese (DIO) rats. Weanling male rats were fed either a 37 % fat diet (n48) or stock pellets (n12) for 22 weeks. Rats fed the 37 % fat diet accumulated more body fat (26·6versus14·8 % body weight,P < 0·001) compared with those on stock diet. The DIO rats had higher systolic blood pressure (+6·6 mmHg,P = 0·002), fasting insulin (+63 %P = 0·006) and areas under the glucose (+21 %,P < 0·001) and insulin (+81 %,P < 0·001) curves following an oral glucose tolerance test. DIO rats were then separated into four groups and offered for 8 weeks either: (1) the 37 % fat diet; (2) an HPLC or (3) HPMC diet; or (4) fed the 37 % fat diet to the intake of the HPMC group. Rats offered the 37 % fat or HPLC diets gained while those on HPMC lost body fat. Blood pressure was not altered by the dietary switch. Both HPLC and HPMC rats had lowered fasting insulin (P = 0·027) and improved homeostatic assessment (HOMA;P = 0·011) that was not different from those of stock animals. These improvements occurred despite differences in fat gain, and indicate that both weight loss and macronutrient intake can impact favourably on obesity-associated morbidities.
Empirical evaluation of the ability to learn a calorie counting system and estimate portion size and food intake
Authors: Martin Corby K. , Anton Stephen D. , York-Crowe Emily , Heilbronn Leonie K. , VanSkiver Claudia , Redman Leanne M. , Greenway Frank L. , Ravussin Eric , Williamson Donald A. ,   for the Pennington CALERIE Team
Published: March 2007

The aim of this study was to determine if: (1) participants could learn the HMR Calorie System© by testing if their use of the system was more accurate after training; and (2) estimated portion size and food intake improved with training. A secondary aim was to use PACE (photographic assessment of calorie estimation) to assess if participants learned the HMR system. The PACE consists of pictures of foods, the energy content of which is known. A within-subjects design was used to test the aims of this study. Participants were 44 overweight (25 ≤ BMI < 30) adults who were randomly assigned to one of three calorie restriction groups or a weight maintenance group for 6 months. Participants attended weekly sessions and were trained to use the HMR system from weeks 5 to 8. Participants were provided with foods to test if they could effectively use the HMR system and accurately estimate portion size and the amount of food eaten. The PACE was also used to quantify accuracy at using the HMR system. Training resulted in more accurate estimation of food intake, use of the HMR system and estimated portion size when presented with food. Additionally, training resulted in significantly more accurate use of the HMR system when measured with PACE. It is concluded that people can learn the HMR Calorie System© and improve the accuracy of portion size and food intake estimates. The PACE is a useful assessment tool to test if participants learn a calorie counting system.
Standardization of measles, mumps and rubella assays to enable comparisons of seroprevalence data across 21 European countries and Australia
Authors: TISCHER A. , ANDREWS N. , KAFATOS G. , NARDONE A. , BERBERS G. , DAVIDKIN I. , ABOUDY Y. , BACKHOUSE J. , BARBARA C. , BARTHA K. , BRUCKOVA B. , DUKS A. , GRISKEVICIUS A. , HESKETH L. , JOHANSEN K. , JONES L. , KUERSTEINER O. , LUPULESCU E. , MIHNEVA Z. , MRAZOVA M. , DE ORY F. , PROSENC K. , SCHNEIDER F. , TSAKRIS A. , SMELHAUSOVA M. , VRANCKX R. , ZARVOU M. , MILLER E.
Published: March 2007

The aim of the European Sero-Epidemiology Network is to establish comparability of the serological surveillance of vaccine-preventable diseases in Europe. The designated reference laboratory (RL) for measles, mumps, rubella (MMR) prepared and tested a panel of 151 sera by the reference enzyme immunoassay (rEIA). Laboratories in 21 countries tested the panel for antibodies against MMR using their usual assay (a total of 16 different EIAs) and the results were plotted against the reference results in order to obtain equations for the standardization of national serum surveys. The RL also tested the panel by the plaque neutralization test (PNT). Large differences in qualitative results were found compared to the RL. Well-fitting standardization equations withR2⩾0·8 were obtained for almost all laboratories through regression of the quantitative results against those of the RL. When compared to PNT, the rEIA had a sensitivity of 95·3%, 92·8% and 100% and a specificity of 100%, 87·1% and 92·8% for measles, mumps and rubella, respectively. The need for standardization was highlighted by substantial inter-country differences. Standardization was successful and the selected standardization equations allowed the conversion of local serological results into common units and enabled direct comparison of seroprevalence data of the participating countries.
Host-shaped segregation of theCryptosporidium parvummultilocus genotype repertoire
Authors: GRINBERG A. , LOPEZ-VILLALOBOS N. , POMROY W. , WIDMER G. , SMITH H. , TAIT A.
Published: March 2007

Cattle are among the major reservoirs ofCryptosporidium parvumin nature. However, the relative contribution ofC. parvumoocysts originating from cattle to human disease burden is difficult to assess, as various transmission pathways – including the human to human route – can co-occur. In this study, multilocus genotype richness of representative samples of human and bovineC. parvumare compared statistically using analytical rarefaction and non-parametric taxonomic richness estimators. Results suggest that in the time and space frames underlying the analysed data, humans were infected with significantly wider spectra ofC. parvumgenotypes than cattle, and consequently, a significant fraction of human infections may not have originated from the regional bovine reservoirs. This study provides statistical support to the emerging idea of the existence of distinct anthroponoticC. parvumcycles that do not involve cattle.
Serological responses toCryptosporidium-specific antigens in Czech populations with different water sources
Authors: KOZISEK F. , CRAUN G. F. , CEROVSKA L. , PUMANN P. , FROST F. , MULLER T.
Published: March 2007

Serological responses toCryptosporidium-specific antigens (15/17 and 27 kDa) were compared among populations in four areas of the Czech Republic that use drinking water from clearly defined sources: (1) wells in a fractured sandstone aquifer, (2) riverbank infiltration, or (3) two different filtered and chlorinated surface waters. Among persons surveyed in the area with riverbank-infiltration water, 33% had a strong serological response to the 15/17-kDa antigen group whereas, in the other three areas, over 72% of persons had a strong response. These response differences suggest thatCryptosporidiumexposures and infection were lower in the area with bank infiltration. The large percentage of the study population with a strong serological response to both antigens suggests high levels of previous infections that may have resulted in protective immunity for cryptosporidiosis. This may be one reason why no waterborne cryptosporidiosis outbreaks and few cases of cryptosporidiosis have been reported in the Czech Republic.
Upscaling for unsaturated flow for non‐Gaussian heterogeneous porous media
Authors: Neuweiler Insa , Vogel Hans‐Jörg
Published: March 2007

Large‐scale models of transient flow processes in the unsaturated zone require, in general, upscaling of the flow problem in order to capture the impact of heterogeneities on a small scale, which cannot be resolved by the model. Effective parameters for the upscaled models are often derived from second‐order stochastic properties of the parameter fields. Such properties are good quantifications for parameter fields, which are multi‐Gaussian. However, the structure of soil does rarely resemble these kinds of fields. The non‐multi‐Gaussian field properties can lead to strong discrepancies between predictions of upscaled models and the averaged real flow process. In particular, the connected paths of parameter ranges of the medium are important features, which are usually not taken into account in stochastic approaches. They are determined here by the Euler number of one‐cut indicator fields. Methods to predict effective parameters are needed that incorporate this type of information. We discuss different simple and fast approaches for estimating the effective parameter for upscaled models of slow transient flow processes in the unsaturated zone, where connected paths of the material may be taken into account. Upscaled models are derived with the assumption of capillary equilibrium. The effective parameters are calculated using effective media approaches. We also discuss the limits of the applicability of these methods.
Spatial patterns of probabilistic temperature change projections from a multivariate Bayesian analysis
Authors: Furrer R. , Knutti R. , Sain S. R. , Nychka D. W. , Meehl G. A.
Published: March 2007

We present probabilistic projections for spatial patterns of future temperature change using a multivariate Bayesian analysis. The methodology is applied to the output from 21 global coupled climate models used for the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. The statistical technique is based on the assumption that spatial patterns of climate change can be separated into a large scale signal related to the true forced climate change and a small scale signal due to model bias and variability. The different scales are represented via dimension reduction techniques in a hierarchical Bayesian model. Posterior probabilities are obtained with a Markov chain Monte Carlo simulation. We show that with 66% (90%) probability 79% (48%) of the land areas warm by more than 2°C by the end of the century for the SRES A1B scenario.
Afterslip (and only afterslip) following the 2004 Parkfield, California, earthquake
Authors: Freed Andrew M.
Published: March 2007

An analysis of the first two years of postseismic surface deformations from GPS reveals that afterslip is the only mechanism significantly contributing to postseismic deformation following the 2004 M6 Parkfield, California earthquake. Finite element modeling shows this event to have been too small to significantly stress the lower crust and upper mantle, thus viscoelastic relaxation did not lead to detectable surface displacements. Similarly, coseismically induced pressure changes in the upper crust were not sufficient to induce a measurable poroelastic response. From 10 days to two years after the Parkfield earthquake, postseismic displacements at all GPS stations experience the same characteristic decay time (∼2 weeks). This suggests that only afterslip was activated and the distribution of slip remained unchanged in this time period. Afterslip was found to be broadly distributed in the upper 15 km of the crust and associated with a moment release of much greater magnitude than the coseismic rupture.
Deviations from ozone photostationary state during the International Consortium for Atmospheric Research on Transport and Transformation 2004 campaign: Use of measurements and photochemical modeling to assess potential causes
Authors: Griffin Robert J. , Beckman Pieter J. , Talbot Robert W. , Sive Barkley C. , Varner Ruth K.
Published: March 2007

Nitric oxide (NO) and nitrogen dioxide (NO2) were monitored at the University of New Hampshire Atmospheric Observing Station at Thompson Farm (TF) during the ICARTT campaign of summer 2004. Simultaneous measurement of ozone (O3), temperature, and the photolysis rate of NO2 (jNO2) allow for assessment of the O3 photostationary state (Leighton ratio, Φ). Leighton ratios that are significantly greater than unity indicate that peroxy radicals (PO2), halogen monoxides, nitrate radicals, or some unidentified species convert NO to NO2 in excess of the reaction between NO and O3. Deviations from photostationary state occurred regularly at TF (1.0 ≤ Φ ≤ 5.9), particularly during times of low NOx (NOx = NO + NO2). Such deviations were not controlled by dynamics, as indicated by regressions between Φ and several meteorological parameters. Correlation with jNO2 was moderate, indicating that sunlight probably controls nonlinear processes that affect Φ values. Formation of PO2 likely is dominated by oxidation of biogenic hydrocarbons, particularly isoprene, the emission of which is driven by photosynthetically active radiation. Halogen atoms are believed to form via photolysis of halogenated methane compounds. Nitrate radicals are believed to be insignificant. Higher Φ values are associated with lower mixing ratios of isoprene and chloroiodomethane and lower ratios of NOx to total active nitrogen, indicating that photochemical aging may very well lead to increased Φ values. PO2 levels calculated using a zero‐dimensional model constrained by measurements from TF can account for 71% of the observed deviations on average. The remainder is assumed to be associated with halogen atoms, most likely iodine, with necessary mixing ratios up to 0.6 or 1.2 pptv, for chlorine and iodine, respectively.
Environmental drivers of evapotranspiration in a shrub wetland and an upland forest in northern Wisconsin
Authors: Mackay D. Scott , Ewers Brent E. , Cook Bruce D. , Davis Kenneth J.
Published: March 2007

To improve our predictive understanding of daily total evapotranspiration (ET), we quantified the differential impact of environmental drivers, radiation (Q), and vapor pressure deficit (D) in a wetland and upland forest. Latent heat fluxes were measured using eddy covariance techniques, and data from four growing seasons were used to test for (1) environmental drivers of ET between the sites, (2) interannual differences in ET responses to environmental drivers, and (3) changes in ET responses to environmental drivers between the leaf expansion period and midsummer. Two simple ET models derived from coupling theory, one radiation‐based model, and another using mass transfer were used to examine the mechanisms underlying the drivers of ET. During summer months, ET from the wetland was driven primarily by Q, whereas it was driven by D in the upland. During the leaf expansion period in the upland forest the dominant driver was Q. ET from the wetland was linearly related to net radiation using coupling coefficients ranging from a low of 0.3–0.6 to a high of 1.0 between early May and midsummer. Interannually, ET from the upland forest exhibited near linear responses to D, with an effective reference canopy stomatal conductance varying from 1 to 5 mm s−1. The results show that ET predictions in northern Wisconsin and other mixed wetland‐upland forests need to consider both wetland and upland forest processes. Furthermore, leaf phenology effects on ET represent a knowledge gap in our understanding of seasonal environmental drivers.
S100A1 and S100B, transcriptional targets of SOX trio, inhibit terminal differentiation of chondrocytes
Authors: Saito Taku , Ikeda Toshiyuki , Nakamura Kozo , Chung Ung‐il , Kawaguchi Hiroshi
Published: March 2007

Transcription factor SOX9 (sex‐determining region Y‐type high mobility group box 9) and its coactivators SOX5 and SOX6 (the SOX trio) induce early‐stage chondrocyte differentiation and suppress its terminal stage. To identify possible targets of the SOX trio, we carried out a microarray analysis and identified S100A1 and S100B as possible target molecules. S100 protein expression was localized in late proliferative and pre‐hypertrophic chondrocytes of the mouse growth plate. Overexpression of S100A1, S100B or their combination in cultured chondrogenic cells did not induce early differentiation, but suppressed hypertrophic differentiation and mineralization. Silencing of both S100A1 and S100B stimulated terminal differentiation and reversed the SOX‐trio‐mediated inhibition. Finally, luciferase reporter, electrophoretic mobility shift and chromatin immunoprecipitation analyses showed that transcription of both S100 proteins is induced by the SOX trio, and also identified their respective enhancer elements in the 5′‐end flanking region. We conclude that S100A1 and S100B are transcriptional targets of the SOX trio and mediate its inhibition of terminal differentiation of chondrocytes.