bluuebunny/crossref_metadata_2025 huggingface dataset:
The Trans-Peninsular Highway: A New Era for Baja California
Authors: Barkenbus Jack N.
Published: March 2007

As Mexican President Luis Echeverria Alvarez strode to the dedication stand, confetti and rose petals filled the air; and upon raising the Mexican flag at the base of a 135-foot-high statue located in the middle of the Baja California desert, more than 5,000 peopled cheered, “Viva Mexico, viva la carretera” (the highway). The occasion of the recent dedication and praise was the completion of the first paved highway that effectively links northern and southern sections of Baja California. To North Americans who have been numbed by the dizzying pace of superhighway construction, this single, rather narrow, twolane highway may seem of scarce consequence. But for the inhabitants of the Baja California peninsula, one of the most desolate areas of land on this earth, the 1,061-mile highway heralds a new era. This paper intends to explore some of the economic and political consequences likely to evolve from the road's existence. More specifically, it examines the basic objectives Mexican officials bring to the highway, and posits the likelihood of the fulfillment of these objectives.
Interest Groups in the Colombian Congress: Group Behavior in a Centralized, Patrimonial Political System
Authors: Kline Harvey F.
Published: March 2007

The use of “group” as a unit of analysis has a long tradition in political science. Some proponents of this approach (Bentley, 1908; Hagan, 1966) define group in such a broad way as to simplify the study of politics little if any. An empirically more useful approach to the study of groups is that pursued by David Truman (1955), who concentrates his attention on interest groups. Although he never states that all of the politics of the United States can be understood through the study of interest groups, it is clear that Truman considers the study of such groups to be a central aspect and, in effect, hypothesizes that such would be the case in any political system. Whether this is in fact the case can be tested by cross-national studies. In one such study, Joseph La Palombara (1960) concluded that the important aspects of Italian politics are not explained satisfactorily by studying organized interest groups. This is in direct contradiction to Truman's implicit hypothesis, which would be refuted if numerous studies in other political systems concluded as La Palombara's did.
The Dependency Model of Latin American Underdevelopment: Three Basic Fallacies
Authors: Ray David
Published: March 2007

This article attempts to examine the set of propositions loosely known as the dependency model of Latin American underdevelopment. The dependency model attributes such underdevelopment to the economic expansion of highly developed capitalist countries, particularly the United States. The model was first elaborated by Latin American economists and has subsequently acquired numerous adherents in the United States, especially among younger political scientists.

The basic premise of the dependency model is that the economic development of Latin America has been determined and limited by the needs of the dominant economies in the world capitalist market. Because they are thus conditioned and limited, the Latin American economies are described as “dependent.”
Education and Political Recruitment in Mexico
Authors: Camp Roderic Ai
Published: March 2007

Education is one of the variables most frequently used by students of bureaucracy to determine background characteristics of political elites (Cochrane, 1967; Gruber, 1971; Hopkins, 1967; de Imaz, 1970; Verner, 1973). Especially in Latin American research, scholars often examine educational levels of men who serve in high public office. Although such studies usually look at the type of education, the number of years of study, and the location of the institution, very few, if any, authors have examined the determining influence on the careers of future political elites of student contact as well as student to faculty relationships at the preparatory school or university. The omission is significant because it is the contention of this paper that at least since the 1946 presidential administration in Mexico, contact which took place during the school days of future political leaders was an important form of recruitment.
Addition and Substitution Reactions of Nitrile‐Stabilized Carbanions
Authors: Arseniyadis Siméon , Kyler Keith S. , Watt David S.
Published: March 2007

The utilization of carbanions stabilized by various electron‐withdrawing groups to effect carboncarbon bond formation occupies a central position in organic synthesis. This chapter focuses on the reactions of nitrile‐stabilized carbanions with an array of carbon electrophiles and updates another chapter along these lines in this series. Subsequent review articles have dealt with various aspects of the chemistry of nitrile‐stabilized carbanions. In this review, the reactions of nitrile‐stabilized anions are grouped according to the nature of the substituents attached to the carbanion center bearing the nitrile group. These substituents include alkyl, alkenyl, alkynyl, and aryl groups as well as various α‐oriented halogen‐, oxygen‐, nitrogen‐, sulfur‐, and selenium‐containing groups. Notably absent from this survey are the carbanions derived from active methylene compounds bearing two electron‐withdrawing groups such as cyanoacetate esters, malononitriles, α‐sulfonylnitriles, and α‐phosphorylnitriles. Also absent are those carbanions such as Reissert compounds, which are the subject of comprehensive reviews.

The chapter is arbitrarily subdivided into six sections: (1) reactions of alkyl‐, aryl‐, and heteroaryl‐substituted nitriles; (2) reactions of α,β‐ and β,γ‐unsaturated nitriles as well as tolunitriles; (3) reactions of cyanohydrins and their hydroxyl‐protected derivatives; (4) reactions of nitriles bearing α‐sulfur and α‐selenium substituents; (5) reactions of α‐(dialkylamino)nitriles; and (6) reactions of α‐halonitriles. Within each of these sections, the reactions are further subdivided according to the nature of the electrophile: (1) alkylation reactions employing alkyl halides, alkyl sulfonates, dialkyl sulfates, and epoxides; (2) arylation reactions involving the substitution of hydrogen, halogen, nitro, or alkoxy groups on aryl or heteroaryl substrates; (3) acylation reactions employing carboxylic esters, anhydrides, acid chlorides, dialkyl carbonates, and nitriles; (4) addition reactions involving aldehydes, ketones, imines, alkenes, and alkynes; and (5) Michael‐type addition reactions to unsaturated aldehydes, ketones, imines, sulfoxides, sulfones, and nitro compounds. Finally, a section involving cyclization reactions is included for each of the six groups of nitrile‐stabilized anions.
Diels‐Alder Reactions of Imino Dienophiles
Authors: Heintzelman Geoffrey R. , Meigh Ivona R. , Mahajan Yogesh R. , Weinreb Steven M.
Published: March 2007

In comparison to all carbon [4 + 2] cycloadditions, Diesl‐Alder reactions are still in their infancy. The last four decades, however, have seen intensive research in this area. The results if that synthetic organic chemists now have a powerful tool at their disposal for rapid construction of highly functionalized six‐membered nitrogen heterocycles, often in a regio‐, diastereo‐, and enantioselective manner.

This chapter encompasses the topic of imine[4 + 2] cycloaddition reactions, of which there are a number of variants. This chapter is limited exclusively to imine and iminium ion dienophiles that undergo inter‐ and intramolecular Diels‐Alder reactions with acylic and cyclic all‐carbon 1,3‐dienes affording 1,2,5,6‐tetrahydropyridines as the initial cycloadducts. In situations where there is a mechanistic ambiguity, such as reactions that proceed via Mannich reactions, these mechanisms are included since it is difficult to know where to draw the line on coverage.

A comprehensive discussion of each structural type of imino dienophiles covers the literature up to the middle of 2004. A general overview of mechanistic, regiochemical, and sterochemical considerations is also presented. Specific relevant exo/endo issues, remote diasteroselectivity and the use of chiral auxiliaries are discussed under each separate imine type. Separate sections have also been included that describe intramolecular reactions, as well as more recent advances in enantioselective cycloadditions involving chiral catalysts.
Fibronectin and culture temperature modulate the efficacy of an avidin–biotin binding system for chondrocyte adhesion and growth on biodegradable polymers
Authors: Tsai Wei‐Bor , Wang Peng‐Yuan , Chang Yung , Wang Min‐Cheng
Published: March 2007

Cell adhesion to a scaffold is a prerequisite for tissue engineering. Many studies have been focused on enhancing cell adhesion to synthetic materials that are used for scaffold fabrication. Previously, we showed that immobilization of biotin molecules to chondrocyte surfaces enhanced cell adhesion to avidin‐coated biodegradable polymers such as poly‐L‐lactic acid, poly‐D,L‐lactic acid and polycaprolactone. However, the endocytosis of cell membrane biotin molecules decreases binding strength between biotinylated‐chondrocytes (B‐chondrocytes) and avidin‐coated substrata, and therefore decreases cell spreading and discourages long‐term chondrocytes culture. In this study, we proposed two strategies to solve the shortcoming of the avidin–biotin binding system. First, the avidin–biotin binding system is combined with the intrinsic integrin‐dependent adhesion systems in order to enhance long‐term cell culture. Second, the incubation temperature is lowered in order to slow down the endocytosis process. We found that the avidin–biotin binding system in combination with FN–integrin binding system enhanced cell adhesion, cell spreading and cell growth. Decrease of cell culture temperature to 4°C enhanced the adhesion of B‐chondrocytes to the avidin‐coated surfaces, but decreased cell viability and proliferation, compared to culture temperature of 37°C. Whether there is an optimal seeding temperature between 4 and 37°C for both adhesion and proliferation of B‐chondrocytes needs further investigation. Our results indicated that modulation of the adhesion conditions could further enhance the efficacy of the avidin–biotin binding system in mediating cell adhesion, and subsequent tissue culture. Biotechnol. Bioeng. 2007;98; 498–507. © 2007 Wiley Periodicals, Inc.
Gas‐chromatographic approach to probe the absence of molecular inclusion in enantioseparations by carbohydrates. Investigation of linear dextrins (“acyclodextrins”) as novel chiral stationary phases
Authors: Sicoli Giuseppe , Pertici Francesca , Jiang Zhengjin , Jicsinszky Lazslo , Schurig Volker
Published: March 2007

Acetylated/silylated maltooligosaccharides with different degrees of oligomerization have been tested as chiral stationary phases for enantioselective gas chromatography. The acyclic dextrin derivatives carrying tert‐butyldimethylsilyl groups at the primary hydroxyl sites and acetyl groups at the secondary hydroxyl sites showed an unexpected ability for the enantioseparation of α‐amino acid derivatives and halogenated compounds, in addition to some underivatized chiral compounds. Some examples of an improved enantioselectivity invoked by the linear CSPs as compared to that of cyclic oligosaccharides are demonstrated in this work. The results highlight the role of the polar external surface of the selector in lieu of the well‐established inclusion mechanism of enantiorecognition by cyclic dextrins. Thus, the enantioseparation of chiral compounds on linear dextrin derivatives—devoid of a molecular cavity—sheds a new light on the mechanisms of enantiorecognition by cyclodextrin derivatives. In contrast to cyclodextrins, linear dextrins are readily accessible in both enantiomeric forms. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Evaluation of enantioselective gas chromatography for the determination of minute deviations from racemic composition of α‐amino acids with emphasis on tyrosine: Accuracy and precision of the method
Authors: Reiner Clarissa , Nicholson Graeme J. , Nagel Ulrich , Schurig Volker
Published: March 2007

Whereas the determination of high enantiomeric fractions (EF) of chiral compounds is very well established, the accurate determination of small deviations from racemic compositions has not yet received much attention despite its relevance to studies dealing with the origin of homochirality, where only small initial enantiomeric bias is expected. Racemic samples of representative α‐amino acids were derivatized as N‐(O,S)‐trifluoroacetyl/ethylesters and analyzed by enantioselective gas chromatography (GC) on fused silica capillaries coated with the chiral stationary phases (CSPs) Chirasil‐D‐Val, Chirasil‐L‐Val, and Lipodex E with GC/FID and GC/MS detection. The validation (accuracy and precision) of the determination of the enantiomeric fraction EF of the D‐enantiomer in racemic or near‐racemic compositions for 10 DL‐α‐amino acids obtained from commercial sources has been carried out. Emphasis is given to DL‐tyrosine, the enantiomers of which have recently been claimed to show different crystallization properties. Values of EF obtained from GC measurements using CSPs were compared with those from CE using chiral mobile phase additives. While the precision of the GC method is generally better than 0.08% for all DL‐α‐amino acids studied, accuracy (trueness) of determination of amino acids with polar side chains is poorer than expected from the precision as a result of systematic errors. The accuracy determined relied on measurements on two oppositely configurated CSPs. Chirality, 2007. © 2007 Wiley‐Liss, Inc.
Exploration on Regulating Factors for Proton Transfer along Hydrogen‐Bonded Water Chains
Authors: Yan Shihai , Zhang Liang , Cukier Robert I. , Bu Yuxiang
Published: March 2007

Proton transfer along a single‐file hydrogen‐bonded water chain is elucidated with a special emphasis on the investigation of chain length, side water, and solvent effects, as well as the temperature and pressure dependences. The number of water molecules in the chain varies from one to nine. The proton can be transported to the acceptor fragment through the single‐file hydrogen‐bonded water wire which contains at most five water molecules. If the number of water molecule is more than five, the proton is trapped by the chain in the hydroxyl‐centered H7O3+ state. The farthest water molecule involved in the formation of H7O3+ is the fifth one away from the donor fragment. These phenomena reappear in the molecular dynamics simulations. The energy of the system is reduced along with the proton conduction. The proton transfer mechanism can be altered by excess proton. The augmentation of the solvent dielectric constant weakens the stability of the system, but favors the proton transfer. NMR spin–spin coupling constants can be used as a criterion in judging whether the proton is transferred or not. The enhancement of temperature increases the thermal motion of the molecule, augments the internal energy of the system, and favors the proton transfer. The lengthening of the water wire increases the entropy of the system, concomitantly, the temperature dependence of the Gibbs free energy increases. The most favorable condition for the proton transfer along the H‐bonded water wire is the four‐water contained chain with side water attached near to the acceptor fragment in polar solvent under higher temperature.
On the effect of the rigid sidewall on the dynamic stiffness of embedded circular footings
Authors: Tassoulas John L. , Kausel Eduardo
Published: March 2007

The effect of the rigid sidewall, which is usually combined with embedded footings, on the dynamic stiffness of the footings is considered. An efficient numerical technique is used to calculate the static and dynamic stiffness of circular footings embedded in a stratum. The results show that the increase in static stiffness with increasing height of the sidewall is most significant in the case of rocking. The dynamic stiffness coefficients change considerably, if the sidewall extends higher than about half the depth of embedment. The damping coefficients corresponding to vertical vibrations and rocking are likewise affected by the height of the sidewall. The damping coefficients corresponding to torsional and horizontal vibrations increase considerably with increasing height of the sidewall.
Role of enzyme‐treated cells in RBC antibody screening using the gel test: a study of anti‐RH1, ‐RH2, and ‐RH3 antibodies
Authors: Conne Jocelyne , Schneider Philippe , Tissot Jean‐Daniel
Published: March 2007

The role of enzyme‐treated cells (ETCs) in red blood cell (RBC) antibody screening has been the subject of controversy, and its place in the clinical routine remains to be determined. In this work, plasma samples containing anti‐RH1 (anti‐D; N = 10), anti‐RH2 (anti‐C; N = 10), or anti‐RH3 (anti‐E; N = 10) antibodies were studied. The samples were diluted in nonbuffered or buffered normal saline, as well as in a pool of AB plasma samples. Titers and scores were determined by means of the gel test, using the indirect antiglobulin test (IAT) as well as ETCs, with R0r, r′r, or r″r test cells. Our results showed that compared to the IAT, ETCs allowed a clearer detection of anti‐RH2 and anti‐RH3, but not of anti‐RH1 antibodies. Based on our study, it is not clear whether the ETC phase of the gel test should be maintained for RBC antibody screening. J. Clin. Lab. Anal. 21:61–66, 2007. © 2007 Wiley‐Liss, Inc.
Woodchuck dendritic cells generated from peripheral blood mononuclear cells and transduced with recombinant human adenovirus serotype 5 induce antigen‐specific cellular immune responses
Authors: Ochoa‐Callejero Laura , Berraondo Pedro , Crettaz Julien , Olagüe Cristina , Vales África , Ruiz Juan , Prieto Jesús , Tennant Bud C. , Menne Stephan , González‐Aseguinolaza Gloria
Published: March 2007

Woodchucks infected with the woodchuck hepatitis virus (WHV) is the best available animal model for testing the immunotherapeutic effects of dendritic cells (DCs) in the setting of a chronic infection, as woodchucks develop a persistent infection resembling that seen in humans infected with the hepatitis B virus. In the present study, DCs were generated from woodchuck peripheral blood mononuclear cells (wDCs) in the presence of human granulocyte macrophage colony‐stimulating factor (hGM‐CSF) and human interleukin 4 (hIL‐4). After 7 days of culture, cells with morphology similar to DCs were stained positively with a cross‐reactive anti‐human CD86 antibody. Functional analysis showed that uptake of FITC‐dextran by wDCs was very efficient and was partially inhibited after LPS‐induced maturation. Furthermore, wDCs stimulated allogenic lymphocytes and induced proliferation. Moreover, wDCs were transduced efficiently with a human adenovirus serotype 5 for the expression of β‐galactosidase. Following transduction and in vivo administration of such DCs into woodchucks, an antigen‐specific cellular immune response was induced. These results demonstrate that wDCs can be generated from the peripheral blood. Following transfection with a recombinant adenovirus wDCs can be used as a feasible and effective tool for eliciting WHV‐specific T‐cell responses indicating their potential to serve as prophylactic and therapeutic vaccines. J. Med. Virol. 79:522–529, 2007. © 2007 Wiley‐Liss, Inc.
Human herpesvirus 8 (HHV‐8) infection in healthy urban employees from Greece: Seroprevalence and associated factors
Authors: Zavitsanou Assimina , Sypsa Vana , Petrodaskalaki Maria , Kalapothaki Victoria , Whitby Denise , Hatzakis Angelos
Published: March 2007

A cross‐sectional study was carried out in healthy company employees from Greece with the aim of assessing the prevalence of human herpesvirus 8 (HHV‐8) and identifying risk factors for this herpesviral infection. Serum samples obtained from 955 subjects were tested for antibodies to HHV‐8 by the K8.1 enzyme‐linked immunosorbent assay (ELISA). Associations between HHV‐8 serostatus and potential risk factors were examined using t‐test, chi square test, and multivariate logistic regression analysis. HHV‐8 prevalence was 7.6% (95% confidence interval (CI): 6.0%, 9.5%) and it increased with age from 6.5% among <30 years old to 13.8% among ≥50 years old subjects (P = 0.006). HHV‐8 seropositivity was independently associated with endoscopic examination (odds ratio (OR): 2.01; 95% CI: 1.09, 3.70; P = 0.026), HBsAg positivity (OR: 5.16; 95% CI: 2.02, 13.20; P = 0.001) and age (OR ≥50 years old vs. <50 years old: 2.09; 95% CI: 1.23, 3.52; P = 0.006). No statistically significant associations between HHV‐8 positive status and gender, occupational status, surgery, transfusion, tattoos/body piercing, multiple sex partners, weakness/fatigue, HCV status were observed. HHV‐8 is prevalent in Greece. The strong association between HBV infection and HHV‐8 positive status supports the hypothesis of an association between these two viral infections. The association between HHV‐8 seropositivity and endoscopic examination requires further investigation. J. Med. Virol. 79:591–596, 2007. © 2007 Wiley‐Liss, Inc.
Influence of HCV genotype and co‐infection with human immunodeficiency virus on CD4+ and CD8+ T‐cell responses to hepatitis C virus
Authors: Capa Laura , Soriano Vincent , García‐Samaniego Javier , Nuñez Marina , Romero Miriam , Cascajero Almudena , Muñoz Fernando , González‐Lahoz Juan , Benito José M.
Published: March 2007

The role of T‐cells in clearance of hepatitis C virus (HCV) during acute infection is critical. The relevance of the immunological response in the control of HCV replication is less clear in chronic HCV infection. HCV‐specific T‐cell responses were examined in 92 interferon‐naive individuals with chronic hepatitis C. A panel of 441 overlapping peptides spanning all expressed HCV proteins was used to measure HCV‐specific T‐cell responses, using flow cytometry after stimulating peripheral blood mononuclear cells (PBMCs) with different pools of these peptides. Most patients showed responses to at least one HCV protein, with NS5B for CD8+ responses and E2 for CD4+ responses identified most frequently. Both the prevalence and breadth of CD4+ and CD8+ responses were lower in co‐infected patients, independently of the HCV genotype. J. Med. Virol. 79:503–510, 2007. © 2007 Wiley‐Liss, Inc.
Signal polynomial smoothing from correlated interrupted observations based on covariances
Authors: Nakamori S. , Caballero‐Águila R. , Hermoso‐Carazo A. , Jiménez‐López J. D. , Linares‐Pérez J.
Published: March 2007

The least‐squares polynomial smoothing problem of discrete‐time signals from uncertain observations is addressed, when the variables describing the uncertainty are correlated at consecutive sampling times. Defining suitable augmented signal and observation vectors, the polynomial estimation problem is reduced to the linear estimation problem of the augmented signal. By an innovation
approach, recursive algorithms are derived for the augmented linear estimators without requiring the knowledge of the state‐space model generating the signal, but only covariance information of the processes involved. Copyright © 2007 John Wiley & Sons, Ltd.
Revisiting the constitutive equations of unsaturated porous solids using a Lagrangian saturation concept
Authors: Coussy O.
Published: March 2007

This paper aims at revisiting the constitutive equations of unsaturated porous solids at the light of a Lagrangian saturation concept. By referring the currently wetted porous volume to the reference configuration, the Lagrangian saturation is the state variable associated with the interfacial energy changes only, irrespective of the elastic energy required for deforming the solid matrix. The Lagrangian saturation concept provides the basis of a generic approach to the theory of poroelastoplasticity in unsaturated conditions. We successively examine the case where the saturating fluids occupy disconnected networks and the case where the networks are connected so that the saturating fluids can invade the porous solid or recede from it. The analysis provides the restricted situations where the averaged pore pressure may play the role of an effective pore pressure. Copyright © 2007 John Wiley & Sons, Ltd.
Modeling particle inflation from poly(amic acid) powdered precursors. I. Preliminary stages leading to bubble growth
Authors: Cano Camilo I. , Kyu Thein , Pipes R. Byron
Published: March 2007

Morphological characteristics of polyimide microstructures obtained by solid‐state powder foaming determine the geometric properties of the unit cell, in polyimide foams prepared by this process. Morphological analysis of precursor particles has shown that particle size and shape, as well as the presence of embedded microvoids, exert a strong influence on the final microstructure morphology. Of equal importance in the morphological development are processing conditions such as heating rate and primary blowing agent content in the particles, prior to thermal treatment.

In the present paper, the first of two numerical schemes is presented. A numerical model has been developed to study the preliminary stages that lead to particle inflation. Based on this model, a parametric analysis is performed for pertinent governing parameters, with the purpose of determining their effect on the onset of particle inflation and the potential morphological characteristics of polyimide microstructures. It has been found that precursor particle morphology and nuclei density are the key parameters in determining the potential morphology of the microstructures, by limiting the number of bubbles that grow within each particle. POLYM. ENG. SCI., 47:560–571, 2007. © 2007 Society of Plastics Engineers.
Predictions of two nonlinear viscoelastic constitutive relations for polymers under multiaxial loadings
Authors: Ellyin F. , Vaziri R. , Bigot L.
Published: March 2007

Two viscoelastic constitutive relations in differential form are further developed here to include material nonlinearity and distinction between loading and unloading regimes, which is a characteristic of polymers. The effects of hydrostatic pressure and anisotropy in tension and compression on the deformation response of polymers are accounted for through the definition of a pressure‐dependent equivalent stress. In the uniaxial stress state, these constitutive relations reduce to the two well‐known mechanical analogue representations: “Kelvin–Voigt‐type” and “Maxwell‐type” rheological models. The predictive capabilities of these constitutive relations are then assessed against a wide range of experimental results, which include both uniaxial and biaxial stress states subjected to quasi‐static and cyclic‐loading conditions. The predictions of both models are found to be in good agreement with the test data. POLYM. ENG. SCI., 47:593–607, 2007. © 2007 Society of Plastics Engineers.
Superabsorbent composite. XIII. Effects of Al3+‐attapulgite on hydrogel strength and swelling behaviors of poly(acrylic acid)/Al3+‐attapulgite superabsorbent composites
Authors: Zhang Junping , Zhao Yaogang , Wang Aiqin
Published: March 2007

Al3+‐attapulgite (Al3+‐APT) was prepared by treating attapulgite (APT) with AlCl3 aqueous solution of various concentrations. The poly(acrylic acid)/Al3+‐attapulgite (PAA/Al3+‐APT) superabsorbent composite was prepared by reaction of partly neutralized acrylic acid, and Al3+‐APT in aqueous solution using N, N′‐methylenebisacrylamide as a crosslinker and ammonium persulfate as an initiator. The surface morphology of the composite was investigated by SEM, and the Al3+‐APT composite generated a relatively planar surface comparing the nature APT. The effects of Al3+‐APT on hydrogel strength and swelling behaviors, such as equilibrium water absorbency, swelling rate, and reswelling capability, of the superabsorbent composites were also studied. The hydrogel strength and reswelling capability were improved, however, the equilibrium water absorbency and swelling rate decreased with increasing AlCl3 solution concentration. The equilibrium water absorbency firstly increased, and then decreased with increasing Al3+‐APT content. The results indicate that Al3+‐APT acts as an assistant crosslinker in the polymeric network, which has great influences on hydrogel strength and swelling behaviors of the PAA/Al3+‐APT superabsorbent composites. POLYM. ENG. SCI., 47:619–624, 2007. © 2007 Society of Plastics Engineers.
Approximate prediction of gas core geometry in gas assisted injection molding using a short cut method
Authors: Polynkin A. , Pittman J.F.T. , Sienz J.
Published: March 2007

A relatively cheap, short cut method for prediction of the form and location of the gas core, and the residual plastic wall thickness in gas assisted injection molding (GAIM) is described. The basis is a steady state, single phase solution for flow of the polymer melt through the channel of interest, without the need to model the gas penetration. The gas‐polymer interface position is predicted by an appropriately chosen isovel of the flow. For a prismatic or slowly varying channel, only a two‐dimensional developed flow solution is required. For more sharply varying cross sections, and where bends are present, a steady three‐dimensional (3D) solution is necessary. When a gas delay is used, during which polymer cools to the cavity walls, a solution for transient conduction in the static melt is carried out before the flow solution. By comparisons with the results of full 3D, transient, two‐phase simulations of GAIM, and with experimental results, the short cut method is shown to provide reasonable approximations, and in contrast to other currently used approximate methods, captures thickness variations around the circumference of noncircular channels. The asymmetric gas core location in bends is reproduced, as is the increased plastic wall thickness resulting from cooling during a gas delay. While the full analysis will still be required for complex parts and when high accuracy is required, the described short cut method is likely to prove useful in many other cases. POLYM. ENG. SCI., 47:713–720, 2007. © 2007 Society of Plastics Engineers.
Particle nucleation rates in continuous emulsion polymerisation reactors
Authors: Brooks Brian W.
Published: March 2007

The design of a continuous, stirred emulsion polymerisation reactor requires a detailed characterisation of the particle nucleation rate. Here, consideration is given to systems which use micelle‐forming surfactants and water‐insoluble monomers. The surfactant micelles will be considered to participate in two competing rate processes; the nucleation of polymer particles and dissolution into the aqueous phase.

When the reactor operates in a steady state it is possible to obtain a size distribution function for the particles. This distribution function is used in the development of a number of diffusion equations and conservation equations. By making various sets of assumptions concerning the nucleation process, these equations are then used to obtain expressions for the particle number. By comparing the different models with experimental results it can be seen that satisfactory predictions for the particle number can be obtained without assuming that the polymer particles are always saturated with surfactant. The models also show that the radical absorption processes are not controlled by diffusion in the aqueous phase.

In some cases the particle number does not reach a steady state but oscillates with time. The nature of these oscillations is described by the solution of nonlinear differential equations. Boundary conditions for these equations depend on the reaction conditions.
Molecular recognition mechanism of FK506 binding protein: An all‐electron fragment molecular orbital study
Authors: Nakanishi Isao , Fedorov Dmitri G. , Kitaura Kazuo
Published: March 2007

The fragment molecular orbital (FMO) method has enabled electronic structure calculations and geometry optimizations of very large molecules with ab initio quality. We applied the method to four FK506 binding protein (FKBP) complexes (denoted by their PDB codes 1fkb, 1fkf, 1fkg, and 1fki) containing rapamycin, FK506, and two synthetic ligands. The geometries of reduced complex models were optimized at the restricted Hartree–Fock (FMO‐RHF) level using the 3‐21G basis set, and then for a better estimate of binding, the energetics were refined at a higher level of theory (2nd order Møller–Plesset perturbation theory FMO‐MP2 with the 6‐31G* basis set). Thus, obtained binding energies were −103.9 (−82.0), −102.2 (−69.2), −70.1 (−57.7), and −71.3 (−55.3) kcal/mol for 1fkb, 1fkf, 1fkg, and 1fki, respectively, where the correlation contribution is given in parentheses. The results show that the electron correlation contribution to binding is extremely important, and it accounts for 70–80% of the binding energy. The molecular recognition mechanism of FKBP was analyzed in detail based on the FMO‐pair interactions between protein residues and the ligands. Solvation effects on the protein–ligand binding were estimated using the Poisson–Boltzmann/surface area model. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Residual toxicity of two insecticides on three field populations of Lygus lineolaris (Hemiptera: Miridae) collected along the St Lawrence valley in eastern Canada
Authors: Fleury Dominique , Bostanian Noubar J , Mauffette Yves , Vincent Charles
Published: March 2007

Insecticides are still the single main pest control method employed today by most growers to mitigate damage done by the tarnished plant bug, Lygus lineolaris (Palisot de Beauvois) (Hemiptera: Miridae). In eastern Canada, the complex agricultural ecosystem, which may be described as a mosaic of farmlands dispersed among natural habitats (forest, prairies), allows tarnished plant bug adults to fly and move from sprayed to non‐sprayed areas. In 2004 (late August to early September), three populations of L. lineolaris were collected from three mixed vegetation strips adjacent to orchards and vineyards along the St Lawrence valley: the Niagara Peninsula (Ontario), Dunham (Quebec) and La Pocatière (Quebec). Assays were done in the laboratory by confining adults in glass vials coated with dried residues. The estimated LC50 values for the three populations varied from 11.2 to 16.8 × 10−5 g L−1 for azinphos‐methyl and from 0.8 to 1.4 × 10−5 g L−1 for cypermethrin. In contrast to the Mississippi delta, no tolerance to insecticides was found in the populations collected. Possible explanations for this non‐tolerance to insecticides includes a very low selection pressure as a result of the reduced number of insecticide treatments done in the context of the diversified agricultural landscapes encountered in eastern Canada which allow movements of adults from treated to non‐treated areas. Copyright © 2007 Society of Chemical Industry
Performance comparison of rough‐terrain robots—simulation and hardware
Authors: Thueer Thomas , Krebs Ambroise , Siegwart Roland , Lamon Pierre
Published: March 2007

The design of a rover for a specific environment is a complex procedure which requires modeling a chassis and evaluating it with specific criteria. This is the aim of the performance optimization tool (POT) presented in this paper. The POT enables the comparison and optimization of a rover chassis in a quick and efficient way. The tool is based on a static approach including optimization of the wheel torques in order to maximize traction. Tests with real hardware were performed to validate the POT. Two different rovers, CRAB and RCL‐E, were assessed in simulation and hardware with respect to specific, well defined metrics. In simulation, their performances were compared to the rocker‐bogie‐type rover MER. CRAB and MER showed similar performance, while RCL‐E had significant problems with the benchmark obstacle. A very good match between simulation results and real measurements was achieved. © 2007 Wiley Periodicals, Inc.
The diameter of randomly perturbed digraphs and some applications
Authors: Flaxman Abraham D. , Frieze Alan M.
Published: March 2007

The central observation of this paper is that if εn random arcs are added to any n‐node strongly connected digraph with bounded degree then the resulting graph has diameter 𝒪(lnn) with high probability. We apply this to smoothed analysis of algorithms and property testing.

Smoothed Analysis: Recognizing strongly connected digraphs is a basic computational task in graph theory. Even for digraphs with bounded degree, it is NL‐complete. By XORing an arbitrary bounded degree digraph with a sparse random digraph R ∼ 𝔻n,ε/n we obtain a “smoothed” instance. We show that, with high probability, a log‐space algorithm will correctly determine if a smoothed instance is strongly connected. We also show that if NL ⫅̸ almost‐L then no heuristic can recognize similarly perturbed instances of (s,t)‐connectivity.

Property Testing: A digraph is called k‐linked if, for every choice of 2k distinct vertices s1,…,sk,t1,…,tk, the graph contains k vertex disjoint paths joining sr to tr for r = 1,…,k. Recognizing k‐linked digraphs is NP‐complete for k ≥ 2. We describe a polynomial time algorithm for bounded degree digraphs, which accepts k‐linked graphs with high probability, and rejects all graphs that are at least εn arcs away from being k‐linked. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2007
Comparative whole-grain intake of British adults in 1986–7 and 2000–1
Authors: Thane Christopher W. , Jones Angela R. , Stephen Alison M. , Seal Christopher J. , Jebb Susan A.
Published: March 2007

Epidemiological evidence suggests that higher consumption of whole-grain foods can significantly reduce the risk of chronic diseases such as CVD, type 2 diabetes and some cancers. The present study compares whole-grain intake of 2086 adults aged 16–64 years from the 1986–7 Dietary and Nutritional Survey of British Adults with that of 1692 adults aged 19–64 years from the 2000–1 National Diet and Nutrition Survey. For each survey, whole-grain intake was estimated from consumption of all foods containing ≥ 10 % whole-grain content (as DM/fresh weight of food) from 7 d weighed dietary records. In 1986–7, median whole-grain intake was 16 (interquartile range 0–45) g/d v. 14 (interquartile range 0–36) g/d in 2000–1 (P < 0·001). In 1986–7, 77 % of adults had less than three 16 g amounts of whole-grain intake/d; 25 % reported no whole-grain intake. In 2000–1, corresponding percentages were 84 and 29 %, respectively. Foods with < 51 % whole-grain content provided 18 % of whole-grain intake in 1986–7 v. 27 % in 2000–1 (P < 0·001). In both surveys, whole-grain intake was significantly lower among adults with a manual v. non-manual occupation (indicative of lower socio-economic status) and among smokers v. non-smokers, independent of occupational social class. In 1986–7, whole-grain breakfast cereals and wholemeal bread contributed 28 and 48 % of whole-grain intake, respectively, v. 45 and 31 % in 2000–1. At each time, one-third of adults consumed neither of these two largest contributors to whole-grain intake. Findings from the present study suggest that whole-grain intake of British adults was low in 1986–7 and became even lower over the subsequent decade.
Relevance of apple consumption for protection against oxidative damage induced by hydrogen peroxide in human lymphocytes
Authors: Maffei Francesca , Tarozzi Andrea , Carbone Fabio , Marchesi Alessandra , Hrelia Silvana , Angeloni Cristina , Cantelli Forti Giorgio , Hrelia Patrizia
Published: March 2007

In a single-dosing crossover study, we investigated the ability of apple fruit consumption to protect human lymphocytes against peroxide-induced damage to DNA. Six healthy, non-smoking male volunteers were placed for 2 d on an antioxidant-poor (AP) diet. After 48 h of AP diet, the volunteers were required to consume a homogenate obtained from 600 g of red delicious unpeeled apples or water (500 ml); blood samples were collected 0, 3, 6 and 24 h post-consumption. To evaluate whether the apple intake was sufficient to restore resistance of DNA to oxidative damage, for each subject at any time point the plasma total antioxidant activity, reactive oxygen species (ROS) formation and induction of micronuclei (MN) in isolated lymphocytes following hydrogen peroxide (H2O2) treatment were measured. Results indicated a significant inhibition (58 %, P < 0·05) of H2O2-induced MN frequency in the plasma samples collected at 3 h after apple consumption, as compared with plasma samples collected at 0 h (4·17 (sd 1·83) v. 9·85 (sd 1·87) MN/1000 binucleated (BN) cells, respectively). A gradual return towards the value observed at 0 h was recorded starting from 6 to 24 h. MN frequency induced by H2O2 was significantly influenced by plasma total antioxidant activity (r = –0·95, P < 0·05) and by the increase of intracellular ROS formation (r = 0·88, P < 0·05). These findings suggest that the consumption of whole apple provides a useful dietary source of active scavengers to protect cells and tissue from oxidative stress and related DNA injury.
Products formed during fermentation of the prebiotic inulin with humangut flora enhance expression of biotransformation genes in human primarycolon cells
Authors: Sauer Julia , Richter Konrad Klaus , Pool-Zobel Beatrice Louise
Published: March 2007

Inulin-type fructans are fermented by gut bacteria to yield SCFA, including butyrate which is trophic for colonocytes and induces glutathioneS-transferases (GST) that detoxify carcinogens. Since little is known on similar effects by complex fermentation samples, we studied related products in non-transformed human colonocytes. Inulin enriched with oligofructose (1 : 1, Synergy1) was fermented with human gut flora. SCFA were quantified and a SCFA mixture was prepared accordingly. Colonocytes were incubated (4–12 h) with the Synergy1 fermentation supernatant (SFS), faeces control, a mixture of the three major SCFA (each 0–15 %, v/v) or butyrate (0–50 mm). Metabolic activity was determined to assess trophic effects and cytotoxicity. Expression of ninety-six genes related to biotransformation was studied using cDNA macroarrays. Results on modulated GST were reassessed with real-time PCR and GST activity was measured. Fermentation of inulin resulted in 2–3-fold increases of SCFA. The samples were non-cytotoxic. SFS increased metabolic activity, pointing to trophic effects. The samples modulated gene expression with different response patterns. Key results were thatGSTM2(2·0-fold) andGSTM5(2·2-fold) were enhanced by SFS, whereas the SCFA mixture reduced expression. The faeces control enhancedGSTA4(2·0-fold), but reducedGSTM2(0·2-fold) andGSTM5(0·2-fold). Real-time qPCR confirmed the induction ofGSTM2andGSTM5by SFS and ofGSTA4andGSTT2by butyrate. Activity of GST was not modulated. High concentrations of fermentation products were well tolerated by primary colonocytes, pointing to trophic effects. The induction of GST by the SFS may protect the cells from carcinogenic compounds.
Epigenetic regulation of transcription: a mechanism for inducing variations in phenotype (fetal programming) by differences in nutrition during early life?
Authors: Burdge Graham C. , Hanson Mark A. , Slater-Jefferies Jo L. , Lillycrop Karen A.
Published: March 2007

There is considerable evidence for the induction of different phenotypes by variations in the early life environment, including nutrition, which in man is associated with a graded risk of metabolic disease; fetal programming. It is likely that the induction of persistent changes to tissue structure and function by differences in the early life environment involves life-long alterations to the regulation of gene transcription. This view is supported by both studies of human subjects and animal models. The mechanism which underlies such changes to gene expression is now beginning to be understood. In the present review we discuss the role of changes in the epigenetic regulation of transcription, specifically DNA methylation and covalent modification of histones, in the induction of an altered phenotype by nutritional constraint in early life. The demonstration of altered epigenetic regulation of genes in phenotype induction suggests the possibility of interventions to modify long-term disease risk associated with unbalanced nutrition in early life.
Idempotent rank in endomorphism monoids of finite independence algebras
Authors: Gray R.
Published: March 2007

In 1992, Fountain and Lewin showed that any proper ideal of an endomorphism monoid of a finite independence algebra is generated by idempotents. Here the ranks and idempotent ranks of these ideals are determined. In particular, it is shown that when the algebra has dimension greater than or equal to three the idempotent rank equals the rank.
Ozone air quality and radiative forcing consequences of changes in ozone precursor emissions
Authors: West J. Jason , Fiore Arlene M. , Naik Vaishali , Horowitz Larry W. , Schwarzkopf M. Daniel , Mauzerall Denise L.
Published: March 2007

Changes in emissions of ozone (O3) precursors affect both air quality and climate. We first examine the sensitivity of surface O3 concentrations (O3srf) and net radiative forcing of climate (RFnet) to reductions in emissions of four precursors – nitrogen oxides (NOx), non‐methane volatile organic compounds, carbon monoxide, and methane (CH4). We show that long‐term CH4‐induced changes in O3, known to be important for climate, are also relevant for air quality; for example, NOx reductions increase CH4, causing a long‐term O3 increase that partially counteracts the direct O3 decrease. Second, we assess the radiative forcing resulting from actions to improve O3 air quality by calculating the ratio of ΔRFnet to changes in metrics of O3srf. Decreases in CH4 emissions cause the greatest RFnet decrease per unit reduction in O3srf, while NOx reductions increase RFnet. Of the available means to improve O3 air quality, therefore, CH4 abatement best reduces climate forcing.
Effects of currents on super‐ and sub‐harmonic waves in a two‐fluid system
Authors: Liu Chi‐Min , Hwung Hwung‐Hweng
Published: March 2007

Effects of currents on wave motions in a two‐fluid system are theoretically studied in this paper. Since super‐ and sub‐harmonic waves are naturally generated by the interaction of arbitrary linear waves, it is of theoretical and practical interest to investigate the influence of pure currents not only on linear waves, but also on second‐order waves. Solutions are derived using the perturbation technique. Solutions of internal Stokes waves recovered from present solutions are firstly discussed. Analyses of the super‐ and sub‐harmonic interactions are carried out for the deep‐ and shallow‐water configurations, respectively. Conditions resulting in the elimination of second‐order waves are determined. Present solutions include and unify most existing theories for the two‐ and single‐fluid systems, and are of great importance to the analysis of random internal waves.
Access to Chemistry
Authors: Higton Avril , Clemmet Mike , Golding Elaine , Jones Alan V
Published: March 2007

This text has been specifically designed to prepare people with previously limited chemical knowledge for entrance into science related courses (such as Foundation and Access courses) which involve chemistry, in higher education. Until now there have been no texts available for use on these courses and this book fills that gap. Access to Chemistry effectively forms a self-study course, which is split into separate modules and units covering the full spread of concepts required for those needing a basic knowledge of chemistry. The material is presented in a friendly and easy-to-use manner which allows the student to pace their acquisition of knowledge and gain increasing confidence in order to succeed in understanding essential relevant concepts. Other useful features of this book include starter diagnostic tests, worked examples and self study tests (with answers) at the end of each unit. In addition to Access or Foundation course students and their tutors, to whom this book will prove essential, it will have an appeal also as a revision text for those needing a 'refresher' after a break in the subject. In addition, it will be of interest to members of the general public who wish to better educate themselves on chemical matters, as it provides a clear and useful insight into areas such as health, home chemicals, business market trends and gardening.