bluuebunny/crossref_metadata_2025 huggingface dataset:
Generalized Hermitean Clifford–Hermite polynomials and the associated wavelet transform
Authors: Brackx Fred , De Schepper Hennie , De Schepper Nele , Sommen Frank
Published: June 2008

Clifford analysis is a higher‐dimensional function theory offering a refinement of classical harmonic analysis, which has proven to be an appropriate framework for developing higher‐dimensional continuous wavelet transforms, the construction of the wavelets being based on generalizations to a higher dimension of classical orthogonal polynomials on the real line. More recently, Hermitean Clifford analysis has emerged as a new branch of Clifford analysis, offering yet a refinement of the standard Euclidean case; it focusses on so‐called Hermitean monogenic functions, i.e. simultaneous null solutions of two Hermitean Dirac operators. In this Hermitean setting, Clifford–Hermite polynomials and their associated families of wavelet kernels have been constructed starting from a Rodrigues formula involving both Hermitean Dirac operators mentioned. Unfortunately, the property of the so‐called vanishing moments of the corresponding mother wavelets, ensuring that polynomial behaviour in the analyzed signal is filtered out, is only partially satisfied and has to be interpreted with care, the underlying mathematical reason being the fact that the Hermitean Clifford–Hermite polynomials show a too restrictive structure. In this paper, we will remediate this drawback by considering generalized Hermitean Clifford–Hermite polynomials, involving in their definition homogeneous Hermitean monogenic polynomials. The ultimate goal being the construction of new continuous wavelet transforms by means of these polynomials, we first deeply investigate their properties, amongst which are their connection with the traditional Laguerre polynomials, their structure and recurrence relations. Copyright © 2008 John Wiley & Sons, Ltd.
A non‐linear coupled finite element–boundary element model for the prediction of vibrations due to vibratory and impact pile driving
Authors: Masoumi Hamid Reza , François Stijn , Degrande Geert
Published: June 2008

This paper presents a non‐linear coupled finite element–boundary element approach for the prediction of free field vibrations due to vibratory and impact pile driving. Both the non‐linear constitutive behavior of the soil in the vicinity of the pile and the dynamic interaction between the pile and the soil are accounted for.

A subdomain approach is used, defining a generalized structure consisting of the pile and a bounded region of soil around the pile, and an unbounded exterior linear soil domain. The soil around the pile may exhibit non‐linear constitutive behavior and is modelled with a time‐domain finite element method. The dynamic stiffness matrix of the exterior unbounded soil domain is calculated using a boundary element formulation in the frequency domain based on a limited number of modes defined on the interface between the generalized structure and the unbounded soil. The soil–structure interaction forces are evaluated as a convolution of the displacement history and the soil flexibility matrices, which are obtained by an inverse Fourier transformation from the frequency to the time domain. This results in a hybrid frequency–time domain formulation of the non‐linear dynamic soil–structure interaction problem, which is solved in the time domain using Newmark's time integration method; the interaction force time history is evaluated using the θ‐scheme in order to obtain stable solutions.

The proposed hybrid formulation is validated for linear problems of vibratory and impact pile driving, showing very good agreement with the results obtained with a frequency‐domain solution. Linear predictions, however, overestimate the free field peak particle velocities as observed in reported field experiments during vibratory and impact pile driving at comparable levels of the transferred energy. This is mainly due to energy dissipation related to plastic deformations in the soil around the pile. Ground vibrations due to vibratory and impact pile driving are, therefore, also computed with a non‐linear model where the soil is modelled as an isotropic elastic, perfectly plastic solid, which yields according to the Drucker–Prager failure criterion. This results in lower predicted free field vibrations with respect to linear predictions, which are also in much better agreement with experimental results recorded during vibratory and impact pile driving. Copyright © 2008 John Wiley & Sons, Ltd.
Bending of fluid‐saturated linear poroelastic beams with compressible constituents
Authors: Wang Zhi‐Hua , Prévost Jean H. , Coussy Olivier
Published: June 2008

Analytical solutions are presented for fluid‐saturated linear poroelastic beams under pure bending. The stress‐free boundary condition at the lateral surfaces is satisfied in the St Venant's sense and the Beltrami–Michell compatibility conditions are resolved rigorously, rendering the flexure of the beams analytically tractable. Two sets of formulations are derived based on the coupled and uncoupled diffusion equations respectively. The analytical solutions are compared with three‐dimensional finite element simulations. Both sets of analytical formulations are capable of capturing exactly both the initial (undrained) and the steady‐state (fully drained) deflection of the beams. However, the analytical solutions are found to be deficient during the transient phase. The cause for the deficiency of the transient analytical solutions is discussed. The accuracy of the analytical solutions improves as Poisson's ratio and the compressibility of the constituents of the porous beam increase, where the St Venant's edge effect at the lateral surfaces is mitigated. Copyright © 2008 John Wiley & Sons, Ltd.
Proton imaging of siloxanes to map tissue oxygenation levels (PISTOL): a tool for quantitative tissue oximetry
Authors: Kodibagkar Vikram D. , Wang Xianghui , Pacheco‐Torres Jesús , Gulaka Praveen , Mason Ralph P.
Published: June 2008

Hexamethyldisiloxane (HMDSO) has been identified as a sensitive proton NMR indicator of tissue oxygenation (pO2) based on spectroscopic spin‐lattice relaxometry. A rapid MRI approach has now been designed, implemented, and tested. The technique, proton imaging of siloxanes to map tissue oxygenation levels (PISTOL), utilizes frequency‐selective excitation of the HMDSO resonance and chemical‐shift selective suppression of residual water signal to effectively eliminate water and fat signals and pulse‐burst saturation recovery 1H echo planar imaging to map T1 of HMDSO and hence pO2. PISTOL was used here to obtain maps of pO2 in rat thigh muscle and Dunning prostate R3327 MAT‐Lu tumor‐implanted rats. Measurements were repeated to assess baseline stability and response to breathing of hyperoxic gas. Each pO2 map was obtained in 3½ min, facilitating dynamic measurements of response to oxygen intervention. Altering the inhaled gas to oxygen produced a significant increase in mean pO2 from 55 Torr to 238 Torr in thigh muscle and a smaller, but significant, increase in mean pO2 from 17 Torr to 78 Torr in MAT‐Lu tumors. Thus, PISTOL enabled mapping of tissue pO2 at multiple locations and dynamic changes in pO2 in response to intervention. This new method offers a potentially valuable new tool to image pO2 in vivo for any healthy or diseased state by 1H MRI. Copyright © 2008 John Wiley & Sons, Ltd.
Influence of Fe‐MMT on the fire retarding behavior and mechanical property of (ethylene‐vinyl acetate copolymer/magnesium hydroxide) composite
Authors: Zhang Yi , Hu Yuan , Song Lei , Wu Jing , Fang Shoulin
Published: June 2008

In this work, Fe‐montmorillonite (Fe‐MMT) is synthesized and used as a synergistic agent in ethylene vinyl acetate/magnesium hydroxide (EVA/MH) flame retardant formulations. The synergistic effect of Fe‐MMT with magnesium hydroxide (MH) as the halogen‐free flame retardant for ethylene vinyl acetate (EVA) is studied by thermogravimetric analysis (TGA), limiting the oxygen index (LOI), UL‐94, and cone calorimetry test. Compared with that of Na‐MMT, it indicates that the synergistic effects of Fe‐MMT enhance the LOI value of EVA/MH polymer and improve the thermal stability and reduce the heat release rate (HRR). The structure and morphology of nanocomposites are studied by X‐ray diffraction (XRD) and transmission electron microscopy (TEM). The mechanical properties of the EVA composites have also been studied here, indicating that the use of Fe‐MMT reduces the amount of inorganic fillers. MH hence enhances the mechanical properties of the EVA composite while keeping the UL‐94 V‐0 rating. Copyright © 2008 John Wiley & Sons, Ltd.
Effects of surfactant and molecular weight of polyol on grating formation and switching of holographic PDLC
Authors: Shim S. S. , Woo J. Y. , Kim K. H. , Kim B. K.
Published: June 2008

The interposition of surfactants between polymer and liquid crystal (LC) droplets was theoretically predicted by the positive spreading coefficient (0 < λ31) and utilized to interpret the morphology, grating formation kinetics, diffraction efficiency, and switching of the holographic polymer dispersed liquid crystal (HPDLC), prepared from various types (octanoic acid, poly oxyethylene octyl phenyl ether, and perfluoro‐1‐butanesulfonyl fluoride) and amounts (0–9 wt%) of surfactant and molecular weights of polyol (PPG). Regardless of the surfactant type, diffraction efficiency increased with the addition and increasing amount of surfactant, a tendency consistent with increasing value of spreading coefficient, which is determined by the formulations of grating formation. In contrast, diffraction efficiency showed a maximum with the polypropylene glycol (PPG) molecular weight. Surfactant effectively reduced the anchoring energy and electrically drove the film which otherwise was not driven. Overall, surfactant with greater λ31 gave smaller droplet, greater diffraction efficiency, driving voltage, contrast ratio, and smaller response time. Copyright © 2008 John Wiley & Sons, Ltd.
5α‐Reduktase‐Inhibitoren – Benigne Prostatahyperplasie und vieles mehr. BPH, Alopezie und Co.
Authors: Holzgrabe Ulrike , Bennack Edith
Published: June 2008

Die 5α‐Reduktase‐Inhibitoren Finasterid und Dutasterid können bei der BPH gleichwertig eingesetzt werden. Manche Leitlinien sehen allerdings α‐Blocker den 5α‐Reduktase‐Inhibitoren überlegen. In der Studie von McConnell et al. gibt es Hinweise, dass eine Kombinationstherapie aus dem α‐Blocker Doxazosin und dem 5α‐Reduktase‐Inhibitor Fina‐sterid einer Einzeltherapie überlegen ist. Allerdings scheinen die Kosten deutlich höher als der Nutzen zu sein.
Energy loss of swift H and He projectiles in Al, Si, Ni and Cu targets
Authors: Denton Cristian D. , Abril Isabel , Moreno‐Marín Juan Carlos , Heredia‐Avalos Santiago , Garcia‐Molina Rafael
Published: June 2008

We have calculated the stopping power of Al, Si, Ni and Cu for swift H and He ion beams. Furthermore, the energy loss straggling corresponding to Ni is also evaluated. The dielectric formalism is used combined with the MELF‐GOS method, which describes the energy loss function of the target by a linear combination of Mermin type energy loss functions for the electron outer‐shell electrons and by generalized oscillator strengths for the electron inner‐shell electrons. We take into account the corrections to the stopping power associated to capture and loss of electrons by the projectile as well as the polarization of the projectile charge density. The versatility of this method is illustrated by the good agreement between their predictions and the experimental results, which is observed for a wide range of projectile energies and targets with different electronic properties. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Ab initio study of hydrogen chemical adsorption on platinum surface/carbon nanotube join system
Authors: Fedorov Alexander S. , Sorokin Pavel B. , Kuzubov Alexander A.
Published: June 2008

The process of hydrogen chemical adsorption on platinum cluster/single wall carbon nanotube (CNT) join surfaces is modelled at various temperatures and pressures. For that, the adsorption energy of hydrogen atoms on surfaces of both platinum (111) plate and CNT (5,5) or (8,8) types is calculated by density functional theory with the PBE approximation. At various temperatures the hydrogen atom hopping rate on both platinum and CNT surfaces is calculated by the transition state theory. Furthermore the hydrogen hopping rate from the platinum surface to the attached nanotube is obtained by calculation of the total energy profile. It is proved that hydrogen atoms can migrate easily at the platinum surface at all temperatures, but at the CNT surface they can migrate beginning at 400–500 K. By calculation of chemical potentials of hydrogen in gas or on CNT or platinum cluster surfaces the equilibrium density of adsorbed hydrogen was calculated at different temperatures and pressures. It is established that for all temperatures in the range 300–900 K and for all pressures less than 500 bar, the hydrogen is dissociated and chemically adsorbed on the platinum surface very effectively, but surface site occupation by hydrogen on attached CNT surface is rather small. But if CNT vacancies are present in the tube structure and the temperature is lower then 450 K, hydrogen atoms can be adsorbed effectively enough on these vacancies. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Surface and interface structural analysis of VOX/TiO2 (110) by X‐ray photoelectron diffraction
Authors: Miyasaka Shinya , Amano Kentaro , Nojima Masashi , Owari Masanori , Nihei Yoshimasa
Published: June 2008

We have studied the atomic structure of the surface and interface of VOX/TiO2 (110) by X‐ray photoelectron diffraction (XPED). The TiO2 (110) crystal surface was cleaned by cycles of Ar+ sputtering followed by annealing. The TiO2 (110) crystal surface was deoxidized by annealing. Therefore, TiO2 (110) crystal surface was annealed in oxygen atmosphere. Vanadium oxides were deposited by two processes. In process A, vanadium was first deposited on the TiO2 crystal and then oxidized in an O2 atmosphere. In process B, vanadium was deposited in an atmosphere of low‐pressure O2. We characterized the VOX ultrathin film grown on the TiO2 (110) surface by low‐energy electron diffraction (LEED), X‐ray photoelectron spectroscopy (XPS), and XPED. Finally the surface and interface structures of the VOX/TiO2 (110) were clarified by using the multiple scattering cluster model with spherical wave (MSC‐SW) method and a reliability factor R(R factor). Copyright © 2008 John Wiley & Sons, Ltd.
Thermal evolution of Co islands on Ag/Si(111)‐√3 × √3 and Ag/Ge(111)‐√3 × √3 surfaces
Authors: Tsay Sung‐Lin , Kuo Chang‐Yu , Lin Chun‐Liang , Chen Wen‐Chen , Fu Tsu‐Yi
Published: June 2008

Thermal evolution of Co islands on Ag/Ge(111)‐√3 × √3 and Ag/Si(111)‐√3 × √3 surfaces was studied by scanning tunneling microscopy (STM) and low‐energy electron diffraction (LEED). Ag‐√3 × √3 buffer layer can avoid alloy formation of Co and Si or Ge below the annealing temperature 500 °C. The growth behavior of Co on Ag/Si(111)‐√3 × √3 surfaces is very different from that on Ag/Ge(111)‐√3 × √3 surfaces, although both the √3 structures can be classified as honeycomb chain trimer (HCT) model. Submonolayer Co on Ag/Si(111)‐√3 × √3 surfaces prefer to form clusters below 500 °C. However, Co clusters nucleate and construct two‐dimensional islands (2D islands) on Ag/Ge(111)‐√3 × √3 surfaces after annealing to 300 °C. The result of different growth behavior comes from two major factors. One is antiphase boundaries (APBs) with extra electron states, which trap Co clusters on Ag/Si(111)‐√3 × √3 surfaces. The other is the strong binding force that exists between Ge and Co atoms to cause the formation of Co period islands on Ag/Ge(111)‐√3 × √3 surfaces. Copyright © 2008 John Wiley & Sons, Ltd.
Two‐stage randomization designs in drug development
Authors: Wolbers Marcel , Helterbrand Jeffrey D.
Published: June 2008

One challenge in oncology drug development is to determine whether a new agent to the care of patients should be added concurrently as a new component to standard of care (SOC) induction treatment, used sequentially as an extended maintenance treatment after SOC induction for patients responding to induction therapy, or used in both the induction and the maintenance settings. A two‐stage randomization design (TSRD) addresses these questions simultaneously. In such trials patients are initially randomized to two induction therapies, followed by another randomization to maintenance therapy contingent upon disease remission under induction therapy. We survey recently proposed methods for analyzing time‐to‐event endpoints in TSRDs and discuss several issues related to the use of TSRDs including sample size calculation and multiplicity.

An alternative drug development strategy is to perform several single randomization designs (SRDs) comparing induction and maintenance regimens, respectively. We present a simulation study, which compares TSRDs to several strategies based on SRDs in terms of total sample size and time to reach clinical decisions. Copyright © 2008 John Wiley & Sons, Ltd.
Estimating a weighted average of stratum‐specific parameters
Authors: Brumback Babette A. , Winner Larry H. , Casella George , Ghosh Malay , Hall Allyson , Zhang Jianyi , Chorba Lorna , Duncan Paul
Published: June 2008

This article investigates estimators of a weighted average of stratum‐specific univariate parameters and compares them in terms of a design‐based estimate of mean‐squared error (MSE). The research is motivated by a stratified survey sample of Florida Medicaid beneficiaries, in which the parameters are population stratum means and the weights are known and determined by the population sampling frame. Assuming heterogeneous parameters, it is common to estimate the weighted average with the weighted sum of sample stratum means; under homogeneity, one ignores the known weights in favor of precision weighting. Adaptive estimators arise from random effects models for the parameters. We propose adaptive estimators motivated from these random effects models, but we compare their design‐based performance. We further propose selecting the tuning parameter to minimize a design‐based estimate of mean‐squared error. This differs from the model‐based approach of selecting the tuning parameter to accurately represent the heterogeneity of stratum means. Our design‐based approach effectively downweights strata with small weights in the assessment of homogeneity, which can lead to a smaller MSE. We compare the standard random effects model with identically distributed parameters to a novel alternative, which models the variances of the parameters as inversely proportional to the known weights. We also present theoretical and computational details for estimators based on a general class of random effects models. The methods are applied to estimate average satisfaction with health plan and care among Florida beneficiaries just prior to Medicaid reform. Copyright © 2008 John Wiley & Sons, Ltd.
Comparison of two‐phase analyses for case–control genetic association studies
Authors: Zheng Gang , Meyer Mark , Li Wentian , Yang Yaning
Published: June 2008

To test for genetic association between a marker and a complex disease using a case–control design, Cochran–Armitage trend tests (CATTs) and Pearson's chi‐square test are often employed. Both tests are genotype‐based. Song and Elston (Statist. Med. 2006; 25:105–126) introduced the Hardy–Weinberg disequilibrium trend test and combined it with CATT to test for association. Compared to using a single statistic to test for case–control genetic association (referred to as single‐phase analysis), two‐phase analysis is a new strategy in that it employs two test statistics in one analysis framework, each statistic using all available case–control data. Two such two‐phase analysis procedures were studied, in which Hardy–Weinberg equilibrium (HWE) in the population is a key assumption, although the procedures are robust to moderate departure from HWE. Our goal in this article is to study a new two‐phase procedure and compare all three two‐phase analyses and common single‐phase procedures by extensive simulation studies. For illustration, the results are applied to real data from two case–control studies. On the basis of the results, we conclude that with an appropriate choice of significance level for the analysis in phase 1, some two‐phase analyses could be more powerful than commonly used test statistics. Copyright © 2008 John Wiley & Sons, Ltd.
Genotype‐adjusted familial correlation analysis using three generalized estimating equations
Authors: Lee Hye‐Seung , Paik Myunghee Cho , Lee Joseph H.
Published: June 2008

We analyze familial correlation of a memory score from Caribbean Hispanic families that have multiple family members affected with Alzheimer's disease, adjusting for having at least one APOE‐ε4 allele, as well as other confounders. To enhance the efficiency of correlation model, this paper proposes an alternative approach for three generalized estimating equations proposed by Yan and Fine (Statist. Med. 2004; 23:859–874). The efficiency of correlation model is evaluated through the asymptotic relative efficiency computation and simulations. Copyright © 2008 John Wiley & Sons, Ltd.
The assessment of non‐inferiority in a gold standard design with censored, exponentially distributed endpoints
Authors: Mielke Matthias , Munk A. , Schacht A.
Published: June 2008

The objective of this paper is to develop statistical methodology for non‐inferiority hypotheses to censored, exponentially distributed time to event endpoints. Motivated by a recent clinical trial in depression, we consider a gold standard design where a test group is compared with an active reference and with a placebo group. The test problem is formulated in terms of a retention of effect hypothesis. Thus, the proposed Wald‐type test procedure assures that the effect of the test group is better than a pre‐specified proportion Δ of the treatment effect of the reference group compared with the placebo group. A sample size allocation rule to achieve optimal power is presented, which only depends on the pre‐specified Δ and the probabilities for the occurrence of censoring. In addition, a pretest is presented for either the reference or the test group to ensure assay sensitivity in the complete test procedure. The actual type I error and the sample size formula of the proposed tests are explored asymptotically by means of a simulation study showing good small sample characteristics. To illustrate the procedure a randomized, double blind clinical trial in depression is evaluated. An R‐package for implementation of the proposed tests and for sample size determination accompanies this paper on the author's web page. Copyright © 2008 John Wiley & Sons, Ltd.
Tumor‐Inhibitory Effect and Immunomodulatory Activity of Fullerol C60(OH)x
Authors: Zhu Jiadan , Ji Zhiqiang , Wang Jing , Sun Ronghua , Zhang Xiang , Gao Yang , Sun Hongfang , Liu Yuanfang , Wang Zheng , Li Aidong , Ma Jie , Wang Tiancheng , Jia Guang , Gu Yiqun
Published: June 2008

The tumor‐inhibitory effect of C60(OH)x was tested on the murine H22 hepatocarcinoma model. Doses of 0.2 and 1.0 mg kg−1 body weight both showed significant antitumor activity with tumor inhibition rates of 31.9 and 38.4%, respectively, when mice were treated for 17 consecutive days. The damnification of liver was prominently reduced. Furthermore, histological examination indicated that an envelope of fibroblasts and lymphocytes was formed surrounding tumor tissues in the C60(OH)x‐treated group, which inhibited the infiltration of tumor to the neighboring normal skeleton muscle tissues. To understand the antitumor mechanism, the immunomodulatory activity of C60(OH)x was investigated. The results indicate that C60(OH)x enhances the phagocytosis of peritoneal macrophages and elevates the activity of arginase and acid phosphatase in vivo. The tumor necrosis factor alpha production of C60(OH)x‐treated macrophages also increases in vitro. These results suggest that C60(OH)x can enhance the innate immunity of tumor‐bearing mice, and therefore inhibits growth of the tumor.
Effects of intravenous placebo with glucose expectation on human basal ganglia dopaminergic function
Authors: Haltia Lauri T. , Rinne Juha O. , Helin Semi , Parkkola Riitta , Någren Kjell , Kaasinen Valtteri
Published: June 2008

Previous positron emission tomography (PET) studies have provided evidence that the psychological expectation of certain drugs combined to the placebo administration may lead to subjectively experienced placebo effects, which, in turn, are associated with dopamine (DA) release in the brain. Our recent study indicated that blind intravenous (i.v.) glucose induces DA release in male subjects. In the present study, we examined if the mere expectation of glucose (i.v. placebo) could similarly release DA in the basal ganglia. [11C]raclopride PET was performed for 12 lean [mean body mass index (BMI) = 22 kg/m2] and 12 overweight (mean BMI = 33 kg/m2) healthy subjects (12 men and 12 women). Each subject was imaged twice in a counter‐balanced setting, after blind i.v. placebo and after open i.v. placebo. DA D2 receptor binding potentials (BP) were estimated. The results of the present study show that i.v. placebo administration with glucose expectation induces bilateral BP reduction in the ventral striatum in the male group, suggesting DA release. The stimulus did not induce dopaminergic placebo effect in the overweight or the lean group (males and females combined). Voxel‐based analysis also suggested regionally selective BP increases in the dorsal striatum in the male subjects, whereas women showed no significant changes in BPs. The results support previously reported gender differences in the DA function after a pharmacological challenge (e.g., amphetamine and glucose). Also, they suggest that the DA release in the ventral striatum mediates placebo responses in the context of glucose expectation. Synapse 62:682–688, 2008. © 2008 Wiley‐Liss, Inc.
A classification of biologic lipids based upon their interaction in aqueous systems
Authors: Small Donald M.
Published: June 2008

A classification of lipids is presented, based upon their physical properties in bulk aqueous systems and at the air‐water or oil‐water interface. This is supported by binary‐phase diagrams of the various classes of lipids in water.

The interactions of the lipids of each class with a lipid of another class is illustrated by a series of different ternary‐phase diagrams of two lipids in water. The various types of association and the molecular relation of one lipid to another are indicated. The interaction of three classes of lipids with water is illustrated in two examples by quaternary‐phase diagrams of the three lipids in water.

As an example of the application of these invitro studies, the composition of bile is correlated with a quaternary‐phase diagram cholesterollecithin‐bile salt‐water. The correlation shows that human bile behaves as a biologic four‐component system the physical state of which is entirely predictable from the quaternary‐phase diagram. Although bile is a special case, it is probable that the physical arrangement of the lipids in membranes, cellular organelles, lipoproteins, and adipose tissue can be suggested by studies of the interaction of lipid classes with themselves in water.
Liquid crystals and living systems
Authors: Fergason James L. , Brown Glenn H.
Published: June 2008

Most lipids do not pass, on heating, directly from a crystalline structure to an isotropic structure. They are often characterized by a number of intermediate phases, ranging from the plastic crystal, where the center of gravity of the molecule may rotate about one or more axes while the three‐dimensional order of the crystal remains, to nematic liquid crystals, which have birefrigent properties of crystals and yet are characterized by completely random ordering of the molecular centers. The smectic and cholesteric liquid crystalline structures are most commonly encountered in lipids. The structural characteristics of these systems are discussed.

Of particular interest in living systems are liquid crystals, which are formed by cholesteric esters and many protein materials, and the two‐dimensional crystals (smectic structure), which are formed by fatty acid derivatives. The mechanisms of energy transfer and the mechanical alignment in these liquid crystalline systems are unique and require different considerations from those found adaptable to liquids or solids. The properties of liquid crystals which might best be associated with living systems will be discussed, including surface properties and diffusivity.
Interaction of soluble proteins with protein monolayers
Authors: Arnold John D. , Pak Charles Y.
Published: June 2008

The direction and strength of intermolecular forces at an air‐water or oil‐water interface is such that many proteins in the interface are distorted in structure. This involves substantial changes in solubility and cross‐sectional area. Many of the changes can be accounted for by rupture of the secondary and tertiary bonds and are often irreversible. The hydrophilic groups of the protein will be concentrated in the aqueous phase and participate in interactions with normal proteins in the supporting solution. It can be shown that certain types of interaction between these hydrophilic groups of a protein monofilm and a soluble protein are dependent on the interfacial pressure, that they are sensitive to a small (one or more amino acid) change in structure of the protein. Evidence is given that they are related to certain antigen‐antibody type reactions between molecules in three‐dimensional systems. Since many proteins in vivo are exposed to oilwater and air‐water interfaces, this laboratory model may have physiologic as well as chemical significance.
Phase equilibria and countercurrent distribution
Authors: Barford R. A. , Bertsch R. J. , Rothbart H. L.
Published: June 2008

Ternary diagrams for methyl oleate/hexane/acetonitrile and methyl palmitate/hexane/acetonitrile systems were constructed from equilibria data obtained at 20.0 and 30.4C. The diagrams varied significantly with temperature; both systems showed expanded regions of immiscibility at the lower temperature. Both the partition coefficient of the methyl ester and the mutual solubility of hexane and acetonitrile, at each temperature, varied with ester concentration in the system. At high ester concentration, an inversion of the phases was observed. The countercurrent distribution of these compounds, as influenced by these effects, is discussed.
A chromatographic method for the analysis of propylene glycol fatty acid esters in shortenings containing mono‐ and diglycerides
Authors: Sahasrabudhe Madhu R. , Legari J. J.
Published: June 2008

A procedure is described for the separation, identification, and quantitative estimation of propylene glycol mono‐ and diesters of lauric, myristic, palmitic, stearic, and oleic acids in shortenings and lard containing mono‐ and diglycerides. Lipid classes are separated on a silicic acid column, and individual esters are estimated by gas chromatography. Analyses of several control mixtures and commercial samples are reported. Recoveries for individual components range from 92 to 105%, and total recoveries range from 96 to 100%.
Dimensional analysis of the detergency process for systems containing multicomponent soils
Authors: Mankowich A. M.
Published: June 2008

Dimensional analysis of the detergency process has been extended from soil‐surfactant systems which contain a single polar soil to those with binary and ternary component soils which contain a nonpolar ingredient. This was made possible by replacement of the soil dipole moment variable by the proportional square root of orientation polarization (Po) and by establishment of the validity of the empirical volume fraction additivity of the ingredient P0 values of binary polar—polar mixtures by using the classical dilute solution—solute (P2) extrapolation procedure with a chemical oscillometer.
An automated method for determining free alkalinity or acidity in soap
Authors: Hoover W. E. , Ginn M. E. , Jungermann Eric
Published: June 2008

An AutoAnalyzer method has been developed to determine free alkalinity or acidity in soap by use of a mixed cresol red‐phenolphthalein indicator solution and by measurement of the color developed at 550 mµ. An internal standard or reference solution is used consisting of a soap solution which has been adjusted to represent neutrality. The method was applied for 0 to 0.10% free alkalinity, calculated as sodium hydroxide, and for 0 to 0.50% free acidity calculated as oleic acid. Attainable precision of the method (95% confidence limits) in the ranges explored was found to be ±0.0025% for free alkali and ±0.05% for free acidity.
Studies in interesterification. II. Acidolysis of some vegetable oils with lauric acid
Authors: Chakrabarty M. M. , Talapatra K.
Published: June 2008

Acidolysis reactions of cottonseed oil, peanut oil, mahua oil (Madhuca latifolia), and palm oil with lauric acid were investigated with special reference to the influence of catalysts and the relative proportions of oil and lauric acid on the extent and type of fatty acids displaced from an oil. Catalysts such as sulfuric acid, zinc oxide, calcium oxide, magnesium oxide, aluminum oxide, and mercuric sulfate were used. The reaction generally was carried out by heating oil and lauric acid at 150C±2 for 3 hr.

The reaction products were separated and then analyzed by UV spectrophotometry and GLC. Sulfuric acid was found to be the best catalyst with 1 part of oil and 1.2 parts of the displacing acid (lauric acid) for displacement of high‐molecular‐weight fatty acids from an oil by low‐molecular‐weight fatty acids. The nature of the displacement of fatty acids varied from oil to oil, depending on their compositions. It was further indicated that linoleic acid was displaced preferentially over oleic acid in an amount dependent on its initial content in an oil with a corresponding increase in saturated acids content. A broad similarity in displacement patterns, in general, was noted; the fatty acids above C18 were not displaced as in the case of peanut oil. The results demonstrate the feasibility of introducing lauric acid in the vegetable oils for the production of interesting oils with vastly different physical and chemical properties.
A survey of the conjugated fatty acids of seed oils
Authors: Hopkins C. Y. , Chisholm Mary J.
Published: June 2008

Fatty acids with conjugated unsaturation occur in many seed oils. Thirty of these acids are reviewed with emphasis on their detection, isolation, and structure determination. Their distribution among plant families is shown, and a botanical source of each acid is given. Some reactions, derivatives, and methods of determining configuration are described. Current theories of their biosynthesis in the seed, involving oxygenated precursors, are summarized.
Solid‐liquid phase relations of some normal long‐chain fatty acids in N,N‐dimethylacetamide and N,N‐dimethylformamide
Authors: Harris James A. , Bailey August V. , Skau Evald L.
Published: June 2008

Solubility data are reported for capric, lauric, myristic, palmitic, stearic, and arachidic acids in N,N‐dimethylacetamide (DMA) and N,N‐dimethylformamide (DMF). Complete binary freezing‐point diagrams were constructed for the capric, myristic, and stearic acid systems. A solid, incongruently melting 1:1 molecular compound formed in all except the stearic acid‐DMF system. Calculated solubility data for lauric, palmitic, and arachidic acids in both solvents were in good agreement with experimental determinations on selected compositions.
Removal of cyclopropenoid fatty acids from cottonseed meals by solvent extraction
Authors: Reilich H. G. , O’Neill H. J. , Levi R. S. , Yamauchi T. , Pons W. A.
Published: June 2008

Direct solvent‐extraction procedures were explored for their effectiveness in removing the residual levels of cyclopropenoid fatty acids from commercial cottonseed meals. Of the seven solvent systems screened, a simple stepwise extraction with an acetone/hexane/water azeotrope was found suitable for the removal of up to 88% of the original CPA content of the meal.
Reactions of the stearoylated enolic form of acetone, involving hexadecylketene as the reactive intermediate
Authors: Rothman Edward S.
Published: June 2008

Enol esters, such as isopropenyl stearate, are useful intermediates capable of forming interesting derivatives of saturated aliphatic fatty acids. Under given conditions, whereas methyl stearate remains unreactive up to 400C, by contrast the isopropenyl stearate ester efficiently liberates hexadecylketene at 170C with the simultaneous expulsion of “isopropenyl alcohol,” i.e., acetone. In the presence of even difficulty acylatable OH or NH compounds the liberated aldoketene combines, usually quantitatively, with these hydrogen‐bearing compounds to form esters or imides. In this manner such resistant materials as barbituric acids, hydantoins, N‐butylstearamide, acetanilide, t‐butyl alcohol, and succinimide may be converted to stearoylated derivatives.

In the absence of reactable substrate and with strong dependence on the nature of the reaction medium, liberated hexadecylketene tetramerizes to derivatives ofgamma pyrone, or forms stearone, or stearoylates the enolic rearrangement product, heneicosane‐2,4‐dione. The latter compound, in forming, has increased the 18 carbon chain‐length to 21 continuous carbon atoms. Di‐isopropenyl esters with polyfunctional acetylatable materials, such as bis‐N‐alkylazelaamide or sucrose, give rise to unusual linear polyimides, three‐dimensional network polymers, or oligomers.
A guide for forecasting soybean futures prices
Authors: Malone Patrick J.
Published: June 2008

The role of the spectator is discussed, and emphasis put on his study of fundamental market analysis, such as supply and demand projections; technical market analysis, such as chart trends and composition of open interest; and the basic trading rules for every trader. Both soybean oil and meal are considered. Statistics from the Commodity Exchange Authority are shown to be auxiliary tools.
The Impact of Self‐Belief on Laparoscopic Performance of Novices and Experienced Surgeons
Authors: Maschuw K. , Osei‐Agyemang T. , Weyers P. , Danila R. , Bin Dayne K. , Rothmund M. , Hassan I.
Published: June 2008

Background

In many professions, nontechnical aspects such as motivation or coping with stress are known to influence performance, success, and outcome. These qualities are assessed and trained in novices for quality and safety reasons. This study explored the impact of self‐belief of surgeons on laparoscopic performance using a virtual reality simulator (LapSim®).

Methods

Eighteen inexperienced surgical residents (with less than ten laparoscopic procedures performed) and 22 advanced residents (with more than 50 laparoscopic procedures performed) filled out a ten‐item questionnaire used for the assessment of the individual sense of general self‐efficacy (GSE). Afterward the participants were asked to perform three defined tasks on the LapSim, each at two different levels of difficulty. The tasks consisted of coordination, dissection, and application of clips. To assess laparoscopic performance, the total time to complete the tasks, economy of motion, and damage parameters were analyzed and correlated with the GSE score by means of Bravis‐Pearson correlation analysis.

Results

In novices, high GSE scores correlated with more errors and poor economy of motion, while in advanced residents, laparoscopic performance was independent of the level of assessed self‐efficacy.

Conclusion

In a small sample, high self‐belief does not predict success. In novices it negatively correlates with laparoscopic skills, while in advanced residents it is independent of laparoscopic performance. Thus, training aspects seem to be of greater importance for laparoscopic skills. Nevertheless, nontechnical aspects like self‐belief, motivation, stress‐coping strategies, judgment, decision‐making, and leadership should be included in the surgical curriculum.
Clinical, Radiological, and Manometric Profile in 145 Patients with Untreated Achalasia
Authors: Fisichella Piero M. , Raz Dan , Palazzo Francesco , Niponmick Ian , Patti Marco G.
Published: June 2008

Background

Esophageal achalasia is characterized by the absence of esophageal peristalsis and by a dysfunctional lower esophageal sphincter (LES). Descriptions of clinical, radiological, and manometric findings in patients with achalasia usually have been based on small numbers of patients. This study was designed to determine in patients with untreated achalasia: (1) clinical presentation; (2) how often a diagnosis of gastroesophageal reflux disease (GERD) was erroneously made based on the presence of heartburn; (3) manometric profile; (4) relationship between chest pain and the manometric finding of vigorous achalasia.

Methods

Between 1990 and 2004, a diagnosis of esophageal achalasia was established in 145 patients. None of them had been previously treated (no previous endoscopic or surgical treatment). We evaluated the demographic and clinical characteristics, as well as the results of the endoscopy, barium swallow, esophageal manometry, and ambulatory pH monitoring. We also compared the clinical and the manometric profile of patients with classic and patients with vigorous achalasia.

Results

Most patients with untreated achalasia had dysphagia (94%). Regurgitation was present in 76% and heartburn in 52%. Chest pain (41%) and weight loss (35%) were less common. Acid‐suppressing medications had been prescribed to 65 patients (45%) who complained of heartburn on the assumption that GERD was present. The LES was hypertensive in 43% of patients only. There was no significant difference in the prevalence, severity, and duration of chest pain in patients with classic and with vigorous achalasia.

Conclusions

These results show that in patients with untreated achalasia: (1) dysphagia was the most frequent complaint, but regurgitation and heartburn were frequently present; (2) a diagnosis of GERD based on the presence of heartburn was highly unreliable; (3) the LES was hypertensive in less than half of patients; and (4) the prevalence, severity, and duration of chest pain did not correlate with the manometric finding of vigorous achalasia.
Acute Care Surgeon South American Model
Authors: Poggetti Renato Sergio
Published: June 2008

Background

In the World Health Organization book by Murray and Lopez (The Global Burden of Disease), the authors make the point that there are major regional differences across the world for death from injury. In the European market economies, injuries accounted for 6% of all deaths, of which the majority were the result of road traffic accidents. In stark contrast, in Latin America and the Caribbean, injuries account for 12–13% of all deaths, and most of these are the result of violence. An estimated 30% of all male deaths are from external causes, and road traffic accidents are the number two cause of death. Within South American countries, trauma is the second most common cause of death in Columbia, Venezuela, Ecuador, and Brazil. In other South American countries, it is the third or fourth most common cause of death. If one examines the Disability Adjusted Life Years, South America is the third highest in the world. Death from injury primarily affects people in the middle‐ and low‐income group. Traffic accidents and suicide are the main causes of trauma in the high‐income population. South America is made up of developing and poor countries that have trauma as a very important cause of death and disability.

Methods

The author has reviewed information on injury from the World Health Organization, Pan American Health Organization, and Brazilian Health Ministry. In addition, a search of injury was performed through MEDLINE.

Results and Conclusions

The results of this review show that trauma is a major public health problem in South America. At the present time, there is a lack of statewide system development. In addition, there are difficulties in training surgeons to cope with these problems.
Changes in plant species diversity along a chronosequence of vegetation restoration in the humid evergreen broad‐leaved forest in the Rainy Zone of West China
Authors: Zhu Wanze , Cheng Song , Cai Xiaohu , He Fei , Wang Jinxi
Published: June 2008

Plant species diversity has been recognized as one of the vital attributes for assessing vegetation restoration. Changes in the diversity may be related to different stages of succession. In this study, 54 sites of humid, evergreen, broad‐leaved forest were selected in the Rainy Zone of West China. A chronosequence of the sites was used to study the successive patterns of the diversity in the forest that had undergone natural regeneration for 5 to 350 years and to test the hypothesis that the diversity is maximized in mid‐succession. Data were collected simultaneously at different stages of succession, and four α‐diversity indices (species richness, Margalef index, Shannon‐Wiener index, Pielou Evenness index) and two β‐diversity indices (Whittaker index, Sørensen's index) were calculated for each stratum in each plot. A total of 394 vascular plant species were recorded. From the β‐diversity indices, the forest succession may be divided into the early‐successional stage (before 50 years), mid‐successional stage (from 50 to 300 years), and late‐successional stage (after 300 years). In this community, the species diversity and richness were found to be the greatest at the mid‐successional stage, followed by the late‐ and early‐successional stages. The results of regression analysis indicated that the richness and Margalef index peaked around the 175th and 165th year, respectively. Shannon‐Wiener index values also appeared to follow an approximately humped pattern of succession and were maximal around the 100th year. However, the species evenness did not show any significant relationship with successional age. Our results demonstrate (1) forest restoration is a long‐term process and the formation of climax forest requires at least 300 years and (2) the forest has a strong capacity for restoration. Our results also suggestLindera limprichitiiandMachilus pingiias ideal tree species for afforestation because of their wide niche.
The Influences of H2Plasma Pretreatment on the Growth of Vertically Aligned Carbon Nanotubes by Microwave Plasma Chemical Vapor Deposition
Authors: Jian Sheng-Rui , Chen Yuan-Tsung , Wang Chih-Feng , Wen Hua-Chiang , Chiu Wei-Ming , Yang Chu-Shou
Published: June 2008

The effects of H2flow rate during plasma pretreatment on synthesizing the multiwalled carbon nanotubes (MWCNTs) by using the microwave plasma chemical vapor deposition are investigated in this study. A H2and CH4gas mixture with a 9:1 ratio was used as a precursor for the synthesis of MWCNT on Ni-coated TaN/Si(100) substrates. The structure and composition of Ni catalyst nanoparticles were investigated using scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The present findings showed that denser Ni catalyst nanoparticles and more vertically aligned MWCNTs could be effectively achieved at higher flow rates. From Raman results, we found that the intensity ratio of G and D bands (I
D/I
G) decreases with an increasing flow rate. In addition, TEM results suggest that H2plasma pretreatment can effectively reduce the amorphous carbon and carbonaceous particles. As a result, the pretreatment plays a crucial role in modifying the obtained MWCNTs structures.