bluuebunny/crossref_metadata_2025 huggingface dataset:
Effect of ATH content on electrical and aging properties of EVA and silicone rubber blends for high voltage insulator compound
Authors: Pradeep M. A. , Vasudev N. , Reddy P. V. , Khastgir D.
Published: March 2007

The effect of trihydrated alumina (Al2O3, 3H2O) (ATH) filler in ethylene‐vinyl acetate copolymer (EVA) and silicone rubber blends was investigated by performing a series of laboratory experiments to simulate different natural aging conditions. Samples with varying ATH content in a 50‐50 blend of EVA and polydimethylsiloxane (PDMS) (silicone rubber, MQ) were tested to investigate the tracking resistance, resistance to UV radiation, corona, heat, and water immersion. Changes in surface resistivity, volume resistivity, and hydrophobic characteristics were evaluated for different compounds having ATH content. These exercises were mainly carried out to optimize the filler level. In immersed condition the water absorption increases with ATH content. The recovery of hydrophobicity, after aging by heat, is appreciable at higher ATH levels, than at lower ATH levels. The tracking and erosion resistance decrease as ATH content increases. When compounds containing different ATH content were subjected to corona treatment, the samples with higher ATH levels exhibited better results. All samples changed their color to a darker shade and there was an increase in the hydrophobicity, when subjected to UV radiation. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 3505–3516, 2007
Phenolics from Extracts of Brahea armata with Inhibitory Effect Against 5α‐Reductase Type‐II.
Authors: Hussein S. A. , Hashim A. N. , Barakat H. H. , Jose J. , Lindequist U. , Nawwar M. A.
Published: March 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
The Trichothecenes and Their Biosynthesis
Authors: Grove J. F.
Published: March 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Design and Function of Low Molecular‐Mass Organic Gelators (LMOGs) Bearing Steroid and Sugar Groups
Authors: Fujita Norifumi , Shinkai Seiji
Published: March 2007

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF.
Neonatal alcohol exposure impairs acquisition of eyeblink conditioned responses during discrimination learning and reversal in weanling rats
Authors: Brown Kevin L. , Calizo Lyngine H. , Goodlett Charles R. , Stanton Mark E.
Published: March 2007

Discrimination and reversal of the classically conditioned eyeblink response depends on cerebellar–brainstem interactions with the hippocampus. Neonatal “binge” exposure to alcohol at doses of 5 g/kg/day or more has been shown to impair single‐cue eyeblink conditioning in both weanling and adult rats. The present study exposed neonatal rats to acute alcohol intubations across different developmental periods (postnatal day [PND] 4‐9 or PND7‐9) and tested them from PND26‐31 on discriminative classical eyeblink conditioning and reversal. A high dose of alcohol (5 g/kg/day) dramatically impaired conditioning relative to controls when exposure occurred over PND4‐9, but produced mild or no impairments when delivered over PND7‐9. These findings support previous claims that developmental exposure period plays a critical role in determining the deleterious effects of alcohol on the developing brain. A lower dose of alcohol (4 g/kg/day) delivered from PND4‐9—lower than has previously been shown to affect single‐cue eyeblink conditioning—also produced deficits on the discrimination task, suggesting that discrimination learning and acquisition of responding to CS+ during reversal may be especially sensitive behavioral indicators of alcohol‐induced brain damage in this rat model. © 2007 Wiley Periodicals, Inc. Dev Psychobiol 49: 243–257, 2007.
Safety of structural systems with reserve elements for earthquake protection
Authors: Eisenberg I. M.
Published: March 2007

Some results of approximate analyses of the safety of earthquake protection systems with reserve elements are presented. Systems with one and several reserve elements are considered. The overshoot random vibration approximation is used for analysis. A numerical example is given. It is shown that the failure probability of structures with reserve elements is considerably lower and the safety is much higher when compared with similar characteristics of structures without reserve elements.
The peak harmonic response of locally non‐linear systems
Authors: Miller Richard K. , Iwan Wilfred D.
Published: March 2007

This paper presents an approximate analytical technique for determining the steady‐state response of a class of systems with spatially localized non‐linearity. A method of finding the amplitude peaks in various modes is presented. Numerical examples illustrate the nature and accuracy of the results of the approximate analysis.
Dynamic response of a submerged hemispherical shell to earthquake motions
Authors: Akkał Nuri
Published: March 2007

The dynamic response to ground motion of hemispherical shells in a fluid, medium is studied numerically. In the analysis, linear thin shell theory is used and the fluid is assumed to be compressible and inviscid. The effect of the duration of the ground motion on the dynamic response is studied using two forcing functions, one with a very short duration and the other in the form of a Heaviside function. As special cases, dynamic responses of the shell in vacuo and of a rigid hemisphere in the fluid medium are investigated. The results are valid also for a ring‐stiffened complete spherical shell accelerating in an acoustic medium.
Approximate frequency analysis of shear wall frame structures
Authors: Cheung Y. K. , Kasemset C.
Published: March 2007

The finite strip method is used to determine the natural frequencies of shear wall frame buildings. The structure can be modelled in two different ways. In the first approach both the shear walls and the frames are idealized simply as an assemblage of finite strips of varying thicknesses with given or computed properties, while in the second approach the shear walls are still idealized as a series of finite strips, but the frames are regarded as a number of long columns which are interconnected with each other or with finite strips through the horizontal beams. Numerical results obtained from both models indicate good agreement with finite element solutions. The proposed models can be applied to a wide range of shear wall frame assemblies and are therefore more versatile than most existing models.
An improved fluid superelement for the coupled solid‐fluid‐surface wave dynamic interaction problem
Authors: Dubois J. J. , De Rouvray A. L.
Published: March 2007

The dynamic solid‐fluid‐surface wave interaction problem can be solved with known Finite Element solutions. However, these solutions are complicated by the unsymmetric nature of the matrix equation to be solved.

This paper shows how the numerical problem can be simplified by symmetrization, without loss of physical generality, using specialized Lagrange co‐ordinates for the fluid free surface wave, and by introducing a Lagrange multiplier representing a generalized fluid pressure.

With these improvements, solid‐fluid‐surface wave analysis capabilities can easily be added to most Finite Element structural analysis programs. Numerical examples of the performance of the improved formulation are given for earthquake analysis.
Triton X‐100 Pretreatment of LR‐white Thin Sections Improves Immunofluorescence Specificity and Intensity
Authors: Ghrebi Salem S. , Owen Gethin Rh. , Brunette Donald M.
Published: March 2007

The staining of intracellular antigenic sites in postembedded samples is a challenging problem. Deterioration of antigenicity and limited antibody accessibility to the antigen are commonly encountered on account of processing steps. In this study preservation of the antigen was achieved by fixing the tissues with mild fixatives, performing partial dehydration, and embedding in a low crosslinked hydrophilic acrylic resin, LR‐White. Permeabilization of cell membranes with Triton X‐100 is well documented but can affect some antigen conformations. We tested the effect of Triton X‐100 on the ED1 antigen present in the lysosomal membrane of the macrophage in cell culture. The ED1 antigen in the lysosome was resistant to extraction by Triton X‐100. Interestingly pretreating the LR‐White sections of macrophage pellets with Triton X‐100 improved the staining intensity of ED1. The most intense and clear specific fluorescent staining was observed when sections were pretreated with 0.2% Triton X‐100 for 2 min. Longer exposure of sections to 0.2% Triton or 2 min exposure to 2% Triton lead to reduced ED1 labeling. SEM observations indicated that the detergent extracted a component from the cells and not the resin and was determined to be lipid. This novel technique could be applied in many research areas where postembedding fluorescent immunolabeling with higher labeling intensity is desired. Microsc. Res. Tech., 2007. © 2007 Wiley‐Liss, Inc.
Downscaling of current and future rainfall climatologies for southern Morocco. Part I: Downscaling method and current climatology
Authors: Huebener H. , Kerschgens M.
Published: March 2007

The use of a statistical‐dynamical downscaling approach to obtain a high‐resolution rainfall climatology for a subtropical region in southern Morocco is analysed. The statistical part of the downscaling uses Circulation Weather Types (CWTs) as a measure for near‐surface wind fields calculated from sea‐level pressure (SLP) data. The daily CWTs are correlated with daily rainfall data at three different climate stations in the region for the period 1978–1997 and systematic differences are discussed. Results are viewed for one extreme dry year (1984) and one extreme wet year (1989) to show the limits of purely statistical downscaling.

Dynamical downscaling is realized for representative days to enable statistical‐dynamical downscaling. Comparison of statistically‐dynamically downscaled rainfall with measured rainfall for the year 2002 and climatological results show that the method is capable of capturing the relevant mechanisms triggering rainfall in the area. For extreme dry (wet) years, rainfall is overestimated (underestimated) by the method and errors might occur even for normal years. However, application to a climatology calculated for the period 1958–1997 via analysing daily SLP fields from NCEP Reanalyses gives satisfactory results. For sufficiently long periods, the method is well capable of producing a reliable high‐resolution rainfall climatology. We will therefore apply the method to climate change simulations in part II of this paper. Copyright © 2007 Royal Meteorological Society
Radical Telomerisation of Vinyl Phosphonic Acid with a Series of Chain Transfer Agents
Authors: David Ghislain , Boutevin Bernard , Seabrook Shane , Destarac Mathias , Woodward Gary , Otter Graham
Published: March 2007

The use of CTAs for the radical polymerisation of VPA has been successfully applied for the first time. Several CTAs were investigated, including thiol, disulfide and halogenated compounds. The use of mercaptoacetic acid led to the synthesis of the mercaptan VPA monoadduct, which was attributed to a high transfer constant (CT = ktr/kp) of approximately 7. Transfer reactions with VPA appeared to be unsuccessful when using benzyldisulfide, 1,1,1‐trichloroethane and trichloroacetic acid. Application of bromotrichloromethane as a transfer agent led to the oligomerisation of VPA, with final conversion being approximately 80%. The transfer events were characterised by 13C NMR, MALDI‐TOF and elemental analysis. Molecular weights of the successful VPA polymerisations showed values ranging from 600 to 5 000 g · mol−1, which were in close agreement with the theoretically calculated values.

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Fabrication and Properties of Cellulose Hydrated Membrane with Unique Structure
Authors: Liang Songmiao , Zhang Lina , Li Yanfang , Xu Jian
Published: March 2007

By employing a pre‐gelation processing of cellulose solution, this work has presented a new method to prepare cellulose hydrated membranes in NaOH/thiourea aqueous solvent system. The morphology and structure of the hydrated membranes obtained at different pre‐gelation temperatures were studied by scanning electron microscopy (SEM), wide‐angle X‐ray diffractometry (WAXD), and attenuated total reflection Fourier transform infrared spectroscopy (ATR‐FTIR). The mechanical properties of the membranes were studied by tensile testing. Using a double‐cell method, permeation of three model drugs (ceftazidine, cefazolin sodium, thiourea) through the hydrate membranes was determined in phosphate buffer solution at body‐like temperature (37 °C). The results indicate that the membranes were packed densely by many hydrated nanospheres and exhibited good mechanical properties. At a relatively low pre‐gelation temperature, the strain and the stress at break of the membranes are even up to 192% and 1.97 MPa, which are much larger than that of the hydrated membranes prepared by the general solution casting method. For the first time, the formation process of the hydrated membrane from gel state in water was investigated by ATR‐FTIR spectrum, indicating a non‐solvent‐induced phase‐separation mechanism.

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Low‐Melting Nematic Quasi‐Rigid Rod‐Like Polyesters
Authors: Osman Maged A.
Published: March 2007

Thermotropic quasi‐rigid rod‐like polyesters with broad nematic phases in temperature ranges that allow melt processing in the mesophase have been synthesized. The desired mesomorphic temperature range can be realized by adjusting the chain flexibility and packing density as well as the axial ratio of the mesogenic segments. The chain flexibility was slightly increased without giving the molecule much conformational freedom by introducing ethylene or dioxyethylene linkages between the phenyl groups of the aromatic polyester (preferably in the acid part of the molecule). The sensitive balance between the axial ratio of the mesogenic segments and the chain flexibility was preserved to retain the mesogeneity of the molecule. Replacing some of the planar aromatic phenyl groups by staggered trans‐cyclohexyl moieties effectively depresses Tm without affecting Ti. The effect of symmetrical and asymmetrical lateral substitution with alkyl groups of different van der Waals volume on Tm and Ti was studied. Asymmetric lateral substitution is quite effective in depressing Tm with little effect on Ti. Combinations of these structural modifications are useful tools to adjust the mesomorphic properties of liquid crystalline polyesters.

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Threshold Temperature Sensors with Tunable Properties
Authors: Crenshaw Brent R. , Kunzelman Jill , Sing Charles E. , Ander Christine , Weder Christoph
Published: March 2007

Thermochromic polymer/dye blends based on small amounts (0.6–2.3 wt.‐%) of chromogenic sensor dyes and glassy amorphous polymers were prepared. Subjecting melt‐processed, quenched blends to temperatures above Tg leads to permanent and pronounced changes of their absorption and fluorescence spectra as a result of phase separation and assembly of dye aggregates. The influence of dye structure and polymer Tg on the aggregation kinetics of these blends was investigated. It is shown that increasing the length of the dye's rigid core leads to slower aggregation rates due to limited mobility in the polymer. The threshold of the color change can be tailored by adjusting the polymer Tg, as was shown by the systematic investigation of blends based on poly(alkyl methacrylate) copolymers of varying composition.

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The moderating influence of mother‐adolescent discussion on early and middle African‐American adolescent sexual behavior
Authors: DiIorio Colleen , McCarty Frances , Denzmore Pamela , Landis Andrea
Published: March 2007

We examined how African‐American mothers' discussions with their adolescents about sex moderated the relationship between adolescents' sex‐based discussions with their friends and adolescents' involvement in sexual behaviors. The 425 African‐American adolescents were 12 through 15 years of age and had participated in an HIV prevention research project with their mothers. Linear and logistic regression analyses showed that, for girls, age, discussions with friends, and the interaction between mother and friend's sex‐based discussions were statistically significant predictors of sexual behaviors. These findings suggest that the level of discussion with mothers had a moderating effect on the relationship between friends' discussions about sex and a girl's involvement in sexual behaviors. Although these results were not apparent for boys, there was a strong relationship between discussions with friends about sex and sexual behaviors among boys. © 2007 Wiley Periodicals, Inc. Res Nurs Health 30: 193–202, 2007
Fast and reliable analysis of molecular motion using proximity relations and dimensionality reduction
Authors: Plaku Erion , Stamati Hernán , Clementi Cecilia , Kavraki Lydia E.
Published: March 2007

The analysis of molecular motion starting from extensive sampling of molecular configurations remains an important and challenging task in computational biology. Existing methods require a significant amount of time to extract the most relevant motion information from such data sets. In this work, we provide a practical tool for molecular motion analysis. The proposed method builds upon the recent ScIMAP (Scalable Isomap) method, which, by using proximity relations and dimensionality reduction, has been shown to reliably extract from simulation data a few parameters that capture the main, linear and/or nonlinear, modes of motion of a molecular system. The results we present in the context of protein folding reveal that the proposed method characterizes the folding process essentially as well as ScIMAP. At the same time, by projecting the simulation data and computing proximity relations in a low‐dimensional Euclidean space, it renders such analysis computationally practical. In many instances, the proposed method reduces the computational cost from several CPU months to just a few CPU hours, making it possible to analyze extensive simulation data in a matter of a few hours using only a single processor. These results establish the proposed method as a reliable and practical tool for analyzing motions of considerably large molecular systems and proteins with complex folding mechanisms. Proteins 2007. © 2007 Wiley‐Liss, Inc.
EADock: Docking of small molecules into protein active sites with a multiobjective evolutionary optimization
Authors: Grosdidier Aurélien , Zoete Vincent , Michielin Olivier
Published: March 2007

In recent years, protein–ligand docking has become a powerful tool for drug development. Although several approaches suitable for high throughput screening are available, there is a need for methods able to identify binding modes with high accuracy. This accuracy is essential to reliably compute the binding free energy of the ligand. Such methods are needed when the binding mode of lead compounds is not determined experimentally but is needed for structure‐based lead optimization. We present here a new docking software, called EADock, that aims at this goal. It uses an hybrid evolutionary algorithm with two fitness functions, in combination with a sophisticated management of the diversity. EADock is interfaced with the CHARMM package for energy calculations and coordinate handling. A validation was carried out on 37 crystallized protein–ligand complexes featuring 11 different proteins. The search space was defined as a sphere of 15 Å around the center of mass of the ligand position in the crystal structure, and on the contrary to other benchmarks, our algorithm was fed with optimized ligand positions up to 10 Å root mean square deviation (RMSD) from the crystal structure, excluding the latter. This validation illustrates the efficiency of our sampling strategy, as correct binding modes, defined by a RMSD to the crystal structure lower than 2 Å, were identified and ranked first for 68% of the complexes. The success rate increases to 78% when considering the five best ranked clusters, and 92% when all clusters present in the last generation are taken into account. Most failures could be explained by the presence of crystal contacts in the experimental structure. Finally, the ability of EADock to accurately predict binding modes on a real application was illustrated by the successful docking of the RGD cyclic pentapeptide on the αVβ3 integrin, starting far away from the binding pocket. Proteins 2007. © 2007 Wiley‐Liss, Inc.
Strategic groups, competitive groups and performance within the U.K. pharmaceutical industry: Improving our understanding of the competitive process
Authors: Leask Graham , Parker David
Published: March 2007

Strategic group research originated in the 1970s and a number of notable studies centered on the U.S. pharmaceutical industry. Results were, however, conflicting. This paper explores the nature of strategic groups in the U.K. pharmaceutical industry. The study confirms the presence of between six and eight strategic groups across the period studied, 1998–2002. The study also demonstrates a statistically significant relationship between these strategic groups and performance using three performance measures. The paper then compares strategic groups with competitive groups and concludes that the distinction is important and may explain the contradictory findings in earlier strategic group research. Copyright © 2007 John Wiley & Sons, Ltd.
Reevaluation of grading standards and discounts for fungus‐damaged soybean seeds
Authors: Sinclair James B.
Published: March 2007

The proportion of off‐colored seed is a primary quality‐rating factor that influences the market grade of soybean,Glycine max L. Merrill. Off‐colors, attributed to biological agents such as fungi and viruses, are visual characteristics that arbitrarily result in lower grade ratings when soybeans show more than ten percent discoloration. These damaged seeds may be further classified under current United States Department of Agriculture, Federal Grain Inspection Service standards as: moldy, weathered, bicolored, mottled, or other colors. Presently, all types of fungal damage and virus symptoms are evaluated equally in the application of discount schedules at grain‐elevators. However, recent information shows that superficial discoloration caused by some biological agents does not lower grain quality. Indeed, methods are available to distinguish those symptoms that actually reduce seed quality from those that are more cosmetic in nature. This communication provides guidance on fungi that are involved most often in seed damage or discoloration. The following organisms are listed in descending order of importance:Phomopsis longicolla, Alternaria, Nematospora coryli, Fusarium graminearum, Colletotrichum, andCercospora kikuchii. Discoloration caused byPeronospora manchurica (downy mildew) and the soybean mosaic virus have limited effect on seed quality. Discoloration caused by each of these agents may be identified by recognizable characteristics. Therefore, knowledge of the relative impact of these organisms on seed quality should be practiced in the application of soybean grading standards and discount schedules.
Trans‐18:1 acids in french tub margarines and shortenings: Recent trends
Authors: Bayard Corinne C. , Wolff Robert L.
Published: March 2007

The fatty acid composition of twelve French tub margarines and three industrial shortenings was established with particular attention to theirtrans‐18:1 acid content. Four of the twelve margarines (including two major brands, with 60% of market share) were devoid oftrans isomers, one contained less than 2%trans‐18:1 acids, whereas the seven others had a mean content of 13.5 ± 3.6%trans isomers. Four years ago, no margarines with 0%trans‐18:1 acids could be found. It is deduced that the recent Dutch and American studies on possible effects oftrans acids on human health (serum cholesterol, heart disease risks) may have had some influence on French margarine manufacturers. Presently, an average French tub margarine contains only 3.8% oftrans‐18:1 acids instead of 13% four years ago. To protect brand names, some manufacturers have replaced partially hydrogenated oils with tropical fats or fully hydrogenated oils. On the other hand, two of the three shortenings had high levels oftrans‐18:1 acids: 53.5 and 62.5%. This last value, obtained for a sample of hydrogenated arachis oil, seems to be one of the highest values ever reported for edible hydrogenated oils. In this sample,trans‐18:1 plus saturated acids accounted for 85% of total fatty acids. This would indicate that shortening producers and users are not yet aware of recent dietary recommendations, probably because these products are not easily identifiable by consumers in food items, in contrast to margarines.
Assessment of olive oil adulteration by reversed‐phase high‐performance liquid chromatography/amperometric detection of tocopherols and tocotrienols
Authors: Dionisi F. , Prodolliet J. , Tagliaferri E.
Published: March 2007

A method involving reversed‐phase high‐performance liquid chromatography with amperometric detection has been developed for the analysis of tocopherols and tocotrienols in vegetable oils. The sample preparation avoids saponification. Recoveries of α‐tocotrienol and γ‐tocotrienol in extra virgin olive oil were 97.0 and 102.0%, respectively. No tocotrienols were detected in olive, hazelnut, sunflower, and soybean oils, whether virgin or refined. However, relatively high levels of tocotrienols were found in palm and grapeseed oils. This method could detect small quantities (1–2%) of palm and grapeseed oils in olive oil or in any tocotrienol‐free vegetable oil and might, therefore, help assess authenticity of vegetable oils.
Estimation of sharma constant and thermoacoustic properties of fatty acids
Authors: Subrahmanyam M. S. R. , Vedanayagam H. Sumathi , Rao D. Venkateshwar , Rajaiah A. , Venkatacharyulu P.
Published: March 2007

From the volume expansivity α, a number of thermoacoustic parameters, including the Sharma constant,S0, are estimated for four fatty acids as a function of temperature. The Sharma constant, which was established to be a constant with the characteristic value 1.11 ± 0.01 over a number of systems investigated by earlier investigators, is also found to be a constant with the same value for all fatty acids under investigation. Further, the Sharma constant,S0, is independent of temperature and dependent only on α. All other parameters estimated are discussed and compared with the values reported in the literature by earlier workers for different systems.
Characterization of lipid hydroperoxides generated by photodynamic treatment of leukemia cells
Authors: Bachowski Gary J. , Korytowski Witold , Girotti Albert W.
Published: March 2007

A new technique, high‐performance liquid chromatography with reductive mode electrochemical detection on a mercury drop (HPLC‐EC), has been used for analyzing lipid hydroperoxide (LOOH) formation in photooxidatively stressed L1210 leukemia cells. Highly specific and sensitive for peroxides (detection limits <0.5 pmol for cholesterol hydroperoxides and <50 pmol for phospholipid hydroperoxides), this approach allows different classes of LOOH to be separated and determined in minimally damaged cells. L1210 cells in serum‐containing growth medium were irradiated in the presence of merocyanine 540 (MC540), a lipophilic photosensitizing dye. Lipid extracts from cells exposed to a light fluence of 0.11 J/cm2 (which reduced clonally assessed survival by 30%) showed 12–15 well‐defined peaks in HPLC‐EC. None of these peaks was observed when cells were irradiated without MC540 or when dye/light‐treated samples were reduced with triphenylphosphine prior to analysis. Three peaks of relatively low retention time (<12 min) were assigned to the following species by virtue of comigration with authentic standards: 3β‐hydroxy‐5α‐cholest‐6‐ene‐5‐hydroperoxide (5α‐OOH), 3β‐hydroxycholest‐4‐ene‐6β‐hydroperoxide (6β‐OOH), and 3β‐hydroxycholest‐5‐ene‐7α/7β‐hydroperoxide (7α/7β‐OOH). Formation of 5α‐OOH and 6β‐OOH (singlet oxygen adducts) was confirmed by subjecting [14C]cholesterol‐labeled cells to relatively high levels of photooxidation and analyzing extracted lipids by HPLC with radiochemical detection. Material represented in a major peak at 18–22 min on HPLC‐EC was isolated in relatively large amounts by semipreparative HPLC and shown to contain phospholipid hydroperoxides (predominantly phosphatidylcholine species, PCOOH) according to the following criteria: (i) decay of 18–22 min peak during Ca2+/phospholipase A2 treatment, with reciprocal appearance of fatty acid hydroperoxides; (ii) reduction of peroxide during treatment with reduced glutathione and phospholipid hydroperoxide glutathione peroxidase, but not glutathione peroxidase; and (iii) comigration with PCOOH standards in thin‐layer chromatography. HPLC‐EC analysis revealed quantifiable amounts ofPCOOH and ChOOH at a light fluence that clonally inactivated <10% of the cells, which allows for the possibility that photoperoxidative damage plays a causal role in cell killing.
Effect of dietary carnosine on plasma and tissue antioxidant concentrations and on lipid oxidation in rat skeletal muscle
Authors: Chan Wendy K. M. , Decker Eric A. , Chow Ching K. , Boissonneault Gilbert A.
Published: March 2007

The effect of dietary carnosine supplementation on plasma and tissue carnosine and α‐tocopherol concentrations and on the formation of thiobarbituric acid reactive substances (TBARS) in rat skeletal muscle homo‐genates was evaluated. Plasma, heart, liver and hind leg muscle was obtained from rats fed basal semipurified diets or basal diets containing carnosine (0.0875%), α‐tocopheryl acetate (50 ppm), or carnosine (0.0875%) plusα‐tocopheryl acetate (50 ppm). Dietary carnosine supplementation did not increase carnosine concentrations in heart, liver and skeletal muscle. Dietary supplementation with both carnosine and α‐tocopherol increased carnosine concentrations in liver 1.56‐, 1.51‐ and 1.51‐fold as compared with diets lacking carnosine, α‐tocopherol or both carnosine and α‐tocopherol, respectively. Dietary supplementation with both carnosine and α‐tocopherol also increased α‐tocopherol concentrations in heart and liver 1.38‐fold and 1.68‐fold, respectively, as compared to supplementation with α‐tocopherol alone. Dietary supplementation with carnosine, α‐tocopherol or both car‐nosine and α‐tocopherol was effective in decreasing the formation of TBARS in rat skeletal muscle homogenate, with dietary α‐tocopherol and α‐tocopherol plus carnosine being more effective than dietary carnosine alone. The data suggest that dietary supplementation with carnosine and α‐tocopherol modulates some tissue carnosine and α‐tocopherol concentrations and the formation of TBARS in rat skeletal muscle homogenates.
Enhanced treatment for depression in primary care: long-term outcomes of a psycho-educational prevention program alone and enriched with psychiatric consultation or cognitive behavioral therapy
Authors: CONRADI HENK JAN , de JONGE PETER , KLUITER HERMAN , SMIT ANNET , van der MEER KLAAS , JENNER JACK A. , van OS TITUS W. D. P. , EMMELKAMP PAUL M. G. , ORMEL JOHAN
Published: March 2007

Background. The long-term outcome of major depression is often unfavorable, and because most cases of depression are managed by general practitioners (GPs), this places stress on the need to improve treatment in primary care. This study evaluated the long-term effects of enhancing the GP's usual care (UC) with three experimental interventions.

Method. A randomized controlled trial was conducted from 1998 to 2003. The main inclusion criterion was receiving GP treatment for a depressive episode. We compared: (1) UC (n=72) with UC enhanced with: (2) a psycho-educational prevention (PEP) program (n=112); (3) psychiatrist-enhanced PEP (n=37); and (4) brief cognitive behavioral therapy followed by PEP (CBT-enhanced PEP) (n=44). We assessed depression status quarterly during a 3-year follow-up.

Results. Pooled across groups, depressive disorder-free and symptom-free times during follow-up were 83% and 17% respectively. Almost 64% of the patients had a relapse or recurrence, the median time to recurrence was 96 weeks, and the mean Beck Depression Inventory (BDI) score over 12 follow-up assessments was 9·6. Unexpectedly, PEP patients had no better outcomes than UC patients. However, psychiatrist-enhanced PEP and CBT-enhanced PEP patients reported lower BDI severity during follow-up than UC patients [mean difference 2·07 (95% confidence interval (CI) 1·13–3·00) and 1·62 (95% CI 0·70–2·55) respectively] and PEP patients [2·37 (95% CI 1·35–3·39) and 1·93 (95% CI 0·92–2·94) respectively].

Conclusions. The PEP program had no extra benefit compared to UC and may even worsen outcome in severely depressed patients. Enhancing treatment of depression in primary care with psychiatric consultation or brief CBT seems to improve the long-term outcome, but findings need replication as the interventions were combined with the ineffective PEP program.
Processes of initiation of motion leading to bedload transport in gravel‐bed rivers
Authors: Garcia Celso , Cohen Hai , Reid Ian , Rovira Albert , Úbeda Xavier , Laronne Jonathan B.
Published: March 2007

Transport processes that lead to the initiation of bedload motion in gravel‐bed rivers have not yet been clarified. We report patch‐ and grain‐scale processes involved in the initiation of bedload motion in a natural gravel‐bed stream as observed through a series of video experiments. With increasing flow strength, the phases of initiation of motion that have been identified are (1) within‐patch grain instability (grain vibration, pivoting, and grain‐scale rolling), (2) within‐patch gyratory step‐and‐rest motion, and (3) general sediment motion involving downstream transport from an individual patch and the throughput of grains inherited from upstream.
Monte Carlo simulations of two-dimensional hard core lattice gases
Authors: Fernandes Heitor C. Marques , Arenzon Jeferson J. , Levin Yan
Published: March 2007

Monte Carlo simulations are used to study lattice gases of particles with extended hard cores on a two-dimensional square lattice. Exclusions of one and up to five nearest neighbors (NN) are considered. These can be mapped onto hard squares of varying side length, λ (in lattice units), tilted by some angle with respect to the original lattice. In agreement with earlier studies, the 1NN exclusion undergoes a continuous order-disorder transition in the Ising universality class. Surprisingly, we find that the lattice gas with exclusions of up to second nearest neighbors (2NN) also undergoes a continuous phase transition in the Ising universality class, while the Landau–Lifshitz theory predicts that this transition should be in the universality class of the XY model with cubic anisotropy. The lattice gas of 3NN exclusions is found to undergo a discontinuous order-disorder transition, in agreement with the earlier transfer matrix calculations and the Landau–Lifshitz theory. On the other hand, the gas of 4NN exclusions once again exhibits a continuous phase transition in the Ising universality class—contradicting the predictions of the Landau–Lifshitz theory. Finally, the lattice gas of 5NN exclusions is found to undergo a discontinuous phase transition.
Hormone signalling and root development: an update on the latest Arabidopsis thaliana research
Authors: Perez-Perez Jose Manuel
Published: March 2007

Plants are sessile organisms whose developmental programs depend mainly on environmental cues that are sensed and interpreted through hormonal signalling pathways. Roots are specialised plant organs that are instrumental during water and nutrient uptake, biotic interactions, stress responses and for mechanical support. Our knowledge about the basic molecular events shaping root patterning and growth has advanced significantly in the past few years thanks to the use of Arabidopsis thaliana (L.) Heynh. as a model system. In this review, I will discuss recent findings that indicate crosstalk between growth regulators and hormone signalling pathways during primary root development. Further comparative research using non-model species will shed light on the conserved developmental modules among distant lineages involved in root architecture.
Stereotypic founder cell patterning and embryonic muscle formation in
Drosophila
require
nautilus
(MyoD) gene function
Authors: Wei Qin , Rong Yikang , Paterson Bruce M.
Published: March 2007

nautilus
is the only MyoD-related gene in
Drosophila
. Nautilus expression begins around stage 9 at full germ-band extension in a subset of mesodermal cells organized in a stereotypic pattern in each hemisegment. The muscle founder cell marker Duf-LacZ, produced by the enhancer trap line rP298LacZ, is coexpressed in numerous Nautilus-positive cells when founders first appear. Founders entrain muscle identity through the restricted expression of transcription factors such as S59, eve, and Kr, all of which are observed in subsets of the
nautilus
expressing founders. We inactivated the
nautilus
gene using homology-directed gene targeting and Gal4/UAS regulated RNAi to determine whether loss of
nautilus
gene activity affected founder cell function. Both methods produced a range of defects that included embryonic muscle disruption, reduced viability and female sterility, which could be rescued by hsp70-
nautilus
cDNA transgenes. Our results demonstrate Nautilus expression marks early founders that give rise to diverse muscle groups in the embryo, and that
nautilus
gene activity is required to seed the correct founder myoblast pattern that prefigures the muscle fiber arrangement during embryonic development.
A gliding lizard from the Early Cretaceous of China
Authors: Li Pi-Peng , Gao Ke-Qin , Hou Lian-Hai , Xu Xing
Published: March 2007

Gliding is an energetically efficient mode of locomotion that has evolved independently, and in different ways, in several tetrapod groups. Here, we report on an acrodontan lizard from the Early Cretaceous Jehol Group of China showing an array of morphological traits associated with gliding. It represents the only known occurrence of this specialization in a fossil lizard and provides evidence of an Early Cretaceous ecological diversification into an aerial niche by crown-group squamates. The lizard has a dorsal-rib-supported patagium, a structure independently evolved in the Late Triassic basal lepidosauromorph kuehneosaurs and the extant agamid lizard
Draco
, revealing a surprising case of convergent evolution among lepidosauromorphans. A patagial character combination of much longer bilaterally than anteroposteriorly, significantly thicker along the leading edge than along the trailing edge, tapered laterally to form a wing tip, and secondarily supported by an array of linear collagen fibers is not common in gliders and enriches our knowledge of gliding adaptations among tetrapods.
nanos
function is essential for development and regeneration of planarian germ cells
Authors: Wang Yuying , Zayas Ricardo M. , Guo Tingxia , Newmark Phillip A.
Published: March 2007

Germ cells are required for the successful propagation of sexually reproducing species. Understanding the mechanisms by which these cells are specified and how their totipotency is established and maintained has important biomedical and evolutionary implications. Freshwater planarians serve as fascinating models for studying these questions. They can regenerate germ cells from fragments of adult tissues that lack reproductive structures, suggesting that inductive signaling is involved in planarian germ cell specification. To study the development and regeneration of planarian germ cells, we have functionally characterized an ortholog of
nanos
, a gene required for germ cell development in diverse organisms, from
Schmidtea mediterranea
. In the hermaphroditic strain of this species,
Smed-nanos
mRNA is detected in developing, regenerating, and mature ovaries and testes. However, it is not detected in the vast majority of newly hatched planarians or in small tissue fragments that will ultimately regenerate germ cells, consistent with an epigenetic origin of germ cells. We show that
Smed-nanos
RNA interference (RNAi) results in failure to develop, regenerate, or maintain gonads in sexual planarians. Unexpectedly,
Smed-nanos
mRNA is also detected in presumptive testes primordia of asexual individuals that reproduce strictly by fission. These presumptive germ cells are lost after
Smed-nanos
RNAi, suggesting that asexual planarians specify germ cells, but their differentiation is blocked downstream of
Smed-nanos
function. Our results reveal a conserved function of
nanos
in germ cell development in planarians and suggest that these animals will serve as useful models for dissecting the molecular basis of epigenetic germ cell specification.
Protease-activated receptor-3 (PAR3) regulates PAR1 signaling by receptor dimerization
Authors: McLaughlin Joseph N. , Patterson Myla M. , Malik Asrar B.
Published: March 2007

Thrombin activates endothelial cell signaling by cleaving the protease-activated receptor-1 (PAR1). However, the function of the apparently nonsignaling receptor PAR3 also expressed in endothelial cells is unknown. We demonstrate here the crucial role of PAR3 in potentiating the responsiveness of PAR1 to thrombin. We tested the hypothesis that PAR1/PAR3 heterodimerization and its effect in modifying G protein selectivity was responsible for PAR3 regulation of PAR1 sensitivity. Using bioluminescent resonance energy transfer-2, we showed that PAR1 had comparable dimerization affinity for PAR3 as for itself. We observed increased Gα13coupling between the PAR1/3 heterodimer compared with the PAR1/1 homodimer. Moreover, knockdown of PAR3 moderated the PAR1-activated increase in endothelial permeability. These results demonstrate a role of PAR3 in allosterically regulating PAR1 signaling governing increased endothelial permeability. Because PAR3 is a critical determinant of PAR1 function, targeting of PAR3 may mitigate the effects of PAR1 in activating endothelial responses such as vascular inflammation.
Period two implies chaos for a class of ODEs
Authors: Obersnel Franco , Omari Pierpaolo
Published: March 2007

We extend a result of J. Andres and K. Pastor concerning scalar time-periodic first order ordinary differential equations without uniqueness, by proving that the existence of just one subharmonic implies the existence of large sets of subharmonics of all given orders. Since these periodic solutions must coexist with complicated dynamics, we might paraphrase T. Y. Li and J. A. Yorke by loosely saying that in this setting even period two implies chaos. Similar results are obtained for a class of differential inclusions.
Hilbert functions of Gorenstein monomial curves
Authors: Arslan Feza , Mete Pinar
Published: March 2007

It is a conjecture due to M. E. Rossi that the Hilbert function of a one-dimensional Gorenstein local ring is non-decreasing. In this article, we show that the Hilbert function is non-decreasing for local Gorenstein rings with embedding dimension four associated to monomial curves, under some arithmetic assumptions on the generators of their defining ideals in the non-complete intersection case. In order to obtain this result, we determine the generators of their tangent cones explicitly by using standard basis computations under these arithmetic assumptions and show that the tangent cones are Cohen-Macaulay. In the complete intersection case, by characterizing certain families of complete intersection numerical semigroups, we give an inductive method to obtain large families of complete intersection local rings with arbitrary embedding dimension having non-decreasing Hilbert functions.
On regularization of plurisubharmonic functions on manifolds
Authors: Blocki Zbigniew , Kolodziej Slawomir
Published: March 2007

We study the question of when a

γ
\gamma

-plurisubharmonic function on a complex manifold, where

γ
\gamma

is a fixed

(
1
,
1
)

(1,1)

-form, can be approximated by a decreasing sequence of smooth

γ
\gamma

-plurisubharmonic functions. We show in particular that it is always possible in the compact Kähler case.
Average ranks of elliptic curves: Tension between data and conjecture
Authors: Bektemirov Baur , Mazur Barry , Stein William , Watkins Mark
Published: March 2007

Rational points on elliptic curves are the gems of arithmetic: they are, to diophantine geometry, what units in rings of integers are to algebraic number theory, what algebraic cycles are to algebraic geometry. A rational point in just the right context, at one place in the theory, can inhibit and control—thanks to ideas of Kolyvagin—the existence of rational points and other mathematical structures elsewhere. Despite all that we know about these objects, the initial mystery and excitement that drew mathematicians to this arena in the first place remains in full force today. We have a network of heuristics and conjectures regarding rational points, and we have massive data accumulated to exhibit instances of the phenomena. Generally, we would expect that our data support our conjectures, and if not, we lose faith in our conjectures. But here there is a somewhat more surprising interrelation between data and conjecture: they are not exactly in open conflict one with the other, but they are no great comfort to each other either. We discuss various aspects of this story, including recent heuristics and data that attempt to resolve this mystery. We shall try to convince the reader that, despite seeming discrepancy, data and conjecture are, in fact, in harmony.
Convergence of Kähler-Ricci flow
Authors: Tian Gang , Zhu Xiaohua
Published: March 2007

In this paper, we prove a theorem on convergence of Kähler-Ricci flow on a compact Kähler manifold which admits a Kähler-Ricci soliton.
Upper bounds in quantum dynamics
Authors: Damanik David , Tcheremchantsev Serguei
Published: March 2007

We develop a general method to bound the spreading of an entire wavepacket under Schrödinger dynamics from above. This method derives upper bounds on time-averaged moments of the position operator from lower bounds on norms of transfer matrices at complex energies. This general result is applied to the Fibonacci operator. We find that at sufficiently large coupling, all transport exponents take values strictly between zero and one. This is the first rigorous result on anomalous transport. For quasi-periodic potentials associated with trigonometric polynomials, we prove that all lower transport exponents and, under a weak assumption on the frequency, all upper transport exponents vanish for all phases if the Lyapunov exponent is uniformly bounded away from zero. By a well-known result of Herman, this assumption always holds at sufficiently large coupling. For the particular case of the almost Mathieu operator, our result applies for coupling greater than two.