bluuebunny/crossref_metadata_2025 huggingface dataset:
Transesterification Reaction of Dimethyl Terephthalate by 2‐Ethylhexanol in the Presence of Heterogeneous Catalysts under Solvent‐free Condition
Authors: Firdovsi Seyidov Tataroglu , Yagoub Mansoori , Parvin Alizadeh Eslamia
Published: February 2007

In this study, the synthesis of bis‐(2‐ethylhexyl) terephthalate, via the transesterification reaction of dimethyl terephthalate (DMT) by 2‐ethylhexanol in the presence of different heterogeneous catalysts, such as Pb(OAc)2·3H2O, Cd(OAc)2·2H2O, Zn(OAc)2·2H2O, Hg(OAc)2, Ca(OAc)2·H2O, Cu(OAc)2·H2O, NaOAc, CaCO3, CaO, ZnSO4·7H2O, and sulfated zirconia, has been investigated. The reactivity of the catalysts in the reaction progress has been studied and compared. It was found that, hydrated cadmium acetate and sulfated zirconia were reactive catalysts to this reaction. The extent of transesterification of methyl ester groups reached up to 93% and 85.6% using these catalysts, respectively.
Measurement of antigen specific immune responses: 2006 update
Authors: Pira Giuseppina Li , Kern Florian , Gratama Jan , Roederer Mario , Manca Fabrizio
Published: February 2007

Measuring antigen‐specific immune responses (MASIR) is essential for basic immunological research and in the clinical setting. Numerous techniques have been used and the recent years have witnessed a flourishing of flow cytometry based methods for the identification of antigen specific T cells, in addition to other methodologies. The second MASIR conference held in Santorini, Greece, from 14 to 18 June 2006 has been a forum for the discussion of methodological issues and for research or clinical applications of these techniques, as reviewed here. In addition to flow cytometry based techniques, other emerging techniques with different degrees of complexity can be applied. These novel methods are highly promising in numerous conditions to look for correlates of protection, to test responses to natural infections or to vaccination trials, to evaluate the immune status of immunocompromised patients and to monitor persistence and function of specific T cells administered as adoptive therapy. © 2007 Clinical Cytometry Society
The Lower Cretaceous Chañarcillo and Neuquén Andean basins: ammonoid biostratigraphy and correlations
Authors: Aguirre‐Urreta M. Beatriz , Mourgues F. Amaro , Rawson Peter F. , Bulot Luc G. , Jaillard Etienne
Published: February 2007

The Chañarcillo and Neuquén basins of the Central Andes shared a common geological history in the earlier part of the Early Cretaceous but from Barremian times onward their evolution began to diverge, probably due to an increasing activity of an intervening volcanic arc. The Berriasian to Lower Barremian sequences were mainly marine and include rich ammonoid faunas, with many taxa in common to both the basins. They include both Andean and near‐pandemic forms, the latter providing some good correlation levels with the ‘standard’ Mediterranean sequence. Marine conditions persisted in the Chañarcillo Basin till Early Albian times; the associated ammonoid faunas include pandemic, Pacific and Antarctic genera. In contrast, in the Neuquén Basin evaporites and continental clastics of the Huitrín Formation mark the beginning of a long disconnection with the Pacific Ocean, though a short‐lived marine incursion is represented by the carbonates of La Tosca Member of the Huitrín Formation. The ammonoid faunas of the two basins are compared here, and a detailed biostratigraphic division of the sequences is discussed and compared with the Mediterranean succession. Copyright © 2007 John Wiley & Sons, Ltd.
Gender and endogenous levels of estradiol do not influence adult hippocampal neurogenesis in mice
Authors: Lagace Diane C. , Fischer Stephanie J. , Eisch Amelia J.
Published: February 2007

In several species, including rat and vole, the proliferation of new neurons in the adult dentate gyrus (DG) subgranular zone (SGZ) is influenced by both gender and endogenous levels of the gonadotropic steroid hormone estradiol. However, little is known about how adult neurogenesis is regulated by these factors in the mouse. We report here that adult C57BL/6 mice do not have gender differences in hippocampal proliferation or neurogenesis. In addition, the production of new SGZ cells in female mice was not influenced by estrous cycle or after ovariectomy, suggesting that fluctuations in endogenous estradiol levels do not alter adult neurogenesis in the mouse. Both male and female mice had a greater number of BrdU‐immunoreactive SGZ cells following chronic treatment with fluoxetine. This demonstrates a parallel proliferation response in both genders, and opens avenues for addressing the neurogenesis hypothesis of depression in female rodents. These findings underscore a distinct regulation of adult neurogenesis in mice vs. other rodents, and are discussed in regard to their implications for the study of adult hippocampal neurogenesis. © 2007 Wiley‐Liss, Inc.
The Seasonal Succession of Biotic Communities in Wetlands of the Tropical Wet‐and‐Dry Climatic Zone: V. Aquatic Invertebrate Communities in the Pantanal of Mato Grosso, Brazil
Authors: Heckman Charles W.
Published: February 2007

The results of a 3 1/2 year study in the Pantanal of Mato Grosso revealed that the life cycles of the invertebrates are profoundly influenced by the annual alternations between a period of very heavy rainfall and several months during which almost no rain falls. A very pronounced effect on the biota is the elimination of many species present in neighboring regions but without the ability to survive periods of adverse conditions resulting from the alternations between flood and dryness. However, those species with suitable adaptations are able to produce very large populations. The annual activity cycles of the invertebrates must not only be timed to the seasonal weather conditions but also to the activities of other species in the food web. They must be adapted to periods of surplus alternating with scarcity of food and predator pressure, which exert great influence on the development of the populations. Of the 256 species considered, most have the ability to produce offspring throughout the year whenever conditions are conducive, but there are also a considerable number which have life cycles apparently including only one reproductive period each year. The general effect of the seasonal changes on the aquatic community of the wetland is to greatly reduce species diversity but to allow the production of vast numbers of those species that have successfully adapted to the conditions. This adaptation of the aquatic species usually entails a dormant stage or a terrestrial one as well as a considerable rate of reproduction to offset losses during periods of unfavorable conditions. The invertebrate fauna includes several taxa represented overwhelmingly by cosmopolitan and circumtropical species, including Rotifera and Gastrotricha, but the great majority of the species are endemic to South America.
Spatio‐Temporal Distribution and Ecological Preferences of Coexisting Hydropsychid Species (Trichoptera) in Two Mediterranean River Basins (S Spain)
Authors: Gallardo‐Mayenco Alfonso , Prenda José , Toja Julia
Published: February 2007

The hydropsychids of two Mediterranean river basins in southern Spain (Guadaira and Guadalete) were investigated from January 1988 to January 1989. The distribution of hydropsychids along an environmental gradient related to altitude varied depending on species. Two distinct species assemblages were observed. one located in the lower altitude sites (the “downstream assemblage” comprising Hydropsyche pictetorum, Hydropsyche exocellata and Cheumatopsyche lepida) and the other in the upper‐most areas (the “upstream assemblage” comprising Hydropsyche punica, Hydropsyche infernalis, Hydropsyche instabilis), which displayed a statistically significant preference for this type of habitat. Finally, H. pictetorum, selected the lowest sites. From a temporal point of view most species displayed a high variability in density dynamics between sites, suggesting a strong plasticity in life‐cycle phenology.
Limnological Characteristics of 70 Lakes Spanning Arctic Treeline from Coronation Gulf to Great Slave Lake in the Central Northwest Territories, Canada
Authors: Rühland Kathleen , Smol John P.
Published: February 2007

Latitudinal transects across subpolar ecozones display striking changes in lakewater chemistry reflecting steep gradients in vegetation, climate, and other variables. This paper explores the relationships among chemical and physical lakewater characteristics of 70 lakes spanning arctic treeline in Canada's Central Northwest Territories. Principal components analysis (PCA) was used to examine trends and relationships among environmental variables and these 70 sites. In general, lakes in this data set were dilute, slightly acidic to slightly alkaline, and nutrient‐poor. However, a strong trend toward more concentrated lakewater conditions in densely forested areas was observed relative to tundra regions. Interrelationships among measured limnological variables appear to be strongly influenced by catchment characteristics associated with proximity of sites to treeline.
Maghnite, a Green Catalyst for Cationic Polymerization of Vinylic and Cyclic Monomers
Authors: Belbachir M. , Harrane A. , Megharbi R.
Published: February 2007

Maghnite‐H is a nontoxic catalyst for cationic polymerization of vinylic and heterocyclic monomers. This catalyst is issued from the proton exchange of Algerian montmorillonite clay. One application of this catalyst is to produce polydioxolane derivatives. The polymerization of 1,3‐dioxolane catalyzed by Maghnite‐H; (Mag‐H), was investigated. The cationic ring‐opening polymerization of 1,3‐dioxolane was initiated by Mag‐H at different temperatures (20, 30, 50, and 70 °C) in bulk and in a solvent (dichloromethane). The effects of the amount of Mag‐H and the temperature were studied. The polymerization rate and the average molecular weights increased with an increase in the temperature and the proportion of the catalyst. These results indicated the cationic nature of the polymerization and suggested that the polymerization was initiated by proton addition to the monomer from Mag‐H. Moreover, we used a simple method, in one step in bulk and in solution at room temperature (20 °C), to prepare a telechelic bismacromonomer: bis‐unsaturated poly(1,3‐dioxolane).
Water‐Soluble Polyelectrolytes with Metal Ion Removal Ability by Using the Liquid Phase Based Retention Technique
Authors: Rivas Bernabé L. , Pooley S. Amalia , Pereira Eduardo D. , Maureira Antonio
Published: February 2007

Water‐soluble polyelectrolytes containing carboxylic acid groups were investigated as polychelatogens, in view to study their metal ion binding properties, using the liquid‐phase polymer‐based retention technique under different experimental conditions. The divalent metal ions investigated were: Co2+, Cu2+, Zn2+, and Cd2+. When the pH increased above 3, and especially at pH 5, metal ion retention capability increased as the majority of the functional groups are carboxylate, which can form more stable complexes with the metal ions. The retention capability also depended on the structure of the polyelectrolyte and the filtration factor, Z.
Characterization of an Epoxy Resin Modified with Natural Oil‐Based Reactive Diluents
Authors: Czub Piotr
Published: February 2007

Modified natural oils ‐ epoxidized soybean and rapeseed oils were tested as reactive diluents for viscosity regulation of Bisphenol A‐based low‐molecular‐ weight epoxy resin. Satisfactory viscosity reducing ability of epoxidized oils as well as non‐Newtonian rheological behaviour of the resin diluted with modified oils were demonstrated. Co‐crosslinking of mixed oil‐resin compositions using isophorone diamine was studied showing essential decreasing of the reaction heat and slight increasing of the peak maximum temperature. Mechanical properties, thermal stability, water absorption and chemical resistance of the epoxy resin modified with natural oils were also investigated.
Structural Analysis of (LDPE) and (HDPE) Films Biodegraded in Sanitary Landfill‐ II
Authors: Grisa Ana M.C. , Zeni Mara
Published: February 2007

The use of the polymeric commodities LDPE and HDPE in the most varied industrial applications and for economic interests, it produces discards in the waste, and great demand of the same ones in the sanitary landfill. In this work we have studied degradation/biodegradation of the polyethylene (PE) in the landfill São Giácomo in Caxias do Sul, Brazil. The PE was collected in cell C4 with 94 months of age and different depths (11 to 16 m). The samples films was analyzed thermogravimetric (TGA), morphologic (SEM) and structural (FT‐IR) determinations of these degraded materials in landfill. The samples in the waste presented the one degradation pick and for the LDPE mass loss it increases and for HDPE mass loss creases with the dump. Evidenced structural changes with absorbency increment corresponding mainly to vibrations in new frequencies. The morphologic analyses (SEM) the films samples they present scales and fissures.
Synthesis and properties of hyperbranched polybenzimidazoles via A2 + B3 approach
Authors: Xu Hongjie , Chen Kangcheng , Guo Xiaoxia , Fang Jianhua , Yin Jie
Published: February 2007

Hyperbranched polybenzimidazoles (HBPBIs) were successfully synthesized by condensation polymerization of 1,3,5‐benzenetricarboxylic acid (BTA) and 3,3′‐diaminobenzidine (DAB) in polyphosphoric acid (PPA) at 190 °C. Different monomer addition manners and molar ratios resulted in different polymers, that is, simultaneous addition of BTA and DAB with the molar ratio of 1:1 (manner 1) gave carboxyl‐terminated HBPBI (HBPBI‐1), whereas the addition of BTA portion‐wise to DAB solution in PPA with the molar ratio of DAB:BTA = 2:1 (manner 2) yielded amine‐terminated HBPBI (HBPBI‐2). The free carboxyl and amino groups of HBPBI‐1 and HBPBI‐2 could further react with o‐diaminobenzene and benzoic acid, respectively, to form the chemically modified polymers. Except HBPBI‐2, all the HBPBIs showed good solubility in some organic solvents (e.g., dimethyl sulfoxide and N,N‐dimethylacetamide). Thermogravimetric analysis measurement revealed that HBPBIs except HBPBI‐1 had high thermal stability (>450 °C). HBPBI membranes with good mechanical properties were obtained by crosslinking treatment of partially chemically modified HBPBIs with terephthaldehyde (TPA) during the film cast process. The HBPBI membranes had high phosphoric acid uptake and the phosphoric acid‐doped HBPBI‐6 (40% o‐diamino groups were reacted with benzoic acid) membrane showed higher tensile strength than the acid‐doped commercial PBI despite the higher doping level of the former. © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1150–1158, 2007
Tight binding modelling of electronic band structure in conventional InGaN/GaN and dilute GaAsN/GaAs nitride heterostructures
Authors: Hakan Gürel H. , Akıncı Özden , Ünlü Hilmi
Published: February 2007

We utilize a semi‐empirical sp3s * tight binding model to investigate the strain and composition effects on electronic structure of conventional InGaN/GaN and dilute GaAsN/GaAs cubic nitride heterostructures. The model includes the second nearest neighbor (2NN) atomic interactions, spin‐orbit splitting and nonlinear composition variation of atomic energies and bond lengths of ternaries. Results show that band gaps of conventional InGaN increase with composition for 0 < x < 1. However, the Γ band gap of dilute GaAsN decreases with composition for x < 0.25 and then starts to increase for 0.26 < x < 1. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A semiconductor based pump‐probe system and its application to THz spectroscopy
Authors: Vickers A. J. , Dudley R. , Henning I. , Ma Y.
Published: February 2007

In this work a description of a semiconductor laser based system is presented that can be utilised in many pump‐probe experiments and in particular as the basis for a THz spectrometer. There are two methods described, one which has a stepping time delay function and the other which has a sweep time delay function. These two methods are achieved in the first case by a manipulation of the relative gain switching of two semiconductor lasers and in the second case by a gain switching of two semiconductor lasers with slightly different RF frequencies. The time delay by cross‐correlating the two gain switched laser outputs on a silicon APD via two photon absorption is demonstrated. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
A novel synthesis route for a gold–polymer soft composite material
Authors: Mallick Kaushik , Witcomb Mike , Scurrell Mike
Published: February 2007

Figure 3 of the Rapid Research Letter by Mallick et al. [phys. stat. sol. (RRL) 1, No. 1, R1–R3 (2007)] is presented here in its correct form. (© 2007 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Brandschaden und Instandsetzung der Wiehltalbrücke im Zuge der A4, Köln – Olpe
Authors: Eisel Hans , Palm Norbert , Prehn Wolfgang , Sedlacek Gerhard
Published: February 2007

Am 26. August 2004 hat ein tragischer Verkehrsunfall eines Tankfahrzeuges auf der Wiehltalbrücke zu dessen Absturz von der Brücke und zu erheblicher Brandeinwirkung auf den Stahlüberbau im ersten Brückenfeld geführt.

Der Beitrag schildert die Sofortmaßnahme zur Sicherung der Brücke, provisorische Verstärkungen zur schnellen Wiederaufnahme des Autobahnverkehrs und die endgültige Instandsetzung zur Wiederherstellung des ursprünglichen Brückenzustandes.

Charakteristisch für die Robustheit der Stahlkonstruktion gegenüber Brand ist, daß trotz Flammtemperaturen um 1200 °C die Objekttemperatur nur etwa 500 °C erreichte, so daß die Schäden in Grenzen blieben.

Die darauf schließenden Werkstoffbefunde wurden durch einen rechnerischen Nachweis mit Naturbrand bestätigt.
Analysis of tocopherols by capillary supercritical fluid chromatography and mass spectrometry
Authors: Snyder Janet M. , Taylor Scott L. , King Jerry W.
Published: February 2007

Tocopherol‐containing mixtures were analyzed by gas chromatography (GC) and capillary supercritical fluid chromatography (SFC). GC analysis of tocopherols required the formation of the silyl derivatives, while SFC analysis of the tocopherol‐containing mixtures was accomplished on neat samples. SFC analysis conditions were optimized with respect to column type and density/pressure programming. Enhanced resolution of many components was achieved by using inverse temperature programming during the SFC analyses. Both SFC and GC analyses permitted the separation and quantitation of alpha‐, beta‐, gamma‐ and delta‐tocopherols. In addition, SFC proved particularly applicable for characterizing the composition of a deodorizer distillate and commercial antioxidant formulation. Coupling of a quadrapole mass spectrometer with a supercritical fluid chromatograph was also achieved; the mass spectrometer provided electron impact mass spectra on the underivatized tocopherol and sterol moieties. Both SFC and SFC/mass spectrometry proved effective for the analysis of complex lipid‐containing mixtures, requiring minimal sample preparation prior to analysis.
Evaluation of some approaches to liquified tallow: Stereochemical consequences of interesterification
Authors: Sonnet Philip E. , Pfeffer Philip E. , Wise William B.
Published: February 2007

Several approaches to converting tallow to a liquid state at ambient temperature to facilitate incorporation into poultry feed were examined. Acetone fractionation can be used in a single step to produce a flowable powder and an oil (no additional semi‐solid fraction). Partial hydrolyses and interestifications mediated by lipases ofCandida rugosa, Rhizopus delemar and porcine pancreas did not lead to liquefaction. Interesterification (trioctanoin + glycerol, 1,2‐acetonide) in the presence ofC. rugosa lipase shows a small but significant sterobias indicating that there are stereochemical consequences in such processes that deserve further investigation.
Biodegradation and fish toxicity of nonionic surfactants
Authors: Yoshimura Koichi
Published: February 2007

In order to investigate the fate and toxicity to fish of nonionic surfactants in the environment, biodegradation tests of river sediments and river water were carried out. In the biodegradation test of river sediments, residual surfactants in the water phase and sediments were analyzed by the colorimetric cobalt‐thiocyanate method (CTAS) and high performance liquid chromatography (HPLC) with a fluorimetric detector. Two kinds of nonionic surfactants, polyoxyethylene nonylphenol ether (C9APE9) and polyoxyethylene alcohol ether (C12AE7), were degraded by river sediments under both stirring and standing conditions, detected by CTAS and HPLC measurements. There was little difference between the time‐course of both surfactants measured by CTAS and HPLC in the water phase. Although the adsorption of both surfactants on sediments was low, most of both surfactants adsorbed on sediments were biodegraded during the test period. Nonylphenolmonoethoxy acetate (Met 2) and nonylphenolacetate (Met 1) were identified as biodegradation intermediates using preparative HPLC and mass spectrometric analysis.

In the river die‐away test of C9APF9, the reduction of toxicity to fish of C9APE9 was observed in the course of biodegradation (after 10 days). LC50 of primary biodegradation intermediates, Met 1 and 2, was almost at the same level as that of C9APE9. This result suggests that the reduction of toxicity to fish is due to further biodegradation of C9APE9 through Met 1 and 2.
Interfacial properties of hydrocarbons
Authors: Gillap William R. , Weiner Norman D. , Gibaldi Milo
Published: February 2007

The interfacial tension of aliphatic hydrocarbon‐water systems has been found to increase in a linear fashion as a function of the log of hydrocarbon chain length. Contrary to the literature, values of ϕ and े H2dO were observed to be also dependent on hydrocarbon chain length. The relationship between hydrocarbon chain length and interfacial tension is actually opposite to that predicted by Antonow's rule. The results are discussed in terms of hydrocarbon‐water interaction and water‐structure at the interface.
Homogenous catalysis in the reactions of olefinic substances. V. Hydrogenation of soybean oil methyl ester with triphenylphosphine and triphenylarsine palladium catalysts
Authors: Itatani Hiroshi , Bailar John C.
Published: February 2007

Some palladium complexes containing coordinated triphenylphosphine or arsine have been found to be effective and selective catalysts in the homogeneous hydrogenation of soybean oil methyl ester. The characteristic features of the catalysis are 1) isomerization ofcis double bonds totrans double bonds, 2) migration of isolated double bonds to form conjugated dienes, 3) selective hydrogenation of poly olefines to mono olefines without hydrogenation of mono olefine, 4) ester exchange of methyl ester to butyl ester, 5) effective hydrogenation and isomerization by methanol in the absence of elemental hydrogen.

The catalytic activity of a variety of palladium complexes decreases in the following order: (ϕ3P)2PdCl2+SnCl2ƃ2H2O>(ϕ3P)2PdCl2+GeCl2>(ϕ3P)2Pd(CN)2> (ϕ3As)2Pd(CN)2>(ϕ3P)2PdCl2 » (ϕ3As)2PdCl2. However, neither K2PdCl4 with SnCl2ƃ2H2O nor (ϕ3P)2Pd(SCN)2 was effective for hydrogenation. The hydrogenation and isomerization of soybean oil methyl ester have been examined under various conditions using a mixture of (ϕ3P)2PdCl2 and SnCl2ƃ2H2O. Under nitrogen pressure, in benzene and methanol as a solvent, both isomerization and hydrogenation of soybean oil methyl ester proceeded less effectively than under hydrogen pressure.
A new acid fromcalea urticaefolia seed oil:trans‐3,cis‐9,cis‐12‐octadecatrienoic acid
Authors: Bagby M. O. , Siegl W. O. , Wolff I. A.
Published: February 2007

A major constituent fatty acid (31.2%) fromCalea urticaefolia (Mill.) DC. seed oil is the previously unknowntrans‐3,cis‐9,cis‐12‐octadecatrienoic acid. The oil also contains 2.2% of an unidentified acid and others with gas‐liquid chromatographic characteristics that correspond to the conventional fatty acids: myristic, 0.1%; palmitic, 9.3%; stearic, 2.9%; oleic, 5.3%; and linoleic, 48.9%.
Quality of corn germ oil obtained by aqueous enzymatic extraction
Authors: Bocevska Mirjana , Karlović Djerdj , Turkulov Jovan , Pericin Draginja
Published: February 2007

Aqueous enzymatic extraction of corn germ oil was investigated. By applying hydrothermal pretreatment of corn germ, it was possible to inactivate native enzymes present in the germ and to loosen its structure. The corn was then ground and treated with enzymes. After the oil had been released by the enzyme reaction, it was separated by centrifugation. The quality of oil obtained by enzymatic extraction (Pectinex Ultra SP‐L at 37°C, pH 5.2, for 6 h) was good. The oil had 1.5% free fatty acids; a total content of oxidation product value of 8.1; light yellow color (AOCS photometric color, 12.7; dominant wavelength λD=575 nm); 0.022% phosphatides; 1350 mg/kg total tocopherol; and an oxidative stability value (Rancimat test, 100°C) of 14.6 h.
Proteasome function is required for activation of programmed cell death in heat shocked tobacco Bright‐Yellow 2 cells
Authors: Vacca Rosa A. , Valenti Daniela , Bobba Antonella , de Pinto Maria C. , Merafina Riccardo S. , De Gara Laura , Passarella Salvatore , Marra Ersilia
Published: February 2007

To find out whether and how proteasome is involved in plant programmed cell death (PCD) we measured proteasome function in tobacco cells undergoing PCD as a result of heat shock (HS‐PCD). Reactive oxygen species (ROS) production, cytochrome c levels and caspase‐3‐like protease activation were also measured in the absence or presence of MG132, a proteasome inhibitor. We show that proteasome activation occurs in early phase of HS‐PCD upstream of the caspase‐like proteases activation; moreover inhibition of proteasome function by MG132 results in prevention of PCD perhaps due to the prevention of ROS production, cytochrome c release and caspase‐3‐like protease activation.
The cytosolic ribonuclease inhibitor contributes to intracellular redox homeostasis
Authors: Monti Daria Maria , Montesano Gesualdi Nicola , Matoušek Josef , Esposito Franca , D’Alessio Giuseppe
Published: February 2007

The hypothesis that the cytosolic RNase inhibitor (cRI) has a role in the protection of the cellular redox homeostasis was investigated testing the effects of oxidants and anti‐oxidants on normal, primary endothelial HUVE cells, and malignant HeLa cells, before and after their engineering into cRI‐deprived cells. We found that cRI plays an important, possibly a key, physiological role in the protection of cells from redox stress, as demonstrated by decreased GSH levels as well as increased oxidant‐induced DNA damage in cRI deprived cells.
Monomeric dark rhodopsin holds the molecular determinants for transducin recognition: Insights from computational analysis
Authors: Dell’Orco Daniele , Seeber Michele , Fanelli Francesca
Published: February 2007

In this computational study, we have investigated the implications of rhodopsin (Rho) oligomerization in transducin (Gt) recognition. The results of docking simulations between heterotrimeric Gt and monomeric, dimeric and tetrameric inactive Rho corroborate the hypothesis that Rho and Gt can be found coupled already in the dark. Moreover, our extensive computational analysis suggests that the most likely Rho:Gt stoichiometry is the 1:1 one. This means that the essential molecular determinants for Gt recognition and activation are contained in one Rho monomer. In this respect, the complex between one Rho molecule and one heterotrimeric Gt should be considered as the functional unit.
Outsourcing impact on manufacturing firms’ value: Evidence from Japan
Authors: Jiang Bin , Belohlav James A. , Young Scott T.
Published: February 2007

Previous studies on the effects of outsourcing have relied largely on anecdotal evidence, non‐financial metrics or accounting‐based measures that ignore intangible value. This study views outsourcing effects from its future revenue‐generation potential, using market value. The relation between firms’ market valuation and outsourcing decisions is investigated using a cross‐sectional valuation approach. Results based on Japanese manufacturing industries data from 1994 to 2002 indicate that core business‐related outsourcing, offshore outsourcing, and shorter‐term outsourcing have positive effects on outsourcing firms’ market value. In contrast, non‐core business‐related outsourcing, domestic outsourcing, and longer‐term outsourcing are not found to enhance firm value.
Folate deficiency is associated with nutritional anaemia in Lebanese women of childbearing age
Authors: Khatib Lynn Al , Obeid Omar , Sibai Abla-Mehio , Batal Malek , Adra Nada , Hwalla Nahla
Published: February 2007

Objective

The objective of this study was to identify the determinants of anaemia in Lebanese women of childbearing age attending health centres in Lebanon.

Design

Cross-sectional study carried out between May and December 2003. Anthropometric measurements as well as sociodemographic, health and dietary intake data were collected using a questionnaire. Haemoglobin (Hb), plasma ferritin, plasma folate and vitamin B12were assessed using standard laboratory methods.

Setting

Governmental health centres in Lebanon.

Subjects

Four hundred and seventy non-pregnant Lebanese women aged 15–45 years.

Results

Anaemia (Hb <12 g dl−1) and iron deficiency (ferritin <15 μg l−1) were prevalent in 16.0 and 27.2% of the study sample, respectively. Of the total sample, 7.7% had iron-deficiency anaemia. The percentage of women with either Hb or ferritin deficiency or both was 35.6%. Plasma folate and vitamin B12deficiency was reported in 25.1 and 39.4%, respectively, and 12.6% of the women had both folate and vitamin B12deficiencies. Of the anaemic group, 48.0% of the women had iron deficiency. The intake of iron was lower in iron-deficient than in non-deficient women and a positive relationship was shown between folate intake and its corresponding serum levels. Regression analysis showed that ferritin, plasma folate and family history of anaemia were significant determinants of the anaemia in the sample of women.

Conclusions

Anaemia not related to iron deficiency was partly explained by plasma folate deficiency. Measures to control folate and iron deficiency should be considered.
Scandal, Protection, and Recovery in the Cabinet
Authors: DEWAN TORUN , MYATT DAVID P.
Published: February 2007

Empirical evidence suggests that a prime minister benefits from firing ministers who are involved in political scandals. We explore a model in which scandals are positively related to policy activism, so that a prime minister may wish to protect a minister from resignation calls. We find that protection can sometimes discourage activism: it enhances the value of a minister's career and hence encourages him to “sit tight” by moderating his activities. On the other hand, an exogenous increase in exposure to scandals may lead a minister to “live for today” by pursuing controversial policies. The prime minister's ability to protect ministers is limited by her short-term incentive to fire. She may, however, enhance her credibility by building a collective reputation with the cabinet; the heterogeneity of cabinet membership plays an important role.
Tax Me If You Can: Ethnic Geography, Democracy, and the Taxation of Agriculture in Africa
Authors: KASARA KIMULI
Published: February 2007

It is typically assumed that African leaders enact policies that benefit their ethnoregional group using all types of patronage. Crop production and political power are geographically concentrated in many African countries, and this paper exploits this overlap to cast doubt on this conventional wisdom. It shows, using data on 50 country-crop combinations, that cash crop farmers who are ethnically identified with the head of state facehighertaxes. Furthermore, democratic regimes impose lower taxes. This paper shows that farmers who have few alternatives face higher taxes. African leaders have used local intermediaries to exert control over the countryside and to ensure that farmers do not support alternative candidates. It suggests that as leaders are better at selecting and monitoring these intermediaries in their home areas, they can extract more from the majority at home than abroad using taxes on cash crops, which are regionally but not individually targetable.
Explaining Bureaucratic Optimism: Theory and Evidence from U.S. Executive Agency Macroeconomic Forecasts
Authors: KRAUSE GEORGE A. , CORDER J. KEVIN
Published: February 2007

We offer a theory of intertemporal bureaucratic decision making which proposes that an agency's forecast optimism is related to the extent to which it discounts future reputation costs associated with bureaucratic incompetence. Agency forecasts of the distant future are more likely to be optimistic than short-term forecasts. We claim that unstable organizations will discount reputation costs at a steeper rate than stable organizations, and therefore will produce more optimistic forecasts. We test our theory using macroeconomic forecasts produced by the Office of Management and Budget (OMB) and the Social Security Administration (SSA) across six forecast horizons from 1979 to 2003. The statistical results are generally consistent with our theory: OMB generates more optimistic long-term forecasts than SSA. Further, differences in forecast optimism between these executive branch agencies widen as the forecast horizon increases. Our evidence suggests that more stable agencies place a premium on minimizing reputation costs. Conversely, less stable agencies are more likely to accommodate political pressures for forecast optimism. These findings underscore the importance of institutional design for understanding how executive agencies balance the conflicting goals of political responsiveness and bureaucratic competence within the administrative state.
Selbststeuerung und Affektregulation
Authors: Knisel Elke , Ziegler Claudia , Lezinsky Dorota , Strang Hanno
Published: February 2007

Zusammenfassung. Übergewicht und Adipositas zählen heute zu den bedeutendsten Gesundheitsproblemen. Ansatzpunkt in der Therapie von Übergewicht und Adipositas ist das eigenverantwortliche Verändern des Ernährungs- und Bewegungsverhaltens. Ein integrativer Interventionsansatz mit den Bausteinen Bewegungsförderung, Ernährungsberatung und Verhaltenstherapie wird als effektiv im Hinblick auf eine Gewichtsreduktion angesehen. Dieser ist auch die Basis des Interventionsprogramms S.T.E.P.S. (Selbststeuerungs- Trainings- und Ernährungs- Programm mit Spaß) für übergewichtige und adipöse Jugendliche. Das anwendungsbezogene Lernen adäquater Steuermechanismen steht im Mittelpunkt des Interventionsprogramms, dessen Wirkung empirisch untersucht wird. Der Untersuchung liegt ein quasi-experimenteller Untersuchungsplan mit zwei Messzeitpunkten zugrunde. An der Studie nahmen 39 übergewichtige Jugendliche teil. Die Ergebnisse deuten auf eine altersabhängige Wirkung des Interventionsprogramms hin. Bei älteren Jugendlichen zeigen sich signifikante Verbesserungen in der Selbststeuerungsfähigkeit und der Fähigkeit Affekte zu regulieren im Vergleich zu den jüngeren.
Wind control of storm‐triggered shallow landslides
Authors: Rulli M. C. , Meneguzzo F. , Rosso R.
Published: February 2007

Heavy rainstorms are a major control of shallow landsliding in mountainous areas. The influence of three‐dimensional (3‐D) variability of precipitation is analyzed by coupling a fine‐resolution atmospheric model (RAMS) with a fine‐resolution topographic model (DEM) to represent the 3‐D precipitation flux generating the catastrophic flood that occurred in Versilia, central Italy, on 19 June 1996. Matching of this flux with the observed scars and debris shows that 92% of the mass movements occurred where the normalized precipitation flux exceeds 0.80 and less then 2% where this is null. These results give an insight of the detected role of exposure in explaining the spatial variability of observed landslides as emerging from multivariate statistical analysis. The interaction of the wind‐driven precipitation field with topography is an important control of shallow landslides triggered by convective storms in upland catchments.
Characterization of single wall carbon nanotubes by means of rare gas adsorption
Authors: Arab M. , Picaud F. , Ramseyer C. , Babaa M. R. , Valsaque F. , McRae E.
Published: February 2007

Based on the formalisms of Langmuir and Fowler, theoretical adsorption isotherms are calculated for different bundle geometries of single wall carbon nanotubes in a triangular lattice. The authors show the dependence of the adsorption properties on the nanotube diameter and on the specific morphology of the bundles they constitute. The authors demonstrate how isotherm curve analysis can help to experimentally determine what kinds of tubes form a given bundle and the ratio of open to closed tubes in a sample having undergone a complete or incomplete opening protocol. In spite of the model’s simplicity, quite satisfactory agreement is observed between experiments and the authors’ calculations.
Homogeneous nucleation: Classical formulas as asymptotic limits of the Cahn-Hilliard approach
Authors: Parra I. E. , Cordero-Gracia M. , Gómez M.
Published: February 2007

Classical expressions for the critical cluster work of formation approximate the nonclassical expressions based in the density functional theory of capillarity for the limit of low supersaturation degrees. However, the ratio between classical and nonclassical expressions for nucleation rates grows as the supersaturation degree decreases. Here, with the aim to obtain simple and more accurate expressions that approximate the modern nucleation rate formulas, an asymptotic expansion of the Cahn-Hilliard expression of the critical work of formation is developed within the limit of low supersaturation. In such asymptotic expansion, terms up to third order are retained. The ratios between the corrected classical expressions and the nonclassical ones are now decreasing for supersaturation degrees tending to zero. However, the corrected approximate formulas are as difficult to handle as the exact Cahn-Hilliard expressions. When only the two first low-order terms of the asymptotic expansion are retained, a simpler corrected classical expression is obtained but it can only approximate nonclassical expressions up to order unity. Finally, using a Becker-Doring model of nucleation, the kinetic prefactor of the critical nuclei rate of formation is modeled consistently with the Cahn-Hilliard approach to the critical work of formation.
Infrared spectroscopy and photochemistry of NCCN+ and CNCN+ trapped in solid neon
Authors: Jacox Marilyn E. , Thompson Warren E.
Published: February 2007

When a Ne:NCCN sample is codeposited at 4.3K with neon atoms that have been excited in a microwave discharge, the infrared and near infrared spectra of the resulting deposit include a prominent peak at 1799.5cm−1, previously assigned to ν3 of NCCN+, and several new absorptions at higher frequencies which are contributed by combination bands of ground-state NCCN+. The exposure of the deposit to near infrared and red light results in the appearance of two new absorptions which are attributed to CNCN+. The reverse isomerization occurs when the sample is exposed to near ultraviolet radiation, but the two new absorptions are regenerated upon subsequent irradiation with near infrared and red light.
Friction in full view
Authors: Merkle A. P. , Marks L. D.
Published: February 2007

The authors report the direct observation of a single asperity tungsten tip sliding on graphite by in situ transmission electron microscopy (TEM) nanomanipulation. The in situ TEM studies have confirmed that graphitic flakes transfer to a sliding tungsten probe, validating proposed friction mechanisms explaining the unique tribological properties of graphite. Wear of graphite was observed, typically removing sheets of graphite on the order of ten basal planes in thickness. Consistency between wear flake thickness and interfacial dislocation standoff distances is discussed.
Eukaryotic RNase P RNA mediates cleavage in the absence of protein
Authors: Kikovska Ema , Svärd Staffan G. , Kirsebom Leif A.
Published: February 2007

The universally conserved ribonucleoprotein RNase P is involved in the processing of tRNA precursor transcripts. RNase P consists of one RNA and, depending on its origin, a variable number of protein subunits. Catalytic activity of the RNA moiety so far has been demonstrated only for bacterial and some archaeal RNase P RNAs but not for their eukaryotic counterparts. Here, we show that RNase P RNAs from humans and the lower eukaryote
Giardia lamblia
mediate cleavage of four tRNA precursors and a model RNA hairpin loop substrate in the absence of protein. Compared with bacterial RNase P RNA, the rate of cleavage (
k
obs
) was five to six orders of magnitude lower, whereas the affinity for the substrate (app
K
d
) was reduced ≈20- to 50-fold. We conclude that the RNA-based catalytic activity of RNase P has been preserved during evolution. This finding opens previously undescribed ways to study the role of the different proteins subunits of eukaryotic RNase P.
Silencing of estrogen receptor α in the ventromedial nucleus of hypothalamus leads to metabolic syndrome
Authors: Musatov Sergei , Chen Walter , Pfaff Donald W. , Mobbs Charles V. , Yang Xue-Jun , Clegg Deborah J. , Kaplitt Michael G. , Ogawa Sonoko
Published: February 2007

Estrogen receptor α (ERα) plays a pivotal role in the regulation of food intake and energy expenditure by estrogens. Although it is well documented that a disruption of ERα signaling in ERα knockout (ERKO) mice leads to an obese phenotype, the sites of estrogen action and mechanisms underlying this phenomenon are still largely unknown. In the present study, we exploited RNA interference mediated by adeno-associated viral vectors to achieve focused silencing of ERα in the ventromedial nucleus of the hypothalamus, a key center of energy homeostasis. After suppression of ERα expression in this nucleus, female mice and rats developed a phenotype characteristic for metabolic syndrome and marked by obesity, hyperphagia, impaired tolerance to glucose, and reduced energy expenditure. This phenotype persisted despite normal ERα levels elsewhere in the brain. Although an increase in food intake preceded weight gain, our data suggest that a leading factor of obesity in this model is likely a decline in energy expenditure with all three major constituents being affected, including voluntary activity, basal metabolic rate, and diet-induced thermogenesis. Together, these findings indicate that ERα in the ventromedial nucleus of the hypothalamus neurons plays an essential role in the control of energy balance and the maintenance of normal body weight.
Cell stress modulates the function of splicing regulatory protein RBM4 in translation control
Authors: Lin Jung-Chun , Hsu Min , Tarn Woan-Yuh
Published: February 2007

RNA-binding motif protein 4 (RBM4) plays a regulatory role in alternative splicing of precursor mRNA. We show here that cell stress such as arsenite exposure induces phosphorylation of RBM4 at serine 309 and also drives its cytoplasmic accumulation and targeting to stress granule via the MKK
3/6
-p38 signaling pathway. Accordingly, RBM4 suppresses cap-dependent translation in a cis-element-dependent manner. However, RBM4 concomitantly activates internal ribosome entry site (IRES)-mediated translation likely by promoting the association of translation initiation factor eIF4A with IRES-containing mRNAs. Overexpression of RBM4 therefore mimics the effect of cell stress-induced signaling on translation initiation control. Whereas arsenite treatment promotes RBM4 loading onto IRES mRNAs and enhances RBM4–eIF4A interactions, a nonphosphorylatable mutant of RBM4 was unresponsive to arsenite stress and failed to activate IRES-mediated translation. Thus, our results uncover a previously unrecognized paradigm for the RNA-binding protein RBM4 in its phosphorylation-modulated dual action as a suppressor of cap-dependent and enhancer of IRES-mediated translation in response to stress signals.
Characterization of Z-DNA as a nucleosome-boundary element in yeastSaccharomyces cerevisiae
Authors: Wong Ben , Chen Shuai , Kwon Jin-Ah , Rich Alexander
Published: February 2007

In this article, the effect of a d(CG) DNA dinucleotide repeat sequence on RNA polymerase II transcription is examined in yeastSaccharomyces cerevisiae. Our previous report shows that a d(CG)ndinucleotide repeat sequence located proximally upstream of the TATA box enhances transcription from a minimal CYC1 promoter in a manner that depends on its surrounding negative supercoiling. Here, we demonstrate that the d(CG)9repeat sequence stimulates gene activity by forming a Z-DNA secondary structure. Furthermore, the extent of transcriptional enhancement by Z-DNA is promoter-specific and determined by its separation distance relative to the TATA box. The stimulatory effect exerted by promoter proximal Z-DNA is not affected by helical phasing relative to the TATA box, suggesting that Z-DNA effects transcription without interacting with the general transcription machinery by looping-out the intervening DNA. A nucleosome-scanning assay reveals that the d(CG)9repeat sequence in the Z conformation blocks nucleosome formation, and it is found in the linker DNA with two flanking nucleosomes. This result suggests that Z-DNA formation proximally upstream of a promoter is sufficient to demarcate the boundaries of its neighboring nucleosomes, which produces transcriptionally favorable locations for the TATA box near the nucleosomal DNA-entry site and at dyad positions on the nucleosome. These findings suggest that Z-DNA formation in chromatin is a part of the “genomic code” for nucleosome positioningin vivo.
Evolutionary and Neuroscience Approaches to the Study of Cognition
Authors: Schmaus Warren
Published: February 2007

There is a need to bring the work of philosophers such as Millikan who take an evolutionary approach to the study of the mind more in harmony with work in the cognitive neurosciences. Studies of the brain suggest that knowledge in the cortex may be organized by sensory modality-specific properties rather than by hierarchies of substance concepts, regardless of how adaptive Millikan argues the latter would be. Ryder's work on SINBAD networks, which purports to support Millikan's conclusions, does not decide this issue. The ability to make cross-modal identifications of individuals and kinds may be only a recent evolutionary adaptation.
Mathematical Rigor in Physics: Putting Exact Results in Their Place
Authors: Gelfert Axel
Published: February 2007

The present paper examines the role of exact results in the theory of many-body physics, and specifically the example of the Mermin-Wagner theorem, a rigorous result concerning the absence of phase transitions in low-dimensional systems. While the theorem has been shown to hold for a wide range of many-body models, it is frequently ‘violated’ by results derived from the same models using numerical techniques. This raises the question of how scientists regulate their theoretical commitments in such cases, given that the models, too, are often described as approximations to the underlying ‘full’ many-body problem.
Carnap's Metrical Conventionalism versus Differential Topology
Authors: Mormann Thomas
Published: February 2007

Geometry was a main source of inspiration for Carnap's conventionalism. Taking Poincaré as his witness, Carnap asserted in his dissertation Der Raum ([1922] 1978) that the metrical structure of space is conventional while the underlying topological structure describes ‘objective’ facts. With only minor modifications he stuck to this account throughout his life. The aim of this paper is to disprove Carnap's contention by invoking some classical theorems of differential topology. It is shown that his metrical conventionalism is indefensible for mathematical reasons. This implies that the relation between topology and geometry cannot be conceptualized as analogous to the relation between the meaning of a proposition and its expression in some language as the logical empiricists used to say.