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Different Positions (different + position)
Selected AbstractsPhosphonylation of 2-Amino- and 2-Amido-3-bromopyridines and 2-Amino-3-chloroquinoxalines with Triethyl PhosphiteEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 27 2009M. Shaker S. Adam Abstract The Tavs reaction of 2-amino- and 2-acylamido-3-bromopyridines 1 and 2 with triethyl phosphite in the presence of palladium acetate or chloride allows the synthesis of 2-amino- and 2-acylamidopyridine-3-phosphonates 3 and 4. A second ring nitrogen atom causes strong activation and leads to excellent yields in the phosphonylation of 2-amino-3-chloroquinoxalines. 2,3-Dichloroquinoxaline does not need a catalyst and undergoes double phosphonylation with sodium diethyl phosphite under Michaelis,Becker conditions. The results show an activating influence of pyridine nitrogen (,M) and deactivating influence of the amino group (+M). The reactivity of 1 and 2 in the Tavs coupling is compared with that of the 3-NH-2-bromopyridine position isomers and 2-bromoanilines and discussed in terms of the opposite effects of pyridine and amino(amido) nitrogen and different position of the N atoms towards the reaction site. The advantage of the Tavs reaction is the easy optimization because neither auxiliary ligands are required nor a base to trap the halide or a solvent. Triethyl phosphite itself acts as ligand and forms Pd0{P(OEt)3}n in the initial phase of the reaction. The structures of the products and the expected intramolecular N,H···O=P hydrogen bridging bonds were proven by solution NMR and by X-ray crystal structure analysis of single crystalline 3c.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] The constrictor dorsalis musculature and basipterygoid articulation in SphenodonJOURNAL OF MORPHOLOGY, Issue 3 2010Peter JohnstonArticle first published online: 5 OCT 200 Abstract The constrictor internus dorsalis (CID) trigeminal muscles in vertebrates lie between the braincase and the palatoquadrate bar, and in reptiles they are believed to function in the relative movements between braincase and maxillary segment known as kinesis. In amniote taxa, the presence of a synovial basipterygoid articulation (BPA) correlates with presence of the CID. Previous descriptions of the CID in the tuatara Sphenodon (Rhynchocephalia) are inconsistent regarding presence, size and direction, particularly of the m. protractor pterygoidei. The Sphenodon skull is reported to be akinetic. The CID was investigated in Sphenodon by examination of sectioned embryonic and hatchling material, and by dissection of fixed specimens. Osteological correlates of CID muscles and morphology of the BPA were examined on disarticulated skulls and on CT scan images. The vectors of action of these muscles in relation to the BPA were projected onto CT images. Mm. levator bulbi and levator pterygoidei are found to be similar to most previous descriptions, but m. protractor pterygoidei was found in a different position, lying entirely medial to the palatoquadrate bar. The insertions of mm. levator pterygoidei and protractor pterygoidei are visible on the disarticulated pterygoid bone. The BPA is mobile only by rotation around the horizontal axis of the joints themselves; metakinesis is not possible in the Sphenodon skull. M. protractor pterygoidei appears to either resist or recognize lateral displacement of the BPA. M. levator ptergyoidei is placed to resist dorsal displacement of the braincase at the BPA, or torsion of the braincase around its longitudinal axis. The BPA appears to be a means to direct compressive stress via the base of the braincase and occipital condyle to the cervical spine in Sphenodon, and probably in its direct ancestors. Metakinesis may never have been a feature of the lepidosaur skull. J. Morphol., 2010. © 2009 Wiley-Liss, Inc. [source] Effects of Si doping position on the emission energy and recombination dynamics of GaN/AlGaN multiple quantum wellsPHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 1 2006Hamid Haratizadeh Abstract We report results from detailed optical spectroscopy from MOCVD grown GaN/Al0.07Ga0.93N multiple quantum wells (MQWs). Effects of Si doping position on the emission energy and recombination dynamics were studied by means of photoluminescence (PL) and time-resolved PL measurements. The samples were Si doped with the same level but different position of the dopant layer. Only the sample doped in the well shows the MQW emission redshifted compare to the GaN bandgap. The redshift is attributed to the self-energy shift of the electron states due to the correlated motion of the electrons exposed to the fluctuating potential of the donor ions. At low temperature the PL decay time of the sample doped in the well by a factor of two is longer than for the barrier doped case. The difference is explained by the effect of interplay of free carriers and ions on the screening of the polarization field in these doped structures. (© 2006 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Crystal structure of the yeast His6 enzyme suggests a reaction mechanismPROTEIN SCIENCE, Issue 6 2006Sophie Quevillon-Cheruel Abstract The Saccharomycescerevisiae His6 gene codes for the enzyme phosphoribosyl-5-amino-1-phosphoribosyl-4-imidazolecarboxamide isomerase, catalyzing the fourth step in histidine biosynthesis. To get an insight into the structure and function of this enzyme, we determined its X-ray structure at a resolution of 1.30 Å using the anomalous diffraction signal of the protein's sulphur atoms at 1.77 Å wavelength. His6 folds in an (,/,)8 barrel similar to HisA, which performs the same function in bacteria and archaea. We found a citrate molecule from the buffer bound in a pocket near the expected position of the active site and used it to model the open form of the substrate (phosphoribulosyl moiety), which is a reaction intermediate. This model enables us to identify catalytic residues and to propose a reaction mechanism where two aspartates act as acid/base catalysts: Asp134 as a proton donor for ring opening, and Asp9 as a proton acceptor and donor during enolization of the aminoaldose. Asp9 is conserved in yeast His6 and bacterial or archaeal HisA sequences, and Asp134 has equivalents in both HisA and TrpF, but they occur at a different position in the protein sequence. [source] Rapid differentiation of isobaric and positional isomers of structurally related glycosides from Phytolacca bogotensisRAPID COMMUNICATIONS IN MASS SPECTROMETRY, Issue 21 2009Guillermo Montoya Through the action of glycosyltransferases, a plant can biosynthetically assemble small different aglycons or 'templates' to various polysaccharides to produce numerous glycoconjugates differing in the type of the attached aglycon, the anomeric configuration of C-1 of the glycosylating sugar, the type of sugar and the different position of attachments of the sugar unit present in the polysaccharide chain. The position of attachments and the anomeric configuration of the different sugar present in the polysaccharide create the opportunity to generate molecules with either the same or very close molecular weights, which have relative structural similarity , forming isobaric and positional isomers. Although isomeric differentiation was once considered outside of the domain of mass spectrometry, this task can now be resolved using tandem mass spectrometry. In a standardized purified glycoconjugate fraction (SPT01) from Phytolacca bogotensis, we report conventional electrospray ionization mass spectrometry and collision-induced dissociation (CID) MS/MS parameters which favored the formation of characteristic product ions. This allowed us to suggest the type of sugar linkages present in a specific glycoconjugate. Ten new glycoconjugate are described from this plant and another twelve known saponins were structurally characterized using the automatic MSn acquisition mode. The differentiation of two pairs of positional isomers and four isobaric glycosides and the production of a library of 30 glycosides present in P. bogotensis were accomplished. Copyright © 2009 John Wiley & Sons, Ltd. [source] Ln3M1,,,,TX7, quasi-isostructural compounds: stereochemistry and silver-ion motion in the Ln3Ag1,,,,GeS7 (Ln = La,Nd, Sm, Gd,Er and Y; , = 0.11,0.50) compoundsACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2009Marek Daszkiewicz The crystal structures of the Ln3Ag1,,,,GeS7 (Ln = La,Nd, Sm, Gd,Er, Y; , = 0.11,0.50, space group P63) compounds were determined by means of X-ray single-crystal diffraction and the similarities among the crystal structures of all Ln3M1,,,,TX7 (space group P63; Ln , lanthanide element, M, monovalent element; T, tetravalent element and X, S, Se) compounds deposited in the Inorganic Crystal Structure Database (ICSD) are discussed. Substitutions of each element in Ln3M1,,,,TX7 result in a different structural effect. On the basis of the data deposited in the ICSD the large family of the Ln3M1,,,,TX7 compounds was divided into three groups depending on the position of the monovalent element in the lattice. This position determines what kind of stereoisomer is present in the structure, either the ++ enantiomer or the +, diastereoisomer. Since the silver ions can occupy a different position and the energy barriers between positions are low the ions can move through the channel. It was shown that this movement is not a stochastic process but a correlated one. [source] Numerical investigation of heat transport and fluid flow during the seeding process of oxide Czochralski crystal growth Part 1: non-rotating seedCRYSTAL RESEARCH AND TECHNOLOGY, Issue 6 2007M. H. Tavakoli Abstract For the seeding process of oxide Czochralski crystal growth, the flow and temperature field of the system as well as the seed-melt interface shape have been studied numerically using the finite element method. The configuration usually used initially in a real Czochralski crystal growth process consists of a crucible, active afterheater, induction coil with two parts, insulation, melt, gas and non-rotating seed crystal. At first the volumetric distribution of heat inside the metal crucible and afterheater inducted by the RF coil was calculated. Using this heat source the fluid flow and temperature field were determined in the whole system. We have considered two cases with respect to the seed position: (1) before and (2) after seed touch with the melt. It was observed that in the case of no seed rotation (,seed = 0), the flow pattern in the bulk melt consists of a single circulation of a slow moving fluid. In the gas domain, there are different types of flow motion related to different positions of the seed crystal. In the case of touched seed, the seed-melt interface has a deep conic shape towards the melt. It was shown that an active afterheater and its location with respect to the crucible, influences markedly the temperature and flow field of the gas phase in the system and partly in the melt. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Using generalized dissimilarity modelling to analyse and predict patterns of beta diversity in regional biodiversity assessmentDIVERSITY AND DISTRIBUTIONS, Issue 3 2007Simon Ferrier ABSTRACT Generalized dissimilarity modelling (GDM) is a statistical technique for analysing and predicting spatial patterns of turnover in community composition (beta diversity) across large regions. The approach is an extension of matrix regression, designed specifically to accommodate two types of nonlinearity commonly encountered in large-scaled ecological data sets: (1) the curvilinear relationship between increasing ecological distance, and observed compositional dissimilarity, between sites; and (2) the variation in the rate of compositional turnover at different positions along environmental gradients. GDM can be further adapted to accommodate special types of biological and environmental data including, for example, information on phylogenetic relationships between species and information on barriers to dispersal between geographical locations. The approach can be applied to a wide range of assessment activities including visualization of spatial patterns in community composition, constrained environmental classification, distributional modelling of species or community types, survey gap analysis, conservation assessment, and climate-change impact assessment. [source] Jungle Law in the Orchard: Comparing Globalization in the New Zealand and Chilean Apple IndustriesECONOMIC GEOGRAPHY, Issue 4 2002Megan K. L. McKenna Abstract: Restructuring in the global apple market is leading to a pronounced tightening in the competitive spaces occupied by Southern Hemisphere producers. For New Zealand and Chile, the world's two most successful apple-exporting countries, significant challenges are presented by projected industry trends, such as declining profitability in the global industry, increased world production, and the continued static demand in key markets. In particular, falling prices in Europe and North America for many key varieties and concomitant lower returns to growers are threatening serious and pervasive impacts. This article explores some of these challenges in the context of the significantly different positions occupied by New Zealand and Chile within the global fresh fruit and vegetable complex. An analysis of the two countries' industries, particularly comparing issues of regulation and innovative varietal development, shows that global food complexes have highly variable spatial expressions, given their process-based nature and underlying dynamics of contestation. Focusing on the increased competition between the New Zealand and Chilean apple industries, the discussion sheds light on wider emerging competitive dynamics within the global fruit industry. The example of the recent Pacific Rose crisis, which involved Chilean "theft" of an exclusive New Zealand apple variety, is used to illustrate the emergence of "jungle law" in the Southern Hemisphere apple industries. [source] Copper Ion Selective Membrane Electrodes Based on Some Schiff Base DerivativesELECTROANALYSIS, Issue 15-16 2003S. Sadeghi Abstract A series of Schiff base derivatives were studied to characterize their abilities as a copper ion carrier in PVC membrane electrodes. The electrode based on 2,2,-[4,4,diphenyl-methanebis(nitrilomethylidyne)]-bisphenol exhibits a Nernstian response for copper ions over the activity range 8.0×10,6,1.0×10,1 mol L,1 with detection limit of about , mol L,1 of copper ion in comparison with two other Schiff bases. The response time, pH effect and other characteristics of the electrodes were studied in a static mode. The effect of the methyl group substitute on Schiff base structure with SO2 bridging group in different positions with respect to OH group was studied. The results show that behavior of the electrodes is not considerably influenced by the position of methyl substitute. The selectivity coefficients were determined with modified fixed interference method (FIM) and matched potential method (MPM). The proposed electrodes comparatively show good selectivity with respect to alkali, alkaline earth and some transition metal ions. The electrodes were used for the determination of copper in black tea, multivitamin and mineral capsule and as an indicator electrode in potentiometric titration of copper ion. [source] Influence of the position of the foot on MRI signal in the deep digital flexor tendon and collateral ligaments of the distal interphalangeal joint in the standing horseEQUINE VETERINARY JOURNAL, Issue 5 2009M. SPRIET Summary Reasons for performing study: Hyperintense signal is sometimes observed in ligaments and tendons of the equine foot on standing magnetic resonance examination without associated changes in size and shape. In such cases, the presence of a true lesion or an artifact should be considered. A change in position of a ligament or tendon relative to the magnetic field can induce increased signal intensity due to the magic angle effect. Objectives: To assess if positional rotation of the foot in the solar plane could be responsible for artifactual changes in signal intensity in the collateral ligaments of the distal interphalangeal joint and in the deep digital flexor tendon. Methods: Six isolated equine feet were imaged with a standing equine magnetic resonance system in 9 different positions with different degrees of rotation in the solar plane. Results: Rotation of the limb induced a linear hyperintense signal on all feet at the palmar aspect of one of the lobes of the deep digital flexor tendon and at the dorsal aspect of the other lobe. Changes in signal intensity in the collateral ligaments of the distal interphalangeal joint occurred with rotation of the limb only in those feet where mediolateral hoof imbalance was present. Conclusions: The position and conformation of the foot influence the signal intensity in the deep digital flexor tendon and in the collateral ligaments of the distal interphalangeal joint. Potential relevance: The significance of increased signal intensity in the deep digital flexor tendon and in the collateral ligaments of the distal interphalangeal joint should be interpreted with regard to the position and the conformation of the foot. [source] Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristicsEQUINE VETERINARY JOURNAL, Issue 7 2008V. RAKESH Summary Reason for performing study: The necessary degree of arytenoid cartilage abduction (ACA) to restore airway patency at maximal exercise has not been determined. Objectives: Use computational fluid dynamics modelling to measure the effects of different degrees of ACA on upper airway characteristics of horses during exercise. Hypothesis: Maximal ACA by laryngoplasty is necessary to restore normal peak airflow and pressure in Thoroughbred racehorses with laryngeal hemiplegia. Methods: The upper airway was modeled with the left arytenoid in 3 different positions: maximal abduction; 88% cross-sectional area of the rima glottis; and 75% cross-sectional area of the rima glottis. The right arytenoid cartilage was maximally abducted. Two models were assumed: Model 1: no compensation of airway pressures; and Model 2: airway pressure compensation occurs to maintain peak airflow. The cross-sectional pressure and velocity distributions for turbulent flow were studied at peak flow and at different positions along the airway. Results: Model 1: In the absence of a change in driving pressure, 12 and 25% reductions in cross-sectional area of the larynx resulted in 4.11 and 5.65% reductions in peak airflow and 3.68 and 5.64% in tidal volume, respectively, with mild changes in wall pressure. Model 2: To maintain peak flow, a 6.27% increase in driving tracheal pressure was required to compensate for a cross-sectional reduction of 12% and a 13.63% increase in driving tracheal pressure was needed for a cross-sectional area reduction of 25%. This increase in negative driving pressure resulted in regions with low intraluminal and wall pressures, depending on the degree of airway diameter reduction. Conclusion: Assuming no increase in driving pressure, the decrease in left ACA reduced airflow and tidal volume. With increasing driving pressure, a decrease in left ACA changed the wall pressure profile, subjecting the submaximally abducted arytenoid cartilage and adjacent areas to airway collapse. Clinical relevance: The surgical target of ACA resulting in 88% of maximal cross-sectional area seems to be appropriate. [source] Seasonally Variable Eusocially Selected Traits in the Paper Wasp, Mischocyttarus mexicanusETHOLOGY, Issue 7 2007Charles W. Gunnels IV The expression of alternative traits that benefit eusocial individuals but are not directly involved in reproductive differences among those individuals, which I call ,eusocially selected traits', may vary in response to environmental changes if this increases an individual's inclusive fitness. In this study, I describe traits that separate individuals within the reproductive division of labor of Mischocyttarus mexicanus, a eusocial paper wasp, and determine whether observed eusocially selected traits vary across seasons. I examined M. mexicanus because females initiate new nests throughout most of the year where they experience different conditions depending on the season. Findings from this study suggest two main conclusions: (1) phenotypic differences among M. mexicanus females are mixed, showing specialized, generalized, and context-dependent eusocially selected traits and (2) a female's position within the reproductive division of labor may be influenced by its state. The presence of context-dependent traits, e.g. large females initiated solitary nests in the spring and grouped nests during the summer, suggests that the payoff for pursuing different positions within the reproductive division of labor changes across seasons. The expression of context-dependent eusocially selected traits also suggests that, roles, instead of castes, may better reflect the reproductive division of labor among individuals of eusocial species like M. mexicanus. [source] An Approach to the Synthesis of Silicon Carbide Nanowires by Simple Thermal Evaporation of Ferrocene onto Silicon WafersEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 25 2007Jun-Jie Niu Abstract Scales of silicon carbide nanowires (SiC-NWs) with high quality were synthesized by direct thermal evaporation of ferrocene onto silicon wafers at high temperature. Ferrocene decomposed into iron and carbon, which was subsequently treated with silicon to form SiC-NWs at high temperature. The SiC-NWs possess small diameters of , 20 nm and lengths of several ,ms. Furthermore, the samples show a uniform morphology, crystalline structure, and a very thin oxide layer. The main crystal direction of [111] was confirmed by high-resolution field-emission-transmission electron microscopy (HR-FETEM). The Raman scattering spectra showed two peaks at , 796 (TO) and , 980 cm,1 (LO) with varying intensity ratios at different positions. The band line fluctuation was contributed to the Raman selection rules. With reference to the experimental results, we suggested a tentative growth model according to the vapor,liquid,solid (VLS) mechanism. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007) [source] Topographic distribution of direct and hippocampus- mediated entorhinal cortex activity evoked by olfactory tract stimulationEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 7 2004Vadym Gnatkovsky Abstract Olfactory information is central for memory-related functions, such as recognition and spatial orientation. To understand the role of olfaction in learning and memory, the distribution and propagation of olfactory tract-driven activity in the parahippocampal region needs to be characterized. We recently demonstrated that repetitive stimulation of the olfactory tract in the isolated guinea pig brain preparation induces an early direct activation of the rostrolateral entorhinal region followed by a delayed response in the medial entorhinal cortex (EC), preceded by the interposed activation of the hippocampus. In the present study we performed a detailed topographic analysis of both the early and the delayed entorhinal responses induced by patterned stimulation of the lateral olfactory tract in the isolated guinea pig brain. Bi-dimensional maps of EC activity recorded at 128 recording sites with 4 × 4 matrix electrodes (410 µm interlead separation) sequentially placed in eight different positions, showed (i) an early (onset at 16.09 ± 1.2 ms) low amplitude potential mediated by the monosynaptic LOT input, followed by (ii) an associative potential in the rostral EC which originates from the piriform cortex (onset at 33.2 ± 2.3 ms), and (iii) a delayed potential dependent on the previous activation of the hippocampus. The sharp component of the delayed response had an onset latency between 52 and 63 ms and was followed by a slow wave. Laminar profile analysis demonstrated that in the caudomedial EC the delayed response was associated with two distinct current sinks located in deep and in superficial layers, whereas in the rostrolateral EC a small-amplitude sink could be detected in the superficial layers exclusively. The present report demonstrates that the output generated by the hippocampal activation is unevenly distributed across different EC subregions and indicates that exclusively the medial and caudal divisions receive a deep-layer input from the hippocampus. In the rostrolateral EC, specific network interactions may be generated by the convergence of the direct olfactory input and the olfaction-driven hippocampal output. [source] Synthesis of New Thiophene-Substituted 3,3-Diphenyl-3H -naphtho[2,1- b]pyrans by Cross-Coupling Reactions, Precursors of Photomodulated MaterialsEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 15 2003Michel Frigoli Abstract 3,3-Diphenyl-3H -naphtho[2,1- b]pyrans linked to one, two, or three thiophene nuclei in different positions of the naphthalene moiety (5, 6, 8, and 9) by a covalent bond have been prepared in good yields. A Suzuki cross-coupling reaction was used with two possible strategies: chromenization before the coupling with oligothiophenes or chromenization after the coupling, the main intermediates being the diphenyl propargylic alcohol, the functionalized naphthol derivatives, and the thiophenic boronates. The overall yields for obtaining such photochromic compounds are generally quite satisfying. For the 7-position, the coupling reaction has been realized using a Grignard reaction between a tetralone derivative and a thiophenic bromo magnesium intermediate. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Microstructure Evolution and Mechanical Properties of Linear Friction Welded 45 Steel JointADVANCED ENGINEERING MATERIALS, Issue 8 2007J. Ma Linear friction welding (LFW) is an emerging solid-state joining process to extend the current applications of welding. The microstructure evolution and mechanical properties of LFW 45 steel joint were investigated. The microstructures from the weld center to the parent metal were the superfine ferrite+pearlite in the weld center, the deformed fine ferrite + pearlite in the thermomechanically affected zone, the tempered sorbite, troosite and martensite in the heat affected zone. The microhardness of the joint decreased gradually from the parent metal to the weld center. The tensile properties of the joint were significantly improved in both the strength and ductility. The microstructure evolution, microhardness variation and fracture position are attributed to the various thermal histories of different positions. [source] The dynamics of developmental system drift in the gene network underlying wing polyphenism in ants: a mathematical modelEVOLUTION AND DEVELOPMENT, Issue 3 2008Marcos Nahmad SUMMARY Understanding the complex interaction between genotype and phenotype is a major challenge of Evolutionary Developmental Biology. One important facet of this complex interaction has been called "Developmental System Drift" (DSD). DSD occurs when a similar phenotype, which is homologous across a group of related species, is produced by different genes or gene expression patterns in each of these related species. We constructed a mathematical model to explore the developmental and evolutionary dynamics of DSD in the gene network underlying wing polyphenism in ants. Wing polyphenism in ants is the ability of an embryo to develop into a winged queen or a wingless worker in response to an environmental cue. Although wing polyphenism is homologous across all ants, the gene network that underlies wing polyphenism has evolved. In winged ant castes, our simulations reproduced the conserved gene expression patterns observed in the network that controls wing development in holometabolous insects. In wingless ant castes, we simulated the suppression of wings by interrupting (up- or downregulating) the expression of genes in the network. Our simulations uncovered the existence of four groups of genes that have similar effects on target gene expression and growth. Although each group is comprised of genes occupying different positions in the network, their interruption produces vestigial discs that are similar in size and shape. The implications of our results for understanding the origin, evolution, and dissociation of the gene network underlying wing polyphenism in ants are discussed. [source] Nuclear factor TDP-43 can affect selected microRNA levelsFEBS JOURNAL, Issue 10 2010Emanuele Buratti TDP-43 has recently been described as the major component of the inclusions found in the brain of patients with a variety of neurodegenerative diseases, such as frontotemporal lobar degeneration and amyotrophic lateral sclerosis. TDP-43 is a ubiquitous protein whose specific functions are probably crucial to establishing its pathogenic role. Apart from its involvement in transcription, splicing and mRNA stability, TDP-43 has also been described as a Drosha-associated protein. However, our knowledge of the role of TDP-43 in the microRNA (miRNA) synthesis pathway is limited to the association mentioned above. Here we report for the first time which changes occur in the total miRNA population following TDP-43 knockdown in culture cells. In particular, we have observed that let-7b and miR-663 expression levels are down- and upregulated, respectively. Interestingly, both miRNAs are capable of binding directly to TDP-43 in different positions: within the miRNA sequence itself (let-7b) or in the hairpin precursor (miR-663). Using microarray data and real-time PCR we have also identified several candidate transcripts whose expression levels are selectively affected by these TDP-43,miRNA interactions. [source] Altering the surface properties of baculovirus Autographa californica NPV by insertional mutagenesis of the envelope protein gp64FEBS JOURNAL, Issue 18 2002Alexandra Spenger The envelope protein gp64 of the baculovirus Autographa californica nuclear polyhedrosis virus is essential for viral entry into insect cells, as the glycoprotein both mediates pH-dependent membrane fusion and binds to host cell receptors. Surface modification of baculovirus particles by genetic engineering of gp64 has been demonstrated by various strategies and thus has become an important and powerful tool in molecular biology. To improve further the presentation of peptides on the surface of baculovirus particles, several insertion sites within the gp64 envelope protein were selected by their theoretical maximum surface probability and investigated for efficient peptide presentation. The ELDKWA peptide of the gp41 of HIV-1, specific for the human mAb 2F5, was inserted into 17 different positions of the glycoprotein gp64. Propagation of viruses was successful in 13 cases, mutagenesis at four positions did not result in production of intact virus particles. Western blotting, FACS analysis and ELISA were used for characterization of the different binding properties of the mutants. Insertion of this peptide into the native envelope protein resulted in high avidity display on the surface of baculovirus particles. This approach offers the possibility of effective modification of surface properties in regard to host range specificity and antigen display. [source] Characterization of yeast strains by fluorescence lifetime imaging microscopyFEMS YEAST RESEARCH, Issue 1 2008Hemant Bhatta Abstract The results of fluorescence lifetime imaging microscopy of selected yeast strains were presented and the fact that the lifetime distributions can be successfully used for strain characterization and differentiation was demonstrated. Four strains of industrially relevant yeast Saccharomyces were excited at 405 nm and the autofluorescence observed within 440,540 nm. Using statistical tools such as empirical cumulative distribution functions with Kolmogorov,Smirnov testing, the four studied strains were categorized into three different groups for normal sample size of 70 cells slide,1 at a significance level of 5%. The differentiation of all of the examined strains from one another was shown to be possible by increasing the sample size to 420 cells, which is achievable by taking the lifetime data at six different positions in the slide. [source] The interaction between ,S, the stationary phase , factor, and the core enzyme of Escherichia coli RNA polymeraseGENES TO CELLS, Issue 3 2002Frédéric Colland Background: The RNA polymerase holoenzyme of Escherichia coli is composed of a core enzyme (subunit structure ,2,,,) associated with one of the , subunits, required for promoter recognition. Different , factors compete for core binding. Among the seven , factors present in E. coli, ,70 controls gene transcription during the exponential phase, whereas ,S regulates the transcription of genes in the stationary phase or in response to different stresses. Using labelled ,S and ,70, we compared the affinities of both , factors for core binding and investigated the structural changes in the different subunits involved in the formation of the holoenzymes. Results: Using native polyacrylamide gel electrophoresis, we demonstrate that ,S binds to the core enzyme with fivefold reduced affinity compared to ,70. Using iron chelate protein footprinting, we show that the core enzyme significantly reduces polypeptide backbone solvent accessibility in regions 1.1, 2.5, 3.1 and 3.2 of ,S, while increasing the accessibility in region 4.1 of ,S. We have also analysed the positioning of ,S on the holoenzyme by the proximity-dependent protein cleavage method using ,S derivatives in which FeBABE was tethered to single cysteine residues at nine different positions. Protein cutting patterns are observed on the , and ,, subunits, but not ,. Regions 2.5, 3.1 and 3.2 of ,S are close to both , and ,, subunits, in agreement with iron chelate protein footprinting data. Conclusions: A comparison between these results using ,S and previous data from ,70 indicates similar contact patterns on the core subunits and similar characteristic changes associated with holoenzyme formation, despite striking differences in the accessibility of regions 4.1 and 4.2. [source] Operator-oriented CRS interpolationGEOPHYSICAL PROSPECTING, Issue 6 2009German Hoecht ABSTRACT In common-reflection-surface imaging the reflection arrival time field is parameterized by operators that are of higher dimension or order than in conventional methods. Using the common-reflection-surface approach locally in the unmigrated prestack data domain opens a potential for trace regularization and interpolation. In most data interpolation methods based on local coherency estimation, a single operator is designed for a target sample and the output amplitude is defined as a weighted average along the operator. This approach may fail in presence of interfering events or strong amplitude and phase variations. In this paper we introduce an alternative scheme in which there is no need for an operator to be defined at the target sample itself. Instead, the amplitude at a target sample is constructed from multiple operators estimated at different positions. In this case one operator may contribute to the construction of several target samples. Vice versa, a target sample might receive contributions from different operators. Operators are determined on a grid which can be sparser than the output grid. This allows to dramatically decrease the computational costs. In addition, the use of multiple operators for a single target sample stabilizes the interpolation results and implicitly allows several contributions in case of interfering events. Due to the considerable computational expense, common-reflection-surface interpolation is limited to work in subsets of the prestack data. We present the general workflow of a common-reflection-surface-based regularization/interpolation for 3D data volumes. This workflow has been applied to an OBC common-receiver volume and binned common-offset subsets of a 3D marine data set. The impact of a common-reflection-surface regularization is demonstrated by means of a subsequent time migration. In comparison to the time migrations of the original and DMO-interpolated data, the results show particular improvements in view of the continuity of reflections events. This gain is confirmed by an automatic picking of a horizon in the stacked time migrations. [source] Managing the Bank-System Crisis in Coordinated Market Economies: Institutions and Blame Avoidance Strategies in Sweden and JapanGOVERNANCE, Issue 1 2006TORSTEN SVENSSON Sweden and Japan represent two different positions regarding policymaking when faced with similar crises of the bank systems. Different institutional settings led the main actors to different paths of reactions in order to avoid blame. In the Japanese case, the very close relationship between private banks and the Ministry of Finance, in combination with the lesser degree of widespread perceptions of a system crisis, made it more urgent as well as possible to conceal the actual state of affairs for the politicians. Confronted with the threat of losing power over the financial administration to a new agency, the ministry postponed the reforms in order to conceal the deep financial problems. The institutional setting was different in Sweden. Deregulation had separated the government from the administration of banks. Among the public deteriorating economic conditions were easily connected to the banks. This brought about political unity. It was possible to put the blame on the banks and take the credit for the efforts to tidy up the mess without losing credibility. [source] Soil water content and yield variability in vineyards of Mediterranean northeastern Spain affected by mechanization and climate variabilityHYDROLOGICAL PROCESSES, Issue 11 2006M. C. Ramos Abstract The objective of this paper was to analyse the combined influence of the Mediterranean climate variability (particularly the irregular rainfall distribution throughout the year) and the land transformations carried out in vineyards of northeastern Spain on soil water content evolution and its influence on grape production. The study was carried out in a commercial vineyard located in the Anoia,Alt Penedès region (Barcelona province, northeastern Spain), which was prepared for mechanization with important land transformations. Two plots were selected for the study: one with low degree of transformation of the soil profile, representing a non-disturbed situation, and the second one in which more than 3 m were cut in the upper part of the plot and filled in the lower part, representing the disturbed situation. Soil water content was evaluated at three positions along the slope in each plot and at three depths (0,20, 20,40, 40,60 cm) during the period 1999,2001, years with different rainfall characteristics, including extreme events and long dry periods. Rainfall was recorded in the experimental field using a pluviometer linked to a data-logger. Runoff rates and yield were evaluated at the same positions. For the same annual rainfall, the season of the year in which rainfall is recorded and its intensity are critical for water availability for crops. Soil water content varies within the plot and is related to the soil characteristics existing at the different positions of the landscape. The differences in soil depth created by soil movements in the field mechanization give rise to significant yield reductions (up to 50%) between deeper and shallow areas. In addition, for the same annual rainfall, water availability for crops depends on its distribution over the year, particularly in soils with low water-storage capacity. The yield was strongly affected in years with dry or very dry winters. Copyright © 2005 John Wiley & Sons, Ltd. [source] Suspended sediment concentration and the ripple,dune transitionHYDROLOGICAL PROCESSES, Issue 17 2004Robert J. Schindler Abstract Flume experiments were conducted in order to monitor changes in flow turbulence intensity and suspended sediment concentration at seven stages across the ripple,dune transition and at three different positions above the bed surface. Three-dimensional velocity measurements were obtained using an acoustic Doppler velocimeter (ADV). Suspended sediment concentration (SSC) was monitored indirectly using ADV signal amplitude. Although limited to time-averaged parameters, the analysis reveals that SSC varies significantly with stage across the transition and with sampling height. The statistical analysis also reveals an apparent uniformity of suspended sediment concentration with height above the bed in the lower half of the flow depth at the critical stage in the transition from ripples to dunes. This is also the stage at which turbulence intensity is maximized. Statistically significant correlations were also observed between suspended sediment concentrations and root-mean-square values of vertical velocity fluctuations. These correlations reflect the various levels of shear-layer activity and the distinct turbulent flow regions across the transition. Conversely, time-averaged values of Reynolds shear stress exhibit a very weak relationship with suspended sediment concentrations. Copyright © 2004 John Wiley & Sons, Ltd. [source] The Debate on Globalization, Poverty and Inequality: Why Measurement MattersINTERNATIONAL AFFAIRS, Issue 4 2003Martin Ravallion In the last year or so, markedly different claims have been heard within the development community about just how much progress is being made against poverty and inequality in the current period of ,globalization'. This article provides a non-technical overview of the conceptual and methodological issues underlying these conflicting claims. It argues that the dramatically different positions taken in this debate often stem from differences in the concepts and definitions used and differences in data sources and measurement assumptions. These differences are often hidden from view in the debate, but they need to be considered carefully if one is properly to interpret the evidence. The article argues that the best available evidence suggests that, if the rate of progress against absolute poverty in the developing world in the 1990s is maintained, then the Millennium Development Goal of halving the 1990 aggregate poverty rate by 2015 will be achieved on time in the aggregate, though not in all regions. The article concludes with some observations on the implications for policy-oriented debates on globalization and pro-poor growth. [source] Body positions and esophageal sphincter pressures in obese patients during anesthesiaACTA ANAESTHESIOLOGICA SCANDINAVICA, Issue 4 2010A. DE LEON Background: The lower esophageal sphincter (LES) and the upper esophageal sphincter (UES) play a central role in preventing regurgitation and aspiration. The aim of the present study was to evaluate the UES, LES and barrier pressures (BP) in obese patients before and during anesthesia in different body positions. Methods: Using high-resolution solid-state manometry, we studied 17 patients (27,63 years) with a BMI,35 kg/m2 who were undergoing a laparoscopic bariatric surgery before and after anesthesia induction. Before anesthesia, the subjects were placed in the supine position, in the reverse Trendelenburg position (+20°) and in the Trendelenburg position (,20°). Thereafter, anesthesia was induced with remifentanil and propofol and maintained with remifentanil and sevoflurane, and the recordings in the different positions were repeated. Results: Before anesthesia, there were no differences in UES pressure in the different positions but compared with the other positions, it increased during the reverse Trendelenburg during anesthesia. LES pressure decreased in all body positions during anesthesia. The LES pressure increased during the Trendelenburg position before but not during anesthesia. The BP remained positive in all body positions both before and during anesthesia. Conclusion: LES pressure increased during the Trendelenburg position before anesthesia. This effect was abolished during anesthesia. LES and BPs decreased during anesthesia but remained positive in all patients regardless of the body position. [source] Selection of locations of knots for linear splines in random regression test-day modelsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 2 2010J. Jamrozik Summary Using spline functions (segmented polynomials) in regression models requires the knowledge of the location of the knots. Knots are the points at which independent linear segments are connected. Optimal positions of knots for linear splines of different orders were determined in this study for different scenarios, using existing estimates of covariance functions and an optimization algorithm. The traits considered were test-day milk, fat and protein yields, and somatic cell score (SCS) in the first three lactations of Canadian Holsteins. Two ranges of days in milk (from 5 to 305 and from 5 to 365) were taken into account. In addition, four different populations of Holstein cows, from Australia, Canada, Italy and New Zealand, were examined with respect to first lactation (305 days) milk only. The estimates of genetic and permanent environmental covariance functions were based on single- and multiple-trait test-day models, with Legendre polynomials of order 4 as random regressions. A differential evolution algorithm was applied to find the best location of knots for splines of orders 4 to 7 and the criterion for optimization was the goodness-of-fit of the spline covariance function. Results indicated that the optimal position of knots for linear splines differed between genetic and permanent environmental effects, as well as between traits and lactations. Different populations also exhibited different patterns of optimal knot locations. With linear splines, different positions of knots should therefore be used for different effects and traits in random regression test-day models when analysing milk production traits. [source] Regional climate modulates the canopy mosaic of favourable and risky microclimates for insectsJOURNAL OF ANIMAL ECOLOGY, Issue 3 2007SYLVAIN PINCEBOURDE Summary 1,One major gap in our ability to predict the impacts of climate change is a quantitative analysis of temperatures experienced by organisms under natural conditions. We developed a framework to describe and quantify the impacts of local climate on the mosaic of microclimates and physiological states of insects within tree canopies. This approach was applied to a leaf mining moth feeding on apple leaf tissues. 2,Canopy geometry was explicitly considered by mapping the 3D position and orientation of more than 26 000 leaves in an apple tree. Four published models for canopy radiation interception, energy budget of leaves and mines, body temperature and developmental rate of the leaf miner were integrated. Model predictions were compared with actual microclimate temperatures. The biophysical model accurately predicted temperature within mines at different positions within the tree crown. 3,Field temperature measurements indicated that leaf and mine temperature patterns differ according to the regional climatic conditions (cloudy or sunny) and depending on their location within the canopy. Mines in the sun can be warmer than those in the shade by several degrees and the heterogeneity of mine temperature was incremented by 120%, compared with that of leaf temperature. 4.,The integrated model was used to explore the impact of both warm and exceptionally hot climatic conditions recorded during a heat wave on the microclimate heterogeneity at canopy scale. During warm conditions, larvae in sunlight-exposed mines experienced nearly optimal growth conditions compared with those within shaded mines. The developmental rate was increased by almost 50% in the sunny microhabitat compared with the shaded location. Larvae, however, experienced optimal temperatures for their development inside shaded mines during extreme climatic conditions, whereas larvae in exposed mines were overheating, leading to major risks of mortality. 5,Tree canopies act as both magnifiers and reducers of the climatic regime experienced in open air outside canopies. Favourable and risky spots within the canopy do change as a function of the climatic conditions at the regional scale. The shifting nature of the mosaic of suitable and risky habitats may explain the observed uniform distribution of leaf miners within tree canopies. [source] | |||||||||||||||||||||||||||||||||||||||||||