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Selected AbstractsCleavage-like cell division and explosive increase in cell number of neonatal gonocytesDEVELOPMENT GROWTH & DIFFERENTIATION, Issue 1 2004Yasuhiro Sakai Based on previous conventional quantitative observations of rat testes, it was proposed that large numbers of gonocytes degenerate after birth and this notion was widely accepted. However, many studies show that neonatal gonocytes display high levels of mitotic activity. In order to resolve the apparent contradiction of increased mitotic activity in gonocytes despite a decrease in their numbers at the neonate stage, quantitative analysis using a marker of suitably higher resolution is required. It has been shown that the vasa protein could be used as a marker of germ cells. In this study, quantitative changes in gonocytes were re-examined using a germ-cell-specific marker in order to delineate more clearly the process of development from gonocytes to spermatogonia after birth. The vasa -positive cells, which correspond to gonocytes and spermatogonia, increased exponentially after birth. This observation suggests that all gonocyte divide actively after birth and do not degenerate as previously believed. Surprisingly, the cell volume of gonocytes decreased during their division. The largest population size was 2000,4000 µ3 at day 2, 1000,2000 µ3 at day 4 and 500,1000 µ3 at day 6. This finding suggests that gonocytes divide in a similar way to cleavage, which can be considered a special mode of fertilized eggs. Judging from the growth of seminiferous tubules and the degree of volume reduction, 60% of the contribution rate is estimated to be due to ordinal cell growth, and 40% due to volume reduction as in cleavage of a fertilized egg. This unique cleavage-like division may contribute to the supply of large numbers of spermatogonia. [source] Biotic ligand model of the acute toxicity of metals.ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 10 2001Abstract The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal,biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal,DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount. [source] Aminoethyl-Functionalized Cyclopentadienyliridium Complexes: Photochemical C,H Activation and Carbonylation of CycloalkanesEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 8 2006Pek Ke Chan Abstract The photochemical C,H activation of cycloalkanes by aminoethyl-functionalized cyclopentadienyliridium complexes proceeds in a broadly similar way to that for their unfunctionalized analogues. In a carbon monoxide atmosphere, there is evidence that carbonylation to form the carboxaldehyde occurred with both systems. In situ infrared spectroscopic studies on these reactions allow the identification of several species present in low concentrations in the reaction mixture. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Synthesis of a Hexadentate Hexameric Aluminum Imide and Its Metathesis ReactionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003N. Dastagiri Reddy Abstract The reaction of AlH3·NMe3 with one equivalent of 2-cyanothiophene in toluene afforded [HAlNCH2(C4H3S)]6 (2) in good yield. Treatment of 2 with SiMe3Br and SiMe3Cl in toluene under refluxing conditions resulted in the formation of compounds [BrAlNCH2(C4H3S)]6 (3) and [ClAlNCH2(C4H3S)]6 (4), respectively. In a similar way [PhC,CAlNCH2(C4H3S)]6 (5) was readily obtained from the reaction between 2 and PhC,CH. When 2 was treated with PhSH the Al-N cluster core dissociated and a four-membered ring compound [(PhS)2AlNHCH2(C4H3S)]2 (6) was formed. In contrast, a similar hexameric aluminum imide (HAlNCH2Ph)6 (1) retains its Al-N network when treated with PhSH to yield (PhSAlNCH2Ph)6 (7). An exchange of ethyl groups and hydrides occurred when 2 was treated with excess of ZnEt2, forming [EtAlNCH2(C4H3S)]68. Compounds 2,4 and 6,8 were characterized by X-ray single-crystal analysis. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Enhancement of steady-state auditory evoked magnetic fields in tinnitusEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2004Eugen Diesch Abstract The steady-state auditory evoked magnetic field and the Pbm, the magnetic counterpart of the second frontocentrally positive middle latency component of the transitory auditory evoked potential, were measured in ten tinnitus patients using a 122-channel gradiometer system. The patients had varying degrees of hearing loss. In all patients, the tinnitus frequency was located above the frequency of the audiometric edge, i.e. the location on the frequency axis above which hearing loss increases more rapidly. Stimuli were amplitude-modulated sinusoids with carrier frequencies at the tinnitus frequency, the audiometric edge, two frequencies below the audiometric edge, and two frequencies between the audiometric edge and the tinnitus frequency. Below the audiometric edge, the root-mean-square field amplitude of the steady-state response computed across the whole head as well as the contralateral and the ipsilateral dipole moment decreased as a function of carrier frequency. With carrier frequency above the audiometric edge, the steady-state response increased again. The amplitudes of the transitory Pbm component were patterned in a qualitatively similar way, but without the differences being significant. For the steady-state response, both whole-head root-mean-square field amplitude and the dipole moment of the sources at the tinnitus frequency showed significant positive correlations with subjective ratings of tinnitus intensity and intrusiveness. These correlations remained significant when the influence of hearing loss was partialled out. The observed steady-state response amplitude pattern likely reflects an enhanced state of excitability of the frequency region in primary auditory cortex above the audiometric edge. The relationship of tinnitus to auditory cortex hyperexcitability and its independence of hearing loss is discussed with reference to loss of surround inhibition in and map reorganization of primary auditory cortex. [source] A Radical Version of the Bromo- and the Iodocyclization of Bis(homoallylic) Alcohols , The Synthesis of Halogenated Tetrahydrofurans by Stereoselective Alkoxyl Radical Ring ClosuresEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2003Jens Hartung Abstract A new synthesis of bromo- and iodomethyl-substituted tetrahydrofurans has been devised. The sequence starts with the conversion of aryl-functionalized bis(homoallylic) alcohols 1 into N -alkenoxythiazole-2(3H)-thiones 6 or pyridine-2(1H)-thiones 7. When photolyzed in the presence of appropriate trapping reagents, thiones 6 and 7 efficiently liberated substituted 4-penten-1-oxyl radicals 2, which underwent synthetically useful 5- exo -trig cyclizations. Cyclized radicals 3 were trapped with BrCCl3 or an adequate iodine atom donor (either n -C4F9I or diethyl 2-iodo-2-methyl malonate) to provide halocyclization products 4 or 5. This strategy has been applied for the synthesis of 3-, 4-, or 5-phenyl-substituted 2-(1-bromo-1-methylethyl)tetrahydrofurans 4a,c (75,90%, 36,96% de), which were not attainable as major products from polar, for example NBS-mediated, bromocyclizations. Aryl-substituted 2-iodomethyl tetrahydrofurans 5 (46,80%) were prepared in a similar way starting from N -alkenoxypyridine-2(1H)-thiones 7 and a suitable iodine atom donor. Diastereomerically pure iodides cis - 5 and trans - 5 served as starting materials for a stereochemical analysis of disubstituted tetrahydrofurans by NMR spectroscopy and X-ray diffraction analysis. The results of this investigation clarified that all new alkoxyl radical cyclizations followed in terms of regio- and diastereoselectivity the general guidelines which had been established for this type of ring-closure reaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] A developmental typology of adolescent personalityEUROPEAN JOURNAL OF PERSONALITY, Issue 4 2010Theo A. Klimstra Abstract The purpose of the current study is to examine whether Block's personality types (i.e. Resilients, Undercontrollers and Overcontrollers) are replicable as developmental trajectories. We applied a Latent Class Growth Analysis (LCGA) framework to five- annual-wave data on a sample of early to middle adolescents (n,=,923). Our results showed that Block's Resilients, Undercontrollers and Overcontrollers are indeed replicable as developmental trajectories across adolescence. These developmental types were related to problem behaviour in a similar way as types found in studies using cross-sectional data. As such, Resilients reflected low levels of problem behaviour, Undercontrollers had high levels of delinquency and Overcontrollers had high levels of depression. Implications and suggestions for further research are discussed. Copyright © 2009 John Wiley & Sons, Ltd. [source] Replicable types and subtypes of personality: Spanish NEO-PI samplesEUROPEAN JOURNAL OF PERSONALITY, Issue S1 2002Bettina Boehm Three major personality prototypes were derived on the basis of a Big Five instrument (NEO-PI) by means of replicated cluster analysis in two Spanish samples (a sample from the general population and a student sample). The replicability of the three prototypes within and their consistency between the two samples were evaluated. In addition, subtypes were analysed in a similar way. Finally, the relation between prototype assignment and level of education was examined in the sample from the general population. Within-study replicability was satisfactory only for the student sample. Comparison with the results for a similar instrument (NEO-PI-R) applied to a German sample showed satisfactory consistency only for the student sample. Discussion centres on the strong sample dependency of the results. Copyright © 2002 John Wiley & Sons, Ltd. [source] Tyr235 of human cytosolic phosphoenolpyruvate carboxykinase influences catalysis through an anion,quadrupole interaction with phosphoenolpyruvate carboxylateFEBS JOURNAL, Issue 23 2008Lakshmi Dharmarajan Tyr235 of GTP-dependent phosphoenolpyruvate (PEP) carboxykinase is a fully invariant residue. The aromatic ring of this residue establishes an energetically favorable weak anion,quadrupole interaction with PEP carboxylate. The role of Tyr235 in catalysis was investigated via kinetic analysis of site-directed mutagenesis-derived variants. The Y235F change lowered the apparent Km for PEP by about six-fold, raised the apparent Km for Mn2+ by about 70-fold, and decreased oxaloacetate (OAA)-forming activity by about 10-fold. These effects were due to an enhanced anion,quadrupole interaction between the aromatic side chain at position 235, which now lacked a hydroxyl group, and PEP carboxylate, which probably increased the distance between PEP and Mn2+ and consequently affected the phosphoryl transfer step and overall catalysis. For the Y235A and Y235S changes, an elimination of the favorable edge-on interaction increased the apparent Km for PEP by four- and six-fold, respectively, and the apparent Km for Mn2+ by eight- and six-fold, respectively. The pyruvate kinase-like activity, representing the PEP dephosphorylation step of the OAA-forming reaction, was affected by the substitutions in a similar way to the complete reaction. These observations indicate that the aromatic ring of Tyr235 helps to position PEP in the active site and the hydroxyl group allows an optimal PEP,Mn2+ distance for efficient phosphoryl transfer and overall catalysis. The Y235A and Y235S changes drastically reduced the PEP-forming and OAA decarboxylase activities, probably due to the elimination of the stabilizing interaction between Tyr235 and the respective products, PEP and pyruvate. [source] Structural and functional evidence for a singular repertoire of BMP receptor signal transducing proteins in the lophotrochozoan Crassostrea gigas suggests a shared ancestral BMP/activin pathwayFEBS JOURNAL, Issue 13 2005Amaury Herpin The transforming growth factor , (TGF-,) superfamily includes bone morphogenetic proteins, activins and TGF-,sensu stricto (s.s). These ligands, which transduce their signal through a heteromeric complex of type I and type II receptors, have been shown to play a key role in numerous biological processes including early embryonic development in both deuterostomes and ecdyzozoans. Lophochotrozoans, the third major group of bilaterian animals, have remained in the background of the molecular survey of metazoan development. We report the cloning and functional study of the central part of the BMP pathway machinery in the bivalve mollusc Crassostrea gigas (Cg- BMPR1 type I receptor and Cg- TGF,sfR2 type II receptor), showing an unusual functional mode of signal transduction for this superfamily. The use of the zebrafish embryo as a reporter organism revealed that Cg- BMPR1, Cg- TGF,sfR2, Cg- ALR I, an activin Type I receptor or their dominant negative acting truncated forms, when overexpressed during gastrulation, resulted in a range of phenotypes displaying severe disturbance of anterioposterior patterning, due to strong modulations of ventrolateral mesoderm patterning. The results suggest that Cg- BMPR1, and to a certain degree Cg- TGF,sfR2 proteins, function in C. gigas in a similar way to their zebrafish orthologues. Finally, based on phylogenetic analyses, we propose an evolutionary model within the complete TGF-, superfamily. Thus, evidence provided by this study argues for a possible conserved endomesoderm/ectomesoderm inductive mechanism in spiralians through an ancestral BMP/activin pathway in which the singular, promiscuous and probably unique Cg- TGF,sfR2 would be the shared type II receptor interface for both BMP and activin ligands. [source] Functional characterization of the evolutionarily divergent fern plastocyaninFEBS JOURNAL, Issue 16 2004José A. Navarro Plastocyanin (Pc) is a soluble copper protein that transfers electrons from cytochrome b6f to photosystem I (PSI), two protein complexes that are localized in the thylakoid membranes in chloroplasts. The surface electrostatic potential distribution of Pc plays a key role in complex formation with the membrane-bound partners. It is practically identical for Pcs from plants and green algae, but is quite different for Pc from ferns. Here we report on a laser flash kinetic analysis of PSI reduction by Pc from various eukaryotic and prokaryotic organisms. The reaction of fern Pc with fern PSI fits a two-step kinetic model, consisting of complex formation and electron transfer, whereas other plant systems exhibit a mechanism that requires an additional intracomplex rearrangement step. The fern Pc interacts inefficiently with spinach PSI, showing no detectable complex formation. This can be explained by assuming that the unusual surface charge distribution of fern Pc impairs the interaction. Fern PSI behaves in a similar way as spinach PSI in reaction with other Pcs. The reactivity of fern Pc towards several soluble c -type cytochromes, including cytochrome f, has been analysed by flavin-photosensitized laser flash photolysis, demonstrating that the specific surface motifs for the interaction with cytochrome f are conserved in fern Pc. [source] Responses of plants in polar regions to UVB exposure: a meta-analysisGLOBAL CHANGE BIOLOGY, Issue 11 2009KEVIN K. NEWSHAM Abstract We report a meta-analysis of data from 34 field studies into the effects of ultraviolet B (UVB) radiation on Arctic and Antarctic bryophytes and angiosperms. The studies measured plant responses to decreases in UVB radiation under screens, natural fluctuations in UVB irradiance or increases in UVB radiation applied from fluorescent UV lamps. Exposure to UVB radiation was found to increase the concentrations of UVB absorbing compounds in leaves or thalli by 7% and 25% (expressed on a mass or area basis, respectively). UVB exposure also reduced aboveground biomass and plant height by 15% and 10%, respectively, and increased DNA damage by 90%. No effects of UVB exposure were found on carotenoid or chlorophyll concentrations, net photosynthesis, Fv/Fm or ,PSII, belowground or total biomass, leaf mass, leaf area or specific leaf area (SLA). The methodology adopted influenced the concentration of UVB absorbing compounds, with screens and natural fluctuations promoting significant changes in the concentrations of these pigments, but lamps failing to elicit a response. Greater reductions in leaf area and SLA, and greater increases in concentrations of carotenoids, were found in experiments based in Antarctica than in those in the Arctic. Bryophytes typically responded in the same way as angiosperms to UVB exposure. Regression analyses indicated that the percentage difference in UVB dose between treatment and control plots was positively associated with concentrations of UVB absorbing compounds and carotenoids, and negatively so with aboveground biomass and leaf area. We conclude that, despite being dominated by bryophytes, the vegetation of polar regions responds to UVB exposure in a similar way to higher plant-dominated vegetation at lower latitudes. In broad terms, the exposure of plants in these regions to UVB radiation elicits the synthesis of UVB absorbing compounds, reduces aboveground biomass and height, and increases DNA damage. [source] Seedling recruitment dynamics of forage and weed species under continuous and rotational sheep grazing in a temperate New Zealand pastureGRASS & FORAGE SCIENCE, Issue 2 2005G. R. Edwards Abstract Understanding the grazing conditions under which plant populations are limited by seed availability (seed limitation) is important for devising management schemes that aim to manipulate the establishment of weed and forage species. Seeds of three weed species (Cirsium arvense, C. vulgare and Rumex obtusifolius) and five forage species (Lolium perenne, Lotus uliginosus syn. L. pedunculatus, Paspalum dilatatum, Plantago lanceolata and Trifolium repens) were broadcast sown into L. perenne,T. repens pastures in Manawatu, New Zealand and five sheep-grazing and two slug-grazing (with and without molluscicide) treatments were imposed in a split-plot design. Of the five sheep-grazing treatments, four compared continuous grazing with rotational grazing at intervals of 12, 24 and 36 d in spring, with all four grazed under a common rotation for the remainder of the year. The fifth treatment was continuous grazing all year. Seed sowing increased seedling emergence of C. vulgare, L. perenne, P. lanceolata, R. obtusifolius and T. repens under all sheep- and slug-grazing treatments, with differences in seedling densities persisting for at least 21 months. Seed sowing did not increase seedling densities of C. arvense, L. uliginosus or P. dilatatum. The effects of sheep-grazing management on seedling emergence and survival were uncoupled. For the five seed-limited species, seedling emergence was greater on pastures that were rotationally grazed during spring compared with those that were continuously grazed. However, seedling survival was lower in pastures grazed rotationally during summer, autumn and winter, so that after 21 months seedling numbers were greater on plots that were continuously grazed all year. Exclusion of slugs increased seedling recruitment of T. repens but had no impact on the other species. As weed and forage species responded in a similar way to sheep-grazing management (increased under continuous, decreased under rotational), it is unlikely that the goals of reducing weed invasions and enhancing forage species establishment could be carried out concurrently in established pastures with the same management. [source] Development of odorless organosulfur reagents and asymmetric reaction using odorless thiolsHETEROATOM CHEMISTRY, Issue 5 2007Manabu Node Odorless organosulfur reagents were developed by increasing their molecular weights to suppress volatility. 1-Dodecanethiol (4), dodecyl methyl sulfide (5), p -heptylphenylmethanethiol (6), p -dodecylbenzenethiol (7), p -heptylbenzenethiol (8), 2-dodecyl-1,3-propanedithiol (11), p -octyloxyphenyl-methanethiol (18b), and p -octyloxybenzenethiol (19) are typical examples of the odorless thiols and sulfides. 6-Morpholinohexyl thiol (15), methyl 6-morpholinohexyl sulfide (16), and methyl 6-morpholinohexyl sulfoxide (17) were also developed as separable reagents from reaction products by facile acid-base extraction. In addition, p -tetramethylsilylphenylmethanethiol (18) and p -tetramethylsilylbenzenethiol (14) were synthesized as the odorless synthetic substitutes of benzyl mercaptan and benzenethiol, respectively. In a similar way, silylated diphenyl disulfide (26) and diselenide (27) were prepared as odorless disulfide and diselenide. Moreover, 10-sulfanylisoborneol (1) was found to be an excellent chiral odorless substitute of hydrogen sulfide in Michael addition. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:572,583, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20348 [source] Enhancement of activity of the primary visual cortex during processing of emotional stimuli as measured with event-related functional near-infrared spectroscopy and event-related potentialsHUMAN BRAIN MAPPING, Issue 1 2008Martin J. Herrmann Abstract In this study we investigated whether event-related near-infrared spectroscopy (NIRS) is suitable to measure changes in brain activation of the occipital cortex modulated by the emotional content of the visual stimuli. As we found in a previous pilot study that only positive but not negative stimuli differ from neutral stimuli (with respect to oxygenated haemoglobin), we now measured the event-related EEG potentials and NIRS simultaneously during the same session. Thereby, we could evaluate whether the subjects (n = 16) processed the positive as well as the negative emotional stimuli in a similar way. During the task, the subjects passively viewed positive, negative, and neutral emotional pictures (40 presentations were shown in each category, and pictures were taken from the International Affective Picture System, IAPS). The stimuli were presented for 3 s in a randomized order (with a mean of 3 s interstimulus interval). During the task, we measured the event-related EEG potentials over the electrode positions O1, Oz, O2, and Pz and the changes of oxygenated and deoxygenated haemoglobin by multichannel NIRS over the occipital cortex. The EEG results clearly show an increased early posterior negativity over the occipital cortex for both positive as well as negative stimuli compared to neutral. The results for the NIRS measurement were less clear. Although positive as well as negative stimuli lead to significantly higher decrease in deoxygenated haemoglobin than neutral stimuli, this was not found for the oxygenated haemoglobin. Hum Brain Mapp 29:28,35, 2008. © 2007 Wiley-Liss, Inc. [source] TERMINATION OF PUPAL DIAPAUSE IN THE BOLLWORM HELICOVERPA ARMIGERA BY PRECOCENE IIINSECT SCIENCE, Issue 4 2001WANG Fang-hai Abstract Precocene II terminated pupal diapause in the bollworm Helicoverpa armigera as 20-hydroxyecdysterone did, whereas juvenile hormone analog ZR-515, cyclic adenosine monophosphate (CAMP), and 5-hydroxytryptamine (5-HT) did not. The results indicate that precocene II affects diapausing pupae in the similar way as what was found in the prepupae of the aphid parasitoids, Aphidius matricariae Haliday and Praon volucre Haliday (Hymenoptera: Aphidiidae). It is suggested that precocene II may affect different kinds of termination of diapause in insects. [source] Analysis of the gutta-percha filled area in C-shaped mandibular molars obturated with a modified MicroSeal techniqueINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2009R. Ordinola-Zapata Abstract Aim, To analyse the gutta-percha filled area of C-shaped molar teeth root filled with the modified MicroSeal technique with reference to the radiographic features and the C-shaped canal configuration. Methodology, Twenty-three mandibular second molar teeth with C-shaped roots were classified according to their radiographic features as: type I , merging, type II , symmetrical and type III , asymmetrical. The canals were root filled using a modified technique of the MicroSeal system. Horizontal sections at intervals of 600 ,m were made 1 mm from the apex to the subpulpal floor level. The percentage of gutta-percha area from the apical, middle and coronal levels of the radiographic types was analysed using the Kruskal,Wallis test. Complementary analysis of the C-shaped canal configurations (C1, C2 and C3) determined from cross-sections from the apical third was performed in a similar way. Results, No significant differences were found between the radiographic types in terms of the percentage of gutta-percha area at any level (P > 0.05): apical third, type I: 77.04%, II: 70.48% and III: 77.13%, middle third, type I: 95.72%, II: 93.17%, III: 91.13% and coronal level, type I: 98.30%, II: 98.25%, III: 97.14%. Overall, the percentage of the filling material was lower in the apical third (P < 0.05). No significant differences were found between the C-shaped canal configurations apically; C1: 72.64%, C2: 79.62%, C3: 73.51% (P > 0.05). Conclusions, The percentage of area filled with gutta-percha was similar in the three radiographic types and canal configuration categories of C-shaped molars. These results show the difficulty of achieving predictable filling of the root canal system when this anatomical variation exists. In general, the apical third was less completely filled. [source] A small-strain overlay modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 1 2009T. Benz Abstract The paper begins with a discussion of the phenomenon of small-strain stiffness and presents the small-strain overlay model, a simple model that takes into account the non-linear stiffness of soils at small strains. The new model can enhance already established elastoplastic formulations for non-linear stiffness variation at small strains in a similar way that intergranular strain enhances the hypoplastic model. The overlay model is driven by the material's strain history and only two additional material constants, both with clear physical meaning. Therefore, the proposed model is a step towards the incorporation of small-strain stiffness into routine design. In this paper, the new small-strain overlay model is formulated. Its ability to take into account the influence of various strain histories on soil stiffness is illustrated in several examples. Copyright © 2008 John Wiley & Sons, Ltd. [source] Finite element formulation and algorithms for unsaturated soils.INTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 9 2003Part I: Theory Abstract This paper presents a complete finite-element treatment for unsaturated soil problems. A new formulation of general constitutive equations for unsaturated soils is first presented. In the incremental stress,strain equations, the suction or the pore water pressure is treated as a strain variable instead of a stress variable. The global governing equations are derived in terms of displacement and pore water pressure. The discretized governing equations are then solved using an adaptive time-stepping scheme which automatically adjusts the time-step size so that the integration error in the displacements and pore pressures lies close to a specified tolerance. The non-linearity caused by suction-dependent plastic yielding, suction-dependent degree of saturation, and saturation-dependent permeability is treated in a similar way to the elastoplasticity. An explicit stress integration scheme is used to solve the constitutive stress,strain equations at the Gauss point level. The elastoplastic stiffness matrix in the Euler solution is evaluated using the suction as well as the stresses and hardening parameters at the start of the subincrement, while the elastoplastic matrix in the modified Euler solution is evaluated using the suction at the end of the subincrement. In addition, when applying subincrementation, the same rate is applied to all strain components including the suction. Copyright © 2003 John Wiley & Sons, Ltd. [source] The Gulf Stream and Atlantic sea-surface temperatures in AD1790,1825INTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2010G. van der Schrier Abstract We present gridded sea-surface temperatures (SSTs) for the Atlantic basin (45°S,60°N) as averages over the period AD1790,1825, based on early-instrumental SST data. The original measurements were compiled by Major James Rennell and made by numerous British naval vessels on behalf of the British Admiralty. We describe the digitization of this dataset and the reconstruction of spatially coherent, averaged conditions for the boreal cold (November-March) and warm (May,September) season using a reduced space optimal interpolation (RSOI) technique, in which the data is projected on a limited number of empirical orthogonal functions. This approach is validated on modern data that are sampled in a similar way as the early-instrumental data. The reconstruction for the November,March period shows a large area with anomalously high temperatures from the point where the Gulf Stream separates from the coast until ca. 20°W. A tongue of anomalous cool water is found at the eastern side of the North Atlantic basin, along the coast of Europe and northern Africa. In the northeastern South Atlantic, anomalously high temperatures are found, while temperatures in the southwestern South Atlantic are anomalously cool. For the March,September season, anomalous temperatures in the South Atlantic are similar, but stronger, compared with those in the boreal cold season. Over the North Atlantic, there is not much similarity between the current SST reconstructions and those published in the late 1950s. Copyright © 2009 Royal Meteorological Society [source] Long-term changes in ozone mini-hole event frequency over the Northern Hemisphere derived from ground-based measurementsINTERNATIONAL JOURNAL OF CLIMATOLOGY, Issue 12 2002Janusz W. Krzy Abstract Decadal changes of ozone mini-hole event appearance over the Northern Hemisphere midlatitudes are examined based on daily total ozone data from seven stations having long records (four decades or more) of ozone observations. The various threshold methods for accepting and rejecting the ozone minima as mini-holes are examined. Mini-hole event activity is seen to be rather stable when averaged over a decadal time scale if the mini-holes are selected as large negative departures (exceeding 20%) relative to the moving long-term total ozone reference. The results are compared with a previous ozone mini-hole climatology derived from satellite data (TOMS measurements on board the Nimbus-7 satellite for the period 1978,93). A nonlinear statistical model (MARS), which takes into account various total ozone dynamical proxies (from NCEP,NCAR reanalysis), is used to study dynamical factors responsible for the ozone extremes over Arosa in the period 1950,99. The model explains as much as 95% of the total variance of the ozone extremes. The model,observation differences averaged over the decadal intervals are rather smooth throughout the whole period analysed. It is suggested that the short-term dynamical processes controlling the appearance of ozone extremes influenced the ozone field in a similar way before and after the onset of abrupt ozone depletion in the early 1980s. The analysis of the ozone profile and the tropopause pressure (from the ozonesondings over Hohenpeissenberg, 1966,99) during mini-hole events shows ,60% ozone reduction in the lower stratosphere and an approximately 50 hPa upward shift of the thermal tropopause there. Copyright © 2002 Royal Meteorological Society. [source] Head-to-head comparison of risedronate vs. teriparatide on bone turnover markers in women with postmenopausal osteoporosis: a randomised trialINTERNATIONAL JOURNAL OF CLINICAL PRACTICE, Issue 6 2008A. D. Anastasilakis Summary Aims:, We aimed to compare the effect of risedronate (RIS) and teriparatide (TPTD) (recombinant human parathyroid hormone 1,34) on bone turnover markers in women with postmenopausal osteoporosis. Methods:, Forty-four Caucasian women (age 65.1 ± 1.6 years) with postmenopausal osteoporosis were randomly assigned to receive either RIS 35 mg once weekly (n = 22) or TPTD 20 ,g once daily (n = 22) for 12 months. Serum N-terminal propeptide of type 1 collagen (P1NP), C-terminal telopeptide of type 1 collagen (CTx), total alkaline phosphatase (ALP) and intact parathyroid hormone (iPTH) were obtained from all women before, 3 and 6 months after treatment initiation. Lumbar spine bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry before and 12 months after treatment initiation. Results:, P1NP, CTx and total ALP levels decreased in RIS group (p < 0.001) and increased in TPTD group (p < 0.001) throughout the treatment. iPTH increased significantly in RIS group (p < 0.05) and decreased in TPTD group (p < 0.001). Finally, lumbar spine BMD increased significantly in both RIS (p = 0.003) and TPTD groups (p < 0.001) without significant differences between them. Conclusions:, Our data suggest that both serum P1NP and CTx are reliable markers of RIS and TPTD action in women with postmenopausal osteoporosis. In a similar way, serum total ALP can be used as an alternative marker for monitoring both RIS and TPTD action, while iPTH can be used only for TPTD-treated women. The increase in P1NP and CTx after 3 months of treatment with RIS or TPTD can predict the increase in BMD after 12 months of treatment. [source] Aspect graphs for three-dimensional object recognition machine vision systemsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 1 2005Tatiana Tambouratzis The purpose of this research is to seek evidence for viewer-centered (especially aspect-graph-based) visual processing in the elementary task of object understanding. Two homologous, bilaterally symmetrical three-dimensional (3-D) objects have been employed that differ in that one is based on parts with flat surfaces and the other on parts with curved surfaces. The following procedure has been followed, separately for each object. In the training (saturated free inspection and manipulation) phase, a location (identical for both objects) of the object is marked with a red strip and the subjects' task is to memorize the object structure as well as the position of the strip. In the test phase, two-dimensional views of the object without the strip are presented and the subjects' task is to determine whether the previously marked location should be visible or invisible in the particular view. Findings have been found consistent with an aspect-graph-based 3-D object representation: (a) the reaction times and errors show characteristic dependencies on viewpoint; (b) a number of views (corresponding to certain aspects and aspect transitions of the aspect graph) consistently produce faster and more accurate recognition; (c) the differences in the aspect graphs of the two objects are reflected in differing patterns of reaction times and errors; furthermore; (d) the subjects impose a standard orientation on the objects, whereby a strong inversion effect is observed; and (e) performance varies in a similar way for both objects as a function of tilt. It is concluded that object understanding is viewpoint dependent, that is, based on a number of views. The characteristics of the views found to be most important for object understanding can be employed for creating efficient 3-D object recognition machine vision systems. © 2005 Wiley Periodicals, Inc. Int J Int Syst 20: 47,72, 2005. [source] Memory effects description by neural networks with delayed feedback connectionsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 4 2004Petia D. Koprinkova For the purpose of dynamic systems modeling, it was proposed to include feedback connections or delay elements in the classical feed-forward neural network structure so that the present output of the neural network depends on its previous values. These delay elements can be connected to the hidden and/or output neurons of the main neural network. Each delay element gets a value of a state variable at a past time instant and keeps this value during a single sampling period. The groups of delay elements record the values of the state variables for a given time period in the past. Changing the number of the delay elements, which belongs to one group, a shorter or a longer time period in the past can be accounted for. Thus, the connection weights determine the influence of the past process states on the present state in a similar way as it is in the time delay kernel or cause-effect relation membership function (CER-MF) models. Specific feed-forward neural networks with time delay connections are used to solve the problem of neural network chemostat modeling as well as specific kinetic rates modeling. The weights of the feedback connections obtained during model training are discussed as the points of a time delay kernel or as the strength levels in a CER model (the points in the CER-MF). The corresponding changes in these weights with the changing time period in the past are shown. © 2004 Wiley Periodicals, Inc. [source] Carbohydrate characterization of quail primordial germ cells during migration and gonadal differentiationJOURNAL OF ANATOMY, Issue 1 2007Clara Armengol Abstract A selection of lectins were used to study changes in the distribution of sugar residues in primordial germ cells (PGCs) during gonadal colonization and differentiation. Although the cytochemical characteristics of PGCs have been described in the chick, little is known about such characteristics in other avian species of interest to experimental biology. Therefore, we studied embryos of Japanese quail (Coturnix coturnix japonica) by light and laser confocal scanning microscopy, using the QH1 antibody as a tool to identify PGCs in both sexes and at all stages. LEA, WGA and RCA-I bound to PGCs in a similar way to QH1. LEA was the best marker for all stages. The presence of acid phosphatase and the intense reaction of LEA, WGA, RCA-I and WFA at the cell surface were shown to be a useful tool in the study of the migratory PGCs of the quail. Quails were sexed histologically in younger embryos than in chick; results were confirmed by PCR. The lectin-binding pattern changed drastically in differentiated gonads. Cell surface reactivity was almost entirely lost. Quail differentiating oogonia showed a characteristic binding pattern to QH1 and to the lectins WGA, RCA-I and WFA. Binding was observed in intense spots in the Golgi complex, and there was a specific PNA reaction. These results suggest that some selective sugar binding sites on the PGCs play a significant role in their migration, colonization and maturation. [source] Use of recycled copper slag for blended cementsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 3 2008M Isabel Sánchez de Rojas Abstract Copper slag is a by-product generated during smelting to extract copper metal from the ore. The copper slag obtained may exhibit pozzolanic activity and may therefore be used in the manufacture of addition-containing cements. In this paper the effect of the incorporation of the copper slag in cement is measured. Blends of copper slag with Portland cement generally possess properties equivalent to Portland cement containing fly ash, but very different to the silica fume incorporation. Copper slag and fly ash reduce the heat of hydration more effectively than silica fume in mortars. The replacement of 30% cement by copper slag reduces the flexural and compressive strength in a similar way to fly ash; however, after 28 days, the reduction is less than the percentage of substitution. Hydrated calcium aluminate phases were analysed using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The pozzolanic activity of copper slag is similar to that of fly ash and higher than silica fume. In the presence of low water/cement ratios, certain pozzolanic materials produce a very compact cement paste that limits the space available for hydration products, a determining factor in the formation of hydrated calcium aluminates. SEM was found to be a useful analytical technique when aluminates are formed and can be clearly detected by XRD. Copyright © 2008 Society of Chemical Industry [source] Integrating laccase,mediator treatment into an industrial-type sequence for totally chlorine-free bleaching of eucalypt kraft pulpJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 7 2006David Ibarra Abstract Enzymatic delignification using the high-redox potential thermostable laccase from the fungus Pycnoporus cinnabarinus and a chemical mediator (1-hydroxybenzotriazole) was investigated to improve totally chlorine-free (TCF) bleaching of Eucalyptus globulus kraft pulps. Different points of incorporation of the enzyme treatment into an industrial-type bleaching sequence (consisting of double oxygen, chelation and peroxide stages) were investigated in pressurized laboratory reactors. The best final pulp properties were obtained using an OOLQPoP sequence, where a laccase,mediator stage (L) was incorporated between double oxygen and chelation. The worse results, when the enzymatic and chelation treatments were combined in a unique stage, seemed related to partial inhibition of laccase-mediator activity by the chelator. The new TCF sequence including the laccase stage permitted to improve eucalypt pulp delignification to values around kappa 5 (hexenuronic acid contribution over 50%) compared to kappa 7 using only TCF chemical reagents. In a similar way, the final brightness obtained, over 91% ISO, was 3,4 points higher than that obtained in the chemical sequences. Although technical and economic issues are to be solved, the results obtained show the feasibility of integrating a laccase,mediator treatment into a TCF sequence for bleaching eucalypt kraft pulp. Copyright © 2006 Society of Chemical Industry [source] Processes underlying deception: an empirical analysis of truth and lies when manipulating the stakesJOURNAL OF INVESTIGATIVE PSYCHOLOGY AND OFFENDER PROFILING, Issue 3 2005Letizia Caso Abstract The aim of the present experiment was to examine to what extent participants experience attempted control, cognitive load and arousal when they lie and tell the truth under lower-stakes and higher-stakes conditions. We expected both differences and similarities between truth tellers and liars. We expected that participants would experience these processes to a higher degree when they lied compared to when they told the truth (differences), but we also expected that both liars and truth tellers would be keen to make a convincing impression; and that raising the stakes would affect liars and truth tellers in a similar way (similarities). A total of 128 participants lied and told the truth during an interview (lying and truth telling was counterbalanced). Stakes were manipulated by informing half of the participants that their interviews would be recorded on videotape and would be analysed and evaluated by police officers. The predictions were supported. Copyright © 2005 John Wiley & Sons, Ltd. [source] Does Parenthood Strengthen a Traditional Household Division of Labor?JOURNAL OF MARRIAGE AND FAMILY, Issue 1 2009Evidence From Sweden Parenthood is often considered a major factor behind gender differences in time allocation, especially between paid work and housework. This article investigates the impact of parenthood on men's and women's daily time use in Sweden and how it changed over the 1990s. The analysis is made using time diary data from the Multinational Time Use Survey (MTUS; N = 13,729) and multivariate Tobit regressions. The results indicate that while parenthood in 1990 , 1991 clearly strengthened the traditional gender division of labor in the household, this was much less the case in 2000 , 2001, when parenthood affected men and women in a more similar way. [source] Serotonergic potentiation of dark pulse-induced phase-shifting effects at midday in hamstersJOURNAL OF NEUROCHEMISTRY, Issue 3 2008Jorge Mendoza Abstract In mammals, resetting of the suprachiasmatic clock (SCN) by behavioral activation or serotonin (5-HT) agonists is mimicked by dark pulses, presented during subjective day in constant light (LL). Because behavioral resetting may be mediated in part by 5-HT inputs to the SCN, here we determined whether 5-HT system can modulate dark-induced phase-shifts in Syrian hamsters housed in LL. Two hours of darkness at mid-subjective day (circadian time 6; CT-6) resulted in increased concentrations of 5-HT in the SCN tissue and induction of c-FOS expression in the raphe nuclei. Injections of the 5-HT1A/7 agonist (+)8-OH-DPAT or dark pulses at CT-6 induced phase-advances of the wheel-running activity rhythm and down-regulated the expression of the clock genes Per1-2 and c-FOS in the SCN in a similar way. The combination of both treatments [(+)8-OH-DPAT + dark pulses], however, resulted in larger phase-advances, while associated molecular changes were not significantly modified, except for the gene Dbp, in comparison to (+)8-OH-DPAT or dark pulses alone. Dark resetting was blocked by pre-treatment with a 5-HT7 antagonist, but not with a 5-HT1A antagonist. The additive phase-shifts of two different cues to reset the SCN clock open wide the gateway for non-photic shifting, leading to new strategies in chronotherapy. [source] | ||||||||||||||||||||||||||||||||||||||||||||||