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Comparison Shows (comparison + shows)
Selected AbstractsSemiclassical path integral theory of a double-well potential in an electric fieldINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 5 2006Theodosios G. Douvropoulos Abstract A recently published methodology based on semiclassical path integral (SCPI) theory was implemented in the case of a model of a double-well potential perturbed by a static electric field, with application to the inversion frequency of NH3. This model was chosen as an idealized case for testing of the present approach, as well as for quantum mechanical models that might be applied in the future. The calculations were concerned with the variation of the frequency of inversion as a function of field strength, F, and of distance, xf (from the symmetric point xo = 0), where the field is "felt." It is found that this variation occurs sharply in very small regions of values of these parameters, and the system switches from internal oscillation to diffusion to the continuum. The fact that the theory is in analytic form allows the extraction of results and conclusions not only at the full SCPI level, but also at the Jeffreys,Wentzel,Kramers,Brillouin (JWKB) level. Comparison shows that the discrepancy sets in as the field strength increases, in accordance with the well-known limitations of the JWKB method regarding its dependence on the degree of variation of the potential as a function of position. © 2005 Wiley Periodicals, Inc. Int J Quantum Chem, 2006 [source] Crannogs and Island Duns: Classification, Dating and FunctionOXFORD JOURNAL OF ARCHAEOLOGY, Issue 3 2000D. W. Harding A recent paper, Islets through Time (OJA 17, 2, 227--44), by Jon Henderson highlighted the fact that the majority of dated crannogs were occupied in the later prehistoric or early historic period, and offered a new classification of artificial islets. This paper addresses consequential issues of definition and classification and urges that artificial islets, whether classed hitherto as crannogs or island duns, should be seen as complementary elements within a spectrum of settlement types, in particular for the Early Iron Age and the early historic periods. Comparison shows that studies of crannogs and their land-based counterparts have faced similar problems of interpretation and that typological compartmentalization has acted to the detriment of a proper understanding of both. [source] Comparison of analytical and numerical solution for optimal vortex diffuser designPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Andreas H. Mehrle The contribution deals with optimization of wing tip devices, so called vortex diffusers. A comparison is given between an analytical approach for obtaining the optimal circulation loading and the results of a numerical investigation using a lifting line method. The purpose of most wing tip devices is to reduce the induced drag of the main wing by converting vortex energy into thrust. In order to achieve an optimal design, a variational formulation originally proposed by Betz and Prandtl for air screws is applied to the circulation distribution of the diffuser blades. In extension to the inviscid formulation, a viscous correction is applied in order to account for frictional forces. In an effort to validate the analytical results, a comparison is given with numerical solutions from a lifting line method. The loading of the diffuser blades is parametrized and optimized with respect to resulting thrust by use of a quasi-Newton gradient method. Comparison shows that, knowing the velocity distribution in the near wake of the wing, considerable decrease of induced drag may be achieved making use of vortex diffusers. Although actual circulation loading may differ between the analytical and numerical estimation, resulting thrust agrees within a few percent. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Organic litter: dominance over stones as a source of interrill flow roughness on low-gradient desert slopes at Fowlers Gap, arid western NSW, AustraliaEARTH SURFACE PROCESSES AND LANDFORMS, Issue 1 2003David Dunkerley Abstract Thirty-six runoff plot experiments provide data on flow depths, speeds, and Darcy,Weisbach friction coefficients (f) on bare soil surfaces, and surfaces to which were added sufficient extra plant litter or surface stones to provide projected cover of 5, 10 and 20 per cent. Precision flow depth data were derived with a computer-controlled gantry and needle gauge for two different discharges for each plot treatment. Taking a fixed flow intensity (Reynolds number, Re = 150) for purposes of comparison shows means of f = 17·7 for bare soil surfaces, f = 11·4 for added stone treatments, and f = 23·8 for added litter treatments. Many individual values of f for stone treatments are lower than for the bare soil surface, but all litter treatments show increases in fcompared to bare soil. The lowering of f in stone treatments relates to the submerged volume that the stones occupied, and the associated concentration of flow onto a smaller part of the plot surface. This leads to locally higher flow intensities and lower frictional drag along threads of flow that the obstacles create. Litter causes higher frictional drag because the particles are smaller, and, for the same cover fraction, are 100 times more numerous and provide 20 times the edge or perimeter length. Along these edges, which in total exceed 2·5 m g,1 (equivalent to 500 m m,2 for a loading of 2 t ha,1), surface tension draws up water from between the litter particles. This reduces flow depth there, and as a consequence of the lower flow intensity, frictional drag rises. Furthermore, no clear passage remains for the establishment of flow threads. These findings apply to shallow interrill flows in which litter is largely immobile. The key new result from these experiments is that under these conditions, a 20 per cent cover of organic litter can generate interrill frictional retardation that exceeds by nearly 41 per cent that of a bare soil surface, and twice that contributed by the same cover fraction of surface stones. Even greater dominance by litter can be anticipated at the many dryland sites where litter covers exceed those tested here. Copyright © 2002 John Wiley & Sons, Ltd. [source] Seismic response of three-dimensional r/c multi-storey frame building under uni- and bi-directional input ground motionEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 12 2007Gennaro Magliulo Abstract This paper deals with seismic analysis of plan-asymmetric r/c frame multi-storey buildings. Non-linear numerical analyses are carried out by using a lumped plasticity model for beams and a multi-spring model for columns, the latter one introduced to account for axial force,biaxial bending moment interaction. A comparison between numerical analyses and experimental test results is reported in order to calibrate the numerical model, showing that the adopted model is very suitable. In order to study the effects of the earthquake orthogonal component, the seismic response of the modelled structure under uni-directional excitation is compared to the one under bi-directional excitation. Such comparison shows that the maximum base shear and the top displacement are not very sensitive to the presence of the orthogonal component, which, conversely, leads to large increase in the column plastic excursions. Copyright © 2007 John Wiley & Sons, Ltd. [source] Microstructural Characterization of Lamellar Features in TiAl by FIB Imaging,ADVANCED ENGINEERING MATERIALS, Issue 6 2010Dennis Peter A novel experimental procedure is introduced to determine phase fractions and the distribution of individual phases of TiAl-based two-phase alloys using the focused ion beam (FIB) technique. Two , -titanium aluminide alloys with a fine-grained duplex and a nearly lamellar microstructure are examined. The special FIB-based preparation procedure results in high contrast ion beam-induced images for all investigated alloys and allows to quantify the phase contents easily by automated microstructural analysis. Fine two-phase structures, e.g. lamellar colonies in , -TiAl, can be imaged in high resolution with respect to different phases. To validate the FIB-derived data, we compare them to results obtained with another method to determine phase fractions, electron back-scatter diffraction (EBSD). This direct comparison shows that the FIB-based technique generally provides slightly higher ,2 -fractions, and thus helps to overcome the limited lateral resolution near grain boundaries and interfaces associated with the conventional EBSD approach. Our study demonstrates that the FIB-based technique is a simple, fast, and more exact way to determine high resolution microstructural characteristics with respect to different phase constitutions in two-phase TiAl alloys and other such materials with fine, lamellar microstructures. [source] Performance analysis of optically preamplified DC-coupled burst mode receiversEUROPEAN TRANSACTIONS ON TELECOMMUNICATIONS, Issue 3 2009T. J. Zuo Bit error rate and threshold acquisition penalty evaluation is performed for an optically preamplified DC-coupled burst mode receiver using a moment generating function (MGF) description of the signal plus noise. The threshold itself is a random variable and is also described using an appropriate MGF. Chernoff bound (CB), modified Chernoff bound (MCB) and the saddle-point approximation (SPA) techniques make use of the MGF to provide the performance analyses. This represents the first time that these widely used approaches to receiver performance evaluation have been applied to an optically preamplified burst mode receiver and it is shown that they give threshold acquisition penalty results in good agreement with a prior existing approach, whilst having the facility to incorporate arbitrary receiver filtering, receiver thermal noise and non-ideal extinction ratio. A traditional Gaussian approximation (GA) is also calculated and comparison shows that it is clearly less accurate (it exceeds the upper bounds provided by CB and MCB) in the realistic cases examined. It is deduced, in common with the equivalent continuous mode analysis, that the MCB is the most sensible approach. Copyright © 2009 John Wiley & Sons, Ltd. [source] Wave-induced progressive liquefaction in a poro-elastoplastic seabed: A two-layered modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 5 2009Z. Liu Abstract In this study, the prediction model proposed by Sassa et al. (Geotechnique 2001; 51(10):847,857) for the wave-induced progressive liquefaction in marine sediment, based on two-layered inviscid fluid system, is re-examined. An alternative approach with a similar framework of Sassa et al. (Geotechnique 2001; 51(10):847,857) is developed to correct the inappropriate mechanism of wave components used. Then, a two-layered wave model which includes viscous effects is established and applied to describe the progressive nature of wave-induced liquefaction. A comprehensive comparison shows that Sassa's model overestimates the maximum liquefaction depth. It is found that the viscosity of liquefied soil cannot be ignored and the solution for an infinite seabed is not suitable for liquefaction analysis of shallow seabed. A parametric study demonstrates the significant influence of numerous wave and soil characteristics on the liquefaction depth. Copyright © 2008 John Wiley & Sons, Ltd. [source] Two-dimensional modeling for stability analysis of two-phase stratified flowINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 7 2010Ghassem Heidarinejad Abstract The effect of wavelength and relative velocity on the disturbed interface of two-phase stratified regime is modeled and discussed. To analyze the stability, a small perturbation is imposed on the interface. Growth or decline of the disturbed wave, relative velocity, and surface tension with respect to time will be discussed numerically. Newly developed scheme applied to a two-dimensional flow field and the governing Navier,Stokes equations in laminar regime are solved. Finite volume method together with non-staggered curvilinear grid is a very effective approach to capture interface shape with time. Because of the interface shape, for any time advancement, a new grid is performed separately on each stratified field, liquid, and gas regime. The results are compared with the analytical characteristics method and one-dimensional modeling. This comparison shows that solving the momentum equation including viscosity term leads to physically more realistic results. In addition, the newly developed method is capable of predicting two-phase stratified flow behavior more precisely than one-dimensional modeling. It was perceived that the surface tension has an inevitable role in dissipation of interface instability and convergence of the two-phase flow model. Copyright © 2009 John Wiley & Sons, Ltd. [source] Reactivities of acridine compounds in hydride transfer reactionsJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7 2007In-Sook Han Lee Abstract Reactivities of acridine derivatives (10-benzylacridinium ion, 1a+, 10-methylacridinium ion, 1b+, and 10-methyl-9-phenylacridinium ion, 1c+) have been compared quantitatively for hydride transfer reactions with 1,3-dimethyl-2-substituted phenylbenzimidazoline compounds, 2Ha,h. Reactions were monitored spectrophotometrically in a solvent consisting of four parts of 2-propanol to one part of water by volume at 25,±,0.1,°C. Reduction potentials have been estimated for acridine derivatives by assuming that the equilibrium constants for the reductions of 1a+,c+ by 2Hb would be the same in aqueous solution and accepting ,361,mV as the reduction potential of the 1-benzyl-3-carbamoylpyridinium ion. The resulting reduction potentials, E, are ,47,mV for 1a+, ,79,mV for 1b+, and ,86,mV for 1c+. Each of acridine derivatives gives a linear Brřnsted plot for hydride transfer reactions. The experimental slopes were compared with those obtained by Marcus theory. This comparison shows that the kinetic data are consistent with a one-step mechanism involving no high-energy intermediates. Copyright © 2007 John Wiley & Sons, Ltd. [source] Physical Modeling and Electrodynamic Characterization of Dielectric Slurries by Impedance Spectroscopy (Part II)JOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2008Vladimir Petrovsky Electrical characterization of dielectric slurries, as 0,3 composite systems, can provide valuable information on the dielectric properties of suspended particles. A new approach developed in our laboratory is based on impedance spectroscopy measurements of the slurries containing dispersed dielectric powders. Dielectric constants of the particles are determined through analysis of the low-frequency section of the impedance spectra. It was shown previously that this approach allows accurate and reliable measurement of dielectric constant of particles (,: ,100,2000) using host liquids (,: ,10,65). This study addresses the validation of this new method with physical model experiments using millimeter-sized sintered BaTiO3 model samples suspended in the liquid. Impedance spectra of barium titanate powder slurries were compared with the spectra of the model samples containing macroscopic cubes prepared by sintering of the same starting powder. This comparison shows a good agreement between the impedance spectra of powder and bulk BaTiO3 and validates the reliability of the new method to determine the dielectric constant of particulate materials. [source] The adjustment of prediction intervals to account for errors in parameter estimationJOURNAL OF TIME SERIES ANALYSIS, Issue 3 2004Paul Kabaila Abstract., Standard approximate 1 , , prediction intervals (PIs) need to be adjusted to take account of the error in estimating the parameters. This adjustment may be aimed at setting the (unconditional) probability that the PI includes the value being predicted equal to 1 , ,. Alternatively, this adjustment may be aimed at setting the probability that the PI includes the value being predicted equal to 1 , ,, conditional on an appropriate statistic T. For an autoregressive process of order p, it has been suggested that T consist of the last p observations. We provide a new criterion by which both forms of adjustment can be compared on an equal footing. This new criterion of performance is the closeness of the coverage probability, conditional on all of the data, of the adjusted PI and 1 , ,. In this paper, we measure this closeness by the mean square of the difference between this conditional coverage probability and 1 , ,. We illustrate the application of this new criterion to a Gaussian zero-mean autoregressive process of order 1 and one-step-ahead prediction. For this example, this comparison shows that the adjustment which is aimed at setting the coverage probability equal to 1 , , conditional on the last observation is the better of the two adjustments. [source] The solution structure of the methylated form of the N-terminal 16-kDa domain of Escherichia coli Ada proteinPROTEIN SCIENCE, Issue 3 2006Hiroto Takinowaki N-Ada16k, the N-terminal 16-kDa domain of the Ada protein; meC38 N-Ada16k, the Cys38 methylated form of N-Ada16k; MTase, methyltransferase; HTH, helix-turn-helix; NMR, nuclear magnetic resonance; MALDI-TOF MS, matrix assisted laser desorption/ionization time of flight mass spectrometry; MNU, methylnitrosourea Abstract The N-terminal 16-kDa domain of Escherichia coli Ada protein (N-Ada16k) repairs DNA methyl phosphotriester lesions by an irreversible methyl transfer to its cysteine residue. Upon the methylation, the sequence-specific DNA binding affinity for the promoter region of the alkylation resistance genes is enhanced by 103 -fold. Then, it acts as a transcriptional regulator for the methylation damage. In this paper, we identified the methyl acceptor residue of N-Ada16k and determined the solution structure of the methylated form of N-Ada16k by using NMR and mass spectrometry. The results of a 13C-filtered 1H- 13C HMBC experiment and MALDI-TOF MS and MS/MS experiments clearly showed that the methyl acceptor residue is Cys38. The solution structure revealed that it has two distinct subdomains connected by a flexible linker loop: the methyltransferase (MTase) subdomain with the zinc,thiolate center, and the helical subdomain with a helix-turn-helix motif. Interestingly, there is no potential hydrogen bond donor around Cys38, whereas the other three cysteine residues coordinated to a zinc ion have potential donors. Hence, Cys38 could retain its inherent nucleophilicity and react with a methyl phosphotriester. Furthermore, the structure comparison shows that there is no indication of a remarkable conformational change occurring upon the methylation. This implies that the electrostatic repulsion between the negatively charged DNA and the zinc,thiolate center may avoid the contact between the MTase subdomain and the DNA in the nonmethylated form. Thus, after the Cys38 methylation, the MTase subdomain can bind the cognate DNA because the negative charge of the zinc,thiolate center is reduced. [source] NMR and SAXS characterization of the denatured state of the chemotactic protein Che Y: Implications for protein folding initiationPROTEIN SCIENCE, Issue 6 2001Pascal Garcia Abstract The denatured state of a double mutant of the chemotactic protein CheY (F14N/V83T) has been analyzed in the presence of 5 M urea, using small angle X-ray scattering (SAXS) and heteronuclear magnetic resonance. SAXS studies show that the denatured protein follows a wormlike chain model. Its backbone can be described as a chain composed of rigid elements connected by flexible links. A comparison of the contour length obtained for the chain at 5 M urea with the one expected for a fully expanded chain suggests that ,25% of the residues are involved in residual structures. Conformational shifts of the ,-protons, heteronuclear 15N-{1H} NOEs and 15N relaxation properties have been used to identify some regions in the protein that deviate from a random coil behavior. According to these NMR data, the protein can be divided into two subdomains, which largely coincide with the two folding subunits identified in a previous kinetic study of the folding of the protein. The first of these subdomains, spanning residues 1,70, is shown here to exhibit a restricted mobility as compared to the rest of the protein. Two regions, one in each subdomain, were identified as deviating from the random coil chemical shifts. Peptides corresponding to these sequences were characterized by NMR and their backbone 1H chemical shifts were compared to those in the intact protein under identical denaturing conditions. For the region located in the first subdomain, this comparison shows that the observed deviation from random coil parameters is caused by interactions with the rest of the molecule. The restricted flexibility of the first subdomain and the transient collapse detected in that subunit are consistent with the conclusions obtained by applying the protein engineering method to the characterization of the folding reaction transition state. [source] The dynamics of long forward rate term structuresTHE JOURNAL OF FUTURES MARKETS, Issue 10 2010Xingguo Luo In this article, we look at study the dynamics of forward rates with maturities longer than 14 years. We re-document the phenomenon of the downward sloping long forward rate term structure using U.S. Treasury STRIPS data over the period 1988 to 2007. By calibrating Diebold F. X. and Li C.-L.'s (2006) dynamic Nelson C. R. and Siegel A. F. (1987) and Christensen J. H. E., Diebold F. X., and Rudebusch G. D.'s (2007) arbitrage-free Nelson-Siegel models, we find that both models explain the empirical phenomenon very well. Out-of-sample comparison shows that imposing no-arbitrage restriction indeed improves the forecasting performance. © 2010 Wiley Periodicals, Inc. Jrl Fut Mark 30:957,982, 2010 [source] CONSULTING KU JLOPLE: SOME HISTORIES OF ORACLES IN WEST AFRICATHE JOURNAL OF THE ROYAL ANTHROPOLOGICAL INSTITUTE, Issue 3 2004Elizabeth Tonkin Historical comparison of oracles in west Africa, mainly during the nineteenth century, shows how divination practices may alter. In the cases explored here, reputation, range of users, economic growth, and political influence interacted as these oracles developed; some at sites with internal and overseas trade access became complex, large-scale operations. But by about 1900, colonialists felt threatened by their secular and their spiritual power and smashed them physically, though not spiritually. Contextualized comparison shows that the many people who were involved as oracle organizers and supplicants must have had different motivations and interests. Some methodological implications of the findings are considered. As in many powerful secular organizations, access to insider knowledge was blocked, but oracular reputation was important, and the oracles had competitors. Success derived partly from collecting intelligence, with simultaneous advertisement that emphasized the mysterious power of their operations. [source] 4-Methoxy-1-naphthol: chains formed by O,H...O hydrogen bonds and ,,, stacking interactionsACTA CRYSTALLOGRAPHICA SECTION C, Issue 12 2009Bernard Marciniak The structure of 4-methoxy-1-naphthol, C11H10O2, (I), contains an intermolecular O,H...O hydrogen bond which links the molecules into a simple C(2) chain running parallel to the shortest crystallographic b axis. This chain is reinforced by intermolecular ,,, stacking interactions. Comparisons are drawn between the crystal structure of (I) and those of several of its simple analogues, including 1-naphthol and some monosubstituted derivatives, and that of its isomer 7-methoxy-2-naphthol. This comparison shows a close similarity in the packing of the molecules of its simple analogues that form ,-stacks along the shortest crystallographic axes. A substantial spatial overlap is observed between adjacent molecules in such stacks. In this group of monosubstituted naphthols, the overlap depends mainly on the position of the substituents carried by the naphthalene moiety, and the extent of the overlap depends on the substituent type. By contrast with (I), in the crystal structure of the isomeric 7-methoxy-2-naphthol there are no O,H...O hydrogen bonds or ,,, stacking interactions, and sheets are formed by O,H..., and C,H..., interactions. [source] 4-Chloro-1-naphtholACTA CRYSTALLOGRAPHICA SECTION C, Issue 5 2009Ewa Rozycka-Sokolowska Molecules of the title compound, C10H7ClO, (I), are connected by a single strong O,H...O hydrogen bond into a simple C(2) chain, which runs parallel to the c axis and is additionally stabilized by intermolecular ,,, stacking interactions. The significance of this study lies in the comparison drawn between the crystal structure of (I) and those of several of its simple analogues. This comparison shows a close similarity in the packing of the molecules that form ,-stacks along the shortest crystallographic axes. A substantial spatial overlap is observed between adjacent molecules in such a ,-stack, depending mainly on the kind of substituent. [source] An Examination of Affine Term Structure Models,ASIA-PACIFIC JOURNAL OF FINANCIAL STUDIES, Issue 4 2009Suk-Joon Byun Abstract This paper examines the relative performance of models in the affine term structure family which includes both complete and essential affine models using Korean government bond yield data. Principal component analysis with Korean government bond yield data shows that the first three components of yields explain 97% of the total yield curve variation, and the components can be characterized as "level", "slope", and "curvature." We also estimate all three-factor affine models using a Kalman filter/quasi maximum likelihood (QML) approach. An exhaustive comparison shows that the three-factor essential affine model, A1 (3) E, in which only one factor affects the instantaneous volatility of short rates but all three factors affect the price of risk, appears to be the best model in Korea. This finding is consistent with results in Dai and Singleton (2002) and Duffee (2002) on US data and in Tang and Xia (2007) on Canadian, German, Japanese, UK and US data. [source] Error analysis of proper motions in decination obtained for 807 Hipparcos stars from PZT observations over many decadesASTRONOMISCHE NACHRICHTEN, Issue 8 2010G. Damljanovi Abstract After publication of the Hipparcos catalogue (in 1997), a few new astrometric catalogues have appeared (TYCHO-2, ARIHIP, etc.), as a good combination of the Hipparcos satellite and ground-based data, to get more accurate coordinates and proper motions of stars than the Hipparcos catalogue ones. There are also investigations on improving the Hipparcos coordinates and proper motions by using the astrometric observations of latitude and universal time variations (via observed stars referred to Hipparcos catalogue), together with Hipparcos data, carried out during the last few years. These kind of ground-based data were collected at the end of the last century by J. Vondrák. There are about 4.4 million optical observations made worldwide at 33 observatories and with 47 instruments during 1899.7,1992.0; our Belgrade visual zenith telescope data (for the period 1949.0-1986.0) were included. First of all, these data were used to determine the Earth Orientation Parameters , EOP, but they are also useful for the opposite task , to check the accuracy of coordinates and proper motions of Hipparcos stars which were observed from the ground over many decades. Here, we use the latitude part of ten Photographic Zenith Tubes , PZT data (more than 0.9 million observations made at 6 observatories during the time interval 1915.8,1992.0), and combine them with the Hipparcos catalogue ones, with suitable weights, in order to check the proper motions in declination for 807 common PZT/Hipparcos stars (and to construct the PZT catalogue of ,, for 807 stars). Our standard errors in proper motions in declination of these stars are less than or equal to the Hipparcos ones for 423 stars. The mean value of standard errors of 313 stars observed over more than 20 years by PZT is 0.40 mas/yr. This is 53% of 0.75 mas/yr (the suitable value from the Hipparcos catalogue). We used the Least Squares Method , LSM with the linear model. Our results are in good agreement with the Earth Orientation Catalogue , EOC-2 and the new Hipparcos ones. The main steps of the method and the investigations of systematic errors in determined proper motions (the proper motion differences with respect to the Hipparcos values, the EOC-2 ones and the new Hipparcos ones, as a function of ,, ,, and magnitude) are presented here. A comparison of the four catalogues by pairs shows that there is no significant relationship between the differences of their ,, values and magnitudes and color indices of the common 807 stars. All catalogues have relatively small random and systematic errors which are close to each other. However, the comparison shows that our formal errors are too small. They are underestimated by a factor of nearly 1.7 (for EOC-2, it is 2.0) if we take the new Hipparcos (or Hipparcos) data as reference (© 2010 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Structure of DsbC from Haemophilus influenzaeACTA CRYSTALLOGRAPHICA SECTION D, Issue 9 2004Man Zhang Bacterial DsbC proteins are involved in rearranging or reducing mismatched disulfide bonds folding within the periplasm. The X-ray structure of the enzyme from Haemophilus influenzae has been solved and compared with the known structure of the Escherichia coli protein. The proteins act as V-shaped dimers with a large cleft to accommodate substrate proteins. The dimers are anchored by a small N-terminal domain, but have a flexible linker region which allows the larger C-terminal domain, with its reactive sulfhydryls, to clamp down on substrates. The overall folds are very similar, but the comparison shows a wider range of hinge motions than previously thought. The crystal packing of the H. influenzae protein allows the movement of the N-terminal domain with respect to the C-terminal domain through motions in the flexible hinge, generating high thermal parameters and unusually high anisotropy in the crystallographic data. [source] Structure of the second PDZ domain from human zonula occludens 2ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 4 2009Hui Chen Human zonula occludens 2 (ZO-2) protein is a multi-domain protein that consists of an SH3 domain, a GK domain and three copies of a PDZ domain with slight divergence. The three PDZ domains act as protein-recognition modules that may mediate protein assembly and subunit localization. The crystal structure of the second PDZ domain of ZO-2 (ZO-2 PDZ2) was determined by molecular replacement at 1.75,Ĺ resolution, revealing a dimer in the asymmetric unit. The dimer is stabilized by extensive symmetrical domain-swapping of the ,1 and ,2 strands. Structural comparison shows that the ZO-2 PDZ2 homodimer may have a similar ligand-binding pattern to the ZO-1 PDZ2,connexin 43 complex. [source] | |||||||||||||||||||||||||