291 resultados para 3-SPACE


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Public genealogical databases are becoming increasingly populated with historical data and records of the current population`s ancestors. As this increasing amount of available information is used to link individuals to their ancestors, the resulting trees become deeper and more dense, which justifies the need for using organized, space-efficient layouts to display the data. Existing layouts are often only able to show a small subset of the data at a time. As a result, it is easy to become lost when navigating through the data or to lose sight of the overall tree structure. On the contrary, leaving space for unknown ancestors allows one to better understand the tree`s structure, but leaving this space becomes expensive and allows fewer generations to be displayed at a time. In this work, we propose that the H-tree based layout be used in genealogical software to display ancestral trees. We will show that this layout presents an increase in the number of displayable generations, provides a nicely arranged, symmetrical, intuitive and organized fractal structure, increases the user`s ability to understand and navigate through the data, and accounts for the visualization requirements necessary for displaying such trees. Finally, user-study results indicate potential for user acceptance of the new layout.

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We consider incompressible Stokes flow with an internal interface at which the pressure is discontinuous, as happens for example in problems involving surface tension. We assume that the mesh does not follow the interface, which makes classical interpolation spaces to yield suboptimal convergence rates (typically, the interpolation error in the L(2)(Omega)-norm is of order h(1/2)). We propose a modification of the P(1)-conforming space that accommodates discontinuities at the interface without introducing additional degrees of freedom or modifying the sparsity pattern of the linear system. The unknowns are the pressure values at the vertices of the mesh and the basis functions are computed locally at each element, so that the implementation of the proposed space into existing codes is straightforward. With this modification, numerical tests show that the interpolation order improves to O(h(3/2)). The new pressure space is implemented for the stable P(1)(+)/P(1) mini-element discretization, and for the stabilized equal-order P(1)/P(1) discretization. Assessment is carried out for Poiseuille flow with a forcing surface and for a static bubble. In all cases the proposed pressure space leads to improved convergence orders and to more accurate results than the standard P(1) space. In addition, two Navier-Stokes simulations with moving interfaces (Rayleigh-Taylor instability and merging bubbles) are reported to show that the proposed space is robust enough to carry out realistic simulations. (c) 2009 Elsevier B.V. All rights reserved.

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The scalar form factor describes modifications induced by the pion over the quark condensate. Assuming that representations produced by chiral perturbation theory can be pushed to high values of negative-t, a region in configuration space is reached (r < R similar to 0.5 fm) where the form factor changes sign, indicating that the condensate has turned into empty space. A simple model for the pion incorporates this feature into density functions. When supplemented by scalar-meson excitations, it yields predictions close to empirical values for the mean square radius (< r(2)>(pi)(S) = 0.59 fm(2)) and for one of the low energy constants ((l) over bar (4) = 4.3), with no adjusted parameters.

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We consider the energy levels of a hydrogen-like atom in the framework of theta-modified, due to space noncommutativity, Dirac equation with Coulomb field. It is shown that on the noncommutative (NC) space the degeneracy of the levels 2S(1/2), 2P(1/2) and 2P(3/2) is lifted completely, such that new transition channels are allowed. (C) 2009 Elsevier B.V. All rights reserved.

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Structural, magnetic and hyperfine interaction measurements have been carried out on the novel compound La(3.5)Ru(4)O(13) prepared under two different atmospheres (air and oxygen flow). This compound is formed in the orthorhombic structure (space group Pmmm, # 47). The coexistence of the triple-layered perovskite-type planes (quasi-2D structure) and the rutile-like slabs (1D structure) leads to interesting magnetic and electronic properties in this compound. The magnetic susceptibility of this system shows a peak at T similar to 47 K associated with antiferromagnetic interactions. The Curie-Weiss behaviour of the susceptibility provides an effective magnetic moment consistent with Ru ions in low-spin state. Perturbed angular correlation measurements carried out with (111)Cd probe in the temperature range 10-60 K reveal only quadrupole interactions and indicate the occurrence of structural distortions for T<40K. (C) 2009 Elsevier B.V. All rights reserved.

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Structural and conformational properties of the molecule bis[isopropoxy(thiocarbonyl)]sulfide, [(CH(3))(2)CHOC(S)](2)S, have been studied by vibrational spectroscopy (IR and Raman) and quantum chemical calculations (HF and B3LYP with 6-31+G* basis sets). The crystal and molecular structure of the title compound was determined by X-ray diffraction methods. It crystallizes in the monoclinic C2/c space group with a = 8.4007(4), b = 13.5936(5), c = 10.3648(5) angstrom, beta = 106.024(4)degrees and Z = 4 molecules per unit cell. The molecules are sited on a crystallographic twofold axis passing through the sulphide atom and arranged in layers perpendicular to the b-axis. The solid state IR and Raman spectra of the compound give no sign of any other rotamer. (C) 2009 Elsevier B.V. All rights reserved.

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Pure O-methyl N-methoxycarbonyl thiocarbamate CH(3)OC(S)N(H)C(O)OCH(3) (I) and O-ethyl N-methoxycarbonyl thiocarbamate, CH(3)CH(2)OC(S)N(H)C(O)OCH(3) (II), are quantitatively prepared by the addition reaction between the CH(3)OC(O)NCS and the corresponding alcohols. The compounds are characterized by multinuclear ((1)H and (13)C) and bi-dimensional ((13)C HSQC) NMR, GC-MS and FTIR spectroscopy techniques. Structural and conformational properties are analyzed using a combined approach involving crystallographic data, vibration spectra and theoretical calculations. The low-temperature (150 K) crystal structure of II was determined by X-ray diffraction methods. The substance crystallizes in the monoclinic space group P2(1)/n with a = 4.088(1)angstrom. b = 22.346(1)angstrom, c = 8.284(1)angstrom, beta = 100.687(3)degrees and Z = 4 molecules per unit cell. The conformation adopted by the thiocarbamate group -OC(S)N(H)- is syn (C=S double bond in synperiplanar orientation with respect to the N-H single bond), while the methoxycarbonyl C=O double bond is in antiperiplanar orientation with respect to the N-H bond. The non-H atoms in II are essentially coplanar and the molecules are arranged in the crystal lattice as centro-symmetric dimeric units held by N-H center dot center dot center dot S=C hydrogen bonds Id(N center dot center dot center dot S) = 3.387(1)angstrom, <(N-H center dot center dot center dot S) = 166.4(2)degrees]. Furthermore, the effect of the it electronic resonance in the structural and vibrational properties is also discussed. (C) 2009 Elsevier Ltd. All rights reserved.

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Pure N,N`-di(methoxycarbonylsulfenyl)urea, [CH(3)OC(O)SNH](2)CO, is quantitatively prepared by the hydrolysis reaction of CH(3)OC(O)SNCO and characterized by (1)H NMR, GC-MS and FTIR spectroscopy techniques. Structural and conformational properties are analyzed using a combined approach with data obtained from X-ray diffraction, vibrational spectra and theoretical calculation methods. The IR and Raman spectra for normal and deuterated species are reported. The crystal structure of [CH(3)OC(O)SNH](2)CO was determined by X-ray diffraction methods. The substance crystallizes in the orthorhombic P2(1)2(1)2 space group with a = 9.524(2), b = 12.003(1), c = 4.481 (1) angstrom, and Z = 2 moieties in the unit cell. The molecule is sited on a twofold crystallographic axis (C(2)) parallel to c and shows the anti-anti conformation (S-N single bonds antiperiplanar with respect to the opposite C-N single bonds in sulfenyl-urea-sic group). Neighboring molecules are arranged in a chain motif that extends along the C(2)-axis and is held by bifurcated NH center dot center dot center dot O center dot center dot center dot HN intermolecular bonds. A local planar symmetry is observed in the crystal for the central -SN(H)C(O)N(H)S- skeleton. Experimental and calculated data allow to trace this structural feature to the occurrence of N-H center dot center dot center dot O=C hydrogen bonding interactions. Calculated vibrational and structural properties are in good agreement with the experimentally determined features. (C) 2008 Elsevier B.V. All rights reserved.

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Structural and conformational properties of 1H-Isoindole-1,3(2H)-dione, 2-[(methoxycarbonyl)thio] (S-phthalimido O-methyl thiocarbonate) are analyzed using a combined approach including X-ray diffraction, vibrational spectra and theoretical calculation methods. The vibrational properties have been studied by infrared and Raman spectroscopies along with quantum chemical calculations (B3LYP and B3PW91 functional in connection with the 6-311++G** and aug-cc-pVDZ basis sets). The crystal structure was determined by X-ray diffraction methods. The substance crystallizes in the monoclinic P2(1)/c space group with a = 6.795(1), b = 5.109(1), c = 30.011(3) angstrom, beta = 90.310(3)degrees and Z = 4 molecules per unit cell. The conformation adopted by the N-S-C=O group is syn (C=O double bond in synperiplanar orientation with respect to the N-S single bond). The experimental molecular structure is well reproduced by the MP2/aug-cc-pVDZ method. (C) 2010 Elsevier B.V. All rights reserved.

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3`-Azido-3`-deoxythymidine (zidovudine, AZT), a synthetic analog of natural nucleoside thymidine, has been used extensively in AIDS treatments. We report here the synthesis. X-ray crystal and molecular structure, NMR, IR and Raman spectra and the thermal behavior of a novel carbonate of AZT [(AZT-O)(2)C=O], prepared by the reaction of zidovudine with carbonyldiimidazole. The carbonate compound, C(21)H(24)N(10)O(9), crystallizes in the tetragonal space group P4(1)2(1)2 with a = b = 15.284(1), c = 21.695(1) angstrom, and Z = 8 molecules per unit cell. It consists of two AZT moieties of closely related conformations which are bridged by a carbonyl group to adopt a folded Z-like shape. (C) 2010 Elsevier B.V. All rights reserved.

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The new trinuclear gadolinium complex [Gd(3)L(2)(NO(3))(2)(H(2)O)(4)]NO(3)center dot 8H(2)O (1) with the unsymmetrical ligand 2-[N-bis-(2-pyridylmethyl)aminomethyl]-4-methyl-6-[N-bis(2-hydroxy-2-oxoethyl)aminomethyl] phenol (H(3)L) was synthesized and characterized. The new ligand H(3)L was obtained in good yield. Complex I crystallizes in an orthorhombic cell, space group Pcab. Kinetic studies show that complex 1 is highly active in the hydrolysis of the substrate 2,4-bis(dinitrophenyl)phosphate (K(m) = 4.09 mM, V(max) = 2.68 x 10(-2) mM s(-1), and k(cat) = V(max)/[1] = 0.67 s(-1)). Through a potentiometric study and determination of the kinetic behavior of 1 in acetonitrile/water solution, the species present in solution could be identified, and a trinuclear monohydroxo species appears to be the most prominent catalyst under mild conditions. Complex 1 displays high efficiency in DNA hydrolytic cleavage, and complete kinetic studies were carried out (K(m) = 4.57 x 10(-4) M, K(cat)` = 3.42 h(-1), and k(cat)`/K(m) = 7.48 x 10(3) M(-1) h(-1)). Studies with a radical scavenger (dimethyl sulfoxide, DMSO) showed that it did not inhibit the activity, indicating the hydrolytic action of 1 in the cleavage of DNA, and studies on the incubation of distamycin with plasmid DNA suggest that 1 is regio-specific, interacting with the minor groove of DNA.

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Cadmium chloride complex of 1-furoyl-3-cyclohexylthiourea (CyTu) was prepared and characterized by elemental analysis, IR, and Raman spectroscopy. The structure of the complex was determined by single crystal X-ray methods (space group Bbab, a = 20.918(1), b = 23.532(1), c = 23.571(1) angstrom, = = , Z = 8). Each cadmium has distorted octahedral geometry, coordinated by two chlorides and the thiocarbonyl sulfurs from four CyTu molecules. All the spectroscopic data are consistent with coordination of CyTu by sulfur to cadmium.

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In this paper we give a partially affirmative answer to the following question posed by Haizhong Li: is a complete spacelike hypersurface in De Sitter space S(1)(n+1)(c), n >= 3, with constant normalized scalar curvature R satisfying n-2/nc <= R <= c totally umbilical? (C) 2008 Elsevier B.V. All rights reserved.

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LetQ(4)( c) be a four-dimensional space form of constant curvature c. In this paper we show that the infimum of the absolute value of the Gauss-Kronecker curvature of a complete minimal hypersurface in Q(4)(c), c <= 0, whose Ricci curvature is bounded from below, is equal to zero. Further, we study the connected minimal hypersurfaces M(3) of a space form Q(4)( c) with constant Gauss-Kronecker curvature K. For the case c <= 0, we prove, by a local argument, that if K is constant, then K must be equal to zero. We also present a classification of complete minimal hypersurfaces of Q(4)( c) with K constant.

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We describe several families of Lagrangian submanifolds in complex Euclidean space which are H-minimal, i.e. critical points of the volume functional restricted to Hamiltonian variations. We make use of various constructions involving planar, spherical and hyperbolic curves, as well as Legendrian submanifolds of the odd-dimensional unit sphere.