Showing papers by "University of Coimbra published in 1981"
TL;DR: A comprehensive survey of low-melting elements and compounds has been carried out, covering 190 substances from neon to carbon tetrachloride, which span T t values from 24.5 to 250.5 K.
46 citations
TL;DR: The organophosphorus insecticides, parathion and azinphos (10−4 M), significantly increase the swelling rates and the extent of cell lysis and these compounds are effective in liposomes reconstituted with lipids extracted from erythrocyte membranes.
37 citations
TL;DR: In this article, it is shown that it is possible to obtain a minimum potential energy function from high-symmetry to low-smmetry parts of the surface by using permutational symmetry.
28 citations
TL;DR: In this paper, low and high-spin states of /sup 68/Ge are investigated through in-beam gamma-ray spectroscopy via the /sup 58/Ni(/sup 12/C,2p), /sup 63/Cu(/Sup 7/Li,2n), and /sup 52/Cr(/SUP 19/F,p2n) reactions.
Abstract: Low- and high-spin states of /sup 68/Ge are investigated through in-beam ..gamma..-ray spectroscopy via the /sup 58/Ni(/sup 12/C,2p), /sup 63/Cu(/sup 7/Li,2n), and /sup 52/Cr(/sup 19/F,p2n) reactions. A surprising richness of collective bands is observed in /sup 68/Ge including three even parity bands built on 8/sup +/ levels, the lower two of which are assigned as rotational aligned bands built on both proton and neutron (g/sub 9/2/)/sup 2/ configurations, and three odd parity bands built on ..pi.. and ..nu.. configurations that include the g/sub 9/2/ orbit. Details of the multiple bands and other levels observed in /sup 68/Ge are presented. Rotation-aligned model calculations and interacting boson model calculations for /sup 68/Ge are also described.
25 citations
TL;DR: In this paper, the set of inertias In H 1 X X ∗ H 2 :X is n 1 ×n 2 in terms of In(H1) and in(H2).
18 citations
TL;DR: In this article, a complete description of the possible inertias of the sum H1+⋯+Hp, in terms of the inertia of Hi, i=1,…,p, is given.
18 citations
TL;DR: In this article, an analytic estimate of V 0 is obtained by adding to the near Hartree-Fock curve a function which approximately fits the correlation energy at small R and reduces at large R to the multipolar expansion of the dispersion energy.
16 citations
TL;DR: In this paper, low-energy elastic scattering, molecular resonances and barrier penetration properties of the 16 O + 16 O reaction have been investigated microscopically from a deformed shell model, taking into account nuclear polarization in the overlapping region.
12 citations
TL;DR: In this paper, a substation model, interfaced with digital processors for data acquisition and control, is used to develop and test on-line strategies to control switching operations. And the authors present a network representation model containing switch data is scanned to forecast the effects of any switch operation providing a comprehensive and flexible interlocking scheme.
Abstract: Power systems on-line control is being studied and applied for its technical and econcmical advantages. This paper presents the work carried out with a substation model, interfaced with digital processors for data acquisition and control, to develop and test on-line strategies to control switching operations. A network representation model containing switch data is scanned to forecast the effects of any switch operation providing a comprehensive and flexible inter-locking scheme. Extension of the concept to optimal sequence switching is also presented.
12 citations
TL;DR: In this paper, the authors used the generator coordinate method and a simple p-wave interaction to investigate pion condensation in neutron matter using the generator-coordinate method and the simple p wave interaction.
12 citations
TL;DR: In this article, the axially symmetric model for the lanthanide-induced shift (l.i.s.) data is presented for cytidine 5′-monophosphate (cydmp) and L-alanine binding to a series of Ln-edta chelates at high pH (edta = ethylenediaminetetra-acetate).
Abstract: Lanthanide-induced shift (l.i.s.) data are presented for cytidine 5′-monophosphate (cydmp) and L-alanine binding to a series of lanthanide–edta chelates at high pH (edta = ethylenediaminetetra-acetate). Slow exchange of these substrates between their bound and free environments precludes the use of the heavier Ln(edta) chelates at 25 °C. The cydmp proton l.i.s. ratios at 90 °C are independent of the Ln(edta) used, indicative of effective axial symmetry for this substrate. The alanine l.i.s. values contain large contact shift components which once removed yield corrected pseudo-contact shifts which also are adequately described by an effective axial symmetry model. The results indicate that chemically reasonable structures may be determined from l.i.s. data for substrates acting as bidentate chelators of the lanthanide, providing rapid exchange conditions are met and contact shift contributions are extracted from experimental l.i.s. values for nuclei near the co-ordination site(s). Therefore the fact that the substrate acts as a bidentate chelator does not necessarily exclude the possibility that the axially symmetric model for the l.i.s. is a satisfactory model.
TL;DR: Taking advantage of the impermeability of sarcoplasmic reticulum to EGTA, it is possible to show the existence of the membrane-bound Ca2+ as a distinct fraction from that which exists intravesicularly.
TL;DR: In this paper, the VUV emission of Ar and Kr filled proportional scintillation counters (GSPC) has been detected by a gaseous photoionization detector with multianode proportional chamber configuration.
TL;DR: In this paper, the authors used simple model potential energy functions for internal rotation of ethane derivatives, associated with the Karplus relationship for vicinal HH coupling as a function of the dihedral angle, to find out how serious an approximation it is to reduce the whole conformational problem to a case of rapid equilibrium between the three staggered conformers.
TL;DR: In this paper, the diffuse magnetic elastic scattering from powder samples of Cr•12 at % Fe and Cr•10 at % Co has been obtained at temperatures above and below TN.
Abstract: The diffuse magnetic elastic scattering from powder samples of Cr‐12 at % Fe and Cr‐10 at % Co has been obtained at temperatures above and below TN. Polarized neutrons and polarization analysis were used on the D5 instrument at I. L. L. Grenoble to obtain a unique determination of the magnetic scattering. For the Cr‐Fe alloy forward scattering was observed both above and below TN without significant change in magnitude or Q‐dependence. The magnitude was consistent with that expected from susceptibility measurements. The fall‐off with increasing Q was more rapid than that anticipated for a typical 3d form factor tending towards zero at (sinϑ)/λ∼0.15 A−1. In contrast, the response of the cobalt‐containing alloy was suppressed below TN although of a similar form to the Fe alloy above TN. This suppression could be associated with a locking of the Co moments to the SDW. The incoming neutrons (λ = 0.84 A) have energy ∼115 meV and with an analyser‐detector window of 20 meV any locking of the Fe moments (with cou...
TL;DR: In this article, a PIPS chamber that couples a gas proportional scintillation counter with a photoionization detector is presented for energy and position resolutions, and possible improvements are considered.
TL;DR: The main result consists of a combinatorial characterization of weakly cyclic matrices of odd index as well as the case of even index.
TL;DR: In this article, the conformations of C(8)-substituted 5′-mononucleotides in aqueous solution were studied by NMR using the lanthanide probe method and the nuclear Overhauser effect.
TL;DR: In this paper, the continued fractions for the regular and irregular spherical Coulomb functions of L th order were given. But they were not shown to be continuous. And they were only for the Coulomb function of the irregular form.
TL;DR: In this article, it was shown that for any n-diagonal matrix A, over a field F of characteristic + 2, the matrix DA has a multiple eigenvalue (or a multiple permanental root).
TL;DR: In this article, the Gaussian curvature of a smooth immersion is assumed to be positive at q+ of these points and negative at q−, with q = q++ q−.
Abstract: Let M be a compact connected boundaryless surface and f: M → ℝ3 a smooth immersion transverse to a straight line L. Thus there is an even number p of points xeM such that f(x)eL. Under further transversality assumptions on f (see §3) there is a finite number q of points x of M such that the plane containing f(x) and L touches f(M) at f(x). These assumptions are mild in the sense that they hold for any f in an open dense subset of the space of smooth immersions under consideration. Suppose that the Gaussian curvature of f(M) is positive at q+ of these points and negative at q−, with q = q++ q−. Thenwhere e(M) denotes the Euler number of M.
TL;DR: In this article, the possibility of existence of a standing wave field describing charged pion condensation in a system of nucleons with a definite charge is discussed in the framework of a modified alternating layer spin model.
Abstract: The possibility of existence of a standing wave field describing charged pion condensation in a system of nucleons with a definite charge is discussed in the framework of a modified Alternating Layer Spin model. The dependence of the energy of the system on the total charge is presented. Using a 7[-N p-wave interaction it is found that, in a neutral superdense system of nucleons, the standing wave modes of the pion condensate lead to a lower energy than the running wave modes.
TL;DR: Isotropic and anistropic Raman band shape analyses of the ν2(a1) mode (the Cl-P-Cl bending) of phosphorous trichloride are reported for the pure liquid and carbon tetrachloride solutions as discussed by the authors.
Abstract: Isotropic and anistropic Raman band shape analyses of the ν2(a1) mode (the Cl–P–Cl bending) of phosphorous trichloride are reported for the pure liquid and carbon tetrachloride solutions. The experimental values are compared with those calculated for the free gas molecule reorientation and the angular velocity correlation times and with those obtained from Stokes–Einstein theory. It is shown that the PCl3 molecule tumbling about the axes perpendicular to the C3 axis in the pure liquid proceeds by small‐step Brownian diffusion and is associated with an Arrhenius activation energy of 7.1 kJ mol−1, in good agreement with reported NMR data. The vibrational linewidth of the ν2(a1) mode does not depend strongly on temperature and concentration. Intramolecular vibrational energy exchange with nearby states is assumed as the main fraction of the vibrational relaxation of this mode.
04 May 1981
TL;DR: The architecture for an integrated indexing unit intended for high-speed generation of the addressing patterns required for a wide range of such applications as random-access memories and large-scale-integrated arithmetic structures is proposed.
Abstract: For applications requiring irregular forms of addressing, the high speed of operation of present day random-access memories and large-scale-integrated arithmetic structures can hardly lead to any significant improvements over conventional techniques unless appropriate means are used for addressing the operands at comparable speeds. This paper proposes the architecture for an integrated indexing unit intended for high-speed generation of the addressing patterns required for a wide range of such applications. Reference is made to the usefulness of the proposed unit for the organization of fast array processing attachments to conventional minicomputers and microcomputers.