Showing papers by "University of Ljubljana published in 1973"
01 Jan 1973
TL;DR: In this paper, the authors compare the singular eigenfunction expansion method with the integral transform method, which is based upon a Fourier or Laplace transformation, for solving the transport equation.
Abstract: Publisher Summary The concept of singular eigenfunction expansions has undoubtedly been of major importance in improving the understanding of idealized problems in neutron transport and of transport problems in other areas of physics. Such expansions have been successfully employed to derive a wide variety of solutions. It appears that few meaningful neutron transport problems remain, which may be solved in closed form by eigenfunction expansions or by any other existing method. Moreover, all the many advances in computer hardware and software, combined with the improvements in discrete-variable and Monte Carlo procedures for directly solving the transport equation, have severely weakened any motivation for attempts to use analytical methods in realistic problems. The method of singular eigenfunctions is not alone in the field; therefore, a clear view of its merit and its meaning cannot be gained without a comparison with other methods serving the same purpose. This chapter presents a comparison to the few analytical methods that are capable of directly yielding closed-form solutions of idealized problems. The most serious competition comes from the integral transform method, which is based upon a Fourier or Laplace transformation.
68 citations
TL;DR: In this article, the infrared and Raman spectra of crystalline NaH(CH3COO)2, KH(CF3cOO), KH(CH2cOO) and their deuterated analogs have been investigated in the 4000-4030 cm−1 range.
62 citations
TL;DR: In this paper, the theory of fast nucleon radiative capture is refined by replacing the original real nucleon-nucleus coupling interaction by a complex one, having a real part of volume form and an imaginary surface peaked part.
61 citations
60 citations
TL;DR: The simplicity of the method makes it suitable for routine application and can be used for a wide range of samples and concentrations (including background levels).
48 citations
01 Jun 1973-Journal of Comparative Physiology A-neuroethology Sensory Neural and Behavioral Physiology
TL;DR: The trichobothria on the abdomen of the bugPyrrhocoris apterus differ in the length of their sensory hairs and in their functional properties, and the significance of these findings for the possible function of trichOBothria as near field sound receptors is discussed.
Abstract: 1.
The trichobothria on the abdomen of the bugPyrrhocoris apterus differ in the length of their sensory hairs and in their functional properties. Three types may be distinguished. On segment four they have the following properties:
2.
The sensory hair of type 1 is about 380 μm long. The receptor cell is spontaneously active. The spike frequency increases by deflection in caudal direction and decreases by deflection in the cranial direction. The adaptation is of the phasictonic type, and there is no significant change in sensitivity with prolonged stimulation. This receptor can follow sine stimuli synchronously up to about 160 Hz.
3.
Type 2 (sensory hair about 180 μm) has no spontaneous activity. The spike frequency is increased by deflections in cranial and caudal direction. The response is of the phasic-tonic type and phase-locked to the sine wave up to 80 Hz.
4.
The response of type 3 (sensory hair about 80 μm) is of the phasic type, and the adaptation is prompt. Like type 2 receptor is excited by deflections in either direction, and it follows sine waves synchronously up to 80 Hz.
34 citations
TL;DR: In this paper, it was shown that the first excited state lies entirely within the particle-hole space generated from the correlated ground state for angularmomentum projection and generator coordinate method in Gaussian overlap approximation.
32 citations
TL;DR: In this article, the existence of the binary compound CeTi2O5 was confirmed, and its limited stability was investigated before the ternary system was investigated, and six compatibility triangles were established in the system at 1200°C.
Abstract: Subsolidus phase relations in the system BaO-CeO2-TiO2 were investigated using X-ray powder diffraction. The existence of the binary compound CeTi2O5 was confirmed, and its limited stability was studied before the ternary system was investigated. Six compatibility triangles were established in the ternary system at 1200°C. No ternary compound was detected. Extensive mutual solid solubility was observed between BaTiO3 and BaCeO3, whereas little or no solid solubility occurred between the other compounds in the system. The effects of small additions of CeO2 on the tetragonal→Cubic and cubic→hexagonal transition temperatures of BaTiO3 were investigated.
28 citations
TL;DR: The results obtained strongly suggest that the extent of urea interaction with protein is the decisive factor in bringing about the unfolding of protein molecules.
25 citations
TL;DR: In this paper, it is shown how one can obtain, extending Birman's method, the symmetry of the soft modes in general second order phase transitions which occurs at k≠0 points in Brillouin zone accompanying the primitive cell volume enlargement.
25 citations
TL;DR: Underdamped soft tunnelling modes, which disappear on deuteration, are observed in KHZP04 type crystals below Tc in addition to a central mode which exists both above and below TC as discussed by the authors.
Abstract: Underdamped soft tunnelling modes, which disappear on deuteration, are observed in KHZP04 type crystals below Tc in addition to a central mode which exists both above and below Tc. These results can be understood in terms of a Bloch type description of pseudo-spin motion.
Ungedampfte soft-Tunnelmoden, die bei Deuterierung verschwinden, werden in Kristalen vom KH2PO4-Typ unterhalb Tc zusatzlich zu einer Zentralmode, die sowohl oberhalb als auch unterhalb Tc existiert, beobachtet. Dieses Ergebnis lasit sich mit einer Bloch-Beschreibung der Pseudo-Spin-Bewegung verstehen.
TL;DR: In this article, phase equilibrium relations in the pseudobinary systems TiCCr and ZrCCr have been investigated by metallographic and X-ray diffraction methods.
Abstract: Phase equilibrium relations in the pseudobinary systems TiCCr and ZrCCr have been investigated by metallographic and X-ray diffraction methods. Selected samples were analysed by an elecron probe microanalyser. Alloys containing various proportions of the monocarbide and chromium were arc-melted in an argon atmosphere using non-consumable electrodes and were subsequently heat-treated at various temperatures, rapidly cooled, and examined for phase identification. Both the systems TiCCr and ZrCCr were found to be of the simple binary eutectic type having partial solid solubility at the ends. Eutectic compositions and their melting temperatures were established and phase diagrams indicating solidus and liquidus boundaries and the solid solubility limits are presented.
TL;DR: In this article, the application of rotating-and dipolar-frame proton-relaxation measurements for the determination of fast quadrupolar relaxation rates of nonresonant spins $S$, the signals of which are too weak to be measured by the conventional NMR technique, is discussed.
Abstract: The application of rotating- and dipolar-frame proton-relaxation measurements for the determination of fast quadrupolar relaxation rates of nonresonant spins $S$, the signals of which are too weak to be measured by the conventional NMR technique, is discussed Both the case where the proton-$S$ cross-relaxation rate is fast as compared to the $S$-spin-lattice relaxation rate and the case where it is slow are treated The method is applied to ${\mathrm{Ag}}_{2}$${\mathrm{H}}_{3}$I${\mathrm{O}}_{6}$ and ${(\mathrm{N}{\mathrm{H}}_{4})}_{2}$${\mathrm{H}}_{3}$I${\mathrm{O}}_{6}$ The $T$ dependence of the $^{127}\mathrm{I}$ quadrupolar spin-lattice relaxation rates is extracted from the $T$ dependence of the proton dipolar- and rotating-frame spin-lattice relaxation times The iodine-spin-lattice relaxation times are found to be very short and seem to be controlled by electric-field-gradient (EFG) fluctuations due to the motion of protons between the two equilibrium sites in the O-H\char22{}O bonds Using the known values of the static $^{127}\mathrm{I}$ EFG tensor, the O-H\char22{}O proton intrabond jump time $\ensuremath{\tau}$ was found to be of the order of ${10}^{\ensuremath{-}10}$ sec at room temperature, ie, of the same order as in K${\mathrm{H}}_{2}$P${\mathrm{O}}_{4}$-type ferroelectrics
TL;DR: In this paper, the phase transitions in KDA, KD†A, RDA and CDA were observed to be of the first order and the static dielectric properties of these ferroelectrics resemble those of KD†P.
TL;DR: In experiments on anesthetized rats, both venom of Vipera ammodytes and the basic protein fraction produced a rapid fall of the arterial blood pressure, followed by respiratory failure, and an abnormal pattern in the EKG appeared only when the organism was in hypoxia.
TL;DR: In this paper, a model calculation of the diffusion of a noble gas (Ar) through polyethylene bulk is performed on the molecular scale and the potential field due to the penetrating atom is evaluated.
Abstract: A model calculation of the diffusion of a noble gas (Ar) through the polyethylene bulk is performed on the molecular scale. The amorphous phase of the polymer chains is generated by computer calculation and the potential field due to the penetrating atom is evaluated. The diffusion process across the barriers is simulated to obtain the value of the diffusion constant.
Es wird eine Modellrechnung fur die Diffusion eines Edelgases (Ar) durch festes Polyathylen im molekularen Masstab durchgefuhrt. Die amorphe Phase der Polymerketten wird mit Hilfe von Computerberechnungen nachgebildet und das Potentialfeld, das durch die eindringenden Atome erzeugt wird, bestimmt. Der Diffusionsprozes wird simuliert, um die Diffusionskonstante zu erhalten.
TL;DR: In this paper, the temperature dependence of the internal magnetic field on the sites of the 57Fe nuclei, on isomer shift and on quadrupole splitting in the region from 90 to 820K was investigated.
Abstract: A study of lanthanum ferrite, LaFe12O19, by use of the Mossbauer effect has contributed experimental data on the temperature dependence of the internal magnetic field on the sites of the57Fe nuclei, on isomer shift and on quadrupole splitting in the region from 90 to 820K. The Curie temperature was determined at 697K. The Mossbauer spectra of lanthanum and thallium lanthanum ferrite suggest that a special Fe2+ sublattice is not present.
TL;DR: A technique for the electrophoretic separation of pre-stained serum on cellulose acetate, agarose gel and polyacrylamide has been developed and in normal fasting human serum, β, pre-β and α lipoprotein bands are observed.
TL;DR: The results show that tetraethytlammonium increases the activation entropy of the methanesulfonylation of acetylcholinesterase, which more than compensates for the higher activation enthalpy in the presence of tetraethylammonia.
TL;DR: In this paper, single crystals of SrEu 2 Fe 2 O 7 have been grown from a PbO flux and cell dimensions and a structure model of the tetragonal crystals were deviced.
TL;DR: In this paper, the alkene was added to the 1-8 positions of I with a concurrent cleavage of the N4N5 bond and cyclopentene and 2,3-dimethyl-1-3-butadiene.
TL;DR: In this article, the experimental data are in agreement with expectations of the dependence of transition characteristics on molybdenum concentration in Mo x V 1−x O 2 samples.
TL;DR: In this paper, the shape and centroid shift of the Doppler shifted emission line were calculated using only the first few ion-atom collisions, where the average stopping power was used.
TL;DR: In this article, 6-Azidoazolopyridazines and 6-azidopyrinomethylene-amino derivatives were formed in a novel reaction in the presence of diethylamine.
TL;DR: In this paper, the thermal decomposition of the complex fluoride is discussed, as well as the X-ray powder diffraction data of 5N2H4 and 3ThF4.
TL;DR: An approximate value is given for the overall enthalpy of denaturation at the midpoint of unfolding at constant guanidine hydrochloride concentration, pH and temperature, which is much higher than that for chymotrypsinogen A in urea, -70 kcal per mole of protein.