Showing papers by "Chalmers University of Technology published in 1983"
TL;DR: In this paper, the problem of nonlinear pulse propagation in optical fibers, as governed by the nonlinear Schrodinger equation, is reformulated as a variational problem and approximate solutions are obtained for the evolution during propagation of pulse width, pulse amplitude, and nonlinear frequency chirp.
Abstract: The problem of nonlinear pulse propagation in optical fibers, as governed by the nonlinear Schr\"odinger equation, is reformulated as a variational problem. By means of Gaussian trial functions and a Ritz optimization procedure, approximate solutions are obtained for the evolution during propagation of pulse width, pulse amplitude, and nonlinear frequency chirp. Comparisons with results from inverse-scattering theory and/or numerically obtained solutions show very good agreement.
867 citations
TL;DR: In this article, a method for the determination of primary and secondary amino acids is presented, where the reaction of 9-fluorenylmethyl chloroformate with amino acids proceeds under mild conditions in aqueous solution and is complete in 30 sec.
536 citations
505 citations
TL;DR: The interface zone between titanium implants and bone is considered at the macroscopic, microscopic, and molecular levels and includes a tightly adherent titanium oxide layer on the surface of the implant which may be similar to a ceramic material in relation to tissue response.
Abstract: The interface zone between titanium implants and bone is considered at the macroscopic, microscopic, and molecular levels. A high rate of successful dental implants of pure titanium is associated with a very close apposition of the bone to the titanium surface, called osseointegration. At the macroscopic level, osseointegration allows efficient stress transfer from the implant to the bone without abrasion or progressive movement that can take place if a fibrous layer intervenes. At the microscopic level, surface roughness and porosity provide interlocking of the implant and bone tissue which grows into direct contact with titanium. Sections studied in the electron microscope show that calcified tissue can be identified within 50 A of the implant surface. The interface zone includes a tightly adherent titanium oxide layer on the surface of the implant which may be similar to a ceramic material in relation to tissue response. The five year success rate of 90% in 2895 implants in clinical trials since 1965 is associated with the favorable behavior of bone tissue at the interface zone with pure titanium.
420 citations
TL;DR: In this article, the authors proposed an extension of the conventional static approximation of the nonlinear terms in the wave equation to include the derivative of the pulse envelope, which may lead to a self-steepening.
Abstract: For nonlinear short-pulse propagation in long optical fibers, the conventional static approximation of the nonlinear terms in the wave equation must be extended to include the derivative of the pulse envelope. As a result, an initially symmetric pulse will develop an asymmetric self-phase modulation and a self-steepening, which ultimately lead to shock formation unless balanced by dispersion. This effect may be responsible for the pulse asymmetries observed in recent experiments.
389 citations
TL;DR: Direct recordings of the efferent activity in thin hypogastric and pelvic nerve filaments to the bladder were used to analyze the neuronal mechanisms underlying this bladder inhibition and the findings are discussed in relation to the normal neuronal control of the bladder and to the clinical application of IVS.
271 citations
TL;DR: In this article, the authors summarize the current understanding of the high-speed, bistable, threshold-sensitive electro-optic effects obtained in planar structures using surface interactions to suppress the spontaneous director helix characteristic of the bulk ferroelectric liquid crystal.
Abstract: The strong linear coupling of the director ň to electric field E in ferroelectric liquid crystals can be utilized to perform high-speed electro-optic switching suitable for device applications. In this article we summarize the current understanding of the high-speed, bistable, threshold-sensitive electro-optic effects obtained in planar structures using surface interactions to suppress the spontaneous director helix characteristic of the bulk ferroelectric liquid crystal.
228 citations
TL;DR: In this paper, hyperfine structures and isotope shifts of barium isotopes in the mass range 122-146 have been measured in the atomic transition 6 s 2 1 S 0 →6 s 6 p 1 P 1 (5536 A ), utilizing collinear fast-beam laser spectroscopy at the ISOLDE facility at CERN.
175 citations
TL;DR: Results indicate that the degree of upper arm elevation is the most important parameter influencing shoulder muscle load, and short rotator muscles stabilizing the shoulder joint were found to be more hand‐load dependent than the deltoid muscle.
146 citations
TL;DR: A comprehensive list of annotated references on surfaces which combine high solar absorptance with low thermal emittance is presented in this article, covering the period 1955-1981, covering papers printed in scientific journals and in published conference proceedings.
Abstract: A comprehensive classified list of annotated references on surfaces which combine high solar absorptance with low thermal emittance is presented, covering the period 1955–1981. The list embraces papers printed in scientific journals and in published conference proceedings. An index of authors and on surface coatings studied is appended.
132 citations
TL;DR: In this article, the authors compared the glass transformation phenomenology in computer simulated LJ argon "glass" with that in laboratory substances studied on the same time scale, and found that most of the attenuated glass transition characteristics observed for Lj argon are found in the ionic system, and the same relation of the dispersion midpoint to the ideal glass transition temperature is observed.
Abstract: Recent Brillouin scattering studies of relaxation in the simple ion system Ca++–K+/NO−3 (two particles of argon structure and a small anion) provide the experimental basis for a direct comparison of glass transformation phenomenology in computer simulated LJ argon ‘‘glass,’’ with that in laboratory substances studied on the same time scale. Most of the attenuated glass transition characteristics observed for LJ argon are found in the ionic system, and the same relation of the dispersion midpoint to the so‐called ‘‘ideal’’ glass transition temperature is observed. Analysis of the real and imaginary parts of the complex longitudinal modulus shows that at high temperatures the relaxation function for Ca++–K+–NO−3, in strong contrast with that at normal low temperature behavior, closely approaches a simple exponential decay with Arrhenius form for the relaxation time. Furthermore, the high temperature Arrhenius plot extrapolates naturally to the reciprocal quasilattice vibration frequency determined by far in...
TL;DR: In this paper, it is shown that empty gaps are responsible for nonadiabatic behavior and that saturated and aromatic parts of the protein permit electron transfer over larger distances than so far recognized.
Abstract: Thermal electron transfer in protein structures is discussed on the basis of a model first proposed by R. A. Marcus. The electronic matrix element H12 is obtained in a many-electron theory for a number of typical structures of interest in proteins. Repetitive structures often permit resonance transfer over long distances provided the absolute value of the coupling matrix element between neighbouring atomic orbitals is larger than a critical value. The crucial energy separation Δ is obtained as a product of the transfer ‘pathway’ multiplied by coupling matrix elements at the gaps. It is shown that empty gaps are responsible for non-adiabatic behaviour and that saturated as well as aromatic parts of the protein permit electron transfer over larger distances than so far recognized. The Salemme model of the cytochrome c–cytochrome b5 interaction may permit electron transfer if the 8.4 A gap between the haem edges is filled by matter, for instance one of the propionate groups at the haem edge. Finally, the cytochrome c–cytochrome c peroxidase model of Poulos and Kraut is discussed and some alternative pathways suggested.
TL;DR: In this paper, Borohydride reduction of spruce meal followed by mild hydrolysis with acid gave a large proportion of 4-O-(α-d -galactopyranosyluronic acid)-d -xylitol.
TL;DR: In this article, branch structures were determined in fractions of a commercial suspension of PVC and experimental PVC samples obtained at subsaturation conditions (U-PVC) with 13 C n.m. spectroscopy at 50.31 MHz after reductive dehalogenation with tributyltinhydride.
TL;DR: In this paper, the global boundedness in time of higher moments to a weak solution of the non-linear space-homogeneous Boltzmann equation for inverse kth-power forces with k ≧ 5.
Abstract: This paper proves the global boundedness in time of higher moments to a weak solution of the non-linear space-homogeneous Boltzmann equation for inverse kth-power forces with k ≧ 5. In the course of the proof a new collisional estimate of \(v^{'s} + v_*^{'s} - v^s - v_*^s \) is obtained, where v, v* are the velocities before and v′, v′* are the velocities after a binary collision.
TL;DR: A comparison between pentafluorobenzoylation and acetylation showed that the acetylated derivatives of chlorophenol isomers separated better on the column.
TL;DR: The first investigation of hyperfine structure in radium isotopes has enabled the determination of nuclear spins, magnetic dipole and electric quadrupole moments of the isotopes with mass numbers A = 211, 213, 221, 223, 225, 227 and 229.
TL;DR: The pyrE gene is transcribed in a counter-clock wise direction from the E. coli chromosome as an mRNA with a considerable leader segment in front of the protein-coding region that indicates that the frequency of pyr E transcription is regulated by an RNA polymerase (UTP) modulated attenuation.
Abstract: Orotate phosphoribosyltransferase (EC 2.4.2.10) was purified to electrophoretic homogeneity from a strain of Escherichia coli containing the pyrE gene cloned on a multicopy plasmid. The relative molecular masses (Mr) of the native enzyme and its subunit were estimated by means of gel filtration and electrophoresis in the presence of dodecyl sulfate. The amino acid sequences at the N and C termini, as well as the amino acid composition, were determined. The nucleotide sequence of the structural pyrE gene, including 394 nucleotide residues preceding the beginning of the coding frame, was also established. From the results the following conclusions may be drawn.
Orotate phosphoribosyltransferase is a dimeric protein with subunits of Mr 23 326 consisting of 211 amino acid residues. The pyrE gene is transcribed in a counter-clockwise direction from the E. coli chromosome as an mRNA with a considerable leader segment in front of the protein-coding region. This leader contains a structure with features characteristic for a (translated?) rho-independent transcriptional terminator, which is preceded by a cluster of uridylate residues. This indicates that the frequency of pyrE transcription is regulated by an RNA polymerase (UTP) modulated attenuation.
TL;DR: The main purpose of as discussed by the authors is to show how :a :-concave capacities may be built up from Newton capacity c, in lR"(n > 3) in much the same way as :~ :concaves measures from Lebesgue measure m n in lr(n > 1).
Abstract: The main purpose of this paper is to show how so-called :a :-concave capacities may be built up from Newton capacity c, in lR"(n > 3) in much the same way as :~ :concave measures from Lebesgue measure m n in lR"(n > 1). Throughout, O, f2 o . . . . stand for non-empty, open, and convex subsets of IR" and J%,~(O) denotes the class of all convex bodies contained in f2. Recall that a positive Radon measure # in f2 is said to be :~ :-concave if ~ < a < + ~ and
TL;DR: In this article, angle resolved high resolution electron energy loss spectroscopy (EELS) and low energy electron diffraction (LEED) has been used to study the adsorption of hydrogen and oxygen on Pd(100).
TL;DR: In this paper, a uniform linearly elastic beam element with non-coinciding centers of geometry, shear and mass is studied under stationary harmonic end excitation, and the Euler-Bernoulli-Saint Venant theory is applied.
Abstract: A uniform linearly elastic beam element with non-coinciding centres of geometry, shear and mass is studied under stationary harmonic end excitation. The Euler-Bernoulli-Saint Venant theory is applied. Thus the effect of warping is not taken into account. The frequency-dependent 12 × 12 element stiffness matrix is established by use of an exact method. The translational and rotational displacement functions are represented as sums (real) of complex exponential terms where the complex exponents are numerically found. Built-up structures containing beam elements of the described type can be analysed with ease and certainty using existing library subroutines.
TL;DR: It is concluded that the heme ligand arrangement changes on cooling from 298 to 77 K with a concomitant change in the spin state, and the rates of formation of both compounds are consistent with the notion that they are involved in the catalytic cycle.
TL;DR: In this article, the potential of 5-dimethylaminonaphthalene-1-sulphonylhydrazine (Dns-Hydrazine) as a precolumn fluorimetric labeling reagent for reducing sugars was examined in detail.
TL;DR: A uniform linear beam in a uniform linear ambient medium is studied in this article, where the beam performs stationary harmonic damped nonsynchronous space vibration in simultaneous tension, torsion, bending and shear in the presence of a large static axial load.
Abstract: A uniform linear beam in a uniform linear ambient medium is studied. The beam performs stationary harmonic damped nonsynchronous space vibration in simultaneous tension, torsion, bending and shear in the presence of a large static axial load. Hysteretic and viscous dampings of the beam material and ambient medium are considered. Generalized complex Kolousek functions are derived. A 12 × 12 complex symmetric stiffness matrix is established for a supported beam member excited at its ends by prescribed harmonic translations and rotations which have the same frequency but may be out of phase. This matrix allows for an exact analysis of nonproportionally damped built-up beam structures, thus avoiding assumed mode shapes and lumped or consistent masses. A general notation is suggested. Numerical examples are given, including applications of the computer program SFVIBAT-DAMP.
TL;DR: In this article, the concentrations of the trace metals Cd, Cu, Fe, Ni, Pb and Zn in the Gota River estuary have been investigated, and the following metal fractions have been determined: acid-leachable, dissolved, labile and particulate.
Abstract: The concentrations of the trace metals Cd, Cu, Fe, Ni, Pb and Zn in the Gota River estuary have been investigated. The following metal fractions have been determined: acid-leachable, dissolved, labile and particulate. The estuary represents a salt wedge type estuary and is situated in a densely populated region of Sweden. The metal concentrations found for the dissolved fraction is in the range of what can be considered as background levels for freshwater. It is difficult to evaluate any estuarine processes other than conservative mixing for Cd, Cu, Ni and Zn. The dissolved levels in the freshwater end member are Cd, 9–25 ngl −1 ; Cu, 1·1–1·4 μgl −1 ; Fe, 20–75 μg l −1 : Ni, 0·7–0·9 μg l −1 : Pb 0·09–0·2 μg l −1 ; and Zn, 6–7 μg l −1 : The results from the acid-leachable fraction show that at high suspended load the particles sediment in the river mouth. The trace metal levels in this fraction are subject to large variations.
TL;DR: In this paper, the authors studied the boundedness of solutions for the initial value problem for the space-homogeneous Boltzmann equation for inverse kth power forces, whenk>5, and under angular cutoff.
Abstract: This paper studies the boundedness of solutionsf of the initial-value problem for the space-homogeneous Boltzmann equation for inverse kth power forces, whenk>5, and under angular cutoff. The main result is that if the initial value isf0 ⩾ 0 with (1 + ¦υ¦2)φ0 eL1 and (1 + ¦υ¦)sf0e L∞ for somes > 2, then (1 + ¦υ¦s'fteL∞ fort>0 and essυ,tsup(1 + ¦υ¦)s'f(υ, t,) 5.
TL;DR: In this paper, a flow injection method was described for the determination of oxidized ketone bodies in milk, and the detection limit was 0.1 mM. Accuracy and reproducibility were good up to 5 mM.
TL;DR: In this paper, the relativistic front form for the equations of the paraxial electromagnetic wave was developed and shown to be particularly suited to the description of paraxials.
Abstract: With the extension of the work of the preceding paper, the relativistic front form for Maxwell's equations for electromagnetism is developed and shown to be particularly suited to the description of paraxial waves. The generators of the Poincare group in a form applicable directly to the electric and magnetic field vectors are derived. It is shown that the effect of a thin lens on a paraxial electromagnetic wave is given by a six-dimensional transformation matrix, constructed out of certain special generators of the Poincare group. The method of construction guarantees that the free propagation of such waves as well as their transmission through ideal optical systems can be described in terms of the metaplectic group, exactly as found for scalar waves by Bacry and Cadilhac. An alternative formulation in terms of a vector potential is also constructed. It is chosen in a gauge suggested by the front form and by the requirement that the lens transformation matrix act locally in space. Pencils of light with accompanying polarization are defined for statistical states in terms of the two-point correlation function of the vector potential. Their propagation and transmission through lenses are briefly considered in the paraxial limit. This paper extends Fourier optics and completes it by formulating it for the Maxwell field. We stress that the derivations depend explicitly on the "henochromatic" idealization as well as the identification of the ideal lens with a quadratic phase shift and are heuristic to this extent.
01 Jan 1983
01 Jan 1983
TL;DR: In this article, trace metal determinations on samples from a station in the Eastern Arctic Ocean were presented, showing that the surface depletion-bottom enrichment is weakly developed compared to that normally found in ocean waters.
Abstract: Results from trace metal determinations on samples from a station in the Eastern Arctic Ocean are presented. Levels observed in subsurface water are Cd, 0.14–0.20 nM, Cu, 1.9–2.3 nM, Ni, 3.5–4.1 nM and for Zn, 0.86–3.9 nM. For these elements the surface depletion-bottom enrichment is weakly developed compared to that normally found in ocean waters. For iron, low levels were found in directly extracted samples (1.2–9.9 nM) while much higher levels (6.8–<63 nM) were found after storage under acid conditions.