Showing papers by "University of Hamburg published in 1973"
01 Jan 1973
TL;DR: In this article, wave spectra were measured along a profile extending 160 kilometers into the North Sea westward from Sylt for a period of two weeks in 1968 and 1969, with particular emphasis on wave growth under stationary offshore wind conditions and the attenuation of swell in water of finite depth.
Abstract: "Wave spectra were measured along a profile extending 160 kilometers into the North Sea westward from Sylt for a period often weeks in 1968 and 1969. During the main experiment in July 1969, thirteen wave stations were in operation, of which six stations continued measurements into the first two weeks of August. A smaller pilot experiment was carried out in September 1968. Currents, tides, air-sea temperature differences and turbulence in the atmospheric boundary layer were also measured. The goal of the experiment (described in Part 1) was to determine the structure of the source function governing the energy balance of the wave spectrum, with particular emphasis on wave growth under stationary offshore wind conditions (Part 2) and the attenuation of swell in water of finite depth (Part 3). The source functions of wave spectra generated by offshore winds exhibit a characteristic plus-minus signature associated with the shift of the sharp spectral peak towards lower frequencies. The two-lobed distribution of the source function can be explained quantitatively by the nonlinear transfer due to resonant wave-wave interactions (second order Bragg scattering). The evolution of a pronounced peak and its shift towards lower frequencies can also be understood as a selfstabilizing feature of this process. For small fetches, the principal energy balance is between the input by wind in the central region of the spectrum and the nonlinear transfer of energy away from this region to short waves, where it is dissipated, and to longer waves. Most of the wave growth on the forward face of the spectrum can be attributed to the nonlinear transfer to longer waves. For short fetches, approximately (80 ± 20) % of the momentum transferred across the air/sea interface enters the wave field, in agreement with Dobson's direct measurements of the work done on the waves by surface pressures. About 80-90 % of the wave-induced momentum flux passes into currents via the nonlinear transfer to short waves and subsequent dissipation; the rest remains in the wave field and is advected away. At larger fetches the interpretation of the energy balance becomes more ambiguous on account of the unknown dissipation in the low-frequency part of the spectrum. Zero dissipation in this frequency range yields a minimal atmospheric momentum flux into the wave field of the order of (10 to 40) % of the total momentum transfer across the air-sea interface -- but ratios up to 100 % are conceivable if dissipation is important. In general, the ratios (as inferred from the nonlinear energy transfer) lie within these limits over a wide (five-decade) range of fetches encompassing both wave-tank and the present field data, suggesting that the scales of the spectrum continually adjust such that the wave-wave interactions just balance the energy input from the wind. This may explain, among other features, the observed decrease of Phillips' "constant" with fetch. The decay rates determined for incoming swell varied considerably, but energy attenuation factors of two along the length of the profile were typical. This is in order of magnitude agreement with expected damping rates due to bottom friction. However, the strong tidal modulation predicted by theory for the case of a quadratic bottom friction law was not observed. Adverse winds did not affect the decay rate. Computations also rule out wave-wave interactions or dissipation due to turbulence outside the bottom boundary layer as effective mechanisms of swell attenuation. We conclude that either the generally accepted friction law needs to be significantly modified or that some other mechanism, such as scattering by bottom irregularities, is the cause of the attenuation. The dispersion characteristics of the swells indicated rather nearby origins, for which the classical (i event model was generally inapplicable. A strong Doppler modulation by tidal currents was also observed.
3,264 citations
TL;DR: In this paper, the elastic scattering cross sections of the electron-proton and electron-deuteron have been measured at squared four-momentum transfers q 2 of 0.39, 0.5 (GeV/ c ) 2 and scattering angles between 10° and 12°.
187 citations
TL;DR: The knowledge on neuraminidases will stimulate their use in the fields of cytology and histochemistry and enable us to understand the biological function of neuraminic acid.
Abstract: This presentation is a brief description of neuraminidases and is mainly concerned with the substrate specificity of these enzymes. From the observed great differences in substrate specificity it is clear that we are dealing not with one enzyme called neuraminidase but with a variety of enzymes named neuraminidases. Further investigations in this direction should clearly define and make known the properties of these enzymes. Some problems of the biological function of viral neuraminidases have been reviewed recently (Drzeniek, 1972). Interesting aspects of the specific role of sialic acids were uncovered by the use of the substrate specificity of viral and bacterial neuraminidases (Ray & Simmons, 1972). It is hoped that our knowledge on neuraminidases will stimulate their use in the fields of cytology and histochemistry and enable us to understand the biological function of neuraminic acid.
164 citations
TL;DR: In this article, the vector-meson spin density matrik is expressed in terms of the s-channel helicity amplitudes inthe hadron c.m. s.s.
148 citations
TL;DR: In this article, it was shown that spherically symmetric collapse can lead to singularities which are not hidden within black holes, and that singularities can be hidden within a black hole.
Abstract: It is shown that spherically symmetric collapse can lead to singularities which arenot hidden within “black holes”.
144 citations
TL;DR: In this article, the vertical and horizontal mass and energy transports for the layer between the sea surface and 700 mb were calculated for the first (undisturbed) period of the Atlantic Trade-Wind Experiment 1969.
Abstract: The vertical and horizontal mass and energy transports for the layer between the sea surface and 700 mb are calculated for the first (undisturbed) period of the Atlantic Trade-Wind Experiment 1969. The trade-wind inversion represents a layer with a strong downward mass flux due to the mean motion. The height of the inversion and its thermodynamic properties seem to depend on the balance between the mean atmospheric sinking and the turbulent mixing. Because of the vertical transport from the sea surface into the atmosphere, this process assures that water vapor is totally accumulated in the layer below the inversion and transported downstream into the equatorial trough region. Thus the effectiveness of the atmospheric heat absorption in the trades as a force for driving the large-scale circulation is closely related to the vertical static structure as well as to the kinematic field of the low-level trade-wind region.
129 citations
TL;DR: The results indicate that, in the bulbo-spinal systems, 5,6-DHT has a direct neurotoxic action primarily on the superficially located non-terminal parts of the indolamine-containing axons, and that terminal degeneration largely occurs as an anterograde degeneration of the lesioned axons.
115 citations
TL;DR: In this paper, two-photon processes in colliding e ± e − beam reactions were studied, with the aim of testing the parton model, and it was shown that parton contributions dominate in certain well defined kinematical limits, and provide an essential difference between photonic and hadronic processes.
115 citations
TL;DR: In this paper, a brief derivation of Freundlich's adsorption isotherm using straight-forward methods of statistical mechanics is presented, where the assumption that the adsorbed atoms move in Morse potential wells of different depths leads to the observed compensation effect in the energy dependence of the occupation probability of surface sites.
105 citations
TL;DR: The functional activity of the contractile cells, the physiological implication of structural alterations of the lamina propria and the necessity to correlate these observations to andrological findings, are discussed.
Abstract: The ultrastructure of the lamina propria of human seminiferous tubules was analyzed in normal specimens and compared to biopsies showing great thickenning of this area in light microscopy.
85 citations
TL;DR: The results of numerical calculations for some special configurations of stochastic fluctuating field gradients as well as magnetic fields are presented in this paper, where interesting features are worked out for the spinrotation spectra.
Abstract: On the base of the stochastic model of M. Blume for time-dependent hyperfine interactions the perturbation factors of the angular correlation function are evaluated. The results of numerical calculations for some special configurations of stochastic fluctuating field gradients as well as magnetic fields are presented. In the medium range where the fluctuation rates are comparable with the nuclear precession frequencies, interesting features are worked out for the spinrotation spectra. For the limiting case of very fast fluctuations it is proved that the well-known exponential decay of anisotropy as predicted by the theory of Abragam and Pound appears.
TL;DR: The reaction γd→π−pp has been measured in a bubble chamber experiment at DESY with a bremsstrahlung beam of Eγmax = 5.5 GeV as discussed by the authors.
TL;DR: It is shown that a torsion free linear connection is determined by a metric of given signature if and only if its holonomy group is a subgroup of the orthogonal group corresponding to the signature.
Abstract: It is shown that a torsion free linear connection is determined by a metric of given signature if and only if its holonomy group is a subgroup of the orthogonal group corresponding to the signature.
TL;DR: The results of a meeting on the evaluation of quantitative procedures for the separation of meiofauna, held at the Marine Station of the Biologische Anstalt Helgoland, in May 1972, have been presented in this paper.
Abstract: 1. This paper presents the results of a meeting on the evaluation of quantitative procedures for the separation of meiofauna, held at the Marine Station of the Biologische Anstalt Helgoland, in May 1972. Close co-operation on the part of the participants (p. 194) has allowed assessment of advantages and disadvantages of the separation methods applied. The time needed for preserved methods can be reduced by changing to scanning rather than picking out for sorting and counting. 2. Sorting without concentrations: This method is suitable for very fine-grained sediments, oozes; it is generally applied for preserved samples; adequate for hard fauna; insufficient for soft fauna; very time consuming. 3. Decantation: Suitable for sandy sediments; generally applied for preserved samples; adequate for hard fauna; insufficient for soft fauna; time consuming. 4. Elutriation: Suitable for sandy sediments; for unpreserved samples only with anaesthetization, more effective with preserved samples; limited for total live fauna. With preserved samples, adequate for hard fauna; insufficient for soft fauna; quick method. 5. Warm-water elutriation: Suitable for sandy sediments; designed for live hard fauna (especially nematodes, ostracods); quick method. 6. Sea-water ice treatment: Suitable for sandy sediments with microporal structure; only for live extraction; limited for hard fauna; well suited for soft fauna (including ciliates and flagellates); time consuming.
TL;DR: In this paper, an extension of Israel's theorem on the regularity of the Killing horizons is proven and well behaved asymptotically flat vacuum solutions of the Einstein equations which represent the exterior of a non-rotating black hole are considered.
Abstract: An extension of Israel's theorem on the regularity of Killing horizons is proven. Well behaved asymptotically flat vacuum solutions of the Einstein equations which represent the exterior of a non-rotating black hole are considered. It is shown that the black hole has spherical topology and that the equipotential surfaces g
00=constant are non-intersecting two-spheres. The solutions must therefore be members of the one-parameter family of spherically symmetric Schwarzschild solutions.
TL;DR: The occurrence of intrinsic serotonin-, noradrenaline- and dopamine-containing neurons in the gut of Lampetra fluviatilis deviates from the established pattern of innervation of the vertebrate intestine and is considered to be a remnant of an autonomic innervation principle common in invertebrates.
Abstract: Monoamine-containing neurons in the gut of Lampetra fluviatilis are characterized by histochemical, electron microscopical and biochemical methods. Strongly yellow fluorescent, probably serotonin-containing intrinsic neurons are found along the entire length of the intestine. Their processes aggregate to form large bundles of mainly non-terminal axons, constituting a subepithelial fibre plexus. This subepithelial, ganglion cell comprising plexus is connected to a wide-meshed subserosal plexus which has ganglion cells of different size and few varicose, single axons. Intermingled with both plexus there occur — in the anterior and middle but not in the preanal portion of the lamprey intestine — scattered green fluorescent intrinsic perikarya, emanating faintly green fluorescent, poorly varicosed axons. The formaldehyde-induced neuronal fluorophores conform to serotonin (yellow fluorescent compound), noradrenaline, and dopamine (green fluorescent substance), as revealed in microspectrofluorimetric recordings. The electron microscopical analysis of the yellow fluorescent intrinsic neurons in the terminal hindgut shows nerve cell pericarya and axons equipped with a typical population of occasional small granular and many large granular vesicles (750–1600 A). The number and opacity of cores of the small and the osmiophilia of the cores of the large granular vesicles are significantly increased following short-term treatment with 5,6-dihydroxytryptamine. Long-term treatment with 5,6- or 5,7-dihydroxytryptamine provokes severe signs of ultrastructure impairment and eventual degeneration in the supposed serotonin-containing axons, besides indications of piling-up of organelles in the non-terminal axons due to arrest of axonal transport. Chromatography of acid extracts from the lamprey intestine, gills and kidney reveals the presence of serotonin (besides another unidentified indoleamine) and dopamine and noradrenaline in the gut, but only dopamine in the brain. The detection of serotonin, noradrenaline and dopamine in the lamprey gut is confirmed by chemical determinations. The occurrence of intrinsic serotonin-, noradrenaline- and dopamine-containing neurons in the gut of Lampetra fluviatilis deviates from the established pattern of innervation of the vertebrate intestine and is considered to be a remnant of an autonomic innervation principle common in invertebrates.
TL;DR: In this paper, the authors report on energy loss experiments with 50 keV electrons transmitted through thin films of the metals Al, Mg, Li, Na, and K. Since these substances oxidize rapidly they were evaporated and studied in ultra high vacuum.
Abstract: We report on energy loss experiments with 50 keV electrons transmitted through thin films of the metals Al, Mg, Li, Na, and K. The valence electrons of these materials behave like a gas of free electrons to a good approximation and, in particular, give rise to significant collective effects. Since these substances oxidize rapidly they were evaporated and studied in ultra high vacuum. The apparatus and the measurement technique are described.
01 Jan 1973
TL;DR: Findings in the human and monkey colon and sphincter ani internus are interpreted as indicative of abortive regeneration and axonal sprouting from intact intrinsic pericarya in the transitional section of the Hirschsprung colon.
Abstract: Neuronal profiles in the human and monkey colon and sphincter ani internus were analyzed microscopically and compared to those in the constricted aganglionic transitional and dilated, hypertrophic sections of colon from 3 cases of Hirschsprung's disease. Light microscopy revealed two different types of nerve bundles in the normal colon: 1. aniline-blue-positive nerve trunks (conventional peripheral type) containing endoneural collagen and layers of perineural sheath cells, in all probability of extrinsic origin and autonomic in nature, and 2. azocarmine-positive, large multiaxonal Schwann units in Auerbach's plexus, devoid of collagen and hardly ensheathed by perineurium (bundles of intrinsic type), resembling central nervous neurophil formations (with or without ganglion cells interspersed). Preterminal and terminal varicose axons in Auerbach's plexus—not distinguishable by light microscopy—were classified according to their vesicle populations and suspected transmitter type into adrenergic, cholinergic, p-type and sensory fibres. The internal anal sphincter receives predominantly large bundles of the conventional peripheral type containing a conspicuous amount of myelinated axons, as does the aganglionic portion of the Hirschsprung colon. Vesicle-filled profiles among the smooth muscle cells of the sphincter are considered adrenergic and cholinergic, but p-type fibres are present in the junctional area of the lower rectum and upper sphincter. In the aganglionic, constricted section of the colon from two cases of Hirschsprung's disease, adrenergic and cholinergic axons establish frequent synaptic contacts with smooth muscle cells by exposed varicosities. Throughout the aganglionic colon section, processes of intrinsic neurons are absent; but close to the cone-shaped transitional section abnormal nerve fascicles are present, bound by hypertrophic perineurium, and contain masses of collagen in distended endoneurial interspaces. Schwann cell units inside these bundles are mono- or oligoaxonal. The ultramorphology of supporting glial cells reveals features of immature, undifferentiated Schwann cells. These findings are interpreted as indicative of abortive regeneration and axonal sprouting from intact intrinsic pericarya in the transitional section of the Hirschsprung colon. Noradrenaline concentrations in both the normal internal anal sphincter and the aganglionic colon section from one case of Hirschsprung's disease are similar and about twice as high as in all colon sections from healthy individuals, indicating a functionally important, direct adrenergic innervation of smooth musculature in both situations. The lack of inhibitory extrinsic and intrinsic innervation in the constricted gut section in Hirschsprung's disease is considered to be the cause of its spastic contraction in vivo. Similarities and differences in innervation and pharmacological behavior of the internal anal sphincter in man and monkey and in the aganglionic colon section in Hirschsprung's disease are pointed out.
01 Jan 1973
TL;DR: In this article, the vertical stratification of the refractive index immediately over sea was interpreted on the basis of the theory of the atmospheric boundary-layer turbulence, and detailed experimental investigations showed that a parajnetrization of the vertical gradients (profiles) is possible, i.e., the evaluation by simple meteorological routine parameters (vertical differences air-sea), making up the basis for a radar-range prediction.
Abstract: The vertical stratification of the refractive index immediately over sea may be interpreted on the basis of the theory of the atmospheric boundary-layer turbulence. Detailed experimental investigations showed that a parajnetrization of the vertical gradients (profiles) is possible, i.e. the evaluation by simple meteorological routine parameters (vertical differences air-sea), making up the basis for a radar-range prediction. For this problem, the thickness of the evaporation duct (mostly present over sea) proves to be a decisive parameter for characterizing the propagation conditions in the maritime boundary layer. This fact is verified by a great number of transmission measurements on transhorizon and line-of-sight radio links in the wave-length range of 1.8 cm to 1.8 m.
TL;DR: In this paper, the Coulomb correction for uranium has been used to reduce the cross-section of Delbruck scattering at photon energies between 1 and 7 GeV and scattering angles between 3 and 5 mrad on copper, silver, gold, and uranium targets.
Abstract: The differential cross section for Delbr\"uck scattering has been measured at photon energies between 1 and 7 GeV and scattering angles between 1 and 3 mrad on copper, silver, gold, and uranium targets. The results confirm the predictions of quantum electrodynamics, if the exchange of a very large number of photons with the nucleus (Coulomb correction) is taken into account. At momentum transfers of a few MeV/c, the Coulomb correction for uranium results in a reduction of the cross section by a factor between 3 and 5 as compared to the prediction of lowest-order relativistic perturbation theory. The photon-splitting process has been experimentally detected at the same energies and angles. Estimates of the cross section are given.
TL;DR: The mild esterification with phenyldiazomethane allows this method to be used for the assay of short and medium chain free fatty acids in biological materials.
TL;DR: Differences in the genetically controlled variability of constructive and degenerative features indicate action and nonaction of natural selection.
Abstract: DARWIN's statement, that rudimentary parts of organisms are apt to be highly variable, is also true for the regressive structures of cavernicolous animals. On the other hand, adaptive traits develop under cave conditions, the variability of which is lowered rather than increased, compared to that of their precursors in the epigean population. These differences in the genetically controlled variability of constructive and degenerative features indicate action and nonaction of natural selection.
TL;DR: In this article, a Bethe-Salpeter equation for the amplitudes of the Dirac quark fields with heavy spin 12 quarks is discussed for the mesons.
TL;DR: In this article, the pit membranes of the bordered pits in about one hundred coniferous wood species were investigated in regard to their chemical composition, in particular to the aromatic compounds, and the variability of these compounds may be considerable not only between species but also within the same species and even between neighbouring tracheids and pits respectively.
Abstract: The pit membranes of the bordered pits in about one hundred coniferous wood species were investigated in regard to their chemical composition, in particular to the aromatic compounds. In many species pit membranes, even in the sapwood, contain phenolic substances. In heartwood, normally lignification takes place besides the development of other polyphenols. The variability of these compounds, both in sapwood an in heartwood, may be considerable not only between species but also within the same species and even between neighbouring tracheids and pits respectively.
TL;DR: Coital activity and sexual drive were significantly more increased among women than among men during the 24 hr following the experiment, and compared to men, women displayed significantly less emotional activation and significantly greater emotional instability and avoidance.
Abstract: In individual sessions, 120 female and 120 male students read one of two stories in which the sexual experience of a young couple was described. The stories differed in the degree to which affection was expressed. The results were as follows: (1) On the average, the stories were rated as “moderately sexually arousing.” (2) The emotional reactions during and to a lesser degree in the 24 hr after the experiment may be described as general activation, an increase of emotional instability, and avoidance reactions. (3) Most of the subjects registered sexual-physiological reactions in the genital region during the experiment. (4) In the 24 hr period following the experiment, there was a slight to moderate activation of sexual behavior, sexual fantasy, and sexual drive. (5) With reference to all measured responses, only slight sex differences were found. Compared to men, women displayed significantly less emotional activation and significantly greater emotional instability and avoidance. Coital activity and sexual drive were significantly more increased among women than among men during the 24 hr following the experiment. (6) The type of story has only a very slight influence on the measured responses. This is true for both men and women.
TL;DR: In this paper, the drift velocity was measured at gas densities 5 × 1020 ⩽N⩽2.5 × 1021cm-3 (20 −97 atm).
TL;DR: In this article, the silylation of (C5H5)2TiCl2 with SiH3K yields olive-green compounds, which are soluble in benzene.
Abstract: Die Silylierung von (C5H5)2TiCl2 mit SiH3K ergab in Benzol losliches olivgrunes [(C5H5)2TiSiH2]2 (1), das in der tetragonalen Raumgruppe P42/mnm (a = 8.018 A, c = 16.113 A; Z = 2) kristallisiert. Im Molekul liegen zwei (C5H5)2Ti-Einheiten vor, die uber zwei SiH2-Brucken verknupft sind. Der Valenzwinkel TiSiTi betragt 102.8°d und liegt damit nur wenig unter dem Tetraederwinkel.
Preparation and Crystal Structure of Tetrakis(π-cyclopentadienyl)-di-μ-silyleno-dititanium [(C5H5)2TiSiH2]2
The silylation of (C5H5)2TiCl2 with SiH3K yields olive-green [(C5H5)2TiSiH2]2 (1), soluble in benzene. The compound crystallizes in the tetragonal space group P42/mnm (a = 8.018 A, c = 16.113 A; Z = 2). The molecule consists of two (C5H5)2Ti units linked by two SiH2 bridges. The bond angle TiSiTi is 102.8° and thus differs little from the tetrahedral angle.
TL;DR: Evidence is presented which shows that all effects seen with exogenous cAMP were brought about by adenosine set free continuously by the action of extracellular enzymes, and could also be achieved in tumor-bearing animals when high doses of adenine nucleotides like cAMP or NAD were injected.
Abstract: In HeLa S3 cultures, exogenous cAMP and its dibutyryl derivative (DBcAMP) produced divergent effects with respect to glycogen levels as well as to incorporation of labeled precursors into nucleic acids, concentration of nucleotide triphosphates, and the extent of cell proliferation inhibition.
01 Mar 1973
TL;DR: In this article, the rechte Parotisausfuhrungsgang unterbunden und das Drusengewebe in verschiedenen zeitlichen Abstanden nach der Gangligatur (6 Std bis maximal 6 Monate) licht-and elektronenmikroskopisch untersucht.
Abstract: Bei 24 weiblichen Wistar-Ratten wurde der rechte Parotisausfuhrungsgang unterbunden und das Drusengewebe in verschiedenen zeitlichen Abstanden nach der Gangligatur (6 Std bis maximal 6 Monate) licht- und elektronenmikroskopisch untersucht. Die linke Parotis wurde als Vergleichsobjekt verwendet. Die fruhesten und starksten Veranderungen finden sich an den hochdifferenzierten Drusenacini (Fragmentation und vesiculare Transformation des endoplasmatischen Reticulums, fokale Cytoplasmanekrosen, osmiophile Einschlusse, mucoide Transformation der Sekretgranula). Der mit Acinuszellnekrosen einhergehende Auflosungsprozes ist mit dem 10. Versuchstag weitgehend abgeschlossen. Die Schadigungen des Gangsystems treten zeitlich spater auf. Entsprechend dem Differenzierungsgrad sind die Destruktionen der Streifenstucke starker und auch zeitlich fruher als die der Schaltstucke. Die Strukturumwandlung des Gangsystems fuhrt nach 4–6 Versuchsmonaten zu indifferenten Gangformationen vom Typus einer embryonalen Speicheldruse. Die Myoepithelzellen bleiben intakt und erweisen sich als eigenstandiges Zellsystem. Die am Speicheldrusenmesenchym ablaufenden Reaktionen fuhren zusammen mit der Parenchymatrophie zu einer abakteriellen Speicheldrusensklerose. Die Umgestaltung der Parotis nach experimenteller Gangunterbindung entspricht sowohl im zeitlichen Ablauf als auch der Lokalisation und dem Starkegrad Befunden, wie sie bei Spontanerkrankungen menschlicher Speicheldrusen (chronische Sialadenitis, Speichelsteinen, Strahlenschaden) zu beobachten sind. Die Gewebsreaktion des Speicheldrusengewebes gegenuber Noxen unterschiedlicher Atiologie ist offensichtlich begrenzt. Lediglich immunologisch ausgeloste Prozesse zeigen spezielle Reaktionsmuster.
TL;DR: In this article, the photoelectric yield of thin films of solid Ar, Kr, and Xe has been studied in the exciton and interband range between 10 and 32 eV using synchrotron radiation.
Abstract: The photoelectric yield of thin films of solid Ar, Kr, and Xe has been studied in the exciton and interband range between 10 and 32 eV using synchrotron radiation. Decay of excitons contributes only weakly to photoemission. Electron affinities are estimated from the thresholds for strong emission. High absolute yields above the band gap combined with only faint spectral fine structure and a broad minimum at more than twice the gap energy are related to electron-electron scattering.