Showing papers by "Technical University of Berlin published in 1986"
TL;DR: The dual fluorescence of certain aromatic systems has greatly advanced in recent years, and the accompanying large charge separation has been linked to a twisted (or small overlap) arrangement of the chromophores as mentioned in this paper.
Abstract: The understanding of the dual fluorescence of certain aromatic systems has greatly advanced in recent years. The accompanying large charge separation has been shown to be linked to a twisted (or small overlap) arrangement of the chromophores. Recent theoretical models are able to describe the excited-state twisting of both single bonds (TICT compounds) and double bonds (olefins) in a unified picture. These models can help to elucidate the photophysical behavior of many organic, inorganic, and biologically relevant compounds, and their application to laser dyes and fluorescent probes provides a route to new “tailor-made” fluorescent materials. Applied to the primary processes of vision and photosynthesis, these models can lead to a deeper understanding of basic photobiological processes.
1,146 citations
TL;DR: In this article, the relativistic thermodynamics of degenerate gases is presented as a field theory of the 14 fields of particle density and stress, and the field equations are based on the conservation laws of particle numbers and energy-momentum and on a balance of fluxes.
262 citations
TL;DR: In this article, the authors analyzed the noise of injection-locked semiconductor lasers by rate equations including the spontaneous emission noise, and the side mode suppression and the relative intensity noise of the locked laser (slave laser) were given for different wavelengths detuning between the master and slave laser and for different linewidth enhancement factors α.
Abstract: The noise of injection-locked semiconductor lasers is analyzed by rate equations including the spontaneous emission noise. The side mode suppression and the relative intensity noise (RIN) of the locked laser (slave laser) are given for different wavelengths detuning between the master and slave laser and for different linewidth enhancement factors α. For large α, locking is difficult to achieve, whereas extremely low noise may be obtained for injection-locked lasers with a low linewidth enhancement factor.
185 citations
01 Jan 1986
TL;DR: A longitudinal study on substance use during adolescence, employing developmental concepts to elucidate that behavior seemed almost truistic, but close scrutiny revealed a fairly consistent "developmental paucity" in the body of literature as discussed by the authors.
Abstract: When in 1982 we started to design a longitudinal study on substance use during adolescence, employing developmental concepts to elucidate that behavior seemed almost truistic. But close scrutiny revealed a fairly consistent “developmental paucity” in the body of literature. Proceeding to the literature on normative development in adolescence, we were struck by another pervasive feature, a kind of isolationism: Either researchers emphasized emerging individual capabilities and behaviors apart from everyday contexts; or they stressed contextual features and their differences, apart from the developing individuals. As Bronfenbrenner (this volume) expressed it, the choice was between development out of context and context without development. Our aim with this introductory chapter and the contributions which follow is to illuminate the contours and features of a developmental perspective appropriate to the study of positive as well as problem behaviors in adolescence.
179 citations
TL;DR: In this paper, the authors studied the asymptotic behavior of polynomials with degree ≥ n satisfying the orthogonal relation and proved that ωm+n(z) is a polynomial of degreem+n+1 with all its zeros contained inV, and the path of integrationC separatesV from the setE.
Abstract: In this paper we continue our study of the asymptotic behavior of polynomialsQmn(z), m, n ∈N, of degree≤n satisfying the orthogonal relation
$$( * )\oint_c {\zeta ^l Q_{mn} (\zeta )} \frac{{f(\zeta )d\zeta }}{{\omega _{m + n} (\zeta )}} = 0,l = 0,...,n - 1,$$
(*)
and all its singularities are supposed to be contained in a set\(E \subseteq \hat C\) of capacity zero, ωm+n(z) is a polynomial of degreem+n+1 with all its zeros contained inV, and the path of integrationC separatesV from the setE. We state and prove results concerning the asymptotic magnitude of the integral in (*) forl=n,n+1,⋯.
160 citations
TL;DR: Raised phosphoenolpyruvate carboxylase activity and simultaneous accumulation of malate in the swollen root zone point to the action of a pH stat preventing a detrimental rise in cytoplasmic pH of transfer cells during enhanced H(+) extrusion.
Abstract: A variety of red pepper (Capsicum annuum L., cv Yaglik) responds to Fe deficiency stress with simultaneously enhanced H+ extrusion, reduction of ferric ions and synthesis of malic and citric acid in a swollen subapical root zone densely covered with root hairs. It is demonstrated that these stress responses temporally coincide with the development of rhizodermal and hypodermal transfer cells in this root zone. During stress response the transfer cells show a marked autofluorescence which could arise from endogenous iron chelators of the phenolic acid type. The presence of organelle-rich cytoplasm which often exhibits rotational cytoplasmic streaming points to high physiological activity and makes these cells, with their increased plasmalemma surface, particularly well suited for the entire stress response mechanism. Since Fe stress-induced acidification is diminished by vanadate and erythrosin B, both specific inhibitors of plasmalemma ATPases, it seems reasonable to suppose that H+ pumping from transfer cells is activated by an ATPase located in their plasmamembrane. H+ extrusion is also shown to be inhibited by abscisic acid. Raised phosphoenolpyruvate carboxylase activity and simultaneous accumulation of malate in the swollen root zone point to the action of a pH stat preventing a detrimental rise in cytoplasmic pH of transfer cells during enhanced H+ extrusion. The simultaneous increase in citric acid concentration favors chelation of iron at the site of its uptake and thus ensures long distance transport to the areas of metabolic demand. A direct link between citrate accumulation and ferric ion reduction as proposed in recent literature further supports the crucial role of transfer cells in the response to Fe deficiency stress.
149 citations
TL;DR: In this paper, a cast Al-Ti-C grain refiner was synthesized by reacting up to 2 pct graphite particles of 20 micron average size with stirred Al-(5 to 10) pct Ti alloy melts, which generated submicron-sized TiC particles within the melts, and their solidified structures showed preferential segregation of the carbide phase in the grain or cell boundary regions.
Abstract: Cast Al-Ti-C grain refiners were synthesized by reacting up to 2 pct graphite particles of 20 micron average size with stirred Al-(5 to 10) pct Ti alloy melts, which generated submicron-sized TiC particles within the melts, and their solidified structures showed preferential segregation of the carbide phase in the grain or cell boundary regions and occasional presence of free carbon whose amount exceeded equilibrium values. At the usual melt temperatures of below 1273 K, though, TiC formed first, but was subsequently found to react with the melt forming a sheathing of A14C3 and Ti3AlC which resulted into poisoning of the TiC particles. However, it was possible to reverse these reactions in order to regain the virgin TiC particles by superheating the melts in the temperature region where TiC particles are thermodynamically stable. Grain refining tests using the TiC master alloys produced fine equiaxed grains of cast aluminum whose sizes were comparable to that obtainable with the standard TiB2 commercial grain refiner. TiC particles introducedvia the master alloys were found to occur in the grain centers, thereby confirming that they nucleated aluminum crystals.
143 citations
01 Jan 1986
123 citations
02 Dec 1986
TL;DR: This tutorial introduction is intended to provide an intuitive understanding of the general format of the graph grammar mechanism underlying the algebraic approach.
Abstract: This tutorial introduction is intended to provide an intuitive understanding of the general format of the graph grammar mechanism underlying the algebraic approach. We point out the essential role of the gluing construction and discuss basic constructions in connection with sequential and parallel independence of derivations and what to do in the case of sequential resp. parallel dependence.
121 citations
TL;DR: The membership problem for fixed context-sensitive languages is polynomial if the right hand side of every production is strictly longer than the left hand side.
104 citations
TL;DR: In this paper, optical spectra of the black hole candidate X-ray binary LMC X-l reveal that the system is surrounded by an extended, highly ionized He III region, N159F, which appears to be the long-sought-for example of an Xray-photo ionized nebula.
Abstract: Optical spectra of the black hole candidate X-ray binary LMC X-l reveal that the system is surrounded by an extended, highly ionized He III region, N159F, which appears to be the long-sought-for example of an X-ray-photoionized nebula The spatially resolved temperature and ionization structure allows us to measure the previously unobservable extreme ultraviolet (EUV) luminosity of an accreting compact object
TL;DR: In this paper, the authors considered the case where there was a unique point maximizing F-h and the curvature at the maximum was not vanishing, where h is the so-called entropy function.
Abstract: We consider expressions of the form Zn=E(exp nF(Sn/n)) where Sn is the sum of n i.i.d. random vectors with values in a Banach space and F is a smooth real valued function. By results of Donsker-Varadhan and Bahadur-Zabell one knows that lim (1/n) log Zn=supxF(x)-h(x) where h is the so-called entropy function. In an earlier paper a more precise evaluation of Zn is given in the case where there was a unique point maximizing F-h and the curvature at the maximum was nonvanishing. The present paper treats the more delicate problem where these conditions fail to hold.
TL;DR: In this article, the experimentally determined negative electron affinities resulting from electron transmission spectroscopy are compared to the theoretically determined eigenvalues of the lowest unoccupied molecular orbitais (ϵ LUMO ) of the neutral compounds, and to the eigen values of the highest occupied molecular orbitals of the respective anion.
TL;DR: The petrography, mineral chemistry and petrogenesis of a sample from the Weissenstein eclogite, Bavaria, Germany, has been investigated in this article.
Abstract: The petrography, mineral chemistry and petrogenesis of a sample from the Weissenstein eclogite, Bavaria, Germany, has been investigated. The total mineral assemblage comprises garnet, clinopyroxeneI+II, quartz, amphiboleI+II, rutile, phengite, epidote/allanite, plagioclase, biotite, apatite, pumpellyite, titanite (sphene), zircon, alkali feldspar and calcite. Textural observations combined with geothermobarometry (Fe/Mg distribution between clinopyroxene/garnet and phengite/garnet; jadeite-content of omphacite, Si-content of phengite, and An-content of plagioclase) provide indications of two different stages in the metamorphic evolution of the rock. The main phengitequartz-eclogite mineral equilibration occurred at minimum P=13–17kbar, minimum T=620±50° C; the retrograde symplectite stage (clinopyroxeneII, amphiboleII, biotite, plagioclase) occurred at P
total between 12 and 8.5 kbar. Reactions of the symplectite stage are:
The phengite decomposition produces H2O, whereas the clinopyroxene decomposition consumes H2O. The estimated P-T-conditions for the Weissenstein eclogite are in the same order of magnitude as those for other eclogite bodies from the Alps and Caledonides believed to be related to subduction processes.
TL;DR: The reaction of alkyl-and aryl-(dicyclopentadienyl)lutetium complexes with H 2 or D 2 gives dimeric dicyclopsedienyl-hydride or -deuteride.
TL;DR: Petrologic data on the paragenesis of kyanite-zoisite marbles and (II) garnet-chloritoid quartz-mica schists are presented with the goal of providing constraints on the pressure-temperature evolution of the Eclogite Zone, Tauern Window, Austria.
TL;DR: Determination des viscosites de Miesowicz η 1, η 2 et η 3 et des coefficients de Leslie γ 1 et γ 2 ; comparaison aux previsions theoriques et a une serie ofensifs experimentaux.
Abstract: The Miesowicz viscosities ${\mathrm{\ensuremath{\eta}}}_{1}$, ${\mathrm{\ensuremath{\eta}}}_{2}$, and ${\mathrm{\ensuremath{\eta}}}_{3}$ and the Leslie coefficients ${\ensuremath{\gamma}}_{1}$ and ${\ensuremath{\gamma}}_{2}$ of perfectly aligned nematics are determined by nonequilibrium molecular-dynamics simulations. The results are compared with theoretical predictions and with experimental data.
TL;DR: In this article, an inhomogeneous ground-state distribution was inferred regarding the relaxation coordinate towards the twisted intramolecular charge transfer (TICT) state of DMABN and similar molecules in polymethylmethacrylate glass.
TL;DR: In this paper, the thermal properties of (KBr${}{1\mathrm{-}x\ensuremath{-}}\mathm{x}}$(KCN${}_{\mathmm{x}$ single crystals have been studied between 0.05 and 100 K over the entire compositional range, and it is shown that these mixed crystals represent an excellent example of two-level system excitations of variable number densities, depending on the choice of x.
Abstract: The thermal properties of (KBr${)}_{1\mathrm{\ensuremath{-}}\mathrm{x}}$(KCN${)}_{\mathrm{x}}$ single crystals have been studied between 0.05 and 100 K over the entire compositional range. For 0.25\ensuremath{\le}x\ensuremath{\le}0.70, these crystals have the thermal conductivity that is typical for all structurally disordered, amorphous solids. The same holds for the low-temperature specific heat, which varies linearly with temperature, and logarithmically with the measuring time. Through a quantitative analysis it is shown that these mixed crystals represent an excellent example of two-level-system excitations of variable number densities, depending on the choice of x. Therefore, these crystals can serve as a model for the exploration of the low-energy excitations which are characteristic for all amorphous solids.
TL;DR: In this article, the aerial parts of nine Baccharis species from Argentina gave 37 new compounds, seven ent -clerodanes, 13 ent -labdanes, two friedolabdane, a norlabdane ketone, seven coumaric acid derivatives, two umbelliferone derivatives, a flavanone, three sesquiterpenes including a nor-furanocadinene and a propiophenone derivative.
TL;DR: In the threshold photoelectron spectrum of Ne, many final states are present, some with quartet spin multiplicity and others with high-L values, in agreement with the theoretical prediction of Greene.
Abstract: Photoionization of helium and neon to excited satellite states, ${\mathrm{He}}^{+}$ nl and ${\mathrm{Ne}}^{+}$ 1${s}^{2}$2${s}^{2}$2${p}^{4}$nl, was studied with synchrotron radiation and threshold electron analysis. Photoelectron satellites have been directly measured at threshold for the first time to our knowledge. The relative satellite cross sections were determined over the kinetic energy range from 0 to 1 eV. The angular distributions were also evaluated close to threshold. Strong correlation effects were observed in two cases. For He near threshold, the angular-distribution asymmetry parameter \ensuremath{\beta} is near zero for the n=2 satellite and is increasingly negative for the higher-n satellites, in agreement with the theoretical prediction of Greene. In the threshold photoelectron spectrum of Ne, many final states are present, some with quartet spin multiplicity and others with high-L values.
TL;DR: It is suggested that the extremely low nitrogen content of the investigated wood species was the primary cause for the extensive delignification as well as the concomitant suppression of cellulose breakdown.
Abstract: Chemical and micromorphological analysis revealed that South Chilean “palo podrido” results from a white-rot fungus that causes highly selective and extensive delignification. Palo podrido samples from 10 different hardwood trunks ( Eucryphia cordifolia, Drimys winteri , and Nothofagus dombeyi ) decayed by Ganoderma applanatum were analyzed. Of 14 samples, 11 had extremely low Klason lignin values, ranging from 6.1 to 0.4% (dry weight). The most remarkable and unusual feature was that delignification and defibration were not restricted to small pockets but extended throughout large areas in the interior of trunks subjected to undisturbed rotting over long periods of time. Comparative analysis of water content, swelling capacity, and lignin content led to the conclusion that besides lignin degradation, suppression of the cellulolytic activity of the rotting organisms plays a decisive role. Among various nutrients added to a palo podrido sample (3% residual Klason lignin), the nitrogen source was the only one leading to almost complete cellulose degradation. We suggest that the extremely low nitrogen content (0.037 to 0.073% [dry weight]) of the investigated wood species was the primary cause for the extensive delignification as well as the concomitant suppression of cellulose breakdown. The low temperatures, high humidity, and microaerobic conditions maintained within the decaying trunks are discussed as additional ecological factors favoring delignification in South Chilean rain forests. Images
TL;DR: The situation in the area of document processing today is described and the requirements for future document processing systems are discussed.
TL;DR: The stratigraphical interpretation of the strata of Nubia allows for the first time, in connection with structural, petrological and sedimentological investigations, to reconstruct the geological development of this cratonal area.
Abstract: The stratigraphical interpretation of the strata of Nubia allows for the first time — in connection with structural, petrological and sedimentological investigations — to reconstruct the geological development of this cratonal area. After cratonization during the PanAfrican event, extensional trends in WSW-ENE direction caused a structural relief, striking NNW-SSE. The collision between Gondwana and the northern continents during the Carboniferous resulted in the uplifting of large parts of the northeast African Plate and was accompanied by more or less East-West striking faults and magmatic intrusions. Erosion of Paleozoic sediments in middle and southern Egypt and reversal of the main drainage direction was the consequence. This caused deposition of Karroo-type strata in northern Sudan, including glacial deposits at the base along the Sudanes Egyptian border.
01 Jan 1986
TL;DR: This extended approach to the algebraic theory of graph grammars is applied to a small library system in order to show the flexibility of this concept for the design of systems in computer science and related areas.
Abstract: The algebraic approach of graph grammars is extended by a very general notion of application conditions which can be defined separately for each production. This extended approach is applied to a small library system in order to show the flexibility of this concept for the design of systems in computer science and related areas. In addition to the general concept we study some special cases of graph grammars with application conditions with respect to their generative power. Finally we state some facts how to extend known results in the algebraic theory of graph grammars to the case with application conditions.
TL;DR: In this paper, the aerial parts of several Mongolian Artemisia species were investigated by spectroscopic methods and a few chemical transformations, yielding two guaianolides and two seco-guaianols.
TL;DR: In this paper, the authors investigated four species from the subtribe Mutisiinae and found eight new monoterpenes, seven 5-methyl coumarins, two closely related 5methyl chromones, two coumarane derivatives, a p-hydroxy acetophenone derivative and a new C14-acetylene.
TL;DR: In this paper, the X-ray structural analysis shows for all three compounds an angle of 31 to 36° between the planes of the two cyclopentadienyl rings and a shielding of the lone pair of electrons at the metal atom by three of the ten benzyl groups each.
Abstract: Germaniumdiiodid, Zinndichlorid bzw. Bleidiacetat reagiert mit Pentabenzylcyclopentadienyllithium (1) unter Bildung von Decabenzylgermanocen (2), Decabenzylstannocen (3) bzw. Decabenzylplumbocen (4). Die luftstabilen Metallocene wurden durch IR-, Raman-, NMR-, 119mSn-Mosbauer- (3) und Massenspektren charakterisiert. Die Rontgenstrukturanalyse der Verbindungen zeigt, das die Ebenen der beiden Cyclopentadienylringe einen Winkel zwischen 31 und 36° einschliesen, und das eine Abschirmung des freien Elektronenpaares am Metallatom jeweils durch drei der zehn Benzylgruppen erfolgt.
Decabenzylgermanocene, -stannocene and -plumbocene. Synthesis and Structure of Air-stable Metallocenes of Main Group IV
Germanium diiodide, tin dichloride, or lead diacetate reacts with pentabenzylcyclopentadienyllithium (1) to give decabenzylgermanocene (2), decabenzylstannocene (3) or decabenzylplumbocene (4), respectively. The air-stable metallocenes were characterized by IR, Raman, NMR, tin-119m-Mossbauer (3), and mass spectroscopy. The X-ray structural analysis shows for all three compounds an angle of 31 to 36° between the planes of the two cyclopentadienyl rings and a shielding of the lone pair of electrons at the metal atom by three of the ten benzyl groups each.
TL;DR: In the MP4(SDTQ)/6-311G★★/MP2/6-31G★★+ ZPE level of theory, HeBCH is predicted to be unstable towards helium dissociation by −6.0 kcalmol, but HeBeO is calculated to be a stable molecule by + 3.2 kcalmol as mentioned in this paper.