Refine
Year of publication
- 2000 (557) (remove)
Document Type
- Article (428)
- Monograph/Edited Volume (70)
- Preprint (29)
- Doctoral Thesis (27)
- Review (2)
- Working Paper (1)
Language
- English (557) (remove)
Keywords
- K-theory (3)
- elliptic operators (2)
- linking coefficients (2)
- 1799-1804 (1)
- 2D tomography (1)
- Alejandro de Humboldt en México (1)
- Atiyah-Bott condition (1)
- Atiyah-Patodi-Singer theory (1)
- Biomembranen (1)
- Crack theory (1)
Institute
- Institut für Physik und Astronomie (128)
- Institut für Mathematik (85)
- Institut für Biochemie und Biologie (68)
- Institut für Informatik und Computational Science (36)
- Wirtschaftswissenschaften (34)
- Department Psychologie (31)
- Institut für Chemie (28)
- Institut für Geowissenschaften (28)
- Department Linguistik (23)
- Institut für Ernährungswissenschaft (19)
- Institut für Umweltwissenschaften und Geographie (18)
- Sozialwissenschaften (10)
- Institut für Anglistik und Amerikanistik (9)
- Interdisziplinäres Zentrum für Dynamik komplexer Systeme (7)
- Institut für Jüdische Studien und Religionswissenschaft (5)
- Department Erziehungswissenschaft (4)
- Department Grundschulpädagogik (4)
- Institut für Germanistik (4)
- Philosophische Fakultät (4)
- Department Sport- und Gesundheitswissenschaften (3)
- Historisches Institut (2)
- MenschenRechtsZentrum (2)
- Zentrum für Gerechtigkeitsforschung (2)
- Öffentliches Recht (2)
- Bürgerliches Recht (1)
- Extern (1)
- Institut für Romanistik (1)
- Institut für Slavistik (1)
- Zentrum für Umweltwissenschaften (1)
Hyperidentities and clones
(2000)
The theory of hyperidentities generalises the equational theory of universal algebras and is applicable in several fields of science, especially in computer sciences. This book presents the theory of hyperidentities and its relation to clone identities. The basic concept of hypersubstitution is used to introduce the monoid of hypersubstitutions, hyperidentities, M-hyperidentities, solid and M-solid varieties. This work integrates into a coherent framework many results scattered throughout the literature over the last eighteen years. In addition, the book contains some applications of hyperidentities to the functional completenes problem in multiple-valued logic. The general theory is also extended to partial algberas. The last chapter contains a list of exercises and open problems with suggestions of future work in this area of research.
Tectonic evolution of an early Precambrian high-pressure granulite belt in the North China Craton
(2000)
A multidisciplinary study has been carried out to contribute to the understanding of the geologic evolution of the largest known occurrence of ultra-high-pressure (UHP) rocks on Earth, the Dabie Shan of eastern China. Geophysical data, collected along a ca. 20 km E-W trending seismic line in the eastern Dabie Shan, indicate that the crust comprises three layers. The upper crust has a homogeneously low reflectivity and exhibits roughly subhorizontal reflectors down to ca. 15 km. It is therefore interpreted to portray a crustal UHP slab thrust over non-UHP crust. An aprubt change in intensity and geometry of observed reflectors marks the boundary of a mid- to lower crustal zone which is present down to ca. 33 km. This crustal zone likely represents cratonal Yangtze crust that was unaffected by the Triassic UHP event and which has acted as the footwall during exhumation of the crustal wedge. Strong and continuous reflectors occurring at ca. 33-40 km depth most likely trace the Moho at the base of the crust. Any trace of a crustal root, that may have formed in response to collision tectonics, is therefore not preserved. A shollow tomographic velocity modell based on inversion of the first arrivals is constructed additionally. This model clearly images the distinct lithologies on both sides of the Tan Lu fault. Sediments to the east exhibit velocities of about 3.4 - 5.0 km* s^-1, whereas the gneisses have 5.2 - 6.0 km*s^-1. Geometry of velocity isolines may trace the structures present in the rocks. Thus the sediments dip shallowly towards the fault, whereas isoclinal folds are imaged to occur in the gneisses. Field data from the UHP unit of the Dabie Shan enables definition of basement-cover sequences that represent sections of the former passive margin of the Yangtze craton. One of the cover sequences, the Changpu unit, still displays a stratigraphic contact with basement gneisses, while the other, the Ganghe unit, includes no relative basement exposure. The latter unit is in tectonic contact with the basement of the former unit via a greenschist-facies blastomylonite. The Changpu unit is chiefly constituted by calc-arenitic metasediments intercalated with meta-basalts, whereas the Ganghe unit contains arenitic-volcanoclastic metasediments that are likewise associated with meta-basalts. The basement comprises a variety of felsic gneisses, ranging from preserved eclogitic- to greenschist-facies paragenesis, and locally contains mafic-ultramafic meta-plutons in addition to minor basaltic rocks. Metabasites of all lithologies are eclogite-facies or are retrogressed equivalents, which, with the exception of those from the Ganghe unit, bear coesite and thus testify to an UHP metamorphic overprint. Mineral chemistry of the analysed samples reveal large compositional variations among the main minerals, i.e. garnet and omphacite, indicating either distinct protoliths or different degrees of interaction with their host-rocks. Contents of ferric iron in low Fetot omphacites are determined by wet chemical titration and found to be rather high, i.e. 30-40 %. However, a even more conservative estimate of 50% is applied in the corresponding calculations, in order to be comparable with previous studies. Textural constraints and compositional zonation pattern are compatible with equilibrium conditions during peak metamorphism followed by a retrogressive overprint. P-T data are calculated with special focus on the application of the garnet-omphacite-phengite barometer, combined with Fe-Mg exchange thermometers. Maximum pressures range from 42-48 kbar (for the Changpu unit) to ~37 kbar (for the Ganghe unit and basement rocks). Temperatures during the eclogite metamorphism reached ca. 750 °C. Although the sample suite reveals variable peak-pressures, temperatures are in reasonable agreement. Pressure differences are interpreted to be due to strongly Ca-dominated garnet (up to 50 mol % grossular in the Changpu unit) and modification of peak-compositions during retrogressive metamorphism. The integrated geological data presented in this thesis allow it to be concluded that, i) basement and cover rocks are present in the Dabie Shan and both experienced UHP conditions ii) the Dabie Shan is the metamorphic equivalent of the former passive margin of the Yangtze craton iii) felsic gneisses undergoing UHP metamorphism are affected by volume changes due to phase transitions (qtz <-> coe), which directly influence the tectono-metamorphic processes iv) initial differences in temperature may account for the general lack of lower crustal rocks in UHP-facies
In her lifetime, Dymphna Cusack continually launched social critiques on the basis of her feminism, humanism, pacificism and anti-fascist/pro-Soviet stance. Recalling her experi-ences teaching urban and country schoolchildren in A Window in the Dark, she was particularly scathing of the Australian education system. Cusack agitated for educational reforms in the belief that Australian schools had failed to cultivate the desired liberal humanist subject: 'Neither their minds, their souls, nor their bodies were developed to make the Whole Man or the Whole Woman - especially the latter. For girls were encouraged to regard their place as German girls once did: Kinder, Küche, Kirche - Children, Kitchen and Church.' I suggest that postwar liberal humanism, with its goals of equality among the sexes and self-realisation or 'becoming Whole', created a popular demand for the romantic realism found in Cusack′s texts. This twentieth century form of humanism, evident in new ideas of the subject found in psychoanalysis, Western economic theory and Modernism, informed each of the global lobbies for peace and freedom that followed the destruction of World War II. Liberal ideas of the individual in society became synonymous with the humanist representations of gender in much of postwar, realistic literature in English-speaking countries. The individual, a free agent whose aim was to 'improve the life of human beings', was usually given the masculine gender. He was shown to achieve self-realisation through a commitment to the development of “mankind”, either materially or spiritually. Significantly, the majority of Cusack′s texts diverge from this norm by portraying women as social agents of change and indeed, as the central protagonists. Although the humanist goal of self-realisation seems to be best adapted to social realism, the generic conventions of popular romance also have humanist precepts, as Catherine Belsey has argued. The Happy End is contrived through the heroine′s mental submission to her physical desire for the previously rejected or criticised lover. As Belsey has noted, desire might be considered a deconstructive force which momentarily prevents the harmonious, permanent unification of mind and body because the body, at the moment of seduction, does not act in accord with the mind. In popular romance, however, desire usually leads to a relationship or proper union of the protagonists. In Cusack′s words, the heroine and hero become “whole men and women” through the “realistic” love story. Thus romance, like realism, seeks to stabilise gender relations, even though female desire is temporarily disruptive in the narrative. In the end, women and men become fully realised characters according to the generic conventions of the love story or the consummation of potentially subversive desire. It stayed anxieties associated with women seeking independence and self-realisation rather than traditional romance which signalled a threat to existing gender relations. I proposed that an analysis of gender in Cusack′s fiction is warranted, since these apparently unified, humanist representations of romantic realism belie the conflicting aims and actions of the gendered subjects in this historical period. For instance, when we examine women′s lives immediately after the war, we can identify in both East and West efforts initiated by women and men to reconstruct private/public roles. In order to understand how women were caught between “realism and romance”, I plan to deconstruct gender within the paradigm of this hybrid genre. By adopting a femininist methodology, new insights may be gained into the conflictual subjectivity of both genders in the periods of the interwar years, the Pacific and World Wars, the Cold War, the Australian Aboriginal Movement at the time of the Vietnam War, as well as the moment of second wave Western feminism in the seventies. My definition of romantic realism and the discourses that inform it are examined in chapters two and three. A deconstruction of femininity and the female subject is pursued in chapter four, when I argue that Cusack′s romantic narratives interact in different ways with social realism: romance variously fails, succeeds, is parodic or idealised. Applying Judith Butler′s philosophical ideas to literary criticism, I argue that this hybridisation of genre prevents the fictional subject from performing his or her gender. Like the “real” subject - actual women in society - the fictional protagonist acts in an unintelligible fashion due to the multifarious demands and constraints on her gender. Consequently, the gendering of the sexed subject produces a multiplicity of genders: Cusack′s women and men are constituted by differing and conflicting demands of the dichotomously opposed genres. Thus gender and sex become indefinite through their complex, inconsistent expression in the romantic realistic text. In other words, the popular combination of romance and realism leads to an explosion of the gender binary presupposed by both genres. Furthermore, a consideration of sexuality and race in chapter five leads to a more differentiated analysis of the humanist representations of gender in postwar fiction. The need to deconstruct these representations in popular and canonical literature is recapitulated in the final chapter of this Dissertation.
Polymers at membranes
(2000)
The surface of biological cells consists of a lipid membrane and a large amount of various proteins and polymers, which are embedded in the membrane or attached to it. We investigate how membranes are influenced by polymers, which are anchored to the membrane by one end. The entropic pressure exerted by the polymer induces a curvature, which bends the membrane away from the polymer. The resulting membrane shape profile is a cone in the vicinity of the anchor segment and a catenoid far away from it. The perturbative calculations are confirmed by Monte-Carlo simulations. An additional attractive interaction between polymer and membrane reduces the entropically induced curvature. In the limit of strong adsorption, the polymer is localized directly on the membrane surface and does not induce any pressure, i.e. the membrane curvature vanishes. If the polymer is not anchored directly on the membrane surface, but in a non-vanishing anchoring distance, the membrane bends towards the polymer for strong adsorption. In the last part of the thesis, we study membranes under the influence of non-anchored polymers in solution. In the limit of pure steric interactions between the membrane and free polymers, the membrane curves towards the polymers (in contrast to the case of anchored polymers). In the limit of strong adsorption the membrane bends away from the polymers.
This paper deals with the Mie scattering kernels for multi-spectral data. The kernels may be represented in form of power series. Furthermore, the singular-value spectrum and the degree of ill-posedness in dependence on the refractive index of the particles are numerically approximated. A special hybrid regularization technique allows us to determine via inversion the particle distributions of different types.
A numerical MHD model is developed to investigate acceleration and heating of both thermal and auroral plasma. This is done for magnetospheric flux tubes in which intensive field aligned currents flow. To give each of these tubes, the empirical Tsyganenko model of the magnetospheric field is used. The parameters of the background plasma outside the flux tube as well as the strength of the electric field of magnetospheric convection are given. Performing the numerical calculations, the distributions of the plasma densities, velocities, temperatures, parallel electric field and current, and of the coefficients of thermal conductivity are obtained in a self-consistent way. It is found that EIC turbulence develops effectively in the thermal plasma. The parallel electric field develops under the action of the anomalous resistivity. This electric field accelerates both the thermal and the auroral plasma. The thermal turbulent plasma is also subjected to an intensive heating. The increase of the plasma of the Earth's ionosphere. Besides, studying the growth and dispersion properties of oblique ion cyclotron waves excited in a drifting magnetized plasma, it is shown that under non-stationary conditions such waves may reveal the properties of bursts of polarized transverse electromagnetic waves at frequencies near the patron gyrofrequency.
Basing on recent solar models, the excitation of ion-acoustic turbulence in the weaklycollisional, fully and partially-ionized regions of the solar atmosphere is investigated. Within the frame of hydrodynamics, conditions are found under which the heating of the plasma by ion-acoustic type waves is more effective than the Joule heating. Taking into account wave and Joule heating effects, a nonlinear differential equation is derived, which describes the evolution of nonlinear ion-acoustic waves in the collisional plasma.
In this paper an analysis of the excitation conditions of mirror waves is done, which propagate parallel to an external magnetic field. There are found analytical expressions for the dispersion relations of the waves in case of different plasma conditions. These relations may be used in future to develop the nonlinear theory of mirror waves. In comparison with former analytical works, in the study the inuence of the magnetic field and nite temperatures of the ions parallel to the magnetic field are taken into account. Application is done for the earth's magnetosheath.
The end of culture?
(2000)
The topological significance of the spectral Atiyah-Patodi-Singer η-invariant is investigated. We show that twice the fractional part of the invariant is computed by the linking pairing in K-theory with the orientation bundle of the manifold. The Pontrjagin duality implies the nondegeneracy of the linking form. An example of a nontrivial fractional part for an even-order operator is presented.
In this thesis we use the gravitational lensing effect as a tool to tackle two rather different cosmological topics: the nature of the dark matter in galaxy halos, and the rotation of the universe. Firstly, we study the microlensing effect in the gravitational lens systems Q0957+561 and Q2237+0305. In these systems the light from the quasar shines directly through the lensing galaxy. Due to the relative motion of the quasar, the lensing galaxy, and the observer compact objects in the galaxy or galaxy halo cause brightness fluctuations of the light from the background quasar. We compare light curve data from a monitoring program of the double quasar Q0957+561 at the 3.5m telescope at Apache Point Observatory from 1995 to 1998 (Colley, Kundic & Turner 2000) with numerical simulations to test whether the halo of the lensing galaxy consists of massive compact objects (MACHOs). This test was first proposed by Gott (1981). We can exclude MACHO masses from 10^-6 M_sun up to 10^-2 M_sun for quasar sizes of less than 3x10^14 h_60^-0.5 cm if the MACHOs make up at least 50% of the dark halo. Secondly, we present new light curve data for the gravitationally lensed quadruple quasar Q2237+0305 taken at the 3.5m telescope at Apache Point Observatory from June 1995 to January 1998. Although the images were taken under variable, often poor seeing conditions and with coarse pixel sampling, photometry is possible for the two brighter quasar images A and B with the help from HST observations. We find independent evidence for a brightness peak in image A of 0.4 to 0.5 mag with a duration of at least 100 days, which indicates that microlensing has taken place in the lensing galaxy. Finally, we use the weak gravitational lensing effect to put limits on a class of Goedel-type rotating cosmologies described by Korotky & Obukhov (1996). In weak lensing studies the shapes of thousands of background galaxies are measured and averaged to reveal coherent gravitational distortions of the galaxy shapes by foreground matter distributions, or by the large-scale structure of space-time itself. We calculate the predicted shear as a function of redshift in Goedel-type rotating cosmologies and compare this to the upper limit on cosmic shear gamma_limit of approximately 0.04 from weak lensing studies. We find that Goedel-type models cannot have larger rotations omega than H_0=6.1x10^-11 h_60/year if this shear limit is valid for the whole sky.
Contents: 1. Capitalist societies as market-bargaining societies on the basis of resources of action: The idealtypical bargain between capital and labour; an alternative to Marx' theory of exploitation - Discussion of the model 2. A general typology of paths of societies in history and a characterisation of state socialism - People's capitalisms as perspective of development - What remains from Marx' ideas? 3. Variations of welfare capitalism after the decline of state socialism 3.1 National differences of welfare capitalism 3.2 Overall inequality of income and overall class consciousness 3.3 Explaining income inequality and variation in class consciousness by class and gender 3.3.1 A test of different class models in the FRG 3.3.2 Developing an international model of gendered occupational and employment status as bundles of resources of action 4. Summary
Prostaglandin F(2alpha) (PGF(2alpha)), modulates hepatocyte functions via a heptahelical G(q)-coupled PGF(2alpha)-receptor (FP-R) which in liver is expressed exclusively in hepatocytes. The aim of the present study was to isolate the 5'-flanking region of the rat FP-R gene and to elucidate its basal and IL-6-modulated transcription control function in rat hepatocytes. The 5'-non-translated region of the rat hepatocyte FP-R mRNA differed from the corresponding region in rat fetal astrocyte or corpus luteum. It was encoded by exons 1a and 2 which were separated by a 1. 4 kb intron containing the exons 1b and 1c coding for the 5'-untranslated region of rat fetal astrocyte and corpus luteum FP-R mRNA, respectively. The transcription initiation site in hepatocytes was localized 263 bp upstream of the start ATG by 5'-RACE. A DNA-fragment covering the 5'-flanking region of the rFP-R gene from - 1 of the transcription initiation site to -2590 bp was cloned and sequenced. Its 3'-two thirds had a 65% sequence identity to the mouse FP-R promoter however no homology to the bovine FP-R promoter. In the overlapping sequence most of the putative transcription factor binding sites were conserved between mouse and rat. The rat promoter contained no classical TATA- or CAAT-boxes but putative binding sites for the transcription factors C/EBP, GATA-1, HNF-1, HNF-3beta, SP-1, and USF. Luciferase reporter gene constructs containing portions of the 5'-flanking region were transfected into rat hepatocytes. Luciferase expression ranked -181 >/= -608 < -1418 > -1821 >/= -2590. The strongest transcriptional activity was conferred by the region between -608 and -1418 containing a cluster of potential HNF-1 and HNF-3beta binding sites that might allow the exclusive expression of FP-R mRNA in hepatocytes. The amount of FP-R mRNA and the luciferase expression under control of the -2590 promoter fragment were reduced by IL-6 in hepatocytes. Copyright 2000 Academic Press.
Prostanoids, that are released from nonparenchymal liver cells in response to proinflammatory stimuli, are involved in the regulation of hepatic functions during inflammation. They exert their effects on their target cells via heptahelical receptors in the plasma membrane. For the 5 prostanoids prostaglandin E(2) (PGE(2)), prostaglandin F(2alpha), prostaglandin D(2) (PGD(2)), prostacyclin, and thromboxane A(2) there exist 8 receptors that are coupled to different heterotrimeric G proteins. These receptors are expressed differentially in the 4 principal liver cell types, i.e., hepatocytes, Kupffer cells, sinusoidal endothelial cells, and hepatic stellate cells. It was intriguing, that the messenger RNA (mRNA) of none of the G(s)-coupled prostanoid receptors (DP-R, EP2-R, EP4-R, and IP-R) that can attenuate the inflammatory reaction were present in hepatocytes. The current study shows that the expression of the G(s)-coupled prostanoid receptors EP2-R, EP4-R, and DP-R, but not the IP-R, was efficiently and rapidly up-regulated by treatment of hepatocytes in vitro or rats in vivo with the key acute phase cytokine interleukin 6 (IL-6). In IL-6-treated hepatocytes PGE(2) in turn attenuated the IL-6-induced alpha(2)-macroglobulin formation via a cyclic adenosine monophosphate (cAMP)- dependent signal chain. The data indicate that an IL-6-mediated induction of the previously not expressed EP2-R and EP4- R on hepatocytes might establish a prostanoid-mediated feedback inhibition loop for the attenuation of the acute phase response.
Eight heptahelical receptors have been characterized for prostaglandin (PG) D(2), PGE(2), PGF(2alpha), prostacyclin and thromboxane A(2). They share a sequence identity of 40%. All of them have potential N-glycosylation sites. The current study analysed the role of the two N-glycosylation sites in the rat EP3beta-subtype PGE(2) receptor for protein folding and sorting. The N-glycosylation consensus sequences were eliminated by site-directed mutagenesis and receptors expressed in HEK-293 cells. Both potential N-glycosylation sites were used. Their joint elimination resulted in the synthesis of a receptor protein with full binding competence, biological activity and no reduction of affinity; however, the half-life of the non-glycosylated receptor was slightly reduced. Ligand binding to intact stably transfected cells and confocal laser microscopic immunocytochemistry showed that the glycosylated receptor was correctly inserted into the plasma membrane to a much larger extent than the non-glycosylated receptor, which tended to accumulate in the perinuclear zone of the endoplasmic reticulum. Inhibition of N-glycosylation with tunicamycin resulted in a similar perinuclear distribution of the wild-type receptor. Therefore, glycosylation of the EP3beta receptor seems not to be necessary for correct folding of the receptor protein but for the efficient transport of the receptor protein to the plasma membrane. This contrasts with a previous finding which described a reduction of the affinity for PGE(2) of the EP3alpha receptor by elimination of the distal glycosylation site when the receptor protein was expressed in insect cells.
We prove a general theorem on the behavior of the relative index under surgery for a wide class of Fredholm operators, including relative index theorems for elliptic operators due to Gromov-Lawson, Anghel, Teleman, Booß-Bavnbek-Wojciechowski, et al. as special cases. In conjunction with additional conditions (like symmetry conditions), this theorem permits one to compute the analytical index of a given operator. In particular, we obtain new index formulas for elliptic pseudodifferential operators and quantized canonical transformations on manifolds with conical singularities.
We continue the investigation of the calculus of Fourier Integral Operators (FIOs) in the class of symbols with exit behaviour (SG symbols). Here we analyse what happens when one restricts the choice of amplitude and phase functions to the subclass of the classical SG symbols. It turns out that the main composition theorem, obtained in the environment of general SG classes, has a "classical" counterpart. As an application, we study the Cauchy problem for classical hyperbolic operators of order (1, 1); for such operators we refine the known results about the analogous problem for general SG hyperbolic operators. The material contained here will be used in a forthcoming paper to obtain a Weyl formula for a class of operators defined on manifolds with cylindrical ends, improving the results obtained in [9].
The problem of analytic representation of integrable CR functions on hypersurfaces with singularities is treated. The nature o singularities does not matter while the set of singularities has surface measure zero. For simple singularities like cuspidal points, edges, corners, etc., also the behaviour of representing analytic functions near singular points is studied.
We prove the existence of Hp(D)-limit of iterations of double layer potentials constructed with the use of Hodge parametrix on a smooth compact manifold X, D being an open connected subset of X. This limit gives us an orthogonal projection from Sobolev space Hp(D) to a closed subspace of Hp(D)-solutions of an elliptic operator P of order p ≥ 1. Using this result we obtain formulae for Sobolev solutions to the equation Pu = f in D whenever these solutions exist. This representation involves the sum of a series whose terms are iterations of double layer potentials. Similar regularization is constructed also for a P-Neumann problem in D.