Refine
Year of publication
- 1998 (1690) (remove)
Document Type
- Article (1133)
- Monograph/Edited Volume (288)
- Doctoral Thesis (110)
- Review (104)
- Preprint (32)
- Other (10)
- Postprint (8)
- Part of Periodical (5)
Language
Keywords
- manifolds with singularities (3)
- 'eta' invariant (2)
- Deutschland (2)
- European Union (2)
- Europäische Union (2)
- Fredholm property (2)
- Germany (2)
- differential operators (2)
- elliptic complexes (2)
- holomorphic solution (2)
- index (2)
- pseudodifferential operators (2)
- singular partial differential equation (2)
- Absorptionsspektroskopie (1)
- Atiyah-Patodi-Singer theory (1)
- Baskenland (1)
- Basque Region (1)
- Belgien (1)
- Belgium (1)
- Bodenwassergehalt (1)
- Brandenburg (1)
- Catalonia (1)
- Chern character (1)
- Coracis garrulus (1)
- E-SAR (1)
- Egypt (1)
- Elliptic equation with order degeneration (1)
- Fluideinschluss (1)
- Fluoreszenzspektroskopie (1)
- Fredholm operators (1)
- German-Polish Relationship (1)
- Gesteinsbildung (1)
- Great Britain (1)
- Großbritannien (1)
- Hodge theory (1)
- Huminstoffe (1)
- Iran (1)
- Israel (1)
- Jemen (1)
- Judentum (1)
- Katalonien (1)
- Lefschetz fixed point formula (1)
- Lefschetz number (1)
- Middle East (1)
- Mikroanalyse (1)
- Naher Osten (1)
- Non-linear (1)
- Nonlinear (1)
- Ostantarktis (1)
- Palestine (1)
- Palästina (1)
- Pegmatoid (1)
- Poland (1)
- Polen (1)
- Radardaten (1)
- Regionalisierung (1)
- Regionalism (1)
- Regionalismus (1)
- Rhenium(V) (1)
- SAK (1)
- SIR-C/X-SAR (1)
- SPECT (1)
- Sillimanit (1)
- Spektroskopie (1)
- Summenparameter (1)
- Tikhonov regularization (1)
- Transformation (1)
- Transition metal complexes (1)
- Vanadium(IV) (1)
- Weyl algebras bundle (1)
- Yemen (1)
- aerosol size distribution (1)
- attenuated Radon transform (1)
- bar with variable cross-section (1)
- bending of an orthotropic cusped plate (1)
- boundary value problems (1)
- cohomology (1)
- conical singularities (1)
- contact transformations (1)
- cusped bar (1)
- deutsch-polnische Beziehungen (1)
- elastic bar (1)
- elliptic operator (1)
- ellipticity (1)
- energetic space (1)
- gauge group (1)
- home range (1)
- index formulas (1)
- index of elliptic operator (1)
- integral formulas (1)
- inverse ill-posed problem (1)
- manifolds with conical singularities (1)
- manifolds with edges (1)
- meromorphic family (1)
- moduli space of flat connections (1)
- molecular mechanics (1)
- monodromy matrix (1)
- multilayered coated and absorbing aerosol (1)
- multiwavelength lidar (1)
- new recursive algorithm (1)
- nonlinear invers problem (1)
- nonlinear optimization (1)
- polyzyklische aromatische Kohlenwasserstoffe (1)
- pseudodiferential operators (1)
- pseudodifferential operator (1)
- quantization (1)
- quantum mechanical calculation (1)
- regularizer (1)
- regularizers (1)
- relative cohomology (1)
- residue (1)
- spectral boundary value problems (1)
- star-product (1)
- symplectic reduction (1)
- territorial behaviour (1)
- territory (1)
- tomogrphy (1)
- weighted Sobolev space (1)
- Ägypten (1)
- ∂-operator (1)
Institute
- Institut für Physik und Astronomie (174)
- Institut für Mathematik (129)
- Wirtschaftswissenschaften (122)
- Institut für Biochemie und Biologie (106)
- Historisches Institut (102)
- Institut für Geowissenschaften (75)
- Sozialwissenschaften (74)
- Institut für Romanistik (69)
- Department Erziehungswissenschaft (63)
- Department Psychologie (59)
Biomacht - Biopolitik
(1998)
Dieses Heft der Potsdamer Studien zur Frauen- und Geschlechterforschung hat den thematischen Schwerpunkt „Biomacht - Biopolitik“ und präsentiert Ergebnisse aus Forschungsprojekten, die in den letzten Jahren am Lehrstuhl Frauenforschung an der Wirtschafts- und Sozialwissenschaftlichen Fakultät der Universität Potsdam realisiert wurden. Inhalt: „Gebärstreik“ im Osten? Wie Sterilisation in einer Pressekampagne diskursiviert wurde und welche Motive ostdeutsche Frauen hatten, sich sterilisieren zu lassen. (Irene Dölling, Daphne Hahn, Sylka Scholz) Sterilisation und Individualisierung: Biopolitik in der DDR (Daphne Hahn)
The nonlinear interaction of waves excited by the modified two-stream instability (Farley-Buneman instability) is considered. It is found that, during the linear stage of wave growth, the enhanced pressure of the high-frequency part of the waves locally generates a ponderomotive force. This force acts on the plasma particles and redistributes them. Thus an additional electrostatic polarization field occurs, which influences the low-frequency part of the waves. Then, the low-frequency waves also cause a redistribution of the high-frequency waves. In the paper, a self-consistent system of equations is obtained, which describes the nonlinear interaction of the waves. It is shown that the considered mechanism of wave interaction causes a nonlinear stabilization of the high-frequency waves’ growth and a formation of local density structures of the charged particles. The density modifications of the charged particles during the non-linear stage of wave growth and the possible interval of aspect angles of the high-frequency waves are estimated.
Contents: 1 Introduction 2 Formation and destruction of sporadic E-layers 3 Temporal variations of parameters of sporadic E-layers during earthquake preparation 3.1 Temporal variations of fbEs with time-scales of a few hours 3.2 Study of fbEs variations with characteristic time-scales of 0.5-3 hours 3.3 Variations of the parameters of sporadic E-layers with characteristic time-scales of 15-45 minutes 3.4 Sporadic E-layer variations with characteristic time-scales of 2-15 minutes 4 On the spatial scales of sporadic E-layer disturbances related to seismic activity 5 Complex experimental researches of the ionosphere, electromagnetic noise and the geomagnetic field 5.1 Ionospheric and electromagnetic phenomena of the Kayraccum earthquake in 1985 5.2 Comparison of anomalies with characteristic time-scales of 2-3 hours for ionospheric E- and F-layers, and temporal behaviour of electromagnetic noise emission intensity 5.3 Night airglow emissions in the E-region before earthquakes and sporadic E-layer variations 6 Physical models of lithosphere-ionosphere links 6.1 Lithosphere-ionosphere links due to AGW 6.2 Electromagnetic models for the lithosphere-ionosphere coupling 6.3 Sporadic E-layers as current generators 7 Discussion and conclusion
In single photon emission computed tomography (SPECT) one is interested in reconstructing the activity distribution f of some radiopharmaceutical. The data gathered suffer from attenuation due to the tissue density µ. Each imaged slice incorporates noisy sample values of the nonlinear attenuated Radon transform (formular at this place in the original abstract) Traditional theory for SPECT reconstruction treats µ as a known parameter. In practical applications, however, µ is not known, but either crudely estimated, determined in costly additional measurements or plainly neglected. We demonstrate that an approximation of both f and µ from SPECT data alone is feasible, leading to quantitatively more accurate SPECT images. The result is based on nonlinear Tikhonov regularization techniques for parameter estimation problems in differential equations combined with Gauss-Newton-CG minimization.
The aim of this paper is to describe an efficient strategy for descritizing ill-posed linear operator equations of the first kind: we consider Tikhonov-Phillips-regularization χ^δ α = (a * a + α I)^-1 A * y ^δ with a finite dimensional approximation A n instead of A. We propose a sparse matrix structure which still leads to optimal convergences rates but requires substantially less scalar products for computing A n compared with standard methods.
The determination of the atmospheric aerosol size distribution is an inverse illposed problem. The shape and the material composition of the air-carried particles are two substantial model parameters. Present evaluation algorithms only used an approximation with spherical homogeneous particles. In this paper we propose a new numerically efficient recursive algorithm for inhomogeneous multilayered coated and absorbing particles. Numerical results of real existing particles show that the influence of the two parameters on the model is very important and therefore cannot be ignored.
We have numerically studied the bifurcations and transition to chaos in a two-dimensional fluid for varying values of the Reynolds number. These investigations have been motivated by experiments in fluids, where an array of vortices was driven by an electromotive force. In these experiments, successive changes leading to a complex motion of the vortices, due to increased forcing, have been explored [Tabeling, Perrin, and Fauve, J. Fluid Mech. 213, 511 (1990)]. We model this experiment by means of two-dimensional Navier-Stokes equations with a special external forcing, driving a linear chain of eight counter-rotating vortices, imposing stress-free boundary conditions in the vertical direction and periodic boundary conditions in the horizontal direction. As the strength of the forcing or the Reynolds number is raised, the original stationary vortex array becomes unstable and a complex sequence of bifurcations is observed. Several steady states and periodic branches and a period doubling cascade appear on the route to chaos. For increasing values of the Reynolds number, shear flow develops, for which the spatial scale is large compared to the scale of the forcing. Furthermore, we have investigated the influence of the aspect ratio of the container as well as the effect of no-slip boundary conditions at the top and bottom, on the bifurcation scenario.
This paper deals with the electrical conductivity problem in geophysics. It is formulated as an elliptic boundary value problem of second order for a large class of bounded and unbounded domains. A special boundary condition, the so called "Complete Electrode Model", is used. Poincaré inequalities are formulated and proved in the context of weighted Sobolev spaces, leading to existence and uniqueness statements for the boundary value problem. In addition, a parameter-to-solution operator arising from the inverse conductivity problem in medicine (EIT) and geophysics is investigated mathematically and is shown to be smooth and analytic.
The stability of the quiescent ground state of an incompressible, viscous and electrically conducting fluid sheet, bounded by stress-free parallel planes and driven by an external electric field tangential to the boundaries, is studied numerically. The electrical conductivity varies as cosh–2(x1/a), where x1 is the cross-sheet coordinate and a is the half width of a current layer centered about the midplane of the sheet. For a <~ 0.4L, where L is the distance between the boundary planes, the ground state is unstable to disturbances whose wavelengths parallel to the sheet lie between lower and upper bounds depending on the value of a and on the Hartmann number. Asymmetry of the configuration with respect to the midplane of the sheet, modelled by the addition of an externally imposed constant magnetic field to a symmetric equilibrium field, acts as a stabilizing factor.
The bifurcations in a three-dimensional incompressible, electrically conducting fluid with an external forcing of the Roberts type have been studied numerically. The corresponding flow can serve as a model for the convection in the outer core of the Earth and is realized in an ongoing laboratory experiment aimed at demonstrating a dynamo effect. The symmetry group of the problem has been determined and special attention has been paid to symmetry breaking by the bifurcations. The nonmagnetic, steady Roberts flow loses stability to a steady magnetic state, which in turn is subject to secondary bifurcations. The secondary solution branches have been traced until they end up in chaotic states.
Die Anwendung von optischen Parametern zur Stoffcharakterisierung wird diskutiert. Dabei ist der Schwerpunkt der Diskussion auf absorptions- und fluoreszenzspektroskopische Methoden gesetzt. Beide Methoden können schnell und zuverlässig – auch im on-line Betrieb – eingesetzt werden. Der Beitrag soll einen Überblick über die grundlegenden Möglichkeiten der Anwendung beider Methoden geben.
Inhalt: 1 Die Trias wohlfahrtsstaatlicher Regimes 2 Der kulturelle und institutionelle Bezugsrahmen in den drei Modell-Ländern: Deutschland, Norwegen, USA 3 Die Operationalisierung der Berufsstrukturen mit Hilfe der international Standard Classification of Occupations 1968 (ISCO1968) 4 Schichtselbsteinstufung und Einstellungsindex zu staatlicher Intervention auf Basis des International Social Survey Programme 1992 (ISSP1992) 5 Schichtselbsteinstufung und Einstellungsindex zur Frauenerwerbstätigkeit auf Basis des International Social Survey Programme 1994 (ISSP1994)
Ziel der Arbeit ist es, einen Vorschlag zur Untersuchung des Mikro-Makro Links zu unterbreiten. Die zentrale These ist, daß die in der westlichen Welt entstandenen Wohlfahrtsstaaten seit ihrer Entstehung wesentlich die Einstellungen der in ihnen lebenden Bevölkerung beeinflußt haben. Inhalt: Die Unterscheidung von Wohlfahrtsstaaten Die Untersuchung von Mikro- Makrozusammenhängen Der Zusammenhang zwischen wohlfahrtsstaatlichen Regimetypen und individuellen Einstellungen - Der Markt-Staat Index - Der Akzeptanz arbeitender Mütter Index
The fiscal reform of 1994 was introduced to strengthen the redistributive function of central government. In the aftermath of the reform it turned out, however, that the dominating cleavage is not necessarily the rivalry between "centre" and "regions", mainly because of the very complex relationships within the provinces. Though taxation itself is highly centralized there is a growing tendency of expensation of "extra-budget revenues". That is why the share of the central government concerning all revenues fell to 27%, falling considerably short of the purpose of the fiscal reform to increase the rate of central redistribution to 60% of the national fiscal ressources. Local communities have turned out to be rather successful in collecting non-tax revenues, concentrating on the non-state sectors of the economy. The problem is not so much the threat of fiscal decentralization but the definition of rules and procedures in the relationship between centre, provinces and local administrations.
In 1988, the Government of the People’s Republic of China established the island of Hainan as a province and made it a Special Economic Zone. While the hope for a spectecular economic take off was the main driving force behind this decision, it provided China with an area where far reaching trial-and-error politics could be. Hence the new provincial government was granted the privilege of setting its own legal framework for administering the special economic policies and establishing a governmental structure guided by the principle of "Small government, big society". Although some of the efforts to reduce the administration in terms of scope and resources, to develop and strengthen non-governmental organizations and provide economic actors with a minimum of freedom and reliability proved successful, the overall results are mixed: While well-being and opportunities for self-fulfillment clearly grew, political participation is still confined to areas defined by the Communist Party.
Auf der Suche nach einem neuen Ideal : zu Theorie, Norm und Praxis des Rechtsstaats in der VR China
(1998)
Besides establishing a legal system for the needs of economic construction, legal theory and legislation in China are extending their concern from an instrumental concept of law to a more value based notion, thus supplementing "rule by laws" by elements of the "Rechtsstaat" (rule of law). Whereas legal and constitutional theory take more and more bold views concerning integrating structures of checks and balances and division of powers into the legal system, urging for statutory control of the ruling party, for reforming the National People’s Congress into a responsible legislative body based on real representation of the people, providing for constitutionality of legal norms by a system of judicial review etc., legislation has started to deal with certain aspects of the Rechtsstaat in fields as administrative, criminal and criminal procedure law. In view of grave problems of implementation, this legislation may partly be regarded more to be an expression of intention to develop gradually a new ideal and a new legitimation for the political system than well established actual practice.
In August 1997 the Australian Government released the first White Paper ever issued on its foreign policy. As one important element, this essay tries to delineate the pro Asia-Pacific shift of Australia’s international economic and security orientations, particularly since the early 1970s - a foreign policy which could rest upon an certain bipartisan basis. The recently launched White Paper represents a new reflection upon Australia’s national interests and a soft relativisation of the strong emphasis on regional and multilateral foreign policy performances of former governments. According to a least the author’s judgement, the fundamental legacy of Australia’s international relations remain: a certain (a definite?) contradiction between the country’s predominant cultural and ethnic (!) heritage on the one hand and its geographical location on the other.
Since 1989 the German-Czech relationship has been burdened by the problem of a just assessment of World War II and the following forced transfer of the Sudeten Germans. Why are democrats on both sides who acknowledge the same values and principles unable to reach an agreement about crucial events in the past? The political and legal differences imply a moral dissent which is not being discussed systematically. The article tries to investigate the deficits of the moral arguments on both sides.
The economic reforms in the German Democratic Republic during the 60s, known as "New Economic System" (NES) or "Economic System of Socialism" (ESS) have been characterised by historians as truly technocratic. What is often not known is the fact, that during the first debate on economic reform in Eastern Germany in 1954-1958 the idea of democratic reform was prominent thanks to the role and writing of the outstanding GAR economist Fritz Behrens, who favoured a diminished role of the state in the economy and the self-rule of the workers in the factories. Behrens and his followers were denounced by party leader Walter Ulbricht as "revisionist". Together with his economic advisor, Wolfgang Berger, originally a scholar of Behrens’, he started the NES and ESS in the 60s. Behrens remained barred from the management of the reform, in which Berger plaid a prominent role. When Behrens began again to publish his demands for a democratic reform in 1967, thus intervening in the progress of the reform, he was forced to leave his academic job into retirement. In 1971, Erich Honekker succeeded Ulbricht. The economic reform was stopped. And Berger lost his job, too.
Nowadays the term "technocracy", which means the elimination of politics by the rule of scientific reasoning, is most often used with a quite negative overtone. Technocrats are described as experts without morals, able to function in any kind of political system. Nevertheless one should remember that the technocratic idea contained from the very beginning a strong ethic element: conventional political power as an instrument of repression should be replaced by the rule of sciences as an instrument to improve human life. Although the idea of eliminating politics by "science-based" decisions of an autocratic leadership has been widely used to legitimate totalitarian rule, it is obvious, that clear technocratic reasoning and decision making do not go conform with the functioning of a totalitarian system. On the contrary, technic and technologic innovation accelerated the breakdown of totalitarianism. The complex character of modern societies calls for regulation by markets and pluralistic political systems. The evolution of our technical civilization improved the conditions for democratic selforganisation.