3,546 research outputs found
About the mass of certain second order elliptic operators
Let be a closed Riemannian manifold of dimension and let
, such that the operator is positive. If
is flat near some point and vanishes around , we can define the
mass of as the constant term in the expansion of the Green function of
at . In this paper, we establish many results on the mass of such
operators. In particular, if f:= \frac{n-2}{4(n-1)} \scal_g, i.e. if is
the Yamabe operator, we show the following result: assume that there exists a
closed simply connected non-spin manifold such that the mass is
non-negative for every metric as above on , then the mass is
non-negative for every such metric on every closed manifold of the same
dimension as .Comment: 39 page
Transparency in monetary policy
For some time now the buzzword 'transparency' has been bandied about in the media almost daily. For example, calls were made for greater transparency in the financial system in connection with developments in the Asian financial markets. But the call for greater transparency goes far beyond the financial markets. It is now regarded as a necessary part of "good governance" demanded of all economic policy makers. As the World Bank's chief economist Joseph Stiglitz put it: 'No one would dare say that they were against transparency (....): It would be like saying you were against motherhood or apple pie.' This paper focuses on transparency in monetary policy, in particular with respect to the European System of Central Bank
Ressourcenschutz in der umweltfreundlichen öffentlichen Beschaffung
Die Vertiefungsanalyse âRessourcenschutz in der umweltfreundlichen öffentlichen Beschaffungâ von Andreas Hermann (2018) untersucht die rechtlichen Ansatzpunkte, mit denen die Politik den Ressourcenschutz in der umweltfreundlichen Beschaffung in Deutschland stĂ€rken kann. Untersucht werden die Beschaffungsfelder âBau und Unterhalt von StraĂenâ, âBauen und Wohnenâ sowie âIT-Produkteâ. Dazu werden die umweltbezogenen Beschaffungskriterien zum Ressourcenschutz analysiert, die die EU selbst veröffentlicht hat sowie die nationalen Kriterien in Deutschland und den Niederlanden.
Der Ăberblick zeigt, dass es sich bei den untersuchten Umweltkriterien zum Ressourcenschutz um nicht rechtsverbindliche âEmpfehlungenâ an die öffentlichen Beschaffungsstellen handelt. Soll die Nutzung in der Praxis forciert werden, ist in ProgRess III zu prĂŒfen, ob und welche Kriterien auch verpflichtend im deutschen Beschaffungsrecht vorgeschrieben werden.
Bei der Beschaffung von IT-Produkten werden derzeit nur umweltfreundliche Beschaffungskriterien fĂŒr die Verbesserung der Produktlebensdauer (z. B. Design fĂŒr Haltbarkeit, Reparierbarkeit und NachrĂŒstung) empfohlen. Denn Kriterien und Nachweismöglichkeiten fĂŒr den umweltschonenden Abbau und die Weiterverarbeitung der mineralischen Rohstoffe, die in den IT-Produkten enthalten sind, existieren nicht. Um auch den umweltschonenden Abbau von Rohstoffen in der Beschaffung zu berĂŒcksichtigen, sollte die Politik und Forschung die Standardisierung von Umweltkriterien vorantreiben
Towards Comparative and Aggregate Vulnerability: An Analysis of Welfare Distributions in Rural Provinces in Thailand and Vietnam
Several measures of vulnerability to poverty have been suggested in the literature. In practise, only little is known about the robustness of vulnerability comparisons based on these often quite specific measures. The theory of stochastic orders can be applied to shed some light on such issues. In the DFG research project "Impact of Shocks on the Vulnerability to Poverty: Consequences for Development of Emerging Southeast Asian Economies" (DFG FOR 756), an extensive panel survey was carried out in six rural provinces of Thailand and Vietnam in 2007. We establish cumulative distribution functions for income and consumption at the provincial level and search for stochastic dominance relations between these distributions. Our comparisons allow for initial, but quite robust conclusions on welfare and provide benchmarks for assessing the vulnerability to poverty in the research regions. --welfare distribution,stochastic ordering,vulnerability
Mass endomorphism, surgery and perturbations
We prove that the mass endomorphism associated to the Dirac operator on a
Riemannian manifold is non-zero for generic Riemannian metrics. The proof
involves a study of the mass endomorphism under surgery, its behavior near
metrics with harmonic spinors, and analytic perturbation arguments
Recycling probability and dynamical properties of germinal center reactions
We introduce a new model for the dynamics of centroblasts and centrocytes in
a germinal center. The model reduces the germinal center reaction to the
elements considered as essential and embeds proliferation of centroblasts,
point mutations of the corresponding antibody types represented in a shape
space, differentiation to centrocytes, selection with respect to initial
antigens, differentiation of positively selected centrocytes to plasma or
memory cells and recycling of centrocytes to centroblasts. We use exclusively
parameters with a direct biological interpretation such that, once determined
by experimental data, the model gains predictive power. Based on the experiment
of Han et al. (1995b) we predict that a high rate of recycling of centrocytes
to centroblasts is necessary for the germinal center reaction to work reliably.
Furthermore, we find a delayed start of the production of plasma and memory
cells with respect to the start of point mutations, which turns out to be
necessary for the optimization process during the germinal center reaction. The
dependence of the germinal center reaction on the recycling probability is
analyzed.Comment: 30 pages, 8 figure
Dirac eigenspinors for generic metrics
We consider a Riemannian spin manifold (M,g) with a fixed spin structure. The
zero sets of solutions of generalized Dirac equations on M play an important
role in some questions arising in conformal spin geometry and in mathematical
physics. In this setting the mass endomorphism has been defined as the constant
term in an expansion of Green's function for the Dirac operator. One is
interested in obtaining metrics, for which it is not zero. In this thesis we
study the dependence of the zero sets of eigenspinors of the Dirac operator on
the Riemannian metric. We prove that on closed spin manifolds of dimension 2 or
3 for a generic Riemannian metric the non-harmonic eigenspinors have no zeros.
Furthermore we prove that on closed spin manifolds of dimension 3 the mass
endomorphism is not zero for a generic Riemannian metric.Comment: PhD thesis, 96 page
A quantum-group-like structure on noncommutative 2-tori
In this paper we show that in the case of noncommutative two-tori one gets in
a natural way simple structures which have analogous formal properties as Hopf
algebra structures but with a deformed multiplication on the tensor product
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