University of Stuttgart

About: University of Stuttgart is a education organization based out in Stuttgart, Germany. It is known for research contribution in the topics: Laser & Finite element method. The organization has 27715 authors who have published 56370 publications receiving 1363382 citations. The organization is also known as: Universität Stuttgart.

Direct measurement of critical Casimir forces

Abstract: When fluctuating fields are confined between two surfaces, long-range forces arise. A famous example is the quantum-electrodynamical Casimir force that results from zero-point vacuum fluctuations confined between two conducting metal plates1. A thermodynamic analogue is the critical Casimir force: it acts between surfaces immersed in a binary liquid mixture close to its critical point and arises from the confinement of concentration fluctuations within the thin film of fluid separating the surfaces2. So far, all experimental evidence for the existence of this effect has been indirect3,4,5. Here we report the direct measurement of critical Casimir force between a single colloidal sphere and a flat silica surface immersed in a mixture of water and 2,6-lutidine near its critical point. We use total internal reflection microscopy to determine in situ the forces between the sphere and the surface, with femtonewton resolution6. Depending on whether the adsorption preferences of the sphere and the surface for water and 2,6-lutidine are identical or opposite, we measure attractive and repulsive forces, respectively, that agree quantitatively with theoretical predictions and exhibit exquisite dependence on the temperature of the system. We expect that these features of critical Casimir forces may result in novel uses of colloids as model systems.

Electrodynamics of Solids: Optical Properties of Electrons in Matter

Abstract: 1. Introduction Part I. Concepts and Properties: 2. The interaction of radiation with matter 3. General properties of the optical constants 4. The medium: correlation and response functions 5. Metals 6. Semiconductors 7. Broken-symmetry states of metals Part II. Methods: 8. Techniques: general considerations 9. Propagation and scattering of electromagnetic waves 10. Spectroscopic principles 11. Measurement configurations Part III. Experiments: 12. Metals 13. Semiconductors 14. Broken-symmetry states of metals Appendix A. Fourier and Laplace transformation Appendix B. Medium of finite thickness Appendix C. k.p perturbation theory Appendix D. Sum rules Appendix E. Non-local response Appendix F. Dielectric response in reduced dimensions Appendix G. Important constants and units.

The CoNLL-2009 Shared Task: Syntactic and Semantic Dependencies in Multiple Languages

Abstract: For the 11th straight year, the Conference on Computational Natural Language Learning has been accompanied by a shared task whose purpose is to promote natural language processing applications and evaluate them in a standard setting. In 2009, the shared task was dedicated to the joint parsing of syntactic and semantic dependencies in multiple languages. This shared task combines the shared tasks of the previous five years under a unique dependency-based formalism similar to the 2008 task. In this paper, we define the shared task, describe how the data sets were created and show their quantitative properties, report the results and summarize the approaches of the participating systems.

Neurodegenerative and neuroprotective effects of tumor Necrosis factor (TNF) in retinal ischemia: opposite roles of TNF receptor 1 and TNF receptor 2.

Abstract: Tumor necrosis factor (TNF) is an important factor in various acute and chronic neurodegenerative disorders. In retinal ischemia, we show early, transient upregulation of TNF, TNF receptor 1 (TNF-R1), and TNF-R2 6 hr after reperfusion preceding neuronal cell loss. To assess the specific role of TNF and its receptors, we compared ischemia-reperfusion-induced retinal damage in mice deficient for TNF-R1, TNF-R2, or TNF by quantifying neuronal cell loss 8 d after the insult. Surprisingly, TNF deficiency did not affect overall cell loss, yet absence of TNF-R1 led to a strong reduction of neurodegeneration and lack of TNF-R2 led to an enhancement of neurodegeneration, indicative of TNF-independent and TNF-dependent processes in the retina, with TNF-R1 augmenting neuronal death and TNF-R2 promoting neuroprotection. Western blot analyses of retinas revealed that reduction of neuronal cell loss in TNF-R1/ animals correlated with the presence of activated Akt/protein kinase B (PKB). Inhibition of the phosphatidylinositol 3-kinase signaling pathway reverted neuroprotection in TNF-R1-deficient mice, indicating an instrumental role of Akt/PKB in neuroprotection and TNF-R2 dependence of this pathway. Selective inhibition of TNF-R1 function may represent a new approach to reduce ischemia-induced neuronal damage, being potentially superior to strategies aimed at suppression of TNF activity in general.