380 research outputs found

    The Rotating Elastic-Plastic Solid Shaft with Free Ends

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    Zur Spannungsverteilung in thermisch beanspruchten elastisch-plastischen Kreisscheiben bei einem speziellen nichtlinearen Verfestigungsgesetz

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    Lung epithelial apoptosis in influenza virus pneumonia: the role of macrophage-expressed TNF-related apoptosis-inducing ligand

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    Mononuclear phagocytes have been attributed a crucial role in the host defense toward influenza virus (IV), but their contribution to influenza-induced lung failure is incompletely understood. We demonstrate for the first time that lung-recruited “exudate” macrophages significantly contribute to alveolar epithelial cell (AEC) apoptosis by the release of tumor necrosis factor–related apoptosis-inducing ligand (TRAIL) in a murine model of influenza-induced pneumonia. Using CC-chemokine receptor 2–deficient (CCR2−/−) mice characterized by defective inflammatory macrophage recruitment, and blocking anti-CCR2 antibodies, we show that exudate macrophage accumulation in the lungs of influenza-infected mice is associated with pronounced AEC apoptosis and increased lung leakage and mortality. Among several proapoptotic mediators analyzed, TRAIL messenger RNA was found to be markedly up-regulated in alveolar exudate macrophages as compared with peripheral blood monocytes. Moreover, among the different alveolar-recruited leukocyte subsets, TRAIL protein was predominantly expressed on macrophages. Finally, abrogation of TRAIL signaling in exudate macrophages resulted in significantly reduced AEC apoptosis, attenuated lung leakage, and increased survival upon IV infection. Collectively, these findings demonstrate a key role for exudate macrophages in the induction of alveolar leakage and mortality in IV pneumonia. Epithelial cell apoptosis induced by TRAIL-expressing macrophages is identified as a major underlying mechanism

    Transfer of quantum states using finite resources

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    We discuss the problem of transfering a qubit from Alice to Bob using a noisy quantum channel and only finite resources. As the basic protocol for the transfer we apply quantum teleportation. It turns out that for a certain quality of the channel direct teleportation combined with qubit purification is superior to entanglement purification of the channel. If, however, the quality of the channel is rather low one should simply apply an estimation-preparation scheme.Comment: 9 pages RevTeX including 5 figures, replaced with revised version, to appear in Phys. Rev.

    Dynamics of entanglement between two trapped atoms

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    We investigate the dynamics of entanglement between two continuous variable quantum systems. The model system consists of two atoms in a harmonic trap which are interacting by a simplified s-wave scattering. We show, that the dynamically created entanglement changes in a steplike manner. Moreover, we introduce local operators which allow us to violate a Bell-CHSH inequality adapted to the continuous variable case. The correlations show nonclassical behavior and almost reach the maximal quantum mechanical value. This is interesting since the states prepared by this interaction are very different from any EPR-like state.Comment: 9 page

    Optimal estimation of qubit states with continuous time measurements

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    We propose an adaptive, two steps strategy, for the estimation of mixed qubit states. We show that the strategy is optimal in a local minimax sense for the trace norm distance as well as other locally quadratic figures of merit. Local minimax optimality means that given nn identical qubits, there exists no estimator which can perform better than the proposed estimator on a neighborhood of size n1/2n^{-1/2} of an arbitrary state. In particular, it is asymptotically Bayesian optimal for a large class of prior distributions. We present a physical implementation of the optimal estimation strategy based on continuous time measurements in a field that couples with the qubits. The crucial ingredient of the result is the concept of local asymptotic normality (or LAN) for qubits. This means that, for large nn, the statistical model described by nn identically prepared qubits is locally equivalent to a model with only a classical Gaussian distribution and a Gaussian state of a quantum harmonic oscillator. The term `local' refers to a shrinking neighborhood around a fixed state ρ0\rho_{0}. An essential result is that the neighborhood radius can be chosen arbitrarily close to n1/4n^{-1/4}. This allows us to use a two steps procedure by which we first localize the state within a smaller neighborhood of radius n1/2+ϵn^{-1/2+\epsilon}, and then use LAN to perform optimal estimation.Comment: 32 pages, 3 figures, to appear in Commun. Math. Phy

    The hard X-ray view of the low-luminosity blazar in the radio galaxy NGC6251

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    We present results from a BeppoSAX (July 2001) observation of the FRI radio galaxy NGC6251, together with a re-analysis of archival ASCA (October 1994) and Chandra (September 2000) data. The weak detection above 10 keV and the lack of iron fluorescent K-alpha emission lines in the BeppoSAX spectrum rule out that the bulk of the X-ray emission is due to an obscured Seyfert nucleus. The study of the multiwavelength spectral energy distribution suggests instead that X-rays probably originate as inverse-Compton of synchrotron seed photons in a relativistic jet, indicating that NGC6251 hosts a low radio luminosity [L(5 GHz) ~10^40 erg/s] blazar. The BeppoSAX spectrum is flatter than in the earlier ASCA observation. This might be due to the emergence of a different spectral component during phases of lower X-ray flux. In this context, we discuss some possible explanations for the intense and mildly-ionized fluorescent iron line measured by ASCA.Comment: 8 Latex pages, 6 figures, To appear in Astronomy & Astrophysic

    TRY plant trait database - enhanced coverage and open access

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    Plant traits-the morphological, anatomical, physiological, biochemical and phenological characteristics of plants-determine how plants respond to environmental factors, affect other trophic levels, and influence ecosystem properties and their benefits and detriments to people. Plant trait data thus represent the basis for a vast area of research spanning from evolutionary biology, community and functional ecology, to biodiversity conservation, ecosystem and landscape management, restoration, biogeography and earth system modelling. Since its foundation in 2007, the TRY database of plant traits has grown continuously. It now provides unprecedented data coverage under an open access data policy and is the main plant trait database used by the research community worldwide. Increasingly, the TRY database also supports new frontiers of trait-based plant research, including the identification of data gaps and the subsequent mobilization or measurement of new data. To support this development, in this article we evaluate the extent of the trait data compiled in TRY and analyse emerging patterns of data coverage and representativeness. Best species coverage is achieved for categorical traits-almost complete coverage for 'plant growth form'. However, most traits relevant for ecology and vegetation modelling are characterized by continuous intraspecific variation and trait-environmental relationships. These traits have to be measured on individual plants in their respective environment. Despite unprecedented data coverage, we observe a humbling lack of completeness and representativeness of these continuous traits in many aspects. We, therefore, conclude that reducing data gaps and biases in the TRY database remains a key challenge and requires a coordinated approach to data mobilization and trait measurements. This can only be achieved in collaboration with other initiatives
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