A hybrid computer study of a dynamic ship positioning system

Hybrid computer program for dynamic ship positioning syste

The Effect of Porosity on X-ray Emission Line Profiles from Hot-Star Winds

We investigate the degree to which the nearly symmetric form of X-ray emission lines seen in Chandra spectra of early-type supergiant stars could be explained by a possibly porous nature of their spatially structured stellar winds. Such porosity could effectively reduce the bound-free absorption of X-rays emitted by embedded wind shocks, and thus allow a more similar transmission of red- vs. blue-shifted emission from the back vs. front hemispheres. For a medium consisting of clumps of size l and volume filling factor f, in which the `porosity length' h=l/f increases with local radius as h = h' r, we find that a substantial reduction in wind absorption requires a quite large porosity scale factor h' > 1, implying large porosity lengths h > r. The associated wind structure must thus have either a relatively large scale l~ r, or a small volume filling factor f ~ l/r << 1, or some combination of these. The relatively small-scale, moderate compressions generated by intrinsic instabilities in line-driving seem unlikely to give such large porosity lengths, leaving again the prospect of instead having to invoke a substantial (ca. factor 5) downward revision in assumed mass-loss rates.Comment: 6 pages in apj-emulate; 3 figures; submitted to Ap

Psalm Lxxvi and Othlr Psalms for the Feast of Tabernacles

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Quantum diagonalization of Hermitean matrices

To measure an observable of a quantum mechanical system leaves it in one of its eigenstates and the result of the measurement is one of its eigenvalues. This process is shown to be a computational resource: Hermitean (N ×N) matrices can be diagonalized, in principle, by performing appropriate quantum mechanical measurements. To do so, one considers the given matrix as an observable of a single spin with appropriate length s which can be measured using a generalized Stern-Gerlach apparatus. Then, each run provides one eigenvalue of the observable. As the underlying working principle is the `collapse of the wavefunction' associated with a measurement, the procedure is neither a digital nor an analogue calculation - it defines thus a new example of a quantum mechanical method of computation

Liver transplantation in mainland China: the overview of CLTR 2011 annual scientific report

China Liver Transplant Registry (CLTR) is the official national liver transplant registry in Mainland China that has been authorized by the National Health and Family Planning Commission of the People's Republic of China (NHFPC) and serves for both regulatory and scientific purposes. The CLTR 2011 annual scientific reports released national statistics describing current status of liver transplant (LT) in China. This article, as an accompanying document of CLTR 2011 annual scientific report, provides an overview of scientific results for LT in China. Up to December 2011, a total number of 20,877 LT performed during 1980-2011 in 81 certified transplant centers had been reported to CLTR. Of these donated livers, 92.63% were procured from deceased donors (N=19,338) and 7.37% were from living donors (N=1,539). In March 2010, the pilot project of the new deceased organ donation was initiated. From the initiation of the pilot program to the end of 2011, there were 115 LT (0.55% of all LT) using the liver grafts from Chinese categories donors. The recipient post-transplant survival had been significantly improved over years. The median post-transplant follow-up was 14.74 months, of which the longest follow-up time was 192.47 months. The 1-year, 3-year and 5-year cumulative survival rate for all recipients was 77.97%, 65.38% and 60.53%, respectively.published_or_final_versio

XII.—Excavations on the site of the Roman city at Silchester, Hants, in 1900.

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How to determine a quantum state by measurements: The Pauli problem for a particle with arbitrary potential

The problem of reconstructing a pure quantum state ¿¿> from measurable quantities is considered for a particle moving in a one-dimensional potential V(x). Suppose that the position probability distribution ¿¿(x,t)¿2 has been measured at time t, and let it have M nodes. It is shown that after measuring the time evolved distribution at a short-time interval ¿t later, ¿¿(x,t+¿t)¿2, the set of wave functions compatible with these distributions is given by a smooth manifold M in Hilbert space. The manifold M is isomorphic to an M-dimensional torus, TM. Finally, M additional expectation values of appropriately chosen nonlocal operators fix the quantum state uniquely. The method used here is the analog of an approach that has been applied successfully to the corresponding problem for a spin system

Fiber transport of spatially entangled photons

Entanglement in the spatial degrees of freedom of photons is an interesting resource for quantum information. For practical distribution of such entangled photons it is desireable to use an optical fiber, which in this case has to support multiple transverse modes. Here we report the use of a hollow-core photonic crystal fiber to transport spatially entangled qubits.Comment: 4 pages, 4 figure