448 research outputs found

    National Geodetic Satellite Program, Part II: Smithsonian Astrophysical Observatory

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    A sequence of advances in the determination of geodetic parameters presented by the Smithsonian Astrophysical Observatory are described. A Baker-Nunn photographic system was used in addition to a ruby-laser ranging system to obtain data for refinement of geodetic parameters. A summary of the data employed to: (1) derive coordinates for the locations of various tracking stations; and (2) determine the gravitational potential of the earth, is presented

    Strong interband Faraday rotation in 3D topological insulator Bi2Se3

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    The Faraday effect is a representative magneto-optical phenomenon, resulting from the transfer of angular momentum between interacting light and matter in which time-reversal symmetry has been broken by an externally applied magnetic field. Here we report on the Faraday rotation induced in the prominent 3D topological insulator Bi2Se3 due to bulk interband excitations. The origin of this non-resonant effect, extraordinarily strong among other non-magnetic materials, is traced back to the specific Dirac-type Hamiltonian for Bi2Se3, which implies that electrons and holes in this material closely resemble relativistic particles with a non-zero rest mass

    Crustal strain in central Greece from repeated GPS measurements in the interval 1989-1997

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    A 66-station GPS network spanning central Greece, first observed in 1989, has been occupied fully on three occasions: June 1989, October 1991 and May 1993. Subsets of this network bounding the Gulf of Korinthos have also been occupied in June 1995, October 1995, May 1996 and September/October 1997. The first three occupations were processed using a fiducial GPS methodology, whereas later surveys were processed using CODE precise orbits. Combination of data from different surveys to yield smooth site velocities requires global network translations at each epoch to compensate for errors in the realization of the reference frame. This method provides a posteriori estimates of the relative coordinate errors and reference frame noise. Only one earthquake, the 1995 June 15 Egion event, has caused significant local coseismic displacement, and its effects on the interseismic velocity field are removed using an elastic dislocation model. We constrain the orientation of the 100 yr triangulation—GPS velocity estimates of Davies et al. (1997) using 14 sites common to the two networks. The goodness of fit of this transformation indicates that the short-term and 100 yr geodetic estimates of deformation are highly compatible. We infer that short-term geodetic studies are capable of determining longer-term deformation rates provided that transient, local effects can be modelled. From the combined velocity field, we estimate principal strains and rigid-body rotation rates at points on a regular grid using data from neighbouring sites. Strain rates are high within the Gulf of Korinthos and much lower elsewhere. The extension rate across the Gulf of Korinthos increases from east to west. Comparison of the extension rate with historical and recent rates of seismic release of strain reveals significant medium-term seismic hazard in the western Gulf of Korinthos, and may also indicate long-term aseismic strai

    Experimental realisation of Shor's quantum factoring algorithm using qubit recycling

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    Quantum computational algorithms exploit quantum mechanics to solve problems exponentially faster than the best classical algorithms. Shor's quantum algorithm for fast number factoring is a key example and the prime motivator in the international effort to realise a quantum computer. However, due to the substantial resource requirement, to date, there have been only four small-scale demonstrations. Here we address this resource demand and demonstrate a scalable version of Shor's algorithm in which the n qubit control register is replaced by a single qubit that is recycled n times: the total number of qubits is one third of that required in the standard protocol. Encoding the work register in higher-dimensional states, we implement a two-photon compiled algorithm to factor N=21. The algorithmic output is distinguishable from noise, in contrast to previous demonstrations. These results point to larger-scale implementations of Shor's algorithm by harnessing scalable resource reductions applicable to all physical architectures.Comment: 7 pages, 3 figure

    Investigating dietary life histories and mobility of children buried in St Gertrude Church Cemetery, Riga, Latvia (15th– 17th centuries AD)

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    Carbon and nitrogen isotope profiles were obtained from incremental dentine analysis of 19 non‐adults from a cemetery in Riga, Latvia. The research compared the life histories and diet between people buried in two mass graves and the general cemetery. The δ13C profiles of several children from the mass graves were similar but did not resemble the patterns seen in children from the general cemetery, suggesting that they probably represented a different population group. The rise in δ15N values towards the end of the life of four individuals from one mass grave suggests they were victims of an historically documented famine

    The Classic: Bone Morphogenetic Protein

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    This Classic Article is a reprint of the original work by Marshall R. Urist and Basil S. Strates, Bone Morphogenetic Protein. An accompanying biographical sketch of Marshall R. Urist, MD is available at DOI 10.1007/s11999-009-1067-4; a second Classic Article is available at DOI 10.1007/s11999-009-1069-2; and a third Classic Article is available at DOI 10.1007/s11999-009-1070-9. The Classic Article is © 1971 by Sage Publications Inc. Journals and is reprinted with permission from Urist MR, Strates BS. Bone morphogenetic protein. J Dent Res. 1971;50:1392–1406

    Overview of power exhaust experiments in the COMPASS divertor with liquid metals

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    Power handling experiments with a special liquid metal divertor module based on the capillary porous system technology were performed in the tokamak COMPASS. The performance of two metals (Li and LiSn alloy) were tested for the first time in a divertor under ELMy H-mode conditions. No damage of the capillary mesh and a good exhaust capability were observed for both metals in two separate experiments with up to 12 MW/m(2) of deposited perpendicular, inter-ELM steady-state heat flux and with ELMs of relative energy similar to 3% and a local peak energy fluence at the module similar to 15 kJ.m(-2). No droplets were directly ejected from the mesh top surface and for the LiSn experiment, no contamination of the core and SOL plasmas by Sn was observed. The elemental depth profile analysis of 14 stainless-steel samples located around the vacuum vessel for each experiment provides information about the migration of evaporated/redeposited liquid elements

    Bcl-2 protein family: Implications in vascular apoptosis and atherosclerosis

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    Apoptosis has been recognized as a central component in the pathogenesis of atherosclerosis, in addition to the other human pathologies such as cancer and diabetes. The pathophysiology of atherosclerosis is complex, involving both apoptosis and proliferation at different phases of its progression. Oxidative modification of lipids and inflammation differentially regulate the apoptotic and proliferative responses of vascular cells during progression of the atherosclerotic lesion. Bcl-2 proteins act as the major regulators of extrinsic and intrinsic apoptosis signalling pathways and more recently it has become evident that they mediate the apoptotic response of vascular cells in response to oxidation and inflammation either in a provocative or an inhibitory mode of action. Here we address Bcl-2 proteins as major therapeutic targets for the treatment of atherosclerosis and underscore the need for the novel preventive and therapeutic interventions against atherosclerosis, which should be designed in the light of molecular mechanisms regulating apoptosis of vascular cells in atherosclerotic lesions

    One-Step Purification of Recombinant Human Amelogenin and Use of Amelogenin as a Fusion Partner

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    Amelogenin is an extracellular protein first identified as a matrix component important for formation of dental enamel during tooth development. Lately, amelogenin has also been found to have positive effects on clinical important areas, such as treatment of periodontal defects, wound healing, and bone regeneration. Here we present a simple method for purification of recombinant human amelogenin expressed in Escherichia coli, based on the solubility properties of amelogenin. The method combines cell lysis with recovery/purification of the protein and generates a >95% pure amelogenin in one step using intact harvested cells as starting material. By using amelogenin as a fusion partner we could further demonstrate that the same method also be can explored to purify other target proteins/peptides in an effective manner. For instance, a fusion between the clinically used protein PTH (parathyroid hormone) and amelogenin was successfully expressed and purified, and the amelogenin part could be removed from PTH by using a site-specific protease

    Collecting duct carcinoma of the kidney: an immunohistochemical study of 11 cases

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    BACKGROUND: Collecting duct carcinoma (CDC) is a rare but very aggressive variant of kidney carcinoma that arises from the epithelium of Bellini's ducts, in the distal portion of the nephron. In order to gain an insight into the biology of this tumor we evaluated the expression of five genes involved in the development of renal cancer (FEZ1/LZTS1, FHIT, TP53, P27(kip1), and BCL2). METHODS: We studied eleven patients who underwent radical nephrectomy for primary CDC. All patients had an adequate clinical follow-up and none of them received any systemic therapy before surgery. The expression of the five markers for tumor initiation and/or progression were assessed by immunohistochemistry and correlated to the clinicopathological parameters, and survival by univariate analysis. RESULTS: Results showed that Fez1 protein expression was undetectable or substantially reduced in 7 of the 11 (64%) cases. Fhit protein was absent in three cases (27%). The overexpression of p53 protein was predominantly nuclear and detected in 4 of 11 cases (36%). Immunostaining for p27 was absent in 5 of 11 cases (45.5%). Five of the six remaining cases (90%) showed exclusively cytoplasmic protein expression, where, in the last case, p27 protein was detected in both nucleus and cytoplasm. Bcl2 expression with 100% of the tumor cells positive was observed in 4 of 11 (36%) cases. Statistical analysis showed a statistical trend (P = 0.06) between loss and reduction of Fez1 and presence of lymph node metastases. CONCLUSIONS: These findings suggest that Fez1 may represent not only a molecular diagnostic marker but also a prognostic marker in CDC
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