516 research outputs found

    Antimony germanium sulphide amorphous thin films fabricated by chemical vapour deposition

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    Antimony germanium sulphide (Sb-Ge-S) amorphous thin films have been directly fabricated on both silica on silicon and commercial glass substrates by means of chemical vapour deposition. These Sb-Ge-S films have been characterized by micro-Raman, scanning electron microscopy and energy dispersive X-ray analysis techniques. The analysis results for these amorphous films indicate the composition of Sb-Ge-S can be varied by changing the deposition temperatures. The quality of these Sb-Ge-S amorphous thin films gives them high potential for the chalcogenide optical waveguide and device applications

    Search For Trapped Antihydrogen

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    We present the results of an experiment to search for trapped antihydrogen atoms with the ALPHA antihydrogen trap at the CERN Antiproton Decelerator. Sensitive diagnostics of the temperatures, sizes, and densities of the trapped antiproton and positron plasmas have been developed, which in turn permitted development of techniques to precisely and reproducibly control the initial experimental parameters. The use of a position-sensitive annihilation vertex detector, together with the capability of controllably quenching the superconducting magnetic minimum trap, enabled us to carry out a high-sensitivity and low-background search for trapped synthesised antihydrogen atoms. We aim to identify the annihilations of antihydrogen atoms held for at least 130 ms in the trap before being released over ~30 ms. After a three-week experimental run in 2009 involving mixing of 10^7 antiprotons with 1.3 10^9 positrons to produce 6 10^5 antihydrogen atoms, we have identified six antiproton annihilation events that are consistent with the release of trapped antihydrogen. The cosmic ray background, estimated to contribute 0.14 counts, is incompatible with this observation at a significance of 5.6 sigma. Extensive simulations predict that an alternative source of annihilations, the escape of mirror-trapped antiprotons, is highly unlikely, though this possibility has not yet been ruled out experimentally.Comment: 12 pages, 7 figure

    A weakly stable algorithm for general Toeplitz systems

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    We show that a fast algorithm for the QR factorization of a Toeplitz or Hankel matrix A is weakly stable in the sense that R^T.R is close to A^T.A. Thus, when the algorithm is used to solve the semi-normal equations R^T.Rx = A^Tb, we obtain a weakly stable method for the solution of a nonsingular Toeplitz or Hankel linear system Ax = b. The algorithm also applies to the solution of the full-rank Toeplitz or Hankel least squares problem.Comment: 17 pages. An old Technical Report with postscript added. For further details, see http://wwwmaths.anu.edu.au/~brent/pub/pub143.htm

    Measurement of the B0-anti-B0-Oscillation Frequency with Inclusive Dilepton Events

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    The B0B^0-Bˉ0\bar B^0 oscillation frequency has been measured with a sample of 23 million \B\bar B pairs collected with the BABAR detector at the PEP-II asymmetric B Factory at SLAC. In this sample, we select events in which both B mesons decay semileptonically and use the charge of the leptons to identify the flavor of each B meson. A simultaneous fit to the decay time difference distributions for opposite- and same-sign dilepton events gives Δmd=0.493±0.012(stat)±0.009(syst)\Delta m_d = 0.493 \pm 0.012{(stat)}\pm 0.009{(syst)} ps1^{-1}.Comment: 7 pages, 1 figure, submitted to Physical Review Letter

    A First Search for coincident Gravitational Waves and High Energy Neutrinos using LIGO, Virgo and ANTARES data from 2007

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    We present the results of the first search for gravitational wave bursts associated with high energy neutrinos. Together, these messengers could reveal new, hidden sources that are not observed by conventional photon astronomy, particularly at high energy. Our search uses neutrinos detected by the underwater neutrino telescope ANTARES in its 5 line configuration during the period January - September 2007, which coincided with the fifth and first science runs of LIGO and Virgo, respectively. The LIGO-Virgo data were analysed for candidate gravitational-wave signals coincident in time and direction with the neutrino events. No significant coincident events were observed. We place limits on the density of joint high energy neutrino - gravitational wave emission events in the local universe, and compare them with densities of merger and core-collapse events.Comment: 19 pages, 8 figures, science summary page at http://www.ligo.org/science/Publication-S5LV_ANTARES/index.php. Public access area to figures, tables at https://dcc.ligo.org/cgi-bin/DocDB/ShowDocument?docid=p120000

    Allogeneic hematopoietic stem cell transplant outcomes in adults with inherited myeloid malignancies

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    Final version published online 17 February 2023There is increasing recognition that pathogenic germline variants drive the development of hematopoietic cancers in many individuals. Currently, patients with hereditary hematologic malignancies (HHMs) receive similar standard therapies and hematopoietic stem cell transplant (HSCT) approaches as those with sporadic disease. We hypothesize that patients with myeloid malignancies and deleterious germline predisposition variants have different post-transplant outcomes compared to those without such alleles. We studied 472 patients with myeloid neoplasms, of whom 26% had deleterious germline variants (DGVs) and 34% underwent HSCT. DGVs in CHEK2 and DDX41 were most commonly seen in American and Australian cohorts, respectively. Patients with deleterious germline DDX41 variants had a higher incidence of severe (stage 3-4) acute graft versus host disease (GVHD) (38%) compared to recipients with deleterious CHEK2 variants (0%), other HHM variants (12%), or patients without such germline variants (9%) (p= 0.002). Importantly, the use of post-transplant cyclophosphamide reduced the risk of severe acute GVHD in patients receiving HSCT for deleterious germline DDX41-associated myeloid neoplasms (0% vs 53%, p=0.03). Based on these results, we advocate the use of post-transplant cyclophosphamide when individuals with deleterious germline DDX41 variants undergo allogeneic HSCT for myeloid malignancies, even when transplantation has been performed using wild-type donors.Caner Saygin, Gregory Roloff, Christopher N. Hahn, Rakchha Chhetri, Saar Gill, Hany Elmariah, Chetasi Talati, Emma Nunley, Guimin Gao, Aelin Kim, Michael Bishop, Satyajit Kosuri, Soma Das, Deepak Singhal, Parvathy Venugopal, Claire C. Homan, Anna Brown, Hamish S. Scott, Devendra Hiwase, and Lucy A. Godle
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