515 research outputs found
Antimony germanium sulphide amorphous thin films fabricated by chemical vapour deposition
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
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
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
The - 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 ps.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
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
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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