49 research outputs found
VLA Observations of J1228+441, a Luminous Supernova Remnant in NGC 4449
The luminous, oxygen-rich supernova remnant, J1228+441, is located in the
irregular galaxy NGC 4449 and has been observed at radio wavelengths for thirty
years. An analysis of recent VLA observations of NGC 4449, combined with VLA
archive data and previously published VLA and WSRT observations, yields light
curves at 6 and 20 cm from 1972 to 2002. The light curves at all radio
frequencies exhibit a marked decline in radio emission, confirming past
findings. This paper presents and discusses the radio light curves and spectral
index, alpha, variations from 1972 to 2002 where nu propto nu^(-alpha) and
compares J1228+441 with other radio supernovae. The spectral index of J1228+441
appears to have steepened in the last five years at higher frequencies from
alpha=0.64 +- 0.02 in 1996 to alpha=1.01 +- 0.02 in 2001-2002.Comment: aastex, 19 pages, 6 figures, to be published in A
The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76
The {\sc Majorana} collaboration is searching for neutrinoless double beta
decay using Ge, which has been shown to have a number of advantages in
terms of sensitivities and backgrounds. The observation of neutrinoless
double-beta decay would show that lepton number is violated and that neutrinos
are Majorana particles and would simultaneously provide information on neutrino
mass. Attaining sensitivities for neutrino masses in the inverted hierarchy
region, meV, will require large, tonne-scale detectors with extremely
low backgrounds, at the level of 1 count/t-y or lower in the region of
the signal. The {\sc Majorana} collaboration, with funding support from DOE
Office of Nuclear Physics and NSF Particle Astrophysics, is constructing the
{\sc Demonstrator}, an array consisting of 40 kg of p-type point-contact
high-purity germanium (HPGe) detectors, of which 30 kg will be enriched
to 87% in Ge. The {\sc Demonstrator} is being constructed in a clean
room laboratory facility at the 4850' level (4300 m.w.e.) of the Sanford
Underground Research Facility (SURF) in Lead, SD. It utilizes a compact graded
shield approach with the inner portion consisting of ultra-clean Cu that is
being electroformed and machined underground. The primary aim of the {\sc
Demonstrator} is to show the feasibility of a future tonne-scale measurement in
terms of backgrounds and scalability.Comment: Proceedings for the MEDEX 2013 Conferenc
Acute myocardial infarction in a patient with hypofibrinogenemia: a case report
<p>Abstract</p> <p>Introduction</p> <p>Congenital fibrinogen deficiency is a rare coagulation disorder usually responsible for hemorrhagic diathesis. However, it can be associated with thrombosis and there have been limited reports of arterial thrombotic complications in these patients.</p> <p>Case presentation</p> <p>A 42-year-old Tunisian man with congenital hypofibrinogenemia and no cardiovascular risk factors presented with new onset prolonged angina pectoris. An electrocardiogram showed features of inferior acute myocardial infarction. His troponin levels had reached 17 ng/L. Laboratory findings confirmed hypofibrinogenemia and ruled out thrombophilia. Echocardiography was not useful in providing diagnostic elements but did show preserved left ventricular function. Coronary angiography was not performed and our patient did not receive any anticoagulant treatment due to the major risk of bleeding. Magnetic resonance imaging confirmed myocardial necrosis. Our patient was managed with aspirin, a beta-blocker, an angiotensin-converting enzyme inhibitor and statin medication. The treatment was well tolerated and no ischemic recurrence was detected.</p> <p>Conclusion</p> <p>Although coronary thrombosis is a rare event in patients with fibrinogen deficiency, this condition is of major interest in view of the difficulties observed in managing these patients.</p
Status of the MAJORANA DEMONSTRATOR experiment
The MAJORANA DEMONSTRATOR neutrinoless double beta-decay experiment is
currently under construction at the Sanford Underground Research Facility in
South Dakota, USA. An overview and status of the experiment are given.Comment: 8 pages, proceeding from VII International Conference on
Interconnections between Particle Physics and Cosmology (PPC 2013), submitted
to AIP proceeding
The Majorana experiment: an ultra-low background search for neutrinoless double-beta decay
The observation of neutrinoless double-beta decay would resolve the Majorana
nature of the neutrino and could provide information on the absolute scale of
the neutrino mass. The initial phase of the Majorana experiment, known as the
Demonstrator, will house 40 kg of Ge in an ultra-low background shielded
environment at the 4850' level of the Sanford Underground Laboratory in Lead,
SD. The objective of the Demonstrator is to determine whether a future 1-tonne
experiment can achieve a background goal of one count per tonne-year in a
narrow region of interest around the 76Ge neutrinoless double-beta decay peak.Comment: Presentation for the Rutherford Centennial Conference on Nuclear
Physic
The MAJORANA DEMONSTRATOR: A Search for Neutrinoless Double-beta Decay of Germanium-76
The observation of neutrinoless double-beta decay would determine whether the
neutrino is a Majorana particle and provide information on the absolute scale
of neutrino mass. The MAJORANA Collaboration is constructing the DEMONSTRATOR,
an array of germanium detectors, to search for neutrinoless double-beta decay
of 76-Ge. The DEMONSTRATOR will contain 40 kg of germanium; up to 30 kg will be
enriched to 86% in 76-Ge. The DEMONSTRATOR will be deployed deep underground in
an ultra-low-background shielded environment. Operation of the DEMONSTRATOR
aims to determine whether a future tonne-scale germanium experiment can achieve
a background goal of one count per tonne-year in a 4-keV region of interest
around the 76-Ge neutrinoless double-beta decay Q-value of 2039 keV.Comment: Submitted to AIP Conference Proceedings, 19th Particles & Nuclei
International Conference (PANIC 2011), Massachusetts Institute of Technology,
Cambridge, MA, USA, July 24-29, 2011; 3 pages, 1 figur