554 research outputs found
HI 21 cm Emission Line Study of Southern Galactic Supernova Remnants
We have searched for HI 21 cm line emission from shocked atomic gas
associated with southern supernova remnants (SNRs) using data from the Southern
Galactic Plane Survey. Among the 97 sources studied, we have detected 10 SNRs
with high-velocity HI emission confined to the SNR. The large velocity and the
spatial confinement suggest that the emission is likely from the gas
accelerated by the SN blast wave. We also detected 22 SNRs which show HI
emission significantly brighter than the surrounding regions over a wide
(\kms) velocity interval. The association with these SNRs is less certain.
We present the parameters and maps of the excess emission in these SNRs. We
discuss in some detail the ten individual SNRs with associated high-velocity HI
emission.Comment: 17 pages, 8 figures, accepted for publication in JKAS (Journal of the
Korean Astronomical Society
Faint HI 21-cm Emission Line Wings at Forbidden-Velocities
We present the results of a search for faint HI 21-cm emission line wings at
velocities forbidden by Galactic rotation in the Galactic plane using the
Leiden/Dwingeloo HI Survey data and the HI Southern Galactic Plane Survey data.
These ``forbidden-velocity wings (FVWs)'' appear as protruding excessive
emission in comparison with their surroundings in limited (< 2 deg) spatial
regions over velocity extent more than ~20 km/s in large-scale (l-v) diagrams.
Their high-velocities imply that there should be some dynamical phenomena
associated. We have identified 87 FVWs. We present their catalog, and discuss
their distribution and statistical properties. We found that 85% of FVWs are
not coincident with known supernova remnants (SNRs), galaxies, or high-velocity
clouds. Their natures are currently unknown. We suspect that many of them are
fast-moving HI shells and filaments associated with the oldest SNRs that are
essentially invisible except via their HI line emission. We discuss other
possible origins.Comment: 41 pages, 14 figures, to be published in apj
Visibility of Old Supernova Remnants in HI 21-cm Emission Line
We estimate the number of old, radiative supernova remnants (SNRs) detectable
in HI 21-cm emission line in the Galaxy. According to our result, the
contamination due to the Galactic background HI emission limits the number of
visible SNRs to 270, or 9% of the total HI SNRs. The telescope sensitivity
further limits the number. We compare the result with observations to find that
the observed number (< 25) of HI SNRs is much less than the expected. A
plausible explanation is that previous observational studies, which were made
toward the SNRs identified mostly in radio continuum, missed most of the HI
SNRs because they are too faint to be visible in radio continuum. We propose
that the faint, extended HI 21-cm emission line wings protruding from the
Galactic background HI emission in large-scale (l, v) diagrams could be
possible candidates for HI SNRs, although our preliminary result shows that
their number is considerably less than the expected in the inner Galaxy. We
conclude that a possible explanation for the small number of \schi SNRs in the
inner Galaxy is that the interstellar space there is largely filled with a very
tenuous gas as in the three-phase ISM model.Comment: 10 pages, 9 figures, accepted for publication in MNRA
Recessive C10orf2 mutations in a family with infantile-onset spinocerebellar ataxia, sensorimotor polyneuropathy, and myopathy
Recessive mutations in chromosome 10 open reading frame 2 (C10orf2) are relevant in infantile-onset spinocerebellar ataxia (IOSCA). In this study, we investigated the causative mutation in a Korean family with combined phenotypes of IOSCA, sensorimotor polyneuropathy, and myopathy. We investigated recessive mutations in a Korean family with two individuals affected by IOSCA. Causative mutations were investigated using whole exome sequencing. Electrophysiological analyses and muscle and nerve biopsies were performed, along with magnetic resonance imaging (MRI) of the brain and lower extremities. Compound heterozygous mutations c.1460C>T and c.1485-1G>A in C10orf2 were identified as causative of IOSCA. Skeletal muscle showed mitochondrial DNA (mtDNA) deletions. Both patients showed a period of normal development until 12–15 months, followed by ataxia, athetosis, hearing loss, and intellectual disability. Electrophysiological findings indicated motor and sensory polyneuropathies. Muscle biopsy revealed variations in the size and shape of myofibers with scattered, small, and angulated degenerating myofibers containing abnormal mitochondria; these observations are consistent with myopathy and may be the result of mtDNA deletions. Sural nerve biopsy revealed an axonal neuropathy. High-signal-intensity lesions in the middle cerebellar peduncles were correlated with clinical severity, and MRI of the lower legs was compatible with the hypothesis of length-dependent axonal degeneration. We identified novel compound heterozygous mutations of the C10orf2 gene as the cause of IOSCA with sensorimotor polyneuropathy and myopathy. Signs of motor neuropathy and myopathy were discovered for the first time in IOSCA patients with C10orf2 mutations. These results suggest that the clinical spectrum of IOSCA caused by C10orf2 mutations may be more variable than previously reported. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1007/s10048-014-0405-1) contains supplementary material, which is available to authorized users
A "Missing" Supernova Remnant revealed by the 21-cm Line of Atomic Hydrogen
Although some 20--30,000 supernova remnants (SNRs) are expected to exist in
the Milky Way, only about 230 are presently known. This implies that most SNRs
are ``missing''. Recently, we proposed that small (\simlt 1^\circ), faint,
high-velocity features seen in large-scale 21-cm line surveys of atomic
hydrogen ({\sc Hi}) in the Galactic plane could be examples of such {\it
missing} old SNRs. Here we report on high-resolution \schi observations of one
such candidate, FVW 190.2+1.1, which is revealed to be a rapidly expanding
( \kms) shell. The parameters of this shell seem only consistent with
FVW 190.2+1.1 being the remnant of a SN explosion that occurred in the
outermost fringes of the Galaxy some yr ago. This shell is
not seen in any other wave band suggesting that it represents the oldest type
of SNR, that which is essentially invisible except via its \schi line emission.
FVW 190.2+1.1 is one of a hundred "forbidden-velocity wings" (FVWs) recently
identified in the Galactic plane, and our discovery suggests that many of these
are likely to be among the oldest SNRs. We discuss the possible link between
FVWs and fast-moving atomic clouds in the Galaxy.Comment: 12 pages, 3 figures, To appear in The Astrophysical Journal Letter
A fatal case of acute pulmonary embolism caused by right ventricular masses of acute lymphoblastic lymphoma-leukemia in a 13 year old girl
We report a case of a 13-year-old girl with acute lymphoblastic lymphoma-leukemia, who presented with a cardiac metastasis in the right ventricle, resulting in a pulmonary embolism. At the time of her leukemia diagnosis, a cardiac mass was incidentally found. The differential diagnosis for this unusual cardiac mass included cardiac tumor, metastasis, vegetation, and thrombus. Empirical treatment was initiated, including anticoagulation and antibiotics. She underwent plasmapheresis and was administered oral prednisolone for her leukemia. Five days later, she experienced sudden hemodynamic collapse and required extracorporeal membrane oxygenation insertion and emergency surgery. These interventions proved futile, and the patient died. Pathology revealed that the cardiac mass comprised an aggregation of small, round, necrotic cells consistent with leukemia. This is the first known case of acute lymphoblastic leukemia presenting as a right ventricular mass, with consequent fatal acute pulmonary embolism. A cardiac mass in a child with acute leukemia merits investigation to rule out every possible etiology, including vegetation, thrombus, and even a mass of leukemic cells, which could result in the fatal complication of pulmonary embolism
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