2,168 research outputs found
Direct UV observations of the circumstellar envelope of alpha Orionis
Observations were made in the IUE LWP camera, low dispersion mode, with alpha Ori being offset various distances from the center of the Long Wavelength Large Aperture along its major axis. Signal was acquired at all offset positions and is comprised of unequal components of background/dark counts, telescope-scattered light, and scattered light emanating from the extended circumstellar shell. The star is known from optical and infrared observations to possess an extended, arc-minute sized, shell of cool material. Attempts to observe this shell with the IUE are described, although the deconvolution of the stellar signal from the telescope scattered light requires further calibration effort
Merging of globular clusters within inner galactic regions. II. The Nuclear Star Cluster formation
In this paper we present the results of two detailed N-body simulations of
the interaction of a sample of four massive globular clusters in the inner
region of a triaxial galaxy. A full merging of the clusters takes place,
leading to a slowly evolving cluster which is quite similar to observed Nuclear
Clusters. Actually, both the density and the velocity dispersion profiles match
qualitatively, and quantitatively after scaling, with observed features of many
nucleated galaxies. In the case of dense initial clusters, the merger remnant
shows a density profile more concentrated than that of the progenitors, with a
central density higher than the sum of the central progenitors central
densities. These findings support the idea that a massive Nuclear Cluster may
have formed in early phases of the mother galaxy evolution and lead to the
formation of a nucleus, which, in many galaxies, has indeed a luminosity
profile similar to that of an extended King model. A correlation with galactic
nuclear activity is suggested.Comment: 18 pages, 10 figures, 3 tables. Submitted to ApJ, main journa
Formation and evolution of clumpy tidal tails around globular clusters
We present some results of numerical simulations of a globular cluster
orbiting in the central region of a triaxial galaxy on a set of 'loop' orbits.
Tails start forming after about a quarter of the globular cluster orbital
period and develop, in most cases, along the cluster orbit, showing clumpy
substructures as observed, for example, in Palomar 5. If completely detectable,
clumps can contain about 7,000 solar masses each, i.e. about 10% of the cluster
mass at that epoch. The morphology of tails and clumps and the kinematical
properties of stars in the tails are studied and compared with available
observational data. Our finding is that the stellar velocity dispersion tends
to level off at large radii, in agreement to that found for M15 and Omega
Centauri.Comment: LaTeX 2e, uses AASTeX v5.x, 40 pages with 18 figures. Submitted to
The Astronomical Journa
ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)
We present ASCA observations of the radio-selected BL Lacertae objects
1749+096 (z=0.32) and 2200+420 (BL Lac, z=0.069) performed in 1995 Sept and
Nov, respectively. The ASCA spectra of both sources can be described as a first
approximation by a power law with photon index Gamma ~ 2. This is flatter than
for most X-ray-selected BL Lacs observed with ASCA, in agreement with the
predictions of current blazar unification models. While 1749+096 exhibits
tentative evidence for spectral flattening at low energies, a concave continuum
is detected for 2200+420: the steep low-energy component is consistent the
high-energy tail of the synchrotron emission responsible for the longer
wavelengths, while the harder tail at higher energies is the onset of the
Compton component. The spectral energy distributions from radio to gamma-rays
are consistent with synchrotron-self Compton emission from a single homogeneous
region shortward of the IR/optical wavelengths, with a second component in the
radio domain related to a more extended emission region. For 2200+420,
comparing the 1995 Nov state with the optical/GeV flare of 1997 July, we find
that models requiring inverse Compton scattering of external photons provide a
viable mechanism for the production of the highest (GeV) energies during the
flare. An increase of the external radiation density and of the power injected
in the jet can reproduce the flat gamma-ray continuum observed in 1997 July. A
directly testable prediction of this model is that the line luminosity in
2200+420 should vary shortly after (~1 month) a non-thermal synchrotron flare.Comment: 28 pages,6 figures, 5 tables; LaTeX document. accepted for
publication in the Astrophysical Journa
The beneficial effect of physiotherapy on the cervical spine mobility of ACDF patients and healthy individuals: An original observational cohort comparison research protocol
Purpose: Population aging and certain behaviors associated with modern life are contributing factors for the increasing incidence of degenerative cervical spine conditions (DCSC), and the number of cervical spine surgeries every year is. Our aim was to determine, with an original research protocol, the impact of ACDF and physiotherapy on the range of motion and EMG parameters of patients suffering from DCSC. Patients and Methods: Two comparable subgroups of 29 patients each were recruited for the present investigation. The first cohort was composed of ACDF patients, whereas the second cohort was composed by healthy subjects. Inclinometry/Range of Motion (RoM) analyses of the neck, and cervical muscles electromyography (EMG) were used to evaluate the neck mobility. We investigated the effects of physiotherapy on ROM and EMG results in order to identify possible significant differences between healthy subjects and ACDF patients. Results: A total of 58 patients were included in the final cohort. Extensive statistical analysis disclosed that higher NDI values were associated with a reduction of the Extension and Rotation movements, NDI scores, were found to be negatively associated to EMG voltages for Rotation, independently of the physiotherapy performed either. Extension, Lateral Bending, and Rotation showed significant improvement after just one session of physiotherapy, whereas Flexion and Extension proved to be those that contributed most to the overall neck mobility. Conclusion: The cervical spine fusion contributes to an overall reduction of cervical mobility. This data is confirmed by inclinometer and EMG parameters. Physiotherapy increases neck mobility thus possibly improving the clinical status of patients
ACHALASIA TREATMENT IMPROVES SPECIFIC SYMPTOMS AND QUALITY OF LIFE: VALIDATION OF AN ACHALASIA SPECIFIC QUALITY OF LIFE QUESTIONNAIRE
Background and aim:
Therapies for achalasia aim to patientsâ symptom
relief, but they affect patientâs quality of life (QoL), too. An ad hoc question-
naire evaluating both achalasia-related symptoms and disease related QoL is
lacking.
Aim: To validate a disease specific QoL questionnaire in perspectively
evaluated Italian achalasia patients.
Material and methods:
22 consecutive achalasia patients (4 men, age range
19â86 years) were included in the study. At baseline a structured question-
naire was used to evaluate both esophageal symptoms and disease specific
QoL. Questionnaire graded achalasia-related symptoms severity (dysphagia for solids and liquids, food regurgitation, chest pain, nocturnal cough) from 0
to 3, based on their impact on daily activities. Also a disease specific QoL was
evaluated by a self administred questionnaire, the AE-18, that investigated
four domains (physical, psychological and social functioning, and sleep dis-
turbance). Scores for each item range from 1
(âalwaysâ) to 5 (âneverâ); higher
scores corresponding to better quality of life. All patients were questioned
before, 1 and 6 months after a specific t
reatment regimen, that according
to patients clinical status consisted in pneumatic dilation, botulinum toxin
injection or surgical myotomy.
Results:
Patients within each specific treatment groups were the following
(3/22 surgical myotomy, 14/22 pneumatic dilation and 5/22 Botox injections,
respectively. In the table are reported the baseline demographics and achalasia-
related symptomsâ severity and QoL (data are expressed as mean
±
SD) within
each treatments group.
Table 1
Surgery group Dilation group Botox group p
Age at diagnosis
42.3
±
6.5 42.3
±
13 81.8
±
4.8
<
0.001
Age at onset of symptoms
39.3
±
7.5 40.3
±
12.4 80.8
±
5.6
<
0.001
Dysphagia for solids
2.7
±
0.6 2.2
±
0.7 2.2
±
0.5 0.5
Dysphagia for liquids
2.0
±
1.0 2.1
±
0.7 2.2
±
0.5 0.9
Regurgitation of undigested food 1.0
±
1.7 0.7
±
0.8 0.6
±
1.3 0.8
Chest pain
0.7
±
1.1 1.1
±
1.1 1.0
±
1.4 0.8
Nocturnal cough
1.3
±
1.5 1.3
±
1.2 1.0
±
1.4 0.9
AE-18 total score
54
±
14 53
±
12 53
±
11 0.9
At both 1 and 6 months of the follow-up, the severity mean scores of dysphagia
achalasia-related symptoms severity were significantly reduced compared to
baseline (p
<
0.05). Similarly, the AE-18 total score was significantly improved
(p
<
0.001).
Conclusions:
We showed that therapy-induced improvement of achalasia-
related symptoms correlate with a significant improvement of patients quality
of life as assessed by a specific questionnaire
Dynamics of the Globular Cluster System Associated with M87 (NGC 4486). II. Analysis
We present a dynamical analysis of the globular cluster system associated
with M87 (= NGC 4486), the cD galaxy near the dynamical center of the Virgo
cluster. The analysis utilizes a new spectroscopic and photometric database
which is described in a companion paper (Hanes et al. 2001). Using a sample of
278 globular clusters with measured radial velocities and metallicities, and
new surface density profiles based on wide-field Washington photometry, we
study the dynamics of the M87 globular cluster system both globally --- for the
entire cluster sample --- and separately --- for the metal-rich and metal-poor
globular cluster samples. This constitutes the largest sample of radial
velocities for pure Population II tracers yet assembled for any galaxy. We
discuss the implications of our findings for models for the formation of giant
elliptical galaxies, globular cluster systems, and the Virgo cluster.
(ABRIDGED)Comment: 28 pages, 19 postscript figures, 1 jpeg image. See
http://www.physics.rutgers.edu/ast/ast-rap.html to download the manuscript
with higher quality figures. Accepted for publication in the Astrophysical
Journa
A Deep Chandra Observation of the Distant Galaxy Cluster MS1137.5+6625
We present results from a deep Chandra observation of MS1137.5+66, a distant
(z=0.783) and massive cluster of galaxies. Only a few similarly massive
clusters are currently known at such high redshifts; accordingly, this
observation provides much-needed information on the dynamical state of these
rare systems. The cluster appears both regular and symmetric in the X-ray
image. However, our analysis of the spectral and spatial X-ray data in
conjunction with interferometric Sunyaev-Zel'dovich effect data and published
deep optical imaging suggests the cluster has a fairly complex structure. The
angular diameter distance we calculate from the Chandra and Sunyaev-Zel'dovich
effect data assuming an isothermal, spherically symmetric cluster implies a low
value for the Hubble constant for which we explore possible explanations.Comment: 16 pages, 6 figures, submitted to Ap
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