1,793 research outputs found
Fornax compact object survey FCOS: On the nature of Ultra Compact Dwarf galaxies
The results of the Fornax Compact Object Survey (FCOS) are presented. The
FCOS aims at investigating the nature of the Ultra Compact Dwarf galaxies
(UCDs) recently discovered in the center of the Fornax cluster (Drinkwater et
al. 2000). 280 unresolved objects in the magnitude space covering UCDs and
bright globular clusters (18<V<21 mag) were observed spectroscopically. 54 new
Fornax members were discovered, plus five of the seven already known UCDs.
Their distribution in radial velocity, colour, magnitude and space was
investigated. It is found that bright compact objects (V<20 or M_V<-11.4 mag),
including the UCDs, have a higher mean velocity than faint compact objects
(V>20 mag) at 96% confidence. The mean velocity of the bright compact objects
is consistent with that of the dwarf galaxy population in Fornax, but
inconsistent with that of NGC 1399's globular cluster system at 93.5%
confidence. The compact objects follow a colour magnitude relation with a slope
very similar to that of normal dEs, but shifted about 0.2 mag redwards. The
magnitude distribution of compact objects shows a fluent transition between
UCDs and GCs with an overpopulation of 8 +/- 4 objects for V<20 mag with
respect to the extrapolation of NGC 1399's GC luminosity function. The spatial
distribution of bright compact objects is in comparison to the faint ones more
extended at 88% confidence. All our findings are consistent with the threshing
scenario (Bekki et al. 2003), suggesting that a substantial fraction of compact
Fornax members brighter than V~20 mag could be created by threshing dE,Ns.
Fainter than V~20 mag, the majority of the objects seem to be genuine GCs. Our
results are also consistent with merged stellar super-clusters (Fellhauer &
Kroupa 2002) as an alternative explanation for the bright compact objects.Comment: 15 pages, 11 figures, accepted for publication in A&
Older Citizens' Opinions on Long-Term Care Options: A Vignette Survey.
Older citizens are directly concerned, as potential beneficiaries and informal caregivers, by access to long-term care (LTC) services matching their expectations. The aim of this research was to collect their opinions regarding LTC arrangements for a diversity of disability profiles.
Mailed vignette survey in a representative population-based sample of 3133 community-dwelling persons 68 years or older residing in a Swiss region.
All persons received a set of 10 vignettes. For each vignette, they considered 2 social situations successively: a person (1) living with an able-bodied spouse, and (2) living alone or with a spouse unable to help (resulting in 20 vignettes). Subjects selected a care setting (home, sheltered housing, or nursing home) and specified the preferred type of caregivers (spouse, professionals, or both) after community-based care options. Population estimates were based on weighted data accounting for the stratification of the survey sample.
A total of 2985 participants (95.3%) expressed opinions on 55,178 vignettes (mean 18.5 vignettes, SD 4.1) Institutionalization was selected by 0.8% (95% confidence interval 0.3-1.4) of the population for the vignette of lowest disability with able-bodied spouse and 78.8% (76.1-81.6) for the vignette of highest disability and no possible help from a spouse. Continence, cognitive, and behavioral difficulties further influenced the preferences expressed for LTC options. Community-based LTC choices involved professionals mostly as a complement to informal help by the spouse, except for vignettes describing isolated moderate cognitive impairment or difficulties in instrumental activities of daily living. In these cases, most favored help provided by spouses only.
This survey had high acceptance. Responses to variations in the disability and social profile displayed in the vignettes suggested the validity of measurements
On-axis spectroscopy of the host galaxies of 20 optically luminous quasars at z~0.3
We present the analysis of a sample of 20 bright low-redshift quasars
(M_B<-23 and z < 0.35) observed spectroscopically with the VLT. The FORS1
spectra, obtained in Multi Object Spectroscopy (MOS) mode, allow to observe
simultaneously the quasars and several reference stars used to spatially
deconvolve the data. Applying the MCS deconvolution method, we are able to
separate the individual spectra of the quasar and of the underlying host
galaxy. Contrary to some previous claims, we find that luminous quasars are not
exclusively hosted by massive ellipticals. Most quasar host galaxies harbour
large amounts of gas, irrespective of their morphological type. Moreover, the
stellar content of half of the hosts is a young Sc-like population, associated
with a rather low metallicity interstellar medium. A significant fraction of
the galaxies contain gas ionized at large distances by the quasar radiation.
This large distance ionization is always associated with signs of gravitational
interactions (as detected from images or disturbed rotation curves). The
spectra of the quasars themselves provide evidence that gravitational
interactions bring dust and gas in the immediate surrounding of the super
massive black hole, allowing to feed it. The quasar activity might thus be
triggered (1) in young gas-rich spiral galaxies by local events and (2) in more
evolved galaxies by gravitational interactions or collisions. The latter
mechanism gives rises to the most powerful quasars. Finally, we derive mass
models for the isolated spiral host galaxies and we show that the most reliable
estimators of the systemic redshift in the quasar spectrum are the tips of the
Ha and Hb lines.Comment: 30 pages, 19 figures, 9 tables, accepted for publication in MNRAS,
major revisio
The Mass Function of Main Sequence Stars in NGC6397 from Near IR and Optical High Resolution HST Observations
We have investigated the properties of the stellar mass function in the
globular cluster NGC6397 using a large set of HST observations that include
WFPC2 images in V and I, obtained at ~4' and 10' radial distances, and a series
of deep images in the J and H bands obtained with the NIC2 and NIC3 cameras of
NICMOS pointed to regions located ~4.5' and ~3.2' from the center. These
observations span the region from ~1 to ~3 times the cluster's half-light
radius. All luminosity functions, derived from color magniutde diagrams,
increase with decreasing luminosity up to a peak at M_I~8.5 or M_H~7 and then
precipitously drop well before photometric incompleteness becomes significant.
Within the observational uncertainties, at M_I~12 or M_H~10.5 (~0.09 Msun) the
luminosity functions are compatible with zero. By applying the best available
mass- luminosity relation appropriate to the metallicity of NGC6397 to both the
optical and IR data, we obtain a mass function that shows a break in slope at
\~0.3 Msun. No single exponent power-law distribution is compatible with these
data, regardless of the value of the exponent. We find that a dynamical model
of the cluster can simultaneously reproduce all the luminosity functions
observed throughout the cluster only if the IMF rises as m**-1.6 in the range
0.8-0.3 Msun and then drops as m**0.2 below ~0.3 Msun. Adopting a more physical
log-normal distribution for the IMF, all these data taken together imply a best
fit distribution with characteristic mass m_c~0.3 and sigma~1.8.Comment: 18 pages, 6 figures (ps). Accepted for publication in Ap
Intervals between response choices on a single-item measure of quality of life.
BACKGROUND: A single overall rating of quality of life (QoL) is a sensitive method that is often used in population surveys. However, the exact meaning of response choices is unclear. In particular, uneven spacing may affect the way QoL ratings should be analyzed and interpreted. This study aimed to determine the intervals between response choices to a single-item QoL assessment.
METHODS: A secondary analysis was conducted on data from the Lc65+ cohort study and two additional, population-based, stratified random samples of older people (N = 5,300). Overall QoL was rated as excellent, very good, good, fair or poor. A QoL score (range 0-100) was derived from participants' answers to a 28-item QoL assessment tool. A transformed QoL score ranging from 1 (poor) to 5 (excellent) was calculated. The same procedure was repeated to compute seven domain-specific QoL subscores (Feeling of safety; Health and mobility; Autonomy; Close entourage; Material resources; Esteem and recognition; Social and cultural life).
RESULTS: Mean (95 % confidence intervals) QoL scores were 96.23 (95.81-96.65) for excellent, 93.09 (92.74-93.45) for very good, 81.45 (80.63-82.27) for good, 65.44 (62.67-68.20) for fair and 54.52 (45.31-63.73) for poor overall QoL, corresponding to transformed QoL scores of respectively 5.00, 4.70, 3.58, 2.05, and 1.00. Ordinality of the categories excellent to poor was preserved in all seven QoL subscores.
CONCLUSIONS: The excellent-to-poor rating scale provides an ordinal measure of overall QoL. The intervals between response choices are unequal, but an interval scale can be obtained after adequate recoding of excellent, very good, good, fair and poor
Globular clusters and dwarf galaxies in Fornax - I. Kinematics in the cluster core from multi-object spectroscopy
We acquired radial velocities of a significant number of globular clusters
(GCs) on wide fields between galaxies in the nearby Fornax cluster of galaxies,
in order to derive their velocity dispersion radial profile and to probe the
dynamics of the cluster. We used FLAMES on the VLT to obtain accurate
velocities for 149 GCs, within a ~500x150 kpc strip centered on NGC 1399, the
Fornax central galaxy. These objects are at the very bright tail (M_V < -9.5)
of the GC luminosity function, overlapping the so-called ``ultra-compact
dwarfs'' magnitude range. Eight of the brightest FLAMES-confirmed members
indeed show hints of resolution in the subarcsecond pre-imaging data we used
for selecting the ~500 targets for FLAMES spectroscopy. Ignoring the GCs around
galaxies by applying 3d_25 diameter masks, we find 61 GCs of 20.0 < V < 22.2
lying in the intra-cluster (IC) medium. The velocity dispersion of the
population of ICGCs is 200 km/s at ~150 kpc from the central NGC 1399 and rises
to nearly 400 km/s at 200 kpc, a value which compares with the velocity
dispersion of the population of dwarf galaxies, thought to be infalling from
the surroundings of the cluster.Comment: To be published in A&A Letters. 4 pages, 3 figures, 3 table
GAMBARAN KELUHAN PENYAKIT DEKOMPRESI PADA PENYELAM TRADISIONAL DI KAMPUNG SIMUENG KABUPATEN KEPULAUAN SANGIHE TAHUN 2017
Pada dasarnya nelayan penyelam tradisional yang sering disebut dengan nelayan kompresor yaitu penyelam yang menggunakan peralatan sangat terbatas. Potensi bahaya dapat dilihat juga dari perilaku nelayan yang bekerja tanpa memperhatikan aspek keselamatan (safety diving), keluhan yang sering terjadi antara lain rasa kesemutan pada daerah persendihan, gatal, keluar darah dari hidung bahkan dapat terjadi kelumpuhan (Navisah,2016). Metode yang digunakan dalam Penelitian ini ialah deskriptif dengan pendekatan survey pada 40 orang penyelam tradisional yang juga berprofesi sebagai nelayan di Kampung Simueng, Kabupaten Kepulauan Sangihe yang dilaksanakan selang bulan Mei 2017. Hasil penelitian menunjukan bahwa gejala ringan 35 % dan berat 27 % . Gejala ringan dialami berupa nyeri sendi, gatal– gatal, timbul bercak darah pada kulit dan kesemutan, adapun selain itu gejala berat yang dialami responden berupah pecah pembuluh darah, lumpuh, dan tuli. Kesimpulan dalam penelitian yakni sebagian responden mengalami gangguan akibat penyelaman, hal tersebut diakibatkan karena penyelam tidak mengikuti aturan serta standar penyelaman yang baik dan menurut para nelayan mereka belum pernah mendapatkan materi/penyuluhan tentang standar penyelaman oleh karena itu pelulis menyarankan kepada Pemerintah Daerah untuk menyelenggarakan pelatihan standar penyelaman kepada para Nelayan tersebut
Young and intermediate-age massive star clusters
An overview of our current understanding of the formation and evolution of
star clusters is given, with main emphasis on high-mass clusters. Clusters form
deeply embedded within dense clouds of molecular gas. Left-over gas is cleared
within a few million years and, depending on the efficiency of star formation,
the clusters may disperse almost immediately or remain gravitationally bound.
Current evidence suggests that a few percent of star formation occurs in
clusters that remain bound, although it is not yet clear if this fraction is
truly universal. Internal two-body relaxation and external shocks will lead to
further, gradual dissolution on timescales of up to a few hundred million years
for low-mass open clusters in the Milky Way, while the most massive clusters (>
10^5 Msun) have lifetimes comparable to or exceeding the age of the Universe.
The low-mass end of the initial cluster mass function is well approximated by a
power-law distribution, dN/dM ~ M^{-2}, but there is mounting evidence that
quiescent spiral discs form relatively few clusters with masses M > 2 x 10^5
Msun. In starburst galaxies and old globular cluster systems, this limit
appears to be higher, at least several x 10^6 Msun. The difference is likely
related to the higher gas densities and pressures in starburst galaxies, which
allow denser, more massive giant molecular clouds to form. Low-mass clusters
may thus trace star formation quite universally, while the more long-lived,
massive clusters appear to form preferentially in the context of violent star
formation.Comment: 21 pages, 3 figures. To appear as invited review article in a special
issue of the Phil. Trans. Royal Soc. A: Ch. 9 "Star clusters as tracers of
galactic star-formation histories" (ed. R. de Grijs). Fully peer reviewed.
PDFLaTeX, requires rspublic.cls style fil
Logarithmic mathematical morphology: a new framework adaptive to illumination changes
A new set of mathematical morphology (MM) operators adaptive to illumination
changes caused by variation of exposure time or light intensity is defined
thanks to the Logarithmic Image Processing (LIP) model. This model based on the
physics of acquisition is consistent with human vision. The fundamental
operators, the logarithmic-dilation and the logarithmic-erosion, are defined
with the LIP-addition of a structuring function. The combination of these two
adjunct operators gives morphological filters, namely the logarithmic-opening
and closing, useful for pattern recognition. The mathematical relation existing
between ``classical'' dilation and erosion and their logarithmic-versions is
established facilitating their implementation. Results on simulated and real
images show that logarithmic-MM is more efficient on low-contrasted information
than ``classical'' MM
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