789 research outputs found
Near Infrared properties of 12 Globular Clusters toward the inner Bulge of the Galaxy
We present near-IR Colour-Magnitude diagrams and physical parameters for a
sample of 12 galactic globular clusters located toward the inner Bulge region.
For each cluster we provide measurements of the reddening, distance,
photometric metallicity, luminosity of the horizontal branch red clump, and of
the red giant branch bump and tip. The sample discussed here together with that
presented in Valenti, Ferraro & Origlia (2007) represent the largest
homogeneous catalog of Bulge globular clusters (comprising ~ 80% of the entire
Bulge cluster population) ever studied. The compilation is available in
electronic form on the World Wide Web (http://www.bo.astro.it/~GC/ir_archive)Comment: 2 pages, 13 figures, 4 tables, accepted for publication in MNRA
An Accurate, Easy to Use Abundace Scale for Globular Clusters Based on 2.2um Spectra of Giant Stars
We present a new method for the determination of [Fe/H] for globular
clusters. This new method is based on moderate resolution (R~1500) near-IR
spectroscopy in the K-band of 6 to 10 of the brightest giants in a cluster. Our
calibration is derived from spectra of 105 stars in 15 globular clusters. From
measurements of the equivalent widths of three features in these spectra, Na,
Ca, and CO, we are able to reproduce the Zinn & West (1984) abundance scale as
updated by Harris (1996) to better than 0.10 dex for clusters with near solar
[Fe/H] down to an [Fe/H] of -1.8. Three advantages of this method are that it
can be used for metal rich, heavily reddened globulars in crowded fields, it
does not require any knowledge of any other cluster or stellar parameters such
as reddening, distance, or luminosity, and it requires only minimal telescope
time. If stellar (J-K)0 and MK values are available as well, the accuracy of
the [Fe/H] estimate is further improved. Observations of as few as three stars
per cluster still gives an [Fe/H] estimate wich is nearly as reliable as that
based on two to three times as many stars.
The accuracy of an [Fe/H] value based on observations of CO absorption alone
is significantly less than that which results from the three spectroscopic
indices. However, we predict that space-based observations of this feature in
the integrated light of stellar systems will prove to be of great value for
abundance determinations at distances as far as the Coma cluster of galaxies.Comment: 53 pages, 16 Postscript figures. Submitted to the A
Phase separation and pairing regimes in the one-dimensional asymmetric Hubbard model
We address some open questions regarding the phase diagram of the
one-dimensional Hubbard model with asymmetric hopping coefficients and balanced
species. In the attractive regime we present a numerical study of the passage
from on-site pairing dominant correlations at small asymmetries to
charge-density waves in the region with markedly different hopping
coefficients. In the repulsive regime we exploit two analytical treatments in
the strong- and weak-coupling regimes in order to locate the onset of phase
separation at small and large asymmetries respectively.Comment: 13 pages, RevTeX 4, 12 eps figures, some additional refs. with
respect to v1 and citation errors fixe
V, J, H and K Imaging of the Metal Rich Globular Cluster NGC 6528
New near-infrared observations of NGC6528 are presented. The JHK observations
complement a previous HST/NICMOS data set by Ortolani et al. (2001), in that
they sample a larger area, contain a more numerous sample of red giant stars,
and include the K band. Also, archival HST data sets (separated by 6.093 years)
were used to proper-motion decontaminate the near-infrared sample and extract a
clean VJHK catalogue. Using the present wide colour baseline, we compared the
cleaned colour-magnitude diagrams of NGC6528 with those of NGC 6553 and NGC104
and derived new estimates of reddening and distance, E(B-V)=0.55 and
(m-M)o=14.44 (7.7 kpc). Moreover, the morphology and location of the cleaned
red giant branch were used to derive a photometric estimate of the cluster
metallicity. The average of 10 metallicity indicators yields a mean value of
[M/H] ~ 0.0, and [Fe/H] ~-0.20 and +0.08 on the Zinn & West (1984) and Carretta
& Gratton (1997) revised metallicity scale, respectively. The best isochrone
fit to the cleaned K,V-K diagram is obtained for a 12.6 Gyr and Z=0.02
isochrone, i.e. the derived metallicity of NGC6528 turns out to be very close
to the mean of stars in the Baade's Window. Five AGB variable star candidates,
whose membership has to be confirmed spectroscopically, are bolometrically as
bright as the known long period variable stars in NGC6553. As discussed in
Guarnieri et al. (1997) for NGC6553, this may indicate that an `intermediate
age' population is not needed to account for the brightest stars in external
galaxies such as M32.Comment: 11 pages, 9 figures, A&A accepte
Near-Infrared photometry of four metal-rich Bulge globular clusters: NGC6304, NGC6569, NGC6637, NGC6638
We present high-quality near-Infrared photometry of four Bulge metal-rich
globular clusters, namely: NGC 6304, NGC 6569, NGC 6637 and NGC 6638. By using
the observed Colour-Magnitude Diagrams we derived a photometric estimates of
the cluster reddening and distance. We performed a detailed analysis of the Red
Giant Branch, presenting a complete description of morphologic parameters and
evolutionary features (Bump and Tip). Photometric estimates of the cluster
metallicity have been obtained by using the updated set of relations (published
by our group) linking the metal abundance to a variety of near-Infrared indices
measured along the Red Giant Branch. The detection of the Red Giant Branch Bump
and the Tip is also presented and briefly discussed.Comment: 12 pages, 15 figures, accepted for publication in MNRA
Kinematics of the Galactic Globular Cluster System: New Radial Velocities for Clusters in the Direction of the Inner Galaxy
HIRES on the Keck I telescope has been used to measure the first radial
velocities for stars belonging to eleven, heavily-reddened globular clusters in
the direction of the inner Galaxy. The question of kinematic substructuring
among the Galactic globular cluster system is investigated using an updated
catalog of globular cluster distances, metallicities and velocities. It is
found that the population of metal-rich globular clusters shows significant
rotation at all Galactocentric radii. For the metal-rich clusters within 4 kpc
of the Galactic center, the measured rotation velocity and line-of-sight
velocity dispersion are similar to those of bulge field stars. We investigate
claims that the metal-rich clusters are associated with the central Galactic
bar by comparing the kinematics of the innermost clusters to that of the atomic
hydrogen in the inner Galaxy. The longitude-velocity diagram of both metal-rich
and metal-poor clusters bears a remarkable similarity to that of the gas,
including the same non-circular motions which have traditionally been
interpreted as evidence for a Galactic bar, or, alternatively, a
non-axisymmetric bulge. However, uncertainties in the existing
three-dimensional Galactocentric positions for most of the clusters do not yet
allow an unambiguous discrimination between the competing scenarios of
membership in a rigidly rotating bar, or in a bulge which is an oblate
isotropic rotator. We conclude that the majority of metal-rich clusters within
the central 4 kpc of the Galaxy are probably associated with the bulge/bar, and
not the thick disk. (ABRIDGED)Comment: 18 pages, including 7 of 13 postscript figures. Figures 1-6 available
at http://astro.caltech.edu/~pc. Accepted for publication in the Astronomical
Journa
Alimentação de bezerros com extrato hidrossolúvel de soja. II. Produção de anticorpos e distúrbios intestinais.
O Objetivo do trabalho foi avaliar a substituição total do sucedâneo lácteo Ă base de proteĂna de leite (SL) por extrato hidrossolĂşvel de soja (EHS) na alimentação de bezerros Holandeses machos, com idade mĂ©dia inicial de cinco dias. Os bezerros alimentados com EHS apresentaram diminuição visĂvel das gorduras presentes no tecido subcutâneo, omento, epĂplon e da gordura perirenal. No abomaso, a principal alteração verificada foi a falta de formação do coágulo do EHS ingerido
Polyamide Nanofibers Impregnated with Nitrile Rubber for Enhancing CFRP Delamination Resistance
Delamination is the main responsible for structural failure of composites having a laminar structure. In the present work, polyamide (Nylon 66) nanofibers, even impregnated with uncrosslinked nitrile butadiene rubber (NBR), are interleaved into epoxy-based carbon fiber reinforced polymer (CFRP) laminates with the aim to counteract the delamination phenomenon. The performance of nano-modified composites using both the nanofibrous mat types, that is, Nylon 66 and NBR-impregnated Nylon 66 membranes, is investigated. Mode I loading tests show a significant improvement of the interlaminar fracture toughness of rubber-modified CFRPs, especially in the G(I,)(R) (up to +151%). The improvement in the G(I,)(C) is less pronounced, but still significant (up to +80%). The achieved results are very encouraging and pave the way to the use of such Nylon-NBR hybrid mats for hindering delamination
Completion of death certificates in the aftermath of a hurricane
Death certificates are used widely for many critical uses. For example, families use them to close out estates as well as to reach emotional closure about the loss of their relative. Information from death certificates is also the fundamental source for official mortality statistics which are used to support statements such as \u201cThe impact of the 2005 Atlantic hurricane season and the resulting death, injury, destruction, and population displacement were unprecedented in U.S. history.\u201d (CDC. MGuide: Hurricanes, accessed at http://www.cdc.gov/mmwr/mguide_nd.html) and to more generally define the mortality scope and impact of particular events. Having more information about past events helps plan for future catastrophic storms.The medical examiner, coroner, or physician\u2019s primary responsibility in certifying or completing the death certificate is to provide a medical opinion on cause of death, that is, an etiological description of the order, type, and association of events resulting in death. In reporting the cause of death, any disease, abnormality, injury, or poisoning believed to have adversely affected the decedent should be reported as specifically and precisely as possible. He or she may also complete other legal and demographic items on the death certificate although normally a funeral director would complete this other information.200
Enhanced P2P Services Providing Multimedia Content
The retrieval facilities of most Peer-to-Peer (P2P) systems are limited to queries based on unique identifiers or small sets of keywords. Unfortunately, this approach is very inadequate and inefficient when a huge amount of multimedia resources is shared. To address this major limitation, we propose an original image and video sharing system, in which a user is able to interactively search interesting resources by means of content-based image and video retrieval techniques. In order to limit the network traffic load, maximizing the usefulness of each peer contacted in the query process, we also propose the adoption of an adaptive overlay routing algorithm, exploiting compact representations of the multimedia resources shared by each peer. Experimental results confirm the validity of the proposed approach, that is capable of dynamically adapting the network topology to peer interests, on the basis of query interactions among users
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