181 research outputs found
Beyond the Hubble Deep Field Limiting Magnitude: Faint Galaxy Number Counts from Surface-Brightness Fluctuations
The faint end of the differential galaxy number counts, n(m), in the Hubble
Deep Field (HDF) North has been determined for the F450W, F606W, and F814W
filters by means of surface-brightness fluctuation (SBF) measurements. This
technique allows us to explore n(m) beyond the limiting magnitude of the HDF,
providing new, stronger constraints on the faint end of n(m). This has allowed
us to test the validity of previous number count studies and to produce a new
determination of the faint end of n(m) for magnitudes fainter than 28.8 in the
AB system and to extend this estimate down to 31. This value represents an
extension of more than two magnitudes beyond the limits of previous photometric
studies. The obtained n(m) slopes are \gamma=0.27, 0.21, and 0.26 in B_{450},
V_{606}, and I_{814}, respectively.Comment: 36 pages, 7 figures and 10 tables, accepted for publication in Ap
The joint structureâfunction dynamics of glaucoma progression
While the presence and rate of glaucoma progression influence treatment decisions, the methods currently available to detect and monitor progression are imprecise and do not allow clinicians to make accurate assessments of the status of their patients. Models that focus on combining structural and functional parameters may improve our ability to detect and monitor glaucoma progression. Several of these models, however, are limited by their reliance on population statistics and on the static assumptions they make about the nature of glaucoma progression. Dynamic modeling of glaucoma progression may lead to a better understanding of glaucoma progression that could eventually translate into making individualized treatment decisions
Structure-ÂFunction Associations in Healthy and Glaucoma Eyes
poster abstractPurpose:
To determine whether differences exist in the structure--âfunction associations between healthy and glaucoma eyes.
Methods:
Structure--âfunction associations were assessed in three different datasets. First, in the Diagnostic Innovation and Glaucoma Study and African Descent and Glaucoma Evaluation Study, associations between rim area (RA) (Heidelberg Retina Tomography II) and both mean sensitivity (MS) and mean deviation (MD) from conventional automated perimetry (CAP) were assessed in 698 healthy subjects and 1036 glaucoma patients. Associations between retinal nerve fiber layer thickness (RNFLT) from the Spectralis optical coherence tomography (OCT) (Heidelberg Engineering) and MS or MD from CAP were assessed in 198 healthy subjects and 634 glaucoma patients. Second, in the dataset used in Swanson et al (2014), the association between RNFLT from the Stratus OCT (Heidelberg Engineering) and MD from CAP, measures from contrast sensitivity perimetry (CSP--â2), and from frequency--âdoubling perimetry (FDP) in the superior temporal (ST) and inferior temporal (IT) optic disc sectors were assessed in 62 healthy subjects and 51 glaucoma patients. Third, in a dataset obtained from Iowa University, association between RNFLT and relative field sensitivity was assessed in 79 healthy subjects. All associations were assessed with the generalized estimating equation (GEE) procedure, linear mixed effect model (LMM), and the Pearson, Spearman and Kendall correlations. Age was included to adjust for its confounding effect in all GEE and LMM models.
Results:
For healthy eyes, no significant structure--âfunction association was found using GEE, Pearson, Spearman and Kendall correlations. With LMM, a significant association was found between RNFLT and both MS and MD. For glaucoma eyes, significant associations were found with all methods.
Conclusion:
Significant structure--âfunction associations were identified in glaucoma eyes but not in healthy ones. This suggests that the structure--âfunction associations should be considered separately in healthy and glaucoma eyes because of the different nature of the associations. Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis IN, US. Departamento de Ăptica. Facultad de FĂsica. Universitat de València, Burjassot, Valencia, Spain. Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis IN, US. Eugene and Marilyn Glick Eye Institute, Indiana University, Indianapolis IN, US.
Acknowledgement:
This project was supported in part by the BrightFocus Foundation grant G2014096, IUPUI DRIVE grant, and by an unrestricted grant from Research to Prevent Blindness. The DIGS and ADAGES studies were supported by National Institutes of Health grants P30EY022589, EY021818, EY11008, U10EY14267, EY019869, and by the Eyesight Foundation of Alabama, Alcon Laboratories, Inc., Allergan, Inc;, Pfizer, Inc., Merck, Inc., Santen, Inc., the Edith C. Blum Research Fund of the New York Glaucoma Research Institute (New York, NY), and by an unrestricted grant from Research to Prevent Blindness. The study reported in Swanson et al (2014) was supported by National Institutes of Health grants R01EY007716 (Swanson) and 5P30EY019008 (Indiana University School of Optometry). One of the authors (RM) received a portion of his funding from the Department of Healthâs NIHR Biomedical Research Centre at Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology. We thank Michael Wall and Randy Kardon for providing the control data for healthy eyes collected at University of Iowa Hospitals and Clinics
The miniJPAS survey : A preview of the Universe in 56 colors
The Javalambre-Physics of the Accelerating Universe Astrophysical Survey (J-PAS) will scan thousands of square degrees of the northern sky with a unique set of 56 filters using the dedicated 2.55 m Javalambre Survey Telescope (JST) at the Javalambre Astrophysical Observatory. Prior to the installation of the main camera (4.2 deg(2) field-of-view with 1.2 Gpixels), the JST was equipped with the JPAS-Pathfinder, a one CCD camera with a 0.3 deg(2) field-of-view and plate scale of 0.23 arcsec pixel(-1). To demonstrate the scientific potential of J-PAS, the JPAS-Pathfinder camera was used to perform miniJPAS, a similar to 1 deg(2) survey of the AEGIS field (along the Extended Groth Strip). The field was observed with the 56 J-PAS filters, which include 54 narrow band (FWHM similar to 145 angstrom) and two broader filters extending to the UV and the near-infrared, complemented by the u, g, r, i SDSS broad band filters. In this miniJPAS survey overview paper, we present the miniJPAS data set (images and catalogs), as we highlight key aspects and applications of these unique spectro-photometric data and describe how to access the public data products. The data parameters reach depths of mag(AB) similar or equal to 22-23.5 in the 54 narrow band filters and up to 24 in the broader filters (5 sigma in a 3 '' aperture). The miniJPAS primary catalog contains more than 64 000 sources detected in the r band and with matched photometry in all other bands. This catalog is 99% complete at r = 23.6 (r = 22.7) mag for point-like (extended) sources. We show that our photometric redshifts have an accuracy better than 1% for all sources up to r = 22.5, and a precision of 2. The miniJPAS survey demonstrates the capability of the J-PAS filter system to accurately characterize a broad variety of sources and paves the way for the upcoming arrival of J-PAS, which will multiply this data by three orders of magnitude.Peer reviewe
Separating the conjoined red clump in the Galactic Bulge: Kinematics and Abundances
We have used the AAOMEGA spectrograph to obtain R spectra of 714
stars that are members of two red clumps in the Plaut Window Galactic bulge
field . We discern no difference between the clump
populations based on radial velocities or abundances measured from the Mg
index. The velocity dispersion has a strong trend with Mg-index metallicity,
in the sense of a declining velocity dispersion at higher metallicity. We also
find a strong trend in mean radial velocity with abundance. Our red clump
sample shows distinctly different kinematics for stars with [Fe/H] , which
may plausibly be attributable to a minority classical bulge or inner halo
population. The transition between the two groups is smooth. The
chemo-dynamical properties of our sample are reminiscent of those of the Milky
Way globular cluster system. If correct, this argues for no bulge/halo
dichotomy and a relatively rapid star formation history. Large surveys of the
composition and kinematics of the bulge clump and red giant branch are needed
to define further these trends.Comment: 5 pages, 4 figures, Accepted for Publication in the Astrophysical
Journal Letters Fixed typos, updated affiliations and added some references
upon reques
Rational direct synthesis methodology of very active and hydrothermally stable Cu-SAPO-34 molecular sieves for the SCR of NOx
A one-pot direct synthesis of Cu-SAPO-34 has been achieved that allows more than 90% yield in the material synthesis. By this method it is easy to control the Cu-loading in the Cu-SAPO-34. It is presented that a maximum in hydrothermal stability with very high activity for NOx SCR with NH3 is obtained for an optimum Cu loading.This work has been supported by Haldor-Topsoe, Consolider Ingenio 2010-Multicat, and UPV through PAID-06-11 (no. 1952). MM acknowledges to "Subprograma Ramon y Cajal" for the contract RYC-2011-08972.MartĂnez Franco, R.; Moliner Marin, M.; Franch MartĂ, C.; Kustov, A.; Corma CanĂłs, A. (2012). Rational direct synthesis methodology of very active and hydrothermally stable Cu-SAPO-34 molecular sieves for the SCR of NOx. Applied Catalysis B: Environmental. 127:273-280. https://doi.org/10.1016/j.apcatb.2012.08.034S27328012
Intergalactic globular clusters and the faint end of the galaxy number counts in A1656 (Coma)
The existence of an intergalactic globular cluster population in the Coma
cluster of galaxies has been tested using surface-brightness fluctuations. The
main result is that the intergalactic globular cluster surface density () does not correlate with the distance to the center of Coma and hence
with the environment. Furthermore, comparing these results with different Coma
mass-distribution model predictions, it is suggested that must in
fact be zero all over Coma. On the other hand, the results for
and the faint end of the galaxy number counts (beyond ) are
connected. So settles the slope of this function, which turns
out to be down to .
The fact that all over Coma suggests that globular clusters
were formed only, or almost only, from protogalactic clouds. None, or perhaps
very few, could have formed in isolated regions. It also seems inappropriate to
advocate a relationship between intergalactic globular clusters and dark matter
distributions, although it is true that the relationship could still exist but
not be strong enough to have been detected. Finally, since our conclusion is
that intergalactic globular clusters do not exist in Coma, accretion of
intergalactic globular clusters might not be significant in galaxy formation
and evolutionary processes in the Coma galaxies.Comment: 23 pages, 5 figures, accepted for publication in Ap
Statistical analysis of dwarf galaxies and their globular clusters in the Local Volume
Morphological classification of dwarf galaxies into early and late type,
though can account for some of their origin and characteristics but does not
help to study their formation mechanism. So an objective classification using
Principal Component analysis together with K means Cluster Analysis of these
dwarf galaxies and their globular clusters is carried out to overcome this
problem. It is found that the classification of dwarf galaxies in the Local
Volume is irrespective of their morphological indices. The more massive (MV 0 <
-13.7) galaxies evolve through self-enrichment and harbor dynamically less
evolved younger globular clusters (GCs) whereas fainter galaxies (MV 0 > -13.7)
are influenced by their environment in the star formation process.Comment: 22 pages, 10 figures, 5 tables, published in Ap
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The ACS Survey Of Galactic Globular Clusters. VI. NGC 6366: A Heavily Stripped Galactic Globular Cluster
We have used observations obtained as part of the Hubble Space Telescope/ACS Survey of Galactic globular clusters (GCs) to construct a color-magnitude diagram for the bulge cluster, NGC 6366. The luminosity function derived from those data extends to M(F606W) similar to 9, or masses of similar to 0.3 M(circle dot). Unlike most GCs, the mass function peaks near the main-sequence turnoff with significantly fewer low-mass stars even after correction for completeness and mass segregation. Using a multimass King model, we extrapolate the global cluster behavior and find the global mass function to be poorly matched by a power law, with a particular deficit of stars with masses between 0.5 and 0.7 M(circle dot). We briefly discuss this interesting anomaly within the context of tidal stripping.NASA GO-10775, 5-26555Space Telescope Science InstituteInstituto de Astrofisica de Canarias P3-94Ministry of Education and Science of the Kingdom of Spain AYA-2008-67913Astronom
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