954 research outputs found
Galaxies infalling into groups: filaments vs. isotropic infall
We perform a comparative analysis of the properties of galaxies infalling
into groups classifying them accordingly to whether they are: falling along
filamentary structures; or they are falling isotropically. For this purpose, we
identify filamentary structures connecting massive groups of galaxies in the
SDSS. We perform a comparative analysis of some properties of galaxies in
filaments, in the isotropic infall region, in the field, and in groups. We
study the luminosity functions (LF) and the dependence of the specific star
formation rate (SSFR) on stellar mass, galaxy type, and projected distance to
the groups that define the filaments. We find that the LF of galaxies in
filaments and in the isotropic infalling region are basically indistinguishable
between them, with the possible exception of late-type galaxies. On the other
hard, regardless of galaxy type, their LFs are clearly different from that of
field or group galaxies. Both of them have characteristic absolute magnitudes
and faint end slopes in between the field and group values. More significant
differences between galaxies in filaments and in the isotropic infall region
are observed when we analyse the SSFR. We find that galaxies in filaments have
a systematically higher fraction of galaxies with low SSFR as a function of
both, stellar mass and distance to the groups, indicating a stronger quenching
of the star formation in the filaments compared to both, the isotropic
infalling region, and the field. Our results suggest that some physical
mechanisms that determine the differences observed between field galaxies and
galaxies in systems, affect galaxies even when they are not yet within the
systems.Comment: Accepted in MNRAS, 10 pages, 8 figure
The evolution of the bi-modal colour distribution of galaxies in SDSS groups
We analyse colour distributions for several samples of galaxies in
groups drawn from the Fourth Data Release of the Sloan Digital Sky Survey. For
all luminosity ranges and environments considered the colour distributions are
well described by the sum of two Gaussian functions. We find that the fraction
of galaxies in the red sequence is an increasing function of group virial mass.
We also study the evolution of the galaxy colour distributions at low redshift,
in the field and in groups for galaxies brighter than
, finding significant evidence of recent evolution in the
population of galaxies in groups. The fraction of red galaxies monotonically
increases with decreasing redshift, this effect implies a much stronger
evolution of galaxies in groups than in the field.Comment: 7 pages, 6 figures, submited to MNRAS after minor revisio
Garden City: Multicultural Issues in Adult Education
Kansas adult education is faced with the growing challenge to prepare its programs for serving the needs of a socioculturally diverse student population. It is imperative that Adult Basic Education (ABE) programs develop effective learning techniques for multicultural student populations. These issues continue to be important topics for educators, administrators, and politicians
Operational-level Optimization of Inbound Intralogistics
This study is concerned with optimizing inbound operations at distribution centers (DCs), warehouses, and cross-docks with staging areas. The objective of the problem is to minimize the makespan required to move all unit loads from the trailers to the flow racks, and from the flow racks to their respective storage locations. It is assumed that a set of inbound trailers with known composition have been assigned and sequenced to inbound dock doors. The following three inbound logistics decisions are simultaneously considered: i) unloadersâ assignment and scheduling, ii) loads-to-flow rack assignment, and iii) assignment and haulersâ scheduling. In this study we describe the relationship between the problem of minimizing makespan and an unloader-hauler balancing problem. Three rule-based heuristics are proposed and evaluated in an instance of the problem
Groups of galaxies: relationship between environment and galaxy properties
We analyse how the properties of galaxies in groups identified in the Sloan
Digital Sky Survey depend on the environment. In particular, we study the
relationship between galaxy properties and group mass and group-centric
distance. Among the galaxy properties we have considered here, we find that the
colour is the most predictive parameter for group mass, while the most
predictive pair of properties are colour and band absolute magnitude.
Regarding the position inside the systems, the colour is the best tracer
of group-centric distance and the most predictive pair of properties are
colour and spectral type taken together. These results remain unchanged when a
subsample of high mass groups is analysed. The same happens if the brightest
group galaxies are excluded.Comment: 5 pages, 3 figures, accepted in MNRA
Real-time Dock Door Monitoring System Using a Kinect Sensor
This study presents a proof of concept where a single Microsoft Kinect sensor is used for automated monitoring of a dock door in real-time. The proposed system will automatically and in real-time: (1) detect when an object breaches the dock door perimeter, and its corresponding speed and direction, (2) count the number of pallets loaded/unloaded to/from a trailer, (3) record the loading/unloading time of each load, and (4) reconstruct an image of every loading/unloading trip at a dock door, irrespectively of the material handling travel speed and direction. Particular emphasis is given to discussing how to extend the proposed concept by using multiple Kinect sensors, the technological challenges for implementation, and the expected benefits of a real-time dock door monitoring syste
The galaxy density environment of gamma-ray burst host galaxies
We analyze cross-correlation functions between Gamma-Ray Burst (GRB) hosts
and surrounding galaxies. We have used data obtained with the Very Large
Telescope at Cerro Paranal (Chile), as well as public Hubble Space Telescope
data. Our results indicate that Gamma-Ray Burst host galaxies do not reside in
high galaxy density environments. Moreover, the host-galaxy cross-correlations
show a relatively low amplitude. Our results are in agreement with the
cross-correlation function between star-forming galaxies and surrounding
objects in the HDF-N.Comment: 6 figures, accepted for publication in Ap
Clustering and light profiles of galaxies in the environment of 20 Ultra Steep Spectrum Radio sources
We have analyzed galaxy properties in the neighborhood of 20 Ultra-Steep
Spectrum Radio sources (USS) taken from the WISH catalog of De Breuck et al.
(2002). Galaxies in these USS fields were identified in deep observations that
were carried out in the K'-band using the OSIRIS imager at the CTIO 4m
telescope. We find a statistically significant signal of clustering around our
sample of USS. The angular extension of the detected USS-galaxy clustering is
theta_c~20" corresponding to a spatial scale ~120 h^{-1}kpc, assuming the
sources are at z~1 in a Omega_m=0.3, Omega_{\Lambda}=0.7 model universe. These
results are in agreement with those obtained by Best (2000) for radio
galaxy-galaxy correlation, and Best et al. (2003) for radio-loud AGN-galaxy
correlation. We have also analyzed the light distribution of the galaxies by
fitting Sersic's law profiles. Our results show no significant dependence of
the galaxy shape parameters on the projected distance to the USS.Comment: Accepted for its publication in Astronomical Journal, 9 figure
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