315 research outputs found
The colour-magnitude relations of ClJ1226.9+3332, a massive cluster of galaxies at z=0.89
(Abridged) The colour-magnitude relations of one of the most massive, high
redshift clusters of galaxies known have been studied. Photometry has been
measured in the V, R, I, z, F606W, F814W, J and K bands to a depth of K*+2.5
and spectroscopy confirms 27 K band selected cluster members. The V-K colours
are equivalent to a rest-frame colour of ~2700A-J, and provide a very sensitive
measure of star-formation activity. HST ACS imaging has been used to
morphologically classify the galaxies.
The cluster has a low early-type fraction compared to nearby clusters, with
only 33% of the cluster members having types E or S0. The early-type member
galaxies form a clear red-sequence in all colours. The scatter and slope of the
relations show no evolution compared to the equivalent Coma cluster relations,
suggesting the stellar populations are already very old. The normalisation of
the relations has been compared to models based on synthetic stellar
populations, and are most consistent with stellar populations forming at z>3.
Some late-type galaxies were found to lie on the red-sequence, suggesting that
they have very similar stellar populations to the early-types.
These results present a picture of a cluster in which the early-type galaxies
are all old, but in which there must be future morphological transformation of
galaxies to match the early-type fraction of nearby clusters. In order to
preserve the tight colour-magnitude relation of early-types seen in nearby
clusters, the late-type galaxies must transform their colours, through the
cessation of star-formation, before the morphological transformation occurs.
Such evolution is observed in the late-types lying on the colour-magnitude
relation.Comment: Accepted for publication in MNRAS. 14 pages, 5 figure
Security Technology by Using Firewall for Smart Grid
Due to the increasing development of computer systems and information networks, power grids should change extensively too. Nowadays, substantial movement has begun to implement the Smart Grid industry around the world. Since with the creation of smart electricity grids, it is possible to access the internal network from the external spaces, it is also necessary to protect information and data against unauthorized access. Therefore, a firewall should be used for information security. The firewall based on existing security regulations, decides which data is incoming to the network or going out of the network. Considering the discussions of passive defense topics at the national level and also the high importance of information security in Smart Grids, in this paper, in addition to examining the Firewalls, its advantages and disadvantages are also stated. Although the firewall has a major role in establishing security, and its installation and appropriate configuration can only be one of the primary activities in this field, we should also take advantage of other security mechanisms to enhance the security of the Smart Grid
Effect of drying process on antioxidant properties of date palm fruits
Aim. In order to identify antioxidant activities and phenolic compound, two varieties of date palm (Mazfati and Kalute varieties) (Phoenix dactylifera) fruits (DPF) from Iran systematically evaluated. Methods. Antioxidant activity determined using typical methods such as DPPH, reducing power and total antioxidant method. The total phenolic content of the dates was measured using Folin-Ciocalteau method. The included samples were gathered at three stages of khalaal, rutab, tamr and dried date from Sam and Jiroft date. The total phenolic content ranged from 1074, 856.4 and 723.8 in Mozafati variety and 921.5, 723.5 and 785.3 mg gallic acid equivalents (GAE/100-g-dw sample) in Kalute variety for khalal, rutab and tamr stage, respectively. Results. In both varieties antioxidant activities and total phenolic content decreased by ripening stages. Result of drying process showed that total phenolic content and antioxidant activities varied from temperature and decreased by increase of drying temperature. Conclusion. This research demonstrates Iranian dates could be potential rich resources of natural antioxidants, and could be developed into functional foods or drug for the prevention and treatment of diseases caused by oxidative stress
Evolution of the galaxy luminosity function in progenitors of fossil groups
Using the semi-analytic models based on the Millennium simulation, we trace
back the evolution of the luminosity function of galaxies residing in
progenitors of groups classified by the magnitude gap at redshift zero. We
determine the luminosity function of galaxies within , and for galaxy groups/clusters. The bright end of the galaxy
luminosity function of fossil groups shows a significant evolution with
redshift, with changes in by 1-2 mag between and
(for the central ), suggesting that the formation of the most
luminous galaxy in a fossil group has had a significant impact on the
galaxies e.g. it is formed as a result of multiple mergers of the
galaxies within the last Gyr. In contrast, the slope of the faint end,
, of the luminosity function shows no considerable redshift evolution
and the number of dwarf galaxies in the fossil groups exhibits no evolution,
unlike in non-fossil groups where it grows by towards low
redshifts. In agreement with previous studies, we also show that fossil groups
accumulate most of their halo mass earlier than non-fossil groups. Selecting
the fossils at a redshift of 1 and tracing them to a redshift 0, we show that
of the fossil groups () will lose their large magnitude gaps. However, about
of fossil clusters () will retain their large
gaps.Comment: Accepted for publication in A&A. 13 pages, 15 figure
Development of an IgG4-RD Responder Index
IgG4-related disease (IgG4-RD) is a multiorgan inflammatory disease in which diverse organ manifestations are linked by common histopathological and immunohistochemical features. Prospective studies of IgG4-RD patients are required to clarify the natural history, long-term prognosis, and treatment approaches in this recently recognized condition. Patients with IgG4-RD have different organ manifestations and are followed by multiple specialties. Divergent approaches to the assessment of patients can complicate the interpretation of studies, emphasizing the critical need for validated outcome measures, particularly assessments of disease activity and response to treatment. We developed a prototype IgG4-RD Responder Index (IgG4-RD RI) based on the approach used in the development of the Birmingham Vasculitis Activity Score for Wegener's granulomatosis (BVAS/WG). The IgG4-RD RI was refined by members of the International IgG4-RD Symposium Organizing Committee in a paper case exercise. The revised instrument was applied retrospectively to fifteen IgG4-RD patients at our institution. Those scores were compared to physician's global assessment scale for the same visits. This paper describes the philosophy and goals of the IgG4-RD RI, the steps in the development of this instrument to date, and future plans for validation of this instrument as an outcome measure
The evolution of the radio luminosity function of group galaxies in COSMOS
To understand the role of the galaxy group environment on galaxy evolution,
we present a study of radio luminosity functions (RLFs) of group galaxies based
on the Karl G. Jansky Very Large Array-COSMOS 3 GHz Large Project. The
radio-selected sample of 7826 COSMOS galaxies with robust optical/near-infrared
counterparts, excellent photometric coverage, and the COSMOS X-ray galaxy
groups (M_200c > 10^13.3 M_0) enables us to construct the RLF of group galaxies
(GGs) and their contribution to the total RLF since z ~ 2.3. Using the Markov
chain Monte Carlo algorithm, we fit a redshift-dependent pure luminosity
evolution model and a linear and power-law model to the luminosity functions.
We compare it with past RLF studies from VLA-COSMOS on individual populations
of radio-selected star-forming galaxies (SFGs) and galaxies hosting active
galactic nuclei (AGN). These populations are classified based on the presence
or absence of a radio excess concerning the star-formation rates derived from
the infrared emission. We find that the fraction of radio group galaxies
evolves by a factor of ~ 3 from z ~ 2 to the present day. The increase in the
galaxy group contribution is due to the radio activity in groups being nearly
constant at z < 1, while it is declining in the field. We show that massive
galaxies inside galaxy groups remain radio active below redshift 1, contrary to
the ones in the field. This evolution in the GG RLF is driven mainly by
satellite galaxies in groups. Group galaxies associated with SFGs dominate the
GG RLF at z_med = 0.3, while at z_med = 0.8, the peak in the RLF, coinciding
with a known overdensity in COSMOS, is mainly driven by AGN. The study provides
an observational probe for the accuracy of the numerical predictions of the
radio emission in galaxies in a group environment.Comment: submitted to A&A; 15 pages, 6 figures, 8 table
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