77 research outputs found
A new smart dynamic external fixator in the treatment of complex fractures of the proximal interphalangeal joint of the long fingers.
Treatment of articular fractures of the proximal interphalangeal (PIP) joint of the hand can be a hard challenge. Ideal treatment should include an anatomic reduction, stable fixation and the possibility of early finger mobilization to prevent joint stiffness. We propose for the treatment of these fractures a new smart dynamic external fixator (SDEF), derived from the device described by Suzuki and based on the concept of the capsuloligamentotaxis described by Vidal
Fossil group origins: VIII RXJ075243.6+455653 a transitionary fossil group
It is thought that fossil systems are relics of structure formation in the
primitive Universe. They are galaxy aggregations that have assembled their mass
at high redshift with few or no subsequent accretion. Observationally these
systems are selected by large magnitude gaps between their 1st and 2nd ranked
galaxies. Nevertheless, there is still debate over whether or not this
observational criterium selects dynamically evolved ancient systems. We have
studied the properties of the nearby fossil group RXJ075243.6+455653 in order
to understand the mass assembly of this system. Deep spectroscopic observations
allow us to construct the galaxy luminosity function (LF) of RXJ075243.6+455653
down to M*+ 6. The analysis of the faint-end of the LF in groups and clusters
provides valuable information about the mass assembly of the system. In
addition, we have analyzed the nearby large-scale structure around this group.
We identified 26 group members within r200=0.9 Mpc. The LF of the group shows a
flat faint-end slope ( -1.08 +/- 0.33). This low density of dwarf galaxies is
confirmed by the low value of the dwarf-to-giant ratio (DGR = 0.99 +/- 0.49)
for this system. Both the lack of dwarf galaxies and the low luminosity of the
BGG suggests that RXJ075243.6+455653 still has to accrete mass from its nearby
environment. This mass accretion will be achieved because it is the dominant
structure of a rich environment formed by several groups of galaxies (15)
within 7 Mpc from the group center and with +/- 1000$ km/s. RXJ075243.6+455653
is a group of galaxies that has not yet completed the process of its mass
assembly. This new mass accretion will change the fossil state of the group.
This group is an example of a galaxy aggregation selected by a large magnitude
gap but still in the process of the accretion of its mass (Abridged).Comment: 9 pages, 9 figures, accepted in A&
The relation between bar formation, galaxy luminosity, and environment
We derive the bar fraction in three different environments ranging from the
field to Virgo and Coma clusters, covering an unprecedentedly large range of
galaxy luminosities (or, equivalently, stellar masses). We confirm that the
fraction of barred galaxies strongly depends on galaxy luminosity. We also show
that the difference between the bar fraction distributions as a function of
galaxy luminosity (and mass) in the field and Coma cluster are statistically
significant, with Virgo being an intermediate case. We interpret this result as
a variation of the effect of environment on bar formation depending on galaxy
luminosity. We speculate that brighter disk galaxies are stable enough against
interactions to keep their cold structure, thus, the interactions are able to
trigger bar formation. For fainter galaxies the interactions become strong
enough to heat up the disks inhibiting bar formation and even destroying the
disks. Finally, we point out that the controversy regarding whether the bar
fraction depends on environment could be resolved by taking into account the
different luminosity ranges of the galaxy samples studied so far.Comment: 4 pages, 2 figures. To appear in the proceedings of EWASS 2012
Special Session 4, Structure of galaxy disks shaped by secular evolution and
environmental processes, ed. P. Di Matteo and C. Jog, Memorie della Societ\`a
Astronomica Italiana Supplement Serie
Fossil group origins XIII. A paradigm shift: fossil groups as isolated structures rather than relics of the ancient Universe
In this work we study the large-scale structure around a sample of non-fossil
systems and compare the results with earlier findings for a sample of genuine
fossil systems selected using their magnitude gap. We compute the distance from
each system to the closest filament and intersection as obtained from a
catalogue of galaxies in the redshift range . We then
estimate the average distances and distributions of cumulative distances to
filaments and intersections for different bins of magnitude gap. We find that
the average distance to filaments is for fossil
systems, whereas it is for non-fossil systems.
Similarly, the average distance to intersections is larger in fossil than in
non-fossil systems, with values of and , respectively. Moreover, the cumulative distributions of distances
to intersections are statistically different between fossil and non-fossil
systems. Fossil systems selected using the magnitude gap appear to be, on
average, more isolated from the cosmic web than non-fossil systems. No
dependence is found on the magnitude gap (i.e. non-fossil systems behave in a
similar manner independently of their magnitude gap and only fossils are found
at larger average distances from the cosmic web). This result supports a
formation scenario for fossil systems in which the lack of infalling galaxies
from the cosmic web, due to their peculiar position, favours the building of
the magnitude gap via the merging of all the massive satellites with the
central galaxy. Comparison with numerical simulations suggests that fossil
systems selected using the magnitude gap are not old fossils of the ancient
Universe, but systems located in regions of the cosmic web not influenced by
the presence of intersections.Comment: 6 pages, 3 figure, accepted for publication in A&
Cobalt, chromium and molybdenum ions kinetics in the human body: data gained from a total hip replacement with massive third body wear of the head and neuropathy by cobalt intoxication.
6openopenPazzaglia, U; Apostoli, P; Congiu, T; Catalani, S; Marchese, M; Zarattini, G.Pazzaglia, Ugo; Apostoli, Pietro; Congiu, T; Catalani, S; Marchese, M; Zarattini, Guid
Fossil group origins - VI. Global X-ray scaling relations of fossil galaxy clusters
We present the first pointed X-ray observations of 10 candidate fossil galaxy
groups and clusters. With these Suzaku observations, we determine global
temperatures and bolometric X-ray luminosities of the intracluster medium (ICM)
out to for six systems in our sample. The remaining four systems show
signs of significant contamination from non-ICM sources. For the six objects
with successfully determined properties, we measure global
temperatures in the range ,
bolometric X-ray luminosities of , and estimate masses,
as derived from , of .
Fossil cluster scaling relations are constructed for a sample that combines our
Suzaku observed fossils with fossils in the literature. Using measurements of
global X-ray luminosity, temperature, optical luminosity, and velocity
dispersion, scaling relations for the fossil sample are then compared with a
control sample of non-fossil systems. We find the fits of our fossil cluster
scaling relations are consistent with the relations for normal groups and
clusters, indicating fossil clusters have global ICM X-ray properties similar
to those of comparable mass non-fossil systems.Comment: 17 pages, 7 figures, 8 tables. Accepted for publication in MNRA
A newly identified galaxy group thanks to tidal streams of intragroup light
In the accretion-driven growth scenario, part of the intracluster light is
formed in the group environment. We report the serendipitous discovery of a
group of galaxies with signs of diffuse light in the foreground of the known
galaxy cluster MACS J0329-0211 at z=0.45. Our investigation began with the
detection of diffuse light streams around a pair of bright galaxies in the
southeastern region of a Suprime-Cam image of the galaxy cluster MACS
J0329-0211. Our analysis is based on the extended CLASH-VLT redshift catalog
and on new spectroscopic data obtained ad hoc with the Italian Telescopio
Nazionale Galileo. We use the density reconstruction method to analyze the
redshift distribution of the galaxies in the region around the galaxy pair. We
also use available photometric and X-ray data to better characterize the
properties of the group. Thanks to the large amount of redshift data collected
in this region, we have been able to discover the existence of a group of
galaxies, here called GrG J0330-0218, which is associated with the pair of
galaxies. These are the two brightest group galaxies (BGG1 and BGG2). We
extracted 41 group members from the redshift catalog and estimate a mean
redshift z=0.1537 and a line-of-sight velocity dispersion sigmav=370 km/s. In
the phase-space diagram, the distribution of the galaxies of GrG J0330-0218
follows the characteristic trumpet-shaped pattern, which is related to the
escape velocity of galaxy clusters, suggesting that the group is a virialized
structure. Under this assumption, the mass of the group is M200 about 6E13
Msun. We also measured a mass-to-light ratio of 130 Msun/Lsun and a luminosity
fraction of diffuse light of about 20% within 0.5 R200. We conjecture that
galaxy pairs that are surrounded by diffuse light, probably due to tidal
interactions, can serve as signposts for groups.Comment: Astronomy & Astrophysics accepted, 13 pages, 10 figure
Fossil Groups Origins III. The relation between optical and X-ray luminosities
This study is part of the FOssil Groups Origin (FOGO) project which aims at
carrying out a systematic and multiwavelength study of a large sample of fossil
systems. Here we focus on the relation between the optical luminosity (Lopt)
and X-ray luminosity (Lx). Out of a sample of 28 candidate fossil systems, we
consider a sample of 12 systems whose fossil classification has been confirmed
by a companion study. They are compared with the complementary sample of 16
systems whose fossil nature is not confirmed and with a subsample of 102 galaxy
systems from the RASS-SDSS galaxy cluster survey. Fossil and normal systems
span the same redshift range 0<z<0.5 and have the same Lx distribution. For
each fossil system, the Lx in the 0.1-2.4 keV band is computed using data from
the ROSAT All Sky Survey. For each fossil and normal system we homogeneously
compute Lopt in the r-band within the characteristic cluster radius, using data
from the SDSS DR7. We sample the Lx-Lopt relation over two orders of magnitude
in Lx. Our analysis shows that fossil systems are not statistically
distinguishable from the normal systems both through the 2D KS test and the fit
of the Lx-Lopt relation. The optical luminosity of the galaxy system does
strongly correlate with the X-ray luminosity of the hot gas component,
independently of whether the system is fossil or not. We conclude that our
results are consistent with the classical "merging scenario" of the brightest
galaxy formed via merger/cannibalism of other group galaxies, with conservation
of the optical light. We find no evidence for a peculiar state of the hot
intracluster medium.Comment: A&A, 12 pages, 4 figures, 3 tables, typos corr. and paper re-numbe
Fossil group origins V. The dependence of the luminosity function on the magnitude gap
In nature we observe galaxy aggregations that span a wide range of magnitude
gaps between the two first-ranked galaxies of a system (). There
are systems with gaps close to zero (e.g., the Coma cluster), and at the other
extreme of the distribution, the largest gaps are found among the so-called
fossil systems. Fossil and non-fossil systems could have different galaxy
populations that should be reflected in their luminosity functions. In this
work we study, for the first time, the dependence of the luminosity function
parameters on using data obtained by the fossil group origins
(FOGO) project. We constructed a hybrid luminosity function for 102 groups and
clusters at . We stacked all the individual luminosity functions,
dividing them into bins of , and studied their best-fit
Schechter parameters. We additionally computed a relative luminosity function,
expressed as a function of the central galaxy luminosity, which boosts our
capacity to detect differences, especially at the bright end. We find trends as
a function of at both the bright and faint ends of the
luminosity function. In particular, at the bright end, the larger the magnitude
gap, the fainter the characteristic magnitude . We also find
differences at the faint end. In this region, the larger the gap, the flatter
the faint-end slope . The differences found at the bright end support a
dissipationless, dynamical friction-driven merging model for the growth of the
central galaxy in group- and cluster-sized halos. The differences in the faint
end cannot be explained by this mechanism. Other processes, such as enhanced
tidal disruption due to early infall and/or prevalence of eccentric orbits, may
play a role. However, a larger sample of systems with is
needed to establish the differences at the faint end.Comment: 11 pages, 10 figures, accepted for publication in A&
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