7,379 research outputs found
On the formation and physical properties of the Intra-Cluster Light in hierarchical galaxy formation models
We study the formation of the Intra-Cluster Light (ICL) using a semi-analytic
model of galaxy formation, coupled to merger trees extracted from N-body
simulations of groups and clusters. We assume that the ICL forms by (1) stellar
stripping of satellite galaxies and (2) relaxation processes that take place
during galaxy mergers. The fraction of ICL in groups and clusters predicted by
our models ranges between 10 and 40 per cent, with a large halo-to-halo scatter
and no halo mass dependence. We note, however, that our predicted ICL fractions
depend on the resolution: for a set of simulations with particle mass one order
of magnitude larger than that adopted in the high resolution runs used in our
study, we find that the predicted ICL fractions are ~30-40 per cent larger than
those found in the high resolution runs. On cluster scale, large part of the
scatter is due to a range of dynamical histories, while on smaller scale it is
driven by individual accretion events and stripping of very massive satellites,
, that we find to be the major contributors
to the ICL. The ICL in our models forms very late (below ), and a
fraction varying between 5 and 25 per cent of it has been accreted during the
hierarchical growth of haloes. In agreement with recent observational
measurements, we find the ICL to be made of stars covering a relatively large
range of metallicity, with the bulk of them being sub-solar.Comment: Accepted for Publication in MNRAS, 19 pages, 13 figures, 1 tabl
Milky Way type galaxies in a LCDM cosmology
We analyse a sample of 52,000 Milky Way (MW) type galaxies drawn from the
publicly available galaxy catalogue of the Millennium Simulation with the aim
of studying statistically the differences and similarities of their properties
in comparison to our Galaxy. Model galaxies are chosen to lie in haloes with
maximum circular velocities in the range 200-250 km/seg and to have
bulge-to-disk ratios similar to that of the Milky Way. We find that model MW
galaxies formed quietly through the accretion of cold gas and small satellite
systems. Only 12 per cent of our model galaxies experienced a major merger
during their lifetime. Most of the stars formed in situ, with only about 15 per
cent of the final mass gathered through accretion. Supernovae and AGN feedback
play an important role in the evolution of these systems. At high redshifts,
when the potential wells of the MW progenitors are shallower, winds driven by
supernovae explosions blow out a large fraction of the gas and metals. As the
systems grow in mass, SN feedback effects decrease and AGN feedback takes over,
playing a more important role in the regulation of the star formation activity
at lower redshifts. Although model Milky Way galaxies have been selected to lie
in a narrow range of maximum circular velocities, they nevertheless exhibit a
significant dispersion in the final stellar masses and metallicities. Our
analysis suggests that this dispersion results from the different accretion
histories of the parent dark matter haloes. Statically, we also find evidences
to support the Milky Way as a typical Sb/Sc galaxy in the same mass range,
providing a suitable benchmark to constrain numerical models of galaxy
formationComment: 10 pages, 7 figures, mne2.cls, MNRAS, replaced with accepted versio
Statistics of Substructures in Dark Matter Haloes
We study the amount and distribution of dark matter substructures within dark
matter haloes, using a large set of high-resolution simulations ranging from
group size to cluster size haloes, and carried our within a cosmological model
consistent with WMAP 7-year data. In particular, we study how the measured
properties of subhaloes vary as a function of the parent halo mass, the
physical properties of the parent halo, and redshift. The fraction of halo mass
in substructures increases with increasing mass. There is, however, a very
large halo-to-halo scatter that can be explained only in part by a range of
halo physical properties, e.g. concentration. At given halo mass, less
concentrated haloes contain significantly larger fractions of mass in
substructures because of the reduced strength of tidal disruption. Most of the
substructure mass is located at the outskirts of the parent haloes, in
relatively few massive subhaloes. This mass segregation appears to become
stronger at increasing redshift, and should reflect into a more significant
mass segregation of the galaxy population at different cosmic epochs. When
haloes are accreted onto larger structures, their mass is significantly reduced
by tidal stripping. Haloes that are more massive at the time of accretion
(these should host more luminous galaxies) are brought closer to the centre on
shorter time-scales by dynamical friction, and therefore suffer of a more
significant stripping. The halo merger rate depends strongly on the environment
with substructure in more massive haloes suffering more important mergers than
their counterparts residing in less massive systems. This should translate into
a different morphological mix for haloes of different mass.Comment: 13 pages, 11 figures and 1 table. MNRAS 2011 in pres
Assessment of the quality of contract translations
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressĂŁoAnĂĄlise de traduçÔes de contratos utilizando-se o modelo de avaliação de qualidade proposto por Juliane House. Descrição do modelo e aplicação do mesmo a dois contratos redigidos em lĂngua inglesa e a trĂȘs traduçÔes de cada um para a lĂngua portuguesa. Descrição dos problemas de equivalĂȘncia encontrados. Apresentação de conclusĂ”es acerca da aplicabilidade do modelo de Juliane House para a avaliasĂŁo de traduçÔes de contratos
Investigating norms in the brazilian official translation of semiotic items, culture-bound items, and translator's paratextual interventions
Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e ExpressĂŁo. Programa de PĂłs-Graduação em Letras/InglĂȘs e Literatura Correspondente.A descriptive approach is used in this study to investigate the norms that are responsible for the constraints limiting the translator's choices when dealing with three specific aspects of official translation in Brazil: the translation of semiotic items; the translation of culture-bound items, and the insertion of paratextual interventions. An analysis was conducted of translations of the following documents: academic transcripts, birth or marriage certificates, driver's licenses, police record certificates and diplomas. By using these textual sources, and also extratextual sources, this study sought to answer the following questions: What are the strategies most frequently employed by the 42 official translators participating in this study when translating coats of arms, stamps and signatures? How are school names, units of measurement and some specific phraseologisms commonly found in official documents translated? What kinds of translator's comments and notes do official translators usually add to their translated texts? The strategies used were analyzed, and possible reasons for the translator's behavior were suggested. In addition, categorizations were proposed for the strategies employed in the translation of semiotic items and for the types of translator's interventions appearing in official translations done in Brazil with the Portuguese-English language pair. Este estudo utiliza uma abordagem descritiva para investigar as normas que impĂ”em restriçÔes Ă s opçÔes do tradutor ao lidar com trĂȘs aspectos especĂficos da tradução juramentada no Brasil: a tradução de itens semiĂłticos; a tradução de marcadores culturais e a inclusĂŁo de intervençÔes paratextuais. TraduçÔes dos seguintes documentos foram analisadas: histĂłricos escolares, certidĂ”es de nascimento ou casamento, carteiras de habilitação, atestados de antecedentes e diplomas. Utilizando essas fontes textuais bem como fontes extra-textuais, este estudo objetivou responder Ă s seguintes perguntas: Quais as estratĂ©gias mais freqĂŒentemente utilizadas pelos 42 Tradutores Juramentados que participaram deste estudo ao traduzir brasĂ”es, carimbos e assinaturas? Como sĂŁo traduzidos os nomes de escolas, as unidades de medidas e alguns fraseologismos especĂficos normalmente encontrados nos documentos oficiais traduzidos? Que tipos de comentĂĄrios e notas os tradutores juramentados normalmente inserem em suas traduçÔes? As estratĂ©gias utilizadas foram analisadas e foram sugeridas as possĂveis razĂ”es para o comportamento tradutĂłrio. AlĂ©m disso, foram propostas categorizaçÔes para as estratĂ©gias utilizadas na tradução de itens semiĂłticos e para os tipos de intervençÔes do tradutor encontradas nas traduçÔes juramentadas feitas no Brasil com o par lingĂŒĂstico portuguĂȘs-inglĂȘs
Kaon physics with the KLOE detector
In this paper we discuss the recent finalized analyses by the KLOE experiment
at DANE: the CPT and Lorentz invariance test with entangled pairs, and the precision measurement of the branching fraction of
the decay . We also present the
status of an ongoing analysis aiming to precisely measure the mass
Assessing Child Obesity and Physical Activity in a Hard-to-Reach Population in California's Central Valley, 2012-2013.
IntroductionIn California's agricultural Central Valley, the rate of childhood obesity is higher than the national average. Adequate physical activity contributes to obesity prevention and its assessment is useful to evaluate the impact of interventions.MethodsNiños Sanos, Familia Sana (Healthy Children, Healthy Family [NSFS]) uses community-based participatory research to implement an intervention program to reduce childhood obesity among people of Mexican origin in the Central Valley. Anthropometric measurements were conducted on more than 650 children enrolled in NSFS. Physical activity data from a subgroup of children aged 4 to 7 years (n = 134) were collected via a wearable accelerometer.ResultsChildren were classified on the basis of age and sex-adjusted body mass index as healthy weight (57.7%); overweight (19.3%), or obese (23%). Logistic regression showed that moderate to vigorous physical activity (MVPA) was associated with a child's likelihood of having a healthy BMI (odds ratio: 1.03; 95% CI, 1.01-1.05; P = .017).ConclusionNSFS's community-based participatory approach resulted in successful use of a commercial electronic device to measure physical activity quantity and quality in this hard-to-reach population. Promotion of adequate daily MVPA is an appropriate and necessary component of NSFS's childhood obesity prevention strategy
Like grandparents, like parents: Empirical evidence and psychoanalytic thinking on the transmission of parenting styles
The authors discuss the issue of intergenerational transmission of parenting from an empirical and psychoanalytic perspective. After presenting a framework to explain their conception of parenting, they describe intergenerational transmission of parenting as a key to interpreting and eventually changing parenting behaviors. Then they present (1) the empirical approach aimed at determining if there is actually a stability across generations that contributes to harsh parenting and eventually maltreatment and (2) the psyphoanalytic thinking that seeks to explain the continuity in terms of representations and clinical phenomena. The authors also discuss the relationship between the attachment and the caregiving systems and hypothesize a common base for the two systems in childhood experience. Finally, they propose the psychoanalytic perspective as a fruitful theoretical framework to integrate the evidence for the neurophysiological mediators and moderators of intergenerational transmission. Psychoanalytically informed research can provide clinically relevant insights and hypotheses to be tested
Numerical simulations challenged on the prediction of massive subhalo abundance in galaxy clusters: the case of Abell 2142
In this Letter we compare the abundance of member galaxies of a rich, nearby
() galaxy cluster, Abell 2142, with that of halos of comparable virial
mass extracted from sets of state-of-the-art numerical simulations, both
collisionless at different resolutions and with the inclusion of baryonic
physics in the form of cooling, star formation, and feedback by active galactic
nuclei. We also use two semi-analytical models to account for the presence of
orphan galaxies. The photometric and spectroscopic information, taken from the
Sloan Digital Sky Survey Data Release 12 (SDSS DR12) database, allows us to
estimate the stellar velocity dispersion of member galaxies of Abell 2142. This
quantity is used as proxy for the total mass of secure cluster members and is
properly compared with that of subhalos in simulations. We find that simulated
halos have a statistically significant ( sigma confidence level)
smaller amount of massive (circular velocity above )
subhalos, even before accounting for the possible incompleteness of
observations. These results corroborate the findings from a recent strong
lensing study of the Hubble Frontier Fields galaxy cluster MACS J0416
\citep{grillo2015} and suggest that the observed difference is already present
at the level of dark matter (DM) subhalos and is not solved by introducing
baryonic physics. A deeper understanding of this discrepancy between
observations and simulations will provide valuable insights into the impact of
the physical properties of DM particles and the effect of baryons on the
formation and evolution of cosmological structures.Comment: 8 pages, 2 figures. Modified to match the version published in ApJ
Fossil Groups in the Millennium Simulation. Evolution of the Brightest Galaxies
We create a catalogue of simulated fossil groups and study their properties,
in particular the merging histories of their first-ranked galaxies. We compare
the simulated fossil group properties with those of both simulated non-fossil
and observed fossil groups. Using simulations and a mock galaxy catalogue, we
searched for massive ( 5 10) fossil
groups in the Millennium Simulation Galaxy Catalogue. In addition, attempted to
identify observed fossil groups in the Sloan Digital Sky Survey Data Release 6
using identical selection criteria. Our predictions on the basis of the
simulation data are:(a) fossil groups comprise about 5.5% of the total
population of groups/clusters with masses larger than 5 x 10. This fraction is consistent with the fraction of fossil groups
identified in the SDSS, after all observational biases have been taken into
account; (b) about 88% of the dominant central objects in fossil groups are
elliptical galaxies that have a median R-band absolute magnitude of , which is typical of the observed fossil groups known in the
literature; (c)first-ranked galaxies of systems with 5 x 10, regardless of whether they are either fossil or
non-fossil, are mainly formed by gas-poor mergers; (d) although fossil groups,
in general, assembled most of their virial masses at higher redshifts in
comparison with non-fossil groups, first-ranked galaxies in fossil groups
merged later, i.e. at lower redshifts, compared with their non-fossil-group
counterparts. We therefore expect to observe a number of luminous galaxies in
the centres of fossil groups that show signs of a recent major merger.Comment: 9 pages, 3 figures, accepted for publication in Astronomy &
Astrophysic
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