4,152 research outputs found
Structure and kinematics of the peculiar galaxy NGC 128
This is a multiband photometric and spectroscopic study of the peculiar S0
galaxy NGC128. We present results from broad (B and R) and narrow band optical
CCD photometry, near (NIR) and far (FIR) infrared observations, long slit
spectroscopy, and Fabry-Perot interferometry (CIGALE). The peculiar peanut
shape morphology of the galaxy is observed both at optical and near-infrared
wavelengths. The stellar disk is thick and distorted (arc-bended), with a color
asymmetry along the major axis due to the presence of a large amount of dust,
estimated through NIR and FIR data of ~6x10^6 M_sun, in the region of
interaction with the companion galaxy NGC127. The color maps are nearly uniform
over the whole galaxy, but for the major axis asymmetry, and a small gradient
toward the center indicating the presence of a redder disk-like component. The
H_alpha image indeed reveals the existence of a tilted gaseous ``disk'' around
the center, oriented with the major axis toward the companion galaxy NGC127.
Long slit and CIGALE data confirm the presence of gas in a disk-like component
counter-rotating and inclined approximately of 50 deg. to the line of sight.
The mass of the gas disk in the inner region is ~2.7x10^4 M_sun. The stellar
velocity field is cylindrical up to the last measured points of the derived
rotation curves, while the velocity dispersion profiles are typical for an S0
galaxy, but for an extended constant behaviour along the minor axis.Comment: accepted for pubblication in A&A Supp
Bimodality in low-luminosity E and S0 galaxies
Stellar population characteristics are presented for a sample of low-luminosity early-type galaxies (LLEs) in order to compare them with their more luminous counterparts. Long-slit spectra of a sample of 10 LLEs were taken with the ESO New Technology Telescope, selected for their low luminosities. Line strengths were measured on the Lick standard system. Lick indices for these LLEs were correlated with velocity dispersion (Ï), alongside published data for a variety of Hubble types. The LLEs were found to fall below an extrapolation of the correlation for luminous ellipticals and were consistent with the locations of spiral bulges in plots of line strengths versus Ï. Luminosity weighted average ages, metallicities and abundance ratios were estimated from Ï2 fitting of 19 Lick indices to predictions from simple stellar population models. The LLEs appear younger than luminous ellipticals and of comparable ages to spiral bulges. These LLEs show a bimodal metallicity distribution, consisting of a low-metallicity group (possibly misclassified dwarf spheroidal galaxies) and a high-metallicity group (similar to spiral bulges). Finally, they have low α-element to iron peak abundance ratios indicative of slow, extended star formation
CyPLOS: a new family of synthetic ionophores
The ion transport properties of a new family of synthetic ionophores based on cyclic phosphate-linked oligosaccharide (CyPLOS) macrocycles are described
Tropical climateâvegetationâfire relationships: multivariate evaluation of the land surface model JSBACH
The interactions between climate, vegetation and fire can strongly influence
the future trajectories of vegetation in Earth system models. We evaluate the
relationships between tropical climate, vegetation and fire in the global
vegetation model JSBACH, using a simple fire scheme and the complex fire
model SPITFIRE with the aim to identify potential for model improvement. We
use two remote-sensing products (based on MODIS and Landsat) in different
resolutions to assess the robustness of the obtained observed relationships.
We evaluate the model using a multivariate comparison that allows us to focus
on the interactions between climate, vegetation and fire and test the
influence of land use change on the modelled patterns.
Climateâvegetationâfire relationships are known to differ between
continents; we therefore perform the analysis for each continent separately.The observed relationships are
similar in the two satellite data sets, but maximum tree cover is reached at
higher precipitation values for coarser resolution. This shows that the
spatial scale of models and data needs to be consistent for meaningful
comparisons. The model captures the broad spatial patterns with regional
differences, which are partly due to the climate forcing derived from an
Earth system model. Compared to the simple fire scheme, SPITFIRE strongly
improves the spatial pattern of burned area and the distribution of burned
area along increasing precipitation. The correlation between precipitation
and tree cover is higher in the observations than in the largely climate-driven vegetation model, with both fire models. The multivariate comparison
identifies excessive tree cover in low-precipitation areas and a too-strong relationship between high fire occurrence and low tree cover for the
complex fire model. We therefore suggest that drought effects on tree cover
and the impact of burned area on tree cover or the adaptation of trees to
fire can be improved.The observed variation in the relationship between precipitation and maximum
tree cover between continents is higher than the simulated one. Land use
contributes to the intercontinental differences in fire regimes with SPITFIRE
and strongly overprints the modelled multimodality of tree cover with
SPITFIRE.The multivariate modelâdata comparison used here has several
advantages: it improves the attribution of modelâdata mismatches to model
processes, it reduces the impact of biases in the meteorological forcing on
the evaluation and it allows us to evaluate not only a specific target variable
but also the interactions.</p
Scaling relations of cluster elliptical galaxies at z~1.3. Distinguishing luminosity and structural evolution
[Abridged] We studied the size-surface brightness and the size-mass relations
of a sample of 16 cluster elliptical galaxies in the mass range
10^{10}-2x10^{11} M_sun which were morphologically selected in the cluster RDCS
J0848+4453 at z=1.27. Our aim is to assess whether they have completed their
mass growth at their redshift or significant mass and/or size growth can or
must take place until z=0 in order to understand whether elliptical galaxies of
clusters follow the observed size evolution of passive galaxies. To compare our
data with the local universe we considered the Kormendy relation derived from
the early-type galaxies of a local Coma Cluster reference sample and the WINGS
survey sample. The comparison with the local Kormendy relation shows that the
luminosity evolution due to the aging of the stellar content already assembled
at z=1.27 brings them on the local relation. Moreover, this stellar content
places them on the size-mass relation of the local cluster ellipticals. These
results imply that for a given mass, the stellar mass at z~1.3 is distributed
within these ellipticals according to the same stellar mass profile of local
ellipticals. We find that a pure size evolution, even mild, is ruled out for
our galaxies since it would lead them away from both the Kormendy and the
size-mass relation. If an evolution of the effective radius takes place, this
must be compensated by an increase in the luminosity, hence of the stellar mass
of the galaxies, to keep them on the local relations. We show that to follow
the Kormendy relation, the stellar mass must increase as the effective radius.
However, this mass growth is not sufficient to keep the galaxies on the
size-mass relation for the same variation in effective radius. Thus, if we want
to preserve the Kormendy relation, we fail to satisfy the size-mass relation
and vice versa.Comment: Accepted for publication in A&A, updated to match final journal
versio
Evidence of disorientation towards immunization on online social media after contrasting political communication on vaccines. Results from an analysis of Twitter data in Italy
Background In Italy, in recent years, vaccination coverage for key immunizations as MMR has been declining to worryingly low levels, with large measles outbreaks. As a response in 2017, the Italian government expanded the number of mandatory immunizations introducing penalties to unvaccinated childrenâs families. During the 2018 general elections campaign, immunization policy entered the political debate with the government in-charge blaming oppositions for fuelling vaccine scepticism. A new government (formerly in the opposition) established in 2018 temporarily relaxed penalties and announced the introduction of forms of flexibility. Objectives and methods First, we supplied a definition of disorientation, as the âlack of well-established and resilient opinions among individuals, therefore causing them to change their positions as a consequence of sufficient external perturbationsâ. Second, procedures for testing for the presence of both short and longer-term collective disorientation in Twitter signals were proposed. Third, a sentiment analysis on tweets posted in Italian during 2018 on immunization topics, and related polarity evaluations, were used to investigate whether the contrasting announcements at the highest political level might have originated disorientation amongst the Italian public. Results Vaccine-relevant tweetersâ interactions peaked in response to main political events. Out of retained tweets, 70.0% resulted favourable to vaccination, 16.4% unfavourable, and 13.6% undecided, respectively. The smoothed time series of polarity proportions exhibit frequent large changes in the favourable proportion, superimposed to a clear up-and-down trend synchronized with the switch between governments in Spring 2018, suggesting evidence of disorientation among the public. Conclusions The reported evidence of disorientation for opinions expressed in online social media shows that critical health topics, such as vaccination, should never be used to achieve political consensus. This is worsened by the lack of a strong Italian institutional presence on Twitter, calling for efforts to contrast misinformation and the ensuing spread of hesitancy. It remains to be seen how this disorientation will impact future parentsâ vaccination decisions
Demise of the Planktic Foraminifer genus Morozovella during the Early Eocene Climatic Optimum: new records from ODP Site 1258 (Demerara Rise, western equatorial Atlantic) and Site 1263 (Walvis Ridge, South Atlantic)
Here we present relative abundances of planktic foraminifera that span the Early Eocene Climatic Optimum (EECO) at Ocean Drilling Program (ODP) Site 1258 in the western equatorial Atlantic. The EECO (~53.3â49.1 Ma) represents peak Cenozoic warmth, probably related to high atmospheric CO2, and when planktic foraminifera, a dominant component of marine sediment, exhibit a major biotic response. Consistent with previous work, the relative abundance of the genus Morozovella, which dominated early Paleogene tropical-subtropical assemblages, markedly and permanently declined from a mean percentage of ~32% to less than ~7% at the beginning of the EECO. The distinct decrease in Morozovella abundance occurred at Site 1258 within ~20 kyr before a negative excursion in ÎŽ13C records known as the J event and which defines the beginning of EECO. Moreover, all morozovellid species except M. aragonensis dropped in abundance permanently at Site 1258, and this is related to a reduction in test-size. Comparing our data with that from other locations, the remarkable switch in planktonic foraminifera assemblages appears to have begun first with unfavourable environmental conditions near the Equator and then extended to higher latitudes. Several potential stressors may explain observations, including some combination of algal photosymbiont inhibition (bleaching), a sustained increase in temperature, or an extended decrease in pH
Angiogenesis and vessel co-option in a mathematical model of diffusive tumor growth: The role of chemotaxis
This work considers the propagation of a tumor from the stage of a small avascular sphere in a host tissue and the progressive onset of a tumor neovasculature stimulated by a pro-angiogenic factor secreted by hypoxic cells. The way new vessels are formed involves cell sprouting from pre-existing vessels and following a trail via a chemotactic mechanism (CM). Namely, it is first proposed a detailed general family of models of the CM, based on a statistical mechanics approach. The key hypothesis is that the CM is composed by two components: i) the wellâknown bias induced by the angiogenic factor gradient; ii) the presence of stochastic changes of the velocity direction, thus giving rise to a diffusive component. Then, some further assumptions and simplifications are applied in order to derive a specific model to be used in the simulations. The tumor progression is favored by its acidic aggression towards the healthy cells. The model includes the evolution of many biological and chemical species. Numerical simulations show the onset of a traveling wave eventually replacing the host tissue with a fully vascularized tumor. The results of simulations agree with experimental measures of the vasculature density in tumors, even in the case of particularly hypoxic tumors
Major axis kinematics of 15 early-type galaxies in the Fornax cluster
Major axis rotation curves and velocity dispersions profiles, extending out
to about one effective radius, are presented for 15 ellipticals and S0's out of
the photometric sample of Fornax cluster galaxies studied by Caon \etal\
(1994). A brief description of the spectroscopic and photometric
characteristics of each galaxy is provided, together with a comparison with
previous studies. Six of the nine E's are possibly misclassified S0's or
ellipticals harboring a disk-like component. Two galaxies (NGC~1399 and 1404)
show a hint of counter-rotation. Evidence is given that the \bright\ and the
\ordinary\ families of early-type galaxies, first introduced by Capaccioli
\etal\ (1992), look distinct also in term of the anisotropy parameter
(\Vm/\sigma)^*.Comment: 33 pages with figures, uuencoded compressed postscrip
Long-Term Outcomes Associated with Traumatic Brain Injury in Childhood and Adolescence: A Nationwide Swedish Cohort Study of a Wide Range of Medical and Social Outcomes
BACKGROUND: Traumatic brain injury (TBI) is the leading cause of disability and mortality in children and young adults worldwide. It remains unclear, however, how TBI in childhood and adolescence is associated with adult mortality, psychiatric morbidity, and social outcomes. METHODS AND FINDINGS: In a Swedish birth cohort between 1973 and 1985 of 1,143,470 individuals, we identified all those who had sustained at least one TBI (n = 104,290 or 9.1%) up to age 25 y and their unaffected siblings (n = 68,268) using patient registers. We subsequently assessed these individuals for the following outcomes using multiple national registries: disability pension, specialist diagnoses of psychiatric disorders and psychiatric inpatient hospitalisation, premature mortality (before age 41 y), low educational attainment (not having achieved secondary school qualifications), and receiving means-tested welfare benefits. We used logistic and Cox regression models to quantify the association between TBI and specified adverse outcomes on the individual level. We further estimated population attributable fractions (PAF) for each outcome measure. We also compared differentially exposed siblings to account for unobserved genetic and environmental confounding. In addition to relative risk estimates, we examined absolute risks by calculating prevalence and Kaplan-Meier estimates. In complementary analyses, we tested whether the findings were moderated by injury severity, recurrence, and age at first injury (ages 0-4, 5-9, 6-10, 15-19, and 20-24 y). TBI exposure was associated with elevated risks of impaired adult functioning across all outcome measures. After a median follow-up period of 8 y from age 26 y, we found that TBI contributed to absolute risks of over 10% for specialist diagnoses of psychiatric disorders and low educational attainment, approximately 5% for disability pension, and 2% for premature mortality. The highest relative risks, adjusted for sex, birth year, and birth order, were found for psychiatric inpatient hospitalisation (adjusted relative risk [aRR] = 2.0; 95% CI: 1.9-2.0; 6,632 versus 37,095 events), disability pension (aRR = 1.8; 95% CI: 1.7-1.8; 4,691 versus 29,778 events), and premature mortality (aRR = 1.7; 95% CI: 1.6-1.9; 799 versus 4,695 events). These risks were only marginally attenuated when the comparisons were made with their unaffected siblings, which implies that the effects of TBI were consistent with a causal inference. A dose-response relationship was observed with injury severity. Injury recurrence was also associated with higher risks-in particular, for disability pension we found that recurrent TBI was associated with a 3-fold risk increase (aRR = 2.6; 95% CI: 2.4-2.8) compared to a single-episode TBI. Higher risks for all outcomes were observed for those who had sustained their first injury at an older age (ages 20-24 y) with more than 25% increase in relative risk across all outcomes compared to the youngest age group (ages 0-4 y). On the population level, TBI explained between 2%-6% of the variance in the examined outcomes. Using hospital data underestimates milder forms of TBI, but such misclassification bias suggests that the reported estimates are likely conservative. The sibling-comparison design accounts for unmeasured familial confounders shared by siblings, including half of their genes. Thus, residual genetic confounding remains a possibility but will unlikely alter our main findings, as associations were only marginally attenuated within families. CONCLUSIONS: Given our findings, which indicate potentially causal effects between TBI exposure in childhood and later impairments across a range of health and social outcomes, age-sensitive clinical guidelines should be considered and preventive strategies should be targeted at children and adolescents
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