355 research outputs found
The role of dark matter in the galaxy mass-size relationship
The observed relationship between stellar mass and effective radius for early
type galaxies, pointed out by many authors, is interpreted in the context of
Clausius' virial maximum theory. In this view, it is strongly underlined that
the key of the above mentioned correlation is owing to the presence of a deep
link between cosmology and the existence of the galaxy Fundamental Plane. Then
the ultimate meaning is: understanding visible mass - size correlation and/or
Fundamental Plane means understanding how galaxies form. The mass - size
relationship involves baryon (mainly stellar) mass and its typical dimension
related to the light, but it gets memory of the cosmological mass variance at
the equivalence epoch. The reason is that the baryonic component virializes by
sharing virial energy in about equal amount between baryons and dark matter,
this sharing depending, in turn, on the steepness of the dark matter
distribution. The general strategy consists in using the two-component tensor
virial theorem for determining the virialized baryonic configurations. A King
and a Zhao density profile are assumed for the inner baryonic and the outer
dark matter component, respectively, at the end of the relaxation phase. All
the considerations are restricted to spherical symmetry for simplicity. The
effect of changing the dark-to-baryon mass ratio, m, is investigated inside a
LambdaCDM scenario. A theoretical mass - size relation is expressed for the
baryonic component, which fits fairly well to the data from a recently studied
galaxy sample. Finally, the play of intrinsic dispersion on the mass ratio, m,
is discussed in the light of the cusp/core problem and some consequences are
speculated about the existence of a limit, m_l, expected by the theory.Comment: 36 pages, 8 figures (Accepted for publication in New Astronomy
On the tilt of Fundamental Plane by Clausius' virial maximum theory
The theory of the Clausius' virial maximum to explain the Fundamental Plane
(FP) proposed by Secco (2000, 2001,2005) is based on the existence of a maximum
in the Clausius' Virial (CV) potential energy of a early type galaxy (ETG)
stellar component when it is completely embedded inside a dark matter (DM)
halo. At the first order approximation the theory was developed by modeling the
two-components with two cored power-law density profiles. An higher level of
approximation is now taken into account by developing the same theory when the
stellar component is modeled by a King-model with a cut-off. Even if the DM
halo density remains a cored power law the inner component is now more
realistic for the ETGs. The new formulation allows us to understand more deeply
what is the dynamical reason of the FP tilt and in general how the CV theory
may really be the engine to produce the FP main features. The degeneracy of FP
in respect to the initial density perturbation spectrum may be now full
understood in a CDM cosmological scenario. A possible way to compare the FPs
predicted by the theory with those obtained by observations is also
exemplified.Comment: 35 pages, 8 figure
Vitamin D and rheumatic diseases.
Vitamin D has some well-known effects on calcium, phosphate and bone metabolism, but it has recently shown to have many other effects, which may potentially be relevant to patients with extra-skeletal rheumatic diseases. Such effects may be justified by: 1) the presence of the vitamin D receptors also on extra-osseous cells, such as cartilage cells, sinoviocytes, muscle cells; 2) the proven role of vitamin D in the control of the transcription of genes involved in rheumatic diseases; 3) the evidence that vitamin D has multiple endocrine effects not only on calcium homeostasis; 4) the activation of vitamin D not only in the kidneys, but also in monocyte-macrophage and lymphocytic cell lines and in some epithelial cells with additional intracrine and paracrine effects. Vitamin D deficiency has been reported in numerous metabolic, degenerative, inflammatory and autoimmune rheumatic diseases. In some cases this association was also related to the risk of developing a rheumatic disease or the degree of disease activity. However there is no conclusive evidence of the efficacy of a preventive or therapeutic strategy based on vitamin D supplementation in extra-skeletal rheumatic diseases. This review aims to provide an overview of the latest evidence concerning the relationship between vitamin D and the most relevant rheumatic diseases
Role of air pollutants mediated oxidative stress in respiratory diseases
Airborne particulate (PM) components from fossil fuel combustion can induce oxidative stress initiated by reactive oxygen species (ROS) that are strongly correlated with airway inflammation and asthma. A valid biomarker of airway inflammation is fractionated exhaled nitric oxide (FENO). The oxidative potential of PM2.5 can be evaluated with the dithiothreitol (DTT) dosage, which represents both ROS chemically produced and intracellular ROS of macrophages. This correlates with quality indicators of the internal environment and ventilation strategies such as dilution and removal of airborne contaminants
Toward Understanding the origin of the Fundamental Plane for Early-Type Galaxies
We present a panoramic review of several observational and theoretical
aspects of the modern astrophysical research about the origin of the
Fundamental Plane (FP) relation for Early-Type Galaxies (ETGs). The discussion
is focused on the problem of the tilt and the tightness of the FP, and on the
attempts to derive the luminosity evolution of ETGs with redshift. Finally, a
number of observed features in the FP are interpreted from the standpoint of a
new theoretical approach based on the two-component tensor virial theorem.Comment: 30 pages, 3 figure
Is it possible to make a diagnosis of raw, heated and baked egg allergy in children using cut-offs? A systematic review
The diagnosis of IgE-mediated egg allergy lies both on a compatible clinical history and on the results of skin prick tests (SPTs) and IgEs levels. Both tests have good sensitivity but low specificity. For this reason, oral food challenge (OFC) is the ultimate gold standard for the diagnosis. The aim of the present paper is to systematically review the literature in order to identify, analyze and synthesize the predictive value of SPT and specific IgEs both to egg white and main egg allergens and to review the cut-offs suggested in the literature
Oxygen abundance in local disk and bulge: chemical evolution with a strictly universal IMF
The empirical differential oxygen abundance distribution (EDOD) is deduced
from subsamples related to two different samples involving solar neighbourhood
(SN) thick disk, thin disk, halo, and bulge stars. The EDOD of the SN thick +
thin disk is determined by weighting the mass, for assumed SN thick to thin
disk mass ratio within the range, 0.1-0.9. Inhomogeneous models of chemical
evolution for the SN thick disk, the SN thin disk, the SN thick + thin disk,
the SN halo, and the bulge, are computed assuming the instantaneous recycling
approximation. The EDOD data are fitted, to an acceptable extent, by their TDOD
counterparts provided (i) still undetected, low-oxygen abundance thin disk
stars exist, and (ii) a single oxygen overabundant star is removed from a thin
disk subsample. In any case, the (assumed power-law) stellar initial mass
function (IMF) is universal but gas can be inhibited from, or enhanced in,
forming stars at different rates with respect to a selected reference case.
Models involving a strictly universal IMF (i.e. gas neither inhibited from, nor
enhanced in, forming stars with respect to a selected reference case) can also
reproduce the data. The existence of a strictly universal IMF makes similar
chemical enrichment within active (i.e. undergoing star formation) regions
placed in different environments, but increasing probability of a region being
active passing from SN halo to SN thick + thin disk, SN thin disk, SN thick
disk, and bulge. On the basis of the results, it is realized that the chemical
evolution of the SN thick + thin disk as a whole cannot be excluded.Comment: 26 pages, 10 tables, and 5 figures; tables out of page are splitted
in two parts in Appendix B; sects.4 and 5 rewritten for better understanding
of the results; further references added. Accepted for publication in
Astrophysics & Space Scienc
Adherence to recommendations for cervical and breast cancer screening in systemic sclerosis.
The aim of the study was to evaluate the adherence of systemic sclerosis (SSc) female patients to cervix and breast cancer screening procedures, as suggested by local guidelines. A cohort of 84 SSc women was asked if they had undergone mammography and Pap test during the previous 2- and 3-year intervals, as indicated according to the Italian recommendations. The results were compared with those collected in patients affected by other chronic rheumatic disorders and in the general population. More than 85% of SSc women declared to comply with an age-related cervix and breast cancer screening schedule. The data were similar to those collected in patients affected by other chronic rheumatic disorders, whereas the subjects belonging to the general population reported to undergo breast cancer screening more frequently. Among SSc women, neither the educational level, nor the lung and skin involvement influenced their cancer screening program compliance. Only a positive history of ischemic digital ulcers seemed to interfere with mammography. Our study reported a very high percentage of SSc female patients who adhered to programs for the early detection of cervical and breast cancer. The significant adherence to guidelines may be due to the schedule adopted by the local health public service, which regularly invites eligible subjects by mail to undergo cancer screening at no charge
Vitamin D and ω-3 Supplementations in Mediterranean Diet During the 1st Year of Overt Type 1 Diabetes: A Cohort Study
Vitamin D and omega 3 fatty acid (\u3c9-3) co-supplementation potentially improves type 1 diabetes (T1D) by attenuating autoimmunity and counteracting inflammation. This cohort study, preliminary to a randomized control trial (RCT), is aimed at evaluating, in a series of T1D children assuming Mediterranean diet and an intake of cholecalciferol of 1000U/day from T1D onset, if \u3c9-3 co-supplementation preserves the residual endogen insulin secretion (REIS). Therefore, the cohort of 22 \u201cnew onsets\u201d of 2017 received \u3c9-3 (eicosapentenoic acid (EPA) plus docosahexaenoic acid (DHA), 60 mg/kg/day), and were compared retrospectively vs. the 37 \u201cprevious onsets\u201d without \u3c9-3 supplementation. Glicosilated hemoglobin (HbA1c%), the daily insulin demand (IU/Kg/day) and IDAA1c, a composite index (calculated as IU/Kg/day
7 4 + HbA1c%), as surrogates of REIS, were evaluated at recruitment (T0) and 12 months later (T12). In the \u3c9-3 supplemented group, dietary intakes were evaluated at T0 and T12. As an outcome, a decreased insulin demand (p < 0.01), particularly as pre-meal boluses (p < 0.01), and IDAA1c (p < 0.05), were found in the \u3c9-3 supplemented group, while HbA1c% was not significantly different. Diet analysis in the \u3c9-3 supplemented group, at T12 vs. T0, highlighted that the intake of arachidonic acid (AA) decreased (p < 0.01). At T0, the AA intake was inversely correlated with HbA1c% (p < 0.05; r;. 0.411). In conclusion, the results suggest that vitamin D plus \u3c9-3 co-supplementation as well as AA reduction in the Mediterranean diet display benefits for T1D children at onset and deserve further investigation
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