10,666 research outputs found
Li-rich RGB stars in the Galactic Bulge
We present Lithium abundance determination for a sample of K giant stars in
the galactic bulge. The stars presented here are the only 13 stars with
detectable Lithium line (6767.18 A) among ~400 stars for which we have spectra
in this wavelength range, half of them in Baade's Window (b=-4) and half in a
field at b=-6. The stars were observed with the GIRAFFE spectrograph of
FLAMES@VLT, with a spectral resolution of R~20,000. Abundances were derived via
spectral synthesis and the results are compared with those for stars with
similar parameters, but no detectable Li line. We find 13 stars with a
detectable Li line, among which 2 have abundances A(Li)>2.7. No clear
correlations were found between the Li abundance and those of other elements.
With the exception of the two most Li rich stars, the others follow a fairly
tight A(Li)-T_eff correlation. It would seems that there must be a Li
production phase during the red giant branch (RGB), acting either on a very
short timescale, or selectively only in some stars. The proposed Li production
phase associated with the RGB bump cannot be excluded, although our targets are
significantly brighter than the predicted RGB bump magnitude for a population
at 8 kpcComment: 8 pages, 9 figures, accepted for publication in A&
Early Science with the Large Millimeter Telescope: an energy-driven wind revealed by massive molecular and fast X-ray outflows in the Seyfert Galaxy IRAS 17020+4544
We report on the coexistence of powerful gas outflows observed in millimeter
and X-ray data of the Radio-Loud Narrow Line Seyfert 1 Galaxy IRAS 17020+4544.
Thanks to the large collecting power of the Large Millimeter Telescope, a
prominent line arising from the 12CO(1-0) transition was revealed in recent
observations of this source. The complex profile is composed by a narrow
double-peak line and a broad wing. While the double-peak structure may be
arising in a disk of molecular material, the broad wing is interpreted as the
signature of a massive outflow of molecular gas with an approximate bulk
velocity of -660 km/s. This molecular wind is likely associated to a
multi-component X-ray Ultra-Fast Outflow with velocities reaching up to ~0.1c
and column densities in the range 10^{21-23.9} cm^-2 that was reported in the
source prior to the LMT observations. The momentum load estimated in the two
gas phases indicates that within the observational uncertainties the outflow is
consistent with being propagating through the galaxy and sweeping up the gas
while conserving its energy. This scenario, which has been often postulated as
a viable mechanism of how AGN feedback takes place, has so far been observed
only in ULIRGs sources. IRAS 17020+4544 with bolometric and infrared luminosity
respectively of 5X10^{44} erg/s and 1.05X10^{11} L_sun appears to be an example
of AGN feedback in a NLSy1 Galaxy (a low power AGN). New proprietary
multi-wavelength data recently obtained on this source will allow us to
corroborate the proposed hypothesis.Comment: Accepted for publication on ApJ Letters, 9 pages, 4 figure
The novel adipokine progranulin counteracts IL-1 and TLR4-driven inflammatory response in human and murine chondrocytes via TNFR1
Progranulin (PGRN) is a recently identified adipokine that is supposed to have anti-inflammatory actions. The proinflammatory cytokine interleukin-1β (IL1β) stimulates several mediators of cartilage degradation. Toll like receptor-4 (TLR4) can bind to various damage-associated molecular patterns, leading to inflammatory condition. So far, no data exist of PGRN effects in inflammatory conditions induced by IL1β or lipopolysaccharide (LPS). Here, we investigated the anti-inflammatory potential of PGRN in IL1β-or LPS-induced inflammatory responses of chondrocytes. Human osteoarthritic chondrocytes and ATDC-5 cells were treated with PGRN in presence or not of IL1β or LPS. First, we showed that recombinant PGRN had no effects on cell viability. We present evidence that PGRN expression was increased during the differentiation of ATDC-5 cell line. Moreover, PGRN mRNA and protein expression is increased in cartilage, synovial and infrapatellar fat pad tissue samples from OA patients. PGRN mRNA levels are upregulated under TNFα and IL1β stimulation. Our data showed that PGRN is able to significantly counteract the IL1β-induced expression of NOS2, COX2, MMP13 and VCAM-1. LPS-induced expression of NOS2 is also decreased by PGRN. These effects are mediated, at least in part, through TNFR1. Taken together, our results suggest that PGRN has a clear anti-inflammatory function
Families of superintegrable Hamiltonians constructed from exceptional polynomials
We introduce a family of exactly-solvable two-dimensional Hamiltonians whose
wave functions are given in terms of Laguerre and exceptional Jacobi
polynomials. The Hamiltonians contain purely quantum terms which vanish in the
classical limit leaving only a previously known family of superintegrable
systems. Additional, higher-order integrals of motion are constructed from
ladder operators for the considered orthogonal polynomials proving the quantum
system to be superintegrable
Pollutants make rheumatic diseases worse: Facts on polychlorinated biphenyls (PCBs) exposure and rheumatic diseases
Background Polychlorinated biphenyls (PCBs) are persistent organic pollutants that bioaccumulate in adipose tissue, disturbing its metabolism and the balance of adipokines, related to obesity. The altering secretion pattern of adipokines from the adipose tissue and the increasing mechanical load in weight-bearing joints presented in obesity condition, are risk factors for osteoarthritis development. The most prevalent rheumatic diseases, osteoarthritis and rheumatoid arthritis, are chronic conditions that target the whole joints, leading to increasing disability and health care cost. The goal of this focused review is to summarize the current knowledge on the role of PCBs in osteoarthritis and rheumatoid arthritis pathogenesis. Search strategy A PubMed search was managed using keywords as “rheumatic diseases”, “polychlorinated biphenyls”, “obesity” and “endocrine disruption”. Main results of the review The incidence of rheumatoid arthritis has been reported to be increased especially in urban areas in industrialized countries, emphasizing the importance of environment in the pathogenesis of rheumatic diseases. Analysis of two cohorts exposed to PCBs food contamination showed high incidence of arthritis. In addition, PCBs in serum correlated positively with the prevalence of self-reported arthritis. Few studies support the hypothesis that osteoarthritis development could be related to PCBs induction of chondrocytes apoptosis. Conclusion Evidences have emerged for a relationship between PCBs and development of several types of arthritis. Further research is encouraged to determine the correlation between PCBs exposure and the development of rheumatic diseases
- …