264 research outputs found
MHD turbulence-Star Formation Connection: from pc to kpc scales
The transport of magnetic flux to outside of collapsing molecular clouds is a
required step to allow the formation of stars. Although ambipolar diffusion is
often regarded as a key mechanism for that, it has been recently argued that it
may not be efficient enough. In this review, we discuss the role that MHD
turbulence plays in the transport of magnetic flux in star forming flows. In
particular, based on recent advances in the theory of fast magnetic
reconnection in turbulent flows, we will show results of three-dimensional
numerical simulations that indicate that the diffusion of magnetic field
induced by turbulent reconnection can be a very efficient mechanism, especially
in the early stages of cloud collapse and star formation. To conclude, we will
also briefly discuss the turbulence-star formation connection and feedback in
different astrophysical environments: from galactic to cluster of galaxy
scales.Comment: 6 pages, 5 figures, 274 IAU Symposium: Advances in Plasma
Astrophysic
Laboratory diagnosis of Streptococcus pneumoniae infections: past and future
Streptococcus pneumoniae is one of the most important causative agent of pneumonia, meningitis, bacteremia, sinusitis and otitis media. The gold standard diagnostic method is still culture evenif bacteriological diagnosis is making progress in molecular biol- ogy and in proteomics areas.
The full article is free available on www.jpmh.or
Bacterial lysate in the prevention of acute exacerbation of COPD and in respiratory recurrent infections
Respiratory tract infections (RTIs) represent a serious problem because they are one of the most common cause of human death by infection. The search for the treatment of those diseases has therefore a great importance. In this study we provide an overview of the currently available treatments for RTIs with particular attention to chronic obstructive pulmonary diseases exacerbations and recurrent respiratory infections therapy and a description of bacterial lysate action, in particular making reference to the medical literature dealing with its clinical efficacy. Those studies are based on a very large number of clinical trials aimed to evaluate the effects of this drug in maintaining the immune system in a state of alert, and in increasing the defences against microbial infections. From this analysis it comes out that bacterial lysates have a protective effect, which induce a significant reduction of the symptoms related to respiratory infections. Those results could be very interesting also from an economic point of view, because they envisage a reduction in the number of acute exacerbations and a shorter duration of hospitalization. The use of bacterial lysate could therefore represent an important means to achieve an extension of life duration in patients affected by respiratory diseases
Local Star formation triggered by SN shocks in magnetized diffuse neutral clouds
In this work, considering the impact of a SNR with a neutral magnetized cloud
we derived analytically a set of conditions which are favorable for driving
gravitational instability in the cloud and thus star formation. We have built
diagrams of the SNR radius, versus the cloud density, that constrain a domain
in the parameter space where star formation is allowed. The diagrams are also
tested with fully 3-D MHD simulations involving a SNR and a self-gravitating
cloud and we find that the numerical analysis is consistent with the results
predicted by the diagrams. While the inclusion of a homogeneous magnetic field
approximately perpendicular to the impact velocity of the SNR with an intensity
~1 G results only a small shrinking of the star formation triggering zone
in the diagrams, a larger magnetic field (~10 G) causes a significant
shrinking, as expected. Applications of the diagrams to a few regions of our
own galaxy have revealed that star formation in those sites could have been
triggered by shock waves from SNRs. Finally, we have evaluated the effective
star formation efficiency for this sort of interaction and found that it is
smaller than the observed values in our own Galaxy (sfe ~0.01-0.3). This result
is consistent with previous work in the literature and also suggests that the
mechanism presently investigated, though very powerful to drive structure
formation, supersonic turbulence and eventually, local star formation, does not
seem to be sufficient to drive global star formation in normal star forming
galaxies, not even when the magnetic field in the neutral clouds is neglected.
(abridged)Comment: 19 pages, 13 figures, accepted for pubblication in MNRA
Super stellar clusters with a bimodal hydrodynamic solution: an Approximate Analytic Approach
We look for a simple analytic model to distinguish between stellar clusters
undergoing a bimodal hydrodynamic solution from those able to drive only a
stationary wind. Clusters in the bimodal regime undergo strong radiative
cooling within their densest inner regions, which results in the accumulation
of the matter injected by supernovae and stellar winds and eventually in the
formation of further stellar generations, while their outer regions sustain a
stationary wind. The analytic formulae are derived from the basic hydrodynamic
equations. Our main assumption, that the density at the star cluster surface
scales almost linearly with that at the stagnation radius, is based on results
from semi-analytic and full numerical calculations. The analytic formulation
allows for the determination of the threshold mechanical luminosity that
separates clusters evolving in either of the two solutions. It is possible to
fix the stagnation radius by simple analytic expressions and thus to determine
the fractions of the deposited matter that clusters evolving in the bimodal
regime blow out as a wind or recycle into further stellar generations.Comment: 5 pages, 4 figures, accepted by A&
A multiwavelength study of the star forming region IRAS 18544+0112
This work aims at investigating the molecular and infrared components in the
massive young stellar object (MYSO) candidate IRAS 18544+0112. The purpose is
to determine the nature and the origin of this infrared source. To analyze the
molecular gas towards IRAS 18544+0112, we have carried out observations in a
90" x 90" region around l = 34.69, b = -0.65, using the Atacama Submillimeter
Telescope Experiment (ASTE) in the 12CO J=3-2, 13CO J=3-2, HCO+ J=4-3 and CS
J=7-6 lines with an angular resolution of 22". The infrared emission in the
area has been analyzed using 2MASS and Spitzer public data. From the molecular
analysis, we find self-absorbed 12CO J=3-2 profiles, which are typical in star
forming regions, but we do not find any evidence of outflow activity. Moreover,
we do not detect either HCO+ J=4-3 or CS J=7-6 in the region, which are species
normally enhanced in molecular outflows and high density envelopes. The 12CO
J=3-2 emission profile suggests the presence of expanding gas in the region.
The Spitzer images reveal that the infrared source has a conspicuous extended
emission bright at 8 um with an evident shell-like morphology of ~ 1.5 arcmin
in size (~ 1.4 pc at the proposed distance of 3 kpc) that encircles the 24 um
emission. The non-detection of ionized gas related to IRAS 18544+0112, together
with the fact that it is still embedded in a molecular clump suggest that IRAS
18544+0112, has not reached the UCHII region stage yet. Based on near infrared
photometry we search for YSO candidates in the region and propos that 2MASS
18565878+0116233 is the infrared point source associated with IRAS 18544+0112.
Finally, we suggest that the expansion of a larger nearby HII region,
G034.8-0.7, might be related to the formation of IRAS 18544+0112.Comment: 14 pages, accepted for publication in A&A. Figures degraded to reduce
file siz
Immunotherapy of lung cancer: An update
In Germany lung cancer is the leading cause of cancer-associated death in men. Surgery, chemotherapy and radiation may enhance survival of patients suffering from lung cancer but the enhancement is typically transient and mostly absent with advanced disease; eventually more than 90% of lung cancer patients will die of disease. New approaches to the treatment of lung cancer are urgently needed. Immunotherapy may represent one new approach with low toxicity and high specificity but implementation has been a challenge because of the poor antigenic characterization of these tumors and their ability to escape immune responses. Several different immunotherapeutic treatment strategies have been developed. This review examines the current state of development and recent advances with respect to non-specific immune stimulation, cellular immunotherapy ( specific and non-specific), therapeutic cancer vaccines and gene therapy for lung cancer. The focus is primarily placed on immunotherapeutic cancer treatments that are already in clinical trial or well progressed in preclinical studies. Although there seems to be a promising future for immunotherapy in lung cancer, presently there is not standard immunotherapy available for clinical routine
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