359 research outputs found
X Her and TX Psc: Two cases of ISM interaction with stellar winds observed by Herschel
The asymptotic giant branch (AGB) stars X Her and TX Psc have been imaged at
70 and 160 microns with the PACS instrument onboard the Herschel satellite, as
part of the large MESS (Mass loss of Evolved StarS) Guaranteed Time Key
Program. The images reveal an axisymmetric extended structure with its axis
oriented along the space motion of the stars. This extended structure is very
likely to be shaped by the interaction of the wind ejected by the AGB star with
the surrounding interstellar medium (ISM). As predicted by numerical
simulations, the detailed structure of the wind-ISM interface depends upon the
relative velocity between star+wind and the ISM, which is large for these two
stars (108 and 55 km/s for X Her and TX Psc, respectively). In both cases,
there is a compact blob upstream whose origin is not fully elucidated, but that
could be the signature of some instability in the wind-ISM shock. Deconvolved
images of X Her and TX Psc reveal several discrete structures along the
outermost filaments, which could be Kelvin-Helmholtz vortices. Finally, TX Psc
is surrounded by an almost circular ring (the signature of the termination
shock?) that contrasts with the outer, more structured filaments. A similar
inner circular structure seems to be present in X Her as well, albeit less
clearly.Comment: 11 pages, Astronomy & Astrophysics, in pres
The detached dust shells of AQ And, U Ant, and TT Cyg
Detached circumstellar dust shells are detected around three carbon variables
using Herschel-PACS. Two of them are already known on the basis of their
thermal CO emission and two are visible as extensions in IRAS imaging data. By
model fits to the new data sets, physical sizes, expansion timescales, dust
temperatures, and more are deduced. A comparison with existing molecular CO
material shows a high degree of correlation for TT Cyg and U Ant but a few
distinct differences with other observables are also found.Comment: Letter accepted for publication on the A&A Herschel Special Issu
First detection of CO lines in a water fountain star
[Context] Water fountain stars are very young post-AGB stars with high
velocity water maser jets. They are the best objects to study the onset of
bipolar jets from evolved stars due to their young dynamical ages. [Methods] We
use the Arizona Radio Observatory 10m telescope to observe the CO J=2-1 line
and compare the line parameters with that of masers. [Results] We report the
detection of 12CO and 13COJ=2-1 lines from IRAS 16342-3814. The inferred 12CO
mass loss rate is an order of magnitude lower than the infrared and OH mass
loss rates, indicating a very cold and thick O-rich circumstellar envelope
around the star. We also find a 12CO expansion velocity of Vexp = 46 +- 1 km/s
that is too high for an AGB wind and confirm the systemic velocity of 44 +- 1
km/s. In addition we measure a very low 12CO/13CO line ratio of 1.7.
[Conclusions] The first detection of CO lines has provided a new way to
investigate the water fountain stars. Given the high expansion velocity of the
CO gas and its relation to maser velocities, we infer that the CO emission
region is co-located with the OH mainline masers in the warm base of the
optical bipolar lobes, while the high velocity OH1612MHz and H2O masers are
located in the side walls and at the farthest ends of the bipolar lobes,
respectively. Further observations are highly desired to understand the very
low 12CO/13CO line ratio.Comment: 5 pages, 1 figure, accepted by A&A Lette
Dosimetric evaluation of Acuros XB Advanced Dose Calculation algorithm in heterogeneous media
<p>Abstract</p> <p>Background</p> <p>A study was realised to evaluate and determine relative figures of merit of a new algorithm for photon dose calculation when applied to inhomogeneous media.</p> <p>Methods</p> <p>The new Acuros XB algorithm implemented in the Varian Eclipse treatment planning system was compared against a Monte Carlo method (VMC++), and the Analytical Anisotropic Algorithm (AAA). The study was carried out in virtual phantoms characterized by simple geometrical structures. An insert of different material and density was included in a phantom built of skeletal-muscle and HU = 0 (setting "A"): Normal Lung (lung, 0.198 g/cm<sup>3</sup>); Light Lung (lung, 0.035 g/cm<sup>3</sup>); Bone (bone, 1.798 g/cm<sup>3</sup>); another phantom (setting "B") was built of adipose material and including thin layers of bone (1.85 g/cm<sup>3</sup>), adipose (0.92 g/cm<sup>3</sup>), cartilage (1.4745 g/cm<sup>3</sup>), air (0.0012 g/cm<sup>3</sup>). Investigations were performed for 6 and 15 MV photon beams, and for a large (13 × 13 cm<sup>2</sup>) and a small (2.8 × 13 cm<sup>2</sup>) field.</p> <p>Results</p> <p>Results are provided in terms of depth dose curves, transverse profiles and Gamma analysis (3 mm/3% and 2 mm/2% distance to agreement/dose difference criteria) in planes parallel to the beam central axis; Monte Carlo simulations were assumed as reference. Acuros XB gave an average gamma agreement, with a 3 mm/3% criteria, of 100%, 86% and 100% for Normal Lung, Light Lung and Bone settings, respectively, and dose to medium calculations. The same figures were 86%, 11% and 100% for AAA, where only dose rescaled to water calculations are possible.</p> <p>Conclusions</p> <p>In conclusion, Acuros XB algorithm provides a valid and accurate alternative to Monte Carlo calculations for heterogeneity management.</p
Incidence and diversity of the fungal genera Aspergillus and Penicillium in Portuguese almonds and chestnuts
Almonds (Prunus dulcis (Miller) D.A. Webb) and European (sweet) chestnuts (Castanea sativa Miller) are of great economic and social impact in Mediterranean countries, and in some areas they constitute the main income of rural populations. Despite all efforts to control fungal contamination, toxigenic fungi are ubiquitous in nature and occur regularly in worldwide food supplies, and these nuts are no exception. This work aimed to provide knowledge on the general mycobiota of Portuguese almonds and chestnuts, and its evolution from field to the end of storage. For this matter, 45 field chestnut samples and 36 almond samples (30 field samples and six storage samples) were collected in Trás-os-Montes, Portugal. All fungi belonging to genus Aspergillus were isolated and identified to the section level. Fungi representative of other genera were identified to the genus level. In the field, chestnuts were mainly contaminated with the genera Fusarium, Cladosporium, Alternaria and Penicillium, and the genus Aspergillus was only rarely found, whereas almonds were more contaminated with Aspergillus. In almonds, Aspergillus incidence increased significantly from field to the end of storage, but diversity decreased, with potentially toxigenic isolates belonging to sections Flavi and Nigri becoming more significant and widespread throughout storage. These fungi were determined to be moderately associated, which can be indicative of mycotoxin co-contamination problems if adequate storage conditions are not secured.P. Rodrigues was supported by grants SFRH/BD/28332/2006 from Fundacao para a Ciencia e a Tecnologia (FCT), and SFRH/PROTEC/49555/2009 from FCT and Polytechnic Institute of Braganca, Portugal
HOSPICIJ-POTREBA HUMANOG DRUŠTVA
Hrvatsko zakonodavstvo i regulativa palijativne skrbi imaju postavljene neke smjernice za razvoj u Republici Hrvatskoj. Međutim, da uhvatimo korak s razvijenim zemljama treba puno toga pravno i organizacijski urediti. Imamo znanje, imamo volju , imamo svijest nesebičnog djelovanja, ali nemamo financijske mogućnosti u ovom trenutku.O palijativnoj skrbi svaki pojedinac počinje razmišljati tek onda kada mu se razboli član njegove obitelji. Da smo u stanju podići ovu djelatnost u prioritete, našla bi se i sredstva za nju. Da bismo mogli iskoristiti znanje koje imamo treba odmah djelovati. To neće biti jednostavan proces, no u svijetu postoji puno modela i primjera, pa bi se uz iskustvo drugih, naš stručni kadar, te djelovanje na fleksibilnost hrvatske birokracije, okolnosti mogle promijeniti u pozitivnom smislu. Ne zbog nas, ali možda i za nas
Usability and digital inclusion: standards and guidelines
This article aims at discussing e-government website usability in relation to concerns about
digital inclusion. E-government web design should consider all aspects of usability, including
those that make it more accessible to all. Traditional concerns of social exclusion are being
superseded by fears that lack of digital competence and information literacy may result in dangerous
digital exclusion. Usability is considered as a way to address this exclusion and should
therefore incorporate inclusion and accessibility guidelines. This article makes an explicit link
between usability guidelines and digital inclusion and reports on a survey of local government
web presence in Portugal
The Critical Role of Notch Ligand Delta-like 1 in the Pathogenesis of Influenza A Virus (H1N1) Infection
Influenza A viral infections have been identified as the etiologic agents for historic pandemics, and contribute to the annual mortality associated with acute viral pneumonia. While both innate and acquired immunity are important in combating influenza virus infection, the mechanism connecting these arms of the immune system remains unknown. Recent data have indicated that the Notch system is an important bridge between antigen-presenting cells (APCs) and T cell communication circuits and plays a central role in driving the immune system to overcome disease. In the present study, we examine the role of Notch signaling during influenza H1N1 virus infection, focusing on APCs. We demonstrate here that macrophages, but not dendritic cells (DCs), increased Notch ligand Delta-like 1 (Dll1) expression following influenza virus challenge. Dll1 expression on macrophages was dependent on retinoic acid-inducible gene-I (RIG-I) induced type-I IFN pathway, and not on the TLR3-TRIF pathway. We also found that IFNα-Receptor knockout mice failed to induce Dll1 expression on lung macrophages and had enhanced mortality during influenza virus infection. Our results further showed that specific neutralization of Dll1 during influenza virus challenge induced higher mortality, impaired viral clearance, and decreased levels of IFN-γ. In addition, we blocked Notch signaling by using γ-secretase inhibitor (GSI), a Notch signaling inhibitor. Intranasal administration of GSI during influenza infection also led to higher mortality, and higher virus load with excessive inflammation and an impaired production of IFN-γ in lungs. Moreover, Dll1 expression on macrophages specifically regulates IFN-γ levels from CD4+and CD8+T cells, which are important for anti-viral immunity. Together, the results of this study show that Dll1 positively influences the development of anti-viral immunity, and may provide mechanistic approaches for modifying and controlling the immune response against influenza H1N1 virus infection
- …