474 research outputs found
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
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
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
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
Stat6 Suppression Prevents Bleomycin-induced Dermal Fibrosis
Fibrosis of the skin and internal organs is a hallmark of systemic sclerosis (SSc). Although the pathogenesis of SSc is poorly understood, increasing evidence suggests that interleukins (IL)-4 and - 13 contribute to the pathogenesis of skin fibrosis by promoting collagen production and myofibroblast differentiation. Signal transducers and activators of transcription 6 (STAT6) is one of the most important downstream transcription factors activated by both IL-4 and IL-13. However, it is not completely understood whether STAT6 plays a role during the pathogenesis of skin fibrosis in SSc. In this study, we observed increased STAT6 phosphorylation in fibrotic skin samples collected from SSc patients as well as bleomycin-injected murine mice. Knockout of Stat6 in mice significantly (1) suppressed the expression of fibrotic cytokines including Il13, Il17, Il22, Ccl2, and the alternatively activated macrophage marker Cd206; (2) reduced the production of collagen and fibronectin, and (3) attenuated late-stage skin fibrosis and inflammation induced by bleomycin. Consistently, mice treated with STAT6 inhibitor AS1517499 also attenuated skin fibrosis on day 28. In addition, a co-culture experiment demonstrated that skin epithelial cells with STAT6 knockdown had reduced cytokine expression in response to IL-4/IL-13, and subsequently attenuated fibrotic protein expression in skin fibroblasts. On the other side, STAT6 depletion in skin fibroblasts attenuated IL-4/IL-13-induced cytokine and fibrotic marker expression, and reduced CXCL2 expression in co-cultured keratinocytes. In summary, our study highlighted an important yet not fully understood role of STAT6 in skin fibrosis by driving innate inflammation and differentiation of alternatively activated macrophages in response to injury
Approximative Analytic Study of Fermions in Magnetar's Crust; Ultra-relativistic Plane Waves, Heun and Mathieu Solutions and Beyond
Working with a magnetic field periodic along and decaying in time, we
deal with the Dirac-type equation characterizing the fermions evolving in
magnetar's crust. For ultra-relativistic particles, one can employ the
perturbative approach, to compute the conserved current density components. If
the magnetic field is frozen and the magnetar is treated as a stationary
object, the fermion's wave function is expressed in terms of the Heun's
Confluent functions. Finally, we are extending some previous investigations on
the linearly independent fermionic modes solutions to the Mathieu's equation
and we discuss the energy spectrum and the Mathieu Characteristic Exponent.Comment: Accepted for publication in Astrophysics & Space Science, 15 pages,
No figure
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
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
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