39 research outputs found
Ionization Structure and Spectra of Iron in Gaseous Nebulae}
The emission spectra and the ionization structure of the low ionization
stages of iron, Fe I--IV, in gaseous nebulae are studied. This work includes:
(i) new atomic data: photoionization cross sections, total e-ion recombination
rates, excitation collision strengths, and transition probabilities; (ii)
detailed study of excitation mechanisms for the [Fe II], [Fe III], and [Fe IV]
emission, and spectroscopic analysis of the observed IR, optical, and UV
spectra; (iii) study of the physical structure and kinematics of the nebulae
and their ionization fronts. Spectral analysis of the well observed Orion
nebula is carried out as a test case, using extensive collisional-radiative and
photoionization models. It is shown that the [Fe II] emission from the Orion
nebula is predominantly excited via electron collisions in high density
partially ionized zones; radiative fluorescence is relatively less effective.
Further evidence for high density zones is derived from the [O I] and [Ni II]
spectral lines, as well as from the kinematic measurements of ionic species in
the nebula. The ionization structure of iron in Orion is modeled using the
newly calculated atomic data, showing some significant differences from
previous models. The new model suggests a fully ionized H II region at
densities on the order of cm, and a dynamic partially ionized H
II/H I region at densities of \cm3. Photoionization models also
indicate that the optical [O I] and [Fe II] emission originates in high density
partially ionized regions within ionization fronts. The gas phase iron
abundance in Orion is estimated from observed spectra.Comment: AAS LaTex, 60 pages 18 figures. Astrophysical Journal. in pres
Comparison of Two Quantitative Methods of Discerning Airspace Enlargement in Smoke-Exposed Mice
In this work, we compare two methods for evaluating and quantifying pulmonary airspace enlargement in a mouse model of chronic cigarette smoke exposure. Standard stereological sample preparation, sectioning, and imaging of mouse lung tissues were performed for semi-automated acquisition of mean linear intercept (Lm) data. After completion of the Lm measurements, D2, a metric of airspace enlargement, was measured in a blinded manner on the same lung images using a fully automated technique developed in-house. An analysis of variance (ANOVA) shows that although Lm was able to separate the smoke-exposed and control groups with statistical significance (pâ=â0.034), D2 was better able to differentiate the groups (p<0.001) and did so without any overlap between the control and smoke-exposed individual animal data. In addition, the fully automated implementation of D2 represented a time savings of at least 24x over semi-automated Lm measurements. Although D2 does not provide 3D stereological metrics of airspace dimensions as Lm does, results show that it has higher sensitivity and specificity for detecting the subtle airspace enlargement one would expect to find in mild or early stage emphysema. Therefore, D2 may serve as a more accurate screening measure for detecting early lung disease than Lm
Lung epithelium as a sentinel and effector system in pneumonia â molecular mechanisms of pathogen recognition and signal transduction
Pneumonia, a common disease caused by a great diversity of infectious agents is responsible for enormous morbidity and mortality worldwide. The bronchial and lung epithelium comprises a large surface between host and environment and is attacked as a primary target during lung infection. Besides acting as a mechanical barrier, recent evidence suggests that the lung epithelium functions as an important sentinel system against pathogens. Equipped with transmembranous and cytosolic pathogen-sensing pattern recognition receptors the epithelium detects invading pathogens. A complex signalling results in epithelial cell activation, which essentially participates in initiation and orchestration of the subsequent innate and adaptive immune response. In this review we summarize recent progress in research focussing on molecular mechanisms of pathogen detection, host cell signal transduction, and subsequent activation of lung epithelial cells by pathogens and their virulence factors and point to open questions. The analysis of lung epithelial function in the host response in pneumonia may pave the way to the development of innovative highly needed therapeutics in pneumonia in addition to antibiotics
Comprehensive molecular characterization of the hippo signaling pathway in cancer
Hippo signaling has been recognized as a key tumor suppressor pathway. Here, we perform a comprehensive molecular characterization of 19 Hippo core genes in 9,125 tumor samples across 33 cancer types using multidimensional âomicâ data from The Cancer Genome Atlas. We identify somatic drivers among Hippo genes and the related microRNA (miRNA) regulators, and using functional genomic approaches, we experimentally characterize YAP and TAZ mutation effects and miR-590 and miR-200a regulation for TAZ. Hippo pathway activity is best characterized by a YAP/TAZ transcriptional target signature of 22 genes, which shows robust prognostic power across cancer types. Our elastic-net integrated modeling further reveals cancer-type-specific pathway regulators and associated cancer drivers. Our results highlight the importance of Hippo signaling in squamous cell cancers, characterized by frequent amplification of YAP/TAZ, high expression heterogeneity, and significant prognostic patterns. This study represents a systems-biology approach to characterizing key cancer signaling pathways in the post-genomic era
International Astronomical Union Sympoisum No.50
Dr J. Landi Dessy, Director of the Astronomical Observatory, Cordoba, Argentina, invited the International Astronomical Union to hold a Symposium in Cordoba in connection with the celebration of the Centennial of the Cordoba Observatory; the date of foundation is October 24, 1871. He proposed that the Symposium should deal with Spectral Classification and Multicolour Photometry as seven years had elapsed since the Symposium No. 24 in Saltsj6baden, and much development had occurred in the field. The invitation and the proposal were accepted by the IAU, and the Symposium was held in Villa Carlos Paz, near Cordoba, between October 18 and October 24, 1971. It was attended by about 50 scientists representing Argentina, Canada, Chile, Den mark, France, Germany, Italy, Mexico, Sweden, Switzerland, U.K., U.S.A., Vatican City State and Venezuela. The Symposium was divided into four sessions: 1. Classification of slit spectra, 2. Classification of objective-prism spectra, 3. Photometric classification, 4. Catalogues and documentation. It was decided not to include problems of calibration of absolute magnitudes and temperatures of stars but to refer this to a separate symposium. The contents of the present volume follow closely the programmes of the individual sessions of the Symposium. All the participants at the Symposium appreciated the excellent hospitality of their Argentinian hosts and the efficient help given by the staff ofthe Cordoba Observatory
Les bandes de CN et C2 dans les spectres des étoiles carbonées (classe C)
La présence d'atomes 12C, 13C, 14N, 15N permet d'expliquer la nature complexe des bandes de CN et C2 observées dans les spectres des étoiles de classe C. Mais les abondances trouvées à partir de ces spectres pour les différents isotopes sont tout à fait surprenantes (35 pour 100 pour 13C, 25 pour 100 pour 15N). De nouvelles mesures, et une théorie plus précise de l'absorption dans les atmosphÚres de ces étoiles sont nécessaires
New determination of the solar apex
Many studies recently have been performed to determine the velocity vector of the Sun,
mainly using the latest data on proper motions and parallaxes given by the Hipparcos satellite.
We wished to carry out a similar study using totally independent data: the numerous radial
velocities (RV) obtained with the Fehrenbach Objective Prisms (PO).
This method allows the determination of the RVs of all the stars contained in the same field.
These RVs are relative to each other but are linked to the IAU standard system by means of at least
two calibration stars of known RV belonging to
that field.
These data are very homogeneous. We discuss the precision of the results, and deduce
that this material is relevant for the computation of the movement of the Sun towards its Apex.
We have performed several studies:
1) With 6965 stars of magnitudes ranging from 7 to 10, measured with the small PO of 15 cm
diameter (PPO), with the whole sample and with the same sample split into blue and red stars.
2) With 11 978 stars of magnitudes ranging from 7 to 11, by adding to the previous sample the
stars measured with the 60 cm diameter PO associated with the Schmidt telescope of
Observatoire de Haute Provence (SPO).
The results of both studies are consistent.
3) We have estimated the distance D of all stars studied and determined U, V, W and S for four groups of stars selected according to their distances:
parsecs.
We have determined the variation of U, V, W and S with respect
to the distance of the stars. The variation of U, V and S is linear up to
500 parsecs. We can consider that W is constant
Mesures de vitesses radiales
We publish 1879 radial velocities of stars distributed
in 105 fields of . We continue
the PPO series (Fehrenbach et al. 1987;
Duflot et al. 1990, 1992 and 1995), using the Fehrenbach
objective prism method
The effect of 15 consecutive days of heatâexercise acclimation on heat shock protein 70
The purpose of this study was to investigate the alterations in serum heat shock protein (Hsp) 70 levels during a 15-consecutive-day intermittent heatâexercise protocol in a 29-year-old male ultra marathon runner. Heat acclimation, for the purpose of physical activities in elevated ambient temperatures, has numerous physiological benefits including mechanisms such as improved cardiac output, increased plasma volume and a decreased core temperature (Tc). In addition to the central adaptations, the role of Hsp during heat acclimation has received an increasing amount of attention. The acclimation protocol applied was designed to correspond with the athleteâs tapering period for the 2007 Marathon Des Sables. The subject (VO2maxâ=â50.7 ml·kgâ1·minâ1, peak power output [PPO]â=â376 W) cycled daily for 90 min at a workload corresponding to 50% of VO2max in a temperature-controlled room (average WBGTâ=â31.9â±â0.9°C). Venous blood was sampled before and after each session for measurement of serum osmolality and serum Hsp70. In addition, Tc, heart rate (HR) and power output (PO) was measured throughout the 90 min to ensure that heat acclimation was achieved during the 15-day period. The results show that the subject was successfully heat acclimated as seen by the lowered HR at rest and during exercise, decreased resting and exercising Tc and an increased PO. The heat exercise resulted in an initial increase in Hsp70 concentrations, known as thermotolerance, and the increase in Hsp70 after exercise was inversely correlated to the resting values of Hsp70 (Spearmanâs rank correlationâ=ââ0.81, pâ<â0.01). Furthermore, the 15-day heatâexercise protocol also increased the basal levels of Hsp70, a response different from that of thermotolerance. This is, as far as we are aware, the first report showing Hsp70 levels during consecutive days of intermittent heat exposure giving rise to heat acclimation. In conclusion, a relatively longer heat acclimation protocol is suggested to obtain maximum benefit of heat acclimation inclusive of both cellular and systemic adaptations