3,582 research outputs found
Detections of C2H, cyclic-C3H2, and H13CN in NGC 1068
We used the Nobeyama 45-m telescope to conduct a spectral line survey in the
3-mm band (85.1-98.4 GHz) toward one of the nearest galaxies with active
galactic nucleus NGC 1068 and the prototypical starburst galaxy NGC 253. The
beam size of this telescope is ~18", which was sufficient to spatially separate
the nuclear molecular emission from the emission of the circumnuclear starburst
region in NGC 1068. We detected rotational transitions of C2H, cyclic-C3H2, and
H13CN in NGC 1068. These are detections of carbon-chain and carbon-ring
molecules in NGC 1068. In addition, the C2H N = 1-0 lines were detected in NGC
253. The column densities of C2H were determined to be 3.4 x 10^15 cm^-2 in NGC
1068 and 1.8 x 10^15 cm^-2 in NGC 253. The column densities of cyclic-C3H2 were
determined to be 1.7 x 10^13 cm^-2 in NGC 1068 and 4.4 x 10^13 cm^-2 in NGC
253. We calculated the abundances of these molecules relative to CS for both
NGC 1068 and NGC 253, and found that there were no significant differences in
the abundances between the two galaxies. This result suggests that the basic
carbon-containing molecules are either insusceptible to AGN, or are tracing
cold (T_rot ~10 K) molecular gas rather than X-ray irradiated hot gas.Comment: 10 pages, 3 figures, Accepted for publication in ApJ Letter. After
the submission of this manuscript, we found two relevant papers. Snell et al.
detected C2H in NGC 1068 (astro-ph 1101.0132). It was very recently published
in The Astronomical Journal 141 38. Costagliola et al. detected C2H and H13CN
in NGC 1068 (astro-ph 1101.2122
The IC2118 association: new T Tauri stars in high-latitude molecular clouds
We identified new pre-main sequence stars in the region of high-latitude
molecular clouds associated with the reflection nebula IC2118, around l = 208
degr and b = -27 degr. The stars were selected as T Tauri candidates in
objective prism plates obtained with the Schmidt telescope of Konkoly
Observatory. Results of spectroscopic follow-up observations, carried out with
the FLAIR spectrograph installed on the UK Schmidt and with ALFOSC on Nordic
Optical Telescope, are presented in this paper. Based on spectral types,
presence of emission lines and lithium absorption line, we identified five
classical T Tauri stars and a candidate weak-line T Tauri star projected on the
molecular clouds, as well as two candidate pre-main sequence stars outside the
nebulous region. Using the near infrared magnitudes obtained from the 2MASS All
Sky Catalog. we determined the masses and ages of these stars. We found that
the five classical T Tauri stars projected on the clouds are physically related
to them, whereas the other stars are probably background objects. Adopting a
distance of 210 pc for IC2118 (Kun et al. 2001) and using Palla & Stahler's
(1999) evolutionary tracks we derived an average age of 2.5 million yrs and a
mass interval of 0.4--1.0 M_sun for the members of the IC2118 association.Comment: 11 pages, 6 figures, accepted for publication by Astronomy and
Astrophysic
Primary phagocytosis of viable neurons by microglia activated with LPS or AÎČ is dependent on calreticulin/LRP phagocytic signalling.
BACKGROUND: Microglia are resident brain macrophages that can phagocytose dead, dying or viable neurons, which may be beneficial or detrimental in inflammatory, ischaemic and neurodegenerative brain pathologies. Cell death caused by phagocytosis of an otherwise viable cell is called 'primary phagocytosis' or 'phagoptosis'. Calreticulin (CRT) exposure on the surface of cancer cells can promote their phagocytosis via LRP (low-density lipoprotein receptor-related protein) on macrophages, but it is not known whether this occurs with neurons and microglia. METHODS: We used primary cultures of cerebellar neurons, astrocytes and microglia to investigate the potential role of CRT/LRP phagocytic signalling in the phagocytosis of viable neurons by microglia stimulated with lipopolysaccharide (LPS) or nanomolar concentrations of amyloid-ÎČ peptide1-42 (AÎČ). Exposure of CRT on the neuronal surface was investigated using surface biotinylation and western blotting. A phagocytosis assay was also developed using BV2 and PC12 cell lines to investigate CRT/LRP signalling in microglial phagocytosis of apoptotic cells. RESULTS: We found that BV2 microglia readily phagocytosed apoptotic PC12 cells, but this was inhibited by a CRT-blocking antibody or LRP-blocking protein (receptor-associated protein: RAP). Activation of primary rat microglia with LPS or AÎČ resulted in loss of co-cultured cerebellar granule neurons, and this was blocked by RAP or antibodies against CRT or against LRP, preventing all neuronal loss and death. CRT was present on the surface of viable neurons, and this exposure did not change in inflammatory conditions. CRT antibodies prevented microglia-induced neuronal loss when added to neurons, while LRP antibodies prevented neuronal loss when added to the microglia. Pre-binding of CRT to neurons promoted neuronal loss if activated microglia were added, but pre-binding of CRT to microglia or both cell types prevented microglia-induced neuronal loss. CONCLUSIONS: CRT exposure on the surface of viable or apoptotic neurons appears to be required for their phagocytosis via LRP receptors on activated microglia, but free CRT can block microglial phagocytosis of neurons by acting on microglia. Phagocytosis of CRT-exposing neurons by microglia can be a direct cause of neuronal death during inflammation, and might therefore contribute to neurodegeneration and be prevented by blocking the CRT/LRP pathway.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are
The Blue Hook Populations of Massive Globular Clusters
We present new HST ultraviolet color-magnitude diagrams of 5 massive Galactic
globular clusters: NGC 2419, NGC 6273, NGC 6715, NGC 6388, and NGC 6441. These
observations were obtained to investigate the "blue hook" phenomenon previously
observed in UV images of the globular clusters omega Cen and NGC 2808. Blue
hook stars are a class of hot (approximately 35,000 K) subluminous horizontal
branch stars that occupy a region of the HR diagram that is unexplained by
canonical stellar evolution theory. By coupling new stellar evolution models to
appropriate non-LTE synthetic spectra, we investigate various theoretical
explanations for these stars. Specifically, we compare our photometry to
canonical models at standard cluster abundances, canonical models with enhanced
helium (consistent with cluster self-enrichment at early times), and
flash-mixed models formed via a late helium-core flash on the white dwarf
cooling curve. We find that flash-mixed models are required to explain the
faint luminosity of the blue hook stars, although neither the canonical models
nor the flash-mixed models can explain the range of color observed in such
stars, especially those in the most metal-rich clusters. Aside from the
variation in the color range, no clear trends emerge in the morphology of the
blue hook population with respect to metallicity.Comment: Accepted for publication in The Astrophysical Journal. Latex, 14
pages, 1 B&W and 6 color figure
Polarization conversion spectroscopy of hybrid modes
Enhanced polarization conversion in reflection for the Otto and Kretschmann
configurations is introduced as a new method for hybrid-mode spectroscopy.
Polarization conversion in reflection appears when hybrid-modes are excited in
a guiding structure composed of at least one anisotropic media. In contrast to
a dark dip, in this case modes are associated to a peak in the converted
reflectance spectrum, increasing the detection sensitivity and avoiding
confusion with reflection dips associated with other processes as can be
transmission.Comment: 4 pages, 4 figure
Body, Sex and Reproduction: the notion of women autonomy questioned: abortion and othersensitive situations
En salud sexual y reproductiva los temas relativos a la autonomĂa son cruciales, personales y a veces muy problemĂĄticos. Nuestro interĂ©s es indagar sobre distintas concepciones acerca del âser una pacienteâ, en tanto pone en juego cuestiones polĂticas y sociales de primer orden, por ejemplo las que tienen que ver con las formas de la autonomĂa y las relaciones sociales de subordinaciĂłn. Y cuestiones que tienen que ver con la construcciĂłn social del cuerpo, la individuaciĂłn y la ciudadanĂa. AquĂ exploramos empĂrica y conceptualmente algunos tipos ideales de paciente, en funciĂłn de su autonomĂa como individuo capaz de juicio y acciĂłn, y como sujeto de derechos y responsabilidades. El anĂĄlisis de diversas situaciones â algunas lĂmite (como el caso del aborto) â nos permiten problematizar quĂ© se entiende por âsujetos/personas autĂłnomos/asâ en el ĂĄmbito de la salud-enfermedad. AquĂ exponemos los resultados del anĂĄlisis que por un lado problematizan la nociĂłn de autonomĂa desligĂĄndola de la matriz liberal y poniĂ©ndola en relaciĂłn con el cuerpo y las emociones en el marco de relaciones interpersonales; y por otro, permiten operacionalizar la tipologĂa de paciente definido en funciĂłn de la autonomĂa de la que partimos (sujeto pasivo, consumidor/usuario, e interlocutor-ciudadano).In the sexual and reproductive health autonomy issues are crucial, personal and sometimes very problematic. Our interest is to research different conceptions of "being a patient," put into play as political and social issues of the first order, for example, having to do with the forms of autonomy and social relations of subordination. And issues that have to do with the social construction of the body, individuation and citizenship. Here we explore some empirical and conceptually ideal patient types, depending on their autonomy as an individual capable of judgment and action, and as a subject of rights and responsibilities. Analysis of different situations - some limit (such asthe case of abortion) - allow usto problematize what is meant by "autonomus person" in the field of health and disease. We present the results of analysis on one hand problematize the notion of autonomy of the liberal matrix separating it and putting it in relation to the body and emotionsin the context of interpersonal relationships, and secondly, allow patient operationalize the typology defined according of autonomy from which we (taxpayer, consumer / user, and peer-citizen).Fil: Brown, Josefina Leonor. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones ; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Pecheny, Mario MartĂn. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones ; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Tamburrino, MarĂa Cecilia. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones ; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; ArgentinaFil: Gattoni, MarĂa Soledad. Universidad de Buenos Aires. Facultad de Ciencias Sociales. Instituto de Investigaciones ; Argentina. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas; Argentin
Strongly hyperbolic Hamiltonian systems in numerical relativity: Formulation and symplectic integration
We consider two strongly hyperbolic Hamiltonian formulations of general
relativity and their numerical integration with a free and a partially
constrained symplectic integrator. In those formulations we use hyperbolic
drivers for the shift and in one case also for the densitized lapse. A system
where the densitized lapse is an external field allows to enforce the momentum
constraints in a holonomically constrained Hamiltonian system and to turn the
Hamilton constraint function from a weak to a strong invariant.
These schemes are tested in a perturbed Minkowski and the Schwarzschild
space-time. In those examples we find advantages of the strongly hyperbolic
formulations over the ADM system presented in [arXiv:0807.0734]. Furthermore we
observe stabilizing effects of the partially constrained evolution in
Schwarzschild space-time as long as the momentum constraints are enforced.Comment: This version clarifies some points concerning the interpretation of
the result
Molecules as tracers of galaxy evolution: an EMIR survey. I. Presentation of the data and first results
We investigate the molecular gas properties of a sample of 23 galaxies in
order to find and test chemical signatures of galaxy evolution and to compare
them to IR evolutionary tracers. Observation at 3 mm wavelengths were obtained
with the EMIR broadband receiver, mounted on the IRAM 30 m telescope on Pico
Veleta, Spain. We compare the emission of the main molecular species with
existing models of chemical evolution by means of line intensity ratios
diagrams and principal component analysis. We detect molecular emission in 19
galaxies in two 8 GHz-wide bands centred at 88 and 112 GHz. The main detected
transitions are the J=1-0 lines of CO, 13CO, HCN, HNC, HCO+, CN, and C2H. We
also detect HC3N J=10-9 in the galaxies IRAS 17208, IC 860, NGC 4418, NGC 7771,
and NGC 1068. The only HC3N detections are in objects with HCO+/HCN<1 and warm
IRAS colours. Galaxies with the highest HC3N/HCN ratios have warm IRAS colours
(60/100 {\mu}m>0.8). The brightest HC3N emission is found in IC 860, where we
also detect the molecule in its vibrationally excited state.We find low HNC/HCN
line ratios (<0.5), that cannot be explained by existing PDR or XDR chemical
models. Bright HC3N emission in HCO+-faint objects may imply that these are not
dominated by X-ray chemistry. Thus the HCN/HCO+ line ratio is not, by itself, a
reliable tracer of XDRs. Bright HC3N and faint HCO+ could be signatures of
embedded starformation, instead of AGN activity
A brown dwarf desert for intermediate mass stars in Sco OB2?
We present JHK observations of 22 intermediate-mass stars in Sco OB2,
obtained with VLT/NACO. The survey was performed to determine the status of
(sub)stellar candidate companions of A and late-B members. The distinction
between companions and background stars is by a comparison with isochrones and
statistical arguments. We are sensitive to companions in the separation range
0.1''-11'' (13-1430 AU) and K<17. We detect 62 secondaries of which 18 are
physical companions (3 new), 11 candidates, and 33 background stars. The
companion masses are in the range 0.03<M<1.19 Msun, with mass ratios
0.06<q<0.55. We include in our sample a subset of 9 targets with multi-color
ADONIS observations from Kouwenhoven et al. (2005). In the ADONIS survey
secondaries with K12 as
background stars. Our multi-color analysis demonstrates that the simple K=12
criterion correctly classifies the secondaries in ~80% of the cases. We
reanalyse the total ADONIS/NACO sample and conclude that of the 176
secondaries, 25 are physical companions, 55 are candidates, and 96 are
background stars. Although we are sensitive and complete to brown dwarfs as
faint as K=14 in the separation range 130-520 AU, we detect only one, giving a
brown dwarf companion fraction of 0.5% (M>30 MJ). However, the number of brown
dwarfs is consistent with an extrapolation of the stellar companion mass
distribution. This indicates that the physical mechanism for the formation of
brown dwarfs around intermediate mass stars is similar to that of stellar
companions, and that the embryo ejection mechanism does not need to be invoked
in order to explain the small number of brown dwarf companions among these
stars.Comment: 29 pages, 9 figures, accepted by A&
The dynamical response to the node defect in thermally activated remagnetization of magnetic dot array
The influence of nonmagnetic central node defect on dynamical properties of
regular square-shaped 5 x 5 segment of magnetic dot array under the thermal
activation is investigated via computer simulations. Using stochastic
Landau-Lifshitz-Gilbert equation we simulate hysteresis and relaxation
processes. The remarkable quantitative and qualitative differences between
magnetic dot arrays with nonmagnetic central node defect and magnetic dot
arrays without defects have been found.Comment: 4 pages,5 figures, submitted to J. Magn. Magn. Matte
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