80 research outputs found
Proposal: DREAMers Success Resource Center (DSRC)
Proposal to create a DREAMers Success Resource Center at Portland State University
Bactrospora totonacae (Arthoniales, Ascomycota), una nueva especie de Veracruz, MĂ©xico
Background and Aims: Bactrospora is a genus of crustose lichens characterized by its black, verrucose to denticulate and little apothecia, and mostly acicular, or sometimes muriform spores, longer than wide. The genus is represented by 38 accepted species. The aim of this work is to describe Bactrospora totonacae, a new species from the tropical dry forest of Veracruz, Mexico. Methods: The specimens were collected on the “Cerro de los Metates” in the municipality of Actopan, Veracruz, Mexico. Macrochemical tests, UV reaction, and a thin layer chromatography were performed; likewise, the presence of amyloid substances distributed in the thallus and ascomata was verified with Lugol’s solution. The voucher is deposited in the herbarium XALU of the Facultad de BiologĂa of the Universidad Veracruzana. Key results: The new species Bactrospora totonacae is characterized by the pruine K+ reddish magenta in its disc. Conclusions: The described species is unique in Bactrospora because the combination of pruine K+ reddish magenta and a thick carbonized exciple has never been reported in this genus.Antecedentes y Objetivos: Bactrospora es un gĂ©nero de lĂquenes costrosos que se caracteriza por el color negro, aspecto verrucoso a denticulado y pequeño de sus apotecios, posee esporas mayoritariamente aciculares y en ocasiones muriformes, pero siempre más largas que anchas. El gĂ©nero está representado por 38 especies aceptadas. El objetivo de este trabajo es describir Bactrospora totonacae, una especie nueva del bosque tropical seco de Veracruz, MĂ©xico.MĂ©todos: Los especĂmenes fueron recolectados en el “Cerro de los Metates”, municipio Actopan, Veracruz, MĂ©xico. Se realizaron pruebas macroquĂmicas, reacciĂłn UV y cromatografĂa en capa fina; asimismo, con la soluciĂłn de Lugol se verificĂł la presencia de sustancias amiloides distribuidas en el talo y el ascoma. Las muestras estudiadas se depositaron en el herbario XALU de la Facultad de BiologĂa de la Universidad Veracruzana.Resultados clave: La nueva especie Bactrospora totonacae se caracteriza por presentar pruina K + magenta rojizo en el disco.
Conclusiones: La especie que se describe en Bactrospora es Ăşnica porque la combinaciĂłn de pruina K + magenta rojizo y un excĂpulo carbonizado y grueso no habĂa sido reportada en alguna otra especie de este gĂ©nero
Multifrequency monitoring of the blazar 0716+714 during the GASP-WEBT-AGILE campaign of 2007
Since the CGRO operation in 1991-2000, one of the primary unresolved
questions about the blazar gamma-ray emission has been its possible correlation
with the low-energy (in particular optical) emission. To help answer this
problem, the Whole Earth Blazar Telescope (WEBT) consortium has organized the
GLAST-AGILE Support Program (GASP) to provide the optical-to-radio monitoring
data to be compared with the gamma-ray detections by the AGILE and GLAST
satellites. This new WEBT project started in early September 2007, just before
a strong gamma-ray detection of 0716+714 by AGILE. We present the GASP-WEBT
optical and radio light curves of this blazar obtained in July-November 2007,
about various AGILE pointings at the source. We construct NIR-to-UV spectral
energy distributions (SEDs), by assembling GASP-WEBT data together with UV data
from the Swift ToO observations of late October. We observe a contemporaneous
optical-radio outburst, which is a rare and interesting phenomenon in blazars.
The shape of the SEDs during the outburst appears peculiarly wavy because of an
optical excess and a UV drop-and-rise. The optical light curve is well sampled
during the AGILE pointings, showing prominent and sharp flares. A future
cross-correlation analysis of the optical and AGILE data will shed light on the
expected relationship between these flares and the gamma-ray events.Comment: 5 pages, 5 figures, to be published in A&A (Letters); revised to
match the final version (changes in Fig. 5 and related text
WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components
In 2007-2008 we carried out a new multiwavelength campaign of the Whole Earth
Blazar Telescope (WEBT) on BL Lacertae, involving three pointings by the
XMM-Newton satellite, to study its emission properties. The source was
monitored in the optical-to-radio bands by 37 telescopes. The brightness level
was relatively low. Some episodes of very fast variability were detected in the
optical bands. The X-ray spectra are well fitted by a power law with photon
index of about 2 and photoelectric absorption exceeding the Galactic value.
However, when taking into account the presence of a molecular cloud on the line
of sight, the data are best fitted by a double power law, implying a concave
X-ray spectrum. The spectral energy distributions (SEDs) built with
simultaneous radio-to-X-ray data at the epochs of the XMM-Newton observations
suggest that the peak of the synchrotron emission lies in the near-IR band, and
show a prominent UV excess, besides a slight soft-X-ray excess. A comparison
with the SEDs corresponding to previous observations with X-ray satellites
shows that the X-ray spectrum is extremely variable. We ascribe the UV excess
to thermal emission from the accretion disc, and the other broad-band spectral
features to the presence of two synchrotron components, with their related SSC
emission. We fit the thermal emission with a black body law and the non-thermal
components by means of a helical jet model. The fit indicates a disc
temperature greater than 20000 K and a luminosity greater than 6 x 10^44 erg/s.Comment: 11 pages, 7 figures, accepted for publication in A&
On the nature of Delta Scuti star HD 115520
Observing Delta Scuti stars is most important as their multi-frequency
spectrum of radial pulsations provide strong constraints on the physics of the
stars interior; so any new detection and observation of these stars is a
valuable contribution to asteroseismology. While performing uvby-beta
photoelectric photometry of some RR Lyrae stars acquired in 2005 at the
Observatorio Astronomico Nacional, Mexico, we also observed several standard
stars, HD115520 among them. After the reduction this star showed indications of
variability. In view of this, a new observing run was carried out in 2006
during which we were able to demonstrate its variability and its nature as a
Delta Scuti star. New observations in 2007 permitted us to determine its
periodic content with more accuracy. This, along with the uvby-beta
photoelectric photometry allowed us to deduce its physical characteristics and
pulsational modes.Comment: 6 pages. To be published in Journal of Physics: Conference Series.
Proc. of the workshop Helioseismology, Asteroseismology and MHD Connections
held in Gottingen, Germany, 20-24 August 200
Multiwavelength observations of 3C 454.3. III. Eighteen months of AGILE monitoring of the "Crazy Diamond"
We report on 18 months of multiwavelength observations of the blazar 3C 454.3
(Crazy Diamond) carried out in July 2007-January 2009. We show the results of
the AGILE campaigns which took place on May-June 2008, July-August 2008, and
October 2008-January 2009. During the May 2008-January 2009 period, the source
average flux was highly variable, from an average gamma-ray flux F(E>100MeV) >
200E-8 ph/cm2/s in May-June 2008, to F(E>100MeV)~80E-8 ph/cm2/s in October
2008-January 2009. The average gamma-ray spectrum between 100 MeV and 1 GeV can
be fit by a simple power law (Gamma_GRID ~ 2.0 to 2.2). Only 3-sigma upper
limits can be derived in the 20-60 keV energy band with Super-AGILE. During
July-August 2007 and May-June 2008, RXTE measured a flux of F(3-20 keV)=
8.4E-11 erg/cm2/s, and F(3-20 keV)=4.5E-11 erg/cm2/s, respectively and a
constant photon index Gamma_PCA=1.65. Swift/XRT observations were carried out
during all AGILE campaigns, obtaining a F(2-10 keV)=(0.9-7.5)E-11 erg/cm2/s and
a photon index Gamma_XRT=1.33-2.04. BAT measured an average flux of ~5 mCrab.
GASP-WEBT monitored 3C 454.3 during the whole 2007-2008 period from the radio
to the optical. A correlation analysis between the optical and the gamma-ray
fluxes shows a time lag of tau=-0.4 days. An analysis of 15 GHz and 43 GHz VLBI
core radio flux observations shows an increasing trend of the core radio flux,
anti- correlated with the higher frequency data. The modeling SEDs, and the
behavior of the long-term light curves in different energy bands, allow us to
compare the jet properties during different emission states, and to study the
geometrical properties of the jet on a time-span longer than one year.Comment: Accepted for publication in ApJ. Adapted Abstract. 17 pages, 19
Figures, 5 Table
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