976 research outputs found
Charged-Current Neutral Pion production at SciBooNE
SciBooNE, located in the Booster Neutrino Beam at Fermilab, collected data
from June 2007 to August 2008 to accurately measure muon neutrino and
anti-neutrino cross sections on carbon below 1 GeV neutrino energy. SciBooNE is
studying charged current interactions. Among them, neutral pion production
interactions will be the focus of this poster. The experimental signature of
neutrino-induced neutral pion production is constituted by two electromagnetic
cascades initiated by the conversion of the neutral pion decay photons, with an
additional muon in the final state for CC processes.
In this poster, I will present how we reconstruct and select charged-current
muon neutrino interactions producing neutral pions in SciBooNE.Comment: NuInt09 poster proceedings, 4 page
Patterns of antenal sensilla of Panstrongylus megistus from three Brazilian states
The objective of the present study was to analyze and describe the phenotype of the antennal sensilla of Panstrongylus megistus, one of the epidemiologically most important species of triatomines in Brazil. Specimens from the Brazilian states of GoiĂĄs (GO), Minas Gerais (MG), and Rio Grande do Sul (RS) were compared, based on studies of four types of sensilla on three antennal segments: thick-walled trichoid (TK), thin-walled trichoid (TH), bristles (BR), and basiconica (BA). Discriminant analysis allowed the separation of the RS specimens from those of GO and MG. Multivariate discriminant analysis demonstrated that the sensilla of males differed from those of females, the variables with greatest weight being the BA of all three segments and the TK of flagellum 1. The basiconica sensilla were significantly more abundant in females, on all three segments. Antennal sensilla patterns also demonstrated significant differences among P. megistus specimens.Fil: Villela, M. M.. FundaciĂłn Oswaldo Cruz; BrasilFil: Catala, Silvia Susana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica de La Rioja. - Universidad Nacional de La Rioja. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica de La Rioja. - Universidad Nacional de Catamarca. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica de La Rioja. - SecretarĂa de Industria y MinerĂa. Servicio GeolĂłgico Minero Argentino. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica de La Rioja. - Provincia de La Rioja. Centro Regional de Investigaciones CientĂficas y Transferencia TecnolĂłgica de La Rioja; ArgentinaFil: Juberg, J.. Instituto Oswaldo Cruz; Brasil. FundaciĂłn Oswaldo Cruz; BrasilFil: Silva, I. G.. Universidade Federal de GoiĂĄs; BrasilFil: Dias, J. C. P.. FundaciĂłn Oswaldo Cruz; Brasi
Spectropolarimetry of the H-alpha line in Herbig Ae/Be stars
Using the HiVIS spectropolarimeter built for the Haleakala 3.7m AEOS
telescope, we have obtained a large number of high precision spectropolarimetrc
observations (284) of Herbig AeBe stars collected over 53 nights totaling more
than 300 hours of observing. Our sample of five HAeBe stars: AB Aurigae,
MWC480, MWC120, MWC158 and HD58647, all show systematic variations in the
linear polarization amplitude and direction as a function of time and
wavelength near the H-alpha line. In all our stars, the H-alpha line profiles
show evidence of an intervening disk or outflowing wind, evidenced by strong
emission with an absorptive component. The linear polarization varies by 0.2%
to 1.5% with the change typically centered in the absorptive part of the line
profile. These observations are inconsistent with a simple disk-scattering
model or a depolarization model which produce polarization changes centered on
the emmissive core. We speculate that polarized absorption via optical pumping
of the intervening gas may be the cause.Comment: Accepted for publication in ApJ Letter
Size dependence of the photoinduced magnetism and long-range ordering in Prussian blue analog nanoparticles of rubidium cobalt hexacyanoferrate
Nanoparticles of rubidium cobalt hexacyanoferrate
(RbCo[Fe(CN)]HO) were synthesized using different
concentrations of the polyvinylpyrrolidone (PVP) to produce four different
batches of particles with characteristic diameters ranging from 3 to 13 nm.
Upon illumination with white light at 5 K, the magnetization of these particles
increases. The long-range ferrimagnetic ordering temperatures and the coercive
fields evolve with nanoparticle size. At 2 K, particles with diameters less
than approximately 10 nm provide a Curie-like magnetic signal.Comment: 10 pages, 6 figures in text, expanded text and dat
Polarization dOTF: on-sky focal plane wavefront sensing
The differential Optical Transfer Function (dOTF) is a focal plane wavefront
sensing method that uses a diversity in the pupil plane to generate two
different focal plane images. The difference of their Fourier transforms
recovers the complex amplitude of the pupil down to the spatial scale of the
diversity. We produce two simultaneous PSF images with diversity using a
polarizing filter at the edge of the telescope pupil, and a polarization camera
to simultaneously record the two images. Here we present the first on-sky
demonstration of polarization dOTF at the 1.0m South African Astronomical
Observatory telescope in Sutherland, and our attempt to validate it with
simultaneous Shack-Hartmann wavefront sensor images.Comment: 11 pages, 9 figures, Proc. SPIE Vol. 991
Asymptotic and measured large frequency separations
With the space-borne missions CoRoT and Kepler, a large amount of
asteroseismic data is now available. So-called global oscillation parameters
are inferred to characterize the large sets of stars, to perform ensemble
asteroseismology, and to derive scaling relations. The mean large separation is
such a key parameter. It is therefore crucial to measure it with the highest
accuracy. As the conditions of measurement of the large separation do not
coincide with its theoretical definition, we revisit the asymptotic expressions
used for analysing the observed oscillation spectra. Then, we examine the
consequence of the difference between the observed and asymptotic values of the
mean large separation. The analysis is focused on radial modes. We use series
of radial-mode frequencies to compare the asymptotic and observational values
of the large separation. We propose a simple formulation to correct the
observed value of the large separation and then derive its asymptotic
counterpart. We prove that, apart from glitches due to stellar structure
discontinuities, the asymptotic expansion is valid from main-sequence stars to
red giants. Our model shows that the asymptotic offset is close to 1/4, as in
the theoretical development. High-quality solar-like oscillation spectra
derived from precise photometric measurements are definitely better described
with the second-order asymptotic expansion. The second-order term is
responsible for the curvature observed in the \'echelle diagrams used for
analysing the oscillation spectra and this curvature is responsible for the
difference between the observed and asymptotic values of the large separation.
Taking it into account yields a revision of the scaling relations providing
more accurate asteroseismic estimates of the stellar mass and radius.Comment: accepted in A&
Spectropolarimetric Observations of Herbig Ae/Be Stars. II. Comparison of Spectropolarimetric Surveys: HAeBe, Be and Other Emission-Line Stars
The polarization of light across individual spectral lines contains
information about the circumstellar environment on very small spatial scales.
We have obtained a large number of high precision, high resolution
spectropolarimetric observations of Herbig Ae/Be, Classical Be and other
emission-line stars collected on 117 nights of observations with the HiVIS
spectropolarimeter at a resolution of R=13000 on the 3.67m AEOS telescope. We
also have many observations from the ESPaDOnS spectropolarimeter at a
resolution of R=68000 on the 3.6m CFH telescope. In roughly ~2/3 of the
so-called "windy" or "disky" Herbig Ae/Be stars, the detected H-alpha linear
polarization varies from our typical detection threshold near 0.1% to over 2%.
In all but one HAe/Be star the detected polarization effect is not coincident
with the H-alpha emission peak but is detected in and around the obvious
absorptive part of the line profile. The qu-loops are dominated by the
polarization in this absorptive region. In several stars the polarization
varies in time mostly in the absorptive component and is not necessarily tied
to corresponding variations in intensity. This is a new result not seen at
lower resolution. In the Be and emission-line stars, 10 out of a sample of 30
show a typical broad depolarization effect but 4 of these 10 show weaker
effects only visible at high resolution. Another 5 of 30 show smaller
amplitude, more complex signatures. Six stars of alternate classification
showed large amplitude (1-3%) absorptive polarization effects. These detections
are largely inconsistent with the traditional disk-scattering and
depolarization models.Comment: Published in ApJS 180. 47 pages, 34 figures. Small corrections made
to tex
The universal red-giant oscillation pattern; an automated determination with CoRoT data
The CoRoT and Kepler satellites have provided thousands of red-giant
oscillation spectra. The analysis of these spectra requires efficient methods
for identifying all eigenmode parameters. The assumption of new scaling laws
allows us to construct a theoretical oscillation pattern. We then obtain a
highly precise determination of the large separation by correlating the
observed patterns with this reference. We demonstrate that this pattern is
universal and are able to unambiguously assign the eigenmode radial orders and
angular degrees. This solves one of the current outstanding problems of
asteroseismology hence allowing precise theoretical investigation of red-giant
interiors.Comment: Accepted in A&A letter
Insulin and Glucagon Impairments in Relation with Islet Cells Morphological Modifications Following Long Term Pancreatic Duct Ligation in the Rabbit â A Model of Non-insulin-dependent Diabete
Plasma levels of glucose, insulin and glucagon were
measured at various time intervals after pancreatic
duct ligation (PDL) in rabbits. Two hyperglycemic
periods were observed: one between 15â90 days
(peak at 30 days of 15.1 ± 1.2mmol/l, p < 0.01), and
the other at 450 days (11.2 ± 0.5 mmol/l, p < 0.02). The
first hyperglycemic episode was significantly correlated
with both hypoinsulinemia (41.8 ± 8pmol/l,
r= â0.94, p < 0.01) and hyperglucagonemia (232 ±
21ng/l, r=0.95, p < 0.01). However, the late hyperglycemic
phase (450 days), which was not accompanied
by hypoinsulinemia, was observed after the
hyperglucagonemia (390 days) produced by abundant
immunostained A-cells giving rise to a 3-fold
increase in pancreatic glucagon stores. The insulin
and glucagon responses to glucose loading at 180,
270 and 450 days reflected the insensitivity of B- and
A-cells to glucose. The PDL rabbit model with
chronic and severe glycemic disorders due to the
predominant role of glucagon mimicked key features
of the NIDDM syndrome secondary to
exocrine disease
Magnetic cycles of the planet-hosting star tauBootis
We have obtained new spectropolarimetric observations of the planet-hosting
star tauBootis, using the ESPaDOnS and NARVAL spectropolarimeters at the
Canada-France-Hawaii Telescope and Telescope Bernard-Lyot. With this data set,
we are able to confirm the presence of a magnetic field at the surface of
tauBoo and map its large-scale structure over the whole star. The overall
polarity of the magnetic field has reversed with respect to our previous
observation (obtained a year before), strongly suggesting that tauBoo is
undergoing magnetic cycles similar to those of the Sun. This is the first time
that a global magnetic polarity switch is observed in a star other than the
Sun; we speculate that the magnetic cycle period of tauBoo is much shorter than
that of the Sun.
Our new data also allow us to confirm the presence of differential rotation
from the latitudinal shearing that the magnetic structure is undergoing. The
differential rotation surface shear that tauBoo experiences is found to be 6 to
10 times larger than that of the Sun. We propose that the short magnetic cycle
period is due to the strong level of differential rotation. With a rotation
period of 3.0 and 3.9 d at the equator and pole respectively, tauBoo appears as
the first planet-hosting star whose rotation (at intermediate latitudes) is
synchronised with the orbital motion of its giant planet (period 3.3 d).
Assuming that this synchronisation is not coincidental, it suggests that the
tidal effects induced by the giant planet can be strong enough to force the
thin convective enveloppe (though not the whole star) into corotation and thus
to play a role in the activity cycle of tauBoo.Comment: MNRAS, in pres
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