206 research outputs found
Cross-Cultural Field Placements: Student Teachers Learning From Schools and Communities
The student teaching experience is typically characterized by a collaboration of school and university-cooperating teacher and university supervisor- to prepare novice educators for the instructional, managerial, and disciplinary demands of classroom teaching. Less often are individuals and groups outside of the immediate school environment perceived as active and important contributors to learning outcomes and professional development for student teachers. However, an increasing number of teacher educators are addressing the role of the community in providing student teachers with information and insights that will enhance the classroom experience in vital ways
The quest for planets around subdwarfs and white dwarfs from Kepler space telescope fields: Part I. Techniques and tests of the methods
In this study, we independently test the presence of an exoplanet around the
binary KIC 9472174, which is composed of a red dwarf and a pulsating type B
subdwarf. We also present the results of our search for Jupiter-mass objects
orbiting near to the eclipsing binary KIC 7975824, which is composed of a white
dwarf and type B subdwarf, and the pulsating white dwarf KIC 8626021. The goal
is to test analytical techniques and prepare the ground for a larger search for
possible substellar survivors on tight orbits around post-common envelope
binaries and stars at the end of their evolution, that is, extended horizontal
branch stars and white dwarfs. We, therefore, mainly focus on substellar bodies
orbiting these stars within the range of the host's former red-giant or
asymptotic-giant phase envelopes. Due to the methods we use, the quest is
restricted to single-pulsating type B subdwarf and white dwarf stars and
short-period eclipsing binaries containing a white dwarf or a subdwarf
component.
Results. Based on the three objects studied in this paper, we demonstrate
that these methods can be used to detect giant exoplanets orbiting around
pulsating white dwarf or type B subdwarf stars as well as short-period binary
systems, at distances which fall within the range of the former red-giant
envelope of a single star or the common envelope of a binary. Using our
analysis techniques, we reject the existence of a Jupiter-mass exoplanet around
the binary KIC 9472174 at the distance and orbital period previously suggested
in the literature. We also found that the eclipse timing variations observed in
the binary might depend on the reduction and processing of the Kepler data. The
other two objects analyzed in this work do not have Jupiter mass exoplanets
orbiting within 0.7 - 1.4 AU from them, or larger-mass objects on closer orbits
(the given mass limits are minimum masses).Comment: 8 page
Exploring Student and Faculty Reactions to Smartphone Policies in the Classroom
The current studies examined attitudes about classroom cell phone usage and reactions to cell phone policies among students and faculty. Study 1 documented students’ and faculty’s perceptions of appropriateness of cell phones in the classroom and about what classroom policies should be. Students reported greater leniency regarding cell phone use in the classroom and suggested stricter penalties for inappropriate use. Study 2 surveyed faculty and students about four cell phone policies ranging in level of leniency. The results indicated as policy leniency increased, cell phone use increased and enforcement decreased. Study 3 evaluated students’ reactions to actual classroom cell phone policies. Students reported using their phones more than they anticipated and rated policy enforcement lower than expected, except under a prohibitive policy. These results indicate that differences remain between faculty and students and that there is a mismatch between what students prefer and perceive as effective cell phone policies
Signatures of the disk-jet coupling in the Broad-line Radio Quasar 4C+74.26
Here we explore the disk-jet connection in the broad-line radio quasar
4C+74.26, utilizing the results of the multiwavelength monitoring of the
source. The target is unique in that its radiative output at radio wavelengths
is dominated by a moderately-beamed nuclear jet, at optical frequencies by the
accretion disk, and in the hard X-ray range by the disk corona. Our analysis
reveals a correlation (local and global significance of 96\% and 98\%,
respectively) between the optical and radio bands, with the disk lagging behind
the jet by days. We discuss the possible explanation for this,
speculating that the observed disk and the jet flux changes are generated by
magnetic fluctuations originating within the innermost parts of a truncated
disk, and that the lag is related to a delayed radiative response of the disk
when compared with the propagation timescale of magnetic perturbations along
relativistic outflow. This scenario is supported by the re-analysis of the
NuSTAR data, modelled in terms of a relativistic reflection from the disk
illuminated by the coronal emission, which returns the inner disk radius
. We discuss the global energetics in
the system, arguing that while the accretion proceeds at the Eddington rate,
with the accretion-related bolometric luminosity erg s , the jet total kinetic energy
erg s, inferred from the dynamical
modelling of the giant radio lobes in the source, constitutes only a small
fraction of the available accretion power.Comment: 9 pages and 6 figures, ApJ accepte
The Clusters AgeS Experiment (CASE). II. The Eclipsing Blue Straggler OGLEGC-228 in the Globular Cluster 47 Tuc
We use photometric and spectroscopic observations of the eclipsing binary
OGLEGC-228 (V228) to derive the masses, radii, and luminosities of the
component stars. Based on measured systemic velocity, proper motion and
distance, the system is a blue straggler member of the globular cluster 47 Tuc.
Our analysis shows that V228 is a semi-detached Algol. We obtain M=1.512 +/-
0.022 Msun, R=1.357 +/- 0.019 Rsun, L=7.02 +/- 0.050 Lsun for the hotter and
more luminous primary component and M=0.200 +/- 0.007 Msun, R=1.238 +/- 0.013
Rsun, L=1.57 +/- 0.09 Lsun for the Roche lobe filling secondary.Comment: 19 pages, 5 figures, AJ, in pres
Defective antigen presentation by monocytes in ESRD patients not responding to hepatitis B vaccination: impaired HBsAg internalization and expression of ICAM-1 and HLA-DR/Ia molecules
This study was undertaken to evaluate the monocyte function of uraemic non-responders to hepatitis B vaccination. Therefore, some parameters concerning antigen processing by monocytes (Mo) as antigen presenting cells (APC) were analysed. It was found that in uraemic non-responders, (1) the internalization of HBsAg by monocytes was significantly decreasjed—HBsAg complexed with specific IgG or as immune complex isolated from patients is better internalized compared with free HBsAg; (2) during antigen presentation the expression of adhesion (ICAM-1) and accessory (HLA-DR/Ia) molecules was significantly decreased in uraemic patients, especially in non-responders; and (3) impaired internalization of HBsAg as well as a decrease in ICAM-1 and HLA-DR/Ia expression, correlated well with the blunted proliferation of CD4+ T cells stimulated by autologous monocytes induced by HBsAg
Radial Velocity Studies of Close Binary Stars.VIII
Radial-velocity measurements and sine-curve fits to the orbital velocity
variations are presented for the seventh set of ten close binary systems: V410
Aur, V523 Cas, QW Gem, V921 Her, V2357 Oph, V1130 Tau, HN UMa, HX UMa, HD
93917, NSV 223. All systems, but three (V523 Cas, HD 93917, NSV 223), were
discovered photometrically by the Hipparcos mission. All systems are
double-lined (SB2) binaries and all, but the detached, very close system V1130
Tau, are contact binaries. The broadening-function permitted improvement of the
orbital elements for V523 Cas, which was the only system observed before for
radial velocity variations. Spectroscopic/visual companions were detected for
V410 Aur and HX UMa.Comment: AASTeX5, 4 figures, 3 tables, to appear AJ, June 200
- …