146 research outputs found
Group Spinner : recognizing and visualizing learning in the classroom for reflection, communication, and planning
Group Spinner is a digital visual tool intended to help teachers observe and reflect on children’s collaborative technology-enhanced learning activities in the classroom. We describe the design of Group Spinner, which was informed by activity theory, previous work and teachers’ focus group feedback. Based on a radar chart and a set of indicators, Group Spinner allows teachers to record in-class observations as to different aspects of group learning and learning behaviors, beyond the limited knowledge acquisition measures. Our exploratory study involved 6 teachers who used the tool for a total of 23 classes in subjects ranging from Maths and Geography to Sociology and Art. Semi-structured interviews with these teachers revealed a number of different uses of the tool. Depending on their experience and pedagogy, teachers considered Group Spinner to be a valuable tool to support awareness, reflection, communication, and/or planning
Nuevos productos electrónicos para 2005
Sección: La RedSiguiendo la línea que el CSIC inició hace tiempo de ir ampliando su oferta de recursos electrónicos en la medida de lo posible cada año, se han suscrito por primera vez en 2005.N
Molecular Ultrasound Imaging of Junctional Adhesion Molecule A Depicts Acute Alterations in Blood Flow and Early Endothelial Dysregulation
Objective: The junctional adhesion molecule A (JAM-A) is physiologically located in interendothelial tight junctions and focally redistributes to the luminal surface of blood vessels under abnormal shear and flow conditions accompanying atherosclerotic lesion development. Therefore, JAM-A was evaluated as a target for molecularly targeted ultrasound imaging of transient endothelial dysfunction under acute blood flow variations.
Approach and Results: Flow-dependent endothelial dysfunction was induced in apolipoprotein E-deficient mice (n=43) by carotid partial ligation. JAM-A expression was investigated by molecular ultrasound using antibody-targeted poly(n-butyl cyanoacrylate) microbubbles and validated with immunofluorescence. Flow disturbance and arterial remodeling were assessed using functional ultrasound. Partial ligation led to an immediate drop in perfusion at the ligated side and a direct compensatory increase at the contralateral side. This was accompanied by a strongly increased JAM-A expression and JAM-A-targeted microbubbles binding at the partially ligated side and by a moderate and temporary increase in the contralateral artery (approximate to 14x [P<0.001] and approximate to 5x [P<0.001] higher than control, respectively), both peaking after 2 weeks. Subsequently, although JAM-A expression and JAM-A-targeted microbubbles binding persisted at a higher level at the partially ligated side, it completely normalized within 4 weeks at the contralateral side. Conclusions: Temporary blood flow variations induce endothelial rearrangement of JAM-A, which can be visualized using JAM-A-targeted microbubbles. Thus, JAM-A may be considered as a marker of acute endothelial activation and dysfunction. Its imaging may facilitate the early detection of cardiovascular risk areas, and it enables the therapeutic prevention of their progression toward an irreversible pathological state
The Tully-Fisher Relation in Cluster Cl0024+1654 at z=0.4
Using moderate-resolution Keck spectra, we have examined the velocity
profiles of 15 members of cluster Cl0024+1654 at z=0.4. WFPC2 images of the
cluster members have been used to determine structural parameters, including
disk sizes, orientations, and inclinations. We compare two methods of optical
rotation curve analysis for kinematic measurements. Both methods take seeing,
slit size and orientation, and instrumental effects into account and yield
similar rotation velocity measurements. Four of the galaxies in our sample
exhibit unusual kinematic signatures, such as non-circular motions. Our key
result is that the Cl0024 galaxies are marginally underluminous (0.50 +/- 0.23
mag), given their rotation velocities, as compared to the local Tully-Fisher
relation. In this analysis, we assume no slope evolution, and take into account
systematic differences between local and distant velocity and luminosity
measurements. Our result is particularly striking considering the Cl0024
members have very strong emission lines, and local galaxies with similar Halpha
equivalent widths tend to be overluminous on the Tully-Fisher relation. Cl0024
Tully-Fisher residuals appear to be correlated most strongly with galaxy
rotation velocities, indicating a possible change in the slope of the
Tully-Fisher relation. However, we caution that this result may be strongly
affected by magnitude selection and by the original slope assumed for the
analysis. Cl0024 residuals also depend weakly on color, emission line strength
and extent, and photometric asymmetry. In a comparison of stellar and gas
motions in two Cl0024 members, we find no evidence for counter-rotating stars
and gas, an expected signature of mergers.Comment: 38 pages, 10 figures, accepted for publication in ApJ; version with
full-resolution figures can be downloaded from
http://www.ucolick.org/~anne/recent_pubs.htm
The shape of the dark matter halo in the early-type galaxy NGC 2974
We present HI observations of the elliptical galaxy NGC 2974, obtained with
the Very Large Array. These observations reveal that the previously detected HI
disc in this galaxy (Kim et al. 1988) is in fact a ring. By studying the
harmonic expansion of the velocity field along the ring, we constrain the
elongation of the halo and find that the underlying gravitational potential is
consistent with an axisymmetric shape.
We construct mass models of NGC 2974 by combining the HI rotation curve with
the central kinematics of the ionised gas, obtained with the integral-field
spectrograph SAURON. We introduce a new way of correcting the observed
velocities of the ionised gas for asymmetric drift, and hereby disentangle the
random motions of the gas caused by gravitational interaction from those caused
by turbulence. To reproduce the observed flat rotation curve of the HI gas, we
need to include a dark halo in our mass models. A pseudo-isothermal sphere
provides the best model to fit our data, but we also tested an NFW halo and
Modified Newtonian Dynamics (MOND), which fit the data marginally worse.
The mass-to-light ratio M/L_I increases in NGC 2974 from 4.3 (M/L_I)sun at
one effective radius to 8.5 (M/L_I)sun at 5 Re. This increase of M/L already
suggests the presence of dark matter: we find that within 5 Re at least 55 per
cent of the total mass is dark.Comment: 17 pages, 20 figures, accepted by MNRA
The DEEP2 Galaxy Redshift Survey: Design, Observations, Data Reduction, and Redshifts
We describe the design and data sample from the DEEP2 Galaxy Redshift Survey,
the densest and largest precision-redshift survey of galaxies at z ~ 1
completed to date. The survey has conducted a comprehensive census of massive
galaxies, their properties, environments, and large-scale structure down to
absolute magnitude M_B = -20 at z ~ 1 via ~90 nights of observation on the
DEIMOS spectrograph at Keck Observatory. DEEP2 covers an area of 2.8 deg^2
divided into four separate fields, observed to a limiting apparent magnitude of
R_AB=24.1. Objects with z < 0.7 are rejected based on BRI photometry in three
of the four DEEP2 fields, allowing galaxies with z > 0.7 to be targeted ~2.5
times more efficiently than in a purely magnitude-limited sample. Approximately
sixty percent of eligible targets are chosen for spectroscopy, yielding nearly
53,000 spectra and more than 38,000 reliable redshift measurements. Most of the
targets which fail to yield secure redshifts are blue objects that lie beyond z
~ 1.45. The DEIMOS 1200-line/mm grating used for the survey delivers high
spectral resolution (R~6000), accurate and secure redshifts, and unique
internal kinematic information. Extensive ancillary data are available in the
DEEP2 fields, particularly in the Extended Groth Strip, which has evolved into
one of the richest multiwavelength regions on the sky. DEEP2 surpasses other
deep precision-redshift surveys at z ~ 1 in terms of galaxy numbers, redshift
accuracy, sample number density, and amount of spectral information. We also
provide an overview of the scientific highlights of the DEEP2 survey thus far.
This paper is intended as a handbook for users of the DEEP2 Data Release 4,
which includes all DEEP2 spectra and redshifts, as well as for the
publicly-available DEEP2 DEIMOS data reduction pipelines. [Abridged]Comment: submitted to ApJS; data products available for download at
http://deep.berkeley.edu/DR4
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