12,392 research outputs found
The implementation and evaluation of a sequential, structured approach for teaching LogoWriter to classroom teachers
The goal of this exploratory study was to implement and evaluate a Logo inservice model which focused on effective principles of staff development and emphasized Logo problem solving using teacher-mediated intervention strategies. The model was designed to facilitate teacher use of Logo in their classrooms;Subjects for this study included 19 elementary teachers and media specialists from the Ames Community Schools. Subjects completed The Stages of Concern Questionnaire (SoCQ), the LogoWriter Basic Comprehension Test, END-OF-DAY inventories, and the Inservice Evaluation LogoWriter Workshop Instrument. Additional outcome measures included projects shared during a final inservice sharing session, and questions, worksheets, and tape recordings from a follow-up discussion session;Results measuring change in teacher stages of concern indicated all participants, except one, made significant shifts to higher stages focusing on using Logo with students. Seven participants were identified as showing potential nonuse tendencies in implementing Logo into their classrooms. Support for Logo implementation was found for structured instructional teaching balanced with opportunities for discovery-based learning;Results from teacher self report of mastery of LogoWriter knowledge and skills indicated that subjects reported mastery of 20 out of 27 objectives. In addition, results from the LogoWriter Basic Comprehension Test validated these self reports. A t-test pairs procedure on the LogoWriter test indicated that there was a significant difference between the pre- and posttest group means (p \u3c.001). Auxiliary findings included results in teacher perceptions of Logo and gender differences;Evaluation of the Logo inservice provided positive support for the Logo inservice approach providing organization and structure and opportunity for individual exploration. Subjects also responded favorably to the inservice sharing session of Logo projects and teaching strategies, and the follow-up sharing session discussing implementation, curriculum integration, classroom management, and Logo procedural concerns. The study found that a structured Logo inservice appears to be a positive step in promoting future use of Logo in the classroom
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Neural precursor cells derived from induced pluripotent stem cells exhibit reduced susceptibility to infection with a neurotropic coronavirus.
The present study examines the susceptibility of mouse induced pluripotent stem cell-derived neural precursor cells (iPSC-NPCs) to infection with the neurotropic JHM strain of mouse hepatitis virus (JHMV). Similar to NPCs derived from striatum of day 1 postnatal GFP-transgenic mice (GFP-NPCs), iPSC-derived NPCs (iPSC-NPCs) are able to differentiate into terminal neural cell types and express MHC class I and II in response to IFN-γ treatment. However, in contrast to postnatally-derived NPCs, iPSC-NPCs express low levels of carcinoembryonic antigen-cell adhesion molecule 1a (CEACAM1a), the surface receptor for JHMV, and are less susceptible to infection and virus-induced cytopathic effects. The relevance of this in terms of therapeutic application of NPCs resistant to viral infection is discussed
The MASSIVE Survey - VIII. Stellar Velocity Dispersion Profiles and Environmental Dependence of Early-Type Galaxies
We measure the radial profiles of the stellar velocity dispersions,
, for 90 early-type galaxies (ETGs) in the MASSIVE survey, a
volume-limited integral-field spectroscopic (IFS) galaxy survey targeting all
northern-sky ETGs with absolute -band magnitude mag, or
stellar mass , within 108 Mpc. Our wide-field
107" 107" IFS data cover radii as large as 40 kpc, for which we
quantify separately the inner (2 kpc) and outer (20 kpc) logarithmic slopes
and of . While
is mostly negative, of the 56 galaxies with sufficient
radial coverage to determine we find 36% to have rising
outer dispersion profiles, 30% to be flat within the uncertainties, and 34% to
be falling. The fraction of galaxies with rising outer profiles increases with
and in denser galaxy environment, with 10 of the 11 most massive galaxies
in our sample having flat or rising dispersion profiles. The strongest
environmental correlations are with local density and halo mass, but a weaker
correlation with large-scale density also exists. The average is similar for brightest group galaxies, satellites, and isolated
galaxies in our sample. We find a clear positive correlation between the
gradients of the outer dispersion profile and the gradients of the velocity
kurtosis . Altogether, our kinematic results suggest that the increasing
fraction of rising dispersion profiles in the most massive ETGs are caused (at
least in part) by variations in the total mass profiles rather than in the
velocity anisotropy alone.Comment: Accepted/in press, MNRA
The MASSIVE Survey - VII. The Relationship of Angular Momentum, Stellar Mass and Environment of Early-Type Galaxies
We analyse the environmental properties of 370 local early-type galaxies
(ETGs) in the MASSIVE and ATLAS3D surveys, two complementary volume-limited
integral-field spectroscopic (IFS) galaxy surveys spanning absolute -band
magnitude , or stellar mass . We find these galaxies to reside in a diverse range of
environments measured by four methods: group membership (whether a galaxy is a
brightest group/cluster galaxy, satellite, or isolated), halo mass, large-scale
mass density (measured over a few Mpc), and local mass density (measured within
the th neighbour). The spatially resolved IFS stellar kinematics provide
robust measurements of the spin parameter and enable us to examine
the relationship among , , and galaxy environment. We find a
strong correlation between and , where the average
decreases from to below 0.1 with increasing mass, and the fraction
of slow rotators increases from % to 90%. We show for
the first time that at fixed , there are almost no trends between galaxy
spin and environment; the apparent kinematic morphology-density relation for
ETGs is therefore primarily driven by and is accounted for by the joint
correlations between and spin, and between and environment. A
possible exception is that the increased at high local density
is slightly more than expected based only on these joint correlations. Our
results suggest that the physical processes responsible for building up the
present-day stellar masses of massive galaxies are also very efficient at
reducing their spin, in any environment.Comment: Accepted to MNRA
The MASSIVE Survey XIII -- Spatially Resolved Stellar Kinematics in the Central 1 kpc of 20 Massive Elliptical Galaxies with the GMOS-North Integral-Field Spectrograph
We use observations from the GEMINI-N/GMOS integral-field spectrograph (IFS)
to obtain spatially resolved stellar kinematics of the central kpc of
20 early-type galaxies (ETGs) with stellar masses greater than in the MASSIVE survey. Together with observations from the wide-field
Mitchell IFS at McDonald Observatory in our earlier work, we obtain
unprecedentedly detailed kinematic maps of local massive ETGs, covering a scale
of kpc. The high () signal-to-noise of the GMOS spectra
enable us to obtain two-dimensional maps of the line-of-sight velocity,
velocity dispersion , as well as the skewness and kurtosis
of the stellar velocity distributions. All but one galaxy in the sample have
profiles that increase towards the center, whereas the slope of
at one effective radius () can be of either sign. The is
generally positive, with 14 of the 20 galaxies having positive within the
GMOS aperture and 18 having positive within . The positive
and rising towards small radii are indicative of a central black
hole and velocity anisotropy. We demonstrate the constraining power of the data
on the mass distributions in ETGs by applying Jeans anisotropic modeling (JAM)
to NGC~1453, the most regular fast rotator in the sample. Despite the
limitations of JAM, we obtain a clear minimum in black hole mass,
stellar mass-to-light ratio, velocity anisotropy parameters, and the circular
velocity of the dark matter halo.Comment: Accepted to Ap
The MASSIVE Survey - X. Misalignment between Kinematic and Photometric Axes and Intrinsic Shapes of Massive Early-Type Galaxies
We use spatially resolved two-dimensional stellar velocity maps over a
field of view to investigate the kinematic features of 90
early-type galaxies above stellar mass in the MASSIVE
survey. We measure the misalignment angle between the kinematic and
photometric axes and identify local features such as velocity twists and
kinematically distinct components. We find 46% of the sample to be well aligned
(), 33% misaligned, and 21% without detectable rotation
(non-rotators). Only 24% of the sample are fast rotators, the majority of which
(91%) are aligned, whereas 57% of the slow rotators are misaligned with a
nearly flat distribution of from to . 11
galaxies have and thus exhibit minor-axis ("prolate")
rotation in which the rotation is preferentially around the photometric major
axis. Kinematic misalignments occur more frequently for lower galaxy spin or
denser galaxy environments. Using the observed misalignment and ellipticity
distributions, we infer the intrinsic shape distribution of our sample and find
that MASSIVE slow rotators are consistent with being mildly triaxial, with mean
axis ratios of and . In terms of local kinematic features,
51% of the sample exhibit kinematic twists of larger than , and 2
galaxies have kinematically distinct components. The frequency of misalignment
and the broad distribution of reported here suggest that the most
massive early-type galaxies are mildly triaxial, and that formation processes
resulting in kinematically misaligned slow rotators such as gas-poor mergers
occur frequently in this mass range.Comment: Accepted to MNRA
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