731 research outputs found
The Influences on K-2 Teachers\u27 Approaches Towards Assessment and Developmentally Appropriate Practice
Kindergarten-second grade teachers often have to navigate conflicting paradigms as they attempt to honor the developmentally appropriate practices best suited for their young learners while working within the demands of the current educational paradigm of high-stakes testing and standardization. This challenge is acutely experienced in the assessment of young children, yet little research has been done to look at how teachers in the early elementary years approach or use assessment in developmentally appropriate ways. The purpose of this study was to use a constructivist grounded theory approach to address the overarching question: How do K-2 teachers come to their conceptualizations regarding developmentally appropriate practices and strong classroom assessment practices? Thirty-five teachers were interviewed in reaching theoretical saturation. Through the constant comparative process of data generation, data analysis, and extensive memoing, the researcher generated a theory with I, They, and We phases to explain the influences on teachers. The study also revealed how teachers conceptualize assessment and the ways teachers’ knowledge, beliefs, and practices interact with each other in regard to classroom assessment and developmentally appropriate practice. The influences of school district administration, teaching colleagues, and experience through time were some of the most considerable influences. Among its implications, the theory suggests a need for more dissemination of knowledge of best practices in early elementary education. The theory also provides a framework for future research to improve assessment decisions and inferences in early elementary classrooms
Generating a Reduced Gravity Environment on Earth
The Active Response Gravity Offload System (ARGOS) is designed to simulate reduced gravity environments, such as Lunar, Martian, or microgravity using a vertical lifting hoist and horizontal motion system. Three directions of motion are provided over a 41 ft x 24 ft x 25 ft tall area. ARGOS supplies a continuous offload of a portion of a person's weight during dynamic motions such as walking, running, and jumping. The ARGOS system tracks the person's motion in the horizontal directions to maintain a vertical offload force directly above the person or payload by measuring the deflection of the cable and adjusting accordingly
Synthetic Galaxy Images and Spectra from the Illustris Simulation
We present our methods for generating a catalog of 7,000 synthetic images and
40,000 integrated spectra of redshift z = 0 galaxies from the Illustris
Simulation. The mock data products are produced by using stellar population
synthesis models to assign spectral energy distributions (SED) to each star
particle in the galaxies. The resulting synthetic images and integrated SEDs
therefore properly reflect the spatial distribution, stellar metallicity
distribution, and star formation history of the galaxies. From the synthetic
data products it is possible to produce monochromatic or color-composite
images, perform SED fitting, classify morphology, determine galaxy structural
properties, and evaluate the impacts of galaxy viewing angle. The main
contribution of this paper is to describe the production, format, and
composition of the image catalog that makes up the Illustris Simulation
Obsevatory. As a demonstration of this resource, we derive galactic stellar
mass estimates by applying the SED fitting code FAST to the synthetic galaxy
products, and compare the derived stellar masses against the true stellar
masses from the simulation. We find from this idealized experiment that
systematic biases exist in the photometrically derived stellar mass values that
can be reduced by using a fixed metallicity in conjunction with a minimum
galaxy age restriction.Comment: 21 pages, 17 figures, submitted to MNRAS. Comments welcom
On the origin of star-gas counterrotation in low-mass galaxies
Stars in galaxies form from the cold rotationally supported gaseous disks
that settle at the center of dark matter halos. In the simplest models, such
angular momentum is acquired early on at the time of collapse of the halo and
preserved thereafter, implying a well-aligned spin for the stellar and gaseous
component. Observations however have shown the presence of gaseous disks in
counterrotation with the stars. We use the Illustris numerical simulations to
study the origin of such counterrotation in low mass galaxies ( - ), a sample where mergers have
not played a significant role. Only of our sample shows a
counterrotating gaseous disk at . These counterrotating disks arise in
galaxies that have had a significant episode of gas removal followed by the
acquisition of new gas with misaligned angular momentum. In our simulations, we
identify two main channels responsible for the gas loss: a strong feedback
burst and gas stripping during a fly-by passage through a more massive group
environment. Once settled, counterrotation can be long-lived with several
galaxies in our sample displaying misaligned components consistently for more
than Gyr. As a result, no major correlation with the present day
environment or structural properties might remain, except for a slight
preference for early type morphologies and a lower than average gas content at
a given stellar mass.Comment: 16 pages, 11 figures. Submitted to ApJ. Comments welcom
Decoupling the rotation of stars and gas - II. The link between black hole activity and simulated IFU kinematics in IllustrisTNG
Funding: UK Science and Technology Funding Council ( STFC) via an PhD studentship (grant number ST/N504427/1) (CD).We study the relationship between supermassive black hole (BH) feedback, BH luminosity and the kinematics of stars and gas for galaxies inIllustrisTNG. We use galaxies with mock MaNGA observations to identify kinematic misalignment at z = 0 (difference in rotation of stars and gas), for which we follow the evolutionary history of BH activity and gas properties over the last 8 Gyrs. Misaligned low mass galaxies (Mstel 1010.2M⊙) with misalignment typically have similar BH luminosities, show lower gas fractions, and have typically lower gas phase metallicity over the last 8 Gyrs in comparison to the high mass aligned.Publisher PDFPeer reviewe
Mitochondrial phenotypes in genetically diverse neurodegenerative diseases and their response to mitofusin activation
Mitochondrial fusion is essential to mitochondrial fitness and cellular health. Neurons of patients with genetic neurodegenerative diseases often exhibit mitochondrial fragmentation, reflecting an imbalance in mitochondrial fusion and fission (mitochondrial dysdynamism). Charcot-Marie-Tooth (CMT) disease type 2A is the prototypical disorder of impaired mitochondrial fusion caused by mutations in the fusion protein mitofusin (MFN)2. Yet, cultured CMT2A patient fibroblast mitochondria are often reported as morphologically normal. Metabolic stress might evoke pathological mitochondrial phenotypes in cultured patient fibroblasts, providing a platform for the pre-clinical individualized evaluation of investigational therapeutics. Here, substitution of galactose for glucose in culture media was used to redirect CMT2A patient fibroblasts (MFN2 T105M, R274W, H361Y, R364W) from glycolytic metabolism to mitochondrial oxidative phosphorylation, which provoked characteristic mitochondrial fragmentation and depolarization and induced a distinct transcriptional signature. Pharmacological MFN activation of metabolically reprogrammed fibroblasts partially reversed the mitochondrial abnormalities in CMT2A and CMT1 and a subset of Parkinson\u27s and Alzheimer\u27s disease patients, implicating addressable mitochondrial dysdynamism in these illnesses
Active Response Gravity Offload and Method
A variable gravity field simulator can be utilized to provide three dimensional simulations for simulated gravity fields selectively ranging from Moon, Mars, and micro-gravity environments and/or other selectable gravity fields. The gravity field simulator utilizes a horizontally moveable carriage with a cable extending from a hoist. The cable can be attached to a load which experiences the effects of the simulated gravity environment. The load can be a human being or robot that makes movements that induce swinging of the cable whereby a horizontal control system reduces swinging energy. A vertical control system uses a non-linear feedback filter to remove noise from a load sensor that is in the same frequency range as signals from the load sensor
Mergers and Mass Accretion Rates in Galaxy Assembly: The Millennium Simulation Compared to Observations of z~2 Galaxies
Recent observations of UV-/optically selected, massive star forming galaxies
at z~2 indicate that the baryonic mass assembly and star formation history is
dominated by continuous rapid accretion of gas and internal secular evolution,
rather than by major mergers. We use the Millennium Simulation to build new
halo merger trees, and extract halo merger fractions and mass accretion rates.
We find that even for halos not undergoing major mergers the mass accretion
rates are plausibly sufficient to account for the high star formation rates
observed in z~2 disks. On the other hand, the fraction of major mergers in the
Millennium Simulation is sufficient to account for the number counts of
submillimeter galaxies (SMGs), in support of observational evidence that these
are major mergers. When following the fate of these two populations in the
Millennium Simulation to z=0, we find that subsequent mergers are not frequent
enough to convert all z~2 turbulent disks into elliptical galaxies at z=0.
Similarly, mergers cannot transform the compact SMGs/red sequence galaxies at
z~2 into observed massive cluster ellipticals at z=0. We argue therefore, that
secular and internal evolution must play an important role in the evolution of
a significant fraction of z~2 UV-/optically and submillimeter selected galaxy
populations.Comment: 5 pages, 4 figures, Accepted for publication in Ap
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