42 research outputs found
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Three Applications of Automated Test Assembly within a User-Friendly Modeling Environment
While linear programming is a common tool in business and industry, there have not been many applications in educational assessment and only a handful of individuals have been actively involved in conducting psychometric research in this area. Perhaps this is due, at least in part, to the complexity of existing software packages. This article presents three applications of linear programming to automate test assembly using an add-in to Microsoft Excel 2007. These increasingly complex examples permit the reader to readily see and manipulate the programming objectives and constraints within a familiar modeling environment. A spreadsheet used in this demonstration is available for downloading. Accessed 12,243 times on https://pareonline.net from June 21, 2009 to December 31, 2019. For downloads from January 1, 2020 forward, please click on the PlumX Metrics link to the right
The ASTRO-H X-ray Observatory
The joint JAXA/NASA ASTRO-H mission is the sixth in a series of highly
successful X-ray missions initiated by the Institute of Space and Astronautical
Science (ISAS). ASTRO-H will investigate the physics of the high-energy
universe via a suite of four instruments, covering a very wide energy range,
from 0.3 keV to 600 keV. These instruments include a high-resolution,
high-throughput spectrometer sensitive over 0.3-2 keV with high spectral
resolution of Delta E < 7 eV, enabled by a micro-calorimeter array located in
the focal plane of thin-foil X-ray optics; hard X-ray imaging spectrometers
covering 5-80 keV, located in the focal plane of multilayer-coated, focusing
hard X-ray mirrors; a wide-field imaging spectrometer sensitive over 0.4-12
keV, with an X-ray CCD camera in the focal plane of a soft X-ray telescope; and
a non-focusing Compton-camera type soft gamma-ray detector, sensitive in the
40-600 keV band. The simultaneous broad bandpass, coupled with high spectral
resolution, will enable the pursuit of a wide variety of important science
themes.Comment: 22 pages, 17 figures, Proceedings of the SPIE Astronomical
Instrumentation "Space Telescopes and Instrumentation 2012: Ultraviolet to
Gamma Ray
The Quiescent Intracluster Medium in the Core of the Perseus Cluster
Clusters of galaxies are the most massive gravitationally-bound objects in
the Universe and are still forming. They are thus important probes of
cosmological parameters and a host of astrophysical processes. Knowledge of the
dynamics of the pervasive hot gas, which dominates in mass over stars in a
cluster, is a crucial missing ingredient. It can enable new insights into
mechanical energy injection by the central supermassive black hole and the use
of hydrostatic equilibrium for the determination of cluster masses. X-rays from
the core of the Perseus cluster are emitted by the 50 million K diffuse hot
plasma filling its gravitational potential well. The Active Galactic Nucleus of
the central galaxy NGC1275 is pumping jetted energy into the surrounding
intracluster medium, creating buoyant bubbles filled with relativistic plasma.
These likely induce motions in the intracluster medium and heat the inner gas
preventing runaway radiative cooling; a process known as Active Galactic
Nucleus Feedback. Here we report on Hitomi X-ray observations of the Perseus
cluster core, which reveal a remarkably quiescent atmosphere where the gas has
a line-of-sight velocity dispersion of 164+/-10 km/s in a region 30-60 kpc from
the central nucleus. A gradient in the line-of-sight velocity of 150+/-70 km/s
is found across the 60 kpc image of the cluster core. Turbulent pressure
support in the gas is 4% or less of the thermodynamic pressure, with large
scale shear at most doubling that estimate. We infer that total cluster masses
determined from hydrostatic equilibrium in the central regions need little
correction for turbulent pressure.Comment: 31 pages, 11 Figs, published in Nature July
La Boheme
Direcció Artística Napoleone AnnovazziEl repartiment el formen Ken Neate, Antonio Cabanes, Jacinto Santamaría, Anna Leonelli, Pedro Clavería, Manuel Ausensi, Antonio Campo, Ana María Olaria i José Torruella; els decorats són realitzats per Ramón BatlleEmpresa: José F. ArquerOrquestra del Gran Teatre del Liceu ; director Angelo QuestaPrograma de La Bohème, òpera en quatre actes de Giacomo Puccini i llibret de Giuseppe Giacosa i Luigi IllicaDe cada obra s'ha digitalitzat un programa sencer. De la resta s'han digitalitzat les parts que són diferents
Hitomi (ASTRO-H) X-ray Astronomy Satellite
The Hitomi (ASTRO-H) mission is the sixth Japanese x-ray astronomy satellite developed by a large international collaboration, including Japan, USA, Canada, and Europe. The mission aimed to provide the highest energy resolution ever achieved at E > 2 keV, using a microcalorimeter instrument, and to cover a wide energy range spanning four decades in energy from soft x-rays to gamma rays. After a successful launch on February 17, 2016, the spacecraft lost its function on March 26, 2016, but the commissioning phase for about a month provided valuable information on the onboard instruments and the spacecraft system, including astrophysical results obtained from first light observations. The paper describes the Hitomi (ASTRO-H) mission, its capabilities, the initial operation, and the instruments/spacecraft performances confirmed during the commissioning operations for about a month
Replication Data for: Guessing and Forgetting: A Latent Class Model for Measuring Learning*
Abstract: Guessing on closed-ended knowledge items is common. Under likely to hold assumptions, in presence of guessing, the most common estimator of learning, difference between pre- and post-process scores, is negatively biased. To account for guessing related error, we develop a latent class model of how people respond to knowledge questions and identify the model with the mild assumption that people do not lose knowledge over short periods of time. A Monte Carlo simulation over a broad range of informative processes and knowledge items shows that the simple difference score is negatively biased and the method we develop here, unbiased. To demonstrate its use, we apply our model to data from Deliberative Polls. We find that estimates of learning once adjusted for guessing are about 13\% higher. Adjusting for guessing also eliminates the gender gap in learning, and halves the pre-deliberation gender gap on political knowledge.
Replicating Guessing and Forgetting
Download replication materials. Open the readme file and follow the specific instructions for how to replicate the results