5,555 research outputs found
A First Map of the CMB at 0.5Deg Resolution
We use a Maximum Entropy technique to reconstruct a map of the microwave sky
near the star Gamma Ursae Minoris, based on data from flights 2, 3 and 4 of the
Millimeter-wave Anisotropy eXperiment (MAX).Comment: 5 pages plus 3 postscript figures, uuencoded compressed postscript,
CfPA-94-TH-5
Detailed Simulation of the Cochlea: Recent Progress Using Large Shared Memory Parallel Computers
We have developed and are refining a detailed three-dimensional computational model of the human cochlea. The model uses the immersed boundary method to calculate the fluid-structure interactions produced in response to incoming sound waves. An accurate cochlear geometry obtained from physical measurements is incorporated. The model includes a detailed and realistic description of the various elastic structures present. Initially, a macro-mechanical computational model was developed for execution on a CRAY T90 at the San Diego Supercomputing Center. This code was ported to the latest generation of shared memory high performance servers from Hewlett Packard. Using compiler generated threads and OpenMP directives, we have achieved a high degree of parallelism in the executable, which has made possible to run several large scale numerical simulation experiments to study the interesting features of the cochlear system. In this paper, we outline the methods, algorithms and software tools that were used to implement and fine tune the code, and discuss some of the simulation results
Evolution and Earth's Entropy
Entropy decreases on the Earth due to day/night temperature differences. This
decrease exceeds the decrease in entropy on the Earth related to evolution by
many orders of magnitude. Claims by creationists that science is somehow
inconsistent with regard to evolution are thus show to be baseless.Comment: 2 page
The COBE Normalization for Standard CDM
The COBE detection of CMB anisotropies provides the best way of fixing the
amplitude of fluctuations on the largest scales. This normalization is usually
given for an n=1 spectrum, including only the anisotropy caused by the Sachs-
Wolfe effect. This is certainly not a good approximation for a model containing
any reasonable amount of baryonic matter. In fact, even tilted S-W spectra are
not a good fit to models like CDM. Here we normalize standard CDM (sCDM) to the
2-year COBE data, and quote the best amplitude in terms of the conventionally
used measures of power. We also give normalizations for some specific variants
of this standard model, and we indicate how the normalization depends on the
assumed values of n, Omega_B and H_0. For sCDM we find =19.9\pm1.5uK,
corresponding to sigma_8=1.34\pm0.10, with the normalization at large scales
being B=(8.16\pm1.04)\times10^5 (Mpc/h)^4, and other numbers given in the
Table. The measured rms temperature fluctuation smoothed on 10deg is a little
low relative to this normalization. This is mainly due to the low quadrupole in
the data: when the quadrupole is removed, the measured value of sigma(10) is
quite consistent with the best-fitting . The use of should be preferred
over sigma(10), when its value can be determined for a particular theory, since
it makes full use of the data.Comment: 4 pages compressed uuencoded postscript. We have corrected an error
in our analysi
Bridging Policy and Education: How Elementary Students Are Impacted by Reform Efforts
This study focuses on how state policies that encourage school reform impact student experience. The paper demonstrates what students in these reformed schools experience and what lessons we can learn from their experiences. In particular, the research focuses on engagement levels and the matching of intentions to student propensities. A goal of the paper is to help bridge the policy and educational worlds by shedding light on what is happening in four school-of-choice classrooms.
A mixed methodology is used; data from an Educational Connoisseurship and Criticism, an engagement measure, and interviews are triangulated. The research was conducted at two school-of-choice schools located in the Denver Metro area. The Expeditionary Learning school is a K-12 school and the Core Knowledge school is a K-8 school.
The study found high levels of engagement and learning in schools of choice where propensities and interest are matched to the five dimensions of a classroom: pedagogy, curriculum, evaluation, structure, and intentions.
Several themes emerged from the research. The first is that students and teachers at both schools had learning propensities and philosophies that were aligned with the intentions of the schools. This alignment helped create a strong community. The second theme is that interest is an important element of student learning and engagement. The third theme is that having a clear mission and intentions improves learning. Fourth, engagement is an important indicator of school success and high levels of engagement should continue to be a goal for schools to meet. I found that engagement is high in the two schools and reflected what was taking place in the classroom. The fifth and final theme is that students have different learning needs, and thus flexible state policies should allow for more variability to allow for a wider range of learning needs to be met.
Data indicate that when the five elements of schooling match the students\u27 propensities, they are interested and engaged in the learning process. It is, therefore, important to create flexible state policies that allow more schools of choice to be created
Art Corner: A Glimpse of Discernment and A Thousand Blessings
Bradley E. Bunn, a self-taught artist living and working in Mid-Michigan, reveals the nature of resiliency found in adolescence through his artwork in this issue. His work captures the glimmers of hopeful expectancy found within the many faces of youth who have crossed his path over the years
Bandwidth in bolometric interferometry
Bolometric Interferometry is a technology currently under development that
will be first dedicated to the detection of B-mode polarization fluctuations in
the Cosmic Microwave Background. A bolometric interferometer will have to take
advantage of the wide spectral detection band of its bolometers in order to be
competitive with imaging experiments. A crucial concern is that interferometers
are presumed to be importantly affected by a spoiling effect known as bandwidth
smearing. In this paper, we investigate how the bandwidth modifies the work
principle of a bolometric interferometer and how it affects its sensitivity to
the CMB angular power spectra. We obtain analytical expressions for the
broadband visibilities measured by broadband heterodyne and bolometric
interferometers. We investigate how the visibilities must be reconstructed in a
broadband bolometric interferometer and show that this critically depends on
hardware properties of the modulation phase shifters. Using an angular power
spectrum estimator accounting for the bandwidth, we finally calculate the
sensitivity of a broadband bolometric interferometer. A numerical simulation
has been performed and confirms the analytical results. We conclude (i) that
broadband bolometric interferometers allow broadband visibilities to be
reconstructed whatever the kind of phase shifters used and (ii) that for
dedicated B-mode bolometric interferometers, the sensitivity loss due to
bandwidth smearing is quite acceptable, even for wideband instruments (a factor
2 loss for a typical 20% bandwidth experiment).Comment: 13 pages, 14 figures, submitted to A&
The Wellbeing Toolkit Training Programme: A Useful Resource for Educational Psychology Services?
Background. Supporting pupils’ social, emotional, and mental health (SEMH) development is a task that schools are expected to undertake in England, yet many staff members find it challenging due to their belief that they don’t possess the necessary skills.
Objective. To evaluate a commercially available, training resource, The Emotional Wellbeing Toolkit, aimed at raising the skills of adults working with children in the SEMH area. Design. The Toolkit was adapted and used as training material by a professional team comprised of educational psychologists, clinical psychologists, and specialist teachers, for schools within an eastern region in England. A mixed methodology was employed to evaluate the usefulness of the Toolkit as a training resource, as well as its perceived effectiveness in raising the skills of school professionals working within the SEMH area. Qualitative as well as quantitative data was gathered from the two groups participating in training, as school staff delegates, and as facilitators of training delivery. Descriptive statistics and content analysis were used for data analysis.
Results. The findings suggest evidence of improved skills and knowledge in the area of SEMH, with some specific impact on delegates’ practice. Implications for practice are discussed
Observational tests of one-bubble open inflationary cosmological models
Motivated by recent studies of the one-bubble inflationary scenario, simple open cold dark matter models are tested for consistency with cosmological observations. The initial perturbation spectrum is derived by solving for the evolution of fluctuations in an open inflationary stage. A likelihood analysis is performed for the Cosmic Microwave Background anisotropies using the two-year COBE DMR data and considering models based on both the Bunch-Davies and conformal vacua. Having normalized the perturbation spectrum to fit the COBE data, we reconsider the validity of the open model from the view point of cosmic structure formation. Open models may be severely constrained by the COBE likelihood analysis. In particular, small values of \Omega_0 are ruled out in the Bunch-Davies case: we find that \Omega_0\ge 0.34 at 95\% confidence for this model
Forecasting the intra-day spread densities of electricity prices
Intra-day price spreads are of interest to electricity traders, storage and electric vehicle operators. This paper formulates dynamic density functions, based upon skewed-t and similar representations, to model and forecast the German electricity price spreads between different hours of the day, as revealed in the day-ahead auctions. The four specifications of the density functions are dynamic and conditional upon exogenous drivers, thereby permitting the location, scale and shape parameters of the densities to respond hourly to such factors as weather and demand forecasts. The best fitting and forecasting specifications for each spread are selected based on the Pinball Loss function, following the closed form analytical solutions of the cumulative distribution functions
- …