1,790 research outputs found
The Impact of Exploring Computer Science in Wisconsin: Where Disadvantage is an Advantage
Assessing the impact of regional or statewide interventions in primary and secondary school (K-12) computer science (CS) education is difficult for a variety of reasons. Qualitative survey data provide only a limited view of impacts, but quantitative data can be notoriously difficult to acquire at scale from large numbers of classrooms, schools, or local educational authorities. In this paper, we use several publicly available data sources to glean insights into public high school CS enrollments across an entire U.S. state. Course enrollments with NCES course codes and local descriptors, school-level demographic data, and school geographic attendance boundaries can be combined to highlight where CS offerings persist and thrive, how CS enrollments change over time, and the ultimate quantitative impact of a statewide intervention. We propose a more appropriate level of data aggregation for these types of quantitative studies than has been undertaken in previous work while demonstrating the importance of a contextual aggregation process. The results of our disparate impact analysis for the first time quantify the impact of a statewide Exploring Computer Science (ECS) program rollout on economic groups across the region. Our blueprint for this analysis can serve as a template to guide and assess large-scale K-12 CS interventions wherever detailed project evaluation methods cannot scale to encompass the entire study area, especially in cases where attribute heterogeneity is a significant issue
Combinatorial nuclear level density by a Monte Carlo method
We present a new combinatorial method for the calculation of the nuclear
level density. It is based on a Monte Carlo technique, in order to avoid a
direct counting procedure which is generally impracticable for high-A nuclei.
The Monte Carlo simulation, making use of the Metropolis sampling scheme,
allows a computationally fast estimate of the level density for many fermion
systems in large shell model spaces. We emphasize the advantages of this Monte
Carlo approach, particularly concerning the prediction of the spin and parity
distributions of the excited states, and compare our results with those derived
from a traditional combinatorial or a statistical method. Such a Monte Carlo
technique seems very promising to determine accurate level densities in a large
energy range for nuclear reaction calculations.Comment: 30 pages, LaTex, 7 figures (6 Postscript figures included). Fig. 6
upon request to the autho
Gamow-Teller strength distributions for nuclei in pre-supernova stellar cores
Electron-capture and -decay of nuclei in the core of massive stars
play an important role in the stages leading to a type II supernova explosion.
Nuclei in the f-p shell are particularly important for these reactions in the
post Silicon-burning stage of a presupernova star. In this paper, we
characterise the energy distribution of the Gamow-Teller Giant Resonance (GTGR)
for mid-fp-shell nuclei in terms of a few shape parameters, using data obtained
from high energy, forward scattering (p,n) and (n,p) reactions. The energy of
the GTGR centroid is further generalised as function of nuclear
properties like mass number, isospin and other shell model properties of the
nucleus. Since a large fraction of the GT strength lies in the GTGR region, and
the GTGR is accessible for weak transitions taking place at energies relevant
to the cores of presupernova and collapsing stars, our results are relevant to
the study of important -capture and -decay rates of arbitrary,
neutron-rich, f-p shell nuclei in stellar cores. Using the observed GTGR and
Isobaric Analog States (IAS) energy systematics we compare the coupling
coefficients in the Bohr-Mottelson two particle interaction Hamiltonian for
different regions of the Isotope Table.Comment: Revtex, 28 pages +7 figures (PostScript Figures, uuencoded, filename:
Sutfigs.uu). If you have difficulty printing the figures, please contact
[email protected]. Accepted for publication in Phys. Rev. C, Nov 01,
199
On Two Models of the Light Pulse Delay in a Saturable Absorber
A comparative analysis of two approaches to description of the light
modulation pulse delay in a saturable absorber is presented. According to the
simplest model, the delay of the optical pulse is a result of distortion of its
shape due to absorption self-modulation in the nonlinear medium. The second
model of the effect, proposed at the beginning of our century, connects the
pulse delay with the so-called "slow light" resulting from the group velocity
reduction under conditions of the coherent population oscillations. It is shown
that all the known experimental data on the light pulse delay in saturable
absorbers can be comprehensively described in the framework of the simplest
model of saturable absorber and do not require invoking the effect of coherent
population oscillations with spectral hole-burning and anomalous modifications
of the light group velocity. It is concluded that the effect of group velocity
reduction under conditions of coherent population oscillations has not received
so far any experimental confirmation, and the assertions about real observation
of the "slow light" based on this mechanism are groundless.Comment: Regretfully, the journal version of the paper (in Optics and
Spectroscopy) appeared to be strongly corrupted due to ignorant editing. In
particular, "coherent population oscillations" (CPO) was replaced by
"population coherent oscillations" (PCO), "bleaching" - by "clearing", and
"bleachable absorber " - by "clearable absorber". Here we present original
version of the pape
Physician Compensation from Salary and Quality of Diabetes Care
OBJECTIVE: To examine the association between physician-reported percent of total compensation from salary and quality of diabetes care. DESIGN: Cross-sectional analysis. PARTICIPANTS: Physicians (n = 1248) and their patients with diabetes mellitus (n = 4200) enrolled in 10 managed care plans. MEASUREMENTS: We examined the associations between physician-reported percent compensation from salary and processes of care including receipt of dilated eye exams and foot exams, advice to take aspirin, influenza immunizations, and assessments of glycemic control, proteinuria, and lipid profile, intermediate outcomes such as adequate control of hemoglobin A1c, lipid levels, and systolic blood pressure levels, and satisfaction with provider communication and perceived difficulty getting needed care. We used hierarchical logistic regression models to adjust for clustering at the health plan and physician levels, as well as for physician and patient covariates. We adjusted for plan as a fixed effect, meaning we estimated variation between physicians using the variance within a particular health plan only, to minimize confounding by other unmeasured health plan variables. RESULTS: In unadjusted analyses, patients of physicians who reported higher percent compensation from salary (>90%) were more likely to receive 5 of 7 diabetes process measures and more intensive lipid management and to have an HbA1c<8.0% than patients of physicians who reported lower percent compensation from salary (<10%). However, these associations did not persist after adjustment. CONCLUSIONS: Our findings suggest that salary, as opposed to fee-for-service compensation, is not independently associated with diabetes processes and intermediate outcomes
Characteristics of transposable element exonization within human and mouse
Insertion of transposed elements within mammalian genes is thought to be an
important contributor to mammalian evolution and speciation. Insertion of
transposed elements into introns can lead to their activation as alternatively
spliced cassette exons, an event called exonization. Elucidation of the
evolutionary constraints that have shaped fixation of transposed elements
within human and mouse protein coding genes and subsequent exonization is
important for understanding of how the exonization process has affected
transcriptome and proteome complexities. Here we show that exonization of
transposed elements is biased towards the beginning of the coding sequence in
both human and mouse genes. Analysis of single nucleotide polymorphisms (SNPs)
revealed that exonization of transposed elements can be population-specific,
implying that exonizations may enhance divergence and lead to speciation. SNP
density analysis revealed differences between Alu and other transposed
elements. Finally, we identified cases of primate-specific Alu elements that
depend on RNA editing for their exonization. These results shed light on TE
fixation and the exonization process within human and mouse genes.Comment: 11 pages, 4 figure
Superior canal dehiscence in a patient with three failed stapedectomy operations for otosclerosis: a case report
<p>Abstract</p> <p>Introduction</p> <p>This case illustrates that superior semicircular canal dehiscence syndrome can be associated with a "pseudo"-conductive hearing loss, a symptom that overlaps with the clinical appearance of otosclerosis.</p> <p>Case presentation</p> <p>We present the case of a 48-year-old German Caucasian woman presenting with hearing loss on the left side and vertigo. She had undergone three previous stapedectomies for hearing improvement. Reformatted high-resolution computed tomographic scanning and the patient's history confirmed the diagnosis of concurrent canal dehiscence syndrome.</p> <p>Conclusion</p> <p>Failure of hearing improvement after otosclerosis surgery may indicate an alternative underlying diagnosis which should be explored by further appropriate evaluation.</p
Modeling resilience and sustainability in ancient agricultural systems
The reasons why people adopt unsustainable agricultural practices, and the ultimate environmental implications of those practices, remain incompletely understood in the present world. Archaeology, however, offers unique datasets on coincident cultural and ecological change, and their social and environmental effects. This article applies concepts derived from ecological resilience thinking to assess the sustainability of agricultural practices as a result of long-term interactions between political, economic, and environmental systems. Using the urban center of Gordion, in central Turkey, as a case study, it is possible to identify mismatched social and ecological processes on temporal, spatial, and organizational scales, which help to resolve thresholds of resilience. Results of this analysis implicate temporal and spatial mismatches as a cause for local environmental degradation, and increasing extralocal economic pressures as an ultimate cause for the adoption of unsustainable land-use practices. This analysis suggests that a research approach that integrates environmental archaeology with a resilience perspective has considerable potential for explicating regional patterns of agricultural change and environmental degradation in the past
- …