6,676 research outputs found
Effect of Mitigation Measures on the Spreading of COVID-19 in Hard-Hit States
State government-mandated social distancing measures have helped to slow down
the growth of the COVID-19 pandemic in the United States. Current predictive
models of the development of COVID-19, especially after mitigation efforts, are
largely based on extrapolating the data from other countries. Since most states
enforced stay-at-home orders towards the end of March, their effect should be
reflected in the death and infection counts at the end of April. Using the data
available until April 25th, we investigate the change in the infection rate due
to the mitigation efforts, and project death and infection counts until
September, 2020, for some of the most heavily impacted states: New York, New
Jersey, Michigan, Massachusetts, Illinois and Louisiana. We find that with the
current mitigation efforts five of those six states reduce their reproduction
number to a value less than one, stopping the exponential growth of the
pandemic. We also projected different scenarios after the mitigation is
relaxed. Analysis for other states can be found at
https://covid19projection.org/.Comment: 8 pages, 6 figures, 2 table
Identifying structural changes with unsupervised machine learning methods
Unsupervised machine learning methods are used to identify structural changes
using the melting point transition in classical molecular dynamics simulations
as an example application of the approach. Dimensionality reduction and
clustering methods are applied to instantaneous radial distributions of atomic
configurations from classical molecular dynamics simulations of metallic
systems over a large temperature range. Principal component analysis is used to
dramatically reduce the dimensionality of the feature space across the samples
using an orthogonal linear transformation that preserves the statistical
variance of the data under the condition that the new feature space is linearly
independent. From there, k-means clustering is used to partition the samples
into solid and liquid phases through a criterion motivated by the geometry of
the reduced feature space of the samples, allowing for an estimation of the
melting point transition. This pattern criterion is conceptually similar to how
humans interpret the data but with far greater throughput, as the shapes of the
radial distributions are different for each phase and easily distinguishable by
humans. The transition temperature estimates derived from this machine learning
approach produce comparable results to other methods on similarly small system
sizes. These results show that machine learning approaches can be applied to
structural changes in physical systems
The CTIO Prime Focus CCD: System Characteristics from 1982-1988
The CTIO Prime Focus CCD instrument with an RCA CCD was in operation at the
CTIO 4-m telescope for six years between 1982-1988. A large body of literature
has been published based on CCD images taken with this instrument. We review
the general properties of the now-retired PFCCD system to aid astronomers in
the interpretation of the photometric data in the literature.Comment: Accepted for publication in the PASP. 15 pages, AASTeX V4.0 latex
format (including figures), 4 ps figures, 4 separate AASTeX V4.0 latex table
The Skills to Pay the Bills: An Evaluation of an Effort to Help Nonprofits Manage Their Finances
This study examines a Wallace Foundation-sponsored initiative aimed at improving the financial management skills and practices of 25 Chicago afterschool providers through training and coaching. Two models for this professional development were provided and each produced long-lasting improvements. Moreover, organizations receiving the less-expensive group training and coaching improved almost as much as those receiving more intensive customized coaching
Tidal Stresses and Energy Gaps in Microstate Geometries
We compute energy gaps and study infalling massive geodesic probes in the new
families of scaling, microstate geometries that have been constructed recently
and for which the holographic duals are known. We find that in the deepest
geometries, which have the lowest energy gaps, the geodesic deviation shows
that the stress reaches the Planck scale long before the probe reaches the cap
of the geometry. Such probes must therefore undergo a stringy transition as
they fall into microstate geometry. We discuss the scales associated with this
transition and comment on the implications for scrambling in microstate
geometries.Comment: 22 pages, 1 figur
Correlation between prescribing quality and pharmaceutical costs in English primary care: national cross-sectional analysis
Background Both pharmaceutical costs and quality-indicator performance vary substantially between general practices, but little is known about the relationship between prescribing costs and quality Aim To measure the association between prescribing quality and pharmaceutical costs among English general practices Design and setting Cross-sectional observational study using data from the Quality and Outcomes Framework and the Prescribing Analysis and Cost database from all 8409 general practices in England in 2005-2006 Method Correlation between practice achievement of 26 prescribing quality indicators in eight prescribing areas and related pharmaceutical costs was examined. Results There was no significant association between the overall achievement of quality indicators and related pharmaceutical costs (P= 0.399). Mean achievement of quality indicators across all eight prescribing areas was 79.0% (standard deviation 4.4%). There were small positive correlations in five prescribing areas: influenza vaccination, beta blockers, angiotensin converting enzyme inhibitors, lipid lowering, and antiplatelet treatment (all
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