6,185 research outputs found
A Comparison of the Michigan and Fair Models: Further Results
This paper examines the equation-by-equation accuracy of the Michigan and Fair model using the method in Fair (1980). Emphasis is placed on examining the possible misspeciļ¬cation of the equations. In an earlier study, Fair and Alexander (1984), we used the method to examine the accuracy of the complete models. In the present study we are interested in the accuracy of the individual equations when considered in isolation from the rest of the model
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A multiregion assessment of observed changes in the areal extent of temperature and precipitation extremes
This study examines trends in the area affected by temperature and precipitation extremes across five large-scale regions using the climate extremes index (CEI) framework. Analyzing changes in temperature and precipitation extremes in terms of areal fraction provides information from a different perspective and can be useful for climate monitoring. Trends in five temperature and precipitation components are analyzed, calculated using a new method based on standard extreme indices. These indices, derived from daily meteorological station data, are obtained from two global land-based gridded extreme indices datasets. The four continental-scale regions of Europe, North America, Asia, and Australia are analyzed over the period from 1951 to 2010, where sufficient data coverage is available. These components are also computed for the entire Northern Hemisphere, providing the first CEI results at the hemispheric scale. Results show statistically significant increases in the percentage area experiencing much-above-average warm days and nights and much-below-average cool days and nights for all regions, with the exception of North America for maximum temperature extremes. Increases in the area affected by precipitation extremes are also found for the Northern Hemisphere regions, particularly Europe and North America
Computer-Assisted Decision Support for Student Admissions Based on Their Predicted Academic Performance
Objective. To develop predictive computational models forecasting the academic performance of students in the didactic-rich portion of a doctor of pharmacy (PharmD) curriculum as admission-assisting tools
Sparsity based sub-wavelength imaging with partially incoherent light via quadratic compressed sensing
We demonstrate that sub-wavelength optical images borne on
partially-spatially-incoherent light can be recovered, from their far-field or
from the blurred image, given the prior knowledge that the image is sparse, and
only that. The reconstruction method relies on the recently demonstrated
sparsity-based sub-wavelength imaging. However, for
partially-spatially-incoherent light, the relation between the measurements and
the image is quadratic, yielding non-convex measurement equations that do not
conform to previously used techniques. Consequently, we demonstrate new
algorithmic methodology, referred to as quadratic compressed sensing, which can
be applied to a range of other problems involving information recovery from
partial correlation measurements, including when the correlation function has
local dependencies. Specifically for microscopy, this method can be readily
extended to white light microscopes with the additional knowledge of the light
source spectrum.Comment: 16 page
Unifying Approaches to Chiral Bosons
Chiral bosons, or self-dual p-form fields, are ubiquitous in string theoretic
contexts but are challenging to treat. Lagrangian constructions invariably
introduce a complexity be it auxiliary fields or sacrificing Lorentz
invariance. In this note we show how to pass between such different approaches
to chiral bosons starting from a Chern Simons point of view to recover
formulations of Pasti, Sorokin and Tonin and of Mkrtchyan. This leads to a
novel generalisation of the latter to include non-Abelian chiral bosons in
2-dimensions, and generalisations to include twisted self-duality which are
relevant in T-duality symmetric approaches to string theory. Our approach also
shows how global affine symmetries of two- and higher-dimensional chiral bosons
emerge from broken Chern-Simons gauge transformations on the boundary.Comment: 22 page
Effects of a mandatory safety belt law on hospital admissions
Although the effectiveness of automobile safety belts in reducing risk of serious injury in traffic crashes is well documented, safety belt use in many U.S. jurisdictions remains low. Michigan's mandatory safety belt law for front-seat occupants, implemented in July 1985, is one of 34 similar laws in the United States intended to increase belt use and reduce crash-related injuries. Using time-series intervention analyses of data from 14 hospitals throughout the state, we found a 19% reduction in the rate of admitted patients for all automobile occupant injuries and a 20% reduction in the rate of admitted patients with extremity injuries following implementation of the safety belt law. The utility of hospital data for the evaluation of interventions like the safety belt law reinforce the importance of consistently recording E-codes for all injury patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/28539/1/0000337.pd
A Comparison of the Michigan and Fair Models: Further Results
This paper examines the equation-by-equation accuracy of the Michigan and Fair model using the method in Fair (1980). Emphasis is placed on examining the possible misspecification of the equations. In an earlier study, Fair and Alexander (1984), we used the method to examine the accuracy of the complete models. In the present study we are interested in the accuracy of the individual equations when considered in isolation from the rest of the model.
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A multiregion model evaluation and attribution study of historical changes in the area affected by temperature and precipitation extremes
The skill of eight climate models in simulating the variability and trends in the observed areal extent of daily temperature and precipitation extremes is evaluated across five large-scale regions, using the climate extremes index (CEI) framework. Focusing on Europe, North America, Asia, Australia, and the Northern Hemisphere, results show that overall the models are generally able to simulate the decadal variability and trends of the observed temperature and precipitation components over the period 1951ā2005. Climate models are able to reproduce observed increasing trends in the area experiencing warm maximum and minimum temperature extremes, as well as, to a lesser extent, increasing trends in the areas experiencing an extreme contribution of heavy precipitation to total annual precipitation for the Northern Hemisphere regions. Using simulations performed under different radiative forcing scenarios, the causes of simulated and observed trends are investigated. A clear anthropogenic signal is found in the trends in the maximum and minimum temperature components for all regions. In North America, a strong anthropogenically forced trend in the maximum temperature component is simulated despite no significant trend in the gridded observations, although a trend is detected in a reanalysis product. A distinct anthropogenic influence is also found for trends in the area affected by a much-above-average contribution of heavy precipitation to annual precipitation totals for Europe in a majority of models and to varying degrees in other Northern Hemisphere regions. However, observed trends in the area experiencing extreme total annual precipitation and extreme number of wet and dry days are not reproduced by climate models under any forcing scenario
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