3,598 research outputs found
Phase Transition in Heisenberg Stacked Triangular Antiferromagnets: End of a Controversy
By using the Wang-Landau flat-histogram Monte Carlo (MC) method for very
large lattice sizes never simulated before, we show that the phase transition
in the frustrated Heisenberg stacked triangular antiferromagnet is of
first-order, contrary to results of earlier MC simulations using old-fashioned
methods. Our result lends support to the conclusion of a nonperturbative
renormalization group performed on an effective Hamiltonian. It puts an end to
a 20-year long controversial issue.Comment: 4 pages, 7 figure
Differentially Private Publication of Sparse Data
The problem of privately releasing data is to provide a version of a dataset
without revealing sensitive information about the individuals who contribute to
the data. The model of differential privacy allows such private release while
providing strong guarantees on the output. A basic mechanism achieves
differential privacy by adding noise to the frequency counts in the contingency
tables (or, a subset of the count data cube) derived from the dataset. However,
when the dataset is sparse in its underlying space, as is the case for most
multi-attribute relations, then the effect of adding noise is to vastly
increase the size of the published data: it implicitly creates a huge number of
dummy data points to mask the true data, making it almost impossible to work
with.
We present techniques to overcome this roadblock and allow efficient private
release of sparse data, while maintaining the guarantees of differential
privacy. Our approach is to release a compact summary of the noisy data.
Generating the noisy data and then summarizing it would still be very costly,
so we show how to shortcut this step, and instead directly generate the summary
from the input data, without materializing the vast intermediate noisy data. We
instantiate this outline for a variety of sampling and filtering methods, and
show how to use the resulting summary for approximate, private, query
answering. Our experimental study shows that this is an effective, practical
solution, with comparable and occasionally improved utility over the costly
materialization approach
Effective Methods of Constituency Service in Oregon State
One would think that casework is the most effective method to reach constituents, however, that was not the case with this research about the Oregon State Legislature. Out of the 90 State Senators and House Representatives, there was a total of 50 surveys conducted and four interviews. The purpose of this research was to determine between casework, outreach and providing information, which method is deemed most effective within the Oregon Legislature when it comes to constituency service. Calculations show that third method, providing information, was the most effective with a solid 63%. These results shows that our legislator still lack in efforts with the other two main methods. There are certainly room for improvement when it comes to bettering the communication between constituents and legislators, even at the local level
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