1,411 research outputs found
Whose absentee votes are returned and counted: The variety and use of absentee ballots in California
Absentee voting is becoming more prevalent throughout the United States. Although there has been some research focused on who votes by absentee ballot, little research has considered another important question about absentee voting: which absentee ballots are counted and which are not? Research in the wake of the 2000 presidential election has studied the problem of uncounted ballots for precinct voters but not for absentee voters. Using data from Los Angeles County – nation's largest and most diverse voting jurisdiction – for the November 2002 general election, we test a series of hypotheses that certain types of voters have a higher likelihood that their ballots will be counted. We find that uniform service personnel, overseas civilians, voters who request non-English ballots and permanent absentee voters have a much lower likelihood of returning their ballot, and once returned, a lower likelihood that their ballots will be counted compared with the general absentee voting population. We also find that there is little partisan effect as to which voters are more likely to return their ballots or have their ballots counted. We conclude our paper with a discussion of the implications of our research for the current debates about absentee voting
The Rise and Fall of Water Net (Hydrodictyon reticulatum) in New Zealand
During the late 1980s to early 1990s a range of aquatic habitats in the central North Island of New Zealand were invaded by the filamentous green alga, water net Hydrodictyon reticulatum (Linn. Lagerheim). The alga caused significant economic and recreational impacts at major sites of infestation, but it was also associated with enhanced invertebrate numbers and was the likely cause of an improvement in the trout fishery. The causes of prolific growth of water net and the range of control options pursued are reviewed. The possible causes of its sudden decline in 1995 are considered, including physical factors, increase in grazer pressure, disease, and loss of genetic vigour
Kernel density classification and boosting: an L2 sub analysis
Kernel density estimation is a commonly used approach to classification. However, most of the theoretical results for kernel methods apply to estimation per se and not necessarily to classification. In this paper we show that when estimating the difference between two densities, the optimal smoothing parameters are increasing functions of the sample size of the complementary group, and we provide a small simluation study which examines the relative performance of kernel density methods when the final goal is classification. A relative newcomer to the classification portfolio is “boosting”, and this paper proposes an algorithm for boosting kernel density classifiers. We note that boosting is closely linked to a previously proposed method of bias reduction in kernel density estimation and indicate how it will enjoy similar properties for classification. We show that boosting kernel classifiers reduces the bias whilst only slightly increasing the variance, with an overall reduction in error. Numerical examples and simulations are used to illustrate the findings, and we also suggest further areas of research
The Superpartner Spectrum of Gaugino Mediation
We compute the superpartner masses in a class of models with gaugino
mediation (or no-scale) boundary conditions at a scale between the GUT and
Planck scales. These models are compelling because they are simple, solve the
supersymmetric flavor and CP problems, satisfy all constraints from colliders
and cosmology, and predict the superpartner masses in terms of very few
parameters. Our analysis includes the renormalization group evolution of the
soft-breaking terms above the GUT scale. We show that the running above the GUT
scale is largely model independent and find that a phenomenologically viable
spectrum is obtained.Comment: 15 page
Rearranging Edgeworth-Cornish-Fisher Expansions
This paper applies a regularization procedure called increasing rearrangement
to monotonize Edgeworth and Cornish-Fisher expansions and any other related
approximations of distribution and quantile functions of sample statistics.
Besides satisfying the logical monotonicity, required of distribution and
quantile functions, the procedure often delivers strikingly better
approximations to the distribution and quantile functions of the sample mean
than the original Edgeworth-Cornish-Fisher expansions.Comment: 17 pages, 3 figure
A Complete Theory of Grand Unification in Five Dimensions
A fully realistic unified theory is constructed, with SU(5) gauge symmetry
and supersymmetry both broken by boundary conditions in a fifth dimension.
Despite the local explicit breaking of SU(5) at a boundary of the dimension,
the large size of the extra dimension allows precise predictions for gauge
coupling unification, alpha_s(M_Z) = 0.118 \pm 0.003, and for Yukawa coupling
unification, m_b(M_Z) = 3.3 \pm 0.2 GeV. A complete understanding of the MSSM
Higgs sector is given; with explanations for why the Higgs triplets are heavy,
why the Higgs doublets are protected from a large tree-level mass, and why the
mu and B parameters are naturally generated to be of order the SUSY breaking
scale. All sources of d=4,5 proton decay are forbidden, while a new origin for
d=6 proton decay is found to be important. Several aspects of flavor follow
from an essentially unique choice of matter location in the fifth dimension:
only the third generation has an SU(5) mass relation, and the lighter two
generations have small mixings with the heaviest generation. The entire
superpartner spectrum is predicted in terms of only two free parameters. The
squark and slepton masses are determined by their location in the fifth
dimension, allowing a significant experimental test of the detailed structure
of the extra dimension. Lepton flavor violation is found to be generically
large in higher dimensional unified theories with high mediation scales of SUSY
breaking. In our theory this forces a common location for all three neutrinos,
predicting large neutrino mixing angles. Rates for mu -> e gamma, mu -> e e e,
mu -> e conversion and tau -> mu gamma are larger in our theory than in
conventional 4D supersymmetric GUTs. Proposed experiments probing mu -> e
transitions will probe the entire interesting parameter space of our theory.Comment: 51 pages, late
Unifying flipped SU(5) in five dimensions
It is shown that embedding a four-dimensional flipped SU(5) model in a
five-dimensional SO(10) model, preserves the best features of both flipped
SU(5) and SO(10). The missing partner mechanism, which naturally achieves both
doublet-triplet splitting and suppression of d=5 proton decay operators, is
realized as in flipped SU(5), while the gauge couplings are unified as in
SO(10). The masses of down quarks and charged leptons, which are independent in
flipped SU(5), are related by the SO(10). Distinctive patterns of quark and
lepton masses can result. The gaugino mass M_1 is independent of M_3 and M_2,
which are predicted to be equal.Comment: revised version-to appear in PRD, 23 pages, 3 figures, ReVTeX
Constraints on R-parity violating supersymmetry from leptonic and semileptonic tau, B_d and B_s decays
We put constraints on several products of R-parity violating lambda lambda'
and lambda' lambda' type couplings from leptonic and semileptonic tau, B_d and
B_s decays. Most of them are one to two orders of magnitude better than the
existing bounds, and almost free from theoretical uncertainties. A significant
improvement of these bounds can be made in high luminosity tau-charm or B
factories.Comment: 14 pages, latex. A few references added, two typos corrected. Version
to be published in Physical Review
Family Unification on an Orbifold
We construct a family-unified model on a Z_2xZ_2 orbifold in five dimensions.
The model is based on a supersymmetric SU(7) gauge theory. The gauge group is
broken by orbifold boundary conditions to a product of grand unified SU(5) and
SU(2)xU(1) flavor symmetry. The structure of Yukawa matrices is generated by an
interplay between spontaneous breaking of flavor symmetry and geometric factors
arising due to field localization in the extra dimension.Comment: 13 page
Strongly Coupled Grand Unification in Higher Dimensions
We consider the scenario where all the couplings in the theory are strong at
the cut-off scale, in the context of higher dimensional grand unified field
theories where the unified gauge symmetry is broken by an orbifold
compactification. In this scenario, the non-calculable correction to gauge
unification from unknown ultraviolet physics is naturally suppressed by the
large volume of the extra dimension, and the threshold correction is dominated
by a calculable contribution from Kaluza-Klein towers that gives the values for
\sin^2\theta_w and \alpha_s in good agreement with low-energy data. The
threshold correction is reliably estimated despite the fact that the theory is
strongly coupled at the cut-off scale. A realistic 5d supersymmetric SU(5)
model is presented as an example, where rapid d=6 proton decay is avoided by
putting the first generation matter in the 5d bulk.Comment: 17 pages, latex, to appear in Phys. Rev.
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