2,264 research outputs found
Studying patterns of use of transport modes through data mining - Application to U.S. national household travel survey data set
Data collection activities related to travel require large amounts of financial and human resources to be conducted successfully. When available resources are scarce, the information hidden in these data sets needs to be exploited, both to increase their added value and to gain support among decision makers not to discontinue such efforts. This study assessed the use of a data mining technique, association analysis, to understand better the patterns of mode use from the 2009 U.S. National Household Travel Survey. Only variables related to self-reported levels of use of the different transportation means are considered, along with those useful to the socioeconomic characterization of the respondents. Association rules potentially showed a substitution effect between cars and public transportation, in economic terms but such an effect was not observed between public transportation and nonmotorized modes (e.g., bicycling and walking). This effect was a policy-relevant finding, because transit marketing should be targeted to car drivers rather than to bikers or walkers for real improvement in the environmental performance of any transportation system. Given the competitive advantage of private modes extensively discussed in the literature, modal diversion from car to transit is seldom observed in practice. However, after such a factor was controlled, the results suggest that modal diversion should mainly occur from cars to transit rather than from nonmotorized modes to transi
Light dark forces at flavor factories
SuperB experiment could represent an ideal environment to test a new U (1)
symmetry related to light dark forces candidates. A promising discovery channel
is represented by the resonant production of a boson U, followed by its decay
into lepton pairs. Beyond approximations adopted in the literature, an exact
tree level calculation of the radiative processes and corresponding QED
backgrounds is performed, including also the most important higher-order
corrections. The calculation is implemented in a release of the generator
BabaYaga@NLO useful for data analysis and interpretation. The distinct features
of U boson production are shown and the statistical significance is analysed
On the Lack of Correlation Between [OIII]/[OII] and Lyman-Continuum Escape Fraction
We present the first results of our pilot study of 8 photometrically selected
Lyman continuum (LyC) emitting galaxy candidates from the COSMOS field and
focus on their optical emission line ratios. Observations were performed in the
H and K bands using the Multi-Object Spectrometer for Infra-Red Exploration
(MOSFIRE) instrument at the Keck Observatory, targeting the [OII], H,
and [OIII] emission lines. We find that photometrically selected LyC emitting
galaxy candidates have high ionization parameters, based on their high
[OIII]/[OII] ratios (O32), with an average ratio for our sample of 2.50.2.
Preliminary results of our companion Low Resolution Imaging Spectrometer (LRIS)
observations, targeting LyC and Ly, show that those galaxies with the
largest O32 are typically found to also be Ly emitters. High O32
galaxies are also found to have tentative non-zero LyC escape fractions
() based on band photometric detections. These results are
consistent with samples of highly ionized galaxies, including confirmed LyC
emitting galaxies from the literature. We also perform a detailed comparison
between the observed emission line ratios and simulated line ratios from
density bounded H regions modeled using the photoionization
code MAPPINGS V. Estimates of for our sample fall in the range
from 0.0-0.23 and suggest possible tension with published correlations between
O32 and , adding weight to dichotomy of arguments in the
literature. We highlight the possible effects of clumpy geometry and mergers
that may account for such tension.Comment: 21 pages, 11 figures, 3 tables, accepted for publication in MNRA
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Investigations into insect vectoring of Fusarium poae in bluegrass seed crops
Evidence for CP Violation in B0 -> D+D- Decays
We report measurements of the branching fraction and CP violation parameters
in B0 -> D+D- decays. The results are based on a data sample that contains 535
x 10^6 BBbar pairs collected at the Upsilon(4S) resonance, with the Belle
detector at the KEKB asymmetric-energy e+e- collider. We obtain [1.97 +- 0.20
(stat) +- 0.20 (syst)] x 10^(-4) for the branching fraction of B0 -> D+D-. The
measured values of the CP violation parameters are: S = -1.13 +- 0.37 +- 0.09,
A = 0.91 +- 0.23 +- 0.06, where the first error is statistical and the second
is systematic. We find evidence of CP violation in B0 -> D+D- at the 4.1 sigma
confidence level. While the value of S is consistent with expectations from
other measurements, the value of the parameter A favors large direct CP
violation at the 3.2 sigma confidence level, in contradiction to Standard Model
expectations.Comment: 12 pages, 3 figures, submitted to PR
Study of B -> \rho \pi decays at Belle
This paper describes a study of B meson decays to the pseudoscalar-vector
final state \rho\pi using 31.9\times 10^6 B\bar{B} events collected with the
Belle detector at KEKB. The branching fractions B(B^+ \to \rho^0\pi^+) =
(8.0^{+2.3+0.7}_{-2.0-0.7}) \times 10^{-6} and B(B^0 -> \rho^{+-} \pi^{-+}) =
(20.8^{+6.0+2.8}_{-6.3-3.1}) \times 10^{-6} are obtained. In addition, a 90%
confidence level upper limit of B(B^0 \to \rho^0\pi^0) < 5.3 \times 10^{-6}is
reported.Comment: 14 pages, 3 figures, to be submitted to Phys. Lett.
Measurements of Branching Fractions and Polarization in B > K^* rho Decays
We present results of a study of the charmless vector-vector decays B^0 ->
K^{*0} rho^0 and B^+ ->K^{*0} rho^+. The results are based on a 140 fb^{-1}
data sample collected by the Belle detector at the KEKB asymmetric e^+e^-
collider. We obtain the branching fraction B(B^+ -> K^{*0} rho^+)=(6.6 +-
2.2(stat.) +- 0.8 (syst.)) x 10^{-6}, and set upper limits on the branching
fractions B(B^0 -> K^{*0} rho^0) f_0(980)
K^{*0})<5.2 x 10^{-6}. We also perform a helicity analysis of the rho and K^*
vector mesons in the decay B^+ -> K^{*0} rho^+, and obtain the longitudinal
polarization fraction R_0(B^+ -> K^{*0} rho^+)=0.50 +-
0.19(stat.)+0.05-0.07}(syst.).Comment: 11 pages, 4 figures, submitted to ICHEP04, Beijing, Chin
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