648 research outputs found
Comparison of the Accuracy of Traffic Counting Devices
Traffic counting devices are commonly used by governmental agencies and private companies in order to assess traffic patterns and the level of occupancy of roadway networks. The data provided by these devices normally encompasses traffic volumes, vehicle classes and vehicle speeds, and are used by traffic engineers in the planning, design and operations of transportation systems. An evaluation of the accuracy of these devices is of great importance because traffic management decisions are compromised without qualified data. This research evaluated the performance of two different models of traffic counters, Jamar Technologiesâ Radar Recorder and Vaisalaâs Traffic Analyzer NC-200, both commonly used by the Indiana Local Technical Assistance Program in data collection for local agencies. These devices were installed for eight counts at seven different road segments under various traffic conditions. The accuracy of each device was assessed by comparing its readings to hand-count data also taken at each location. Results suggest that these devices have a high level of accuracy when measuring traffic volumes and vehicle speeds, with errors usually below 15% for volumes and below 10% for speeds. However, both devices failed to provide satisfactory results in terms of vehicle classification, with significant truck detection errors in 4 out of 8 counts for each model. The findings of this research will be helpful for local transportation agencies in the management of their traffic data in order to assure safe and informed decisions about their transportation network
Density perturbations in an Universe dominated by the Chaplygin gas
We study the fate of density perturbations in an Universe dominate by the
Chaplygin gas, which exhibit negative pressure. We show that it is possible to
obtain the value for the density contrast observed in large scale structure of
the Universe by fixing a free parameter in the equation of state of this gas.
The negative character of pressure must be significant only very recently.Comment: Latex file, 5 page
On the equivalence between Implicit Regularization and Constrained Differential Renormalization
Constrained Differential Renormalization (CDR) and the constrained version of
Implicit Regularization (IR) are two regularization independent techniques that
do not rely on dimensional continuation of the space-time. These two methods
which have rather distinct basis have been successfully applied to several
calculations which show that they can be trusted as practical, symmetry
invariant frameworks (gauge and supersymmetry included) in perturbative
computations even beyond one-loop order.
In this paper, we show the equivalence between these two methods at one-loop
order. We show that the configuration space rules of CDR can be mapped into the
momentum space procedures of Implicit Regularization, the major principle
behind this equivalence being the extension of the properties of regular
distributions to the regularized ones.Comment: 16 page
Climate Indicators and the Impact on Morbidity and Mortality of Acute Respiratory Infections
The fire incidences in Campo Grande have been a serious environmental problem. Therefore, this study is aimed at studying the trend of acute respiratory infections (IRA) from the year 2011 to 2017 and to correlate it with precipitation, wind speed, relative humidity, maximum and minimum temperatures, surface ozone concentration, optical depth, index of clarity and the number of outbreaks of fires. IRA records were obtained through DATASUS; the record of burn outbreaks at the National Institute for Space Research and the ozone concentration at the Federal University of Mato Grosso do Sul. There exists a positive and significant correlation between the number of burn outbreaks, wind velocity, ozone concentration, and optical depth with rates of hospitalizations for IRA. Also, a negative correlation exists between precipitation parameters, relative humidity, maximum and minimum temperatures. These results show the intensity of the problem and the great impact on the respiratory health of the population as well as on the economy due to increase in the number of hospitalizations and days of treatment
Search for a W' boson decaying to a bottom quark and a top quark in pp collisions at sqrt(s) = 7 TeV
Results are presented from a search for a W' boson using a dataset
corresponding to 5.0 inverse femtobarns of integrated luminosity collected
during 2011 by the CMS experiment at the LHC in pp collisions at sqrt(s)=7 TeV.
The W' boson is modeled as a heavy W boson, but different scenarios for the
couplings to fermions are considered, involving both left-handed and
right-handed chiral projections of the fermions, as well as an arbitrary
mixture of the two. The search is performed in the decay channel W' to t b,
leading to a final state signature with a single lepton (e, mu), missing
transverse energy, and jets, at least one of which is tagged as a b-jet. A W'
boson that couples to fermions with the same coupling constant as the W, but to
the right-handed rather than left-handed chiral projections, is excluded for
masses below 1.85 TeV at the 95% confidence level. For the first time using LHC
data, constraints on the W' gauge coupling for a set of left- and right-handed
coupling combinations have been placed. These results represent a significant
improvement over previously published limits.Comment: Submitted to Physics Letters B. Replaced with version publishe
Search for the standard model Higgs boson decaying into two photons in pp collisions at sqrt(s)=7 TeV
A search for a Higgs boson decaying into two photons is described. The
analysis is performed using a dataset recorded by the CMS experiment at the LHC
from pp collisions at a centre-of-mass energy of 7 TeV, which corresponds to an
integrated luminosity of 4.8 inverse femtobarns. Limits are set on the cross
section of the standard model Higgs boson decaying to two photons. The expected
exclusion limit at 95% confidence level is between 1.4 and 2.4 times the
standard model cross section in the mass range between 110 and 150 GeV. The
analysis of the data excludes, at 95% confidence level, the standard model
Higgs boson decaying into two photons in the mass range 128 to 132 GeV. The
largest excess of events above the expected standard model background is
observed for a Higgs boson mass hypothesis of 124 GeV with a local significance
of 3.1 sigma. The global significance of observing an excess with a local
significance greater than 3.1 sigma anywhere in the search range 110-150 GeV is
estimated to be 1.8 sigma. More data are required to ascertain the origin of
this excess.Comment: Submitted to Physics Letters
Measurement of the Lambda(b) cross section and the anti-Lambda(b) to Lambda(b) ratio with Lambda(b) to J/Psi Lambda decays in pp collisions at sqrt(s) = 7 TeV
The Lambda(b) differential production cross section and the cross section
ratio anti-Lambda(b)/Lambda(b) are measured as functions of transverse momentum
pt(Lambda(b)) and rapidity abs(y(Lambda(b))) in pp collisions at sqrt(s) = 7
TeV using data collected by the CMS experiment at the LHC. The measurements are
based on Lambda(b) decays reconstructed in the exclusive final state J/Psi
Lambda, with the subsequent decays J/Psi to an opposite-sign muon pair and
Lambda to proton pion, using a data sample corresponding to an integrated
luminosity of 1.9 inverse femtobarns. The product of the cross section times
the branching ratio for Lambda(b) to J/Psi Lambda versus pt(Lambda(b)) falls
faster than that of b mesons. The measured value of the cross section times the
branching ratio for pt(Lambda(b)) > 10 GeV and abs(y(Lambda(b))) < 2.0 is 1.06
+/- 0.06 +/- 0.12 nb, and the integrated cross section ratio for
anti-Lambda(b)/Lambda(b) is 1.02 +/- 0.07 +/- 0.09, where the uncertainties are
statistical and systematic, respectively.Comment: Submitted to Physics Letters
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