6,523 research outputs found
Anti-Competitive Marketing Practices in the Airline Industry
Consumers, airlines and the economy as a whole have benefited from airline deregulation. Government regulation was replaced by competition as the protector of the consumers. Airlines continue to pursue marketing strategies which reduce competition and as act as barriers to new entrants. This paper reviews some of those strategies and suggest actions by which policy makers might encourage competition
Internalizing Symptoms as Predictors of School Absenteeism Severity at Multiple Levels: Ensemble and Classification and Regression Tree Analysis
School attendance problems are highly prevalent worldwide, leading researchers to investigate many different risk factors for this population. Of considerable controversy is how internalizing behavior problems might help to distinguish different types of youth with school attendance problems. In addition, efforts are ongoing to identify the point at which children and adolescents move from appropriate school attendance to problematic school absenteeism. The present study utilized ensemble and classification and regression tree analysis to identify potential internalizing behavior risk factors among youth at different levels of school absenteeism severity (i.e., 1+%, 3+%, 5+%, 10+%). Higher levels of absenteeism were also examined on an exploratory basis. Participants included 160 youth aged 6–19 years (M = 13.7; SD = 2.9) and their families from an outpatient therapy clinic (39.4%) and community (60.6%) setting, the latter from a family court and truancy diversion program cohort. One particular item relating to lack of enjoyment was most predictive of absenteeism severity at different levels, though not among the highest levels. Other internalizing items were also predictive of various levels of absenteeism severity, but only in a negatively endorsed fashion. Internalizing symptoms of worry and fatigue tended to be endorsed higher across less severe and more severe absenteeism severity levels. A general expectation that predictors would tend to be more homogeneous at higher than lower levels of absenteeism severity was not generally supported. The results help confirm the difficulty of conceptualizing this population based on forms of behavior but may support the need for early warning sign screening for youth at risk for school attendance problems
Statistics of the first passage time of Brownian motion conditioned by maximum value or area
We derive the moments of the first passage time for Brownian motion
conditioned by either the maximum value or the area swept out by the motion.
These quantities are the natural counterparts to the moments of the maximum
value and area of Brownian excursions of fixed duration, which we also derive
for completeness within the same mathematical framework. Various applications
are indicated.Comment: 29 pages, 4 figures include
The first-passage area for drifted Brownian motion and the moments of the Airy distribution
An exact expression for the distribution of the area swept out by a drifted
Brownian motion till its first-passage time is derived. A study of the
asymptotic behaviour confirms earlier conjectures and clarifies their range of
validity. The analysis also leads to a simple closed-form solution for the
moments of the Airy distribution.Comment: 13 page
Long- and short-time asymptotics of the first-passage time of the Ornstein-Uhlenbeck and other mean-reverting processes
The first-passage problem of the Ornstein-Uhlenbeck process to a boundary is
a long-standing problem with no known closed-form solution except in specific
cases. Taking this as a starting-point, and extending to a general
mean-reverting process, we investigate the long- and short-time asymptotics
using a combination of Hopf-Cole and Laplace transform techniques. As a result
we are able to give a single formula that is correct in both limits, as well as
being exact in certain special cases. We demonstrate the results using a
variety of other models
Higgs-photon resonances
We study models that produce a Higgs boson plus photon ()
resonance at the LHC. When the resonance is a boson, decays to occur at one loop. If the boson couples at tree-level to quarks,
then the branching fraction is typically of order or
smaller. Nevertheless, there are models that would allow the observation of at TeV with a cross section times branching
fraction larger than 1 fb for a mass in the 200--450 GeV range, and larger
than 0.1 fb for a mass up to 800 GeV. The 1-loop decay of the into lepton
pairs competes with , even if the couplings to leptons vanish
at tree level. We also present a model in which a boson decays into a
Higgs boson and a pair of collimated photons, mimicking an
resonance. In this model, the resonance search would be the
discovery mode for a as heavy as 2 TeV. When the resonance is a scalar,
although decay to is forbidden by angular momentum conservation,
the plus collimated photons channel is allowed. We comment on prospects
of observing an resonance through different Higgs decays, on
constraints from related searches, and on models where is replaced by a
nonstandard Higgs boson.Comment: 22 page
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