6,355 research outputs found
Interpreting the time variable RM observed in the core region of the TeV blazar Mrk 421
In this work we interpret and discuss the time variable rotation measure (RM)
found, for the first time over a 1-yr period, in the core region of a blazar.
These results are based on a one-year, multi-frequency (15, 24, and 43 GHz)
Very Long Baseline Array (VLBA) monitoring of the TeV blazar Markarian 421 (Mrk
421). We investigate the Faraday screen properties and its location with
respect to the jet emitting region. Given that the 43 GHz radio core flux
density and the RM time evolution suggest a similar trend, we explore the
possible connection between the RM and the accretion rate. Among the various
scenarios that we explore, the jet sheath is the most promising candidate for
being the main source of Faraday rotation. During the one-year observing period
the RM trend shows two sign reversals, which may be qualitatively interpreted
within the context of the magnetic tower models. We invoke the presence of two
nested helical magnetic fields in the relativistic jet with opposite
helicities, whose relative contribution produce the observed RM values. The
inner helical field has the poloidal component () oriented in the
observer's direction and produces a positive RM, while the outer helical field,
with in the opposite direction, produces a negative RM. We assume
that the external helical field dominates the contribution to the observed RM,
while the internal helical field dominates when a jet perturbation arises
during the second observing epoch. Being the intrinsic polarization angle
parallel to the jet axis, a pitch angle of the helical magnetic field
is required. Additional scenarios are also considered to
explain the observed RM sign reversals.Comment: 6 pages, 2 figures. Published on MNRA
Risk factors associated with sudden death vs. congestive heart failure or arterial thromboembolism in cats with hypertrophic cardiomyopathy
AN ANALYSIS OF STRATEGIC AND PERFORMANCE CHANGES OF TRUCK CARRIERS IN THE AGRICULTURAL COMMODITY AND FOOD MARKETS
Agribusiness,
Multiple Object Tracking in Urban Traffic Scenes with a Multiclass Object Detector
Multiple object tracking (MOT) in urban traffic aims to produce the
trajectories of the different road users that move across the field of view
with different directions and speeds and that can have varying appearances and
sizes. Occlusions and interactions among the different objects are expected and
common due to the nature of urban road traffic. In this work, a tracking
framework employing classification label information from a deep learning
detection approach is used for associating the different objects, in addition
to object position and appearances. We want to investigate the performance of a
modern multiclass object detector for the MOT task in traffic scenes. Results
show that the object labels improve tracking performance, but that the output
of object detectors are not always reliable.Comment: 13th International Symposium on Visual Computing (ISVC
Management of incidentally detected heart murmurs in dogs and cats
A dog or a cat has an incidentally detected heart murmur if the murmur is an unexpected discovery during a veterinary consultation that was not initially focused on the cardiovascular system. This document presents approaches for managing dogs and cats that have incidentally-detected heart murmurs, with an emphasis on murmur characteristics, signalment profiling, and multifactorial decision-making to choose an optimal course for a given patient
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