436 research outputs found
Gas Dynamics in the Barred Seyfert Galaxy NGC4151 - II. High Resolution HI Study
We present sensitive, high angular resolution (6" x 5") 21-cm observations of
the neutral hydrogen in the nearby barred Seyfert galaxy, NGC4151. These HI
observations, obtained using the VLA in B-configuration, are the highest
resolution to date of this galaxy, and reveal hitherto unprecedented detail in
the distribution and kinematics of the HI on sub-kiloparsec scales. A complete
analysis and discussion of the HI data are presented and the global properties
of the galaxy are related to the bar dynamics presented in Paper I.Comment: 13 pages including 9 figures and 3 tables; accepted for publication
in MNRA
Applications of stochastic modeling in air traffic management:Methods, challenges and opportunities for solving air traffic problems under uncertainty
In this paper we provide a wide-ranging review of the literature on stochastic modeling applications within aviation, with a particular focus on problems involving demand and capacity management and the mitigation of air traffic congestion. From an operations research perspective, the main techniques of interest include analytical queueing theory, stochastic optimal control, robust optimization and stochastic integer programming. Applications of these techniques include the prediction of operational delays at airports, pre-tactical control of aircraft departure times, dynamic control and allocation of scarce airport resources and various others. We provide a critical review of recent developments in the literature and identify promising research opportunities for stochastic modelers within air traffic management
The effect of caffeine mouth rinse on self-paced cycling performance
The aim of the study was to determine whether caffeine mouth rinse would improve 30 min self-paced cycling trial. Twelve healthy active males (age 20.5±0.7 years, mass 87.4±18.3 kg) volunteered for the study. They attended the laboratory on 3 separate occasions performing a 30 min self-paced cycling trial. On one occasion water was given as a mouth rinse for 5 s (PLA), on another occasion a 6.4% maltodextrin (CHO) solution was given for 5 s and finally a caffeine solution (containing 32 mg of caffeine dissolved in 125 ml water; CAF) was given for 5 s. Distance cycled, heart rate, ratings of perceived exertion, cadence, speed and power output were recorded throughout all trials. Distance cycled during the CAF mouth rinse trial (16.2±2.8 km) was significantly greater compared to PLA trial (14.9±2.6 km). There was no difference between CHO and CAF trials (P=0.89). Cadence, power and velocity were significantly greater during the CAF trial compared to both PLA and CHO (P0.05). Caffeine mouth rinse improves 30 min cycling performance by allowing the participant to increase cadence, power and velocity without a concurrent increase in perceived exertion and heart rate
Dinosaur tracks in Triassic Molteno sediments: the earliest evidence of dinosaurs in South Africa?
A fossil tracksite containing well-preserved tridactyl footprints of bipedal theropod dinosaurs is reported from fluvial overbank deposits of Molteno age (Stormberg Group: Triassic) in the northeastern Cape Province, South Africa. They occur stratigraphically below the mudrocks of the Elliot Formation, in which dinosaur remains are comparatively common, and are taken to represent the earliest evidence for dinosaurs in South Africa. They also represent the earliest unequivocal evidence of tetrapods in Molteno deposits.Foundation for Research Development; Trustees of the Port Elizabeth Museu
Spontaneous fusion of malignant and host mouse cells in culture detected by phosphoglucose isomerase (GPI) isoenzymes.
Coping with emotional labour in tennis coaching
A tennis coach works in a social environment, employed in a service
based economy with the outcome of client-customer interactions
significantly impacting on the consumer experience. Research
conducted outside of sport has shown that positive affective
displays during interactions, which in a tennis situation may
include providing support through displays of warmth, empathy,
positivity and compassion as the client attempts to master a
new technique, have shown positive associations with customer
satisfaction. Hochschild (1983) coined the term ‘emotional labour’
to describe the process of, and demands resulting from adjusting
one’s demeanour, language and tone during social encounters
in a planned and strategic manner in order to facilitate a positive
outcome. Hochschild proposed that individuals in jobs which
require a high degree of face-to-face interaction with the public are
particularly at risk of experiencing potentially deleterious effects
that result from dealing with emotional labour demands on a daily
basis. It would appear that tennis coaches work in environments
that make them susceptible to experiencing emotional labour and
as such the intention of this article is to first introduce the concept
and then to provide suggestions for how a coach may cope with
these demands
Botulinum neurotoxin serotype F is a zinc endopeptidase specific for VAMP/synaptobrevin
Botulinum neurotoxin serotype F contains the zinc binding motif of zinc endopeptidases. Atomic adsorption analysis of highly purified toxin preparation revealed the presence of one atom of zinc per molecule of toxin, which could be removed with EDTA or o-phenanthroline. The light chain of the neurotoxin was shown to have a zinc-dependent protease activity specific for VAMP/synaptobrevin, an integral membrane protein of synaptic vesicles. Both isoforms of rat VAMP were cleaved at the same site corresponding to the single Gln-Lys peptide bond present in their sequences. This proteolytic activity was inhibited by EDTA, o-phenanthroline, and captopril as well as by VAMP peptides spanning the cleavage site
Resource allocation in congested queueing systems with time-varying demand:An application to airport operations
Motivated by the need to develop time-efficient methods for minimizing operational delays at severely congested airports, we consider a problem involving the distribution of a common resource between two sources of time-varying demand. We formulate this as a dynamic program in which the objective is based on second moments of stochastic queue lengths and show that, for sufficiently high volumes of demand, optimal values can be well-approximated by quadratic functions of the system state. We identify conditions which enable the strong performance of myopic policies and develop approaches to the design of heuristic policies by means of approximate dynamic programming (ADP) methods. Numerical experiments suggest that our ADP-based heuristics, which require very little computational effort, are able to improve substantially upon the performances of more naive decision-making policies, particularly if exogenous system parameters vary considerably as functions of time
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