45 research outputs found
Treating rhinitis in the older population: special considerations
Rhinitis in the elderly is a common but often neglected condition. Structural changes in the nose associated with aging, predisposes the elderly to rhinitis. There are a number of specific factors that affect medical treatment of the elderly including polypharmacy, cognitive dysfunction, changes in body composition, impairment of liver and renal function and the cost of medications in the face of limited resources. Rhinitis in the elderly can be placed in several categories and treatment should be appropriate for each condition. The most important aim is to moisten the nasal mucosa since the nose of the elderly is so dry. Great caution should be used in treatment with first generation antihistamines and decongestants. Medications generally well tolerated by the elderly are second generation antihistamines, intra-nasal anti-inflammatory agents, leukotriene modifiers and iprapropium nasal spray
Evaporation and condensation of spherical interstellar clouds. Self-consistent models with saturated heat conduction and cooling
Shortened version: The fate of IS clouds embedded in a hot tenuous medium
depends on whether the clouds suffer from evaporation or whether material
condensates onto them. Analytical solutions for the rate of evaporative mass
loss from an isolated spherical cloud embedded in a hot tenuous gas are deduced
by Cowie & McKee (1977). In order to test the validity of the analytical
results for more realistic IS conditions the full hydrodynamical equations must
be treated. Therefore, 2D numerical simulations of the evolution of IS clouds
%are performed with different internal density structures and surrounded by a
hot plasma reservoir. Self-gravity, interstellar heating and cooling effects
and heat conduction by electrons are added. Classical thermal conductivity of a
fully ionized hydrogen plasma and saturated heat flux are considered. Using
pure hydrodynamics and classical heat flux we can reproduce the analytical
results. Heat flux saturation reduces the evaporation rate by one order of
magnitude below the analytical value. The evolution changes totally for more
realistic conditions when interstellar heating and cooling effects stabilize
the self-gravity. Evaporation then turns into condensation, because the
additional energy by heat conduction can be transported away from the interface
and radiated off efficiently from the cloud's inner parts. I.e. that the
saturated heat flux consideration is inevitable for IS clouds embedded in hot
tenuous gas. Various consequences are discussed in the paper.Comment: 16 pages, 24 figures, accepted in Astronomy and Astrophysic
Dynamics of Ganymede's magnetopause: Intermittent reconnection under steady external conditions
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95138/1/jgra20818.pd
Magnetic field change across the Earth's bow shock: Comparison between observations and theory
Subcallosal cingulate deep brain stimulation for treatment-resistant depression: a multi-site, randomized, sham-controlled trial
Dust in Supernovae and Supernova Remnants II: Processing and survival
Observations have recently shown that supernovae are efficient dust factories, as predicted for a long time by theoretical models. The rapid evolution of their stellar progenitors combined with their efficiency in precipitating refractory elements from the gas phase into dust grains make supernovae the major potential suppliers of dust in the early Universe, where more conventional sources like Asymptotic Giant Branch (AGB) stars did not have time to evolve. However, dust yields inferred from observations of young supernovae or derived from models do not reflect the net amount of supernova-condensed dust able to be expelled from the remnants and reach the interstellar medium. The cavity where the dust is formed and initially resides is crossed by the high velocity reverse shock which is generated by the pressure of the circumstellar material shocked by the expanding supernova blast wave. Depending on grain composition and initial size, processing by the reverse shock may lead to substantial dust erosion and even complete destruction. The goal of this review is to present the state of the art about processing and survival of dust inside supernova remnants, in terms of theoretical modelling and comparison to observations