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Contractionary Effects of Stabilization and Long-Run Growth
This paper reviews models of long-run growth which assume that the economy is not on its so-called "normal" path, and in which both aggregate demand and aggregate supply issues have a role in determining long-run growth. This review shows that contractionary stabilization policies can have adverse long-run effects on growth, and may in fact exacerbate the problems they were intended to solve
Modelling and parameter estimation of diethyl phthalate partitioning behaviour on glass and aluminum surfaces
The knowledge of the partitioning behaviour of semi-volatile organic compounds (SVOCs), such as phthalates, between different materials and their surrounding air is of extreme importance for quantifying levels of human exposure to these compounds, which have been associated with adverse health effects. Phthalates’ partitioning behaviour also represents a key property for modelling and assessing polymer degradation mechanisms associated with plasticiser loss. However, the characterisation of phthalates partitioning behaviour has been reported only for a limited number of compounds, mainly involving di-2-ethylhexyl phthalate (DEHP), di-isononyl phthalate (DINP) and di-isodecyl phtahalate (DIDP), while the characterisation of diethyl phthalate (DEP) partitioning has been overlooked. As one of the first plasticisers employed in the production of semi-synthetic plastics produced industrially in the late 19th and early 20th century, DEP plays an important role for understanding stability issues associated with historically significant artefacts in museum collections and archives. Here we show that the partitioning behaviour of DEP between borosilicate glass and aluminum surfaces and their surrounding air can be described by an exponential function of temperature, presenting a model to describe this relationship for the first time. Model parameters are estimated using nonlinear regression from experimental measurements acquired using 109 samples which have been equilibrated at different temperatures between 20 and 80 °C in sealed environments. Measured partition coefficients have been predicted accurately by our proposed model. The knowledge of DEP equilibrium distribution between adsorptive surfaces and neighbouring environments will be relevant for developing improved mathematical descriptions of degradation mechanisms related to plasticiser loss
Bifurcations in the Lozi map
We study the presence in the Lozi map of a type of abrupt order-to-order and
order-to-chaos transitions which are mediated by an attractor made of a
continuum of neutrally stable limit cycles, all with the same period.Comment: 17 pages, 12 figure
Intrinsic Brightness Temperatures of AGN Jets
We present a new method for studying the intrinsic brightness temperatures of
the parsec-scale jet cores of Active Galactic Nuclei (AGN). Our method uses
observed superluminal motions and observed brightness temperatures for a large
sample of AGN to constrain the characteristic intrinsic brightness temperature
of the sample as a whole. To study changes in intrinsic brightness temperature,
we assume that the Doppler factors of individual jets are constant in time as
justified by their relatively small changes in observed flux density. We find
that in their median-low brightness temperature state, the sources in our
sample have a narrow range of intrinsic brightness temperatures centered on a
characteristic temperature, T_int = 3 x 10^10 K, which is close to the value
expected for equipartition, when the energy in the radiating particles equals
the energy stored in the magnetic fields. However, in their maximum brightness
state, we find that sources in our sample have a characteristic intrinsic
brightness temperature greater than 2 x 10^11 K, which is well in excess of the
equipartition temperature. In this state, we estimate the energy in radiating
particles exceeds the energy in the magnetic field by a factor of ~ 10^5. We
suggest that the excess of particle energy when sources are in their maximum
brightness state is due to injection or acceleration of particles at the base
of the jet. Our results suggest that the common method of estimating jet
Doppler factors by using a single measurement of observed brightness
temperature and/or the assumption of equipartition may lead to large scatter or
systematic errors in the derived values.Comment: 4 pages, 2 figures, Accepted to Appear in ApJ Letter
Kinematics of parsec-scale structures in AGN: the 2cm VLBA Survey
We are investigating the kinematics of jets in active galactic nuclei on
parsec scales by studying a representative population of sources. This study is
being carried out using the Very Long Baseline Array at 15 GHz, with more than
800 images taken since 1994. In this contribution we present an overview of the
diversity of kinematics for a complete sample of sources.Comment: Proceedings of the 6th European VLBI Network Symposium, Ros E.,
Porcas R.W., Lobanov, A.P., & Zensus, J.A. (eds), MPIfR, Bonn, Germany. 2
pages, 3 figures, needs evn2002.cls style fil
Variability and Velocity of Superluminal Sources
We investigate the relation between the Doppler factor determined from
variations in total flux at 22 and 37 GHz, and the apparent transverse velocity
determined from VLBA observations at 2 cm. The data are consistent with the
relativistic beaming theory for compact radio sources, in that the distribution
of beta_{app}/delta_{var}, for 30 quasars, is roughly consistent with a Monte
Carlo simulation. The intrinsic temperature appears to be ~2x10^{10} K, close
to the "equipartition value" calculated by Readhead (1994). We deduce the
distribution of Lorentz factors for a group of 48 sources; the values range up
to about gamma=40.Comment: To be published in "Radio Astronomy at the Fringe", ASP Conf. Ser.
Vol. 300, J. A. Zensus, M. H. Cohen, & E. Ros (eds.), 8 pages, 3 figures,
needs rafringe.st
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