782 research outputs found
Actinometry of Hydrogen Plasmas
Optical emission spectroscopy (OES) can be used to map the electron energy distribution of hydrogen plasmas. Using actinometry, a type of OES where trace amounts of noble gases are introduced, the effect of discharge power on the electron temperature of hydrogen plasmas was explored. This was done using argon and krypton as actinometers for low pressure hydrogen plasmas. It was determined that the electron temperature decreased with respect to power supplied to the discharge
The Structure of Debt and Active Equity Investors: The Case of the Buyout Specialist
This paper examines the role buyout specialists play in structuring the debt used to finance the LBO and in monitoring management in the post-LBO firm. We find that when buyout specialists control the majority of the post-LBO equity, the LBO transaction is likely to be financed with less short-term and/or senior debt and less likely to experience financial distress. We also find that buyout specialists have greater board representation on smaller boards, suggesting that they actively monitor managers, and that for these transactions, using debt with tighter terms does not significantly increase the firm\u27s performance. In contrast, in all other transactions using such debt does significantly increase the firm\u27s performance. These findings suggest that active monitoring by a buyout specialist substitutes for tighter debt terms in monitoring and motivating managers of LBOs
Hedging Effectiveness under Conditions of Asymmetry
We examine whether hedging effectiveness is affected by asymmetry in the return distribution by applying tail specific metrics to compare the hedging effectiveness of short and long hedgers using Oil futures contracts. The metrics used include Lower Partial Moments (LPM), Value at Risk (VaR) and Conditional Value at Risk (CVAR). Comparisons are applied to a number of hedging strategies including OLS and both Symmetric and Asymmetric GARCH models. Our findings show that asymmetry reduces in-sample hedging performance and that there are significant differences in hedging performance between short and long hedgers. Thus, tail specific performance metrics should be applied in evaluating hedging effectiveness. We also find that the Ordinary Least Squares (OLS) model provides consistently good performance across different measures of hedging effectiveness and estimation methods irrespective of the characteristics of the underlying distribution.Hedging Performance; Asymmetry; Downside Risk; Value at Risk, Conditional Value at Risk. JEL classification: G10, G12, G15. ____________________________________________________________________ John Cotter, Director of Centre for Financial Markets, Department of Banking and Finance, University College Dublin, Blackrock, Co. Dublin, Ireland, tel 353 1 716 8900, e-mail [email protected]. Jim Hanly, School of Accounting and Finance, Dublin Institute of Technology, tel 353 1 402 3180, e-mail [email protected]. The authors would like to thank the participants at the Global Finance Annual Conference for their constructive comments.
Measuring Securities Market Efficiency in the Regulatory Setting
In Nov 1998, the SEC proposed a modification to the federal securities law disclosure requirements to facilitate the process of issuing new securities. Thomas and Cotter discuss how to determine when companies should be able to issue simplified disclosure documents
Waltzing peakons and compacton pairs in a cross-coupled Camassa-Holm equation
We consider singular solutions of a system of two cross-coupled Camassa-Holm
(CCCH) equations. This CCCH system admits peakon solutions, but it is not in
the two-component CH integrable hierarchy. The system is a pair of coupled
Hamiltonian partial differential equations for two types of solutions on the
real line, each of which separately possesses exp(-|x|) peakon solutions with a
discontinuity in the first derivative at the peak. However, there are no
self-interactions, so each of the two types of peakon solutions moves only
under the induced velocity of the other type. We analyse the `waltzing'
solution behaviour of the cases with a single bound peakon pair (a peakon
couple), as well as the over-taking collisions of peakon couples and the
antisymmetric case of the head-on collision of a peakon couple and a peakon
anti-couple. We then present numerical solutions of these collisions, which are
inelastic because the waltzing peakon couples each possess an internal degree
of freedom corresponding to their `tempo' -- that is, the period at which the
two peakons of opposite type in the couple cycle around each other in phase
space. Finally, we discuss compacton couple solutions of the cross-coupled
Euler-Poincar\'e (CCEP) equations and illustrate the same types of collisions
as for peakon couples, with triangular and parabolic compacton couples. We
finish with a number of outstanding questions and challenges remaining for
understanding couple dynamics of the CCCH and CCEP equations
The Square Root Depth Wave Equations
We introduce a set of coupled equations for multilayer water waves that
removes the ill-posedness of the multilayer Green-Naghdi (MGN) equations in the
presence of shear. The new well-posed equations are Hamiltonian and in the
absence of imposed background shear they retain the same travelling wave
solutions as MGN. We call the new model the Square Root Depth equations, from
the modified form of their kinetic energy of vertical motion. Our numerical
results show how the Square Root Depth equations model the effects of
multilayer wave propagation and interaction, with and without shear.Comment: 10 pages, 5 figure
Surrogate Accelerated Bayesian Inversion for the Determination of the Thermal Diffusivity of a Material
Determination of the thermal properties of a material is an important task in
many scientific and engineering applications. How a material behaves when
subjected to high or fluctuating temperatures can be critical to the safety and
longevity of a system's essential components. The laser flash experiment is a
well-established technique for indirectly measuring the thermal diffusivity,
and hence the thermal conductivity, of a material. In previous works,
optimization schemes have been used to find estimates of the thermal
conductivity and other quantities of interest which best fit a given model to
experimental data. Adopting a Bayesian approach allows for prior beliefs about
uncertain model inputs to be conditioned on experimental data to determine a
posterior distribution, but probing this distribution using sampling techniques
such as Markov chain Monte Carlo methods can be incredibly computationally
intensive. This difficulty is especially true for forward models consisting of
time-dependent partial differential equations. We pose the problem of
determining the thermal conductivity of a material via the laser flash
experiment as a Bayesian inverse problem in which the laser intensity is also
treated as uncertain. We introduce a parametric surrogate model that takes the
form of a stochastic Galerkin finite element approximation, also known as a
generalized polynomial chaos expansion, and show how it can be used to sample
efficiently from the approximate posterior distribution. This approach gives
access not only to the sought-after estimate of the thermal conductivity but
also important information about its relationship to the laser intensity, and
information for uncertainty quantification. We also investigate the effects of
the spatial profile of the laser on the estimated posterior distribution for
the thermal conductivity
Social group work with alcoholic patients in relation to their group experiences.
Thesis (M.S.)--Boston Universit
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