70,976 research outputs found
Extreme paths in oriented 2D Percolation
A useful result about leftmost and rightmost paths in two dimensional bond
percolation is proved. This result was introduced without proof in \cite{G} in
the context of the contact process in continuous time. As discussed here, it
also holds for several related models, including the discrete time contact
process and two dimensional site percolation. Among the consequences are a
natural monotonicity in the probability of percolation between different sites
and a somewhat counter-intuitive correlation inequality
Solar cell angular position transducer
An angular position transducer utilizing photocells and a light source is disclosed. The device uses a fully rotatable baffle which is connected via an actuator shaft to the body whose rotational displacement is to be measured. The baffle blocks the light path between the light source and the photocells so that a constant semicircular beam of light reaches the photocells. The current produced by the photocells is fed through a resistor, a differential amplifier measures the voltage drop across the resistor which indicates the angular position of the actuator shaft and hence of the object
Looking Ahead
[Excerpt] The American entertainment industry and its system of labor-management relations is now at a crossroads. Its future will be determined to a great extent by emerging developments that could either hinder or facilitate expansion, depending on the course of affairs approaching the year 2000. The key trends will converge to influence the course of collective bargaining in the industry and the choices made by unions and employers
Statistical design and data analysis techniques for space station application - An essay Final report
Application of statistical design and data analysis to configuration and development of space station experiments and missio
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Idealised simulations of cyclones with robust symmetrically-unstable sting jets
Idealised simulations of Shapiro-Keyser cyclones developing a sting jet (SJ) are presented. Thanks to an improved and accurate implementation of thermal wind balance in the initial state, it has been possible to use more realistic environments than in previous idealised studies. As a consequence, this study provides further insight in SJ evolution and dynamics and explores SJ robustness to different environmental conditions, assessed via a wide range of sensitivity experiments.
The control simulation contains a cyclone that fits the Shapiro-Keyser conceptual model and develops a SJ whose dynamics are associated with the evolution of mesoscale instabilities along the airstream, including symmetric instability (SI). The SJ undergoes a strong descent while leaving the cloud-head banded tip and markedly accelerating towards the frontal-fracture region, revealed as an area of buckling of the already-sloped moist isentropes.
Dry instabilities, generated by vorticity tilting via slantwise frontal motions in the cloud head, exist in similar proportions to moist instabilities at the start of the SJ descent and are then released along the SJ. The observed evolution supports the role of SI in the airstream’s dynamics proposed in a conceptual model outlined in a previous study.
Sensitivity experiments illustrate that the SJ is a robust feature of intense Shapiro-Keyser cyclones, highlighting a range of different environmental conditions in which SI contributes to the evolution of this airstream, conditional on the model having adequate resolution.
The results reveal that several environmental factors can modulate the strength of the SJ. However, a positive relationship between the strength of the SJ, both in terms of peak speed and amount of descent, and the amount of instability occurring along it can still be identified.
In summary, the idealised simulations presented in this study show the robustness of SJ occurrence in intense Shapiro-Keyser cyclones and support and clarify the role of dry instabilities in SJ dynamics
Debt as a control device in transitional economies : the experiences of Hungary and Poland
The basic economic challenge in the transition from socialism to capitalism is creating incentive structures and institutions that promote enterprise change and restructuring. This is the motivation for most of the reforms debated during the transition - whether privatization, demonopolization, trade reform, or financial sector reform. Most research on corporate governance and privatization has focused on the role of owners - whether on the problems inherent in the separation of ownership and management (most Western literature) or on the need for true owners who represents the interests of capital (most literature on transition economies). But debt is also an important control device, as Western literature on corporate finance increasingly recognizes. The authors explore debt's role as a control device in transition economies, focusing especially on Hungary and Poland, which are relatively far along in the reform process. They ask, first, in what ways creditors exert control over firms in advanced market economies and how such control interacts with that exerted by equity holders. They then ask whether creditors in Central and Eastern European countries play similar roles and, if not, what roles they should play, and what can be done to give them the capacity and incentives to play those roles. They focus on three fundamental requirements for debt to function as a control device: information, proper incentives for creditors (including banks, suppliers, and government), and an efficient legal framework for debt collection (including collateral, workout, and bankruptcy regimes). While both countries are making progress in all three areas, there is still much to be done. Hungary and Poland illustrate only two of many approaches. Other transitional economies, such as the Czech Republic, Estonia, and Russia, are following different approaches that should be explored in future analysis.International Terrorism&Counterterrorism,Banks&Banking Reform,Payment Systems&Infrastructure,Environmental Economics&Policies,Financial Intermediation,Banks&Banking Reform,Environmental Economics&Policies,Financial Intermediation,Financial Crisis Management&Restructuring,Housing Finance
Granulation in K-type Dwarf Stars. II. Hydrodynamic simulations and 3D spectrum synthesis
We construct a 3D radiative-hydrodynamic model atmosphere of parameters Teff
= 4820 K, log g = 4.5, and solar chemical composition. The theoretical line
profiles computed with this model are asymmetric, with their bisectors having a
characteristic C-shape and their core wavelengths shifted with respect to their
laboratory values. The line bisectors span from about 10 to 250 m/s, depending
on line strength, with the stronger features showing larger span. The
corresponding core wavelength shifts range from about -200 m/s for the weak Fe
I lines to almost +100 m/s in the strong Fe I features. Based on observational
results for the Sun, we argue that there should be no core wavelength shift for
Fe I lines of EW > 100 mA. The cores of the strongest lines show contributions
from the uncertain top layers of the model, where non-LTE effects and the
presence of the chromosphere, which are important in real stars, are not
accounted for. The comparison of model predictions to observed Fe I line
bisectors and core wavelength shifts for a reference star, HIP86400, shows
excellent agreement, with the exception of the core wavelength shifts of the
strongest features, for which we suspect inaccurate theoretical values. Since
this limitation does not affect the predicted line equivalent widths
significantly, we consider our 3D model validated for photospheric abundance
work.Comment: A&A, in pres
[Review of] William P. French, Michel J. Febre, Amritjit Singh, and Geneviève E. Fabre (Eds). Afro-American Poetry and Drama, 1760-1975: A Guide to Information Sources
This bibliographic guide is actually two guides in one volume, both of them quite useful to the student of Afro-American writing. Black writers have often published their work themselves or in limited editions through small and relatively unknown presses
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