What are the odds? option-based forecasts of FOMC target changes

This article uses probability forecasts derived from options to assess evolving market uncertainty about Federal Reserve monetary policy actions in a variety of recent events and episodes. Options on federal funds futures contracts reveal a complete probability density function over possible Federal Reserve target rates, thus augmenting the expectations provided by federal funds futures contracts. Option-based forecasts are most useful when more than two federal funds target outcomes are plausible at an upcoming policy meeting.Federal Open Market Committee ; Forecasting ; Monetary policy

An Optically Controlled Closing and Opening Semiconductor Switch

A concept for a bulk semiconductor switch is presented, where the conductivity is increased and reduced, respectively, through illumination with light of different wavelengths. The increase in conductivity is accomplished by electron ionization from deep centers and generation of bound holes. The reduction of conductivity is obtained by hole ionization from the excited centers and subsequent recombination of free electrons and holes. The transient behavior of electron and hole density in a high power semiconductor (GaAs:Cu) switch is computed by means of a rate equation model. Changes in conductivity by five orders of magnitude can be obtained

Influence of Copper Doping on the Performance of Optically Controlled GaAs Switches

The influence of the copper concentration in silicon-doped gallium arsenide on the photoionization and photoquenching of charge carriers was studied both experimentally and theoretically. The studies indicate that the compensation ratio (NCu/NSi) is an important parameter for the GaAs:Si:Cu switch systems with regard to the turn-on and turn-off performance. The optimum copper concentration for the use of GaAs:Si:Cu as an optically controlled closing and opening switch is determined

Nanosecond Optical Quenching of Photoconductivity in a Bulk GaAs Switch

Persistent photoconductivity in copper-compensated, silicon-doped semi-insulating gallium arsenide with a time constant as large as 30 µs has been excited by sub-band-gap laser radiation of photon energy greater than 1 eV. This photoconductivity has been quenched on a nanosecond time scale by laser radiation of photon energy less than 1 eV. The proven ability to turn the switch conductance on and off on command, and to scale the switch to high power could make this semiconductor material the basis of an optically controlled pulsed-power closing and opening switch

Hyperfine structure of the ground state muonic He-3 atom

On the basis of the perturbation theory in the fine structure constant $\alpha$ and the ratio of the electron to muon masses we calculate one-loop vacuum polarization and electron vertex corrections and the nuclear structure corrections to the hyperfine splitting of the ground state of muonic helium atom $(\mu\ e \ ^3_2He)$. We obtain total result for the ground state hyperfine splitting $\Delta \nu^{hfs}=4166.471$ MHz which improves the previous calculation of Lakdawala and Mohr due to the account of new corrections of orders $\alpha^5$ and $\alpha^6$. The remaining difference between our theoretical result and experimental value of the hyperfine splitting lies in the range of theoretical and experimental errors and requires the subsequent investigation of higher order corrections.Comment: Talk on poster section of XXIV spectroscopy congress, 28 February-5 March 2010, Moscow-Troitsk, Russia, 21 pages, LaTeX, 8 figure

TiO2 Breakdown Under Pulsed Conditions

Model studies of current conduction and breakdown in TiO2 were carried out. Our simulation results indicate that electrical breakdown of TiO2 under multiple-pulsed conditions can occur at lower voltages as compared to quasi-dc biasing. This is in agreement with recent experimental data and is indicative of a cumulative phenomena. We demonstrate that the lower breakdown voltages observed in TiO2 under pulsed conditions is a direct rise-time effect, coupled with successive detrapping at the grain boundaries. 2007 American Institute of Physics

Knowledge Maps for Intelligent Questioning Systems in Engineering Education

The development of a hierarchical knowledge map with an intelligent questioning system to improve the educational process in engineering courses is discussed. Knowledge map represents the architecture of the entire curriculum and each course as an interconnection of modules. The knowledge system provides the necessary framework to allow a questioning system to select appropriate questions. It will also give immediate feedback and assistance to the student for improving the delays with classical assessment

An Instrument for Assessing Knowledge Gain in a First Course in Circuit Theory

Although there has been considerable research on the development and use of assessment instruments to measure the effectiveness of various pedagogical approaches to teaching introductory physics classes (Hestenes et al. 1, Hestenes et al 2, Hake 3, Saul et al. 4) and other science courses (for example, see Vosniadou 5), there is relatively little similar work that has been done to develop assessment instruments for the first circuit theory course that is taught in electrical and computer engineering. Given the large numbers of students nationwide who take such a course, the challenge this course presents to beginning engineering students, and the introduction of new approaches to teach this material, an instrument similar to those available for physics is needed to identify student misconceptions at the beginning of the class and to measure the normalized learning gain at the end of the class (Hake 3). These gains and other metrics can then be used to compare the effect of different teaching methods. In addition, this same instrument or portions of it can be offered at later times in the curriculum to measure retention and reinforcement from other courses. This concept-based testing approach is useful to examine the overall effectiveness of the circuit component of a curriculum and could thus be used as part of the continuous self-improvement process required under the ABET 2000 rules

GaAs Photoconductive Closing Switches with High Dark Resistance and Microsecond Conductivity Decay

Silicon-doped n-type gallium arsenide crystals, compensated with diffused copper, were studied with respect to their application as photoconductive, high-power closing switches. The attractive features of GaAs:Cu switches are their high dark resistivity, their efficient activation with Nd:YAG laser radiation, and their microsecond conductivity decay time constant. In the authors\u27 experiment, electric fields are high as 19 kV/cm were switched, and current densities of up to 10 kA/cm2 were conducted through a closely compensated crystal. At field strengths greater than approximately 10 kV/cm, a voltage `lock-on\u27 effect was observed

Universal Cellular Automata and Class 4

Wolfram has provided a qualitative classification of cellular automata(CA) rules according to which, there exits a class of CA rules (called Class 4) which exhibit complex pattern formation and long-lived dynamical activity (long transients). These properties of Class 4 CA's has led to the conjecture that Class 4 rules are Universal Turing machines i.e. they are bases for computational universality. We describe an embedding of a ``small'' universal Turing machine due to Minsky, into a cellular automaton rule-table. This produces a collection of $(k=18,r=1)$ cellular automata, all of which are computationally universal. However, we observe that these rules are distributed amongst the various Wolfram classes. More precisely, we show that the identification of the Wolfram class depends crucially on the set of initial conditions used to simulate the given CA. This work, among others, indicates that a description of complex systems and information dynamics may need a new framework for non-equilibrium statistical mechanics.Comment: Latex, 10 pages, 5 figures uuencode