15,768 research outputs found

    Noise-robust detection of peak-clipping in decoded speech

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    Using graded questions to increase timely reading of assigned material

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    We assigned students in a personality psychology class graded long-answer questions in an attempt to increase their likelihood of reading assigned class material in a timely manner. We evaluated the effectiveness of this technique by examining exam scores and student evaluations. Students performed significantly better on the exam questions that were related to the topics covered by the long-answer questions than they did on exam questions related to other topics. Students also reported having read significantly more of the assigned material when there was a long-answer question as-signed, and they evaluated the method positively and recommended its use in future classes. In an attempt to increase students' comprehension of material presented during lectures, course instructors often as-sign readings to their students before each class. Unfortunately, many students do not read the assigned mate-rial prior to class; in fact, compliance with reading assigned material has decreased in recent years (Burchfield & Sappington, 2000). Students tend to postpone preparation until a few days immediately preceding the tests (Thorne, 2000). Failing to complete readings before class is a strong predictor of nonparticipation (Karp & Yoels, 1976) and negatively affects students' learning and achievement (Bur-roughs, Kearney, & Plax, 1989). Despite the potential and known benefits of reading the assigned material before class, such as enhancing the comprehension of lecture material (Solomon, 1979), motivating students to read may not be an easy task, especially when students are not given an incentive to do so. Carkenord (1994) stated "practical experience … indicates that most students don't read textbooks or journal articles as a result of their intrinsic interest and desire to learn" (p. 164). Accordingly, Burchfield and Sappington (2000) recommended the use of strategies to monitor timely reading compliance and claimed that not doing so would send a message to students that this aspect of learning is optional and of little concern to the instructor. One strategy to monitor and encourage read-ing compliance is the use of quizzes (e.g., Marchant, 2002; Ruscio, 2001); however, quizzes can create undue anxiety in some students. In this study, we tested an alternative strategy to increase the likelihood that students would read the as-signed material prior to class: graded long-answer questions based on the assigned reading material. In particular, we tested whether graded assignments based on assigned readings would increase students' timely reading of the materia

    Spurious Eccentricities of Distorted Binary Components

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    I discuss the effect of physical distortion on the velocities of close binary components and how we may use the resulting distortion of velocity curves to constrain some properties of binary systems, such as inclination and mass ratio. Precise new velocities for 5 Cet convincingly detect these distortions with their theoretically predicted phase dependence. We can even use such distortions of velocity curves to test Lucy's theory of convective gravity darkening. The observed distortions for TT Hya and 5 Cet require the contact components of those systems to be gravity darkened, probably somewhat more than predicted by Lucy's theory but clearly not as much as expected for a radiative star. These results imply there is no credible evidence for eccentric orbits in binaries with contact components. I also present some speculative analyses of the observed properties of a binary encased in a non-rotating common envelope, if such an object could actually exist, and discuss how the limb darkening of some recently calculated model atmospheres for giant stars may bias my resuts for velocity-curve distortions, as well as other results from a wide range of analyses of binary stars.Comment: 14 pp, 2 tables, 12 fig; under review by Ap

    An adaptive, hanging-node, discontinuous isogeometric analysis method for the first-order form of the neutron transport equation with discrete ordinate (SN) angular discretisation

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    In this paper a discontinuous, hanging-node, isogeometric analysis (IGA) method is developed and applied to the first-order form of the neutron transport equation with a discrete ordinate (SN) angular discretisation in two-dimensional space. The complexities involved in upwinding across curved element boundaries that contain hanging-nodes have been addressed to ensure that the scheme remains conservative. A robust algorithm for cycle-breaking has also been introduced in order to develop a unique sweep ordering of the elements for each discrete ordinates direction. The convergence rate of the scheme has been verified using the method of manufactured solutions (MMS) with a smooth solution. Heuristic error indicators have been used to drive an adaptive mesh refinement (AMR) algorithm to take advantage of the hanging-node discretisation. The effectiveness of this method is demonstrated for three test cases. The first is a homogeneous square in a vacuum with varying mean free path and a prescribed extraneous unit source. The second test case is a radiation shielding problem and the third is a 3×3 “supercell” featuring a burnable absorber. In the final test case, comparisons are made to the discontinuous Galerkin finite element method (DGFEM) using both straight-sided and curved quadratic finite elements

    The Forward Exchange Market, Speculation, and Exchange Market Intervention

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    This paper develops a stochastic equilibrium model of an open economy incorporating speculation in the forward exchange market. The model is used to examine two issues. The first is the role of speculation in stabilizing the economy against stochastic disturbances. Much risk averse speculation stabilizes domestic income against disturbances in the domestic bond market and forward exchange marketbut exacerbates the effect of foreign disturbances. Speculation may dampen or augment the effect of money market and output supply disturbances depending upon the share of foreign bonds in total wealthand the interest elasticity of bond demand. The second issue that the model addresses is the role of the forward market in stabilization policy. Forward market intervention (or its equivalent in this model,sterilized spot market intervention) does not provide monetary authorities additional leverage in stabilizing income beyond unsterilized spot market intervention. Intervention rules based on reactions to both the forward and the spot exchange rates, however, can outper-form intervention policies responding to the spot rate alone,regardless of the market in which intervention occurs.

    Covered Interest Parity, Uncovered Interest Parity, and Exchange Rate Dynamics

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    A number of macroeconomic models of open economies under flexible exchange rate assume a strong version of perfect capital mobility which implies that currency speculation commands no risk premium. If this assumption is dropped a number of important results no longer obtain. First, the exchange rate and interest rate cannot be in steady state unless both the government deficit and current account equal zero, not simply their sum, as would otherwise be the case. Second, even in steady state the domestic interest rate can deviate from the foreign interest rate by an amount which de ends upon relative domestic asset supplies. Finally, introducing risk aversion on the part of speculators can reduce the response on impact of the exchange rate to changes in domestic asset supplies. In this sense rational speculators, if they are less risk averse than other agents, can destabilize exchange markets.

    Satellite Relay Telemetry of Seismic Data in Earthquake Prediction and Control

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    The Satellite Telemetry Earthquake Monitoring Program was started to evaluate the applicability of satellite relay telemetry in the collection of seismic data from a large number of dense seismograph clusters laid out along the major fault systems of western North America. Prototype clusters utilizing phone-line telemetry were then being installed by the National Center for Earthquake Research in 3 regions along the San Andreas fault in central California; and the experience of installing and operating the clusters and in reducing and analyzing the seismic data from them was to provide the raw materials for evaluation in the satellite relay telemetry project. The principal advantages of the satellite relay system over commercial telephone or microwave systems were: (1) it could be made less prone to massive failure during a major earthquake; (2) it could be extended readily into undeveloped regions; and (3) it could provide flexible, uniform communications over large sections of major global tectonic zones. Fundamental characteristics of a communications system to cope with the large volume of raw data collected by a short-period seismograph network are discussed
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