Cross-Correlation in the Auditory Coincidence Detectors of Owls

Interaural time difference (ITD) plays a central role in many auditory functions, most importantly in sound localization. The classic model for how ITD is computed was put forth by Jeffress (1948). One of the predictions of the Jeffress model is that the neurons that compute ITD should behave as cross-correlators. Whereas cross-correlation-like properties of the ITD-computing neurons have been reported, attempts to show that the shape of the ITD response function is determined by the spectral tuning of the neuron, a core prediction of cross-correlation, have been unsuccessful. Using reverse correlation analysis, we demonstrate in the barn owl that the relationship between the spectral tuning and the ITD response of the ITD-computing neurons is that predicted by cross-correlation. Moreover, we show that a model of coincidence detector responses derived from responses to binaurally uncorrelated noise is consistent with binaural interaction based on cross-correlation. These results are thus consistent with one of the key tenets of the Jeffress model. Our work sets forth both the methodology to answer whether cross-correlation describes coincidence detector responses and a demonstration that in the barn owl, the result is that expected by theory

A Study of Vocational Choices and Preferences of Freshmen Male Students at State College in Terms of Their Abilities and Scholastic Achievement in College

The writer in this problem is deeply concerned with those high school students who are preparing themselves for the future and are going to college. Naturally colleges as well as students and their parents are interested in factors which make for success in college. Several of these are well known, such as, general mental ability, keen interest in college work, good study habits, regular attention to college tasks and definite vocational choice. The last of these mentioned, definite vocational choice has been subjected to less research than any of the others. This study has as its objective to determine if the more capable students, in terms of better scholastic ability, had made their vocational choices as they began their college work and to determine the degree to which those students who made definite vocational choices or expressed very definitely their vocational preferences, achieved better or less well than those who had not made such choices, early in college work. The general impression students and college faculties have is that the student who has committed himself to a vocational choice will consequently work harder at it and achieve better than the student who has not yet made his occupational choice. It is felt that the student without a vocational choice misses an important motivation and tends to flounder around in his work, achieving less well than the other one. But these are general impressions. The purpose of this study is to gather and statistically treat the pertinent data which may give a definite positive or negative answer to this general impression. The writer has no knowledge that such a problem concerning vocational choices and vocational preferences and their relationship to academic achievement, has been undertaken in South Dakota. There have been studies, a thesis by William Hass, on comparing educational proficiency of one-room-school graduates and town-elementary-school graduates found in the freshman and sophomore classes of six eastern South Dakota high schools. A research was completed by John Woodruff on scholastic records and personality and character traits of public-school trained versus parochial-school-trained students, in the Aberdeen, South Dakota school systems. These studies are not so similar to this one of content as they are similar to it in statistical technique. Guy Karnes completed a research dealing with vocational choices of high school graduates and the relation of their choices to their ACE Test scores. However, Karnes used different statistical methods to analyze his problem. This study seeks to show the difference between those students who had made their vocational choices while taking their ACE Tests in their senior year in high school and those students that tend to neglect their vocational choices while taking their ACE Tests and select various vocational preferences to vocations or do not specify any preferences, while enrolling as freshman at South Dakota State College at Brookings, South Dakota

Geometric approach to Fletcher's ideal penalty function

Original article can be found at: www.springerlink.com Copyright Springer. [Originally produced as UH Technical Report 280, 1993]In this note, we derive a geometric formulation of an ideal penalty function for equality constrained problems. This differentiable penalty function requires no parameter estimation or adjustment, has numerical conditioning similar to that of the target function from which it is constructed, and also has the desirable property that the strict second-order constrained minima of the target function are precisely those strict second-order unconstrained minima of the penalty function which satisfy the constraints. Such a penalty function can be used to establish termination properties for algorithms which avoid ill-conditioned steps. Numerical values for the penalty function and its derivatives can be calculated efficiently using automatic differentiation techniques.Peer reviewe

Random walk on surfaces with hyperbolic cusps

We consider the operator associated to a random walk on finite volume surfaces with hyperbolic cusps. We study the spectral gap (upper and lower bound) associated to this operator and deduce some rate of convergence of the iterated kernel towards its stationary distribution.Comment: 28 page

Explicit Delegation Using Configurable Cookies

Password sharing is widely used as a means of delegating access, but it is open to abuse and relies heavily on trust in the person being delegated to. We present a protocol for delegating access to websites as a natural extension to the Pico protocol. Through this we explore the potential characteristics of delegation mechanisms and how they interact. We conclude that security for the delegator against misbehaviour of the delegatee can only be achieved with the cooperation of the entity offering the service being delegated. To achieve this in our protocol we propose configurable cookies that capture delegated permissions.We are grateful to the European Research Council for funding this research through grant StG 307224 (Pico)

A calculus for distrust and mistrust

Properties of trust are becoming widely studied in several applications within the computational domain. On the contrary, negative trust attribution is less well-defined and related issues are yet to be approached and resolved. We present a natural deduction calculus for trust protocols and its negative forms, distrust and mistrust. The calculus deals efficiently with forms of trust transitivity and negative trust multiplication and we briefly illustrate some possible applications