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

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

Our Part in These Times by J. O. Christianson, UND Mid-Year Commencement: January 31, 1943

Text of speech delivered by Dr. J. O. Christianson at the UND Mid-Year Commencement on January 31, 1943. Dr. Christianson was the superintendent for the School of Agriculture at the University of Minnesota - Twin Cities. He entitled his remarks: Our Part in These Times

The Rise of Jonas Olsen: A Norwegian Immigrant’s Saga

Review of: "The Rise of Jonas Olsen: A Norwegian Immigrant’s Saga," by Johannes B. Wist, translated by Orm Øverland

Near Sharp Strichartz estimates with loss in the presence of degenerate hyperbolic trapping

We consider an $n$-dimensional spherically symmetric, asymptotically Euclidean manifold with two ends and a codimension 1 trapped set which is degenerately hyperbolic. By separating variables and constructing a semiclassical parametrix for a time scale polynomially beyond Ehrenfest time, we show that solutions to the linear Schr\"odiner equation with initial conditions localized on a spherical harmonic satisfy Strichartz estimates with a loss depending only on the dimension $n$ and independent of the degeneracy. The Strichartz estimates are sharp up to an arbitrary $\beta>0$ loss. This is in contrast to \cite{ChWu-lsm}, where it is shown that solutions satisfy a sharp local smoothing estimate with loss depending only on the degeneracy of the trapped set, independent of the dimension

Quest for Cash: Exempt Organizations, Joint Ventures, Taxable Subsidiaries, and Unrelated Business Income

Most “for-profit” or “business” activities of exempt organizations take one of three forms: (A) The exempt organization may undertake to perform the business activities within the existing structure of the exempt organization. (B) The exempt organization may form a “taxable” subsidiary or affiliate which will perform the business activities. (C) The exempt organization may “partner” with other individuals and entities (both nonprofit and for-profit) to form a corporation, limited liability company (LLC), partnership, joint venture, strategic alliance, or other collaborative effort which will perform the “for-profit” activities. Depending in part upon which of these forms is chosen, any business activities by an exempt organization may result in: (i) income taxes being imposed upon the exempt organization or the “for-profit” entity; (ii) the exempt organization losing its tax-exempt status; (iii) excise taxes being imposed by the Internal Revenue Service (IRS) on the individuals and for-profit companies (as well as on the managers of the exempt organization) with whom the tax-exempt organization conducts a business activity; (iv) a regulatory action brought against the organization by federal or state governmental authorities; or (v) all of the above. This article gives an overview of the regulations, Treasury rulings, IRS manuals, and case law that become important when an exempt organization decides to engage in business activity

Quest for Cash: Exempt Organizations, Joint Ventures, Taxable Subsidiaries, and Unrelated Business Income

Most “for-profit” or “business” activities of exempt organizations take one of three forms: (A) The exempt organization may undertake to perform the business activities within the existing structure of the exempt organization. (B) The exempt organization may form a “taxable” subsidiary or affiliate which will perform the business activities. (C) The exempt organization may “partner” with other individuals and entities (both nonprofit and for-profit) to form a corporation, limited liability company (LLC), partnership, joint venture, strategic alliance, or other collaborative effort which will perform the “for-profit” activities. Depending in part upon which of these forms is chosen, any business activities by an exempt organization may result in: (i) income taxes being imposed upon the exempt organization or the “for-profit” entity; (ii) the exempt organization losing its tax-exempt status; (iii) excise taxes being imposed by the Internal Revenue Service (IRS) on the individuals and for-profit companies (as well as on the managers of the exempt organization) with whom the tax-exempt organization conducts a business activity; (iv) a regulatory action brought against the organization by federal or state governmental authorities; or (v) all of the above. This article gives an overview of the regulations, Treasury rulings, IRS manuals, and case law that become important when an exempt organization decides to engage in business activity