Starch and Stripes, 1955

https://digitalcommons.unmc.edu/yearbooks/1006/thumbnail.jp

Wiener filtering with a seismic underground array at the Sanford Underground Research Facility

A seismic array has been deployed at the Sanford Underground Research Facility in the former Homestake mine, South Dakota, to study the underground seismic environment. This includes exploring the advantages of constructing a third-generation gravitational-wave detector underground. A major noise source for these detectors would be Newtonian noise, which is induced by fluctuations in the local gravitational field. The hope is that a combination of a low-noise seismic environment and coherent noise subtraction using seismometers in the vicinity of the detector could suppress the Newtonian noise to below the projected noise floor for future gravitational-wave detectors. In this paper, we use Wiener filtering techniques to subtract coherent noise in a seismic array in the frequency band 0.05 -- 1\,Hz. This achieves more than an order of magnitude noise cancellation over a majority of this band. We show how this subtraction would benefit proposed future low-frequency gravitational wave detectors. The variation in the Wiener filter coefficients over the course of the day, including how local activities impact the filter, is analyzed. We also study the variation in coefficients over the course of a month, showing the stability of the filter with time. How varying the filter order affects the subtraction performance is also explored. It is shown that optimizing filter order can significantly improve subtraction of seismic noise, which gives hope for future gravitational-wave detectors to address Newtonian noise

Retinal adaptation to spatial correlations

The classical center-surround retinal ganglion cell receptive field is thought to remove the strong spatial correlations in natural scenes, enabling efficient use of limited bandwidth. While early studies with drifting gratings reported robust surrounds (Enroth-Cugell and Robson, 1966), recent measurements with white noise reveal weak surrounds (Chichilnisky and Kalmar, 2002). This might be evidence for dynamical weakening of the retinal surround in response to decreased spatial correlations, which would be predicted by efficient coding theory. Such adaptation is reported in LGN (Lesica et al., 2007), but whether the retina also adapts to correlations is unknown. 

We tested for adaptation by recording simultaneously from ~40 ganglion cells on a multi-electrode array while presenting white and exponentially correlated checkerboards and strips. Measuring from ~200 cells responding to 90 minutes each of white and correlated stimuli, we were able to extract precise spatiotemporal receptive fields (STRFs). We found that a difference-of-Gaussians was not a good fit and the surround was generally displaced from the center. Thus, to assess surround strength we found the center and surround regions and the total weight on the pixels in each region. The relative surround strength was then defined as the ratio of surround weight to center weight. Surprisingly, we found that the majority of recorded cells have a stronger surround under white noise than under correlated noise (p<.05), contrary to naive expectation from theory. The conclusion was robust to different methods of extracting STRFs and persisted with checkerboard and strip stimuli.

To test, without assuming a model, whether the retina decorrelates stimuli, we also measured the pairwise correlations between spike trains of simultaneously recorded neurons under three conditions: white checkerboard, exponentially correlated noise, and scale-free noise. The typical amount of pairwise correlation increased with extent of input correlation, in line with our STRF measurements

Tree constructions of free continuous algebras

AbstractContinuous algebras are algebras endowed with a partial order which is complete with respect to specified joins and such that the operations preserve these specified joins. We prove the existence of free continuous algebras by actually giving a concrete description of them in terms of trees, for any type of algebras and any choice of the “specified” joins

Key Organizational Elements for Effective Information and Knowledge Management

Effective information and knowledge management (IKM) is critical to corporate success; yet, its actual establishment and management is not yet fully understood. We identify ten organizational elements that need to be addressed to ensure the effective implementation and maintenance of information and knowledge management within organizations. We define these elements and provide key characterizations. We then discuss a case study that describes the implementation of an information system (designed to support IKM) in a medical supplies organization. We apply the framework of organizational elements in our analysis to uncover the enablers and barriers in this systems implementation project. Our analysis suggests that taking the ten organizational elements into consideration when implementing information systems will assist practitioners in managing information and knowledge processes more effectively and efficiently. We discuss implications for future research

A Framework for a Dynamic Metropolitan University

A Metropolitan University (MU) is deeply embedded in its local community, entwined in various economic, social, and professional networks over which creative and innovative ideas circulate. In keeping with its core mission of education, a MU can leverage these networks by implementing a research agenda designed to gain a better understanding of the propagation and exchange of ideas over the networks in which it operates. We refer to a university that has adopted such an agenda as a Dynamic Metropolitan University. Guided by a strategic plan that recognizes and supports the study of networks, a Dynamic MU is then positioned to effectively differentiate itself from online education, local community colleges, and less community-oriented universities

An Analysis of Data Regarding Public Private Partnerships to Encourage Hotel Development in the United States

In recent decades, communities in the United States have increasingly turned to public private partnerships, also known as PPPs or P3s, to encourage development of large convention headquarter hotels. Under such arrangements communities provide incentives to encourage private sector investors to build hotels that can house delegates, exhibitors and other attendees participating in events at publicly owned conventions centers. In recent years the practice of public subsidies, and in some cases outright public ownership, has spread beyond convention hotels to a wide range of hotel projects. This study presents data collected on these publicly assisted hotels to provide a picture of how these arrangements are structured. It goes on propose an economic model based on the income capitalization approach to valuation to determine the rate of return that communities can expect from their investments in these project