Stimulus-invariant processing and spectrotemporal reverse correlation in primary auditory cortex

The spectrotemporal receptive field (STRF) provides a versatile and integrated, spectral and temporal, functional characterization of single cells in primary auditory cortex (AI). In this paper, we explore the origin of, and relationship between, different ways of measuring and analyzing an STRF. We demonstrate that STRFs measured using a spectrotemporally diverse array of broadband stimuli -- such as dynamic ripples, spectrotemporally white noise, and temporally orthogonal ripple combinations (TORCs) -- are very similar, confirming earlier findings that the STRF is a robust linear descriptor of the cell. We also present a new deterministic analysis framework that employs the Fourier series to describe the spectrotemporal modulations contained in the stimuli and responses. Additional insights into the STRF measurements, including the nature and interpretation of measurement errors, is presented using the Fourier transform, coupled to singular-value decomposition (SVD), and variability analyses including bootstrap. The results promote the utility of the STRF as a core functional descriptor of neurons in AI.Comment: 42 pages, 8 Figures; to appear in Journal of Computational Neuroscienc

An Expert Systems Approach to Realtime, Active Management of a Target Resource

The application of expert systems techniques to process control domains represents a potential approach to managing the increasing complexity and dynamics which characterizes many process control environments. This thesis reports on one such application in a complex, multi-agent environment, with an eye toward generalization to other process control domains. The application concerns the automation of large computing system operation. The requirement for high availability, high performance, computing systems has created a demand for fast, consistent, expert quality response to operational problems, and effective, flexible automation of computer operations would satisfy this demand while improving the productivity of operations. However, like many process control environments, the computer operations environment is characterized by high complexity and frequent change, rendering it difficult to automate operations in traditional procedural software. These are among the characteristics which motivate an expert systems approach to automation. JESQ, the focus of this thesis, is a realtime expert system which continuously monitors the level of operating system queue space in a large computing system and takes corrective action as queue space diminishes. JESQ is one of several expert systems which comprise a system called Yorktown Expert System/MVS Manager (YES/MVS). YES/MVS automates many tasks in the domain of computer operations, and is among the first expert systems designed for continuous execution in realtime. The expert system is currently running at the IBM Thomas J. Watson Research Center, and has received a favorable response from operations staff. The thesis concentrates on several related issues. The requirements which distinguish continuous realtime expert systems that exert active control over their environments from more conventional session-oriented expert systems are identified, and strategies for meeting these requirements are described. An alternative methodology for managing large computing installations is presented. The problems of developing and testing a realtime expert system in an industrial environment are described

Explaining and Refining Decision-Theoretic Choices

As the need to make complex choices among competing alternative actions is ubiquitous, the reasoning machinery of many intelligent systems will include an explicit model for making choices. Decision analysis is particularly useful for modelling such choices, and its potential use in intelligent systems motivates the construction of facilities for automatically explaining decision-theoretic choices and for helping users to incrementally refine the knowledge underlying them. The proposed thesis addresses the problem of providing such facilities. Specifically, we propose the construction of a domain-independent facility called UTIL, for explaining and refining a restricted but widely applicable decision-theoretic model called the additive multi-attribute value model. In this proposal we motivate the task, address the related issues, and present preliminary solutions in the context of examples from the domain of intelligent process control

A study of the effects of micro-gravity on seed germination

This study will identify characteristics of seed germination dependent upon gravity. To accomplish this objective, four different seed types will be germinated in space and then be compared to a control group germinated on Earth. Both the experimental and control groups will be analyzed on the cellular level for the size of cells, structural anomalies, and gravitational effects. The experiment will be conducted in a Get Away Special Canister (GAS Can no. 608) owned by the U.S. Space and Rocket Center and designed for students. The GAS Can will remain in the cargo bay of the Space Shuttle with minimal astronaut interaction

Managing the Global knowledge-creation Network: A Sense Making Perspective

We have entered the era of the knowledge economy, a period when knowledge has replaced natural resources and capital as the most important economic resource. Increasingly, corporations are reaching out globally to secure the best talent available at the most reasonable cost to serve world-wide markets

The status of the brown bear in Alaska

Presented at the 9th Alaska Science Conference, University of Alaska, College, September 5, 1958.Undertaken in part with Federal Aid to Wildlife Restoration Funds under Alaska Pittman-Robertson Project Number W-3-R

Ariel - Volume 5 Number 5

Editors Mark Dembert J. D. Kanofsky Entertainment Robert Breckenridge Joe Conti Gary Kaskey Photographer Scot Kastner Overseas Editor Mike Sinason Circulation Jay Amsterdam Humorist Jim McCann Staff Ken Jaffe Bob Sklaroff Janet Welsh Dave Jacoby Phil Nimoityn Frank Chervane

Cellular aspect ratio and cell division mechanics underlie the patterning of cell progeny in diverse mammalian epithelia.

Cell division is essential to expand, shape, and replenish epithelia. In the adult small intestine, cells from a common progenitor intermix with other lineages, whereas cell progeny in many other epithelia form contiguous patches. The mechanisms that generate these distinct patterns of progeny are poorly understood. Using light sheet and confocal imaging of intestinal organoids, we show that lineages intersperse during cytokinesis, when elongated interphase cells insert between apically displaced daughters. Reducing the cellular aspect ratio to minimize the height difference between interphase and mitotic cells disrupts interspersion, producing contiguous patches. Cellular aspect ratio is similarly a key parameter for division-coupled interspersion in the early mouse embryo, suggesting that this physical mechanism for patterning progeny may pertain to many mammalian epithelia. Our results reveal that the process of cytokinesis in elongated mammalian epithelia allows lineages to intermix and that cellular aspect ratio is a critical modulator of the progeny pattern