Quantitative Aspects of the Computation Performed by Visual Cortex in the Cat, With a Note on a Function of Lateral Inhibition

Work reported herein was conducted at the Artificial Intelligence Laboratory, a Massachusetts Institute of Technology research program supported in part by the Advanced Research Projects Agency of the Department of Defense and monitored by the Office of Naval Research under Contract Number N00014-70-A-0362-0005. Working Papers are informal papers intended for internal use.A quantitative summary is given of the computation that is performed by visual cortex in the cat. Part of this computation seems to be achieved using a sample-and-average technique; some quantitative features of this technique are briefly set out.MIT Artificial Intelligence Laborator

Kainic acid-induced eye enlargement in chickens: differential effects on anterior and posterior segments

Intravitreal injections of kainic acid were used to examine the significance of normal retinal activity for eye growth in chickens, this acid being chosen because of its known, selective neurotoxic effects on cells in the chicken retina. A 6 nmole dose of kainic significantly reduces amacrine cell numbers when used in very young chickens, while higher doses of kainic acid also affect bipolar and horizontal cell numbers. The effects of intravitreal injection of kainic acid on eye growth were assessed 4 weeks after treatment. A 200 nmole dose of kainic acid, used with day-old and 14-day-old chickens, had opposing effects on the anterior and posterior segments of the eye; while growth of the anterior segment was inhibited, the posterior segment was enlarged, predominantly in the equatorial direction. A 20 nmole dose of this acid similarly affected growth in 14-day-old chickens, but in day-old chickens, the anterior segment was also enlarged and the overall eye enlargement had an axial bias. Myopia was the most common refractive error associated with both patterns of development. A 2 nmole dose of kainic acid was without effect on eye growth. Parallels are drawn between these eye enlargement phenomena and those described in chickens whose visual environments have been manipulated. Our results indicate that normal retinal activity is fundamental to normal eye growth in chickens, and furthermore, that growth of the anterior and posterior segments of the chicken eye are independently regulated

Electroreception In monotremes

I will briefly review the history of the bill sense of the platypus, a sophisticated combination of electroreception and mechanoreception that coordinates information about aquatic prey provided from the bill skin mechanoreceptors and electroreceptors, and provide an evolutionary account of electroreception in the three extant species of monotreme (and what can be inferred of their ancestors). Electroreception in monotremes is compared and contrasted with the extensive body of work an electric fish, and an account of the central mechanoreceptive and electroreceptive input In the somatosensory neocortex of the platypus, where sophisticated calculations seem to enable a complete three-dimensional fix on prey, is given

Observations of the Eastern Maine Coastal Current and Its Offshore Extensions in 1994

Cold surface temperatures, reflecting Scotian Shelf origins and local tidal mixing, serve as a tracer of the Eastern Maine Coastal Current and its offshore extensions, which appear episodically as cold plumes erupting from the eastern Maine shelf. A cold water plume emanating from the Eastern Maine Coastal Current in May 1994 was investigated using advanced very high resolution radiometer (AVHRR) imagery, shipboard surveys of physical and biochemical properties, and satellite-tracked drifters. Evidence is presented that suggests that some of the plume waters were entrained within the cyclonic circulation over Jordan Basin, while the major portion participated in an anticyclonic eddy at the distal end of the plume. Calculations of the nitrate transported offshore by the plume show that this feature can episodically export significant quantities of nutrients from the Eastern Maine Coastal Current to offshore regions that are generally nutrient depleted during spring-summer. A series of AVHRR images is used to document the seasonal along-shelf progression of the coastal plume separation point. We speculate on potential causes and consequences of plume separation from the coastal current and suggest that this feature may be an important factor influencing the patterns and overall biological productivity of the eastern Gulf of Maine

Observations of the Eastern Maine Coastal Current and Its Offshore Extensions in 1994

Cold surface temperatures, reflecting Scotian Shelf origins and local tidal mixing, serve as a tracer of the Eastern Maine Coastal Current and its offshore extensions, which appear episodically as cold plumes erupting from the eastern Maine shelf. A cold water plume emanating from the Eastern Maine Coastal Current in May 1994 was investigated using advanced very high resolution radiometer (AVHRR) imagery, shipboard surveys of physical and biochemical properties, and satellite-tracked drifters. Evidence is presented that suggests that some of the plume waters were entrained within the cyclonic circulation over Jordan Basin, while the major portion participated in an anticyclonic eddy at the distal end of the plume. Calculations of the nitrate transported offshore by the plume show that this feature can episodically export significant quantities of nutrients from the Eastern Maine Coastal Current to offshore regions that are generally nutrient depleted during spring-summer. A series of AVHRR images is used to document the seasonal along-shelf progression of the coastal plume separation point. We speculate on potential causes and consequences of plume separation from the coastal current and suggest that this feature may be an important factor influencing the patterns and overall biological productivity of the eastern Gulf of Maine

Kuroshio Intrusion and the Circulation in the South China Sea

The Princeton Ocean Model is used to study the circulation in the South China Sea (SCS) and its seasonal transition. Kuroshio enters ( leaves) the SCS through the southern ( northern) portion of the Luzon Strait. The annually averaged net volume flux through the Luzon Strait is similar to2 Sv into the SCS with seasonal reversals. The inflow season is from May to January with the maximum intrusion of Kuroshio water reaching the western SCS during fall in compensation of summertime surface offshore transport associated with coastal upwelling. From February to April the net transport reverses from the SCS to the Pacific. The intruded Kuroshio often forms an anticyclonic current loop west of the Luzon Strait. The current loop separates near the Dongsha Islands with the northward branch continuously feeding the South China Sea Warm Current (SCSWC) near the shelf break and the westward branch becoming the South China Sea Branch of Kuroshio on the slope, which is most apparent in the fall. The SCSWC appears from December to February on the seaward side of the shelf break, flowing eastward against the prevailing wind. Diagnosis shows that the onshore Ekman transport due to northeasterly monsoon generates upwelling when moving upslope, and the particular distributions of the density and sea level associated with the cross shelf motion supports the SCSWC

The role of framing mechanisms in explaining system wide change: the case of the Northern Ireland conflict and peace process

System-wide change is often challenging to achieve due to complex and fragmented institutions, dispersed and diffused power structures, confidence sapping histories of failure and the influence of multiple and over-lapping fields. This study examines how a large complex system wide problem such as the Northern Ireland Conflict and Peace Process was paradoxically opened up and made more receptive to change by widening of the way the problem was framed. We demonstrate how and why the framing enables the mobilisation of cooperation and the delivery of contextually appropriate collective action critical to the achievement of outcomes in system wide change processes. More specifically, we examine how and why such complex and precarious processes emerge over extended timescales through four mechanisms: frame contesting, reframing, frame reproduction and frame defending. Each of these mechanisms is agentic, dynamic, purposive and politically charged. The time series analysis of these interlinked mechanisms is a crucial and innovative feature of the study. We encourage management and organizational scholars to elevate their gaze to system-wide changes so emblematic of contemporary society and offer an outline agenda for research

The golden circle: A way of arguing and acting about technology in the London ambulance service

This paper analyses the way in which the London Ambulance Service recovered from the events of October 1992, when it implemented a computer-aided despatch system (LASCAD) that remained in service for less than two weeks. It examines the enactment of a programme of long-term organizational change, focusing on the implementation of an alternative computer system in 1996. The analysis in this paper is informed by actor-network theory, both by an early statement of this approach developed by Callon in the sociology of translation, and also by concepts and ideas from Latour’s more recent restatement of his own position. The paper examines how alternative interests emerged and were stabilized over time, in a way of arguing and acting among key players in the change programme, christened the Golden Circle. The story traces four years in the history of the London Ambulance Service, from the aftermath of October 1992 through the birth of the Golden Circle to the achievement of National Health Service (NHS) trust status. LASCAD was the beginning of the story, this is the middle, an end lies in the future, when the remaining elements of the change programme are enacted beyond the Golden Circle

Let’s sculpt it! Experiencing the role of context in coaching

This exercise aims to familiarize students with the under-discussed topic of the role of context in coaching through a physical activity. It consists of a Group Sculpture – a combination of Socio-drama, Systemic Constellation, Social Presencing Theater – drawing from a coaching case of an ethical dilemma, using the placement and arrangement of participants to represent the stakeholders and context (economic, legal, sociological, etc.). The visual and embodied representation aims to raise awareness and develop understanding of the invisible, but often felt contextual factors at play in coaching, to generate reflection about their influence, and to offer insights on how to identify and embrace them. This activity is primarily aimed for coaching educators and supervisors, but a slightly adapted version could expand its benefits to a more general audience of managers and leaders