Deficit of temporal dynamics of detection of a moving object during egomotion in a stroke patient: a psychophysical and MEG study

To investigate the temporal dynamics underlying object motion detection during egomotion, we used psychophysics and MEG with a motion discrimination task. The display contained nine spheres moving for 1 second, eight moved consistent with forward observer translation, and one (the target) with independent motion within the scene (approaching or receding). Observers's task was to detect the target. Seven healthy subjects (7HS) and patient PF with an infarct involving the left occipital-temporal cortex participated in both the psychophysical and MEG study. Psychophysical results showed that PF was severely impaired on this task. He was also impaired on the discrimination of radial motion (with even poorer performance on contraction) and 2D direction as well as on detecting motion discontinuity. We used anatomically constrained MEG and dynamic Granger causality to investigate the direction and dynamics of connectivity between the functional areas involved in the object-motion task and compared the results of 7HS and PF. The dynamics of the causal connections among the motion responsive cortical areas (MT, STS, IPS) during the first 200 ms of the stimulus was similar in all subjects. However, in the later part of the stimulus (>200 ms) PF did not show significant causal connections among these areas. Also the 7HS had a strong, probably attention modulatory connection, between MPFC and MT, which was completely absent in PF. In PF and the 7HS, analysis of onset latencies revealed two stages of activations: early after motion onset (200–400 ms) bilateral activations in MT, IPS, and STS, followed (>500 ms) by activity in the postcentral sulcus and middle prefrontal cortex (MPFC). We suggest that the interaction of these early and late onset areas is critical to object motion detection during self-motion, and disrupted connections among late onset areas may have contributed to the perceptual deficits of patient PF.Published versio

Deficit Reduction Through Diversity: How Affirmative Action at the FCC Increased Auction Competition

In recent auctions for paging licenses, the Federal Communications Commission has granted businesses owned by minorities and women substantial bidding credits. In this article, Professors Ayres and Cramton analyze a particular auction and argue that the affirmative action bidding preferences, by increasing competition among auction participants, increased the government's revenue by $45 million. Subsidizing the participation of new bidders can induce established bidders to bid more aggressively. The authors conclude that this revenue- enhancing effect does not provide a sufficient constitutional justification for affirmative action-but when such justification is independently present, affirmative actions can cost the government much less than is currently thought.Auctions; Affirmative Action

Control of the isoperimetric deficit by the Willmore deficit

In the class of smoothly embedded surfaces of sphere type we prove that the isoperimetric deficit can be controlled by the Willmore deficit

The $1 Trillion Wage Deficit

The strong rise in the U.S. stock market since the spring and the return to positive economic growth in the third quarter of this year have created a consensus among economists that the Great Recession is very likely over. Unfortunately, the end of the official recession will have little visible impact on U.S. labor markets until almost 2012. Within that time, this paper estimates that U.S. workers will have lost over $1 trillion in wages and salaries,$150 billion more than the 10-year costs of proposed health care reform legislation.recession, wages, labor, unemployment

Philanthropy's Awareness Deficit

Engaged Americans show limited knowledge of foundations and struggle to identify their impact on communities or issues they care about, according to a recent survey by Harris Interactive. But there is a silver lining: they still express positive feelings towards foundations and their social value. Read about these and other survey findings in this Philanthropy Awareness Initiative Digest