Accurate, Focused Research on Law, Technology and Knowledge Discovery Since 2002

Daily Archives: December 9, 2014

Hummingbirds control hovering flight by stabilizing visual motion

Benjamin Goller and Douglas L. Altshuler – PNAS December 8, 2014

“The avian brain has numerous specializations for navigation and processing visual information, but relatively little is known about how flying birds control their position in space. To study the role of vision in controlling hovering flight, we developed a virtual reality environment where visual patterns could be displayed to a freely flying hummingbird. Normal flight could only be performed if the visual background was completely stationary. In contrast, any motion in the background image caused the birds to lose stability. In natural settings, visual motion is constantly produced when objects and observers move relative to each other. This research demonstrates that flying birds are surprisingly sensitive to movements in their visual field and direct flight to respond to those movements.

Abstract – Relatively little is known about how sensory information is used for controlling flight in birds. A powerful method is to immerse an animal in a dynamic virtual reality environment to examine behavioral responses. Here, we investigated the role of vision during free-flight hovering in hummingbirds to determine how optic flow—image movement across the retina—is used to control body position. We filmed hummingbirds hovering in front of a projection screen with the prediction that projecting moving patterns would disrupt hovering stability but stationary patterns would allow the hummingbird to stabilize position. When hovering in the presence of moving gratings and spirals, hummingbirds lost positional stability and responded to the specific orientation of the moving visual stimulus. There was no loss of stability with stationary versions of the same stimulus patterns. When exposed to a single stimulus many times or to a weakened stimulus that combined a moving spiral with a stationary checkerboard, the response to looming motion declined. However, even minimal visual motion was sufficient to cause a loss of positional stability despite prominent stationary features. Collectively, these experiments demonstrate that hummingbirds control hovering position by stabilizing motions in their visual field. The high sensitivity and persistence of this disruptive response is surprising, given that the hummingbird brain is highly specialized for sensory processing and spatial mapping, providing other potential mechanisms for controlling position.”

FBI 2013 Hate Crime Statistics

“Today, the FBI released its annual Hate Crime Statistics report, which revealed that 5,928 hate crime incidents involving 6,933 offenses were reported by our law enforcement partners to the Bureau’s Uniform Crime Reporting (UCR) Program in 2013. These hate crime incidents impacted a total of 7,242 victims—which are defined as individuals, businesses, institutions, or society… Continue Reading

Annual Income and Earnings Inequality Metrics: 2009-2012

Census: “Using four calendar years (2009-2012) of data from the 2008 Survey of Income and Program Participation panel, this table package presents inequality metrics for annual estimates of personal, family and household income and earnings. The derived inequality measures for each calendar year are the Gini index, the mean log deviation, the Theil index and the… Continue Reading

Economic and Budgetary Effects of Producing Oil and Natural Gas From Shale

CBO – “Recent advances in combining two drilling techniques, hydraulic fracturing and horizontal drilling, have allowed access to large deposits of shale resources—that is, crude oil and natural gas trapped in shale and certain other dense rock formations. As a result, the cost of that “tight oil” and “shale gas” has become competitive with the… Continue Reading

Patients Prescribed Narcotic Painkillers Use More of Them for Longer, Study Finds

New York Times: “While a major public health campaign has had some success in reducing the number of people who take potentially addictive narcotic painkillers, those patients who are prescribed the drugs are getting more of them for a longer time, according to a new study. Nearly half the people who took the painkillers for over… Continue Reading

Study of the CIA’s Detention and Interrogation Program – Unclassified

Senate Select Committee on Intelligence, Committee Study of the Central Intelligence Agency’s Detention and Interrogation Program. Foreword by Senate Select Committee on Intelligence Chairman Dianne Feinstein. Findings and Conclusions – Executive Summary Approved December 13,2012. Updated for Release April 3, 2014. Declassifications Revisions December 3, 2014. “On April 3, 2014, the Senate Select Committee on Intelligence voted to send the Findings and Conclusions and… Continue Reading