“One of the big success stories, and the first example of information processing by the nervous system, was the discovery that the nerve cells in the eye inhibit their neighbors, which allows the eye to accentuate edges,” said Richard Kramer, UC Berkeley professor of molecular and cell biology. “This is great if you only care about edges. But we also want to know about the insides of objects, especially in dim light.”

This terrific story comes from the terrific Terra Daily
Why the eye is better than a camera at capturing contrast and faint detail simultaneously

Kramer and former graduate student Skyler L. Jackman, now a post-doctoral fellow at Harvard University, discovered that while light-sensitive nerve cells in the retina inhibit dozens of their close neighbors, they also boost the response of the nearest one or two nerve cells.

That extra boost preserves the information in individual light detecting cells – the rods and cones – thereby retaining faint detail while accentuating edges, Kramer said. The rods and cones thus get both positive and negative feedback from their neighbors.

“By locally offsetting negative feedback, positive feedback boosts the photoreceptor signal while preserving contrast enhancement,” he said.

Jackman, Kramer and their colleagues at the University of Nebraska Medical Center in Omaha report their findings in the journal PLoS Biology. Kramer also will report the findings at the 2011 annual meeting of the Association for Research in Vision and Ophthalmology in Ft. Lauderdale, Fla.

Read the rest of the article at: Why the eye is better than a camera at capturing contrast and faint detail simultaneously

Cones normally release the neurotransmitter glutamate in the dark, while light decreases glutamate release. This graph of neurotransmitter release shows what happens when cone cells are exposed to a dark spot in a light background (top) under various scenarios, including no feedback (green trace) and only negative feedback from horizontal cells (red trace). Negative feedback to many cones enhances edges, but would decrease detail in dark areas were it not for newly discovered positive feedback that is localized to only a few cone cells (blue trace). Credit: Richard Kramer lab, UC Berkeley

The worm then appears to have been introduced into Natanz via infected laptops or USB drives. There, Stuxnet infected the Siemens control systems and, specialists say, manipulated centrifugal speeds to a degree that caused permanent damage to the motors.

This article is derived from Stuxnet: five companies used as spring-boards – The H Security: News and Features which was taken from Symantics papers that can be seen here: Updated W32.Stuxnet Dossier is Available | Symantec Connect

It is interesting to the community because it shows that an attack on somewhat secure, but somewhat monoculture systems can be done. And since we have somewhat secure, but somewhat monoculture systems, it is a lesson toward the premise of being constantly vigilant.

Symantec managed to trace the worm’s dissemination pathways and infection figures because Stuxnet itself apparently logs the computers it infects. The logged information contained exact timings and served as the basis for Symantec’s analyses. According to the AV vendor, 3,280 unique samples of the worm were responsible for approximately 12,000 infections.

Reportedly, the first attack took place in June 2009, and further attacks followed in July 2009, March 2010, April 2010 and May 2010. Various organisations were targeted repeatedly by the Stuxnet authors, and some computers were successfully infected several times.

The creators of the worm deployed three variants of Stuxnet via targeted attacks, but only the variant deployed in March contained what was a zero-day exploit for the LNK hole in Windows at that time. Using the timestamps in the compiled code, Symantec concluded that the first infection was already successful only 12 hours after the first version of Stuxnet was completed.

The new analyses show that Stuxnet actually contained two sabotage routines to infect and manipulate two separate types of control, but that the second routine was incomplete and disabled. Experts assume that the developers ran out of time.