Anhinga anhinga

Greg Egan recently designed another of his universes. This one is named "Orthogonal" and is based on symmetry between space and time (instead of the Minkowski space-time the world is based on the 4-dimensional Euclidean space):

http://www.gregegan.net/ORTHOGONAL/ORTHOGONAL.html

A beautiful universe; the role of light is really interesting; very interesting biology with innovative gender and procreation scheme (and more or less familiar social patterns refracted by this physics and biology). "The Clockwork Rocket" appeared this Summer and is the first novel of the planned trilogy, I've just read the Kindle edition, liked it a lot.

The bacterial communication phenomenon that we study is called quorum sensing, which is a process that allows bacteria to communicate using secreted chemical signaling molecules called autoinducers. This process enables a population of bacteria to collectively regulate gene expression and, therefore, behavior.

So a population of bacteria can behave as if it is a single organism.

(Talk at MIT on May 11, 4pm)

http://nature-wonder.livejournal.com/167564.html

В том же журнале хорошая выдержка из беседы с К.Еськовым про эволюцию:

http://nature-wonder.livejournal.com/167238.html

It looks like a real scientist will be our next Secretary of Energy:

http://en.wikipedia.org/wiki/Steven_Chu

(Director of the Berkeley Lab, Nobel Prize for laser cooling and trapping of atoms)

MIT -- Special Lecture Series on

Statistical Physics of Algorithms (or Belief Propagation and Beyond)

Michael (Misha) Chertkov (Theory Division, Los Alamos National Laboratory)

Time: 4-5pm
Date and Room:
Sep 29 Mon 32-141
Oct 01 Wed 32-141
Oct 02 Thur 36-156 (room change: 32-D463 (Star Room))
Oct 27 Mon 32-141
Oct 29 Wed 32-141
Oct 30 Thur 36-156 (room change: 32-D463 (Star Room))
( Read more... )

I've read some recent studies on Darwinist evolution of the computer code, and what is required to make such evolution computationally feasible. Basically, there are two main problems: almost all mutations of a typical piece of code are lethal, and the rewards landscape is too sparse (only goals we care about are rewarded), so the evolutionary process cannot find a "ladder" to climb to the goals. A couple of recent papers present case studies of systems where these problems were sufficiently rectified to enable nontrivial evolution.( Read more... )

University of Wales, Swansea, 30 June - 5 July, 2006

Luca Cardelli: Biological Systems as Reactive Systems.
Martin Davis: The Church-Turing Thesis: Consensus and Opposition.
István Németi: Can general relativistic computers break the Turing barrier?

http://www.nytimes.com/2005/11/06/books/review/06shreeve.html

"In "Bugs in the Brain," he describes a parasite that infects the brains of rats without any effect on their behavior except that they lose their instinctual aversion to the smell of cats and, instead, are drawn to it. Needless to say, such absurdly obliging prey is quickly gobbled up: bad for the rat but great for the parasite, since it can only reproduce inside a cat host."

Yet another suggestion that the line between pathological and functional mechanisms is not well defined:

http://economist.com/science/displayStory.cfm?story_id=4078826

"Brain development may be influenced by genetic parasites"

"[...]Nerve-cell precursors can turn into two types of brain cell besides nerve cells. These other two types have supporting, rather than starring roles in the brain, and cannot transmit nerve impulses. The rat-cell work showed that LINE-1 jumping happens only in precursors that turn into nerve cells, and that it seems to be regulated by a protein called Sox2 that is already known to play a crucial role in the formation of nerve cells. The mouse work showed that LINE-1 was not jumping in any other parts of the body (except, oddly, the sex cells—a result that had been seen before). That suggests it is happening in the brain for a purpose[...]"


(Also I've discovered that you can force LJ to e-mail your own comments to you, I have no idea, why I did not notice this option before; also I am probably going to Provincetown for the weekend --- no Internet access, I think.)