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In trying to understand the topological component of error tolerance, we can get help from a field of physics known as percolation. Percolation theory tells us that if we randomly remove nodes, then at some critical fraction, fc, the network should fragment into tiny, non-communicating islands of nodes. To our considerable surprise, simulations on scale-free networks do not support this prediction. Even when we remove up to 80% of the nodes, the remainder still form a compact cluster (figure 4). The mystery was resolved last year by Reuven Cohen of Bar-Ilan University in Israel and co-workers. They showed that as long as the connectivity exponent G is less than three (which is the case for most real networks, including the Internet) the critical threshold for fragmentation is fc = 1. This is a wonderful demonstration that scale-free networks cannot be broken into pieces by the random removal of nodes, a result also supported by the independent calculations of Duncan Callaway and collaborators at Cornell University. This extreme robustness to failures is rooted in the inhomogeneous topology of the network. The random removal of nodes is most likely to affect small nodes rather than hubs with many links because nodes significantly outnumber hubs. Therefore the removal of a node does not create a significant disruption in the network topology, just like the closure of a small local airport has little impact on international air traffic. The bad news is that the inhomogeneous topology has its drawbacks as well. Scale-free networks are rather vulnerable to attacks. Indeed, the absence of a tiny fraction of the most-connected nodes will cause the network to break into pieces. These findings uncovered the underlying topological vulnerability of scale-free networks. While the Internet is not expected to break under the random failure of the routers and lines, well informed hackers can easily design a scenario to handicap the network.

"Recently Romualdo Pastor-Satorras from Universitat Politecnica de Catalunya in Barcelona, Spain, and Allessandro Vespigniani from the International Centre for Theoretical Physics in Trieste, Italy, demonstrated that viruses behave rather differently on scale-free networks compared with random networks. For decades, both marketing experts and epidemiologists have intensively studied so-called diffusion theories. These theories predict a critical threshold for virus spreading. Viruses that are less contagious than a well defined threshold will inevitably die out, while those that are above the threshold will multiply exponentially and eventually reach the whole system. The BarcelonaTrieste group, on the other hand, has found that the threshold for a scale-free network is zero. In other words, all viruses, even those that are only weakly contagious, will spread and persist in the system. This explains why "Love Bug", the most damaging virus so far, is still the seventh most frequent virus, a year after its introduction and supposed eradication. "

Tully and co-workers have combined the data from the four experiments at LEP and found evidence that the Higgs boson has a mass of 114.9 GeV c-2. 'It is a 2.6 sigma effect,' he told PhysicsWeb, 'so there's still a 6 in 1000 chance that what we are seeing are background events, rather than the Higgs.'

The international physics community gives its golden stamp of approval for the existence of a particle is, I believe, 1 in 10 000, and the LEP at CERN would probably have been able to get that accuracy within a year or two had it not been dismantled for something even bigger.

The danish solar physicist Henrik Svensmark claims that there is a close link between solar activity and cloudforming, which again affects average earth temperature. He finds a nice correlations between temperature and the number of solar spots. Some of his theories are being tested at CERN. If I remember correctly the UN climate council has admitted that solar activity was responsible for the rise in temperature in the first half of this century.

The gulf stream is being driven by cold water that sinks in the basin between Greenland and Norway. The german physicist Stefan Rahmstorf claims that when the icecap melts ic creates a layer of freshwather on top of the ocean. This fresh water is so light that eddies do not form, and therefore it does not sink. His simulations showthat this effect can (within 50 years) force the gulf stream turn west outside spain, leaving northern europe very cold. Computer simulatuons may be largely insecure, but I think that he does show a mechanism by which a 2 degree temperature change end up having a dramatic effect on the climate where I live.

BTW: The american oil industry is sponsoring a lot of scientist to work on reports showing that there is no global warming going on, so we have FUD against FUD.

that I submitted the story on the optical transistor (a different link) on Friday night. Woo hoo.

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Maybe if they used these fully optical transistors it might be faster. However, I have slight doubts about the speed of these babies because of a chemical reaction that is central to their operation. But then again, ordinary silicon transistors are based on the diffusion of electrons, which is slow as hell compared to something purely optical, so these might well turn out a lot faster.

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Um, printer cables (the ones that go to the print head from the main pcb in the printer)? Plastic and metal and pretty flexible. A big goal isn't to have a scrunchable computer, just a more durable one.

Have to agree to your point on Gallium Arsenide though - was my first reaction, I mean they only just got silicon lasing and they reckon it's the best semiconductor?!?

The fact of the matter that it is very easy to get statistical fluctuations of this magnatude in high-energy physics. (insert obligatory comment about the accuracy of political "polls" here) And in the higgs search at CERN they have frequently seen extra events just at the end of their range. (The mass of 114.9 GeV is barely within the range of the accelerator to see at its current energy)

If the higgs exists, it will be found by the LHC. It's enticing to think it's barely beyond LEP's reach, and if the LHC finds it there, the LEP people will bemoan not being able to extend LEP's run just a little bit longer...

Disclaimer: IAP (I Am a Physicist), and have worked on the higgs analysis at CERN (but do not currently). How come more physics people don't post to slashdot? I know you guys read it. ;)

--Bob

there are 6 chances out of 1000 that the Higgs Boson weighs 114.9 Gev.c^-2 according to this article

we covered our top ten a couple of weeks ago. You may want to check it out. http://physicsweb.org

Regards

Paul Guinnessy