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SOC e Câncer

A dar uma olhada…

Self-Organized Criticality: A Prophetic Path to Curing Cancer

J. C. Phillips
(Submitted on 28 Sep 2012)

While the concepts involved in Self-Organized Criticality have stimulated thousands of theoretical models, only recently have these models addressed problems of biological and clinical importance. Here we outline how SOC can be used to engineer hybrid viral proteins whose properties, extrapolated from those of known strains, may be sufficiently effective to cure cancer.

Subjects: Biomolecules (q-bio.BM)
Cite as: arXiv:1210.0048 [q-bio.BM]
(or arXiv:1210.0048v1 [q-bio.BM] for this version)

Probabilidade de ocorrer um evento maior que o “11 de setembro” ultrapassa os 95%

Statisticians Calculate Probability Of Another 9/11 Attack

According to the statistics, there is a 50 per cent chance of another catastrophic terrorist attack within the next ten years

3 comments

THE PHYSICS ARXIV BLOG

Wednesday, September 5, 2012

Earthquakes are seemingly random events that are hard to predict with any reasonable accuracy. And yet geologists make very specific long term forecasts that can help to dramatically reduce the number of fatalities.

For example, the death toll from earthquakes in the developed world, in places such as Japan and New Zealand, would have been vastly greater were it not for strict building regulations enforced on the back of well-founded predictions that big earthquakes were likely in future.

The problem with earthquakes is that they follow a power law distribution–small earthquakes are common and large earthquakes very rare but the difference in their power is many orders of magnitude.

Humans have a hard time dealing intuitively with these kinds of statistics. But in the last few decades statisticians have learnt how to handle them, provided that they have a reasonable body of statistical evidence to go on.

That’s made it possible to make predictions about all kinds of phenomena governed by power laws, everything from earthquakes, forest fires and avalanches to epidemics, the volume of email and even the spread of rumours.

So it shouldn’t come as much of a surprise that Aaron Clauset at the Santa Fe Institute in New Mexico and Ryan Woodard at ETH, the Swiss Federal Institute of Technology, in Zurich have used this approach to study the likelihood of terrorist attacks.  Read more [+]

Quanto pior, melhor… ou a eleição de Obama

Estava pensando aqui sobre para quem vou torcer (dado que não posso influenciar)  nas eleições dos EUA. Bom, por default, eu deveria torcer pelo Obama, dado que me parece que sou um “liberal” no sentido americano, e não um “conservative”. Por outro lado, acho que sempre temos que pensar no que é melhor para o mundo e não no que é melhor para os EUA ou o Brasil.

Romney e Obama estão, no presente momento, empatados em termos estatísticos. Então, acho que dá para simular dois cenários:

Democratas ganham: dado que a crise econômica continua e não tem fim a vista, isso implicará em mais quatro anos de desgaste para os Democratas. Afinal de contas, os democratas não poderão dizer que Obama herdou uma situação irresponsável de seu antecessor. Os movimentos sociais tipo Ocupar Wall Street ficaram enfraquecidos num governo Democrata. Afinal de contas, se os ricos são (melhor) defendidos pelos republicanos, protestar contra os 1% ou 0.1% ricos não tem muito sentido se os mesmos não estão com o poder (politico). No final de um novo governo Obama, certamente os republicanos irão ganhar, iniciando talvez um longo período conservador. Ou não, pois o cenário abaixo (republicanos ganham) poderia ocorrer, apenas com um delay de quatro anos.

Republicanos ganham: Se os republicanos ganharem, o fosso entre ricos e pobres irá aumentar, os gastos sociais irão diminuir, o ataque a ciência vindo dos criacionista e céticos do clima terá suporte, etc. Ou seja, neste cenário, a situação social/econômica/cultural dos EUA irá piorar sensivelmente. O gap economico entre EUA e China irá diminuir, caminharemos para um mundo bipolar, talvez uma nova guerra fria (contra os “comunistas” chineses). Possivelmente vai haver um período de protestos similar o maio de 1968 (possivelmente por volta de 2018, se o tal ciclo de violência social de 50 anos – um ciclo de Lotka-Volterra ou uma onda num sistema excitável?), apenas para ser reprimido por uma nova reação conservadora.

Bom, para os adeptos do “quanto pior, melhor”, visando uma revolução social, imagino que seja melhor torcer para o Romney, pois assim os republicanos pegam o repique (o segundo fosso do W) da crise econômica em seu auge…

Will the US Really Experience a Violent Upheaval in 2020? Read more [+]

Grandes extinções são mais periódicas do que se pensava

The Death of Nemesis: The Sun’s Distant, Dark Companion

Posted: 11 Jul 2010 09:10 PM PDT

The data that once suggested the Sun is orbited by a distant dark companion now raises even more questions

Over the last 500 million years or so, life on Earth has been threatened on many occasions; the fossil record is littered with extinction events. What’s curious about these events is that they seem to occur with alarming regularity.

The periodicity is a matter of some controversy among paleobiologists but there is a growing consensus that something of enormous destructive power happens every 26 or 27 million years. The question is what?

In this blog, we’ve looked at various ideas such as the Sun’s passage through the various spiral arms of the Milky Way galaxy (it turns out that this can’t explain the extinctions because the motion doesn’t have had the right periodicity).

But another idea first put forward in the 1980s is that the Sun has a distant dark companion called Nemesis that sweeps through the Oort cloud every 27 million years or so, sending a deadly shower of comets our way. It’s this icy shower of death that causes the extinctions, or so the thinking goes.

Today, Adrian Melott at the University of Kansas and Richard Bambach at the Smithsonian Institute in Washington DC re-examine the paleo-record to see if they can get a more accurate estimate of the orbit of Nemesis.

Their work throws up a surprise. They have brought together a massive set of extinction data from the last 500 million years, a period that is twice as long as anybody else has studied. And their analysis shows an excess of extinctions every 27 million years, with a confidence level of 99%.

That’s a clear, sharp signal over a huge length of time. At first glance, you’d think it clearly backs the idea that a distant dark object orbits the Sun every 27 million years.

But ironically, the accuracy and regularity of these events is actually evidence against Nemesis’ existence, say Melott and Bambuch.

That’s because Nemesis’ orbit would certainly have been influenced by the many close encounters we know the Sun has had with other starsin the last 500 million years.

These encounters would have caused Nemesis’ orbit to vary in one of two ways. First, the orbit could have changed suddenly so that instead of showing as a single the peak, the periodicity would have two or more peaks. Or second, it could have changed gradually by up 20 per cent, in which case the peak would be smeared out in time.

But the data indicates that the extinctions occur every 27 million years, as regular as clockwork. “Fossil data, which motivated the idea of Nemesis, now militate against it,” say Melott and Bambuch.

That means something else must be responsible. It’s not easy to imagine a process in our chaotic interstellar environment that could have such a regular heart beat; perhaps the answer is closer to home.

There is a smidgeon of good news. The last extinction event in this chain happened 11 million years ago so, in theory at least, we have plenty of time to work out where the next catastrophe is coming from.

Either way, the origin of the 27 million year extinction cycle is hotting up to become one of the great scientific mysteries of our time. Suggestions, if you have any, in the comments section please.

Ref: arxiv.org/abs/1007.0437: Nemesis Reconsidered

Segundo vulcão maior e mais potente pode entrar em erupção na Islândia

PUBLICIDADE

Após o caos aéreo na Europa, causado pela erupção do vulcão Eyjafjallojkull, que causou transtornos e prejuízos a companhias aéreas e passageiros em todo o mundo, um vulcão ainda maior e mais potente ameaça entrar em atividade na Islândia, o Katla, informam especialistas britânicos. Em abril, durante o caos aéreo, especialistas afirmaram que já houve outros casos em que o Katla entrou em erupção após o Eyjafjallojkull, entrar em atividade.

“Uma erupção a curto prazo do vulcão Katla, maior e mais potente que a do Eyjafjallojkull, é uma grande possibilidade”, afirma os especialistas do Instituto para a Redução de Riscos e do Número de Catástrofes, ligado ao University College London (UCL).

Binod Joshi/AP
Turistas franceses retidos no Nepal após nuvem ce cinzas vulcânicas; prejuízos são de R$ 2,9 bi
Turistas retidos no Nepal após nuvem de cinzas vulcânicas; prejuízos são de R$ 2,9 bilhões

“É muito provável que as erupções na Islândia, moderadas ou importantes, combinadas com condições meteorológicas apropriadas, provoquem uma repetição das perturbações recentes do transporte aéreo”, destaca o relatório.

Outro documento, publicado pelo Instituto de Física de Londres, afirma que cientistas descobriram que as nuvens de cinzas vulcânicas que sobrevoaram recentemente na Escócia geravam uma carga elétrica que pode ter danificado os aviões.

Katla

Em abril, durante o auge da erupção do Eyjafjallojkul, vulcanologistas islandeses chegaram a afirmar que uma erupção embaixo do glaciar Eyjafjallojkull poderia levar o vulcão Katla a entrar em atividade.

O Katla tem uma camada muito mais grossa de gelo na sua superfície e foi o magma tocando o gelo no Eyjafjallajokull que provocou a grossa nuvem de fumaça e pó que parou o tráfego aéreo europeu por seis dias. Ele entrou em erupção pela última vez em 1918.

Na época cientistas manifestaram preocupação dizendo que as explosões de lava poderiam ter reflexo no vulcão vizinho, causando uma erupção no Monte Katla, um vulcão “extremamente poderoso” localizado debaixo de uma geleira próxima.

“O Eyjafjallajokull dificilmente faz um movimento sem o Monte Katla querer entrar em ação”, disse Pall Einarsson, um geofísico na Universidade da Islândia. “É, portanto, de extrema importância observar os eventos com cuidado”.

Uma erupção no Monte Katla poderia derreter grandes quantidades de gelo e causar enormes inundações, potencialmente afetando uma cidade próxima de 300 pessoas, afirmou Einarsson. Três erupções anteriores do Eyjafjallajokull causaram erupções no Katla.

Atividade sísmica e UFOs

Existe uma certa correlação temporal entre o fenômeno El Ninõ e número de UFOs reportados. Isso sugere que boa parte dos UFOs corresponde a um fenômeno natural. Por outro lado, existe uma correlação entre atividade sísmica e o El Ninõ. Finalmente, existe correlação espacial entre UFOs e sítios com falhas geológicas. Seria possível que fortes campos eletromagnéticos emitidos por rupturas sísmicas induzissem alucinações em formato de bolas e discos luminosos, conforme o artigo abaixo?

Magnetically-Induced Hallucinations Explain Ball Lighting Say Physicists

Posted: 10 May 2010 09:10 PM PDT

Powerful magnetic fields can induce hallucinations in the lab, so why not in the real world too?

Transcranial magnetic stimulation (TMS) is an extraordinary technique pioneered by neuroscientists to explore the workings of the brain. The idea is to place a human in a rapidly changing magnetic field that is powerful enough to induce currents in neurons in the brain. Then sit back and see what happens.

Since TMS was invented in the 1980s, it has become a powerful way of investigating how the brain works. Because the fields can be tightly focused, it is possible to generate currents in very specific areas of the brain to see what they do.

Focus the field in the visual cortex, for example, and the induced eddys cause the subject to ‘see’ lights that appear as discs and lines. Move the the field within the cortex and the subject sees the lights move too.

All that much is repeatable in the lab using giant superconducting magnets capable of creating fields of as much as 0.5 Tesla inside the brain.

But if this happens in the lab, then why not in the real world too, say Joseph Peer and Alexander Kendl at the University of Innsbruck in Austria. They calculate that the rapidly changing fields associated with repeated lightning strikes are powerful enough to cause a similar phenomenon in humans within 200 metres.

To be sure, this is a rare event. The strike has to be of a particular type in which there are multiple return strokes at the same point over a period of a few seconds, a phenomenon that occurs in about 1-5 per cent of strikes, say Peer and Kendl.

And the observer has to be capable of properly experiencing the phenomenon; in other words uninjured. “As a conservative estimate, roughly 1% of (otherwise unharmed) close lightning experiencers are likely to perceive transcranially induced above-threshold cortical stimuli,” say Peer and Kendl. They add that these observers need not be outside but could be otherwise safely inside buildings or even sitting in aircraft.

So what would this kind of lightning-induced transcranial stimulation look like to anybody unlucky enough to experience it? Peer and Kendl say it may well look like the type of hallucinations induced by lab-based tests, in other words luminous lines and balls that appear to float in space in front of the subject’s eyes.

It turns out, of course, that there are numerous reports of these types of observations during thunder storms. “An observer reporting this experience is likely to classify the event under the preconcepted term of “ball lightning”,” say Kendl and Peer.

That’s an interesting idea: that a large class of well-reported phenomenon may be the result of hallucinations induced by transcranial magnetic stimulation.

A difficult idea to test, to be sure, but no less interesting for it. And it raises an important question: in what other circumstances are ambient fields large enough to trigger hallucinations of one kind or another?

Ref: arxiv.org/abs/1005.1153: Transcranial Stimulability Of Phosphenes By Long Lightning Electromagnetic Pulses

Terremoto no Haiti, hora a hora

A blogosfera é uma rede sensorial que podemos seguir hora a hora no Blogpulse. O número de posts em inglês é de cinco a seis vezes maior que em português ou castelhano (ver abaixo). Mas o número de posts sobre o Haiti é de três vezes a quase uma igualdade. Existem muitos brasileiros na missão de paz no Haiti (e foi noticiado agora que Zilda Arns morreu no terremoto). Ou seja, na blogosfera como na vida, dói mais quanto mais próximo estamos uns dos outros.

Porque os físicos estatísticos computacionais são tão espertos?

Biology, Sociology, Geology by Computational Physicists

(Monograph Series on Nonlinear Science and Complexity)

Stauffer, Dietrich, Oliveira, Suzana Moss de, Oliveira, Paulo Murilo Castro de and Martins, Jorge Simoes de Sa

Elsevier: Amsterdam, 2006
ISBN 0444521461 (pb)
Comprar aqui.

Reviewed by
Frank Schweitzer and Markus Geipel
ETH Zurich, Switzerland

“Physicists pretend not only to know everything, but also to know everything better. This applies in particular to computational statistical physicists like us”. These are the very first two sentences of the book reviewed here. In a nutshell, the authors point the reader at their position on approaching phenomena as diverse as biological aging and speciation (chapters 3, 4), languages (chapter 5) or earthquakes (chapter 7).

What is special about Biology, Sociology, Geology by Computational Physicists? First of all the fact that the authors approach these topics without the burden of frameworks and know how, immanent to these disciplines. Thus, compared to the predominant doctrine, they exhilarate the reader with a fresh, diametrical and sometimes odd perspective.

In this respect, the authors follow their predecessor book Evolution, Money, War and Computers, where also a plethora of topics in various scientific disciplines is explored. Common to both books, statistical physics and computer simulations are creatively used to explain the most diverse phenomena. While the predecessor book had a strong bias towards biological aging, the new one treats the different subjects more equally.

Albeit, in-depth analysis of the topics discussed is not the authors intention. They rather prefer a reductionistic, sometimes a somewhat superficial way of presenting the problem under consideration, with a strong bias towards their own toy models. The KISS (“Keep it simple and stupid”) principle flourishes throughout the book, which is good and bad at the same time. It is good because their computer simulations allow the reader to get a first insight into the dynamics of a model without being fed with all details. In many cases, this seems to be a good starting point for further investigations, and scientists obsessed with the idea of putting as much as possible into their computer simulations could be impressed by the results obtained already from basic models. The downside of that approach, as always with the KISS principle, is the pitfall of oversimplification.

For the social scientist, the models discussed in Chapter 6 “Social Science” could be of special interest. Here, the topics range from retirement demography, self-organization of hierarchies and opinion dynamics to traffic jams, networks, social percolation and legal physics (each with a special subsection, about 50 pages in total). Again, compactness and boldness in interpretation is a trademark of the authors style. In chapter 6.2 for example they give insights into the self-organization of social hierarchies in mere four pages. More specifically, they extend one particular model, the Bonabeau model, and courageously interpret the simulation results – a two dimensional curve – as the “transition from the more egalitarian nomadic society to agricultural life with property of land, cities and nobility” (188).

Different chapters vary in difficulty and compactness, though. Thus, even the unprepared reader will find chapters accessible to him. In general the book is aimed at those who are to some extend familiar with the disciplines discussed. Some technical terms or concepts such as “Hamming Distance” or “Diploid” should ring a bell, as they are only very briefly outlined. As long as one is not too much interested in the theories underlying the specific models, the book gives a short, but mostly entertaining view of a variety of current topics from different disciplines.

Another positive aspect of the book is the appendix chapter, which provides a rich pool of lean Fortran program listings related to the topics discussed in the different chapters. These listings shall “encourage readers to start their own simulation” as the authors point out and they are in fact quite simple to understand.

The reference section impresses as a rather complete list of papers mainly from the field of interdisciplinary physics. On a second glimpse, one realizes that the list is only of limited use because no titles of the papers are given at all (if only to give a hint about their content) and the reader has to be familar with the partially cryptic abbreviaton of the journal names from various fields.

All in all, Biology, Sociology, Geology by Computational Physicists is a book for the open minded reader and the connoisseur of interdisciplinary physics. They will, in particular, like the fresh and homourous, sometimes ironic style in which the authors comment about their own research and may obtain hints for further research. So, to quote the authors at the very end: “keep our minds open, without demanding immediate large-scale applications”.

Terremotos e avalanches na blogosfera

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Música dos Terremotos

Neurofisiólgos costumam ouvir os spikes de neurônios em aplificadores em em vez de apenas visualizá-los em osciloscópios. Dizem que isso se faz porque o ouvido humano é mais sensível a detetar padrões do que o sistema visual.

Idéia: imitando este vídeo, faça uma escala associando magnitudes dos terremotos com tons, de um modo psicofisicamente significativo. Em princípio, se os eventos são descorrelacionados, deveriamos ter apenas uma “música fractal”, ou seja, notas musicais tiradas de uma distribuição tipo lei de potência.

Mas os pre-shocks, os after-shoks e os terremotos correlacionados ou disparados em avalanches globais produzirias assinaturas que poderiam ser facilmente detetáveis acusticamente. Ou não?

Ufos e Terremotos

Por falar em terremotos (sim, eu trabalhei em modelos de terremotos com criticalidade auto-organizada), faz tempo que se fala em uma conexão entre UFOs e terremotos. Me perguntaram outro dia porque virei cético quanto a UFOs e isto é parcialmente a resposta (quando adolescente eu descobri essa conexão – e depois descobri que Persinger publicou primeiro, argh!).
No Blogpulse a correlação também apareceu…
Sightings of aliens have been linked to electrical fields caused by quakes.

Jerome Burne

You are driving along an empty road late at night when several large, disc-shaped lights suddenly fly in front of you. One stops and hovers above the road. Your ignition cuts out and your curiosity turns to panic. The glowing ball is on the ground in front of you now. Is that a figure emerging..? You are having a UFO experience which could mean: a) you have actually been contacted by

aliens; b) you are having hallucinations, are stressed or schizophrenic, or it is a false memory implanted later under hypnosis; c) you have walked on to the set of a sci-fi B movie in the making. But there is another possibility – you might simply be receiving advance warning of an earthquake. This is the theory of Michael Persinger, a professor of psychology and neuroscience at Laurentian University in Sudbury, Ontario, who is the subject of a television documentary tomorrow night [Ref: Equinox : Identified Flying Objects]. Mr Persinger’s research project is odd and intriguing.

For 20 years he has been working on a theory that connects not only UFOs and earthquakes, but also powerful electromagnetic fields and an explanation of paranormal beliefs in terms of unusual brain activity. “Beneath the Earth’s surface seethe massive geophysical forces,” says Mr Persinger. “Around the time of an earthquake particularly, the tremendous seismic pressure on rock crystals produces powerful local electrical fields, measuring several thousand volts per metre, more than enough to produce balls or columns of light.” Depending on the culture, these can be interpreted as dragons, mystical visions or flying saucers. In one study Mr Persinger found that 90 per cent of the accounts of luminous events in the sky reported between 1820 and 1926 could be linked to a rise in seismic activity at the same time.
More recently, noting the connection between large dams and a build-up of seismic strain he has found a link between UFO reports and five major American dams.An apparent epidemic of UFO reports in Manitoba, Canada, in 1975 was found to have coincided with a severe earthquake in the area. An apparent rash of UFOs in Missouri during 1973 and 1974 occurred at just the same time as the only two recently recorded earthquakes in the region. Two British researchers, Paul McCartney, a geochemist, and Paul Devereux, writer, have found that Clev Hill in Wiltshire, long a favourite haunt of UFO spotters lies, beside the only two fault lines in the area. But these geomagnetic fields are not only producing balls of light, they are also capable of having an effect on the brain. In a series of laboratory studies Mr Persinger has found that electromagnetically stimulating two parts of the brain involved with memory and meaning – the amygdala and the hippocampus – can suddenly release a flood of images from the past that are automatically imbued with a tremendous sense of reality and importance. He has also found that stimulating another area, the temporal lobes, can produce all sorts of mystical experiences, out-of-the-body sensations and other apparently paranormal phenomena.
Susan Blackmore, a psychologist and presenter of the television programme on Mr Persinger, has reported how she felt when her temporal lobes were stimulated with a pulsed magnetic field of the same intensity as that of a commercially available relaxation device. “It felt for all the world as though two hands had grabbed my shoulders and yanked me upright… I felt as though I had been stretched halfway up to the ceiling. Then came the emotions, Totally out of the blue, but in tensely and vividly, I suddenly felt angry. Later… I was terrified.” So not only can the electromagnetic field produced by tectonic strain produce UFO-like luminous shapes but the subjective experiences of those having close encounters begin to make sense too. Reports of blacking out as the “ship” gets near and subsequent amnesia suggest an assault on the brain’s electrical system, which could also explain why car engines often fail.Then there are sinister aliens and sexual experiments, “Temporal lobe stimulation can evoke the feeling of a presence, disorientation, and perceptual irregularities,” says Mr Persinger. “It can also activate images stored in the subject’s memory, including nightmares and monsters that are normally suppressed.” Strong magnetic fields affect the genitals,sensations which can be interpreted as “spacemen did tests on my genitals”.
Mr Persinger’s theory also implies that UFO spotting could seriously damage your health. “Exposure to intense magnetic fields has been associated with an increase in cancers of the blood, brain and sexual organs and a rise in depression, suicide and alcohol abuse,” says Mr Persinger. He notes that of three children who were closest to the famous lights, interpreted as a vision of Virgin Mary, at Fatima in Portugal in 1917, two died within three years, one from a solid lung tumour.

Chacoalhando vulcões

Parece que terremotos podem disparar erupções vulcânicas a centenas de quilômetros de distância…

Via Physics Today:

Shaken volcanoes blow their tops

ScienceNOW: As if people living in the world’s major earthquake zones don’t have enough to worry about, a new analysis of two of the biggest quakes of the past century reveals a sharp spike in volcanic eruptions after the events, sometimes in volcanoes located hundreds of kilometers from the epicenters. The researchers are quick to point out that not all large earthquakes trigger eruptions, but the work does suggest that in areas where both earthquakes and volcanoes are common, such as in Indonesia, increased volcanic activity could be looming in the wake of big temblors.

Minha contribuição: comparando as tags “earthquake” e “volcano” no Blogpulse. Embora a maior parte dos posts se refere a eventos passados ou metáforas (acho que isso forma a linha média), é possível ver dois possíveis eventos desse tipo nos dias 01 e 15 de novembro passado. E, ao contrário dos terremotos maiores, puntais (29 de julho e 6 de setembro), a atividade vulcanica parece coincidir com atividade sísmica mais duradoura, na forma dos “morrinhos” mais extensos de comentários da curva. O que acham?

Terremoto na Blogosfera

Portuguese (Português) posts that contain Terremoto per day for the last 30 days.
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O mistério do atrito

Paper interessante, capa do PRL. Muitos estudantes não sabem que tópicos simples como atrito não são entendidos pelos físicos e são temas de pesquisa atual.

Modeling Friction on a Mesoscale: Master Equation for the Earthquakelike Model

O. M. Braun
Institute of Physics, National Academy of Sciences of Ukraine, 46 Science Avenue, 03028 Kiev, Ukraine
M. Peyrard
Ecole Normale Supérieure de Lyon, 46 Allée d’Italie, 69364 Lyon Cédex 07, France
(Received 23 November 2007; published 25 March 2008)
The earthquakelike model with a continuous distribution of static thresholds is used to describe the properties of solid friction. The evolution of the model is reduced to a master equation which can be solved analytically. This approach naturally describes stick-slip and smooth-sliding regimes of tribological systems within a framework which separates the calculation of the friction force from the studies of the properties of the contacts.
©2008 The American Physical Society
URL: http://link.aps.org/abstract/PRL/v100/e125501
doi:10.1103/PhysRevLett.100.125501
PACS: 81.40.Pq, 46.55.+d
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