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Nicholas Lan

Ancient Egyptians transported pyramid stones over wet sand - 1 views

phys.org/...tians-pyramid-stones-sand.html

science fun

shared by Nicholas Lan on 01 May 14 - No Cached
  • Nicholas Lan on 01 May 14
     
    Apr 30, Physics/General Physics A large pile of sand accumulates in front of the sledge when this is pulled over dry sand (left). On the wet sand (right) this does not happen.
Marcus Maertens

Physics Just made the Axe Cooler - 2 views

www.fromquarkstoquasars.com/ysics-just-made-the-axe-cooler

fun technology

shared by Marcus Maertens on 28 Apr 14 - No Cached
  • Marcus Maertens on 28 Apr 14
     
    Need to chop some wood? Use the Lever Axe!
jmlloren

Insect flight dynamics: Stability and control - 2 views

journals.aps.org/...RevModPhys.86.615

BIO PHY

shared by jmlloren on 09 Jun 14 - No Cached
  • jmlloren on 09 Jun 14
     
    A recently published review on insect flight appeared in Review of Modern Physics. It might be of interest to the biomimetics unit.
Thijs Versloot

Solar singlet fission bends the laws of physics to boost solar power efficiency by 30% ... - 2 views

www.extremetech.com/...t-solar-power-efficiency-by-30

technology science

shared by Thijs Versloot on 19 May 15 - No Cached
LeopoldS and Paul N liked it
  • Thijs Versloot on 19 May 15
     
    Chemists at UCR have found a way of turning a single photon into two excitons, by a process known as singlet fission. By doubling the yield of excitons in a solar cell, you theoretically double the number of electrons produced and could lead to having a max theoretical efficiency of 60% or more in an (organic) solar cell See also DOI: 10.1021/jz500676c - "Singlet Fission: From Coherences to Kinetics"
jcunha

Explosion-Generated Collapsing Vacuum Bubbles Reach 20,000 Kelvin - 1 views

www.physicsforums.com/...uum-bubbles-reach-20000-kelvin

PHY sonoluminescence fun

shared by jcunha on 16 Sep 15 - No Cached
  • jcunha on 16 Sep 15
     
    "In a recent paper published in Physical Review Letters (PRL) Jérôme Duplat and Emmanuel Villermaux developed a method to generate centimeter-sized vacuum bubbles in water with miniature laser-driven explosions, and observed the flash of light produced as the bubble collapsed a not-fully-understood phenomenon known as sonoluminescence." Amazingly they concluded that the temperatrue inside the bubble as it collapses is about 26000 K. At this temperatures some (not me) argue for nuclear fusion... Intriguing stuff!!! Check the videos! Yet another test for the 'Experimental Physics Stagiare' :-)?
  • dejanpetkow on 16 Sep 15
     
    For sure no fusion, that starts appr. from about 20keV, not 20kK. Between both there is still a factor of 11500. What I would rather expect is that the conditions are not appropriate to work with Maxwellian distribution functions. If certain fusion products should be measurable, than this would rather confirm (but not proof) the hypothesis that they do not have Maxwellians but something close to monoenergetic. But most probably they will not measure fusion products, hence no fusion, hence no confusion.
pacome delva

Players attack aerodynamics of the World Cup ball - 3 views

physicsworld.com/...42886

phy aerodynamics world_cup

shared by pacome delva on 10 Jun 10 - Cached
  • pacome delva on 10 Jun 10
     
    when physics comes into public debate... of high interest!!!
  • Joris _ on 10 Jun 10
     
    soon the ball may look like a golf ball ... better aero.
  • Ma Ru on 10 Jun 10
     
    A bad workman blames his tools... P.S. Polish version of this proverb is much nicer, and says that poor ballet dancer blames her skirt... but it's nothing compared to the Russian version, which says about a male ballet dancer who blames his... well, guess yourselves...
pacome delva

Physics - Small-scale hydraulics - 1 views

physics.aps.org/...PhysRevLett.103.144503

phy nan nanofluidic bio

shared by pacome delva on 07 Oct 09 - Cached
  • Taking a cue from biology, scientists are now designing nanofluidic devices in which molecular interactions at the walls of a narrow channel are engineered to control fluid flow.
pacome delva

Metamaterials Probe Changes in Spacetime Structure | Physical Review Focus - 0 views

focus.aps.org/st6

phy metamaterials cosmology

shared by pacome delva on 24 Aug 10 - Cached
  • At the time of the big bang, our universe may not have had exactly three dimensions of space and one of time, according to some theorists. In the 6 August Physical Review Letters, a team proposes a way to observe the postulated transition to our current universe using so-called metamaterials, structures in which the propagation of light can be precisely controlled. Experiments on such structures, they say, could test predictions that a "big flash" of radiation would accompany changes in the structure of spacetime that may have occurred in the early universe.
pacome delva

Rolling rubber bands stretch students - 1 views

physicsworld.com/...43351

phy rubber students

shared by pacome delva on 28 Jul 10 - Cached
  • pacome delva on 28 Jul 10
     
    funny how "basic physics" can still be fashionable
LeopoldS

The surprising motion of ski moguls - Physics Today November 2009 - 2 views

scitation.aip.org/...PrintPTJ

physics PHY kinematic waves

shared by LeopoldS on 28 Feb 10 - Cached
  • LeopoldS on 28 Feb 10
     
    for those lucky ones currently on skis ....
pacome delva

Physics - Outsmarting decoherence in a trapped ion quantum computer - 0 views

physics.aps.org/...PhysRevLett.103.200503

phy quantum_computation ion_trap quantum_physics

shared by pacome delva on 03 Dec 09 - Cached
  • This is the first ion trap demonstration of a set of logical gates that are universal for quantum computation
LeopoldS

Self-organized adaptation of a simple neural circuit enables complex robot behaviour : ... - 3 views

www.nature.com/...nphys1508.html

robotics

shared by LeopoldS on 19 Jan 10 - Cached
  • LeopoldS on 19 Jan 10
     
    is this really worth a nature paper??
  • Luzi Bergamin on 19 Jan 10
     
    Funny to read this question exactly from you, the all and ever fan of anything linked to bio :-) I have read worse papers in nature and in addition it's just "Nature physics", viz. "Nature garbage." Could be that they don't find enough really good stuff to publish in all their topical clones of Nature.
  • Nicholas Lan on 19 Jan 10
     
    francesco already posted this below
pacome delva

Philosophers' Imprint - 5 views

quod.lib.umich.edu/...text-idx

philosophy phy math

shared by pacome delva on 18 Jan 10 - Cached
Nicholas Lan liked it
  • pacome delva on 18 Jan 10
     
    An interesting (free) journal on philosophy, with even some article with mathematics and physics !
  • Luzi Bergamin on 18 Jan 10
     
    Reading the titles somehow reminds me of the most important webpage of the ACT: the Advanced Concepts Generator :-)
  • pacome delva on 18 Jan 10
     
    have you seen the 2 articles on canonical GR ...!
pacome delva

Condensation transition in networks and other complex systems - 4 views

nuweb.neu.edu/...Condensation.html

phy bio complex_networks

shared by pacome delva on 15 Jan 10 - Cached
  • pacome delva on 15 Jan 10
     
    I like this work... it mixes physics, networks and biology ! Anyone heard about her ? Here's an interesting paper found on this website: http://nuweb.neu.edu/gbianconi/condensation.pdf
  • ...3 more comments...
  • Francesco Biscani on 15 Jan 10
     
    Eh... Barabasi is really milking the golden cow :) It seems interesting, even if I don't remember enough from my statistical mechanics classes to truly understand it without a major effort. Maybe you could make a layman's science coffee about it?
  • pacome delva on 15 Jan 10
     
    yeah i could if there's enough interest...? do u know Barabasi ?
  • Francesco Biscani on 15 Jan 10
     
    He's quite well known for his work on scale-free networks: http://en.wikipedia.org/wiki/Albert-L%C3%A1szl%C3%B3_Barab%C3%A1si He's applying them for everything and the kitchen sink :) We have a Barabasi-Albert network topology implemented in PaGMO...
  • Dario Izzo on 16 Jan 10
     
    We worked on this with Luzi a few years back ... while the analogy is original and interesting it fails to capture the dynamics of a network, e.g. if a network has hubs that grow and shrink .... Luzi worked on an extended model to solve this issue, but, if I remember correctly, he got stuck in a computationally very hard problem .... We intended to develop and use the extended model to define relevant characteristic of the ESA network formed by mail exchanges.....
  • nikolas smyrlakis on 18 Jan 10
     
    ...but then the CMS YGT didn't really like the project
santecarloni

Breakthrough Propulsion Physics - 7 views

www.grc.nasa.gov/bpp

propulsion physics space

shared by santecarloni on 26 Jan 11 - Cached
  • santecarloni on 26 Jan 11
     
    The competition is open....
  • Luzi Bergamin on 26 Jan 11
     
    And what does one win in the end? Yet another unfeasible concept to be archived somewhere in a journal? Look at "Millis hypothetical drives"... Give me a break, for sure!!
  • Dario Izzo on 26 Jan 11
     
    I like the sentence "16 peer-reviewed journal articles, and an award-winning website (Warp-When), all for a total investment of less than $1.6M". This gives 100.000 dollars per peer-reviewed paper (we neglect the award-winning web-site under the assumption that is the easy part....). With these number the ACT in 2010 cashed 1.4 millions only in research papers making it an obvious good investment for the European Space Agency also in austerity times!!!
Joris _

Cosmic Log - Volunteers find another prize pulsar - 2 views

cosmiclog.msnbc.msn.com/...eers-find-another-prize-pulsar

phy pulsar @home

shared by Joris _ on 02 Mar 11 - No Cached
LeopoldS liked it
  • Joris _ on 02 Mar 11
  • LeopoldS on 05 Mar 11
     
    like the profiles ... "The clearest evidence for the pulsar's existence was provided by computers operated by two volunteers: Vitaly Shiryaev, a Russian researcher who has a Ph.D. in radio physics; and Stacey Eastham, who does vehicle testing for the British government in Darwen. In his profile, Eastham says he's studying astronomy and physics on the side. He got involved in the Einstein @ Home project because he's interested in "anything space-like, and being able to be part of something like this is right up my street."
santecarloni

Sharpening the Nanofocus: Berkeley Lab Researchers Use Nanoantenna to Enhance... - 0 views

newscenter.lbl.gov/...a-to-enhance-plasmonic-sensing

nan technology

shared by santecarloni on 18 May 11 - No Cached
  • santecarloni on 18 May 11
     
    See Also: Matter & Energy Nanotechnology Optics Physics Materials Science Graphene Organic Chemistry Reference White gold Electromagnetic radiation Nanomedicine Nanoparticle Any use for the smell project? "We have demonstrated resonant antenna-enhanced single-particle hydrogen sensing in the visible region and presented a fabrication approach to the positioning of a single palladium nanoparticle in the nanofocus of a gold nanoantenna,"
Luís F. Simões

Bitcoin P2P Currency: The Most Dangerous Project We've Ever Seen - 10 views

launch.is/...dangerous-project-weve-ev.html

bitcoin p2p money disruptive

shared by Luís F. Simões on 16 May 11 - No Cached
LeopoldS liked it
  • After month of research and discovery, we’ve learned the following:1. Bitcoin is a technologically sound project.2. Bitcoin is unstoppable without end-user prosecution.3. Bitcoin is the most dangerous open-source project ever created.4. Bitcoin may be the most dangerous technological project since the internet itself.5. Bitcoin is a political statement by technotarians (technological libertarians).*6. Bitcoins will change the world unless governments ban them with harsh penalties.
  • The benefits of a currency like this:a) Your coins can’t be frozen (like a Paypal account can be)b) Your coins can’t be trackedc) Your coins can’t be taxedd) Transaction costs are extremely low (sorry credit card companies)
  • An individual with the name -- or perhaps handle -- of Satoshi Nakamoto first wrote about bitcoins in a paper called Bitcoin: A Peer-to-Peer Electronic Cash System.
  • ...1 more annotation...
  • * We made this term up to describe the “good people” of the internet who believe in the fundamental rights of individuals to be free, have free speech, fight hypocrisy and stand behind logic, technology and science over religion, political structure and tradition. These are the people who build and support things like Wikileaks, Anonymous, Linux and Wikipedia. They think that people can, and should, govern themselves. They are against external forms of control such as DRM, laws that are bought and sold by lobbyists, and religions like Scientology. They include splinter groups that enforce these ideals in the form of hacktivism, such as the takedown of the Sony Playstation Network after Sony tried to prosecute a hacker for unlocking its console.
  • Ma Ru on 17 May 11
     
    Sounds good!
  • ...9 more comments...
  • pacome delva on 18 May 11
     
    wow it's frigthening! it's the dream of every anarchist, every drug, arm, human dealer! the world made as a global fiscal paradise... the idea is clever however it will not replace real money because 1 - no one will build a fortune on bitcoin if a technological breakthrough can ruin them 2 - government never allowed parallel money to flourish on their territory, so it will be almost impossible to change bitcoin against euros or dollars
  • Nicholas Lan on 18 May 11
     
    interesting stuff anyone read cryptonomicon by neal stephenson? similar theme.
  • Luís F. Simões on 18 May 11
     
    :) yes. One of the comments on reddit was precisely drawing the parallels with Neal Stephenson's Snowcrash / Diamond Age / Cryptonomicon. Interesting stuff indeed. It has a lot of potential for misuse, but also opens up new possibilities. We've discussed recently how emerging technologies will drive social change. Whether it's the likes of NSA / CIA who will benefit the most from the Twitters, Facebooks and so on, by gaining greater power for control, or whether individuals are being empowered to at least an identical degree. We saw last year VISA / PayPal censoring WikiLeaks... Well, here's a way for any individual to support such an organization, in a fully anonymous and uncontrollable way...
  • tvinko on 18 May 11
     
    One of my colleagues has made a nice, short write-up about BitCoin: http://www.pds.ewi.tudelft.nl/~victor/bitcoin.html
  • LeopoldS on 18 May 11
     
    very nice analysis indeed - thanks Tamas for sharing it!
  • pacome delva on 20 May 11
     
    mmm I'm not an expert but it seemed to me that, even if these criticisms are true, there is one fundamental difference between the money you exchange on internet via your bank, and bitcoins. The first one is virtual money and the second one aims at being real, physical, money, even if digital, in the same way as banknotes, coins, or gold.
  • nikolas smyrlakis on 20 May 11
     
    An algorithm wanna-be central bank issuing untraceable tax free money between internet users? not more likely than the end of the world supposed to take place tomorrow, in my opinion. Algorithms don't usually assault women though !:P
  • LeopoldS on 21 May 11
     
    well, most money is anyway just virtual and only based on expectations and trust ... (see e.g. http://en.wikipedia.org/wiki/Money_supply) and thus if people trust that this "money" has some value in the sense that they can get something of value to them in exchange, then not much more is needed it seems to me ...
  • pacome delva on 23 May 11
     
    @Leopold: ok let's use the rigth words then. Bitcoin aim at being a currency ("physical objects generally accepted as a medium of exchange" from wikipedia), different than the "demand deposit". In the article proposed by Tamas he compares what cannot be compared (currencies, demand deposits and their mean of exchange). The interesting question is wether one can create a digital currency which is too difficult to counterfeit. As far as I know, there is no existing digital currency except this bitcoins (and maybe the currencies from games as second life and others, but which are of limited use in real world).
  • nikolas smyrlakis on 23 May 11
     
    well of course money is trust, and even more loans and credit and even more stock and bond markets. It all represents trust and expectations. However since the first banks 500 years ago and the first loans etc. etc., and as well the fact that bonds and currencies bring down whole countries (Greece lately), and are mainly controlled by large financial centres and (central) banks, banks have always been on the winning side no matter what and that isn't going to change easily. So if you are talking about these new currencies it would be a new era, not just a new currency. So should Greece convert its debt to bitcoins ;P ?
  • pacome delva on 23 May 11
     
    well, from 1936 to 1993 the central bank of france was owned by the state and was supposed to serve the general interest...
LeopoldS

BBC News - Speed-of-light experiments give baffling result at Cern - 5 views

www.bbc.co.uk/...science-environment-15017484

PHY physics Einstein

shared by LeopoldS on 22 Sep 11 - No Cached
  • LeopoldS on 22 Sep 11
     
    Sante, Luzi have a look at this???!!!
  • ...3 more comments...
  • Luís F. Simões on 23 Sep 11
     
    and here's the xkcd on it: http://xkcd.com/955/
  • Luzi Bergamin on 23 Sep 11
     
    And here's the arXiv paper http://arxiv.org/abs/1109.4897 Serious? Difficult to say. I'm theorist and can't really rate their measurement techniques. Certainly be cautious, mostly such things disappear faster than they appeared.
  • LeopoldS on 23 Sep 11
     
    it took them 3 years to "appear"!
  • Luzi Bergamin on 23 Sep 11
     
    Leo, you mean that they measured 3 years? That's not a point to criticize: since the only interaction of neutrinos with matter is the Weak Interaction (which is indeed very, very weak), it is extremely hard to get a reasonable statistic. By the same reason, it's essentially impossible to shield the experiment from the background. And this background (solar neutrinos, cosmic radiation neutrinos) is huge.
  • pacome delva on 28 Sep 11
     
    for sure a result to be taken seriously. It makes a buzz in my lab... but always be cautious with this kind of declaration, that hugely violates all physics we know and even most of the reasonable alternative theories... Remember the Pionneer anomaly for which it took almost ten years to set up that finally its a thermal effect.
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