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Luís F. Simões

Timelapse video of asteroid discoveries in our solar system from 1980-2010 (watch in 10... - 5 views

www.youtube.com/watch

asteroid detection solar system WISE

shared by Luís F. Simões on 13 Sep 10 - No Cached
Joris _ liked it
  • Ma Ru on 14 Sep 10
     
    Nice... Now I have a lame question: after you have discovered ~500k asteroids, all moving (I assume more or less) chaotically in that asteroid belt, how do you tell one from another?
  • ...1 more comment...
  • Joris _ on 14 Sep 10
     
    hmm, not very chaotic indeed - laws of Kepler plus some perturbations.
  • Ma Ru on 15 Sep 10
     
    That's what I thought but when presented as a green "goo" in the video, it appears rather unordered... so I guess this is just an impression evoked by a not-to-scale presentation?
  • Francesco Biscani on 19 Sep 10
     
    It depends... orbits can be chaotic if the orbital period is in a resonance with Jupiter, although such orbits are not stable. Such configurations tend to get disrupted pretty quickly (in cosmic terms :P) http://en.wikipedia.org/wiki/Kirkwood_gap
pacome delva

Information converted to energy - physicsworld.com - 4 views

physicsworld.com/...44385

phy information maxwell_demon

shared by pacome delva on 22 Nov 10 - No Cached
  • By tracking the particle's motion using a video camera and then using image-analysis software to identify when the particle had rotated against the field, the researchers were able to raise the metaphorical barrier behind it by inverting the field's phase. In this way they could gradually raise the potential of the particle even though they had not imparted any energy to it directly.
  • "Nobody thinks of using bits to boil water," he says, "but that would in principle be possible at nanometre scales." And he speculates that molecular processes occurring in nature might already be converting information to energy in some way. "The message is that processes taking place on the nanoscale are completely different from those we are familiar with, and that information is part of that picture."
  • pacome delva on 22 Nov 10
     
    crazy, the Maxwell's demon at work !
  • Nicholas Lan on 23 Nov 10
     
    crazy indeed
pacome delva

Cutting Soot Counteracts Warming in California - 1 views

news.sciencemag.org/...-soot-counteracts-warming.html

phy climate_change soot

shared by pacome delva on 15 Dec 10 - No Cached
  • models suggest that cut may also have cut into the warming of the state's climate in an unexpectedly big way, preventing temperatures from climbing even higher.
  • "This indeed has major implications for mitigating climate change on a global scale," says Ramanathan. "We have the chance to see a quick global response."
Francesco Biscani

The End Of Gravity As a Fundamental Force - 6 views

science.slashdot.org/...Gravity-As-a-Fundamental-Force

phy

shared by Francesco Biscani on 11 Jan 10 - Cached
LeopoldS liked it
  • Francesco Biscani on 11 Jan 10
     
    "At a symposium at the Dutch Spinoza-instituut on 8 December, 2009, string theorist Erik Verlinde introduced a theory that derives Newton's classical mechanics. In his theory, gravity exists because of a difference in concentration of information in the empty space between two masses and its surroundings. He does not consider gravity as fundamental, but as an emergent phenomenon that arises from a deeper microscropic reality. A relativistic extension of his argument leads directly to Einstein's equations."
  • ...8 more comments...
  • Dario Izzo on 12 Jan 10
     
    Diffcult for me to fully understand / believe in the holographic principle at macroscopical scales ... potentially it looks though as a revolutionary idea.....
  • pacome delva on 13 Jan 10
     
    never heard about it... seems interesting. At first sight it seems that it is based on fundamental principle that could lead to a new phenomenology, so that could be tested. Perhaps Luzi knows more about this ? Did we ever work on this concept ?
  • Luzi Bergamin on 13 Jan 10
     
    The paper is quite long and I don't have the time right now to read it in detail. Just a few comments: * We (ACT) definitely never did anything in this direction? But: is there a new phenomenology? I'm not sure, if the aim is just to get Einstein's theory as emergent theory, then GR should not change (or only change in extreme conditions.) * Emergent gravity is not new, also Erik admits that. The claim to have found a solution appears quite frequently, but most proposals actually are not emergent at all. At least, I have the impression that Erik is aware of the relevant steps to be performed. * It's very difficult to judge from a short glance at the paper, up to which point the claims are serious and where it just starts to be advertisments. Section 6 is pretty much a collection of self-praise. * Most importantly: I don't understand how exactly space and time should be emergent. I think it's not new to observe that space is related to special canonical variables in thermodynamics. If anybody can see anything "emergent" in the first paragraphs of section 3, then please explain me. For me, this is not emergent space, but space introduced with a "sledge hammer." Time anyway seems to be a precondition, else there is nothing like energy and nothing like dynamics. * Finally, holography appears to be a precondition, to my knowledge no proof exists that normal (non-supersymmetric, non-stringy, non-whatever) GR has a holographic dual.
  • Luzi Bergamin on 13 Jan 10
     
    Update: meanwhile I understood roughly what this should be about. It's well known that BH physics follow the laws of theormodynamics, suggesting the existence of underlying microstates. But if this is true, shouldn't the gravitational force then be emergent from these microstates in the same way as any theromdynamical effect is emergent from the behavior of its constituents (e.g. a gas)? If this can be prooven, then indeed gravity is emergent. Problem: one has to proof that *any* configuration in GR may be interpreted as thermodynamical, not just BHs. That's probably where holography comes into the play. To me this smells pretty much like N=4 SYM vs. QCD. The former is not QCD, but can be solved, so all stringy people study just that one and claim to learn something about QCD. Here, we look at holographic models, GR is not holographic, but who cares... Engineering problems...
  • LeopoldS on 13 Jan 10
     
    is there any experimental or observational evidence that points to this "solution"?
  • Luzi Bergamin on 13 Jan 10
     
    Are you joking??? :D
  • pacome delva on 14 Jan 10
     
    I was a bit fast to say it could be tested... apparently we don't even know a theory that is holographic, perhaps a string theory (see http://arxiv.org/abs/hep-th/9409089v2). So very far from any test...
  • LeopoldS on 14 Jan 10
     
    Luzi, I miss you!!!
  • Luzi Bergamin on 14 Jan 10
     
    Leo, do you mean you liked my comment on your question more than Pacome's? Well, the ACT has to evolve and fledge, so no bullshitting anymore, but serious and calculating answers... :-) Sorry Pacome, nothing against you!! I just LOVE this Diigo because it gives me the opportunity for a happy revival of my ACT mood.
  • pacome delva on 14 Jan 10
     
    haha, today would have been great to show your mood... we had a talk on the connection between mind and matter !!
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
Joris _

Panel Picks 3 Finalists for ESAs Cosmic Vision M class Missions | SpaceNews.com - 3 views

spacenews.com/...ic-vision-mclass-missions.html

MAD Class_M Science Marco Polo

shared by Joris _ on 20 Jan 10 - Cached
pacome delva liked it
  • “superb from a science standpoint,” but beyond Europe’s current budget
  • There was some questioning of the cost estimate for Euclid, but at some point you have to decide: Either you don’t believe the estimates that [ESA science program managers] produced, or you assume their estimates are credible. Euclid was the one mission where costs were debated, but the consensus was to use the cost estimates presented to us.
  • pacome delva on 20 Jan 10
     
    finally cross-scale is not selected, it was the only cosmic vision mission with multi-satellites formation flying, since the concept for Xeus has changed. There is still Swarm but it's not really formation flying... So ESA is missing something here...
Joris _

SPACE.com -- Venus Probe's Problems May Cause Japan to Scale Back - 0 views

www.space.com/...suki-japan-rethink-101217.html

space MAD

shared by Joris _ on 20 Dec 10 - No Cached
  • We have to be more conservative to plan our next planetary mission, so it will never fail in any aspect."
  • the probe's initial failure will have a big impact on how JAXA plans future planetary missions
  • hew to more conservative ideas in the near future
  • Joris _ on 20 Dec 10
     
    what a shame! ambition and innovation have not been fairly rewarded ...
  • ...1 more comment...
  • Ma Ru on 20 Dec 10
     
    Did you try to run your algorithm on their problem as Dario suggested? I'm very curious!
  • Joris _ on 20 Dec 10
     
    I didn't have time yet. But formulating the failure with a MTBF or a FIT, you can easily imagine a more robust solution. Instead of one single burn, you would make several smaller burns - It will take more time and require more fuel though. Another "robust" approach is to consider weak stability boundary capture. Again it takes time, but chances of failure are lessen.
  • LeopoldS on 21 Dec 10
     
    would be a pity indeed!
Francesco Biscani

Robot Armada Might Scale New Worlds - 1 views

www.sciencedaily.com/...091027195507.htm

ai

shared by Francesco Biscani on 28 Oct 09 - Cached
  • We are departing from traditional approaches of a single robotic spacecraft with no redundancy that is Earth-commanded to one that allows for having multiple, expendable low-cost robots that can command themselves or other robots at various locations at the same time.
pacome delva

Physics - Nanospheres on a silver plate - 0 views

physics.aps.org/64

phy nan nanoparticle

shared by pacome delva on 05 Aug 09 - Cached
  • As a result of its high symmetry and conjugated bond structure, the electronic properties of C60 are very unusual, and there is a massive research effort toward integrating it into molecular scale electronic devices [4].
  • In this context, it is important to understand how the molecule forms bonds with a metal substrate, such as silver, which is commonly used as an electrode material.
  • The general trend in all of these cases shows that even molecules with relatively weak individual (atom-to-atom) surface bonds can induce substantial substrate reconstructions in order to create favorable adsorption sites [8]. Such “nanopatterning” of substrates is essential to the stability of ordered structures of these molecules and can critically influence their electronic structure, which is an important aspect in the design of molecular electronic devices.
Joris _

Ion trap quantum computing - 0 views

www.physorg.com/news161348276.html

shared by Joris _ on 14 May 09 - Cached
  • One of the most important considerations in quantum computing is the fact that quantum computing scales polynomially, rather than exponentially, as classical computing does
  • his process would allow us to take problems of great complexity and still solve them on a humanly possible timescale. This could provide the key to modeling complex systems - especially perhaps in biology - that we can’t solve now. This would be a tremendous advantage over classical computing.
  • Joris _ on 14 May 09
     
    a follow-up question: Can quantum computer be efficient for global optimisation ?
ESA ACT

Dynamics of phononic dissipation at the atomic scale: Dependence on internal degrees of... - 0 views

scitation.aip.org/...GetabsServlet

nan

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    Dynamics of dissipation local vibrations to the surrounding substrate is a key issue in friction between sliding surfaces as well as in boundary lubrication.
ESA ACT

Micronanostructures of the scales on a mosquito's legs and their role in weight support - 0 views

scitation.aip.org/...GetabsServlet

BIO Microtechnology technology Robotics

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    We show here that the mosquito cannot only give rise to a higher water-supporting force than the water strider if the ratio of the water-supporting force to the body weight of the insect itself is compared, but also can safely take off or land on the wate
ESA ACT

Novel Photoanode Structure Templated from Butterfly Wing Scales - 0 views

pubs.acs.org/...cm702458p

Bio paper optics energy

shared by ESA ACT on 24 Apr 09 - No Cached
  • ESA ACT on 24 Apr 09
     
    Full pdf
ESA ACT

Large-scale pattern growth of graphene films for stretchable transparent electrodes : A... - 0 views

www.nature.com/...nature07719.html

electricity NAN nanotechnology polymerElectronics ENG NRG Chemistry

shared by ESA ACT on 24 Apr 09 - Cached
  • ESA ACT on 24 Apr 09
     
    wow ... look at this!
nikolas smyrlakis

BBC NEWS | Asia-Pacific | Scientists bring snow to Beijing - 2 views

news.bbc.co.uk/...8337337.stm

china asia Weather Modification Office climate change

shared by nikolas smyrlakis on 02 Nov 09 - Cached
  • nikolas smyrlakis on 02 Nov 09
     
    Did you know about this Weather Modification Office? Promising or dodgy?
  • Friederike Sontag on 03 Nov 09
     
    Yes. In China it happens apparently quite often that weather is regionally modified, e.g. in order to have good weather conditions during certain events (like olympics in Beijing). But also in other countries weather modification is applied, for reasons of agriculture, pollution, skiing, etc. Obviously, one wonders on the environmental impact of such an artificial cloud feeding process with silver iodide. I just googled, stumbling upon this report http://www.weathermodification.org/AGI_toxicity.pdf which published the result: no environmentally harmful effects...
  • Friederike Sontag on 03 Nov 09
     
    and w.r.t. ur question: I mean different weather conditions which we experience locally (like droughts or other extreme weather events) are (often) due to large-scale/global climatic changes. Hence, cloud seeding just describes a local, short-term mitigation of these events. However, there is a geoengineering proposal (so climate modification) which also suggests to seed clouds above the sea (i.e. increase cloud coverage, e.g. by using seaspray as cloud condesation nuclei), thereby increasing the planetary albedo (Earth reflectance) and reducing the energy reaching the Earth surface. If this idea is promising or not, I couldn't judge upon, but for sure it is worthwhile to take a closer look at.
LeopoldS

SpaceX Targets 2013 for Launch of Falcon Heavy | SpaceNews.com - 1 views

spacenews.com/...pacex-launch-falcon-heavy.html

spacex launcher

shared by LeopoldS on 05 Apr 11 - No Cached
  • LeopoldS on 05 Apr 11
     
    big big booster coming ... !
  • ...1 more comment...
  • Joris _ on 06 Apr 11
     
    In similar story (http://www.orlandosentinel.com/news/os-spacex-rocket-elon-musk-20110405,0,3234336.story) the quote: " "This is a rocket of truly huge scale," said Musk, adding it would have the capability to one day enable moon or Mars missions." tells a lot about the ambition of it...
  • Luís F. Simões on 17 Apr 11
     
    even bigger booster also coming: China Aims To Build World's Largest Rocket "Back in March, China revealed it is studying the feasibility of designing the most powerful carrier rocket in history for making a manned moon landing and exploring deep space, according to Liang Xiaohong, vice head of the China Academy of Launch Vehicle Technology. The rocket is envisaged to have a payload of 130 tonnes, five times larger than that of China's current largest rocket. This rocket, if built, will eclipse the 53 tonne capacity of the planned Falcon 9 Heavy from SpaceX. It will even surpass the largest rocket ever built, the 119-tonne Saturn V."
  • LeopoldS on 18 Apr 11
     
    still only "is studying the feasibility of designing a powerful carrier rocket" - we could easily do the same at no cost almost ... but still ... they might be serious ...
santecarloni

[1107.0392] Emergence of good conduct, scaling and Zipf laws in human behavioral sequen... - 3 views

arxiv.org/1107.0392

emergence human behavior science

shared by santecarloni on 07 Jul 11 - No Cached
LeopoldS liked it
  • santecarloni on 07 Jul 11
     
    ... proof that humanity is good?
  • LeopoldS on 16 Jul 11
     
    "The dataset contains practically all actions of all players of the MMOG Pardus since the game went online in 2004 [18]. Pardus is an open-ended online game with a world- wide player base of currently more than 370,000 people. Play- ers live in a virtual, futuristic universe in which they interact with others in a multitude of ways to achieve their self-posed goals [22]. Most players engage in various economic activities typically with the (self-posed) goal to accumulate wealth and status. Social and economical decisions of players are often strongly influenced and driven by social factors such as friend- ship, cooperation, and conflict." quite impressive ...
Thijs Versloot

Properties of galaxies reproduced by hydrodynamic simulation (VIDEO) - 3 views

www.nature.com/...index.html

simulation universe

shared by Thijs Versloot on 18 Aug 14 - No Cached
  • Thijs Versloot on 18 Aug 14
     
    Scientists at MIT have traced 13 billion years of galaxy evolution, from shortly after the Big Bang to the present day. Their simulation, named Illustris, captures both the massive scale of the Universe and the intriguing variety of galaxies - something previous modelers have struggled to do. It produces a Universe that looks remarkably similar to what we see through our telescopes, giving us greater confidence in our understanding of the Universe, from the laws of physics to our theories about galaxy formation. "Simulation is the future of innovation"
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