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pandomilla

Not a scratch - 7 views

shared by pandomilla on 12 Apr 12 - No Cached
LeopoldS liked it
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    I hate scorpions, but this could be a nice subject for a future Ariadna study! This north African desert scorpion, doesn't dig burrows to protect itself from the sand-laden wind (as the other scorpions do). When the sand whips by at speeds that would strip paint away from steel, the scorpion is able to scurry off without apparent damage.
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    Nice research, though they have done almost all the work that we could do in an Ariadna, didnt they? "To check, they took further photographs. In particular, they used a laser scanning system to make a three-dimensional map of the armour and then plugged the result into a computer program that blasted the virtual armour with virtual sand grains at various angles of attack. This process revealed that the granules were disturbing the air flow near the skeleton's surface in ways that appeared to be reducing the erosion rate. Their model suggested that if scorpion exoskeletons were smooth, they would experience almost twice the erosion rate that they actually do. Having tried things out in a computer, the team then tried them for real. They placed samples of steel in a wind tunnel and fired grains of sand at them using compressed air. One piece of steel was smooth, but the others had grooves of different heights, widths and separations, inspired by scorpion exoskeleton, etched onto their surfaces. Each sample was exposed to the lab-generated sandstorm for five minutes and then weighed to find out how badly it had been eroded. The upshot was that the pattern most resembling scorpion armour-with grooves that were 2mm apart, 5mm wide and 4mm high-proved best able to withstand the assault. Though not as good as the computer model suggested real scorpion geometry is, such grooving nevertheless cut erosion by a fifth, compared with a smooth steel surface. The lesson for aircraft makers, Dr Han suggests, is that a little surface irregularity might help to prolong the active lives of planes and helicopters, as well as those of scorpions."
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    What bugs me (pardon the pun) is that the dimensions of the pattern they used were scaled up by many orders of magnitude, while "grains of sand" with which the surface was bombarded apparently were not... Not being a specialist in the field, I would nevertheless expect that the size of the surface pattern *in relation to* to size of particles used for bombarding would be crucial.
LeopoldS

GTOC problem announced! - 0 views

"This year's problem is the global mapping of Jupiter's Galilean satellites, Io, Europa, Ganymede, and Callisto, by means of close flybys. A trajectory must be designed for a low-thrust spacecraft ...

Mas ai

started by LeopoldS on 10 Sep 12 no follow-up yet
LeopoldS

CMS search for the Standard Model Higgs Boson in LHC data from 2010 and 2011 | CMS Expe... - 0 views

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    news from the search for higgs ...
santecarloni

Has 'new physics' been found at CERN? - physicsworld.com - 1 views

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    Physicists working on the LHCb experiment at the CERN particle-physics lab have released the best evidence yet for direct charge-parity (CP) violation in charm mesons....While more data must be analysed to confirm the result, the work could point to new physics beyond the Standard Model and help physicists understand why there is more matter than antimatter in the universe.
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    lot of new physics this year ...
johannessimon81

Cosmological model without accelerated expansion proposed - 1 views

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    Redshift in this model is partially produced by a change in the masses of elementary particles (and atoms)
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    It seems to solve the problem of infinite energy density at the singularity in any case. I would love to see a way of experimentally verifying this, although most people seem to believe it is wrong. I read the following quote though by Dirac to Pauli "we all agree your idea is crazy, but the real question is it crazy enough to be correct?"
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    As far as I can see, this is not untestable per se, rather an explanation to the redshift that is equivalent to accelerating expansion. It is not that the theory is untestable, rather just another way of looking at it. Kind of like that its sometimes convenient to consider light a particle, sometimes a wave. In the same way it could sometime convenient to view the universe as static with increasing mass instead.
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    Well the premiss "matter getting heavier" may be up to falsification in some way or another. Currently, there is no absolute method to determine mass so it might even be plausible that this is actually the case. I don't think it is related but there is a problem with the 1kg-standards (1 official and 6 copies) where the masses seem to deviate.
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    It should not be impossible to verify a change in mass(es) over time. For example the electron cyclotron frequency scales ~e/m while the Hydrogen emission frequencies scale with ~m*e^4. Using multiple relationships like that which can be easily and accurately measured an increase in the mass of fundamental particles should - in principle - be detectable (even if the mass of the earth increases at the same time changing the relativistic reference frame).
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    The Watt balance and a definition using the Planck's constant seems to do the trick and is currently being discussed. Would the electron charge not be problematic as it is related to Coulombs which depends on Amperes which is defined by Newtons which hence depends back on the mass again?
johannessimon81

Software Makes 3-D Models From Any Photo - 3 views

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    Video shows how easy the process is and how cool the results look. Does anybody know a potential scientific application for such image processing?
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    this is very impressive indeed ... looks like the manual steps they are doing could be automatised, can't they?
LeopoldS

Sex differences in the structural connectome of the human brain - 0 views

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    it seems that there are indications that we are differently wired .... Sex differences in human behavior show adaptive complementarity: Males have better motor and spatial abilities, whereas females have superior memory and social cognition skills. Studies also show sex differences in human brains but do not explain this complementarity. In this work, we modeled the structural connectome using diffusion tensor imaging in a sample of 949 youths (aged 8-22 y, 428 males and 521 females) and discovered unique sex differences in brain connectivity during the course of development. Connection-wise statistical analysis, as well as analysis of regional and global network measures, presented a comprehensive description of network characteristics. In all supratentorial regions, males had greater within-hemispheric connectivity, as well as enhanced modularity and transitivity, whereas between-hemispheric connectivity and cross-module participation predominated in females. However, this effect was reversed in the cerebellar connections. Analysis of these changes developmentally demonstrated differences in trajectory between males and females mainly in adolescence and in adulthood. Overall, the results suggest that male brains are structured to facilitate connectivity between perception and coordinated action, whereas female brains are designed to facilitate communication between analytical and intuitive processing modes.
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    I like this abstract: sex, sex, sex, sex, SEX, SEX, SEX, SEX...!!! I wonder if the "sex differences" are related to gender-specific differences...
tvinko

Massively collaborative mathematics : Article : Nature - 28 views

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    peer-to-peer theorem-proving
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    Or: mathematicians catch up with open-source software developers :)
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    "Similar open-source techniques could be applied in fields such as [...] computer science, where the raw materials are informational and can be freely shared online." ... or we could reach the point, unthinkable only few years ago, of being able to exchange text messages in almost real time! OMG, think of the possibilities! Seriously, does the author even browse the internet?
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    I do not agree with you F., you are citing out of context! Sharing messages does not make a collaboration, nor does a forum, .... You need a set of rules and a common objective. This is clearly observable in "some team", where these rules are lacking, making team work inexistent. The additional difficulties here are that it involves people that are almost strangers to each other, and the immateriality of the project. The support they are using (web, wiki) is only secondary. What they achieved is remarkable, disregarding the subject!
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    I think we will just have to agree to disagree then :) Open source developers have been organizing themselves with emails since the early '90s, and most projects (e.g., the Linux kernel) still do not use anything else today. The Linux kernel mailing list gets around 400 messages per day, and they are managing just fine to scale as the number of contributors increases. I agree that what they achieved is remarkable, but it is more for "what" they achieved than "how". What they did does not remotely qualify as "massively" collaborative: again, many open source projects are managed collaboratively by thousands of people, and many of them are in the multi-million lines of code range. My personal opinion of why in the scientific world these open models are having so many difficulties is that the scientific community today is (globally, of course there are many exceptions) a closed, mostly conservative circle of people who are scared of changes. There is also the fact that the barrier of entry in a scientific community is very high, but I think that this should merely scale down the number of people involved and not change the community "qualitatively". I do not think that many research activities are so much more difficult than, e.g., writing an O(1) scheduler for an Operating System or writing a new balancing tree algorithm for efficiently storing files on a filesystem. Then there is the whole issue of scientific publishing, which, in its current form, is nothing more than a racket. No wonder traditional journals are scared to death by these open-science movements.
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    here we go ... nice controversy! but maybe too many things mixed up together - open science journals vs traditional journals, conservatism of science community wrt programmers (to me one of the reasons for this might be the average age of both groups, which is probably more than 10 years apart ...) and then using emailing wrt other collaboration tools .... .... will have to look at the paper now more carefully ... (I am surprised to see no comment from José or Marek here :-)
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    My point about your initial comment is that it is simplistic to infer that emails imply collaborative work. You actually use the word "organize", what does it mean indeed. In the case of Linux, what makes the project work is the rules they set and the management style (hierachy, meritocracy, review). Mailing is just a coordination mean. In collaborations and team work, it is about rules, not only about the technology you use to potentially collaborate. Otherwise, all projects would be successful, and we would noy learn management at school! They did not write they managed the colloboration exclusively because of wikipedia and emails (or other 2.0 technology)! You are missing the part that makes it successful and remarkable as a project. On his blog the guy put a list of 12 rules for this project. None are related to emails, wikipedia, forums ... because that would be lame and your comment would make sense. Following your argumentation, the tools would be sufficient for collaboration. In the ACT, we have plenty of tools, but no team work. QED
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    the question on the ACT team work is one that is coming back continuously and it always so far has boiled down to the question of how much there need and should be a team project to which everybody inthe team contributes in his / her way or how much we should leave smaller, flexible teams within the team form and progress, more following a bottom-up initiative than imposing one from top-down. At this very moment, there are at least 4 to 5 teams with their own tools and mechanisms which are active and operating within the team. - but hey, if there is a real will for one larger project of the team to which all or most members want to contribute, lets go for it .... but in my view, it should be on a convince rather than oblige basis ...
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    It is, though, indicative that some of the team member do not see all the collaboration and team work happening around them. We always leave the small and agile sub-teams to form and organize themselves spontaneously, but clearly this method leaves out some people (be it for their own personal attitude or be it for pure chance) For those cases which we could think to provide the possibility to participate in an alternative, more structured, team work where we actually manage the hierachy, meritocracy and perform the project review (to use Joris words).
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    I am, and was, involved in "collaboration" but I can say from experience that we are mostly a sum of individuals. In the end, it is always one or two individuals doing the job, and other waiting. Sometimes even, some people don't do what they are supposed to do, so nothing happens ... this could not be defined as team work. Don't get me wrong, this is the dynamic of the team and I am OK with it ... in the end it is less work for me :) team = 3 members or more. I am personally not looking for a 15 member team work, and it is not what I meant. Anyway, this is not exactly the subject of the paper.
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    My opinion about this is that a research team, like the ACT, is a group of _people_ and not only brains. What I mean is that people have feelings, hate, anger, envy, sympathy, love, etc about the others. Unfortunately(?), this could lead to situations, where, in theory, a group of brains could work together, but not the same group of people. As far as I am concerned, this happened many times during my ACT period. And this is happening now with me in Delft, where I have the chance to be in an even more international group than the ACT. I do efficient collaborations with those people who are "close" to me not only in scientific interest, but also in some private sense. And I have people around me who have interesting topics and they might need my help and knowledge, but somehow, it just does not work. Simply lack of sympathy. You know what I mean, don't you? About the article: there is nothing new, indeed. However, why it worked: only brains and not the people worked together on a very specific problem. Plus maybe they were motivated by the idea of e-collaboration. No revolution.
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    Joris, maybe I made myself not clear enough, but my point was only tangentially related to the tools. Indeed, it is the original article mention of "development of new online tools" which prompted my reply about emails. Let me try to say it more clearly: my point is that what they accomplished is nothing new methodologically (i.e., online collaboration of a loosely knit group of people), it is something that has been done countless times before. Do you think that now that it is mathematicians who are doing it makes it somehow special or different? Personally, I don't. You should come over to some mailing lists of mathematical open-source software (e.g., SAGE, Pari, ...), there's plenty of online collaborative research going on there :) I also disagree that, as you say, "in the case of Linux, what makes the project work is the rules they set and the management style (hierachy, meritocracy, review)". First of all I think the main engine of any collaboration like this is the objective, i.e., wanting to get something done. Rules emerge from self-organization later on, and they may be completely different from project to project, ranging from almost anarchy to BDFL (benevolent dictator for life) style. Given this kind of variety that can be observed in open-source projects today, I am very skeptical that any kind of management rule can be said to be universal (and I am pretty sure that the overwhelming majority of project organizers never went to any "management school"). Then there is the social aspect that Tamas mentions above. From my personal experience, communities that put technical merit above everything else tend to remain very small and generally become irrelevant. The ability to work and collaborate with others is the main asset the a participant of a community can bring. I've seen many times on the Linux kernel mailing list contributions deemed "technically superior" being disregarded and not considered for inclusion in the kernel because it was clear that
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    hey, just catched up the discussion. For me what is very new is mainly the framework where this collaborative (open) work is applied. I haven't seen this kind of working openly in any other field of academic research (except for the Boinc type project which are very different, because relying on non specialists for the work to be done). This raise several problems, and mainly the one of the credit, which has not really been solved as I read in the wiki (is an article is written, who writes it, what are the names on the paper). They chose to refer to the project, and not to the individual researchers, as a temporary solution... It is not so surprising for me that this type of work has been first done in the domain of mathematics. Perhaps I have an ideal view of this community but it seems that the result obtained is more important than who obtained it... In many areas of research this is not the case, and one reason is how the research is financed. To obtain money you need to have (scientific) credit, and to have credit you need to have papers with your name on it... so this model of research does not fit in my opinion with the way research is governed. Anyway we had a discussion on the Ariadnet on how to use it, and one idea was to do this kind of collaborative research; idea that was quickly abandoned...
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    I don't really see much the problem with giving credit. It is not the first time a group of researchers collectively take credit for a result under a group umbrella, e.g., see Nicolas Bourbaki: http://en.wikipedia.org/wiki/Bourbaki Again, if the research process is completely transparent and publicly accessible there's no way to fake contributions or to give undue credit, and one could cite without problems a group paper in his/her CV, research grant application, etc.
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    Well my point was more that it could be a problem with how the actual system works. Let say you want a grant or a position, then the jury will count the number of papers with you as a first author, and the other papers (at least in France)... and look at the impact factor of these journals. Then you would have to set up a rule for classifying the authors (endless and pointless discussions), and give an impact factor to the group...?
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    it seems that i should visit you guys at estec... :-)
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    urgently!! btw: we will have the ACT christmas dinner on the 9th in the evening ... are you coming?
Thijs Versloot

Regrowing limbs of mice #CELL - 0 views

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    By reactivating a dormant gene called Lin28a, which is active in embryonic stem cells, researchers were able to regrow hair and repair cartilage, bone, skin and other soft tissues in a mouse model.
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    regrow hair???!!!??? :-)
Francesco Biscani

Saturn's rings gave birth to mini-moons - 0 views

  • Low density, recent surfaces, and somewhat oblong shapes all hint that some of these moons are likely to be less than 100 million years old.
  • Researchers suspected that the moons might have originated through some sort of interactions within the A Ring, but the number of bodies involved made modeling the system too computationally challenging. Fortunately, Moore's Law caught up with Cassini, and today's issue of Nature contains a paper that describes a model that successfully reproduces the pattern of moons we now observe.
Loretta Latronico Poulain

Agent-based computer models could anticipate future economic crisis - 1 views

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    "The Illinois Commerce Commission wanted to make sure that if they deregulated the power market, individual producers of electricity would not be able to manipulate the market during times of high demand by withholding capacity or charging excessive rates. The Argonne model found that during certain times of heavy load such a situation could emerge, which led to the recommendation that independent monitors maintain some oversight of the power market." Interesting this study on power grids !
pacome delva

Direction Changes of Insect Swarms - 2 views

shared by pacome delva on 28 Jul 10 - Cached
  • Swarms of insects or schools of fish can suddenly switch direction, seemingly at random. A research team now believes they understand why. In the August Physical Review E they describe experiments with locusts and their mathematical model of the swarm. The model suggests that tiny alignment errors between neighboring individual locusts within the swarm, which normally cancel each other, can accumulate over long times and eventually cause the entire swarm to suddenly move in a new direction.
Luís F. Simões

Inferring individual rules from collective behavior - 2 views

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    "We fit data to zonal interaction models and characterize which individual interaction forces suffice to explain observed spatial patterns." You can get the paper from the first author's website: http://people.stfx.ca/rlukeman/research.htm
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    PNAS? Didnt strike me as sth very new though... We should refer to it in the roots study though: "Social organisms form striking aggregation patterns, displaying cohesion, polarization, and collective intelligence. Determining how they do so in nature is challenging; a plethora of simulation studies displaying life-like swarm behavior lack rigorous comparison with actual data because collecting field data of sufficient quality has been a bottleneck." For roots it is NO bottleneck :) Tobias was right :)
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    Here they assume all relevant variables influencing behaviour are being observed. Namely, the relative positions and orientations of all ducks in the swarm. So, they make movies of the swarm's movements, process them, and them fit the models to that data. In the roots, though we can observe the complete final structure, or even obtain time-lapse movies showing how that structure came out to be, getting the measurements of all relevant soil variables (nitrogen, phosphorus, ...) throughout the soil, and over time, would be extremely difficult. So I guess a replication of the kind of work they did, but for the roots, would be hard. Nice reference though.
pacome delva

Neutron Star Formation Could Awaken the Vacuum | Physical Review Focus - 0 views

  • Lima and Vanzella joined with George Matsas of São Paulo State University in their latest work to examine a model of the highly-curved spacetime that appears during formation of an ultradense neutron star. For some reasonable values of the mass and size of the star, they predict that the vacuum energy will grow within milliseconds for some values of the coupling parameter. At this point the vacuum energy would begin to induce additional gravitational effects, which they haven't yet calculated, so they don't know how the star would be affected. If further research shows such a neutron star to be unstable, the existence of stable neutron stars of particular sizes could rule out the existence fields of the type they modeled.
Luís F. Simões

The 70 Online Databases that Define Our Planet - 0 views

  • an ambitious European plan to simulate the entire planet. The idea is to exploit the huge amounts of data generated by financial markets, health records, social media and climate monitoring to model the planet's climate, societies and economy. The vision is that a system like this can help to understand and predict crises before they occur so that governments can take appropriate measures in advance.
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    website of the project working on the 'Living Earth Simulator': http://www.futurict.ethz.ch/FuturICT five page summary of the FuturICT Proposal: http://www.futurict.ethz.ch/data/FuturICT-FivePageSummary.pdf
Nina Nadine Ridder

Stratospheric Water Vapor is a Global Warming Wild Card - 1 views

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    Climate models are not able to reproduce the observed decrease in stratospheric water vapor which shows that the global water cycle is still not known well enough and further research is desperately needed. 
Nina Nadine Ridder

NASA Sets Coverage for GOES-P Weather Satellite Launch on March 2 | SpaceRef - Your Spa... - 0 views

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    launch of satellite to collect data for improvement of ocean models, weather predictions and hurricane forecasts
pacome delva

Power Law Explains Insurgent Violence - 1 views

  • To try to explain the mechanism behind these patterns, the team borrowed a simple computer model from economics. The model treated all insurgencies like a marketplace--groups of people constantly deciding whether to act. Rather than coordinating, the groups simply watch the news. The size of the carnage reported at any given time determines the probability that a group of a given size will strike next. Like clockwork, the attacks over the course of the conflict--from the smallest to the most deadly--have the same distribution.
Friederike Sontag

Robotic roach creates order from chaos : Nature News - 8 views

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    posted before, twice:)
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    "The cockroach robot provides a specific model that biologists can test." Apparently drawing hypotheses from an arbitrary model still does the job of getting you funding and published in trendy websites...
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    @Christos: still feeling strong, ey?
pacome delva

Condensation transition in networks and other complex systems - 4 views

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    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
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    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?
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    yeah i could if there's enough interest...? do u know Barabasi ?
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    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...
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    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.....
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    ...but then the CMS YGT didn't really like the project
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