Group items tagged Nature - Advanced Concepts Team

Accelerated search for materials with targeted properties by adaptive design - 0 views

www.nature.com/...ncomms11241.html

technology machine learning PHY materials

shared by jcunha on 10 May 16 - No Cached

jcunha on 10 May 16

There has been much recent interest in accelerating materials discovery. High-throughput calculations and combinatorial experiments have been the approaches of choice to narrow the search space. The emphasis has largely been on feature or descriptor selection or the use of regression tools, such as least squares, to predict properties. The regression studies have been hampered by small data sets, large model or prediction uncertainties and extrapolation to a vast unexplored chemical space with little or no experimental feedback to validate the predictions. Thus, they are prone to be suboptimal. Here an adaptive design approach is used that provides a robust, guided basis for the selection of the next material for experimental measurements by using uncertainties and maximizing the 'expected improvement' from the best-so-far material in an iterative loop with feedback from experiments. It balances the goal of searching materials likely to have the best property (exploitation) with the need to explore parts of the search space with fewer sampling points and greater uncertainty.

<div class="cArrow"> </div><div class="cContentInner">There has been much recent interest in accelerating materials discovery. High-throughput calculations and combinatorial experiments have been the approaches of choice to narrow the search space. The emphasis has largely been on feature or descriptor selection or the use of regression tools, such as least squares, to predict properties. The regression studies have been hampered by small data sets, large model or prediction uncertainties and extrapolation to a vast unexplored chemical space with little or no experimental feedback to validate the predictions. Thus, they are prone to be suboptimal. Here an adaptive design approach is used that provides a robust, guided basis for the selection of the next material for experimental measurements by using uncertainties and maximizing the 'expected improvement' from the best-so-far material in an iterative loop with feedback from experiments. It balances the goal of searching materials likely to have the best property (exploitation) with the need to explore parts of the search space with fewer sampling points and greater uncertainty.</div>

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jcunha on 11 May 16

Can AI create the next wonder material? http://www.nature.com/news/can-artificial-intelligence-create-the-next-wonder-material-1.19850?WT.ec_id=NATURE-20160505&spMailingID=51301208&spUserID=MTEzODM0NjYzMzgS1&spJobID=920498312&spReportId=OTIwNDk4MzEyS0

<div class="cArrow"> </div><div class="cContentInner">Can AI create the next wonder material? <a href="http://www.nature.com/news/can-artificial-intelligence-create-the-next-wonder-material-1.19850?WT.ec_id=NATURE-20160505&spMailingID=51301208&spUserID=MTEzODM0NjYzMzgS1&spJobID=920498312&spReportId=OTIwNDk4MzEyS0" rel="nofollow" target="_blank">http://www.nature.com/news/can-artificial-intelligence-create-the-next-wonder-material-1.19850?WT.ec_id=NATURE-20160505&spMailingID=51301208&spUserID=MTEzODM0NjYzMzgS1&spJobID=920498312&spReportId=OTIwNDk4MzEyS0</a></div>

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Mutations in DMRT3 affect locomotion in horses and spinal circuit function in mice : Na... - 0 views

www.nature.com/...nature11399.html

gates BIO biomimetics

shared by LeopoldS on 03 Sep 12 - No Cached

LeopoldS on 03 Sep 12

isn't it strange that one single gene mutation can enable or disable such a complex behavioural pattern? anything to take advantage of in our gate study (Guido?)

<div class="cArrow"> </div><div class="cContentInner">isn't it strange that one single gene mutation can enable or disable such a complex behavioural pattern? anything to take advantage of in our gate study (Guido?)</div>

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One or more bound planets per Milky Way star from microlensing observations : Nature : ... - 1 views

www.nature.com/...nature10684.html

exploration

shared by LeopoldS on 11 Jan 12 - No Cached

LeopoldS on 11 Jan 12

Plenty of other earths ....

<div class="cArrow"> </div><div class="cContentInner">Plenty of other earths ....</div>

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IPCC models getting mushy | Financial Post - 2 views

opinion.financialpost.com/...ipcc-models-getting-mushy

models climate

shared by Dario Izzo on 17 Sep 13 - No Cached

Dario Izzo on 17 Sep 13

why am I not surprised .....

<div class="cArrow"> </div><div class="cContentInner">why am I not surprised .....</div>

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Athanasia Nikolaou on 17 Sep 13

http://www.academia.edu/4210419/Can_climate_models_explain_the_recent_stagnation_in_global_warming A view of well-respected scientists on how to proceed from here, that was rejected from Nature. In any case, a long way to go...

<div class="cArrow"> </div><div class="cContentInner"><a href="http://www.academia.edu/4210419/Can_climate_models_explain_the_recent_stagnation_in_global_warming" rel="nofollow" target="_blank">http://www.academia.edu/4210419/Can_climate_models_explain_the_recent_stagnation_in_global_warming</a> A view of well-respected scientists on how to proceed from here, that was rejected from Nature. In any case, a long way to go...</div>

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LeopoldS on 18 Sep 13

unfortunately it's too early to cheer and burn more coal ... there is also a nice podcast associated to this paper from nature Recent global-warming hiatus tied to equatorial Pacific surface cooling Yu Kosaka & Shang-Ping Xie Nature 501, 403-407 (19 September 2013) doi:10.1038/nature12534 Received 18 June 2013 Accepted 08 August 2013 Published online 28 August 2013 Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3, 4, 5, 6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas

<div class="cArrow"> </div><div class="cContentInner">unfortunately it's too early to cheer and burn more coal ... there is also a nice podcast associated to this paper from nature Recent global-warming hiatus tied to equatorial Pacific surface cooling Yu Kosaka & Shang-Ping Xie Nature 501, 403-407 (19 September 2013) doi:10.1038/nature12534 Received 18 June 2013 Accepted 08 August 2013 Published online 28 August 2013 Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century1, 2, challenging the prevailing view that anthropogenic forcing causes climate warming. Various mechanisms have been proposed for this hiatus in global warming3, 4, 5, 6, but their relative importance has not been quantified, hampering observational estimates of climate sensitivity. Here we show that accounting for recent cooling in the eastern equatorial Pacific reconciles climate simulations and observations. We present a novel method of uncovering mechanisms for global temperature change by prescribing, in addition to radiative forcing, the observed history of sea surface temperature over the central to eastern tropical Pacific in a climate model. Although the surface temperature prescription is limited to only 8.2% of the global surface, our model reproduces the annual-mean global temperature remarkably well with correlation coefficient r = 0.97 for 1970-2012 (which includes the current hiatus and a period of accelerated global warming). Moreover, our simulation captures major seasonal and regional characteristics of the hiatus, including the intensified Walker circulation, the winter cooling in northwestern North America and the prolonged drought in the southern USA. Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas </div>

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Reducing the contact time of a bouncing drop : Nature : Nature Publishing Group - 2 views

www.nature.com/...nature12740.html

bio science

shared by Marcus Maertens on 20 Nov 13 - No Cached

Thijs Versloot liked it

Marcus Maertens on 20 Nov 13

The reason why butterflies do not get wet wings.

<div class="cArrow"> </div><div class="cContentInner">The reason why butterflies do not get wet wings.</div>

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Nature: Spawning rings of exceptional points out of Dirac cones - 3 views

www.nature.com/...nature14889.html

technology lasers QM PHY Dirac Cone

shared by jcunha on 10 Sep 15 - No Cached

LeopoldS liked it

jcunha on 10 Sep 15

Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?

<div class="cArrow"> </div><div class="cContentInner">Dirac cones, a band-structure of two cones touching each other, are the key to understand graphene exceptional properties. They also appear in the theory of photon waveguides and atoms in optical lattices. In here, the study of a Dirac cone deformation in an open system (a system that is perturbed by external agents) lead to the deformation of the Dirac cone, meaning a change in the fundamental properties of the system. This change is such that strange phenomena such as unidirectional transmission or reflection or lasers with single mode (really single) operation can be achieved. Proved experimentally in photonic crystals. New way for extremely pure lasers?</div>

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Exotic matter : Insight : Nature - 5 views

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

nan phy

shared by jmlloren on 03 Aug 10 - Cached

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jmlloren on 03 Aug 10

Trends in materials and condensed matter. Check out the topological insulators. amazing field.

<div class="cArrow"> </div><div class="cContentInner">Trends in materials and condensed matter. Check out the topological insulators. amazing field.</div>

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...12 more comments...
Luzi Bergamin on 03 Aug 10

Aparently very interesting, will it survive the short hype? Relevant work describing mirror charges of topological insulators and the classical boundary conditions were done by Ismo and Ari. But the two communities don't know each other and so they are never cited. Also a way to produce new things...

<div class="cArrow"> </div><div class="cContentInner">Aparently very interesting, will it survive the short hype? Relevant work describing mirror charges of topological insulators and the classical boundary conditions were done by Ismo and Ari. But the two communities don't know each other and so they are never cited. Also a way to produce new things...</div>

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jmlloren on 04 Aug 10

Thanks for noticing! Indeed, I had no idea that Ari (don't know Ismo) was involved in the field. Was it before Kane's proposal or more recently? What I mostly like is that semiconductors are good candidates for 3D TI, however I got lost in the quantum field jargon. Yesterday, I got a headache trying to follow the Majorana fermions, the merons, skyrnions, axions, and so on. Luzi, are all these things familiar to you?

<div class="cArrow"> </div><div class="cContentInner">Thanks for noticing! Indeed, I had no idea that Ari (don't know Ismo) was involved in the field. Was it before Kane's proposal or more recently? What I mostly like is that semiconductors are good candidates for 3D TI, however I got lost in the quantum field jargon. Yesterday, I got a headache trying to follow the Majorana fermions, the merons, skyrnions, axions, and so on. Luzi, are all these things familiar to you?</div>

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Luzi Bergamin on 04 Aug 10

Ismo Lindell described in the early 90's the mirror charge of what is now called topological insulator. He says that similar results were obtained already at the beginning of the 20th century... Ismo Lindell and Ari Sihvola in the recent years discussed engineering aspects of PEMCs (perfect electro-megnetic conductors,) which are more or less classical analogues of topological insulators. Fundamental aspects of PEMCs are well knwon in high-energy physics for a long time, recent works are mainly due to Friedrich Hehl and Yuri Obukhov. All these works are purely classical, so there is no charge quantisation, no considerations of electron spin etc. About Majorana fermions: yes, I spent several years of research on that topic. Axions: a topological state, of course, trivial :-) Also merons and skyrnions are topological states, but I'm less familiar with them.

<div class="cArrow"> </div><div class="cContentInner">Ismo Lindell described in the early 90's the mirror charge of what is now called topological insulator. He says that similar results were obtained already at the beginning of the 20th century... Ismo Lindell and Ari Sihvola in the recent years discussed engineering aspects of PEMCs (perfect electro-megnetic conductors,) which are more or less classical analogues of topological insulators. Fundamental aspects of PEMCs are well knwon in high-energy physics for a long time, recent works are mainly due to Friedrich Hehl and Yuri Obukhov. All these works are purely classical, so there is no charge quantisation, no considerations of electron spin etc. About Majorana fermions: yes, I spent several years of research on that topic. Axions: a topological state, of course, trivial :-) Also merons and skyrnions are topological states, but I'm less familiar with them.</div>

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LeopoldS on 04 Aug 10

"Non-Abelian systems1, 2 contain composite particles that are neither fermions nor bosons and have a quantum statistics that is far richer than that offered by the fermion-boson dichotomy. The presence of such quasiparticles manifests itself in two remarkable ways. First, it leads to a degeneracy of the ground state that is not based on simple symmetry considerations and is robust against perturbations and interactions with the environment. Second, an interchange of two quasiparticles does not merely multiply the wavefunction by a sign, as is the case for fermions and bosons. Rather, it takes the system from one ground state to another. If a series of interchanges is made, the final state of the system will depend on the order in which these interchanges are being carried out, in sharp contrast to what happens when similar operations are performed on identical fermions or bosons." wow, this paper by Stern reads really weired ... any of you ever looked into this?

<div class="cArrow"> </div><div class="cContentInner">"Non-Abelian systems1, 2 contain composite particles that are neither fermions nor bosons and have a quantum statistics that is far richer than that offered by the fermion-boson dichotomy. The presence of such quasiparticles manifests itself in two remarkable ways. First, it leads to a degeneracy of the ground state that is not based on simple symmetry considerations and is robust against perturbations and interactions with the environment. Second, an interchange of two quasiparticles does not merely multiply the wavefunction by a sign, as is the case for fermions and bosons. Rather, it takes the system from one ground state to another. If a series of interchanges is made, the final state of the system will depend on the order in which these interchanges are being carried out, in sharp contrast to what happens when similar operations are performed on identical fermions or bosons." wow, this paper by Stern reads really weired ... any of you ever looked into this?</div>

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jmlloren on 04 Aug 10

C'mon Leopold, it's as trivial as the topological states, AKA axions! Regarding the question, not me!

<div class="cArrow"> </div><div class="cContentInner">C'mon Leopold, it's as trivial as the topological states, AKA axions! Regarding the question, not me!</div>

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LeopoldS on 04 Aug 10

just looked up the wikipedia entry on axions .... at least they have some creativity in names giving: "In supersymmetric theories the axion has both a scalar and a fermionic superpartner. The fermionic superpartner of the axion is called the axino, the scalar superpartner is called the saxion. In some models, the saxion is the dilaton. They are all bundled up in a chiral superfield. The axino has been predicted to be the lightest supersymmetric particle in such a model.[24] In part due to this property, it is considered a candidate for the composition of dark matter.[25]"

<div class="cArrow"> </div><div class="cContentInner">just looked up the wikipedia entry on axions .... at least they have some creativity in names giving: "In supersymmetric theories the axion has both a scalar and a fermionic superpartner. The fermionic superpartner of the axion is called the axino, the scalar superpartner is called the saxion. In some models, the saxion is the dilaton. They are all bundled up in a chiral superfield. The axino has been predicted to be the lightest supersymmetric particle in such a model.[24] In part due to this property, it is considered a candidate for the composition of dark matter.[25]"</div>

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jmlloren on 04 Aug 10

Thank's Leopold. Sorry Luzi for being ironic concerning the triviality of the axions. Now, Leo confirmed me that indeed is a trivial matter. I have problems with models where EVERYTHING is involved.

<div class="cArrow"> </div><div class="cContentInner">Thank's Leopold. Sorry Luzi for being ironic concerning the triviality of the axions. Now, Leo confirmed me that indeed is a trivial matter. I have problems with models where EVERYTHING is involved.</div>

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Luzi Bergamin on 04 Aug 10

Well, that's the theory of everything, isn't it?? Seriously: I don't think that theoretically there is a lot of new stuff here. Topological aspects of (non-Abelian) theories became extremely popular in the context of string theory. The reason is very simple: topological theories are much simpler than "normal" and since string theory anyway is far too complicated to be solved, people just consider purely topological theories, then claiming that this has something to do with the real world, which of course is plainly wrong. So what I think is new about these topological insulators are the claims that one can actually fabricate a material which more or less accurately mimics a topological theory and that these materials are of practical use. Still, they are a little bit the poor man's version of the topological theories fundamental physicists like to look at since electrdynamics is an Abelian theory.

<div class="cArrow"> </div><div class="cContentInner">Well, that's the theory of everything, isn't it?? Seriously: I don't think that theoretically there is a lot of new stuff here. Topological aspects of (non-Abelian) theories became extremely popular in the context of string theory. The reason is very simple: topological theories are much simpler than "normal" and since string theory anyway is far too complicated to be solved, people just consider purely topological theories, then claiming that this has something to do with the real world, which of course is plainly wrong. So what I think is new about these topological insulators are the claims that one can actually fabricate a material which more or less accurately mimics a topological theory and that these materials are of practical use. Still, they are a little bit the poor man's version of the topological theories fundamental physicists like to look at since electrdynamics is an Abelian theory.</div>

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jmlloren on 04 Aug 10

I have the feeling, not the knowledge, that you are right. However, I think that the implications of this light quantum field effects are great. The fact of being able to sustain two currents polarized in spin is a technological breakthrough.

<div class="cArrow"> </div><div class="cContentInner">I have the feeling, not the knowledge, that you are right. However, I think that the implications of this light quantum field effects are great. The fact of being able to sustain two currents polarized in spin is a technological breakthrough.</div>

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LeopoldS on 04 Aug 10

not sure how much I can contribute to your apparently educated debate here but if I remember well from my work for the master, these non-Abelian theories were all but "simple" as Luzi puts it ... and from a different perspective: to me the whole thing of being able to describe such non-Abelian systems nicely indicates that they should in one way or another also have some appearance in Nature (would be very surprised if not) - though this is of course no argument that makes string theory any better or closer to what Luzi called reality ....

<div class="cArrow"> </div><div class="cContentInner">not sure how much I can contribute to your apparently educated debate here but if I remember well from my work for the master, these non-Abelian theories were all but "simple" as Luzi puts it ... and from a different perspective: to me the whole thing of being able to describe such non-Abelian systems nicely indicates that they should in one way or another also have some appearance in Nature (would be very surprised if not) - though this is of course no argument that makes string theory any better or closer to what Luzi called reality ....</div>

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Luzi Bergamin on 04 Aug 10

Well, electrodynamics remains an Abelian theory. From the theoretical point of view this is less interesting than non-Abelian ones, since in 4D the fibre bundle of a U(1) theory is trivial (great buzz words, eh!) But in topological insulators the point of view is slightly different since one always has the insulator (topological theory), its surrounding (propagating theory) and most importantly the interface between the two. This is a new situation that people from field and string theory were not really interested in.

<div class="cArrow"> </div><div class="cContentInner">Well, electrodynamics remains an Abelian theory. From the theoretical point of view this is less interesting than non-Abelian ones, since in 4D the fibre bundle of a U(1) theory is trivial (great buzz words, eh!) But in topological insulators the point of view is slightly different since one always has the insulator (topological theory), its surrounding (propagating theory) and most importantly the interface between the two. This is a new situation that people from field and string theory were not really interested in.</div>

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Dario Izzo on 04 Aug 10

guys... how would you explain this to your gran mothers?

<div class="cArrow"> </div><div class="cContentInner">guys... how would you explain this to your gran mothers?</div>

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jmlloren on 05 Aug 10

I will try my best. In a nutshell: http://www.nature.com/news/2010/100714/full/466310a.html

<div class="cArrow"> </div><div class="cContentInner">I will try my best. In a nutshell: <a href="http://www.nature.com/news/2010/100714/full/466310a.html" rel="nofollow" target="_blank">http://www.nature.com/news/2010/100714/full/466310a.html</a></div>

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LeopoldS on 07 Aug 10

*you* tried *your* best .... ??

<div class="cArrow"> </div><div class="cContentInner">*you* tried *your* best .... ??</div>

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Quantum gravitational contributions to quantum electrodynamics : Nature : Nature Publis... - 2 views

www.nature.com/...nature09506.html

science phy

shared by LeopoldS on 10 Nov 10 - No Cached

Bose-Einstein condensation of photons in an optical microcavity : Nature : Nature Publi... - 1 views

www.nature.com/...nature09567.html

physics PHY Bose-Einstein-Condensate BEC

shared by LeopoldS on 25 Nov 10 - No Cached

pacome delva liked it

Unbound or distant planetary mass population detected by gravitational microlensing : N... - 1 views

www.nature.com/...nature10092.html

space phy NRG

shared by LeopoldS on 18 May 11 - No Cached

LeopoldS on 18 May 11

dark matter :-) ?? could there be loads of them?

<div class="cArrow"> </div><div class="cContentInner">dark matter :-) ?? could there be loads of them?</div>

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Nature Publishing Group announces a ban on human authorship - 3 views

www.nature.com/...477244a.html

AI

shared by Luís F. Simões on 12 Sep 11 - No Cached

Nature Publishing Group announced today that its flagship journal, Nature, will no longer accept submissions from humans (Homo sapiens)
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