Shapeev A.,Skolkovo Innovation Center
Computational Materials Science | Year: 2017
In this paper I propose a new model for representing the formation energies of multicomponent crystalline alloys as a function of atom types. In the cases when displacements of atoms from their equilibrium positions are not large, the proposed method has a similar accuracy as the state-of-the-art cluster expansion method, and a better accuracy when the fitting dataset size is small. The proposed model has only two tunable parameters—one for the interaction range and one for the interaction complexity. © 2017 Elsevier B.V.
Yarotsky D.,Skolkovo Innovation Center
Neural Networks | Year: 2017
We study expressive power of shallow and deep neural networks with piece-wise linear activation functions. We establish new rigorous upper and lower bounds for the network complexity in the setting of approximations in Sobolev spaces. In particular, we prove that deep ReLU networks more efficiently approximate smooth functions than shallow networks. In the case of approximations of 1D Lipschitz functions we describe adaptive depth-6 network architectures more efficient than the standard shallow architecture. © 2017 Elsevier Ltd
Bourdine A.V.,Skolkovo Innovation Center
Proceedings of SPIE - The International Society for Optical Engineering | Year: 2017
This work presents method for design of precision positioning scheme for mode division multiplexing (MDM) system channels at the end of link few-mode optical fiber with enlarged core diameter. Proposed solution is based on combination of well known overlap integral method and earlier on developed Gaussian approximation modification generalized for analysis of silica weakly guiding optical fibers with one outer solid cladding and arbitrary axially-symmetric refractive index profile. The last one provides a passage to analytical expressions for any order mode coupling coefficients under taking into account set precision radial misalignment. By using presented method we computed launching parameters of 5-mode MDM multiplexer channels to the end of few-mode optical fiber samples with enlarged core diameter up to 42 μm and reduced differential mode delay provided by specially designed graded refractive index profile. According to computation results, it is able to transmit the almost total one MDM channel mode power to only one optical fiber particular mode with the same azimuthal order by corresponding combination between mode field diameter and precision radial misalignment. © 2017 SPIE.
Orekhov A.N.,Skolkovo Innovation Center |
Bobryshev Y.V.,University of New South Wales |
Chistiakov D.A.,Moscow State University
Cardiovascular Research | Year: 2014
Pericytes, which are also known as Rouget cells or perivascular cells, are considered to represent a likely distinct pool of vascular cells that are extremely branched and located mostly in the periphery of the vascular system. The family of pericytes is a heterogeneous cell population that includes pericytes and pericyte-like cells. Accumulated data indicate that networks of pericyte-like cells exist in normal non-atherosclerotic intima, and that pericyte-like cells can be involved in the development of atherosclerotic lesions from the very early stages of disease. The pathogenic role of arterial pericytes and pericyte-like cells also might be important in advanced and complicated atherosclerotic lesions via realizing mechanisms of vascular remodelling, ectopic ossification, intraplaque neovascularization, and probably thrombosis. © The Author 2014.
Shapeev A.V.,Skolkovo Innovation Center
Multiscale Modeling and Simulation | Year: 2016
Density functional theory offers a very accurate way of computing materials properties from first principles. However, it is too expensive for modeling large-scale molecular systems whose properties are, in contrast, computed using interatomic potentials. The present paper considers, from a mathematical point of view, the problem of constructing interatomic potentials that approximate a given quantum-mechanical interaction model. In particular, a new class of systematically improvable potentials is proposed, analyzed, and tested on an existing quantum-mechanical database. © 2016 Societ y for Industrial and Applied Mathematics.
Dymarsky A.,Skolkovo Innovation Center
Journal of High Energy Physics | Year: 2015
Abstract: We discuss to what extent the full set of Ward Identities constrain the four-point function of the stress-energy tensors or conserved currents in a conformal field theory. We calculate the number of kinematically unrestricted functional degrees of freedom governing the corresponding correlators and find that it matches the number of functional degrees of freedom governing scattering amplitudes of some “dual” massless particles in the auxiliary Minkowski space. We also formulate the conformal bootstrap constraints for the correlators in question in terms of only unrestricted degrees of freedom. As a by-product we find interesting parallels between solving Ward Identities in coordinate and momentum space. © 2015, The Author(s).
Krimpenfort P.,Netherlands Cancer Institute |
Berns A.,Netherlands Cancer Institute |
Berns A.,Skolkovo Innovation Center
Cell | Year: 2015
In mouse intestinal tumors induced by the inhibition of APC, the restoration of APC function causes complete tumor regression with normal differentiation and return of stem cell function irrespective of whether tumors also carried mutations in Kras and p53. These findings by Dow et al. validate the Wnt pathway as an exquisite target for intervention. © 2015 Elsevier Inc.
News Article | September 28, 2012
Mark Zuckerberg is set to meet with Russian prime minister Dmitry Medvedev on Monday during a trip to Russia, where Facebook use is growing. According to a report from French news agency AFP, the meeting will take place at the Skolkovo Innovation Center, a technology hub and science park being built on the outskirts of Moscow with support from American companies including Microsoft, Intel, and IBM. Zuckerberg will also attend the Facebook World Hack in Moscow on the same day. Medvedev, for his part, is known as a champion of social media While Zuckerberg's social empire currently plays second fiddle to the homegrown network VKontakte in Russia, it is still extremely popular. Medvedev, for his part, is known as a champion of social media, maintaining a pair of Twitter accounts in Russian and English with a combined following of more than 1.8 million users, alongside accounts on Facebook, VKontakte and LiveJournal. As AFP points out, Facebook's Russian connections run deep — investment firm Digital Sky Technologies (DST), run by oligarch Yuri Milner, is estimated to have built up a stake of more than 10 percent in the company prior to its May 18th IPO, beginning with a $200 million investment in 2009. Despite this, Zuckerberg has reportedly never visited the country, preferring to focus on operations back home in California.
News Article | June 25, 2012
In recent years, the US government has created research agencies for homeland security, intelligence, and energy — all modeled on the Pentagon’s mad-scientist arm, Darpa. Now Russia has gotten the bug, too. Russian industry and defense leaders announced plans last week to bankroll the Russian Foundation for Advanced Research Projects in the Defense Industry. Russia’s newly re-coronated president, Vladimir Putin, has already sent a bill to parliament to authorize the agency, which will be tasked with keeping track of projects that “can ensure Russian superiority in defense technology,” according to news service RIA Novosti. One possible location is near the Gromov Flight Research Institute — an experimental aircraft test base — to Moscow’s southeast. The future site, though, may also resemble the Skolkovo Innovation Center, a sort of Silicon Valley for Russia’s high-tech companies located on the city’s opposite end. But instead of focusing on civilian IT and biotech like at Skolkovo, the companies near Gromov would take charge of “all high-risk and fundamental research projects in the military-industrial complex,” Dmitry Rogozin, chief of Russia’s defense industry, said. Basically, Russia wants to modernize, and needs its own far-out research department to do it. Its military is getting old and risks becoming dependent on other (read: more advanced) countries. It’s also a part of a larger Russian push for more military tech. And there’s no telling what projects the agency could come up with. Perhaps the agency, when open for business, can take on the task of controlling our minds and constructing robots that will keep the human brain alive forever. It’s also necessary if Russia is serious about moving forward on plans to build advanced drones and new long-range bombers. Russia has a stealthy new fighter, the PAK FA (or T-50), but it probably doesn’t have the radar, avionics and other advanced technology like the F-22. Russia is interested in making directed energy weapons, like the Pentagon’s Active Denial System, while at the same time being more willing to use them to zap crowds. There are plans to upgrade submarines and stealth-killing radars. There is also competition from China, which is boosting its defense budget and has its own Darpa-like tech programs. China has a stealth fighter of its own: the J-20. China’s navy may not be alarming, but its missiles are increasingly lethal, and Beijing is catching up in space. Another problem is that Russia has traditionally built its military around quantity, not quality. It’s been slow to modernize, and the civilian sector has historically been left out, nor did it compete for contracts. That’s changed, but scattered private firms without oversight can also bog down development. Russia’s missile-defense-dodging Bulava ballistic missile was prone to delays and test failures during development. Officials blamed the hundreds of subcontractors supplying parts, with varying degrees of quality. Russian defense subcontractors are also prone to duplicating work because Russia has no centralized database to track research projects. Still, it won’t be as easy as building a database. The agency comes just as Russia is preparing a major arms build-up after nearly two decades of austerity. That means Darpaski has some catching up to do.