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Of all publications in the section: 3 552
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Working paper
V. Kleptsyn, A. Okunev, I. Schurov et al. arxiv.org. math. Cornell University, 2015. No. 1507.07638.
We study tunneling of charge carriers in single- and bilayer graphene. We propose an explanation for non-zero "magic angles" with 100% transmission for the case of symmetric potential barrier, as well as for their almost-survival for slightly asymmetric barrier in the bilayer graphene known previously from numerical simulations. Most importantly, we demonstrate that these magic angles are not protected in the case of bilayer and give an explicit example of a barrier with very small electron transmission probability for any angles. This means that one can lock charge carriers by a p-n-p (or n-p-n) junction without opening energy gap. This creates new opportunities for the construction of graphene transistors.
Working paper
Roshchin S., Markova K. EERC Working Paper Series. Economics Education and Research Consortium, 2004. No. 04/05.
Working paper
Lapshin V. A., Sofia Sokhatskaya. Financial Economics. FE. Высшая школа экономики, 2018. No. WP BRP 73/FE/2018.
Estimates of the term structure of interest rates depend heavily on the quality of the market data from which it is constructed. Estimated rates can be incorrect because of observation errors and omissions in the data. The usual way to deal with the heteroscedasticity of observation errors is by introducing weights in the fitting procedure. There is currently no consensus in the literature about the choice of such weights. We introduce a non-parametric bootstrap-based method of introducing observation errors drawn from the empirical distribution into the model data, which allows us to perform a comparison test of different weighting schemes without implicitly favoring one of the contesting models – a common design flaw in comparison studies. We use government bonds from several countries with examples of both liquid and illiquid bond markets. We show that realistic observation errors can greatly distort the estimated yield curve. Moreover, we show that using different weights or other modifications to account for observation errors in bond price data does not always improve the term structure estimates, and often worsens the situation. Based on our comparison, we advise to either use equal weights or weights proportional to the inverse duration in practical applications.
Working paper
Виняр А. И., Налетова П. Р., Казакова П. Н. Linguistics. WP BRP. НИУ ВШЭ, 2017. № 58.
This paper is devoted to denominal verb constructions (DNV construction, in a sense of [Gerdts & Marlett 2008]) in Chukchi language. The goals of this paper are twofold. The first aim is purely descriptive: we will clarify the description of morphosyntax and semantics of six affixal verbs which participate in the formation of DNVs in Chukchi, and also suggest a new way of analyzing the polysemy of these and other Chukchi affixal predicates. The second aim of the paper is to compare DNVs in Chukchi to the closely related phenomenon of Noun Incorporation in the same language. We will highlight the similarities between the two constructions and examine different approaches ([Mithun 1997], [Johns 2007], [Gerdts & Marlett 2008], [Muro 2008] and [Barrie 2006]) to the relationship between these phenomena. We will show that it is natural to analyze Chukchi DNVs as a result of the grammaticalization of noun incorporation construction (see [Mithun 1997] for the similar analysis for Salish and Wakashan languages).
Working paper
Gafarov E., Lazarev A. A., Werner F. Otto-von-Guericke Universitaet, 2010. No. 11.
Working paper
Levin A., Olshanetsky M., Zotov A. arxiv.org. math. Cornell University, 2014
In our recent paper we suggested a natural construction of the classical relativistic integrable tops in terms of the quantum R-matrices. Here we study the simplest case -- the 11-vertex R-matrix and related gl_2 rational models. The corresponding top is equivalent to the 2-body Ruijsenaars-Schneider (RS) or the 2-body Calogero-Moser (CM) model depending on its description. We give different descriptions of the integrable tops and use them as building blocks for construction of more complicated integrable systems such as Gaudin models and classical spin chains (periodic and with boundaries). The known relation between the top and CM (or RS) models allows to re-write the Gaudin models (or the spin chains) in the canonical variables. Then they assume the form of n-particle integrable systems with 2n constants. We also describe the generalization of the top to 1+1 field theories. It allows us to get the Landau-Lifshitz type equation. The latter can be treated as non-trivial deformation of the classical continuous Heisenberg model. In a similar way the deformation of the principal chiral model is also described.
Working paper
A. Levin, Olshanetsky M., Zotov A. arxiv.org. math. Cornell University, 2013
We consider the isomonodromy problems for flat $G$-bundles over punctured elliptic curves $\Sigma_\tau$ with regular singularities of connections at marked points. The bundles are classified by their characteristic classes. These classes are elements of the second cohomology group $H^2(\Sigma_\tau,{\mathcal Z}(G))$, where ${\mathcal Z}(G)$ is the center of $G$. For any complex simple Lie group $G$ and arbitrary class we define the moduli space of flat bundles, and in this way construct the monodromy preserving equations in the Hamiltonian form and their Lax representations. In particular, they include the Painlev\'e VI equation, its multicomponent generalizations and elliptic Schlesinger equations. The general construction is described for punctured curves of arbitrary genus. We extend the Beilinson-Drinfeld description of the moduli space of Higgs bundles to the case of flat connections. This local description allows us to establish the Symplectic Hecke Correspondence for a wide class of the monodromy preserving equations classified by characteristic classes of underlying bundles. In particular, the Painlev\'e VI equation can be described in terms of ${\rm SL}(2, {\mathbb C})$-bundles. Since ${\mathcal Z}({\rm SL}(2, {\mathbb C}))= {\mathbb Z}_2$, the Painlev\'e VI has two representations related by the Hecke transformation: 1) as the well-known elliptic form of the Painlev\'e VI (for the trivial bundles); 2) as the non-autonomous Zhukovsky-Volterra gyrostat (for non-trivial bundles).
Working paper
Verbitsky M., Vuletescu V., Ornea L. arxiv.org. math. Cornell University, 2018
We give a mostly self-contained proof of the classification of non-Kahler surfaces based on Buchdahl-Lamari theorem. We also prove that all non-Kahler surfaces which are not of class VII are locally conformally Kahler.
Working paper
Kurnosov N., Bogomolov F. A., Buonerba F. math. arxive. Cornell University, 2018
We give a new proof of a theorem of Bogomolov, that the only VII_0 surfaces with b_2=0 are those constructed by Hopf and Inoue. The proof follows the strategy of the original one, but it is of purely group-theoretic nature.
Working paper
Kolpachnikov V. Psychology. PSY. Высшая школа экономики, 2013. No. WP BRP 14/PSY/2013.
This article analyzes Client-Centered (Person-Centered) and Existential approaches in counseling and psychotherapy. The proximity of these approaches, both in theoretical and practical terms, is demonstrated
Working paper
Mikova N. Science, Technology and Innovation. WP BRP. National Research University Higher School of Economics, 2016. No. 65/STI/2016 .
This paper proposes a multidisciplinary approach to understanding the future perspectives of climate change. First, it analyzes the possibilities of using the media as an information source for anticipating trends and challenges in this area through exploring the topics that have been actively discussed in the news in the recent 5 years. Second, qualitative and quantitative approaches are combined in this study in order to identify trends of different categories: social, technological, economic, environmental, political and values/culture. It allows integrating the results of trends monitoring obtained from qualitative and quantitative sources and create a complex map of trends. Qualitative approach is based on the literature review and consultations with the experts, while quantitative analysis includes collecting the news from Factiva database and processing it in Vantage Point software using bibliometric analysis, natural language processing, statistical analysis and principal component analysis. The results shown that 58% of trends were validated by the news and its contribution to the final trends list accounts for 25% on average, which means that the media can be considered as a useful additional data source for validating and updating trends. The results of this multidisciplinary study can be of interest to researchers, economists, business representatives and policy makers that are involved in the climate change related activities.
Working paper
Arkhangelskiy T. Linguistics. WP BRP. НИУ ВШЭ, 2014. No. 10.
The Beserman dialect of the Udmurt language has a large number of clitics, mainly discourse markers, which have never been described in detail. These clitics occur very frequently in texts and often appear in clusters. The rules which govern the ordering of clitics within a cluster are especially interesting because the binary relation “clitic A normally precedes clitic B in a cluster” proves to be intransitive, thus making it impossible to use a clitic template to describe the ordering. In this paper, the rules which govern placement of individual clitics in a sentence and their mutual order in clusters are described. The research is based on a corpus of approximately 64,000 tokens and the authorʼs own field data collected in the village of Shamardan, Yukamensk region, Udmurtia.
Working paper
Fedor Bogomolov, De Oliveira B. arxiv.org. math. Cornell University, 2013
A closed symmetric differential of the 1st kind is a differential that locally is the product of closed holomorphic 1-forms. We show that closed symmetric 2-differentials of the 1st kind on a projective manifold $X$ come from maps of $X$ to cyclic or dihedral quotients of Abelian varieties and that their presence implies that the fundamental group of $X$ (case of rank 2) or of the complement $X\setminus E$ of a divisor $E$ with negative properties (case of rank 1) contains subgroup of finite index with infinite abelianization. Other results include: i) the identification of the differential operator characterizing closed symmetric 2-differentials on surfaces (which provides in this case a connection to flat Riemannian metrics) and ii) projective manifolds $X$ having symmetric 2-differentials $w$ that are the product of two closed meromorphic 1-forms are irregular, in fact if $w$ is not of the 1st kind (which can happen), then $X$ has a fibration $f:X \to C$ over a curve of genus $\ge 1$.
Working paper
Remington T. F. Political Science. PS. Высшая школа экономики, 2017. No. WP BRP 53/PS/2017.
Around the world employers complain of shortages of skilled workers. Meantime, educational and training institutions often function as “bridges to nowhere.” This has implications for both social and economic development. When VET systems are ineffective, they either turn out individuals with skills that are poorly matched to the demands of the labor market, or replicate existing social divisions between rich and poor. Economic inequality, both cross-sectional and spatial, undermines the ability of educational and skill-forming institutions to equalize opportunities for young people to acquire skills usable in the labor market. This bifurcates society between a low-wage, low-skill, often informal employment sector, and a higher-skill, higher-wage sector. This problem has grown more acute everywhere as a result of automation and globalization. For this reason, experts and policy-makers around the world have called for upgrading the quality and effectiveness of vocational education and training (VET), in particular by encouraging closer cooperation between employers and schools. They seek to adapt elements of the German and other continental systems where apprenticeships are the most common pathway leading from school to jobs. Building firm-school partnerships requires overcoming two sets of collective action dilemmas, however: coordinating the interests of firms around setting professional standards and curricular goals, and establishing cooperation between employers and schools. The paper argues that cooperative arrangements vary along two dimensions: the “breadth” of collaboration by schools and firms, i.e. how many firms and schools pool their efforts to upgrade VET; and the “depth” of commitment, that is, how costly is the joint commitment by firms and schools to VET. The evidence suggests that there is typically a trade-off between deepening and broadening. The paper compares China and Russia — two large, relatively decentralized countries with different economic systems — with respect to current efforts to close the gap between skills and jobs. It draws conclusions about the nature of the circumstances under which reforms are likely to result in greater deepening or broadening of cooperation. The paper argues that the formation of effective institutions for resolving collective dilemmas result from government initiatives mobilizing existing capacities to respond to challenges in the external environment
Working paper
Баширов М. А. Law. LAW. Высшая школа экономики, 2013. No. WP BRP 29/LAW/2013.
Сloud computing is treated by most of the experts as one of the main trends of information technologies development for forthcoming years. In present article we focus on general overview of the main aspects of cloud computing services legal regime in Russia. Such aspects include, inter alia, intellectual property and contract law matters, taxation issues, execution of the agreements, warranties and representations under cloud computing agreements and personal data regulations.
Working paper
Malykhin N. I., Ushchev P. Basic research program. WP BRP. National Research University Higher School of Economics, 2016. No. WP BRP 140/EC/2016.
We develop a simple partial-equilibrium model of endogenous city structure formation. No production externalities are at work, the only two forces shaping the spatial configurations of the city being love for variety (on the consumer side) and seeking for a better access to the market (on the firm side). We show that, unlike in existing models of a similar nature, our model generates clustering rather than co-agglomeration. Namely, if there are few firms relative to the urban population size, then firms tend to cluster at the city center, while consumers choose to reside on the outskirts. Otherwise, the opposite holds. Although a continuum of equilibrium city structures may emerge, we show that all spatial equilibria are segregated. In addition, the market outcome features spatial price dispersion, even though our framework does not involve imperfect information and search costs on the consumer side.
Working paper
Bershtein M., Gavrylenko P., Marshakov A. arxiv.org. math. Cornell University, 2018
In this paper the relation between the cluster integrable systems and q-difference equations is extended beyond the Painlevé case. We consider the class of hyperelliptic curves when the Newton polygons contain only four boundary points. The corresponding cluster integrable Toda systems are presented, and their discrete automorphisms are identified with certain reductions of the Hirota difference equation. We also construct non-autonomous versions of these equations and find, that their solutions are expressed in terms of 5d Nekrasov functions with the Chern-Simons contributions, while in the autonomous case these equations are solved in terms of the Riemann theta-functions.
Working paper
Cheltsov I., Kuznetsov A. G., Shramov K. arxiv.org. math. Cornell University, 2018
We construct two small resolutions of singularities of the Coble fourfold (the double cover of the four-dimensional projective space branched over the Igusa quartic). We use them to show that all S_6-invariant three-dimensional quartics are birational to conic bundles over the quintic del Pezzo surface with the discriminant curves from the Wiman-Edge pencil. As an application, we check that S_6-invariant three-dimensional quartics are unirational, obtain new proofs of rationality of four special quartics among them and irrationality of the others, and describe their Weil divisor class groups as S_6-representations.