Showing papers by "National Research University – Higher School of Economics published in 2022"

Watermarking schemes for digital images: Robustness overview

Abstract: Digital watermarking is an important scientific direction located at the intersection of cybersecurity and multimedia processing. Digital watermarking is used for digital objects copyright protection and protection against forgery. The importance of those tasks is highlighted by the ongoing COVID-19 pandemic that lasts for more than a year and forced multiple industries to transit to online. The main digital watermarking application include active attackers whose goal is to destroy or damage watermarks. Thus, digital watermarking schemes must be robust to attacks. Despite of the large number of existing digital watermarking schemes, a comprehensive analysis of their robustness towards various attacks does not exist. Our study aims to fill this gap. In this article, latest years findings in digital watermarking are systematized. First of all, we review the most prominent distinctive features of watermarking schemes, attack types, and performance measures to facilitate navigation in digital image watermarking. Then, we introduce classification of digital watermarking schemes by their robustness towards various classes of attacks. We believe this classification could be useful for researchers who aim to choose a digital watermarking scheme for their application with a known set of attacks. Finally, we highlight the most promising solutions that further development could lead to schemes with better robustness compared to existing schemes.

A robust credibility DEA model with fuzzy perturbation degree: An application to hospitals performance

Abstract: Performance evaluation enables decision makers (DMs) to have a better view about the weaknesses and strengths of leading units to improve efficiencies as a crucial goal. Data envelopment analysis (DEA) is the most popular technique to measure performance efficiency of decision making units (DMUs). However, conventional DEA is unable to consider uncertainty of input and output data in the evaluations. In this study, in order to address uncertainty in data, a robust credibility DEA (RCDEA) model has been introduced. First, a fuzzy credibility approach is used to construct fuzzy data. Then, a robust optimization approach is applied to consider uncertainty in constructing fuzzy sets. Moreover, perturbation level is considered as exact and fuzzy values. To illustrate the capability of the proposed model, 28 hospitals are evaluated in northwestern region of Iran and results are analyzed. According to the results, as perturbation degree increases, DMUs get normalized lower efficiencies and vise-versa.

Post-Minkowskian radial action from soft limits and velocity cuts

Abstract: A bstract We consider gravitational massive scalar-scalar scattering from unitarity and demonstrate how intermediate soft graviton behavior and the concept of extracting classical physics from localization of integrands on velocity cuts devise an efficient extraction scheme for computing the classical post-Minkowskian radial action perturbatively. We demonstrate the computational efficiency by deriving the scattering amplitudes in the probe regime to the fifth post-Minkowskian order in arbitrary dimensions.

The interaction of collaboration, note-taking completeness, and performance over 10 weeks of an online course

Abstract: This study examines the effects that online collaborative note-taking has on student performance. The study draws on 10 weeks of data from 273 STEM university students who were collaborating in 61 groups. Group and individual learning were assessed weekly by evaluating the completeness of collaborative note-taking documents and subsequent individual assessments. Analysis suggested up to 23% of the variation in course performance could be attributed to between-group effects. Further, a series of 10 multilevel temporal models suggested no substantive effects in the first half of the course, though in the second half of the course, groups that co-created more complete course notes tended to exhibit improved average student performance. We speculate that the learning advantages afforded to student groups that produce more complete course notes may be delayed. This study adds to the growing body of research into the effects that collaboration has on student learning.

Video-based Frame-level Facial Analysis of Affective Behavior on Mobile Devices using EfficientNets

Abstract: In this paper, we consider the problem of real-time video-based facial emotion analytics, namely, facial expression recognition, prediction of valence and arousal and detection of action unit points. We propose the novel frame-level emotion recognition algorithm by extracting facial features with the single EfficientNet model pre-trained on Affect-Net. The predictions for sequential frames are smoothed using mean or median filters. It is demonstrated that our approach may be implemented even for video analytics on mobile devices. Experimental results for the large scale AffWild2 database from the third Affective Behavior Analysis in-the-wild Competition demonstrate that our simple model is significantly better when compared to the VggFace baseline. In particular, our method is characterized by 0.1-0.5 higher performance measures for test sets in the uni-task Expression Classification, Valence-Arousal Estimation, Action Unit Detection and Multi-Task Learning. Our team took the 3rd place in the multi-task learning challenge and 4th places in Valence-Arousal and Expression challenges. Due to simplicity, the proposed approach may be considered as a new baseline for all four sub-challenges.

Analytical evaluation of cosmological correlation functions

Abstract: A bstract Using the Schwinger-Keldysh-formalism, reformulated in [1] as an effective field theory in Euclidean anti-de Sitter, we evaluate the one-loop cosmological four-point function of a conformally coupled interacting scalar field in de Sitter. Recasting the Witten cosmological correlator as flat space Feynman integrals, we evaluate the one-loop cosmological four-point functions in de Sitter space in terms of single-valued multiple polylogarithms. From it we derive anomalous dimensions and OPE coefficients of the dual conformal field theory at space-like, future infinity. In particular, we find an interesting degeneracy in the anomalous dimensions relating operators of neighboring spins.

Quantum difference equation for Nakajima varieties

Abstract: For an arbitrary Nakajima quiver variety X, we construct an analog of the quantum dynamical Weyl group acting in its equivariant K-theory. The correct generalization of the Weyl group here is the fundamental groupoid of a certain periodic locally finite hyperplane arrangement in $${{\,\mathrm{Pic}\,}}(X)\otimes {\mathbb {C}}$$ . We identify the lattice part of this groupoid with the operators of quantum difference equation for X. The cases of quivers of finite and affine type are illustrated by explicit examples.

Why Botter: How Pro-Government Bots Fight Opposition in Russia

Abstract: There is abundant anecdotal evidence that nondemocratic regimes are harnessing new digital technologies known as social media bots to facilitate policy goals. However, few previous attempts have been made to systematically analyze the use of bots that are aimed at a domestic audience in autocratic regimes. We develop two alternative theoretical frameworks for predicting the use of pro-regime bots: one which focuses on bot deployment in response to offline protest and the other in response to online protest. We then test the empirical implications of these frameworks with an original collection of Twitter data generated by Russian pro-government bots. We find that the online opposition activities produce stronger reactions from bots than offline protests. Our results provide a lower bound on the effects of bots on the Russian Twittersphere and highlight the importance of bot detection for the study of political communication on social media in nondemocratic regimes.

Dust Acoustic Solitons in Saturn’s Dust-Filled Magnetosphere

Abstract: Abstract The possibility is considered of propagation of localized wave structures, such as dust acoustic solitons, in the plasma of the dust-filled Saturn’s magnetosphere, which contains electrons of two sorts (hot and cold) subject to kappa distribution, ions, and charged dust grains. The ranges of possible velocities and amplitudes of the solitons are determined. Soliton solutions for different sizes and concentrations of dust grains in the dust-filled Saturn’s magnetosphere are found.

The Asymmetric Impact of Economic Growth, Energy Consumption, Population, and R&D on Carbon Emission in Turkey: Evidence From ARDL and Non-Linear ARDL

Abstract: The presented study analyzes the asymmetry effect of research and development (R&D) expenditures, population growth, energy consumption, and economic growth on carbon emissions in the sample of Turkey for the period 1990-2020. Nonlinear ARDL is used to control the asymmetry of the variables. Linear ARDL is used to control the long-term and short-term relationships between the variables. The findings show that there is a symmetrical or linear relationship between the variables of R&D expenditures, population growth, energy consumption, economic growth, and carbon emissions. The findings display that economic growth and R&D are effective in reducing carbon emissions, while energy consumption seems to increase carbon emissions. Interestingly, the population was found to be effective in reducing carbon emissions in the study. In order for Turkey to reach its 2050 target, it is necessary to give priority to environmental regulations and policies.

Single-layer atom chip for continuous operation: Design, fabrication and performance

Abstract: A single-layer atom chip for laser cooling and trapping of atoms which operates in a continuous regime is designed and experimentally investigated. The continuous regime was achieved by optimizing the processes of heat released and heat removal from the working area of the atom chip. To do this, we use silver microwires and optimization of the heat dissipation through different heat removal channels. The main channels for heat dissipation are the contacts of the silicon substrate of the atom chip with a copper massive base and the heat sink through the clamps. The design of the atom chip ensures efficient heat transfer from the work area to the periphery through the metal layer of the atom chip. Using continuous operation regime, we cooled and trapped about 3 ∙ 105 atoms near the atom chip.

New avenues and challenges in semantic map research (with a case study in the semantic field of emotions)

Abstract: Abstract In this paper, we present an overview of the methods associated with semantic maps, focusing on current challenges and new avenues for research in this area, which are at the core of the contributions to this special issue. Among the fundamental questions are: (1) the validity of the basic assumption, namely, to what extent does coexpression reflect semantic similarity; (2) the central problem of identifying analytical primitives in the domain of semantics; (3) the methods of inference used for creating coexpression maps and the representation techniques (graph structure vs. Euclidean space) as well as their respective merits (including the goodness of fit of the models); and (4) the use of semantic maps to support diachronic and synchronic descriptions of individual languages. In order to illustrate and discuss key aspects, we conduct an experiment in the semantic field of emotions, for which we construct a classical semantic map based on the dataset of CLICS 3 .

Insurers’ responses to cyber crime: Evidence from Russia

Abstract: This study aims to identify effective responses to cyber crime in the insurance industry. Survey responses from Moscow-based employees holding key positions in the leading insurance companies have been collected. The study analyses awareness of, attitudes to, and approaches to cyber security, as well as the incidence and impact of breaches or attacks. According to the experts, complying with laws or regulations and preventing fraud or theft are the main reasons for investing in cyber security. Phishing, viruses, and unauthorised use of computers, networks or servers by staff are the most widely spread threats to cyber security. Russian insurers often undertake additional staff training or change their policies in response to cyber breaches. Strategic recommendations were elaborated for industry professionals.

General lower and upper bounds under minimum-error quantum state discrimination

Abstract: For the optimal success probability under minimum-error discrimination between $r\geq2$ arbitrary quantum states prepared with any a priori probabilities, we find new general analytical lower and upper bounds and specify the relations between these new general bounds and the general bounds known in the literature. We also present the example where the new general analytical bounds, lower and upper, on the optimal success probability are tighter than most of the general analytical bounds known in the literature. The new upper bound on the optimal success probability explicitly generalizes to $r>2$ the form of the Helstrom bound. For $r=2$, each of our new bounds, lower and upper, reduces to the Helstrom bound.

Reduced arc schemes for Veronese embeddings and global Demazure modules

Abstract: We consider arc spaces for the compositions of Plücker and Veronese embeddings of the flag varieties for simple Lie groups of types ADE. The arc spaces are not reduced and we consider the homogeneous coordinate rings of the corresponding reduced schemes. We show that each graded component of a homogeneous coordinate ring is a cocyclic module over the current algebra and is acted upon by the algebra of symmetric polynomials. We show that the action of the polynomial algebra is free and that the fiber at the special point of a graded component is isomorphic to an affine Demazure module whose level is the degree of the Veronese embedding. In type A 1 (which corresponds to the Veronese curve), we give the precise list of generators of the reduced arc space. In general type, we introduce the notion of global higher level Demazure modules, which generalizes the standard notion of the global Weyl modules, and identify the graded components of the homogeneous coordinate rings with these modules.