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In patients with psychotic disorders, sleep spindles are reduced, supporting the hypothesis that the thalamus and glutamate receptors play a crucial etio-pathophysiological role, whose underlying mechanisms remain unknown. We hypothesized that a reduced function of NMDA receptors is involved in the spindle deficit observed in schizophrenia.
An electrophysiological multisite cell-to-network exploration was used to investigate, in pentobarbital-sedated rats, the effects of a single psychotomimetic dose of the NMDA glutamate receptor antagonist ketamine in the sensorimotor and associative/cognitive thalamocortical (TC) systems.
Under the control condition, spontaneously-occurring spindles (intra-frequency: 10–16 waves/s) and delta-frequency (1–4 Hz) oscillations were recorded in the frontoparietal cortical EEG, in thalamic extracellular recordings, in dual juxtacellularly recorded GABAergic thalamic reticular nucleus (TRN) and glutamatergic TC neurons, and in intracellularly recorded TC neurons. The TRN cells rhythmically exhibited robust high-frequency bursts of action potentials (7 to 15 APs at 200–700 Hz). A single administration of low-dose ketamine fleetingly reduced TC spindles and delta oscillations, amplified ongoing gamma-(30–80 Hz) and higher-frequency oscillations, and switched the firing pattern of both TC and TRN neurons from a burst mode to a single AP mode. Furthermore, ketamine strengthened the gamma-frequency band TRN-TC connectivity. The antipsychotic clozapine consistently prevented the ketamine effects on spindles, delta- and gamma−/higher-frequency TC oscillations.
The present findings support the hypothesis that NMDA receptor hypofunction is involved in the reduction in sleep spindles and delta oscillations. The ketamine-induced swift conversion of ongoing TC-TRN activities may have involved at least both the ascending reticular activating system and the corticothalamic pathway.
In the 1990's David Schmeidler and Itzhak Gilboa initiated the study of decision making under uncertainty in a completely new framework, without states but with data sets as the information on which to build choice behavior. While the first formulations of Case-Based Decision Theory (CBDT) aimed at applications in economic decision making, this theory which takes data as a primitive concept provides an alternative foundation for deriving beliefs and driving the choice of predictions. This opened a new perspective on old questions in statistics and artificial intelligence. In this review, we summarize these developments in Case-Based Decision Theory and highlight the immensely innovative nature of David Schmeidler's academic work.
We analyse the determinants of football fans’ happiness in the Russian Premier League using facial emotion recognition. We propose a new way of measuring subjective well-being and provide its empirical validation using sports data. Our sample consists of about 10,000 photos from football matches uploaded on the most popular social network in Russia during the seasons 2014/15–2017/18. The dataset of photos is analysed with the Emotion Recognition software, which takes a facial expression in an image as an input and returns the confidence across a set of emotions for each face in the image. Next we use multinomial logistic regression to identify the determinants of happiness. The results show that uncertainty and expectations are important drivers of football fans’ happiness. A win decreases the probability of being unhappy, and the effect becomes stronger for late rounds of a national championship. The change in happiness because of a home team win is stronger for males.
The common approach to predict the price of residential property is the hedonic price model and its extension to the case of spatial autoregression. The hedonic approach models the dependence between the price and internal characteristics of an apartment, house characteristics and external characteristics. To account for the unobserved quality of the surrounding environment price model includes factors of spatial price correlation, where the distance is usually measured as the distance in geographic space. Determining the price the seller focuses not only on the observed and unobserved factors of the apartment, house and its environment but also on the prices of similar marketed objects which can be selected both by geographic proximity and by characteristics similarity. In this paper, we use ensemble clustering approach to measure objects proximity and test that the proximity of objects in the characteristics space along with spatial correlation explains the significant variation in prices that in turn leads to an improvement of predictive ability of the model.
Purpose. This study suggests an alternative to confirmatory content analysis (CA) and empirically demonstrates that explorative CA enables new insights into the mechanism of intellectual capital (IC) disclosure. In so doing, this research contributes to both methodological and empirical advancements in IC disclosure research.
Design/methodology/approach. Employing the assumptions of positive accounting theory and taking book value of intangible assets as a reference, our research design utilizes well-established text-mining (TM) tools based on a least absolute shrinkage and selection operator regression. We assume that the degree of cohesion between officially disclosed and evaluated intangible assets on balance sheets and those contextually delivered in narrative form may affect how IC is ultimately disclosed in annual reports.
Findings. Our main finding is in line with the results and criticism of previous studies. We show that companies do not extensively disclose IC in their annual reports. However, some narrative forms for IC disclosure are identified and confirmed by several robustness checks.
Research limitations/implications. First, the findings provide internal validity only for large US enterprises. These firms have similar, well-structured reporting requirements. This analysis might be enriched by an examination and a comparison of different institutional contexts, such as emerging countries. Second, following previous studies, annual reports serve as the source of data. Consequently, the findings are relevant only for mandatory and voluntary disclosure of IC, mitigating the relevance of this study for contexts of involuntary disclosure.
Originality/value. This study make two contributions. First, we add to the empirical literature by offering one more piece of evidence on whether and, if so, the extent to which companies disclose IC in their annual reports. Second, we provide a further examination of confirmatory CA by proposing a number of statistically validated codes and tokens that are indicators of IC communication by companies.
Using Major League Soccer as a unique dataset, this study examines the direct andindirect role of coaches’ experience in determining team performance. Inspired by labormarket studies, we applied traditional indicators of team salary structure and, unlikeprevious studies, empirically test the hypothesis that coach experience affects the way inwhich team salary distribution inuences performance. Our results suggest that coacheswith experience as professional soccer players improve team performance directly butworsen the negative effect of a skewed s alary distribution. Moreover, experience as aplayer is more important than coaching experience. (JEL D3, J3, M5)
Growing importance of human resources places the role of managers at the core of
company efficiency. However, there are studies that demonstrate the efficiency of teams
without a manager, so-called self-managed teams, is higher comparing with managed
teams. Thus, despite the focus on managerial efficiency in the economic literature, the
issue of whether a team needs amanager is far from settled. In this paper, we use a quasiexperimental
setting from e-Sports (competitive video gaming) to understand whether
the hiring a manager is of benefit to team performance. The empirical part of the study
is based on endogenous switching regression model. This method allows investigating
what performance of self-managed team would be if it will have a manager and vice
versa. The dataset includes the information of prize money and features of top e-Sports
teams in Counter-Strike: Global Offensive (e-Sports discipline) from 2013 to 2017. The
main finding of this study is that managed teams perform better than self-managed ones
but this is not due to the manager.
The most common tools to understand perception of food products are hall tests,
surveys and observations. However, these approaches require large samples to get reliable
results and they are rather costly and time-consuming. Furthermore, they are also highly
expert-dependent and rely on the assumption that study participants can express their
preferences consciously and explicitly. In our paper, we suggest an electroencephalography-
based (EEG) approach to evaluate perceived product similarity in a cross-modal taste-visual
task. We tested two potential neurometrics measured from Fz electrode: the amplitude of the
N400-like evoked response potentials (ERP) and the power of induced gamma oscillations
during 400-600 ms period after visual stimulus presentation. Both metrics showed a strong
correlation with the perceived similarity scores at both individual and group levels; however,
N400-like amplitude had greater inter-subject variability making it less suitable for practical
applications. The results based on the power of induced gamma oscillations (N=18) could be
compared to traditional hall-tests (N=200) and may potentially reveal subtle differences in
food perception that can not be captured in the hall-tests.
In this paper, we address several aspects of applying classical machine learning algorithms to a regression problem. We compare the predictive power to validate our approach on a data about revenue of a large Russian restaurant chain. We pay special attention to solve two problems: data heterogeneity and a high number of correlated features. We describe methods for considering heterogeneity — observations weighting and estimating models on subsamples. We define a weighting function via Mahalanobis distance in the space of features and show its predictive properties on following methods: ordinary least squares regression, elastic net, support vector regression, and random forest.
This study investigates whether economic freedom of a region drives firm performance. Despite the large number of papers about the relationship between economic freedom and growth, there is still little evidence on the role of economic freedom in performance of individual firms. We address this gap in the literature using hierarchical linear modelling, allowing us to investigate regional differences in company level performance. The dataset consists of information about 1096 companies combined with the Index of Economic Freedom for Russian regions during the period 2004 – 2014
In this paper we apply social network analysis to study the boards of directors of 107 large listed Russian firms between 2009 and 2014. Traditional corporate governance metrics, such as demographic characteristics, experience or multiple directorships, confirm a previously established positive trend towards greater independence and better qualification of the boards of Russian firms. We also find a decrease in the centrality of directors, which corroborates the diminishing concentration of power of some directors. The most connected firms have a specific profile since they are larger, have lower market valuations, and stronger ties with government (both due to higher proportions of government owned shares and a greater number of directors who are former politicians). Our findings also demonstrate that the boards of financial
institutions are less connected, whereas political and independent directors are more centralized.
We construct and compare the results of individual investment strategies: take into account trade, dynamics and costs, and assess the benefits of policy diversification. Our analysis is based on a set of 10 major currencies and an extended sample of 16 additional emerging market currencies. We implement foreign exchange strategies in FX markets against the ruble instead of the US dollar, as is customary in the foreign exchange literature. We find that the effectiveness of strategies depends on changing the ruble mode. We also provide evidence that combining strategies based on volatility offers a significant risk-adjusted yield improvement over either of the two strategies independently or with benchmarks.
This paper is devoted to determining the impact of economic policy uncertainty on corporate investment of Russian manufacturing companies. By applying fixed effects models on panel data, it was found that under increasing level of economic policy uncertainty, the companies reduce their investment activity. The effect is most pronounced for large companies. It is important to note that public companies are not affected by the uncertainty of Russian economic policy, however, the European and global economic policy uncertainty has a negative impact on their investments. Testing the robustness by applying the methods of instrumental variables confirms the results. The study suggests that maintaining transparency and stability of economic policy can increase the level of corporate investment.
The paper presents an approach to describe and analyze the accumulation of specific capital in a Soviet design organization during the late Soviet period. The study covers the period from 1968 to 1982. The system of fashion production under the Late Socialism is less explored compared with the Stalin and Thaw periods. The functioning of regional Clothing Design Houses which constituted a specific feature of the Soviet system of fashion production during this period is underexplored as well. Finally, as far as we know this study is the first attempt to apply the Bourdieu’s theory of the field of production to the Soviet fashion production. Typically, researchers do not use sociological theories of fashion production for the analysis of Soviet fashion. The study implies the categories of specific capital, hierarchy, and dynamic of the field of production. The system of fashion production of the Late Soviet period is considered as a particular case of fashion production in a non-capitalist society. There are two components of the study. The first one reconstructs the hierarchy of the Soviet system of fashion production. The second one describes professional strategies to accumulate specific capital and to occupy a position in the field of production. The study focuses on two cases of development and presentation of clothes collections by Perm Clothing Design House during All-Union and cluster meetings of designers in 1968 – 1969 and 1979 – 1982. The paper relies on published research on Soviet fashion history, archive documents, and in-depth interviews with ex-employees of Perm Clothing Design House. The results discuss the applicability of the term of specific capital to the explanation of hierarchy construction processes in the Late Soviet field of production of fashion. The paper contributes to the earlier conclusions about the ambivalent Soviet fashion policy. Also, it introduces the definition of specific capital as official representatives’ appreciation of the balance between the officially approved fashion trend of a season and creative search achieved by designers of a certain Clothing Design House. It suggests that there was a weird combination of socialist and pseudo-market practices penetrating the Soviet fashion field of restricted production.
Understanding neurological mechanisms of motor recovery after stroke is important for selecting appropriate therapeutic and rehabilitation strategies. One of the most widely-used but yet rather controversial MRI predictors is a co-called lesion load on the cortico-spinal tract (CST). This metric corresponds to the overlap between the volumes of the lesion and the cortico-spinal tract which is responsible for conducting neuronal signals that lead to motion generation. In this study we evaluated the potential of the lesion load to explain the motor outcome in a cohort of patients with chronic ischemic stroke. Lesions were automatically identified on structural T1-weighted images using LINDA package. Once lesions are identified, lesion loads on CST were calculated automatically using PALS software package (Ito et al., 2018). Finally, the obtained results were used to classify patients according to their motor outcome using decision tree classifier J48 implemented in WEKA software. However, the classification accuracy was much lower compared to the classification results based on another widely accepted MRI parameter: asymmetry of the fractional anisotropy in the internal capsule of the CST.
The degree of mental attention in childhood and adolescence determines in the future the effectiveness of working memory (ability to store and manipulate information). Attention has been previously found to be related to the prefrontal and parietal areas of the human cortex. But the relationship between attention and white matter properties are still largely unknown. The goal of this study was to identify the relationships between attention and fractional anisotropy (FA) of diffusion MRI in bilateral superior longitudinal fasciculus (in three subdivisions SLF 1- 3), arcuate fasciculus (AF), and corpus callosum (CC) in children and adolescents. Subjects: 14 children (9-11 years) and 13 teenagers (12-15 years). During the experiments participants had to establish a match between the colors on the screen and the colors on the previous slide. The task had six difficulty levels and both performance accuracy (m-score) and reaction time (RT) were measured. There was a positive correlation for m-score and a negative correlation for RT with FA in СС (levels 1-3) in the children's group (p<0.05). On the contrary, when FA increases in the right SLF 3 (level 6), there is a decrease in m-score, and when FA increases in the left SLF 3 and AF, there is an increase in RT at 2,3,4 and 6 levels. In contrast, a decrease in RT with an increase FA of bilateral SLF 3 (level 6) and left AF (level 4) was observed for adolescents, which reflects the redistribution of the roles between fiber tracts with age. FA values of the left (level 2) and right (level 1) SLF 2 negatively correlated with mscore (p <0.05) in the same group. For females (n=13) (regardless the age), there was only a negative correlation for m-score (2,3,5 levels) and the only positive correlation for RT (level 2) with FA of the right SLF 1, left and right SLF 2, in the left SLF 3 and СС (p<0.05). For males (n=13), on the contrary, there were positive correlations between m-score and FA of the СС (1,3,4 levels) and the left SLF 1 (5 level), and inverse correlations between RT and FA for the same fibers of the white matter (1 level) (p<0,05). Interestingly, an increase in FA with age was found in males in all the components of the white matter (p<0.01), except for the СС, and in females, on thecontrary – only in the СС. Further research is needed, taking into account gender, to fully understand the influence of white matter on the development of mental attention.
This research was aimed at analyzing the moderating role of region on the impact of internal and external sources of knowledge on product innovation from a multilevel perspective. This study has made a contribution to the knowledge and innovation management field for small and medium-sized enterprises (SMEs), by analyzing the utilization of internal and external sources of knowledge in rapidly changing environments, such as the Russian business context, with consideration given to regional disparity. Empirical estimations are carried out on the basis of more than 700 Russian manufacturing SMEs, observed in 2018 within the framework of the project, “Factors of Competitiveness and Growth of Russian Manufacturing Enterprises”. Internal and external sources of knowledge were identified through latent variables and a method of hierarchical linear modeling was applied, considering firm-level data nested within different regions. The results obtained, show that in Russian SMEs, when considering the moderation role of the region, internal and external knowledge have a positive impact on product innovation. Moreover, external knowledge contributes more by comparison to internal knowledge. Meanwhile, the region context conditions the strength of the innovation effect for both knowledge sources. The significance of regional conditions in transforming internal and external sources of knowledge into product innovation, requires specific policy elaboration at regional level. Moreover, the dominating role of external knowledge sources for product innovation in SMEs, proves the necessity of specific policy elaboration with regard to the knowledge-sharing infrastructure connecting different business units.
In Russia, many citizens have a deficiency of vitamins and minerals due to their deficiency in the diet. This deficit can be made up by eating fortified foods. This study is devoted to the study of the attitude of Russian consumers to products enriched with vitamins and minerals. The theoretical study of the article is devoted to the identification, justification and grouping of factors that affect the choice of foods enriched with added vitamins and minerals. The article presents the results of a study of consumers’ attitude to salt enriched with iodine as the most important product in the Ural region, for which the problem of iodine deficiency is traditionally acute. According to the study, young people, women, consumers with higher incomes, people who already use iodine-containing vitamins and increased amounts of seafood, people who have a doctor’s prescription for the consumption of these products, as well as those who have formed an understanding of the increased usefulness of this product are willing to pay more for an enriched product.