6 research outputs found
Cover – from See how it’s done to You get a pat on the shoulder (titles of popular Bulgarian songs)
Get PDFCover is a common and valuable musical phenomenon that needs to be studied, well-defined, and classified. This report is an initial attempt of the author in this direction. Certain songs and artists provide arguments for cover’s significance at a micro and macro-structural level. Cover is the main carrier of models and stylistic features that are modified and presented in different musical environments. The interpreted works influence the processes of development and evolution in popular music, unite them and promote the creation of new styles such as rock‘n‘roll. Covers of some types of music can be perceived more easily by a wider range of listeners. This is essential for the upgrading and cultivation of musical taste
Assessing the diversification of energy mix with the methods of entropy and hierarchy of information
No full textEnergy systems are a typical example of complex and dynamic systems and the study of their structure is of particular interest in theoretical and practical terms. Becoming the main trend of diversification and, renewable energies play important role in the evolution and dynamics of energy balances at the international, national, and local levels. Usually, natural sciences use Information Theory and the concept of entropy to assess diversity, uncertainty, and chaos in systems with a high number of components. An alternative approach to assess system complexity is to consider these issues from point of view of the concentration of resources, dominance, and hierarchy in the interactions between system components. This report presents an original method developed by the author for assessing the hierarchy in energy mix structures and the role of renewable energies. The author’s studies in the field of energy explore the evolution of markets and energy balances (energy mixes) on an international, regional and national level with a special focus on the European Union and Bulgaria. The hierarchy approach provides results in a more logical, objective, and balanced format and improves the analysis in terms of energy security and diversification. In this paper, is presented a research on the structure of the energy mix in Bulgaria
Bootstrapping non-stationary stochastic volatility
Get PDFThis is the author accepted manuscript. The final version is available from Elsevier via the DOI in this recordIn this paper we investigate to what extent the bootstrap can be applied to conditional mean models, such as regression or time series models, when the volatility
of the innovations is random and possibly non-stationary. In fact, the volatility of
many economic and financial time series displays persistent changes and possible
non-stationarity. However, the theory of the bootstrap for such models has focused
on deterministic changes of the unconditional variance and little is known about
the performance and the validity of the bootstrap when the volatility is driven
by a non-stationary stochastic process. This includes near-integrated exogenous
volatility processes as well as near-integrated GARCH processes, where the conditional variance has a diffusion limit; a further important example is the case where
volatility exhibits infrequent jumps. This paper fills this gap in the literature by developing conditions for bootstrap validity in time series and regression models with
non-stationary, stochastic volatility. We show that in such cases the distribution of
bootstrap statistics (conditional on the data) is random in the limit. Consequently,
the conventional approaches to proofs of bootstrap consistency, based on the notion of weak convergence in probability of the bootstrap statistic, fail to deliver
the required validity results. Instead, we use the concept of ‘weak convergence in
distribution’ to develop and establish novel conditions for validity of the wild bootstrap, conditional on the volatility process. We apply our results to several testing
problems in the presence of non-stationary stochastic volatility, including testing in a location model, testing for structural change using CUSUM-type functionals,
and testing for a unit root in autoregressive models. Importantly, we work under
sufficient conditions for bootstrap validity that include the absence of statistical
leverage effects, i.e., correlation between the error process and its future conditional
variance. The results of the paper are illustrated using Monte Carlo simulations,
which indicate that a wild bootstrap approach leads to size control even in small
samples.Danish Council for Independent ResearchUniversity of BolognaItalian Ministry of University and Researc
TREBLE: Fast Software Updates by Creating an Equilibrium in an Active Software Ecosystem of Globally Distributed Stakeholders
Get PDFThis paper presents our experience with TREBLE, a two-year initiative to build the modular base in Android, a Java-based mobile platform running on the Linux kernel. Our TREBLE architecture splits the hardware independent core framework written in Java from the hardware dependent vendor implementations (e.g., user space device drivers, vendor native libraries, and kernel written in C/C++). Cross-layer communications between them are done via versioned, stable inter-process communication interfaces whose backward compatibility is tested by using two API compliance suites. Based on this architecture, we repackage the key Android software components that suffered from crucial post-launch security bugs as separate images. That not only enables separate ownerships but also independent updates of each image by interested ecosystem entities. We discuss our experience of delivering TREBLE architectural changes to silicon vendors and device makers using a yearly release model. Our experiments and industry rollouts support our hypothesis that giving more freedom to all ecosystem entities and creating an equilibrium are a transformation necessary to further scale the world largest open ecosystem with over two billion active devices.\c{opyright} K. S. Yim et al. | ACM 2019. This is the author\u27s version of the work. It is posted here for your personal use. Not for redistribution. The definitive Version of Record was published in ACM TECS, https://doi.org/10.1145/335823
Clinical Analysis of Pregnant Women with COVID-19 in Bulgaria
Get PDFIntroduction: The coronavirus disease 2019 (COVID-19) pandemic remains a global threat. The clinical course of the infection in pregnant women and its impact on their fetuses are currently discussed topics among medical specialists.Aim: The aim of this article is to evaluate the clinical course of COVID-19 in pregnant women and assess the effects of the disease on their fetuses.Material and Methods: Ten pregnant women in the third trimester with COVID-19, hospitalised at the labour ward of St. Anna Hospital in Varna were examined between November 2020 and May 2021. A clinical and laboratory study was conducted. The nasopharyngeal swab samples were collected and tested positive using reversed transcriptase-polymerase chain reaction (COVID-19 real-time PCR). Cardiotocography and abdominal ultrasound were used to evaluate the fetuses’ condition. Statistic methods were used for data processing.Results: The clinical presentation of coronavirus infection of the ten hospitalized pregnant women with COVID-19 includes fever, cough, shortness of breath, and fatigue. The laboratory tests revealed absolute lymphopenia, elevated C-reactive protein, and elevated D-dimer. All women showed evidence of hypoxemia, accompanied in 90% of cases by respiratory alkalosis. No signs of preterm birth or presence of fetal distress were established.Conclusion: The clinical course of COVID-19 showed no difference in pregnant women and non-pregnant individuals. However, the physiological adaptation to pregnancy with its clinical and laboratory variations may make assessing the effects of COVID-19 on pregnant women difficult. In mild and moderate cases, COVID-19 does not aggravate the course of pregnancy and does not threaten the fetal condition. Additional systematic studies are needed to evaluate the effects of COVID-19 on pregnant women.
Whole-brain annotation and multi-connectome cell typing of Drosophila
Get PDFThe fruit fly Drosophila melanogaster has emerged as a key model organism in neuroscience, in large part due to the concentration of collaboratively generated molecular, genetic and digital resources available for it. Here we complement the approximately 140,000 neuron FlyWire whole-brain connectome1 with a systematic and hierarchical annotation of neuronal classes, cell types and developmental units (hemilineages). Of 8,453 annotated cell types, 3,643 were previously proposed in the partial hemibrain connectome2, and 4,581 are new types, mostly from brain regions outside the hemibrain subvolume. Although nearly all hemibrain neurons could be matched morphologically in FlyWire, about one-third of cell types proposed for the hemibrain could not be reliably reidentified. We therefore propose a new definition of cell type as groups of cells that are each quantitatively more similar to cells in a different brain than to any other cell in the same brain, and wevalidate this definition through joint analysis of FlyWire and hemibrain connectomes. Further analysis defined simple heuristics for the reliability of connections between brains, revealed broad stereotypy and occasional variability in neuron count and connectivity, and provided evidence for functional homeostasis in the mushroom body through adjustments of the absolute amount of excitatory input while maintaining the excitation/inhibition ratio. Our work defines a consensus cell type atlas for the fly brain and provides both an intellectual framework and open-source toolchain for brain-scale comparative connectomics. © The Author(s) 2024.TRUEsciescopu
