Cliromospheric activity is found in ten types of stars, both single and binary. Variability at many time scales is reviewed, from minutes to centuries. The emphasis is on what is not understood, incorrecty understood, and understood but not appreciated. Observational results in hand include photometry, spectroscopy, spectrophotometry, speckle interferometry, magnetic flelds, and orbltal period variations. Certain physical mechanisms responsible for variability are discussed, making the distinction between the well-established, tlie suspected, and the posslble. Specific topics
include flares, rotation, differential rotation, synchronization, circularization, starspots, spot models, migratlon periods, spot cycles, magnetic activity cycles, sector structure, Maunder minima,
pulsation, light curve solutions, convective envelope changes, mass transfer, mass loss, and orbital period variations. Specific directions for future research are identified.
Results are presented from a study of variability in the stellar wind of G8 Cygni [07.5 III((f))], based on 33 lUE high resolution spectra taken over ~ 7 days. Significant changes are evident in the Si IV resonance line profiles on timescales as short as ~ 1 hour, cliaracterised by broad absorption enhancements at relatively low velocity (0.5 to 0.7 of the terminal velocity, υ∞) which evolve into high velocity discrete absorption components (at > 0.8 over a period of ~ 1 day. The recurrence timescale for the appearance of the broad features is ~ 15-20 hours. Three well monitored consecutive sequenccs of progressive opacity enhancements are described. Their properties are parameterised and incorporated into a self-consistent phenomenological model where the opacity enhancements and ‘underlying’ wind sure radiatively coupled.
The model results show that the absorption enhancements do not propagate from the photosphere in any simple way, and are not due to spherically symmetric phenomena. We conclude that the discrete absorption variability in G8 Cyg is not due to ‘shells’ or ‘puffs’ of matter, but instcaid arise from material passing through perturbations in the flow, which may be illustrated in terms of spirally wound-up streams.
Ample experimental evidence suggests that sepsis could interfere
with any mitochondrial function; however, the true role of
mitochondrial dysfunction in the pathogenesis of sepsis-induced
multiple organ dysfunction is still a matter of controversy. This
review is primarily focused on mitochondrial oxygen consumption
in various animal models of sepsis in relation to human disease
and potential sources of variability in experimental results
documenting decrease, increase or no change in mitochondrial
respiration in various organs and species. To date, at least three
possible explanations of sepsis-associated dysfunction of the
mitochondrial respiratory system and consequently impaired
energy production have been suggested: 1. Mitochondrial
dysfunction is secondary to tissue hypoxia. 2. Mitochondria are
challenged by various toxins or mediators of inflammation that
impair oxygen utilization (cytopathic hypoxia). 3. Compromised
mitochondrial respiration could be an active measure of survival
strategy resembling stunning or hibernation. To reveal the true
role of mitochondria in sepsis, sources of variability of
experimental results based on animal species, models of sepsis,
organs studied, or analytical approaches should be identified and
minimized by the use of appropriate experimental models
resembling human sepsis, wider use of larger animal species in
preclinical studies, more detailed mapping of interspecies
differences and organ-specific features of oxygen utilization in
addition to use of complex and standardized protocols evaluating
mitochondrial respiration.
In this paper, we are going to characterize the space ${\rm BMO}({\mathbb R}^n)$ through variable Lebesgue spaces and Morrey spaces. There have been many attempts to characterize the space ${\rm BMO}({\mathbb R}^n)$ by using various function spaces. For example, Ho obtained a characterization of ${\rm BMO}({\mathbb R}^n)$ with respect to rearrangement invariant spaces. However, variable Lebesgue spaces and Morrey spaces do not appear in the characterization. One of the reasons is that these spaces are not rearrangement invariant. We also obtain an analogue of the well-known John-Nirenberg inequality which can be seen as an extension to the variable Lebesgue spaces.
In this paper, the variance-constrained H∞ finite-horizon filtering problem is investigated for a class of time-varying nonlinear system under muti-rate communication network and stochastic protocol (SP). The stochastic protocol is employed to determine which sensor obtains access to the muti-rate communication network in order to relieve communication burden. A novel mapping technology is applied to characterize the randomly switching behavior of the data transmission resulting from the utilization of the SP in muti-rate communication network. By using relaxation method, sufficient conditions are derived for the existence of the finite-horizon filter satisfying both the prescribed H∞ performance and the covariance requirement of filtering errors, and the solutions of filters satisfying the above indexes are obtained by using linear matrix inequalities. Finally, the validity and effectiveness of the proposed filter scheme are verified by numerical simulation.
The aim of the article is to present an analysis of variant endings -i and -é. The research was carried out on the base of Czech National Corpus SYN2005. The ending -i is a variant of ending -é in the standard language (it amounts to 4 %). According to the corpora examination, the ending -i can be mainly found in the names of followers and members of social and political movements and institutions. No occurence or sporadic occurrence of the ending -i can be found in names of followers of religious views, suppor-ters of religious movements and members of sects, the names of specialists and sportsmen. The occurence of the form -i depends on the various factors: linguistical layer, semantical group that the word belongs to, type and frequency of the word, context and a text.
A thorough analysis of theoretical and computational properties of Kolmogorov learning algorithm for feedforward neural networks lead us to proposal of efficient sequential and parallel impleinentation. A novel approach to parallelization is presented which combines our previous rcsnlts in order to achieve higher parallel speed-up.