Number of results to display per page
Search Results
3122. Blankenship, R. E.: Molecular mechanisms of photosynthesis
- Creator:
- Šesták, Z.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- photosynthesis research
- Language:
- Multiple languages
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3123. Blaschke product generated covering surfaces
- Creator:
- Barza, Ilie and Ghisa, Dorin
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Blaschke product, covering surface, covering transformation, fundamental domain, and Cantor set
- Language:
- English
- Description:
- It is known that, under very general conditions, Blaschke products generate branched covering surfaces of the Riemann sphere. We are presenting here a method of finding fundamental domains of such coverings and we are studying the corresponding groups of covering transformations.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
3124. Blast load of building structure
- Creator:
- Makovička, Daniel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- blast wave, building, dynamic response, and assessment
- Language:
- English
- Description:
- The paper follows from the theory of explosion and interaction of an impact wave formed by the explosion and a structure..As a rule, a number of simplifying assumptions must be applied as regards the characteristics of the explosion and of the threatened structure to analyze the structure. As example of dynamic analysis of a new reinforced concrete structure, loaded with a blast wave was used to apply the principles of simpflified ingineering analysis of an explosion-loaded structure. The way of structure failure was analyzed based on time courses of calculated internal forces and displacenets of individual structure elements. The criteria of structural elements failure due to explosion load effects were determined as a part of the dynamic structure response assessment. and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3125. Blind source-separation in mixed-signal VLSI
- Creator:
- Valenzuela, Waldo, Carvajal, Gonzalo, and Figueroa, Miguel
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- Independent components analysis, InfoMax, Kurtosis, mixed-signal VLSI, low-power CMOS, on-chip learning, and adaptive silicon circuits
- Language:
- English
- Description:
- This paper describes an implementation of the Kurtosis and InfoMax algorithms for an independent components analysis in mixed-signal CMOS. Our design uses on-chip calibration techniques and local adaptation to compensate for the effect of device mismatch in arithmetic blocks and analog memory cells. We use our design to perform two-input blind source-separation on mixtures of audio signals and mixtures of EEG signals. Our experiments show that the hardware implementation of InfoMax consistently separates the signals within a normalized reconstruction error of less than 10%, while the reconstruction error of Kurtosis varies between 25% and 60%, due to its higher sensitivity to device mismatch and input statistics. Each circuit has a settling time of 8 ms, occupies a die area of 0.016-0.022 mm² and dissipates 15-20 mW of power.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
3126. Block diagonalization
- Creator:
- Koliha, J.J.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- eigenprojection, resolutions of the unit matrix, and block diagonalization
- Language:
- English
- Description:
- We study block diagonalization of matrices induced by resolutions of the unit matrix into the sum of idempotent matrices. We show that the block diagonal matrices have disjoint spectra if and only if each idempotent matrix in the inducing resolution double commutes with the given matrix. Applications include a new characterization of an eigenprojection and of the Drazin inverse of a given matrix.
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
3127. Blood flukes (Digenea: Aporocotylidae) of walking catfishes (Siluriformes: Clariidae): new genus and species from the Mekong River (Vietnam) with comments on related catfish aporocotylids
- Creator:
- Truong, Triet Nhat and Bullard, Stephen A.
- Format:
- bez média and svazek
- Type:
- model:article and TEXT
- Subject:
- taxonomy, Nomasanguinicola canthoensis, Sanguinicola clarias, Plehniella dentata, Clarias macrocephalus, and South East Asia
- Language:
- English
- Description:
- Nomasanguinicola canthoensis gen. et sp. n. infects the branchial vessels of bighead catfish, Clarias macrocephalus Günther (Siluriformes: Clariidae), in the Mekong River near Can Tho, southern Vietnam. Nomasanguinicola differs from all other genera of fish blood flukes (Digenea: Aporocotylidae) by the combination of lacking body spines and by having an anterior sucker with two flanking columns of large denticles, an intestine comprising several short papilla-like caeca, an inverse U-shaped uterus, and an ootype located near the separate genital pores. The new species has an ootype that is posterior to the level of the female genital pore. That feature most easily differentiates it from the only other putative aporocotylid species having an anterior sucker with two flanking columns of large denticles, Plehniella dentata Paperna, 1964 and Sanguinicola clarias Imam, Marzouk, Hassan et Itman, 1984, which have an ootype that is lateral (P. dentata) or anterior (S. clarias) to the level of the female genital pore. These two species apparently lack extant type materials, infect North African catfish, Clarias gariepinus (Burchell), and herein are considered incertae sedis, but likely comprise species of Nomasanguinicola. An updated list of hosts, sites of infection and geographic localities for the six species and three genera of blood flukes that mature in catfishes is provided. The new species is the first fish blood fluke recorded from Vietnam and only the third reported from a walking catfish (Clariidae).
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3128. Blood preassure modulation and cardiovascular protection by melatonin: potential mechanism behind
- Creator:
- Ľudovít Paulis and Fedor Šimko
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, fyziologie, melatonin, hypertenze, oxid dusnatý, volné radikály, sympatický nervový systém, physiology, hypertension, nitric oxide, free radicals, sympathetic nervous system, 14, and 612
- Language:
- English
- Description:
- The production of the pineal hormone melatonin is synchronized with day-night cycle via multisynaptic pathway including suprachiasmatic nucleus linking several physiological functions to diurnal cycle. The recent data indicate that impaired melatonin production is involved in several cardiovascular pathologies including hypertension and ischemic heart disease. However, the mechanisms of melatonin effect on cardiovascular system are still not completely understood. The activation of melatonin receptors on endothelial and vascular smooth muscle cells and antioxidant properties of melatonin could be responsible for the melatonin effects on vascular tone. However, the data from in vitro studies are controversial making the explanation of the melatonin effect on blood pressure in vivo difficult. In vivo, melatonin also attenuates sympathetic tone by direct activation of melatonin receptors, scavenging free radicals or increasing NO availability in the central nervous system. The central and peripheral antiadrenergic action of chronic melatonin treatment might eliminate the mechanisms counter-regulating decreased blood pressure, providing thus additional cardioprotective mechanism. The extraordinary antioxidant activity and antilipidemic effects of melatonin may enhance the modulation of blood pressure by melatonin and probably play the most important role in the amelioration of target organ damage by chronic melatonin treatment. Further investigation of these mechanisms should provide novel knowledge about pathophysiological mechanisms of cardiovascular diseases, additional explanation for their circadian and seasonal variability and potentially generate new impulses for the development of therapeutic arsenal., Ľ. Paulis, F. Šimko., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3129. Blood pressure and heart rate variability response to noninvasive ventilation in patients with exacerbations of chronic obstructive pulmonary disease
- Creator:
- Peter Skyba, Pavol Joppa, Martin Orolín, and Ružena Tkáčová
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Patologie. Klinická medicína, fyziologie, nemoci plic, pulz (lékařství), autonomní nervový systém, physiology, pulmonary diseases, pulse, autonomic nervous system, chronic obstructive pulmonary disease, 14, and 616
- Language:
- English
- Description:
- Sympathetic activation and parasympathetic withdrawal are commonly observed during acute exacerbations of chronic obstructive pulmonary disease (COPD). We have demonstrated previously that noninvasive positive-pressure ventilation (NPPV) improves parasympathetic neural control of heart rate in patients with obstructive sleep apnea. We hypothesized that NPPV may exert such beneficial effects in COPD as well. Therefore, we assessed the acute effects of NPPV on systemic blood pressure and indexes of heart rate variability (HRV) in 23 patients with acute exacerbations of COPD. The measurements of HRV in the frequency domain were computed by an autoregressive spectral technique. The use of NPPV resulted in significant increases of oxygen saturation (from 89.2±1.0 to 92.4±0.9 %, p<0.001) in association with reductions in systolic and diastolic blood pressures and heart rate (from 147±3 to 138±3 mm Hg, from 86±2 to 81±2 mm Hg, from 85±3 to 75±2 bpm, p<0.001 for all variables), and increases in ln-transformed high frequency band of HRV (from 6.4±0.5 to 7.4±0.6 ms2/Hz, p<0.01). Reductions in heart rate and increases in ln-transformed HF band persisted after NP PV withdrawal. In conclusion, these findings suggest that NPPV may cause improvements in the neural control of heart rate in patients with acute exacerbations of COPD., P. Skyba, P. Joppa, M. Orolín, R. Tkáčová., and Obsahuje bibliografii a bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
3130. Blood pressure and hemodynamics: Mayer waves in different phases of ovarian and menstrual cycle in women
- Creator:
- Lutsenko, O. I. and Kovalenko, S. O.
- Format:
- print, bez média, and svazek
- Type:
- article, články, journal articles, model:article, and TEXT
- Subject:
- Fyziologie člověka a srovnávací fyziologie, krevní tlak, blood pressure, spontaneous baroreflex sensitivity, Mayer waves, ovarian-menstrual cycle, 14, and 612
- Language:
- English
- Description:
- The goal of the research is to investigate the special effect of ovarian-menstrual cycle phases on the level of women’s blood pressure and characteristics of Mayer waves. 77 women aged 18-19 were tested under condition close to the state of basal metabolism in follicular phase (I), ovulation (II) and luteal phase (III) of ovarian-menstrual cycle. In phases II and III, the increase of mean and diastolic blood pressure level, in comparison with phase I in the prone position at rest and with psycho-emotional loading, were observed. The distinctions between variation parameters of R-R interval duration, stroke volume and its synchronization in phases II and III, in comparison with phase I, were observed in the prone position at rest, during tilt-test and with psycho-emotional loading. The substantial level of relationship between the power of Mayer waves and mean and diastolic blood pressure, mainly in phase I under conditions of all types, is observed. The maximum peak amplitude of stroke volume spectrogram is associated with pressure levels in the range of 0.04-0.15 Hz (ρ from -0.33 to -0.64). The obtained results indicate the possible participation of spontaneous baroreflex sensitivity characteristics in keeping blood pressure level in women., O. I. Lutsenko, S. O. Kovalenko., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public