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1434. 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

1435. 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

1436. 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

1437. 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

1438. Bludištěm světa? K motivu malby labyrintu románského portálu klášterního kostela v Plasích

Creator:
Skalický, Petr
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
painting, labyrinth, and Monastery Church in Plasy
Language:
Czech
Description:
Nedávný nález románského portálu západního průčelí cisterciáckého kostela v Plasích patří k nejvýznamnější domácí medievistické a také památkářské události posledních let. Výzdoba exteriérové strany jeho tympanonu nese reliéf, v interiéru se nachází unikátní nástěnná malba s motivem labyrintu. Na obou stranách spatřujeme dvakrát opakovaný motivy kříže. Na reliéfu jsou kříže zobrazeny jako procesní, na malbě je kříž akcentován ve středu cesty labyrintem umístěném v centru kříže, který je vymezen pozadím plochy. Obě strany interpretačně spojuje zásadní idea pohybu (procesní kříže, cesta labyrintem), a ta je spjata též se samotnou funkcí portálu; vstupovalo se jím z vnějšího profánního světa do posvátna církve-chrámu (ecclesia). Motiv labyrintu se v umění objevuje od antiky po současnost. V každé z epoch se uplatňoval ve zcela odlišných kontextech, jež korespondovaly s radikálně odlišnými funkcemi konkrétních labyrintů. První labyrint v křesťanském chrámu pochází ze 4. století. Od 9. století jej běžně nalézáme v různých významech v rukopisech. V evropské sakrální architektuře se vyskytovaly přibližně pouze v rozmezí 12. a 15. století. V následných staletích se přesunuly spíše do exteriérů s odlišnými světskými významy (zvl. zahradní bludiště). Labyrint v Plasích je třeba interpretovat na základě soudobých labyrintů dochovaných zejména ve Francii a Itálii a také v zrcadle středověkých etymologických výkladů slova labyrinthus. Na jedné straně reprezentoval nelehkou cestu kříže (imitatio Christi), na druhé formuloval komplikovaný a přitom triumfální vstup do lůna církve. Oba výklady nebyly protikladné, doplňovaly se, a navíc mohly absorbovat další významové roviny. Proto také mohl labyrint v Plasích v jednom ze svých etymologických výkladů (labor et intus) asociovat řádové heslo Ora et labora a v dalších významových odkazech též aktuálně prožívané křížové výpravy do Svaté země, které v té době hýbaly celou Evropou a nebyly živým námětem jen na vladařských dvorech (zakladatelem kláštera byl český panovník), ale právě i v nitru cisterciáckého řádu. and The discovery of the Romanesque portal of the western facade of the Cistercian church in Plasy is one of the most important events of recent years for Czech medievalists and conservationists. The exterior side of its tympanum carries a relief, while on the interior side there is a unique wall painting of a labyrinth. On both sides appear repeated crosses. On the relief they are depicted as processional, while in the painting the theme of the cross is emphasised with one cross in the centre of the way through a labyrinth that is itself set in the centre of another cross delineated in the background. In terms of interpretation, the two sides are linked by the idea of movement (the processional crosses, the path through the labyrinth) and this is also connected with the very function of the portal, through which one moves from the external profane world into the sacral church (ecclesia). The theme of the labyrinth has appeared in art from antiquity up to the present day. In every epoch it has been applied in different contexts that corresponding with the different functions. The first labyrinth in a Christian church dates from the 4th century. From the 9th century the labyrinths appear also in manuscripts. In European sacral architecture, the theme appears only in — roughly — the 12th to 15th centuries. The labyrinth in Plasy needs to be considered with an eye to other labyrinths of the period that have survived, particularly in France and Italy, and to medieval etymological interpretations of the word labyrinthus. Labyrinthus represented the hard way of the cross (imitatio Christi), but also a difficult yet triumphant journey into the womb of the Church. These interpretations were not contradictory but rather complementary and could absorb different levels of meaning. Thus, the labyrinth in Plasy could also be associated in one etymological meaning (labor et intus) with the order’s maxim Ora et labor, and also be an allusion to the crusades, which were causing a great stir throughout Europe at the time and inspired artistic production not just in the courts of rulers, but inside the Cistercian order itself.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1439. Blue radiation stimulates photosynthetic induction in Fagus sylvatica L.

Creator:
Košvancová-Zitová, M., Urban, O., Navrátil, M., Špunda, V., Robson, T. M., and Marek, M. V.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
blue, red ratio, electron transport, non-photochemical quenching, radiation quality, Rubisco activation, and transient limitations of photosynthesis
Language:
Multiple languages
Description:
This study was designed to test the hypothesis that the spectral composition of incident radiation, as defined by the relative proportions of blue (B; λmax = 455 nm) and red (R; λmax = 625 nm) photons, can affect photosynthetic induction, since B photons stimulate stomatal opening and are more effectively absorbed by leaves than R photons. Different stages of photosynthetic induction, primarily determined by the photo-modulation of Rubisco activity and stomata opening, were investigated in dark-adapted leaves of Fagus sylvatica transferred to saturating irradiance [800µmol(photon) m-2 s-1] at B/R ratios of 1/3, 1/1, or 3/1. In agreement with our hypothesis, photosynthesis was induced faster by irradiance with a high B/R ratio (3/1); as demontrated by a higher IS60 (induction state 60 s after leaf illumination) and lower T 90 (the time period required to reach 90 % of maximum steady-state photosynthesis). However, there were no differences in induction between leaves receiving equal (1/1) and low (1/3) B/R ratios. Electron transport was highly sensitive to radiation quality, exhibiting faster induction kinetics with increasing B/R ratio. Such stimulation of carbon-assimilatory processes corresponds with faster activation of Rubisco and lower non-photochemical quenching (NPQ) as the proportion of B photons is increased. In contrast, the kinetics of stomatal opening was independent of the spectral composition of incoming radiation. Since slightly higher absorption efficiency of high B/R radiation does not fully explain the changes in induction kinetics, the other possible mechanisms contributing to the stimulation of electron transport and Rubisco activity are discussed. and M. Košvancová-Zitová ... [et al.].
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

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