Arsenic release and its kinetic in severely contaminated stream sediments of the Kyjov brook and impoundment material (eastern Slovakia) using column and batch experiments was studied. The results of the column experiments showed that As release from the solid samples by water was likely controlled by Fe and Mn oxyhydroxides and pH of the sediments and leachates. It was also observed that extraction time was an important factor influencing the As release. The empirical correlations between the rate constants of As release and oxalate-extractable Fe content or total Mn content imply that diffusion in hydrated micropores of amorphous Fe and Mn oxides might be the rate-limiting mechanism of the As release. Although the fractions of As released in column experiments were generally less than 10 % of its total contents, these low fractions represented high absolute amounts of readily available and water-soluble As with a mean value of 83 mg kg-1. This amount of readily available As is approximately 4-times higher than the guideline value for As according to DEFRA UK, based upon ''bioavailable'' concentration, indicating high As availability for plants and living organisms in the studied region. and V štúdii bolo sledované uvoľňovanie arzénu a jeho rýchlosť vo výrazne kontaminovaných riečnych sedimentoch toku Kyjov na východnom Slovensku a materiáli odkaliska použitím kolónových a nádobkových experimentov. Výsledky kolónových experimentov naznačujú, že pravdepodobne najväčší vplyv na uvoľňovanie As vodou majú oxyhydroxidy Fe a Mn a pH výluhov a použitých sedimetov. Ukázalo sa, že aj čas trvania kontaktu kontaminovaných vzoriek s roztokom je dôležitý faktor uvoľňovania As. Nájdené korelácie medzi rýchlostnými konštantami uvoľňovania As a extrahovateľnými obsahmi Fe šťavelanom amónnym ako aj celkovými obsahmi Mn by mohli poukazovať na fakt, že difúzia v hydratovaných mikropóroch amorfných oxyhydroxidov Fe a Mn je hlavný mechanizmus limitujúci rýchlosť uvoľňovania As. Hoci frakcie uvoľneného As v kolónových experimentoch boli celkovo nižšie ako 10 % z jeho totálnych obsahov v skúmaných vzorkách, tieto nízke frakcie predstavujú vysoké obsahy ľahko dostupného a vo vode rozpustného As s priemernou hodnotou 83 mg kg-1. Uvedený obsah ľahko dostupného As je približne 4-krát vyšší ako smernicová hodnota podľa DEFRA UK založená na ''biodostupnej'' koncentrácii As. Toto porovnanie poukazuje na potenciálne vysokú dostupnosť As pre rastliny a živé organizmy v študovanej oblasti
Artefacts in applications of the global gravity field and topographic models based on satellite and terrestrial data of diverse kinds are studied. Various types of artefacts are presented and analysed with the aim to understand how the artefacts originated, how to reduce them (if feasible) and to avoid misinterpretations in geoscience. We work with the gravity aspects (gravity anomalies, the Marussi tensor of the second derivatives of disturbing potential, gravity invariants and their specific ratio, strike angles, and virtual deformations), and with surface or bedrock topography. Examples for the Earth, the Moon, and Mars are presented., Jaroslav Klokočník, Jan Kostelecký, Aleš Bezděk and Gunther Kleteschka., and Obsahuje bibliografii
The paper comments and elaborates upon five pages of P. F. Strawson’s Individuals (1959, 230 - 234), together with his ‘Entity and Identity’ and ''Universals''. The focus is on Strawson’s understanding of individual non-particulars as types or universals, and on his contention that the most obvious non-particular entities (''well-entrenched non-particulars'') are the broadly conceived artefacts including the works of art. The narrow focus is on the implications of Strawson’s suggestion that ‘an appropriate model for non-particulars of these kinds is that of a model particular - a kind of prototype, or ideal example, itself particular, which serves as a rule or standard for the production of others’ (1959, 233). The paper analyzes the relation between Strawson’s position and the issue of artefacts and their (largely missing) ontology. It also asks about some less obvious affinities between the problem of the non-particulars (and their entrenchment) and Strawson’s concept of a person., Příspěvek komentuje a zpracovává na pěti stranách PF Strawson's Individuals (1959, 230 - 234) spolu s jeho ,,Entity and Identity'' a ,,Universals''. Důraz je kladen na Strawsonovo chápání jednotlivých ne-specifik jako typů nebo univerzálů, a na jeho tvrzení, že nejzřejmějšími nespecifickými entitami (,,dobře zakořeněné nešpecifické'') jsou široce pojaté artefakty včetně uměleckých děl. Úzké zaměření je na důsledky Strawsonova návrhu, že ,,vhodným modelem pro ne-detaily těchto druhů je model konkrétního modelu - určitý typ prototypu, nebo ideální příklad, který je sám o sobě, který slouží jako pravidlo nebo standard pro produkce druhých ''(1959, 233). Článek analyzuje vztah mezi postavením Strawsona a problematikou artefaktů a jejich (převážně chybějící) ontologií., and Karel Thein
A quantitative analysis and adequate theoretical and practical steps employing a near-field scanning optical microscope (NSOM) are currently quickly developing areas of near-field optics. The basic task of the analysis consists in the correct description of tip - surface system geometry together with an electromagnetic field propagation through the system. This article deals with the results characterising tips applied in a scanning electron microscope technique and modelling field in the scanning optical microscope. Results are compared with practical measurements obtained with simple structures.
The aim of study was to review the status of arterial pH, pO2 and pCO2 under general anesthesias in dependence on the light-dark (LD) cycle in spontaneously breathing rats. The experiments were performed using three- to four-month-old pentobarbital(P)-, ketamine/xylazine(K/X)- and zoletil(Z)-anesthetized female Wistar rats after a four-week adaptation to an LD cycle (12 h light:12 h dark). The animals were divided into three experimental groups according to the anesthetic agent used: P (light n=11; dark n=8); K/X (light n=13; dark n=11); and Z (light n=18; dark n=26). pH and blood gases from arterial blood were analyzed. In P anesthesia, LD differences in pH, pO2, and pCO2 were eliminated. In K/X anesthesia, parameters showed significant LD differences. In Z anesthesia, LD differences were detected for pH and pO2 only. Acidosis, hypoxia, and hypercapnia have been reported for all types of anesthesia during the light period. In the dark period, except for P anesthesia, the environment was more stable and values fluctuated within normal ranges. From a chronobiological perspective, P anesthesia was not the most appropriate type of anesthesia in these rat experiments. It eliminated LD differences, and also produced a more acidic environment and more pronounced hypercapnia than K/X and Z anesthesias., P. Svorc, D. Petrášová, P. Svorc Jr., and Obsahuje bibliografii
Impaired cerebrovascular reactivity (CVR), an important risk factor for future stroke, is affected by a presence carotid stenosis. However, in some cases CVR can be impaired in the absence of carotid stenosis due to several poorly characterized mechanisms. We hypothesized that arterial stiffening as observed in coronary heart disease (CHD) could be associated with alteration in CVR in CHD patients without carotid stenosis. The study population consisted of patients referred for coronary angiography without significant carotid stenosis (<50 %). CVR was evaluated by breath holding index (BHI) measured with transcranial color code duplex ultrasound. Arterial stiffness was assessed by pulse wave velocity (PWV) measured by the oscillometric method. The extent of coronary atherosclerosis was quantified by Gensini score (GS). Out of 186 subjects, sixty-two patients fulfilled the inclusion and exclusion criteria. BHI decreased with increasing PWV (r = -0.47, p<0.001). Decrease in BHI was significantly inversely associated with GS (r = -0.61, p<0.001). GS was associated with PWV (p<0.001). In conclusion, impaired CVR was associated with increased arterial stiffening in CHD patients in the absence of significant carotid stenosis. Thus, we speculate that increased arterial stiffness may at least partially contribute to the pathophysiology of CVR alteration in coronary artery disease., D. Rucka, J. Marek, Z. Rucklova, J.-C. Lubanda, S. Havranek, J. Skvaril, P. Varejka, M. Chochola, D. Karetova, J. Korinek, A. Linhart., and Obsahuje bibliografii