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Study of laser mixture in the large pressure region
Morávek, Matěj Jan ; Hrachová, Věra (advisor) ; Kudrna, Pavel (referee)
This work studies discharge plasma in a mixture of gases, similar to that used in the so-called CO2-lasers. This mixture consists of CO2, N2 and He. The effect of the mixture composition and discharge parameters (especially pressure, in the range of 266 Pa - 100 kPa) on the distribution of energy in the vibrational levels of nitrogen was examined. This is important parameter for modelling of the discharge plasma. The effect of the mixture composition on the degree of dissociation of the CO2 molecules was also studied. The relative concentration of CO was applied to find the conditions leading to a minimal dissociation of the carbon dioxide. Measurements of radial profiles were also made. Results from two discharge tubes made from different materials were compared. Two types of discharge were utilized to acquire a wide pressure range - low pressure DC glow discharge in the range of 266 Pa to 1330 Pa and dielectric barrier discharge in the range of 5 kPa to 100 kPa. Both discharges are used in commercial CO2-lasers. We observed a descending dependence of the vibrational temperature on the pressure and a big step caused by increased occurrence of standing ionizing waves in the mixtures with low nitrogen ratio. Vibrational temperature in the DBD was markedly lower than in the DC GD, because of the...
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Characterization of active layers with pH dye for fluorescent pH fiber optic sensors
Škrabal, Pavel ; Kuncová, Gabriela (referee) ; Pospíšilová, Marie (advisor)
Diploma thesis is deal with the problem of plant intracellular pH measurement in range of pH5-pH7. Convenient method of pH measurement is in this case local optical microdetection using so call pH transducers immobilized into matrices. Ratio-metric method of measurement of emission of excited transducer on two wavelengths is used. Tree excitation wavelengths were chosen from measured absorption spectra of pH transducers which were solved in calibration buffers (liquid samples). Time independence calibration curves (dependence of ratio-coefficient on pH) of liquid samples were established from their emission spectra for transducers BCECF, HPTS and HPCE. The requirements of sensitivity in pH range satisfied BCECF and HPTS transducers. These transducers were immobilized into xero-gel layers (TEOS, APEX and PTES) and by dip-coating method coated on the glass slide (solid samples). The diference of pH values of control medium, which were read from the calibration curves of solid samples (BCECF + TEOS and HPTS + PTES) and from pH measured potentiometrically, were 0.73. The first test measurement of pH was made by the V-taper with deposited active layer (transducer BCECF immobilized in TEOS) on its tip.
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Dolní odhad pro omezené pravděpodobnostní online algoritmy pro rozvrhování
Tichý, Tomáš
This paper studies a restricted class of randomized on-line non-preemptive algorithms for scheduling in multiprocessor systems. In this class each task is specified by its processing time and scheduled to a processor with the smallest or $h$th biggest load for a fixed $h$. The competitive ratio is the maximum of the ratios of the expected makespan and the optimal makespan over all.
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Productivity of differently managed mountain meadows
Mašková, Z. ; Květ, Jan ; Zelený, D.
A mountain meadow (about 1160 asl) situated in the Šumava NP/BR was subjected to 3 treatments applied in mid-July in 4 succesive years: (i)mowing, (ii)mulching, (iii)no management. Seasonal courses of aboveground biomass varied between 0,35-0,5 kg.m-2 in all treatments and years while belowground biomass did between 6-9 kg.m-2. R/S ratio varied between 6-18, being mostly highest in the mown treatment. Litter dry weight varied mostly between 0,2-0,8 kg.m-2, being usually hightest in the unmanaged treatment. Seasonal courses of the above 3 production characteristics were highly variable. Estimated average annual aboveground net production was 0,6-0,7 kg.m-2 for all treatments and years.
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Analysis of Ginger root extract. II.
Zárubová, Kateřina ; Jahodář, Luděk (advisor) ; Macáková, Kateřina (referee)
Zárubová, K.: Analysis of Ginger root extract. II. [Thesis] Hradec Králové 2010, Charles University in Prague, Faculty of Pharmacy. The main goal of this work was verification of the declared quality of commercially available dry ginger extract. Having a standard sample is a necessary requirement for its testing in planned preclinical trials. Ethanol extract of the plant Zingiber officinale Rosc. was analyzed. For qualitative evaluation was used TLC method. Elution system was a mixture of ether and n-hexane in the ratio 6 : 4, an adsorbent was silicagel, detection was performed by spraying with solution of 1% vanillin in perchloric acid and sulfuric acid 6N. 6-gingerol was used as a standard. It was confirmed that the analyzed sample contains gingerols. Liquid chromatography for the quantitative evaluation of the extract was performed. The mobile phase was a mixture of acetonitrile and water (acidified with 1 ml of phosphoric acid in 1000 ml of water) and methanol in the ratio 55:44:1, column was Merck Purospher RP-18 endcapped, 5 µm, 250×4 mm. Flow rate of mobile phase was 1.0 ml/min, inject volume 20 ml, UV / VIS detection at 282 nm. As a standard was used 6-gingerol in a concentration of 1 mg / 1 ml.There was determined 5,47 % of gingerols.
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Prediction of Stock Returns using Financial Statement
Hájková, Petra ; Hollmannová, Monika (referee) ; Jakubík, Petr (advisor)
This thesis should contribute to research in the area of fundamental analysis. Its aim is to study whether financial statement data of Czech non-financial companies capture information that is not reflected in prices. Therefore, the question is whether investment strategy based on financial statement analysis could earn excess returns. In order to test this hypothesis, a three-step estimation procedure based on a logit model is used to identify financial ratios relevant for prediction of future earnings. The final estimated model includes four financial ratios and is then used to set a one-year investment strategy. Although the performance of the estimated model is not too sound, this investment strategy brings positive abnormal returns during the monitored period of time. Despite the fact that results were influenced by several factors, they could indicate that financial statement analysis of companies listed on the Prague Stock Exchange is able to predict stock returns.
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A study of the properties of tablets from the mixture of directly compressible xylitol and microcrystalline cellulose.
Komínková, Hana ; Mužíková, Jitka (advisor) ; Šnejdrová, Eva (referee)
Název v anglictine: A study of the properties of tablets from the mixture of directly compressible xylitol and microcrystalline cellulose. Summary: The thesis deals with the study of properties of tablets from a mixture of directly compressible xylitol, namely Xylitab® 300, and microcrystalline cellulose, namely Microcel® MC-12, in the ratio of 1:1. (This ratio was arrived at after preceding experiments concerning the strength of tablets made only from Xylitab® 300, and from a mixture of Xylitab® 300 and Microcel® MC-12 in the ratio of 3:1. The strength was insufficient in these cases.) The focus of the study was the dependence of the tensile strength and disintegration time of the tablets on the compression force, the addition of lubricants, namely magnesium stearate and sodium stearyl fumarate (Pruv®), with concentrations of 0.5% and 1%, and a 50% addition of model active ingredients, namely acetylsalicylic acid and ascorbic acid. The compression forces used were 10, 12.5, and 15 kN; tablets containing the drugs were only compressed with a force of 15 kN. Tablets with a weight of 0.5 g and a diameter of 13 mm were compressed using material testing machine T1-FRO 50 TH.A1K Zwick/Roell and they were further subjected to a strength test using Schleuniger Tablet Tester 8M and to a disintegration time test...
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Evolution of host specifity in cuckoo bees of the genus Sphecodes (Hymenoptera)
Habermannová, Jana ; Straka, Jakub (advisor) ; Kratochvíl, Lukáš (referee)
Cuckoo bees behave similarly to the well-known birds, cuckoos - they lay eggs in the nests of other bees. Proposed thesis charts the evolution of host specialization within the strictly cuckoo genus Sphecodes. According to the classical view based on the Red Queen hypothesis, parasites should gradually specialize during evolution to keep pace in the "arms race" with their hosts. Specialization is also perceived as an evolutionary dead end - narrow adaptation prevents change of host. To test these hypotheses phylogeny of tribus Sphecodini based on the partial sequences of five genes was constructed. For each ancestor has been by two methods of mapping ancestral characters (Bayesian method, Maximum Parsimony) specified, whether it was specialist or generalist and which kind of host or hosts it had. The results show that the original strategy of genus Sphecodes is specialization and generalists originated from specialized ancestors only recently. The results also show that the jumps between the hosts are common. These findings are inconsistent with the Red Queen hypothesis as well as with the view that specialization is an evolutionary dead end. Falsity of these hypotheses within the genus Sphecodes established also likelihood ratio test, in which the likelihood of model allowing two-way transition...
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Emise skleníkových plynů ve vztahu k mikrobiální aktivitě a obsahu živin arktických půd
HAJŠMANOVÁ, Klára
The aim of this study was to understand the link beween greenhouse gasses emissions (CH4 and N2O) microbial activity and nutrient content in soil from different types of soil in Svalbard. Warming can cause release of large amounts of carbon and nitrogen in form of greenhouse gasses from soil into the atmosphere. This might strengthen the greenhouse effect and thus global climate change. We measured release of greenhouse gases from soil. At the same time, soil sampling was conducted at five different localities in August in the years 2014 and 2015. Soils were found to have low nutrient content and unfavourable C/N ratio to support vegetation growth. Areas were not a significant source of emissions of greenhouse gasses from soil to the atmosphere.
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