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Properties and production of microbial lipases
Martinková, Patrícia ; Reichstädter, Marek (referee) ; Omelková, Jiřina (advisor)
Bachelor´s thesis is focused on testing the culture media for growing various strains of yeasts, producing lipolytic enzymes and to study the influence of culture media composition on the production of lipolytic enzymes. Theoretical part of this thesis states the characteristics of lipolytic enzymes, their properties, sources, conditions for their production and the possibilities of their application. Together 8 strains of yeasts were used in the experimental part of the thesis, namely 2 strains of Yarrowia lipolytica, 2 strains of Kluyveromyces lactis, Cryptococcus saitoi, Candida intermedia, Candida oleophila and Debaryomyces hansenii, which were cultivated on 4 media with different compounds. During the cultivation the growth of biomass was monitored and growth curves were formed based on these results. Selected strains of yeasts were tested during the process of cultivation for lipolytic activity of two types of enzymes – enzymes bonded to the cellular structure and extracellular enzymes, which were measured by spectrophotometer. Production of lipolytic enzymes varied depending on applied culture medium.
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Extraction of anthocyanin pigments from black chokeberry pomace
Martinková, Patrícia ; Zemanová, Jana (referee) ; Vespalcová, Milena (advisor)
The diploma thesis deals with the preparation of extract and concentrate of anthocyanin dyes from aronia moldings (Aronia melanocarpa). It also determines chemical properties important for human´s health, which are important also for further possible use of extract/concentrate as natural red food coloring. A series of extractions of dried and powdered aronia moldings was carried out in the experimental part of the thesis, aiming for the optimization the conditions of the extraction. Extracts were characterized by content of total anthocyans, content of total fenolic substances and total antioxidant activity. The best laboratory conditions for extraction were determined as follows: amount of moldings 12,5 g, composition of extraction agent ethanol:water 1:1, volume of extraction mixture 60 ml and time of the extraction 11 hours. Prepared extracts were concentrated on vacuum evaporator. It has been found that the temperature of the water bath in the vacuum evaporator can not exceed 40 °C. At higher temperatures there is significant degradation of anthocyanins. Furthemore, the content of individual anthocyanic dyes in extract and concentrate, from aronia moldings, was quantified by HPLC. The major anthocyanin, cyanidine-3-galactoside, was contained in the concentrate at 923,6 ± 8,5 mg·l-1, the other specified anthocyanin, minor cyanidine-3-glucoside, was present at a concentration of 53,5 ± 0,3 mg·l-1.
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Statistical models for detection of differential item functioning
Hladká, Adéla ; Martinková, Patrícia (advisor) ; Wiberg, Marie (referee) ; Hlávka, Zdeněk (referee)
This thesis focuses on topic of Differential Item Functioning (DIF), a phenomenon that can arise in various contexts of educational, psychological, or health-related multi- item measurements. We discuss several statistical methods and models to detect DIF among dichotomous, ordinal, and nominal items. In the first part, generalized logistic regression models for DIF detection among di- chotomous items are introduced, which account for possibility of guessing and/or inat- tention. Techniques for estimation of item parameters are presented, including a newly proposed algorithm based on a parametric link function. Two simulation studies are presented. The first compares the generalized logistic regression models to other widely used DIF detection methods. The second illustrates differences between the techniques to estimate item parameters. Implementation of the models into the R software and its difNLR package is illustrated. In the second part, generalized logistic regression models for DIF detection among polytomous items are discussed. Cumulative logit, adjacent category logit, and nominal models are introduced together with the maximum likelihood method to estimate item parameters and with examples of implementation in the difNLR package. The third part deals with a nonparametric comparison of regression...
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Models for equating in cognitive tests
Vařejková, Michaela ; Martinková, Patrícia (advisor) ; Hlávka, Zdeněk (referee)
This thesis focuses on statistical methods for equating cognitive tests, which is the process of transforming scores from multiple test versions to ensure their comparability. Divided into three chapters, the theoretical part of the thesis addresses different approaches to test equating. The first chapter presents tra- ditional equating methods, the second explores kernel equating methods, while the third covers equating methods using Item Response Theory models. The concluding part of the thesis showcases an empirical study demonstrating the application of equating methods on a real dataset. This dataset contains respon- ses to two versions of a math test taken by fourth-grade students in the Czech Republic as part of the 2015 TIMSS international survey. 1
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An interactive tool to support the evaluation of data from standardized tests
Martinková, Patrícia ; Potužníková, E. ; Netík, Jan
In this work, we present features of an interactive tool module for supporting analyses of data from achievement tests by presenting an example of data from the Matura (graduation) exam in mathematics. We present methods for detection of different functioning of items for different types of school, or for comparison of a selected school with other schools. We show that the tool has a potential to help with informed use of achievement test data and to support decision making on both the school and the system levels.
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Computerized Adaptive Testing In Kinanthropology: Monte Carlo Simulations Using The Physical Self Description Questionnaire
Komarc, Martin ; Štochl, Jan (advisor) ; Martinková, Patrícia (referee) ; Scheier, Lawrence (referee)
This thesis aims to introduce the use of computerized adaptive testing (CAT) - a novel and ever increasingly used method of a test administration - applied to the field of Kinanthropology. By adapting a test to an individual respondent's latent trait level, computerized adaptive testing offers numerous theoretical and methodological improvements that can significantly advance testing procedures. In the first part of the thesis, the theoretical and conceptual basis of CAT, as well as a brief overview of its historical origins and basic general principles are presented. The discussion necessarily includes the description of Item Response Theory (IRT) to some extent, since IRT is almost exclusively used as the mathematical model in today's CAT applications. Practical application of CAT is then evaluated using Monte-Carlo simulations involving adaptive administration of the Physical Self-Description Questionnaire (PSDQ) (Marsh, Richards, Johnson, Roche, & Tremayne, 1994) - an instrument widely used to assess physical self-concept in the field of sport and exercise psychology. The Monte Carlo simulation of the PSDQ adaptive administration utilized a real item pool (N = 70) calibrated with a Graded Response Model (GRM, see Samejima, 1969, 1997). The responses to test items were generated based on item...
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Computerized adaptive testing in knowledge assessment
Tělupil, Dominik ; Martinková, Patrícia (advisor) ; Omelka, Marek (referee)
In this thesis, we describe and analyze computerized adaptive tests (CAT), the class of psychometrics tests in which items are selected based on the actual estimate of respondent's ability. We focus on the tests based on di- chotomic IRT (item response theory) models. We present critera for item selection, methods for ability estimation and termination criteria, as well as methods for exposure rate control and content balancing. In the analytical part, the effect of CAT settings on the average length of the test and on absoulute bias of ability estimates is investigated using linear regression mo- dels. We provide post hoc analysis of real data coming from real admission test with unknown true values of abilities, as well as simulation study based on the simulated answers of respondents with known true values of ability. In the last chapter of the thesis we investigate the possibilities of analysing adaptive tests in R software and of creating a real CAT. 1
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Extraction of anthocyanin pigments from black chokeberry pomace
Martinková, Patrícia ; Zemanová, Jana (referee) ; Vespalcová, Milena (advisor)
The diploma thesis deals with the preparation of extract and concentrate of anthocyanin dyes from aronia moldings (Aronia melanocarpa). It also determines chemical properties important for human´s health, which are important also for further possible use of extract/concentrate as natural red food coloring. A series of extractions of dried and powdered aronia moldings was carried out in the experimental part of the thesis, aiming for the optimization the conditions of the extraction. Extracts were characterized by content of total anthocyans, content of total fenolic substances and total antioxidant activity. The best laboratory conditions for extraction were determined as follows: amount of moldings 12,5 g, composition of extraction agent ethanol:water 1:1, volume of extraction mixture 60 ml and time of the extraction 11 hours. Prepared extracts were concentrated on vacuum evaporator. It has been found that the temperature of the water bath in the vacuum evaporator can not exceed 40 °C. At higher temperatures there is significant degradation of anthocyanins. Furthemore, the content of individual anthocyanic dyes in extract and concentrate, from aronia moldings, was quantified by HPLC. The major anthocyanin, cyanidine-3-galactoside, was contained in the concentrate at 923,6 ± 8,5 mg·l-1, the other specified anthocyanin, minor cyanidine-3-glucoside, was present at a concentration of 53,5 ± 0,3 mg·l-1.
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