Xylogenesis and phloemogenesis of Norway spruce in different ages stands at middle altitudinal zone

This study aimed to determine the influence of the stand age and selected weather conditions on the cambial activity, xylem and phloem formation and their development. For the analysis, microcores were taken weekly from two corresponding stands of Norway spruce (Picea abies (L.) Karst.) with various ages (35- and 106-years-old) during the growing season 2012 in the Czech Republic. Young specimens were characterised by higher cambium activity; however, more considerable variation and imbalance were found there. In old trees, delayed processes during the development of the xylem and phloem at the cell level were proved. The cambium activity started in March till mid-April, and it lasted for 22 weeks in both cases. The commencement of xylogenesis was established in the first half of May. In both investigated stands, the fully lignified ring was observed at the end of October. For the creation of most xylem cells, it was required 124 and 121 days in the young and old stands, respectively. Daily increment of 0.57 (young) and 0.49 (old) cells on average was observed during the active xylem growth. The relationship between air temperature and wood cell formation for both age groups was recorded. The precipitation influenced wood development just in the case of the young trees. Phloem formation was resistant to external influence according to the Pearson correlation coefficient.O

Risk analysis in investment appraisal based on the Monte Carlo simulation technique

This work has been prepared for the purpose of presenting the methodology and uses of the Monte Carlo simulation technique as applied in the evaluation of investment projects to analyze and assess risk. In the deterministic appraisal the basic decision rule for a project is simply to accept or reject the project depending on whether its net present value (NPV) is positive or negative, respectively. Similarly, when choosing among alternative (mutually exclusive) projects, the decision rule is to select the one with the highest NPV, provided that it is positive. Recognizing the fact that the key project variables (as: volume of sales, sales price, costs) are not certain, an appraisal report is usually supplemented to include sensitivity and scenario analysis tests. Both tests are static and rather arbitrary in their nature. During the simulation process, random scenarios are built up using input values for the project's key uncertain variables, which are selected from appropriate probability distributions. The results are collected and analyzed statistically so as to arrive at a probability distribution of the potential outcomes of the project and to estimate various measures of project risk

Information system extension and integration with social networks

katedra softwarového inženýrstv

Cooperation between elementary schools and Police of Czech Republic in Police headquarters of Prague III

Katedra pedagogikyPedagogická fakultaFaculty of Educatio

Bayesowska estymacja punktu zmiany w modelu regresji dwufazowej

The purpose of this paper is to carry out the Bayesian analysis of a two-phase regression model with an unknown break point. Essentially, there are two problems associated with a changing linear model. Firstly, one will want to be able to detect a break point, and secondly, assuming that a change has occurred, to be able to estimate it as well as other parameters of the model. Much of the classical testing procedure for the parameter constancy (as the Chow test, CUSUM, CUSUMSQ, tests and their modifications, predictions tests for structural stability) indicate only that the regression coefficients shifted, without specifying a break point. In this study we adopt the Bayesian methodology of investigating structural changes in regression models. The break point is identified as the largest posterior mass density, the peak of the posterior discrete distribution of a break point. It seems to work well with artificially generated data. The Bayesian framework also seems to be promising for extending the analysis of a single break to that of multiple breaks.Zadanie pt. „Digitalizacja i udostępnienie w Cyfrowym Repozytorium Uniwersytetu Łódzkiego kolekcji czasopism naukowych wydawanych przez Uniwersytet Łódzki” nr 885/P-DUN/2014 dofinansowane zostało ze środków MNiSW w ramach działalności upowszechniającej naukę

Skośny rozkład normalny - podstawowe własności i obszary zastosowań

The skew-normal is a class of distribution that includes the normal distribution as a special case. A systematic treatment of the skew-normal distribution has been given in Azzalini (1985, 1986); generalizations to the multivariate case are given in Azzalini and Capitanio (1999), while Azzalini and Capitanio (2003) propose a further extension with a skew-t distribution. In this paper we study the properties of this class of density functions and we investigate the applicability of this distributions for modeling some financial and income data.Klasa skośnych rozkładów normalnych zawiera jako szczególny przypadek rozkład normalny. Szczegółowemu omówieniu własności rozkładu skośnego normalnego poświęcona jest praca Azzalini (1985, 1986); przypadek wielowymiarowy przedstawili Azzalini i Capitanio (1999), natomiast w pracy tych autorów z roku 2003 można znaleźć dalsze rozszerzenie tej klasy rozkładów o rozkłady skośne t-Studenta. W niniejszym artykule przedstawiono podstawowe własności funkcji gęstości omawianych rozkładów i pokazano możliwości ich wykorzystania w modelowaniu dochodów i danych finansowych