Populiariausi pagalbiniai finansinio kintamumo rodikliai yra absoliučios ir kvadratinės grąžos. Šie du rodikliai yra plačiai nagrinėjami įvairiuose kintamumo tyrimuose. Šiame darbe mes juos praplėsime nagrinėdami absoliučias grąžas tam tikrame teigiamame laipsnyje. Pagalbinio kintamumo rodiklio statistinėms savybėms gauti, naudosime įvairius kintamumo modelius: apibendrintą autoregresinį sąlyginio heteroskedastiškumo modelį, stochastinio kintamumo modelį, eksponentinį apibendrintą autoregresinį sąlyginio heteroskedastiškumo modelį bei asimetrinį laipsninį autoregresinį sąlyginio heteroskedastiškumo modelį. Šiuos apibrėžimus mes pritaikysime S&P 500 uždarymo kainų indekso duomenims nuo 1928.01.01 iki 2007.12.31. Siekdami nustatyti geriausią laipsnį, naudosime du metodus: vidutinę kvadratinę paklaidą ir autokoreliacinės funkcijos elgesį. Vidutinės kvadratinės paklaidos pagalba nagrinėsime kintamumo rodiklį kaip kintamumo įvertį ir ieškosime laipsnio, minimizuojančio šią funkciją. Šiame darbe gaunama, kad laipsnis svyruoja apie 2-3. Taip pat ieškosime laipsnio, kuris duos stipriausią papildomo kintamumo rodiklio koreliaciją. Skirtingiems kintamumo apibrėžimams gausime, kad laipsnis, duodantis stipriausią autokoreliaciją svyruoja tarp 1 ir 1,5 skirtingiems kintamumo apibrėžimams. / The most popular proxy variables, used to describe the financial volatility, are squared and absolute returns. These two proxy variables are widely discussed in recent studies. In this paper we proposed the extension of existing studies analysing absolute returns in some positive degree as volatility proxy variable. Some statistical properties of this new proxy variable were investigated using four main discrete volatility models as a basis for our investigation: Generalized ARCH, Stochastic Volatility, Exponential GARCH and Asymmmetric Power ARCH. We applied these definitions to daily data of S&P 500 stock market closing prices ranging from 1928.01.01 till 2007.12.31. In order to estimate the best degree, the modeled volatility was compared with the volatility proxy variable. We used our volatility proxy as volatility estimate to find degree, which minimizes mean squared error. We have shown that the best degree for volatility proxy variable is ranging from 2 to 3. The second method we have used was analysis of the autocorrelation function. We obtained that degree ranges from 1 to 1.5.

The purpose of the study was to evaluate the wood yield and stem quality of (Norway Spruce (Picea abies) provenances from Jurbarkas, Telšiai, Kaunas and Alytus and to assess the transfer effect. to Kaunas region. The problem was the following: incase of shortage of Norway spruce seeds in the local Dubrava forest enterprise, from where it would be profitable to introduce seeds? The object of the study: experimental plantation of Norway spruce in Vaišvydava forest district of Dubrava experimental forest enterprise established in 1995. Trees of four provenances are tested: Jurbarkas, Telšiai, Vaišvydava and Alytus. The total area of experimental plantation is 1.2 hectares. The work methods and technical means: the age of young trees was 11 years at the time of measurements. The following characteristics were measured: height young trees, the number of leader shoots, the straightness of stem, time of budburst (the beginning of the growth period). The height of trees was measured with telescopic measurement instrument; qualitative traits were evaluated according to the class scales used in the genetic research. The results were the following: It was established that the descendants of the provenance of Mociškiai were the tallest and of the best stem quality. The descendants of the provenance of Punia were in the second place by wood yield and quality. This advantage can be explained by good genetic quality of the tested material and the positive effect of transfer. The descendants... [to full text]

Objective of the study is to assess wood yield and quality of Polish Norway spruce provenances and transfer effect in comparison with the local provenances. Object of the study is experimental plantation established in Kazlų Rūda EFE, Agurkiškės forest district (62 comp.., 43 plot). Six southern Polish proveniences were from Istebna, Ustron, Ujstoly ir Lagow forest districts and three open-pollinated families from Girionys seed orchard and progeny from the local Agurkiškės forest district were tested. Area of the experimental plantations 1,8 ha. Methods: quantitative and qualitative traits of the trees in the plantation were assessed by using the following tools and methods: height was measured with a telescopic pole, diameter with calipers and the quantitative traits were assessed by the standard methods used in genetics and breeding. Results: this study showed that growth rate and wood yield of the southern provenances were higher than of the progenies of the selected plus trees of Lithuanian origin. However, wood yield of soother Polish provenances was significantly higher than that of the local regular stands of Agurkiškių provenance. This indicates, that the seed orchard material is superior over the material form regular unimproved forests stands. This difference may be caused not only by the geographical transfer effect but also related to genetic quality of the original stands. Polish provinces possessed a lower number of forked trees but their stems were less... [to full text]

Magistro darbe tiriama brandžių medynų inventorizacijos miškotvarkos metu patikimumas. Darbo objektas – Kazlų Rūdos mokomosios miškų urėdijos valstybinės reikšmės miškų II-IV miškų grupės brandūs medynai. Darbo tikslas – išanalizuoti brandžių medynų inventorizacijos miškotvarkos metu tikslumą ir įvertinti atrankinės miškų inventorizacijos efektyvumą. Darbo metodai – Palyginamoji analizė, atrankos metodas. Darbo rezultatai - Brandžių medynų visuma inventorizuota atrankos metodu. Pagrindinis šio metodo pranašumas – jo objektyvumas, leidžiantis patikimai su žinoma atrankos paklaida įvertinti inventorizuotų medynų vidutinius rodiklius, pirmoje eilėje vidutinį tūrį. Tokiu būdu nustatytas brandžių medynų tūris yra 12 % didesnis už sklypinės inventorizacijos metu nustatytą tūrį, panaudojant taip pat atrankos metodą kiekviename sklype. Brandžių medynų visumos atrankinės inventorizacijos metu nustatytas medžių tūrio kintamumas, leisiantis geriau planuoti tokias inventorizacijas. Didžiausiu vidutinio medžių tūrio kintamumu Kazlų Rūdos miškų urėdijoje pasižymi brandūs pušynai (variacijos koeficientas – 48%). Beržynų ir eglynų tūrio variacijos koeficientas 40-41%, juodalksnynų - 37%. / The work object is Kazlų Rūda forest enterprises, II-IV group mature stands. The main goal of the work was to estimate the reliability of inventory mature stands during standwise inventory. Methods. Comparative analysis and sampling methods were used. The main results Mature stands were inventoried by sampling method. The main advantage of this method - its objectivity, which allow to estimate growing stock volume of mature stands with known error. Estimated mature stands volume of growing stock is 12 % higher than volume inventoried using angle count inventory method for each individual compartment. Estimated variation of growing stock of volume mature stands will allow to calculate other inventories. The highest variation of growing stock volume of mature stands Kazlų Rūda forest enterprise is in pine stands– 48 % medium, in birch and spruce stands 40-41 %, and the least in black alder stands– 37 %.

Magistro darbe tiriama tolimųjų paprastosios pušies populiacijų spyglių žiotelių skaičiaus geografinio kintamumo dėsningumai. Darbo objektas – Prokazin serijos paprastosios pušies tolimųjų kilmių bandomieji želdiniai Kazlų Rūdos MMU. Darbo metodai – ištirtos 34 populiacijos, kilusios iš rytinės pušies arealo dalies. Kiekvienoje populiacijoje atsitiktinai atrinkta po 5 medžius – iš viso 170 medžių. Medžiai įvertinti pagal pasirinktus rodiklius (skersmuo, šakų kampas, šakų skaičius menturyje ir žievės forma). Nuo kiekvieno medžio paimti ūgliai analizei, po 6 spyglius nuo kiekvieno medžio (viso 1020 spygliai). Spygliai buvo analizuoti mikroskopu pagal parinktus tokius morfologinius rodiklius: spyglio ilgis, žiotelių skaičius lygioje spyglio pusėje, žiotelių eilių skaičius lygioje spyglio pusėje. Darbo rezultatai. Atlikus tyrimus Prokazin serijos paprastosios pušies tolimųjų kilmių bandomuosiuose želdiniuose ir apdorojus duomenis statistinėmis programomis gauti tokie rezultatai: žiotelių vidutinis skaičius 2 mm spyglio segmente yra 195 žiotelės; žiotelių skaičius ir spyglių ilgis priklauso nuo medžių kilmės: populiacijos kilusios iš Europos šiaurės rytų pasižymi trumpesniais spygliais ir mažesniu žiotelių skaičiumi nei kilusios iš pietų; medžių skersmuo nėra susijęs su žiotelių skaičiumi spyglio ploto vienete, tačiau yra susijęs su spyglio ilgiu ir bendru žiotelių skaičiumi spyglyje. / This Master's thesis investigated the geographical diversity patterns of Scots pine populiations on the number of needle stomata. Object of the work – Scots pine provenance trials known as the Prokazin series in Kazlu Ruda training forest enterprise. Method of the work – 34 populations of Scots pine which represent the eastern range of the species distribution, were tested. Each population represented by 5 trees, for a total of 170 trees. The trees were evaluated with regard to the following traits: diameter, branch angle, number of whorls of branches, bark in the form. Shoots were cut from the each tree and subsequently 6 needles (for a total of 1020 needles) were taken from each tree for analysis. Each needle was analyzed under a binocular microscope separately in regard to the following seven morphological traits: needle length, number of stomatal rows on the flat side of a needle, number of stomata per 2 mm of needle length on the flat side. The results of the work. The results of this study showed that the average number of stomata is 195 per 2 millimeters segment; the number of stomata and needle length in Scots pine depends on the tree of origin: the Northeast European populations have shorter needles and fewer stomata than populations from the south; tree diameter is not associated with the number of stomata per unit area, however is related to the needle length and the total number of stomata.

This doctoral dissertation has been accomplished during the period of 1995-2006 in the Department of Forestry at the Lithuanian University of Agriculture. In Lithuanian forests only one species of genus - small-leaved lime (Tilia cordata Mill.) – is natural. Study aim was to determine the distribution of lime stands in Lithuania, estimate their productivity and phenotypic variation. For the first time distribution of lime stands in different natural forest regions of Lithuania has been analysed. For the first time studies of the phenotypical diversity were conducted, phenotypical diversity in natural stands has been analysed. Phenological forms of small-leaved lime were singled out, their development differences were justified. Yield models for all lime stand sites and site productivity scale for lime stands were designed.For the first time data on the diversity of phenotypical traits and on the influence of environmental factors on phenotypical indices of lime trees were analysed in Lithuanian stands of natural origin. The data may be applied to estimate the possibilities of lime growth in different conditions, forecasting stand productivity. The data on phenotypic diversity may be important to preserve genetic diversity of naturally growing lime stands. For the first time the distribution of lime stands, their species composition in natural forest regions of Lithuania and in different sites were analysed. Yield models of modal stands and site productivity scales for lime... [to full text]

Darbe siekiama aprašyti periodinį ilgos atminties finansinių laiko eilučių elgesį. Remiantis anksčiau sukurtais modeliais, siūlomas h-faktorių Gegenbauer-LARCH modelis, kuris į LARCH tipo proceso sąlyginės dispersijos lygtį įtraukia apibendrintą ilgos atminties filtrą, paremtą Gegenbauer polinomais. Darbe pateikiama anksčiau sukurtų modelių, skirtų finansinių aktyvų grąžų kintamumo modeliavimui, apžvalga. Remiantis ankstesnėmis idėjomis ir darbais, sukonstruojamas naujas Gegenbauer-LARCH modelis, kuriam tikrinama kovariacijos stacionarumo sąlyga. Pateikiamos modeliuotos h-faktorių Gegenbauer-LARCH proceso trajektorijos. Sukurtas modelis taikomas realiems Euro-Dolerio valiutų kurso duomenims. Identifikuotas modelio parametrai vertinami LUDE algoritmu, kuris maksimizuoja didžiausio tikėtinumo funkciją. Atliekama modelio adekvatumo analizė. Darbo pabaigoje pateikiamos išvados ir rekomendacijos. / On the ground of previous works and ideas a new class of models which describe long memory periodic behaviour in a time varying volatility of financial returns is introduced. Generalised periodic long-memory filters, based on Gegenbauer polynomials, are included into volatility equation of LARCH model and capture long memory periodic behaviour of the data. Thus, a new type of model called h-factor Gegenbauer-LARCH is presented. Moreover, a covariance stationarity condition is checked for one factor Gegenbauer-LARCH model. Also, generated processes are demonstrated. Furthermore, h-factor Gegenbauer-LARCH model is applied to Euro-Dollar hourly exchange rate returns. Identified model is estimated by means of LUDE algorithm which maximizes maximum likelihood function. The adequasy of the model is checked by reviewing residuals behaviour. Concerning empirical results the following conclusion is drawn: • Although model captures specific characteristics of the data such as slowly decaying periodic behaviour of autocorrelation function and pronounced peaks in periodogram but residuals analysis shows that model should be improved. Bordignon, Caporin, Lisi suggest that all possible frequencies were included to the model because higher frequencies might not be obvious from autocorrelation function or periodogram. However, we face computer capability problem. As a matter of fact, we cannot estimate a more complex model. Inclusion of autoregresive coefficients into the model did not... [to full text]