Phosphorus is the main limiting nutrient for plant growth in large areas of the world and the availability of phosphorus to plants and microbes can be strongly affected by soil properties. Even though the phosphorus cycle has been studied extensively, much remains unknown about the key processes governing phosphorus availability in different environments. In this thesis the complex dynamics of soil phosphorus and its availability were studied by relating various phosphorus fractions and soil characteristics to microbial respiration kinetics. The soils used represent a range of aluminium, iron, carbon and total phosphorus content, and were located in four different biomes: subtropical forest, warm temperate forest, boreal forest and tundra. The results showed that NaOH extractable phosphorus, a fraction previously considered to be available to plants only over long time scales, can be accessed by microbes in days or weeks. Microbial phosphorus availability was not related to aluminium or iron content in any of the studied systems, not even in highly weathered soils with high aluminium and iron content. This is in contrast with other studies of soils with high sorption capacity and shows the variability of factors that govern phosphorus availability in different environments. In the boreal forest chronosequence, no difference could be seen with age in total phosphorus content or concentrations of occluded phosphorus forms. However, there were lower concentrations of labile phosphorus forms in older systems, which were correlated with a decrease in microbial respiration. This was most likely related to organic matter quality in the system, and not to geochemical factors. Phosphorus availability was linked to differences in topography (water regime) and vegetation in the tundra ecosystems. The results suggest that the availability of phosphorus, both for microbes and plants, was lower on the meadow vegetation sites compared to the two types of heath vegetation. Many factors are important for phosphorus availability in soils, but these results suggest that microbes can access less available phosphorus if not restricted by carbon, and this may be important in regard to forest management practices as well as effects of environmental change.

Fatigue crack growth behavior of AA7050 T7451 aluminum alloy under mode II loading condition in two orientations was investigated. Compact shear specimens were prepared in TL and LT directions. A loading frame for mode II type of loading was manufactured. Using the loading frame and the specimen, KIIC values and mode II fatigue crack growth rates were calculated. Fractographic analysis of the fracture surfaces of both mode II fracture toughness test specimens and mode II fatigue crack growth test specimens were done to examine the effects of mode II load. KIIC values were measured between 1.3 and 1.5 times the KIC values for this alloy. As for mode II fatigue crack growth rates, TL orientation shows the highest mode II fatigue crack growth resistance.

本研究採用總資產成長率作為交易策略，而其較資本支出更能完整呈現公司經營活動的特性，近來更受到學者的重視。此外，我們更引進信用風險的概念，利用台灣經濟新報資料庫(TEJ)所發布的TCRI，作為我們分類樣本的依據，在不同信評指標與資產規模分類下，對單一群組，買進總資產成長率較低的投資組合，並同時賣出總資產成長率較高的投資組合。 本研究實證後發現，從2000年到2009年不同信用風險與資產規模的分類群組，可藉由此交易策略得到顯著的異常報酬。主要的原因可推論為「過度投資」與「投資不足」的情形，而特定信用風險的分類，對於公司取得資金的難易也會有所影響，當資金取得容易且管理階層存在代理問題時，異常報酬就會顯著，譬如說低度風險中型公司，其容易取得資金進行過度投資，與公司未來的股價報酬呈現負向關係；又譬如說低度風險大型公司，資產規模龐大，可以視為各產業前幾大公司，雖然資金取得容易，但完善的內控制度使該分類下的交易策略，無法得到顯著的異常報酬。我們可以推論利用資產規模與信用風險進行分類，在某些特定群組下，總資產成長率的交易策略可以得到顯著的異常報酬。 / The research use credit rating index and asset size to classify our sample and set up variety of investment portfolios. In each portfolio, we use asset growth rate to be our investment strategy. Asset growth rate could be known as a good indicator to measure the company growth in the future. By means of forming hedged portfolio, we want to exam the anomalies in credit rating category combined with asset size. We find statistical significance exist in different investment portfolios.

An experimental study of the effect of initial conditions on the development of Rayleigh Taylor Instabilities (RTI) at low Atwood numbers (order of 10-4) was performed in the water channel facility at TAMU. Initial conditions of the flow were generated using a controllable, highly reliable Servo motor. The uniqueness of the study is the system’s capability of generating the required initial conditions precisely as compared to the previous endeavors. Backlit photography was used for imaging and ensemble averaging of the images was performed to study mixing width characteristics in different regimes of evolution of Rayleigh-Taylor Instability (RTI). High-speed imaging of the flows was performed to provide insights into the growth of bubble and spikes in the linear and non-linear regime of instability development. RTI are observed in astrophysics, geophysics and in many instances in nature. The vital role of RTI in the feasibility and efficiency of the Inertial Confinement Fusion (ICF) experiment warrants a comprehensive study of the effect of mixing characteristics of RTI and its dependence on defining parameters. With this broader objective in perspective, the objectives of this present investigation were mainly threefold: First was the validation of the novel setup of the Water channel system. Towards this objective, validation of Servo motor, splitter plate thickness effects, density and temperature measurements and single-mode experiments were performed. The second objective was to study the mixing and growth characteristics of binary and multi-mode initial perturbations seeking an explanation of behavior of the resultant flow structures by performing the first ever set of such highly controlled experiments. The first-ever set of experiments with highly controlled multi-mode initial conditions was performed. The final objective of this study was to measure and compare the bubble and spike velocities with single-mode initial conditions with existing analytical models. The data derived from these experiments would qualitatively and quantitatively enhance the understanding of dependence of mixing width on parametric initial conditions. The knowledge would contribute towards a generalized theory for RTI mixing with specified dependence on various parameters, which has a wide range of applications. The system setup was validated to provide a reliable platform for the novel multi-modal experiments to be performed in the future. It was observed that the ensemble averaged mixing width of the binary system does not vary significantly with the phase-difference between the modes of a binary mode initial condition experiment, whereas it varies with the amplitudes of the component modes. In the exponential and non-linear regimes of evolution, growth rates of multi-mode perturbations were found to be higher than the component modes, whereas saturation growth rates correspond to the dominant wavelength. Quadratic saturation growth rate constants, alpha were found to be about 0.07 ± 0.01 for binary and multi modes whereas single-mode data measured alpha about 0.06 ± 0.01. High-speed imaging was performed to measure bubble and spike amplitudes to obtain velocities and growth rates. It was concluded that higher temporal and spatial resolution was required for accurate measurement. The knowledge gained from the above study will facilitate a better understanding of the physics underlying Rayleigh-Taylor instability. The results of this study will also help validating numerical models for simulation of this instability, thereby providing predictive capability for more complex configurations.

The effect of different aging treatments on fatigue crack growth behavior of AA6013 aluminum alloy was investigated. C(T) (Compact Tension) specimens were prepared in L-T and T-L direction for fatigue crack growth tests. Samples were in T651 as received, T42 which is solution heat treated at 538 &ordm / C for 90 minutes, water quenched and aged in room temperature for 96 hours, and one group of samples were overaged at 245 &ordm / C for 12 hours after T42 condition was achieved. Hardness and conductivity measurements were achieved for all conditions after the heat treatments. Fatigue crack growth tests were performed at as received condition T651, T42 and 245 &ordm / C aged samples in laboratory air with sinusoidal loading of stress ratio R=0.1 and at a frequency of 1 Hz. The highest fatigue crack growth resistance is observed for T651 T-L and 245 &ordm / C overaged L-T condition.

This thesis analyzes the connection between monetary policies and belief-driven fluctuation, and discusses the effects of monetary policies in a small open economy. We construct an endogenous growth model that introduces the role of money into the production function and allows elastic labor supply. In departing from the findings proposed by Benhabib and Farmer (1994), we find that belief-driven fluctuation can be easily encouraged, as long as there is lower increasing return to scale under money growth rate targeting. However, if there is a higher level of increasing return to scale, the increase of the growth rate of nominal money supply will only increase the economic growth rate temporarily, and money is super-neutral in the long run. More importantly, we show that under inflation rate targeting, the central bank will eliminate possibilities of belief-driven fluctuation in the small open economy, but lose the efficacy of monetary policy on the short-term economic growth at the same time.

Recent research has suggested that individual specialization within populations could be substantial and more common than previously acknowledged. Eurasian perch is one of many species of fish in lakes of postglacial origin that displays a morphological and dietary variation tightly coupled to the littoral and pelagic habitats of the lake. The occurrence of such resource polymorphisms might have important consequences for local adaptation and might also be an important initial step in speciation. I have investigated the importance of a number of factors for the development of resource polymorphisms using perch as a study organism. I found a weak genetic basis for morphological differences, and the environmental influence on morphology was of such a magnitude that an induced morphology could be reversed. The results nevertheless suggested that genetic differentiation could be substantial at small spatial and temporal scales, even within habitats. Several environmental factors were shown to influence the morphological development, and the results also suggest that behavioral differences could mediate a morphological response. I also found evidence for that competition-driven divergence might only occur when divergence in resource use is favoured at the same time as growth rates are kept sufficiently high for character divergence to be effective. The results finally indicate that divergence in the gut length of individuals might co-vary with habitat and diet use in resource polymorphic populations. This might enhance habitat fidelity and possibly also facilitate the persistence of resource polymorphisms since individuals should experience a cost of switching diets due to a too specific digestive system. Based on these findings I conclude that small scaled genetic differentiation might be more common than currently acknowledged, that more multi-factorial studies are needed if we are to fully understand the mechanisms behind trait diversity, and that competition not always favors divergence.

With two last decades there has been a very big interest in various feed additives and supplements as, e.g. prebiotics, probiotics, phytobiotics and symbiotics which are applied to keep and maintain a necessary level of the useful microorganisms who could create an environment the nutrients of the feed to be digested more effectively in the tract of animal. From the 1st of January, 2006 in EU there was a ban announced regarding the use of feed antibiotics to obtain better productivity of agricultural animals. For this reason the growers of the agricultural animals started to look for an alternative which could be approved by numbers of the tests. The goal of the study – to reveal what was the influence of “ARBOCEL RC” and “VITACEL R 200” raw fiber concentrates on the both daily weight gain and carcass characteristics of the crossbreed pigs.

Darbo apimtis ir struktūra Darbas parašytas lietuvių kalba, kurį sudaro: įvadas, literatūros apžvalga, medžiagos ir metodai, rezultatai, išvados, naudotos literatūros sąrašas; darbo apimtis 65 puslapiai, darbe yra: 78 literatūros šaltiniai, 15 lentelių ir 13 paveikslėlių. Darbo tikslas įvertinti klinoptilolito įtaką skirtingo amžiaus ir lyties šuniukų augimo spartai ir sveikatingumui. Darbo uždaviniai:  įvertinti šuniukų ir suaugusių šunų šėrimui vartojamų ėdalų maistinę ir energinę vertę;  nustatyti ėdalų suvartojimo kiekius atskirais auginimo periodais priklausomai nuo gyvūno lyties;  nustatyti šuniukų ir suaugusių šunų svorio kitimą priklausomai nuo gyvūno lyties atskirais auginimo periodais;  paskaičiuoti gyvūnų kūno masės priaugimą atskirais auginimo periodais;  nustatyti pagrindinių maisto medžiagų kiekius patinėlių ir kalyčių išmatose;  paskaičiuoti maisto medžiagų pasisavinamumo lygį šuniukų ir suaugusių šunų organizme;  pateikti stebėjimo rezultatus apie išskiriamų išmatų konsistenciją;  pateikti šunų išmatų bakteriologinio tyrimo rezultatus;  pateikti išmatų pH dydžius atskirais auginimo tarpsniais. Šuniukų ir šunų šėrimui buvo naudojamas visavertis ėdalas „NATURE’S PROTECTION“, kurio sudėtyje nustatyta 920 g kg-1 sausosios medžiagos, 260 g kg-1 žalių baltymų, 150 g kg-1 žalių riebalų, 52 g kg-1 žalių pelenų, energinė vertė 20,25 MJ kg-1. Nustatyta, kad tiriamosios grupės šunys ir kalytės tiriamojo laikotarpio atskirais mėnesiais suvartojo mažesnius... [toliau žr. visą tekstą] / The scope of work and structure The Master's project is written in Lithuanian and consists of introduction, literature review, materials and methods, results, conclusions, references. The project comprises of 65 pages, 78 references, 15 tables and 13 pictures. Project aims: the main aim of this project is to evaluate the impact of a clinoptilolite of different age puppies growth rate and their health status. Objectives of the project:  to evaluate the puppies and dogs feeds nutritional and energy values  to determine the amount of food consumptions of different gender animals of various growth periods  to measure the weight alteration of different gender puppies and adult dogs of various growth periods  to estimate the animals weight gain of various growth periods  to measure the amount of the basic nutrients in male and female dogs faeces  to calculate the nutrients absorption level of puppies and adult dogs organisms  to represent the observation results about the dogs faeces consistency  to introduce the results of a bacteriological analysis of the dogs feaces  to present the dogs feaces values of pH of various growth periods Dogs and puppies have been fed with a full-rate dog‘s fodder “NATURE’S PROTECTION“, containing 920 g kg-1 of dry substance, 260 g kg-1 of raw protein, 150 g kg-1 of raw fats, 52 g kg-1 of raw ash; its energetic value - 20,25 MJ kg-1. As research data reveal, female and male dogs of a test group have been consuming lower amount of full-rate... [to full text]

Temos aktualumas. Avininkystė Lietuvoje yra svarbi žemės ūkio sritis. Šio sektoriaus plėtrai šalyje yra palankios gamtinės sąlygos, susiformavusios gyvulių auginimo tradicijos, sukaupta patirtis. Gyvulininkystės sektorius yra daugiašakė ir įvairiapuse produkcija pasižyminti veikla, reikšminga Lietuvos gyventojams daugeliu ekonominių ir socialinių aspektų. Šis sektorius yra reikšmingas, aprūpinant Lietuvos vartotojus įvairiais maisto produktais bei svarbus Lietuvos eksporto šaltinis. Gyvūninės kilmės produktai yra svarbi subalansuotos mitybos dalis. Juose yra daug žmogaus organizmui reikalingų maisto medžiagų, vitaminų ir mineralų. Lietuvos Respublikos žemės ūkis atlieka svarbią ekonominę, socialinę, gamtosauginę ir etnokultūrinę funkciją, todėl laikomas prioritetine ūkio šaka. Jis pajėgus aprūpinti šalies gyventojus visais kokybiškais maisto produktais ir dalį jų eksportuoti. Nors ir lėtai, avininkystės sektorius plečiasi. Auga mėsos paklausa, atsigauna ir vilnos bei kailių perdirbėjai. Vidutinis avių ūkis Lietuvoje, palyginti su vakarų šalimis, dar yra labai mažas. Dauguma augintojų laiko nedaug avių. O tų žmonių, kuriems avininkystė yra verslas, tėra vos kelios dešimtys. Tačiau mažieji augintojai pamažu didina savo bandas. Įdiegus pažangias intensyvaus avių auginimo technologijas, auginant perspektyvias krypties avių veisles, galima tikėtis šio verslo sėkmės. Darbo objektas: skirtingą skaičių avių turintys ūkiai. Darbo tikslas: išanalizuoti ūkio dydžio įtaką avių... [toliau žr. visą tekstą] / Relevance of the thesis. Shepherding has an important place in Lithuania‘s agriculture. There are suitable enviromental conditions, established cattle herding traditions and accumulated experience needed for this sector‘s further development in the country. The area of animal husbandry is activity known for its multisectoral and multifaceted production, many aspects of which has great economical and social significance for Lithuanians. This area is also very significant when providing Lithuanian consumer with eatables, furthermore it is very important branch of Lithuania‘s export. Products of animal origin takes big part in a balanced diet. They contain many components, vitamins and minerals which human body requires daily. Husbandry has important economical, social, enviromental and ethnocultural function in the Republic of Lithuania, thus it has priority in Lithuania‘s economy. It has capability not only to provide quality eatables for citizens, but also to export some. Sheepherding sector is growing, even though the growth rate is not very pronounced. The demand for meat grows; wool and fur processors are recovering. In Lithuania average sheep farm is very small when comparing with farms in other western countries. Most livestock owners don‘t have a lot of sheep. Furthermore, there are only few who make business out of it. However the small farmers seem to be increasing their flocks. If this business were introduced to advanced sheep herding technologies as well as... [to full text]