Ultraviolettkiirguse sõltuvus kliimateguritest. Eesti varasemate UV-kiirguse dooside arvutamine

Väitekirja elektrooniline versioon ei sisalda publikatsioone.Looduslik ultraviolettkiirgus (UV-kiirgus) on päikesekiirguse osa, millest maapinnani jõuab UVB (280–315 nm) ning UVA (315–400 nm) kiirgus. Suure energia tõttu avaldab UV-kiirgus mõju elusorganismidele, materjalidele ning atmosfääri keemiale. Enim pakub ühiskonnale huvi UV-kiirguse mõju inimestele – ohustatud on nii nahk, silmad kui immuunsüsteem, samal ajal osaleb UV-kiirgus D vitamiini sünteesis. UV-kiirguse võimaliku toime hindamiseks on vajalik teada maapinnani jõudva kiirguse spektraalset koostist (lühema lainepikkusega kiirgus on üldiselt ohtlikum), saadud energiat ning kuidas neid mõjustavad keskkonnatingimused. Väitekirja peamiseks eesmärgiks on uurida maapinnani jõudva UV-kiirguse ajalist muutlikust Eestis ning millises ulatuses mõjutavad seda pilved, osoon ning aerosoolid. Andmestik põhineb Tartu Observatooriumis alates 2004. aastast registreeritud UV-kiirguse spektritel ning Tõravere ilmajaama vaatlusandmetel. Suvel selge ilma korral võivad Tõraveres UVA päevadoosid ületada 1500 kJ/m2 ning UVB omad 30 kJ/m2. Selliste suurte päevaste dooside korral ulatub UV indeks keskpäeval üle 7, esmaseid päikesekaitsevahendeid peab kasutama juba UV indeksi 3 korral. UVA ja UVB suhe spektris sõltub eelkõige päikese kõrgusest ning osooni hulgast, muutudes suvise päeva jooksul üle 10 korra. Paksud pilved peavad kinni aga vaid kuni 2/3 UV-kiirgusest. Lisaks mõõdetud andmete uurimisele koostati töö käigus ka mudelid UV-kiirguse päevaste dooside arvutamiseks. Mudeleid rakendati UV-kiirguse rekonstrueerimiseks perioodil 1955–2003. Mudelid on jätkuvalt kasutusel ka instrumendi riketest põhjustatud mõõtepauside täitmiseks. Päevadooside katkematu aegrida on loodud ajavahemikule 1955–2015. Minimaalsed UV-doosid olid Tõraveres 1970ndate lõpus ja 1980ndate alguses. Hiljem UV-kiirguse hulk tõusis ja saavutas maksimumi 2011. aasta. Viimasel ajal on aastased doosid olnud taas languses. Väitekirja valmimist toetas oluliselt EU teadusprojekt „Eesti kiirguskliima“.Natural ultraviolet (UV) radiation, reaching the ground, is a part of solar radiation and is divided to UVB (280–315 nm) and UVA (315–400 nm) ranges. Due to high energy UV radiation can influence living organisms, materials as well as atmospheric photochemistry. The public is most interested in the influence of UV radiation on humans, including damage of skin, eyes and immune system. At the same time UV radiation participates in vitamin D synthesis. To evaluate the possible risk of damage or benefit it is important to know the spectral composition (shorter wavelengths are generally more dangerous), received energy and how they are influenced by environmental conditions. The main objective of this work was to investigate the variability of UV radiation reaching the ground in Tõravere, Estonia and how it is influenced by clouds, ozone and aerosols. The dataset is based on measurements conducted at Tartu Observatory since 2004 and on data from Tõravere meteorological station. It was found that in summer in clear conditions the daily dose of UVA can reach over 1500 kJ/m2 and of UVB over 30 kJ/m2. In these high radiation conditions UV index can be over 7. First sun protection is needed in case of UV index 3. The ratio of UVA and UVB can change more than 10 times during a day in summer. Heavy cloudiness decreases irradiance only by 2/3 during the summer. In addition to data analysis models for calculating daily doses were created and reconstruction of UVB and UVA radiation for period 1955–2003 was made. These models are continuously used for filling measurement gaps. Continuous dataset of daily doses from 1955–2015 is now available. Minimum yearly doses in Tõravere were at the end of the 1970s and at the beginning of the 1980s. Since then the yearly doses increased and maximum level was met in 2011. Recently UV doses have decreased. The thesis was supported by EU scientific project "Estonian radiation climate"

Raiete lühiajaline mõju süsiniku voogudele ja varudele erinevates Eesti metsaökosüsteemides

A Thesis for applying for the degree of Doctor of Philosophy in Forestry.Boreal forests are large C sinks that play an essential role in the fight with climate changes. However, forest management and especially fellings are one of the important factors affecting stand C accumulation capacity. In the present thesis, the short-term effect of thinning and clear-cutting was studied on the ecosystem C cycling in silver birch and Scots pine stands. On the basis of a compiled C budget, a 6-year-old pine stand acted as a moderate C source (NEP -1.37 t C ha-1yr-1), which was in accordance with the results of eddy-covariance measurements at the same study site (NEE -1.19 t C ha-1yr-1). Since the magnitude of C loss via soil heterotrophic respiration was similar with that in middle-aged and matured stands, then the C source status of the site was attributed mostly to the small biomass of trees and thus to the low annual production of the stand. However, since the annual production of the trees increased in the following years and, assuming a stable annual Rh flux, the ecosystem will become a C sink already during a short period after clear-cut. Therefore, the recovery of the C budget after clear-cut depends strongly on timely and vigorous regeneration. Moderate thinning from below was used in the current study. Thinning did not significantly increase soil heterotrophic respiration in silver birch or Scots pine stands of different ages in the second post-thinning year. As expected, thinning decreased the aboveground C storage of the stand, as well as the production of the tree layer, but all thinned stands still remained their C sink status (NEP 1.5-4.4 t C ha-1 yr-1). Therefore, the use of moderate thinning from below can be recommended the retain a stand as a C neutral ecosystem in the immediate post-thinning period both for silver birch and Scots pine. The recovery of C accumulation rate to the pre-thinning level may occur roughly during the following five years.Põhjapoolkera metsad on olulised süsiniku sidujad ja seeläbi kliimamuutuste leevendajad. Ühe olulise tegurina mõjutab puistute süsiniku sidumist aga metsade majandamine erinevate raiete näol. Doktoritöös uuriti harvendus- ja lageraie lühiajalist mõju metsaökosüsteemi süsinikuringele männikutes ja arukaasikutes. Teema on äärmiselt aktuaalne, sest tänapäeva metsanduses tähtsustatakse üha enam puistute süsiniku sidumise aspekti erinevate majandamismeetodite kavandamisel ja rakendamisel. Koostatud süsinikubilansi põhjal osutus kuueaastane männinoorendik mõõdukaks süsiniku emiteerijaks (NEP -1.37 t C ha-1a-1) mis oli heas kooskõlas samal alal läbi viidud turbulentsete kovariatsioonide meetodil hinnatuga (NEE -1.19 t C ha-1a-1). Lageraie järgselt uuenenud männinoorendikus ei olnud aastane heterotroofse mullahingamise voog oluliselt suurem vanemates puistutes mõõdetust, mis näitab, et ökosüsteemi negatiivne süsiniku bilanss oli tingitud puude väikesest biomassist ja seega ka puistu madalast produktiivsusest. Arvestades puude kiirenevat kasvu, võib prognoosida süsinikubilansi tasakaalustumist juba seitsmeaastases puistus. Seega aitab õigeaegne ja kvaliteetne metsauuendamine oluliselt kaasa metsaökosüsteemi lageraie järgsele süsiniku sidumise kiirele taastumisele. Käesolevas töös uuritud puistuid harvendati alameetodil ja mõõduka raiekraadiga. Selline harvendamine ei suurendanud mulla heterotroofse hingamise voogu teisel raiejärgsel aastal arukaasikutes ega männikutes. Loomulikult vähenes peale harvendusraiet puistu maapealne süsiniku varu ja sellega seoses ka puurinde aastane süsiniku sidumise voog, samas jäid kõik uuritud puistud süsinikku siduvateks ökosüsteemideks (NEP 1,5-4,4 t C ha-1a-1). Harvendatud puistute süsiniku sidumise võime taastub raie-eelsele tasemele ligikaudu järgneva viie aasta jooksul. Hooldusraied alameetodil ja mõõduka raiekraadiga ei muuda üldjuhul lati- ja keskealisi arukaasikuid ning männikuid raiejärgselt ajutiselt süsinikku emiteerivateks ökosüsteemideks.Publication of this thesis is supported by the Estonian University of Life Sciences

Organizational Family Values and Happiness in Nonprofit Organizations

Existing studies of individual retention in the nonprofit organizational setting seem relatively silent on the significance of corporate family values and personal happiness, although both concepts could improve particular commitment, better collaboration, and a propensity to perform pro-social behaviour. Grounded on 32 interviews from four Indonesian nonprofit organizations, this article develops the individual retention model based on organizational family values generated by management practices. The findings show that corporate family values would lead to personal happiness, resulting in personal retention.  Meanwhile, nonprofits could influence personal satisfaction and retention by generating organizational family values through certain management practices. This model has broadened our understanding of the relations between corporate values, unique perspectives, and management practices; while also contributing to HRM practitioners in managing staff and volunteers.Existing studies of individual retention in the nonprofit organizational setting seem relatively silent on the significance of corporate family values and personal happiness, although both concepts could improve particular commitment, better collaboration, and a propensity to perform pro-social behaviour. Grounded on 32 interviews from four Indonesian nonprofit organizations, this article develops the individual retention model based on organizational family values generated by management practices. The findings show that corporate family values would lead to personal happiness, resulting in personal retention.  Meanwhile, nonprofits could influence personal satisfaction and retention by generating organizational family values through certain management practices. This model has broadened our understanding of the relations between corporate values, unique perspectives, and management practices; while also contributing to HRM practitioners in managing staff and volunteers

Prediction of Total Suspended Sediments in Penang Waters Using Remote Sensing

Total suspended sediments (TSS) are one of the main causes of pollution in the country’s coastal areas. Land-based loaded and seabed resuspension are two main sources of TSS in coastal and estuary areas. In this study, remote sensing techniques were used to predict TSS concentrations. Landsat-5 TM satellite imagery was used simultaneously with groundtruth data collected on 27th May 2000 in the Penang Straits. Various image processing steps such as geometric correction, radiometric correction and atmospheric correction were carried out in this study. Initially, digital number (DN) of imagery was corrected and converted into reflectance values for algorithm development. Subsequently combinations of various radiometric correction methods were used in this study to reduce the errors from various sources prior to statistical analysis. Data generated from corrected satellite imagery and TSS concentrations measured from field sampling were compared and tested using statistical analysis. Only the best-fit algorithm developed in this study was selected to predict the TSS concentrations from satellite imagery. Out of the six algorithms derived, Algorithm 6 showed the best correlation with the ground-truth data (R2 value of 0.9755 and RMSE value of 4.0107). The developed algorithm was then applied to predict the TSS concentrations on historical Landsat imagery acquired on 1st February 1993. The historical satellite image was normalized and converted to reflectance for the biophysical study. Besides the derived algorithm, models suggested by other researchers were tested in this study. However, the Algorithm 6 showed the best results in predicting TSS concentration for the Penang waters. The predicted TSS concentrations distribution maps were generated and compared with the GIS platform

Modeling Asymmetric Volatility In Oil Prices

Recent volatility in crude oil prices has affected economies around the world, especially the US economy, which is the largest consumer of oil. This paper focuses on how shocks to volatility of crude oil prices may affect future oil prices. The paper uses daily crude oil price data for the past 10 years to test and model the oil price volatility by fitting different variations of GARCH including a univariate asymmetric GARCH model to the series. Tests show high persistence and asymmetric behavior in oil price volatility, and reveal that negative and positive news have a different impact on oil price volatility. These results will help interested observers better understanding of the energy markets and has important consequences for the overall economy

Performance of Malaysian local banks: Before & after merger

Malaysia is experiencing another round of crisis brought about by the global credit crunch. With the impending weaker economy, the resiliency of Malaysian banking sector would again be tested. This paper will gain insights into the performance of Malaysian local banks after the consolidation of banking sector in year 2000 which was expedited by the Asian Financial crisis.The objective of this paper is to find out whether the local banks have achieved performance efficiency during the post merger period namely in the areas of profitability, cost savings and shareholders’ wealth.Comparison and analysis of ratios are used to compare the performance of local banks during the pre-merger period (1999-2000) and post-merger period (2006-2007).Banks’ mergers in Malaysia do not necessary improve their profitability as measured by return on asset (ROA). Cost savings as measured by expenses to revenue ratio indicated mixed result whereas almost all the banks had shown improvement in expenses to asset ratio. Most of the banks had improved in shareholders wealth

The Influence Of Board’s Human Capital And Social Capital Towards Firm Performance In Asian Tourism Industry

This study examines the relationship between firm performance and board diversity in human capital and social capital in the context of the tourism industry. Human capital is represented by educational background and working experience of the board of directors; social capital is represented by external network ties via interlocking directorates of the board of directors. 85 tourism firms from the four economies in Asia, namely China, Hong Kong, Malaysia and Singapore are selected. This sample period of analysis is 2001-2011. Kajian ini mengkaji hubungan antara prestasi firma and kepelbagaian modal insan dan modal sosial lembaga pengarah, dalam konteks industri pelancongan. Modal insan merujuk kepada latar belakang pendidikan serta pengalaman pekerjaan pengarah, manakala modal sosial merujuk kepada jaringan luar pengarah melalui pegangan jawatan pengarah di firma yang lain. Sebanyak 85 firma pelancongan dari empat buah ekonomi di Asia, iaitu China, Hong Kong, Malaysia dan Singapora telah dikaji. Tempoh kajian merangkumi tahun 2001-2011

User-guided Database Schema Generation For Naive Database Developers

The world is abound with data. Data creates value and competitive edges to an organization when it turned into more strategic, customer-oriented, and competitive information, a great significant to the continued health and survival of an organization. Hence, almost every organization has employed a Database Management System (DBMS) to store and manage the huge amount of data. However, problem exists when the ability to leverage the latest techniques and basic features of the tools has historically fallen to a limited group of experts - the certified or database developer with great expertise gained through the years of experiences. Having the software available alone is not enough to support users’ data storage intention due to the concept of database design itself will need to be understood and mastered by the users before they can use the software effectively. This would require formal database design training and cannot be done over a night. As such, the first problem lead to second issue - most users tend to avoid using DBMS but rather opt to keep their data using more familiar software such as Excel spreadsheet or Word processor. This decision even though seems to be appropriate to most users has its drawbacks due to the nature of the software themselves. The objective of this research is to solve the issue above by developing an approach method for users who has less experiences and understanding in database design to be able to develop their own database schema. This proposed user-guided approach will basically prompt users with successive relevant questions and from the feedbacks captured, a database schema will gradually be developed. The scope is first focusing on the database developer in Malaysia due to time constraints. The research method used will be exploratory and constructive where researcher are require to collect data such as survey on the students and naïve database developers and interview the database expert and then make a solution based on design thinking and rapid application development (RAD) of system development life cycle (SDLC). At the end of research, researcher are expected to the generate algorithms and initial prototype for the formulated method to provide a user-friendly platform for the developer or user to reduce the above issue. The technology advance will assist them to deploy a solution that best fit to their need with more scalable, secure, multi-user framework. In short, the research can provide a significant value to the new and less experiences database developer, business and IT research field to make the process simple and understandable

Persistence And Asymmetry In Exchange Rate Volatility

Recent economic downturn in the United States and Europe has affected major currencies around the world. This paper focuses on the behavior of exchange rates over the past decade to study how volatility pattern of these exchange rates responds to any exogenous shocks. The paper focuses on persistence and asymmetry in volatility of major exchange rates due to exogenous shocks. The paper employs a univariate GARCH and an EGRACH model to test the persistence and asymmetry of exchange rate volatility using data from the past decade plus. The results show high persistence and asymmetric behavior in volatility implying that the effect of good news on exchange rates is different from the effect of bad news. The results of this paper have important implications for foreign exchange investors and will provide a better understanding of the foreign exchange market to interested observers