Effect of Lactobacillus sp. isolates supernatant on Escherichia coli O157:H7 enhances the role of organic acids production as a factor for pathogen control

Many attempts have been made to establish the control of foodborne pathogens through Lactobacillus isolates and their metabolism products with success being obtained in several situations. The aim of this study was to investigate the antagonistic effect of eight Lactobacillusisolates, including L. caseisubsp. pseudoplantarum,L. plantarum, L. reuteri and L. delbrueckii subsp. delbrueckii, on the pathogenic Escherichia colistrain O157:H7. The inhibitory effect of pure cultures and two pooled cultures supernatants of Lactobacillus on the growth of pathogenic bacteria was evaluated by the spot agar method and by monitoring turbidity. Antimicrobial activity was confirmed for L. reuteri and L. delbrueckii subsp. delbrueckii and for a pool of lactic acid bacteria. The neutralized supernatant of the pool exerted a higher antimicrobial activity than that of the individual strains. Furthermore, D-lactic acid and acetic acid were produced during growth of the Lactobacillus isolates studied.

Price spike forecasting in a competitive day-ahead energy market

Electricity price forecasting has become an important area of research in the aftermath of the worldwide deregulation of the power industry that launched competitive electricity markets now embracing all market participants including generation and retail companies, transmission network providers, and market managers. Based on the needs of the market, a variety of approaches forecasting day-ahead electricity prices have been proposed over the last decades. However, most of the existing approaches are reasonably effective for normal range prices but disregard price spike events, which are caused by a number of complex factors and occur during periods of market stress. In the early research, price spikes were truncated before application of the forecasting model to reduce the influence of such observations on the estimation of the model parameters; otherwise, a very large forecast error would be generated on price spike occasions. Electricity price spikes, however, are significant for energy market participants to stay competitive in a market. Accurate price spike forecasting is important for generation companies to strategically bid into the market and to optimally manage their assets; for retailer companies, since they cannot pass the spikes onto final customers, and finally, for market managers to provide better management and planning for the energy market. This doctoral thesis aims at deriving a methodology able to accurately predict not only the day-ahead electricity prices within the normal range but also the price spikes. The Finnish day-ahead energy market of Nord Pool Spot is selected as the case market, and its structure is studied in detail. It is almost universally agreed in the forecasting literature that no single method is best in every situation. Since the real-world problems are often complex in nature, no single model is able to capture different patterns equally well. Therefore, a hybrid methodology that enhances the modeling capabilities appears to be a possibly productive strategy for practical use when electricity prices are predicted. The price forecasting methodology is proposed through a hybrid model applied to the price forecasting in the Finnish day-ahead energy market. The iterative search procedure employed within the methodology is developed to tune the model parameters and select the optimal input set of the explanatory variables. The numerical studies show that the proposed methodology has more accurate behavior than all other examined methods most recently applied to case studies of energy markets in different countries. The obtained results can be considered as providing extensive and useful information for participants of the day-ahead energy market, who have limited and uncertain information for price prediction to set up an optimal short-term operation portfolio. Although the focus of this work is primarily on the Finnish price area of Nord Pool Spot, given the result of this work, it is very likely that the same methodology will give good results when forecasting the prices on energy markets of other countries.

Turveperävaunun väsymiskestävyyden parantaminen

Työssä tutkittiin turveperävaunun renkaan kiinnitysrakenteen väsymiskestävyyttä. Väsymiskestävyyden parantamiseksi renkaiden kiinnityskohdan muotoilu ja mitoitus suunniteltiin uudelleen. Suunnittelussa keskityttiin ensisijaisesti nimellisten ja rakenteellisten jännitysheilahdusten pienentämiseen. Sekä vanhan, että uuden rakenneratkaisun väsymiskestoikiä tarkasteltiin käyttämällä hot spot – menetelmää.

Lämmöntuotanto älykkäässä energiaverkossa

Energiaverkon edistäminen tulee olemaan tulevaisuudessa suuressa roolissa niin Suomessa kuin maailmalla. Tällöin yhtenä vaihtoehtona on älykkyyden tuominen koko energiajärjestelmään niin sähkön kuin lämmönkin osalta. Tällöin voidaan vähentää kulutushuippujen aikaista energian käyttöä ja saada koko verkoston energiankulutus profiili tasaiseksi. Tässä työssä tarkastellaan spot-sähkön hyödyntämismahdollisuuksia lämmöntuotannossa. Työssä kehitetyn mallinnustyökalun avulla tutkittiin erilaisia ajotapoja ja erilaisten järjestelmien kokonaiskustannuksia. Työssä esitellään esimerkkilaskennan avulla spot-sähkön käytöstä syntyviä kustannuksia ja keinoja vaikuttaa niihin eri järjestelmä muutoksin. Malli mahdollistaa erilaisten järjestelmien ja niiden ajotapojen tutkimista. Mallilla voidaan myös tutkia erilaisten alueiden kulutuskäyttäytymistä ja hyödyntää sitä kustannuslaskelmiin. Voidaan todeta, että työssä muodostunut malli on toimiva ja sitä voidaan hyödyntää alueellisten lämmöntuotantojärjestelmien ajotapojen optimointiin.

Characterization Of Process Efficiency Improvement In Laser Additive Manufacturing

Laser additive manufacturing (LAM), known also as 3D printing, has gained a lot of interest in past recent years within various industries, such as medical and aerospace industries. LAM enables fabrication of complex 3D geometries by melting metal powder layer by layer with laser beam. Research in laser additive manufacturing has been focused in development of new materials and new applications in past 10 years. Since this technology is on cutting edge, efficiency of manufacturing process is in center role of research of this industry. Aim of this thesis is to characterize methods for process efficiency improvements in laser additive manufacturing. The aim is also to clarify the effect of process parameters to the stability of the process and in microstructure of manufactured pieces. Experimental tests of this thesis were made with various process parameters and their effect on build pieces has been studied, when additive manufacturing was performed with a modified research machine representing EOSINT M-series and with EOS EOSINT M280. Material used was stainless steel 17-4 PH. Also, some of the methods for process efficiency improvements were tested. Literature review of this thesis presents basics of laser additive manufacturing, methods for improve the process efficiency and laser beam – material- interaction. It was observed that there are only few public studies about process efficiency of laser additive manufacturing of stainless steel. According to literature, it is possible to improve process efficiency with higher power lasers and thicker layer thicknesses. The process efficiency improvement is possible if the effect of process parameter changes in manufactured pieces is known. According to experiments carried out in this thesis, it was concluded that process parameters have major role in single track formation in laser additive manufacturing. Rough estimation equations were created to describe the effect of input parameters to output parameters. The experimental results showed that the WDA (width-depth-area of cross-sections of single track) is correlating exponentially with energy density input. The energy density input is combination of the input parameters of laser power, laser beam spot diameter and scan speed. The use of skin-core technique enables improvement of process efficiency as the core of the part is manufactured with higher laser power and thicker layer thickness and the skin with lower laser power and thinner layer thickness in order to maintain high resolution. In this technique the interface between skin and core must have overlapping in order to achieve full dense parts. It was also noticed in this thesis that keyhole can be formed in LAM process. It was noticed that the threshold intensity value of 106 W/cm2 was exceeded during the tests. This means that in these tests the keyhole formation was possible.

Further molecular characterization of weed-associated begomoviruses in Brazil with an emphasis on Sida spp

Begomoviruses are whitefly-transmitted, single-stranded DNA viruses that are often associated with weed plants. The aim of this study was to further characterize the diversity of begomoviruses infecting weeds (mostly Sida spp.) in Brazil. Total DNA was extracted from weed samples collected in Viçosa (Minas Gerais state) and in some municipalities of Alagoas state in 2009 and 2010. Viral genomes were amplified by RCA, cloned and sequenced. A total of 26 DNA-A clones were obtained. Sequence analysis indicated the presence of 10 begomoviruses. All viral isolates from Blainvillea rhomboidea belonged to the same species, Blainvillea yellow spot virus (BlYSV ), thereby suggesting that BlYSV may be the only begomovirus present in this weed species. Four isolates represent new species, for which the following names are proposed: Sida yellow blotch virus (SiYBV), Sida yellow net virus (SiYNV), Sida mottle Alagoas virus (SiMoAV) and Sida yellow mosaic Alagoas virus (SiYMAV). Recombination events were detected among the SiYBV isolates and in the SiYNV isolate. These results constitute further evidence of the high species diversity of begomoviruses in Sida spp. However, the role of this weed species as a source of begomoviruses infecting crop plants remains to be determined.

Notchikololiitosten FE-analyysit

Työn kandidaatintyössä tutkittiin kolollisen levyrakenteen hot spot -jännityksiä ja väsymiskestävyyttä varioimalla kolon sädettä. Työssä haluttiin selvittää, kuinka hot spot -jännitykset, rakenteen kestoikä ja rakenteen kriittinen kohta muuttuvat, kun kolon sädettä muutetaan. Työn tavoitteena oli myös tutkia, kuinka laboratoriossa suoritettujen väsytyskokeiden ja tietokoneella laskettujen elementtimallien tulokset eroavat toisistaan.

Tilttisangan väsymiskestävyys

Kandidaatin työssä tutkittiin tilttisangan väsymiskestävyyttä laboratoriokokeella. Tilttisangalle laskettiin myös teoreettinen väsymiskestoikä nimellisen jännityksen menetelmällä. Tutkimustulosten perusteella havaittiin tilttisangan väsymisen kannalta kriittiseksi kohdaksi kuormaa kantamattoman korvakkeen hitsausliitos.

Vääntökuormitetun koteloprofiilipuomin väsymiskestävyys

Tässä työssä tutkittiin vääntökuormitettua hitsattua koteloprofiilipuomia. Vääntökuormitus aiheuttaa koteloprofiiliin vinouttavan voimasysteemin, joka aiheuttaa kotelopalkkiin sekä poikittaisia taivutusjännityksiä että pitkittäisiä jännityksiä. Vinoutumisen aiheuttamia lisära-situksia on tutkittu analyyttisesti BEF-analogian avulla sekä elementtimenetelmää apuna käyttäen. Lisäksi vääntökuormitus aiheuttaa puomiin estetyn väännön jännityksiä. Väsymiskestoikää tutkittiin laboratoriossa suoritettujen väsytyskokeiden avulla sekä las-kennallisesti. Kestoikälaskennassa käytettiin tehollisen lovijännityksen menetelmää hitsin juuren puolen väsymisen arvioinnissa sekä hot spot- jännityksen menetelmää hitsin rajavii-van väsymisen arvioinnissa. Teholliset lovijännitykset sekä hot spot jännitykset ovat määri-tetty elementtimenetelmän avulla. Laboratoriokokeiden ja elementtimenetelmä laskennan perusteella saatiin rakenteen kes-toiän kannalta kriittiset detaljit määritettyä. Kriittiset detaljit sijaitsevat puomin päädyn rakenteissa. Tutkimuksessa saatiin selville, että kriittisten detaljien rakenteellisilla ja valmis-tusteknisillä ratkaisuilla on merkittävä vaikutus lopullisen tuotteen väsymiskestoikään.

Laser cladding with scanning optics

Scanning optics create different types of phenomena and limitation to cladding process compared to cladding with static optics. This work concentrates on identifying and explaining the special features of laser cladding with scanning optics. Scanner optics changes cladding process energy input mechanics. Laser energy is introduced into the process through a relatively small laser spot which moves rapidly back and forth, distributing the energy to a relatively large area. The moving laser spot was noticed to cause dynamic movement in the melt pool. Due to different energy input mechanism scanner optic can make cladding process unstable if parameter selection is not done carefully. Especially laser beam intensity and scanning frequency have significant role in the process stability. The laser beam scanning frequency determines how long the laser beam affects with specific place local specific energy input. It was determined that if the scanning frequency in too low, under 40 Hz, scanned beam can start to vaporize material. The intensity in turn determines on how large package this energy is brought and if the intensity of the laser beam was too high, over 191 kW/cm2, laser beam started to vaporize material. If there was vapor formation noticed in the melt pool, the process starts to resample more laser alloying due to deep penetration of laser beam in to the substrate. Scanner optics enables more flexibility to the process than static optics. The numerical adjustment of scanning amplitude enables clad bead width adjustment. In turn scanner power modulation (where laser power is adjusted according to where the scanner is pointing) enables modification of clad bead cross-section geometry when laser power can be adjusted locally and thus affect how much laser beam melts material in each sector. Power modulation is also an important factor in terms of process stability. When a linear scanner is used, oscillating the scanning mirror causes a dwell time in scanning amplitude border area, where the scanning mirror changes the direction of movement. This can cause excessive energy input to this area which in turn can cause vaporization and process instability. This process instability can be avoided by decreasing energy in this region by power modulation. Powder feeding parameters have a significant role in terms of process stability. It was determined that with certain powder feeding parameter combinations powder cloud behavior became unstable, due to the vaporizing powder material in powder cloud. Mainly this was noticed, when either or both the scanning frequency or powder feeding gas flow was low or steep powder feeding angle was used. When powder material vaporization occurred, it created vapor flow, which prevented powder material to reach the melt pool and thus dilution increased. Also powder material vaporization was noticed to produce emission of light at wavelength range of visible light. This emission intensity was noticed to be correlated with the amount of vaporization in the powder cloud.

Host Parasite Interactions in Damselflies. From Individuals to Populations

The main goal of this thesis is to increase understanding on evolutionary and ecological factors that have contributed to differences in parasite numbers in insects. Furthermore, the thesis addresses the effects of parasites on their hosts. The most important findings were: The Northern damselfly’s (Coenagrion hastulatum) immune response to artificial pathogen increased with increasing parasite numbers (Article I). Marginal, more isolated C. hastulatum populations on the edge of distribution have fewer parasites when compared to distribution’s core populations (Article II). The Banded damselfly Calopteryx splendens individuals with higher homozygosity have more parasites, however, the rate of homozygosity did not differ between populations (Article III). Parasite prevalence was affected by whether the host species occurred in allopatric or sympatric population: sympatric C. splendens populations with sister species the Beautiful damselfly Calopteryx virgo harbored more parasites (Article IV). Parasites were associated with the wing spot size, an ornament under sexual selection, and thus may play an important role in character displacement, i.e. the size of the wing spot (Article V). To conclude with, this thesis brings about new information on the parasite infection patterns in insects, proposing several factors to contribute to these patters, as well as it addresses the effects of parasites on their hosts, from individual to population level.

Joukkorahoituksen markkinointi viihdeteollisuudessa

Laadullinen tutkimus joukkorahoituksen markkinointikeinoista, joukkorahoituksen nykytilasta ja terminologiasta sekä potentiaalista rahoitusmuotona viihdeteollisuudessa. Empiirinen aineisto on kerätty Blind Spot -tuotantoyhtiöstä.

Commodity Future Price Premiums – Case EU ETS

The purpose of this thesis was to study commodity future price premiums and their nature on emission allowance markets. The EUA spot and future contracts traded on the secondary market during EU ETS Phase 2 and Phase 3 were selected for empirical testing. The cointegration of spot and future prices was examined with Johansen cointegration methodology. Daily interest rates with a similar tenor to the future contract maturity were used in the cost-of-carry model to calculate the theoretical future prices and to estimate the deviation from the fair value of future contracts, assumed to be explained by the convenience yield. The time-varying dependence of the convenience yield was studied by regression testing the correlation between convenience yield and the time to maturity of the future contract. The results indicated cointegration between spot and future prices, albeit depending on assumptions on linear trend and intercept in cointegration vector Dec-14 and Dec-15 contracts. The convenience yield correlates positively with the time-to-maturity of the future contract during Phase 2, but negatively during Phase 3. The convenience yield featured positive correlation with spot price volatility and negative correlation with future price volatility during both Phases 2 and 3.

Frequency of B cells in normal mice which recognize self proteins

The mechanism whereby the immune system avoids self-aggression is one of the central issues of Immunology. The discovery of natural autoantibodies, mainly of IgM isotype, and of idiotypic interactions between antibodies indicates that elements of the immune system interact with self constituents and with themselves. Results of studies with soluble antibodies have indicated that the pool of circulating IgM represents the end result of a highly selective process of B cells activation and differentiation by self proteins resulting in the formation of a network. The objective of the present work was to determine the frequency of self-reacting B cells in normal mice. We were able to detect B cells that recognize self proteins present in extracts of different organs in normal adult, 2-3-month old, BALB/c and C57BL/6 mice with an ELISA spot assay. About 1% of total IgM-secreting cells among small, LPS-stimulated spleen cells reacted with organ extracts, whereas among large spleen cells the frequency was 5- to 10-fold lower. Immunization induced an increase in the frequency of IgM-secreting cells. The present results provide cellular evidence for the results of studies done at the serological level. The physiological role of these self-recognizing cells, as well as their participation in autoimmune processes, remain to be established