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  • Malmivaara-Lämsä, Minna (Finnish Society of Forest Science, Finnish Forest Research Institute, Faculty of Agriculture and Forestry of the University of Helsinki, Faculty of Forestry of the University of Joensuu, 2008)
    The impacts of fragmentation and recreational use on the hemiboreal urban forest understorey vegetation and the microbial community of the humus layer (the phospholipid fatty acid (PLFA) pattern, microbial biomass and microbial activity, measured as basal respiration) were examined in the greater Helsinki area, southern Finland. Trampling tolerance of 1) herb-rich OMT, 2) mesic MT, and 3) sub-xeric VT forests (in decreasing order of fertility) was studied by comparing relative understorey vegetation cover (urban/untrampled reference ratio) of the three forest types. The trampling tolerance of forest vegetation increased with the productivity of the site (sub-xeric < mesic < herb-rich). Wear of understorey vegetation correlated positively with the number of residents (i.e., recreational pressure) around the forest patch. An increase of 15000 residents within a radius of 1 km around a forest patch was associated with ca. 30% decrease in the relative understorey vegetation cover. The cover of dwarf shrub Vaccinium myrtillus in particular decreased with increasing levels of wear. The cover of mosses in urban forests was less than half of that in untrampled reference areas. Cover of tree saplings, mainly Sorbus aucuparia, and some resilient herbs was higher than in the reference areas. In small urban forest fragments, broad-leaved trees, grasses and herbs were more abundant and mosses were scarcer than in larger urban forest areas. Thus, due to trampling and edge effects, resilient herb and grass species are replacing sensitive dwarf shrubs, mosses and lichens in urban forests. Differences in the soil microbial community structure were found between paths and untrampled areas and the effects of paths extended more than one meter from the paths. Paths supported approximately 25-30% higher microbial biomass with a transition zone of at least 1 m from the path edge. However, microbial activity per unit of biomass was lower on paths than in untrampled areas. Furthermore, microbial biomass and activity were 30-45% lower at the first 20 m into the forest fragments, due to low moisture content of humus near the edge. The decreased microbial activity detected at forest edges and paths implies decreased litter decomposition rates, and thus, a change in nutrient cycling. Changes in the decomposition and nutrient supply may in turn affect the diversity and function of plant communities in urban forests. Keywords: boreal forest vegetation, edge effects, phospholipid fatty acids, trampling, urban woodlands, wear
  • Viherä-Aarnio, Anneli (Helsingin yliopisto, 2009)
    The aim of this thesis was to increase our knowledge about the effects of seed origin on the timing of height growth cessation and field performance of silver birch from different latitudes, with special attention paid to the browsing damage by moose in young birch plantations. The effect of seed origin latitude and sowing time on timing of height growth cessation of first-year seedlings was studied in a greenhouse experiment with seven seed origins (lat. 58º - 67ºN). Variation in critical night length (CNL) for 50 % bud set within two latitudinally distant stands (60º and 67ºN) was studied in three phytotron experiments. Browsing by moose on 5-11 -year-old silver birch saplings from latitudinally different seed origins (53º - 67ºN) was studied in a field experiment in southern Finland. Yield and stem quality of 22-year-old silver birch trees of Baltic, Finnish and Russian origin (54º - 63ºN) and the effect of latitudinal seed transfers were studied in two provenance trials at Tuusula, southern and Viitasaari, central Finland. The timing of height growth cessation depended systematically on latitude of seed origin and sowing date. The more northern the seed origin, the earlier the growth cessation and the shorter the growth period. Later sowing dates delayed growth cessation but also shortened the growth period. The mean CNL of the southern ecotype was longer, 6.3 ± 0.2 h (95 % confidence interval), than that of the northern ecotype, 3.1 ± 0.3 h. Within-ecotype variance of the CNL was higher in the northern ecotype (0.484 h2) than in the southern ecotype (0.150 h2). Browsing by moose decreased with increasing latitude of seed origin and sapling height. Origins transferred from more southern latitudes were more heavily browsed than the more northern native ones. Southern Finnish seed origins produced the highest volume per unit area in central Finland (lat. 63º11'N). Estonian and north Latvian stand seed origins, and the southern Finnish plus tree origins, were the most productive ones in southern Finland (lat. 60º21'N). Latitudinal seed transfer distance had a significant effect on survival, stem volume/ha and proportion of trees with a stem defect. The relationship of both survival and stem volume/ha to the latitudinal seed transfer distance was curvilinear. Volume was increased by transferring seed from ca. 2 degrees of latitude from the south. A longer transfer from the south, and transfer from the north, decreased the yield. The proportion of trees with a stem defect increased linearly in relation to the latitudinal seed transfer distance from the south.
  • Vakkuri, Anne (Helsingin yliopisto, 2000)
  • Viskari-Lähdeoja, Suvi (Helsingin yliopisto, 2013)
    Background and aims. Sudden infant death syndrome (SIDS) is a rare lethal event occurring in 0.1 to 0.3 of infants. In Finland, 10 to 20 infants die from SIDS annually. Research has defined many risk factors for SIDS, but the cascade leading to death remains unexplained. Cardiovascular recordings of infants succumbing to SIDS, as well as animal models, suggest that the final sequelae involve cardiovascular collapse resembling hypotensive shock. There is also evidence of previous hypoxia in SIDS infants. In animal studies, vestibulo-mediated cardiovascular control has been shown to be important in hypotensive shock. Hence, we hypothetized that SIDS victims may have impaired vestibulo-mediated cardiovascular control, possibly due to previous hypoxic episodes. In this thesis, we studied cardiovascular control, and especially vestibulo-mediated cardiovascular control in infants with known risk factors for SIDS at 2 to 4 months of age when the risk for SIDS is highest. Study subjects. A full polysomnographic recording with continuous blood pressure (BP) measurement was performed in 50 infants at 2-4 months of age: 20 control infants, nine infants with univentricular heart (UVH) suffering from chronic hypoxia, 10 infants with bronchopulmonary dysplasia (BPD) with intermittent postnatal hypoxic events, and 11 infants whose mothers had smoked during pregnancy, and thus had been exposed to intrauterine hypoxia and nicotine, were studied. In addition, 20 preterm infants were studied at the gestational age of 34-39 weeks to evaluate developmental aspects of cardiovascular control during head-up tilt test and vestibular stimulus. Methods. Linear side motion and 45° head-up tilt tests were performed in quiet non-rapid eye movement sleep (NREM). Heart rate (HR) and BP responses were analysed from the tests without signs of subcortical or cortical arousal. In addition, HR variability during NREM sleep was assessed. As a general marker of cardiovascular reactivity, HR response to spontaneous arousal from NREM sleep was also evaluated. Results.Side motion test. In the side motion test, control infants presented a biphasic response. First, there was a transient increase in HR and BP. This was followed by a decrease in BP to below baseline, and a return to baseline in HR. All other infant groups showed altered responses. UVH infants and preterm infants near term age had markedly reduced responses. Infants with BPD presented with variable responses: some responded similarly to controls, whereas others showed no initial increase in BP, and the following BP decrease was more prominent. Infants with intrauterine exposure to cigarette smoke showed flat initial BP responses, and the following decrease was more prominent, similarly to a subgroup of BPD infants. Tilt test. Control infants presented with a large variability in BP responses to head-up tilting. On average, systolic BP remained, at first, close to baseline, and diastolic BP increased, after which both decreased and remained below baseline even at the end of the tilt test. On average, HR showed a biphasic response with an initial increase followed by a decrease to below and, finally, a return to baseline. UVH infants showed a similar BP response, but their HR response was tachycardic. Preterm infants with BPD presented with an even greater variability in their BP responses to head-up tilts than control infants, but the overall response as a group did not differ from that of the controls. The tilt response of infants exposed to maternal cigarette smoking during pregnancy did not markedly differ from the control response. Preterm infants near term age showed attenuated responses in both cardiovascular measures, together with greater inter-subject variability compared to the control infants. Discussion. In conclusion, the studied infants with SIDS risk factors showed altered vestibulo-mediated cardiovascular control during the linear side motion test and head-up tilt test. The findings support our initial hypothesis that some infants with SIDS risk factors have defective vestibulo-mediated cardiovascular control, which may lead to death in life-threatening situations.
  • Kalliokoski, Annikka (Helsingin yliopisto, 2008)
    Organic anion-transporting polypeptide 1B1 (OATP1B1), encoded by the SLCO1B1 gene, is an influx transporter expressed on the sinusoidal membrane of human hepatocytes. The common c.521T>C (p.Val174Ala) single-nucleotide polymorphism (SNP) of the SLCO1B1 gene has been associated with reduced OATP1B1 transport activity in vitro and increased plasma concentrations of several of its substrate drugs in vivo in humans. Another common SNP of the SLCO1B1 gene, c.388A>G (p.Asn130Asp), defining the SLCO1B1*1B (c.388G-c.521T) haplotype, has been associated with increased OATP1B1 transport activity in vitro. The aim of this thesis was to investigate the role of SLCO1B1 polymorphism in the pharmacokinetics of the oral antidiabetic drugs repaglinide, nateglinide, rosiglitazone, and pioglitazone. Furthermore, the effect of the SLCO1B1 c.521T>C SNP on the extent of interaction between gemfibrozil and repaglinide as well as the role of the SLCO1B1 c.521T>C SNP in the potential interaction between atorvastatin and repaglinide were evaluated. Five crossover studies with 2-4 phases were carried out, with 20-32 healthy volunteers in each study. The effects of the SLCO1B1 c.521T>C SNP on single doses of repaglinide, nateglinide, rosiglitazone, and pioglitazone were investigated in Studies I and V. In Study II, the effects of the c.521T>C SNP on repaglinide pharmacokinetics were investigated in a dose-escalation study, with repaglinide doses ranging from 0.25 to 2 mg. The effects of the SLCO1B1*1B/*1B genotype on repaglinide and nateglinide pharmacokinetics were investigated in Study III. In Study IV, the interactions of gemfibrozil and atorvastatin with repaglinide were evaluated in relation to the c.521T>C SNP. Plasma samples were collected for drug concentration determinations. The pharmacodynamics of repaglinide and nateglinide was assessed by measuring blood glucose concentrations. The mean area under the plasma repaglinide concentration-time curve (AUC) was ~70% larger in SLCO1B1 c.521CC participants than in c.521TT participants (P ≤ 0.001), but no differences existed in the pharmacokinetics of nateglinide, rosiglitazone, and pioglitazone between the two genotype groups. In the dose-escalation study, the AUC of repaglinide was 60-110% (P ≤ 0.001) larger in c.521CC participants than in c.521TT participants after different repaglinide doses. Moreover, the AUC of repaglinide increased linearly with repaglinide dose in both genotype groups (r > 0.88, P 0.001). The AUC of repaglinide was ~30% lower in SLCO1B1*1B/*1B participants than in SLCO1B1*1A/*1A (c.388AA-c.521TT) participants (P = 0.007), but no differences existed in the AUC of nateglinide between the two genotype groups. In the drug-drug interaction study, the mean increase in the repaglinide AUC by gemfibrozil was ~50% (P = 0.002) larger in c.521CC participants than in c.521TT participants, but the relative (7-8-fold) increases in the repaglinide AUC did not differ significantly between the genotype groups. In c.521TT participants, atorvastatin increased repaglinide peak plasma concentration and AUC by ~40% (P = 0.001) and ~20% (P = 0.033), respectively. In each study, after repaglinide administration, there was a tendency towards lower blood glucose concentrations in c.521CC participants than in c.521TT participants. In conclusion, the SLCO1B1 c.521CC genotype is associated with increased and the SLCO1B1*1B/*1B genotype with decreased plasma concentrations of repaglinide, consistent with reduced and enhanced hepatic uptake, respectively. Inhibition of OATP1B1 plays a limited role in the interaction between gemfibrozil and repaglinide. Atorvastatin slightly raises plasma repaglinide concentrations, probably by inhibiting OATP1B1. The findings on the effect of SLCO1B1 polymorphism on the pharmacokinetics of the drugs studied suggest that in vivo in humans OATP1B1 significantly contributes to the hepatic uptake of repaglinide, but not to that of nateglinide, rosiglitazone, or pioglitazone. SLCO1B1 polymorphism may be associated with clinically significant differences in blood glucose-lowering response to repaglinide, but probably has no effect on the response to nateglinide, rosiglitazone, or pioglitazone.
  • Barua, Sepul K (Helsingin yliopisto, 2012)
    This dissertation examines the effects of taxes and policy instruments that aim to regulate climate services from forests. It consists of a summary section and four articles. Articles (I) and (II) examine the effects of taxes on management decisions in the context of managed boreal forests distinguished by forest-owners amenity preferences and also their age. Articles (III) and (IV) examine the role of carbon-based policy instruments in the presence of taxes on land incomes in curbing tropical deforestation. Article (I) reveals that the intensity of forest-owners preferences for forest amenities affects the non-neutrality of forest taxes pertaining to forest harvesting. Therefore, the effects of taxes depend on this intensity. This highlights the importance of developing methods to measure forest-owners amenity preferences quantitatively. Article (II) shows that the age of forest-owners governs their propensity to consume as opposed to leave bequests. Furthermore, it shown that the effects of capital income and inheritance taxes vary across different age-groups of forest-owners. Article (III) demonstrates that taxes on forestry and cash-crop incomes, per se, may be ineffective in curbing tropical forest loss. The carbon payments may complement these taxes, and an effective policy to combat tropical deforestation should jointly target forestry and cash-crop sectors. Article (IV) demonstrates the link between carbon compensation policies and land income taxation. An optimal carbon compensation scheme may require that national governments are allowed to use different compensation rates from that applied globally when passing national level compensations on to the local level. These results suggest that existing policies such as taxation should be accounted for in the analysis and design of international carbon policy instruments that aim at enhancing forests role in climate change mitigation.
  • Aulavuori, Katja (Helsingin yliopisto, 2008)
    Tutkielma käsittelee suomalaisten televisiotekstittäjien ammatillisuutta, käännösprosessia ja digitaalisten tekstitysohjelmien vaikutuksia tekstitysprosessiin ammattitekstittäjien näkökulmasta. Suomen television digitalisoituminen on aiheuttanut mullistuksia myös tekstitysalalla kun tekstitettävä kuvamateriaali on ryhdytty toimittamaan käännöstoimistoille ja tekstittäjille digitaalisena. Teoriaosuudessa käsitellään käännös- ja tekstitystutkimusta sekä koulutusta Suomessa, ammattitaitoa ja ammatillisuutta sekä kääntämisen apukeinoja. Tekstittäminen esitellään erikoistuneena kääntämisen muotona. On kuitenkin myös huomioitava, että kääntäminen on yksi vaihe tekstitysprosessissa. Teoriaosuus päättyy suomalaisten televisiotekstittäjien arjen ja työkentän nykytilanteen käsittelyyn – tekstittäjät työskentelevät monenlaisilla työehdoilla ja laadun kriteerit saatetaan joutua arvioimaan uudelleen. Empiirisen osan alussa esitetään, että suomalaisia televisiotekstittäjiä on haastateltu yllättävän vähän, ja Jääskeläisen ajatuksiin nojaten mainitaan, että tekstittämisen alalla on vielä paljon tutkimatta – etenkin suomalaisesta tekstitysprosessista löytyy tutkittavaa. Tutkimuskohde on ammatikseen televisioon tekstityksiä tekevät kääntäjät. Suomalaiselle tekstitykseen erikoistuneelle käännöstoimistolle työskenteleville tekstittäjille lähetettiin alkutalvesta 2008 kyselylomake, jolla kartoitettiin sekä monivalintakysymyksillä että avoimilla kysymyksillä heidän ammatillisuuttaan, työmenetelmiään, käännös- ja tekstitysprosessiaan, ammattiylpeyttään ja -identiteettiään, ajanhallintaansa, sekä heidän käyttämäänsä digitaalista tekstitysohjelmaa. Tutkimuksessa kävi ilmi, että lähes kolmanneksella vastaajista on ammatistaan neutraali tai jopa negatiivinen käsitys. Näitä tekstittäjiä yhdistää se seikka, että kaikilla on alle 5 vuotta kokemusta alalta. Valtaosa vastanneista on kuitenkin ylpeitä siitä, että toimivat suomen kielen ammattilaisina. Tekstitysprosessi oli lomakkeessa jaettu esikatseluvaiheeseen, käännösvaiheeseen, ajastamisvaiheeseen ja korjauskatseluvaiheeseen. Tekstittäjät pyydettiin mm. arvioimaan tekstitysprosessinsa kokonaiskestoa. Kestoissa ilmeni suuria eroavaisuuksia, joista ainakin osa korreloi kokemuksen kanssa. Runsas puolet vastaajista on hankkinut digitaalisen tekstitysohjelmiston käyttöönsä ja osa ajastaa edelleen käännöstoimistossa muun muassa ohjelmiston kalleuden vuoksi. Digitaalisen ohjelmiston myötä tekstitysprosessiin ja työkäytänteisiin on tullut muutoksia, kun videonauhureista ja televisioista on siirrytty pelkän tietokoneen käyttöön. On mahdollista tehdä etätyötä kaukomailta käsin, kääntää ja ajastaa lomittain tai tehdä esiajastus ja kääntää sitten. Digitaalinen tekniikka on siis mahdollistanut tekstitysprosessin muuttumisen ja vaihtoehtoiset työmenetelmät, mutta kaikista menetelmistä ei välttämättä ole tekstittäjälle hyötyä. Perinteinen tekstitysprosessi (esikatselu, repliikkijakojen merkitseminen käsikirjoitukseen, kääntäminen ja repliikkien laadinta, korjaukset ja tarkastuskatselu) vaikuttaa edelleen tehokkaimmalta. Vaikka työkäytänteet eroavat toisistaan, kokonaiskäsitys on se, että digitalisoitumisen alkukangertelujen jälkeen tekstittäjien työskentely on tehostunut.
  • Pekcan-Hekim, Zeynep (Helsingin yliopisto, 2007)
    In aquatic systems, the ability of both the predator and prey to detect each other may be impaired by turbidity. This could lead to significant changes in the trophic interactions in the food web of lakes. Most fish use their vision for predation and the location of prey can be highly influenced by light level and clarity of the water environment. Turbidity is an optical property of water that causes light to be scattered and absorbed by particles and molecules. Turbidity is highly variable in lakes, due to seasonal changes in suspended sediments, algal blooms and wind-driven suspension of sediments especially in shallow waters. There is evidence that human activity has increased erosion leading to increased turbidity in aquatic systems. Turbidity could also play a significant role in distribution of fish. Turbidity could act as a cover for small fish and reduce predation risk. Diel horizontal migration by fish is common in shallow lakes and is considered as consequences of either optimal foraging behaviour for food or as a trade-off between foraging and predator avoidance. In turbid lakes, diel horizontal migration patterns could differ since turbidity can act as a refuge itself and affect the predator-prey interactions. Laboratory experiments were conducted with perch (Perca fluviatilis L.) and white bream (Abramis björkna (L.)) to clarify the effects of turbidity on their feeding. Additionally to clarify the effects of turbidity on predator preying on different types of prey, pikeperch larvae (Sander lucioperca (L.)), Daphnia pulex (Leydig), Sida crystallina (O.F. Müller), and Chaoborus flavicans (Meigen) were used as prey in different experiments. To clarify the role of turbidity in distribution and diel horizontal migration of perch, roach (Rutilus rutilus (L.)) and white bream, field studies were conducted in shallow turbid lakes. A clear and a turbid shallow lake were compared to investigate distribution of perch and roach in these two lakes in a 15-year study period. Feeding efficiency of perch and white bream was not significantly affected with increasing clay turbidity up to 50 NTU. The perch experiments with pikeperch larvae suggested that clay turbidity could act as a refuge especially at turbidity levels higher than 50 NTU. Perch experiments with different prey types suggested that pikeperch larvae probably use turbidity as a refuge better compared to Daphnia. Increase in turbidity probably has stronger affect on perch predating on plant-attached prey. The main findings of the thesis show that turbidity can play a significant role in distribution of fish. Perch and roach could use turbidity as refuge when macrophytes disappear while small perch may also use high turbidity as refuge when macrophytes are present. Floating-leaved macrophytes are probably good refuges for small fish in clay-turbid lakes and provide a certain level of turbidity and not too complex structure for refuge. The results give light to the predator-prey interactions in turbid environments. Turbidity of water should be taken in to account when studying the diel horizontal migrations and distribution of fish in shallow lakes.
  • Saarinen, Antti (2009)
    Data on the influence of unilateral vocal fold paralysis on breathing, especially other than information obtained by spirometry, are relatively scarce. Even less is known about the effect of its treatment by vocal fold medialization. Consequently, there was a need to study the issue by combining multiple instruments capable of assessing airflow dynamics and voice. This need was emphasized by a recently developed medialization technique, autologous fascia injection; its effects on breathing have not previously been investigated. A cohort of ten patients with unilateral vocal fold paralysis was studied before and after autologous fascia injection by using flow-volume spirometry, body plethysmography and acoustic analysis of breathing and voice. Preoperative results were compared with those of ten healthy controls. A second cohort of 11 subjects with unilateral vocal fold paralysis was studied pre- and postoperatively by using flow-volume spirometry, impulse oscillometry, acoustic analysis of voice, voice handicap index and subjective assessment of dyspnoea. Preoperative peak inspiratory flow and specific airway conductance were significantly lower and airway resistance was significantly higher in the patients than in the healthy controls (78% vs. 107%, 73% vs. 116% and 182% vs. 125% of predicted; p = 0.004, p = 0.004 and p = 0.026, respectively). Patients had a higher root mean square of spectral power of tracheal sounds than controls, and three of them had wheezes as opposed to no wheezing in healthy subjects. Autologous fascia injection significantly improved acoustic parameters of the voice in both cohorts and voice handicap index in the latter cohort, indicating that this procedure successfully improved voice in unilateral vocal fold paralysis. Peak inspiratory flow decreased significantly as a consequence of this procedure (from 4.54 ± 1.68 l to 4.21 ± 1.26 l, p = 0.03, in pooled data of both cohorts), but no change occurred in the other variables of flow-volume spirometry, body-plethysmography and impulse oscillometry. Eight of the ten patients studied by acoustic analysis of breathing had wheezes after vocal fold medialization compared with only three patients before the procedure, and the numbers of wheezes per recorded inspirium and expirium increased significantly (from 0.02 to 0.42 and from 0.03 to 0.36; p = 0.028 and p = 0.043, respectively). In conclusion, unilateral vocal fold paralysis was observed to disturb forced breathing and also to cause some signs of disturbed tidal breathing. Findings of flow volume spirometry were consistent with variable extra-thoracic obstruction. Vocal fold medialization by autologous fascia injection improved the quality of the voice in patients with unilateral vocal fold paralysis, but also decreased peak inspiratory flow and induced wheezing during tidal breathing. However, these airflow changes did not appear to cause significant symptoms in patients.
  • Saaristo, Minna (Helsingin yliopisto, 2009)
    In aquatic environments, endocrine disrupting chemicals (EDCs) that interfere with the endocrinology of males and females form a threat to the maintenance of populations. EDCs are a diverse group of natural and manmade chemicals that already at very low concentrations (at nanogram levels) can have severe effects on reproduction by individuals, e.g. complete sex reversal, feminisation of males, impaired reproduction even resulting in near extinction of populations. With regard to fish, despite the extensive literature on physiological effects of EDCs, very little is known about potential population-level effects. In this thesis, I examined how 17α-ethinyl estradiol (EE2), a synthetic estrogen used in oral contraceptive pills, affects the reproductive behaviour of a marine fish, the sand goby (Pomatoschistus minutus). The aims were fourfold. First, I investigated how exposure to EE2 affects courtship and parental care of sand goby males. Secondly, I looked at effects on the mating system and sexual selection. In the third study, I observed the effects of exposure in a social context where exposed males had to compete with non-exposed males for resources and mates. Finally, I studied the effects of exposure on male-male competition and male aggressive behaviour. This work revealed that EE2 exposure impairs the ability of males to acquire and defend a nest, as well as diminishes the attractiveness of males to females by decreasing their courtship and aggressive behaviour. These effects are harmful for a male whose reproductive success is determined by the ability to compete for limited resources and to attract mates. Furthermore, this thesis showed that selection on male size was relaxed after EE2 exposure and male size had a smaller effect on mating success. These effects can be of a profound nature as they interfere with sexual selection, and may in the long run lead to the loss of traits maintained through sexual selection. The thesis shows that an exposure to environmentally relevant levels of EE2 clearly reduces the chances of individuals to reproduce successfully. Furthermore, it strongly suggests that several types of biomarkers should be used to detect and assess the effects of EDC exposure because severe behavioural effects can sometimes be seen before effects are detectable at the molecular or morphometric level. Behavioural assays should be considered an important complementary tool for the standard ecotoxicological assays because observed behavioural changes have direct and negative effects on fitness, while the connection between changes in molecular expression and fitness may be less obvious.
  • Henriksson, Britta (2001)
    Aminoglykosid- och b-laktamkombinationer har använts för behandling av mastiter ända sedan 1960-talet. Den teoretiska grunden för användningen har varit bredspektrighet, undvikande av uppkomst av resistenta bakteriestammar, samt en allmänt utbredd uppfattning att dessa kombinationer utövar synergism mot vissa grampositiva mastitförorsakande bakterier. Det saknas dock sådana kliniska försöksrapporter, som entydigt skulle visa att dessa kombinationer skulle ge något avsevärt bättre behandlingsresultat vid behandling av mastit hos mjölkkor. Till de viktigaste problemen som användningen av dessa produkter för med sig, förutom frågan huruvida de alls är effektivare än enbart penicillin, hör aminoglykosidernas förmåga att koncentrera sig i vävnaderna och speciellt då njurarna, vilket kan ge upphov till förlångsammad eliminering och möjligen läkemedelsrester i nötlivsmedel. Dessutom finns vissa indicier om att användning av kombinationspreparat, speciellt då tillräckligt höga koncentrationer vid bakteriehärden har visat sig svåra att uppnå, kan leda till ökad antibiotikaresistens. Målet med detta projekt var att jämföra resultatet av behandling med enbart penicillin (behandling A) med kombinationsterapi med penicillin G - neomycin (behandling B) vid klinisk mastit under mjölkningsperioden hos nöt, då inflammationen orsakas av grampositiva juverpatogener (KNS, Staphylococcus aureus, streptokocker). Som tilläggsmaterial undersöktes tillfrisknandet av mastiter förorsakade av penicillinasproducerande stafylokocker vid behandling med kloxacillin (behandling K). I försöket deltog sammanlagt 127 kor och 157 juverfjärdedelar behandlade för mastit på praktikområdet för Helsingfors universitets veterinärmedicinska fakultets ambulatoriska klinik i Saari under åren 1999-2000, samt mastiter behandlade av de kommunalveterinärer som medverkade i försöket. Av dessa behandlades 64 fjärdedelar med preparat A, 74 med preparat B och 19 med preparat K. Försöket utfördes som dubbelblindförsök. De medverkande korna behandlades med en injektion prokainpenicillin första behandlingsdagen samt en infusion av ettdera behandlingspreparat A, B eller K intramammart i varje sjuk juverdel i fyra dagar. Tillfrisknandet kontrollerades kliniskt och bakteriologiskt efter 3-4 veckor, därtill undersöktes även inflammationsindikatorn NAGas i kontrollmjölkprovet. Som kriterier för tillfrisknandet användes ett negativt bakterieresultat i kontrollprovet, NAGas-värden under 40 U, samt den kliniska bedömningen av tillfrisknandet, inkluderande CMT-test. Bakteriologiskt tillfrisknade 68 % av alla mastiter behandlade med preparat A. För preparat B var motsvarande siffra 68 % och för preparat K 53 % De kliniska tillfriskningsprocenterna var 77 % för preparat A, 73 % för preparat B och 58 %för preparat K. Då behandlingsresultaten mellan grupp A och B jämförs, kan konstateras att ingen statistisk skillnad föreligger mellan behandling med enbart penicillin och behandling med kombinationspreparat med penicillin och neomycin. Detta gäller även då de olika bakteriestammarna betraktas skilt. På basen av detta försök ger en tillsats av neomycin i intramammarier vid behandling av mastiter förorsakade av penicillinkänsliga bakteriestammar ingen fördel gentemot behandling med enbart penicillin.
  • Gabrielsson, Beata (2000)
    I detta pro gradu arbete behandlas effektivt teamarbete ur ett externt perspektiv (Ancona 1987). Det externa perspektivet fokuserar på centrala och komplexa relationer som uppstår mellan ett team och dess omgivning. Forskningsintresset är fokuserat på hur en organisation påverkar gruppen samt på hur gruppen påverkar organisationen. Enligt det externa perspektivet påverkas teamarbetets effektivitet av hur ett team reglerar sin interaktion med omgivningen. Därmed är det viktigt att ett team kan styra sin interaktion med sin omgivningen på ett effektivt sätt. Den teoretiska referensramen utgår ifrån Sundströms, De Meuses och Futrells omfattande modell (1990). Modellen behandlar den organisatoriska kontexten, teamets inre gruppdynamik och teamets s.k. gränser. Gränserna styr och reglerar den interaktion som sker mellan den organisatoriska kontexten och teamets medlemmar. Alla dessa tre komponenter -kontexten, gränserna och teamet- anses påverka teamarbetets effektivitet. I detta pro gradu arbete står gränserna, som styr ett teams interaktion med omgivningen, i fokus för intresset. Sundströms, De Meuses och Futrells modell kompletteras av Anconas och Caldwells (1990a, 1990b, 1992) studier om effektiv reglering av interaktion. Den empiriska delen i pro gradu arbetet utfördes som en enkel omslutande fallstudie. Forskningsmaterialet bestod av nitton intervjuer, organisationens egna effektivitetsmätare samt av andra relevanta dokument. Syftet med undersökningen var att undersöka hur två team reglerar sin interaktion med omgivningen samt om det existerar ett samband mellan interaktionen och teamarbetets effektivitet. Detta gjordes utgående från den teoretiska referensramen, som klart styrde undersökningens struktur. Efter datainsamlingen analyserades materialet. På basen av analysen och med stöd av referensramen, gjordes antaganden om de undersökta teamens effektivitet. Därefter jämfördes undersökningens resultat med organisationens egna effektivitetsmätare. Effektivitetsmätarna gav stöd för den egna undersökningen. Därmed ser det ut att existera ett samband mellan aktiv interaktion och effektivt teamarbete.
  • Knuutila, Antti (Helsingin yliopisto, 2012)
    Brains are capable of processing information with remarkable efficiency under constraints set by the limited supply of physical resources such as the amount of space and the availability of metabolic energy. Natural selection has optimised the structure and function of brain networks using simple design rules similar to those found in man-made electronic and information systems. This study presents findings concerning a number of general principles of brain design governing the evolution and organisation of neural information processing. The rule of minimising wiring in neuronal networks is one such principle operating on multiple levels of brain organisation. Both individual components and larger brain architectural units are seen to feature characteristics of near-optimal wiring. Miniaturisation of neuronal components conserves space but raises problems about noise in signalling. Small-world organisation of anatomical and functional networks is widely employed in the brain, contributing to high global efficiency at low cost. Metabolic costs severely constrain signal traffic in the human brain, necessitating the use of energy-efficient sparse neural representations. Extensive evidence is presented of anatomical and physiological optimisations facilitating efficient information processing in brain networks. Limitations of current experimental techniques are discussed, with a view on possible future avenues of research.
  • Tarkoma, Sasu (Helsingin yliopisto, 2006)
    Event-based systems are seen as good candidates for supporting distributed applications in dynamic and ubiquitous environments because they support decoupled and asynchronous many-to-many information dissemination. Event systems are widely used, because asynchronous messaging provides a flexible alternative to RPC (Remote Procedure Call). They are typically implemented using an overlay network of routers. A content-based router forwards event messages based on filters that are installed by subscribers and other routers. The filters are organized into a routing table in order to forward incoming events to proper subscribers and neighbouring routers. This thesis addresses the optimization of content-based routing tables organized using the covering relation and presents novel data structures and configurations for improving local and distributed operation. Data structures are needed for organizing filters into a routing table that supports efficient matching and runtime operation. We present novel results on dynamic filter merging and the integration of filter merging with content-based routing tables. In addition, the thesis examines the cost of client mobility using different protocols and routing topologies. We also present a new matching technique called temporal subspace matching. The technique combines two new features. The first feature, temporal operation, supports notifications, or content profiles, that persist in time. The second feature, subspace matching, allows more expressive semantics, because notifications may contain intervals and be defined as subspaces of the content space. We also present an application of temporal subspace matching pertaining to metadata-based continuous collection and object tracking.
  • Gurtov, Andrei (Helsingin yliopisto, 2004)
  • Hämäläinen, Wilhelmiina (Helsingin yliopisto, 2010)
    Analyzing statistical dependencies is a fundamental problem in all empirical science. Dependencies help us understand causes and effects, create new scientific theories, and invent cures to problems. Nowadays, large amounts of data is available, but efficient computational tools for analyzing the data are missing. In this research, we develop efficient algorithms for a commonly occurring search problem - searching for the statistically most significant dependency rules in binary data. We consider dependency rules of the form X->A or X->not A, where X is a set of positive-valued attributes and A is a single attribute. Such rules describe which factors either increase or decrease the probability of the consequent A. A classical example are genetic and environmental factors, which can either cause or prevent a disease. The emphasis in this research is that the discovered dependencies should be genuine - i.e. they should also hold in future data. This is an important distinction from the traditional association rules, which - in spite of their name and a similar appearance to dependency rules - do not necessarily represent statistical dependencies at all or represent only spurious connections, which occur by chance. Therefore, the principal objective is to search for the rules with statistical significance measures. Another important objective is to search for only non-redundant rules, which express the real causes of dependence, without any occasional extra factors. The extra factors do not add any new information on the dependence, but can only blur it and make it less accurate in future data. The problem is computationally very demanding, because the number of all possible rules increases exponentially with the number of attributes. In addition, neither the statistical dependency nor the statistical significance are monotonic properties, which means that the traditional pruning techniques do not work. As a solution, we first derive the mathematical basis for pruning the search space with any well-behaving statistical significance measures. The mathematical theory is complemented by a new algorithmic invention, which enables an efficient search without any heuristic restrictions. The resulting algorithm can be used to search for both positive and negative dependencies with any commonly used statistical measures, like Fisher's exact test, the chi-squared measure, mutual information, and z scores. According to our experiments, the algorithm is well-scalable, especially with Fisher's exact test. It can easily handle even the densest data sets with 10000-20000 attributes. Still, the results are globally optimal, which is a remarkable improvement over the existing solutions. In practice, this means that the user does not have to worry whether the dependencies hold in future data or if the data still contains better, but undiscovered dependencies.
  • Raatikainen, Marko (2013)
    Regulations for medical device software require that some of the tools used in development are validated. This thesis takes a look at how the tool validation is done in GE Healthcare. Guidelines for more efficient tool validation are presented and tested out in practice. Final version of the guidelines are evaluated by 9 experts. According to the experts the initial validation done by following the guidelines will be somewhat faster, and subsequent validations will be significantly faster. However, the guidelines take advantage of automation, including automation of tests. More time is required, if the tools are unfamiliar, or if the tool being validated is not easy to test automatically.
  • Auruksenaho, Liisa (Helsingin yliopisto, 2005)
    Tutkielma on kaksivaiheinen. Ensin esittelen apostolisen, Syyrialaisortodoksisen kirkon historiaa ja luostariperinnettä. Toisen osan tarkoitus on selvittää, liittyykö Pyhän Efraim Syyrialaisen luostarin munkkien luostariinjäämispäätökseen yhteiskunnallisia syitä ja mitä muita mahdollisia syitä voidaan löytää. Vertailen lopuksi varhaisia, 400-luvulla eläneiden kilvoittelijoiden Pyhän Efraim Syyrialaisen, Antonius Suuren ja Simeon Pylväspyhimyksen motiiveita nykykilvoittelijoiden motiiveihin, sikäli kuin se on mahdollista. Selvitän myös, onko Efraim Syyrialaisen esimerkillä ollut merkitystä nykykilvoittelijoille. Empiirinen aineisto kerättiin kahtena vuotena v. 2002 ja 2003. Tutkielmaa varten haastattelin kolmea Efraim Syyrialaisen luostarin munkkia. Pääinformanttini oli ko. luostarin seminaarin teologiopiskelija. Heidän kotitaustansa on syyrialaisortodoksinen, voimakkaasti uskonnollinen. Spiritualiteettia harjoitettiin jo lapsuudessa sekä kotona että kirkossa. Tutkielmani näkökulma on uskontohistoriallinen ja uskontososiologinen. Tutkin miten varhaiset- sekä nykypäivän kilvoittelijat ovat suhtautuneet yhteiskuntaan ja miten he ovat integroituneet luostariinsa. Kysymyksessä on nykypäivän osalta laadullinen tapaustutkimus, jonka metodeina ovat teemahaastattelu, jonka yhtenä osana olivat argumentit ja osallistruva havainnointi. Analysoin vastaukset sisällön analyysiä käyttäen. Haastatellut munkit korostivat syyrian kielen ja tradition opiskelun ja sen siirtämisen tärkeyttä seminaariin opiskelemaan hakeutumisensa, ja sen jälkeen munkiksi jäämisensä perusteluna. Pyhän Efraim Syyrialaisen esimerkin munkit kokivat olevan heille hyvin tärkeän tradition siirtäjän. Opiskelemisen ja matkustamisen mahdollisuus munkkina koettiin myös tärkeänä ja siitä syystä luostariin jäätiin, eli yhteiskunnallinen syy löytyi. Sisällön analyysissä ilmeni, että alkujaan koti edusti munkille primaarista tekijää. Sekundääristä tekijää edustivat kirkkoon kuuluva ryhmä, munkit ja luostari. Kodin ja kirkossa käynnin seurauksena tradition ja syyrian kielen oppimisen halu korostui ja niitä haluttiin lähteä opiskelemaan. Positiiviseksi viiteryhmäksi tällöin muodostuivat seminaariopiskelun aikana munkit ja muut luostarin asukkaat. Luostariin jäämisensä jälkeen primaarin tekijän voidaan huomata vaihtuneen luostariksi ja kodin asema on jäänyt sekundaariseksi. Yhteys luostarin ja ympäröivän yhteiskunnan kanssa tapahtui varhaisena aikana pääasiallisesti siten, että ihmiset tulivat kilvoittelijan luokse. Nykymunkit puolestaan käyvät niiden seurakuntalaisten kotona, jotka eivät pääse yhteisiin jumalanpalveluksiin ja auttavat heitä sielunhoidollisesti ja tarvittaessa taloudellisesti. Kirkon patriarkka Mar Ignatios Zakka I Iwasilla ja metropoliitta Eusthatios Matta Rohamilla on paljon yhteyksiä myös islaminuskoiseen väestönosaa Syyriassa. Ekumeenisia yhteyksiä on munkeillakin runsaasti. Ne mahdollistuvat erilaisissa kirkon kokouksissa ja konferensseissa sekä opiskelupaikkakunnalla Kreikassa.