6 resultados para Few-body systems
em Helda - Digital Repository of University of Helsinki
Resumo:
During the past ten years, large-scale transcript analysis using microarrays has become a powerful tool to identify and predict functions for new genes. It allows simultaneous monitoring of the expression of thousands of genes and has become a routinely used tool in laboratories worldwide. Microarray analysis will, together with other functional genomics tools, take us closer to understanding the functions of all genes in genomes of living organisms. Flower development is a genetically regulated process which has mostly been studied in the traditional model species Arabidopsis thaliana, Antirrhinum majus and Petunia hybrida. The molecular mechanisms behind flower development in them are partly applicable in other plant systems. However, not all biological phenomena can be approached with just a few model systems. In order to understand and apply the knowledge to ecologically and economically important plants, other species also need to be studied. Sequencing of 17 000 ESTs from nine different cDNA libraries of the ornamental plant Gerbera hybrida made it possible to construct a cDNA microarray with 9000 probes. The probes of the microarray represent all different ESTs in the database. From the gerbera ESTs 20% were unique to gerbera while 373 were specific to the Asteraceae family of flowering plants. Gerbera has composite inflorescences with three different types of flowers that vary from each other morphologically. The marginal ray flowers are large, often pigmented and female, while the central disc flowers are smaller and more radially symmetrical perfect flowers. Intermediate trans flowers are similar to ray flowers but smaller in size. This feature together with the molecular tools applied to gerbera, make gerbera a unique system in comparison to the common model plants with only a single kind of flowers in their inflorescence. In the first part of this thesis, conditions for gerbera microarray analysis were optimised including experimental design, sample preparation and hybridization, as well as data analysis and verification. Moreover, in the first study, the flower and flower organ-specific genes were identified. After the reliability and reproducibility of the method were confirmed, the microarrays were utilized to investigate transcriptional differences between ray and disc flowers. This study revealed novel information about the morphological development as well as the transcriptional regulation of early stages of development in various flower types of gerbera. The most interesting finding was differential expression of MADS-box genes, suggesting the existence of flower type-specific regulatory complexes in the specification of different types of flowers. The gerbera microarray was further used to profile changes in expression during petal development. Gerbera ray flower petals are large, which makes them an ideal model to study organogenesis. Six different stages were compared and specifically analysed. Expression profiles of genes related to cell structure and growth implied that during stage two, cells divide, a process which is marked by expression of histones, cyclins and tubulins. Stage 4 was found to be a transition stage between cell division and expansion and by stage 6 cells had stopped division and instead underwent expansion. Interestingly, at the last analysed stage, stage 9, when cells did not grow any more, the highest number of upregulated genes was detected. The gerbera microarray is a fully-functioning tool for large-scale studies of flower development and correlation with real-time RT-PCR results show that it is also highly sensitive and reliable. Gene expression data presented here will be a source for gene expression mining or marker gene discovery in the future studies that will be performed in the Gerbera Laboratory. The publicly available data will also serve the plant research community world-wide.
Resumo:
In Finland, suckler cow production is carried out in circumstances characterized by a long winter period and a short grazing period. The traditional winter housing system for suckler cows has been insulated or uninsulated buildings, but there is a demand for developing less expensive housing systems. In addition, more information is needed on new winter feeding strategies, carried out in inexpensive winter facilities with conventional (hay, grass silage, straw) or alternative (treated straw, industrial by-product, whole-crop silage) feeds. The new feeding techniques should not have any detrimental effects on animal welfare in order to be acceptable to both farmers and consumers. Furthermore, no official feeding recommendations for suckler cows are available in Finland and, thus, recommendations for dairy cows have been used. However, this may lead to over- or underfeeding of suckler cows and, finally, to decreased economic output. In Experiment I, second-calf beef-dairy suckler cows were used to compare the effects of diets based on hay (H) or urea-treated straw (US) at two feeding levels (Moderate; M vs. Low; L) on the performance of cows and calves. Live weight (LW) gain during the indoor feeding was lower for cows on level L than on level M. Cows on diet US lost more LW indoors than those on diet H. The cows replenished the LW losses on good pasture. Calf LW gain and cow milk production were unaffected by the treatments. Conception rate was unaffected by the treatments but was only 69%. Urea-treated straw proved to be a suitable winter feed for spring-calving suckler cows. Experiment II studied the effects of feeding accuracy on the performance of first- and second-calf beef-dairy cows and calves. In II-1, the day-to-day variation in the roughage offered ranged up to ± 40%. In II-2, the same variation was used in two-week periods. Variation of the roughages offered had minor effects on cow performance. Reproduction was unaffected by the feeding accuracy. Accurate feeding is not necessary for young beef-dairy crosses, if the total amount of energy offered over a period of a few weeks fulfills the energy requirements. Effects of feeding strategies with alternative feeds on the performance of mature beef-dairy and beef cows and calves were evaluated in Experiment III. Two studies consisted of two feeding strategies (Step-up vs. Flat-rate) and two diets (Control vs. Alternative). There were no differences between treatments in the cow LW, body condition score (BCS), calf pre-weaning LW gain and cow reproduction. A flat-rate strategy can be practised in the nutrition of mature suckler cows. Oat hull based flour-mill by product can partly replace grass silage and straw in the winter diet. Whole-crop barley silage can be offered as a sole feed to suckler cows. Experiment IV evaluated during the winter feeding period the effects of replacing grass silage with whole-crop barley or oat silage on mature beef cow and calf performance. Both whole-crop silages were suitable winter feeds for suckler cows in cold outdoor winter conditions. Experiment V aimed at assessing the effects of daily feeding vs. feeding every third day on the performance of mature beef cows and calves. No differences between the treatments were observed in cow LW, BCS, milk production and calf LW. The serum concentrations of urea and long-chain fatty acids were increased on the third day after feeding in the cows fed every third day. Despite of that the feeding every third day is an acceptable feeding strategy for mature suckler cows. Experiment VI studied the effects of feeding levels and long-term cold climatic conditions on mature beef cows and calves. The cows were overwintered in outdoor facilities or in an uninsulated indoor facility. Whole-crop barley silage was offered either ad libitum or restricted. All the facilities offered adequate shelter for the cows. The restricted offering of whole-crop barley silage provided enough energy for the cows. The Finnish energy recommendations for dairy cows were too high for mature beef breed suckler cows in good body condition at housing, even in cold conditions. Therefore, there is need to determine feeding recommendations for suckler cows in Finland. The results showed that the required amount of energy can be offered to the cows using conventional or alternative feeds provided at a lower feeding level, with an inaccurate feeding, flat-rate feeding or feeding every third day strategy. The cows must have an opportunity to replenish the LW and BCS losses at pasture before the next winter. Production in cold conditions can be practised in inexpensive facilities when shelter against rain and wind, a dry resting place, adequate amounts of feed suitable for cold conditions and water are provided for the animals as was done in the present study.
Resumo:
It has been hypothesized that abuse of supra-therapeutic doses of anabolic androgenic steroids (AASs) can lead to dependence and function as a gateway to abuse of other drugs. This is supported by behavioral studies on animal models and psychiatric evaluations of human subjects, although their neurochemical effects remain largely unknown. A large body of evidence suggests that the ability of the drugs to induce a strong elevation of extracellular dopamine (DA) levels in the nucleus accumbens (NAc), especially, plays a crucial role in their reinforcing effects. -- This study had four main aims. The first was to explore the effects of nandrolone decanoate on dopaminergic and serotonergic activities in the brains of rats. The second aim was to assess whether or not nandrolone pre-exposure modulates the acute neurochemical and behavioral effects of psychostimulant drugs in experimental animals. The third was to investigate if the AAS-pre-treatment induced changes in brain reward circuitry are reversible. And the fourth main goal was to evaluate the role of androgen and estrogen receptors in the modulation of the dopaminergic and serotonergic effects of acute injections of stimulant drugs by sub-chronic nandrolone treatment. The results showed that nandrolone decanoate at doses, high enough to induce erythropoiesis, significantly increased the levels of DOPAC and 5-HT in the cerebral cortex. Co-administration of AAS and psychostimulant drugs showed that the increase in extracellular DA and 5-HT concentration evoked by amphetamine, MDMA and cocaine in the NAc was attenuated dose-dependently by pretreatment with nandrolone. Nandrolone pre-exposure also attenuated the ability of stimulants to cause increased stereotyped behavior and locomotor activity. Despite the significant decrease in nandrolone concentration in blood, the attenuation of cocaine’s effects remained unchanged after a fairly long period without nandrolone, suggesting that nandrolone effects could be long lasting. Blockade of androgen receptors with flutamide abolished the attenuating effect of nandrolone pretreatment on amphetamine-induced elevation of extracellular DA concentration. --- In conclusion, the results show that AAS-pretreatment is able to inhibit the reward-related neurochemical and behavioral effects of amphetamine, MDMA and cocaine in experimental animals. Furthermore, it seems that these effects could be long lasting and it appears that the ability of nandrolone to modulate reward-related effects of stimulants is dependent on activation of androgen receptors.
Resumo:
Agriculture is an economic activity that heavily relies on the availability of natural resources. Through its role in food production agriculture is a major factor affecting public welfare and health, and its indirect contribution to gross domestic product and employment is significant. Agriculture also contributes to numerous ecosystem services through management of rural areas. However, the environmental impact of agriculture is considerable and reaches far beyond the agroecosystems. The questions related to farming for food production are, thus, manifold and of great public concern. Improving environmental performance of agriculture and sustainability of food production, sustainabilizing food production, calls for application of wide range of expertise knowledge. This study falls within the field of agro-ecology, with interphases to food systems and sustainability research and exploits the methods typical of industrial ecology. The research in these fields extends from multidisciplinary to interdisciplinary and transdisciplinary, a holistic approach being the key tenet. The methods of industrial ecology have been applied extensively to explore the interaction between human economic activity and resource use. Specifically, the material flow approach (MFA) has established its position through application of systematic environmental and economic accounting statistics. However, very few studies have applied MFA specifically to agriculture. The MFA approach was used in this thesis in such a context in Finland. The focus of this study is the ecological sustainability of primary production. The aim was to explore the possibilities of assessing ecological sustainability of agriculture by using two different approaches. In the first approach the MFA-methods from industrial ecology were applied to agriculture, whereas the other is based on the food consumption scenarios. The two approaches were used in order to capture some of the impacts of dietary changes and of changes in production mode on the environment. The methods were applied at levels ranging from national to sector and local levels. Through the supply-demand approach, the viewpoint changed between that of food production to that of food consumption. The main data sources were official statistics complemented with published research results and expertise appraisals. MFA approach was used to define the system boundaries, to quantify the material flows and to construct eco-efficiency indicators for agriculture. The results were further elaborated for an input-output model that was used to analyse the food flux in Finland and to determine its relationship to the economy-wide physical and monetary flows. The methods based on food consumption scenarios were applied at regional and local level for assessing feasibility and environmental impacts of relocalising food production. The approach was also used for quantification and source allocation of greenhouse gas (GHG) emissions of primary production. GHG assessment provided, thus, a means of crosschecking the results obtained by using the two different approaches. MFA data as such or expressed as eco-efficiency indicators, are useful in describing the overall development. However, the data are not sufficiently detailed for identifying the hot spots of environmental sustainability. Eco-efficiency indicators should not be bluntly used in environmental assessment: the carrying capacity of the nature, the potential exhaustion of non-renewable natural resources and the possible rebound effect need also to be accounted for when striving towards improved eco-efficiency. The input-output model is suitable for nationwide economy analyses and it shows the distribution of monetary and material flows among the various sectors. Environmental impact can be captured only at a very general level in terms of total material requirement, gaseous emissions, energy consumption and agricultural land use. Improving environmental performance of food production requires more detailed and more local information. The approach based on food consumption scenarios can be applied at regional or local scales. Based on various diet options the method accounts for the feasibility of re-localising food production and environmental impacts of such re-localisation in terms of nutrient balances, gaseous emissions, agricultural energy consumption, agricultural land use and diversity of crop cultivation. The approach is applicable anywhere, but the calculation parameters need to be adjusted so as to comply with the specific circumstances. The food consumption scenario approach, thus, pays attention to the variability of production circumstances, and may provide some environmental information that is locally relevant. The approaches based on the input-output model and on food consumption scenarios represent small steps towards more holistic systemic thinking. However, neither one alone nor the two together provide sufficient information for sustainabilizing food production. Environmental performance of food production should be assessed together with the other criteria of sustainable food provisioning. This requires evaluation and integration of research results from many different disciplines in the context of a specified geographic area. Foodshed area that comprises both the rural hinterlands of food production and the population centres of food consumption is suggested to represent a suitable areal extent for such research. Finding a balance between the various aspects of sustainability is a matter of optimal trade-off. The balance cannot be universally determined, but the assessment methods and the actual measures depend on what the bottlenecks of sustainability are in the area concerned. These have to be agreed upon among the actors of the area
Resumo:
Triggered by the very quick proliferation of Internet connectivity, electronic document management (EDM) systems are now rapidly being adopted for managing the documentation that is produced and exchanged in construction projects. Nevertheless there are still substantial barriers to the efficient use of such systems, mainly of a psychological nature and related to insufficient training. This paper presents the results of empirical studies carried out during 2002 concerning the current usage of EDM systems in the Finnish construction industry. The studies employed three different methods in order to provide a multifaceted view of the problem area, both on the industry and individual project level. In order to provide an accurate measurement of overall usage volume in the industry as a whole telephone interviews with key personnel from 100 randomly chosen construction projects were conducted. The interviews showed that while around 1/3 of big projects already have adopted the use of EDM, very few small projects have adopted this technology. The barriers to introduction were investigated through interviews with representatives for half a dozen of providers of systems and ASP-services. These interviews shed a lot of light on the dynamics of the market for this type of services and illustrated the diversity of business strategies adopted by vendors. In the final study log files from a project which had used an EDM system were analysed in order to determine usage patterns. The results illustrated that use is yet incomplete in coverage and that only a part of the individuals involved in the project used the system efficiently, either as information producers or consumers. The study also provided feedback on the usefulness of the log files.
Resumo:
The dissertation examines the foreign policies of the United States through the prism of science and technology. In the focal point of scrutiny is the policy establishing the International Institute for Applied Systems Analysis (IIASA) and the development of the multilateral part of bridge building in American foreign policy during the 1960s and early 1970s. After a long and arduous negotiation process, the institute was finally established by twelve national member organizations from the following countries: Bulgaria, Canada, Czechoslovakia, Federal Republic of Germany (FRG), France, German Democratic Republic (GDR), Great Britain, Italy, Japan, Poland, Soviet Union and United States; a few years later Sweden, Finland and the Netherlands also joined. It is said that the goal of the institute was to bring together researchers from East and West to solve pertinent problems caused by the modernization process experienced in industrialized world. It originates from President Lyndon B. Johnson s bridge building policies that were launched in 1964, and was set in a well-contested and crowded domain of other international organizations of environmental and social planning. Since the distinct need for yet another organization was not evident, the process of negotiations in this multinational environment enlightens the foreign policy ambitions of the United States on the road to the Cold War détente. The study places this project within its political era, and juxtaposes it with other international organizations, especially that of the OECD, ECE and NATO. Conventionally, Lyndon Johnson s bridge building policies have been seen as a means to normalize its international relations bilaterally with different East European countries, and the multilateral dimension of the policy has been ignored. This is why IIASA s establishment process in this multilateral environment brings forth new information on US foreign policy goals, the means to achieve these goals, as well as its relations to other advanced industrialized societies before the time of détente, during the 1960s and early 1970s. Furthermore, the substance of the institute applied systems analysis illuminates the differences between European and American methodological thinking in social planning. Systems analysis is closely associated with (American) science and technology policies of the 1960s, especially in its military administrative applications, thus analysis within the foreign policy environment of the United States proved particularly fruitful. In the 1960s the institutional structures of European continent with faltering, and the growing tendencies of integration were in flux. One example of this was the long, drawn-out process of British membership in the EEC, another is de Gaulle s withdrawal from NATO s military-political cooperation. On the other hand, however, economic cooperation in Europe between East and West, and especially with the Soviet Union was expanding rapidly. This American initiative to form a new institutional actor has to be seen in that structural context, showing that bridge building was needed not only to the East, but also to the West. The narrative amounts to an analysis of how the United States managed both cooperation and conflict in its hegemonic aspirations in the emerging modern world, and how it used its special relationship with the United Kingdom to achieve its goals. The research is based on the archives of the United States, Great Britain, Sweden, Finland, and IIASA. The primary sources have been complemented with both contemporary and present day research literature, periodicals, and interviews.