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No description available.

No description available.

No description available.

Growth, mortality, production, spat collection, seasonal cycles of condition index, biochemical composition, carrying capacity of commercial raft culture systems and population genetic characteristics of blue mussel (Mytilus edulis) were studied at different sites in Loch Etive and Loch Kishorn on the west coast of Scotland between May 1993 and May 1995. The main objective of the study was to evaluate current suspended mussel culture production in raft systems and to obtain basic information on the biology and the genetic structure of the two mussel populations in the lochs. There were some water quality differences between the sites in relation to seston, salinity and transparency but not to temperature, particulate organic matter and chlorophylla. When food is available (as particulate organic matter and chlorophyll-a), there was a clear seasonal cycle in mussel somatic growth and shell growth. Mussel growth was relatively high from mid-spring until late autumn, but very slow during the rest of the year. The spring-summer period of rapid shell length and somatic growth coincided with relatively optimum environmental conditions and positive relationships were indicated between growth rates, temperature and salinity, indicating the limiting effect of these two primary factors on growth from late-autumn to mid-spring when there is also a lack of available food. Mussel growth was higher at 2m depth on the raft-rope systems, but in lantern nets experimental growth did not show differences between depths. Growth was found to be similar in the lantern nets and on culture ropes in the two lochs in the first year of experiments (from May 1993 to May 1994). Overall, mean length increments were 31.01mm in Loch Etive and 28.75mm in Loch Kishorn over a 15 month period. The mussels reached marketable size (>50mm) in two years from the known time of spat settlement. A cross-transplantation experiment showed that site rather than stock is the main factor explaining differences in mussel growth in Loch Etive and Loch Kishorn. The position of the mussels within a raft has a significant effect on their growth; mussels at the inflow of a raft have a better growth than those near the outflow (p<0.05) due to greater availability of food. Mean mussel biomass was higher in Loch Kishorn while production was higher in Loch Etive, but there were seasonal and monthly fluctuations in both biomass and production at both sites. Biochemical composition and energy content were similar in both sites, while mussel meat yield and condition indices were significantly higher in Loch Kishom than Loch Etive. Meat content, condition index and carbohydrate values were high during the summer and low from autumn to spring, reaching minimum values in March and April at the time of spawning. Spat settlement occurred in June-July in Loch Etive and June-December in Loch Kishorn. Sea squirt, starfish and eider duck are problems effecting spat collection at the Loch Kishorn site, whereas spat collection in Loch Etive is unaffected by these pests/predators. The carrying capacities for cultured mussels were found to be about 24 metric tons per raft for Loch Etive and 38 metric tons per raft for Loch Kishorn using a particulate organic matter based model; these are reasonable estimates in comparison to the known mussel production levels reported by producers. However, a seston-based model gave an overestimate of carrying capacity for both sites. Cross-transplantation of mussels, electrophoresis and shell morphological measurements showed significant differences between the Loch Etive and Loch Kishorn mussel populations. Mortality rates were higher in transplanted mussels than in the native mussels (p<0.001).

Since the 1990s the use of the Internet and electronic commerce (e-commerce) has exploded, yet few SMEs seem to benefit from its potential. The lack of personal involvement and low level of use are an indication that managers still have not committed themselves to e-commerce. Consequently they are not reaping the full benefits first hand. The objectives of the study are to identify key factors and relationships likely to influence e-commerce use by SME managers in the Netherlands and to investigate whether relevant and significant factors can be combined in a new model to predict how SME managers will use new technology. To achieve these objectives, a well-established model of IT usage behaviour, the Technology Acceptance Model (TAM), was used. Building upon TAM, a theoretical research model was developed to investigate a large number of external variables that are possible antecedents of managerial beliefs, attitudes, and the use of IT. E-commerce systems were chosen as the IT tool under review. A cross-sectional field survey was conducted to investigate the theoretical research model. The results are based on the analysis of questionnaire data from 114 managers from Dutch SMEs. Using Structural Equation Modelling (SEM) the results show significant support for external variables, mostly of an individual nature, in the categories of demographics, managerial and IT knowledge, individual characteristics, and company characteristics. Contrary to expectations, two categories - social factors and environmental characteristics - had few or no variables with a significant relationship. This study further presents empirical evidence to suggest a limited number of antecedents under managerial control influencing beliefs, attitudes, and use. A better understanding of the various factors that may impede or increase effective utilization of IT can facilitate the design of organizational or managerial interventions that address these issues. Building on the core TAM model a new model, the e-Tam Model, has been developed based on the results of the theoretical research model. In this model, it is hypothesized that IT usage is directly and indirectly influenced by seven external variables divided into three categories: demographics, personality, and company characteristics. Using the e-Tam Model, effective and increased use of managerial IT tools can be promoted. This will enable managers to have a better use of e-commerce systems leading in turn to better margins and opportunities.

Throughout the early twentieth century, dengue fever was considered to be a nonthreatening illness, only infecting visitors of the tropics. However, in the last fifty years, there has been a resurgence of dengue fever; it is now considered to be the most consequential arbovirus, infecting more than 50 million people each year and leaving about half of the world's current population at risk of infection. The purpose of this thesis is to explore the various environmental factors that have contributed to the resurgence of dengue fever that has been seen in the last half century. Most notable of these factors are climate change and the increasing urbanization associated with population growth. Specifically, increasing temperatures and precipitation increases the available habitat for the dengue fever vector, the Aedes mosquito, while concurrently increasing both the longevity of the virus and the mosquito. Furthermore, changing sociodemographic factors associated with urbanization have helped spread the mosquito around the world, as the vector largely relies on human transportation. Finally, substandard housing often associated with insufficient water management systems creates the ideal breeding spots for the dengue vector. The Aedes mosquito is known to be one of the most versatile and one of the toughest mosquitoes in the world, which has allowed it to quickly adapt and succeed in these changing environments. Understanding these factors and their influence on the spread of dengue fever is vital in order to effectively manage current and future outbreaks. This is specifically important in regards to dengue fever and severe dengue as no vaccine or medications currently exists to treat this virus.

Signal extraction in tree-ring research is considered as a general time series decomposition problem. A linear aggregate model for a hypothetical ring-width series is proposed, which allows the problem to be reduced to the estimation and extraction of five discrete classes of signals. These classes represent the signals due to trend, climate, endogenous disturbance, exogenous disturbance, and random error. For each class of signal, some mathematical/statistical techniques of estimation are described and reviewed. Except for the exogenous disturbance signal, the techniques only require information contained within the ring-width series, themselves. A unified mathematical framework for solving this decomposition problem has not yet been explicitly formulated. However, the general applicability of ARMA time series models to this problem and the power and flexibility of state space modelling suggest that these techniques will provide the closest thing to a unified framework in the future.

The thesis is a summary and discussion of six papers. The purpose of the investigation was to study the influence of (i) environmental factors and (ii) the physiological condition of the thallus on nitrogen fixation in the lichen Stereocaulon paschale (L.) Fr. The nitrogen input to the site, a sparsely stocked pine forest in northern Sweden, was also studied. Nitrogen fixation (nitrogenase activity) was measured as acetylene reduction both in the field and in the laboratory. Usually intact lichen thalli were used, but also excised cephalodia were studied. All nitrogenase activity was located in the external cephalodia containing the blue-green alga Stigonema sp. There was always a reduction in nitrogenase activity when the cephalodia were quantitatively excised from the thallus. Moisture was found to be the most important environmental factor in the field during the snow free part of the year. At the site, with 14 % of the ground covered by S. paschale3 the yearly nitrogen fixation was estimated to c. 0.1 g nitrogen per m^. The lichen thalli could withstand several months in a very dry condition and at a low temperature without significant decrease in nitrogenase activity. A higher capacity for nitrogenase activity was found in lichen thalli collected from bare ground than in thalli collected under the snow. The light conditions before as well as during the nitrogenase activity measurements affected the nitrogenase activity. Thalli incubated with acetylene in the dark had only c. two thirds of their activities in the light. Lichen thalli pretreated in the light showed increased nitrogenase activities, probably due to raised content of carbohydrates available for nitrogenase activity. The necessary energy for nitrogenase activity is supplied by either oxidative phosphorylation or photophosphorylation. / digitalisering@umu

The number of children living in the context of relative poverty in western industrialized countries is increasing, while at the same time a little amount of research is conducted about the impact of relative poverty on the child’s participation and development; focused on the socio-emotional development. This systematic literature review therefore investigates the impact of environmental factors, focused mainly on structural factors, in poverty settings in western industrialized countries on children´s peer relations. The focus will be laid on children´s participation in peer relations in school activities.  Current literature published from 2012 or more recent was searched and results found were linked to theories. The findings of the articles covered several environmental aspects regarding the impact of poverty on the child and its peer relations. The results, in relation to theories, show the interwoven influences of several factors and environments. They indicate the big influence poverty has on several aspects of the child´s life. Both in this systematic literature review researched hypotheses – that the poverty setting influences the child´s development negatively and that the child shows difficulties to develop and participate in positive peer relations - can be confirmed. Future research should aim at generating knowledge about the impact of relative poverty on the child´s development and perceptions of holistic wellbeing. This is necessary to enhance the understanding of the impact of relative poverty on the child´s participation.