Browsing by Subject "Productivity"

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  • Vuorinne, Ilja; Heiskanen, Janne; Maghenda, Marianne; Mwangala, Lucas; Muukkonen, Petteri; Pellikka, Petri K.E. (2021)
    Biomass is a key variable for crop monitoring and for assessing carbon stocks and bioenergy potential. This study aimed to develop an allometric model for predicting the dry leaf biomass of sisal, an agave plant with crassulacean acid metabolism grown for fibre production in the tropics and subtropics and whose biomass can be utilised as a feedstock to produce biogas through anaerobic digestion. The allometric model was used to estimate leaf biomass and productivity across different stand ages in a sisal plantation in semi-arid region in south-east Kenya (annual rainfall 611 mm and temperature 24.9 °C). Based on a sample of 38 leaves, the best predictor for biomass was leaf maximum width and plant height used as a combined variable in a log-log regression model (cross-validated R2 = 0.96 and root-mean-square error = 7.69 g). The mean productivity in nine 26- to 36-month-old plots was 11.1 Mg ha−1 yr−1, which could potentially yield approximately 3000 m3 CH4 ha−1 yr−1. The leaf biomass in 55 field plots (400 m2 in area) ranged from 2.7 to 42.7 Mg ha−1, with mean at 13.5 Mg ha−1, which equals to 6.3 Mg C ha−1. The yielded allometric equations can be utilised for predicting the leaf biomass of sisal in similar agro-ecological zones. The estimates on plantation biomass can be used in assessing the role of sisal plantations as a regional carbon storage. In addition, the results provide reference on the productivity of agave and crassulacean acid metabolism in semi-arid regions of East Africa, where such reports are few.
  • Mankinen, Petri; Lundström, Tuomas; Soini, Erkki; Sumelahti, Marja-Liisa; Ruutiainen, Juhani; Niskala, Ulla; Järvinen, Elina (2020)
    Introduction Cost assessment modelling (CAM) of treatments in highly active relapsing multiple sclerosis was conducted. Methods The CAM was developed using the R programming language. The PICOSTEPS health technology assessment framework was applied in the CAM. Modelled patients were 280 adults with highly active relapsing multiple sclerosis eligible for disease-modifying treatment. Intervention was cladribine tablets, a new and reimbursed oral treatment for highly active relapsing multiple sclerosis in Finland. Comparators included fingolimod, the most used oral reimbursed treatment for the highly active disease, and natalizumab, the most used intravenous treatment, and a treatment mix (80% use fingolimod, 20% use natalizumab) in Finland. Outcomes presented expected annual and cumulative drug-associated costs in the overall population and per patient. Setting was modelled public specialist care in Finland. Time was set to 4 years, without discounting. Effects covered expected drug-associated costs (screening, acquisition, administration, monitoring, adverse events, travelling, productivity). Perspective was a limited societal perspective. Sensitivity analyses regarding all PICOSTEPS components were conducted. Results Cladribine tablets were projected to be cost saving in comparison to fingolimod, natalizumab and treatment mix. The respective modelled savings were euro4,598,742, euro16,249,701 and euro6,928,934 in the overall population, and euro16,424, euro58,035 and euro24,746 per patient, respectively, during the 4 years. The most important cost driver was drug costs, representing 96.3%, 96.0% and 83.4% of modelled costs associated with cladribine tablets, fingolimod and natalizumab, respectively. Cladribine tablets sustained their affordability in the sensitivity analyses. From the perspective of health care payer, cladribine tablets' savings were projected to be euro4,514,509, euro15,145,366 and euro6,640,680 in the overall population, and euro16,123, euro54,091 and euro23,717 per patient in comparison to fingolimod, natalizumab and treatment mix, respectively. Conclusion Based on the CAM, cladribine tablets were projected to robustly save modelled drug-associated costs in comparison to fingolimod, natalizumab and their mix in Finland.
  • Järvinen, Jaakko (Helsingin yliopisto, 2019)
    The main thesis of economies of agglomeration is that by increasing the density of employment, economic benefits will follow. In this research, this hypothesis is tested in the context of the Nordic countries by studying if the increases in the employment density affect the regional productivity. This effect between the employment density and regional productivity is called the agglomeration effect. The theoretical background of this effect lies in three fundamental concepts: economies of scale, labor pooling and knowledge spillovers. Cities have their origins in the economies of scale and ag- glomerations of people they comprise of form a fertile base for effective matching between employers and employees. The denser these production centers are populated, the easier it is for the spillovers of innovation and ideas to happen. This study uses a linear ordinary least squares (OLS) model to estimate this effect. The data consists of 70 regional observations and the model comprises of employment density as the explanatory variable, varying number of education level control variables and dummy variables for different countries. Endogeneity of the explanatory variable is also assessed but as the proposed instrument, the total land area of the included regions, proves to be invalid for this particular geographic region, the OLS estimates will serve as the final results. In the previous studies conducted in Europe and in the USA, the magnitude of the agglomeration effect has been found to be between 4.4 and 6 %. This study’s estimates tell the effect to be between 2.1 and 2.9 % in the Nordic countries that is lower than the corresponding values for the aforementioned regions. This result is discussed to stem from the unique geographical and political characteristics of the Nordic regions.
  • Kauppi, L.; Norkko, A.; Norkko, J. (2018)
    Three species of the invasive polychaete genus Marenzelleria are among the dominant benthic taxa in many, especially deeper, areas in the Baltic Sea. The population dynamics of the polychaetes in the Baltic are, however, still largely unknown. We conducted monthly samplings of the benthic communities and environmental parameters at five sites with differing depths and sediment characteristics in the northern Baltic Sea (59 degrees 50.896', 23 degrees 15.092') to study the population dynamics, productivity and growth of Marenzelleria spp. from April 2013 to June 2014. The species of Marenzelleria occurring at the study sites were identified by genetic analyses. At the deepest site (33 m) only M. arctia was present, while all three species were found at the shallower, muddy sites (up to 20 m depth). At the shallow (6 m) sandy site only M. viridis and M. neglecta occurred. The sites differed in the seasonal dynamics of the Marenzelleria spp. population, reflecting the different species identities. The muddy sites up to 20 m depth showed clear seasonal dynamics, with the population practically disappearing by winter, whereas more stable populations occurred at the deepest site and at the sandy site. The highest density, biomass and production were observed at the 20 m deep, organic-rich muddy site where all three species recruited. The seasonally very high densities are likely to have important consequences for organic matter processing, and species interactions at these sites. The observed high productivity of the populations has possibly facilitated their establishment, and considerably increased secondary production in especially the deeper areas.