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Now showing items 13-32 of 382
  • Khriachtchev, Leonid; Lundell, Jan; Pettersson, Mika; Tanskanen, Hanna; Räsänen, Markku (American Institute of Physics, 2002)
  • Fischer, Johannes; Mäkinen, Veli; Navarro, Gonzalo (Springer-Verlag, 2008)
    Suffix trees are one of the most important data structures in stringology, with myriads of applications in fluorishing areas like bioinformatics. As their main problem is space usage, recent efforts have focused on compressed suffix tree representations, which obtain large space reductions in exchange for moderate slowdowns. Such a smaller suffix tree could fit in a faster memory, outweighting by far the theoretical slowdown. We present a novel compressed suffix tree. Compared to the current compressed suffix trees, it is the first achieving at the same time sublogarithmic complexity for the operations, and space usage which goes to zero as the entropy of the text does. Our development contains several novel ideas, such as compressing the longest common prefix information, and totally getting rid of the suffix tree topology, expressing all the suffix tree operations using range minimum queries and a new primitive called next/previous smaller value in a sequence.
  • Li, Rui; Xie, Jinglin; Kantor, Carmela; Koistinen, Vesa; Altieri, Dario C.; Nortamo, Pekka; Gahmberg, Carl G. (Rockefeller University Press, 1995)
    β2 integrin (CDlla,b,c/CD18)-mediated cell adhesion is required for many leukocyte functions. Under normal circumstances, the integrins are nonadhesive, and become adhesive for their cell surface ligands, the intercellular adhesion molecules (ICAMs), or soluble ligands such as fibrinogen and iC3b, when leukocytes are activated. Recently, we defined a peptide derived from ICAM-2, which specifically binds to purified CDlla/CD18. Furthermore, this peptide strongly induces T cell aggregation mainly mediated by CDlla/CD18-ICAM-1 interaction, and natural killer cell cytotoxicity. In the present study, we show that the same ICAM-2 peptide also avidly binds to purified CDllb/CD18, but not to CDllc/CD18. This binding can be blocked by the CD1 lb antibody OKM10. The peptide strongly stimulates CDllb/CD18-ICAM-l-mediated cell aggregations of the monocytic cell lines THP-1 and U937. The aggregations are energy and divalent cation-dependent. The ICAM-2 peptide also induces CDllb/CD18 and CDllc/CD18-mediated binding of THP-1 cells to fibrinogen and iC3b coated on plastic. These findings indicate that in addition to induction of CDlla/CD18- mediated cell adhesion, the ICAM-2 peptide may also serve as a "trigger" for high avidity ligand binding of other β2 integrins.
  • Kikuchi, R. (Elsevier Science B.V., 1999)
    The rapid increase in population and economic growth have led to an increase in energy demand. Coal reserves are distributed worldwide, and coal is now known to be the most stable and available energy source. However, utilization of coal as an energy source involves the generation of a great amount of coal ash, and the recycling rate of the ash is rather low. Coal ash is mainly used in civil construction materials, and there is a limit to the demand for coal ash by construction industries: therefore, the increasing amount of coal ash will be a serious problem in the near future. Different applications should be considered. In this paper, three environmentally-friendly methods for coal ash recycling are described. Firstly, alkali treatment can transform coal ash to zeolite, which is used in deodorant and for wastewater treatment and soil improvement. Secondly, potassium silicate fertilizer is produced from coal ash and has a higher retentivity in the soil than that of conventional fertilizers. Thirdly, emission of sulfur dioxide is controlled by flue gas desulfurization using coal ash. It is considered that environmentally-friendly use of coal ash is important from the viewpoints of energy, economy, and environmental strategy in order to realize the concept of sustainable development.
  • Mukherjee, A.B.; Bhattacharya, P. (NRC Research Press, 2001)
  • Voigt, H.-R. (Yhtyneet Kuvalehdet, 1976)
  • Polishchuk, Valentin; Suomela, Jukka (Elsevier, 2009)
    We present a local algorithm (constant-time distributed algorithm) for finding a 3-approximate vertex cover in bounded-degree graphs. The algorithm is deterministic, and no auxiliary information besides port numbering is required.
  • Voigt, H.-R. (Scandinavian Society for Parasitology, 1981)
  • Voigt, H.-R. (Nordenskiöld-samfundet, 1972)
  • Lehvävirta, S.; Rita, H.; Koivula, M. (Elsevier GmbH, 2004)
    In order to maintain indigenous, self-regenerating tree populations in urban woodlands, it is essential to identify factors affecting the survival of tree seedlings and saplings. In densely populated areas, intensive recreational use may cause considerable wear of the vegetation and soil, and decrease the total number of saplings. At the same time trees, high stones and other structural elements in a woodland patch can act as natural barriers and give shelter against wear. Hence, we hypothesised that with an increasing amount of wear, a greater proportion of tree saplings survive, and is thus found, close to these natural barriers. We tested this hypothesis with observational data, and described the microhabitat associations of different sapling species in detail to define the most favourable or unfavourable microhabitats. We recorded the microhabitats of saplings and randomly chosen points in 30 medium-fertile Picea abies dominant woodlands in Helsinki and the surroundings, Finland. The description included location in relation to physical objects (stones, trees, topography, etc.), other saplings, vegetation and canopy. We then compared the sapling microhabitats to those available (the random points). Our results suggest that the microhabitat associations of saplings change with increasing wear: Sorbus aucuparia, Populus tremula, Rhamnus frangula, Picea abies and Acer platanoides saplings grew more often close to natural barriers (obstacles X30 cm high excluding other saplings), the first three showing a statistically significant response to wear in logistic regression models. The saplings were able to grow in a variety of microhabitats, but the species also differed in their microhabitat associations. In general, saplings grew in groups, and in worn sites the grouping was more pronounced. With increasing wear the saplings associated more positively with trees, canopy cover and lush vegetation.
  • Isaksson, Eva (Astronomical Society of the Pacific, 2007)
    Finnish astronomy publishing provides us with an interesting data sample. It is small but not too small: approximately one thousand articles have been published in a decade. There are only four astronomy institutes to be compared. An interesting paradox also emerges in the field: while Finnish science assessments usually value highly the impact of scientific publishing, no serious evaluations using real bibliometric data have been made. To remedy this, a comprehensive ten-year database of refereed papers was collected and analyzed.
  • Niemelä, J. (Finnish Zoological and Botanical Publishing Board, 2000)
    Biodiversity monitoring provides guidelines for decisions on how to manage biological diversity in terms of production and conservation. Monitoring determines the status of biological diversity at one or more ecological levels and assesses changes over time and space. Monitoring at the global level is needed to compare trends caused by the increasing homogenisation of the world’s landscapes. Bioindicators are routinely used, but each indicator’s potential to determine changes in the overall biodiversity should be rigorously tested. Monitoring is a vital feedback link between human actions and the environment, but incorporation of monitoring results into decision making is hampered by poor communication between ecologists and decision-makers. A global network for assessing biodiversity changes (GLOBENET) is described as an example of an initiative that attempts to address the above issues by using a simple field protocol with the aim to develop tools for assessment and prediction of the ecological effects of human-caused changes in the landscape.
  • Voigt, H.-R. (University of Helsinki, 1992)
  • Voigt, H.-R. (University of Helsinki, 1995)
  • Kauppi, P.E.; Mielikäinen, K.; Kuusela, K. (American Association for the Advancement of Science, 1992)
  • Voigt, H.-R. (Centralförbundet för fiskerihushållning, 1994)
  • Koivula, M.; Kukkonen, J.; Niemelä, J. (Kluwer Academic Publishers, 2002)
    We examined the occurrence of carabid beetles along a forest succession gradient in central Finland (forest age classes: 5, 10, 20, 30 and 60 years since clear-cutting). Species richness of carabids was higher in the two youngest age classes, while no clear differences were detected in carabid abundance. The high species richness in the young, open sites was due to invasion of open-habitat species. Many forest species were absent from or scarce in the young sites and became gradually more abundant towards the older forest age classes. The catches indicated a drastic decrease and assemblagelevel change in concert with canopy closure, i.e. 20–30 years after clear-cutting. Some forest specialists with poor dispersal ability may face local extinction, if the proportion of mature forest decreases further and the remaining mature stands become more isolated. We recommend that, while harvesting timber, connectivity between mature stands is ensured, mature stands are maintained close (a few tens of metres) to each other and the matrix quality is improved for forest species by green tree retention.