| 1. |
- Kivinen, Sonja, et al.
(author)
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Threat spots and environmental determinants of red-listed plant, butterfly and bird species in boreal agricultural environments
- 2008
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In: Biodiversity and Conservation. - : Springer Science and Business Media LLC. - 0960-3115 .- 1572-9710. ; 17:13, s. 3289-3305
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Journal article (peer-reviewed)abstract
- The aims of this study were (1) to examine the geographic distribution of red-listed species of agricultural environments and identify their national threat spots (areas with high diversity of threatened species) in Finland and (2) to determine the main environmental variables related to the richness and occurrence patterns of red-listed species. Atlas data of 21 plant, 17 butterfly and 11 bird species recorded using 10 km grid squares were employed in the study. Generalized additive models (GAMs) were constructed separately for species richness and occurrence of individual species of the three species groups using climate and land cover predictor variables. The predictive accuracy of models, as measured using correlation between the observed and predicted values and AUC statistics, was generally good. Temperature-related variables were the most important determinants of species richness and occurrence of all three taxa. In addition, land cover variables had a strong effect on the distribution of species. Plants and butterflies were positively related to the cover of grasslands and birds to small-scale agricultural mosaic as well as to arable land. Spatial coincidence of threat spots of plants, butterflies and birds was limited, which emphasizes the importance of considering the potentially contrasting environmental requirements of different taxa in conservation planning. Further, it is obvious that the maintenance of various non-crop habitats and heterogeneous agricultural landscapes has an essential role in the preservation of red-listed species of boreal rural environments.
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| 2. |
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| 3. |
- Tengborn, Elisabeth, 1978, et al.
(author)
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Effect of the misorientation of the 4H-SiC substrate on the open volume defects in GaN grown by metal-organic chemical vapor deposition
- 2006
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In: Applied Physics Letters. ; 89:091905, s. 3-
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Journal article (peer-reviewed)abstract
- Positron annihilation spectroscopy has been used to study GaN grown by metal-organic chemical vapor deposition on misoriented 4H-SiC substrates. Two kinds of vacancy defects are observed: Ga vacancies and larger vacancy clusters in all the studied layers. In addition to vacancies, positrons annihilate at shallow traps that are likely to be dislocations. The results show that the vacancy concentration increases and the shallow positron trap concentration decreases with the increasing substrate misorientation.
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| 4. |
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| 5. |
- Aavikko, R., et al.
(author)
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Clustering of vacancy defects in high-purity semi-insulating SiC
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - 1098-0121 .- 1550-235X. ; 75:8, s. 085208-
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Journal article (peer-reviewed)abstract
- Positron lifetime spectroscopy was used to study native vacancy defects in semi-insulating silicon carbide. The material is shown to contain (i) vacancy clusters consisting of four to five missing atoms and (ii) Si-vacancy-related negatively charged defects. The total open volume bound to the clusters anticorrelates with the electrical resistivity in both as-grown and annealed materials. Our results suggest that Si-vacancy-related complexes electrically compensate the as-grown material, but migrate to increase the size of the clusters during annealing, leading to loss of resistivity. © 2007 The American Physical Society.
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| 6. |
- Aavikko, R, et al.
(author)
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Observation of vacancy clusters in HTCVD grown SiC
- 2005
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In: Materials Science Forum, Vols. 483-485. ; , s. 469-472
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Conference paper (peer-reviewed)abstract
- Positron lifetime spectroscopy was used to study defects in semi-insulating (SI) silicon carbide (SiC) substrates grown by high-temperature chemical vapor deposition (HTCVD). The measured positron lifetime spectra can be decomposed into two components, of which the longer corresponds to vacancy clusters. We have carried out atomic superposition calculations to estimate the size of these clusters.
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| 7. |
- Giuliani, G., et al.
(author)
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Round-Robin Measurements of Linewidth Enhancement Factor of Semiconductor Lasers in COST 288 Action
- 2007
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In: Lasers and Electro-Optics, 2007 and the International Quantum Electronics Conference. CLEOE-IQEC 2007. European Conference on. - 1424409306 - 9781424409303 ; , s. 4385967-
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Conference paper (peer-reviewed)abstract
- Round-robin measurements on the linewidth enhancement factor are carried out in many laboratories participating to EU COST 288 Action. Up to 7 different techniques are applied to DFB, VCSELs, QCL, and QD lasers, and results are compared.
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| 8. |
- Gogova, D., et al.
(author)
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Investigation of the structural and optical properties of free-standing GaN grown by HVPE
- 2005
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In: Journal of Physics D. - : IOP Publishing. - 0022-3727 .- 1361-6463. ; 38:14, s. 2332-2337
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Journal article (peer-reviewed)abstract
- The potential of the high-growth rate hydride vapour phase epitaxy technique and laser lift-off for the fabrication of free-standing GaN substrates is explored. Structural and optical properties of 300 νm thick free-standing GaN have been investigated employing different analytical techniques. The x-ray diffraction (XRD) measurements prove good crystalline quality of the material grown. A comparatively low value of (3 ± 1) × 1016 cm-3 of Ga vacancy-related defects is inferred from positron annihilation spectroscopy data. Complete strain relaxation is observed on the Ga-polar face of the free-standing GaN by XRD and Raman spectroscopy measurements. The strain-free homoepitaxy will significantly reduce the defect density, and thus an improvement of the device performance and lifetime can be realized. © 2005 IOP Publishing Ltd.
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| 9. |
- Hall, C. Michael, et al.
(author)
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Nordic Tourism : Issues and Cases
- 2009
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Book (peer-reviewed)abstract
- Tourism is a major industry in the Nordic countries (Denmark, Finland, Iceland, Norway and Sweden) as well as a growing field of academic study. For many cities and regions tourism is also increasingly recognised as being integral to economic, social and sustainable development. In addition, tourism also contributes to Nordic identity through destination promotion and tourism activities, including winter tourism and the tradition of access to common land, as well as specific forms of tourism, such as second homes.This book is the first comprehensive and accessible introduction to tourism in the region that links Nordic tourism research and concerns with key concept in tourism studies. The book consists of eleven chapters dealing with issues ranging from marketing and policy to nature-based tourism, culture and the contribution of tourism to environmental change. The inclusion of case studies from leading Nordic researchers on specific destinations, attractions, resources, sectors and developments also provide a valuable learning tool for all students of tourism.
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| 10. |
- Heiskanen, Annamari, et al.
(author)
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N-glycolylneuraminic acid xenoantigen contamination of human embryonic and mesenchymal stem cells is substantially reversible.
- 2007
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In: Stem cells (Dayton, Ohio). - : Oxford University Press (OUP). - 1066-5099 .- 1549-4918. ; 25:1, s. 197-202
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Journal article (peer-reviewed)abstract
- Human embryonic and mesenchymal stem cell therapies may offer significant benefit to a large number of patients. Recently, however, human embryonic stem cell lines cultured on mouse feeder cells were reported to be contaminated by the xeno-carbohydrate N-glycolylneuraminic acid (Neu5Gc) and considered potentially unfit for human therapy. To determine the extent of the problem of Neu5Gc contamination for the development of stem cell therapies, we investigated whether it also occurs in cells cultured on human feeder cells and in mesenchymal stem cells, what are the sources of contamination, and whether the contamination is reversible. We found that N-glycolylneuraminic acid was present in embryonic stem cells cultured on human feeder cells, correlating with the presence of Neu5Gc in components of the commercial serum replacement culture medium. Similar contamination occurred in mesenchymal stem cells cultured in the presence of fetal bovine serum. The results suggest that the Neu5Gc is present in both glycoprotein and lipid-linked glycans, as detected by mass spectrometric analysis and monoclonal antibody staining, respectively. Significantly, the contamination was largely reversible in the progeny of both cell types, suggesting that decontaminated cells may be derived from existing stem cell lines. Although major complications have not been reported in the clinical trials with mesenchymal stem cells exposed to fetal bovine serum, the immunogenic contamination may potentially be reflected in the viability and efficacy of the transplanted cells and thus bias the published results. Definition of safe culture conditions for stem cells is essential for future development of cellular therapies.
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