| 1. |
- Sumaila, U. Rashid, et al.
(författare)
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WTO must ban harmful fisheries subsidies
- 2021
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Ingår i: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 374:6567, s. 544-544
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
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| 2. |
- Berthelsen, A., et al.
(författare)
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Recording marine airgun shots at offsets between 300 and 700 km
- 1991
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Ingår i: Geophysical Research Letters. - 0094-8276 .- 1944-8007. ; 18:4, s. 645-648
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Tidskriftsartikel (refereegranskat)abstract
- This paper demonstrates that - under favorable conditions - by using multichannel recording and subsequent stacking of adjacent records marine airgun shots have been detected at offset distances up to 700 km, the maximum offset at which the authors attempted to record data.^Besides a powerful airgun array, a low noise environment at the recording site and the elimination of static shifts are the prerequisites to obtain refracted and reflected arrivals from the crust and upper mantle at such large offsets.^Primary arrivals detected at offsets between 400 and 700 km image the upper mantle from 70 to about 120 km depth.^Stacking of neighboring shots and/or receivers successfully increases the signal-to-noise ratio, if the traces have been corrected for offset differences, which requires knowledge of the apparent phase velocities.^The data presented here were collected in autumn 1989 during the BABEL Project on the Baltic Shield.
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| 3. |
- Brändström, U., et al.
(författare)
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Results from the intercalibration of optical low light calibration sources 2011
- 2012
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Ingår i: Geoscientific Instrumentation, Methods and Data Systems. - : Copernicus GmbH. - 2193-0856 .- 2193-0864. ; 1:1, s. 43-51
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Tidskriftsartikel (refereegranskat)abstract
- Following the 38th Annual European Meeting onAtmospheric Studies by Optical Methods in Siuntio in Finland,an intercalibration workshop for optical low light calibrationsources was held in Sodankyl¨a, Finland. The mainpurpose of this workshop was to provide a comparable scalefor absolute measurements of aurora and airglow. All sourcesbrought to the intercalibration workshop were compared tothe Fritz Peak reference source using the Lindau CalibrationPhotometer built by Wilhelm Barke and Hans Lauche in1984. The results were compared to several earlier intercalibrationworkshops. It was found that most sources were fairlystable over time, with errors in the range of 5–25 %. To furthervalidate the results, two sources were also intercalibratedat UNIS, Longyearbyen, Svalbard. Preliminary analysis indicatesagreement with the intercalibration in Sodankyl¨a withinabout 15–25 %.
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| 4. |
- Hobbs, R. W., et al.
(författare)
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Integrated seismic studies of the Baltic shield using data in the Gulf of Bothnia region
- 1993
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Ingår i: Geophysical Journal International. - 0956-540X .- 1365-246X. ; 112:3, s. 305-324
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Tidskriftsartikel (refereegranskat)abstract
- In the autumn of 1989 a co-operative experiment involving 12 research institutions in northwestern Europe collected 2268 km of deep seismic reflection profiles in the Gulf of Bothnia and the Baltic Sea. the 121 litre airgun array used for this profiling was also recorded by 62 muiticomponent land stations to provide coincident refraction surveys, fan-spreads, and 3-D seismic coverage of much of the Gulf of Bothnia. We thus have potentially both high-resolution impedance contrast images as well as more regional 3-D velocity models in both P- and S-waves. In the Bothnian Bay a south-dipping, non-reflective zone coincides with the conductive Archaean-Proterozoic boundary onshore in Finland. Between the Bothnian Bay and Bothnian Sea observed reflectivity geometries and velocity models at Moho depths suggest structures inherited from a 1.9Ga subduction zone; the upper crust here appears to have anomalously low velocity. Within the Bothnian Sea, reflectivity varies considerably beneath the metasedimentary/granitoid rocks of the Central Svecofennian Province (CSP) and the surrounding metavolcanic-arc rocks. Numerous dipping reflectors appear throughout the metavolcanic crust, whereas the CSP has little reflectivity. Wide-angle reflections indicate that the metasedimentary crust of the Bothnian Basin is 10 km thicker than the neighbouring Svecofennian subprovinces. Near the Åland archipelago Rapakivi granite plutons exhibit bright reflections, a contrast to the usual non-reflective plutons elsewhere in western Europe. Additional dipping reflections deep in the crust of this area may support models of rifting and crustal thinning during emplacement of the 1.70-1.54 Ga Rapakivi granites. Coeval gabbroic/anorthositic magmatism may explain the high reflectivity and high velocity of these plutons. the c. 1.25 Ga mafic sills and feeder dykes of the Central Scandinavian Dolerite Group also produce clear reflections on both near- and far-offset seismic sections. Continued modelling will produce better velocity models of the crust and better constrained contour maps of crustal thickness in this part of the Baltic shield.
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| 5. |
- Katerelos, Dionisios T. G., et al.
(författare)
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Alteration of the mechanical behaviour of polypropylene owing to successive introduction of multiwall carbon nanotubes and stretching
- 2009
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Ingår i: Mechanics of composite materials. - : Springer Science and Business Media LLC. - 0191-5665 .- 1573-8922. ; 45:4, s. 423-434
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Tidskriftsartikel (refereegranskat)abstract
- Stretching effects on the morphology of polypropylene/carbon nanotube composites is the focus of this work. The material under investigation was composed of isotactic polypropy lene (iPP) and multiwall car bon nanotubes (MWCNTs) in amount of 0.5 wt.%. The iPP and CNTs were mixed under sonication in a solvent, and the homogenized mixture was melted and pressed. The rectangular plates produced from the material were stretched by a constant load at a fixed temperature in order to obtain extended specimens. The scanning electron microscopy, a thermal gravimetric analysis, and the differential scanning calorimetry were employed to study variations in the structural morphology of the material. A dynamic mechanical analysis showed that the strain-induced crystallization of polypropylene and the possible Stone-Wales transformation of the carbon nanotubes due to stretching improved the mechanical performance of the nanocomposites considered.
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| 6. |
- Kislev, T., et al.
(författare)
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On the nature of opaque cylindrical regions formed at fibre break sites in a fragmentation test
- 2002
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Ingår i: Advanced Composites Letters. - : SAGE Publications. - 0963-6935 .- 2633-366X. ; 11:1, s. 7-13
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Tidskriftsartikel (refereegranskat)abstract
- When a single-fibre composite test is performed to obtain information about the interfacial adhesion in a composite, a gradual strain increase often causes an opaque (black) cylinder to nucleate at, and grow from, the fibre failure sites. The nature of the opaque cylinder is difficult to ascertain using optical microscopy. This is the subject of the present note. To study the inside of the opaque cylinder we use several experimental methods based on imaging the failed region: optical microscopy, laser Raman spectroscopy and scanning electron microscopy. Mechanical models, including FEM analysis and analytic equations based on the shear-lag, approach, are used to discuss the experimental work. The nature and growth mechanism of the opaque cylinder are of importance in defining the parameters and/or contributions that appear in both the force balance and the. energy balance schemes.
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| 7. |
- Korja, Toivo, et al.
(författare)
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The geoelectric model of the POLAR Profile, Northern Finland
- 1989
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Ingår i: Tectonophysics. - : Elsevier BV. - 0040-1951 .- 1879-3266. ; 162:1-2, s. 113-133
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Tidskriftsartikel (refereegranskat)abstract
- Electromagnetic soundings have been made in order to construct a geoelectrical (conductivity) model of the crust along the European Geotraverse (EGT) POLAR Profile. Forty magnetotelluric (MT) soundings, eighteen audiomagnetotelluric (AMT) soundings and ten magnetohydrodynamic (MHD) soundings were made on the main POLAR Profile (POLAR I) and ten more MT soundings on a parallel profile (POLAR II), 40 km to the southeast of the main profile. Analysis of simultaneous recordings by the EISCAT magnetometer chain, and thin-sheet modelling of the effect of the Barents Sea, indicate that neither the source field effects nor the presence of the ocean are significant at periods below 200 s in the measurement area. The magnetotelluric data have been modelled with two-dimensional models representing the regional structure along the profiles. In addition to the regional structure, a thin inhomogeneous surface layer is included in the models in order to explain some local features of the measured response functions. Although details of the surface electrical structures are poorly resolved, the gross features of the geoelectrical cross section are considered to be reliable. The results divide the POLAR Profile into three different blocks. The better conducting Karasjok-Kittilä Greenstone Belt in the south has an average resistivity of less than 10 Ωm. The more resistant Lapland Granulite Belt, with a resistivity between 100 and 200 Ωm, is underlain by conductive (< 5 Ωm), N-dipping layers. The depth for the uppermost conductive layer varies from a few kilometres in the southwestern part of the granulite belt to 13 km in the northeastern part, from where it rises steeply towards the surface close to the boundary between the Lapland Granulite Belt and the Inari Terrain. These features appear to be continuous between the two parallel MT profiles. Within the Inari Terrain a conductive zone at an approximate depth of 10 km and with a resistivity of about 20 Ωm was identified in a resistive upper crust. The geoelectric cross section agrees, in gross detail, with the corresponding gravity, refraction seismic and reflection seismic cross sections of the POLAR Profile. All methods indicated a similar shape for the southwestern part of the Lapland Granulite Belt i.e., granulites have a gently NE-dipping boundary against the underlying Karelian Province. In the northeastern part of the granulite belt the geoelectric model and the gravimetric model show a rather steep S-dipping boundary against the Inari Terrain northeast of the granulite belt.
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| 8. |
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| 9. |
- Öhlander, Björn, et al.
(författare)
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Delineation and character of the Archaean-Proterozoic boundary in northern Sweden
- 1993
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Ingår i: Precambrian Research. - 0301-9268 .- 1872-7433. ; 64:1-4, s. 67-84
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Tidskriftsartikel (refereegranskat)abstract
- Before the deposition of a Proterozoic cover and the repeated Proterozoic reworking of the older rocks, the presently exposed Archaean areas in northern Sweden formed part of a coherent craton. In the present study, we have used Sm---Nd isotopic analyses of Proterozoic granitoids and metavolcanics to delineate the Archaean palaeoboundary. In a regional context, the transition from strongly negative εNd(t) values in the northeast to positive values in the southwest is distinct, and approximately defines the border of the old craton. The Archaean palaeoboundary extends in a WNW direction, and is subparallel to the longitudinal axis of the Skellefte sulphide ore district but it is situated ≈ 100 km farther to the north. The ≈ 1.9 Ga old granitoids on the two sides of the palaeoboundary were all formed in compressional environments, but those situated to the north have higher contents of LILE and LREE at similar contents of Si. This indicates that they were generated in an area with thicker crust and supports the location of the Archaean-Proterozoic palaeoboundary. There is no simple correlation between the Archaean palaeoboundary, as defined by the isotopic results, and any of the major fracture systems as interpreted from regional geophysical measurements. Reflection seismic work indicates that juvenile volcanic-arc terrains to the south have been thrust onto the Archaean craton. Possible thrust faults have been identified from aeromagnetic measurements. Rifting of the Archaean craton created a passive margin ≈ 2.0 Ga ago. Spreading shifted to convergence with subduction beneath the Archaean continent ≈ 1.9 Ga ago. Subsequently, the resulting juvenile volcanic arc collided with the old continent, and the Archaean palaeoboundary as existing today was formed by a collision characterized by overthrusting. The boundary then was disturbed by later deformation predominantly along NNE-trending fracture systems.
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