| 1. |
- Rem, Peter C., et al.
(författare)
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The investigation of separability of particles smaller than 5 mm by eddy-current separation technology - Part II: novel design concepts
- 2000
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Ingår i: Magnetic and Electrical Separation. - : Hindawi Limited. - 1055-6915 .- 1029-0303 .- 1477-2876. ; 10:2, s. 85-105
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Tidskriftsartikel (refereegranskat)abstract
- Separability and separation mechanisms of small particles in modern rotating type eddy-current separators (ECSs) were discussed in Part I. In order to address problems associated with this design concept, a number of novel ECSs, each with a unique design, have been developed. Part II reports on investigation into the separability and separation principles for various materials smaller than 5 mm, including fine copper wires, in three new devices: the redesigned Delft vertical ECS (VECS), prototype TNO ECS and a laboratory wet ECS (WECS). It is found that TNO ECS and WECS are more practical tools for separation of small metal particles. In particular, WECS is able to recover approximately 80% of very fine copper wires, with 0.5 mm diameter and 2 mm length. Separation principles for WECS are discussed in greater detail than other design concepts in the present study. It appears that the fledgling WECS will be most promising in the future for processing small particles. Further, aluminum separation from the -10 mm fraction of electronic scrap has been carried out using TNO ECS. It transpires that both the recovery and the grade of the aluminum concentrate are superior to those obtained with the rotary belted-drum ECS of any type.
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| 2. |
- Wang, Yanmin, et al.
(författare)
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Purification of fine powders by a superconducting HGMS with vibration assistance
- 2000
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Ingår i: Magnetic and Electrical Separation. - : Hindawi Limited. - 1055-6915 .- 1029-0303 .- 1477-2876. ; 10:3, s. 161-178
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Tidskriftsartikel (refereegranskat)abstract
- In this study, a superconducting high gradient magnetic separator (HGMS) with a matrix vibration system in dry mode was utilized to purify fine calcite and quartz powders smaller than 38 μm. The effects of the operating parameters (particle size, magnetic field/average air velocity (B0/V0), the amplitude of vibration as well as the aperture size of the expanded metal matrix) have been presented. The mechanically-based matrix vibration with the air blowing was recognized to be effective for dry purification of fine powdered materials at high magnetic fields. The function of the matrix vibration has been discussed. In addition, the results have been empirically correlated with the operating parameters used for the purification in the separator.
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| 3. |
- Carlsson, Lars
(författare)
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Towards a sustainable Russian forest sector
- 2000
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Ingår i: Natural resources forum (Print). - : Wiley. - 0165-0203 .- 1477-8947. ; 24:1, s. 31-37
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Tidskriftsartikel (refereegranskat)abstract
- Russia's forest resources are enormous, but despite almost ten years of transition, problems are still immense, in terms of commercial output and with respect to forest management. This article suggests that one way of changing the situation is to introduce community management of forests. Using the Swedish forest commons as an example, this article argues that such a change in property rights will provide an alternative to massive privatization of the forests and to the undesirable continuation or strengthening of state forest management. Finally, it is concluded that such an introduction of new property rights regimes will not provide the solution to the problems, but rather will contribute to the establishment of a better institutional framework in the Russian forest sector
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| 4. |
- Wågberg, Thomas, et al.
(författare)
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2D polymerization and doping of fullerenes under pressure
- 2000
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Ingår i: High Pressure Research vol. 18. - : Gordon & Breach. ; 18:1-6, s. 139-143
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Konferensbidrag (refereegranskat)abstract
- Tetragonal polymeric C60 has been studied by Raman spectroscopy and other methods. Attempts have been made to transform samples from the tetragonal to the orthorhom-bic phase and vice versa. The results suggest that the transformation is direct with no intermediate stage with free molecules. Tetragonal C60 has also been intercalated by potassium metal.
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| 5. |
- Palmgren, J
(författare)
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Exponential family models and statistical genetics
- 2000
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Ingår i: Statistical methods in medical research. - : SAGE Publications. - 0962-2802 .- 1477-0334. ; 9:1, s. 57-72
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Tidskriftsartikel (refereegranskat)abstract
- This article describes the evolution of applied exponential family models, starting at 1972, the year of publication of the seminal papers on generalized linear models and on Cox regression, and leading to multivariate (i) marginal models and inference based on estimating equations and (ii) random effects models and Bayesian simulation-based posterior inference. By referring to recent work in genetic epidemiology, on semiparametric methods for linkage analysis and on transmission/disequilibrium tests for haplotype transmission this paper illustrates the potential for the recent advances in applied probability and statistics to contribute to new and unified tools for statistical genetics. Finally, it is emphasized that there is a need for well-defined postgraduate education paths in medical statistics in the year 2000 and thereafter.
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| 6. |
- Papi, F, et al.
(författare)
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Open-sea migration of magnetically disturbed sea turtles
- 2000
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Ingår i: Journal of Experimental Biology. - 1477-9145. ; 203:22, s. 3435-3443
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Tidskriftsartikel (refereegranskat)abstract
- Green turtles (Chelonia mydas) that shuttle between their Brazilian feeding grounds and nesting beaches at Ascension Island in the middle of the Atlantic Ocean are a paradigmatic case of long-distance oceanic migrants. It has been suggested that they calculate their position and the direction of their target areas by using the inclination and intensity of the earths magnetic field. To test this hypothesis, we tracked, by satellite, green turtles during their postnesting migration from Ascension Island to the Brazilian coast more than 2000 km away. Seven turtles were each fitted with six powerful static magnets attached in such a way as to produce variable artificial fields around the turtle that made reliance on a geomagnetic map impossible. The reconstructed courses were very similar to those of eight turtles without magnets that were tracked over the same period and in the previous year, and no differences between magnetically disrupted and untreated turtles were found as regards navigational performance and course straightness. These findings show that magnetic cues are not essential to turtles making the return trip to the Brazilian coast. The navigational mechanisms used by these turtles remain enigmatic.
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| 7. |
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| 8. |
- Andrén, Elinor, et al.
(författare)
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Holocene history of the Baltic Sea as a background for assessing records of human impact in the sediments of the Gotland Basin
- 2000
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Ingår i: The Holocene. - : SAGE Publications. - 0959-6836 .- 1477-0911. ; 10, s. 687-702
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Tidskriftsartikel (refereegranskat)abstract
- Sediment cores from the Gotland Basin were studied for their siliceous microfossil assemblages and organic carbon content to compare recent environmental changes in the Baltic Sea with its natural long-term history. Age models were constructed using Pb-210, Cs-137 and corrected and calibrated C-14 dates. The transgression that marks the onset of the Ancylus Lake stage is recorded in the sediments as a small increase in organic carbon coinciding with a peak in diatom abundance and increased diatom diversity. A minor occurrence of brackish-freshwater diatoms is recorded in the Ancylus Lake c. 9950-9750 cal. yr BP (c. 8900-8800 C-14 yr BP), correlating with the onset of the Initial Litorina Sea in the Bornholm Basin. A high-productivity event is recorded in the end of the Post-Litorina Sea and corresponds to the Mediaeval warm event. An alteration in the diatom assemblage contemporaneous with a decrease in organic carbon, interpreted as representing a deterioration in the climate, correlates with the start of the ‘Little Ice Age’ about 850-700 cal. yr BP. A change dated to ad 1950-1960 is probably an effect of increased nutrient availability in the open Baltic Sea. This effect of eutrophication was probably caused by increased discharge of nutrients deriving from fertilizers, as the responding diatom species partly indicate a cold climate rather than a warm one, as would have been expected if this had been only a response to the warmer climate documented during the last 100 years or so.
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| 9. |
- Arvanitidis, J., et al.
(författare)
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High pressure study of the 2D polymeric phase of C60by means of raman spectroscopy
- 2000
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Ingår i: High Pressure Research. - : Taylor & Francis. - 0895-7959 .- 1477-2299. ; 18:1-6, s. 145-151
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Tidskriftsartikel (refereegranskat)abstract
- The effect of high hydrostatic pressure, up to 12 GPa, on the intramolecular phonon frequencies and the material stability of the two-dimensional tetragonal C-60 polymer has been studied by means of Raman spectroscopy in the spectral range of the radial intramolecular modes (200-800 cm(-1)). A number of new Raman modes appear in the spectrum for pressures similar to 1.4 and similar to 5.0 GPa. The pressure coefficients for the majority of the phonon modes exhibit changes to lower values at P=4.0 GPa, which may be related to a structural modification of the 2D polymer to a more isotropic phase. The peculiarities observed in the Raman spectra are reversible and the material is stable in the pressure region investigated.
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| 10. |
- Baudet, C, et al.
(författare)
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Positive and negative interactions of GDNF, NTN and ART in developing sensory neuron subpopulations, and their collaboration with neurotrophins
- 2000
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Ingår i: Development (Cambridge, England). - : The Company of Biologists. - 0950-1991 .- 1477-9129. ; 127:20, s. 4335-4344
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Tidskriftsartikel (refereegranskat)abstract
- Glial cell line-derived neurotrophic factor (GDNF), neurturin (NTN) and neublastin/artemin (ART) are distant members of the transforming growth factor β; family, and have been shown to elicit neurotrophic effects upon several classes of peripheral and central neurons. Limited information from in vitro and expression studies has also substantiated a role for GDNF family ligands in mammalian somatosensory neuron development. Here, we show that although dorsal root ganglion (DRG) sensory neurons express GDNF family receptors embryonically, they do not survive in response to their ligands. The regulation of survival emerges postnatally for all GDNF family ligands. GDNF and NTN support distinct subpopulations that can be separated with respect to their expression of GDNF family receptors, whereas ART supports neurons in populations that are also responsive to GDNF or NTN. Sensory neurons that coexpress GDNF family receptors are medium sized, whereas small-caliber nociceptive cells preferentially express a single receptor. In contrast to brain-derived neurotrophic factor (BDNF)-dependent neurons, embryonic nerve growth factor (NGF)-dependent nociceptive neurons switch dependency to GDNF, NTN and ART postnatally. Neurons that survive in the presence of neurotrophin 3 (NT3) or neurotrophin 4 (NT4), including proprioceptive afferents, Merkel end organs and D-hair afferents, are also supported by GDNF family ligands neonatally, although at postnatal stages they lose their dependency on GDNF and NTN. At late postnatal stages, ART prevents survival elicited by GDNF and NTN. These data provide new insights on the roles of GDNF family ligands in sensory neuron development.
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