| 1. |
- Holmberg, Hans-Christer, et al.
(author)
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Contribution of the legs to double-poling performance in elite cross-country skiers.
- 2006
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In: Medicine and science in sports and exercise. - : Ovid Technologies (Wolters Kluwer Health). - 0195-9131 .- 1530-0315. ; 38:10, s. 1853-60
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Journal article (peer-reviewed)abstract
- In the classical style of cross-country skiing, the double-poling (DP) technique, which is regarded as an upper-body exercise, is used on the flatter parts of a course. Limited biomechanical and physiological data are available about DP compared with other cross-country skiing techniques. The purpose of the present study was to evaluate the possible role of the lower body during DP.Eleven elite cross-country skiers performed two incremental tests using DP roller skiing at 1 degree inclination on a treadmill with or without locking the knee and ankle joints (DPLOCKED and DPFREE). Maximal and peak oxygen uptake (VO2max and VO2peak) during classic diagonal skiing and DP, respectively, were measured. In addition, heart rate, blood lactate concentration, and maximal DP velocity (Vmax) were determined. Pole-ground reaction forces and joint angles (elbow, hip, knee, and ankle) were analyzed.The skiers obtained 7.7% higher VO2peak, 9.4% higher Vmax, and 11.7% longer time to exhaustion during DPFREE compared with DPLOCKED (all P < 0.05). There was a higher heart rate and blood lactate concentration in DPLOCKED at submaximal stages (all P < 0.05), with no difference in oxygen consumption. At 85% Vmax, corresponding to approximately 81% VO2peak FREE, the differences in physiological variables were accompanied by a 13.6% higher poling frequency, a 4.9% shorter poling phase, 13.3% shorter recovery phase, and 10.9% lower relative pole force in DPLOCKED (all P < 0.05).Movements of the knee and ankle joints are an integrative part in the skillful use of the DP technique, and restriction of the motion in these joints markedly affects both biomechanical and physiological variables, impairing DP performance.
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| 2. |
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| 3. |
- Dahlqvist, Ralf, et al.
(author)
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Temporal variations of colloidal carrier phases and associated trace elements in a boreal river
- 2007
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In: Geochimica et Cosmochimica Acta. - : Elsevier BV. - 0016-7037 .- 1872-9533. ; 71:22, s. 5339-5354
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Journal article (peer-reviewed)abstract
- Elemental size distributions, from truly dissolved through colloidal to particulate, have been studied in a subarctic boreal river. The measurements, carried out during 2002, ranged from winter to summer conditions, including an intense spring flood event. Results are reported for a total of 42 elements. Size distributions were characterised using a combination of cross-flow (ultra)filtration (CFF), flow field-flow fractionation (FIFFF), and diffusive gradients in thin-films (DGT). The three techniques showed similar trends, but quantitative comparisons reveal some important differences that warrant further investigation. Previous work has identified two colloidal carrier phases in fresh waters, dominated by iron and carbon, respectively. The majority of the elements studied are associated with one or both of these colloidal carrier phases. The exceptions are the alkali metals and several anions that are only very weakly associated with colloidal material, and which therefore occur mainly as truly dissolved material (< 1 kDa in molecular weight). We discuss the likely origin for the two colloidal carrier phases and consider how associated trace elements fit into the geochemical framework. The relative affinities of the elements for iron and carbon colloidal carrier phases are related to their chemistries, and are compared with earlier data from the Delsjo Creek in southern Sweden. Elemental colloidal concentrations show strong seasonal variations related to changes in the colloidal carrier phase(s) with which they associate. In particular, many elements show a strong spring maximum in colloidal concentrations associated with the strong maximum in colloidal carbon concentration during the spring flood.
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| 4. |
- Ecke, Frauke, et al.
(author)
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Landscape structure and the long-term decline of cyclic grey-sided voles in Fennoscandia
- 2010
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In: Landscape Ecology. - : Springer. - 0921-2973 .- 1572-9761. ; 25:4, s. 551-560
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Journal article (peer-reviewed)abstract
- Changes in forest landscape structure have been suggested as a likely contributing factor behind the long-term decline in the numbers of cyclic grey-sided voles (Clethrionomys rufocanus) in northern Fennoscandian lowland regions in contrast to mountain regions due to the absence of forest management in the mountains. This study, for the first time, formally explored landscape structure in 29 lowland (LF) and 14 mountain forest (MF) landscapes (each 2.5 x 2.5 km) in northern Sweden, and related the results to the cumulated spring trapping index of the grey-sided vole in 2002-2006. The grey-sided vole showed striking contrasts in dynamics close in space and time. The MF landscapes were characterized by larger patches and less fragmentation of preferred forest types. The grey-sided vole was trapped in all of 14 analyzed MF landscapes but only in three out of 29 of the LF landscapes. MF and LF landscapes with grey-sided vole occurrence were characterized by similar focal forest patch size (mean 357 ha, minimum 82 ha and mean 360 ha, minimum 79 ha, respectively). In contrast, these MF compared to the LF landscapes were characterized by larger patches of preferred forest types and less fragmented preferred forest types and by a lower proportion of clear-cut areas. The present results suggest that landscape structure is important for the abundance of grey-sided voles in both regions. However, in the mountains the change from more or less seasonal dynamics to high-amplitude cycles between the mid 1990s and 2000s cannot be explained by changes in landscape structure.
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| 5. |
- Holmberg, Hans-Christer, et al.
(author)
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Reliability and validity of a new double poling ergometer for cross-country skiers
- 2008
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In: Journal of Sports Sciences. - : Informa UK Limited. - 0264-0414 .- 1466-447X. ; 26:2, s. 171-179
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Journal article (peer-reviewed)abstract
- Thirty-eight competitive cross-country skiers were divided into three groups to assess the reliability and validity of a new double poling ergometer. Group A (n = 22) performed two maximal 60-s tests, Group B (n = 8) repeated peak oxygen uptake tests on the double poling ergometer, and Group C (n = 8) performed a maximal 6-min test on the double poling ergometer and a double poling time-trial on snow. The correlation between the power calculated at the flywheel and the power applied at the base of the poles was r = 0.99 (P < 0.05). The power at the poles was 50 - 70% higher than that at the flywheel. There was a high test - retest reliability in the two 60-s power output tests (coefficient of variation = 3.0%) and no significant difference in peak oxygen uptake in the two 6-min all-out tests (coefficient of variation = 2.4%). There was a strong correlation between the absolute (W) and relative power (W . kg(-1)) output in the 6-min double poling ergometer test and the double poling performance on snow (r = 0.86 and 0.89 respectively; both P < 0.05). In conclusion, our results show that the double poling ergometer has both high reliability and validity. However, the power calculated at the flywheel underestimated the total power produced and needs to be corrected for in ergonomic estimations.
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| 6. |
- Boman, Christoffer, et al.
(author)
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Stove performance and emission characteristics in residential wood log and pellet combustion : Part 1: Pellet stoves
- 2011
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In: Energy & Fuels. - : American Chemical Society (ACS). - 0887-0624 .- 1520-5029. ; 25:1, s. 307-314
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Journal article (peer-reviewed)abstract
- Stove performance, characteristics and quantities of gaseous and particulate emissions were determined for two different pellet stoves, varying fuel load, pellet diameter and chimney draught. This approach aimed at covering variations in emissions from stoves in use today. The extensive measurement campaign included CO, NOx, organic gaseous carbon, volatile organic compounds (VOCs), polycyclic aromatic hydrocarbons (PAHs), total particulate matter (PMtot) as well as particle mass and number concentrations, size distributions and inorganic composition. At high load, most emissions were similar. For stove B, operating at high residual oxygen and solely with primary air, the emissions of PMtot and particle numbers were higher while the particles were smaller. Lowering the fuel load, the emissions of CO and hydrocarbons increased dramatically for stove A, which operated continuously also at lower fuel loads. On the other hand for stove B, which had intermittent operation at lower fuel loads, the emissions of hydrocarbons increased only slightly lowering the fuel load, while CO emissions increased sharply, due to high emissions at the end of the combustion cycle. Beside methane, dominating VOCs were ethene, acetylene and benzene and the emissions of VOC varied in the range 1.1-47 mg/MJfuel. PAH emissions (2-340 µg/MJfuel) were generally dominated by phenantrene, fluoranthene and pyrene. PMtot (15-45 mg/MJfuel) were in all cases dominated by fine particles with mass median diameters in the range 100-200 nm, peak mobility diameters of 50-85 nm and number concentrations in the range 4×1013- 3×1014 particles/MJfuel. During high load conditions the particulate matter was totally dominated by inorganic particles at 15-25 mg/MJfuel consisting of potassium, sodium, sulfur and chlorine, in the form of K2SO4, K3Na(SO4)2 and KCl. The study shows that differences in operation and modulation principles for the tested pellet stoves, relevant for appliances in use today, will affect the performance and emissions significantly, although with lower scattering in the present study compared to compiled literature data.
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| 7. |
- Eriksson, Darek M., et al.
(author)
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A framework for the modelling of tempo-spatial enterprise
- 2007
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In: International Journal of Applied Systemic Studies. - 1751-0589 .- 1751-0597. ; 1:3, s. 231-247
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Journal article (peer-reviewed)abstract
- A framework for the modelling of enterprise operations is presented, aiming at enabling a conception of enterprise operations in three explicitly aligned perspectives: its what, or morphology; its when, or temporal position; its where, or spatial position. It is derived from the precepts of a General Systems Theory and its General Process Theory. The practical and empirical benefit of this framework is indicated by a real-life case, a so-called 'Transatlantic Shopping Process', where the models constructed enable management of complexities emerging from enterprise operations.
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| 8. |
- Runardotter, Mari, et al.
(author)
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Being an Archivist in our Times - Trying to Manage Long-Term Digital Preservation
- 2007
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In: International Journal of Public Information Systems. - Sundsvall : Mittuniversitetet. - 1653-4360. ; 3:2, s. 47-61
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Journal article (peer-reviewed)abstract
- Information technology offers the possibility to produce and archive more recorded information than ever before. Thus it is has become feasible to preserve and have access to information in almost unlimited amounts. In sharp contrast, the situation today suggests that societal data has become significantly less accessible than was previously the case. This is both ironic and tragic. In this paper, we recognize that the cultural heritage is at risk, given current circumstances as revealed through observation and dialogue with an archivist. While there are many projects, cultural heritage institutions, government agencies and private enterprises involved in an ambitious research agenda, the majority of these are focussed on technical solutions. In contrast, we provide an indepth point of view of an archivist who is expected to preserve information in order to safeguard the long-term preservation of the cultural heritage. This report reveals the challenges as well as the systemic implications related to the full implementation of the Archival Information Systems guidelines, that fully involve archivists and users in systems design features and functionalities, in order to enable the advancement of longterm digital preservation.
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| 9. |
- Larsson, Peter, 1979-, et al.
(author)
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Calculating carbon nanotube–catalyst adhesion strengths
- 2007
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In: Physical Review B. Condensed Matter and Materials Physics. - : American Physical Society. - 1098-0121 .- 1550-235X. ; 75:11
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Journal article (peer-reviewed)abstract
- Density-functional theory is used to assess the validity of modeling metal clusters as single atoms or rings of atoms when determining adhesion strengths between clusters and single-walled carbon nanotubes (SWNTs). Representing a cluster by a single atom or ring gives the correct trends in SWNT-cluster adhesion strengths (Fe ≈ Co > Ni), but the single-atom model yields incorrect minimum-energy structures for all three metals. We have found that this is because of directional bonding between the SWNT end and the metal cluster, which is captured in the ring model but not by the single atom. Hence, pairwise potential models that do not describe directional bonding correctly, and which are commonly used to study these systems, are expected to give incorrect minimum-energy structures.
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| 10. |
- Gustafsson, Magnus
(author)
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Diatom-diatom interactions with light : Applications and line shape theoretical aspects
- 2008
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In: Spectral line shapes, volume 15. - Melville, NY : American Institute of Physics (AIP). - 9780735405882 ; 15, s. 297-301
-
Conference paper (peer-reviewed)abstract
- Recent advances in calculations of collision-induced absorption- and Raman-spectra in pure diatomic gases are presented. An extensive calculation of H2-H2 absorption from 40 K to 400 K has provided improved understanding of the atmosphere of Uranus. A highly advanced close-coupling calculation of H2-H2 light scattering has verified that the line shapes are affected by interference between the permanent H2 and the H2-H2 interaction-induced polarizabilities. A few directions that the research in astrophysical applications of collision-induced absorption is taking are also described. For instance, H2-H 2 dipole and potential surfaces for vibrations higher than v = 1 are currently being developed to enable simulations of collision-induced absorption at temperatures relevant for white dwarf atmospheres. For low temperature N 2-N2 absorption there is unresolved discrepancy between measurement and simulation. A possible solution to this puzzle is suggested
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