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| 2. |
- Markljung, Ellen, 1978-
(författare)
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QTL Analysis in the Pig : From the Identification of Quantitative Trait Loci to the Understanding of Molecular Mechanisms
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Domestic pigs have become very different form the wild ancestors they originate from. Selection for muscle growth and meat quality has made the pig a good model for genetic studies of muscle development.The first part of this thesis presents a genome-wide scan for quantitative trait loci (QTL) in a cross between Landrace and Hampshire pigs. Traits such as body composition, fat deposition, body length, meat quality and weight measurements of individual muscles were investigated. In total we identified 15 different QTLs that reached genome-wide significance. The three most significant QTLs were for carcass length on chromosome 17 and two overlapping QTLs on chromosome 1 for body composition and weight of M. biceps femoris, respectively. A strong candidate gene for the body composition QTL is melanocortin 4 receptor (MC4R). We also identified several QTLs for sizes of different muscles, fat deposition and meat quality traits.In a previous study using a cross between the domestic Large White and wild boar, the mutation underlying a major QTL for muscle growth and fat deposition was identified as a single nucleotide substitution (QTN) in intron 3 of the IGF2 gene. The QTN disrupts the binding of a repressor affecting IGF2 mRNA expression. In the second part of this thesis, the identification of the repressor is presented. The repressor, named ZBED6, is a previously unknown mammalian member of the BED-domain protein family. We could show that Zbed6 specifically binds the wild-type but not the mutated sequence surrounding the QTN. Further studies of silenced Zbed6 in the mouse myoblast cell line C2C12 showed that it represses transcription in a luciferase reporter assay and affects Igf2 mRNA transcription and proliferation. ZBED6 shows very high sequence conservation and has a broad tissue distribution of expression suggesting that ZBED6 also has important biological function outside the muscle cell.
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| 3. |
- Adolfsson, Annsofie, 1960-, et al.
(författare)
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Miscarriage : Evidence Based Information for the Web and Its Development Procedure
- 2015
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Ingår i: Advances in Sexual Medicine. - Irvine, USA : Scientific Research Publishing. - 2164-5191 .- 2164-5205. ; 5:4, s. 89-110
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Tidskriftsartikel (refereegranskat)abstract
- Objective: The aim of this paper is to describe the process of developing web information on miscarriage based on scientific evidence, for women and couples in Sweden experiencing miscarriage. Method: A participatory design was used which included researchers, professional xperts and users. A participatory design was used involving researchers, professional experts and users. The information was developed in six stages: 1) identifying the needs of information; 2) identifying and constructing the main areas of information and its paths; 3) identifying and inviting experts for revision; 4) developing the text; 5) reviewing the text; 6) design and structuring for adaption to website. Results: The text of information developed gradually based on the seven steps. The final text comprised three parts: 1) what is miscarriage; 2) experiences of miscarriage; 3) processing and lanning for new pregnancy. Conclusion: Using participatory design was time and resource consuming, however it was functional for producing appropriate information for the target group. The developed evidence based facts text is assumed to be a complement to the information that is provided by the health care system.
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| 4. |
- Aikio, A T, et al.
(författare)
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On the origin of the high-altitude electric field fluctuations in the auroral zone
- 1996
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Ingår i: Journal of Geophysical Research. - 0148-0227 .- 2156-2202. ; 101:A12, s. 27157-27170
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Tidskriftsartikel (refereegranskat)abstract
- Intense fluctuations in the electric field at high altitudes in the auroral zone are frequently measured by the Viking satellite. We have made an analysis of the origin of electric and magnetic fluctuations in the frequency range of 0.1 - 1 Hz by assuming four different sources for the signals: (I) spatial structures, (2) spatial structures with a parallel potential drop below the satellite, (3) traveling; shear Alfven waves, and (4) interfering shear Alfven waves. We will shaw that these different sources of the signals may produce similar amplitude ratios and phase differences between the perpendicular electric and magnetic fields. Since the different sources have different frequency dependencies, this can be used as an additional test if the signals are broadband. In other cases, additional information is needed, for example, satellite particle measurements or ground; magnetic measurements. The ideas presented in the theory were tested for one Viking eveningside pass over Scandinavia, where ground-based magnetometer and EISCAT radar measurements were available. The magnetic conditions were active during this pass and several interfering shear Alfven waves were found. Also, a spatial structure with a parallel potential drop below the satellite was identified. The magnitude of the 10-km-wide potential drop was at least 2 kV and the upward field-aligned current 26 mu A m(-2) (value mapped to the ionospheric level). The held-aligned conductance was estimated as 1.3 - 2.2x10(-8) S m(-2).
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| 5. |
- Aikio, A. T., et al.
(författare)
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Temporal evolution of two auroral arcs as measured by the Cluster satellite and coordinated ground-based instruments
- 2004
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Ingår i: Annales Geophysicae. - : Copernicus GmbH. - 0992-7689 .- 1432-0576. ; 22:12, s. 4089-4101
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Tidskriftsartikel (refereegranskat)abstract
- The four Cluster s/c passed over Northern Scandinavia on 6 February 2001 from south-east to north-west at a radial distance of about 4.4 R-E in the post-midnight sector. When mapped along geomagnetic field lines, the separation of the spacecraft in the ionosphere was confined to within 110 km in latitude and 50 km in longitude. This constellation allowed us to study the temporal evolution of plasma with a time scale of a few minutes. Ground-based instrumentation used involved two all-sky cameras, magnetometers and the EISCAT radar. The main findings were as follows. Two auroral arcs were located close to the equatorward and poleward edge of a large-scale density cavity, respectively. These arcs showed a different kind of a temporal evolution. (1) As a response to a pseudo-breakup onset, both the up- and downward field-aligned current (FAC) sheets associated with the equatorward arc widened and the total amount of FAC doubled in a time scale of 1-2 min. (2) In the poleward arc, a density cavity formed in the ionosphere in the return (downward) current region. As a result of ionospheric feedback, a strongly enhanced ionospheric southward electric field developed in the region of decreased Pedersen conductance. Furthermore, the acceleration potential of ionospheric electrons, carrying the return current, increased from 200 to 1000 eV in 70 s, and the return current region widened in order to supply a constant amount of return current to the arc current circuit. Evidence of local acceleration of the electron population by dispersive Alfven waves was obtained in the upward FAC region of the poleward arc. However, the downward accelerated suprathermal electrons must be further energised below Cluster in order to be able to produce the observed visible aurora. Both of the auroral arcs were associated with broad-band ULF/ELF (BBELF) waves, but they were highly localised in space and time. The most intense BBELF waves were confined typically to the return current regions adjacent to the visual arc, but in one case also to a weak upward FAC region. BBELF waves could appear/disappear between s/c crossings of the same arc separated by about 1 min.
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| 6. |
- Alm, Love
(författare)
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Cluster investigations of the extent and altitude distribution of the auroral density cavity
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The auroral density cavity constitutes the boundary between the cold, dense ionospheric plasma and the hot, tenuous plasma sheet plasma. The auroral density cavity is characterized by low electron density and particle populations modified by parallel electric fields. Inside the cavity the electron densities can be as much as a factor 100-1000 lower than same altitude outside the cavity.The Cluster mission's wide range of instruments, long lifetime and ability to make multi-spacecraft observations has been very successful. Over its 15 year lifespan, the Cluster satellites have gathered data on auroral density cavities over a large altitude range and throughout an entire solar cycle, providing a vast data material.The extent of the density cavity and acceleration region is large compared to the typical altitude coverage of a satellite crossing the cavity. This makes it difficult to produce a comprehensive altitude/density profile from a single crossing. In order to facilitate comparisons between data from different events, we introduce a new reference frame, pseudo altitude. Pseudo altitude describes the satellites' position relative to the acceleration region, as opposed to relative to the Earth. This pseudo altitude is constructed by dividing the parallel potential drop below the satellite with the total parallel potential drop. A pseudo altitude of 0 corresponds to the bottom of the acceleration region and a pseudo altitude of 1 to the top of the acceleration region. As expected, the pseudo altitude increases with altitude. The electron density exhibits an anti-correlation with the pseudo altitude, the density becomes lower close to the upper edge of the acceleration region. The upper edge of the acceleration region is located between a geocentric altitude of 4.375 and 5.625 RE. Above the upper edge of the acceleration region, the electron density continues to decrease for the entire range of the study, 3.0-6.5 RE. This is much further than the geocentric altitude range of 2-3 RE which is suggested by previous models. We can conclude that the auroral density cavity is not confined by the auroral acceleration region, as suggested by previous models, and may extend all the way to the plasma sheet.
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| 7. |
- Alm, L., et al.
(författare)
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Differing Properties of Two Ion-Scale Magnetopause Flux Ropes
- 2018
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Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 123:1, s. 114-131
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Tidskriftsartikel (refereegranskat)abstract
- In this paper, we present results from the Magnetospheric Multiscale constellation encountering two ion-scale, magnetopause flux ropes. The two flux ropes exhibit very different properties and internal structure. In the first flux rope, there are large differences in the currents observed by different satellites, indicating variations occurring over sub-d(i) spatial scales, and time scales on the order of the ion gyroperiod. In addition, there is intense wave activity and particle energization. The interface between the two flux ropes exhibits oblique whistler wave activity. In contrast, the second flux rope is mostly quiescent, exhibiting little activity throughout the encounter. Changes in the magnetic topology and field line connectivity suggest that we are observing flux rope coalescence.
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| 8. |
- Alm, L., et al.
(författare)
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EDR signatures observed by MMS in the 16 October event presented in a 2-D parametric space
- 2017
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Ingår i: Journal of Geophysical Research - Space Physics. - : AMER GEOPHYSICAL UNION. - 2169-9380 .- 2169-9402. ; 122:3, s. 3262-3276
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Tidskriftsartikel (refereegranskat)abstract
- We present a method for mapping the position of satellites relative to the X line using the measured B-L and B-N components of the magnetic field and apply it to the Magnetospheric multiscale (MMS) encounter with the electron diffusion region (EDR) which occurred on 13:07 UT on 16 October 2015. Mapping the data to our parametric space succeeds in capturing many of the signatures associated with magnetic reconnection and the electron diffusion region. This offers a method for determining where in the reconnection region the satellites were located. In addition, parametric mapping can also be used to present data from numerical simulations. This facilitates comparing data from simulations with data from in situ observations as one can avoid the complicated process using boundary motion analysis to determine the geometry of the reconnection region. In parametric space we can identify the EDR based on the collocation of several reconnection signatures, such as electron nongyrotropy, electron demagnetization, parallel electric fields, and energy dissipation. The EDR extends 2-3km in the normal direction and in excess of 20km in the tangential direction. It is clear that the EDR occurs on the magnetospheric side of the topological X line, which is expected in asymmetric reconnection. Furthermore, we can observe a north-south asymmetry, where the EDR occurs north of the peak in out-of-plane current, which may be due to the small but finite guide field.
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| 9. |
- Alm, Love, et al.
(författare)
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Electron density and parallel electric field distribution of the auroral density cavity
- 2015
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Ingår i: Journal of Geophysical Research. - : American Geophysical Union (AGU). - 0148-0227 .- 2156-2202. ; 120:11, s. 9428-9441
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Tidskriftsartikel (refereegranskat)abstract
- We present an event study in which Cluster satellites C1 and C3 encounters the flux tube of a stable auroral arc in the pre-midnight sector. C1 observes the mid cavity, while C3 enters the flux tube of the auroral arc at an altitude which is below the acceleration region, before crossing into the top half of the acceleration region. This allows us to study the boundary between the ionosphere and the density cavity, as well as large portion of the upper density cavity. The position of the two satellites, in relation to the acceleration region, is described using a pseudo altitude derived from the distribution of the parallel potential drop above and below the satellites.The electron density exhibits an anti-correlation with the pseudo altitude, indicating that the lowest electron densities are found near the top of the density cavity. Over the entire pseudo altitude range, the electron density distribution is similar to a planar sheath, formed out of a plasma sheet dominated electron distribution, in response to the parallel electric field of the acceleration region. This indicates that the parallel electric fields on the ionosphere-cavity boundary, as well as the mid cavity parallel electric fields, are part of one unified structure rather than two discrete entities.The results highlight the strong connection between the auroral density cavity and auroral acceleration as well as the necessity of studying them in a unified fashion.
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| 10. |
- Alm, Love, et al.
(författare)
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In situ observations of density cavities extending above the auroral acceleration region
- 2014
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Ingår i: Journal of Geophysical Research - Space Physics. - : American Geophysical Union (AGU). - 2169-9380 .- 2169-9402. ; 119:7, s. 5286-5294
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Tidskriftsartikel (refereegranskat)abstract
- The uppermost part of a stable potential structure in the auroral acceleration region was studied using simultaneous observations of Cluster satellites C1 and C3. Both satellites observe a monotonically decreasing electron density as they ascend through the auroral acceleration region. As C1 exits the top of the auroral acceleration region, the electron densities continue to decrease, and the minimum electron density is reached 14 km above the upper edge of the auroral acceleration region. The electron density does not return to noncavity values until the spacecraft exits the potential structure's flux tube. The data indicate that the auroral density cavity is not confined by the potential structure and may extend above the auroral acceleration region.
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