| 21. |
|
|
| 22. |
|
|
| 23. |
- Forsman, Anders, et al.
(författare)
-
Fitness benefits of diverse offspring in pygmy grasshoppers
- 2007
-
Ingår i: Evolutionary Ecology Research. ; 9:8, s. 1305-1318
-
Tidskriftsartikel (refereegranskat)abstract
- Question: Do females obtain fitness benefits from an increase in offspring diversity?Hypotheses: Polyandry increases offspring diversity within a clutch. Increased offspring diversity will reduce competition among siblings (manifested as increased mean survival in more diverse families) and the probability that all offspring might be ill-suited to future conditions (manifested as lower variance in survival in diverse families).Organisms: Pygmy grasshoppers, Tetrix subulata and Tetrix: undulata, that are polymorphic for colour pattern.Field site: South-central Sweden.Methods: We varied the number of mates provided to colour polymorphic pygmy grasshoppers. We reared families in either warm or cold conditions using a split-brood design.Conclusions: The colour morph diversity of broods increased with the number of experimentally provided mates. Colour morphs represent alternative strategies that differ in body size, physiology, behaviour, and life history. Survival increased with increasing sibling diversity, supporting the hypothesis that different morphs avoid competition by using different subsets of available resources. Homogeneous families (in which all siblings belong to the same or only a few colour morphs) varied more in survival than did families with diverse siblings, supporting the hypothesis that morphs vary in their ability to cope with and utilize different resources.
|
|
| 24. |
- Fröberg, Andreas, 1985, et al.
(författare)
-
Awareness of current recommendations and guidlines regarding strength training for youth
- 2014
-
Ingår i: International Journal of Adolescent Medicine and Health. - : Walter de Gruyter GmbH. - 0334-0139 .- 2191-0278. ; 26:4, s. 517-523
-
Tidskriftsartikel (refereegranskat)abstract
- Aim: Physical conditioning of youth has always been a controversial topic as it raises ethical, physiological, and medical issues. Current recommendations and guidelines suggest that strength training is a relatively safe and worthwhile method in conditioning youth. This, however, requires well-informed coaches who follow age-appropriate strength training recommendations and guidelines, compiles well-designed strength training programs, and provides qualified supervision and instructions. The purpose of this study was to investigate coaches’ awareness of current recommendations and guidelines regarding strength training for youth.Method: A total of 39 football (US: soccer) coaches (34 males and 5 females) training boys in age groups 8–12 years were included in this study. Data were collected using an attitude statement questionnaire, and the assertions were based upon current recommendations and guidelines.Results: The results revealed significant differences among coaches in terms of knowledge of important aspects of strength training for youth.Conclusions: The results suggested that coaches in the present study were not aware of the latest recommendations and guidelines regarding strength training for youth.
|
|
| 25. |
- Fröberg, Andreas, 1985, et al.
(författare)
-
Ledare tveksamma till styrketräningsråd för barn
- 2011
-
Ingår i: Svensk Idrottsforskning : Organ för Centrum för Idrottsforskning. - Stockholm : Centrum för idrottsforskning (CIF). - 1103-4629. ; :4, s. 47-50
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)
|
|
| 26. |
- Fröberg, Andreas, et al.
(författare)
-
Ledare tveksamma tillstyrketräningsråd för barn
- 2011
-
Ingår i: Svensk Idrottsforskning. - Stockholm : Centrum för idrottsforskning (CIF). - 1103-4629. ; :4, s. 47-50
-
Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- I Sverige har vi haft en försiktig hållning till styrketräning för barn.År 2009 kom Riksidrottsförbundet med rekommendationer som imotsats till tidigare tydligt förespråkar styrketräning. I en pilotstudievisar vi bland annat att fotbollsledare från olika divisioner trots detär oeniga om vad som egentligen är det rätta.
|
|
| 27. |
|
|
| 28. |
- Källman, Hans-Erik, et al.
(författare)
-
Source modeling for Monte Carlo dose calculation of CT examinations with a radiotherapy treatment planning system
- 2016
-
Ingår i: Medical physics (Lancaster). - : Wiley. - 0094-2405. ; 43:11, s. 6118-6128
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose:Radiation dose to patients undergoing examinations with Multislice Computed Tomography (MSCT) as well as Cone Beam Computed Tomography (CBCT) is a matter of concern. Risk management could benefit from efficient replace rational dose calculation tools. The paper aims to verify MSCT dose calculations using a Treatment Planning System (TPS) for radiotherapy and to evaluate four different variations of bow-tie filter characterizations for the beam model used in the dose calculations.Methods:A TPS (RayStation™, RaySearch Laboratories, Stockholm, Sweden) was configured to calculate dose from a MSCT (GE Healthcare, Wauwatosa, WI, USA). The x-ray beam was characterized in a stationary position the by measurements of the Half-Value Layer (HVL) in aluminum and kerma along the principal axes of the isocenter plane perpendicular to the beam. A Monte Carlo source model for the dose calculation was applied with four different variations on the beam-shaping bow-tie filter, taking into account the different degrees of HVL information but reconstructing the measured kerma distribution after the bow-tie filter by adjusting the photon sampling function. The resulting dose calculations were verified by comparison with measurements in solid water as well as in an anthropomorphic phantom.Results:The calculated depth dose in solid water as well as the relative dose profiles was in agreement with the corresponding measured values. Doses calculated in the anthropomorphic phantom in the range 26–55 mGy agreed with the corresponding thermo luminescence dosimeter (TLD) measurements. Deviations between measurements and calculations were of the order of the measurement uncertainties. There was no significant difference between the different variations on the bow-tie filter modeling.Conclusions:Under the assumption that the calculated kerma after the bow-tie filter replicates the measured kerma, the central specification of the HVL of the x-ray beam together with the kerma distribution can be used to characterize the beam. Thus, within the limits of the study, a flat bow-tie filter with an HVL specified by the vendor suffices to calculate the dose distribution. The TPS could be successfully configured to replicate the beam movement and intensity modulation of a spiral scan with dose modulation, on the basis of the specifications available in the metadata of the digital images and the log file of the CT.
|
|
| 29. |
- Söderberg, Jonas, et al.
(författare)
-
Evaluation of a photon dose calculation algorithm applied to fast-neutron therapy treatment planning using a neutron pencil-beam kernel
-
Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Treatment planning in fast-neutron therapy is commonly performed using conventional treatment planning systems designed for photon beam therapy. In this work Monte Carlo derived neutron pencil-beam kernels in water were parameterised using an algorithm developed for photon beams and implemented in the TMS photon dose treatment planning system. A rectangular fast-neutron fluence spectrum with energies 0-40 Me V was used. Central axis depth doses and lateral dose distributions were calculated by the dose planning system and compared with corresponding dose distributions using direct Monte Carlo calculations in homogeneous water phantom and heterogeneous phantoms. Good agreement was found in both lateral and depth dose distributions in a homogeneous water phantom. However, considerable deviations were obtained between absorbed doses calculated by the dose planning system and the Monte Carlo calculated absorbed doses in heterogeneous media. The multipurpose Monte Carlo code FLUKA was used both for the calculation of the pencil-beam kernel and in the direct calculations of absorbed dose in the phantom.
|
|
| 30. |
- Söderberg, Jonas, et al.
(författare)
-
Monte Carlo evaluation of a photon pencil kernel algorithm applied to fast neutron therapy treatment planning
- 2003
-
Ingår i: Physics in Medicine and Biology. - : IOP Publishing. - 0031-9155 .- 1361-6560. ; 48:20, s. 3327-3344
-
Tidskriftsartikel (refereegranskat)abstract
- When dedicated software is lacking, treatment planning for fast neutron therapy is sometimes performed using dose calculation algorithms designed for photon beam therapy. In this work Monte Carlo derived neutron pencil kernels in water were parametrized using the photon dose algorithm implemented in the Nucletron TMS (treatment management system) treatment planning system. A rectangular fast-neutron fluence spectrum with energies 0–40 MeV (resembling a polyethylene filtered p(41)+ Be spectrum) was used. Central axis depth doses and lateral dose distributions were calculated and compared with the corresponding dose distributions from Monte Carlo calculations for homogeneous water and heterogeneous slab phantoms. All absorbed doses were normalized to the reference dose at 10 cm depth for a field of radius 5.6 cm in a 30 × 40 × 20 cm3 water test phantom. Agreement to within 7% was found in both the lateral and the depth dose distributions. The deviations could be explained as due to differences in size between the test phantom and that used in deriving the pencil kernel (radius 200 cm, thickness 50 cm). In the heterogeneous phantom, the TMS, with a directly applied neutron pencil kernel, and Monte Carlo calculated absorbed doses agree approximately for muscle but show large deviations for media such as adipose or bone. For the latter media, agreement was substantially improved by correcting the absorbed doses calculated in TMS with the neutron kerma factor ratio and the stopping power ratio between tissue and water. The multipurpose Monte Carlo code FLUKA was used both in calculating the pencil kernel and in direct calculations of absorbed dose in the phantom.
|
|
