Long-term species balance in sympatric populations: implications for Atlantic salmon and brown trout

The factors determining regional adaptation in salmonids are still unclear, but it is known that changes in their habitat imply changes in their population structure. In this preliminary study we integrate habitat data, molecular analyses (from both nuclear microsatellite and mitochondrial loci) and life-history traits (measured on archaeological vertebrae and modern scales) of two sympatric salmonid species: Atlantic salmon and brown trout. We propose that water temperature and geological characteristics changed the biogeographic patterns of these species through asymmetric migration and different (but complementary) population growth rates. As a consequence, differences in a life-history trait (mean number of years at sea) and population sizes were detected between regions, suggesting a process of substitution of Atlantic salmon by brown trout

Long-term species balance in sympatric populations: implications for Atlantic salmon and brown trout

The factors determining regional adaptation in salmonids are still unclear, but it is known that changes in their habitat imply changes in their population structure. In this preliminary study we integrate habitat data, molecular analyses (from both nuclear microsatellite and mitochondrial loci) and life-history traits (measured on archaeological vertebrae and modern scales) of two sympatric salmonid species: Atlantic salmon and brown trout. We propose that water temperature and geological characteristics changed the biogeographic patterns of these species through asymmetric migration and different (but complementary) population growth rates. As a consequence, differences in a life-history trait (mean number of years at sea) and population sizes were detected between regions, suggesting a process of substitution of Atlantic salmon by brown trout

Evaluación de la calidad de los exámenes de tomografía computarizada de columna lumbar en la indicación de hernia discal

Aim: To apply quality criteria of computerized tomography (CT) of the lumbar spine as defined in the European Guidelines, in four hospitals of the Community of Madrid, using spiral CT (SCT) in the clinical indication of disc hernia. Materials and Methods: There were selected 20 lumbar spine studies from each center. These were evaluated by five independent radiologists in order to determine the degree of adherence to criteria quality of the European Guidelines for such studies. Dosimetric measurements were performed in parallel in order to estimate values of CT dose index (CTDIw), dose length product (DLP) and effective dose for each patient. Results: The results showed a high degree of adherence to image quality criteria in four centers (97-100)%. Median CTDIw values per center were (34-60) mGy; those of DLP were (242-499) mGy·cm, and those of effective dose between 4 and 7 mSv. Conclusion: There has been a good adherence to the quality criteria. In some cases, however, it seems that doses could very well be reduced through a re-thinking of the protocols

Evaluación de la calidad de imagen y de la dosis en exámenes de TC helicoidal de tórax en pacientes con carcinoma de pulmón. Resultados preliminares.

We have applied criteria for CT quality defined in the European Guidelines to a sample of thoracic CT examinations - for the indication of pulmonary carcinoma - of 5 institutions of the Community of Madrid that have spiral CT equipment. The selected examinations have been evaluated independently by five radiologists to determine the degree of adherence to the quality criteria for image defined in the Guideliness for examinations of general thorax. Dosimetric measurements carried out in parallel have served to estimate the values of CT (CTDIw) dose indices, dose-length product (DLP) and effective dose for every patient. The results show a high global adherence to the quality criteria (96%), with averages per institution being between 94% (in two institutions) and 98% (in three institutions). There are 10 of 16 criteria that are adhered to in all examinations of the sample; those which are not adhered to systematically are: two of visualization (1.1 and 1.4), with 92-96% fulfillment, and four of critical reproduction (2.6; 2.8; 2.9 and 2.10), with percentages of adherence between 91% and 96%. The average CTDIw values per institution are in the interval 12.9-19.1 mGy; those of DLP between 263 and 577 mGy cm and those of effective dose between 4.2 and 9.2 mSv. The DLP-image quality correlation in institutions with the best image quality was null in two of them and direct and moderate in the third. In both institutions with the poorest image quality, the correlation was inverse and moderate in one and direct and weak in the other. Reasons for these results are analyzed, as well as possible ways of optimizing quality in relation to dose and parameters used