University of Southern Denmark

About: University of Southern Denmark is a education organization based out in Odense, Syddanmark, Denmark. It is known for research contribution in the topics: Population & Randomized controlled trial. The organization has 11928 authors who have published 37918 publications receiving 1258559 citations. The organization is also known as: SDU.

Animal evolution, bioturbation, and the sulfate concentration of the oceans.

Abstract: As recognized already by Charles Darwin, animals are geobiological agents. Darwin observed that worms aerate and mix soils on a massive scale, aiding in the decomposition of soil organic matter. A similar statement can be made about marine benthic animals. This mixing, also known as bioturbation, not only aides in the decomposition of sedimentary organic material, but as contended here, it has also significantly influenced the chemistry of seawater. In particular, it is proposed that sediment mixing by bioturbating organisms resulted in a severalfold increase in seawater sulfate concentration. For this reason, the evolution of bioturbation is linked to the significant deposition of sulfate evaporate minerals, which is largely a phenomena of the Phanerozoic, the last 542 million years and the time over which animals rose to prominence.

Magnetic resonance imaging and low back pain in adults: a diagnostic imaging study of 40-year-old men and women

Abstract: Study design Cross-sectional cohort study of a general population. Objective To investigate "abnormal" lumbar spine magnetic resonance imaging (MRI) findings, and their prevalence and associations with low back pain (LBP). Summary of background data The clinical relevance of various "abnormal" findings in the lumbar spine is unclear. Distinguishing between inevitable age-related findings and degenerative findings with deleterious consequences is a challenge. Methods Lumbar spine MRI was obtained in 412, 40-year-old individuals. Predefined "abnormal" MRI findings were interpreted without any knowledge of patient symptoms. Associations between MRI abnormalities and LBP were calculated using odds ratios. The "overall picture" of each MRI finding was established on the basis of the frequencies, diagnostic values, and the strength and consistency of associations. Results Most "abnormal" MRI findings were found at the lowest lumbar levels. Irregular nucleus shape and reduced disc height were common (>50% of individuals). Relatively common (25% to 50%) were hypointense disc signal, anular tears, high intensity zones, disc protrusions, endplate changes, zygapophyseal joint degeneration, asymmetry, and foraminal stenosis. Nerve root compromise, Modic changes, central spinal stenosis, and anterolisthesis/retrolisthesis were rare ( 4). Significantly positive associations with all LBP variables were seen for hypointense disc signals, reduced disc height, and Modic changes. All disc "abnormalities" except protrusion were moderately associated with LBP during the past year. Conclusion Most degenerative disc "abnormalities" were moderately associated with LBP. The strongest associations were noted for Modic changes and anterolisthesis. Further studies are needed to define clinical relevance.

Causal Inference and Observational Research: The Utility of Twins

Abstract: Valid causal inference is central to progress in theoretical and applied psychology. Although the randomized experiment is widely considered the gold standard for determining whether a given exposure increases the likelihood of some specified outcome, experiments are not always feasible and in some cases can result in biased estimates of causal effects. Alternatively, standard observational approaches are limited by the possibility of confounding, reverse causation, and the nonrandom distribution of exposure (i.e., selection). We describe the counterfactual model of causation and apply it to the challenges of causal inference in observational research, with a particular focus on aging. We argue that the study of twin pairs discordant on exposure, and in particular discordant monozygotic twins, provides a useful analog to the idealized counterfactual design. A review of discordant-twin studies in aging reveals that they are consistent with, but do not unambiguously establish, a causal effect of lifestyle factors on important late-life outcomes. Nonetheless, the existing studies are few in number and have clear limitations that have not always been considered in interpreting their results. It is concluded that twin researchers could make greater use of the discordant-twin design as one approach to strengthen causal inferences in observational research.