Exceptionally preserved fossils are the product of complex interplays of biological and geological processes including burial, autolysis and microbial decay, authigenic mineralization, diagenesis, metamorphism, and finally weathering and exhumation. Determining which tissues are preserved and how biases affect their preservation pathways is important for interpreting fossils in phylogenetic, ecological, and evolutionary frameworks. Although laboratory decay experiments reveal important aspects of fossilization, applying the results directly to the interpretation of exceptionally preserved fossils may overlook the impact of other key processes that (...) remove or preserve morphological information. Investigations of fossils preserving non-biomineralized tissues suggest that certain structures that are decay resistant are rarely preserved, and decay-prone structures can fossilize, albeit rarely. As we review here, decay resistance is an imperfect indicator of fossilization potential, and a suite of biological and geological processes account for the features preserved in exceptional fossils. Organisms decayed experimentally in seawater have been used as direct analogs for soft-bodied fossil taxa, with fossils representing a snapshot of a particular stage of decay. We argue that numerous geological and biological processes account for fossilization and that all of these should be considered when reconstructing extinct organisms. (shrink)

Exceptionally preserved fossils are the product of complex interplays of biological and geological processes including burial, autolysis and microbial decay, authigenic mineralization, diagenesis, metamorphism, and finally weathering and exhumation. Determining which tissues are preserved and how biases affect their preservation pathways is important for interpreting fossils in phylogenetic, ecological, and evolutionary frameworks. Although laboratory decay experiments reveal important aspects of fossilization, applying the results directly to the interpretation of exceptionally preserved fossils may overlook the impact of other key processes that (...) remove or preserve morphological information. Investigations of fossils preserving non-biomineralized tissues suggest that certain structures that are decay resistant are rarely preserved, and decay-prone structures can fossilize, albeit rarely. As we review here, decay resistance is an imperfect indicator of fossilization potential, and a suite of biological and geological processes account for the features preserved in exceptional fossils. Organisms decayed experimentally in seawater have been used as direct analogs for soft-bodied fossil taxa, with fossils representing a snapshot of a particular stage of decay. We argue that numerous geological and biological processes account for fossilization and that all of these should be considered when reconstructing extinct organisms. (shrink)

Phototoxicity frequently occurs during live fluorescence microscopy, and its consequences are often underestimated. Damage to cellular macromolecules upon excitation light illumination can impair sample physiology, and even lead to sample death. In this review, we explain how phototoxicity influences live samples, and we highlight that, besides the obvious effects of phototoxicity, there are often subtler consequences of illumination that are imperceptible when only the morphology of samples is examined. Such less apparent manifestations of phototoxicity are equally problematic, and can change (...) the conclusions drawn from an experiment. Thus, limiting phototoxicity is a prerequisite for obtaining reproducible quantitative data on biological processes. We present strategies to reduce phototoxicity, e.g. limiting the illumination to the focal plane and suggest controls for phototoxicity effects. Overall, we argue that phototoxicity needs increased attention from researchers when designing experiments, and when evaluating research findings. (shrink)

Brian Clark's drama, Whose Life Is It Anyway?, explores the difficulties of applying the principle of respect for autonomy to real-life circumstances. In the play a permanently disabled patient, who wishes to be allowed to die, raises moral questions about the adequacy of the autonomous agent, respect for the autonomy of others, the authority of the law, the allocation of society's resources, and the intrinsic value of human life. After a brief review of the story and definition of respect for (...) autonomy, this paper cites passages from the play that dramatize the tension between respect for autonomy and these other moral concerns. There follows a review of relevant commentary from the classicists Kant and Mill and the modernists Childress and Gillon. The study concludes that although classical and contemporary philosophers have clarified and elaborated upon the relationship between ethical principles, they have not provided definitive guidelines. (shrink)

During the past decade and a half, the field of family literacy has gone from its infancy on the educational periphery toward a position closer to the mainstream. Characteristic ofthe field’s growth is the nation’s largest endeavor in family literacy, the federal Even Start program, which began from scratch in the late 1980s and now claims more than 800 local programs in 50 states and Puerto Rico.Despite several national evaluations of Even Start, no comprehensive study in the family literacy literature (...) specifically focuses on this quarter-billion dollar program’s attempts to measure the progress of its adult students. Accordingly, this study sought to discover the ways in which adult assessment is performed by Even Start programs.This essay emphasizes critical thinking with regards to assessment in Even Start programs Critical thought and reflection drive the exploration of several themes in the study’s data that carry itnplications for the families served by Even Start. These implications, gleaned from what Brookfield (1987) calls “reflective skepticism” and careful study of the data, bring the survey’s numbers to life and ultimately yield useful, potentially program-enhancing information.The article offers background on family literacy and Even Start programs and briefly illustrates the study’s methodology. Then follows a discourse that views the study’s findings through the lens of critical thought, drawing meaning from selected findings that contain repercussions for Even Start families. The piece concludes with recommendations for the improvement of Even Start programs through enhanced assessment and continued study. (shrink)