St. Olaf College

Die Sarkopeniespielt in der intensivmedizinisch erworbenen Schwäche (ICUAW) durch Immobilisation und ischämisch-hypoxisch getriggerter Abnahme der Kapillarisierung eine entscheidende Rolle im rehabilitativen Behandlungsverlauf. Klinisch zeigen sich eine Abnahme der Muskelmasse und Muskelkraft, welche durch Verlust der Typ II Muskelfasern, Reduzierung der Satellitenzellen und Kollageneinbau in die Muskulatur bedingt sind. Die Quantifizierung der Sarkopenie stellt die Diagnostik von ICUAW vermittelten Krankheitsbildern, wie critical illness polymyopathie (CIM) und critical illness polyneuropathie (CIP), vor eine Herausforderung. Wir untersuchten einen 66-jährigen Patienten mit ICUAW-bedingter Immobilisationssarkopenie mit der Bestimmung der Rheobase, Chronaxie und Akkommodationsschwelle unter EMG-Kontrolle nach 101 Tagen Intensivbehandlung. In Ruhe lagen die EMG-Werte der Frequenz im Mittel bei 53 Hz, der RMS bei 4,6 μV, die MVC bei 51 μV und das iEMG bei 243 μV*s, was auf eine geringere muskuläre Eigenaktivität hinwies. Die Rheobase lag um 7 μV, die Chronaxie um 12,5 ms und die Akkomodationsschwelle um 7 mA oberhalb der Normwertbereiche. Der Akkomodationsquotient lag um 0,4 unterhalb des Normwertbereiches. Die stimulationsbedingten Muskelpotentiale lagen im Durchschnitt bei einer RMS von 602,5 μV, einer MVC von 2761,2 μV und einem iEMG bei 528,7 μV*S. In der Kombination der ermittelten Werte muss bei einer Immobilisationssarkopenie von einer neuromuskulären Funktionsstörung ausgegangen werden, da neben sicheren Hinweisen einer Muskelatrophie auch Anzeichen neurodegenerativer Funktionsveränderungen ermittelt wurden.

Parallel and Distributed Computing (PDC) has increased in importance in recent years, with ABET requiring exposure to PDC topics, and CS2023 recommending at least 9 hours of coverage in required CS courses. However, injecting PDC topics quickly into a course is difficult due to time and expense to set up requisite hardware and lack of readily available materials to adopt for the classroom. In this demo, we -- the CSinParallel project -- present free, web-based, interactive textbooks for learning and practicing various forms of PDC. We developed the backend system and wrote the material based on decades of experience integrating these topics into courses throughout the computer science curriculum. Currently we have two books that educators can readily use: Parallel Computing for Beginners, and Intermediate Parallel and Distributed Computing, along with some additional materials. With just a laptop in class, students can edit and run PDC code examples on remote hardware that is professionally maintained, eliminating the need for instructors to prepare hardware and software. The material spans a range of PDC technology (OpenMP, MPI, CUDA, OpenACC), provides mini assessments as readers work, and is designed so that instructors can add brief modules into existing courses or can be used comprehensively for a course dedicated to PDC. All materials are available on learnpdc.org and the code used in the books is on https://github.com/csinparallel/csinparallel. Additional assignments for a PDC course can be found on https://github.com/csinparallel/pdc-assignments.

Arguments against naturalism and materialism have a long history, from Plato to Plantinga. The paper has three parts: First, I reconstruct an argument from reason found in Plato’s the Phaedo. Second I consider whether the argu‑ ment is relevant to contemporary forms of naturalism. I argue that the argument does constitute a serious objection to some forms of naturalism. I then defend the argument against objections from GEM Anscombe, Graham Oppy, and Peter van Inwagen.

The evolution of novel animal signals is critical to the generation of biodiversity. Here, we explore how new sexual signals become established. This process is challenging to explain because if receiver preferences are coupled with existing signals, then most receivers should discriminate against new signals. We investigated an underappreciated hypothesis: relaxed receiver preferences facilitate novel signal evolution by allowing new signals to establish a foothold. Further, we probed the mechanistic underpinnings of relaxed preferences by combining field-based and common garden approaches, allowing us to investigate evolution and plasticity as mechanisms. We capitalized on the Pacific field cricket, Teleogryllus oceanicus, a species that has recently evolved multiple novel acoustic signals (e.g., purring and rattling) in response to an eavesdropping parasitoid fly only found in the crickets' introduced range in Hawaii. To test the hypothesis that selection associated with high search costs in introduced populations leads to relaxed mating preferences and determine whether such relaxation is plastic, we conducted sound preference (phonotaxis) trials with females from the cricket's native range (Australia and French Polynesia, where the fly is absent) and its introduced range (Hawaii, where the fly is present). We presented females with novel songs plus the typical, ancestral song. Differences in phonotactic behavior between the lab and field settings would indicate plasticity in preferences. We found that Australian and French Polynesian females were quite plastic; they discriminated strongly against most songs in the field, but were much more phonotactic to rattling and the typical song in the lab. However, Hawaiian females exhibited little plasticity and were consistently highly responsive to the rattling and typical songs in the lab and field. This pattern points to a loss of ancestral plasticity in female preferences sometime after colonizing Hawaii, resulting in heightened responsiveness to all songs-allowing novel signals to establish.

Lipid droplets are increasingly recognized as necessary organelles. However, the cellular pathways that regulate lipid droplets have only been defined in select fungi, algae, plants, and animals. Our experiments expand the study of lipid droplets to an evolutionarily distinct model organism, the ciliate Tetrahymena thermophila. We identify conserved pathways that promote lipid droplet homeostasis while also uncovering features that suggest adaptation. We show that Tetrahymena accumulate lipid droplets in response to nutrient deprivation, including starvation and the stationary phase. Pulse-chase experiments with a fluorescent fatty acid analogue demonstrate lipid trafficking to lipid droplets in starved cultures. Unlike other cell types, starved Tetrahymena appear to use both peroxisomes and mitochondria (not vacuoles) for further fatty acid catabolism. We observe cooccurence of the fluorescent fatty acid analogue with markers of peroxisomes and a subpopulation of mitochondria, suggesting specialized catabolic roles for both organelles. We demonstrate a decrease in survival following starvation in the presence of inhibitors of mitochondrial fatty acid import or peroxisomal fatty acid metabolism. Together, our experiments add Tetrahymena to the expanding list of eukaryotes that increase lipid droplets in response to nutrient depletion while also uncovering important and distinct roles for mitochondrial and peroxisomal catabolism in survival pathways.

Many complex wetting behaviors of fibrous materials are rooted in the behaviors of individual droplets attached to pairs of fibers. Here, we study the splitting of a droplet held between the tips of two cylindrical fibers. We discover a sharp transition between two post-rupture states, navigated by changing the angle between the rods, in agreement with our bifurcation analysis. Depinning of the bridge contact line can lead to a much larger asymmetry between the volume of liquid left on each rod. This second scenario enables the near-complete transfer of an aqueous glycerol droplet between two identical vinylpolysiloxane fibers. We leverage this response in a device that uses a ruck to pass a droplet along a train of fibers, a proof-of-concept for the geometric control of droplets on deformable, architected surfaces.