329 research outputs found
Analyses of Dental Pulp in Restored Teeth
Restored teeth were extracted from test animals at four time intervals (1 hour, 1 day, 1 week, and 3 months) following amalgam insertion. Extracted teeth were frozen in liquid nitrogen, cryo-fractured so as to expose the pulps and then freeze-dried. Pulps were analyzed for mercury content by energy dispersive spectrometry (EDS) and atomic absorption spectrophotometry (AAS). Mercury levels appeared below the detection limits of EDS but could be detected by AAS which showed the highest readings seven days after amalgam insertion
Forecasting the Senate vote on the Supreme Court vacancy
This paper forecasts current senators’ votes on Merrick Garland’s nomination to the U.S. Supreme Court, in the unlikely case that a vote actually takes place. The forecasts are necessarily conditional, awaiting measurement of the nominee’s characteristics. Nonetheless, a model that combines parameters estimated from existing data with values of some measurable characteristics of senators—particularly their party affiliations, party loyalty levels, and ideological positions—is sufficient to identify potential swing voters in the Senate. By accounting for a more nuanced and refined understanding of the confirmation process, our model reveals that if President Obama were to nominate almost any nominee (conservative or liberal) today, that nominee would be rejected if a vote was allowed to take place. So why nominate anyone at all? Obama’s hope for a successful confirmation must come from the stochastic component, that is, from outside the traditional decision-making calculus
Self-repairing symmetry in jellyfish through mechanically driven reorganization
What happens when an animal is injured and loses important structures? Some animals simply heal the wound, whereas others are able to regenerate lost parts. In this study, we report a previously unidentified strategy of self-repair, where moon jellyfish respond to injuries by reorganizing existing parts, and rebuilding essential body symmetry, without regenerating what is lost. Specifically, in response to arm amputation, the young jellyfish of Aurelia aurita rearrange their remaining arms, recenter their manubria, and rebuild their muscular networks, all completed within 12 hours to 4 days. We call this process symmetrization. We find that symmetrization is not driven by external cues, cell proliferation, cell death, and proceeded even when foreign arms were grafted on. Instead, we find that forces generated by the muscular network are essential. Inhibiting pulsation using muscle relaxants completely, and reversibly, blocked symmetrization. Furthermore, we observed that decreasing pulse frequency using muscle relaxants slowed symmetrization, whereas increasing pulse frequency by lowering the magnesium concentration in seawater accelerated symmetrization. A mathematical model that describes the compressive forces from the muscle contraction, within the context of the elastic response from the mesoglea and the ephyra geometry, can recapitulate the recovery of global symmetry. Thus, self-repair in Aurelia proceeds through the reorganization of existing parts, and is driven by forces generated by its own propulsion machinery. We find evidence for symmetrization across species of jellyfish (Chrysaora pacifica, Mastigias sp., and Cotylorhiza tuberculata)
Naval Narratives of Re-enactment: In Which We Serve and Sea of Fire
This essay examines two narrative examples of the Royal Navy and naval combat on screen, exploring their resemblances in the reenactment of naval history and their portrayal of the past through consistent representational strategies. In Which We Serve (Noel Coward and David Lean, 1942) and Sea of Fire (Ian Duncan, 2007) use deliberate and self-conscious recreations of the past to authenticate their interpretations of British naval history, and evince comparably conservative stances towards the Royal Navy and perceptions of its traditions. The similarity of their narratives, which describe the events leading up to the loss of two Navy destroyers, helps to reveal and reinforce the tonal, structural and stylistic parallels in their depictions. The correspondence in their portrayal of naval combat and the institution of the Royal Navy illustrates the consistencies of representation which characterise the naval war film as a distinctive, definable narrative form. Above all, their commitment to the recreation and reenactment of identifiable historical events underpins their importance in the representation and commemoration of the national, naval past. It is this aspect of both productions which is significant in the exploration of the role of visual representations to construct, affirm and broadcast pervasive and persuasive versions of popular history
Adaptive MGS Phase Retrieval
Adaptive MGS Phase Retrieval software uses the Modified Gerchberg-Saxton (MGS) algorithm, an image-based sensing method that can turn any focal plane science instrument into a wavefront sensor, avoiding the need to use external metrology equipment. Knowledge of the wavefront enables intelligent control of active optical systems
Belowground rhizomes in paleosols:The hidden half of an Early Devonian vascular plant
The colonization of terrestrial environments by rooted vascular plants had far-reaching impacts on the Earth system. However, the belowground structures of early vascular plants are rarely documented, and thus the plant-soil interactions in early terrestrial ecosystems are poorly understood. Here we report the earliest rooted paleosols (fossil soils) in Asia from Early Devonian deposits of Yunnan, China. Plant traces are extensive within the soil and occur as complex network-like structures, which are interpreted as representing long-lived, belowground rhizomes of the basal lycopsid Drepanophycus. The rhizomes produced large clones and helped the plant survive frequent sediment burial in well-drained soils within a seasonal wet-dry climate zone. Rhizome networks contributed to the accumulation and pedogenesis of floodplain sediments and increased the soil stabilizing effects of early plants. Predating the appearance of trees with deep roots in the Middle Devonian, plant rhizomes have long functioned in the belowground soil ecosystem. This study presents strong, direct evidence for plant-soil interactions at an early stage of vascular plant radiation. Soil stabilization by complex rhizome systems was apparently widespread, and contributed to landscape modification at an earlier time than had been appreciated.National Natural Science Foundation of China [41272018]; Yunnan Key Laboratory for Palaeobiology, Yunnan University [2015DG007-KF04]; Key Laboratory of Economic Stratigraphy and Palaeogeography, Chinese Academy of Sciences (Nanjing Institute of Geology and Palaeontology)SCI(E)[email protected]
A conserved strategy for inducing appendage regeneration
Can limb regeneration be induced? Few have pursued this question, and an evolutionarily conserved strategy has yet to emerge. This study reports a strategy for inducing regenerative response in appendages, which works across three species that span the animal phylogeny. In Cnidaria, the frequency of appendage regeneration in the moon jellyfish Aurelia was increased by feeding with the amino acid L-leucine and the growth hormone insulin. In insects, the same strategy induced tibia regeneration in adult Drosophila. Finally, in mammals, L-leucine and sucrose administration induced digit regeneration in adult mice, including dramatically from mid- phalangeal amputation. The conserved effect of L-leucine and insulin/sugar suggests a key role for energetic parameters in regeneration induction. The simplicity by which nutrient supplementation can induce appendage regeneration provides a testable hypothesis across animals
A conserved strategy for inducing appendage regeneration
Can limb regeneration be induced? Few have pursued this question, and an evolutionarily conserved strategy has yet to emerge. This study reports a strategy for inducing regenerative response in appendages, which works across three species that span the animal phylogeny. In Cnidaria, the frequency of appendage regeneration in the moon jellyfish Aurelia was increased by feeding with the amino acid L-leucine and the growth hormone insulin. In insects, the same strategy induced tibia regeneration in adult Drosophila. Finally, in mammals, L-leucine and sucrose administration induced digit regeneration in adult mice, including dramatically from mid- phalangeal amputation. The conserved effect of L-leucine and insulin/sugar suggests a key role for energetic parameters in regeneration induction. The simplicity by which nutrient supplementation can induce appendage regeneration provides a testable hypothesis across animals
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