More Like this

1. From Clear to DKIST: advancing solar MCAO from 1.6 to 4 meters

   https://doi.org/10.1117/12.2313787  

   Rimmele, Thomas R.; Marino, José; Johnson, Luke C.; Gorceix, Nicolas; Goode, Philip R.; Berkefeld, Thomas; Schmidt, Dirk; Schmidt, Dirk; Schreiber, Laura; Close, Laird M. (January 2019, Proceedings of the SPIE)

   The MCAO pathfinder Clear on the 1.6-meter Goode Solar Telescope has been enabling us to advance solar MCAO from early conceptual demonstrations to science grade wide-field image correction. We report on recent improvements to the control loop and we comment on issues such as the co-aligning of wavefront sensors and deformable mirrors and the sensitivity of wavefront sensor gains. Further, we comment on the challenges to wavefront sensing and the control system architecture faced when scaling up to a 4-meter aperture. Finally, we present an early concept of the future MCAO upgrade for the Daniel K. Inouye Solar Telescope. 

   more » « less
2. From Dendrochronology to Allometry

   https://doi.org/10.3390/f11020146  

   Biondi, Franco (February 2020, Forests)

   The contribution of tree-ring analysis to other fields of scientific inquiry with overlapping interests, such as forestry and plant population biology, is often hampered by the different parameters and methods that are used for measuring growth. Here I present relatively simple graphical, numerical, and mathematical considerations aimed at bridging these fields, highlighting the value of crossdating. Lack of temporal control prevents accurate identification of factors that drive wood formation, thus crossdating becomes crucial for any type of tree growth study at inter-annual and longer time scales. In particular, exactly dated tree rings, and their measurements, are crucial contributors to the testing and betterment of allometric relationships. 

   more » « less
3. From curves to currents

   https://doi.org/10.1017/fms.2021.68  

   Martínez-Granado, Dídac; Thurston, Dylan P. (January 2021, Forum of Mathematics, Sigma)

   Abstract Many natural real-valued functions of closed curves are known to extend continuously to the larger space of geodesic currents. For instance, the extension of length with respect to a fixed hyperbolic metric was a motivating example for the development of geodesic currents. We give a simple criterion on a curve function that guarantees a continuous extension to geodesic currents. The main condition of our criterion is the smoothing property, which has played a role in the study of systoles of translation lengths for Anosov representations. It is easy to see that our criterion is satisfied for almost all known examples of continuous functions on geodesic currents, such as nonpositively curved lengths or stable lengths for surface groups, while also applying to new examples like extremal length. We use this extension to obtain a new curve counting result for extremal length. 

   more » « less
4. From fossils to mind

   https://doi.org/10.1038/s42003-023-04803-4  

   de_Sousa, Alexandra A; Beaudet, Amélie; Calvey, Tanya; Bardo, Ameline; Benoit, Julien; Charvet, Christine J; Dehay, Colette; Gómez-Robles, Aida; Gunz, Philipp; Heuer, Katja; et al (December 2023, Communications Biology)

   Abstract Fossil endocasts record features of brains from the past: size, shape, vasculature, and gyrification. These data, alongside experimental and comparative evidence, are needed to resolve questions about brain energetics, cognitive specializations, and developmental plasticity. Through the application of interdisciplinary techniques to the fossil record, paleoneurology has been leading major innovations. Neuroimaging is shedding light on fossil brain organization and behaviors. Inferences about the development and physiology of the brains of extinct species can be experimentally investigated through brain organoids and transgenic models based on ancient DNA. Phylogenetic comparative methods integrate data across species and associate genotypes to phenotypes, and brains to behaviors. Meanwhile, fossil and archeological discoveries continuously contribute new knowledge. Through cooperation, the scientific community can accelerate knowledge acquisition. Sharing digitized museum collections improves the availability of rare fossils and artifacts. Comparative neuroanatomical data are available through online databases, along with tools for their measurement and analysis. In the context of these advances, the paleoneurological record provides ample opportunity for future research. Biomedical and ecological sciences can benefit from paleoneurology’s approach to understanding the mind as well as its novel research pipelines that establish connections between neuroanatomy, genes and behavior. 

   more » « less
5. From Curves to Words

   Chang, Hsien-Chih; Fasy, Brittany Terese; McCoy, Bradley; Millman, David L.; Wenk, Carola (June 2023, Young Researcher's Forum at CG Week)

   Blank, in his Ph.D. thesis on determining whether a planar closed curve $$\gamma$$ is self-overlapping, constructed a combinatorial word geometrically over the faces of $$\gamma$$ by drawing cuts from each face to a point at infinity and tracing their intersection points with $$\gamma$$. Independently, Nie, in an unpublished manuscript, gave an algorithm to determine the minimum area swept out by any homotopy from a closed curve $$\gamma$$ to a point. Nie constructed a combinatorial word algebraically over the faces of $$\gamma$$ inspired by ideas from geometric group theory, followed by dynamic programming over the subwords. In this paper, we examine the definitions of the two words and prove the equivalence between Blank's word and Nie's word under the right assumptions. 

   more » « less