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1. Vertical Structure of Ocean Mesoscale Eddies with Implications for Parameterizations of Tracer Transport

   https://doi.org/10.1029/2020MS002151  

   Stanley, Z.; Bachman, S_D; Grooms, I. (October 2020, Journal of Advances in Modeling Earth Systems)

   Abstract The Gent–McWilliams parameterization is commonly used in global ocean models to model the advective component of tracer transport effected by unresolved mesoscale eddies. The vertical structure of the transfer coefficient in this parameterization is studied using data from a 0.1° resolution global ocean‐ice simulation. The vertical structure is found to be well approximated by a baroclinic mode structure with no flow at the bottom, though horizontal anisotropy is crucial for obtaining a good fit. This vertical structure is motivated by reference to the vertical structure of mesoscale eddy velocity and density anomalies, which are also diagnosed from the data. 

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2. Similarity in spatial structure constrains ecosystem relationships: Building a macroscale understanding of lakes

   https://doi.org/10.1111/geb.12781  

   Lapierre, Jean‐Francois; Collins, Sarah_M; Seekell, David_A; Spence_Cheruvelil, Kendra; Tan, Pang‐Ning; Skaff, Nicholas_K; Taranu, Zofia_E; Fergus, C_Emi; Soranno, Patricia_A (September 2018, Global Ecology and Biogeography)

   Abstract AimWe aimed to measure the dominant spatial patterns in ecosystem properties (such as nutrients and measures of primary production) and the multi‐scaled geographical driver variables of these properties and to quantify how the spatial structure of pattern in all of these variables influences the strength of relationships among them. Location and time periodWe studied > 8,500 lakes in a 1.8 million km²area of Northeast U.S.A. Data comprised 10‐year medians (2002–2011) for measured ecosystem properties, long‐term climate averages and recent land use/land cover variables. Major taxa studiedWe focused on ecosystem properties at the base of aquatic food webs, including concentrations of nutrients and algal pigments that are proxies of primary productivity. MethodsWe quantified spatial structure in ecosystem properties and their geographical driver variables using distance‐based Moran eigenvector maps (dbMEMs). We then compared the similarity in spatial structure for all pairs of variables with the correlation between variables to illustrate how spatial structure constrains relationships among ecosystem properties. ResultsThe strength of spatial structure decreased in order for climate, land cover/use, lake ecosystem properties and lake and landscape morphometry. Having a comparable spatial structure is a necessary condition to observe a strong relationship between a pair of variables, but not a sufficient one; variables with very different spatial structure are never strongly correlated. Lake ecosystem properties tended to have an intermediary spatial structure compared with that of their main drivers, probably because climate and landscape variables with known ecological links induce spatial patterns. Main conclusionOur empirical results describe inherent spatial constraints that dictate the expected relationships between ecosystem properties and their geographical drivers at macroscales. Our results also suggest that understanding the spatial scales at which ecological processes operate is necessary to predict the effects of multi‐scaled environmental changes on ecosystem properties. 

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3. Spatiotemporal fluctuations of population structure in the Americas revealed by a meta‐analysis of the first decade of archaeogenomes

   https://doi.org/10.1002/ajpa.24673  

   Campelo dos Santos, Andre Luiz; Lavalle Sullasi, Henry Socrates; Gokcumen, Omer; Lindo, John; DeGiorgio, Michael (December 2022, American Journal of Biological Anthropology)

   Abstract ObjectivesSince 2010, genome‐wide data from hundreds of ancient Native Americans have contributed to the understanding of Americas' prehistory. However, these samples have never been studied as a single dataset, and distinct relationships among themselves and with present‐day populations may have never come to light. Here, we reassess genomic diversity and population structure of 223 ancient Native Americans published between 2010 and 2019. Materials and MethodsThe genomic data from ancient Americas was merged with a worldwide reference panel of 278 present‐day genomes from the Simons Genome Diversity Project and then analyzed through ADMIXTURE,D‐statistics, PCA, t‐SNE, and UMAP. ResultsWe find largely similar population structures in ancient and present‐day Americas. However, the population structure of contemporary Native Americans, traced here to at least 10,000 years before present, is noticeably less diverse than their ancient counterparts, a possible outcome of the European contact. Additionally, in the past there were greater levels of population structure in North than in South America, except for ancient Brazil, which harbors comparatively high degrees of structure. Moreover, we find a component of genetic ancestry in the ancient dataset that is closely related to that of present‐day Oceanic populations but does not correspond to the previously reported Australasian signal. Lastly, we report an expansion of the Ancient Beringian ancestry, previously reported for only one sample. DiscussionOverall, our findings support a complex scenario for the settlement of the Americas, accommodating the occurrence of founder effects and the emergence of ancestral mixing events at the regional level. 

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4. Reassignment of the Structure of Janthinolide A

   https://doi.org/10.1002/ejoc.202300910  

   Bates, Roderick_W; Elyashberg, Mikhail; Kutateladze, Andrei_G; Williams, Craig_M (October 2023, European Journal of Organic Chemistry)

   Abstract Using computational methods and chemical intuition, the proposed structure of janthinolide A is shown to be incorrect. It is further shown that the material described as janthinolide A is highly likely to be janthinolide C. 

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5. Convergent evolution of disordered lipidic structural colour in the fruits of Lantana strigocamara (syn. L. camara hybrid cultivar)

   https://doi.org/10.1111/nph.18262  

   Sinnott‐Armstrong, Miranda A.; Ogawa, Yu; van de Kerkhof, Gea Theodora; Vignolini, Silvia; Smith, Stacey D. (June 2022, New Phytologist)

   Summary The majority of plant colours are produced by anthocyanin and carotenoid pigments, but colouration obtained by nanostructured materials (i.e. structural colours) is increasingly reported in plants. Here, we identify a multilayer photonic structure in the fruits ofLantana strigocamaraand compare it with a similar structure inViburnum tinusfruits.We used a combination of transmission electron microscopy (EM), serial EM tomography, scanning force microscopy and optical simulations to characterise the photonic structure inL. strigocamara. We also examine the development of the structure during maturation.We found that the structural colour derives from a disordered, multilayered reflector consisting of lipid droplets ofc.105 nm that form a plate‐like structure in 3D. This structure begins to form early in development and reflects blue wavelengths of light with increasing intensity over time as the structure develops. The materials used are likely to be lipid polymers.Lantana strigocamarais the second origin of a lipid‐based photonic structure, convergently evolved with the structure inViburnum tinus. Chemical differences between the lipids inL. strigocamaraand those ofV. tinussuggest a distinct evolutionary trajectory with implications for the signalling function of structural colours in fruits. 

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