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1. Instabilities and patterns in a submerged jelling jet

   https://doi.org/10.1039/D1SM00517K  

   Chakrabarti, Aditi; Al-Mosleh, Salem; Mahadevan, L. (November 2021, Soft Matter)

   When a thin stream of aqueous sodium alginate is extruded into a reacting calcium chloride bath, it polymerizes into a soft elastic tube that spontaneously forms helical coils due to the ambient fluid drag. 

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2. Among‐ and within‐population variation in morphology, rewards, and scent in a hawkmoth‐pollinated plant

   https://doi.org/10.1002/ajb2.16030  

   Eisen, Katherine E.; Ma, Rong; Raguso, Robert A. (November 2022, American Journal of Botany)

   Abstract PremiseFloral scent is a complex trait that mediates many plant–insect interactions, but our understanding of how floral scent variation evolves, either independently or in concert with other traits, remains limited. Assessing variation in floral scent at multiple levels of biological organization and comparing patterns of variation in scent to variation in other floral traits can contribute to our understanding of how scent variation evolves in nature. MethodsWe used a greenhouse common garden experiment to investigate variation in floral scent at three scales—within plants, among plants, and among populations—and to determine whether scent, alone or in combination with morphology and rewards, contributes to population differentiation inOenothera cespitosasubsp.marginata. Its range spans most of the biomes in the western United States, such that variation in both the abiotic and biotic environment could contribute to trait variation. ResultsMultiple analytical approaches demonstrated substantial variation among and within populations in compound‐specific and total floral scent measures. Overall, populations were differentiated in morphology and reward traits and in scent. Across populations, coupled patterns of variation in linalool, leucine‐derived compounds, and hypanthium length are consistent with a long‐tongued moth pollination syndrome. ConclusionsThe considerable variation in floral scent detected within populations suggests that, similar to other floral traits, variation in floral scent may have a heritable genetic component. Differences in patterns of population differentiation in floral scent and in morphology and rewards indicate that these traits may be shaped by different selective pressures. 

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3. A note on surfaces in ℂℙ² and ℂℙ²#ℂℙ²

   https://doi.org/10.1090/bproc/218  

   Marengon, Marco; Miller, Allison; Ray, Arunima; Stipsicz, András (June 2024, Proceedings of the American Mathematical Society, Series B)

   In this brief note, we investigate the ${\mathbb{C}\mathbb{P}}^2$-genus of knots, i.e., the least genus of a smooth, compact, orientable surface in ${\mathbb{C}\mathbb{P}}^2\setminus <\#comment/>\stackrel{˚<\#comment/>}{B^4}$bounded by a knot in $S^3$. We show that this quantity is unbounded, unlike its topological counterpart. We also investigate the ${\mathbb{C}\mathbb{P}}^2$-genus of torus knots. We apply these results to improve the minimal genus bound for some homology classes in ${\mathbb{C}\mathbb{P}}^2\mathrm{\#<\#comment/>}{\mathbb{C}\mathbb{P}}^2$. 

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4. Positioning in a collaboration network and performance in competitions: a case study of Kaggle

   https://doi.org/10.1093/jcmc/zmad024  

   Twyman, Marlon; Murić, Goran; Zheng, Weiwei; Baym, ed., Nancy; Ellison, ed., Nicole (June 2023, Journal of Computer-Mediated Communication)

   Abstract Online innovation competitions are ecosystems where institutions source numerous solutions from knowledge workers through a platform intermediary. By considering how an individual competitor’s performance varies based on their social positioning in a competition ecosystem’s collaboration network, we illustrate the value of social networks for individual outcomes in online competitions. The study reports results from Kaggle, a popular online competition platform for data science, where a sample of 350,956 users participated in 2,789 competitions over 4 years. We investigate how the number of collaborations, membership in the largest connected component in the network, and diversity of collaboration experiences impact the points and medals earned and how quickly competitors earn their first medal. Results show that positioning has a positive relationship with performance in competitive ecosystems. Relevant to the future of work, the study considers how knowledge workers in future workplaces should manage their online collaborations. 

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5. Flow and Drag in a Seagrass Bed

   https://doi.org/10.1029/2018JC014862  

   Monismith, Stephen G.; Hirsh, Heidi; Batista, Natasha; Francis, Holly; Egan, Galen; Dunbar, Robert B. (March 2019, Journal of Geophysical Research: Oceans)

   Abstract We report direct measurement of drag forces due to tidal flow over a submerged seagrass bed in Ngeseksau Reef, Koror State, Republic of Palau. In our study, drag is computed using an array of high‐resolution pressure measurements, from which values of the drag coefficients,C_D, referenced to measured depth‐averaged velocities,V, were inferred. Reflecting the fact that seagrass blades deflect in the presence of flow, we find thatC_Dis O(1) when flows are weak and tends toward a value of 0.03 at the highest velocities, behavior that is consistent with existing theory for canopy flows with flexible canopy elements. A limited subset of velocity profiles obey the law of the wall, producing values of shear velocity that, while noisy, broadly agree with values inferred from the pressure measurements. 

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