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Keywords = Groucho

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40 pages, 4900 KiB  
Article
Stability of a Groucho-Style Bounding Run in the Sagittal Plane
by Jeffrey Duperret and Daniel E. Koditschek
Robotics 2023, 12(4), 109; https://doi.org/10.3390/robotics12040109 - 27 Jul 2023
Cited by 1 | Viewed by 2484
Abstract
This paper develops a three-degree-of-freedom sagittal-plane hybrid dynamical systems model of a Groucho-style bounding quadrupedal run. Simple within-stance controls using a modular architecture yield a closed-form expression for a family of hybrid limit cycles that represent bounding behavior over a range of user-selected [...] Read more.
This paper develops a three-degree-of-freedom sagittal-plane hybrid dynamical systems model of a Groucho-style bounding quadrupedal run. Simple within-stance controls using a modular architecture yield a closed-form expression for a family of hybrid limit cycles that represent bounding behavior over a range of user-selected fore-aft speeds as a function of the model’s kinematic and dynamical parameters. Controls acting on the hybrid transitions are structured so as to achieve a cascade composition of in-place bounding driving the fore-aft degree of freedom, thereby decoupling the linearized dynamics of an approximation to the stride map. Careful selection of the feedback channels used to implement these controls affords infinitesimal deadbeat stability, which is relatively robust against parameter mismatch. Experiments with a physical quadruped reasonably closely match the bounding behavior predicted by the hybrid limit cycle and its stable linearized approximation. Full article
(This article belongs to the Section Sensors and Control in Robotics)
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11 pages, 282 KiB  
Concept Paper
Sector-Scale Proliferation of CSR Quality Label Programs via Mimicry: The Rotkäppchen Effect
by Ralf Buckley
Sustainability 2023, 15(14), 10910; https://doi.org/10.3390/su151410910 - 12 Jul 2023
Cited by 2 | Viewed by 1420
Abstract
Proliferation of CSR quality certification programs can be analysed within theories of mimicry. Some firms use third-party quality certificates to signal their CSR practices to consumers accurately. These firms and consumers benefit from few, simple, recognized, reliable labels. Other firms use competing or [...] Read more.
Proliferation of CSR quality certification programs can be analysed within theories of mimicry. Some firms use third-party quality certificates to signal their CSR practices to consumers accurately. These firms and consumers benefit from few, simple, recognized, reliable labels. Other firms use competing or own-brand labels to signal deceptively, gaining competitive advantage without compliance costs. Unreliable labels act as mimics to dupe consumers. If consumers cannot determine which labels are misleading, they ignore them all. Within ecological theories of mimicry, this is known as aggressive reverse Brouwerian automimicry. CSR-label research has a different naming tradition, and this sector-scale effect could be called a rotkäppchen effect, analogous to program-scale groucho and firm-scale goldilocks effects. It is testable by analysing mimicry mechanisms or predicted patterns. Full article
(This article belongs to the Special Issue Retail Marketing Management and Consumer Behavior Research)
14 pages, 2550 KiB  
Article
Role of Groucho and Groucho1-like in Regulating Metamorphosis and Ovary Development in Nilaparvata lugens (Stål)
by Han Gao, Xiaojuan Jiang, Shiwen Zheng, Yan Li and Xinda Lin
Int. J. Mol. Sci. 2022, 23(3), 1197; https://doi.org/10.3390/ijms23031197 - 21 Jan 2022
Cited by 5 | Viewed by 2347
Abstract
Juvenile hormone and ecdysone are key regulators in the metamorphosis and development. Grocho (Gro) is a highly conserved protein required for metamorphosis and development. Brown planthopper (Nilaparvata lugens) is a major pest affecting rice production in China and many Asian countries. [...] Read more.
Juvenile hormone and ecdysone are key regulators in the metamorphosis and development. Grocho (Gro) is a highly conserved protein required for metamorphosis and development. Brown planthopper (Nilaparvata lugens) is a major pest affecting rice production in China and many Asian countries. Although the molecular function of Gro has been investigated in holometabolous insects such as Aedes aegypti and Drosophila melanogaster, their role in the hemimetabolous insect, brown planthopper, and the relationship between NlGro/NlGro1-L and JH/ecdysone signaling pathway, remained unknown. In this study, NlGroucho (NlGro) and NlGroucho1-like (NlGro1-L) were cloned. An analysis of the predicted protein sequence showed that NlGro has highly conserved Q domain and WD40 domain, and NlGro1-L has a highly conserved WD40 domain. The expression profiles of both genes were studied by quantitative real-time PCR (qRT-PCR). Their relative expressions were high in egg, head, wing, ovary, and testis. NlGro and NlGro1-L were found to interact genetically with juvenile hormone and ecdysone signaling by hormone treatment and RNAi of JH/ecdysone signaling-related genes. Moreover, when NlGro or NlGro1-L was down-regulated alone, the survival rate was decreased, the ovarian development was delayed, and the oviposition was also affected. All defects were aggravated when NlGro and NlGro1-L were down-regulated together. This study will help to develop new pesticides on the basis of the function of NlGro and NlGro1-L, and provide new possibilities for the control of Nilaparvata lugens. Full article
(This article belongs to the Section Biochemistry)
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17 pages, 3145 KiB  
Article
Limited Availability of General Co-Repressors Uncovered in an Overexpression Context during Wing Venation in Drosophila melanogaster
by Anja C. Nagel, Dieter Maier, Janika Scharpf, Manuela Ketelhut and Anette Preiss
Genes 2020, 11(10), 1141; https://doi.org/10.3390/genes11101141 - 28 Sep 2020
Cited by 2 | Viewed by 3480
Abstract
Cell fate is determined by the coordinated activity of different pathways, including the conserved Notch pathway. Activation of Notch results in the transcription of Notch targets that are otherwise silenced by repressor complexes. In Drosophila, the repressor complex comprises the transcription factor [...] Read more.
Cell fate is determined by the coordinated activity of different pathways, including the conserved Notch pathway. Activation of Notch results in the transcription of Notch targets that are otherwise silenced by repressor complexes. In Drosophila, the repressor complex comprises the transcription factor Suppressor of Hairless (Su(H)) bound to the Notch antagonist Hairless (H) and the general co-repressors Groucho (Gro) and C-terminal binding protein (CtBP). The latter two are shared by different repressors from numerous pathways, raising the possibility that they are rate-limiting. We noted that the overexpression during wing development of H mutants HdNT and HLD compromised in Su(H)-binding induced ectopic veins. On the basis of the role of H as Notch antagonist, overexpression of Su(H)-binding defective H isoforms should be without consequence, implying different mechanisms but repression of Notch signaling activity. Perhaps excess H protein curbs general co-repressor availability. Supporting this model, nearly normal wings developed upon overexpression of H mutant isoforms that bound neither Su(H) nor co-repressor Gro and CtBP. Excessive H protein appeared to sequester general co-repressors, resulting in specific vein defects, indicating their limited availability during wing vein development. In conclusion, interpretation of overexpression phenotypes requires careful consideration of possible dominant negative effects from interception of limiting factors. Full article
(This article belongs to the Special Issue Regulating Gene Activity By Sequestering Transcriptional Regulators)
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