Se não existe design intencional, por que buscar inspiração na natureza?

Vision-controlled jetting for composite systems and robots

Thomas J. K. Buchner, Simon Rogler, Stefan Weirich, Yannick Armati, Barnabas Gavin Cangan, Javier Ramos, Scott T. Twiddy, Davide M. Marini, Aaron Weber, Desai Chen, Greg Ellson, Joshua Jacob, Walter Zengerle, Dmitriy Katalichenko, Chetan Keny, Wojciech Matusik & Robert K. Katzschmann

Nature volume 623, pages 522–530 (2023)

An image montage of the soft robotic hand holding a marker pen and a water bottle.(Image credit: ETH Zurich/Thomas Buchner)

Abstract

Recreating complex structures and functions of natural organisms in a synthetic form is a long-standing goal for humanity1. The aim is to create actuated systems with high spatial resolutions and complex material arrangements that range from elastic to rigid. Traditional manufacturing processes struggle to fabricate such complex systems2. It remains an open challenge to fabricate functional systems automatically and quickly with a wide range of elastic properties, resolutions, and integrated actuation and sensing channels2,3. We propose an inkjet deposition process called vision-controlled jetting that can create complex systems and robots. Hereby, a scanning system captures the three-dimensional print geometry and enables a digital feedback loop, which eliminates the need for mechanical planarizers. This contactless process allows us to use continuously curing chemistries and, therefore, print a broader range of material families and elastic moduli. The advances in material properties are characterized by standardized tests comparing our printed materials to the state-of-the-art. We directly fabricated a wide range of complex high-resolution composite systems and robots: tendon-driven hands, pneumatically actuated walking manipulators, pumps that mimic a heart and metamaterial structures. Our approach provides an automated, scalable, high-throughput process to manufacture high-resolution, functional multimaterial systems.

FREE PDF GRATIS: Nature 

Não saia de casa sem informação: ela é importante para sua sobrevivência.

Semantic Information in a Model of Resource Gathering Agents

Damian R. Sowinski, Jonathan Carroll-Nellenback, Robert N. Markwick, Jordi Piñero, Marcelo Gleiser, Artemy Kolchinsky, Gourab Ghoshal, and Adam Frank

PRX Life 1, 023003 – Published 17 October 2023

 

Abstract

We explore the application of a theory of semantic information to the well-motivated problem of resource foraging. Semantic information is defined as the subset of correlations, which is here measured via the transfer entropy, between agent A and environment E that is necessary for the agent to maintain its viability V. Viability, in turn, is endogenously defined as opposed to the use of exogenous quantities like utility functions. In our model, the forager's movements are determined by its ability to measure, via a sensor, the presence of an individual unit of resource, while the viability function is its expected lifetime. Through “interventions”—scrambling the correlations between agent and environment by noising the sensor—we demonstrate the presence of a critical value of the noise parameter, ηc, above which the forager's expected lifetime is dramatically reduced. On the other hand, for η<ηc there is little to no effect on its ability to survive. We refer to this boundary as the semantic threshold, quantifying the subset of agent-environment correlations that the agent actually needs to maintain its desired state of staying alive. Each bit of information affects the agent's ability to persist both above and below the semantic threshold. Modeling the viability curve and its semantic threshold via forager and/or environment parameters, we show how the correlations are instantiated. Our work demonstrates the successful application of semantic information to a well-known agent-based model of biological and ecological interest. Additionally, we demonstrate that the concept of semantic thresholds may prove useful for understanding the role information plays in allowing systems to become autonomous agents.

FREE PDF GRATIS: PRX Life 1

Controle de redes reguladoras de genes padronizando tecidos orientado por morfogênese: mero acaso, fortuita necessidade ou princípios de design inteligente?

Optimal control of gene regulatory networks for morphogen-driven tissue patterning

Alberto Pezzotta, 1, 2, James Briscoe, 1

1. Developmental Dynamics Laboratory, The Francis Crick Institute, 1 Midland Road, NW1 1AT London, UK

2. Gatsby Computational Neuroscience Unit, University College London, 25 Howland Street, W1T 4JG London, UK

Received 17 August 2022, Revised 6 June 2023, Accepted 10 October 2023, Available online 15 November 2023, Version of Record 15 November 2023.

Published: November 15, 2023

https://doi.org/10.1016/j.cels.2023.10.004 

Highlights

• Morphogen signaling controls the pattern of gene expression in developing tissues

• Optimal control theory identifies signaling mechanisms for morphogen patterning    

• By incorporating feedback between signaling and gene regulation, it explains dynamics

• Provides an alternative framework to the “French Flag model” for morphogen patterning

Summary

The generation of distinct cell types in developing tissues depends on establishing spatial patterns of gene expression. Often, this is directed by spatially graded chemical signals—known as morphogens. In the “French Flag model,” morphogen concentration instructs cells to acquire specific fates. How this mechanism produces timely and organized cell-fate decisions, despite the presence of changing morphogen levels, molecular noise, and individual variability, is unclear. Moreover, feedback is present at various levels in developing tissues, breaking the link between morphogen concentration, signaling activity, and position. Here, we develop an alternative framework using optimal control theory to tackle the problem of morphogen-driven patterning: intracellular signaling is derived as the control strategy that guides cells to the correct fate while minimizing a combination of signaling levels and time. This approach recovers experimentally observed properties of patterning strategies and offers insight into design principles that produce timely, precise, and reproducible morphogen patterning.

FREE PDF GRATIS: Cell Systems

Darwin, nós temos um grande problema: onde estão as pontes conceituais e empíricas entre a micro e a macroevolução?

Conceptual and empirical bridges between micro- and macroevolution

Jonathan Rolland, L. Francisco Henao-Diaz, Michael Doebeli, Rachel Germain, Luke J. Harmon, L. Lacey Knowles, Lee Hsiang Liow, Judith E. Mank, Antonin Machac, Sarah P. Otto, Matt Pennell, Nicolas Salamin, Daniele Silvestro, Mauro Sugawara, Josef Uyeda, Catherine E. Wagner & Dolph Schluter

Nature Ecology & Evolution volume 7, pages 1181–1193 (2023 

Image/Imagem

Abstract

Explaining broad molecular, phenotypic and species biodiversity patterns necessitates a unifying framework spanning multiple evolutionary scales. Here we argue that although substantial effort has been made to reconcile microevolution and macroevolution, much work remains to identify the links between biological processes at play. We highlight four major questions of evolutionary biology whose solutions require conceptual bridges between micro and macroevolution. We review potential avenues for future research to establish how mechanisms at one scale (drift, mutation, migration, selection) translate to processes at the other scale (speciation, extinction, biogeographic dispersal) and vice versa. We propose ways in which current comparative methods to infer molecular evolution, phenotypic evolution and species diversification could be improved to specifically address these questions. We conclude that researchers are in a better position than ever before to build a synthesis to understand how microevolutionary dynamics unfold over millions of years.

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Nature Ecology & Evolution

Como os girassóis podem ver o sol: mero acaso, fortuita necessidade ou design inteligente?

Multiple light signaling pathways control solar tracking in sunflowers

Christopher J. Brooks,Hagop S. Atamian,Stacey L. Harmer 

Published: October 31, 2023

https://doi.org/10.1371/journal.pbio.3002344

Pixabay

Abstract

Sunflowers are famous for their ability to track the sun throughout the day and then reorient at night to face east the following morning. This occurs by differential growth patterns, with the east sides of stems growing more during the day and the west sides of stems growing more at night. This process, termed heliotropism, is generally believed to be a specialized form of phototropism; however, the underlying mechanism is unknown. To better understand heliotropism, we compared gene expression patterns in plants undergoing phototropism in a controlled environment and in plants initiating and maintaining heliotropic growth in the field. We found the expected transcriptome signatures of phototropin-mediated phototropism in sunflower stems bending towards monochromatic blue light. Surprisingly, the expression patterns of these phototropism-regulated genes are quite different in heliotropic plants. Most genes rapidly induced during phototropism display only minor differences in expression across solar tracking stems. However, some genes that are both rapidly induced during phototropism and are implicated in growth responses to foliar shade are rapidly induced on the west sides of stems at the onset of heliotropism, suggesting a possible role for red light photoreceptors in solar tracking. To test the involvement of different photoreceptor signaling pathways in heliotropism, we modulated the light environment of plants initiating solar tracking. We found that depletion of either red and far-red light or blue light did not hinder the initiation or maintenance of heliotropism in the field. Together, our results suggest that the transcriptional regulation of heliotropism is distinct from phototropin-mediated phototropism and likely involves inputs from multiple light signaling pathways.

FREE PDF GRATIS: PLoS Biology

Visão no cérebro – programada para a ação: mero acaso, necessidade fortuita ou design inteligente?

Retina-derived signals control pace of neurogenesis in visual brain areas but not circuit assembly

Shachar Sherman, Irene Arnold-Ammer, Martin W. Schneider, Koichi Kawakami & Herwig Baier

Nature Communications volume 14, Article number: 6020 (2023) 

Neurons in the zebrafish brain - Biological Intelligence/Herwig Baier

Abstract

Brain development is orchestrated by both innate and experience-dependent mechanisms, but their relative contributions are difficult to disentangle. Here we asked if and how central visual areas are altered in a vertebrate brain depleted of any and all signals from retinal ganglion cells throughout development. We transcriptionally profiled neurons in pretectum, thalamus and other retinorecipient areas of larval zebrafish and searched for changes in lakritz mutants that lack all retinal connections. Although individual genes are dysregulated, the complete set of 77 neuronal types develops in apparently normal proportions, at normal locations, and along normal differentiation trajectories. Strikingly, the cell-cycle exits of proliferating progenitors in these areas are delayed, and a greater fraction of early postmitotic precursors remain uncommitted or are diverted to a pre-glial fate. Optogenetic stimulation targeting groups of neurons normally involved in processing visual information evokes behaviors indistinguishable from wildtype. In conclusion, we show that signals emitted by retinal axons influence the pace of neurogenesis in visual brain areas, but do not detectably affect the specification or wiring of downstream neurons.

FREE PDF GRATIS: Nature Communications

Darwin, nós temos um problema: mais controvérsias recentes na teoria da evolução

 

A V HILL Lecture – Recent controversies in evolutionary theory

Dr John Welch

6 November 2023, 18:00 – 19:00  A V Hill Lecture  Bristol-Myers Squibb Lecture Theatre

Overview

Every few years, critics of evolutionary theory have argued that the field needs a radical overhaul, and this trend shows no sign of stopping. This talk will discuss some recent challenges to core parts of evolutionary theory, focussing on the most serious and substantial challenges, which have come from evolutionary biologists themselves. I will trace many of these debates back to the contested legacy of R. A. Fisher (former head of the Department of Genetics in Cambridge), arguing that the reception of his work has cast long shadows. Throughout, the issues at stake will be illustrated with recent empirical work, especially from the Mexican cave tetra (Astyanax mexicanus), and the bacterial pathogen Mycobacterium tuberculosis. 

Biography

Dr Welch retrained as a biologist after a music degree and a job as a programmer. Following postdoctoral work at University of Sussex, University of Edinburgh and Université de Montpellier, John joined the Department of Genetics as a lecturer in 2010.

Dr Welch’s doctoral work was in mathematical population genetics, and this is still a large part of his research, but he now combines this with empirical approaches, especially evolutionary inference from microbial genealogies, and cross-species comparative analyses.

A.V. Hill Lecture

Archibald Vivian Hill (1886-1977) FRS was an English physiologist, one of the founders of the diverse disciplines of biophysics and operations research. He shared the 1922 Nobel Prize in Physiology or Medicine for his elucidation of the production of heat and mechanical work in muscles. Hill is regarded, along with Hermann Helmholz, as one of the founders of biophysics.

The first AV Hill Lecture was delivered in 2013 by Sir Leszek Borysiewicz, Vice Chancellor of Cambridge University.