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https://www.readbyqxmd.com/read/28616697/borders-tensegrity-and-development-in-dialogue
#1
Giuseppina Marsico, Luca Tateo
In this article we propose a development of the Dialogical Self Theory by introducing the notions of borders, cogenetic logic and tensegrity that we have elaborated during the last 5 years, in order to introduce a stronger developmental and dynamic perspective within the theory. We start from the discussion of some recent advancements of the model proposed by Hermans et al. (Integrative Psychological and Behavioural Science, 51(4), 2017), who refer to the metaphor of democratic society of the Self to understand the challenges and possible directions of adaptation that the persons can face in those border-crossing processes characterizing contemporary western societies...
June 14, 2017: Integrative Psychological & Behavioral Science
https://www.readbyqxmd.com/read/28615709/programmable-deployment-of-tensegrity-structures-by-stimulus-responsive-polymers
#2
Ke Liu, Jiangtao Wu, Glaucio H Paulino, H Jerry Qi
Tensegrity structures with detached struts are naturally suitable for deployable applications, both in terrestrial and outer-space structures, as well as morphing devices. Composed of discontinuous struts and continuous cables, such systems are only structurally stable when self-stress is induced; otherwise, they lose the original geometrical configuration (while keeping the topology) and thus can be tightly packed. We exploit this feature by using stimulus responsive polymers to introduce a paradigm for creating actively deployable 3D structures with complex shapes...
June 14, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28607953/a-tensegrity-model-for-hydrogen-bond-networks-in-proteins
#3
Robert P Bywater
Hydrogen-bonding networks in proteins considered as structural tensile elements are in balance separately from any other stabilising interactions that may be in operation. The hydrogen bond arrangement in the network is reminiscent of tensegrity structures in architecture and sculpture. Tensegrity has been discussed before in cells and tissues and in proteins. In contrast to previous work only hydrogen bonds are studied here. The other interactions within proteins are either much stronger - covalent bonds connecting the atoms in the molecular skeleton or weaker forces like the so-called hydrophobic interactions...
May 2017: Heliyon
https://www.readbyqxmd.com/read/28477281/self-assembly-as-the-underlying-mechanism-for-exine-development-in-larix-decidua-d-c
#4
Nina I Gabarayeva, Valentina V Grigorjeva
Our findings suggest a new approach to pollen ontogenetic investigations, entailing consideration of physical factors, which enable a better understanding of exine developmental processes. The sporopollenin-containing part of the pollen wall-the exine-is one of the most complex cell walls in plants. By tracing each stage of microspore development in Larix decidua with TEM, we aimed to understand the underlying mechanisms of its exine establishment. Our hypothesis is that self-assembly interferes with exine development...
May 5, 2017: Planta
https://www.readbyqxmd.com/read/28466984/an-organic-semiconductor-organized-into-3d-dna-arrays-by-bottom-up-rational-design
#5
Xiao Wang, Ruojie Sha, Martin Kristiansen, Carina Hernandez, Yudong Hao, Chengde Mao, James W Canary, Nadrian C Seeman
A 3D array of organic semiconductors was assembled using a DNA scaffold. An octameric aniline molecule ("octaniline") was incorporated into a DNA building block based on a dimeric tensegrity triangle. The construct self-assembled to form a 3D crystal. Reversible redox conversion between the pernigraniline and leucoemeraldine states of the octaniline is retained in the crystal. Protonic doping gave emeraldine salt at pH 5, corresponding to the conductive form of polyaniline. Redox cycling within the crystal was visualized by color changes and Raman microscopy...
June 1, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28224241/stem-cell-mechanical-behaviour-modelling-substrate-s-curvature-influence-during-adhesion
#6
M Vassaux, J L Milan
Recent experiments hint that adherent cells are sensitive to their substrate curvature. It is already well known that cells behaviour can be regulated by the mechanical properties of their environment. However, no mechanisms have been established regarding the influence of cell-scale curvature of the substrate. Using a numerical cell model, based on tensegrity structures theory and the non-smooth contact dynamics method, we propose to investigate the mechanical state of adherent cells on concave and convex hemispheres...
February 21, 2017: Biomechanics and Modeling in Mechanobiology
https://www.readbyqxmd.com/read/27934217/fluorescence-and-energy-transfer-in-dye-labeled-dna-crystals
#7
Joseph S Melinger, Ruojie Sha, Chengde Mao, Nadrian C Seeman, Mario G Ancona
DNA crystals make it possible to organize guest molecules into specific periodic 3D patterns at the nanoscale, and thereby to create novel macroscopic objects with potentially useful functionality. Here, we describe the fluorescence and energy transfer properties of DNA crystals that are self-assembled from DNA tensegrity triangles with covalently attached Cy3 and Cy5 dyes. When compared to reference DNA strands in solution, the fluorescence measurements indicate that the dyes in the crystal experience a more homogeneous environment, resulting in a 2-fold increase in Cy3 quantum yield and single-exponential Cy3 fluorescence decays...
December 8, 2016: Journal of Physical Chemistry. B
https://www.readbyqxmd.com/read/27812997/designed-3d-dna-crystals
#8
Nadrian C Seeman, Ruojie Sha, Jens Birktoft, Jianping Zheng, Wenyan Liu, Tong Wang, Chengde Mao
The simplest practical route to producing precisely designed 3D macroscopic objects is to form a crystalline arrangement by self-assembly, because such a periodic array has only conceptually simple requirements: a motif that has a robust 3D structure, dominant affinity interactions between parts of the motif when it self-associates, and predictable structures for these affinity interactions. Fulfilling these three criteria to produce a 3D periodic system is not easy, but should readily be achieved with well-structured branched DNA motifs tailed by sticky ends (Zheng et al...
2017: Methods in Molecular Biology
https://www.readbyqxmd.com/read/27705770/a-tensegrity-model-of-cell-reorientation-on-cyclically-stretched-substrates
#9
Guang-Kui Xu, Bo Li, Xi-Qiao Feng, Huajian Gao
Deciphering the mechanisms underlying the high sensitivity of cells to mechanical microenvironments is crucial for understanding many physiological and pathological processes, e.g., stem cell differentiation and cancer cell metastasis. Here, a cytoskeletal tensegrity model is proposed to study the reorientation of polarized cells on a substrate under biaxial cyclic deformation. The model consists of four bars, representing the longitudinal stress fibers and lateral actin network, and eight strings, denoting the microfilaments...
October 4, 2016: Biophysical Journal
https://www.readbyqxmd.com/read/27554017/inter-trabecular-angle-a-parameter-of-trabecular-bone-architecture-in-the-human-proximal-femur-that-reveals-underlying-topological-motifs
#10
Natalie Reznikov, Hila Chase, Yehonatan Ben Zvi, Victoria Tarle, Matthew Singer, Vlad Brumfeld, Ron Shahar, Steve Weiner
UNLABELLED: Trabecular bone is an intricate 3D network of struts and plates. Although the structure-function relations in trabecular bone have been studied since the time of Julius Wolff, controversy still exists regarding the architectural parameters responsible for its stability and resilience. We present a parameter that measures the angle between two connected trabeculae - the Inter-Trabecular Angle (ITA). We studied the ITA values derived from μCT scans of different regions of the proximal femora of 5 individuals of different age and sex...
October 15, 2016: Acta Biomaterialia
https://www.readbyqxmd.com/read/27546500/systems-specificity-in-responsiveness-to-intermittent-artificial-gravity-during-simulated-microgravity-in-rats
#11
Li-Fan Zhang, Shu Zhang
It has been shown that the minimum gravity exposure requirements vary greatly among different physiological systems. A preliminary comparison between two extremes, vessels vs. bones, shows that not only the mechanostat at the tissue level differs greatly, but also the bone loss during weightlessness may also involve calcium deposition-resorption changes. It seems that the surprising efficacy of intermittent artificial gravity (IAG) is due to the vascular tissues possessing a strong resilience or "memory" function toward restoring their original pre-stress and tensegrity state at the 1 G environment...
August 25, 2016: Sheng Li Xue Bao: [Acta Physiologica Sinica]
https://www.readbyqxmd.com/read/27465497/pivotal-debates-and-controversies-on-the-structure-and-function-of-the-avian-respiratory-system-setting-the-record-straight
#12
John N Maina
Among the extant air-breathing vertebrates, the avian respiratory system is structurally the most complex and functionally the most efficient gas exchanger. Having been investigated for over four centuries, some aspects of its biology have been extremely challenging and highly contentious and others still remain unresolved. Here, while assessing the most recent findings, four notable aspects of the structure and function of the avian respiratory system are examined critically to highlight the questions, speculations, controversies and debates that have arisen from past research...
July 28, 2016: Biological Reviews of the Cambridge Philosophical Society
https://www.readbyqxmd.com/read/27447563/the-mitotic-tensegrity-guardian-tau-protects-mammary-epithelia-from-katanin-like1-induced-aneuploidy
#13
Haruka Sudo, Kazunori Nakajima
The microtubule associated-protein tau has been identified as an effective positive prognostic indicator in breast cancer. To explore the physiological function of tau in early carcinogenesis, endogenous tau was knocked down in primary cultured human mammary epithelial cells. This resulted in chromosome-bridging during anaphase followed by micronucleation, both of which were suppressed by a further katanin-like1 knockdown. We also detected that the exogenously expressed katanin-like1 induction of cellular transformation is prevented by exogenous tau in rat fibroblasts...
August 16, 2016: Oncotarget
https://www.readbyqxmd.com/read/27444846/nonlinear-elasticity-of-semiflexible-filament-networks
#14
Fanlong Meng, Eugene M Terentjev
We develop a continuum theory for equilibrium elasticity of a network of crosslinked semiflexible filaments, spanning the full range between flexible entropy-driven chains to stiff athermal rods. We choose the 3-chain constitutive model of network elasticity over several plausible candidates, and derive analytical expressions for the elastic energy at arbitrary strain, with the corresponding stress-strain relationship. The theory fits well to a wide range of experimental data on simple shear in different filament networks, quantitatively matching the differential shear modulus variation with stress, with only two adjustable parameters (which represent the filament stiffness and the pre-tension in the network, respectively)...
August 10, 2016: Soft Matter
https://www.readbyqxmd.com/read/27389390/control-of-drop-shape-transformations-in-cooled-emulsions
#15
Diana Cholakova, Nikolai Denkov, Slavka Tcholakova, Ivan Lesov, Stoyan K Smoukov
The general mechanisms of structure and form generation are the keys to understanding the fundamental processes of morphogenesis in living and non-living systems. In our recent study (Denkov et al., Nature 528 (2015) 392) we showed that micrometer sized n-alkane drops, dispersed in aqueous surfactant solutions, can break symmetry upon cooling and "self-shape" into a series of geometric shapes with complex internal structure. This phenomenon is important in two contexts, as it provides: (a) new, highly efficient bottom-up approach for producing particles with complex shapes, and (b) remarkably simple system, from the viewpoint of its chemical composition, which exhibits the basic processes of structure and shape transformations, reminiscent of morphogenesis events in living organisms...
September 2016: Advances in Colloid and Interface Science
https://www.readbyqxmd.com/read/27265774/stabilisation-of-self-assembled-dna-crystals-by-triplex-directed-photo-cross-linking
#16
Hatem O Abdallah, Yoel P Ohayon, Arun Richard Chandrasekaran, Ruojie Sha, Keith R Fox, Tom Brown, David A Rusling, Chengde Mao, Nadrian C Seeman
The tensegrity triangle is a robust DNA motif that can self-assemble to generate macroscopic three-dimensional crystals. However, the stability of these crystals is dependent on the high ionic conditions used for crystal growth. Here we demonstrate that a triplex-forming oligonucleotide can be used to direct the specific intercalation, and subsequent photo-cross-linking, of 4,5',8-trimethylpsoralen to single or multiple loci within or between the tiles of the crystal. Cross-linking between the tiles of the crystal improves their thermal stability...
June 28, 2016: Chemical Communications: Chem Comm
https://www.readbyqxmd.com/read/26965444/the-organelle-of-differentiation-in-embryos-the-cell-state-splitter
#17
REVIEW
Natalie K Gordon, Richard Gordon
The cell state splitter is a membraneless organelle at the apical end of each epithelial cell in a developing embryo. It consists of a microfilament ring and an intermediate filament ring subtending a microtubule mat. The microtubules and microfilament ring are in mechanical opposition as in a tensegrity structure. The cell state splitter is bistable, perturbations causing it to contract or expand radially. The intermediate filament ring provides metastability against small perturbations. Once this snap-through organelle is triggered, it initiates signal transduction to the nucleus, which changes gene expression in one of two readied manners, causing its cell to undergo a step of determination and subsequent differentiation...
March 10, 2016: Theoretical Biology & Medical Modelling
https://www.readbyqxmd.com/read/26898230/break-of-symmetry-in-regenerating-tobacco-protoplasts-is-independent-of-nuclear-positioning
#18
Linda Brochhausen, Jan Maisch, Peter Nick
Nuclear migration and positioning are crucial for the morphogenesis of plant cells. We addressed the potential role of nuclear positioning for polarity induction using an experimental system based on regenerating protoplasts, where the induction of a cell axis de novo can be followed by quantification of specific regeneration stages. Using overexpression of fluorescently tagged extranuclear (perinuclear actin basket, kinesins with a calponin homology domain (KCH)) as well as intranuclear (histone H2B) factors of nuclear positioning and time-lapse series of the early stages of regeneration, we found that nuclear position is no prerequisite for polarity formation...
September 2016: Journal of Integrative Plant Biology
https://www.readbyqxmd.com/read/26780650/the-interphase-mammalian-chromosome-as-a-structural-system-based-on-tensegrity
#19
Armando Aranda-Anzaldo
Each mammalian chromosome is constituted by a DNA fiber of macroscopic length that needs to be fitted in a microscopic nucleus. The DNA fiber is subjected at physiological temperature to random thermal bending and looping that must be constrained so as achieve structural stability thus avoiding spontaneous rupturing of the fiber. Standard textbooks assume that chromatin proteins are primarily responsible for the packaging of DNA and so of its protection against spontaneous breakage. Yet the dynamic nature of the interactions between chromatin proteins and DNA is unlikely to provide the necessary long-term structural stability for the chromosomal DNA...
March 21, 2016: Journal of Theoretical Biology
https://www.readbyqxmd.com/read/26347645/reward-modulated-hebbian-plasticity-as-leverage-for-partially-embodied-control-in-compliant-robotics
#20
Jeroen Burms, Ken Caluwaerts, Joni Dambre
In embodied computation (or morphological computation), part of the complexity of motor control is offloaded to the body dynamics. We demonstrate that a simple Hebbian-like learning rule can be used to train systems with (partial) embodiment, and can be extended outside of the scope of traditional neural networks. To this end, we apply the learning rule to optimize the connection weights of recurrent neural networks with different topologies and for various tasks. We then apply this learning rule to a simulated compliant tensegrity robot by optimizing static feedback controllers that directly exploit the dynamics of the robot body...
2015: Frontiers in Neurorobotics
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