scholarly journals Biomechanical ordering of dense cell populations

2008 ◽  
Vol 105 (40) ◽  
pp. 15346-15351 ◽  
Author(s):  
Dmitri Volfson ◽  
Scott Cookson ◽  
Jeff Hasty ◽  
Lev S. Tsimring
Keyword(s):  
Spatial Organization ◽  
Aqueous Media ◽  
Cell Communication ◽  
Fundamental Aspect ◽  
Cell Dynamics ◽  
Bacterial Populations ◽  
Tensor Order ◽  
Local Cell ◽  
Discrete Element Simulations ◽  
The Relationship

The structure of bacterial populations is governed by the interplay of many physical and biological factors, ranging from properties of surrounding aqueous media and substrates to cell–cell communication and gene expression in individual cells. The biomechanical interactions arising from the growth and division of individual cells in confined environments are ubiquitous, yet little work has focused on this fundamental aspect of colony formation. We analyze the spatial organization of Escherichia coli growing in a microfluidic chemostat. We find that growth and expansion of a dense colony of cells leads to a dynamical transition from an isotropic disordered phase to a nematic phase characterized by orientational alignment of rod-like cells. We develop a continuum model of collective cell dynamics based on equations for local cell density, velocity, and the tensor order parameter. We use this model and discrete element simulations to elucidate the mechanism of cell ordering and quantify the relationship between the dynamics of cell proliferation and the spatial structure of the population.

Abstract 17071: Cell Communication Inference in Macrophages

Circulation ◽  
2020 ◽  
Vol 142 (Suppl_3) ◽  
Author(s):  
Nika Taghdiri ◽  
Kevin R King ◽  
David Calcagno ◽  
Zhenxing Fu ◽  
Kenneth Huang ◽  
...  
Keyword(s):  
Image Analysis ◽  
Analytical Methods ◽  
Cell Injury ◽  
Diffusion Mechanism ◽  
Cell Communication ◽  
In Vivo Studies ◽  
Cell Dynamics ◽  
Calcium Indicator

Introduction: Tissue macrophages play diverse roles in the cardiovascular system during health and disease. They have diverse functions within tissues, but our understanding of their dynamics is limited because most macrophage characterization assays are destructive and have low temporal resolution. We asked whether these cells are dynamic and interconnected. Methods: Here, we describe experimental and analytical methods for measuring cell dynamics and inferring communication between cells in vitro and in vivo. We created a mouse (Csf1r-Cre x GCaMP5) expressing the Cre-inducible genetically encoded calcium indicator GCaMP5 under the regulation of the innate immune promoter, Csf1r, to non-destructively quantify high-frequency cell dynamics and differentiated them in culture using m-CSF. We developed custom image analysis routines and parameterization strategies for classifying calcium responses. Results: Our studies revealed that calcium reporter BMDMs display minimal fluctuations at baseline but exhibit a dynamic response to immunogenic DNA sensing. DNA-induced isolated cell injury and death, which precipitated cell communication that spread with a velocity of [9μm/s], consistent with an extracellular diffusion mechanism. We developed quantitative image analysis methods that corrected for random calcium fluctuations and identified statistically significant areas of correlated calcium changes suggestive of communication. An analytical pipeline enabled quantification of calcium spike dynamics and correlations of dynamic calcium profiles of single cell sharing a local microenvironment. This resulted in an “improbable synchrony” metric that allowed localization of communication in time and space. We adapted the pipeline for in vivo studies and tested them in a dorsal window chamber model using intravital microscopy. At 2Hz sampling frequency, we identified 27 potential communication events as they responded to complex microenvironmental cues in vivo. Conclusion: The experimental and analytical methods for inferring cell communication provide a new quantitative toolkit for investigating known as-yet undiscovered cell communication pathways.

scholarly journals The influence of forest-forming tree species on diversity and spatial distribution of algae in forest litter

2018 ◽  
Vol 45 (2) ◽  
pp. 72-81 ◽  
Author(s):  
Yevhen Maltsev ◽  
Irina Maltseva
Keyword(s):  
Species Richness ◽  
Leaf Litter ◽  
Green Algae ◽  
Tree Species ◽  
Spatial Organization ◽  
Forest Litter ◽  
Equal Distribution ◽  
Blue Green Algae ◽  
Different Types ◽  
The Relationship

Abstract The forest litter plays a significant role in forest ecosystems. The composition of the litter biota comprises micro- and mesofauna, and a great diversity of microorganisms, including unrecognized algae (eukaryotic representatives and Cyanoprokaryota). The aim of this work was to study the diversity of algae in the different types of forest litters and to clarify the relationship between the algae composition and the forest-forming tree species. Our results show that the pine forest litter is the most appropriate habitat for the development of green and yellow-green algae and that this litter type limits the variety of blue-green ones. The admixture of deciduous leaf litter to pine litter caused an increase in the species richness of blue-green algae and diatoms. The algae were unevenly distributed across the sub-horizons of pine litter. The highest species richness of algae was identified in the enzymatic sub-horizon of litter. The peculiarity of the composition of leaf litter algae was a significant variety of green, yellow-green and blue-green algae. The spatial organization of algae communities in the leaf litter was characterized by equal distribution of algae species in the litter-subhorizons.

scholarly journals ‘Learning to Be More Human’: Perspectives of Respect Within Prison Education in an Irish Young Offenders institution

2017 ◽  
Vol 4 (1) ◽  
Author(s):  
Emmanuel O'Grady
Keyword(s):  
Prison Education ◽  
Fundamental Aspect ◽  
Young Offenders ◽  
Human Beings ◽  
The Core ◽  
Primary Function ◽  
Considerable Impact ◽  
The Relationship

Respect is fundamental aspect of how human beings relate to each other and, arguably, is a significant factor in the relationship between student and teacher. For incarcerated adults, the relationships they foster with their teachers (and by extension the respect or disrespect cultivated within it) often has a considerable impact on their educative development. This research explores how respect, and disrespect, is perceived to be communicated within prison education by 13 prisoners and 13 teachers in an Irish Young Offenders institution. The values at the core of prison educators’ practice and their capacity to promote self-respect within their students emerged as central to this cultivation of respect. The place of socialisation within these educative relationships also emerged as a prominent factor and is discussed in relation to MacMurray’s (2012) assertion that the primary function of education is ‘learning to be human’

Japanese Phenomenology

2015 ◽  
pp. 630-648 ◽  
Author(s):  
Tōru Tani
Keyword(s):  
Twentieth Century ◽  
Fundamental Aspect ◽  
Human Relationships ◽  
Early Twentieth Century ◽  
Nishida Kitaro ◽  
The Relationship

This chapter is an introduction to Japanese phenomenology, which was brought to Japan in the early twentieth century by Nishida Kitarō and others, soon after Husserl launched the movement in Germany. Beginning with a brief historical and cultural overview, the chapter focuses on four major phenomenologists: Sakabe Megumi, Nitta Yoshihiro, Noé Keiichi, and Washida Kiyokazu. Each of the four, each in a different way, articulates a fundamental aspect of Japanese phenomenology: the criticism of subject-object dualism and the attending idea of an autonomous being-in-itself. All attempt to inquire more deeply into the nondual dimensions underlying that dualism: Sakabe through an inquiry into betweenness (aida or awai), encounter, and reflection (utsushi); Nitta by probing the depths of “verticality” and “mediality”; Noé by investigating the relationship between narrative and experience; and Washida by transgressing the borders of philosophy and pursuing more “reversibility” in human relationships.

scholarly journals Geometrical reorganization of Dectin-1 and TLR2 on single phagosomes alters their synergistic immune signaling

2019 ◽  
Vol 116 (50) ◽  
pp. 25106-25114 ◽  
Author(s):  
Wenqian Li ◽  
Jun Yan ◽  
Yan Yu
Keyword(s):  
Immune Responses ◽  
Immune Regulation ◽  
Spatial Organization ◽  
Innate Immune ◽  
Innate Immune Responses ◽  
Membrane Composition ◽  
Intracellular Compartments ◽  
Synergistic Regulation ◽  
The Relationship

Receptors of innate immune cells function synergistically to detect pathogens and elicit appropriate immune responses. Many receptor pairs also appear “colocalized” on the membranes of phagosomes, the intracellular compartments for pathogen ingestion. However, the nature of the seemingly receptor colocalization and the role it plays in immune regulation are unclear, due to the inaccessibility of intracellular phagocytic receptors. Here, we report a geometric manipulation technique to directly probe the role of phagocytic receptor “colocalization” in innate immune regulation. Using particles with spatially patterned ligands as phagocytic targets, we can decouple the receptor pair, Dectin-1 and Toll-like receptor (TLR)2, to opposite sides on a single phagosome or bring them into nanoscale proximity without changing the overall membrane composition. We show that Dectin-1 enhances immune responses triggered predominantly by TLR2 when their centroid-to-centroid proximity is <500 nm, but this signaling synergy diminishes upon receptor segregation beyond this threshold distance. Our results demonstrate that nanoscale proximity, not necessarily colocalization, between Dectin-1 and TLR2 is required for their synergistic regulation of macrophage immune responses. This study elucidates the relationship between the spatial organization of phagocytic receptors and innate immune responses. It showcases a technique that allows spatial manipulation of receptors and their signal cross-talk on phagosomes inside living cells.

scholarly journals Ambiance through Spatial Organization in Vernacular architecture of hot and dry regions of India − The case of Ahmedabad and Jodhpur

2019 ◽  
Vol 64 ◽  
pp. 03002
Author(s):  
Vibha Gajjar ◽  
Foram Bhavsar
Keyword(s):  
Spatial Organization ◽  
Vernacular Architecture ◽  
Movement Analysis ◽  
Graph Analysis ◽  
Climatic Regions ◽  
Spatial Morphology ◽  
Visibility Graph Analysis ◽  
Relationship Of ◽  
Digital Simulations ◽  
The Relationship

Most notable vernacular settlements of the past had a potential of generating stimulating ambiance because of their “organicness”. The understanding of the “Nature of order” in this informality can identify the factors or parameters generating the definite spatial character appropriate for the time and place. The spatial character generates the spirit of the place, what we call the genius loci. This paper analyses the relationship of spatial organization and ambiance of the old city settlements in hot and dry climatic regions of two selected cities of India − Ahmedabad and Jodhpur at various levels. Both the selected cities are informal in nature and rich with its ambiance. Space syntax and digital simulations are used to decode the parameters of the spatial organization. The spatial morphology is analysed using tools such as justified graph analysis, visibility graph analysis, isovists analysis, agent movement analysis and sunlight study. The result of the study is summarised in tabular format and presented in a graphical manner for better understanding. This analysis is valuable in the derivation of the constants and variables to define the learning from the vernacular spatial organization.

Candidate Positioning and Voter Choice

2008 ◽  
Vol 102 (3) ◽  
pp. 303-318 ◽  
Author(s):  
MICHAEL TOMZ ◽  
ROBERT P. VAN HOUWELING
Keyword(s):  
Health Care Policy ◽  
Formal Theory ◽  
Fundamental Aspect ◽  
Care Policy ◽  
Policy Positions ◽  
Voter Choice ◽  
Nationally Representative ◽  
Proximity Voting ◽  
The Relationship ◽  
Theory And Experiments

This article examines a fundamental aspect of democracy: the relationship between the policy positions of candidates and the choices of voters. Researchers have suggested three criteria—proximity, direction, and discounting—by which voters might judge candidates' policy positions. More than 50 peer-reviewed articles, employing data from more than 20 countries, have attempted to adjudicate among these theories. We explain why existing data and methods are insufficient to estimate the prevalence of these criteria in the electorate. We then formally derive an exhaustive set of critical tests: situations in which the criteria predict different vote choices. Finally, through survey experiments concerning health care policy, we administer the tests to a nationally representative sample. We find that proximity voting is about twice as common as discounting and four times as common as directional voting. Furthermore, discounting is most prevalent among ideological centrists and nonpartisans, who make sophisticated judgments that help align policy with their preferences. These findings demonstrate the promise of combining formal theory and experiments to answer previously intractable questions about democracy.

scholarly journals Intercellular adhesion promotes clonal mixing in growing bacterial populations

2018 ◽  
Vol 15 (146) ◽  
pp. 20180406 ◽  
Author(s):  
Anton Kan ◽  
Ilenne Del Valle ◽  
Tim Rudge ◽  
Fernán Federici ◽  
Jim Haseloff
Keyword(s):  
Spatial Organization ◽  
Single Cells ◽  
Computational Modelling ◽  
Colony Growth ◽  
Intercellular Adhesion ◽  
Adhesive Properties ◽  
Bacterial Populations ◽  
Intercellular Interactions ◽  
Solid Media ◽  
Adhesin Protein

Dense bacterial communities, known as biofilms, can have functional spatial organization driven by self-organizing chemical and physical interactions between cells, and their environment. In this work, we investigated intercellular adhesion, a pervasive property of bacteria in biofilms, to identify effects on the internal structure of bacterial colonies. We expressed the self-recognizing ag43 adhesin protein in Escherichia coli to generate adhesion between cells, which caused aggregation in liquid culture and altered microcolony morphology on solid media. We combined the adhesive phenotype with an artificial colony patterning system based on plasmid segregation, which marked clonal lineage domains in colonies grown from single cells. Engineered E. coli were grown to colonies containing domains with varying adhesive properties, and investigated with microscopy, image processing and computational modelling techniques. We found that intercellular adhesion elongated the fractal-like boundary between cell lineages only when both domains within the colony were adhesive, by increasing the rotational motion during colony growth. Our work demonstrates that adhesive intercellular interactions can have significant effects on the spatial organization of bacterial populations, which can be exploited for biofilm engineering. Furthermore, our approach provides a robust platform to study the influence of intercellular interactions on spatial structure in bacterial populations.

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