scholarly journals Bacterial spinning top

2019 ◽  
Vol 880 ◽  
pp. 620-652 ◽  
Author(s):  
Kenta Ishimoto

We have investigated the dynamics of a monotrichous bacteria cell near a wall boundary, taking elastic hook flexibility into consideration. Combining theoretical linear stability analysis and direct numerical computations via the boundary element method, we have found that the elastohydrodynamic coupling between the hook elasticity and cell rotational motion enables a stable vertical spinning behaviour like a low-Reynolds-number spinning top. The forwardly rotated flagellum, which generates the force exertion pushing towards the cell body, typically destabilizes the vertical upright position and leads to a boundary-following motion. In contrast, the backward rotation of the flagellum, generating a force pulling the cell body, contributes to stable upright behaviour in a large range of hook rigidity. Further numerical investigations have demonstrated that the non-spherical geometry of the cell body and boundary adhesive interactions affect the bacterial dynamics, leading to complex behaviours such as horizontal spinning and unstable vertical spinning motions, both of which are experimentally observed in Pseudomonas aeruginosa bacteria. These results highlight the rich diversity of bacterial surface motility emerging from mechanical boundary interactions coupled with the cell swimming and hook flexibility.

Author(s):  
Stefan Winter

This concluding chapter summarizes key themes and presents some final thoughts. The book has shown that the multiplicity of lived ʻAlawi experiences cannot be reduced to the sole question of religion or framed within a monolithic narrative of persecution; that the very attempt to outline a single coherent history of “the ʻAlawis” may indeed be misguided. The sources on which this study has drawn are considerably more accessible, and the social and administrative realities they reflect consistently more mundane and disjointed, than the discourse of the ʻAlawis' supposed exceptionalism would lead one to believe. Therefore, the challenge for historians of ʻAlawi society in Syria and elsewhere is not to use the specific events and structures these sources detail to merely add to the already existing metanarratives of religious oppression, Ottoman misrule, and national resistance but rather to come to a newer and more intricate understanding of that community, and its place in wider Middle Eastern society, by investigating the lives of individual ʻAlawi (and other) actors within the rich diversity of local contexts these sources reveal.


2018 ◽  
Vol 16 (1) ◽  
pp. 112-119
Author(s):  
VLADIMIR GLEB NAYDONOV

The article considers the students’ tolerance as a spectrum of personal manifestations of respect, acceptance and correct understanding of the rich diversity of cultures of the world, values of others’ personality. The purpose of the study is to investgate education and the formation of tolerance among the students. We have compiled a training program to improve the level of tolerance for interethnic differences. Based on the statistical analysis of the data obtained, the most important values that are significant for different levels of tolerance were identified.


2021 ◽  
Author(s):  
Valentin Waschulin ◽  
Chiara Borsetto ◽  
Robert James ◽  
Kevin K. Newsham ◽  
Stefano Donadio ◽  
...  

AbstractThe growing problem of antibiotic resistance has led to the exploration of uncultured bacteria as potential sources of new antimicrobials. PCR amplicon analyses and short-read sequencing studies of samples from different environments have reported evidence of high biosynthetic gene cluster (BGC) diversity in metagenomes, indicating their potential for producing novel and useful compounds. However, recovering full-length BGC sequences from uncultivated bacteria remains a challenge due to the technological restraints of short-read sequencing, thus making assessment of BGC diversity difficult. Here, long-read sequencing and genome mining were used to recover >1400 mostly full-length BGCs that demonstrate the rich diversity of BGCs from uncultivated lineages present in soil from Mars Oasis, Antarctica. A large number of highly divergent BGCs were not only found in the phyla Acidobacteriota, Verrucomicrobiota and Gemmatimonadota but also in the actinobacterial classes Acidimicrobiia and Thermoleophilia and the gammaproteobacterial order UBA7966. The latter furthermore contained a potential novel family of RiPPs. Our findings underline the biosynthetic potential of underexplored phyla as well as unexplored lineages within seemingly well-studied producer phyla. They also showcase long-read metagenomic sequencing as a promising way to access the untapped genetic reservoir of specialised metabolite gene clusters of the uncultured majority of microbes.


Science ◽  
2013 ◽  
Vol 341 (6147) ◽  
pp. 746-751 ◽  
Author(s):  
Jeffery L. Dangl ◽  
Diana M. Horvath ◽  
Brian J. Staskawicz

Diverse and rapidly evolving pathogens cause plant diseases and epidemics that threaten crop yield and food security around the world. Research over the last 25 years has led to an increasingly clear conceptual understanding of the molecular components of the plant immune system. Combined with ever-cheaper DNA-sequencing technology and the rich diversity of germ plasm manipulated for over a century by plant breeders, we now have the means to begin development of durable (long-lasting) disease resistance beyond the limits imposed by conventional breeding and in a manner that will replace costly and unsustainable chemical controls.


This exciting new Handbook offers a comprehensive overview of the contemporary state of the field. The editors’ introduction and forty-five essays cover feminist critical engagements with philosophy and adjacent scholarly fields, as well as feminist approaches to current debates and crises across the world. Authors cover topics ranging from the ways in which feminist philosophy attends to other systems of oppression, and the gendered, racialized, and classed assumptions embedded in philosophical concepts, to feminist perspectives on prominent subfields of philosophy. The first section contains chapters that explore feminist philosophical engagement with mainstream and marginalized histories and traditions, while the second section parses feminist philosophy’s contributions to with numerous philosophical subfields, for example metaphysics and bioethics. A third section explores what feminist philosophy can illuminate about crucial moral and political issues of identity, gender, the body, autonomy, prisons, among numerous others. The Handbook concludes with the field’s engagement with other theories and movements, including trans studies, queer theory, critical race, theory, postcolonial theory, and decolonial theory. The volume provides a rigorous but accessible resource for students and scholars who are interested in feminist philosophy, and how feminist philosophers situate their work in relation to the philosophical mainstream and other disciplines. Above all it aims to showcase the rich diversity of subject matter, approach, and method among feminist philosophers.


2016 ◽  
Vol 8 (3) ◽  
pp. 360-369
Author(s):  
Devi A.G. PRASAD ◽  
Shwetha BHARATHI

Sacred groves are one of the finest examples of informal way of conserving the forest wealth. Baseline data collection of their diversity, distribution and regeneration capacity becomes necessary for the management and conservation of these undisturbed forest patches. In this context, the present investigation was carried out using random quadrat method in the sacred groves of Virajpet, Karnataka, India. A total of 132 tree species belonging to 113 genera and 45 families were identified within five sacred groves. Higher basal area (51.73-85.65 m2/ha) and tree density (453.33-515.9 individuals/ha) were observed as compared to other forests of Western Ghats region. The present investigation has revealed a healthy regeneration of tree species. Seedling and sapling composition differed to some extent from the mature tree species composition which could be used in predicting the future possibilities. Protection and conservation of such sacred groves should be of interest, for better regeneration of the rich diversity they harbour.


2010 ◽  
Vol 30 (8) ◽  
pp. 1412-1431 ◽  
Author(s):  
David W Howells ◽  
Michelle J Porritt ◽  
Sarah SJ Rewell ◽  
Victoria O'Collins ◽  
Emily S Sena ◽  
...  

No single animal model is able to encompass all of the variables known to affect human ischemic stroke. This review highlights the major strengths and weaknesses of the most commonly used animal models of acute ischemic stroke in the context of matching model and experimental aim. Particular emphasis is placed on the relationships between outcome and underlying vascular variability, physiologic control, and use of models of comorbidity. The aim is to provide, for novice and expert alike, an overview of the key controllable determinants of experimental stroke outcome to help ensure the most effective application of animal models to translational research.


Humanities ◽  
2018 ◽  
Vol 7 (3) ◽  
pp. 78 ◽  
Author(s):  
James Baumlin ◽  
Craig Meyer

The aim of this essay is to introduce, contextualize, and provide rationale for texts published in the Humanities special issue, Histories of Ethos: World Perspectives on Rhetoric. It surveys theories of ethos and selfhood that have evolved since the mid-twentieth century, in order to identify trends in discourse of the new millennium. It outlines the dominant theories—existentialist, neo-Aristotelian, social-constructionist, and poststructuralist—while summarizing major theorists of language and culture (Archer, Bourdieu, Foucault, Geertz, Giddens, Gusdorf, Heidegger). It argues for a perspectivist/dialectical approach, given that no one theory comprehends the rich diversity of living discourse. While outlining the “current state of theory,” this essay also seeks to predict, and promote, discursive practices that will carry ethos into a hopeful future. (We seek, not simply to study ethos, but to do ethos.) With respect to twenty-first century praxis, this introduction aims at the following: to acknowledge the expressive core of discourse spoken or written, in ways that reaffirm and restore an epideictic function to ethos/rhetoric; to demonstrate the positionality of discourse, whereby speakers and writers “out themselves” ethotically (that is, responsively and responsibly); to explore ethos as a mode of cultural and embodied personal narrative; to encourage an ethotic “scholarship of the personal,” expressive of one’s identification/participation with/in the subject of research; to argue on behalf of an iatrological ethos/rhetoric based in empathy, care, healing (of the past) and liberation/empowerment (toward the future); to foster interdisciplinarity in the study/exploration/performance of ethos, establishing a conversation among scholars across the humanities; and to promote new versions and hybridizations of ethos/rhetoric. Each of the essays gathered in the abovementioned special issue achieves one or more of these aims. Most are “cultural histories” told within the culture being surveyed: while they invite criticism as scholarship, they ask readers to serve as witnesses to their stories. Most of the authors are themselves “positioned” in ways that turn their texts into “outings” or performances of gender, ethnicity, “race,” or ability. And most affirm the expressive, epideictic function of ethos/rhetoric: that is, they aim to display, affirm, and celebrate those “markers of identity/difference” that distinguish, even as they humanize, each individual and cultural storytelling. These assertions and assumptions lead us to declare that Histories of Ethos, as a collection, presents a whole greater than its essay-parts. We conceive it, finally, as a conversation among theories, histories, analyses, praxes, and performances. Some of this, we know, goes against the grain of modern (Western) scholarship, which privileges analysis over narrative and judges texts against its own logocentric commitments. By means of this introduction and collection, we invite our colleagues in, across, and beyond the academy “to see differently.” Should we fall short, we will at least have affirmed that some of us “see the world and self”—and talk about the world and self—through different lenses and within different cultural vocabularies and positions.


PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e3836 ◽  
Author(s):  
Erin C. McKiernan ◽  
Diano F. Marrone

Neuron types (e.g., pyramidal cells) within one area of the brain are often considered homogeneous, despite variability in their biophysical properties. Here we review literature demonstrating variability in the electrical activity of CA1 hippocampal pyramidal cells (PCs), including responses to somatic current injection, synaptic stimulation, and spontaneous network-related activity. In addition, we describe how responses of CA1 PCs vary with development, experience, and aging, and some of the underlying ionic currents responsible. Finally, we suggest directions that may be the most impactful in expanding this knowledge, including the use of text and data mining to systematically study cellular heterogeneity in more depth; dynamical systems theory to understand and potentially classify neuron firing patterns; and mathematical modeling to study the interaction between cellular properties and network output. Our goals are to provide a synthesis of the literature for experimentalists studying CA1 PCs, to give theorists an idea of the rich diversity of behaviors models may need to reproduce to accurately represent these cells, and to provide suggestions for future research.


Biomolecules ◽  
2021 ◽  
Vol 11 (10) ◽  
pp. 1468
Author(s):  
Charles D. Morin ◽  
Eric Déziel

Pseudomonas aeruginosa is a motile bacterium able to exhibit a social surface behaviour known as swarming motility. Swarming requires the polar flagellum of P. aeruginosa as well as the secretion of wetting agents to ease the spread across the surface. However, our knowledge on swarming is limited to observed phenotypes on agar-solidified media. To study the surface behaviour and the impact of wetting agents of P. aeruginosa on other surfaces, we assessed surface motility capabilities of the prototypical strain PA14 on semi-solid media solidified with alternative gelling agents, gellan gum and carrageenan. We found that, on these alternative surfaces, the characteristic dendritic spreading pattern of P. aeruginosa is drastically altered. One striking feature is the loss of dependence on rhamnolipids to spread effectively on plates solidified with these alternative gelling agents. Indeed, a rhlA-null mutant unable to produce its wetting agents still spreads effectively, albeit in a circular shape on both the gellan gum- and carrageenan-based media. Our data indicate that rhamnolipids do not have such a crucial role in achieving surface colonization of non-agar plates, suggesting a strong dependence on the physical properties of the tested surface. The use of alternative gelling agent provides new means to reveal unknown features of bacterial surface behaviour.


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