scholarly journals Gaussian curvature directs the distribution of spontaneous curvature on bilayer membrane necks

2017 ◽  
Author(s):  
Morgan Chabanon ◽  
Padmini Rangamani
Keyword(s):  
Lipid Bilayers ◽  
Gaussian Curvature ◽  
Source Term ◽  
Bilayer Membrane ◽  
Fundamental Question ◽  
Spontaneous Curvature ◽  
Shape Equation ◽  
Curvature Distribution ◽  
Membrane Protein Interaction ◽  
The Relationship

ABSTRACTFormation of membrane necks is crucial for fission and fusion in lipid bilayers. In this work, we seek to answer the following fundamental question: what is the relationship between protein-induced spontaneous mean curvature and the Gaussian curvature at a membrane neck? Using an augmented Helfrich model for lipid bilayers to include membrane-protein interaction, we solve the shape equation on catenoids to find the field of spontaneous curvature that satisfies mechanical equilibrium of membrane necks. In this case, the shape equation reduces to a variable coefficient Helmholtz equation for spontaneous curvature, where the source term is proportional to the Gaussian curvature. We show how this latter quantity is responsible for non-uniform distribution of spontaneous curvature in minimal surfaces. We then explore the energetics of catenoids with different spontaneous curvature boundary conditions and geometric asymmetries to show how heterogeneities in spontaneous curvature distribution can couple with Gaussian curvature to result in membrane necks of different geometries.

scholarly journals Gaussian curvature directs the distribution of spontaneous curvature on bilayer membrane necks

Soft Matter ◽  
2018 ◽  
Vol 14 (12) ◽  
pp. 2281-2294 ◽  
Author(s):  
Morgan Chabanon ◽  
Padmini Rangamani
Keyword(s):  
Gaussian Curvature ◽  
Bilayer Membrane ◽  
Spontaneous Curvature

The energy to maintain a catenoid-shaped membrane neck with spontaneous curvature shows a barrier dependent on the neck asymmetry.

Religion and Toleration from the Enlightenment to the Post-Secular Era

2017 ◽  
Author(s):  
Rainer Forst
Keyword(s):  
Immanuel Kant ◽  
Recent Work ◽  
Common Ground ◽  
Fundamental Question ◽  
Modern World ◽  
Human Beings ◽  
Human Reason ◽  
The Enlightenment ◽  
Pierre Bayle ◽  
The Relationship

This chapter addresses the classical question of the relationship between enlightenment and religion. In doing so, the chapter compares Jürgen Habermas's thought to that of Pierre Bayle and Immanuel Kant. For, although Habermas undoubtedly stands in a tradition founded by Bayle and Kant, he develops a number of important orientations within this tradition and has changed his position in his recent work. The chapter studies this change to understand Habermas's position better. It also draws attention to a fundamental question raised by the modern world: what common ground can human reason establish in the practical and theoretical domain between human beings who are divided by profoundly different religious (including antireligious) views?

scholarly journals Self-Assembly of Shape-Tunable Oblate Colloidal Particles into Orientationally Ordered Crystals, Glassy Crystals and Plastic Crystals

Soft Matter ◽  
2021 ◽  
Author(s):  
Jiawei Lu ◽  
Xiangyu Bu ◽  
Xinghua Zhang ◽  
Bing Liu
Keyword(s):  
Crystal Structures ◽  
Self Assembly ◽  
Colloidal Particles ◽  
Building Blocks ◽  
Fundamental Question ◽  
The Self ◽  
Plastic Crystals ◽  
Self Assembled ◽  
Glassy Crystals ◽  
The Relationship

The shapes of colloidal particles are crucial to the self-assembled superstructures. Understanding the relationship between the shapes of building blocks and the resulting crystal structures is an important fundamental question....

scholarly journals What does it mean when we ask the public if they are ‘confident’ in policing? The trust, fairness, presence model of ‘public confidence’

2019 ◽  
Vol 22 (2) ◽  
pp. 111-122 ◽  
Author(s):  
Kevin Morrell ◽  
Ben Bradford ◽  
Basit Javid
Keyword(s):  
Survey Data ◽  
Good Evidence ◽  
Fundamental Question ◽  
Police Force ◽  
Public Confidence ◽  
Single Item ◽  
The Public ◽  
West Midlands ◽  
The Relationship ◽  
Part Model

‘Confidence’ is widely taken to be a crucial measure of the relationship between citizens and public services such as policing. It is acknowledged that confidence is multifaceted and hard to measure, but often discussions are based on one ‘headline’ rating of a single item, for instance: ‘What is your level of confidence in…’. The subsequent focus for research is explaining what might drive ‘confidence’, or what it might predict. We are interested in a more fundamental question: what does it mean when we ask the public if they are ‘confident’ in policing? To answer this, we analyse extensive and detailed survey data specifically designed to measure public confidence, within the jurisdiction of a UK police force – West Midlands Police. We develop then validate a three-part model of confidence as trust, fairness and presence, and find good evidence to support this model across different waves of the survey. This extends existing literature with implications for policy.

scholarly journals Fracture faces of frozen membranes: 50th anniversary

2016 ◽  
Vol 27 (3) ◽  
pp. 421-423
Author(s):  
Daniel Branton
Keyword(s):  
Electron Microscopy ◽  
Lipid Bilayers ◽  
Fracture Process ◽  
Relative Proportion ◽  
50Th Anniversary ◽  
Biological Membranes ◽  
Bilayer Membrane ◽  
Biological Cells ◽  
Membrane Surfaces ◽  
Freeze Etching

In 1961, the development of an improved freeze-etching (FE) procedure to prepare rapidly frozen biological cells or tissues for electron microscopy raised two important questions. How does a frozen cell membrane fracture? What do the extensive face views of the cell’s membranes exposed by the fracture process of FE tell us about the overall structure of biological membranes? I discovered that all frozen membranes tend to split along weakly bonded lipid bilayers. Consequently, the fracture process exposes internal membrane faces rather than either of the membrane’s two external surfaces. During etching, when ice is allowed to sublime after fracturing, limited regions of the actual membrane surfaces are revealed. Examination of the fractured faces and etched surfaces provided strong evidence that biological membranes are organized as lipid bilayers with some proteins on the surface and other proteins extending through the bilayer. Membrane splitting made it possible for electron microscopy to show the relative proportion of a membrane’s area that exists in either of these two organizational modes.

Instrument of Mobilization or a Bridge towards Understanding? Religion and Values in the Reform Process of the European Union

2009 ◽  
Vol 2 (3) ◽  
pp. 257-284 ◽  
Author(s):  
Christof Mandry
Keyword(s):  
European Union ◽  
Political Identity ◽  
Fundamental Question ◽  
Fundamental Rights ◽  
The Self ◽  
Reform Process ◽  
The European Union ◽  
Charter Of Fundamental Rights ◽  
The Relationship ◽  
The Eu

AbstractThe self-understanding of the Europeans has been profoundly put into question since 1989, and during the EU reform process, 'Europe' was confronted by the task of describing itself anew. In this context, the debate about the significance of the religious patrimony took on a key position in the discourse. The broad public discussions of the preambles to the European Charter of Fundamental Rights and the Treaty establishing a Constitution for the European Union (ECT) indicate that the relationship between religion and political remains a controversial issue. The article argues that the 'preamble disputes' are part and parcel of the European Union's quest for a political identity and that the outcome of the identity debate—the self-description as a 'community of values'—deals in a specific way with this fundamental question.

EQUIVALENCE OF THE TWO METHODS IN CALCULATING THE EQUILIBRIUM SHAPES OF CYLINDRICAL VESICLES

1999 ◽  
Vol 13 (16) ◽  
pp. 547-553
Author(s):  
SHAOGUANG ZHANG ◽  
ZHONGCAN OUYANG ◽  
JIXING LIU
Keyword(s):  
Differential Equations ◽  
Ordinary Differential Equations ◽  
The Other ◽  
General Shape ◽  
Calculus Of Variation ◽  
And Topology ◽  
Shape Equation ◽  
Equilibrium Shapes ◽  
Comparison Of The Results ◽  
The Relationship

So far, two methods are often used in solving the equilibrium shapes of vesicles. One method is by starting with the general shape equation and restricting it to the shapes with particular symmetry. The other method is by assuming the symmetry and topology of the vesicle first and treating it with the calculus of variation to get a set of ordinary differential equations. The relationship between these two methods in the case of cylindrical vesicles, and a comparison of the results are given.

Sikhism and Islam: A Structural Analysis

2019 ◽  
pp. 209-232
Author(s):  
J.P.S. Uberoi
Keyword(s):  
Structural Analysis ◽  
Fundamental Question ◽  
Central Theme ◽  
Political Aspect ◽  
Contemporary World ◽  
Definition Of ◽  
The Relationship ◽  
Structural Definition

This chapter outlines the author’s structural definition of the problems involved in the theoretical and practical relations between Sikhism and Islam in terms of religion, history and society since the time of Guru Nanak through the various vicissitudes that were to follow. It contains a synchronous analysis of the structure of the discourse of religion as well as an analysis of the structure of the discourse of history, that is, the diachronous political aspect of the relation. The issues of the unity and duality of the religious and political aspects of life in both the medieval and the contemporary world are a central theme and lead to the more fundamental question of plurality in Indian modernity. Also included is a discussion on non-Sanskritic sects and the relationship between the Mughals and the Sikhs.

CRYO-Tem Measurements of Membrane Elasticity in Equilibrium Vesicle Systems: Two Distinct Mechanisms of Stability

2000 ◽  
Vol 6 (S2) ◽  
pp. 848-849
Author(s):  
B. Coldren ◽  
H.T. Jung ◽  
J. Zasadzinski
Keyword(s):  
Lipid Bilayers ◽  
Spontaneous Curvature ◽  
Aqueous Mixtures ◽  
Membrane Elasticity ◽  
Theoretical Concepts ◽  
Curvature Energy ◽  
Nanomaterials Synthesis ◽  
Equilibrium Phases ◽  
Image Position ◽  
New Applications

Aqueous mixtures of oppositely charged surfactants spontaneously form equilibrium phases of unilamellar vesicles.1 The wide variety of surfactants that display this behavior allows control over vesicle charge, size, and polydispersity. This may be useful for new applications in drug delivery, nanomaterials synthesis, and as tests of theoretical concepts of membrane organization and interactions.A subtle competition between the entropy of mixing and the elastic properties of surfactant and lipid bilayers determines their phase behavior and morphology. The curvature energy per unit area of bilayer, fc, iswhere R1 and R2 are the principle radii of curvature, K is the curvature modulus, and is the saddle-splay modulus. The spontaneous curvature, l/ro, is nonzero only if there is asymmetry between the two sides of the bilayer.

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