world function
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2021 ◽  
Author(s):  
Eva Bertosin ◽  
Christopher M. Maffeo ◽  
Thomas Drexler ◽  
Maximilian N. Honemann ◽  
Aleksei Aksimentiev ◽  
...  

AbstractBiological molecular motors transform chemical energy into mechanical work by coupling a cycle of catalytic reactions to large scale structural transitions. Mechanical deformation can be surprisingly efficient in realizing such coupling, as demonstrated by the celebrated example of F1FoATP synthase. Here, we describe a synthetic molecular mechanism that transforms a rotary motion of an asymmetric camshaft into reciprocating large-scale transitions in the structure of the surrounding stator orchestrated by mechanical deformation. We designed the mechanism using DNA origami, characterized the structure of the components and the entire mechanism using cryo-electron microscopy, and examined the mechanism’s dynamic behavior using single-particle fluorescence microscopy and molecular dynamics simulations. The data indicates that, while the camshaft can rotate inside the stator by diffusion, mechanical deformation of the stator makes the camshaft pause at a set of preferred orientations. By changing the mechanical stiffness of the stator, we could accelerate or suppress the Brownian rotation within the mechanism, thereby demonstrating an allosteric coupling between the movement of the camshaft and of the stator, and the ability to tailor the free energy landscape that governs the rotary motion. Our mechanism provides a framework for the manufacture of artificial nanomachines that, just like the man-made machines in the macroscopic world, function because of coordinated movements of their components.


2020 ◽  
Vol 177 ◽  
pp. 108099 ◽  
Author(s):  
Mark J. Millan ◽  
Anne Dekeyne ◽  
Alain Gobert ◽  
Mauricette Brocco ◽  
Clotilde Mannoury la Cour ◽  
...  

2019 ◽  
Vol 31 (1) ◽  
pp. 143-148
Author(s):  
Nikola Vidović ◽  
Milenko Dželetović ◽  
Hatidža Beriša

The paper focuses on a topic that explains the impact of credit flows on the conduct of monetary policy, as well as their impact on economic activities within national economies in certain countries in the world. Function and importance for the banking sector, as well as for all economic entities, which are categorized by company size, and the impact on the performance and realization of business activities.By comparing similarities and differences, there is a clear distinction between the basic banking channel of credit and the credit channel in the wider sense, as well as their degree of operation in the period before, during, and after the global economic crisis. The paper highlights the positive effects, as well as the negative, ie how their implementation affects the actors of a country's economic system and what are the consequences with a focus on demand, personal consumption, inflation and employment. The problems of adequate application of the model in periods of recession, as well as the degree of representation in developed countries, moderately developed, and countries in the transition period are studied.


2019 ◽  
Vol 28 (06) ◽  
pp. 1950079
Author(s):  
Dawood Kothawala

If there exists a lower bound [Formula: see text] to spacetime intervals which is Lorentz-invariant, then the effective description of spacetime that incorporates such a lower bound must necessarily be nonlocal. Such a nonlocal description can be derived using standard tools of differential geometry, but using as basic variables certain bi-tensors instead of the conventional metric tensor [Formula: see text]. This allows one to construct a qmetric [Formula: see text], using the Synge’s world function [Formula: see text] and the van Vleck determinant [Formula: see text], that incorporates the lower bound on spacetime intervals. The same nonanalytic structure of the reconstructed spacetime which renders a perturbative expansion in [Formula: see text] meaningless, will then also generically leave a non-trivial “relic” in the limit [Formula: see text]. We present specific results derived from [Formula: see text] where such a relic term manifests, and discuss several implications of the same. Specifically, we will discuss how these results: (i) suggest a description of gravitational dynamics different from the conventional one based on the Einstein–Hilbert Lagrangian, (ii) imply a dimensional reduction to [Formula: see text] at small scales and (iii) can be significant for the idea that the cosmological constant itself might be related to some nonlocal vestige of the small-scale structure of spacetime. We will conclude by discussing the ramifications of these ideas in the context of quantum gravity.


Author(s):  
Bahram Mashhoon

In extended general relativity (GR), Einstein’s field equation of GR can be expressed in terms of torsion and this leads to the teleparallel equivalent of GR, namely, GR||, which turns out to be the gauge theory of the Abelian group of spacetime translations. The structure of this theory resembles Maxwell’s electrodynamics. We use this analogy and the world function to develop a nonlocal GR|| via the introduction of a causal scalar constitutive kernel. It is possible to express the nonlocal gravitational field equation as modified Einstein’s equation. In this nonlocal gravity (NLG) theory, the gravitational field is local, but satisfies a partial integro-differential field equation. The field equation of NLG can be expressed as Einstein’s field equation with an extra source that has the interpretation of the effective dark matter. It is possible that the kernel of NLG, which is largely undetermined, could be derived from a more general future theory.


2017 ◽  
Vol 43 (suppl_1) ◽  
pp. S25-S25
Author(s):  
Adam Culbreth ◽  
Erin Moran ◽  
Andrew Westbrook ◽  
Julia Sheffield ◽  
Deanna Barch

2011 ◽  
Vol 26 (23) ◽  
pp. 1737-1751 ◽  
Author(s):  
B. LINET ◽  
P. TEYSSANDIER

A new method based on Synge's world function is developed for determining within the WKB approximation the gravitationally induced quantum phase shift of a particle propagating in a stationary spacetime. This method avoids any calculation of geodesics. A detailed treatment is given for relativistic particles within the weak field, linear approximation of any metric theory. The method is applied to the calculation of the oscillation terms governing the interference of neutrinos considered as the superposition of two eigenstates having different masses. It is shown that the neutrino oscillations are not sensitive to the gravitomagnetic components of the metric as long as the spin contributions can be ignored. Explicit calculations are performed when the source of the field is a spherical, homogeneous body. A comparison is made with previous results obtained in Schwarzschild spacetime.


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