The unperturbed state of dendrimers

2000 ◽  
Vol 113 (20) ◽  
pp. 9288-9293 ◽  
Author(s):  
Fabio Ganazzoli ◽  
Roberto La Ferla
Keyword(s):  
Unperturbed State

Influence of Distributed Dislocations on Stability of Hollow Nonlinearly Elastic Sphere

2020 ◽  
pp. 17-21
Author(s):  
Evgeniya V. Goloveshkina
Keyword(s):  
Boundary Value Problem ◽  
Elasticity Theory ◽  
Elastic Body ◽  
Nonlinear Elasticity ◽  
External Pressure ◽  
Elastic Sphere ◽  
Unperturbed State ◽  
Nonlinear Elasticity Theory ◽  
Edge Dislocations ◽  
Distributed Dislocations

The phenomenon of stability loss of a hollow elastic sphere containing distributed dislocations and loaded with external hydrostatic pressure is studied. The study was carried out in the framework of the nonlinear elasticity theory and the continuum theory of continuously distributed dislocations. An exact statement and solution of the stability problem for a three-dimensional elastic body with distributed dislocations are given. The static problem of nonlinear elasticity theory for a body with distributed dislocations is reduced to a system of equations consisting of equilibrium equations, incompatibility equations with a given dislocation density tensor, and constitutive equations of the material. The unperturbed state is caused by external pressure and a spherically symmet-ric distribution of dislocations. For distributed edge dislocations in the framework of a harmonic (semi-linear) mate-rial model, the unperturbed state is defined as an exact spherically symmetric solution to a nonlinear boundary value problem. This solution is valid for any function that characterizes the density of edge dislocations. The perturbed equilibrium state is described by a boundary value problem linearized in the neighborhood of the equilibrium. The analysis of the axisymmetric buckling of the sphere was performed using the bifurcation method. It consists in determining the equilibrium positions of an elastic body, which differ little from the unperturbed state. By solving the linearized problem, the value of the external pressure at which the sphere first loses stability is found. The effect of dislocations on the buckling of thin and thick spherical shells is analyzed.

Stability of parallel flow of a multi-component cylindrical plasma to electrostatic perturbations

1981 ◽  
Vol 26 (2) ◽  
pp. 369-383
Author(s):  
R. Lucas
Keyword(s):  
Normal Mode ◽  
Axial Velocity ◽  
Sufficient Conditions ◽  
Parallel Flow ◽  
Zeroth Order ◽  
Unperturbed State ◽  
Plasma Component ◽  
Cylindrical Plasma ◽  
The Stability ◽  
System Variables

Sufficient conditions for the stability of parallel flow of a warm N-component cylindrical plasma to electrostatic perturbations are obtained. In the unperturbed state the jth plasma component is assumed to have axial velocity Vj0(r), r being the radial co-ordinate, and the equilibrium quantities are permitted to be arbitrary functions of r consistent with the zeroth-order equations. The L2-norms of certain system variables are shown to be bounded uniformly in time. Circle theorems are obtained for the complex eigenfrequencies of any normal mode.

Note on magneto-hydrodynamic gravitational stability of a double fluids interface

2008 ◽  
Vol 86 (3) ◽  
pp. 477-485
Author(s):  
Ahmed E Radwan ◽  
Mourad F Dimian
Keyword(s):  
Dispersion Relation ◽  
Present Model ◽  
The Self ◽  
Wave Number ◽  
Symmetric Mode ◽  
Fluid Interface ◽  
Unperturbed State ◽  
Gravitational Stability ◽  
The Stability ◽  
Range Force

The magneto–gravitational stability of double-fluid interface is discussed. The pressure in the unperturbed state is not constant because the self-gravitating force is a long-range force. The dispersion relation is derived and discussed. The self-gravitating model is unstable in the symmetric mode m = 0 (m is the transverse wave number), while it is stable in all other states. The effects of the densities, the liquid-fluid radii ratios, and the electromagnetic force on the stability of the present model are identified for all wavelengths.PACS Nos.: 47.35.Tv, 47.65.–d, 04.40.–b

Unperturbed state and solitary structures in an electron-positron plasma having dust impurity and density inhomogeneity

2014 ◽  
Vol 80 (4) ◽  
pp. 629-641 ◽  
Author(s):  
Hitendra K. Malik ◽  
Rakhee Malik
Keyword(s):  
Density Gradient ◽  
Mkdv Equation ◽  
Charged Dust ◽  
Unperturbed State ◽  
Pair Plasma ◽  
Electron Positron ◽  
Electrons And Positrons ◽  
Solitary Structures ◽  
Dust Distribution ◽  
Positively Charged

An electron–positron pair plasma having dust impurity and density non-uniformity is studied for its unperturbed state and evolution of solitary structures under the effect of either positively charged or negatively charged dust grains. Zeroth-order equations are solved to examine the unperturbed state of the plasma via unperturbed potential φ0, drift velocities of the electrons and positrons (ve0 and vp0), and plasma (positron) density gradient np0η. It is observed that the dust distribution affects the gradient np0η significantly, which increases very sharply with a small increment in the dust density gradient nd0η. With relation to the solitary structures, a modified form of Korteweg–deVries equation (mKdV equation) is realized in the said plasma, which reveals that a tailing structure is associated with the soliton (sech2 structure). This tail is less prominent in the present pair plasma, contrary to the observation made in ordinary plasmas having only ions and electrons. The dust impurity is found to influence the solitary structure much significantly and its presence suppresses the rarefactive solitons, which are generally observed in multi-component species plasmas.

scholarly journals Structure impact of two galactomannan fractions on their viscosity properties in dilute solution, unperturbed state and gel state

2017 ◽  
Vol 96 ◽  
pp. 550-559 ◽  
Author(s):  
Sébastien Gillet ◽  
Mario Aguedo ◽  
Raul Petrut ◽  
Gilles Olive ◽  
Paul Anastas ◽  
...  
Keyword(s):  
Dilute Solution ◽  
Unperturbed State

scholarly journals Disulfide reduction allosterically destabilizes the β-ladder sub-domain assembly within the NS1 dimer of ZIKV

2020 ◽  
Author(s):  
P Roy ◽  
S Roy ◽  
N Sengupta
Keyword(s):  
Disulfide Bonds ◽  
Viral Pathogenesis ◽  
Interfacial Region ◽  
High Symmetry ◽  
Ns1 Protein ◽  
Unperturbed State ◽  
Dynamical Heterogeneity ◽  
Drug Molecules ◽  
Model Free ◽  
Protein Dimer

AbstractThe Zika virus (ZIKV) was responsible for a recent debilitating epidemic that till date has no cure. A potential way to reduce ZIKV virulence is to limit the action of the non-structural proteins involved in its viral replication. One such protein, NS1, encoded as a monomer by the viral genome, plays a major role via symmetric oligomerization. We examine the homodimeric structure of the dominant β-ladder segment of NS1 with extensive all atom molecular dynamics. We find it stably bounded by two spatially separated interaction clusters (C1 and C2) with significant differences in the nature of their interactions. Four pairs of distal, intra-monomeric disulfide bonds are found to be coupled to the stability, local structure, and wettability of the interfacial region. Symmetric reduction of the intra-monomeric disulfides triggers marked dynamical heterogeneity, interfacial wettability and asymmetric salt bridging propensity. Harnessing the model-free Lipari-Szabo based formalism for estimation of conformational entropy (Sconf), we find clear signatures of heterogeneity in the monomeric conformational entropies. The observed asymmetry, very small in the unperturbed state, expands significantly in the reduced states. This allosteric effect is most noticeable in the electrostatically bound C2 cluster that underlies the greatest stability in the unperturbed state. Allosteric induction of conformational and thermodynamic asymmetry is expected to affect the pathways leading to symmetric higher ordered oligomerization, and thereby affect crucial replication pathways.Statement of significanceControlling viral pathogenesis remains a challenge in the face of modern-day epidemics. Though cumbersome and fraught with misleads, most therapeutic endeavors lean towards the design of drug molecules targeting specific proteins involved in viral pathogenesis. This work demonstrates an alternative approach, namely the usage of allosteric intervention to disrupt the binding integrity of the primary domain of the non-structural NS1 protein dimer crucially important in ZIKV virulence. The intervention, triggered by symmetric reduction of the internal monomeric disulfide bonds, results in weakening and distortion of the distal binding interfaces. It further introduces marked structural and entropic asymmetry within the homooligomeric unit, precluding the formation of higher ordered oligomers of high symmetry. The results have important ramifications for consolidated efforts at limiting ZIKV virulence.

Conformational Analysis of Model Poly(ether urethane) Chains in the Unperturbed State and under External Forces

2002 ◽  
Vol 35 (26) ◽  
pp. 9825-9831 ◽  
Author(s):  
İskender Yılgör ◽  
Ersin Yurtsever ◽  
Burak Erman
Keyword(s):  
Conformational Analysis ◽  
Unperturbed State ◽  
External Forces

scholarly journals ULF hydromagnetic oscillations with the discrete spectrum as eigenmodes of MHD-resonator in the near-Earth part of the plasma sheet

2006 ◽  
Vol 24 (6) ◽  
pp. 1639-1648 ◽  
Author(s):  
V. A. Mazur ◽  
A. S. Leonovich
Keyword(s):  
Discrete Spectrum ◽  
Plasma Sheet ◽  
Good Accuracy ◽  
Turning Points ◽  
Unperturbed State ◽  
Parabolic Geometry ◽  
The Stability ◽  
Oscillation Frequencies ◽  
The Waves ◽  
Eigenfrequency Spectrum

Abstract. A new concept is proposed for the emergence of ULF geomagnetic oscillations with a discrete spectrum of frequencies (0.8, 1.3, 1.9, 2.6 ...mHz) registered in the magnetosphere's midnight-morning sector. The concept relies on the assumption that these oscillations are MHD-resonator eigenmodes in the near-Earth plasma sheet. This magnetospheric area is where conditions are met for fast magnetosonic waves to be confined. The confinement is a result of the velocity values of fast magnetosonic waves in the near-Earth plasma sheet which differ greatly from those in the magnetotail lobes, leading to turning points forming in the tailward direction for the waves under study. To compute the eigenfrequency spectrum of such a resonator, we used a model magnetosphere with parabolic geometry. The fundamental harmonics of this resonator's eigenfrequencies are shown to be capable of being clustered into groups with average frequencies matching, with good accuracy, the frequencies of the observed oscillations. A possible explanation for the stability of the observed oscillation frequencies is that such a resonator might only form when the magnetosphere is in a certain unperturbed state.

scholarly journals The quantum theory of atomic polarization II— The van der Waals energy of two atoms

1937 ◽  
Vol 160 (900) ◽  
pp. 113-126 ◽  
Keyword(s):  
Wave Function ◽  
Quantum Theory ◽  
Electric Field ◽  
Large Distance ◽  
Van Der Waals ◽  
Uniform Electric Field ◽  
Unperturbed System ◽  
Unperturbed State ◽  
Atomic Polarization ◽  
Energy Of Interaction

In a previous paper (p. 94) (which will be referred to as Paper I), the polarizability of an atom in a uniform electric field was calculated by a method of varying parameters. The same method can equally well be applied to find the energy of interaction of two atoms a large distance apart, by treating their interaction as a perturbation of the system in which the atoms are separated by an infinite distance. The mutual energy, other than that arising from the ionic charges, if they exist, of the atoms, is usually called the van der Waals energy. We shall suppose that one atom contains N 1 electrons, and is represented in its unperturbed state by a determinantal wave function Ψ 1 (as in equation (3·1) of Paper I), containing electronic functions of the type Ψ p 1 p 3 where p 1 may be any one of the N 1 occupied states α 1 , β 1 , ..., v 1 of this atom, and p denotes that the spatial and spin co-ordinates of the p th electron are inserted in Ψ P1P > Similarly the second atom contains N 2 electrons, and is represented in its unperturbed state by a determinant Ψ 2, containing functions Ψ p 2 r , where p 2 may be one of the N 2 occupied states α 2 , β 2 ,..., V 2 , and r refers to the co-ordinates of the r th electron. Then if we neglect any exchange of electrons between the atoms, the wave function of the unperturbed system of two atoms is Ψ = Ψ 1 Ψ 2 f Ψ * Ψ dr = N 1 ! N 2 !, where the integration is taken over the co-ordinate-space of all N 1 electrons of atom 1 and all N 2 electrons of atom 2.

Sign in / Sign up

Export Citation Format

Share Document