Linking Bond Theory to Drift Theory

2019 ◽  
pp. 45-63
Author(s):  
Alfonso Serrano-Maillo
Keyword(s):  
Drift Theory ◽  
Bond Theory

scholarly journals An Antigenic Thrift-Based Approach to Influenza Vaccine Design

Vaccines ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 657
Author(s):  
Jai S. Bolton ◽  
Hannah Klim ◽  
Judith Wellens ◽  
Matthew Edmans ◽  
Uri Obolski ◽  
...  
Keyword(s):  
Influenza Vaccine ◽  
Influenza Season ◽  
Vaccine Design ◽  
Antigenic Drift ◽  
Influenza Vaccines ◽  
Immune Protection ◽  
Immune Selection ◽  
Drift Theory ◽  
Gradual Accumulation ◽  
Additional Constraints

The antigenic drift theory states that influenza evolves via the gradual accumulation of mutations, decreasing a host’s immune protection against previous strains. Influenza vaccines are designed accordingly, under the premise of antigenic drift. However, a paradox exists at the centre of influenza research. If influenza evolved primarily through mutation in multiple epitopes, multiple influenza strains should co-circulate. Such a multitude of strains would render influenza vaccines quickly inefficacious. Instead, a single or limited number of strains dominate circulation each influenza season. Unless additional constraints are placed on the evolution of influenza, antigenic drift does not adequately explain these observations. Here, we explore the constraints placed on antigenic drift and a competing theory of influenza evolution – antigenic thrift. In contrast to antigenic drift, antigenic thrift states that immune selection targets epitopes of limited variability, which constrain the variability of the virus. We explain the implications of antigenic drift and antigenic thrift and explore their current and potential uses in the context of influenza vaccine design.

scholarly journals The electronic structure of carbones revealed: insights from valence bond theory

2021 ◽  
Vol 23 (5) ◽  
pp. 3327-3334
Author(s):  
Remco W. A. Havenith ◽  
Ana V. Cunha ◽  
Johannes E. M. N. Klein ◽  
Francesca Perolari ◽  
Xintao Feng
Keyword(s):  
Electronic Structure ◽  
Valence Bond ◽  
Carbon Suboxide ◽  
Valence Bond Theory ◽  
Bond Theory

Valence bond theory reveals the nature of the OC–C bond in carbon suboxide and related allene compounds.

The valence-bond theory of molecular structure II. Reformulation of the theory

1954 ◽  
Vol 223 (1154) ◽  
pp. 306-323 ◽  
Keyword(s):  
Valence Bond ◽  
Closed Shell ◽  
Numerical Illustration ◽  
Atomic Orbitals ◽  
Spin Eigenfunctions ◽  
Spin Pairing ◽  
Vb Structures ◽  
Bond Theory ◽  
Strong Repulsion ◽  
A Charge

The construction of spin eigenfunctions and the evaluation of matrix elements between ,them are discussed generally in preparation for a development of the valence bond (VB) theory along the lines indicated in I. The customary approximation of considering explicitly only the electrons outside a ‘closed shell’ is shown to be defensible. The reformulation of the VB theory is now straightforward, but its final description of bonding is quite new. Atomic orbitals (AO’s) are replaced, whenever they appear, by orthogonalized atomic orbitals (AO’s); but when the assumptions of the conventional theory are rigorously validated in this way the ‘covalent’ structures (now ‘VB’ structures) are found, quite generally, to indicate only strong repulsion between the ‘bonded’ atoms, and formal descriptions of bonding and of bond orders, in terms of ‘spin-pairing’, become nonsensical. Bonding can be described only by admitting into the wave functions polar VB structures; a bond between two atoms demands the appearance (with considerable weight) of pairs of structures differing by a ‘charge hop’ between the atoms concerned. The conventional VB structures are found to be equivalent to certain groupings of VB structures (non-polar and polar) and do, indeed, predict bonds between spin-paired atoms and repulsion between the atoms of different pairs. It is then possible to make full use of chemical intuition, using a plausible combination of conventional structures as a starting approximation in the more rigorous theory. A numerical illustration is provided by a discussion of the Kekulé structures of benzene. Some important characteristics of energy calculations in the VB theory are pointed out. Quantities of intra - and inter -atomic origin are well separated, and the method is apparently well suited to development along either ab initio or empirical lines.

Schr�dinger equation in the drift theory of cold plasma

1995 ◽  
Vol 38 (11) ◽  
pp. 737-745
Author(s):  
S. P. Efimov
Keyword(s):  
Cold Plasma ◽  
Dinger Equation ◽  
Drift Theory

The “Double Drift” Theory of Star Motions

Nature ◽  
1907 ◽  
Vol 76 (1969) ◽  
pp. 293-294
Author(s):  
A. S. EDDINGTON
Keyword(s):  
Drift Theory

Resonating–valence-bond theory of phase transitions and superconductivity inLa2CuO4-based compounds

1987 ◽  
Vol 58 (26) ◽  
pp. 2790-2793 ◽  
Author(s):  
P. W. Anderson ◽  
G. Baskaran ◽  
Z. Zou ◽  
T. Hsu
Keyword(s):  
Phase Transitions ◽  
Valence Bond ◽  
Valence Bond Theory ◽  
Resonating Valence Bond ◽  
Bond Theory
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