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Results for “CONSERVATION”
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Conserved momenta of a ferromagnetic soliton
Linear and angular momenta of a soliton in a ferromagnet are commonly derived through the application of Noether’s theorem. We show that these quantities exhibit unphysical behavior: they depend on the choice of a gauge potential in the spin Lagrangian and can be made arbitrary. To resolve this problem, we exploit a similarity between the dynamics of a ferromagnetic soliton and that of a charged particle in a magnetic field. For the latter, canonical momentum is also gauge-dependent and thus unphysical; the physical momentum is the generator of magnetic translations, a symmetry combining physical translations with gauge transformations. We use this analogy to unambiguously define conserved momenta for ferromagnetic solitons. General considerations are illustrated on simple models of a domain wall in a ferromagnetic chain and of a vortex in a thin film.
Mechanistic insights into energy conservation by flavin-based electron bifurcation
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The 2.1 Å structure of protein F9 and its comparison to L1, two components of the conserved poxvirus entry-fusion complex
The poxvirus F9 protein is a component of the vaccinia virus entry fusion complex (EFC) which consists of 11 proteins. The EFC forms a unique apparatus among viral fusion proteins and complexes. We solved the atomic structure of the F9 ectodomain at 2.10Å. A structural comparison to the ectodomain of the EFC protein L1 indicated a similar fold and organization, in which a bundle of fve α-helices is packed against two pairs of β-strands. However, instead of the L1 myristoylation site and hydrophobic cavity, F9 possesses a protruding loop between α-helices α3 and α4 starting at Gly90. Gly90 is conserved in all poxviruses except Salmon gill poxvirus (SGPV) and Diachasmimorpha longicaudata entomopoxvirus. Phylogenetic sequence analysis of all Poxviridae F9 and L1 orthologs revealed the SGPV genome to contain the most distantly related F9 and L1 sequences compared to the vaccinia proteins studied here. The structural diferences between F9 and L1 suggest functional adaptations during evolution from a common precursor that underlie the present requirement for each protein.
The structure of human Nocturnin reveals a conserved ribonuclease domain that represses target transcript translation and abundance in cells
Abstract not provided
Conservation laws, vertex corrections, and screening in Raman spectroscopy
We present a microscopic theory for the Raman response of a clean multiband superconductor, with emphasis on the effects of vertex corrections and long-range Coulomb interaction. The measured Raman intensity, R(Ω), is proportional to the imaginary part of the fully renormalized particle-hole correlator with Raman form factors γ( ⃗ k). In a BCS superconductor, a bare Raman bubble is nonzero for any γ( ⃗ k) and diverges at Ω = 2Δ max , where Δ max is the largest gap along the Fermi surface. However, for γ( ⃗ k) = constant, the full R(Ω) is expected to vanish due to particle number conservation. It was sometimes stated that this vanishing is due to the singular screening by long-range Coulomb interaction. In our general approach, we show diagrammatically that this vanishing actually holds due to vertex corrections from the same short-range interaction that gives rise to superconductivity. We further argue that long-range Coulomb interaction does not affect the Raman signal for any γ( ⃗ k). We argue that vertex corrections eliminate the divergence at 2Δ max . Here, we also argue that vertex corrections give rise to sharp peaks in R(Ω) at Ω < 2Δ min (the minimum gap along the Fermi surface), when Ω coincides with the frequency of one of the collective modes in a superconductor, e.g., Leggett and Bardasis-Schrieffer modes in the particle-particle channel, and an excitonic mode in the particle-hole channel.
XYLEM NAC DOMAIN1, an angiosperm NAC transcription factor, inhibits xylem differentiation through conserved motifs that interact with RETINOBLASTOMA‐RELATED
Summary The Arabidopsis thaliana gene XYLEM NAC DOMAIN1 ( XND1 ) is upregulated in xylem tracheary elements. Yet overexpression of XND1 blocks differentiation of tracheary elements. The molecular mechanism of XND1 action was investigated. Phylogenetic and motif analyses indicated that XND1 and its homologs are present only in angiosperms and possess a highly conserved C‐terminal region containing linear motifs (CKII‐acidic, LXCXE, E2F TD ‐like and LXCXE‐mimic) predicted to interact with the cell cycle and differentiation regulator RETINOBLASTOMA‐RELATED (RBR). Protein–protein interaction and functional analyses of XND1 deletion mutants were used to test the importance of RBR‐interaction motifs. Deletion of either the LXCXE or the LXCXE‐mimic motif reduced both the XND1–RBR interaction and XND1 efficacy as a repressor of differentiation, with loss of the LXCXE motif having the strongest negative impacts. The function of the XND1 C‐terminal domain could be partially replaced by RBR fused to the N‐terminal domain of XND1. XND1 also transactivated gene expression in yeast and plants. The properties of XND1, a transactivator that depends on multiple linear RBR‐interaction motifs to inhibit differentiation, have not previously been described for a plant protein. XND1 harbors an apparently angiosperm‐specific combination of interaction motifs potentially linking the general differentiation regulator RBR with a xylem‐specific pathway for inhibition of differentiation.
A highly conserved cryptic epitope in the receptor binding domains of SARS-CoV-2 and SARS-CoV
Abstract not provided
Deep Conservation: A Latent-Dynamics Model for Exact Satisfaction of Physical Conservation Laws [Poster]
Learning a latent-dynamics model for complex real-world physical processes is indispensable. Most previous latent-dynamics modeling approaches suffer from the violation of important physical properties such as conservation.
Truly conserving with conservative remapping methods
Abstract. Conservative mapping of data from one horizontal grid to another should preserve certain integral or mean properties of the original data. This may be essential in some model applications, including ensuring realistic exchange of energy and mass between coupled model components. It can also be essential for certain types of analysis, such as evaluating how far a system is from an equilibrium state. For some common grids, existing remapping algorithms may fail to perfectly represent the shapes and sizes of grid cells, which leads to errors in the remapped fields. A procedure is presented here that enables users to rely on the mapping weights generated by remapping algorithms but corrects for their deficiencies. With this procedure, for a given pair of source and destination grids, a single set of remapping weights can be applied to remap any variable, including those with grid cells that are partially or fully masked.
A brief description of a new numerical framework for solving conservation laws: The method of space-time conservation element and solution element
A new numerical method for solving conservation laws is being developed. It differs substantially from the well established methods, i.e., finite difference, finite volume, finite element, and spectral methods, in both concept and methodology. It is much simpler than a typical high resolution method. No flux limiter or any technique related to characteristics is involved. No artificial viscosity or smoothing is introduced, and no moving mesh is used. Yet this method is capable of generating highly accurate shock tube solutions. The slight numerical overshoot and/or oscillations generated can be removed if a simple averaging formula initially used is replaced by a weighted formula. This modification has little effect on other parts of the solution. Because of its simplicity, generalization of this new method for multi-dimensional problems is straightforward.
Towards a more healthy conservation paradigm: integrating disease and molecular ecology to aid biological conservation†
Not provided.
Conservation of Structure and Immune Antagonist Functions of Filoviral VP35 Homologs Present in Microbat Genomes
Abstract not provided