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1622. Algae cells with deletion of the segment D210-R226 in γ subunit from chloroplast ATP synthase have lower transmembrane proton gradient and grow slowly

Creator:
Ponomarenko, S.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Chlamydomonas, deletion mutant, and proteins
Language:
Multiple languages
Description:
The γ-subunits of chloroplast ATP synthases are about 30 amino acids longer than the bacterial or mitochondrial homologous proteins. This additional sequence is located in the mean part of the polypeptide chain and includes in green algae and higher plants two cysteines (Cys198 and Cys204 in Chlamydomonas reinhardtii) responsible for thiol regulation. In order to investigate its functional significance, a segment ranging from Asp-D210 to Arg-226 in the γ-subunit of chloroplast ATP synthase from C. reinhardtii was deleted. This deletion mutant called T2 grows photoautotrophically, but slowly than the parental strain. The chloroplast ATP synthase complex with the mutated γ is assembled, membrane bound, and as CF0CF1 displays normal ATPase activity, but photophosphorylation is inhibited by about 20 %. This inhibition is referred to lower light-induced transmembrane proton gradient. Reduction of the proton gradient is apparently caused by a disturbed functional connection between CF1 and CF0 effecting a partially leaky ATP synthase complex.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1623. Algebraic approach to locally finite trees with one end

Creator:
Zelinka, Bohdan
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
locally finite tree, one-way infinite path, acyclic monounary algebra, and tree semilattice
Language:
English
Description:
Let T be an infinite locally finite tree. We say that T has exactly one end, if in T any two one-way infinite paths have a common rest (infinite subpath). The paper describes the structure of such trees and tries to formalize it by algebraic means, namely by means of acyclic monounary algebras or tree semilattices. In these algebraic structures the homomorpisms and direct products are considered and investigated with the aim of showing, whether they give algebras with the required properties. At the end some further assertions on the structure of such trees are stated, without the algebraic formalization.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1625. Algebraic connectivity of $k$-connected graphs

Creator:
Kirkland, Steve, Rocha, Israel, and Trevisan, Vilmar
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
algebraic connectivity and Fiedler vector
Language:
English
Description:
Let $G$ be a $k$-connected graph with $k \ge 2$. A hinge is a subset of $k$ vertices whose deletion from $G$ yields a disconnected graph. We consider the algebraic connectivity and Fiedler vectors of such graphs, paying special attention to the signs of the entries in Fiedler vectors corresponding to vertices in a hinge, and to vertices in the connected components at a hinge. The results extend those in Fiedler's papers Algebraic connectivity of graphs (1973), A property of eigenvectors of nonnegative symmetric matrices and its application to graph theory (1975), and Kirkland and Fallat's paper Perron Components and Algebraic Connectivity for Weighted Graphs (1998).
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1627. Algebraic integrability for minimum energy curves

Creator:
Yudin, Ivan and Silva Leite, Fátima
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
Darboux polynomials, drag power, Euler-Lagrange equations, grading, integrability, and vector fields
Language:
English
Description:
This paper deals with integrability issues of the Euler-Lagrange equations associated to a variational problem, where the energy function depends on acceleration and drag. Although the motivation came from applications to path planning of underwater robot manipulators, the approach is rather theoretical and the main difficulties result from the fact that the power needed to push an object through a fluid increases as the cube of its speed.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1628. Algebraic solution to box-constrained bi-criteria problem of rating alternatives through pairwise comparisons

Creator:
Krivulin, Nikolai
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
idempotent semifield, tropical optimization, constrained bi-criteria decision problem, Pareto-optimal solution, box constraints, and pairwise comparisons
Language:
English
Description:
We consider a decision-making problem to evaluate absolute ratings of alternatives that are compared in pairs according to two criteria, subject to box constraints on the ratings. The problem is formulated as the log-Chebyshev approximation of two pairwise comparison matrices by a common consistent matrix (a symmetrically reciprocal matrix of unit rank), to minimize the approximation errors for both matrices simultaneously. We rearrange the approximation problem as a constrained bi-objective optimization problem of finding a vector that determines the approximating consistent matrix, and then represent the problem in terms of tropical algebra. We apply methods and results of tropical optimization to derive an analytical solution of the constrained problem. The solution consists in introducing two new variables that describe the values of the objective functions and allow reducing the problem to the solution of a system of parameterized inequalities constructed for the unknown vector, where the new variables play the role of parameters. We exploit the existence condition for solutions of the system to derive those values of the parameters that belong to the Pareto front inherent to the problem. Then, we solve the system for the unknown vector and take all solutions that correspond to the Pareto front, as a complete solution of the bi-objective problem. We apply the result obtained to the bi-criteria decision problem under consideration and present illustrative examples.
Rights:
http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public

1629. Algebras and spaces of dense constancies

Creator:
Bella, Angelo, Martinez, Jorge, and Woodward, Scott D.
Format:
bez média and svazek
Type:
model:article and TEXT
Subject:
space and algebra of dense constancy and $c$-spectrum
Language:
English
Description:
A DC-space (or space of dense constancies) is a Tychonoff space $X$ such that for each $f\in C(X)$ there is a family of open sets $\lbrace U_i\: i\in I\rbrace $, the union of which is dense in $X$, such that $f$, restricted to each $U_i$, is constant. A number of characterizations of DC-spaces are given, which lead to an algebraic generalization of the concept, which, in turn, permits analysis of DC-spaces in the language of archimedean $f$-algebras. One is led naturally to the notion of an almost DC-space (in which the densely constant functions are dense), and it is shown that all metrizable spaces have this property.
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

1630. Alginate matrices for protein delivery: a short review

Creator:
Wawrzyńska, E and Dana Kubies
Format:
print, bez média, and svazek
Type:
model:article and TEXT
Subject:
algináty, růstové faktory, alginates, growth factors, biomaterials, protein release, growth factor release, 14, and 612
Language:
English
Description:
Growth factors are powerful molecules that regulate cellular growth, proliferation, healing, and cellular differentiation. A delivery matrix that incorporates growth factors with high loading efficiencies, controls their release, and maintains bioactivity would be a powerful tool for regenerative medicine. Alginate has several unique properties that make it an excellent platform for the delivery of proteins. Mild gelling conditions can minimize the risk of protein denaturation; moreover, alginate can serve as protection from degradation until protein release. Various modifications have been proposed to tune alginate binding and release proteins, simultaneously adjusting alginate degradability, mechanical stiffness, swelling, gelation properties and cell affinity. The primary objective of this article is to review the literature related to recent advances in the application of alginate matrices in protein delivery in regenerative medicine. A special emphasis is put on the relevance of delivery of growth factors and chemokine., E. Wawrzyńska, D. Kubies., and Obsahuje bibliografii
Rights:
http://creativecommons.org/publicdomain/mark/1.0/ and policy:public

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