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1
Yang, Congli. "Inner functions inQKtype spaces." Journal of Function Spaces and Applications 9, no. 3 (2011): 305–22. http://dx.doi.org/10.1155/2011/765101.
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Inner functions inQK(p,q)are studied, providedKsatisfies certain regularity conditions. In particular, it is shown that the only inner functions inQK(p, p-2), p≥1, are precisely the Blaschke products whose zeros{zn}satisfysupa∈D∑K(1-|φa(zn)|2)<∞.
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Bayart, Frédéric. "Universal Inner Functions on the Ball." Canadian Mathematical Bulletin 51, no. 4 (December 1, 2008): 481–86. http://dx.doi.org/10.4153/cmb-2008-048-8.
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AbstractIt is shown that given any sequence of automorphisms (ϕk)k of the unit ball of ℂN such that ‖ϕk(0)‖ tends to 1, there exists an inner function I such that the family of “non-Euclidean translates” (I о ϕk)k is locally uniformly dense in the unit ball of H∞().
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Qian, Ruishen. "Inner functions in QK spaces and multipliers." Mathematica Slovaca 72, no. 3 (June 1, 2022): 623–34. http://dx.doi.org/10.1515/ms-2022-0042.
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Abstract In this paper, under some conditions on weighted function K, we give some new equivalent characterizations of inner functions in Q K spaces. Meanwhile, we also studied inner functions in Q K spaces as multipliers of C 𝓑(Q K ) ∩ BMOA, where C 𝓑(Q K ) denoted the closure of Q K spaces in Bloch spaces.
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Huban, Mualla, Hamdullah Başaran, and Mehmet Gürdal. "Berezin number inequalities via convex functions." Filomat 36, no. 7 (2022): 2333–44. http://dx.doi.org/10.2298/fil2207333h.
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The Berezin symbol ?A of an operator A on the reproducing kernel Hilbert space H (?) over some set ? with the reproducing kernel k? is defined by ? (?) = ?A k?/||k?||, k?/||k?||?, ? ? ?. The Berezin number of an operator A is defined by ber(A) := sup ??? |?(?)|. We study some problems of operator theory by using this bounded function ?, including treatments of inner product inequalities via convex functions for the Berezin numbers of some operators. We also establish some inequalities involving of the Berezin inequalities.
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Shakh-Emirov, Tadgidin. "On uniform convergence of Fourier-Sobolev series." Daghestan Electronic Mathematical Reports, no. 12 (December 5, 2019): 55–61. http://dx.doi.org/10.31029/demr.12.5.
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Let $\{\varphi_{k}\}_{k=0}^\infty$ be a system of functions defined on $ [a, b] $ and orthonormal in $ L ^ 2_ \rho = L ^ 2_\rho ( a, b) $ with respect to the usual inner product. For a given positive integer $ r $, by $\{\varphi_{r,k}\}_{k=0}^\infty$ we denote the system of functions orthonormal with respect to the Sobolev-type inner product and generated by the system $\{\varphi_{k}\}_{k=0}^\infty$. In this paper, we study the question of the uniform convergence of the Fourier series by the system of functions $\{\varphi_{r,k}\}_{k=0}^\infty$ to the functions $f\in W^r_{L^p_\rho}$ in the case when the original system $\{\varphi_{k}\}_{k=0}^\infty$ forms a basis in the space $L^p_\rho=L^p_\rho(a,b)$ ($1\le p$, $p\neq2$).
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Khare, Mona, and Pratibha Pandey. "Outer and inner approximations in quantum spaces." Mathematica Slovaca 71, no. 1 (January 29, 2021): 11–26. http://dx.doi.org/10.1515/ms-2017-0449.
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Abstract The present paper introduces and studies the concepts of K-outer approximation and K-inner approximation for a monotone function μ defined on a D-poset P, by a subfamily K of P. Some desirable properties of K-approximable functions are established and it is shown that the family of all elements of P that possess K-approximation, forms a lattice and is closed under orthosupplementation. We have proved that a submodular measure on a suitable subfamily of P having K-outer approximation can be extended to a function that has K-outer approximation, and a tight function that has K-inner approximation can be extended to a function having K-inner approximation.
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Boudref, Mohamed Ahmed. "Inner product and Gegenbauer polynomials in Sobolev space." Russian Universities Reports. Mathematics, no. 138 (2022): 150–65. http://dx.doi.org/10.20310/2686-9667-2022-27-138-150-163.
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In this paper we consider the system of functions G_(r,n)^α (x) (r∈N,n=0,1,…) which is orthogonal with respect to the Sobolev-type inner product on (-1,1) and generated by orthogonal Gegenbauer polynomials. The main goal of this work is to study some properties related to the system {φ_(k,r) (x)}_(k≥0) of the functions generated by the orthogonal system {G_(r,n)^α (x)} of Gegenbauer functions. We study the conditions on a function f(x) given in a generalized Gegenbauer orthogonal system for it to be expandable into a generalized mixed Fourier series of the form f(x)~∑_(k=0)^(r-1)▒〖f^((k) ) (-1) (x+1)^k/k!+∑_(k=r)^∞▒〖G_(r,k)^α (f) 〗〗 φ_(r,k)^α (x), as well as the convergence of this Fourier series. The second result of this paper is the proof of a recurrence formula for the system {φ_(k,r) (x)}_(k≥0). We also discuss the asymptotic properties of these functions, and this represents the latter result of our contribution.
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Saito, Hiroshi. "On L-functions associated with the vector space of binary quadratic forms." Nagoya Mathematical Journal 130 (June 1993): 149–76. http://dx.doi.org/10.1017/s0027763000004475.
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The purpose of this paper is to prove functional equations of L-functions associated with the vector space of binary quadratic forms and determine their poles and residues. For a commutative ring K, let V(K) be the set of all symmetric matrices of degree 2 with coefficients in K. In V(C), we consider the inner productwhere for .
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Yang, Liu. "Inner functions as multipliers and zero sets in weighted Dirichlet spaces." Georgian Mathematical Journal 27, no. 4 (December 1, 2020): 655–60. http://dx.doi.org/10.1515/gmj-2018-0064.
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DMITRIEV, ANDREY V., NINA A. DMITRIEVA, KENT T. KEYSER, and STUART C. MANGEL. "Multiple functions of cation-chloride cotransporters in the fish retina." Visual Neuroscience 24, no. 4 (July 2007): 635–45. http://dx.doi.org/10.1017/s0952523807070629.
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A GABA- or glycine-induced increase in Cl− permeability can produce either a depolarization or hyperpolarization, depending on the Cl− equilibrium potential. It has been shown that retinal neurons express the chloride cotransporters, Na-K-2Cl (NKCC) and K-Cl (KCC), the primary molecular mechanisms that control the intracellular Cl− concentration. We thus studied (1) the localization of these cotransporters in the fish retina, and (2) how suppression of cotransporter activity in the fish retina affects function. Specific antibodies against NKCC and KCC2 revealed that both cotransporters were expressed in the outer and inner plexiform layers, and colocalized in many putative amacrine cells and in cells of the ganglion cell layer. However, the somata of putative horizontal cells displayed only NKCC immunoreactivity and many bipolar cells were only immunopositive for KCC2. In the outer retina, application of bumetanide, a specific inhibitor of NKCC activity, (1) increased the steady-state extracellular concentration of K+ ([K+]o) and enhanced the light-induced decrease in the [K+]o, (2) increased the sPIII photoreceptor-dependent component of the ERG, and (3) reduced the extracellular space volume. In contrast, in the outer retina, application of furosemide, a specific inhibitor of KCC activity, decreased sPIII and the light-induced reduction in [K+]o, but had little effect on steady-state [K+]o. In the inner retina, bumetanide increased the sustained component of the light-induced increase in [K+]o. These findings thus indicate that NKCC and KCC2 control the [K+]o and extracellular space volume in the retina in addition to regulating GABA- and glycine-mediated synaptic transmission. In addition, the anatomical and electrophysiological results together suggest that all of the major neuronal types in the fish retina are influenced by chloride cotransporter activity.
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Boudref, Mohamed Ahmed. "Hermite functions and inner product in Sobolev space." Russian Universities Reports. Mathematics, no. 142 (2023): 155–68. http://dx.doi.org/10.20310/2686-9667-2023-28-142-155-168.
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Let us consider the orthogonal Hermite system 〖{φ_2n (x)}〗_(n≥0) of even index defined on (-∞,∞), where φ_2n (x)=e^(-x^2/2)/(√((2n)!) π^(1/4) 2^n ) H_2n (x), by H_2n (x) we denote a Hermite polynomial of degree 2n. In this paper, we consider a generalized system {ψ_(r,2n) (x)} with r>0, n≥0 which is orthogonal with respect to the Sobolev type inner product on (-∞,∞), i.e. 〈f,g〉=lim┬(t→-∞)∑_(k=0)^(r-1)▒〖f^((k) ) (t) g^((k) ) (t)+∫_(-∞)^∞▒〖f^((r) ) (x) g^((r) ) (x)ρ(x)dx〗〗 with ρ(x)=e^(-x^2 ), and generated by 〖{φ_2n (x)}〗_(n≥0). The main goal of this work is to study some properties related to the system 〖{ψ_(r,2n) (x)}〗_(n≥0), ψ_(r,n) (x)=〖(x-a)〗^n/n!,n=0,1,2,…,r-1, ψ_(r,r+n) (x)=1/(r-1)! ∫_a^b▒〖(x-t)^(r-1) φ_n (t)dt,〗 n=0,1,2,… . We study the conditions on a function f(x), given in a generalized Hermite orthogonal system, for it to be expandable into a generalized mixed Fourier series as well as the convergence of this Fourier series. The second result of the paper is the proof of a recurrent formula for the system 〖{ψ_(r,2n) (x)}〗_(n≥0). We also discuss the asymptotic properties of these functions, and this concludes our contribution.
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Lance, T. L., and M. I. Stessin. "Multiplication Invariant Subspaces of Hardy Spaces." Canadian Journal of Mathematics 49, no. 1 (February 1, 1997): 100–118. http://dx.doi.org/10.4153/cjm-1997-005-9.
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AbstractThis paper studies closed subspaces L of the Hardy spaces Hp which are g-invariant (i.e., g. L ⊆ L) where g is inner, g ≠ 1. If p = 2, theWold decomposition theorem implies that there is a countable “g-basis” f1, f2, . . . of L in the sense that L is a direct sum of spaces fj . H2[g] where H2[g] = {f o g | f ∈ H2}. The basis elements fj satisfy the additional property that ∫T |fj|2gk = 0, k = 1, 2, . . . . We call such functions g-2-inner. It also follows that any f ∈ H2 can be factored f = hf ,2 . (F2 o g) where hf,2 is g-2-inner and F is outer, generalizing the classical Riesz factorization. Using Lp estimates for the canonical decomposition of H2,we find a factorization f = hf ,p.(Fpog) for f ∈ Hp. If p ≤ 1 and g is a finite Blaschke product we obtain, for any g-invariant L ⊆ Hp, a finite g-basis of g-p-inner functions.
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Shi, Y. Y., and Y. F. Zhu. "Quantum communication complexity of block-composed functions." Quantum Information and Computation 9, no. 5&6 (May 2009): 444–60. http://dx.doi.org/10.26421/qic9.5-6-7.
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A major open problem in communication complexity is whether or not quantum protocols can be exponentially more efficient than classical ones for computing a {\em total} Boolean function in the two-party interactive model. Razborov's result ({\em Izvestiya: Mathematics}, 67(1):145--159, 2002) implies the conjectured negative answer for functions $F$ of the following form: $F(x, y)=f_n(x_1\cdot y_1, x_2\cdot y_2, ..., x_n\cdot y_n)$, where $f_n$ is a {\em symmetric} Boolean function on $n$ Boolean inputs, and $x_i$, $y_i$ are the $i$'th bit of $x$ and $y$, respectively. His proof critically depends on the symmetry of $f_n$. We develop a lower-bound method that does not require symmetry and prove the conjecture for a broader class of functions. Each of those functions $F$ is the ``block-composition'' of a ``building block'' $g_k : \{0, 1\}^k \times \{0, 1\}^k \rightarrow \{0, 1\}$, and an $f_n : \{0, 1\}^n \rightarrow \{0, 1\}$, such that $F(x, y) = f_n( g_k(x_1, y_1), g_k(x_2, y_2), ..., g_k(x_n, y_n) )$, where $x_i$ and $y_i$ are the $i$'th $k$-bit block of $x, y\in\{0, 1\}^{nk}$, respectively. We show that as long as g_k itself is "hard'' enough, its block-composition with an arbitrary f_n has polynomially related quantum and classical communication complexities. For example, when g_k is the Inner Product function with k=\Omega(\log n), the deterministic communication complexity of its block-composition with any f_n is asymptotically at most the quantum complexity to the power of 7.
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Pihakaski-Maunsbach, Kaarina, Henrik Vorum, Bent Honoré, Shigeki Tokonabe, Jørgen Frøkiær, Haim Garty, Steven J. D. Karlish, and Arvid B. Maunsbach. "Locations, abundances, and possible functions of FXYD ion transport regulators in rat renal medulla." American Journal of Physiology-Renal Physiology 291, no. 5 (November 2006): F1033—F1044. http://dx.doi.org/10.1152/ajprenal.00086.2006.
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The γ-subunit of Na-K-ATPase (FXYD2) and corticosteroid hormone-induced factor (CHIF; FXYD4) are considered pump regulators in kidney tubules. The aim of this study was to expand the information about their locations in the kidney medulla and to evaluate their importance for electrolyte excretion in an animal model. The cellular and subcellular locations and abundances of γ and CHIF in the medulla of control and sodium-depleted rats were analyzed by immunofluorescence and immunoelectron microscopy and semiquantitative Western blotting. The results showed that antibodies against the γ-subunit COOH terminus and splice variant γa, but not splice variant γb, labeled intercalated cells, but not principal cells, in the initial part of the inner medullary collecting duct (IMCD1). In subsequent segments (IMCD2 and IMCD3), all principal cells exhibited distinct basolateral labeling for both the γ-subunit COOH terminus, splice variant γa, and CHIF. Splice variant γb was abundant in the inner stripe of the outer medulla but absent in the inner medulla (IM). Double labeling by high-resolution immunoelectron microscopy showed close structural association between CHIF and the Na-K-ATPase α1-subunit in basolateral membranes. The present observations provide new information about the cellular and subcellular locations of γ and CHIF in the renal medulla and show a new γ variant in the IM. Extensive NaCl depletion did not induce significant changes in the locations or abundances of the γ-subunit COOH terminus and CHIF in different kidney zones. We conclude that the unchanged levels of these two FXYD proteins suggest that they are not primary determinants for urine electrolyte composition during NaCl depletion.
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Bandura, A. I., O. B. Skaskiv, and T. M. Salo. "Note on composition of entire functions and bounded $L$-index in direction." Matematychni Studii 55, no. 1 (March 4, 2021): 51–56. http://dx.doi.org/10.30970/ms.55.1.51-56.
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We study the following question: ``Let $f\colon \mathbb{C}\to \mathbb{C}$ be an entire function of bounded $l$-index, $\Phi\colon \mathbb{C}^n\to \mathbb{C}$ an be entire function, $n\geq2,$ $l\colon \mathbb{C}\to \mathbb{R}_+$ be a continuous function. What is a positive continuous function $L\colon \mathbb{C}^n\to \mathbb{R}_+$ and a direction $\mathbf{b}\in\mathbb{C}^n\setminus\{\mathbf{0}\}$ such that the composite function $f(\Phi(z))$ has bounded $L$-index in the direction~$\mathbf{b}$?'' In the present paper, early known result on boundedness of $L$-index in direction for the composition of entire functions $f(\Phi(z))$ is modified. We replace a condition that a directional derivative of the inner function $\Phi$ in a direction $\mathbf{b}$ does not equal zero. The condition is replaced by a construction of greater function $L(z)$ for which $f(\Phi(z))$ has bounded $L$-index in a direction. We relax the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K|\partial_{\mathbf{b}}\Phi(z)|^k$ for all $z\in\mathbb{C}^n$,where $K\geq 1$ is a constant and ${\partial_{\mathbf{b}} F(z)}:=\sum\limits_{j=1}^{n}\!\frac{\partial F(z)}{\partial z_{j}}{b_{j}}, $ $\partial_{\mathbf{b}}^k F(z):=\partial_{\mathbf{b}}\big(\partial_{\mathbf{b}}^{k-1} F(z)\big).$ It is replaced by the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K(l(\Phi(z)))^{1/(N(f,l)+1)}|\partial_{\mathbf{b}}\Phi(z)|^k,$ where $N(f,l)$ is the $l$-index of the function $f.$The described result is an improvement of previous one.
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BAO, GUANLONG, JAVAD MASHREGHI, STAMATIS POULIASIS, and HASI WULAN. "MÖBIUS INVARIANT FUNCTION SPACES AND DIRICHLET SPACES WITH SUPERHARMONIC WEIGHTS." Journal of the Australian Mathematical Society 106, no. 1 (July 12, 2018): 1–18. http://dx.doi.org/10.1017/s1446788718000022.
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Let ${\mathcal{D}}_{\unicode[STIX]{x1D707}}$ be Dirichlet spaces with superharmonic weights induced by positive Borel measures $\unicode[STIX]{x1D707}$ on the open unit disk. Denote by $M({\mathcal{D}}_{\unicode[STIX]{x1D707}})$ Möbius invariant function spaces generated by ${\mathcal{D}}_{\unicode[STIX]{x1D707}}$. In this paper, we investigate the relation among ${\mathcal{D}}_{\unicode[STIX]{x1D707}}$, $M({\mathcal{D}}_{\unicode[STIX]{x1D707}})$ and some Möbius invariant function spaces, such as the space $BMOA$ of analytic functions on the open unit disk with boundary values of bounded mean oscillation and the Dirichlet space. Applying the relation between $BMOA$ and $M({\mathcal{D}}_{\unicode[STIX]{x1D707}})$, under the assumption that the weight function $K$ is concave, we characterize the function $K$ such that ${\mathcal{Q}}_{K}=BMOA$. We also describe inner functions in $M({\mathcal{D}}_{\unicode[STIX]{x1D707}})$ spaces.
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Gohma, Hiroshi, Takashi Kuramoto, Mitsuru Kuwamura, Ryoko Okajima, Noriaki Tanimoto, Ken-ichi Yamasaki, Satoshi Nakanishi, et al. "WTC deafness Kyoto (dfk): a rat model for extensive investigations of Kcnq1 functions." Physiological Genomics 24, no. 3 (March 2006): 198–206. http://dx.doi.org/10.1152/physiolgenomics.00221.2005.
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KCNQ1 forms K+ channels by assembly with regulatory subunit KCNE proteins and plays a key role in the K+ homeostasis in a variety of tissues. In the heart, KCNQ1 is coassembled with KCNE1 to produce a cardiac delayed rectifier K+ current. In the inner ear, the KCNQ1/KCNE1 complex maintains the high concentration of K+ in the endolymph. In the stomach, KCNQ1 is coassembled with KCNE2 to form the K+ exflux channel that is essential for gastric acid secretion. In the colon and small intestine, KCNQ1 is coassembled with KCNE3 to play an important role in transepithelial cAMP-stimulated Cl− secretion. For further understanding of Kcnq1 function in vivo, an animal model has been required. Here we reported the identification of a coisogenic Kcnq1 mutant rat, named deafness Kyoto ( dfk), and the characterization of its phenotypes. WTC- dfk rats carried intragenic deletion at the Kcnq1 gene and showed impaired gain of weight, deafness, and imbalance resulting from the marked reduction of endolymph, prolonged QT interval in the electrocardiogram (ECG), and gastric achlorhydria associated with hypertrophic gastric mucosa. Surprisingly, WTC- dfk rats showed hypertension, which suggested that Kcnq1 might be involved in the regulation of blood pressure. These findings suggest that WTC- dfk rats could represent a powerful tool for studying the physiological functions of KCNQ1 and for the establishment of new therapeutic procedures for Kcnq1-related diseases.
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Bandura, A. I., O. B. Skaskiv, and I. R. Tymkiv. "Composition of entire and analytic functions in the unit ball." Carpathian Mathematical Publications 14, no. 1 (June 9, 2022): 95–104. http://dx.doi.org/10.15330/cmp.14.1.95-104.
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In this paper, we investigate a composition of entire function of several complex variables and analytic function in the unit ball. We modified early known results with conditions providing equivalence of boundedness of $L$-index in a direction for such a composition and boundedness of $l$-index of initial function of one variable, where the continuous function $L:\mathbb{B}^n\to \mathbb{R}_+$ is constructed by the continuous function $l: \mathbb{C}^m\to \mathbb{R}_+.$ Taking into account new ideas from recent results on composition of entire functions, we remove a condition that a directional derivative of the inner function $\Phi$ in the composition does not equal to zero. Instead of the condition we construct a greater function $L(z)$ for which $F(z)=f(\underbrace{\Phi(z),\ldots,\Phi(z)}_{m\text{ times}})$ has bounded $L$-index in a direction, where $f\colon \mathbb{C}^m\to \mathbb{C}$ is an entire function of bounded $l$-index in the direction $(1,\ldots,1)$, $\Phi\colon \mathbb{B}^n\to \mathbb{C}$ is an analytic function in the unit ball.
We weaken the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K|\partial_{\mathbf{b}}\Phi(z)|^k$ for all $z\in\mathbb{B}^n$, where $K\geq 1$ is a constant, $\mathbf{b}\in\mathbb{C}^n\setminus\{0\}$ is a given direction and $${\partial_{\mathbf{b}} F(z)}:=\sum\limits_{j=1}^{n}\!\frac{\partial F(z)}{\partial z_{j}}{b_{j}}, \ \partial_{\mathbf{b}}^k F(z):=\partial_{\mathbf{b}}\big(\partial_{\mathbf{b}}^{k-1} F(z)\big).$$ It is replaced by the condition $|\partial_{\mathbf{b}}^k\Phi(z)|\le K(l(\Phi(z)))^{1/(N_{\mathbf{1}}(f,l)+1)}|\partial_{\mathbf{b}}\Phi(z)|^k$, where $N_{\mathbf{1}}(f,l)$ is the $l$-index of the function $f$ in the direction $\mathbf{1}=(1,\ldots,1).$ The described result is an improvement of previous one. It is also a new result for the one-dimensional case $n=1,$ $m=1$, i.e. for an analytic function $\Phi$ in the unit disc and for an entire function $f: \mathbb{C}\to\mathbb{C}$ of bounded $l$-index.
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Kohan, D. E., and F. T. Fiedorek. "Endothelin synthesis by rat inner medullary collecting duct cells." Journal of the American Society of Nephrology 2, no. 2 (August 1991): 150–55. http://dx.doi.org/10.1681/asn.v22150.
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Endothelin has been shown to affect a broad range of renal functions, including rat inner medullary collecting duct Na/K ATPase activity, renin release, renal blood flow, and glomerular filtration rate. The source of endothelin in the kidney has been assumed to be endothelial cells. However, the inner medulla contains the highest concentration of immunoreactive endothelin in the kidney. Additionally, MDCK cells, a distal tubule-like cell line, synthesize endothelin. In order to determine if primary renal tubule cells release endothelin, supernatants collected from rat inner medullary collecting duct cells in culture were tested for endothelin-1 detected by specific radioimmunoassay. Inner medullary collecting duct cells produced endothelin-1 in a time-dependent manner, releasing 1,016.7 +/- 60.1 pg of endothelin-1 per mg/cell protein/24 h. Inner medullary collecting duct cells expressed a 2.2-kilobase mRNA on blot hybridization with rat prepro endothelin-1 cDNA. Vasopressin, thrombin, bradykinin, and epinephrine did not affect endothelin-1 release. These data demonstrate endothelin-1 production by inner medullary collecting duct cells and suggest a possible autocrine role for the peptide.
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Archbold, Robert J., and Douglas W. B. Somerset. "The Inner Corona Algebra of a C0(X)-Algebra." Proceedings of the Edinburgh Mathematical Society 60, no. 2 (September 19, 2016): 299–318. http://dx.doi.org/10.1017/s0013091516000171.
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AbstractLet A = C(X) ⊗ K(H), where X is a compact Hausdorff space and K(H) is the algebra of compact operators on a separable infinite-dimensional Hilbert space. Let As be the algebra of strong*-continuous functions from X to K(H). Then As/A is the inner corona algebra of A. We show that if X has no isolated points, then As/A is an essential ideal of the corona algebra of A, and Prim(As/A), the primitive ideal space of As/A, is not weakly Lindelof. If X is also first countable, then there is a natural injection from the power set of X to the lattice of closed ideals of As/A. If X = βℕ\ℕ and the continuum hypothesis (CH) is assumed, then the corona algebra of A is a proper subalgebra of the multiplier algebra of As/A. Several of the results are obtained in the more general setting of C0(X)-algebras.
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Sepúlveda, Francisco V., L. Pablo Cid, Jacques Teulon, and María Isabel Niemeyer. "Molecular Aspects of Structure, Gating, and Physiology of pH-Sensitive Background K2P and Kir K+-Transport Channels." Physiological Reviews 95, no. 1 (January 2015): 179–217. http://dx.doi.org/10.1152/physrev.00016.2014.
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K+ channels fulfill roles spanning from the control of excitability to the regulation of transepithelial transport. Here we review two groups of K+ channels, pH-regulated K2P channels and the transport group of Kir channels. After considering advances in the molecular aspects of their gating based on structural and functional studies, we examine their participation in certain chosen physiological and pathophysiological scenarios. Crystal structures of K2P and Kir channels reveal rather unique features with important consequences for the gating mechanisms. Important tasks of these channels are discussed in kidney physiology and disease, K+ homeostasis in the brain by Kir channel-equipped glia, and central functions in the hearing mechanism in the inner ear and in acid secretion by parietal cells in the stomach. K2P channels fulfill a crucial part in central chemoreception probably by virtue of their pH sensitivity and are central to adrenal secretion of aldosterone. Finally, some unorthodox behaviors of the selectivity filters of K2P channels might explain their normal and pathological functions. Although a great deal has been learned about structure, molecular details of gating, and physiological functions of K2P and Kir K+-transport channels, this has been only scratching at the surface. More molecular and animal studies are clearly needed to deepen our knowledge.
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Chen, Xiang, Yuwen Huang, Pan Gao, Yuexia Lv, Danna Jia, Kui Sun, Yunqiao Han, et al. "Knockout of mafba Causes Inner-Ear Developmental Defects in Zebrafish via the Impairment of Proliferation and Differentiation of Ionocyte Progenitor Cells." Biomedicines 9, no. 11 (November 16, 2021): 1699. http://dx.doi.org/10.3390/biomedicines9111699.
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Zebrafish is an excellent model for exploring the development of the inner ear. Its inner ear has similar functions to that of humans, specifically in the maintenance of hearing and balance. Mafba is a component of the Maf transcription factor family. It participates in multiple biological processes, but its role in inner-ear development remains poorly understood. In this study, we constructed a mafba knockout (mafba−/−) zebrafish model using CRISPR/Cas9 technology. The mafba−/− mutant inner ear displayed severe impairments, such as enlarged otocysts, smaller or absent otoliths, and insensitivity to sound stimulation. The proliferation of p63+ epidermal stem cells and dlc+ ionocyte progenitors was inhibited in mafba−/− mutants. Moreover, the results showed that mafba deletion induces the apoptosis of differentiated K+-ATPase-rich (NR) cells and H+-ATPase-rich (HR) cells. The activation of p53 apoptosis and G0/G1 cell cycle arrest resulted from DNA damage in the inner-ear region, providing a mechanism to account for the inner ear deficiencies. The loss of homeostasis resulting from disorders of ionocyte progenitors resulted in structural defects in the inner ear and, consequently, loss of hearing. In conclusion, the present study elucidated the function of ionic channel homeostasis and inner-ear development using a zebrafish Mafba model and clarified the possible physiological roles.
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YANG, XIAONAN, and HONG-KUN XU. "Projection algorithms for composite minimization." Carpathian Journal of Mathematics 33, no. 3 (2017): 389–97. http://dx.doi.org/10.37193/cjm.2017.03.14.
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Parallel and cyclic projection algorithms are proposed for minimizing the sum of a finite family of convex functions over the intersection of a finite family of closed convex subsets of a Hilbert space. These algorithms consist of two steps. Once the kth iterate is constructed, an inner circle of gradient descent process is executed through each local function, and then a parallel or cyclic projection process is applied to produce the (k + 1) iterate. These algorithms are proved to converge to an optimal solution of the composite minimization problem under investigation upon assuming boundedness of the gradients at the iterates of the local functions and the stepsizes being chosen appropriately.
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Gorinski, Nataliya, Daniel Wojciechowski, Daria Guseva, Dalia Abdel Galil, Franziska E. Mueller, Alexander Wirth, Stefan Thiemann, et al. "DHHC7-mediated palmitoylation of the accessory protein barttin critically regulates the functions of ClC-K chloride channels." Journal of Biological Chemistry 295, no. 18 (March 17, 2020): 5970–83. http://dx.doi.org/10.1074/jbc.ra119.011049.
Full textAbstract:
Barttin is the accessory subunit of the human ClC-K chloride channels, which are expressed in both the kidney and inner ear. Barttin promotes trafficking of the complex it forms with ClC-K to the plasma membrane and is involved in activating this channel. Barttin undergoes post-translational palmitoylation that is essential for its functions, but the enzyme(s) catalyzing this post-translational modification is unknown. Here, we identified zinc finger DHHC-type containing 7 (DHHC7) protein as an important barttin palmitoyl acyltransferase, whose depletion affected barttin palmitoylation and ClC-K-barttin channel activation. We investigated the functional role of barttin palmitoylation in vivo in Zdhhc7−/− mice. Although palmitoylation of barttin in kidneys of Zdhhc7−/− animals was significantly decreased, it did not pathologically alter kidney structure and functions under physiological conditions. However, when Zdhhc7−/− mice were fed a low-salt diet, they developed hyponatremia and mild metabolic alkalosis, symptoms characteristic of human Bartter syndrome (BS) type IV. Of note, we also observed decreased palmitoylation of the disease-causing R8L barttin variant associated with human BS type IV. Our results indicate that dysregulated DHHC7-mediated barttin palmitoylation appears to play an important role in chloride channel dysfunction in certain BS variants, suggesting that targeting DHHC7 activity may offer a potential therapeutic strategy for reducing hypertension.
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Xu, Rang Shu, Ling Niu, Xin Zhu Weng, Long Xu, and Min Li Bai. "Investigation of Numerical Simulation in Combustion Chamber Predictability." Advanced Materials Research 317-319 (August 2011): 2085–90. http://dx.doi.org/10.4028/www.scientific.net/amr.317-319.2085.
Full textAbstract:
For the purpose of increasing applicability of combustion chamber simulation, computational domain, boundary condition, simplicity of complicated structures, mesh generation and physical parameters are investigated in this paper. An annular combustion chamber of some aero-engine is studied by means of predictive numerical simulation. The computational domain includes diffuser, swirler, inner flame tube, inner ring of combustion chamber and the flow channel of all the holes on the wall of flame tube. The film cooling holes row was simplified into a slit filled with porous media. Realizable k-turbulent model and non-premixed combustion model were adopted. Model of pressure atomization nozzle were calibrated and validated through inner nozzle flow property two-phase flow VOF model and experimental data. Physical parameters are express through polynomial functions. A commercial CFD code was adopted on a high performance computing cluster with parallel algorithm and the solving method are high-order discretization scheme. The velocity, pressure, temperature, fuel spray, density of fuel and productions, etc. are calculated and validated with the experimental data.
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Shumilina, Ekaterina, Stephan M. Huber, and Florian Lang. "Ca2+signaling in the regulation of dendritic cell functions." American Journal of Physiology-Cell Physiology 300, no. 6 (June 2011): C1205—C1214. http://dx.doi.org/10.1152/ajpcell.00039.2011.
Full textAbstract:
Dendritic cells (DCs) are highly versatile antigen-presenting cells critically involved in both innate and adaptive immunity as well as maintenance of self-tolerance. DC function is governed by Ca2+signaling, which directs the DC responses to diverse antigens, including Toll-like receptor ligands, intact bacteria, and microbial toxins. Ca2+-sensitive DC functions include DC activation, maturation, migration, and formation of immunological synapses with T cells. Moreover, alterations of cytosolic Ca2+trigger immune suppression or switch off DC activity. Ca2+signals are generated by the orchestration of Ca2+transport processes across plasma, endoplasmic reticulum, and inner mitochondrial membrane. These processes include active pumping of Ca2+, Ca2+/Na+antiport, and electrodiffusion through Ca2+-permeable channels or uniporters. Ca2+channels in the plasma membrane such as Ca2+release-activated Ca2+or L-type Ca2+channels are tightly regulated by the membrane potential which in turn depends on the activity of voltage-gated K+or Ca2+-activated nonselective cation channels. The rapidly growing knowledge on the function and regulation of these membrane transport proteins provides novel insight into pathophysiological mechanisms underlying dysfunction of the immune system and opens novel therapeutic opportunity to favorably influence the function of the immune system.
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GOODYEAR, MELINDA J., SHEILA G. CREWTHER, and BARBARA M. JUNGHANS. "A role for aquaporin-4 in fluid regulation in the inner retina." Visual Neuroscience 26, no. 2 (March 2009): 159–65. http://dx.doi.org/10.1017/s0952523809090038.
Full textAbstract:
AbstractMany diverse retinal disorders are characterized by retinal edema; yet, little experimental attention has been given to understanding the fundamental mechanisms underlying and contributing to these fluid-based disorders. Water transport in and out of cells is achieved by specialized membrane channels, with most rapid water transport regulated by transmembrane water channels known as aquaporins (AQPs). The predominant AQP in the mammalian retina is AQP4, which is expressed on the Müller glial cells. Müller cells have previously been shown to modulate neuronal activity by modifying the concentrations of ions, neurotransmitters, and other neuroactive substances within the extracellular space between the inner and the outer limiting membrane. In doing so, Müller cells maintain extracellular homeostasis, especially with regard to the spatial buffering of extracellular potassium (K+) via inward rectifying K+ channels (Kir channels). Recent studies of water transport and the spatial buffering of K+ through glial cells have highlighted the involvement of both AQP4 and Kir channels in regulating the extracellular environment in the brain and retina. As both glial functions are associated with neuronal activation, controversy exists in the literature as to whether the relationship is functionally dependent. It is argued in this review that as AQP4 channels are likely to be the conduit for facilitating fluid homeostasis in the inner retina during light activation, AQP4 channels are also likely to play a consequent role in the regulation of ocular volume and growth. Recent research has already shown that the level of AQP4 expression is associated with environmentally driven manipulations of light activity on the retina and the development of myopia.
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Hyndman, Kelly A., Chin-Rang Yang, Hyun Jun Jung, Ezigbobiara N. Umejiego, Chung-Ling Chou, and Mark A. Knepper. "Proteomic determination of the lysine acetylome and phosphoproteome in the rat native inner medullary collecting duct." Physiological Genomics 50, no. 9 (September 1, 2018): 669–79. http://dx.doi.org/10.1152/physiolgenomics.00029.2018.
Full textAbstract:
Phosphorylation and lysine (K)-acetylation are dynamic posttranslational modifications of proteins. Previous proteomic studies have identified over 170,000 phosphorylation sites and 15,000 K-acetylation sites in mammals. We recently reported that the inner medullary collecting duct (IMCD), which functions in the regulation of water-reabsorption, via the actions of vasopressin, expresses many of the enzymes that can modulated K-acetylation. The purpose of this study was to determine the K-acetylated or phosphorylated proteins expressed in IMCD cells. Second we questioned whether vasopressin V2 receptor activation significantly affects the IMCD acetylome or phosphoproteome? K-acetylated or serine-, threonine-, or tyrosine-phosphorylated peptides were identified from native rat IMCDs by proteomic analysis with four different enzymes (trypsin, chymotrypsin, ASP-N, or Glu-C) to generate a high-resolution proteome. K-acetylation was identified in 431 unique proteins, and 64% of the K-acetylated sites were novel. The acetylated proteins were expressed in all compartments of the cell and were enriched in pathways including glycolysis and vasopressin-regulated water reabsorption. In the vasopressin-regulated water reabsorption pathway, eight proteins were acetylated, including the novel identification of the basolateral water channel, AQP3, acetylated at K282; 215 proteins were phosphorylated in this IMCD cohort, including AQP2 peptides that were phosphorylated at four serines: 256, 261, 264, and 269. Acute dDAVP did not significantly affect the IMCD acetylome; however, it did significantly affect previously known vasopressin-regulated phosphorylation sites. In conclusion, presence of K-acetylated proteins involved in metabolism, ion, and water transport in the IMCD points to multiple roles of K-acetylation beyond its canonical role in transcriptional regulation.
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Tang, Rui, Songjie Xie, and Youlong Wu. "On the Achievable Rate Region of the K-Receiver Broadcast Channels via Exhaustive Message Splitting." Entropy 23, no. 11 (October 26, 2021): 1408. http://dx.doi.org/10.3390/e23111408.
Full textAbstract:
This paper focuses on K-receiver discrete-time memoryless broadcast channels (DM-BCs) with private messages, where the transmitter wishes to convey K private messages to K receivers. A general inner bound on the capacity region is proposed based on an exhaustive message splitting and a K-level modified Marton’s coding. The key idea is to split every message into ∑j=1KKj−1 submessages each corresponding to a set of users who are assigned to recover them, and then send these submessages via codewords chosen from a K-level structure codebooks. To guarantee the joint typicality among all transmitted codewords, a sufficient condition on the subcodebooks’ sizes is derived through a newly establishing hierarchical covering lemma, which extends the 2-level multivariate covering lemma to the K-level case with more intricate dependences. As the number of auxiliary random variables and rate conditions both increase exponentially with K, the standard Fourier–Motzkin elimination procedure becomes infeasible when K is large. To tackle this problem, we obtain a closed form of achievable rate region with a special observation of disjoint unions of sets that constitute the power set of {1,⋯,K}. The proposed achievable rate region allows arbitrary input probability mass functions and improves over previously known achievable (closed form) rate regions for K-receiver (K≥3) BCs.
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Kabanets, Valentine, Sajin Koroth, Zhenjian Lu, Dimitrios Myrisiotis, and Igor C. Oliveira. "Algorithms and Lower Bounds for De Morgan Formulas of Low-Communication Leaf Gates." ACM Transactions on Computation Theory 13, no. 4 (December 31, 2021): 1–37. http://dx.doi.org/10.1145/3470861.
Full textAbstract:
The class FORMULA[s]∘G consists of Boolean functions computable by size- s De Morgan formulas whose leaves are any Boolean functions from a class G. We give lower bounds and (SAT, Learning, and pseudorandom generators ( PRG s )) algorithms for FORMULA[n 1.99 ]∘G, for classes G of functions with low communication complexity . Let R (k) G be the maximum k -party number-on-forehead randomized communication complexity of a function in G. Among other results, we show the following: • The Generalized Inner Product function GIP k n cannot be computed in FORMULA[s]° G on more than 1/2+ε fraction of inputs for s=o(n 2 /k⋅4 k ⋅R (k) (G)⋅log(n/ε)⋅log(1/ε)) 2 ). This significantly extends the lower bounds against bipartite formulas obtained by [62]. As a corollary, we get an average-case lower bound for GIP k n against FORMULA[n 1.99 ]∘PTF k −1 , i.e., sub-quadratic-size De Morgan formulas with degree-k-1) PTF ( polynomial threshold function ) gates at the bottom. Previously, it was open whether a super-linear lower bound holds for AND of PTFs. • There is a PRG of seed length n/2+O(s⋅R (2) (G)⋅log(s/ε)⋅log(1/ε)) that ε-fools FORMULA[s]∘G. For the special case of FORMULA[s]∘LTF, i.e., size- s formulas with LTF ( linear threshold function ) gates at the bottom, we get the better seed length O(n 1/2 ⋅s 1/4 ⋅log(n)⋅log(n/ε)). In particular, this provides the first non-trivial PRG (with seed length o(n)) for intersections of n halfspaces in the regime where ε≤1/n, complementing a recent result of [45]. • There exists a randomized 2 n-t #SAT algorithm for FORMULA[s]∘G, where t=Ω(n\√s⋅log 2 (s)⋅R (2) (G))/1/2. In particular, this implies a nontrivial #SAT algorithm for FORMULA[n 1.99 ]∘LTF. • The Minimum Circuit Size Problem is not in FORMULA[n 1.99 ]∘XOR; thereby making progress on hardness magnification, in connection with results from [14, 46]. On the algorithmic side, we show that the concept class FORMULA[n 1.99 ]∘XOR can be PAC-learned in time 2 O(n/log n) .
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Bagchi, Susmit. "Topological Sigma-Semiring Separation and Ordered Measures in Noetherian Hyperconvexes." Symmetry 14, no. 2 (February 20, 2022): 422. http://dx.doi.org/10.3390/sym14020422.
Full textAbstract:
The interplay between topological hyperconvex spaces and sigma-finite measures in such spaces gives rise to a set of analytical observations. This paper introduces the Noetherian class of k-finite k-hyperconvex topological subspaces (NHCs) admitting countable finite covers. A sigma-finite measure is constructed in a sigma-semiring in a NHC under a topological ordering of NHCs. The topological ordering relation maintains the irreflexive and anti-symmetric algebraic properties while retaining the homeomorphism of NHCs. The monotonic measure sequence in a NHC determines the convexity and compactness of topological subspaces. Interestingly, the topological ordering in NHCs in two isomorphic topological spaces induces the corresponding ordering of measures in sigma-semirings. Moreover, the uniform topological measure spaces of NHCs need not always preserve the pushforward measures, and a NHC semiring is functionally separable by a set of inner-measurable functions.
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Devasthale, A., U. Willén, K. G. Karlsson, and C. G. Jones. "Quantifying the clear-sky temperature inversion frequency and strength over the Arctic Ocean during summer and winter seasons from AIRS profiles." Atmospheric Chemistry and Physics Discussions 10, no. 2 (February 4, 2010): 2835–58. http://dx.doi.org/10.5194/acpd-10-2835-2010.
Full textAbstract:
Abstract. Temperature inversions are one of the dominant features of the Arctic atmosphere and play a crucial role in various processes by controlling the transfer of mass and moisture fluxes through the lower troposphere. It is therefore essential that they are accurately quantified, monitored and simulated as realistically as possible over the Arctic regions. In the present study, the characteristics of inversions in terms of frequency and strength are quantified for the entire Arctic Ocean for summer and winter seasons of 2003 to 2008 using the AIRS data for the clear-sky conditions. The probability density functions (PDFs) of the inversion strength are also presented for every summer and winter month. Our analysis shows that although the inversion frequency along the coastal regions of Arctic decreases from June to August, inversions are still seen in almost each profile retrieved over the inner Arctic region. In winter, inversions are ubiquitous and are also present in every profile analysed over the inner Arctic region. When averaged over the entire study area (70° N–90° N), the inversion frequency in summer ranges from 69% to 86% for the ascending passes and 72% to 86% for the descending passes. For winter, the frequency values are 88% to 91% for the ascending passes and 89% to 92% for the descending passes of AIRS/AQUA. The PDFs of inversion strength for the summer months are narrow and right-skewed (or positively skewed), while in winter, they are much broader. In summer months, the mean values of inversion strength for the entire study area range from 2.5 K to 3.9 K, while in winter, they range from 7.8 K to 8.9 K. The standard deviation of the inversion strength is double in winter compared to summer. The inversions in the summer months of 2007 were very strong compared to other years. The warming in the troposphere of about 1.5 K to 3.0 K vertically extending up to 400 hPa was observed in the summer months of 2007.
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Holmuhamedov, Ekshon L., Sofija Jovanović, Petras P. Dzeja, Aleksandar Jovanović, and Andre Terzic. "Mitochondrial ATP-sensitive K+ channels modulate cardiac mitochondrial function." American Journal of Physiology-Heart and Circulatory Physiology 275, no. 5 (November 1, 1998): H1567—H1576. http://dx.doi.org/10.1152/ajpheart.1998.275.5.h1567.
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Discovered in the cardiac sarcolemma, ATP-sensitive K+(KATP) channels have more recently also been identified within the inner mitochondrial membrane. Yet the consequences of mitochondrial KATP channel activation on mitochondrial function remain partially documented. Therefore, we isolated mitochondria from rat hearts and used K+ channel openers to examine the effect of mitochondrial KATPchannel opening on mitochondrial membrane potential, respiration, ATP generation, Ca2+ transport, and matrix volume. From a mitochondrial membrane potential of −180 ± 15 mV, K+ channel openers, pinacidil (100 μM), cromakalim (25 μM), and levcromakalim (20 μM), induced membrane depolarization by 10 ± 7, 25 ± 9, and 24 ± 10 mV, respectively. This effect was abolished by removal of extramitochondrial K+ or application of a KATP channel blocker. K+ channel opener-induced membrane depolarization was associated with an increase in the rate of mitochondrial respiration and a decrease in the rate of mitochondrial ATP synthesis. Furthermore, treatment with a K+ channel opener released Ca2+ from mitochondria preloaded with Ca2+, an effect also dependent on extramitochondrial K+concentration and sensitive to KATP channel blockade. In addition, K+ channel openers, cromakalim and pinacidil, increased matrix volume and released mitochondrial proteins, cytochrome cand adenylate kinase. Thus, in isolated cardiac mitochondria, KATP channel openers depolarized the membrane, accelerated respiration, slowed ATP production, released accumulated Ca2+, produced swelling, and stimulated efflux of intermembrane proteins. These observations provide direct evidence for a role of mitochondrial KATP channels in regulating functions vital for the cardiac mitochondria.
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Everard-Gigot, Valerie, Cory D. Dunn, Brigid M. Dolan, Susanne Brunner, Robert E. Jensen, and Rosemary A. Stuart. "Functional Analysis of Subunit e of the F1Fo-ATP Synthase of the Yeast Saccharomyces cerevisiae: Importance of the N-Terminal Membrane Anchor Region." Eukaryotic Cell 4, no. 2 (February 2005): 346–55. http://dx.doi.org/10.1128/ec.4.2.346-355.2005.
Full textAbstract:
ABSTRACT Mitochondrial F1Fo-ATP synthase complexes do not exist as physically independent entities but rather form dimeric and possibly oligomeric complexes in the inner mitochondrial membrane. Stable dimerization of two F1Fo-monomeric complexes involves the physical association of two membrane-embedded Fo-sectors. Previously, formation of the ATP synthase dimeric-oligomeric network was demonstrated to play a critical role in modulating the morphology of the mitochondrial inner membrane. In Saccharomyces cerevisiae, subunit e (Su e) of the Fo-sector plays a central role in supporting ATP synthase dimerization. The Su e protein is anchored to the inner membrane via a hydrophobic region located at its N-terminal end. The hydrophilic C-terminal region of Su e resides in the intermembrane space and contains a conserved coiled-coil motif. In the present study, we focused on characterizing the importance of these regions for the function of Su e. We created a number of C-terminal-truncated derivatives of the Su e protein and expressed them in the Su e null yeast mutant. Mitochondria were isolated from the resulting transformant strains, and a number of functions of Su e were analyzed. Our results indicate that the N-terminal hydrophobic region plays important roles in the Su e-dependent processes of mitochondrial DNA maintenance, modulation of mitochondrial morphology, and stabilization of the dimer-specific Fo subunits, subunits g and k. Furthermore, we show that the C-terminal coiled-coil region of Su e functions to stabilize the dimeric form of detergent-solubilized ATP synthase complexes. Finally, we propose a model to explain how Su e supports the assembly of the ATP synthase dimers-oligomers in the mitochondrial membrane.
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Costanzo, Maria C., Nathalie Bonnefoy, Elizabeth H. Williams, G. Desmond Clark-Walker, and Thomas D. Fox. "Highly Diverged Homologs of Saccharomyces cerevisiae Mitochondrial mRNA-Specific Translational Activators Have Orthologous Functions in Other Budding Yeasts." Genetics 154, no. 3 (March 1, 2000): 999–1012. http://dx.doi.org/10.1093/genetics/154.3.999.
Full textAbstract:
Abstract Translation of mitochondrially coded mRNAs in Saccharomyces cerevisiae depends on membrane-bound mRNA-specific activator proteins, whose targets lie in the mRNA 5′-untranslated leaders (5′-UTLs). In at least some cases, the activators function to localize translation of hydrophobic proteins on the inner membrane and are rate limiting for gene expression. We searched unsuccessfully in divergent budding yeasts for orthologs of the COX2- and COX3-specific translational activator genes, PET111, PET54, PET122, and PET494, by direct complementation. However, by screening for complementation of mutations in genes adjacent to the PET genes in S. cerevisiae, we obtained chromosomal segments containing highly diverged homologs of PET111 and PET122 from Saccharomyces kluyveri and of PET111 from Kluyveromyces lactis. All three of these genes failed to function in S. cerevisiae. We also found that the 5′-UTLs of the COX2 and COX3 mRNAs of S. kluyveri and K. lactis have little similarity to each other or to those of S. cerevisiae. To determine whether the PET111 and PET122 homologs carry out orthologous functions, we deleted them from the S. kluyveri genome and deleted PET111 from the K. lactis genome. The pet111 mutations in both species prevented COX2 translation, and the S. kluyveri pet122 mutation prevented COX3 translation. Thus, while the sequences of these translational activator proteins and their 5′-UTL targets are highly diverged, their mRNA-specific functions are orthologous.
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Jaisser, F., N. Coutry, N. Farman, H. J. Binder, and B. C. Rossier. "A putative H(+)-K(+)-ATPase is selectively expressed in surface epithelial cells of rat distal colon." American Journal of Physiology-Cell Physiology 265, no. 4 (October 1, 1993): C1080—C1089. http://dx.doi.org/10.1152/ajpcell.1993.265.4.c1080.
Full textAbstract:
Recently, a putative distal colon H(+)-K(+)-ATPase alpha-subunit has been identified and characterized (M. S. Crowson and G. E. Shull. J. Biol. Chem. 267:13740-13748, 1992). In the present study, we report the tissue and cell expression of this putative H(+)-K(+)-ATPase. The results indicate that, first, in the gut, the putative H(+)-K(+)-ATPase alpha-subunit is restricted to the distal part of the colon and is predominantly expressed in surface epithelial cells, in marked contrast to the alpha 1-subunit of Na(+)-K(+)-ATPase that is also expressed in glands. These data suggest that the H(+)-K(+)-ATPase alpha-subunit is a potential marker for terminal differentiation of distal colon. Second, in the uterus, the putative H(+)-K(+)-ATPase is restricted to the region of the myometrium between the inner and midmuscular zone that is very rich in vascular supply and nerve cells. This striking expression suggests that the H(+)-K(+)-ATPase may not be involved in the control of pH and potassium concentration of the uterine fluid but rather in distinct functions of vascular and/or nerve cells. Third, with the use of three independent and different approaches (Northern blot analysis, ribonuclease protection assay, and in situ hybridization), we were unable to detect any significant amount of H(+)-K(+)-ATPase transcripts in kidney tissue. Our data suggest that the putative distal colon H(+)-K(+)-ATPase is probably distinct from the kidney isoform. Finally, we report the sequence of a set of degenerate oligonucleotides that are useful to clone alpha-subunits of the Na(+)-K(+)-/H(+)-K(+)-ATPase gene family in different tissues and different species.
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Grigoryan, S. A., and T. V. Tonev. "Blaschke inductive limits of uniform algebras." International Journal of Mathematics and Mathematical Sciences 27, no. 10 (2001): 599–620. http://dx.doi.org/10.1155/s0161171201006792.
Full textAbstract:
We consider and studyBlaschke inductive limit algebrasA(b), defined as inductive limits of disc algebrasA(D)linked by a sequenceb={Bk}k=1∞of finite Blaschke products. It is well known that bigG-disc algebrasAGover compact abelian groupsGwith ordered dualsΓ=Gˆ⊂ℚcan be expressed as Blaschke inductive limit algebras. Any Blaschke inductive limit algebraA(b)is a maximal and Dirichlet uniform algebra. Its Shilov boundary∂A(b)is a compact abelian group with dual group that is a subgroup ofℚ. It is shown that a bigG-disc algebraAGover a groupGwith ordered dualGˆ⊂ℝis a Blaschke inductive limit algebra if and only ifGˆ⊂ℚ. The local structure of the maximal ideal space and the set of one-point Gleason parts of a Blaschke inductive limit algebra differ drastically from the ones of a bigG-disc algebra. These differences are utilized to construct examples of Blaschke inductive limit algebras that are not bigG-disc algebras. A necessary and sufficient condition for a Blaschke inductive limit algebra to be isometrically isomorphic to a bigG-disc algebra is found. We consider also inductive limitsH∞(I)of algebrasH∞, linked by a sequenceI={Ik}k=1∞of inner functions, and prove a version of the corona theorem with estimates for it. The algebraH∞(I)generalizes the algebra of bounded hyper-analytic functions on an open bigG-disc, introduced previously by Tonev.
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Mitsopoulos, Panagiotis, Julie St-Pierre, Stanley Dunn, and Joaquín Madrenas. "Bioenergetics of stomatin-like protein-2-deficient T cells reveal a regulatory role for this protein in immunometabolism (P1173)." Journal of Immunology 190, no. 1_Supplement (May 1, 2013): 50.29. http://dx.doi.org/10.4049/jimmunol.190.supp.50.29.
Full textAbstract:
Abstract Stomatin-like protein (SLP)-2 is a mainly mitochondrial protein identified in proteome analysis of glycolipid-enriched membrane microdomains of mammalian cells, and modulates T cell activation. To study SLP-2 function we generated T cell-specific SLP-2 knockout (SLP-2 T-K/O) mice since conventional SLP-2 knockout mice were embryonic lethal at the pre-implantation stage. These mice showed reduced CD4+ T cell responses and decreased respiratory complex I and II+III activities. Our mechanistic studies suggest SLP-2 recruits prohibitins to cardiolipin (CL)-enriched domains in the mitochondrial inner membrane to form specialized CL-enriched membrane microdomains, required for optimal cellular respiration. We hypothesized SLP-2 functions in this manner to regulate the bioenergetics of T cells. Seahorse XF analysis revealed that although SLP-2 T-K/O cells showed unaltered total cellular and mitochondrial oxygen consumption rates (OCRs), they had significantly greater non-mitochondrial OCR, mitochondrial OCR uncoupled from ATP synthesis, and greater reliance on glycolysis (71% of mice). Surprisingly, SLP-2 T-K/O cells exhibited greater spare respiratory capacity, a phenomenon not due to differential sensitivities of cells to uncoupling agents. This new immunometabolic phenotype suggests SLP-2 may regulate assembly of functional respiratory supercomplexes. Bioenergetic and biochemical analyses of mitochondria are underway to establish the regulatory role of SLP-2 in T cell metabolism.
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Devasthale, A., U. Willén, K. G. Karlsson, and C. G. Jones. "Quantifying the clear-sky temperature inversion frequency and strength over the Arctic Ocean during summer and winter seasons from AIRS profiles." Atmospheric Chemistry and Physics 10, no. 12 (June 22, 2010): 5565–72. http://dx.doi.org/10.5194/acp-10-5565-2010.
Full textAbstract:
Abstract. Temperature inversions are one of the dominant features of the Arctic atmosphere and play a crucial role in various processes by controlling the transfer of mass and moisture fluxes through the lower troposphere. It is therefore essential that they are accurately quantified, monitored and simulated as realistically as possible over the Arctic regions. In the present study, the characteristics of inversions in terms of frequency and strength are quantified for the entire Arctic Ocean for summer and winter seasons of 2003 to 2008 using the AIRS data for the clear-sky conditions. The probability density functions (PDFs) of the inversion strength are also presented for every summer and winter month. Our analysis shows that although the inversion frequency along the coastal regions of Arctic decreases from June to August, inversions are still seen in almost each profile retrieved over the inner Arctic region. In winter, inversions are ubiquitous and are also present in every profile analysed over the inner Arctic region. When averaged over the entire study area (70° N–90° N), the inversion frequency in summer ranges from 69 to 86% for the ascending passes and 72–86% for the descending passes. For winter, the frequency values are 88–91% for the ascending passes and 89–92% for the descending passes of AIRS/AQUA. The PDFs of inversion strength for the summer months are narrow and right-skewed (or positively skewed), while in winter, they are much broader. In summer months, the mean values of inversion strength for the entire study area range from 2.5 to 3.9 K, while in winter, they range from 7.8 to 8.9 K. The standard deviation of the inversion strength is double in winter compared to summer. The inversions in the summer months of 2007 were very strong compared to other years. The warming in the troposphere of about 1.5–3.0 K vertically extending up to 400 hPa was observed in the summer months of 2007.
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Babe Cheikh, A., A. Bouhlal, A. Jellal, and E. H. Atmani. "Tunneling effect in gapped graphene disk in magnetic flux and electrostatic potential." Physica Scripta 96, no. 12 (November 30, 2021): 125863. http://dx.doi.org/10.1088/1402-4896/ac3b6a.
Full textAbstract:
Abstract We investigate the tunneling effect of a Corbino disk in graphene in the presence of a variable magnetic flux Φ i created by a solenoid piercing the inner disk under the effect of a finite mass term in the disk region (R 1 < r < R 2) and an electrostatic potential. Considering different regions, we explicitly determine the associated eigenspinors in terms of Hankel functions. The use of matching conditions and asymptotic behavior of Hankel functions for large arguments, enables us to calculate transmission and other transport quantities. Our results show that the energy gap suppresses the tunneling effect by creating singularity points of zero transmission corresponding to the maximum shot noise peaks quantified by the Fano factor F. The transmission as a function of the radii ratio R 2/R 1 becomes oscillatory with a decrease in periods and amplitudes. It can even reach one (Klein tunneling) for large values of the energy gap. The appearance of the minimal conductance at the points k F R 1 = R 1 δ is observed. Finally we find that the electrostatic potential can control the effect of the band gap.
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Ahmad, Nisar, Ivana L. de la Serna, Himangi G. Marathe, Xiaoming Fan, Prabhatchandra Dube, Shungang Zhang, Steven T. Haller, David J. Kennedy, Nikolay B. Pestov, and Nikolai N. Modyanov. "Eutherian-Specific Functions of BetaM Acquired through Atp1b4 Gene Co-Option in the Regulation of MyoD Expression." Life 13, no. 2 (February 2, 2023): 414. http://dx.doi.org/10.3390/life13020414.
Full textAbstract:
Vertebrate ATP1B4 genes represent a rare instance of orthologous gene co-option, resulting in radically different functions of the encoded BetaM proteins. In lower vertebrates, BetaM is a Na, K-ATPase β-subunit that is a component of ion pumps in the plasma membrane. In placental mammals, BetaM lost its ancestral role and, through structural alterations of the N-terminal domain, became a skeletal and cardiac muscle-specific protein of the inner nuclear membrane, highly expressed during late fetal and early postnatal development. We previously determined that BetaM directly interacts with the transcriptional co-regulator SKI-interacting protein (SKIP) and is implicated in the regulation of gene expression. This prompted us to investigate a potential role for BetaM in the regulation of muscle-specific gene expression in neonatal skeletal muscle and cultured C2C12 myoblasts. We found that BetaM can stimulate expression of the muscle regulatory factor (MRF), MyoD, independently of SKIP. BetaM binds to the distal regulatory region (DRR) of MyoD, promotes epigenetic changes associated with activation of transcription, and recruits the SWI/SNF chromatin remodeling subunit, BRG1. These results indicate that eutherian BetaM regulates muscle gene expression by promoting changes in chromatin structure. These evolutionarily acquired new functions of BetaM might be very essential and provide evolutionary advantages to placental mammals.
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Schroeder, Indra, and Ulf-Peter Hansen. "Tl+-induced μs Gating of Current Indicates Instability of the MaxiK Selectivity Filter as Caused by Ion/Pore Interaction." Journal of General Physiology 131, no. 4 (March 31, 2008): 365–78. http://dx.doi.org/10.1085/jgp.200809956.
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Patch clamp experiments on single MaxiK channels expressed in HEK293 cells were performed at high temporal resolution (50-kHz filter) in asymmetrical solutions containing 0, 25, 50, or 150 mM Tl+ on the luminal or cytosolic side with [K+] + [Tl+] = 150 mM and 150 mM K+ on the other side. Outward current in the presence of cytosolic Tl+ did not show fast gating behavior that was significantly different from that in the absence of Tl+. With luminal Tl+ and at membrane potentials more negative than −40 mV, the single-channel current showed a negative slope resistance concomitantly with a flickery block, resulting in an artificially reduced apparent single-channel current Iapp. The analysis of the amplitude histograms by β distributions enabled the estimation of the true single-channel current and the determination of the rate constants of a simple two-state O-C Markov model for the gating in the bursts. The voltage dependence of the gating ratio R = Itrue/Iapp = (kCO + kOC)/kCO could be described by exponential functions with different characteristic voltages above or below 50 mM Tl+. The true single-channel current Itrue decreased with Tl+ concentrations up to 50 mM and stayed constant thereafter. Different models were considered. The most likely ones related the exponential increase of the gating ratio to ion depletion at the luminal side of the selectivity filter, whereas the influence of [Tl+] on the characteristic voltage of these exponential functions and of the value of Itrue were determined by [Tl+] at the inner side of the selectivity filter or in the cavity.
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Ogierman, Monica, and Volkmar Braun. "Interactions between the Outer Membrane Ferric Citrate Transporter FecA and TonB: Studies of the FecA TonB Box." Journal of Bacteriology 185, no. 6 (March 15, 2003): 1870–85. http://dx.doi.org/10.1128/jb.185.6.1870-1885.2003.
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ABSTRACT Both induction of transcription of the ferric citrate transport genes and transport of ferric citrate by the Escherichia coli outer membrane receptor FecA require energy derived from the proton motive force (PMF) of the inner membrane. The energy is transduced to FecA by the inner membrane complex, TonB, ExbB, and ExbD. Region 160 of TonB and the conserved TonB box of other TonB-dependent receptors are implicated as sites of interaction. In the present study, the postulated TonB box (D80A81L82T83V84) of FecA was deleted in frame, with a subsequent loss of both FecA functions. DALTV of FecA could be functionally replaced with the core TonB boxes of FhuA (DTITV) and FepA (DTIVV). Each residue of the TonB box of FecA was sequentially replaced with cysteine residues, and only the D80C replacement showed a loss (reduction) of both FecA functions. A physical interaction between TonB and FecA was demonstrated using both in vivo site-specific disulfide bond cross-linking and nonspecific formaldehyde (FA) cross-linking. Pairwise combinations of FecA (DALTV)/Cys substitutions were cross-linked via disulfide bond formation with TonBQ160C, TonBQ162C, and TonBY163C. Unexpectedly, this cross-linking was not enhanced by substrate (ferric citrate). In contrast, the TonB-FecA interaction was enhanced by ferric citrate in the FA-cross-linking assay. Energy derived from the PMF was not required for the TonB-FecA interaction in either the disulfide- or FA-cross-linking assay. TonB/CysExbB/ExbD(D25N) was still able to cross-link with the FecA (DALTV)/Cys derivatives in a tonB tolQ background, even though ExbD25N renders the TonB/ExbBD complex nonfunctional (V. Braun, S. Gaisser, C. Herrmann, K. Kampfenkel, H. Killmann, and I. Traub, J. Bacteriol. 178:2836-2845, 1996). TonB cross-linked to FecA via FA was not inhibited by either carbonylcyanide-m-chlorophenylhydrazone or 1 mM 2,4-dinitrophenol, which dissipate the electrochemical potential of the cytoplasmic membrane and disrupt both FecA functions. The studies shown here demonstrate the significance of the TonB box for FecA functions and are consistent with the view that it is the structure and not the sequence of the TonB box that is important for activity. Demonstrated here for the first time is the physical interaction of TonB and FecA, which is enhanced by ferric citrate.
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Schippers, Eric, and Wolfgang Staubach. "Plemelj–Sokhotski isomorphism for quasicircles in Riemann surfaces and the Schiffer operators." Mathematische Annalen 378, no. 3-4 (October 31, 2019): 1613–53. http://dx.doi.org/10.1007/s00208-019-01922-4.
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Abstract Let R be a compact Riemann surface and $$\Gamma $$ Γ be a Jordan curve separating R into connected components $$\Sigma _1$$ Σ 1 and $$\Sigma _2$$ Σ 2 . We consider Calderón–Zygmund type operators $$T(\Sigma _1,\Sigma _k)$$ T ( Σ 1 , Σ k ) taking the space of $$L^2$$ L 2 anti-holomorphic one-forms on $$\Sigma _1$$ Σ 1 to the space of $$L^2$$ L 2 holomorphic one-forms on $$\Sigma _k$$ Σ k for $$k=1,2$$ k = 1 , 2 , which we call the Schiffer operators. We extend results of Max Schiffer and others, which were confined to analytic Jordan curves $$\Gamma $$ Γ , to general quasicircles, and prove new identities for adjoints of the Schiffer operators. Furthermore, let V be the space of anti-holomorphic one-forms which are orthogonal to $$L^2$$ L 2 anti-holomorphic one-forms on R with respect to the inner product on $$\Sigma _1$$ Σ 1 . We show that the restriction of the Schiffer operator $$T(\Sigma _1,\Sigma _2)$$ T ( Σ 1 , Σ 2 ) to V is an isomorphism onto the set of exact holomorphic one-forms on $$\Sigma _2$$ Σ 2 . Using the relation between this Schiffer operator and a Cauchy-type integral involving Green’s function, we also derive a jump decomposition (on arbitrary Riemann surfaces) for quasicircles and initial data which are boundary values of Dirichlet-bounded harmonic functions and satisfy the classical algebraic constraints. In particular we show that the jump operator is an isomorphism on the subspace determined by these constraints.
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Natalya V., Nalegach. "The Role of the Motive of Reading in K. Paustovsky’s Novel Shining Clouds (1928)." Humanitarian Vector 15, no. 5 (October 2020): 28–35. http://dx.doi.org/10.21209/1996-7853-2020-15-5-28-35.
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The article is devoted to the consideration of the artistic functioning of the reading motive in K. G.Paustovsky’s little-known novel Shining Clouds (1928). The motivational analysis undertaken in the work revealed the significance of the readers’ horizons of the characters of the work, not only for characterizing their inner world. In the case when it comes to the reading circle of the main characters, we can talk about the functions of plot prediction and create the pathos of romance. In this regard, mentioning the works by J. London, V. Hugo, E. T. A. Hoffmann, O. Henry, etc., is noteworthy. Since the plot of Shining Clouds is subordinated to the genre assignment of a detective-adventurous novel, the reading experience of such heroes as captain Kravchenko, Baturin and Berg allows you to actualize this form, performing the role of the genre framework in a work with a high level of lyrical digressions. Of particular note is the insertion text ‒ Nelidov’s diary, which simultaneously functions as the sought-after treasure and the actual text, in which engineering and art are organically combined. By virtue of this position in the structure of the novel, Nelidov’s diary enters into complex dialogical relations with other works read by heroes, which prompts a closer analysis of its fragments in comparison with the works of real writers. This comparison comes to the fore in the poem Galatea by L. Mei and the travelogue Journey to Arzrum by A. S. Pushkin, which allows you to see the place of the reading motive in the motif-thematic complex of creativity, as well as go to the author’s concept of a new person embodied in the image of Nelidov and a genuine value that encourages the heroes of the novel to go on a “treasure hunt”. Keywords: K. Paustovsky, motive, reading, novel, poetics
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Sekiguchi, Yuji, Yoichi Kamagata, Kazunori Nakamura, Akiyoshi Ohashi, and Hideki Harada. "Fluorescence In Situ Hybridization Using 16S rRNA-Targeted Oligonucleotides Reveals Localization of Methanogens and Selected Uncultured Bacteria in Mesophilic and Thermophilic Sludge Granules." Applied and Environmental Microbiology 65, no. 3 (March 1, 1999): 1280–88. http://dx.doi.org/10.1128/aem.65.3.1280-1288.1999.
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ABSTRACT 16S rRNA-targeted in situ hybridization combined with confocal laser scanning microscopy was used to elucidate the spatial distribution of microbes within two types of methanogenic granular sludge, mesophilic (35°C) and thermophilic (55°C), in upflow anaerobic sludge blanket reactors fed with sucrose-, acetate-, and propionate-based artificial wastewater. The spatial organization of the microbes was visualized in thin sections of the granules by using fluorescent oligonucleotide probes specific to several phylogenetic groups of microbes. In situ hybridization with archaeal- and bacterial-domain probes within granule sections clearly showed that both mesophilic and thermophilic granules had layered structures and that the outer layer harbored mainly bacterial cells while the inner layer consisted mainly of archaeal cells. Methanosaeta-,Methanobacterium-, Methanospirillum-, andMethanosarcina-like cells were detected with oligonucleotide probes specific for the different groups of methanogens, and they were found to be localized inside the granules, in both types of which dominant methanogens were members of the genusMethanosaeta. For specific detection of bacteria which were previously detected by whole-microbial-community 16S ribosomal DNA (rDNA)-cloning analysis (Y. Sekiguchi, Y. Kamagata, K. Syutsubo, A. Ohashi, H. Harada, and K. Nakamura, Microbiology 144:2655–2665, 1998) we designed probes specific for clonal 16S rDNAs related to unidentified green nonsulfur bacteria and clones related toSyntrophobacter species. The probe designed for the cluster closely related to Syntrophobacter species hybridized with coccoid cells in the inner layer of the mesophilic granule sections. The probe for the unidentified bacteria which were clustered with the green nonsulfur bacteria detected filamentous cells in the outermost layer of the thermophilic sludge granule sections. These results revealed the spatial organizations of methanogens and uncultivated bacteria and their in situ morphologies and metabolic functions in both mesophilic and thermophilic granular sludges.
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Baiburin, Merkhasyl. "About nonlinear integro-differential Volterra and Fredholm equations." Applied Mathematics and Control Sciences, no. 4 (January 26, 2022): 7–20. http://dx.doi.org/10.15593/2499-9873/2021.4.01.
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Two nonlinear problems in terms of abstract operator equations of the form Bx = f are investigated in this paper. In the first problem the operator B contains a linear differential operator A , the Volterra operator K with kernel of convolution type and the inner product of vectors g ( x )Ф( u ) with nonlinear bounded functionals Φ. The first problem is given by equation Bu ( x ) = Аu ( x ) - Ku ( x ) - g ( x )Ф( u ) = f ( x ) with boundary condition D ( B ) = D ( A ). In the second problem the operator B contains a linear differential operator A and the inner product of vectors g ( x )F( Аu ) with nonlinear bounded on C [ a , b ] functionals F , where F ( Аu ) denotes the nonlinear Fredholm integral. The second problem is presented by equation Bu = Аu - gF ( Au ) = f with boundary condition D ( B ) = D ( A ). A direct method for exact solutions of nonlinear integro-differential Volterra and Fredholm equations is proposed. Specifically, the three theorems about existing exact solutions are proved in this paper. The first theorem is mean that for nonzero constant α0 Volterra integro-differential equation Аu ( x ) - Ku ( x ) = 0 is reducing to Volterra integral equation and has a unique zero solution. During it the operator A - K is closed and continuously invertible. Also, if the functions u ( t ), g ( t ) and f ( t ) are of exponential order α then nonhomogeneous equation Аu ( x ) - Ku ( x ) = f ( x ) for each f ( x ) has a unique solution, shown in this paper. The second theorem is mean that for the first investigated problem with an injective operator A - K , for f ( x ) and g ( x ) from C [ a , b ], the exact solution is given by equation u = ( A - K )- 1 f +( A - K )- 1 g b* for every vector b* = Ф( u ) that solves nonlinear algebraic (transcendental) system of n equations b = Ф(( A - K )- 1 f +( A - K )- 1 g b). And if the last algebraic system has no solution, then investigated problem also has no solution. The third theorem is means that exact solution of the second investigated problem is given by u = A - 1( f+g d*) for every vector d* = F ( Au ) that solves nonlinear algebraic (transcendental) system of n equations d = F ( f + g d). In this case we have same property - if the last algebraic system has no solution, then investigated problem also has no solution. Two particular examples for each considered problem are shown for illustration of exact solutions giving by perform the suggested in this paper methods. In the first example was considered integro-differential Volterra and Fredholm equation and in the second case was considered equation with nonlinear Fredholm integral.
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Schneider, B. G., A. W. Shyjan, and R. Levenson. "Co-localization and polarized distribution of Na,K-ATPase alpha 3 and beta 2 subunits in photoreceptor cells." Journal of Histochemistry & Cytochemistry 39, no. 4 (April 1991): 507–17. http://dx.doi.org/10.1177/39.4.1848572.
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Na,K-ATPase plays a central role in the visual sensitivity of photoreceptors by driving the dark current of vision. The alpha 3 and beta 2 isoforms of Na,K-ATPase were previously shown to be the major alpha and beta subunit mRNAs expressed in photoreceptors. Here we compared the distribution of beta-subunits of the enzyme in the retina and kidney, using electron microscopic immunocytochemistry with specific antibodies against alpha 3, beta 1, and beta 2 isoforms as well as with an antibody (Ax2) that binds to alpha 2 and/or alpha 3 isoforms. Both the alpha 3 and beta 2 isoforms were localized to photoreceptor inner segments at highest labeling density between the base of the connecting cilium and the outer limiting membrane (OLM). Quantitative analysis of Ax2 antibody binding to alpha 3 revealed a significant decrease in labeling density below the OLM and above the base of the connecting cilium. Although the beta 2-subunit has been reported to have adhesive functions in glial cells in cerebellum, we detected beta 2 in the photoreceptor, a cell of neural origin, but not in the Mueller cell, the glial cell of the retina. Moreover, anti-beta 2 antibodies bound maximally to portions of photoreceptor cells not involved in cell-cell contact.
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Nieves-González, Aniel, Chris Clausen, Mariano Marcano, Anita T. Layton, Harold E. Layton, and Leon C. Moore. "Fluid dilution and efficiency of Na+ transport in a mathematical model of a thick ascending limb cell." American Journal of Physiology-Renal Physiology 304, no. 6 (March 15, 2013): F634—F652. http://dx.doi.org/10.1152/ajprenal.00100.2012.
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Thick ascending limb (TAL) cells are capable of reducing tubular fluid Na+ concentration to as low as ∼25 mM, and yet they are thought to transport Na+ efficiently owing to passive paracellular Na+ absorption. Transport efficiency in the TAL is of particular importance in the outer medulla where O2 availability is limited by low blood flow. We used a mathematical model of a TAL cell to estimate the efficiency of Na+ transport and to examine how tubular dilution and cell volume regulation influence transport efficiency. The TAL cell model represents 13 major solutes and the associated transporters and channels; model equations are based on mass conservation and electroneutrality constraints. We analyzed TAL transport in cells with conditions relevant to the inner stripe of the outer medulla, the cortico-medullary junction, and the distal cortical TAL. At each location Na+ transport efficiency was computed as functions of changes in luminal NaCl concentration ([NaCl]), [K+], [NH4+], junctional Na+ permeability, and apical K+ permeability. Na+ transport efficiency was calculated as the ratio of total net Na+ transport to transcellular Na+ transport. Transport efficiency is predicted to be highest at the cortico-medullary boundary where the transepithelial Na+ gradient is the smallest. Transport efficiency is lowest in the cortex where luminal [NaCl] approaches static head.
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Tong, Bao Hong, Xiao Qian Sun, and Hong Su. "Numerical Simulation on Internal Flow Field of Rolling Bearing under Oil-Air Lubrication." Applied Mechanics and Materials 271-272 (December 2012): 1056–61. http://dx.doi.org/10.4028/www.scientific.net/amm.271-272.1056.
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Heat dissipation and working efficiency of transport air in rolling bearing under oil-air lubrication are closely related to the flowing state of oil-air in bearing chamber. For cylindrical roller bearing NF211, numerical simulation model of oil-air flow field in bearing chamber was established combining with the practical structure features of rolling bearing and ignoring the effect caused by roller rotation. Combining with flow field numerical simulation functions of Fluent software, simulation analysis of the flow state in bearing chamber were carried out. Based on k-ε turbulent model, three-dimensional flow field in the bearing chamber and main feature parameters of inner flow were got analyzed carefully considering the effect of twirling. Comparing with the numerical simulation of simplified flow field, it showed that energy dissipation and axial velocity of the air were influenced by the effect of twirling distinctly. Simulation results were expected to give useful references for the optimization design of the oil-air lubrication system in rolling bearing.