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The main preoccupation of this article is the characterization of Richard's inequality, which it is closely related to Buzano's inequality. Finally, we present a new approach for Richard's inequality, where we use the Selberg operator. [ABSTRACT FROM AUTHOR]

In this paper, we prove some singular value inequalities for sums and products of matrices. Some of our inequalities will give several generalizations of recent known inequalities. Among other inequalities, we prove that if A,B,C,D,X,Y are n×n complex matrices such that X and Y are positive semidefinite, then... for j = 1,2,. . ., n, which is a generalization of an inequality in [12]. Here, s j and ||·|| denote the singular value and the spectral norm of matrices, respectively. [ABSTRACT FROM AUTHOR]

Operator matrices have played a significant role in the study of properties of the numerical radii of Hilbert space operators. This paper presents several new sharp upper bounds for the numerical radii of operator matrices in terms of certain complex combinations. The obtained results reveal many interesting properties of the numerical radius. [ABSTRACT FROM AUTHOR]

In this article, we delve into the classic Bohr inequality for complex numbers, a fundamental result in complex analysis with broad mathematical applications. We offer refinements and generalizations of Bohr's inequality, expanding on the established inequalities of N. G. de Bruijn and Radon, as well as leveraging the class of functions defined by the Daykin–Eliezer–Carlitz inequality. Our novel contribution lies in demonstrating that Bohr's and Bergström's inequalities can be derived from one another, revealing a deeper interconnectedness between these results. Furthermore, we present several new generalizations of Bohr's inequality, along with other notable inequalities from the literature, and discuss their various implications. By providing more comprehensive and verifiable conditions, our work extends previous research and enhances the understanding and applicability of Bohr's inequality in mathematical studies. [ABSTRACT FROM AUTHOR]

In this paper, we introduce the f-operator radius of Hilbert space operators as a generalization of the Euclidean operator radius and the q-operator radius. The properties of the newly defined radius are discussed, emphasizing how it extends some known results in the literature. [ABSTRACT FROM AUTHOR]

The classical Bohr inequality for scalars was extended to the non-commutative case of Hilbert space operators in the literature. The sole goal of this article is to discuss the operator Bohr inequality and present some of its new variants. This includes fresh reverses and refinements of this inequality with applications towards an operator's real and imaginary parts, not to forget the new discussion of different domains of the parameters. One further application towards the operator Dunkl-Williams inequality will be presented too. While the new results are interesting, we emphasize that the approach used to explore these inequalities differs from the existing literature methods for this context. [ABSTRACT FROM AUTHOR]

This paper investigates possible upper and lower bounds for the numerical radii of 2 × 2 operator matrices. The obtained results improve and generalize many results from the literature in accessible forms. Moreover, many numerical examples will be given to support the feasibility of our findings. [ABSTRACT FROM AUTHOR]

In this paper we establish different refinements and applications of the Hermite-Hadamard inequality for convex functions in the context of NPC global spaces.

The main focus of this paper is the study of the Selberg operator. It aims to establish appropriate bounds for the norm and numerical radius of the product of three bounded operators, with one of them being a Selberg operator. Moreover, it offers several bounds involving the summation of operators, notably the Selberg operator. Through the examination of these properties and relationships, this study contributes to a better understanding of the Selberg operator and its influence on operator compositions. The paper also highlights the significance of symmetry in mathematics and its potential implications across various mathematical domains. [ABSTRACT FROM AUTHOR]

Our aim in this article is to establish several new norm and numerical radius inequalities for products and sums of operators acting on a complex Hilbert space (H , 〈 · , · 〉) . Some of the obtained inequalities improve well known ones. In addition, by using new techniques, we prove certain new inequalities related to ω A (·) and | | · | | A , where ω A (T) and | | T | | A denote the A-numerical radius and the A-operator seminorm of an operator T acting on the semi-Hilbert space (H , 〈 · , · 〉 A) , respectively. Here 〈 x , y 〉 A : = 〈 A x , y 〉 for every x , y ∈ H . [ABSTRACT FROM AUTHOR]

This paper introduces several refinements of the classical Selberg inequality, which is considered a significant result in the study of the spectral theory of symmetric spaces, a central topic in the field of symmetry studies. By utilizing the contraction property of the Selberg operator, we derive improved versions of the classical Selberg inequality. Additionally, we demonstrate the interdependence among well-known inequalities such as Cauchy–Schwarz, Bessel, and the Selberg inequality, revealing that these inequalities can be deduced from one another. This study showcases the enhancements made to the classical Selberg inequality and establishes the interconnectedness of various mathematical inequalities. [ABSTRACT FROM AUTHOR]

The main goal of this work is to present new matrix inequalities of Cauchy-Schwarz type. In particular, we investigate the so-called Lieb functions, whose definition came as an umbrella of Cauchy-Schwarz-like inequalities, then we consider the mixed Cauchy-Schwarz inequality. This latter inequality has been influential in obtaining several other matrix inequalities, including numerical radius and norm results. Among many other results, we show that ||T||≤1/4(|| |T|+|T*|+2RT||+|| T|+|T*|-2RT||) where RT is the real part of the matrix T. [ABSTRACT FROM AUTHOR]

The paper deals with the generalized numerical radius of linear operators acting on a complex Hilbert space H , which are bounded with respect to the seminorm induced by a positive operator A on H . Here A is not assumed to be invertible. Mainly, if we denote by ω A (⋅) and ω (⋅) the generalized and the classical numerical radii respectively, we prove that for every A-bounded operator T we have ω A (T) = ω ( A 1 / 2 T (A 1 / 2 ) † ) , where (A 1 / 2 ) † is the Moore-Penrose inverse of A 1 / 2 . In addition, several new inequalities involving ω A (⋅) for single and several operators are established. In particular, by using new techniques, we cover and improve some recent results due to Najafi [Linear Algebra Appl. 2020;588:489–496]. [ABSTRACT FROM AUTHOR]

Two graphs having the same spectrum are said to be cospectral. A pair of singularly cospectral graphs is formed by two graphs such that the absolute values of their nonzero eigenvalues coincide. Clearly, a pair of cospectral graphs is also singularly cospectral but the converse may not be true. Two graphs are almost cospectral if their nonzero eigenvalues and their multiplicities coincide. In this paper, we present necessary and sufficient conditions for a pair of graphs to be singularly cospectral, giving an answer to a problem posted by Nikiforov. In addition, we construct an infinite family of pairs of noncospectral singularly cospectral graphs with unbounded number of vertices. It is clear that almost cospectral graphs are also singularly cospectral but the converse is not necessarily true, we present families of graphs where both concepts: almost cospectrality and singularly cospectrality agree. [ABSTRACT FROM AUTHOR]

In this paper we present refinements and improvement of the Young inequality in the context of linear bounded operators [ABSTRACT FROM AUTHOR]

This paper studies the metric structure of manifolds of semi-negative curvature. Explicit estimates on the geodesic distance and sectional curvature are obtained in the setting of homogeneous spaces G/K of Banach–Lie groups, and a characterization of convex homogeneous submanifolds is given in terms of the Banach–Lie algebras. A splitting theorem via convex expansive submanifolds is proved, inducing the corresponding splitting of the Banach–Lie group G. The notion of nonpositive curvature in Alexandrov's sense is extended to include p-uniformly convex Banach spaces, and manifolds of semi-negative curvature with a p-uniformly convex tangent norm fall in this class of nonpositively curved spaces. Several well-known results, such as the existence and uniqueness of best approximations from convex closed sets, or the Bruhat–Tits fixed-point theorem, are shown to hold in this setting, without dimension restrictions. Finally, these notions are used to study the structure of the classical Banach–Lie groups of bounded linear operators acting on a Hilbert space, and the splittings induced by conditional expectations in such a setting. [ABSTRACT FROM PUBLISHER]

The aim of this study was to evaluate the influence of the poly-L-lactic acid (PLLA)-based scaffold's pore size on the proliferation and differentiation of dental pulp stem cells (DPSCs). The scaffolds were prepared in pulp chambers of 1-mm-thick tooth slices from third molars using salt crystals (150-250 µm or 251-450 µm) as porogen. DPSC (1x105 cells) were seeded in the scaffolds with different pore sizes, and cultured in 24-well plates. The cell proliferation was evaluated using the WST-1 assay after 3-21 days. Furthermore, RT-PCR was used to assess the differentiation of the DPSCs into odontoblasts, using markers of odontoblastic differentiation (DSPP, DSP-1 and MEPE). RNA from human odontoblasts was used as control. Cell proliferation rate was similar in both scaffolds except at the 14th day period, in which the cells seeded in the scaffolds with larger pores showed higher proliferation (p<0.05). After 21 days DPSCs seeded in both evaluated scaffolds were able of expressing odontoblastic markers DMP-1, DSPP and MEPE. In summary, both scaffolds tested in this study allowed the proliferation and differentiation of DPSCs into odontoblast-like cells.