156 research outputs found

    On minimal norms on MnM_n

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    In this note, we show that for each minimal norm N()N(\cdot) on the algebra MnM_n of all n×nn \times n complex matrices, there exist norms 1\|\cdot\|_1 and 2\|\cdot\|_2 on Cn{\mathbb C}^n such that N(A)=max{Ax2:x1=1,xCn}N(A)=\max\{\|Ax\|_2: \|x\|_1=1, x\in {\mathbb C}^n\} for all AMnA \in M_n. This may be regarded as an extension of a known result on characterization of minimal algebra norms.Comment: 4 pages, to appear in Abstract and Applied Analysi

    A trick for investigation of approximate derivations

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    We utilize the notion of module extension to reduce the problem of stability of derivations to that of ring homomorphisms studied by R. Badora in the context of Banach bimodules over Banach algebras

    A Characterization For 2-Self-Centered Graphs

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    A Graph is called 2-self-centered if its diameter and radius both equal to 2. In this paper, we begin characterizing these graphs by characterizing edge-maximal 2-self-centered graphs via their complements. Then we split characterizing edge-minimal 2-self-centered graphs into two cases. First, we characterize edge-minimal 2-self-centered graphs without triangles by introducing \emph{specialized bi-independent covering (SBIC)} and a structure named \emph{generalized complete bipartite graph (GCBG)}. Then, we complete characterization by characterizing edge-minimal 2-self-centered graphs with some triangles. Hence, the main characterization is done since a graph is 2-self-centered if and only if it is a spanning subgraph of some edge-maximal 2-self-centered graphs and, at the same time, it is a spanning supergraph of some edge-minimal 2-self-centered graphs

    Information technology's impact on productivity in conventional power plants

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    The economy has undergone a profound structural transformation in the last two decades. The Information Technology (IT) revolution has expanded well beyond the cutting-edge high-tech sector redefining the rules of global competition. In general, a direct correlation between IT spending and organisational productivity (often referred to as the 'productivity paradox') has been very elusive. Numerous studies have been undertaken to either explain or dispel this paradox. While findings from earlier studies have been conflicting, recent firm-level studies indicate that IT investment has a positive impact on productivity. Data Envelopment Analysis (DEA) has been widely used to evaluate the comparative efficiencies of production processes. We propose a two-stage DEA model to decompose the IT investment impacts on productivity in the power plant industry. IT plays an important role in the effective and efficient generation of electricity in conventional power plants. The proposed model allows the integration of production performance and investment performance and provides management with a comprehensive performance evaluation system. We also propose a benchmarking model in conjunction with our DEA model to measure performance against the 'best-in-class'. The data from 20 public conventional power plants in Iran are used to illustrate and validate our model

    Localized radiotherapy of solid tumors using radiopharmaceutical loaded implantable system: insights from a mathematical model

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    IntroductionComputational models yield valuable insights into biological interactions not fully elucidated by experimental approaches. This study investigates an innovative spatiotemporal model for simulating the controlled release and dispersion of radiopharmaceutical therapy (RPT) using 177Lu-PSMA, a prostate-specific membrane antigen (PSMA) targeted radiopharmaceutical, within solid tumors via a dual-release implantable delivery system. Local delivery of anticancer agents presents a strategic approach to mitigate adverse effects while optimizing therapeutic outcomes.MethodsThis study evaluates various factors impacting RPT efficacy, including hypoxia region extension, binding affinity, and initial drug dosage, employing a novel 3-dimensional computational model. Analysis gauges the influence of these factors on radiopharmaceutical agent concentration within the tumor microenvironment. Furthermore, spatial and temporal radiopharmaceutical distribution within both the tumor and surrounding tissue is explored.ResultsAnalysis indicates a significantly higher total concentration area under the curve within the tumor region compared to surrounding normal tissue. Moreover, drug distribution exhibits notably superior efficacy compared to the radiation source. Additionally, low microvascular density in extended hypoxia regions enhances drug availability, facilitating improved binding to PSMA receptors and enhancing therapeutic effectiveness. Reductions in the dissociation constant (KD) lead to heightened binding affinity and increased internalized drug concentration. Evaluation of initial radioactivities (7.1×107, 7.1×108, and 7.1×109 [Bq]) indicates that an activity of 7.1×108 [Bq] offers a favorable balance between tumor cell elimination and minimal impact on normal tissues.DiscussionThese findings underscore the potential of localized radiopharmaceutical delivery strategies and emphasize the crucial role of released drugs relative to the radiation source (implant) in effective tumor treatment. Decreasing the proximity of the drug to the microvascular network and enhancing its distribution within the tumor promote a more effective therapeutic outcome. The study furnishes valuable insights for future experimental investigations and clinical trials, aiming to refine medication protocols and minimize reliance on in vivo testing
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