Questions concerning matrix algebras and invariance of spectrum

Let $A$ and $B$ be unital Banach algebras with $A$ a subalgebra of $B$. Denote the algebra of all $n\times n$ matrices with entries from $A$ by $M_{n}(A)$. In this paper we prove some results concerning the open question: If $A$ is inverse closed in $B$, then is $M_{n}(A)$ inverse closed in $M_{n}(B)$? We also study related questions in the setting where $A$ is a symmetric Banach *-algebra.Comment: 6 pages, no figures, no table

Syndication and Bargaining With a Monopolist

This dissertation consists of three related game-theoretic essays on bargaining. The first essay develops a model of monopolistic economies in which total profit is determined by the set of traders that cooperate with the monopolist. The traders each bargain bilaterally with the monopolist for their profits and each bargaining outcome is determined by some bargaining solution. For any set of continuous bargaining solutions, there exists a general bargaining equilibrium, which is a profit distribution that is the fixed point of a system of bilateral bargaining outcome functions. The second essay defines the class of strongly power sensitive bargaining solutions, which includes all bargaining solutions that are strongly individually rational and either independent of irrelevant alternatives or individually monotonic. Measures of bargaining power are introduced for generalized Nash bargaining solutions and generalized monotonic bargaining solutions. The final essay analyzes the effects of syndication among traders bargaining with a monopolist with respect to the general bargaining equilibria associated with risk sensitive bargaining solutions and strongly power sensitive bargaining solutions. If the monopolist is risk neutral, the effects of syndication depend on the profit function: syndication is neutral if the profit function is additive for the set of traders, advantageous if it is submodular, and disadvantageous if it is supermodular. A strictly risk averse monopolist creates opportunities for advantageous syndication among the traders. If the monopolist is strictly risk averse and the profit function is additive, then traders in larger syndicates receive greater profits, and syndicate merger is advantageous. The traders can maximize their profits by forming a single monopolistic syndicate. This confirms the conventional wisdom that traders faced with a monopolist should syndicate to form a bilateral monopoly. In bargaining with a strictly risk averse opponent, size alone creates bargaining power. In the absence of any cost considerations, a strictly risk averse opponent may grant a larger player more favorable terms in bargaining. This may provide an explanation of volume discounts in the absence of price discrimination, economies of scale or transaction costs

Student Perceptions of Effective Foreign Language Teachers: A Quantitative Investigation from a Korean University

Abstract: The present study uses a questionnaire instrument to measure the importance that students from a Korean university place on a wide range of effective foreign language teacher attributes. Respondents to the present study placed high importance on rapport attributes such as friendliness, care, and patience; and delivery attributes which included the provision of clear explanations, error correction, and a participatory mode of instruction. Impartiality, target language knowledge, and good preparation were attributes also rated highly. The results also provided insights into student opinions about various instructional issues, such as the selective use of the students’ first language, explicit grammar instruction, and particular questioning techniques. This knowledge can be used by foreign language teachers and student teachers to improve the efficacy of their instruction

The Attributes of Effective Lecturers of English as a Foreign Language as Perceived by Students in a Korean University

This study, conducted in a Korean university setting, examines student beliefs about the attributes of effective lecturers[1] of English as a foreign language. Student opinions about rapport and delivery type attributes are particularly informative. Rapport attributes were the major focus of discussion and viewed as particularly important in Korean university contexts where student anxiety about interacting in English often inhibits effective English language learning. Discussion about delivery attributes was generally supportive of participatory modes of instruction, but contained different views about how aggressively lecturers should enlist participation. The beliefs of Korean university students revealed in this study can, if seen as appropriate, be used by existing practitioners and teachers in training to guide instructional approache

Proposed Schematics for an Advanced Development Lunar Portable Life Support System

The latest development of the NASA space suit is an integrated assembly made up of primarily a Pressure Garment System (PGS) and a Portable Life Support System (PLSS). The PLSS is further composed of an oxygen (O2) subsystem, a ventilation subsystem, and a thermal subsystem. This paper baselines a detailed schematic of the PLSS to provide a basis for current and future PLSS development efforts. Both context diagrams and detailed schematics describe the hardware components and overall functions for all three of the PLSS subsystems. The various modes of operations for the PLSS are also presented. A comparison of the proposed PLSS to the Apollo and Shuttle PLSS designs is presented, highlighting several anticipated improvements over the historical PLSS architectures

Organizational Adoption of Blockchain Technology: An Ecosystem Perspective

Organizations of all sizes are developing blockchain projects in hopes of reaping benefits from this technology. Despite rising academic interest in blockchain technology, extant research has primarily focused on technical or design challenges and improvements, with scant scholarly attention being paid to factors contributing to the adoption of blockchain technologies by organizations, which presents an opportunity for us to undertake this theory guided empirical investigation. Drawing on the Technological-Organizational-Environmental (TOE) framework and extending the framework by considering the network of actors comprising an enterprise blockchain ecosystem, we identify a set of factors most applicable to blockchain adoption and developed a research model that examines how different technological (i.e., perceived usefulness, compatibility, relative advantage, complexity, and scope of technology), organizational (i.e., top management support, organizational readiness, firm size, and firm centralization), and environmental ecosystem actors (i.e., business competition, trading partner support, technology vendor support, governmental support, and customer support) influence organizational adoption of blockchain technology. We also propose a cross-industry field survey to test our hypotheses

Magic Numbers for the Photoelectron Anisotropy in Li-Doped Dimethyl Ether Clusters

Photoelectron velocity map imaging of Li(CH$_3$OCH$_3$)$_n$ clusters (1 $\leq$ n $\leq$ 175) is used to search for magic numbers related to the photoelectron anisotropy. Comparison with density functional calculations reveals magic numbers at n=4, 5, and 6, resulting from the symmetric charge distribution with high s-character of the highest occupied molecular orbital. Since each of these three cluster sizes correspond to the completion of a first coordination shell, they can be considered as 'isomeric motifs of the first coordination shell'. Differences in the photoelectron anisotropy, the vertical ionization energies and the enthalpies of vaporization between Li(CH$_3$OCH$_3$)$_n$ and Na(CH$_3$OCH$_3$)$_n$ can be rationalized in terms of differences in their solvation shells, atomic ionization energies, polarizabilities, metal-oxygen bonds, ligand-ligand interactions, and by cooperative effects