Expressing the Behavior of Three Very Different Concurrent Systems by Using Natural Extensions of Separation Logic

Separation Logic is a non-classical logic used to verify pointer-intensive code. In this paper, however, we show that Separation Logic, along with its natural extensions, can also be used as a specification language for concurrent-system design. To do so, we express the behavior of three very different concurrent systems: a Subway, a Stopwatch, and a 2x2 Switch. The Subway is originally implemented in LUSTRE, the Stopwatch in Esterel, and the 2x2 Switch in Bluespec

National Hockey League guaranteed contracts: A principal agent problem impacting on performance

Purpose – This paper aims to investigate, through the lens of the principal–agent problem, the relationship between payment of National Hockey League (NHL) salaries and player performance during the period of 2005-2011 and explore the inherent issues within the NHL player compensation and incentive structure. Design/methodology/approach – The research adopts a pragmatic philosophy with deductive reasoning. This paper focuses on the NHL season 2005-2011 and undertake analysis of historical player contracts and performance data of 670 players across 29 clubs to undertake liner regression analysis. Findings – This paper quantifies potential inefficiencies of NHL league contracts and defines the parameters of the principal–agent problem. It is identifies that player performance generally increases with salary, is higher in the first year of a contract and despite decreasing over the life of the contract, will usually peak again in the final year of the contract. Research limitations/implications – The research is based around figures from 2005-2011 and secondary statistical data. The study captures quantitative data but does not allow for an exploration of the qualitative perspective to the problem. Practical implications – Entry-level or first contracts are good for all teams and players because they provide incentive to perform and a reduction of risk to the team should a player not perform to expectations. The same can be said for players at the other end of the spectrum. Although not typically used much, performance bonuses for players over the age of 35 allow clubs to “take a chance” on a player and the player can benefit by reaching attainable bonuses. These findings therefore provide contributions to the practicing managers and coaches of NHL teams who can consider the results to help shape their approach to management of players and the planning of teams and succession planning for talent. Originality/value – The paper presents a comprehensive and current perspective of the principal–agent problem in NHL and extends the work of Purcell (2009) and Gannon (2009) in understanding player performance enhancement

Pituitary-adrenal axis in Prader Willi syndrome

Purpose: Prader Willi syndrome (PWS) is a rare genetic condition that has concurrent endocrinological insufficiencies. The presence of growth hormone deficiency has been well documented, but adrenal insufficiency (AI) is not widely reported. A review was conducted to investigate its prevalence and relevance in PWS in both adults and children. Methodology: A literature review was performed with the search terms “Prader-Willi syndrome” and “adrenal insufficiency”. Results: The review found studies disagree on the prevalence and method of investigation of AI in PWS. Case studies demonstrate that patients with PWS are at risk of premature death, often secondary to respiratory infections. The possibility that this may be the result of the inability to mount an effective cortisol response has been studied, with some evidence confirming AI in PWS patients. Most reports agreed AI is present in PWS, however, Farholt et al. showed no HPA axis dysfunction in adults, suggesting that perhaps it is rare in adults, and children should be the focus of further studies. Conclusion: AI is present in some patients with PWS. Further research is required to ensure optimal treatment can be implemented and to prevent premature deaths related to adrenal insufficiency. Clinicians should have a low threshold for testing the adrenal axis and considering treatment for adrenal insufficiency in PWS patients

The use of isotopic carbon in a study of the metabolism of anthanilic acid in Neurospora

The finding by Tatum, Banner, and Beadle (l), that the tryptophanless Neurospora mutant strain 10575 accumulates anthranilic acid, which in turn can be utilized for growth of strain 40008, has provided evidence that anthranilic acid is a biochemical precursor of tryptophan in this organism. It has been further established that indole is an intermediate in this conversion (2-5). More recent work with a number of mutants of Neurospora (6-8) has established that tryptophan is a biochemical precursor to niacin with kynurenine and hydroxyanthranilic acid as intermediates. The accumulated evidence has indicated the existence in the mold of the following series of reactions: → Anthranilic acid → indole → tryptophan → kynurenine → 3-hydroxyanthranilic acid → nicotinic acid In the light of this evidence the present work was undertaken to trace the carbon in the carboxyl group of anthranilic acid in order to estimate its contribution as a structural unit in the formation of niacin and tryptophan. The organism chosen for this investigation was a biochemical mutant strain of Neurospora designated as strain 40008. This mutant utilizes anthranilic acid, indole, or tryptophan for growth. The mutant was grown in the presence of anthranilic acid containing Cl4 in the carboxyl group. Niacin and tryptophan were isolated from the mold mycelium and tested for radioactivity

Attractors of directed graph IFSs that are not standard IFS attractors and their Hausdorff measure

For directed graph iterated function systems (IFSs) defined on R, we prove that a class of 2-vertex directed graph IFSs have attractors that cannot be the attractors of standard (1-vertex directed graph) IFSs, with or without separation conditions. We also calculate their exact Hausdorff measure. Thus we are able to identify a new class of attractors for which the exact Hausdorff measure is known