Mathematical Aspects of the Periodic Law

We review different studies of the Periodic Law and the set of chemical elements from a mathematical point of view. This discussion covers the first attempts made in the 19th century up to the present day. Mathematics employed to study the periodic system includes number theory, information theory, order theory, set theory and topology. Each theory used shows that it is possible to provide the Periodic Law with a mathematical structure. We also show that it is possible to study the chemical elements taking advantage of their phenomenological properties, and that it is not always necessary to reduce the concept of chemical elements to the quantum atomic concept to be able to find interpretations for the Periodic Law. Finally, a connection is noted between the lengths of the periods of the Periodic Law and the philosophical Pythagorean doctrine.Comment: 20 pages, PDF fil

Experience With The Intelligent Hybrid Arm Systems

Microprocessors are increasingly used in prosthetic applications. The flexibility they provide allows new functions to be added easily, and fitting and maintenance can be simplified [1,2,3]. Prosthetic controllers are available that can be adapted to different needs through field programming, allowing the prosthetist to try different control strategies or even invent completely new ones. The process of setting up the prosthesis is made easier through the use of graphical software programming tools [4]. However, there remains a need for interoperability standards so that complete prostheses can be built up from modular components that are compatible in software terms as well as mechanically and electrically

A prospective study of basal insulin concentrations in dogs with congenital portosystemic shunts

Objectives: Hypoglycaemia is a common cause of morbidity in dogs with congenital portosystemic shunts but the aetiology is unknown. The hypothesis of this study was that dogs with congenital portosystemic shunts would have significantly higher insulin concentrations than dogs without congenital portosystemic shunts. The main objective of the study was to compare peripheral glucose and insulin concentrations between dogs with congenital portosystemic shunts and dogs without congenital portosystemic shunts. Methods: Peripheral serum insulin and plasma glucose concentrations were measured in dogs with congenital portosystemic shunts and without congenital portosystemic shunts and compared both between groups as well as to reference intervals derived from healthy dogs. Results: Congenital portosystemic shunts were diagnosed in 41 dogs. Forty-eight dogs hospitalised with other conditions acted as controls. Serum insulin concentrations were mildly elevated (Ä40 μU/mL) in seven dogs and were markedly elevated in two dogs with congenital portosystemic shunts, yet mild hypoglycaemia (3·3 mmol/L) was detected in only one of these dogs. Four dogs with congenital portosystemic shunts showed fasting hypoglycaemia, yet insulin concentrations were within or below the reference interval in three. There was no difference between the median insulin concentration of dogs with congenital portosystemic shunts and without congenital portosystemic shunts. Clinical Significance: Hyperinsulinaemia is infrequently observed in dogs with congenital portosystemic shunts. The aetiology of hypoglycaemia in dogs with congenital portosystemic shunts merits further investigation

Sudden cardiac death following liver transplantation: incidence, trends and risk predictors

Background: Cardiovascular events are a leading cause of mortality following liver transplantation (LT). Although a preponderance of sudden cardiac death (SCD) in this population has been reported, there is a paucity of data evaluating the incidence, timing and predictors of SCD following LT. Methods: Using the prospectively collected Australian and New Zealand Liver Transplant Registry, a cohort study of all adult LTs from 1985 to 2017 was performed to ascertain the incidence and predictors of SCD. Recipient cause of death was adjudicated by an interdisciplinary panel. Results: 4265 LT patients were followed-up for 37,409 person-years. SCD was the leading mode of cardiovascular death with an incidence rate of 165 per 100,000 person-years. There was a significant increase in the hazard of SCD in the contemporary (1996–2017) vs early era (1985–1995) (hazard ratio [HR] 2.42, 95%CI 1.10–5.40; p = 0.02). On Cox regression after adjusting for significant univariate predictors including age, coronary artery disease and non-alcoholic steatohepatitis, pre-transplant diabetes was the only independent predictor of SCD (HR 2.5 95%CI 1.1–6.0). Conclusion: SCD is the leading mode of cardiovascular cause-specific mortality following LT and diabetes was associated with a two-fold higher risk for its occurrence. Given the escalating cardiovascular risk factor profile of LT candidates, targeted therapies especially in patients with diabetes are needed to mitigate risk of post-transplant SCD.Anoop N. Koshy, Paul J. Gow, Hui-Chen Han, Andrew W. Teh, Han S. Lim, Adam Testro, Robert Jones, Omar Farouqu

High circulating oestrone and low testosterone correlate with adverse clinical outcomes in men with advanced liver disease

Background & Aims: Circulating testosterone is usually reduced in men with cirrhosis, but there has not been a comprehensive analysis of androgen status or circulating oestrogens. Little is known about associations between circulating sex steroids with aspects of health in this population. Methods: We report data from men with cirrhosis and low serum testosterone (<12 nmol/L or calculated free testosterone <230 pmol/L). Comprehensive circulating sex steroid profiles were measured by liquid chromatography-mass spectrometry and compared with age-matched controls. Relationships between sex hormone levels, severity of liver disease, biochemistry and clinical outcomes were assessed. Results: Serum oestrone and oestradiol were significantly elevated in men with cirrhosis compared with controls (median, 869.1 pmol/L vs. 133.8 pmol/L and 166.7 pmol/L vs. 84.6 pmol/L respectively). Serum oestrone correlated with MELD score (correlation +0.306, P < 0.001) and inversely correlated with serum sodium (correlation -0.208, P = 0.004) and haemoglobin (correlation -0.177, P = 0.012). No such correlations were observed for oestradiol. Serum testosterone levels inversely correlated with MELD score (correlation -0.294, P < 0.001) and positively with handgrip strength (correlation +0.242, P < 0.001), physical activity (correlation +0.276, P = 0.012), haemoglobin (correlation +0.282, P < 0.001) and serum sodium (+0.344, P < 0.001). Dihydrotestosterone inversely correlated with MELD score (correlation -0.225, P = 0.002) and shared similar significant relationships to testosterone. Conclusion: Low serum androgens and elevated serum oestrone (but not oestradiol) are associated with higher MELD and individual adverse health outcomes in cirrhotic cohort of men selected for low testosterone. Serum oestrone may be a novel marker of ill health in this population. Whether low androgens are markers or mediators of ill health requires further investigation.Marie Sinclair, Paul J. Gow, Peter W. Angus, Rudolf Hoermann, David J. Handelsman, Gary Wittert, Sean Martin and Mathis Grossman