Output reversibility in linear discrete-time dynamical systems

Output reversibility involves dynamical systems where for every initial condition and the corresponding output there exists another initial condition such that the output generated by this initial condition is a time-reversed image of the original output with the time running forward. Through a series of necessary and sufficient conditions, we characterize output reversibility in linear discrete-time dynamical systems in terms of the geometric symmetry of its eigenvalue set with respect to the unit circle in the complex plane. Furthermore, we establish that output reversibility of a linear continuous-time system implies output reversibility of its discretization. In addition, we present a control framework that allows to alter the system dynamics in such a way that a discrete-time system, otherwise not output reversible, can be made output reversible. Finally, we present numerical examples involving a discretization of a Hamiltonian system that exhibits output reversibility and an example of a controlled system that is rendered output reversible.     

Diagnosis,Evaluation, and Treatment of Lead Poisoning in General Population

Among the heavy metals, lead still remains the major toxic pollutant of the environment. Human exposure to lead can occur through numerous pathways including air, food, dust, soil, and water. In the present study 14 lead poisoned patients with non-occupational lead exposure were evaluated. They were followed up and compared against the controls with no history of lead exposure. The patients had high blood lead levels and symptoms of weakness, dizziness, abdominal pain, generalized body ache, loss of appetite, and anxiety. Repeated course of chelation therapy helped to bring down their body burden of lead. Alternative sources for lead exposure can cause severe lead poisoning in general population. Screening and medical management of such individuals is very important to identify and eliminate sources of lead. The treatment and management requires a thorough medical evaluation and environmental intervention.     

Value of ascitic fluid cholesterol and serum-ascites albumin gradient in differentiating cirrhotic and malignancy related ascites

In a perspective study, the ascitic fluid and serum concentration of total cholesterol, total proteins and albumin in a group of 45 patients was studied. Patients with nonmalignant or cirrhotic ascites were compared with patients having malignancy related ascites and it was proved that the ascitic fluid cholesterol and the serum ascites albumin gradient helped to differentiate cirrhotic from malignant ascites. These two parameters showed a remarkable relationship to the presence/absence of malignancy. Non malignant ascites patients had ascitic fluid cholesterol values of 19.41±8.33 mg/dl, as against the malignancy related ascites patients, who showed levels of 95.87±1.24 mg/dl. Similarly, the serum-ascites albumin gradient levels were 2.89±0.65 in non malignant ascites patients, while the malignancy related ascites cases had 0.86±0.50. The discrimination values for cholesterol were taken as 45 mg/dl while that for serum ascites gradient was taken as 1.1. Levels of serum cholesterol, total protein and albumin were not significantly altered.     

Studies on the age dependent changes in serum adenosine deaminase activity and its changes in hepatitis

Serum Adenosine deaminase (ADA) activity in normal healthy control subjects increases upto 30 years, remains steady between 31–60 years of age and shows a steep increase in the age group of 61–70 years. This was compared with serum aspartate transaminase (AST) and alanine transaminase (ALT) activity which also showed a gradual increase upto 40 years of age and decreased thereafter. The activities of serum ADA, AST and ALT increased in patients with hepatitis of all age groups compared to their respective controls. The degree of increase in the activities of the above enzymes in hepatitis, decreased with age. The present study also shows that while studying serum ADA activity in hepatitis for diagnostic purposes, the value obtained in a particular age group should be compared with normal range of values for the respective age group only.     

Teacher opinions on performance pay: Evidence from India

The practical viability of performance-based pay programs for teachers depends critically on the extent of support the idea will receive from teachers. We present evidence on teacher opinions with regard to performance-based pay from teacher interviews conducted in the context of an experimental evaluation of a program that provided performance-based bonuses to teachers in the Indian state of Andhra Pradesh. We report four main findings in this paper: (1) over 80% of teachers had a favorable opinion about the idea of linking a component of pay to measures of performance, (2) exposure to an actual incentive program increased teacher support for the idea, (3) teacher support declines with age, experience, training, and base pay, and (4) the extent of teachers’ stated ex ante support for performance-linked pay (over a series of mean-preserving spreads of pay) is positively correlated with their ex post performance as measured by estimates of teacher value addition. This suggests that teachers are aware of their own effectiveness and that implementing a performance-linked pay program could not only have broad-based support among teachers but also attract more effective teachers into the teaching profession.     

Antioxidants: Basis concepts in relation to the eye

Antioxidants are a small group of substances that protect living cells from the destructive consequences of powerful oxidizing intermediates that can be formed from oxygen. Situations in which pro-oxidant mechanisms within the body are more active than the antioxidant mechanisms (oxidative stress) predispose and contribute to the pathogenesis of several ailments in various organs of the body. In the eye, pro-oxidant factors have been blamed for the causation of diseases such as age related macular degeneration and senile cataract. The role of pro-oxidants in the genesis of certain diseases is well established however, the effectivity of antioxidants provided to the body by dietary supplementation is inconclusive. In this article we provide a review on the basic concepts of antioxidant-pro-oxidant interaction in relation to its effects on the eye.     

A cognitive-motivational model of decision satisfaction

Satisfaction is a condition that contributes to the development of intrinsic motivation and a continuing motivation to learn. Research that helps to identify the factors that contribute to learning satisfaction is useful for educators. This paper introduces the Cognitive-Motivational Model of Decision Satisfaction, a model that extends Kruglanski's work on closure and builds on Keller's work on the motivational aspects of instruction and learning. Focusing on decision-making activities in a learning context, this model recognizes the importance of information-processing in judgmental tasks and specifies confidence as a major contributing factor to learning satisfaction. Some potential applications to both classroom and computer-based learning environments are suggested.     

Biochemical studies to confirm a missed case of multiple myeloma in a seventy year old male

Routine investigations of a 70 year old male led to provisional diagnosis of anemia. However further investigations suggested the possibilities of carcinoma of stomach associated with pernicious anemia, multiple myeloma and megaloblastic anemia. Finally serum protein electrophoresis supported by the clinical suspicion confirmed multiple myeloma.