Directional flow of solitons with asymmetric potential wells: Soliton diode

We study the flow of bright solitons through two asymmetric potential wells. The scattering of a soliton by certain type of single potential wells, e.g., Gaussian or Rosen-Morse, is distinguished by a critical velocity above which solitons can transmit almost completely and below which solitons can reflect nearly perfectly. For two such wells in series with certain parameter combinations, we find that there is an appreciable velocity range for which solitons can propagate in one direction only. Our study shows that this directional propagation or diode behavior is due to a combined effect of the sharp transition in the transport coefficients at the critical velocity and a slight reduction in the center-of-mass speed of the soliton while it travels across a potential well.Comment: 7 pages, 5 figure

Exchange Rate Misalignment in Pakistan: Evidence from Purchasing Power Parity Theory

This paper examines the validity of the purchasing power parity to evaluate whether the Pakrupee vis-à-vis the US-dollar has been overvalued since the introduction of managed floating exchange rate. The Johansen multivariate cointegration technique is applied for the period 1982Q2-2002Q4. A single cointegrating vector is identified whose coefficients conform in broad terms to the restriction implied by the PPP theory, lending support to the interpretation of the model as describing a long-run relationship. This support is reinforced by the results derived from the adjustment coefficient, which is identifies clear short-run tendency for the exchange rate to revert to the equilibrium value defined by the estimated long-run model. Furthermore, exchange rate misalignment is also calculated using the estimated long-run relationship to evaluate whether the Pak-rupee vis-à-vis the US-dollar was undervalued or overvalued since the inception of managed floating exchange rate system. Calculated misalignment shows a substantial undervaluation of the Pak-rupee vis-à-vis the US dollar.Exchange Rate, Pakistan

Obesity and high risk pathological features of papillary thyroid carcinoma: A retrospective analysis of a university hospital in Pakistan

BACKGROUND: Incidence of papillary thyroid carcinoma (PTC) and the frequency of obesity is increasing globally. In literature, relationship between excessive body weight and bad prognostic features of PTC is still debatable. In this study, we aimed to explore the association of obesity with high risk pathological features of PTC in a population treated by total thyroidectomy +/- neck dissection. MATERIALS AND METHODS: Retrospective analysis of patients at Aga Khan University Hospital from January 2013 to December 2014, who underwent total thyroidectomy +/- neck dissection due to PTC. Patients were grouped according to World Health Organization (WHO) classification of BMI. They were categorized into two groups, i.e. normal (BMI= 18.5 - 24.9 kg/m2) and obese (BMI = 30 kg/m2) as none of our patients lie in underweight and overweight category. Pathological features i.e. T-stage, multifocality, bilaterality, extrathyroidal extension, vascular invasion and N-stage were assessed. All tumors were staged according to TNM staging system proposed by 2010 American Joint Committee on Cancer (AJCC). Odds ratio (OR) with 95% confidence interval was used to examine the association between BMI ∧ pathological characteristics of PTC. RESULTS: A total of 53 patients were treated for PTC in two-years period. There were 38 female and 15 male patients. Twenty-eight patients had BMI in normal while twenty-five in obese category. Patients who were in obese category had a significantly greater risk of having a multifocal tumor (OR=5.55, p-value=0.02) and bilaterality (OR=6.54, p-value=0.01) compared to normal weight patients. No positive associations were identified between BMI and extrathyroidal extension, high T-stage, vascular invasion and N-stage. CONCLUSION: Obesity is not associated with high risk pathological features such as extrathyroidal extention, high T-stage, vascular invasion and N-stage in PTC. Although it has been correlated with multifocal and bilateral tumors in this retrospective study, the presence of these factors alone is not adequate to support the association conclusively

Exchange Rate Misalignment in Pakistan: Evidence from Purchasing Power Parity Theory

Exchange rate provides a key link between the domestic and world markets for goods and assets. Therefore, a proper and detailed analysis of the behaviour of exchange rate is required. There is also growing agreement that prolonged and substantial exchange rate misalignment can create severe macroeconomic disequilibria and the correction of external balance will require both exchange rate devaluation and demand management policies. Thus the policy-makers have used PPP theory as a guide to represent the external competitiveness of a country, and as a benchmark against which floating exchange rates are judged to be misaligned. Developments in 1990s and 2000s show that cost associated with exchange rate misalignment is very high. Hence, the analysis of exchange rate determination in the presence of exchange rate misalignment is crucial for the policy purpose because of its role as a component of an early warning system [Berg, et al. (2000)]

PID Controller Tuning Optimization with Genetic Algorithms for a Quadcopter

This paper is focused on the dynamic of mathematical modeling, stability, nonlinear gain control by using Genetic algorithm, utilizing MATLAB tool of a quadcopter. Previously many researchers have been work on several linear controllers such as LQ method; sliding mode and classical PID are used to stabilize the Linear Model. Quadcopter has a nonlinear dynamics and unstable system. In order to maintain their stability, we use nonlinear gain controllers; classical PID controller provides linear gain controller rather than nonlinear gain controller; here we are using modified PID control to improve stability and accuracy. The stability is the state of being resistant to any change. The task is to maintain the quadcopter stability by improving the performance of a PID controller in term of time domain specification. The goal of PID controller design is to determine a set of gains: Kp, Ki, and Kd, so as to improve the transient response and steady state response of a system as: by reducing the overshoot; by shortening the settling time; by decrease the rise time of the system. Modified PID is the combination of classical PID in addition to Genetic Algorithm. Genetic algorithm consists of three steps: selection, crossover, and mutation. By using Genetic algorithm we correct the behavior of quadcopter

Self-Navigation Car using Reinforcement Learning

In this paper, a project is described which is a 2-D modelled version of a car that will learn how to drive itself. It will have to figure everything out on its own. In addition, to achieve that the simulator contains a car running simultaneously &can be controlled by different control algorithms - heuristic, reinforcement learning-based, etc. For each dynamic input, the Reinforcement- Learning modifies new patterns. Ultimately, Reinforcement Learning helps in maximizing the reward from every state. In this first Part, we will implement a Reinforcement-Learning model to build an AI for Self Driving Car. Project will be focusing on the brain of the car not any graphics. The car will detect obstacles and take basic actions. To make autonomous car or self-driving car a reality, some of the factors to be considered are human safety and quality of life

268 composition in experimental diabetes

269 alba, Nigella sativa and Trigonella foenum graecum which show the inhibitory effect of glucose utilization, and are in use as hypoglycemic agents of varying degree in traditional system of medicine. The glucose uptake activity of (methanolic extracts) of these plants was tested in vitro and glucose was estimated by glucose oxidase method. The results in three different media revealed that, hypoglycemic activity is more prominent in neutral and basic media as compared to acidic medium