Experimental investigation of feedforward control schemes of a flexible robot manipulator system

This paper presents experimental investigations into the applications of feedforward control schemes for vibration control of a flexible manipulator system. Feedforward control schemes based on input shaping and filtering techniques are to be examined. A constrained planar single-link flexible manipulator is considered in this experimental work. An unshaped bang-bang torque input is used to determine the characteristic parameters of the system for design and evaluation of the input shaping control techniques. The input shapers and filtering techniques are designed based on the properties of the system. Simulation results of the response of the manipulator to the shaped and filtered inputs are presented in time and frequency domains. Performances of the shapers are examined in terms of level of vibration reduction and time response specifications. The effects of derivative order of the input shaper on the performance of the system are investigated. Finally, a comparative assessment of the control strategies is presented and discusse

MONETARY POLICY EFFECTIVENESS & YIELD CURVE DYNAMICS – US EXPERIENCE FROM AHETEREGENEOUS ECONOMIC PERSPECTIVE (2000-2009)

The question of how do the monetary policy translate across the yield curve remain at the forefront of many recent policy debates. The monetary policy targets the very short end of the yield curve although real economic activity is largely dependent upon the medium to long- term market interest rates. Conventional wisdom agree that given efficient market conditions decrease in the monetary policy target rate leads to an immediate decrease in market interest rates, and an increase in bond prices; yet evidence for this view is elusive. Bringing the foundations of Expectation Hypothesis (EH) and empirical analysis of US money market and government bond daily yield rates for the period 2000 to 2009 explains that monetary policy impact monotonically decreases over the yield curve. The impact appears to be waning at a faster pace and concentrate on a preferred habitat towards shorter end at times of financial and economic uncertainties compared against stable economic period. This invites policy attention, especially at times of economic uncertainty, on the part of monetary policy effectiveness and market confidence in US to resurrect economic activities.Monetary policy; Expectation hypothesis; Segmented market hypothesis; Preferred habitat hypothesis; Yield curve and term structure of interest rates

Hybrid iterative learning control of a flexible manipulator

This paper presents an investigation into the development of a hybrid control scheme with iterative learning for input tracking and end-point vibration suppression of a flexible manipulator system. The dynamic model of the system is derived using the finite element method. Initially, a collocated proportional-derivative (PD) controller using hub angle and hub velocity feedback is developed for control of rigid-body motion of the system. This is then extended to incorporate a non-collocated proportional-integral-derivative (PID) controller with iterative learning for control of vibration of the system. Simulation results of the response of the manipulator with the controllers are presented in the time and frequency domains. The performance of the hybrid iterative learning control scheme is assessed in terms of input tracking and level of vibration reduction in comparison to a conventionally designed PD-PID control scheme. The effectiveness of the control scheme in handling various payloads is also studied

Role of ABCB1 C3435T variant in response to antiepileptic drugs in epilepsy: a review

Over-expression of P-glycoprotein (P-gp), the encoded product of the ATP-binding cassette (ABC), sub-family B, member 1 (ABCB1/MDR1) gene, plays an important role in mediating multidrug resistance to antiepileptic drugs (AEDs) in about 30% of patients with epilepsy. Genetic variation may in part explain inter-individual differences in phenotype-genotype relationships in the pharmacological response of epilepsy patients to AEDs. The synonymous C3435T polymorphism is one of the most common allelic variants in the ABCB1/MDR1 gene, proposed in the causation of refractory epilepsy. Many studies have shown the relationship between C3435T polymorphism and refractoriness to AEDs in epilepsy. However, there is controversy between the findings of various studies, that is, whether ABCB1/MDR1 C3435T gene polymorphism is associated with response to AEDs in epilepsy patients. This review provides a background and discusses the results of investigations on possible confounding factors affecting the interpretation and implementation of association studies in this area

Comparison of drug release from liquid crystalline monoolein dispersions and solid lipid nanoparticles using a flow cytometric technique

AbstractColloidal lipid particles such as solid lipid nanoparticles and liquid crystalline nanoparticles have great opportunities as drug carriers especially for lipophilic drugs intended for intravenous administration. In order to evaluate drug release from these nanoparticles and determine their behavior after administration, emulsion droplets were used as a lipophilic compartment to which the transfer of a model drug was measured. The detection of the model drug transferred from monoolein cubic particles and trimyristin solid lipid nanoparticles into emulsion droplets was performed using a flow cytometric technique. A higher rate and amount of porphyrin transfer from the solid lipid nanoparticles compared to the monoolein cubic particles was observed. This difference might be attributed to the formation of a highly ordered particle which leads to the expulsion of drug to the surface of the crystalline particle. Furthermore, the sponge-like structure of the monoolein cubic particles decreases the rate and amount of drug transferred. In conclusion, the flow cytometric technique is a suitable technique to study drug transfer from these carriers to large lipophilic acceptors. Monoolein cubic particles with their unique structure can be used successfully as a drug carrier with slow drug release compared with trimyristin nanoparticles

Perceptions of mental illness among Muslim general practitioners in South Africa

KMBackground: Mental health literacy on the part of medical practitioners is an important component of mental healthcare. General practitioners (GPs) are typically the first doctors consulted by a person who is ill. Exploration of their perceptions regarding mental illness, aetiological issues and treatment is important. Objective: To investigate perceptions of mental illness in a sample of ten South African Muslim GPs (five male, five female) in the Lenasia area (Johannesburg, South Africa). Methods: Using a qualitative approach, semi-structured interviews were conducted with each GP. The questionnaire encompassed 37 questions relating to the context in which the GPs practised, perceptions of mental illness, understanding of religion and culture, and treatment of mental illness (including aspects of spiritual illness). Thematic content analysis was used to analyse the data. Results: Six dominant themes were identified, namely GPs' understanding of mental illness and its causation; stigma, secrecy and somatisation; the beneficial effects of religion in mental illnesses; perceptions of spiritual illnesses; collaboration with traditional healers; and collaboration with psychiatrists and psychologists. Conclusion: Greater awareness regarding the stigmatisation of mental illness is needed. Furthermore, it is important that healthcare professionals have an understanding of religious and cultural taxonomies of illness as well as the use of traditional healing as a mode of treatment. Participants identified a need for increased collaboration between healthcare professionals, including traditional healers