Vogt-koyanagi-harada syndrome

ABSTRACT Vogt-Koyanagi-Harada (VKH) syndrome is a rare multisystem disease of melanocyte containing organs. It is characterized by diffuse granulomatous inflammation involving various organs including eye. VKH syndrome is usually sporadic, but some familial cases have also been reported indicating a hereditary basis. VKH is not associated with mortality but it may result in long-term complications such as decreased vision associated with cataract, glaucoma and choroidal neovascularization. For successful outcomes, early aggressive treatment using systemic steroids with gradual tapering is essential. This report describes a case of VKH syndrome in a 26-year-old male of Pakistan origin who was successfully treated with systemic steroids. The case is briefly contextualised within wider literatur

Sinteza H-beskonačno regulatora s unaprijednom granom za kompenzaciju histereze kod piezoelektričnih aktuatora

Piezoelectric actuators, widely used in different micro/nanopositioning applications, generally exhibit nonlinear hysteresis characteristics. The compensation of hysteretic behavior of piezoelectric actuators is mandatory for precise micro/nanopositioning. In this paper, nonlinear hysteresis effect is first characterized using the Prandtl-Ishlinskii hysteresis model. The inverse of the Prandtl-Ishlinskii hysteresis model is employed as a feed-forward controller to compensate for hysteresis nonlinearities of the piezoelectric actuator. Slight hysteresis nonlinearity is still observed in the experimental results due to small mismatch between the identified hysteresis model and the measured hysteresis loop. To further enhance the performance of the piezoelectric actuator in terms of mitigation of hysteresis nonlinearity and precise reference tracking, advanced robust full-order as well as fixed-order H-infinity feedback controllers are designed and applied to this actuator in the presence of feed-forward compensator. The experimental results verify the effectiveness of the proposed control scheme in achieving the improved tracking performance with peak-to-peak tracking error of less than 1% for the desired displacement of 12 um with tracking frequency of 10 Hz.Piezoelektrični aktuatori, rasprostranjeni u različitim primjenama mikro/nanopozicioniranja, općenito su izloženi nelinearnim histereznim karakteristikama. Kompenzacija histereznog ponašanja piezoelektričnih aktuatora nužna je za precizno mikro/nanopozicioniranje. Inverzni Prandtl-Ishlinskii histerezni model korišten je za unaprijednu kompenzaciju histereznih nelinearnosti piezoelektričnog aktuatora. Neznatna histerezna nelinearnost još uvijek je vidljiva u eksperimentalnim rezultatima zbog malog neslaganja između identificiranog histereznog modela i mjerene histerezne petlje. Za daljnje poboljšanje performansi piezoelektričnog aktuatora u smislu smanjenja histerezne nelinearnosti i preciznog slijeđenja reference, napredni robusni H-beskonačno regulatori punog i određenog reda sintetizirani su i primijenjeni na ovaj aktuator uz prisutnost unaprijednog kompenzatora. Eksperimentalni rezultati potvrđuju efektivnost predložene upravljačke strukture u postizanju poboljšanih performansi slijeđenja, uz vršnu vrijednost pogreške manju od 1% za ciljani pomak od 12 um s frekvencijom slijeđenja od 10 Hz

Investigation of the effect of tool materials and process parameters on dry drilling of Ti-6Al-4V Alloy

The performance of un-coated and TiAlN-coated carbide tools were investigated when dry drilling Ti-6Al-4V alloy. The investigation had been performed in order to find the best tool material performance when dry drilling Ti-6Al-4V. The effect of spindle speed and feed rate on thrust force, torque, dimensional tolerance, and surface roughness were reported. Response surface methodology (RSM) based on central composite design (CCD) is used to perform the investigation. In addition, RSM based on CCD integrated with desirability function is used to determine the optimum input conditions that produce the most desirable quality characteristics (minimum tolerance and surface roughness) with good productivity. Analysis of variance (ANOVA) is used to detect the relative significance of the input factors on each response

Investigation of the performance of an automatic arterial oxygen controller

Premature infants often require respiratory support with a varying concentration of the fraction of inspired oxygen (FiO2) to keep the arterial oxygen saturation (SpO2) within the desired range to avoid both hypoxemia and hyperoxemia. Currently, manual adjustment of FiO2 is the common practice in neonatal intensive care units (NICUs). The automation of this adjustment is a topic of interest. The research team, at University of Missouri-Columbia (UMC), has developed a novel automatic arterial oxygen saturation controller. In this study, a systematic approach has been developed to investigate both non-clinical and clinical performance of this device. The non-clinical investigation of the performance was performed using a neonatal respiratory model (hardware-in-the-loop test). A factorial experimental design was utilized to generate challenging model responses of SpO2, which were addressed by the controllers. With this study, we demonstrate the stability and ability of the adaptive PI-controller to improve oxygen saturation control over manual control by increasing the proportion of time where SpO2 of the neonatal respiratory model was within the desired range and by minimizing the variability of the SpO2. In addition, the controller ability to significantly reduce the number of hypoxemic events of the neonatal respiratory model was reported. Results of this investigation show the competence of the controller estimation system for estimating neonatal respiratory model parameters while the adaptive PI-controller was in use. Also, the functionality of the controller with no mechanical or communication failure was validated non-clinically before heading forward to the clinical trial. The clinical investigation of the performance was performed by conducting a clinical trial at the NICU of the MU Women's and Children's Hospital. The crossover design was used for the clinical trial to allow within-subject comparison and to eliminate interpatient variability. Two human subjects, with two different target ranges of SpO2, were enrolled in the study. The adaptive automatic PI-controller shows clinical feasibility to improve the maintenance of SpO2 within the intended range. With this study, we demonstrate the potential of the automatic controller to minimize the variability of SpO2. In addition, the controller shows the ability to reduce the bradycardia and the hypoxemia. Moreover, the hardware and software of the controller show an ability to transition from manual to automatic mode, and vice versa with no pronounced “bump” or step variation in the control signal, and stability and performance were not adversely affected during the transitions.Includes bibliographical reference

Exchange-rate risk and exports: evidence from a set of transition economies

This article investigates the hypothesis that exchange-rate risk may have an effect on exports for a set of transition countries, namely, Belarus, Kazakhstan, Russia, and Ukraine. To assess this effect, although a two-step estimation approach has earned an extensive empirical record in the literature, a number of studies in this context do not appear to support this approach due to a potential generated regressor issue. This dissonance in a two-step estimation procedure seems to have been somewhat resolved by a relatively new branch of empirical approach that exploits a multivariate version of generalized autoregressive conditional heteroskedasticity in-mean models. The findings suggest that the effect of exchange-rate risk seems to be detrimental in Belarus and Ukraine. However, for Russia and Kazakhstan, which are heavily dependent on crude oil exports, the effect has been found to be indeterminate

The Impact of Expert Systems on AIS - Characteristics and Productivity Work Life Cycle: A Study Targeting Jordan Large Market Organizations

The computer science new emerged technology on AIS researches should explore the application of AIS on the commercial development in terms of availability and characteristics, in addition to productivity and life cycle. The AIS researches are concerning not only into computer science and accounting, but also in organizations and organizational effects. A general citation of expert systems on AIS will be stated and studied in this paper, which aims to investigate the impact of theuse of artificial intelligence and expert systems techniques strategies on accounting information systems. Itconcentrates on concerns that are of most interest for accounting information systems, this investigation looks at the use of Artificial Intelligence and expert systems to be a solution to those concerns, and to be efficient factors in improving general characteristics of accounting information systems in an organization simply by improving productivity and work quality and make a reasonable change in the process life cycle. This thesis targets the large scale market organization in Jordan, where those organizations also has many constrains and limitations. Keywords – AIS; Expert Systems; Work Life Cycle; Productivit

Exchange Market Pressure and Intervention Index for Pakistan: Evidence from a Time-Varying Parameter Approach

The paper uses the approach of Weymark(1995) for constructing exchange market pressure andintervention index for Pakistan and to account for potentiallinearity. A rolling regression indicates unstable real moneydemand and price equation estimates. Consequently, a Kalmanfilter approach is used for evaluating the effects of structuralchanges on parameter constancy. The results indicate unstablereal money demand and price equation parameters. The evidenceshows downward pressure and active Central Bank intervention.Exchange Market Pressure mean value for the first half is higherthan the second half of the sample period suggesting the postreformperiod as more tranquil