112 research outputs found
Inhaled aztreonam lysine vs. inhaled tobramycin in cystic fibrosis: a comparative efficacy trial.
No full textBackground: Open-label, parallel-group, international trial comparing aztreonam for inhalation solution (AZLI) and tobramycin nebulizer solution (TNS) for cystic fibrosis patients with airway Pseudomonas aeruginosa.
Methods: 273 patients (≥ 6 years); randomized to three 28-day courses (AZLI 75 mg [three-times/day] or TNS 300 mg [twice/day]); 28 off-days separated each course.
Results: 268 patients were treated (AZLI/TNS: 136/132). Mean baseline FEV1 was 52% predicted. Mean relative changes after 1 course (AZLI: 8.35%; TNS: 0.55%; p<0.001) and mean actual changes across 3 courses (AZLI: 2.05%; TNS: -0.66%; p=0.002) indicated AZLI statistical superiority vs. TNS. AZLI-treated patients had fewer respiratory hospitalizations (p=0.044) and respiratory events requiring additional antipseudomonal antibiotics (p=0.004); both treatments were well tolerated. 133 patients received 1 to 3 courses of AZLI treatment in the open-label extension-period (28-day courses separated by 28 days off-treatment); lung function improvements were comparable regardless of whether patients had received TNS or AZLI in the preceding comparative period.
Conclusions: AZLI demonstrated statistical superiority in lung function and a reduction in acute pulmonary exacerbations compared to TNS over 3 treatment courses (ClinicalTrials.gov: NCT00757237)
Digital control of an electro discharge machining (EDM) system
Get PDFThis thesis presents a model of the complete Electro Discharge Machining (EDM) system and the design and implementation of a digital controller for the servomotor control and the gap voltage and current pulse power generator. A Matlab/Simulink simulation is used to investigate the EDM system model behaviour and based on the simulation results, a compensated EDM control system is designed. Simulation studies were also earned out to predict the material removal rate of a steel workpiece in mm3/min . The control software of the EDM control process and servo system control was performed mainly in software with minimal hardware implementation. The control hardware consists of an eZdsp, userinterface device and analogue signal processing and interfacing circuit. The eZdsp communicates with the user-interface device by sending the information/instruction to the LCD screen while the user-interface device uses push button switches to communicate with the eZdsp. It is shown that one DSP microcontroller can be used to provide the control functions for the EDM system. The experimental studies of the Electro Discharge Machining process using a copper electrode, a graphite electrode and steel workpiece materials are presented in tabular and graphical forms. The analysis of the experimental results show that the material removal rate is influenced by the process parameters such as the gap current Igap• gap voltage V arc. pulse on-time Ion, and sparking frequency F, as well as the material properties of the electrode and the workpiece. Comparison studies between simulation and experimental results show reasonable agreement. Further improvement was made to the EDM process model based on the comparison studies. As a result, the predicted material removal rate using the improved EDM process model shows better agreement with experimental results.EThOS - Electronic Theses Online ServiceGBUnited Kingdo
Fabrication and characterization of polycaprolactone (PCL)/gelatin electrospun fibers
No full textOver the past few decades, there has been considerable interest in developing electrospun fibers by using electrospinning technique for various applications. Polymer blending is one of the most effective methods in providing desired properties. In this study, synthetic polymer polycaprolactone (PCL) was blended together with natural polymer gelatin where both of them have different properties. It is done by using electrospinning technique. 10%w/v and 14%w/v PCL/gelatin electrospun fibers were successfully electrospun with different weight ratio. Processing parameters were set constant in this study and only solution parameters were altered. The optimized electrospun fiber formed was 14%w/v PCL/gelatin 70:30 with average fiber diameter of 246.30 nm. No beaded fiber was formed in this scanning electron microscope (SEM) image. The result obtained also showed that by increasing the overall polymeric concentration of PCL/gelatin, average fiber diameter decreases. Fiber diameter was also found decreasing with the increase of the concentration of gelatin in the same concentratoin of PCL/gelatin blended electrospun fiber. Blending of PCL and gelatin in different weight ratio had provided different properties of electrospun fibers. It is believed that blended electrospun fibers can be used for biomedical applications
Mathematical model of electrical discharge machining pulse profile
Get PDFElectrical Discharge Machining (EDM) is a non-conventional manufacturing process where the removal of the unwanted materials is performed without a direct contact between the electrode and workpiece. This paper reports the mathematical model of EDM pulses that focuses on open circuit and normal discharge of circuit condition. The model is based on the equivalent electrical model of voltage and current control where the normal discharge model employs ignition delay of 4μs, 10μs and 16μs. By applying Kirchhoff’s voltage law, the voltage gap of an open circuit can be expressed according to a closed-loop network with zero current flow. As a result, the developed mathematical model capables to represent the pulse profile in EDM machining process
Consistent machining of electrical discharge machining power supply towards hip implant surface texturing
Get PDFElectrical Discharge Machining, EDM is one of the technologies used for surface texturing such as the embedded micro-dimples on the metallic acetabular cup. During the machining process, changes in the gap distance may lead to load changes from open to short circuit. Limiting the load current under short circuit conditions and load voltage under open circuit conditions is the requirement in this system. Power supply is one of the elements that controls the process parameters which is related to improve the machining condition as well as Material Removal Rate (MRR). A considerable number of power supply design method were proposed for various EDM application. This research proposed a Switch Mode Power Supply method implementing new design of Flyback power supply which can stabilize the voltage during open circuit condition as well as during discharge condition. Experimental studies were conducted to verify the capability of Flyback power supply by machining eight micro-dimples in lower position and twelve micro-dimples in upper position, both in circular arrangement on metallic acetabular cup. Research conducted shows that the Flyback power supply improve the consistency of MRR when compared to Linear power supply. This may help to predict the machining time, thus improving the production of microdimples in required time
The emerging roles of managers in influencing life insurance agents to perform customer-orientation behaviour
Get PDFThe issue of salespeople's customer-orientation behaviour has attracted the interest of both academic and business people. One major factor which has been increasingly discussed as a determining factor of salespeople's customerorientation behaviour is role perception, which consists of role ambiguity and role conflict. In this study, the influence of these two factors on salespeople S
customer-orientation behaviour was examined. Data gathered from 445 life insurance agents were used to test the hypothesised relationships. The results supported the hypotheses that both rule ambiguity and role conflict
negatively affect salespeople to adopt customer-orientation behaviuur in their selling activities. The theoretical implications and managerial implications, particularly the important role of insurance managers in dealing with insurance agent's customer-orientation behaviour, of these findings are discussed
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