An Investigation into the Influence of the Contact Pressure Distribution at the Friction Pair Interface on Disc Brake Squeal

The main purpose of this thesis is to investigate the dynamic centre of pressure during a noisy brake application. A novel technique is employed to measure the centre of pressure and contact pressure distribution between the disc/pad interfaces during braking events. The test rig was developed to study the contact pressure distribution between disc/pad interfaces. The caliper and set of pads were modified to measure both static and dynamic centre of pressure during braking events. The brake uses a 12 piston opposed caliper arranged to allow a number of the pistons to be controlled independently using 4 master cylinders. This allows the interface centre of pressure to be adjusted both along the length of the pad and radially. The tests included static pressure measurements with the sensor film between the pad friction face and the disc, the centre of pressure being adjusted using the master cylinders to provide a “system benchmark”. Once the static characteristic behaviour of the modified pad is established, the centre of pressure variation is measured under dynamic conditions. This allows the movement of the centre of pressure to be plotted against brake pressure and rotor speed. Furthermore, a detailed finite element model of a disc brake assembly is developed. Contact analysis was performed to determine the pressure distribution, interfacial contact area and normal contact forces under both frictionless (μ=0) and frictional braking conditions. The effect of varying friction coefficients and the brake hydraulic pressure is also examined. Preliminary finite element results of contact pressure distribution between the disc/pad interfaces were compared with the experimental results, followed by a detailed modal analysis of disc brake to predict the natural frequencies and the mode shapes of disc brake. In addition, a stability analysis of brake assembly is carried out to distinguish the unstable frequencies. Structure modification of disc brake assembly was also investigated to understand the characteristics behaviour of brake system in terms of squeal noise performance. It is established from the results that there is a strong relationship between the interface pressure distribution, the effective centre of pressure and the propensity of the brake to generate noise. It is noticed that the centre of pressure may vary both along the pad and radially during braking which adds to the complex analysis of instability. The finite element results compared well with the experimental results. It is observed that the contact pressure distribution and the magnitude of normal contact forces are much higher towards the leading edge of the pads comparing to the trailing edge. It is also established yet again that with a leading centre of pressure the brake is more prone to noise whereas with a trailing centre of pressure the system is more likely to be stable

A Clinical Study of Newborns with Tachypnea: Frequency, Aetiologies and their Outcome

Aims & Objectives: To estimate the frequency, aetiologies and outcome of neonates admitted with Tachypnea in Neonatal Intensive Care Unit (NICU) FGPC PGMI Islamabad.To identify the causes of Tachypnea in newborns, analyze outcome at present, and to plan better outcome in futureMaterials & Methods: A prospective study was conducted at Neonatal Intensive Care Unit of Federal Government Polyclinic Hospital PGMI from 1st June 2016 till 31st July 2017.Data were collected from all patients enrolled in the study during this period. Aim of our study is to identify the causes of Tachypnea in newborns, analyze outcome at present, and to plan better outcome in future.Results: Total 826 neonates were admitted, of which 248 were enrolled in the study. The frequency of tacyopnea was found to be 29.9%.The commonest causes of Tachypnea in our study were Respiratory distress syndrome 82 cases (33.1%), Transient Tachypnea of newborn 71 cases (28.6%) , Meconium Aspiration syndrome 31 cases (12.5%), Congenital heart disease 17 cases (6.8%).Cesearean section was the most common predisposing factor associated with development of  RDS & TTN( the two most common causes of respiratory distress in our study) 146 (58.9%) cases. The mortality rate of tacyopnea in our study was 103 cases (41.5%).Conclusion: Tachypnea is one of the most common problems encountered in neonatal ICUs of which RDS, TTN, MAS and CHD are the common ones. Prematurity, low birth weight neonates and neonates born via Cesearean section show a poorer outcome, needing advanced respiratory support and longer duration of hospital stay. Thus, timely decisions regarding the mode of delivery, prevention of preterm deliveries, and appropriate management of Tacyopnea may reduce neonatal mortality

Assessing the needs and measuring the impact of the information literacy sessions at the Aga Khan University’s Institute for Educational Development, Pakistan

Main objective of this paper is to assess the information literacy needs of the fresh M.Ed. students at the AKU-IED and to measure the impact of the information literacy sessions over the students by using the pretest and post-test tool.Document the users’ reflections to improve the forthcoming information literacy sessions. Pretest questionnaire was sent to the M.Ed. students of AKU-IED to know the information literacy needs, and to know about their understanding about collection, OPAC and e-resources. As a result needs identified through this questionnaire were addressed in the information literacy session. This hands-on information literacy session was complimented with the handouts and assignments were given to the students as well. After the information literacy session, posttest questionnaire was sent to the users. This posttest questionnaire was having some questions taken from the pretest with a purpose to measure the impact the session had made over the students. This measurement was carried out by comparing the responses collected in the pretest and posttest. Posttest questionnaire was also having the questions to know the users reflections about the weak part of the session, strongest part of the session and their opinion to improve the forthcoming sessions. Present results showed the weak areas of the students which include the concepts of call number, classification number, author mark, ways to access the library collection, use of OPAC, databases, full-text articles were needed to be covered in the IL session. Some areas needed less attention and time during the sessions because majority of the students were already familiar to them. These were concepts of on-campus access, type of searches through OPAC and the definition of OPAC. Post-test analysis showed us the impact the session has made

Underage motorbike driving in Pakistan: a neurosurgical burden heading towards societal disaster

No abstract available

An affordable low-cost home-made skull model for interactive neurosurgical workshops: experience with hands-on intracranial pressure monitoring at 2 international neurosurgical conferences

Background: Undergraduate neurosurgery conferences are acknowledged to play an important role in bridging the gap between a limited exposure to neurosurgery within medical schools and a highly competitive application process. Hands-on workshops are attractive for any conference but can be prohibitively expensive, especially for student societies. Methods: We describe our method to manufacture a low-cost skull model, which we used for a hands-on intracranial pressure (ICP) monitoring workshop station at 2 international neurosurgical conferences. We describe the workflow for our ICP monitoring workshop using these models. Results: Our model acts as an appropriate substitute for more professional simulators while adequately mimicking the sensation of skull drilling, dural puncture, and intraparenchymal ICP bolt and probe insertion. All tools and resources are accessible from local markets and can be sourced online. A total of GB£100 was spent making 5 skull models and took 2 hours to manufacture by 3 individuals. The ICP monitoring workshop was carried out 3 times over 40 minutes, with each session accommodating 18 or 19 delegates (N = 55). Conclusions: These workshop models have been praised by medical students for increasing exposure and awareness toward neurosurgical procedures and the sophistication of investigations used by the specialty. Consultant neurosurgeons have praised the simulation provided by these models as closely mimicking the procedure in reality

Mapping the Spatial Deprivation of Pakistan

Geographical targeting may be a viable way to allocate resources for poverty alleviation in developing countries. Efficiency can be increased, and leakages to the nonpoor reduced substantially, by targeting needy areas. A national and regional database of substantial poverty maps or deprivation indices are not readily available in Pakistan. Further, existing activities of poverty alleviation are carried out on ad hoc basis in the absence of identified pockets of poverty. This paper presents indices of multiple deprivations based on the 1998 Population and Housing Census data. Possible applications of this exercise include identifying areas of need, making decisions on regional and sectoral priorities, facilitating targeted public interventions through special poverty alleviation programmes, understanding the relationship between poverty and its causes, and helping federal and provincial governments in determining financial awards.

Clinico-Biochemical Profile in Neonates with Birth Asphyxia

Objective: To study the biochemical derangements in neonates with asphyxia having different clinical presentation. Patients and Methods: This cross-sectional study was conducted at Neonatal Intensive Care Unit, Federal Govt. Polyclinic (PGMI) Hospital, Islamabad from 1st November 2016 to 30th April 2017. All neonates with history suggestive of birth Asphyxia were inducted in study. Complete history, examination and laboratory investigation (Complete blood count, Blood Sugar, Serum Calcium, Serum Electrolytes, Serum Urea, Serum Creatinine, Liver function tests, Cardiac Enzymes) were done. The data was entered in SPSS version 23 for further analysis. Results: Out of 39 babies, 66.7% had moderate and 33.3% had severe birth asphyxia. Severity of birth asphyxia was associated with lower APGAR Scores. Multi-organ involvement was observed with increasing severity of birth asphyxia as; respiratory system 71.8%, cardiovascular system (shock) 25%, central nervous system (convulsion)15.4%, renal tract (acute renal failure) 12.8% and gastro intestinal tract 5.1%. Significant mortality was noted with shock, convulsion and hypoglycemia. Cardiac and liver enzymes were deranged and were significantly related to severity of birth asphyxia. Conclusion: Multi-organ dysfunction is common in birth asphyxia. Early assessment of clinical and biochemical profile will help in managing disease, reducing severity and improving the outcome of illness

Takayasu’s Disease: A Rear Case of Occlusive Vascular Disorder of Brain

Takayasu’s Disease is a type of inflammatory disease which involve the vessels at different levels. This disease is important for remission and relapse. It usually affects the younger age group resulting in morbidity of the most valuable group of society. Its symptoms are non specific but it may present with the involvement of different organs of the body like heart, renal impairment, fibrosis of retroperitoneal area. Diagnostic tool is Ultrasonography but definitive diagnosis is achieved with the help of CT angiography at the level of aortic arch, neck and brain. Treatment includes both medical and surgical options. Most of the time relapse occurred but with various treatment we can prolong the remission span and improve the quality of life of the patient

Anterior Cage Fixation in Spinal Injuries

Methods:  The study comprised 121 patients (98 men and 23 women) between ages 15-70 years with one spinal fracture with two or three column destruction, who underwent with expandable cage placement, between January 2005 to January 2009. Neurological status was classified using American Spinal Injury Association (ASIA) impairment scale and motor index. The fusion status and spine alignment were examined by radiological imaging. Results:  All patients in this study achieved solid fusion with significant neurologic improvement. Mean follow up time was 6 months. Neurologic status in 41 patients (pre op: ASIA-E post op-unchanged). 30 patients (pre-op: ASIA-D, post-op improved to ASIA-E). 6 patients (pre op: ASIA-B, 2 patients improved to ASIA-D and 5 patients improved to ASIA-D). Pain improved in all case and sensations were last to recover. Conclusion:  The TMC is an effective adjunct in restoring and maintaining sagittal plane alignment after thoracolumbar vertebrectomy to achieve canal decompression and in this context it provides an effective method for anterior column reconstruction. It has been found to be a rapid and safe procedure for lumber spine fusion, with a high fusion rate and clinical success with rare serious complications. Key words:  Thoracolumbar spinal trauma, Titanium Mesh Cage, Anterior Column Reconstruction of spine, Spinal stability