Transient response of a polymer electrolyte membrane fuel cell subjected to modulating cell voltage

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97515/1/er1940.pd

An experimental study of heat transfer through liquid foam.

An experimental investigation was carried out to determine the thermal conductivity and the total solar transmissivity of liquid foam and to check the feasibility of its use as an insulation medium between the walls of a greenhouse in a hot climate to act both as an insulator and as a translucent medium to attenuate thermal radiation. Two test rigs were designed and fabricated: one for thermal conductivity tests and one for solar transmissivity tests. An online data acquisition program was developed for fast collection of information and in situ data reduction. As a translucent medium to attenuate radiation, liquid foam was found to be very effective. A 25 mm layer was found to transmit only 50% of the incident radiation. In addition, it was found that the thermal conductivity is independent of the solute concentration of the surfactant solution, decreases with an increase in the temperature difference and increases rapidly with an increase in the mean temperature. The results revealed that a vertical annular liquid foam layer of 25 mm thickness has a thermal conductance 1.86 times that of air for a mean temperature of 25\sp\circC and a temperature difference of 10\sp\circC. An uncertainty analysis showed that the values of the thermal conductivities and the solar transmissivities had uncertainties of approximately 5.7% and 8.9% respectively.Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1992 .S436. Source: Masters Abstracts International, Volume: 31-04, page: 1914. Thesis (M.A.Sc.)--University of Windsor (Canada), 1992

Follow-up bibliometric analysis of neurosurgical publications from Pakistan and institutional comparison with other countries using h-index and i-10 Index

Aim: The aim of the study was to analyze the neurosurgical research output of Pakistan and compare it with that of developed countries.Methodology: We conducted a bibliometric analysis of publically available databases for all neurosurgical publications from Pakistan. All indexed peer-reviewed publications from January 2009 to December 2014 where at least one author was affiliated with any neurosurgical departments in Pakistan and research was conducted in Pakistan were selected. Manual and electronic search was done using MeSH terms to search for articles from Pakistan. Articles were then categorized according to design, subspecialty, region, and year.Results: Our search identified 121 articles during the defined study period (mean = 20.16 ± 5.2 papers/year). A relatively constant increase was noticed for the last 6 years, i.e., 2009-2014. From the total 121 references, 100 (82.4%) publications were from one city, and on subanalysis, 80 (66.1%) were from a single institution. Three primary authors cumulatively contributed to 76 (62.8%) of these publications. Almost two-thirds (n = 76, 62.8%) of these publications were published in either regional or international journals while only 37.2% (n = 45) were published in local nonneurosurgery-specific journals. Only one study in the 6-year study period was with Level I evidence (meta-analysis).Conclusion: Neurosurgery research in Pakistan has shown modest improvement in terms of quality and quantity. Collaboration between various centers and channelizing different resources to create national data registries along with basic science laboratories is much needed

Value of routine preoperative tests for coagulation before elective cranial surgery. Results of an institutional audit and a nationwide survey of neurosurgical centers in Pakistan

Background: Routine preoperative blood testing has become a dogma. The general practice is to order preoperative workup as a knee-jerk response rather than individualize it for each patient. The fact that the bleeding brain tends to swell, which coupled with limited options for proximal control, packing, and overall hemostasis, leads to an overemphasis on the preoperative coagulation profile.Material and methods: This is a retrospective review of the medical records of patients admitted at Aga Khan University Hospital from January 2010 to December 2015 for an elective craniotomy. The hospital registry was used to identify files for review. Data were collected on a predefined proforma. A nationwide survey was performed, and 30 neurosurgery centers were contacted across Pakistan to confirm the practice of preoperative workup.Results: The survey revealed that all centers had a similar practice of preoperative workup. This included complete blood count, serum electrolytes, and coagulation profile, including prothrombin time, activated partial thromboplastin time (aPTT), and international normalized ratio (INR). A total of 1800 files were reviewed. Nine (0.5%) patients were found to have deranged clotting profile without any predictive history of clotting derangement; 56% were male and 44% were female. Median age was 32 years with an interquartile range of 27 years. Median aPTT was (40.8 with 20.8 IQR). Median INR was (1.59 with 0.48 IQR). Median blood loss was (400 with 50 IQR). No significant association between coagulation profile (aPTT, INR) and blood loss was found (P = 0.85, r = -0.07).Conclusions: We conclude that patients without a history of coagulopathy and normal physical examination do not require routine coagulation screening before elective craniotomy

Smart monitoring and controlling of frequency deviation by using MATLAB GUI and ARDUINO DAQ card

Electricity transmission and distribution in most of the countries are needed to be improved by the construction of new networks. These improvements are not that much cost effective and if cost is tried to be reduced then the quality and efficiency of the system is compromised which is not suitable at all for the current system. In addition obtaining planning permission and carrying out construction is so much difficult in busy cities. The main objective of this research is to monitor and control frequency deviation. A simple MATLAB controlling and monitoring system is being developed and the ARDUINO DAQ card is used to calculate the frequency deviation. The purpose of respective research is basically based on a dummy load which is used to show the usage of particular equipment’s used in a home such as fridge, freezer, oven, lighting system, and domestic wet appliances such as washer dryer which are attached these to a DAQ and then to a controlling and monitoring GUI MATLAB based. However, this research is focused on the monitoring and controlling of the frequency deviation

Clinical outcome and cost effectiveness of early tracheostomy in isolated severe head injury patients

Background: Early tracheostomy (ET) has been shown to be effective in reducing complications associated with prolong mechanical ventilation. The study was carried out to evaluate the role of ET in reducing the duration of mechanical ventilation, duration of intensive care unit (ICU) stay, ICU-related morbidities, and its overall effect on outcome, in patients with isolated severe traumatic brain injury (TBI).Methods: This 7-year review included 100 ICU patients with isolated severe TBI requiring mechanical ventilation. ET was defined as tracheostomy within 7 days of TBI, and prolonged endotracheal intubation (EI) as EI exceeding 7 days of TBI. Of 100 patients, 49 underwent ET and 51 remained on prolong EI for ventilation. All patients were comparable in term of age and initial Glasgow Coma Scale (GCS). We evaluated groups regarding clinical outcome in terms of ventilator-associated pneumonia (VAP), ICU stay, and Glasgow Outcome Score (GOS).Results: The frequency of VAP was higher in EI group relative to ET group (63% vs. 45%, P value 0.09). ET group showed significantly less ventilator days (10 days vs. 13 days, P value 0.031), ICU stay (11 days vs. 13 days, P value 0.030), complication rate (14% vs. 18%), and mortality (8.2% vs. 17.6%). Clinical outcome assessed on the basis of GOS was also better in the ET group. Total inpatient cost was also considerably less (USD $8027) in the ET group compared with the EI group (USD$9961).Conclusions: In patients with severe TBI, ET decreases total days of ventilation and ICU stay, and is associated with a decrease in the frequency of VAP. ET should be considered in severe head injury patients requiring prolong ventilatory support

Numerical Investigation of Heat Transfer Performance of Various Coiled Square Tubes for Heat Exchanger Application

AbstractIn heat exchanger application, working fluid inside the tubes is subjected to considerable temperature changes. In order to improve heat transfer performance, various strategies are proposed and evaluated; one of them is the application of coiled tubes. Coiled tubes have been used widely in heat exchanger application mainly due to the presence of secondary flow which enhances heat transfer considerably. This study addresses heat transfer performance of three configurations of coiled tubes with square cross-section, i.e. in-plane, helical and conical coiled tubes, subjected to large temperature difference. Their heat transfer performance is numerically evaluated and compared with that of a straight tube with identical cross-section and length. A concept of Figure of Merit (FoM) is introduced and utilized to fairly asses the heat transfer performance of the coiled tube configurations. The results indicate that FoM increase as the wall temperature increase. In addition, combination of temperature-induced buoyancy flow and curvature-induced secondary flow considerably affect the flow behavior and heat transfer performance inside the tubes

The discrepancy between admission and discharge diagnoses: Underlying factors and potential clinical outcomes in a low socioeconomic country

Objective: The discrepancy between admission and discharge diagnosis can lead to possible adverse patient outcomes. There are gaps in integrated studies, and less is understood about its characteristics and effects. Therefore, this study was conducted to determine the frequency, characteristics, and outcomes of diagnostic discrepancies at admission and discharge.Design and data sources: This retrospective study reviewed the admitting and discharge diagnoses of adult patients admitted at Aga Khan University Hospital (AKUH), Internal Medicine Department between October 2018 and February 2019. The frequency and outcomes of discrepancies in patient diagnoses were noted among Emergency Department (ED) physician versus admitting physician, admitting physician versus discharge physician, and ED physician versus discharge physician for the full match, partial match, and mismatch diagnoses. The studied outcomes included interdepartmental transfer, Intensive Care Unit (ICU) transfer, in-hospital mortality, readmission within 30 days, and the length of stay. For simplicity, we only analyzed the factors for the discrepancy among ED physicians and discharge physicians.Results: Out of 537 admissions, there were 25.3-27.2% admissions with full match diagnoses while 18.6-19.4% and 45.3-47.9% had mismatch and partial match diagnoses respectively. The discrepancy resulted in an increased number of interdepartmental transfers (5-5.8%), ICU transfers (5.6-8.7%), in-hospital mortality (8-11%), and readmissions within 30 days in ED (14.4%-16.7%). A statistically significant difference was observed for the ward\u27s length of stay with the most prolonged stay in partially matched diagnoses (6.3 ± 5.4 days). Among all the factors that were evaluated for the diagnostic discrepancy, older age, multi-morbidities, level of trainee clerking the patient, review by ED faculty, incomplete history, and delay in investigations at ED were associated with significant discrepant diagnoses.Conclusions: Diagnostic discrepancies are a relevant and significant healthcare problem. Fixed patient or physician characteristics do not readily predict diagnostic discrepancies. To reduce the diagnostic discrepancy, emphasis should be given to good history taking and thorough physical examination. Patients with older age and multi-morbidity should receive significant consideration

Applying a mixed-method approach to improve on-the-job learning and job satisfaction in a cohort of interns at a university hospital

Introduction: Job satisfaction is vital for the optimal functioning of medical practitioners. Herein, we report our experience of restructuring the internship program by identifying the gaps, developing, implementing strategies to overcome gaps and sharing the results of the pre-implementation and post-implementation audit, as an example for establishing a system for improving intern\u27s work-based learning and satisfaction in a university hospital setting.Methods: Using Kern\u27s six-step instructional model, a prospective mixed-method study was conducted at Aga Khan University Hospital. In phase 1 (2013) gaps were identified by evaluating various aspects of the internship program. Strategies were developed and implemented to overcome the identified gaps. In phase 2 (2014-2016) the impact of these developmental strategies was assessed.Results: A total of 65 interns, 30 residents, and 22 faculty members participated in phase I, while 71 interns participated in phase II. The reformation of orientation sessions, including practical exposure and content of sessions, opportunities to enhance hands-on experience and supervision in inpatient areas, operating rooms, supervision by fellows, supervision for hands-on procedures, career counseling, and mentorship, led to significant improvement in satisfaction. It was identified that the lack of hands-on opportunities can be overcome by surgical skills-based workshops. These reforms led to an overall rise in intern satisfaction (50% vs 75.4%, p=0.02).Conclusion: Periodic restructuring of an existing program helps to improve the work-based learning experience and overall satisfaction among interns. This not only maximizes learning but also eases interns into their postgraduate life and workload subsequently enabling them to become more competent and well-rounded health practitioners