249 research outputs found

    DESIGN OF REAL-TIME FUZZY LOGIC PSS BASED ON PMUs FOR DAMPING LOW FREQUENCY OSCILLATIONS

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    Poorly damped low frequency oscillations is one of the main problems threatening safe and stable operation of the interconnected power systems and reducing the capability of transmission the power. The generator's excitation system has been supplemented with the Power System Stabilizer (PSS) in order to improve the damping of these low oscillations. In the latest smart power grids, the Phasor Measurement Units (PMUs) become a fundamental element in the monitoring, protection and control applications as PMU signals are more accurate than the conventional measurement units and real time GPS stamped. In this study, Fuzzy Power System Stabilizer (FPSS) has been designed and its performance in damping inter-are oscillations compared with the conventional PSS (CPSS) based on the simulation with MATLAB/Simulink model. The results of the simulation with the Simulink model proved that the performance of the designed FPSS in damping inter-area oscillation is better than the CPSS. One of the main features of fuzzy controller is that it doesn't require mathematical modeling as it is designed based on the time-domain and the operator experience while, in contrast, the conventional PSS requires to be designed in the frequency domain. Real Time Digital Simulator (RTDS) has been used to develop the real-time models of the test systems. The time-domain simulations with the RTDS model when the system subjected to the large disturbance (three-phase to ground fault) have been performed to show that the designed FPSS improved the damping of the oscillations effectively. The simulation results have been verified by modal analysis

    FEASIBILITY OF BAY SALAM FINANCE: A SURVEY OF THE OPINIONS OF STAKEHOLDERS

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    The present study aims to explore the potential application of Bai Salam (forward sale agreement) as substitute financial instrument in the agriculture sector of Pakistan. The conclusion is drawn through a survey questionnaire from 300 farmers and bankers in a district of Punjab. For analysis, we use SPSS software and presented the results by using descriptive methods. This study overall concludes the banker’s and farmer’s awareness, willingness, risks, hurdles and the role of institutions in the Salam promotion. The majority of the farmers are not aware of the Salam contract because the Islamic bank’s branch network is limited to urban areas and there is no proper promotion campaign launched by the Islamic banks for awareness about Salaam among the farmers. Bankers are reluctant to finance the tenants, orchards due to more operational risk for the bank. Bankers opinion that small farmers do not have personal securities which is not a solid reason because half of the sampled farmers take a loan from the formal system if they can provide securities to conventional interest-based institution why they can’t provide securities to Islamic financial institutions? There is a vast market for the Islamic Banks if they sincerely pay their attention towards forward sale contracts. The concept applies to all areas of agriculture and livestock farming to overcome financing problems and boost production.

    Laparoscopic repair of diaphragmatic defect by total intracorporeal suturing: Clinical and technical considerations

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    OBJECTIVE: The use of laparoscopy in urology is increasing. Tumor of the kidney or adrenal gland and, in some cases, metastatic disease can involve the diaphragm. We describe the application of laparoscopic suturing techniques in the case of diaphragmatic involvement with a renal tumor. METHODS: After resection of the tumor and a small area of the diaphragm, a chest tube was placed under laparoscopic guidance. The tube was kept clamped until the end of the procedure. Decreasing intraabdominal pneumoperitoneum pressure made suturing easier with less tension on the edges of the diaphragmatic incision. Nonabsorbable interrupted horizontal mattress sutures were placed to close the diaphragmatic defect. RESULTS: The repair was uneventful; no intraoperative complications occurred. Extubation was done at the end of the procedure in the operating room. The chest tube was removed on postoperative day 2, and the patient was discharged on postoperative day 3. CONCLUSIONS: Laparoscopic repair of the diaphragm should be commensurate with traditional open surgical principles. In this regard, it is essential that surgeons interested in performing “advanced” laparoscopic onco-logic surgery become facile in laparoscopic suturing

    A Case of Alcohol Withdrawal-Induced Central and Extrapontine Myelinolysis

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    A 40-year-old female with a history of chronic alcohol use disorder presented with an acute intractable left-sided headache for three days and progressively worsening unsteady gait requiring a wheelchair to ambulate. The patient had a history of chronic alcoholism since 2019 but reported abstinence since September 2021. One month after quitting alcohol, she experienced a sudden deterioration in bilateral extremity neuropathy, forgetfulness, difficulty writing, and severe mood swings, which continued to worsen until her presentation in July 2022. Laboratory tests, including complete blood count and electrolyte levels, were within normal ranges. A previous MRI performed during the investigation for alcoholic neuropathy a few months before she quit drinking showed no abnormalities. However, a subsequent MRI during work-up for the current acute symptoms revealed significant signal abnormalities involving the central pons, bilateral cerebral peduncles, and medullary pyramids, consistent with chronic central pontine myelinolysis (CPM) with extrapontine myelinolysis (EPM) extending into the peduncles. The patient received treatment with folate and multivitamins and was scheduled for outpatient follow-up with physical therapy for rehabilitation. This case highlights CPM as a consequence of alcohol withdrawal and emphasizes the importance of timely diagnosis and appropriate management in such patients

    Cross talk between serum Kisspeptin-Leptin during assisted reproduction techniques

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    Background & Objective: Leptin facilitates onset of puberty by impact on hypothalamic Kisspeptin, gonadotropin releasing hormone, follicle stimulating and luteinizing hormone. The link of peripheral Leptin-Kisspeptin in regulating the ovarian and endometrial tissue in relation to adiposity is unknown. Therefore, we wanted to identify Kisspeptin-Leptin association with body mass index (BMI) and success of assisted reproductive treatments (ART) in infertile females.Methods: A cross sectional study was carried from August 2014 till May 2016 after receiving ethical approval at Australian Concept Infertility Medical Centre, and Aga Khan University. The study group comprised of females with an age range of 25-37 year who had duration of unexplained infertility for more than two years. They were grouped as; underweight (/m2), normal weight (18-22.9 kg/m2), overweight 23-24.99 kg/m2 and obese (\u3e25 kg/m2). Kisspeptin and Leptin levels were measured by enzyme linked immune sorbent assay before down regulation of ovaries and initiation of treatment protocol of ART. Failure of procedure was detected by beta human chorionic gonadotropin \u3c25mIU/ml (non-pregnant) whereas females with levels \u3e25mIU/ml and cardiac activity on trans-vaginal scan were declared pregnant.Results: Highest Kisspeptin and Leptin levels were seen in normal weight group (374.80 ± 185.08ng/L; 12.78 ± 6.8 pg/ml) respectively, yet the highest number of clinical pregnancy was observed in overweight group (42%).A strong correlation of Kisspeptin with Leptin (r=0.794, p=0.001) was observed in the overweight females.Conclusion: Leptin-Kisspeptin-fertility link is expressed by maximum number of clinical pregnancies in the female group that showed strongest relationship between serum Leptin and Kisspeptin levels, irrespective of their BMI

    Salinity induced changes in cell membrane stability, protein and RNA contents

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    Seedlings of sugar beet (Beta vulgarus L.) were used at salinity levels of 0 (control), 4.7, 9.4 and 14.1 dS m-1 to determine the effect of salt on vegetative growth, relative water content, cell membrane stability, protein and RNA contents in sand culture experiment. Fresh and dry weights of plants, shoots and roots decreased significantly with increasing salt concentration. Salinity significantly reduced leaf area and relative water content while cell membrane injury increased with increasing salt concentration. Leaf protein content decreased significantly and sodium dodecyl sulphate-polyacrylamide gel electrophresis (SDS-PAGE) analysis showed significant change in protein profiles in salt treated samples, which suggests that NaCl altered protein pattern. Salinity induced RNA degradation with increasing salt level. Cell membrane stability exhibited negative correlation with fresh and dry weight, leaf area, leaf water content and total protein content. There was also a significant positive correlation between cell membrane injury and RNA degradation.Key words: Salt stress, membrane injury, growth, RWC, protein activity, RNA, Beta vulgarus L

    Motivation and retention of physicians in primary healthcare facilities: a qualitative study from abbottabad, Pakistan

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    BACKGROUND: Workforce motivation and retention is important for the functionality and quality of service delivery in health systems of developing countries. Despite huge primary healthcare (PHC) infrastructure, Pakistan\u27s health indicators are not impressive; mainly because of under-utilization of facilities and low patient satisfaction. One of the major underlying issues is staff absenteeism. The study aimed to identify factors affecting retention and motivation of doctors working in PHC facilities of Pakistan. METHODS: An exploratory study was conducted in a rural district in Khyber Puktunkhwa (KP) province, in Pakistan. A conceptual framework was developed comprising of three organizational, individual, and external environmental factors. Qualitative research methods comprising of semi-structured interviews with doctors working in basic health units (BHUs) and in-depth interviews with district and provincial government health managers were used. Document review of postings, rules of business and policy actions was also conducted. Triangulation of findings was carried out to arrive at the final synthesis. RESULTS: Inadequate remuneration, unreasonable facilities at residence, poor work environment, political interference, inadequate supplies and medical facilities contributed to lack of motivation among both male and female doctors. The physicians accepted government jobs in BHUs with a belief that these jobs were more secure, with convenient working hours. Male physicians seemed to be more motivated because they faced less challenges than their female counterparts in BHUs especially during relocations. Overall, the organizational factors emerged as the most significant whereby human resource policy, career growth structure, performance appraisal and monetary benefits played an important role. Gender and marital status of female doctors was regarded as most important individual factor affecting retention and motivation of female doctors in BHUs. CONCLUSION: Inadequate remuneration, unreasonable facilities at residence, poor work environment, political interference, inadequate supplies, and medical facilities contributed to lack of motivation in physicians in our study. Our study advocates that by addressing the retention and motivation challenges, service delivery can be made more responsive to the patients and communities in Pakistan and other similar settings

    A New Look at the YY Tetraquarks and Ωc\Omega_c Baryons in the Diquark Model

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    We analyze the hidden charm PP-wave tetraquarks in the diquark model, using an effective Hamiltonian incorporating the dominant spin-spin, spin-orbit and tensor interactions. We compare with other PP-wave system such as PP-wave charmonia and the newly discovered Ωc\Omega_c baryons, analysed recently in this framework. Given the uncertain experimental situation on the YY states, we allow for different spectra and discuss the related parameters in the diquark model. In addition to the presently observed ones, we expect many more states in the supermultiplet of L=1L=1 diquarkonia, whose JPCJ^{PC} quantum numbers and masses are worked out, using the parameters from the currently preferred YY-states pattern. The existence of these new resonances would be a decisive footprint of the underlying diquark dynamics.Comment: Revised and extended to accommodate referee comments. Added a table and references. Accepted for publication in the EPJ
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