Grid synchronization algorithm for distributed generation system during grid abnormalities

Distributed Generation (DG) System is a small scale (less than 20 MW) electric or shaft power generation at or near the user‟s facility as opposed to the normal mode of centralized power generation. DGs include wind energy, photo voltaic system, fuel cell and combined heat and power (CHP) generation etc. To ensure safe and reliable operation of power system based on DG system, usually power plant operators should satisfy the grid code requirements such as grid stability, fault ride through, power quality improvement, grid synchronization and power control etc. Number of synchronizing algorithms has been discussed in the literature to track the phase angle of the grid voltage or current to synchronize DG system with the grid. One of the earliest introduced methods for tracking the phase angle is Zero Crossing Detector (ZCD) and it gives better response during balanced grid conditions. But the occurrence of power quality problems, especially in weak grid, leads to malfunctioning of the controllers based on ZCDs. An alternative to ZCD is the Phase Locked Loops (PLLs) for grid synchronization which provides better response with accuracy. Different PLLs have also been proposed and are studied extensively in the available literature starting from Charge Pump PLL to Linear PLL and Synchronous Reference Frame (SRF) PLL which can very well track the phase angle and frequency during balanced conditions. But during abnormal conditions like frequency deviations, voltage unbalances and power quality problems such as voltage flicker, voltage dip, voltage sag, distorted grid voltages, these PLLs fails to track the phase angle and frequency with good accuracy. These shortcomings are overcome by Double Synchronous Reference Frame (DSRF) PLL and a PLL based on Second Order Generalized Integrator (SOGI).In this work the above mentioned PLLs are analysed for different abnormal grid condition which is followed by the comparative study between two advanced PLL techniques (DSRF PLL and SOGI based PLL). The analysis is carried out in MATLAB/SIMULINK environment and the obtained results are discussed for effectiveness of the study

Episodic fluviolacustrine deposits of Indus River Basin: a case study of Spituk palaeolake sequence

Abstract HKT-ISTP 2013 B

Prevalence of Extended Spectrum Beta Lactamase Producing and Carbapenems Resistance Isolates from Hands of Health Care Workers in a Health Care Setting of Nepal

Background: Hands of healthcare workers (HCWs) could be colonized by potential drug resistant bacteria like Extended Spectrum Beta Lactamase producers (ESBLs) and Carbapenems-resistant (CR) isolates and could become vectors of nosocomial pathogens in healthcare facilities that are associated with an increase of morbidity, mortality and healthcare costs. This study aimed to investigate the prevalence of ESBLs and CR isolates from hands of HCWs with their antibiotic susceptibility pattern. Materials and methods: This was a cross-sectional study that included a total of 150 hand swabs collected from March, 2018 to September, 2018 in Gandaki Medical College and Teaching Hospital. Isolation, identification and antimicrobial susceptibility tests were done using standard microbiological procedures. Results: Among the total isolates of 219 obtained from growth positive samples 92/219(42.01%) were Gram negative bacteria (GNB) and the most common were Klebsiella spp 32(34.78%) followed by Escherichia coli 17(18.48%), Pseudomonas aeruginosa12 (13.04%), Acenetobacter spp 11(11.96%), Proteus spp 9(9.78%), Citrobacter spp 7(7.61%) and Enterobacter spp 4(4.35%). The prevalence of ESBLs, CR and ESBLs with Co-resistant to Carbapenems were 19.56%,14.13% and 9.78%, respectively. The most effective drugs for isolates were Nitrofurantoin followed by Amikacin, Tetracycline and Gentamycin. Distribution pattern of the ESBLs and CR isolates among doctors, nurses, laboratory technicians, helpers and basic science faculties were not significant (p>0.05). Conclusions: This report revealed the emerging and moderately high prevalence of ESBLs, CR and ESBLs with Co-resistant to Carbapenems GNB with their antibiotic susceptibility patterns found on hands of HCWs in Nepal. Thus, this study could be helpful in developing proper guidelines on hand hygiene and implementation of infection control measures including contact precautions against the spread of infections by such pathogens in healthcare settings

Mid-Late Holocene climatic variations in Trans-Himalaya, Ladakh, NW India

Abstract HKT-ISTP 2013 B

Urea-Fibrinogen Slide Coagulase Test – A Simple Alternative Method for the Rapid Identification of Staphylococcus aureus

Introduction: The accurate identification of Staphylococcus aureus clinical isolates requires a series of tests. Morphological features and slide coagulase test are two criteria on which S. aureus are identified. Resort to tube coagulase test is sought when results of slide coagulase test are equivocal or doubtful. Both coagulase tests detect the enzymes that convert fibrinogen into fibrin. Human, rabbit or sheep pooled plasma is used as substrate for both tests. Slide coagulase test is simpler and faster as compared to tube coagulase test. The plasma could be carrier of many human and animal pathogens like HIV, HBV, HCV etc. Storage of plasma for longer duration is fraught with chances of contamination. Improperly stored plasma can lead to false positive or negative results. Citrated plasma may be unsuitable for this test if contaminated with citrate utilizing bacteria. Considering the role of S. aureus as a common etiological agent in nosocomial and community infections, there is a need of implementing rapid, easy and cost-effective phenotypic test. Objectives: Considering the disadvantages and risks associated with fresh plasma, this study aims to launch for safer, more reliable substitute with longer shelf life that may provide reliable results for prompt identification of S. aureus by slide coagulase test. Methods: The present work evaluates slide coagulase test (SCT), and urea fibrinogen slide coagulase test (UF-SCT) for S. aureus detection considering Tube coagulase test (TCT) as the reference method. Sensitivity, specificity, positive predictive value and negative predictive values of SCT and UF-SCT were calculated using TCT as gold standard. Results: A total of 150 staphylococcal isolates from different clinical specimens ere selected for the evaluation of coagulase tests. All the specimens were subjected to SCT, UF-SCT and TCT. The UF-SCT showed better sensitivity (95.04%), specificity (100%), PPV (100%), and NPV (82.85%) with reference to TCT. UF-SCT showed similar sensitivity and specificity to SCT. None of the isolates were negative in UF-SCT and positive in SCT. Since UF-SCT does not incorporate plasma directly and at the same time has a very good sensitivity and specificity, it is recommended that UF-SCT could replace SCT for identification of S. aureus. Conclusion: The findings of present study shall encourage laboratories to use the urea-fibrinogen slide coagulase test routinely for the rapid identification of S aureus. Journal of Gandaki Medical College   Vol. 10, No. 1, 2017, Page: 5-1

Fecal carriage of Extended Spectrum β-Lactamases (ESBL) Producing Escherichia coli and Klebsiella spp. among School Children in Pokhara, Nepal

Extended-spectrum β-lactamases (ESBL) producing microbes in recent years have been a major problem in developing countries like Nepal, with limited treatment options. This study aimed to determine the prevalence of ESBL producing E. coli and Klebsiella spp. in school children in Pokhara, Nepal. The study was conducted from June to October, 2015 at the microbiology laboratory of Manipal Teaching Hospital, Pokhara, Nepal. Antibiotic Susceptibility Test (AST) was done after isolation and identification of bacterial isolates. Then, presence of ESBL enzymes in E. coli and Klebsiella spp. were tested by combination disc diffusion test using cefotaxime and ceftazidime alone and with clavulanic acid. Out of total 309 school children, 211 (68%) bacterial isolates were detected from stool samples. Among them, E. coli and Klebsiella spp. were detected in 97 (46%) and 39 (19%) stool samples respectively. Bacteria isolated from 14 (5%) stool samples were multi-drug resistant (MDR) positive. After applying combined disk method, 88 (29%) isolates were found to be ESBL producer. Emerging prevalence rate of ESBL producing E. coli and Klebsiella spp. are major problem in medical history. Therefore, rapid need of surveillance for effective management of such MDR-strain is required

Antibiotic Susceptibility Profile of respiratory pathogens obtained at tertiary care hospital from western Nepal

The prevalence and drug resistance of the respiratory pathogens is increasing gradually in Nepal. However, their detail study is rare in the western region of Nepal. Hence, this study was carried out to know the incidence and antibiotic susceptibility profile of the respiratory pathogens obtained at a tertiary care center located at Pokhara. 139 pathogens were isolated from 460 clinical samples included. Significant pathogens were Gram-negative bacteria 94 (67.62%), followed by 28 (20.15%) Candida, and Gram-positive isolates 17 (12.23%). The growth rate was significantly higher for sputum samples in comparison to throat swabs. Pseudomonas aeruginosa, Klebsiella pneumoniae, and Acinetobacter were significant Gram-negative isolates while Staphylococcus aureus, Streptococcus pneumoniae, and Streptococcus pyogenes were Gram-positive pathogens. Sensitivity rate was higher for colistin and imipenem among Gram-negative isolates while lower sensitivity was for cefepime. Vancomycin was effective against all tested Gram-positive isolates while erythromycin and ciprofloxacin were less effective

Burden of Serious Bacterial Infections and Multidrug-Resistant Organisms in an Adult Population of Nepal: A Comparative Analysis of Minimally Invasive Tissue Sampling Informed Mortality Surveillance of Community and Hospital Deaths.

BACKGROUND: Bacterial diseases are the leading cause of mortality globally, and due to haphazard use of antibiotics, antimicrobial resistance has become an emerging threat. METHODS: This cross-sectional observational study utilized a minimally invasive tissue sampling procedure to determine the cause of death among an adult population. Bacterial cultures (blood, cerebrospinal fluid, lung tissue) and antibiotic susceptibility were evaluated, and the results were compared between community and hospital deaths. RESULTS: Of 100 deceased persons studied, 76 (76%) deaths occurred in the community and 24 (24%) in the hospital. At least 1 bacterial agent was cultured from 86 (86%) cases; of these, 74 (86%) had a bacterial disease attributed as the primary cause of death, with pneumonia (35, 47.3%), sepsis (33, 44.6%), and meningitis (3, 4.1%) most common. Of 154 bacterial isolates (76.6% from the community and 23.4% from the hospital) detected from 86 culture-positive cases, 26 (16.8%) were multidrug-resistant (MDR). Klebsiella species were the most common (13 of 26) MDR organisms. The odds of getting an MDR Klebsiella infection was 6-fold higher among hospital deaths compared with community deaths (95% confidence interval [CI], 1.37-26.40; P = .017) and almost 23-fold higher (CI, 2.45-213.54; P = .006) among cases with prior antibiotic use compared to those without. CONCLUSIONS: High incidence of serious bacterial infections causing death of adults in the community, with most MDR organisms isolated from hospitalized cases, calls for robust surveillance mechanisms and infection prevention activities at the community level and evidence-driven antibiotic stewardship in healthcare settings

Disseminated cryptococcosis in a deceased with HIV-1 diagnosed by minimally invasive tissue sampling technique.

Minimal invasive tissue sampling (MITS) technique detected HIV infection and disseminated cryptococcosis in an adult female with sudden death. A proper autopsy is essential to diagnose the exact cause of death and MITS can suffice in natural deaths

Bacteriological profile and antimicrobial susceptibility patterns of wound infections among adult patients attending Gandaki Medical College Teaching Hospital, Nepal

Introduction: Wound infections are significant group of infections in the hospitals worldwide. The wide spread uses of antimicrobial agents lead to emergence of resistant pathogens contributing to increased morbidity and mortality. Accurate and prompt antimicrobial therapy is required to reduce the complications. This study was aimed to investigate pyogenic bacterial pathogens and their susceptibility patterns. Methods: A cross sectional study was carried out at Gandaki Medical College Teaching Hospital from July to December 2018. Wound specimens obtained from adult patients were inoculated onto appropriate media and pathogens were identified using standard microbiological methods. Antimicrobial susceptibility patterns were determined by Kirby-Bauer disc diffusion method following the guidelines of Clinical and Laboratory Standard Institute (CLSI). Results: A total of 264 specimens were included in the study of which 167 (63.3%) were positive for bacterial growth. Of these, polymicrobial growth was observed in two specimens. Gram positive bacteria (119, 70.4%) were the leading cause of infections, Staphylococcus aureus (102, 85.7%) being the most dominant. Among the Gram negative pathogens (50, 29.6%), Escherichia coli (31,62%) was found to be the predominant followed by Pseudomonas aeurogenosa (10, 20%). Overall, the isolates were resistance to Ampicillin (90.7%), Amoxycillin (64.9%), Cloxacillin (68%), Ofloxacin (61.5%) and Cotrimoxazole (55.6%). Lesser rates of resistance were observed to Doxycycline, Erythromycin, Amikacin, Gentamicin and Imipenem. Conclusion: This study revealed the most common pathogens causing pyogenic wound infections in our setting. Again, these pathogens are resistance to commonly used antibiotics. Therefore, this study could be helpful to develop proper guidelines of antibiotics to be used for prophylactic and empiric treatment