Search

Sustainable groundwater aquifers are critical in arid and semiarid countries due to the scarcity of surface water and precipitation. Management of groundwater resources requires estimation of aquifer properties and interaction between multilayers in heterogeneous aquifers. A three-dimensional groundwater flow model was implemented to simulate a complex multilayer aquifer in Oman. Steady-state model was calibrated using groundwater level data in July 2016. Both the automated parameter calibration technique and manual trial and error method were applied for calibrating hydraulic conductivity, groundwater recharge, and anisotropy of soil layers. The optimum set of parameters of 14 observation wells was obtained from the simulation with minimum root mean square error of 0.8 m for groundwater water level. The calibrated model was validated using measured data for October 2016, and root mean square error was found to be 0.81 m for groundwater water level. Among the observation wells which were used in the above analysis, 4 of them were directed to different aquifer depths and each two observation wells were in the same location. These two sets of wells, therefore, were used for analyzing interactions among different aquifer layers. Results showed that increased pumping rates enhanced water transfer between multilayers due to increased hydraulic gradient. The effect was more dominant in layers with high vertical hydraulic conductivity. Also, the sensitivity analysis was performed and results indicated that the predicted water level was less sensitive to vertical anisotropy. The findings of this study could be useful for decision-makers for better management of groundwater resources in arid regions. [ABSTRACT FROM AUTHOR]

Site characterization was carried out for Muscat region using the ambient noise measurements applying the horizontal-to-vertical spectral ratio (HVSR) technique and using active seismic survey utilizing the multichannel analysis of surface waves (MASW) of survey data. Microtremors measurements were carried out at 459 sites using short-period sensors. This extensive survey allowed the fundamental resonance frequency of the soft soil to be mapped and areas prone to site amplification to be identified. The results indicate a progressive decrease in the fundamental resonance frequencies from the southern and eastern parts, where the bedrock outcrops, toward the northern coast where a thickness of sedimentary cover is present. Shear wave velocity (Vs) was evaluated using the 2-D MASW at carefully selected 99 representative sites in Muscat. These 99 sites were investigated with survey lines of 52 m length. 1-D and interpolated 2-D profiles were generated up to a depth range 20–40 m. The vertical Vs soundings were used in the SHAKE91 software in combination with suitable seismic input strong motion records to obtain the soil effect. Most of the study area has amplification values less than 2.0 for all the considered spectral periods. The estimated fundamental frequencies obtained using the H/V spectral ratio method and using SHAKE91 are found to be in a relatively good agreement. Maps of spectral amplification, earthquake characteristics on the ground surface for peak ground and spectral accelerations at 0.1, 0.2, 0.3, 1.0, and 2.0 s, for 475 years return period are produced. The surface ground motion maps show that the hazard level is moderate with expected PGA in the range 0.059–0.145 g for 475 years return period. [ABSTRACT FROM AUTHOR]

This study presents the results of the first probabilistic seismic hazard assessment (PSHA) in the framework of logic tree for Oman. The earthquake catalogue was homogenized, declustered, and used to define seismotectonic source model that characterizes the seismicity of Oman. Two seismic source models were used in the current study; the first consists of 26 seismic source zones, while the second is expressing the alternative view that seismicity is uniform along the entire Makran and Zagros zones. The recurrence parameters for all the seismogenic zones were determined using the doubly bounded exponential distribution except the zones of Makran, which were modelled using the characteristic distribution. Maximum earthquakes were determined and the horizontal ground accelerations in terms of geometric mean were calculated using ground-motion prediction relationships developed based upon seismic data obtained from active tectonic environments similar to those surrounding Oman. The alternative seismotectonic source models, maximum magnitude, and ground-motion prediction relationships were weighted and used to account for the epistemic uncertainty. Hazard maps at rock sites were produced for 5 % damped spectral acceleration (SA) values at 0.1, 0.2, 0.3, 1.0 and 2.0 s spectral periods as well as peak ground acceleration (PGA) for return periods of 475 and 2,475 years. The highest hazard is found in Khasab City with maximum SA at 0.2 s spectral period reaching 243 and 397 cm/s for return periods 475 and 2,475 years, respectively. The sensitivity analysis reveals that the choice of seismic source model and the ground-motion prediction equation influences the results most. [ABSTRACT FROM AUTHOR]

Aim: As Coronavirus Disease-2019 (COVID-19) pandemic continues to evolve, the search for safe and effective therapeutic interventions remain essential., Methods: We conducted a retrospective cohort study on patients hospitalized with laboratory confirmed severe acute respiratory syndrome coronavirus-2 infection, comparing standard of care along with Convalescent Plasma with or without Tocilizumab (CP vs. CPT)., Results: A total of 110 patients were enrolled with an overall mean age of 50 ± 16 years. Patients on CPT were more likely to have had acute respiratory distress syndrome (77% vs. 42%; p < 0.001), sepsis (9.7% vs. 0; p = 0.036), chest X-ray abnormalities (71% vs. 44%; p = 0.004), intensive care unit admission (84% vs. 56%; p = 0.001) as well as being on mechanical ventilation (79% vs. 48%; p = 0.001). After CPT treatment, all measured inflammatory markers, except interleukine-6, showed an overall steady decline over time (all p -values <0.05) and the ventilatory parameters showed significant improvement of PaO 2 /FiO 2 ratio from 127 to 188 within 7 days ( p < 0.001). Additionally, 52% (32/62) of the patients had favorable outcome, either as improvement of ventilatory parameters or extubation within 14 days of hospitalization. However, mortality rate in those on CPT was higher than those who received CP alone (24% vs. 8.3%; p = 0.041)., Conclusion: In patients with severe COVID-19 infection, using tocilizumab with convalescent plasma is associated with improvement in inflammatory and ventilatory parameters but no effect on mortality. These findings require validation from randomized clinical trials., Competing Interests: The authors declare they have no conflicts of interest., (© 2020 The Authors. Published by Atlantis Press International B.V.)

Background: Bacillus Calmette-Guérin (BCG) vaccine-related complications are frequently observed in children in Oman. There are a few regional studies on BCG complications, but none from Oman., Objective: Evaluate the spectrum of BCG-vaccine related complications and immune status in Omani children., Design: Retrospective cross-sectional study., Setting: Referral tertiary hospital., Methods: Children aged younger than 13 years old and with complications of BCG vaccination recorded from 2006-2018 were included in this study. Clinical characteristics, treatment, immune workup and outcome were reviewed from hospital records., Main Outcome Measures: Different BCG vaccine-related complications categorized by the site of involvement., Sample Size: 226., Results: Of the 226 children had BCG-vaccine related complications, 99% received BCG vaccine immediately after birth. The median age of presentation was 4 months. The most common complication was isolated BCG lymphadenitis (85%, n=192), followed by BCG-related osteomyelitis (10.2%, n=23) and disseminated BCG infection (4.9%, n=11). The median age of presentation of disseminated BCG was 5 months, with different organs involved. Out of 11 children with disseminated BCG infection, 72.7% (n=8) had primary immune deficiency (PID), including chronic granulomatous disease (CGD, n=5), severe combined immunodeficiency (SCID) (n=2); 1 patient had Mendelian susceptibility to mycobacterial disease (IFNGR2 deficiency); 2 patients with PID not yet identified and the 1 with a non-specific PID had blood or saliva samples sent for whole-exome sequencing., Conclusion: Because of the spectrum of BCG vaccine-related complications, including the most severe in children with PID, we suggest that delaying the BCG vaccine from birth to 6 months may prevent disseminated BCG diseases and their complications in children with PID because any PID will have been identified before 6 months. Further studies are needed to guide this recommendation., Limitations: Single center-based study that may not provide a full overview of all BCG vaccine-related complications in Oman. Unavailability of details of some microbiological results and an inability to determine the detailed management for all patients., Conflict of Interest: None.

Introduction: Predominantly, studies on COVID-19 report quantitative data that often miss the social implications and other determinants of health. The objective of this study was to explore the experiences and perceptions of health care workers (HCWs) in primary health care in the management of COVID-19 with respect to medical response experiences, socio-cultural and religious reforms, psychological impressions, and lessons learned., Methods: This was a qualitative study using an empirical phenomenological approach. Six focus group discussions were conducted across various stakeholders working frontline in the management of COVID-19 (managerial, public health/field/community and primary care health centers). They participated in semi-structured, in-depth group discussions from 11th to 20th May 2020. All discussions were audio-recorded, transcribed verbatim and analyzed using thematic analysis., Results: Forty participants were involved in this study. Three themes emerged related to the medical response experiences, including the rapid re-structuring of the PHC services, use of technology and challenges of working on COVID-19. Perceptions on the socio-cultural and religious reforms included changes in social and religious norms, and anticipated gaps in accessing health care among the vulnerable groups (elderly, expatriates, and individuals with low economic status). Perceptions on psychological disturbances were themed as consequences of social distancing, management of dead bodies, exhaustion among the health care workers, and risk of exposure. Finally, lessons learned were centered around building on the existing epidemiological and public health capacities, improving access to health care and overcoming resistance to change. Most participants labelled their experience in COVID-19 as an "experience of wisdom" in which learning was a continuous process., Conclusion: This qualitative study amongst primary HCWs revealed certain aspects of response to COVID-19 in Muscat, Oman. Results has unfolded various aspects of COVID-19. The situation was perceived by primary HCWs as a new experience that challenged the primary health care; enforced the utilization of public health/epidemiological skills, and linked to unfavorable socio-religious and psychological events.

Background: The aim of this study was to investigate the degree of sterility of some fruit juices post manufacture and to determine how effective the preservatives in them aid the killing of some microorganisms introduced into them., Material/methods: Blackcurrant/raspberry, apple, guava, orange, mango, and mixed fruits were each checked for sterility by inoculating 100 microl separately in tryptone soy broth, Robertson's cooked meat, and Sabouraud broth and incubating for growth for 72 hours at 37 degrees C. Twenty-milliliter aliquots of each juice were subsequently kept in a 37 degrees C water bath and inoculated separately with S. aureus, P. aeruginosa, E. coli, and C. albicans. At predetermined time intervals, a 1:250 dilution of each juice with the individual organism was made and the dilutions were plated on blood and Sabouraud plates for viable counts. Each 1:250 dilution was then incubated along with the plates. The pH of each undiluted juice was determined., Result: All the juices were found to be sterile. The growth inhibition exhibited by each juice was bactericidal or bacteriostatic, fungicidal or fungistatic, depending on the type of juice. The p[H of the juices varied from 2.53-3.75., Conclusions: We found the juices to be bacteriologically free of organisms associated with food infection. Though the juices were sterile, they could allow the survival of some bacteria and yeasts if these gained access into them. We found the orange, blackcurrant/raspberry, and mango juices to be bactericidal and fungicidal, while pineapple, mixed fruit, and guava were fungistatic, though with varying bactericidal activities.

Aim: To determine the presence of HLA antigens in people with blinding trachoma., Methods: Fifty Omanis with blinding trachoma were serologically typed for HLA A, B, C, DR, and DQ antigens and DNA typed for class II DR beta and DQ beta alleles and compared with a population of 100 healthy controls., Results: chi 2 analysis of serological reactions did not reveal any significant differences in HLA antigen frequencies after correction of probability, although DR4, DR7, and DR53 were completely absent in the patients and all of the patients were HLA DQ1 positive. In the case of DQ1 the relative risk was 22.6 (95% confidence interval of 20.7-24.7). Class II DNA low resolution DR beta typing showed a significant increase in HLA DR16 (pc = 0.036, relative risk = 3.8) and a significant decrease in HLA DR53 (pc = 0.018, relative risk = 0.05)., Conclusion: The finding that HLA DR16 (a DR2 subtype) is associated with susceptibility to blinding trachoma, a disease that is caused by an intracellular micro-organism, is consistent with reports of an HLA DR2 association with leprosy and tuberculosis, diseases also caused by an intracellular micro-organism. Similarly, resistance to leprosy is associated with HLA DR53 as is the case with blinding trachoma described here. It is postulated that HLA DR2 or subtypes in association with HLA DQ 1 may enable an intracellular micro-organism to enter the cell or are involved in presentation of peptides derived from intracellular micro-organisms to T lymphocytes initiating a delayed hypersensitivity or autoimmune reaction. These findings are the first report that genetic factors are of major importance in the development and protection against blinding trachoma.