Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia’s National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.
Two national surveys of vision impairment and blindness were undertaken in The Gambia in 1986 and 1996. These provided data for the inception of The Gambia’s National Eye Health Programme (NEHP) within the Ministry of Health and Social Welfare. There have been important developments in the eye health services provided by the NEHP in the last 20 years. At the same time, the population has also undergone major demographic changes that may have led to substantial changes in the burden of eye disease. We conducted a National Eye Health Survey of vision impairment, blindness and its comorbidities in adults in The Gambia in 2019. We examined a nationally representative population-based sample of adults 35 years and above to permit direct comparison with the data available from the previous surveys. Alongside a comprehensive vision and eye examination, the survey provides nationally representative data on important comorbidities in this population: diabetes, hypertension, obesity, hearing impairment, disability and mental health. Secondly, it estimates access to assistive technologies and eye health services. Thirdly, it is powered to allow a five-year follow up cohort study to measure the incidence and progression of eye disease.
TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractWith vast regions of the Gulf of Mexico (GOM) rapidly becoming mature provinces, operators are constantly looking for ways to systematically reduce the costs of drilling development wells, especially with improved technologies that deliver reliable performance and decreased risk.The application of a new steel tooth rollercone bit with a technically advanced metal seal bearing has achieved this goal and is having a significant impact on drilling economics in the GOM. Improvements in bearing life, seal reliability and cutting structure durability have resulted in more time on bottom, thereby giving the operator the confidence to apply the new rollercone bits in long directional hole sections. Most of the wells drilled are directional, and heavy water-based drilling fluids are often required in the intermediate hole sections; heavy synthetic muds are sometimes used deep in the wellbore. Relatively high bottomhole temperatures combine with extremely high bottomhole pressures and balling shales to present a challenging drilling environment. Operators strive to increase rate of penetration, maximize hours on bottom for each bit, reduce risk, and complete the section with fewer bits to reduce the number of trips.The bit development phase consisted of a thorough analysis of field application data, along with rigorous forensic examinations of representative dulls from around the world to identify the downhole conditions and sealed bearing wear mechanisms that limited the current metal sealed bit life. A host of design and material improvements were conceived and developed to deliver an improved metal sealed bearing with significantly longer life and higher reliability.The improvements included metal seal surfaces up to 20% wider; a proprietary wear resistant surface on one seal face that greatly reduced both the seal wear rate and the coefficient of friction; improved back-up ring geometry and gland; and design features that enable more consistent manufacturing assembly processes to be utilized. The new rollercone bearing package proved to deliver unequaled life and reliability in high rotary speed drilling applications, superior to all current rollercone sealed bearing systems.The new steel tooth bit's long life, resistance to balling in water-based muds, highly steerable characteristics, and ability to be combined with various hole-opening systems make it the bit of choice for many GOM applications. The authors show actual GOM performance data of the new bits achieving an 80% reliability of nearly 700,000 total bit revolutions (TBR), compared to existing technology bits at less than 400,000 TBR. Specific case studies show examples of one new style bit replacing two to three current technology steel tooth bits, effectively doubling the footage drilled and TBR in the process. Another example shows 1 of the new technology bits replacing two current technology steel tooth bits with associated substantial cost savings due to higher ROP's and less flat time due one less trip...
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