Background:In 2009 Ghana began to design a trachoma pre-validation surveillance plan,based on then-current WHO recommendations.The plan aimed to identify active trachoma resurgence and identify and manage trichiasis c...Background:In 2009 Ghana began to design a trachoma pre-validation surveillance plan,based on then-current WHO recommendations.The plan aimed to identify active trachoma resurgence and identify and manage trichiasis cases,through both active and passive surveillance approaches.This paper outlines and reviews the adaptations made by Ghana between 2011 and 2016.The assessment will provide a learning opportunity for a number of countries as they progress towards elimination status.Methods:A mixed methods approach was taken,comprising in-depth interviews and documents review.Between January and April 2016,20 in-depth interviews were conducted with persons involved in the operationalisation of the trachoma surveillance system from across all levels of the health system.A three-tier thematic coding framework was developed using a primarily inductive approach but also allowed for a more iterative approach,which drew on aspects of grounded theory.Results:During the operationalisation of the Ghana surveillance plan there were a number of adaptations(as compared to the WHO recommendations),these included:(i)Inclusion of surveillance of active trachoma in the passive surveillance approach,as compared to trichiasis alone.Issues with case identification,challenges in implementation coverage and a non-specific reporting structure hampered effectiveness;(ii)Random selection and increase in number of sites selected for the active surveillance component.This likely lacked the spatiotemporal power to be able to identify recrudescence in a timely manner;(iii)Targeted trichiasis door-to-door case searches,led by ophthalmic nurses.An effective methodology to identify trichiasis cases but resource intensive;(iv)A buddy system between ophthalmic nurses to support technical skills in an elimination setting where it is difficult to attain diagnostic and surgical skills,due to a lack of cases.The strategy did not take into account the loss of proficiency within experienced personnel.Conclusions:Ghana developed a comprehensive surveillance system that exceeded the WHO recommendations but issues with sensitivity and specificity likely led to an inefficient use of resources.Improved targeted surveillance strategies for identification of recrudescence and trichiasis case searches,need to be evaluated.Strategies must address the contextual changes that arise because of transmission decline,such as loss of surgical skills.展开更多
A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environment...A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.展开更多
文摘Background:In 2009 Ghana began to design a trachoma pre-validation surveillance plan,based on then-current WHO recommendations.The plan aimed to identify active trachoma resurgence and identify and manage trichiasis cases,through both active and passive surveillance approaches.This paper outlines and reviews the adaptations made by Ghana between 2011 and 2016.The assessment will provide a learning opportunity for a number of countries as they progress towards elimination status.Methods:A mixed methods approach was taken,comprising in-depth interviews and documents review.Between January and April 2016,20 in-depth interviews were conducted with persons involved in the operationalisation of the trachoma surveillance system from across all levels of the health system.A three-tier thematic coding framework was developed using a primarily inductive approach but also allowed for a more iterative approach,which drew on aspects of grounded theory.Results:During the operationalisation of the Ghana surveillance plan there were a number of adaptations(as compared to the WHO recommendations),these included:(i)Inclusion of surveillance of active trachoma in the passive surveillance approach,as compared to trichiasis alone.Issues with case identification,challenges in implementation coverage and a non-specific reporting structure hampered effectiveness;(ii)Random selection and increase in number of sites selected for the active surveillance component.This likely lacked the spatiotemporal power to be able to identify recrudescence in a timely manner;(iii)Targeted trichiasis door-to-door case searches,led by ophthalmic nurses.An effective methodology to identify trichiasis cases but resource intensive;(iv)A buddy system between ophthalmic nurses to support technical skills in an elimination setting where it is difficult to attain diagnostic and surgical skills,due to a lack of cases.The strategy did not take into account the loss of proficiency within experienced personnel.Conclusions:Ghana developed a comprehensive surveillance system that exceeded the WHO recommendations but issues with sensitivity and specificity likely led to an inefficient use of resources.Improved targeted surveillance strategies for identification of recrudescence and trichiasis case searches,need to be evaluated.Strategies must address the contextual changes that arise because of transmission decline,such as loss of surgical skills.
基金Project(20030533011)supported by the National Research Foundation for the Doctoral Program of Higher Education of China
文摘A DMVOCC-MVDA （distributed multiversion optimistic concurrency control with multiversion dynamic adjustment） protocol was presented to process mobile distributed real-time transaction in mobile broadcast environments. At the mobile hosts, all transactions perform local pre-validation. The local pre-validation process is carried out against the committed transactions at the server in the last broadcast cycle. Transactions that survive in local pre-validation must be submitted to the server for local final validation. The new protocol eliminates conflicts between mobile read-only and mobile update transactions, and resolves data conflicts flexibly by using multiversion dynamic adjustment of serialization order to avoid unnecessary restarts of transactions. Mobile read-only transactions can be committed with no-blocking, and respond time of mobile read-only transactions is greatly shortened. The tolerance of mobile transactions of disconnections from the broadcast channel is increased. In global validation mobile distributed transactions have to do check to ensure distributed serializability in all participants. The simulation results show that the new concurrency control protocol proposed offers better performance than other protocols in terms of miss rate, restart rate, commit rate. Under high work load （think time is ls） the miss rate of DMVOCC-MVDA is only 14.6%, is significantly lower than that of other protocols. The restart rate of DMVOCC-MVDA is only 32.3%, showing that DMVOCC-MVDA can effectively reduce the restart rate of mobile transactions. And the commit rate of DMVOCC-MVDA is up to 61.2%, which is obviously higher than that of other protocols.
