BACKGROUND Retrograde single balloon enteroscopy(SBE)is a minimally invasive procedure which is less frequently performed compared with antegrade SBE.There are few studies on the retrograde through-the-scope enterosco...BACKGROUND Retrograde single balloon enteroscopy(SBE)is a minimally invasive procedure which is less frequently performed compared with antegrade SBE.There are few studies on the retrograde through-the-scope enteroscopy(TTSE),a novel technique for evaluation of the small bowel.AIM To compare the clinical utility and safety of retrograde TTSE with retrograde SBE.METHODS Clinical data and complications of retrograde TTSE(2014-2018)and retrograde SBE(2011-2018)performed in a community hospital were reviewed and presented as mean±SD or frequency(%)and compared using proper statistical tests.Technical success was defined as insertion of the enteroscope>20 cm beyond ileocecal valve.RESULTS Data obtained from 54 retrograde SBE in 49 patients and 27 retrograde TTSE in 26 patients were studied.The most common indication for retrograde enteroscopy was iron deficiency anemia(41 patients)followed by gastrointestinal bleeding(37 patients),and chronic diarrhea(7 patients).The duration of retrograde SBE procedure(91.9±34.2 min)was significantly longer compared with retrograde TTSE(70.5±30.7 min)(P=0.04).Technical success was comparable in TTSE[23/27(85.2%)]and SBE[41/54(75.9%)(P=0.33)].The mean depth of insertion beyond the ileocecal valve in retrograde SBE(92.5±70.0 cm)tended to be longer compared with retrograde TTSE(64.6±49.0 cm)(P=0.08).No complication was observed in this study.CONCLUSION Both retrograde TTSE and retrograde SBE are feasible and safe.Retrograde TTSE takes a shorter time and has a comparable technical success with SBE.TTSE has a lower capacity of small bowel insertion.展开更多
Coffee is one of the world most traded agricultural commodities. Currently, a lot of attention has been on Robusta coffee (Coffea canephora Pierre ex A. Froehner) because it seems to evidence a greater tolerance to ex...Coffee is one of the world most traded agricultural commodities. Currently, a lot of attention has been on Robusta coffee (Coffea canephora Pierre ex A. Froehner) because it seems to evidence a greater tolerance to extreme climatic events than Arabica coffee (C. arabica L.). Despite this, only a few works have been developed aimed at discriminating the climatic vulnerability in regions which prioritize robust coffee production. The aim of this work was to analyze historical climatic variables in space and time for the characterization of climatic vulnerability of micro-regions, in search of mitigation and adaptation, which might support the improvement of production systems of C. canephora coffee trees. The case study was carried out for one of the largest production regions of Robusta coffee of the world, in Brazil, geographically located between the 39°38' and 41°50' West longitude meridians and the 17°52' and 21°19' South latitude parallels. The vulnerability was characterized by the spatial and temporal variation of rainfall and rainfall seasonal pattern (based on 30 years of historical data), elements of climatic water balance, elevation and area planted with Robusta coffee. The choice of mitigation and adaptation were based on widely validated criteria. Overall, the results show that the vulnerability of Robusta coffee is related to low index of rainfall, the rainfall seasonability and the water deficiency. In the studied region, there is approximately 42% of some type of water vulnerability during the year, with a severe to medium scale;this vulnerability is very pronounced in regions farther away from the coast of the Atlantic Ocean, since for a year approximately 92% of them are water deficient. In addition, the data show that this distance from the ocean implies a reduction of 75% in the phases of water surplus not only. The strategies of greater potential for adaptation and mitigation are related to the planting of improved genotypes, utilization of polycultures systems, increasing plant density, the implementation of irrigation systems and the management of spontaneous plants.展开更多
In simulations of fluidized beds using computational fluid dynamics （CFD）, the description of gas-solid flow hydrodynamics relies on a drag model to account for the momentum transfer between gas and solid phases. Al...In simulations of fluidized beds using computational fluid dynamics （CFD）, the description of gas-solid flow hydrodynamics relies on a drag model to account for the momentum transfer between gas and solid phases. Although several studies of drag models have been published, there have been few investigations of the application of lattice Boltzmann method （LBM）-based drag models to bubbling fluidized bed simu- lations. In the present study, a comprehensive comparison of empirical and LBM-based drag models was carried out to assess the performance of these models during simulations of gas-solid flow hydrodynam- ics in a bubbling fluidized bed. A CFD model using the MFIX code based on the Eulerian-Eulerian approach and the kinetic theory of granular flow was used to simulate a 2D bubbling fluidized bed with Geldart B particles. The simulation results were validated by comparison with experimental data. Statistical anal- ysis of the results shows that LBM-based drag models can reliably model gas-solid flow hydrodynamics in a bubbling fluidized bed.展开更多
基金The study was approved by the Texas Tech University Health Sciences Center Institutional Review Board(Approval Number.E14078).
文摘BACKGROUND Retrograde single balloon enteroscopy(SBE)is a minimally invasive procedure which is less frequently performed compared with antegrade SBE.There are few studies on the retrograde through-the-scope enteroscopy(TTSE),a novel technique for evaluation of the small bowel.AIM To compare the clinical utility and safety of retrograde TTSE with retrograde SBE.METHODS Clinical data and complications of retrograde TTSE(2014-2018)and retrograde SBE(2011-2018)performed in a community hospital were reviewed and presented as mean±SD or frequency(%)and compared using proper statistical tests.Technical success was defined as insertion of the enteroscope>20 cm beyond ileocecal valve.RESULTS Data obtained from 54 retrograde SBE in 49 patients and 27 retrograde TTSE in 26 patients were studied.The most common indication for retrograde enteroscopy was iron deficiency anemia(41 patients)followed by gastrointestinal bleeding(37 patients),and chronic diarrhea(7 patients).The duration of retrograde SBE procedure(91.9±34.2 min)was significantly longer compared with retrograde TTSE(70.5±30.7 min)(P=0.04).Technical success was comparable in TTSE[23/27(85.2%)]and SBE[41/54(75.9%)(P=0.33)].The mean depth of insertion beyond the ileocecal valve in retrograde SBE(92.5±70.0 cm)tended to be longer compared with retrograde TTSE(64.6±49.0 cm)(P=0.08).No complication was observed in this study.CONCLUSION Both retrograde TTSE and retrograde SBE are feasible and safe.Retrograde TTSE takes a shorter time and has a comparable technical success with SBE.TTSE has a lower capacity of small bowel insertion.
基金supported by the Universidade Federal do Espirito Santo,by the Portuguese national funds through Fundacao para a Ciencia e Tecnologia,under the scope of the project PTDC/AGR-PRO/3386/2012(JCR)as well through the grants from CNPq(LDM,ARS and MAT),CAPES(LDM in PDSE/12226/12-2)FAPES(FCE,WNR and LDM-under the scope of the project FAPES/CNPq No.012/2014-DCR-No.71444289/15).
文摘Coffee is one of the world most traded agricultural commodities. Currently, a lot of attention has been on Robusta coffee (Coffea canephora Pierre ex A. Froehner) because it seems to evidence a greater tolerance to extreme climatic events than Arabica coffee (C. arabica L.). Despite this, only a few works have been developed aimed at discriminating the climatic vulnerability in regions which prioritize robust coffee production. The aim of this work was to analyze historical climatic variables in space and time for the characterization of climatic vulnerability of micro-regions, in search of mitigation and adaptation, which might support the improvement of production systems of C. canephora coffee trees. The case study was carried out for one of the largest production regions of Robusta coffee of the world, in Brazil, geographically located between the 39°38' and 41°50' West longitude meridians and the 17°52' and 21°19' South latitude parallels. The vulnerability was characterized by the spatial and temporal variation of rainfall and rainfall seasonal pattern (based on 30 years of historical data), elements of climatic water balance, elevation and area planted with Robusta coffee. The choice of mitigation and adaptation were based on widely validated criteria. Overall, the results show that the vulnerability of Robusta coffee is related to low index of rainfall, the rainfall seasonability and the water deficiency. In the studied region, there is approximately 42% of some type of water vulnerability during the year, with a severe to medium scale;this vulnerability is very pronounced in regions farther away from the coast of the Atlantic Ocean, since for a year approximately 92% of them are water deficient. In addition, the data show that this distance from the ocean implies a reduction of 75% in the phases of water surplus not only. The strategies of greater potential for adaptation and mitigation are related to the planting of improved genotypes, utilization of polycultures systems, increasing plant density, the implementation of irrigation systems and the management of spontaneous plants.
文摘In simulations of fluidized beds using computational fluid dynamics （CFD）, the description of gas-solid flow hydrodynamics relies on a drag model to account for the momentum transfer between gas and solid phases. Although several studies of drag models have been published, there have been few investigations of the application of lattice Boltzmann method （LBM）-based drag models to bubbling fluidized bed simu- lations. In the present study, a comprehensive comparison of empirical and LBM-based drag models was carried out to assess the performance of these models during simulations of gas-solid flow hydrodynam- ics in a bubbling fluidized bed. A CFD model using the MFIX code based on the Eulerian-Eulerian approach and the kinetic theory of granular flow was used to simulate a 2D bubbling fluidized bed with Geldart B particles. The simulation results were validated by comparison with experimental data. Statistical anal- ysis of the results shows that LBM-based drag models can reliably model gas-solid flow hydrodynamics in a bubbling fluidized bed.
