Interobserver variation in histopathological assessment of Helicobacter pylori gastritis

AIM:Because the presence or absence of H pylori infection has important implications for therapeutic decisions based on histological assessment,the reproducibility of Sydney system is important.The study was designed to test the reproducibility of features of Helicobacter pylori gastritis, using the updated Sydney classification. METHODS:Gastric biopsies of 40 randomly selected cases of H pylori gastritis were scored semiquantitatively by three pathologists.Variables analysed induded chronic inflammation, inflammatory activity,atrophy,intestinal metaplasia,H pylori, surface epithelial damage.κ values below 0.5 represented poor,those between 0.5 and 0.75 good and values over 0.75 excellent interobserver agreement. RESULTS:The best interobserver agreement(κ=0.62)was present for intestinal metaplasia.The agreement was the poorest for evaluating atrophy(κ=0.31). CONCLUSION:Although the results of this study were in accordance with some previous studies,an excellent agreement could not be reached for any features of H pylori gastritis.This low degree of concordance is assumed to be due to the personal evaluation differences in grading the features,the lack of standardized diagnostic criteria,and the ignorance to reach a consensus about the methods to be used in grading the features of H pylori gastritis before initiating the study.

Interobserver reliability of computed tomography angiography in the assessment of ruptured intracranial aneurysm and impact on patient management

BACKGROUND Aneurysmal subarachnoid hemorrhage is an emergency that can lead to a high mortality rate and many severe complications.It is critical to make a rapid radiological evaluation of ruptured intracranial aneurysms(RIAs)to determine the appropriate surgical treatment.AIM To assess the reliability of computed tomography angiography(CTA)in assessing different features of ruptured intracranial aneurysm and its impact on patient management.METHODS The final cohort of this study consisted of 146 patients with RIAs(75 male and 71 female)who underwent cerebral CTA.Their age ranged from 25 to 80,and the mean age±SD was 57±8.95 years.Two readers were asked to assess different features related to the aneurysm and perianeurysmal environment.Inter-observer agreement was measured using kappa statistics.Imaging data extracted from non-contrast computed tomography and CTA were considered to categorize the study population into two groups according to the recommended therapeutic approach.RESULTS The inter-observer agreement of both reviewers was excellent for the detection of aneurysms(K=0.95,P=0.001),aneurysm location(K=0.98,P=0.001),and(K=0.98,P=0.001),morphology(K=0.92,P=0.001)and margins(K=0.95,P=0.001).There was an excellent interobserver agreement for the measurement of aneurysm size(K=0.89,P=0.001),neck(K=0.85,P=0.001),and dome-to-neck ratio(K=0.98,P=0.001).There was an excellent inter-observer agreement for the detection of other aneurysm-related features such as thrombosis(K=0.82,P=0.001),calcification(K=1.0,P=0.001),bony landmark(K=0.89,P=0.001)and branch incorporation(K=0.91,P=0.001)as well as perianeurysmal findings including vasospasm(K=0.91,P=0.001),perianeurysmal cyst(K=1.0,P=0.001)and associated vascular lesions(K=0.83,P=0.001).Based on imaging features,87 patients were recommended to have endovascular treatment,while surgery was recommended in 59 patients.71.2%of the study population underwent the recommended therapy.CONCLUSION CTA is a reproducible promising diagnostic imaging modality for detecting and characterizing cerebral aneurysms.

Variations of temperature, salinity and current in the southern tidal passage of the Hangzhou Bay, China

Field surveys covering a spring-neap tidal period were conducted to investigate the characteristics of tidal dynamics within a curved channel in the southern Hangzhou Bay, China. The channel has a maximum depth of more than 100 m with an average tidal range of 2.5 m, serving as the main tidal passage in the southern part of the Hangzhou Bay. Water salinity, temperature and velocity data were collected from the ship-based transects and mooring measurements. During flood tide, the tidal current intrudes into the Hangzhou Bay through the northern side of the channel with a maximum velocity of about 2 m/s, while retreats through the southern side during ebb tide with a maximum velocity of 1.8 m/s. Due to the pressure, density gradients, the Coriolis force and centrifugal effect, a lateral exchange flow is generated as the tidal current relaxes from flood to ebb. Salinity and temperature data show that the water in the channel is weakly stratified during both spring and neap tides in summer time.However, mixing in the middle region will be enhanced by the lateral circulation. Mooring data indicate that the temperature and salinity are varying at a frequency similar to tidal current but higher than sea level oscillation.Our results support the hypothesis that the high frequency salinity and temperature variations could be generated by combination of the tidal current and the lateral exchanging flow.

Adaptive backstepping control for levitation system with load uncertainties and external disturbances

To explore the precise dynamic response of the levitation system with active controller, a maglev guide way-electromagnet-air spring-cabin coupled model is derived firstly. Based on the mathematical model, it shows that the inherent nonlinearity, inner coupling, misalignments between the sensors and actuators, load uncertainties and external disturbances are the main issues that should be solved in engineering. Under the assumptions that the loads and external disturbance are measurable, the backstepping module controller developed in this work can tackle the above problems effectively. In reality, the load is uncertain due to the additions of luggage and passengers, which will degrade the dynamic performance. A load estimation algorithm is introduced to track the actual load asymptotically and eliminate its influence by tuning the parameters of controller online. Furthermore,considering the external disturbances generated by crosswind, pulling motor and air springs, the extended state observer is employed to estimate and suppress the external disturbance. Finally, results of numerical simulations illustrating closed-loop performance are provided.

Analysis of the characteristics of offshore currents in the Changjiang(Yangtze River) estuarine waters based on buoy observations

A buoy of 10 m in diameter was used to record the current speed and direction in a vertical profile in the offshore area of the Changjiang（Yangtze River） Estuary（with an average water depth of 46.0 m） for one year.The results include：（1） the currents rotate clockwise and the current direction is consistent in a vertical profile without clear seasonal variations.（2） The horizontal current speeds are generally high,with a maximum of 128.5 cm/s occurring in summer and 105.5 cm/s appearing in winter commonly close to the surface.The average current speeds in the vertical profile fall in the same range（the differences are less than 8.0 cm/s）,with the maximum of47.0 cm/s occurring in summer and 40.8 cm/s in winter.The average current speed during spring tides is twice that during neap tides（26.5 cm/s）.（3） Significant differences of speeds are observed in the vertical profile.The maximum current speed occurs at either surface（spring and winter） or sub-surface（summer and autumn）,with the minimum current speed appearing at the bottom.The maximum average current speed of all layers is 57.9cm/s,which occurs in the 18-m layer during summer.（4） The average speed of the residual currents ranges from7.5 cm/s to 11.3 cm/s,with the strongest occurring in spring and weakest in winter.The residual currents of all layers are eastward during spring and winter,whereas northeastward or northward during summer and autumn.（5） The currents in the offshore of Changjiang Estuary are impacted collectively by diluted Changjiang River discharge,the Taiwan Warm Current,monsoon and tides.