Endoscopic diverticulotomy for Killian-Jamieson diverticulum: mid-term outcome and description of an ultra-short tunnel technique

Background and study aims Killian-Jamieson Diverticulum (KJD) is a rarer and more recently described upper pharyngeal diverticulum than Zenker’s diverticulum (ZD). KJD is more difficult to manage than ZD because it tends to extend lower into the upper mediastinum and the diverticulum neck is in close proximity to the recurrent laryngeal nerve. There is limited literature on KJD management and transcervical surgical diverticulectomy is the mainstay of therapy. Patients and methods Here we describe two methods of endoscopic diverticulotomy to treat KJD – direct and tunneling diverticulotomy (with hypopharyngeal tunnel or ultra-short tunnel – the latter being our preferred technique). Results This was a retrospective study including 13 consecutive patients between March 2015 and April 2018. Three patients received direct and 10 received tunneling diverticulotomy (7 with the hypopharyngeal tunnel and 3 with the ultra-short tunnel). All procedures were completed in 16 to 52 minutes. There was no incidence of bleeding, mediastinitis, or sign of recurrent laryngeal nerve injury. At follow up of 9 to 79 months (median 33), the clinical success rate was 92 % (12/13); 11 patients had complete symptom resolution (post-operative symptom score = 0) and one patient had near-complete symptom resolution (occasional residual dysphagia). One patient receiving direct myotomy had limited symptom relief (frequent residual dysphagia and occasional residual regurgitation), possibly related to incomplete myotomy. Conclusions Endoscopic tunneling diverticulotomy is a feasible, safe, and effective method to treat KJD.

Allostery in the nitric-oxide dioxygenase mechanism of flavohemoglobin

The substrates O2 and NO cooperatively activate the NO dioxygenase function of Escherichia coli flavohemoglobin. Steady-state and transient kinetic measurements support a structure-based mechanistic model in which O2 and NO movements and conserved amino acids at the E11, G8, E2, E7, B10 and F7 positions within the globin domain control activation. In the cooperative and allosteric mechanism, O2 migrates to the catalytic heme site via a long hydrophobic tunnel and displaces LeuE11 away from the ferric iron, which forces open a short tunnel to the catalytic site gated by the ValG8/IleE15 pair and LeuE11, which NO permeates and leverages upon to trigger the CD loop to furl, which moves the E and F-helices and switches an electron transfer gate formed by LysF7, GlnE7 and water, which allows FADH2 to reduce the ferric iron, which forms the stable ferric-superoxide-TyrB10/GlnE7 complex, which reacts with internalized NO with a bimolecular rate constant of 1010 M-1 s-1 forming nitrate, which migrates to the CD loop and unfurls the spring-like structure. To restart the cycle, LeuE11 toggles back to the ferric iron. Actuating electron transfer with O2 and NO movements averts irreversible NO poisoning and reductive inactivation of the enzyme. Together, structure snapshots and kinetic constants provide glimpses of intermediate conformational states, time scales for motion, and associated energies.

Variations in Naturalistic Driving Behavior and Visual Perception at the Entrances of Short, Medium, and Long Tunnels

Driver behavior and visual perception are very important factors in the management of traffic accident risk at tunnel entrances. This study was undertaken to analyze the differences in driving behavior and visual perception at the entrances of three types of tunnels, namely, short, medium-length, and long tunnels, under naturalistic driving conditions. Using three driving behavior indicators (speed, deceleration, and position) and two visual perception indicators (fixation and saccade), the driving performance of twenty drivers at six tunnels (two tunnels per condition) was comparatively analyzed. The results revealed that the speed maintained by the drivers prior to deceleration with braking under the short-tunnel condition was significantly larger than that under the medium- and long-tunnel conditions and that the drivers had a greater average and maximum deceleration rates under the short-tunnel condition. A similar general variation of driver visual perception appeared under the respective tunnel conditions, with the number of fixations gradually increasing and the maximum saccade amplitude gradually decreasing as the drivers approached the tunnel portal. However, the variation occurred approximately 60 m earlier under the short-tunnel condition than under the medium- and long-tunnel conditions. Interactive correlations between driving behavior and visual perception under the three conditions were established. The commencement of active deceleration was significantly associated (with correlation factors of 0.80, 0.77, and 0.79 under short-, medium-, and long-tunnel conditions, respectively) with the point at which the driver saccade amplitude fell below 10 degrees for more than 3 s. The results of this study add to the sum of knowledge of differential driver performance at the entrances of tunnels of different lengths.

Comparison of LED and HPS Luminaries in Terms of Energy Savings at Tunnel Illumination

Energy demand is increasing day by day be cause of the step up of population, rising living standards, rising energy prices, global warming and climate change, developments in industry and tech nology in developing countries. In order to meet this increasing energy demand, it is not possible to increase production only due to limited energy resources. Therefore existing energy sources need to be used in the most efficient way. One of the most important means of reaching this target is the effi cient use of energy and its saving. Tunnel illumina tion is one of the areas of efficient and saving use of energy. In this study, high pressure sodium (HPS) and light emitting diode (LED) luminaires usage are compared to Buzlup?nar tunnel, which is a short tunnel in Bitlis province. It has also been found that illumination with LED luminaires is more efficient and economical in tunnel illumination instead of HPS.

Towards Efficient Implementation of an Octree for a Large 3D Point Cloud

The present study introduces an efficient algorithm to construct a file-based octree for a large 3D point cloud. However, the algorithm was very slow compared with a memory-based approach, and got even worse when using a 3D point cloud scanned in longish objects like tunnels and corridors. The defects were addressed by implementing a semi-isometric octree group. The approach implements several semi-isometric octrees in a group, which tightly covers the 3D point cloud, though each octree along with its leaf node still maintains an isometric shape. The proposed approach was tested using three 3D point clouds captured in a long tunnel and a short tunnel by a terrestrial laser scanner, and in an urban area by an airborne laser scanner. The experimental results showed that the performance of the semi-isometric approach was not worse than a memory-based approach, and quite a lot better than a file-based one. Thus, it was proven that the proposed semi-isometric approach achieves a good balance between query performance and memory efficiency. In conclusion, if given enough main memory and using a moderately sized 3D point cloud, a memory-based approach is preferable. When the 3D point cloud is larger than the main memory, a file-based approach seems to be the inevitable choice, however, the semi-isometric approach is the better option.

Analysis of the aerodynamic pressure effect on the fatigue strength of the carbody of high-speed trains passing by each other in a tunnel

When two high-speed trains pass through a tunnel, the aerodynamic changes are more complex and drastic than in open air owing to the interference of the tunnel wall and the entry effect. The impact on the carbody fatigue strength is very significant in the fatigue reliability design of the carbody. In this paper, the sequential coupling method was used for the first time to study the effect of pressure waves on the fatigue strength in a large-scale and complex carbody structure. The computational fluid dynamics method was used to calculate and analyze the aerodynamic pressure wave of the intersection of the trains in a long and short tunnel. A full-scale finite element shell model of the carbody structure was established. Then, the time integration method was used to convert the transient pressure wave into the aerodynamic loads bearing by the side wall of the carbody. The inhomogeneous stress concentrations at the restraint points were eliminated by the inertial release method; moreover, a finite element analysis of the carbody was carried out under the combined aerodynamic and mechanical loads. The Goodman fatigue strength curve of the aluminum alloy carbody was drawn. The influence of the aerodynamic load on the fatigue strength of the vehicle body was analyzed and compared under the entry effect of the short tunnel. The results show that the aerodynamic load of the short tunnel has a significant impact on the fatigue strength of the carbody owing to the train's entry effect. The safety factor of the fatigue strength is 15% less than that of the long tunnel aerodynamic load. In this paper, computational fluid dynamics and finite element method were used to analyze and evaluate the impact of the pressure wave on the fatigue strength of the carbody, which is of great reference value in the structural design of the carbody subjected to complex aerodynamic loads.