Single Tunnel Research Articles

Minimally Invasive Cochlear Implantation Assisted by Bi-planar Device

Background:A single drilled tunnel from the lateral mastoid cortex to the cochlea via the facial recess is essential for minimally invasive cochlear implant surgery. This study aimed to explore the safety profile of this kind of new image-guided and bi-planar device-assisted surgery procedure in vitro.Methods:Image-guided minimally invasive cochlear implantations were performed on eight cadaveric temporal bone specimens. The main procedures were: (1) temporal bone specimens were prepared for surgery and fiducial markers were registered. (2) computed tomography (CT) scans were performed for future reference. (3) CT scan images were processed and drill path was planned to minimize cochlear damage. (4) bi-planar device-assisted drilling was performed on the specimens using the registration. (5) surgical safety was evaluated by calculating the deviation between the drill and the planned paths, and by measuring the closest distance between the drilled path and critical anatomic structures.Results:Eight cases were operated successfully to the basal turn of the cochlear with intact facial nerves (FNs). The deviations from target points and entrance points were 0.86 mm (0.68–1.00 mm) and 0.44 mm (0.30–0.96 mm), respectively. The angular error between the planned and the drilled trajectory was 1.74° (1.26–2.41°). The mean distance from the edge of the drilled path to the FN and to the external canal was 0.60 mm (0.35–0.83 mm) and 1.60 mm (1.30–2.05 mm), respectively. In five specimens, the chorda tympani nerves were well preserved. In all cases, no injury happened to auditory ossicles.Conclusions:This exploratory study demonstrated the safety of the newly developed image-guided minimally invasive cochlear implantation assisted by the bi-planar device and established the operational procedures. Further, more in vitro experiments are needed to improve the system operation and its safety.

Universality of photoelectron circular dichroism in the photoionization of chiral molecules

Photoionization of chiral molecules by circularly polarized radiation gives rise to a strong forward/backward asymmetry in the photoelectron angular distribution, referred to as photoelectron circular dichroism (PECD). Here we show that PECD is a universal effect that reveals the inherent chirality of the target in all ionization regimes: single photon, multiphoton, above-threshold and tunnel ionization. These different regimes provide complementary spectroscopic information at electronic and vibrational levels. The universality of the PECD can be understood in terms of a classical picture of the ionizing process, in which electron scattering on the chiral potential under the influence of a circularly polarized electric field results in a strong forward/backward asymmetry.

Anatomic Double-Bundle Anterior Cruciate Ligament Reconstruction With a Free Quadriceps Tendon Autograft

Anatomic double-bundle anterior cruciate ligament (ACL) reconstruction aims to restore the 2 functional bundles of the ACL in an attempt to better reproduce the native biomechanics of the injured knee and promote long-term knee health. However, this concept is not fully accepted and is not performed on a standard basis. In addition, the superiority of this technique over the conventional single-bundle technique has been questioned, especially the long-term clinical results. One of the down sides of the double-bundle reconstruction is the complexity of the procedure, with increased risks, operative time, and costs compared with the single-bundle procedure. Also, the revision procedure, if necessary, is more challenging. We propose a technique that has some advantages over the traditional double-bundle procedure, using a single femoral tunnel, 2 tibial tunnels, and a free quadriceps tendon autograft.

Kinetic energy distribution of photoelectrons in the tunnel ionization process in the case of ultrashort laser pulses

In this paper, we use semiclassical model to discusse the kinetic electron energy distribution in the single tunnel ionization process of an atom with respect on the pulse duration and the spatial–temporal laser beam distribution. Our theoretical study show that the pulse duration is an important parameter in the ionization process, as well as beam shape.

The Early Results of the Reconstruction of Chronic Anterior Cruciate Ligament Deficiency with Single Tunnel-Dual-Bundle Technique and Quadruple Hamstring Autograft

Purpose: Our study retrospectively evaluates the early results of the reconstruction of anterior cruciate ligament (ACL) defficiency by single tunnel–Dual bundle technique and quadruple autogenous hamstring tendon graft. Methods: Fourteen female and 46 male patients whom with chronic instability due to ACL deficiency were included in this study. The injury mechanism was sports related injury in 45 patients and in 15 patients the injury were other causes. All of the patients were treated with Single tunnel–Dual band technique and quadruple autogenous hamstring semitendinosus (ST) and gracilis (G) tendon graft. The patients were clinically evaluated with Lachman test, pivot-shift test, anterior drawer test, Mc Murray test, Lysholm activity scale and International Knee Documentation Comittee (IKDC) Questionaire preoperatively and postoperatively and the data were recorded. Results: The average follow-up was 34.08 months (45–26 months). Both of the menisci were intact in 22 of the patients (36.6%) and meniscal lesion were present in 38 (63.3%) patients. Two of the patients with medial meniscal lesion were sutured with meniscal repair system. Also micro-fracture was performed in 4 patients with grade 3 chondral lesion in medial femoral condyle. The preoperative mean IKDC scores of 38.3 points (range 28.7–63.9) raised to 78.1 points (range 54-98.9) postoperatively and the difference was statystically significant. Conclusion: In light of the findings of our study and related literature we can comment that the mid-term results of the reconstruction of anterior cruciate ligament (ACL) defficiency by single tunnel–Dual band technique and quadruple autogeneus hamstring tendon graft with AperFix fixation system are stisfactory.

Dynamic interaction of twin vertically overlapping lined tunnels in an elastic half space subjected to incident plane waves

The scattering of plane harmonic P and SV waves by a pair of vertically overlapping lined tunnels buried in an elastic half space is solved using a semi-analytic indirect boundary integration equation method. Then the effect of the distance between the two tunnels, the stiffness and density of the lining material, and the incident frequency on the seismic response of the tunnels is investigated. Numerical results demonstrate that the dynamic interaction between the twin tunnels cannot be ignored and the lower tunnel has a significant shielding effect on the upper tunnel for high-frequency incident waves, resulting in great decrease of the dynamic hoop stress in the upper tunnel; for the low-frequency incident waves, in contrast, the lower tunnel can lead to amplification effect on the upper tunnel. It also reveals that the frequency-spectrum characteristics of dynamic stress of the lower tunnel are significantly different from those of the upper tunnel. In addition, for incident P waves in low-frequency region, the soft lining tunnels have significant amplification effect on the surface displacement amplitude, which is slightly larger than that of the corresponding single tunnel.

Centrifuge modelling of tunnelling with forepoling

Geotechnical centrifuge modelling provides a means by which geotechnical events and processes can be better understood. In particular, the technique has proved invaluable when investigating collapse mechanisms in small-scale models that can be related to full-scale events. A series of eight plane strain centrifuge model tests investigating the effect of inserting inclusions around the annulus of a single tunnel in overconsolidated clay have been conducted using the geotechnical centrifuge at City University London. The model used a compressed air-supported circular cavity to simulate the tunnel. Stiff resin inclusions embedded around its periphery were used to represent closely spaced forepoles forming grout umbrella arches. Image processing was used to obtain patterns of displacements at the subsurface and displacement transducers measured vertical settlement at the ground surface level. The investigation focused on how different arrangements of forepoling affected tunnel stability. The influence of forepoling on normally accepted plastic collapse mechanisms is discussed. An optimisation of the forepoling layout is suggested in accordance with the findings.

A novel sub 20 nm single gate tunnel field effect transistor with intrinsic channel for ultra low power applications

We propose a nanoscale single gate ultra thin body intrinsic channel tunnel field effect transistor using the charge plasma concept for ultra low power applications. The characteristics of TFETs (having low leakage) are improved by junctionless TFETs through blending advantages of Junctionless FETs (with high on current). We further improved the characteristics, simultaneously simplifying the structure at a very low power rating using an InAs channel. We found that the proposed device structure has reduced short channel effects and parasitics and provides high speed operation even at a very low supply voltage with low leakage. Simulations resulted in IOFF of ∼ 9 × 10−16 A/μm, ION of ∼20 μA/μm, ION/IOFF of ∼2 × 1010, threshold voltage of 0.057 V, subthreshold slope of 7 mV/dec and DIBL of 86 mV/V for PolyGate/HfO2/InAs TFET at a temperature of 300 K, gate length of 20 nm, oxide thickness of 2 nm, film thickness of 10 nm, low-k spacer thickness of 10 nm and VDD of 0.2 V.

Comparative Performance Analysis of Multi Gate Tunnel Field Effect Transistors

In this paper, analytical modelling and performance analysis of novel device structures such as single gate SOI Tunnel Field Effect transistor (SG SOI TFET), Dual-Material Gate TFET (DMG TFET) and Dual Material Double Gate TFET (DMDG TFET) are proposed. The performance of the three devices is studied and compared in terms of surface potential, electric field and drain current. The DMDG TFET shows better performance in suppressing leakage current and enhancing ION current than the SG SOI TFET and DMG TFET. The analytical models of the devices are found to be in good agreement with the results obtained using two-dimensional TCAD device simulator.

Air flow behavior and gas dispersion in the recirculation ventilation system of a twin-tunnel construction

Forced ventilation and recirculation systems are usually used in the construction of long twin tunnels as they offer large amounts of fresh air economically. However, because of the confluence near the cross-aisle, the fluid behavior and gas concentration are very different than in traditional forced ventilation for a single tunnel. A three-dimensional numerical model was built to study the air flow behavior and hazardous gas dispersion near the cross-aisle of a twin-tunnel construction. Field measurements were also carried out to validate the numerical model. The results show that there is a “dead zone” ahead of the cross-aisle which has a much lower air velocity than in other parts of the twin tunnels and where hazardous gases are more concentrated and uniformly distributed. In the cross-aisle and confluence zone of the air flow-out tunnel, methane tends to gather at the top and hydrogen sulfide tends to gather at the bottom. Increasing the recirculation velocity does not eliminate the “dead zone” near the cross-aisle although it consumes a huge amount of energy. Increasing the air velocity of the duct is an effective method to improve the air quality, but it is also expensive, especially when the air duct is long. When a jet fan was placed ahead of the cross-aisle in this study, the “dead zone” was eliminated completely. With respect to the recirculation ventilation system of twin tunnels, local jet fans offer an effective and economical way to eliminate the “dead zone”.

Investigation of ft and fmax in Si and Si1–xGex based single and dual material double-gate Tunnel FETs for RF applications

This study optimizes Si1−xGex based double gate tunnel field effect transistor (TFET) for their high ON current (Ion) and lesser sub-threshold swing and compares Si and Si1−xGex based single material double gate (SMDG) and dual material double gate (DMDG) TFETs. This study also measures the two RF performance metrics, unity gain cut-off frequency (ft) and maximum oscillation frequency (fmax) by varying the structural parameters, gate length, gate oxide thickness, channel thickness and underlap. Compared to single material gate devices, dual material gate devices give higher Ion without compromising the leakage current for both Si and Si1−xGex based TFETs. Si1−xGex based TFETs offers higher ft and fmax compared to that of Si TFETs for all the structural parameter variations considered in this study. DMDG TFETs exhibit higher ft with respect to SMDG TFETs. SMDG TFETs offers more fmax compared to DMDG TFETs due to the smaller values of output conductance.

Evolution of various quantum transport properties in a suspended disordered graphene device by the high bias voltage exposure

We investigated the evolution of the electronic transport properties of a suspended disordered graphene device by systematically controlling the bias voltage. Previously, the application of high bias voltage resulted in the sudden constriction of a graphene device. During the high bias voltage process, we utilized an electronic feedback loop to prevent the sudden change in resistance to ensure that the constriction proceeded sufficiently slowly. We performed a total of 137 sequential steps of a controlled high bias voltage exposure on the device in a cryostat. After each exposure, we measured the electronic transport properties and observed the transformation between various intriguing quantum transport phenomena. When the overall conductance was suppressed below approximately 10% of the single quantum conductance, superimposed Coulomb diamond patterns appeared at low temperatures, exhibiting parallel double quantum dot behaviors. We also found that the parallel double quantum dots were transformed into a single quantum dot and then into a single tunnel barrier as the high-voltage exposure was applied repeatedly. The transformation of the electronic transport properties along with the high bias voltage exposure processes can be attributed to the gradual reduction of the graphene width.

Combined reconstruction of the posterior cruciate ligament and medial collateral ligament using a single femoral tunnel.

Lesions of the medial collateral ligament (MCL) are the most common knee ligament injuries, and lesions associated with the anterior cruciate ligament or the posterior cruciate ligament (PCL) in knee dislocations should be reconstructed to prevent failure of the central pivot reconstruction. The purpose of this study was to evaluate the outcomes of combined PCL/MCL reconstruction using a single femoral tunnel with a minimum 2-year follow-up. A retrospective study of thirteen patients with combined PCL/MCL injuries was conducted. The patients underwent PCL and MCL reconstruction using an Achilles tendon allograft with a single tunnel in the medial femoral condyle, thereby avoiding tunnel conversion. All patients achieved a range of motion of at least 100°. The mean loss of extension and flexion values compared to the contralateral side was 1°±2° and 9°±10°, respectively. Our results included 26 reconstructions with three (11.5%) failures, two in the PCL (15.3%) and one in the MCL (7.6%), in three different patients. In the final evaluation, the mean IKDC subjective score was 71.63±16.23, the mean Lysholm score was 80.08±13.87, and the median Tegner score was 6 (range=2-7). The PCL/MCL reconstruction technique using a single femoral tunnel and an Achilles tendon allograft is safe, avoids the convergence of tunnels in the medial femoral condyle, has excellent results, and is reproducible. IV.

Perpendicular magnetic tunnel junctions with a synthetic storage or reference layer: A new route towards Pt- and Pd-free junctions.

We report here the development of Pt and Pd-free perpendicular magnetic tunnel junctions (p-MTJ) for STT-MRAM applications. We start by studying a p-MTJ consisting of a bottom synthetic Co/Pt reference layer and a synthetic FeCoB/Ru/FeCoB storage layer covered with an MgO layer. We first investigate the evolution of RKKY coupling with Ru spacer thickness in such a storage layer. The coupling becomes antiferromagnetic above 0.5 nm and its strength decreases monotonously with increasing Ru thickness. This contrasts with the behavior of Co-based systems for which a maximum in interlayer coupling is generally observed around 0.8 nm. A thin Ta insertion below the Ru spacer considerably decreases the coupling energy, without basically changing its variation with Ru thickness. After optimization of the non-magnetic and magnetic layer thicknesses, it appears that such a FeCoB/Ru/FeCoB synthetic storage layer sandwiched between MgO barriers can be made stable enough to actually be used as hard reference layer in single or double magnetic tunnel junctions, the storage layer being now a single soft FeCoB layer. Finally, we realize Pt- or Pd-free robust perpendicular magnetic tunnel junctions, still keeping the advantage of a synthetic reference layer in terms of reduction of stray fields at small pillar sizes.

Bending behaviors and fracture characteristics of laminatedductile-tough composites under different modes

The bending load-deflection curves and fracture characteristics of a range of laminated Ti(TiBw/Ti) composites were investigated under five modes. The results show ductile-brittle transition with decreasing Ti layer thicknesses and increasing volume fractions of TiBw, which is attributed to the constrained plastic deformation mechanism accompanying with high stress traixiality and tensile stress. The laminated composites with weak interfaces display superior fracture toughness under notched crack arrested orientation, which is related to the delamination cracks and multiple tunnel cracks. Moreover, single tunnel crack propagation and periodic multiple tunnel cracks were observed in the laminated composites under mode IV, which depend on the thickness and ultimate strength ratio of ductile Ti layer and tough TiBw/Ti composite layer. There are many interfacial delamination cracks and multiple tunneling cracks presented under mode V, playing an effective role in toughening the laminated composites. In addition, with decreasing the Ti layer thickness, laminated composites reveal obvious size effect characterized by more tunnel cracks.

Remnant-preserving, selective single-bundle augmentation of the anterior cruciate ligament using a bone–patellar tendon–bone autograft: A technical note

BackgroundTo the best of our knowledge, there has been no detailed study on bone–patellar tendon–bone (BTB) grafts for remnant-preserving, selective-bundle anterior cruciate ligament (ACL) augmentation. Therefore, we aimed to develop such a technique using a BTB graft. MethodA total of five patients underwent surgery using the presented procedure. These patients were young, male, and with high body mass index, and hence required very high durability of reconstructed ACL. A femoral bone tunnel was created using the inside-out technique via an accessory far-medial portal, protecting the remnant using a probe, regardless of the presence of an anteromedial (AM) or posterolateral (PL) tunnel. A single tibial tunnel was drilled at the center of the AM or PL attachment and two transverse skin incisions were made in the ipsilateral knee. The central third of the patellar tendon attached to a patellar and tibial bone plug autograft with a width of seven millimeters was harvested by subcutaneous tunneling. The femoral side was fixed using a cortical fixation device for BTB and the tibial bone plug was fixed using an interference screw with the knee at an angle of 20° of flexion by applying maximal manual traction. ResultsBone tunnel enlargement, which was measured by computed digital radiography, was not observed in all cases. A BTB autograft for remnant-preserving, selective-bundle ACL augmentation offers reduced risk of tunnel enlargement. ConclusionThe presented procedure might be considered one of the potentially available options for patients with ACL partial tear who require very high durability of reconstructed ACL. Level of evidence5

Concurrent Minimally Invasive Carpal Tunnel Release Techniques in Distal Radius Open Reduction Internal Fixation.

Carpal tunnel syndrome is a common complication associated with distal radius fractures. Open carpal tunnel release in the same setting as open reduction and internal fixation of distal radius fractures is widely accepted. In this paper, we describe the technical details of a minimally invasive carpal tunnel release in the same setting as the fixation of a distal radius fracture via the same incision. Two options of minimally invasive techniques are described: The Knifelight® (Stryker, Kalamazoo, Michigan, USA) instrument and the single portal carpal tunnel release system (Agee, 3M Healthcare, St Paul, Minnesota, USA). Being well known and accepted techniques of carpal tunnel release, we believe that the techniques described in this paper provide a viable alternative for carpal tunnel release in the setting of distal radius fracture fixation; with the added advantages of the original minimally invasive techniques.

VERIFICATION OF NUMERICAL MODEL OF FIRE AND SMOKE DEVELOPMENT IN RAILWAY TUNNEL

Simulation of fire spread and development of toxic gases during a fire accident in a railway tunnel allows prepare and validate models of safe evacuation of people. Highly complex problem of fire dynamics in a tunnel can be solved by the aid of numerical models based on CFD method. In order to check the quality of prediction models the procedure of verification is used. A relatively simple model of a single track railway tunnel is solved in two independent codes - FDS and Smart Fire. Accuracy of the model prediction is verified by the aid of gas temperature resolution along the tunnel length. To estimate an error based on different mesh resolutions of numerical model, calculation of the same model is carried out using different mesh density.

San Pasquale Station of Line 6 in Naples: Measurements and Numerical Analyses

The paper reports some geotechnical aspects of the design and construction of the San Pasquale Station, intermediate along Line 6 and located close to the sea and at the same time within one of the most fascinating district of the city known as Chiaia borough. The station required an excavation deeper than 25 m, almost entirely located in pyroclastic sand below the groundwater table. The main shaft is 85.5 m long and 24.1 m large, containing also the whole length of the pedestrian platform while a single large section tunnel, built before the excavation of the station shaft, accommodates the two operating rail tracks. In the paper monitoring data will be presented and discussed. Settlements and horizontal displacements represent certainly very significant outcomes among the observed data. Their variations along with time and main construction steps are first of all presented in the paper. The monitoring data have also been submitted to a process of careful interpretation based on the use of numerical analyses to better understand the interaction of deep excavation with urban area. The FEM code Plaxis has been adopted for such a purpose adopting advanced constitutive soil models which are available in the code library.

Hydraulic Experiment for Friction Loss Coefficient in Non-circular Pipe

Recently, global warming and climate change has been known as the main driving force of the extreme floods in urban area. Therefore, the flood and traffic problem should be solved simultaneously in the mega cities. The multi-functional tunnel with the road and stormwater bypass is suggested as one of the solutions. A single bored tunnel feasible by TBM machine has the double-deck road tunnel and stormwater bypass underneath. In the multi-functional tunnel, the shape of the stormwater bypass is usually not circular. Therefore, the friction loss in the non-circular pipe should be evaluated for the accurate design. In this study, hydraulic experiment was set and the friction loss coefficients were evaluated using 6 different Reynolds numbers. As the result, the difference between measured and computed friction loss coefficients become substantial when the Reynolds number is decreased less than 2,000 for the laminar flow. When the stormwater pipe using the non-circular shape is designed, the different friction loss coefficients should be applied for the accurate calculation.