Short Tunnel Research Articles

Microclimate of Brown Bear (Ursus arctos L.) Dens and Denning Area.

The aim of this study was to determine the microclimate of brown bear dens depending on their size, their status (active or inactive), and the location of the den. The study included five dens of different sizes and locations in the Velebit Mountains, in the Dinaric Alps. The measurements of air temperature (°C) and relative humidity (%) in dens and the forest stands were carried out over 182 days. The absolute minimum air temperature in inactive dens was between -2.88 °C and -0.38 °C and belonged to the dens with shorter tunnels and without chambers. The exception was inactive den 1, which was situated in a thermophilic forest. No negative absolute minimum air temperatures were recorded in active dens. The absolute minimum air temperatures in the forest stands were lower than in the dens. The relative humidity was significantly higher in all dens than in the forest stands. Dens with a large entrance opening and a short tunnel were strongly influenced by the local microclimate of the forest stand. The greatest temperature difference (den-forest) was between elongated dens with chambers and the associated forest stand, while the smallest temperature differences occurred in dens with a short tunnel, without a chamber, and at the northern exposure. The greatest differences in relative humidity (den-forest) were found in dens with chambers. The den temperatures correlated with the air temperatures in the forest stands.

Anatomical classification of patent foramen ovale before percutaneous closure

Abstract Introduction Anatomical characteristics of patent foramen ovale (PFO) vary a lot, potentially impacting the embolic risk, selection of the device and the final sealing results of the closure procedure. Objective To categorize the different PFO anatomies and evaluate the consequence on the type of device used and the incidence of residual shunt. Methods 624 consecutive patients who underwent PFO percutaneous closure with transoesophageal echocardiography (TEE) guidance were retrospectively reviewed. Four types of PFO were identified once a rigid wire was in place using per-procedural TEE. This new classification was based on the PFO sheathed tunnel’s length and width, presence of concomitant atrial septal aneurysm (ASA) or additional defect (ASD), width of the septum secundum (SS) and aortic enlargement (Figure 1). Type I, or "single PFO" was defined by the absence of ASA or ASD, a tunnel width ≤ 4mm, SS’s width ≤ 10mm and no aortic enlargement (i.e., aortic root diameter <21mm/m², distorted anatomy or scoliosis). Type II or "dominant septal aneurysm" was defined by the presence of an ASA, with a distinction between subtype IIa (long PFO tunnel with length ≥10mm) and subtype IIb (short PFO tunnel with length <10mm). Type III or "modified PFO" was defined by SS’s width > 10 mm, aortic enlargement, or severe scoliosis, and type IV or "multi perforated" was defined by the presence of a concomitant ASD or a multifenestrated septal wall. In case of concomitant criteria, the predominant order was IV, then IIb, then III. For each category, the presence of residual shunt was evaluated after Valsalva manoeuvres with contrast echocardiogram 6 months after the procedure. Results Our population had a median age of 51 [41-59] years and included 43.8% women. The type II PFO was the most frequently encountered, with 42% of the patients (Table 1). A total of 44 (7.1%) patients presented multiple types concomitantly (mostly type II and III). PFO occluders were the most implanted devices overall, particularly with type I and IIb, while ASD occluder were more frequently used with types IV and IIb. Cribriform/Uni™ devices were more frequently used with type IV. Large devices (i.e., left disc’s diameter >25 mm) were predominantly used with type III and IV, but scarcely employed with type I and II. Within type II anatomies, large devices were significantly more frequently used with type IIb. Fluoroscopy duration was significantly higher with type IV. At 6 months ultrasound evaluation, large right-to-left residual shunt was significantly more frequent with type IV anatomy and with patients presenting multiple types concomitantly (18/34 - 40.9%). No significant differences were observed regarding clinical outcomes during follow-up. Conclusion Based on specific anatomical characteristics, four types of PFO may be identified, presenting with increasing procedural complexity, and requesting specific closure devices.

Absence of Additional Stretching-Induced Electron Scattering in Highly Conductive Cross-linked Nanocomposites with Negligible Tunneling Barrier Height and Width.

The intrinsic resistance of stretchable materials is dependent on strain, following Ohm's law. Here the invariable resistance of highly conductive cross-linked nanocomposites over 53% strain is reported, where additional electron scattering is absent with stretching. The in situ generated uniformly dispersed small silver nanosatellite particles (diameter=3.6nm) realize a short tunneling barrier width of 4.1nm in cross-linked silicone rubber matrix. Furthermore, the barrier height can be precisely controlled by the gap state energy level modulation in silicone rubber using cross-linkers. The negligible barrier height (0.01eV) and short barrier width, achieved by the silver nanosatellite particles in cross-linked silicone rubber, dramatically increase the electrical conductivity (51710Scm-1) by more than 4 orders of magnitude. The high conductance is also maintained over 53% strain. The quantum tunneling behavior is observed when the barrier height is increased, following the Simmons approximation theory. The transport becomes diffusive, following Ohm's law, when the barrier width is increased beyond 10.3nm. This study provides a novel strain-invariant resistance mechanism in highly conductive cross-linked nanocomposites.

Safety and complications associated with tunneling and pseudotunneling techniques during PICC and Midline insertion.

Peripherally Inserted Central Catheters and Midline Catheters are particularly attractive because of their favorable risk/benefit ratio. If the ideal venipuncture site is in an area inappropriate for catheter emergence, a valid alternative is the tunneling technique, which allows the exit site to be moved to reach the optimal position. There are two main types of tunneling techniques: standard tunnel, using a tunneling device (metal tunneler or peel-away tunneler), and pseudo-tunnel. As much as both are recognized as appropriate and safe, there are still few literature data indicating the criteria for choosing and using the two techniques and the possible related complications. This retrospective observational investigation analyzed data regarding intra- and post-procedural complications of tunneled catheters inserted using two different techniques. The sample was stratified into three subgroups: (1) Standard Tunnel (patients with no PLT or INR disorders), (2) Pseudotunnel (patients with no PLT or INR disorders), and (3) Pseudotunnel (patients with any PLT or INR disorder). Data regarding the procedure, at 24 h and 7 days were collected and analyzed. A total of 143 patients who underwent tunneled catheter insertion were included in the study. Among these, 113 patients were divided into subgroups 1 and 2 and 30 were assigned to subgroup 3. No significant differences were found among the three subgroups regarding immediate, short, and medium-term tunnel complications. The findings of this study suggest that both standard and pseudo-tunnels provide comparable levels of safety and comfort for patients. It was noted that Pseudotunnel offers an equivalent level of safety for patients with coagulation disorders related to PLT and INR, rendering it comparable to a "minimally invasive procedure," which necessitates the same precautions as a non-tunneled PICC.

Catheter Exchange With Elongation of Tunnel (CEET) Procedure-A Novel Technique for Cuff Extrusion of Tunneled Dialysis Catheter: Surgical Experience and Early Outcomes.

Cuff extrusion of tunneled dialysis catheter (TDC) leads to catheter dysfunction, leading to loss of vascular access and the need for new catheter. Definitive management is to remove TDC and reinsert new catheter by new venous puncture and tunnel, which may not be possible in all cases. The study evaluated the surgical experience and early outcomes of a novel "Catheter Exchange with Elongation of Tunnel (CEET)" procedure for cuff extrusion. The retrospective study included all cases of hemodialysis with TDC with partial or complete cuff extrusion and excluded complete catheter dislodgement, tunnel infection, or any catheter related infection. All patients also underwent the CEET procedure under fluoroscopy guidance, and the clinical details and outcomes were analyzed. Eleven cases of TDC cuff extrusion underwent the CEET procedure of which three (27.2%) had previous and four (36.4%) had partial cuff extrusion, and seven cases (63.6%) had short tunnel length, which likely predisposed to cuff extrusion. CEET procedure was successful in 10 cases (success rate 90.1%) with desired position of catheter tip and good blood flow. Study population was divided into early and late cuff extrusion (≥1 month). Short tunnel length was associated with late extrusion (p = 0.05), whereas premature removal of TDC anchor sutures was associated with early cuff extrusion (p = 0.04). CEET procedure is a successful alternative technique for correction of cuff extrusion of TDC with good success rate. Premature removal of anchor sutures was associated with early cuff extrusion, whereas short tunnel length was associated with late cuff extrusion.

Use of double short tandem scleral tunnels for repairing eroded ahmed glaucoma valve tubes

PurposeTo evaluate the effectiveness and safety of a method for repairing an eroded Ahmed glaucoma valve (AGV) tube using two short scleral tunnels made in tandem with a 22G needle instead of covering the eroded tube with another scleral graft.MethodsFrom May 12, 2015, to July 27, 2019, we retrospectively reviewed eight patients at Ningbo Aier Eye Hospital who developed AGV tube erosion secondary to necrosis of their overlying conjunctiva and scleral grafts. This defect was repaired in all the patients using the double short tandem scleral tunnel technique, which involved the creation of double short tandem scleral tunnels made by a 22G needle. Two parallel-to-limbus scleral incisions were made 3 mm and 6 mm from the limbus first, then a curved 22G needle was inserted between the two scleral cuts to make one scleral tunnel, the other scleral tunnel was completed during the first surgery, inserted the tube into the two tunnels. The mean length of time between the AGV placement and the first erosion was 12.25 ± 6.36 months (3–24 months). The mean age of the patients was 65.50 ± 11.70 years (49–78 years).ResultsThe surgical outcome was assessed in terms of the tectonic integrity of the conjunctiva over the follow-up period (12 months). There was no AGV tube erosion, scleral thinning, or ocular infection after a mean of 41.25 ± 26.54 months of follow-up in all eight patients.ConclusionAGV tube erosion following shunt surgery can be successfully managed using the improved double short tandem scleral tunnel technique.

From nano to macro in graphene-polymer nanocomposites: A new methodology for conductivity prediction

A two-step approach is proposed to forecast the conductivity of graphene polymer composites using simple models reflecting the tunneling mechanism and interphase part. Firstly, graphene and the adjacent interphase are presumed as figurative particles, and their conductivity is estimated. In the second stage, the conductivity of the nanocomposite containing figurative particles is predicted, considering the tunneling size between adjacent particles. The advanced methodology is used to forecast the conductivity for real examples. Additionally, the implications of all terms on the nanocomposite conductivity are assessed and explained. The estimations of conductivity acceptably agree with the measured data, which justifies the predictability of the suggested methodology. Thick interphase and short tunnels produce desirable conductivity, because they positively influence the net dimensions and tunneling resistance. Among the studied parameters, the thicknesses of graphene nanosheets and interphase have the highest impacts on the nanocomposite conductivity. The highest conductivity of nanocomposite as 7 S/m is obtained by the thickest interphase (ti = 10 nm) and the thinnest nanosheets (t = 1 nm), while t > 2 nm or ti < 5.5 nm cannot improve the conductivity. Furthermore, graphene volume fraction of 0.03 with the graphene diameter of 4 μm maximizes the nanocomposite conductivity to 3 S/m, but less filler amount and shorter nanosheets weaken the conductivity of nanocomposites.

Impact of traffic signs on driving speed at mountain highway tunnel entrances − The role of low-volume intermittent information

Driver’s perception of speed is the basis of driving safety, and installing speed limit signs at tunnel entrances is an intuitive means of controlling a driver’s driving speed. Therefore, tunnel entrance signs should be set up effectively to ensure each signage can fulfil its intended effect. Quantifying the information volume conveyed by traffic signs, discovering the impact of different information volumes on driving speeds, and understanding the effects of typical signs are the prerequisites for the effective use of signage. This study collected the speed variations of 40 drivers driving at nine mountainous highway tunnels with different entrance traffic signs through a naturalistic driving real vehicle test. The effect of low-volume intermittent information at tunnel entrances is identified in terms of the black hole effect on drivers (BHD), white hole effect on drivers (WHD), velocity fluctuation trend (VFT), and effect of speed limit signs (ELS). The study’s results confirm that the effect of speed limit signage with traffic sign information volume (TSIV) in the range of 8.904 to 33.318 bit is significant. In comparison, the sign will lose its effectiveness in guiding drivers to control their speed when TSIV is greater than 58.641 bits. Using low-volume information speed limit signs or tunnel warning signs repeated twice before entering a tunnel can alert drivers and regulate their driving speeds. The speed limit sign (sign ①) for each type of vehicle is set individually, and the combined speed limit and no lane change sign (sign ②) used in two stacks have a strong speed control effect. Moreover, the sign ②, when used alone, has the best timeliness; the effective distance of speed control can reach 1522 m; using it before short tunnels or long tunnels less than 1500 m can achieve better effectiveness.

Femoral tunnel length does not impact outcomes following ACL reconstruction using a single-bundle quadriceps tendon autograft: A systematic review.

To determine whether femoral tunnel length (FTL) affects clinical or functional outcomes following primary Anterior cruciate ligament reconstruction (ACLR) with single-bundle quadriceps tendon autograft, both with and without a patellar bone block. An electronic search of MEDLINE, EMBASE, and Cochrane databases was carried out via OVID. Data pertaining to study characteristics, patient demographics, surgical techniques, femoral tunnel length, and subjective/objective clinical outcomes was abstracted. Studies were stratified into two groups based on FTL; a short femoral tunnel (S-FT) group of ≤25 mm, and a long femoral tunnel (L-FT) group of >25 mm. There was a high degree of heterogeneity between studies, prohibiting meta-analysis. Seven studies comprising 368 total patients with a mean age of 30.3 years (range: 23.4-34 years) were included for analysis. The S-FT group included 126 patients and the L-FT group 242 patients. Both groups demonstrated statistically significant postoperative improvements across both subjective and objective clinical and functional outcomes. Average complication rates were 11.9% (range: 0%-29%) in the S-FT group and 4.5% (range: 1%-14%) in the L-FT group. Ranges of re-rupture rates were 0%-2% and 0%-3% for the S-FT and L-FT groups, respectively (n.s.). Both S-FT and L-FT groups demonstrated comparable postoperative outcomes following primary ACLR with single bundle quadriceps tendon autograft. There were slightly superior, although non-significant, outcomes reported with short femoral tunnel length, however, this may have been confounded by the variation in surgical technique used. IV.

Driving Characteristics of Drivers Avoiding Lateral Obstacles in Mountain Highway Tunnels: A Dynamic Lateral Safety Distance Prediction Model

A natural driving real-vehicle test was conducted in nine tunnels in Chongqing, China. The driving trajectories and speeds of 40 drivers were recorded to better understand drivers’ driving characteristics under the mutual influence of various tunnel lengths and numerous lateral obstacles on mountainous highways. According to the driver’s need for lateral safety distance in different scenarios, the conditions and scope of the occurrence of the shy away effect are defined, and a dynamic avoidance prediction model is established in multiple scenarios. It was demonstrated that, when there were no lateral dynamic obstacles, drivers were influenced by the tunnel sidewalls to drift away from them. However, when lateral dynamic obstacles were present, drivers’ driving trajectories were corrected to be closer to the inside of the lane. The influence of vehicles of the same type resulted in the trajectory offset to the left by 0.2 m (extra-long tunnel), 0.7 m (long tunnel), 0.5 m (medium tunnel), and 0.7 m (short tunnel) compared with the driving trajectory without the influence of the obstacle. The influence of trucks causes the trajectory offset to the left compared with the driving trajectory without obstacles by 0.2 m (extra-long tunnel), 0.5 m (long tunnel), 1 m (medium tunnel), and 1.75 m (short tunnel). There is some variation in the degree of risk to the driver from different obstacles under different tunnels. The lateral distance between the driver and the dynamic obstacle is related to the nature of the available driving distance ahead. A sufficiently long driving maneuver distance enables the subject vehicle to gradually overtake the lateral dynamic obstacle in a more stable state. Dynamic avoidance models with fitting accuracies of 0.6–0.99 were implemented to predict vehicle trajectories in different tunnels and under the influence of various lateral dynamic obstacles. The study of the correlation of vehicle trajectories under the influence of various factors in tunnels is completed by the research findings, which can serve as a foundation for the design of driving behavior regulation, an improvement in traffic safety facilities, traffic management, and monitoring of lateral safety distances of intelligent vehicles in tunnels.

Why frequent traffic accidents at highway tunnel exit? – An experimental analysis of the slack effect

This study analyzes the causes of frequent traffic accidents at the exit areas of highway tunnels. Vehicle experiments were conducted to collect data on the light environment, vehicle speed, and driver eye movement. The distribution patterns of the illumination, vehicle speed, and gaze location occupancy were analyzed, and highway tunnels of different lengths were compared. The tunnel exit area is divided into the transition, exit, and departure zones. It was observed that there was an obvious white-hole effect at the exit zone, with drastic changes in the light environment. The presence of abnormal acceleration behavior in the transition zone and decreased attention in the departure zone demonstrate the existence of psychological and physiological slack in drivers. Additionally, the tunnel length positively correlates to the slack effect, which is stronger in extra-long tunnels than in the short and medium tunnels. Multiple control scenarios were established and driving simulation experiments were conducted to further analyze the impact of the slack effect on the traffic safety. The experimental results demonstrated that the slack effect of the extra-long tunnels exhibited an evident lag which was still present after leaving the tunnel exit. The average vehicle speed and trajectory offset were larger and more discrete in the post-tunnel zone than on an ordinary open road. The speed of the curve in the post-tunnel zone is 5.1 % higher than that of the curve in the ordinary road, and the maximum trajectory offset is 54.3 % higher. Thus, this study reveals the slack effect at tunnel exits and explains the abnormal phenomenon of relatively good traffic environments but high traffic accident rates in the transition and departure zones of tunnel exits. These results present considerable practical significance for the safe operation of highway tunnels, particularly extra-long tunnels.

Some Questions about the Safe Operation of Short Road Tunnels

Some Questions about the Safe Operation of Short Road Tunnels

The influence of reservoir water level on the hydraulic characteristics of spillway tunnel

Abstract The spillway tunnel for water discharging is very important in water conservancy and hydropower engineering. Spillway tunnel with inclined and elbow part near the outlet can be more easily adapted to the topographic and geological conditions than that near the inlet, and can limit the cavitation damage to the short tunnel near outlet. Therefore, it has been widely used in the case of discharging water with high head and large discharge. Cavitation induced by high speed flow may cause severe damage to the spillway tunnel surface. And aeration is a common measure for surface protection. Study on the hydraulic characteristics of water-air two-phase flow is of great significance for improving aeration effect. In this paper, the velocity, depth of water and Froude Number of spillway tunnel under different reservoir water levels are studied by using VOF method. The results show that the Froude Number decreases at first and then increases as reservoir water level becomes lower.

Experimental study on the effect of flexible joints of a deep-buried tunnel across an active fault under high in-situ stress conditions

During dislocation, a tunnel crossing the active fault will be damaged to varying degrees due to its permanent stratum displacement. Most previous studies did not consider the influence of the tunnel’s deep burial and the high in-situ stress, so the results were not entirely practical. In this paper, the necessity of solving the anti-dislocation problem of deep-buried tunnels is systemically discussed. Through the model test of tunnels across active faults, the differences in failures between deep-buried tunnels and shallow-buried tunnels were compared, and the dislocation test of deep-buried segmental tunnels was carried out to analyze the external stress change, lining strain, and failure mode of tunnels. The results are as follows: (1) The overall deformation of deep-buried and shallow-buried tunnels is both S-shaped. The failure mode of deep-buried tunnels is primarily characterized by shear and tensile failure, resulting in significant compressive deformation and a larger damaged area. In contrast, shallow-buried tunnels mainly experience shear failure, with the tunnel being sheared apart at the fault crossing, leading to more severe damage. (2) After the segmental structure design of the deep-buried tunnel, the “S” deformation pattern is transformed into a “ladder” pattern, and the strain of the tunnel and the peak stress of the external rock mass are reduced; therefore, damages are significantly mitigated. (3) Through the analysis of the distribution of cracks in the tunnel lining, it is found that the tunnel without a segmental structure design has suffered from penetrating failure and that cracks affect the entire lining. The cracks in a flexible segmental tunnel affect about 66.6% of the entire length of the tunnel, and cracks in a tunnel with a short segmental tunnel only affect about 33.3% of the entire length of the tunnel. Therefore, a deep-buried tunnel with a short segmental tunnel can yield a better anti-dislocation effect. (4) By comparing the shallow-buried segmental tunnel in previous studies, it is concluded that the shallow-buried segmental tunnel will also suffer from deformation outside the fault zone, while the damages to the deep-buried segmental tunnel are concentrated in the fault zone, so the anti-dislocation protection measures of the deep-buried tunnel shall be provided mainly in the fault zone. The results of the above study can provide theoretical reference and technical support for the design and reinforcement measures of the tunnel crossing active fault under high in-situ stress conditions.

Optimization of Blasting Parameters Considering Both Vibration Reduction and Profile Control: A Case Study in a Mountain Hard Rock Tunnel

The number of excavated tunnels is increasing day by day, and the corresponding engineering scale is also getting increasing. Safe, efficient, and economically beneficial tunnel construction methods are indispensable in the process of crossing mountains and steep ridges in the southwest region. However, behind the improvement of transportation infrastructure in Southwest China is the support provided by the rapid development of blasting industry engineering technology in China. In the process of tunnel construction using the drilling and blasting method, in addition to blasting vibration disasters the phenomenon of overbreak and underbreak caused by blasting construction is a prominent problem. This phenomenon not only affects the safety and stability of the tunnel excavation but also seriously increases the construction cost. Based on a short mountain hard rock tunnel project in southwest China, this paper studies the effect of blasting construction on the blasting vibration of adjacent structures and the influence of tunnel contour forming quality. Through the monitoring and analysis of in situ blasting vibration, the Sadowski formula is used to study the attenuation law of blasting vibration velocity in different tunnel sites, which provides a theoretical basis for tunnel blasting vibration control. This article compares the use of overbreak and underbreak value with the traditional method to determine the degree of overbreak and underbreak. It introduces the analysis of contour section fractal dimension value and uses fractal theory in the Python image processing module to accurately and quantitatively describe the problems of tunnel overbreak and underbreak. The feasibility and accuracy of this method have been verified, by combining the total station and 3D laser scanner results of overbreak and underbreak measurements of the Brenner Base Tunnel and a short hard rock tunnel in a mountainous area of southwestern China. The blasting scheme was optimized from the aspects of cut hole form, detonator interval time, and peripheral hole charge structure, and the rationality of the optimized scheme was verified according to the on-site blasting experiments. It has a profound influence on strengthening the protection of adjacent tunnel structures and improving the economic benefit of mountain highway projects.

Roof stability analysis of cylindrical tunnels in hard soil/soft rock with reduced tension strength

Three-dimensional roof stability analyses of cylindrical tunnel segments limited along the tunnel direction were performed based on the modified Mohr–Coulomb failure criterion with reduced tensile strength. A wedge-shaped region of the classical Mohr–Coulomb envelope, where unrealistic tensile and shear strengths are predicted, is truncated by a Mohr circle associated with the true tensile strength. This revised failure criterion with partial nonlinearity allows geomaterials deep into the roof to deform with large velocity gradients under the normality plastic flow rule, observed in field investigations. Using the kinematic approach of limit analysis, rigorous bounds for three quantitative stability measures–stability number, factor of safety, and supporting pressure–were calculated. The roof failure mechanism adopted is relatively elaborate, involving three-dimensional geometry intersecting with a cylindrical tunnel segment; thus, an efficient approach was presented for tunnels with long length constraints. With respect to extremely short tunnel lengths, a modified roof failure mechanism with distinct ridges was proposed. The factor of safety with accommodation of the nonlinear pressure dependency was estimated by a consistent procedure associated with a reduced elliptic failure criterion. The results show that roof stability distinctly depends on the magnitude of the true tensile strength, internal friction angle, and length constraint.

Modelling reservoir sediment flushing through a bottom tunnel with an initially covered intake

Sediment flushing through a bottom tunnel is one of the most effective methods to alleviate reservoir sedimentation. However, the multi-physical hydro-sediment-morphological processes of reservoir sediment flushing through an initially covered bottom tunnel intake have remained poorly understood, and a physically enhanced and practically viable mathematical model is required. The present study uses an integrated model to resolve sediment flushing through an initially covered bottom tunnel intake. The proposed model couples a two-dimensional double layer-averaged model for the reservoir with a one-dimensional model for the bottom tunnel by means of numerical fluxes calculations at the inner boundary. The governing equations are solved synchronously using a well-balanced finite volume method. Several parameters related to boundary resistances and sediment exchange flux need to be determined for model closure. The model is tested against data from a series of physical experiments on reservoir sediment flushing, with sound agreement achieved between computed and measured scour hole geometries. Moreover, the present model successfully predicts the occurrence of tunnel blockage. The results prove that reservoir sediment flushing is best accomplished for high reservoir water level, small cover layer thickness, short tunnel length and steep tunnel slope. The present model facilitates reservoir design and operation to help preserve reservoir capacity.

Cavity and entrance pore development in ant plant hypocotyls.

Some genera of Rubiaceae in South-eastern Asia are known as typical ant plants. They have large domatia, which form in well-developed hypocotyls in which ants nest. Previously, cavity formation processes were described; however, these reports were dependent on tissue sections of different individuals of different ages. No continuous time-course analyses were done because cavity formation occurs inside the thick tissues of highly swollen domatia. Here we observed cavity formation processes in ant plants by using X-ray computed tomography (CT) imaging and revealed previously overlooked features of cavity formation. Firstly, the cavity pore occurs at the hypocotyl base in not only gravity-dependent but also basal position-dependent manner. Secondly, the cavity forms prior to the start of short tunnel formation between the cavity and the pore. The cavity axis is parallel to the longitudinal axis of the hypocotyl; however, the short tunnel axis between the pore and cavity depends on gravity. Non-invasive CT scanning is a very powerful method to analyze deeply hidden morphogenic processes in organs.

Behavioral Evaluation of Laboratory-housed Ferrets (Mustela Putorius Furo) in Different Enclosure Sizes.

The domestic ferret (Mustela putorius furo) is a common research model for infectious disease and behavioral studies. Ferrets are social animals that are commonly pair-housed. The United States has no species-specific regulatory standards for housing ferrets. Optimal enclosure dimensions have also not been investigated in this species, and cage sizes reported in the literature vary. Adequate space is an important animal welfare consideration, as smaller cages have been linked to increased incidence of stress- or boredom-related behaviors in some species. Here, we evaluated activity budget and space utilization in 2 different enclosure sizes for pair-housed female ferrets (n = 12). Single cages measured 78.7×78.7×45.7cm; double cages were comprised of 2 single cages connected by a short tunnel measuring 17.8 cm. Three pairs of ferrets were housed in each cage size and continuous video recordings were captured for 2 wk prior to crossover to the other cage size. The overall activity budget was similar between groups, with the predominant behavior being inactivity (89%). Stereotypic behaviors, such as cage biting or escape attempts, were infrequent (<0.1%) in both groups. Ferrets in double cages remained in the same cage as their partner 96% of the time, suggesting that social support is very valuable. Our results suggest that ferrets in both cage sizes experienced satisfactory welfare conditions. Our findings also suggest that while cage size is not the only determinant of conspecific aggression, larger cages may be an effective intervention to ameliorate aggression in certain ferrets based on signalment or behavioral history, with particular utility as a potential alternative to re-pairing or single-housing. This study provides valuable information to guide animal care and use programs regarding appropriate ferret housing.

Influence of knee flexion angle on graft bending angle during anterior cruciate ligament reconstruction using the transportal technique

This study aimed to examine change in the graft bending angle (GBA) according to various knee flexion angles in creating femoral tunnel by the transportal technique in ACL reconstruction, and to reveal knee flexion angle minimizing GBA while maintaining stable femoral tunnel characteristics. Patients who underwent ACL reconstruction using the transportal technique between January 2017 and December 2018 were retrospectively reviewed. Patients were classified into three groups according to knee flexion angle when creating femoral tunnel (group 1: < 120° (n = 19); group 2: 120–129° (n = 32); group 3: ≥ 130° (n = 33). GBA was measured on three-dimensional knee model reconstructed from postoperative computed tomography images. The length of the femoral tunnel and posterior wall blow-out were also checked. There was significant difference of GBA between the groups (group 1 = 112.1°; group 2 = 106.4°; group 3 = 101.4°, p < 0.001). The knee flexion angle in creating femoral tunnel was negatively correlated with GBA (r = − 0.733, p < 0.001). Five patients in group 1 had short femoral tunnel. GBA was influenced by knee flexion angle in creating femoral tunnel and got more acute as the knee flexion angle increased. Considering length and risk of wall blow-out in femoral tunnel, and GBA, knee flexion angle between 120 and 130° could be recommended as appropriate angle to create optimal femoral tunnel in ACL reconstruction using the transportal technique.