Approach Angle Research Articles

Variation in flight characteristics associated with entry by eagles into rotor‐swept zones of wind turbines

Automated curtailment of wind turbines can reduce fatality rates of wildlife but the resulting increased number of curtailments can reduce power generation. Tailoring curtailment criteria for each individual turbine could reduce unnecessary curtailment, yet it is unknown whether the risk to wildlife varies among turbines. We demonstrate turbine‐specific variation in the speed, altitude, approach angle and distance metrics associated with entry by eagles into rotor‐swept zones. Our results thus illustrate the potential value of turbine‐specific curtailment criteria to reduce fatality rates of wildlife at wind energy facilities.

An Encodable Scaffold for Sequence-Specific Recognition of Duplex RNA.

RNA, unlike DNA, folds into a multitude of secondary and tertiary structures. This structural diversity has impeded the development of ligands that can sequence-specifically target this biomolecule. We sought to develop ligands for double-stranded RNA (dsRNA) segments, which are ubiquitous in RNA tertiary structure. The major groove of double-stranded DNA is sequence-specifically recognized by a range of dimeric helical transcription factors, including the basic leucine zippers (bZIP) and basic helix-loop-helix (bHLH) proteins; however, such simple structural motifs are not prevalent in RNA-binding proteins. We interrogated the high-resolution structures of DNA and RNA to identify requirements for a helix fork motif to occupy dsRNA major grooves akin to dsDNA. Our analysis suggested that the rigidity and angle of approach of dimeric helices in bZIP/bHLH motifs are not ideal for the binding of dsRNA major grooves. This investigation revealed that the replacement of the leucine zipper motifs in bHLH proteins with synthetic crosslinkers would allow recognition of dsRNA. We show that a model bHLH DNA-binding motif does not bind dsRNA but can be reengineered as an RNA ligand. Based on this hypothesis, we rationally designed a miniature synthetic crosslinked helix fork (CHF) as a generalizable proteomimetic scaffold for targeting dsRNA. We evaluated several CHF constructs against a set of RNA and DNA hairpins to probe the specificity of the designed construct. Our studies reveal a new class of proteomimetics as an encodable platform for sequence-specific recognition of dsRNA.

An Encodable Scaffold for Sequence‐Specific Recognition of Duplex RNA

AbstractRNA, unlike DNA, folds into a multitude of secondary and tertiary structures. This structural diversity has impeded the development of ligands that can sequence‐specifically target this biomolecule. We sought to develop ligands for double‐stranded RNA (dsRNA) segments, which are ubiquitous in RNA tertiary structure. The major groove of double‐stranded DNA is sequence‐specifically recognized by a range of dimeric helical transcription factors, including the basic leucine zippers (bZIP) and basic helix‐loop‐helix (bHLH) proteins; however, such simple structural motifs are not prevalent in RNA‐binding proteins. We interrogated the high‐resolution structures of DNA and RNA to identify requirements for a helix fork motif to occupy dsRNA major grooves akin to dsDNA. Our analysis suggested that the rigidity and angle of approach of dimeric helices in bZIP/bHLH motifs are not ideal for the binding of dsRNA major grooves. This investigation revealed that the replacement of the leucine zipper motifs in bHLH proteins with synthetic crosslinkers would allow recognition of dsRNA. We show that a model bHLH DNA‐binding motif does not bind dsRNA but can be reengineered as an RNA ligand. Based on this hypothesis, we rationally designed a miniature synthetic crosslinked helix fork (CHF) as a generalizable proteomimetic scaffold for targeting dsRNA. We evaluated several CHF constructs against a set of RNA and DNA hairpins to probe the specificity of the designed construct. Our studies reveal a new class of proteomimetics as an encodable platform for sequence‐specific recognition of dsRNA.

Understanding the Effects of Wind Intensity, Forward Speed, and Wave on the Propagation of Hurricane Harvey Surges

Hurricane storm surges are influenced by wind intensity, forward speed, width and slope of the ocean bottom, central pressure, angle of approach, shape of coastal lines, local features, and storm size. A numerical experiment is conducted using the Advanced Circulation + Simulation and Simulating Waves Nearshore (ADCIRC + SWAN) coupled model for understanding the effects of wind intensity, forward speed, and wave on the storm surges caused by Hurricane Harvey. The ADCIRC + SWAN is used to simulate hurricane storm surges and waves. The wind fields of Hurricane Harvey were reconstructed from observed data, aided by a variety of methodologies and analyses conducted by Ocean Weather Inc (OWI) after the event. These reconstructed wind fields were used as the meteorological forcing in the base case in ADCIRC+SWAN to investigate the storm surges caused by the hurricane. Hurricane Harvey was the second most costly hurricane in the United States, causing severe urban flooding by dropping more than 60 inches of rainfall in Texas. The hurricane made three landfalls, with its first landfall as a Category 4 based on the Saffir–Simpson Hurricane Wind Scale (SSHWS), with wind intensities of 212.98 km/h (59 m/s). The storm surges caused by Hurricane Harvey were unique due to the slow speed, crooked tracks, triple landfalls in the USA, and excessive rain. The model’s storm surge and wave results were compared against observed data. High water marks at 21 locations and time series at 12 National Oceanic and Atmospheric Administration (NOAA) gauges were compared with the generated results. Several cases were investigated by increasing or decreasing the wind intensity or hurricane forward speed by 25% of the OWI wind and pressure data. The effects of the wave were analyzed by comparing the results obtained from ADCIRC + SWAN (with waves) and ADCIRC (without waves) models. The study found that the changes in wind intensity had the most significant effect on storm surges, followed by wave and forward speed changes. This study signifies the importance of considering these factors to enhance accuracy in predicting storm surges.

A Numerical Investigation of Rider Injury Risks During Falls Caused by E-Scooter-Stopper Impacts.

Within the past decade, injuries caused by electric scooter (e-scooter) crashes have significantly increased. A primary cause is front wheel collisions with a vertical surface such as a curb or object, generically referred to as a "stopper." In this study, various e-scooter-stopper crashes were simulated numerically across different impact speeds, approach angles, and stopper heights to characterize the influence of crash type on rider injury risk during falls. A finite element (FE) model of a standing Hybrid III anthropomorphic test device was used as the rider model after being calibrated against certification test data. Additionally, an FE model of an e-scooter was developed based on reconstructed scooter geometry. Forty-five FE simulations were run to investigate various e-scooter crash scenarios. Test parameters included impact speed (from 3.2 m/s to 11.16 m/s), approach angle (30 deg to 90 deg), and stopper height (52 mm, 101 mm, and 152 mm). Additionally, the perpendicular (90 deg) impact scenarios were run twice: once with Hybrid-III arm activation to mimic a rider attempting to break a fall with their hands and once without this condition. Overall, the risks of serious injury to the rider varied greatly; however, roughly half the impact scenarios indicated serious risk to the rider. This was expected, as the speeds tested were in the upper 25th percentile of reported scooter speeds. The angle of approach was found to have the greatest effect on injury risk to the rider, and was shown to be positively correlated with injury risk. Smaller approach angles were shown to cause the rider to land on their side, while larger approach angles caused the rider to land on their head and chest. Additionally, arm bracing was shown to reduce the risk of serious injury in two thirds of the impact scenarios.

Endoscope-Assisted Visualization of the Internal Auditory Canal Using the Middle Fossa Approach.

Angled endoscopes have been postulated to increase visualization of the internal auditory canal (IAC); however, few studies have quantified the extent of IAC visualization using endoscopes of varying angles. Preservation of the bony labyrinth in middle fossa (MF) vestibular schwannoma surgery may limit visualization of the lateral IAC. We sought to determine the extent to which IAC visualization is increased with endoscopes in these situations. Computed tomography (CT) scans were acquired before and after two cadaveric MF bony drill-outs. An atlas-based method was used to localize the IAC in the preprocedure CT and then registered with the postprocedure CT using standard image registration methods. Virtual microscope and endoscope positions and angles of approach were determined in a 3D rendering environment. Using ray casting techniques, the percentage of IAC surface area visible (unobscured by bony structures) with the microscope and 0°, 30°, and 45° endoscopes was calculated. For cadaver 1, the microscope led to visible IAC surface areas of 72%, whereas 0°, 30°, and 45° endoscopes visualized 58%, 79%, and 84%, respectively. For cadaver 2, the microscope led to visible surface areas of 67%, whereas the same endoscopes visualized 66%, 84%, and 84%, respectively. Using a microscope yields similar proportions of visible IAC surface area to a 0° endoscope in MF bony drill-outs. Increased visualization of the IAC is possible with more angled endoscopes. Using angled endoscopes may facilitate improved tumor dissection in the lateral IAC with neural and vascular preservation in vestibular schwannoma surgery aimed at hearing preservation.

Heat transfer and air flow friction in solar air heaters: A comprehensive computational and experimental investigation with wire-roughened absorber plate

This research focuses on the purpose and importance of studying the impact of physical factors on heat transfer and air flow patterns in a solar air heater (SAH) with wire-shaped roughness on the absorbers rectangle conduit. By understanding these factors, we can enhance the radiation absorption effectiveness of solar collectors. To investigate the effects of artificial roughness arrangement on SAH efficiency, we developed an experimental apparatus. The experiments involved determining the allowable ranges of dimensionless factors such as relative wire roughness height (h/D), relative roughness wire pitch (p/h), and the angle of approach of flow (α). Additionally, we considered the Reynolds number (Re) and the duct width to height ratio (W/H) during the development of computer program code for optimization. By comparing experimental findings with those obtained from a smooth duct under similar flow circumstances, we evaluated the improved heat transfer and friction factor. Notably, for specific parameters such as W/H = 5, h/D = 0.01, p/h = 40, and α = 50◦, the average Stanton number (Stav) was found to be 1.196 times higher than that of a smooth SAH duct. Similarly, the average friction factor (fav) was observed to be 1.044 times higher than that of a smooth SAH duct. At p/h = 40 and h/D = 0.01, the average air friction factor and average Stanton number are the lowest for Reynolds number 3000. These numbers have the best efficiency index, which is 1.148. The research findings have implications for optimizing solar air heaters by incorporating wire-shaped roughness on the absorbers conduit. This enhances heat transfer and overall performance, leading to more efficient solar collectors with positive environmental and economic impacts through increased energy efficiency and reduced reliance on non-renewable energy sources.

Optimization of Dry Turning of Inconel 601 Alloy Based on Surface Roughness, Tool Wear, and Material Removal Rate

In this work, the dry turning of Inconel 601 alloy in a dry environment with PVD-coated cutting inserts was studied. Turning was performed at various cutting speeds, feeds, insert shapes, corner radii, rake angles, and approach angles. After machining, arithmetic mean surface roughness (Ra) and flank wear (VB) were measured, and the material removal rate was also calculated (MRR). An analysis of variance (ANOVA) was performed to determine the effects of the turning input parameters. For the measured values, the turning process was modeled using an artificial neural network (ANN). Based on the obtained model, the process parameters were optimized using a genetic algorithm (GA). The objective function was to simultaneously minimize Ra and VB and maximize MRR. The accuracy of the model and the optimal values were further validated by confirmation experiments. The maximum percentage errors, which are less than 2%, indicate the possibility of practical implementation of the hybrid approach for modeling and optimization of dry turning of Inconel 601 alloy.

DeforMoBot: A Bio-Inspired Deformable Mobile Robot for Navigation Among Obstacles

Many animals can move in cluttered environments by conforming their body shape to geometric constraints in their surroundings such as narrow gaps. Most robots are rigid structures and do not possess these capabilities. Navigation around movable or compliant obstacles results in a loss of efficiency—and possible mission failure—compared to progression through them. In this letter, we propose the novel design of a deformable mobile robot; it can adopt a wider stance for greater stability (and possible higher payload capacity), or a narrower stance to become capable of fitting through small gaps and progressing through flexible obstacles. We use a whisker-based feedback control approach to match the amount of the robot's deformation with the compliance level of the obstacle. We present a real-time algorithm which uses whisker feedback and performs shape adjustment in uncalibrated environments. The developed robot was tested navigating among obstacles with varying physical properties from different approach angles. Our results highlight the importance of co-development of environment perception and physical reaction capabilities for improved performance of mobile robots in unstructured environments.

Analysis of the approach angle to medial orbitotomy that avoids accidental neurotrauma in the mesaticephalic dog skull utilizing 3D computer models and virtual surgical planning.

This study was conducted to determine an approach angle to medial orbitotomy that avoids accidental neurotrauma in mesaticephalic dogs. Medical records of dogs with mesaticephalic skulls that were presented to the veterinary medical teaching hospital for head computed tomography (CT) between September 2021 and February 2022 were reviewed. Descriptive data were queried, and CT findings were analyzed. Dogs greater than 20 kg and possessing a disease-free orbitozygomaticomaxillary complex (OZMC) on at least one side of the skull were included in this study. Digital imaging and communications in medicine (DICOM) files of head CT studies were imported into medical modeling software, and the safe approach angle for medial orbitotomy was determined using three-dimensional (3D) computer models and virtual surgical planning (VSP) principles. Angles were measured along the ventral orbital crest (VOC) from the rostral cranial fossa (RCF) to the rostral alar foramen (RAF). The safe approach angle at four points from rostral to caudal along the VOC was measured. The results at each location were reported as mean, median, 95% CI, interquartile ranges, and distribution. The results were statistically different at each location and generally increased from rostral to caudal. The variances between subjects and the differences between locations were large enough to suggest a standard safe approach angle in mesaticephalic dogs cannot be determined and should be measured for each patient. A standardized approach angle to medial orbitotomy is not possible in the mesaticephalic dog. Computer modeling and VSP principles should be implemented as part of the surgical planning process to accurately measure the safe approach angle along the VOC.

Combined finite-discrete element modelling of hydraulic fracturing in deep geologically complex reservoirs

Hydraulic fracturing is known to be one of the most effective stimulation techniques to enhance reservoir permeability. A hydraulic fracture (HF) fluid injection's efficiency largely depends on the pre-existing sources of heterogeneities. Amongst these features, conglomerate reservoirs containing blocks in a matrix and rock masses with filled joints are largely ignored despite their presence in deep rocks. This study focuses on the HF development in such reservoir conditions using the combined finite-discrete element method (FDEM). First, the capabilities of the FDEM are verified against available analytical solutions and experimental data. The influence of a single or multiple types of blocks is studied in the conglomerate models. Various controlling parameters including in-situ stresses, flow rate, fluid viscosity, directional HF (DHF), distance between the injection points, properties of the block and matrix interface are considered, and their effects on the hydraulic fracturing path are investigated. In the second scenario, the effect of the joints' filling material is studied, models containing randomly distributed filled joints are built and several controlling factors including different filling materials, angle of approach, in-situ stresses, flow rate and fluid viscosity are considered. The analysis results show a significant influence of both blocks in the matrix and filled joints on the HF pattern. The HF interaction with these features is shown to be complex, and six interaction types for the blocks and nine interaction types for the filled joints are identified based on the close examination of the results.

PO-02-024 ANCHOR BALLOON TECHNIQUE AS A RESCUE STRATEGY FOR CHALLENGING CORONARY SINUS CANNULATION: A CASE SERIES

Cardiovascular resynchronization therapy (CRT) improves outcomes in patients with chronic systolic heart failure and interventricular dyssynchrony. However difficult coronary sinus (CS) access due to tortuosity, stenosis or steep angulation can pose challenges to successful left ventricular (LV) lead implantation. Many such cases require surgical epicardial LV lead placement which is more invasive and associated with higher incidence of complications. Despite the use of interventional tools and techniques, such as use of delivery sheaths of varied sizes, Amplatz support wire, vein selectors and snaring, some cases require more advanced techniques such as anchor balloon as a rescue strategy to ensure successful LV lead placement. We describe a case series of 8 patients where anchor balloon technique was used to cannulate the CS due to inability to cannulate the CS despite using interventional techniques From 2017 to 2020, 8 patients were identified who required the anchor balloon technique for CS cannulation. Clinical information, imaging methods, LV lead implantation techniques, and complications were obtained by retrospective chart review. Stepwise description of using anchor balloon technique for CS cannulation is described in figure 1. The basic principle is to change the angle of approach and create a more supportive rail using compliant coronary balloons over which the sheath is advanced. Coronary balloons offer several advantages, they have a low profile, can track over wire, have a hydrophilic coating and can advance easily into CS. In our cohort of patients, anchor balloon technique was used to successfully cannulate the CS in all 8 patients where the other techniques had failed. In the group, 3 were denovo implants, 3 were upgrades to a prior implant and 2 were redo procedures where other operators had tried to implant the CS lead without success. 2 patients had prior history of open-heart surgery. The details of the patient population in each group are delineated in Table 1. Potential complications from using anchor balloons include vein rupture and laceration leading to pericardial effusion, but these were not seen in our study despite most patients with no prior history of open-heart surgery. Anchor balloon technique when added to the basic interventional CRT tools contributes to successful LV lead implantation in patients with challenging CS anatomy without any significant additional risk.Tabled 1Baseline CharacteristicsPatient IDAge (years)SexPrior open heart surgeryType of implant177MYesRedo271MYesUpgrade346FNoUpgrade471FNoDenovo561MNoDenovo653FNoDenovo757MNoUpgrade857FNoRedo Open table in a new tab

Transforaminal Endoscopic Approach to L5S1: Imaging Characterization of the Lower Lumbar Spine and Pelvis for Surgical Planning

To determine and compare pelvic and lumbosacral reference parameters with computed tomography in patients with low back pain (LBP) and a control group of asymptomatic patients to provide quantification data and morphological correlations for L5S1 transforaminal endoscopic approach (L5S1TEA). We prospectively evaluated 100 patients with LBP and a control group of 100 individuals, with spinopelvic computed tomography. We measured lumbopelvic and L5S1 transforaminal approach parameters: maximum approach angle (maxAA) and minimum approach angle (minAA) and skin incision (maxSI and minSI), iliac crest (IC) projection at intersection point (ICPi), distance between the projected intersection of maxAA with the ilium (ICi) and the posterior limit of the IC (ΔICi-ICpost), and distance between ICi and spinous process (ΔICi-SP). Females and ICPi were increased in the LBP group: maxAA: 48.38°±5.09°; minAA:32.5°±3.90°; maxSI: 11.39 ± 1.86cm; and minSI: 8.30 ± 1.48cm. Ilium intersection was increased in males; IC projection at the highest point (ICPh) was higher than ICPi; maxAA intersected the ilium in 28% and minAA in 1.5% of cases; ICi was positively correlated with facet angle, ICPh, and ICPi and negatively with ΔICi-SP. Our results set preliminary reference values for L5S1TEA surgical planning. Besides higher ICPi, there were no differences between groups in measured parameters. Traditional IC height (ICPh) does not correspond to the point of intersection of the approach and is significantly higher than ICPi. ICi correlated to higher facet angle values, ICPh and ICPi grades, and lower ΔICi-SP. Potential conflict with the ilium is increased in the male population. IC is not impeditive of L5S1TEA in most cases.

A Safety Distance Warning Method for Transmission Lines Based on the Relationship Between Approach Angle and Field Strength

To prevent construction machinery from intruding into the transmission corridor, a distance early warning method based on the relationship between the approach angle and the electric field strength is proposed. First, use the simulation analysis to determine the installation position of the electric field sensor. Then, the relationship between the approach angle and the electric field strength at the minimum safe distance outside the transmission line for different voltage levels, number of loops, and loop arrangement are analyzed, and the approach angle and electric field strength are used as comprehensive criteria. Finally, the relationship between the comprehensive criteria of various types of transmission lines is analyzed. Through the method proposed in this paper, an effective control method can be provided for maintaining the minimum safe distance when the construction machinery works near the transmission line.

Harrow with Turning Disc Section

Introduction. At present, there is widely used smooth plowing, which is moldboard plowing without back ridges and deep furrows. Aim of the Article. The article deals with developing a new design of working tools for smooth soil plowing that ensure the fulfillment of the required quality of soil cultivation. Materials and Methods. Based on the analysis of existing designs, the authors developed a harrow with a turning disc section, which is characterized by increased operational reliability by reducing energy costs for its adjustment. The range of change in the approach angle of the disk working bodies is 5–45°. Results. It was found that the speed of movement and the inclination angle disks have the greatest influence on the tillage quality. To optimize the motion parameters with a turning disk section for the best smooth plowing quality, a two-factor experiment was carried out. Discussion and Conclusion. As a result, it was found that at a speed of 9.113 km/h and approach angle of working disks of 32°, the quality of tillage is maximum and amounts to 86.1%.

Real-time tracking and dynamic berthing information extraction system with 2D LiDAR data

In smart ports, accurately perceiving the state of a berthing vessel relative to the berth is essential for ensuring the safety and efficiency of vessels and ports. This paper presents a real-time tracking and dynamic berthing information extraction system based on two-dimensional light detection and ranging (LiDAR). First, data preprocessing, fast segmentation, and filtering are performed in polar coordinates based on the continuous measurements and high angular resolution of the LiDAR. Moreover, the ship clusters are merged owing to “blind spot”. Then, simple online and real-time tracking with ship features is proposed by modifying the simple online and real-time tracking with a deep association metric framework to remove invalid frames and adapt to different berthing scenarios. Qualitative and quantitative analyses of the dynamic distance and approach angle berthing parameters relative to the dock are performed. The frequency of the calculation results can reach a rate of 20 Hz for LiDAR. On-site monitoring experiments were conducted on the training ship YuKun berthing/unberthing in the Dalian Port and a simulated berthing scenario was also established to verify the algorithm. The proposed method proved feasible and effective for dynamic ship target tracking and ensuring safe ship berthing.

Neuro-oncological augmented reality planning for intracranial tumor resection.

Before starting surgery for the resection of an intracranial tumor, its outlines are typically marked on the skin of the patient. This allows for the planning of the optimal skin incision, craniotomy, and angle of approach. Conventionally, the surgeon determines tumor borders using neuronavigation with a tracked pointer. However, interpretation errors can lead to important deviations, especially for deep-seated tumors, potentially resulting in a suboptimal approach with incomplete exposure. Augmented reality (AR) allows displaying of the tumor and critical structures directly on the patient, which can simplify and improve surgical preparation. We developed an AR-based workflow for intracranial tumor resection planning deployed on the Microsoft HoloLens II, which exploits the built-in infrared-camera for tracking the patient. We initially performed a phantom study to assess the accuracy of the registration and tracking. Following this, we evaluated the AR-based planning step in a prospective clinical study for patients undergoing resection of a brain tumor. This planning step was performed by 12 surgeons and trainees with varying degrees of experience. After patient registration, tumor outlines were marked on the patient's skin by different investigators, consecutively using a conventional neuronavigation system and an AR-based system. Their performance in both registration and delineation was measured in terms of accuracy and duration and compared. During phantom testing, registration errors remained below 2.0 mm and 2.0° for both AR-based navigation and conventional neuronavigation, with no significant difference between both systems. In the prospective clinical trial, 20 patients underwent tumor resection planning. Registration accuracy was independent of user experience for both AR-based navigation and the commercial neuronavigation system. AR-guided tumor delineation was deemed superior in 65% of cases, equally good in 30% of cases, and inferior in 5% of cases when compared to the conventional navigation system. The overall planning time (AR = 119 ± 44 s, conventional = 187 ± 56 s) was significantly reduced through the adoption of the AR workflow (p < 0.001), with an average time reduction of 39%. By providing a more intuitive visualization of relevant data to the surgeon, AR navigation provides an accurate method for tumor resection planning that is quicker and more intuitive than conventional neuronavigation. Further research should focus on intraoperative implementations.

In vitro efficacy of non‐surgical and surgical implant surface decontamination methods in three different defect configurations in the presence or absence of a suprastructure

Analysis of the in vitro efficacy of non-surgical and surgical dental implant surface decontamination with or without suprastructure. Three hundred and sixty implants were dipped in indelible red and distributed to 30°, 60°, or 90° angulated bone defect models. One hundred and twenty implants were used for each bone defect, 40 of which were assigned to a decontamination method (CUR: curette; SOSC: soundscaler; APA: air powder abrasion). Of these, 20 were subjected to a simulated non-surgical (NST) or surgical treatment (ST), with/without mucosa mask, of which 10 were carried out with (S+) or without (S-) suprastructure. Uncleaned implant surface was assessed by both-sided implant surface photography. Surface morphology changes were analyzed using scanning electron microscopy (SEM). Cleaning efficacy was significantly better within NST if the suprastructure was removed (p < 0.001). No significant difference was found within ST (p=0.304). Overall, cleaning efficacy in the order APA > SOSC>CUR decreased significantly (p < 0.0001) for both S+ and S- in NST as well as ST. Separated by NST/ST, S+/S-, defect angulation and decontamination method, only isolated significant differences in cleaning efficacy were present. Linear regression analysis revealed significant associations of remnants with the treatment approach, decontamination method, and defect angle (p < 0.0001). SEM micrographs showed serious surface damage after use of CUR and SOSC. Suprastructure removal is an additional option to improve cleaning efficacy of non-surgical implant surface decontamination in this in vitro model.

A Conversation with Marilyn Strathern

Professor Strathern recently delivered the 25th annual Westermarck Memorial Lecture in Helsinki: the lecture, titled ‘Comparing Concerns’, was published in issue 4/2009 of Suomen Antropologi. In the lecture Professor Strathern highlighted a number of unvoiced assumptions prevalent in the fields of organ, tissue and blood donations, through a comparison of contexts that are often considered incompatible. This is a perspective that has been dominant in much of her work: opening up new angles of approach through comparisons from a broad range of fields including personhood, gender, systems of kinship, law, intellectual and cultural property, and new reproductive technologies, to mention but some of her interests. In addition, she has been an active discussant onquestions of administrative reforms in academia, though she does not regard herself as political in the sense that many people who read her work actually do. These were the issues that were foremost in our minds as we sat down for a conversation with Professor Strathern. In between her Westermarck lecture, a seminar held in her honour, and the Finnish Anthropological Society Christmas party, time was a scarce resource; we therefore decided to waste no words on idle chit-chat and dove right in at the deep end.

Indocyanine Green–Assisted Retrograde Ureterolysis in Robotic Transvaginal NOTES for the Management of Stage IV Endometriosis with Obliterated Cul-de-sac

To explore the use of indocyanine green (ICG) in highlighting ureteral anatomical landmarks for the successful and safe execution of robotic-assisted transvaginal NOTES hysterectomy with resection of deeply infiltrated endometriosis. Stepwise demonstration with narrated video footage. An academic tertiary care hospital. Our patient is a 38-year-old G4P1031 with a symptomatic enlarged uterus secondary to adenomyosis and uterine myomas, dense adhesions between the posterior uterus, and left uterosacral ligament. Stage IV endometriosis with obliterated cul-de-sac is a challenging procedure in the surgical management of endometriosis. Ureterolysis is the key step to performing this surgery successfully and safely; however, the routine dissection of ureters from the sacral promontory level to the uterine artery is challenging in obliterated cul-de-sacs with pelvic side wall adhesions with the proximal ureter at greatest risk [1-4]. Using the ICG firefly technique allowed us to rapidly identify and safely dissect the ureter through robotic transabdominal endometriosis surgery [5,6]. The angle of approach in transvaginal NOTES surgery for hysterectomy with obliterated cul-de-sac endometriosis leads to far more difficulty in identifying the ureter at the beginning of surgery [3]. Therefore, an obliterated cul-de-sac was associated with a potentially increased risk of ureteral injury and bowel injury. We used ICG to help identify the ureter at the beginning of the case leading to reducing the risk of surgical complication, in which the concept of ureterolysis from the level of the uterine artery to the bifurcation of common iliac vessels in vNOTES surgery will be referred to as "vNOTES retrograde ureterolysis." With the cystoscope in place, a ureteral catheter was inserted into the right ureter and 5 cc of ICG was injected, and the same procedure was done on the left [1,5]. Bovie electrosurgical device was used to incise circumferentially around the cervix. The bladder was dissected off the pubovesical cervical fascia anteriorly and posteriorly with a combination of the Bovie as well as blunt and sharp dissection. Bilateral uterosacral and cardinal ligaments, as well as uterine arteries, were then clamped, transected with Mayo scissors, and secured. Entry into the anterior cul-de-sac was completed, and a stitch using 0 vicryl was used to tag the anterior peritoneum to the anterior vaginal cuff.Posterior entry was attempted unsuccessfully. The Gelpoint mini device was then placed, and the Da Vinci XI robot was docked. Bilateral ureters were identified and dissected out of bilateral pelvic sidewalls using the firefly mode at the level of the uterine artery. The ureters were easily dissected away from the uterus. The left broad ligament was then cauterized and transected using the vessel sealer. The plane between the uterus and the rectum was identified laterally, and the rectum was taken down from the uterus from the right to the left side.Bilateral broad ligaments were then cauterized and transected using the vessel sealer, followed by cauterization and transection of the round ligaments, utero-ovarian ligaments, and mesosalpinx bilaterally. The vaginal cuff angles were secured with a figure-of-eight stitch of 0 vicryl, and the vaginal cuff was then closed in a running fashion with 0 V-Loc.The patient was discharged in one day with reports of minimal pain (Videos 1-3). Robotic-assisted NOTES hysterectomy with deeply infiltrated endometriosis resection is feasible and safe with ICG-assisted ureteral labeling in a case of obliterated cul-de-sac. The unique green color labeling of ureters offers a prominent landmark in assisting the ureteral dissection while avoiding ureteral and bowel injury, resulting in the possibility of using vNOTES surgery in challenging cases.