Low Complexity Cases Research Articles

Learning curve in robotic liver surgery: easily achievable, evolving from laparoscopic background and team-based

PurposeLimited and heterogeneous literature data necessitate a focused examination of the learning curve in robotic liver resections. This study aims to assess the learning curve of two surgeons from the same team with differing laparoscopic backgrounds. MethodSince February 2021, San Raffaele Hospital in Milan has implemented a robotic liver surgery program, performing 250 resections by three trained console surgeons. Using cumulative sum (CUSUM) analysis, the learning curve was evaluated for a Pioneer Surgeon (PS) with around 1200 laparoscopic cases and a New Generation Surgeon (NGS) with approximately 100 laparoscopic cases. Cases were stratified by complexity (38 low, 74 intermediate, 85 high). ResultsBoth PS and NGS demonstrated a learning curve for operative time after 15 low-complexity and 10 intermediate-complexity cases, with high-complexity learning curves apparent after 10 cases for PS and 18 cases for NGS. Conversion rates remained unaffected, and neither surgeon experienced increased blood loss or postoperative complications. A “team learning curve” effect in terms of operative time emerged after 12 cases, suggesting the importance of a cohesive surgical team. DiscussionThe robotic platform facilitated a relatively brief learning curve for low and intermediate complexity cases, irrespective of laparoscopic background, underscoring the benefits of team collaboration.

WP5.3 - Rejuvenating the golden patient protocol in a tertiary centre general surgical emergency theatre

Abstract Aims Poor patient flow and complex sub-specialty decision making discussions lengthened time to operation of lower priority operations e.g. appendicectomy/abscesses. By prioritising start times and registrar patient selection for low complexity cases/day case discharge, we rejuvenated the golden patient protocol (GPP) and assessed the implementation and impact of a novel GPP in a tertiary centre emergency list on surgical wait times and overall theatre flow. Methods The GPP was agreed between surgical/anaesthetic night registrars and theatre staff which took into consideration the urgency of the surgery, fitness of patient and anaesthetic/technical difficulties. Eligible patients were identified prior to 08:00 and scheduled as the first case of the day to be huddled and sent for by 08:30. Two cycles were conducted, one month before and after GPP introduction, using the trust theatre management system (TMIS). Results Time series analysis was conducted for patient sent-for, anaesthetic room entry, and procedure start times during both cycles. Results indicated a median decrease of 11-minutes in patient sent-for time (Cycle 1: 08:56, Cycle 2: 08:45) and a 12-minute reduction in median procedure start time (Cycle 1: 09:42, Cycle 2: 09:30). The proportion of low complexity cases performed first-on-list also increased by 22.5% (Cycle 1: 35.5%, Cycle 2: 58.0%). Conclusions This analysis demonstrates a positive change by starting theatre faster with lower complexity cases, developing surgical registrar independence, improving time to treatment without complex discussions delaying first send.

SP1.6 - To facilitate the consent process efficiency for high volume low complexity cases as part of GIRFT

Abstract Background Our department completes a high volume of low complexity surgical cases (appendicectomies, cholecystectomies, inguinal hernia repairs and para-umbilical hernia repairs). Each case must have a completed consent form facilitating autonomous patient informed decision-making. The list of potential risks is key, currently handwritten and not standardised. Get It Right First Time (GIRFT) highlighted the importance of clear risks documentation. (1) The aim of this study is to analyse and evaluate the risks listed in consent forms for these surgeries and their adherence to GIRFT. Method First, thirty-three department members were surveyed for a complete list of risks for each surgery. After seven suggestions a consensus was reached. Second, we prospectively collected data from 05/07/2023 to 12/10/2023, identifying patients undergoing appendicectomies, cholecystectomies, inguinal hernia repairs, para-umbilical hernia repairs and collected risks listed in consent forms, comparing them to the agreed list. Result We identified 24 appendicectomies, 14 cholecystectomies, 14 inguinal hernia repairs, 9 para-umbilical hernia repairs. The mean completeness of the list of risks was: appendicectomies 42% (min: 16%, max: 56%); cholecystectomies 37% (min: 24%, max: 50%); inguinal hernia repairs 45% (min: 28%, max: 56%); para-umbilical hernia repairs 44% (min: 24%, max: 62%). Conclusion Completeness and standardisation of risks in consent forms is vital as highlighted by GIRFT. Current practices limit surgeons in achieving this.

Value for money of reusable versus disposable ophthalmic instruments for intravitreal injections

aim: The aim of this study was to follow the instruments’ pathways and cost each segment to calculate whether reusable or disposable ophthalmic instruments offer better value for money for intravitreal injections. methods: The cycles and costs of reusable and single-use disposable instruments used for intravitreal injections were mapped out, including purchase costs, transport to and from the place of use, opening and disposal, sterilisation, replacement, salary costs of staff involved, etc. results: The cost of using reusable instruments for intravitreal injections (NZ$29.00) was lower than the cost of using disposable instruments ($30.51) by $1.51 per patient. conclusions: Intravitreal injections performed with reusable instruments offer better value for money than when performed with disposable instruments. This equates to a beneficial financial saving just for this one low-complexity case. Such savings can multiply significantly when considering the instruments used in a wider variety of ophthalmic procedures. There are of course trade-offs between safety, quality, cost and sustainability.

The Benefits of Promoting Junior Trainees in Vascular Surgery.

Introduction United Kingdom surgical training consists of a two-year core surgical training (CST) followed by a six-year higher speciality training (ST). There is a significant step up in responsibility and operative skills when transitioning from core to higher training. One-way trainees can bridge this gap is to "act up" to registrar level "CST-R."The CST "steps up" to the role of ST typically in the latter part of their core trainingand gains exposure at being the "reg of the week," primary assistant in theatre, managing MDTs, and taking speciality referrals. This can be an excellent training opportunity. This study aims to demonstrate a quantitative improvement in trainee operation as a result of stepping up. Methods This study compares the operative experience of one vascular surgery-themed trainee during six months as a CST and six months acting up as a CST-R.The trainee's eLogbook was searched for all operations between August 3, 2022, and January 31, 2023, and between February 1, 2023, and August1, 2023. The number of cases performed and the role played in each were analyzed.The number of low complexity cases conducted in each block was used as a baseline to ensure the progression seen was because of increasingly complex ST operating rather than the increase in CST level operating expected throughout CST. An abscess incision and drainage were used as the reference low-complexity case. Results The number of cases the trainee performed independently increased from 13% to 25%, while the number where they were simply assisting decreased from 43% to 35%. The number of cases where the trainer remained scrubbed decreased nonsignificantly from 43% to 39%. The number of low-complexity cases performed remained unchanged for each six-month block. Conclusion As a CST-R, the trainee played a more prominent operative role in a greater number of cases. The CST-R does require a supportive department and consultant body. It also enables other STs to gain more surgical exposure because of their reduced frequency of being the "reg of the week." If a trainee can remain in a post for two six-month blocks, then there is much to be gained from a formalised acting-up program, and consideration should be given to formally incorporating this into core surgical programs.

Proper proximality in non-positive curvature

abstract: Proper proximality of a countable group is a notion that was introduced by Boutonnet, Ioana and Peterson as a tool to study rigidity properties of certain von Neumann algebras associated to groups or ergodic group actions. In the present paper, we establish the proper proximality of many groups acting on nonpositively curved spaces. First, these include many countable groups $G$ acting properly nonelementarily by isometries on a proper ${\rm CAT}(0)$ space $X$. More precisely, proper proximality holds in the presence of rank one isometries or when $X$ is a locally thick affine building with a minimal $G$-action. As a consequence of Rank Rigidity, we derive the proper proximality of all countable nonelementary ${\rm CAT}(0)$ cubical groups, and of all countable groups acting properly cocompactly nonelementarily by isometries on either a Hadamard manifold with no Euclidean factor, or on a $2$-dimensional piecewise Euclidean ${\rm CAT}(0)$ simplicial complex. Second, we establish the proper proximality of many hierarchically hyperbolic groups. These include the mapping class groups of connected orientable finite-type boundaryless surfaces (apart from a few low-complexity cases), thus answering a question raised by Boutonnet, Ioana, and Peterson. We also prove the proper proximality of all subgroups acting nonelementarily on the curve graph. In view of work of Boutonnet, Ioana and Peterson, our results have applications to structural and rigidity results for von Neumann algebras associated to all the above groups and their ergodic actions.

Abstract 4284: Enhancing subclonal reconstruction algorithm for resolving complex tumor phylogenies from multi-sample tumor DNA sequencing

Abstract Cancer is characterized by the ongoing accumulation of somatic mutations, providing selective advantages that may lead to dysregulated cellular proliferation. While the cancer genome at diagnosis has been extensively studied, many cancer types still lack strong prognostic biomarkers. The continuous acquisition and selection for driver mutations in a population of cancer cells acts as a Darwinian process, resulting in clonal expansions of progressively more aberrant and fit phenotypes. Reconstructing tumor evolution allows us to understand key events that drive cancer progression and patterns of mutation co-occurrence within clones. These evolutionary features guide our understanding of fundamental mechanisms that lead to disease lethality. Inferring tumor evolution from DNA sequencing data is becoming part of routine analysis in cancer research. As sequencing costs drop, sequencing multiple tumor samples from a patient becomes routine. These multiple samples can represent different spatial regions of a tumor, longitudinal samples from a single region or a combination of both. This provides an opportunity to study tumor evolution in much greater detail and accuracy than was previously feasible through single-sample datasets. The most widely used methods to reconstruct the subclonal evolution of a tumor utilize stochastic-search algorithms. These approaches iterate through a parameter space to select phylogenetic solutions that maximize the likelihood of observed sequencing data. They are optimized for low complexity cases, where the size and number or subclones are relatively limited. As tumor subclonal structure increases in complexity, the parameter space grows exponentially, and stochastic-search algorithms become computationally intractable. For instance, recent benchmarking studies have revealed that many methods fail to reconstruct clone trees for data with as few as ten subclones. To circumvent current computational limitations, we developed a deterministic algorithm for subclonal reconstruction that leverages fundamental principles of cancer biology to encode heuristics that reduce the solution space to biologically plausible phylogenies. When applied to samples (4-36 tumors; median 16) from 12 patients with metastatic breast cancer, our method reduced the average runtime ten-fold. We were able to delineate the evolutionary history of up to 57 distinct subclones per patient, which is infeasible with most current methods. Benchmarking using methods developed for the SMCHet DREAM challenge on real and simulated datasets further quantifies the accuracy, resolution, and scalability. We have thus presented a novel method for rapid and optimized reconstruction of tumor evolutionary histories. Citation Format: Helena Winata, Daniel Knight, Juber A. Patel, Nicholas K. Wang, Pier Selenica, Stefan E. Eng, Caroline Kostrzewa, Jaron Arbet, Yingjie Zhu, Ronglai Shen, Jorge Reis-Filho, Pedram Razafi, Paul C. Boutros. Enhancing subclonal reconstruction algorithm for resolving complex tumor phylogenies from multi-sample tumor DNA sequencing. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4284.

Women in Surgery Italia: what are the opportunities in the operatory room? Results from a nationwide interdisciplinary survey.

Many studies documented the "glass ceiling" effect for women in surgery: achievements in academic and leadership positions are not consistent with the percentage of female surgeons in practice. A solid surgical case volume and expertise in high-complexity cases are required to pursue leadership positions. The aim of the study was to determine whether part of the difficulties encountered by female surgeons may lie in reduced surgical opportunities. This is the first study to investigate this issue in Italy. An online survey, conceived and promoted by Women in Surgery Italia, was administered through the RedCap platform, between November and December 2020, and female surgeons actively working in Italian academic and non-academic hospitals were invited to answer anonymously. A multivariate analysis was performed to evaluate the role of different factors on two main variables: overall procedures done and a sub-analysis of complex cases performed as first surgeon. 1810 respondents were included; the women who responded participated in 3% fewer cases on average, when compared to the mean staff case volume, and were significantly more often listed as the assistant surgeon and as primary surgeons in low-complexity cases. 36.5% of the respondents declared that at least one female physician on staff had to abandon the operatory room (OR) and does not regularly perform any surgical procedure. 73% female surgeons would like to spend more hours in the OR. While acquiring skills and surgical autonomy, many obstacles still exist for female surgeons. A portion of women are relegated to non-surgical activities, irrespective of their specialty, and these results confirm the theory that gender-biased underemployment still exists in surgical fields.

What are we missing? The quality of intraoperative handover before and after introduction of a checklist.

Intraoperative handovers are common in anesthesia practice and are associated with increased patient morbidity and mortality. Checklists may improve transfer of information during handovers. This before-and-after study sought to examine the effect of a checklist on intraoperative handover. We hypothesized that introducing a handover checklist would improve our primary outcome of completeness of data transfer. From February to August 2016, anesthesia providers (residents, fellows, and consultants) at a single tertiary academic center participated in a handover study. Baseline handovers between anesthesia care providers were videotaped, analyzed, and compared with anesthetic records. An intraoperative handover checklist was then introduced, and handovers completed with it were videotaped. The completeness of handovers was compared between the baseline routine and checklist groups. The primary outcome was completeness of information transfer. Sixty-seven anesthesia providers participated in the study. Use of the intraoperative handover checklist improved completeness of handover by 6% (95% confidence interval [CI], 2 to 10; P < 0.01). There was no relationship observed between the provider (consultants/fellows vs resident) of the handovers and the degree of completeness (95% CI, 3 to 8; P = 0.33). Complexity had a significant impact on the handover completeness with low or high complexity cases more completely handed over than those of medium complexity both before and after the intervention-a 6% increase for low complexity (95% CI, 1 to 11; P = 0.02) and a 9% increase for high complexity (95% CI, 3 to 14; P < 0.01). Use of a checklist during intraoperative handovers improved completeness of data transfer. Handover checklists should be considered to improve handover completeness.

PD41-11 A DEEPER LOOK INTO SURGEON USE OF 3D VIRTUAL IMAGING PLATFORM (IRISTM): ANALYSIS OF GAZE PATTERNS AND PUPIL METRICS USING HEAD MOUNTED EYE TRACKERS (HMET)

You have accessJournal of UrologySurgical Technology & Simulation: Instrumentation & Technology II (PD41)1 Sep 2021PD41-11 A DEEPER LOOK INTO SURGEON USE OF 3D VIRTUAL IMAGING PLATFORM (IRISTM): ANALYSIS OF GAZE PATTERNS AND PUPIL METRICS USING HEAD MOUNTED EYE TRACKERS (HMET) Rachel Melnyk, Yuxin Chen, Tyler Holler, Nathan Schuler, Scott Quarrier, Jonathan Bloom, William Tabayoyong, Thomas Frye, Hani Rashid, Jean Joseph, and Ahmed Ghazi Rachel MelnykRachel Melnyk More articles by this author , Yuxin ChenYuxin Chen More articles by this author , Tyler HollerTyler Holler More articles by this author , Nathan SchulerNathan Schuler More articles by this author , Scott QuarrierScott Quarrier More articles by this author , Jonathan BloomJonathan Bloom More articles by this author , William TabayoyongWilliam Tabayoyong More articles by this author , Thomas FryeThomas Frye More articles by this author , Hani RashidHani Rashid More articles by this author , Jean JosephJean Joseph More articles by this author , and Ahmed GhaziAhmed Ghazi More articles by this author View All Author Informationhttps://doi.org/10.1097/JU.0000000000002051.11AboutPDF ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareFacebookLinked InTwitterEmail Abstract INTRODUCTION AND OBJECTIVE: Surgeons rely on 2D computed tomography (CT) scans for preoperative planning. IRIS is an interactive 3D virtual adjunct for surgical planning that includes features such as altering transparency, rotation, zooming, panning, and CT overlay. The objective of the study was to assess differences in patterns of use and eye tracking metrics during preoperative surgical planning of renal masses using IRIS and CT scans. METHODS: 7 surgeons wearing HMET (Tobii) reviewed 9 renal mass patient cases [5 high complexity (nephrectomy score ≥8), 4 low complexity (≤7)] using IRIS and CT images. Imaging modalities were randomly presented to avoid recall bias. Surgeons answered a series of questions regarding patient anatomy, perceived difficulty (/100), confidence (/100) and surgical plan. IRIS feature utilization frequencies were counted. Eye tracking metrics (mean pupil diameter (MPD), number of fixations, and gaze duration for each surface) were collected when the surgeon’s gaze focused on the survey or the imaging modality RESULTS: Surgeons spent significantly less time interpreting data from IRIS than CT scans (-70 s, p=0.001) and identified more accurate information, namely the number of branches of both arteries and veins (p≤0.001) and tumor location. Additional information caused an overall increase in perceived difficulty (80➝85) and changes in planned surgical approach in over a third of the cases (22), including 7 and 5 changes between partial/radical for high and low complexity cases, respectively. Confidence decreased for high complexity cases (49➝43) and increased for low complexity cases (38➝46). The most utilized IRIS feature was rotation, followed by panning, transparency, zooming, and CT overlay (8.2, 1.4, 1.4, 1.0, 0.5 times/case, respectively). Compared to viewing the CT scan, left and right MPD, fixations, and fixation duration were significantly lower when using IRIS (p<0.01, p<0.01, p=0.02, p<0.01, respectively) (Figure 1) indicating interpreting information from IRIS required less mental effort. CONCLUSIONS: Surgeons extrapolated more information in less time with less mental effort using IRIS than CT scans, despite underutilization of its manipulation features. Surgeon education may be required to optimize benefit from this technology. Source of Funding: None © 2021 by American Urological Association Education and Research, Inc.FiguresReferencesRelatedDetails Volume 206Issue Supplement 3September 2021Page: e685-e685 Advertisement Copyright & Permissions© 2021 by American Urological Association Education and Research, Inc.MetricsAuthor Information Rachel Melnyk More articles by this author Yuxin Chen More articles by this author Tyler Holler More articles by this author Nathan Schuler More articles by this author Scott Quarrier More articles by this author Jonathan Bloom More articles by this author William Tabayoyong More articles by this author Thomas Frye More articles by this author Hani Rashid More articles by this author Jean Joseph More articles by this author Ahmed Ghazi More articles by this author Expand All Advertisement Loading ...

Comparative efficacy and safety of the Captus device for inferior vena cava filter retrieval

PurposeRetrievable inferior vena cava filters (IVCF) have been increasingly used for mechanical pulmonary embolism prophylaxis since their development. The Captus Vascular Retrieval System (Avantec Vascular, Sunnyvale, California) is a new device developed for retrieval of IVCF. This study compared the safety and efficacy of the new Captus device against the existing EnSnare Endovascular Snare System (Merit Medical, South Jordan, Utah) for IVCF retrieval. MethodsPatients undergoing IVCF retrieval at a single institution between July 2015 and July 2020 were retrospectively identified. All adult patients (>18 years) undergoing filter retrieval with either Captus or Ensnare were included. Technical success and complications were compared by device. A complexity score was assigned to each case to adjust for selection bias. Logistic regression was used to model the association between device type and primary technical success. Results99 IVCF retrievals met inclusion criteria, 59 with Captus and 40 with Ensnare. The majority of the cohort consisted of low complexity cases (n = 51, 86% Captus versus n = 31, 78% Ensnare; p = 0.28). Technical success for low and medium complexity retrievals was 88% and 62% with Captus and 96% and 33% with Ensnare. There was no significant association between device type and technical success, adjusting for case complexity (Captus OR 0.55, 95% CI 0.08–2.72, p = 0.49). There were no device-related complications. ConclusionNo statistically significant difference in device technical success or complications between the Ensnare and Captus devices for uncomplicated IVCF retrieval. PrecisThe Captus Vascular Retrieval System is a new device for IVC filter retrieval which has similar technical success to the existing EnSnare.

Demand for Surgical Procedures Following COVID-19: The Need for Operational Strategies That Optimize Resource Utilization and Value.

Demand for Surgical Procedures Following COVID-19: The Need for Operational Strategies That Optimize Resource Utilization and Value.

The use of biological glue (Starsil® Hemostat) in robotic partial nephrectomy: a safety and efficacy study

Introduction: Robotic partial nephrectomy (RPN) is a relatively safe nephron sparing surgery (NSS) approach for the treatment of small renal masses (cT1). However, a major perioperative complication is extensive bleeding and blood loss necessitating blood transfusion. This complication is most challenging during the intraoperative setting and requires proper tumor bed closure. Recently several biological tissue adhesives have been tested to decrease intraoperative bleeding. A novel adhesive, Starsil® Hemostat is a plant-derived polysaccharide that can be applied directly to a bleeding wound to achieve hemostasis. The aim of our current study was to perform an evaluation of the safety and efficacy of this novel hemostat in patients undergoing RPN. Methods: This prospective single arm study included twenty patients with T1a-T1b renal masses who underwent RPN between the years 2017-2018. Renal masses were classified according to size, exophytic/endophytic properties and anatomic location into low, moderate and high complexity cases as described by the R.E.N.A.L nephrometry score. Starsil® Hemostat was applied by a feeding tube through a laparoscopic port after tumor excision. Perioperative data were collected, including blood loss during surgery, blood product transfusion rates, short and long-term adverse events and surgeon satisfaction using a visual analog scale (VAS 1-10). Results: Twenty RPN surgeries were completed using the Starsil® Hemostat. The average age was 61.8 ± 14.3. Average maximal tumor diameter was 3.8 cm (range 1.5-5.7). The calculated mean R.E.N.A.L nephrometry score was 8.4 (range 5-12). Mean blood loss during surgery was 346 mL (range 50-1400 mL). Mean surgeon satisfaction (VAS 1-10) with bleeding control was 8.3, when recorded 24 hours post operation. In 17/20 procedures (85%), bleeding control was good (VAS 9-10) and only 2 patients required blood transfusion. None of the patients developed an allergic reaction. No adverse events related to the adhesive product were noted in the post-surgical follow up period. Conclusion: Tumor bed closure during NSS with the adhesive STARSIL® Hemostat is safe, feasible and easy to use. It has the potential to reduce blood loss and transfusion rate in patients undergoing RPN.

Differential Diagnosis Assessment in Ambulatory Care With an Automated Medical History-Taking Device: Pilot Randomized Controlled Trial.

BackgroundAutomated medical history–taking devices (AMHTDs) are emerging tools with the potential to increase the quality of medical consultations by providing physicians with an exhaustive, high-quality, standardized anamnesis and differential diagnosis.ObjectiveThis study aimed to assess the effectiveness of an AMHTD to obtain an accurate differential diagnosis in an outpatient service.MethodsWe conducted a pilot randomized controlled trial involving 59 patients presenting to an emergency outpatient unit and suffering from various conditions affecting the limbs, the back, and the chest wall. Resident physicians were randomized into 2 groups, one assisted by the AMHTD and one without access to the device. For each patient, physicians were asked to establish an exhaustive differential diagnosis based on the anamnesis and clinical examination. In the intervention group, residents read the AMHTD report before performing the anamnesis. In both the groups, a senior physician had to establish a differential diagnosis, considered as the gold standard, independent of the resident’s opinion and AMHTD report.ResultsA total of 29 patients were included in the intervention group and 30 in the control group. Differential diagnosis accuracy was higher in the intervention group (mean 75%, SD 26%) than in the control group (mean 59%, SD 31%; P=.01). Subgroup analysis showed a between-group difference of 3% (83% [17/21]-80% [14/17]) for low complexity cases (1-2 differential diagnoses possible) in favor of the AMHTD (P=.76), 31% (87% [13/15]-56% [18/33]) for intermediate complexity (3 differential diagnoses; P=.02), and 24% (63% [34/54]-39% [14/35]) for high complexity (4-5 differential diagnoses; P=.08). Physicians in the intervention group (mean 4.3, SD 2) had more years of clinical practice compared with the control group (mean 5.5, SD 2; P=.03). Differential diagnosis accuracy was negatively correlated to case complexity (r=0.41; P=.001) and the residents’ years of practice (r=0.04; P=.72). The AMHTD was able to determine 73% (SD 30%) of correct differential diagnoses. Patient satisfaction was good (4.3/5), and 26 of 29 patients (90%) considered that they were able to accurately describe their symptomatology. In 8 of 29 cases (28%), residents considered that the AMHTD helped to establish the differential diagnosis.ConclusionsThe AMHTD allowed physicians to make more accurate differential diagnoses, particularly in complex cases. This could be explained not only by the ability of the AMHTD to make the right diagnoses, but also by the exhaustive anamnesis provided.

Multispectral Transforms Using Convolution Neural Networks for Remote Sensing Multispectral Image Compression

A multispectral image is a three-order tensor since it is a three-dimensional matrix, i.e., one spectral dimension and two spatial position dimensions. Multispectral image compression can be achieved by means of the advantages of tensor decomposition (TD), such as Nonnegative Tucker Decomposition (NTD). Unfortunately, the TD suffers from high calculation complexity and cannot be used in the on-board low-complexity case (e.g., multispectral cameras) that the hardware resources and power are limited. Here, we propose a low-complexity compression approach for multispectral images based on convolution neural networks (CNNs) with NTD. We construct a new spectral transform using CNNs, where the CNNs are able to transform the three-dimension spectral tensor from large-scale to a small-scale version. The NTD resources only allocate the small-scale three-dimension tensor to improve calculation efficiency. We obtain the optimized small-scale spectral tensor by the minimization of original and reconstructed three-dimension spectral tensor in self-learning CNNs. Then, the NTD is applied to the optimized three-dimension spectral tensor in the DCT domain to obtain the high compression performance. We experimentally confirmed the proposed method on multispectral images. Compared to the case that the new spectral tensor transform with CNNs is not applied to the original three-dimension spectral tensor at the same compression bit-rates, the reconstructed image quality could be improved. Compared with the full NTD-based method, the computation efficiency was obviously improved with only a small sacrifices of PSNR without affecting the quality of images.

Differences in early career operative experiences among pediatric urologists

Previous research suggests that pediatric urologists feel well trained by their fellowship for cases encountered early in their career. We questioned the complexity and diversity of cases new pediatric urologists were actually performing. The aim was to identify the frequency with which newly trained pediatric urologists are performing various procedures, investigate which factors are associated with case complexity and diversity, and evaluate for differences between male and female surgeons. Case logs of urologists from July 30, 2007, to June 30, 2013, initially applying for the certifying examination who self-identified as pediatric urologists were reviewed. Data points included cases/dates, and surgeon demographics. An in-depth analysis was performed on 51 index cases from the 71 included pediatric urologists, for which a level of complexity was assigned. Compared with the bottom volume quartile, surgeons in the top quartile performed more cases of minimal (115.9±8.7 vs. 51.7±8.7, p<0.001), moderate (31.1±2.7 vs. 10.1±1.0, p<0.001) and significant (10.8±1.9 vs. 2.0±0.4, p<0.001) complexity. More than 90% logged circumcisions, orchiopexies, and inguinal hernia repairs, while less than 1.5% logged open nephroureterectomies or complete male epispadias repair. Surgeons submitted at least one of 17.2±0.5 (range 5-28) unique codes. The figure presents the percentage of current procedural terminology (CPT) codes performed by each urologist. Surgeons with the least case diversity performed a higher percentage of low-complexity cases, and lower percentages of moderate and complex cases (p<0.001). Males, comprising 60.6% of urologists, performed more cases than females (342.9±30.9 vs. 229.1±18.1, p=0.007), averaging more cases of minimal (95.0±6.6 vs. 73.3±4.6, p=0.018) and significant (6.7±1.0 vs. 2.8±0.5, p=0.005) complexity. There was no difference in cases of moderate complexity (22.0±1.9 vs. 18.1±2.1, p=0.201). In general, pediatric urologists should expect to perform many minor cases when they enter practice. Women are entering urology in increasing numbers. In our study, female urologists performed fewer cases. This could have implications for the workforce, which in urology in general is expected to decrease. Case diversity and degree of complexity vary among newly trained pediatric urologists. The urologist with the greatest case diversity never performed 45% of the 51 analyzed CPT codes, while the one with the least case diversity never performed 90% of the codes. Male surgeons performed more operations, particularly those of minimal and significant complexity. The variability in operative experience reinforces the importance of continuing education and mentorship after completion of fellowship.

In patients undergoing hepatic resection, is the liver surgery complexity score a better predictor of case complexity and postoperative morbidity than the conventional major/minor classification?

Background: To validate the updated liver surgery complexity score (LSCS) (Strasberg, 2016) and compare it to the major/minor classification (MMC) in predicting major complications (Clavien-Dindo gradeִ ≥ 3) and case complexity (CC) Methods: Case complexity was assessed using estimated blood loss (EBL) and operative time (OT) as surrogates. Multivariate logistic regression models were developed for prediction of major morbidity and CC. EBL and OT were dichotomized using the medians of the variables (350 ml and 240 min respectively). The performance of MMC3 (≥3 vs. <3 segments), MMC4 (≥4 vs. <4 segments), LSCS (low, medium, and high complexity), and case specific-LSCS (using each specific hepatectomy listed by expert survey) in predicting CC and serious postoperative morbidity was compared using the Receiving Operator Characteristics curve analysis Results: Of 662 hepatic resections from 2005 to 2015, 485 were classified by LSCS and were included (single segment and multiple sub-segmental resections were excluded). Low (43%), medium (45%) and high (12%) complexity cases were associated with major morbidity of 16%, 32% and 57% respectively (p < 0.05). MMC4 (AUC = 0.813) and LSCS (AUC = 0.809) were comparable to MMC3 (AUC = 0.807) in predicting complications (p > 0.05). Case specific-LSCS (0.826) has better predictive ability than MMC3 (p < 0.05), but not MMC4 (p = 0.117). LSCS and case-specific LSCS were superior to MM3 and MM4 in predicting case complexity, as reflected in more accurate prediction of EBL and OT as separate outcome variables in multivariate logistic regression models (p < 0.05) Conclusion: The LSCS is significantly associated with case complexity and postoperative complications. In comparison to the conventional MMC, LSCS is a better predictor of CC; case specific-LSCS and MMC4 most accurately predict postoperative complications

Large-scale rigidity properties of the mapping class groups

We study the coarse geometry of the mapping class group of a compact orientable surface. We show that, apart from a few low-complexity cases, any quasi-isometric embedding of a mapping class group into itself agrees up to bounded distance with a left multiplication. In particular, such a map is a quasi-isometry. This is a strengthening of the result of Hamenst¨adt and of Behrstock, Kleiner, Minsky and Mosher that the mapping class groups are quasi-isometrically rigid. In the course of proving this, we also develop the general theory of coarse median spaces and median metric spaces with a view to applications to Teichm¨uller space, and related spaces.

Galois Conjugates of Pseudo-Anosov Stretch Factors are Dense in the Complex Plane

In this paper, we study the Galois conjugates of stretch factors of pseudo-Anosov elements of the mapping class group of a surface. We show that - except in low-complexity cases - these conjugates are dense in the complex plane. For this, we use Penner's construction of pseudo-Anosov mapping classes. As a consequence, we obtain that in a sense there is no restriction on the location of Galois conjugates of stretch factors arising from Penner's construction. This complements an earlier result of Shin and the author stating that Galois conjugates of stretch factors arising from Penner's construction may never lie on the unit circle.

The Genus of Curve, Pants and Flip Graphs

This article is about the graph genus of certain well studied graphs in surface theory: the curve, pants and flip graphs. We study both the genus of these graphs and the genus of their quotients by the mapping class group. The full graphs, except for in some low complexity cases, all have infinite genus. The curve graph once quotiented by the mapping class group has the genus of a complete graph so its genus is well known by a theorem of Ringel and Youngs. For the other two graphs we are able to identify the precise growth rate of the graph genus in terms of the genus of the underlying surface. The lower bounds are shown using probabilistic methods.