bluuebunny/crossref_metadata_2025 huggingface dataset:
Optical Efficiency Analysis of Primary Mirror in LFR-CSP
Authors: Lv Hongwei , Chen Kang , Chen Pengfei , Wang Xiao , Wen Long
Published: April 2022

The linear Fresnel solar thermal power generation system is one of the most representative forms of solar thermal power generation system at present. The primary mirror, as the main mirror, plays a key role in the photothermic conversion process of the collector tube. In this paper, the solar position and the optical efficiency of the primary mirror in LFR-CSP are modeled and analyzed. The light reflection process of primary mirror by solar position through four dimensions of solar declination angle, solar time angle, altitude angle and azimuth angle is studied, and the distribution law of solar position parameters in different seasons and different times throughout the year is analyzed. It is found that the variation range of chord efficiency of a single mirror element in the whole day is 75 %-93 %. The position of a mirror element in winter solstice has the greatest impact on the end loss of more than 1 %, but the summer solstice has no effect.
Research on influence of the unilateral surge chamber about the main surge chamber
Authors: Chu Shanpeng , He Wei , Qu Xingquan
Published: April 2022

The hydropower station diversion tunnel is long. When the upstream water level is low, the minimum upsurge of the surge chamber is likely to be lower than its bottom, which may cause dangerous conditions such as liquid column separation. In order to solve the problem, an engineering measure that an unilateral surge chamber is set up near the main surge chamber was proposed in this paper. Its effect was analyzed. Based on establishment of mathematical model, the transition process of hydropower station water conveyance system was numerically simulated. The influence of different diameter, injection flow rate and position on minimum upsurge was researched. The results showed that increasing diameter and position of unilateral surge chamber has little effect on rising of minimum upsurge, but increasing injection flow rate of unilateral surge chamber has great effect on it. The study provides references for engineering design.
Fuzzy Proportional-Derivative Based Robot Arm Control for Object Transfer
Authors: Chen Shouyan , Yu Huaxin , Tan Zhifeng , Huang Junfeng , Zhou Danting , Li Haozhuo
Published: April 2022

With the development of robot technology, humanoid robot and human-robot interaction are gradually playing a more and more important role in our society. At present, the arm control of humanoid intelligent robot has become one of the hot research issues in the field of robot. This paper proposes a fuzzy based NAO robot hand control method to reduce the vibration and increase position accuracy during object transferring between NAO robot and human. The 5-DOF kinematics model of NAO robot right arm is first established. Motion path of the NAO robot arm during human-robot interaction is planned and conducted in Matlab and reality. The impact of control period, joint speed and trajectory error on vibration is observed and discussed. Based on the discussion, the fuzzy-PD control method is proposed. Experiments result indicates that the proposed Fuzzy-PD control method can reduce vibration and trajectory error, which can benefit the smooth motion control process of the NAO robot arm receiving objects in the process of human-robot interaction.
DC-link Voltage Equalization and Output Voltage Stabilization Control of the Medium Voltage High Power Cascaded Converter Source
Authors: Zhu Peng , Liu Baolong , Qiao Mingzhong , Wei Yongqing , Fe Yu
Published: April 2022

Nowadays, H-bridge cascaded converter is widely adopted in the field of ship’s shore power supply in ports and quays, new energy grid connection, et al. This paper focuses on the design and key technology of cascaded inverter. According to the design requirements of medium voltage shore power supply, the main circuit voltage, current and other parameters were calculated firstly, and overall design scheme of cascaded H-bridge type converter power supply is designed. And then the specific realization process of the carrier phase-shifted control of each H-bridge module in the cascaded connection converter was analyzed. To solve the problems of unequal capacitor voltages and unstable output voltages caused by power grid fluctuation and variable load, the DC-link voltages equalization and output voltages stabilization control method of the converter power supply without output voltage sensors was proposed. Furthermore, a sliding window iterative DFT algorithm was used to detect current feedback rapidly. Based on the design parameters, the system simulation was built, and the principle prototype was completed. Finally, the simulation and experimental results are compared to verify the design and control method. And the results indicate that the system design scheme proposed in this paper can basically meet the requirements of design indexes, and realize the control of DC-link voltage equalization and output voltage stabilization at the same time. All those certify the control method is correct and effective.
Readout electronics for the CMS Phase II Endcap Calorimeter: system overview and prototyping experience
Authors: Strobbe N.
Published: April 2022

The frontend readout system for the silicon section of the CMS Phase II Endcap Calorimeter faces unique challenges due to the high channel count and associated bandwidth, limited physical space, as well as radiation tolerance requirements. I will give an overview of the frontend electronics design and will discuss the recent experience obtained from the first test system that integrates the HGCROC2 readout ASIC, lpGBT, and VTRX+ in a realistic manner, linking together prototypes of the hexaboard, engine, and wagon boards.
Efficacy of the global protected area network is threatened by disappearing climates and potential transboundary range shifts
Authors: Parks Sean A , Holsinger Lisa M , Littlefield Caitlin E , Dobrowski Solomon Z , Zeller Katherine A , Abatzoglou John T , Besancon Charles , Nordgren Bryce L , Lawler Joshua J
Published: April 2022

Protected areas are essential to conserving biodiversity, yet changing climatic conditions challenge their efficacy. For example, novel and disappearing climates within the protected area network indicate that extant species may not have suitable climate in protected areas in the future. Further, potential transboundary range shifts, those that involve movement from one country to another, are also challenging because physical (e.g. fencing) and non-physical barriers (e.g. contrasting conservation policies) may impede climate-induced movements. Through the lens of climate analogs, we examined disappearing and novel climates within the global terrestrial protected area network and the potential for transboundary range shifts among protected areas under global warming 2 °C above preindustrial levels. We found that globally, climates in 24% of protected lands will no longer be protected within a 500 km radius of their focal location (indicating disappearing climates within the protected area network), while 36% of protected lands will gain climates not previously protected (indicating novel climates within the protected area network). Further, we found that potential transboundary range shifts are widespread but variable; for example, 23% of protected climates in Europe and >50% of protected climates in Africa under climate change are located in a different country than the focal protected areas. As the global conservation community actively deliberates conservation frameworks (e.g. 30% by 2030), our study offers insights to reduce the prevalence of novel and disappearing climates within the global protected area network via strategic conservation actions and underscores the importance of setting and accommodating targets and strategies that transcend national boundaries.
Increases of extreme heat-humidity days endanger future populations living in China
Authors: Chen Huopo , He Wenyue , Sun Jianqi , Chen Lefeng
Published: April 2022

Changes in heat stress due to climate change affect living and working conditions. A wet-bulb temperature (TW) of 35 °C is identified as the upper physiological limit for human survivability. On the basis of Coupled Model Intercomparison Project phase 6 model simulations, our evaluations show that the daily maximum TW is expected to significantly intensify throughout China and is likely to exceed this critical threshold in some regions by the end of this century, especially under the high emission scenario of the shared socioeconomic pathway (SSP)5-8.5. The most dangerous hazard from extreme heat-humidity events is concentrated around the most densely populated regions of eastern China as well as the Sichuan basin. Under SSP5-8.5, the significant increase of extreme heat-humidity days with a daily maximum TW exceeding 35 °C results in a large fractional population of approximately 81% being exposed to these extremes in China by the end of this century. This is true for different future warming scenarios, and a population fraction of up to 51% would also be exposed to such extremes even if early mitigation was conducted via SSP1-2.6. Our findings in this study thus have significant implications to ongoing considerations for climate-change policy in China.
Percolation on spatial anisotropic networks*
Authors: Gotesdyner Ouriel , Gross Bnaya , Vaknin Ben Porath Dana , Havlin Shlomo
Published: April 2022

Many realistic systems such as infrastructures are characterized by spatial structure and anisotropic alignment. Here we propose and study a model for dealing with such characteristics by introducing a parameter that controls the strength of the anisotropy in the spatial network. This parameter is added to an existing isotropic model used to describe networks under spatial constraints, thus generalizing the spatial model to take into account both spatial and anisotropic features. We study the resilience of such networks by using a percolation process and find that anisotropy has a negative impact on a network’s robustness. In addition, our results suggest that the anisotropy in this model does not affect the critical exponent of the correlation length,ν, which remains the same as the knownνin 2D isotropic lattices.
Four super integrable equations: nonlocal symmetries and applications
Authors: Zhou Hanyu , Tian Kai , Li Nianhua
Published: April 2022

By applying Hamiltonian operators to gradients of spectral parameters, nonlocal symmetries quadratically depending on eigenfunctions of linear spectral problems are constructed for super bi-Hamiltonian equations including a super modified Korteweg–de Vries (KdV) equation, a super K(−1, −2) equation, Kupershmidt’s super KdV equation and a super Ablowitz–Kaup–Newell–Segur system. In each example, the nonlocal symmetry is prolonged to an enlarged system, and generates a finite symmetry transformation. On this basis, a non-trivial solution, as well as a Bäcklund transformation, is established for the each super equation under consideration.
Chiral quantum network with giant atoms
Authors: Wang Xin , Li Hong-Rong
Published: April 2022

In superconducting quantum circuits (SQCs), chiral routing quantum information is often realized with the ferrite circulators, which are usually bulky, lossy and require strong magnetic fields. To overcome those problems, we propose a novel method to realize chiral quantum networks by exploiting giant atom effects in SQC platforms. By assuming each coupling point being modulated with time, the interaction becomes momentum-dependent, and giant atoms will chirally emit photons due to interference effects. The chiral factor can approach 1, and both the emission direction and rate can be freely tuned by the modulating signals. We demonstrate that a high-fidelity state transfer between remote giant atoms can be realized. Our proposal can be integrated on the superconducting chip easily, and has the potential to work as a tunable toolbox for quantum information processing in future chiral quantum networks.
Temperature and entanglement of the three-state quantum walk
Authors: Tude Luísa Toledo , de Oliveira Marcos César
Published: April 2022

In the present work, the evolution of a three state quantum walk without decoherence is investigated. Despite being a closed quantum system under unitary evolution, its Hilbert space can be divided in two subspaces, which enables the analysis of the subsystems (the coin or the walker) as an open system in contact with a reservoir. We calculate the asymptotic reduced density matrix of the coin space of the three-state quantum walk in an infinite line, and use that result to analyze the entanglement between the chirality, and position space. We calculate the von Neumann entropy and the entanglement temperature per mean energy of the system in the asymptotic limit.
Fixed points of Koch maps
Authors: Le Van Tu
Published: April 2022

We study endomorphisms constructed by Sarah Koch in [Teichmüller theory and critically finite endomorphisms, Advances in Mathematics 248 (2013), 573–617] and we focus on the eigenvalues of the differential of such maps at its fixed points. To each post-critically finite unicritical polynomial, Koch associated a post-critically algebraic endomorphism of

C
P

k

{\mathbb {CP}}^k

. Koch showed that the eigenvalues of the differentials of such maps along periodic cycles outside the post-critical sets have modulus strictly greater than

1
1

. In this article, we show that the eigenvalues of the differentials at fixed points are either

0
0

or have modulus strictly greater than

1
1

. This confirms a conjecture proposed by the author in his thesis. We also provide a concrete description of such values in terms of the multiplier of a unicritical polynomial.
Entry-Level Expectations for Pathologists’ Assistants
Authors: Kolheffer Kerwin M , Moudden Ismail E L
Published: April 2022

Objectives

The aim of this study was to assess expectations of performance that exist in the marketplace for entry-level pathologists’ assistants (PathAs), defined as recent graduates of a pathologists’ assistant program on their first day of employment.

Methods

A voluntary, anonymous survey was distributed to pathologist and PathA members of the American Society for Clinical Pathology by email. We assessed 98 professional activities of PathAs using a 5-point scale of expectations based on levels of trust placed in them. We also collected demographic information.

Results

A total of 728 participants responded to this survey, including 280 pathologists and 448 PathAs. We classified 98 activities according to expectations: independent performance (20/98), developing independence (48/98), and not expected of PathAs (5/98). Some activities (25/98) were indeterminate yet likely represent areas of developing independence.

Conclusions

This study demonstrates an expectation for entry-level PathAs to perform some activities included in the scope of practice independently but eventually to develop independent proficiency for most professional activities. A minority of activities were identified as responsibilities that are not expected of PathAs. Entry-level PathAs, therefore, remain “works in progress,” with an expectation for independent performance of core activities while developing abilities in many areas of professional practice.
A Correlation of the Glogau Scale With VISIA-CR Complexion Analysis Measurements in Assessing Facial Photoaging for Clinical Research
Authors: Oesch Sydney , Vingan Nicole R , Li Xingchen , Hoopman John , Akgul Yucel , Kenkel Jeffrey M
Published: April 2022

Background

Historically, standard evaluations for photoaging have involved subjective analysis; recently, however, investigators have turned to noninvasive systems for more objective evaluation of facial aging.

Objectives

The aim of this study was to establish a clinical correlation between the Glogau Photoaging Scale and the VISIA-CR Complexion Analysis System (Canfield Imaging Systems, Fairfield, NJ), and thereby reduce intra- and interobserver variability when assessing photodamage.

Methods

In total, 117 subjects aged between 18 and 89 years were included. Two-dimensional facial photographs were analyzed by 3 independent reviewers and assigned Glogau scores. Images were also captured and analyzed with VISIA software. Data were grouped by median Glogau score and compared between groups.

Results

All groups were statistically different (P < 0.05) for Spots, Wrinkles, and Remasked Wrinkles, except for Glogau 1 and 2 for Spots and Remasked Wrinkles. Scores for Wrinkles were plotted against age, and an exponential regression model was noted to be a better fit (R2 = 0.5) than a linear model (R2 = 0.47). The same was true for Spots with an exponential model (R2 = 0.36) compared with a linear model (R2 = 0.33). Scores were also evaluated based on sun exposure history, but no significant differences were observed.

Conclusions

The results illustrate that an imaging system can be used to reliably determine objective scores correlating to Glogau photoaging evaluations, and indicate that aging appears to be an exponential process. Collectively, these findings will assist future investigations of facial aging and the therapeutic options available for facial skin rejuvenation, and enable objective assessment of treatment outcomes.
Integrating multi-omics data to identify dysregulated modules in endometrial cancer
Authors: Chen Zhongli , Liang Biting , Wu Yingfu , Liu Quanzhong , Zhang Hongming , Wu Hao
Published: April 2022

Cancer is generally caused by genetic mutations, and differentially expressed genes are closely associated with genetic mutations. Therefore, mutated genes and differentially expressed genes can be used to study the dysregulated modules in cancer. However, it has become a big challenge in cancer research how to accurately and effectively detect dysregulated modules that promote cancer in massive data. In this study, we propose a network-based method for identifying dysregulated modules (Netkmeans). Firstly, the study constructs an undirected-weighted gene network based on the characteristics of high mutual exclusivity, high coverage and complex network topology among genes widely existed in the genome. Secondly, the study constructs a comprehensive evaluation function to select the number of clusters scientifically and effectively. Finally, the K-means clustering method is applied to detect the dysregulated modules. Compared with the results detected by IBA and CCEN methods, the results of Netkmeans proposed in this study have higher statistical significance and biological relevance. Besides, compared with the dysregulated modules detected by MCODE, CFinder and ClusterONE, the results of Netkmeans have higher accuracy, precision and F-measure. The experimental results show that the multiple dysregulated modules detected by Netkmeans are essential in the generation, development and progression of cancer, and thus they play a vital role in the precise diagnosis, treatment and development of new medications for cancer patients.
Development and validation of a nomogram to predict kidney survival at baseline in patients with C3 glomerulopathy
Authors: Caravaca-Fontán Fernando , Rivero Marta , Cavero Teresa , Díaz-Encarnación Montserrat , Cabello Virginia , Ariceta Gema , Quintana Luis F , Marco Helena , Barros Xoana , Ramos Natalia , Rodríguez-Mendiola Nuria , Cruz Sonia , Fernández-Juárez Gema , Rodríguez Adela , Pérez de José Ana , Rabasco Cristina , Rodado Raquel , Fernández Loreto , Pérez-Gómez Vanessa , Ávila Ana , Bravo Luis , Espinosa Natalia , Allende Natalia , Sanchez de la Nieta Maria Dolores , Rodríguez Eva , Olea Teresa , Melgosa Marta , Huerta Ana , Miquel Rosa , Mon Carmen , Fraga Gloria , de Lorenzo Alberto , Draibe Juliana , González Fayna , Shabaka Amir , López-Rubio Maria Esperanza , Fenollosa María Ángeles , Martín-Penagos Luis , Da Silva Iara , Alonso Titos Juana , Rodríguez de Córdoba Santiago , Goicoechea de Jorge Elena , Praga Manuel
Published: April 2022

Background

C3 glomerulopathy is a rare and heterogeneous complement-driven disease. It is often challenging to accurately predict in clinical practice the individual kidney prognosis at baseline. We herein sought to develop and validate a prognostic nomogram to predict long-term kidney survival.

Methods

We conducted a retrospective, multicenter observational cohort study in 35 nephrology departments belonging to the Spanish Group for the Study of Glomerular Diseases. The dataset was randomly divided into a training group (n = 87) and a validation group (n = 28). The least absolute shrinkage and selection operator (LASSO) regression was used to screen the main predictors of kidney outcome and to build the nomogram. The accuracy of the nomogram was assessed by discrimination and risk calibration in the training and validation sets.

Results

The study group comprised 115 patients, of whom 46 (40%) reached kidney failure in a median follow-up of 49 months (range 24–112). No significant differences were observed in baseline estimated glomerular filtration rate (eGFR), proteinuria or total chronicity score of kidney biopsies, between patients in the training versus those in the validation set. The selected variables by LASSO were eGFR, proteinuria and total chronicity score. Based on a Cox model, a nomogram was developed for the prediction of kidney survival at 1, 2, 5 and 10 years from diagnosis. The C-index of the nomogram was 0.860 (95% confidence interval 0.834–0.887) and calibration plots showed optimal agreement between predicted and observed outcomes.

Conclusions

We constructed and validated a practical nomogram with good discrimination and calibration to predict the risk of kidney failure in C3 glomerulopathy patients at 1, 2, 5 and 10 years.
An Unobtrusive Approach to Emotion Detection in E-Learning Systems
Authors: Rasheed Fareeha , Wahid Abdul
Published: April 2022

Researchers have proved that emotions play vital role in a human’s life. They affect our way of living, making decisions and also our way of learning. There are many methods for emotion detection in e-learning. However, each of them comes with its own set of disadvantages discussed in the literature review. In this paper, the attributes that have been identified are purely unobtrusive in nature; attributes that do not interfere with the learner’s activity and less is known to them that their emotions are being monitored. A methodology is presented to detect the emotions of the learner using keystrokes, mouse clicks, forum discussions and the results of assessments. Machine learning models have been trained and tested to predict the learner’s emotions. The logistic regression performed fairly well in comparison to the other algorithms with an accuracy of about 85% and cross-validation score of 86%. During this study, interesting patterns are observed in learner’s emotions that are discussed. Future directions include collecting diverse data to understand emotions of learners from various age groups and observing patterns in their emotional changes.
32: ENHANCED RECOVERY AFTER SURGERY CAN IMPROVE PATIENTS’ OUTCOMES AND REDUCE HOSPITAL COST OF GASTRECTOMY FOR CANCER IN THE WEST. A PROPENSITY SCORE-BASED ANALYSIS
Authors: Weindelmayer J , Mengardo V , Gasparini A , Sacco M , Torroni L , Carlini M , Verlato G , De Manzoni G
Published: April 2022

Background and aim

Data on ERAS for gastrectomy are scarce and the majority of the studies come from Eastern countries. Patients in the West are older and suffer from more advanced tumors that impair their clinical conditions and often require neoadjuvant treatment. This retrospective study assessed the feasibility and safety of an Enhanced Recovery After Surgery (ERAS) protocol for gastrectomy in a Western center.

Methods

We conducted a single-center study of 351 patients operated for gastric cancer: 103, operated from January 2015 to December 2016, followed the standard pathway, while 248, operated from January 2017 to December 2019, followed the ERAS program. The primary outcomes considered were length of hospital stay (LOS) and direct costs. Secondary outcomes were 90-day morbidity and mortality, readmission rate and compliance with ERAS items. A propensity score (PS) was built on confounding variables.

Results

Compliance with ERAS items after the program was ≥70%. Univariable analysis evidenced a 2-day median reduction in LOS and a median cost reduction of €826 per patient in ERAS group. PS-based multivariable analysis confirmed a significant 2-day decrease in median LOS and a €1097 saving after ERAS introduction. Ninety-day mortality decreased slightly in ERAS group, while complications and readmissions did not significantly change. When complications were included in the multivariable analysis, ERAS retained its significance, although the effects on LOS and cost were blunted: median reduction was one day and €775, respectively.

Conclusion

ERAS for gastrectomy improved patients’ recovery and reduced hospital costs without changes in morbidity, mortality or readmission.
33: A SNAPSHOT OF THE CURRENT PRACTICE ON THE USE OF PROPHYLACTIC DRAIN AFTER GASTRECTOMY IN ITALY: THE ABDOMINAL DRAIN IN GASTRECTOMY (ADIGE) SURVEY
Authors: Mengardo V , Weindelmayer J , Torroni L , Veltri A , De Manzoni G
Published: April 2022

Background and aim

Evidence against the use of prophylactic drain after gastrectomy are increasing. Nevertheless, it is unclear whether this practice is still widespread. We conducted a survey among Italian surgeons through the Italian Gastric Cancer Study Group and the Polispecialistic Society of Young Surgeons, aiming to understand the current use of prophylactic drain.

Methods

A 23-item questionnaire-based survey was developed to analyze the current practice and the individual opinion about the use of prophylactic drain after gastrectomy. Groups based on age, experience and unit volume were separately analyzed.

Results

Response of 104 surgeons from 73 surgical units were collected. A standardized ERAS protocol for gastrectomy was applied by 42% of the interviewed surgeons. The large majority of the surgeons, regardless of age, experience or unit volume, declared to routinely place one or more drain after gastrectomy. Only 2 (1.9%) and 7 surgeons (6.7%) belonging to high volume units, do not routinely place drains after total and subtotal gastrectomy, respectively. More than 60% of the interviewed remove the drain on postoperative day 4–6 after performing an assessment of the anastomosis integrity. Interestingly, less than half of the surgeons believe that drain is the main tool for leak management, and this percentage further drops among younger surgeons. On the other hand, drain’s role seems to be more defined for duodenal stump leak treatment, with almost 50% of the surgeons recognizing its importance.

Conclusion

Routine use of prophylactic drain after gastrectomy is still a widespread practice even if younger surgeons are more persuaded that it could not be advantageous.

New and stronger evidence are needed to define the role of prophylactic drain after gastrectomy.
35: DOES CARDIOPULMONARY TESTING HELP PREDICT LONG-TERM SURVIVAL AFTER OESOPHAGECTOMY?
Authors: Chmelo J , Khaw R , Sinclair R C , Navidi M , Phillips A W
Published: April 2022

Background and aim

Oesophagectomy is associated with a high rate of morbidity and mortality. Preoperative cardiopulmonary fitness has been correlated with outcomes within major surgery. Variables derived from CPET have been associated with postoperative outcomes. It is unclear whether preoperative cardiorespiratory fitness of patients undergoing oesophagectomy is associated with long-term survival. The aim of this study was to evaluate whether any of the cardiopulmonary exercise testing (CPET) variables that are routinely derived in patients with oesophageal cancer may aid in predicting long-term survival after oesophagectomy.

Methods

Patients undergoing CPET followed by trans-thoracic oesophagectomy for oesophageal cancer with curative intent between January 2013 and January 2017 from single high-volume centre were retrospectively analysed. The relationship between predictive co-variables including CPET variables, and survival was studied with a Cox proportional hazard model. Receiver operation curve (ROC) analysis was conducted to find cut-off values for CPET variables predictive of 3-year survival.

Results

A total of 313 patients were analyzed. The ventilatory equivalent for carbon dioxide (VE/VCO2) at anaerobic threshold was the only CPET variable independently predictive of long-term survival in multivariable analysis (HR 1.049, 95% CI 1.011–1.088, P = 0.011). Pathological stage III and IV disease was the other co-variable found to be independently predictive of survival. ROC analysis of the VE/VCO2 failed to demonstrate a predictive cut-off value of 3-year survival (AUC = 0.564, 95% CI 0.499–0.629, P = 0.056).

Conclusion

A high VE/VCO2 before oesophagectomy for malignant disease is an independent predictor of long-term survival and may be an important variable for consideration when counselling patients.
42: THE LAPAROSCOPIC HELLER-DOR IS AN EFFECTIVE LONG-TERM TREATMENT FOR END-STAGE ACHALASIA
Authors: Nezi G , Forattini F , Riccio F , Vittori A , Provenzano L , Capovilla G , Nicoletti L , Moletta L , Pierobon E S , Zanchettin G , Valmasoni M , Merigliano S , Costantini M , Salvador R
Published: April 2022

Background and aim

Laparoscopic Heller-Dor (LHD) is an effective treatment for esophageal achalasia, with good long-term results in more than 85–90% of patients. It remains controversial whether LHD is also indicated in the end-stage disease when the esophagus has a sigmoid shape. The aim of this study was to evaluate the outcome of LHD in patients with end-stage achalasia, as compared to patients with megaesophagus but without a sigmoid shape.

Methods

From 1992 to 2020, patients with a radiological diagnosis of sigmoid-shaped esophagus (radiological stage IV achalasia: group SE) and patients with straight, larger than 6 cm in diameter esophagus (radiological stage III achalasia: group NSE), both treated with LHD, were compared. Treatment failure was defined as the persistence or reoccurrence of an Eckardt score > 3, or the need for retreatment.

Results

During the study period, 164 such patients were observed: 73 patients in the SE group and 91 in the NSE group. The patients’ demographic and clinical parameters are summarised in Table 1. The median follow-up was 67 months (IQR: 24–106). No intra or postoperative mortality was recorded. There were 7 mucosal lesions: 2 in the SE group and 5 in the NSE group (P = 0.45). A positive outcome was obtained in 73% of patients in the SE group, as compared to 90% in the NSE group (P = 0.007, Table 2). All the patients whose surgery failed subsequently underwent one or more endoscopic pneumatic dilations. The overall success rate of the combination of LHD and endoscopic dilations was 83.6% in the SE group and all patients in the NSE group. The persisting failures had additional treatments: 4 patients a redo-myotomy, one each a botox injection, POEM and only one patient had an esophagectomy; the remaining 5 patients refused additional treatments. Postoperative 24-hour pH-monitoring was abnormal in 16.6% in SE group and 8.3% in NSE group (P = 0.33).

Conclusion

In end-stage achalasia patients, LHD may still achieve good results by relieving symptoms in more than 70% of patients. Therefore, LHD may still be the first surgical option to be offered to these patients before esophagectomy.
55: COMPETENCY ASSESSMENT TOOL FOR MINIMALLY INVASIVE ESOPHAGECTOMY: DEVELOPMENT AND PRELIMINARY CONSTRUCT VALIDITY AND RELIABILITY RESULTS
Authors: Ketel M , Hannink G , Eddahchouri Y , Klarenbeek B ,   Collaboration Group M, Van Workum F , Rosman C
Published: April 2022

Background and aim

Performance of the surgical team is essential for patient outcome. Minimally invasive esophagectomy (MIE) is a complex and technically demanding procedure and implementation is associated with a substantial learning curve. A validated, procedure specific and scientifically robust competency assessment tool (CAT) could provide structured feedback and can be a tool to improve patient outcome. The aim is to develop a MIE-CAT and assess construct validity, intra-observer reliability and inter-observer reliability.

Methods

Based on defined key steps from a Delphi study and refinement with a core group of MIE experts to establish content validity and obtain user agreement, the MIE-CAT was developed. Eighteen independent and blinded international MIE experts (> 120 MIEs performed) followed an online workshop to train in using the MIE-CAT and assessed Ivor Lewis MIE videos that were performed from 2010–2020 by four MIE surgeons from the Esophageal Center East Netherlands. To analyze construct validity, 32 videos were divided into four groups (novice, intermediate, advanced and expert) based on the surgical team’s experience. For intra-rater and inter-rater reliability, the same video was scored twice by the same and different experts.

Results

The MIE-CAT consists of eight procedural phases, starting with the mobilization of the greater curvature and ending with creation of the intrathoracic anastomosis. Each phase contains four domains (exposure, execution, adverse events and end-product quality) and are scored with a 1–4 Likert scale. A total of 72 video assessments were used for analysis. Substantial performance variation between the MIE-CAT scores was seen (median 98 [IQR, 84–113.4]; range = 47–126). Median MIE-CAT scores were 79.5 [IQR 74–96.3], 91 [87.5–107], 101 [84.8–108] and 101 [95.5–108.3] for respectively the novice, intermediate, advanced and expert group (Figure 1). Significant differences between the average MIE-CAT scores of the experience groups were found with a Kruskal Wallis (P = 0.002). Good intra-rater reliability was observed (ICC, 0.71, 95% CI [0.35, 0.89) and moderate inter-rater reliability was observed (ICC, 0.54, 95% CI [0.10, 0.87).

Conclusion

A specific competency assessment tool to score the MIE performance, the MIE-CAT, was developed. It has the potential to be used for surgical training, safe implementation, performance improvement and research purposes.
116: INFLUENCE OF BODY COMPOSITE MEASURES ON CHYLE LEAK AFTER OESOPHAGECTOMY
Authors: Halle-Smith J , Subramanya M , Ghoneim A , Almonib A , Tan B
Published: April 2022

Background and aim

Chyle leak is an infrequent but potentially serious complication of oesophagectomy. Sarcopenia is an increasingly recognised prognostic factor in oesophageal cancer surgery. The aim of this study was to identify the influence of body composition and related factors on chyle leak following oesophagectomy.

Methods

Patients who developed chyle leak after oesophagectomy between January 2006–December 2020 were identified retrospectively from a prospectively collected and maintained dataset. A control group of patients undergoing oesophagectomy during the same time period was also collected. Relationships between chyle leak and demographics, operative factors and body composition measures were investigated as primary outcomes. Risk factors for severe chyle leak, defined as need for reintervention or greater than 1 litre of output per day, were evaluated as a secondary outcome.

Results

There were 26 patients who developed a chyle leak following an oesophagectomy. On univariate analysis, preoperative body mass index (BMI) (P = 0.001), subcutaneous fat index (P = 0.001) and total fat index (P = 0.004) were significantly associated with chyle leak. On multivariate analysis, a lower preoperative subcutaneous fat index was a significant independent predictor of chyle leak (P = 0.001). Sarcopenia was not found to be a significant predictor of developing chyle leaks. No significant predictors of severe chyle leak were identified.

Conclusion

A reduced preoperative body fat composition is a risk factor for chyle leak after oesophagectomy. Sarcopenia doesn’t predict either the occurrence or severity of chyle leak. This emphasises the importance of physiological and nutritional optimisation before oesophagectomy.
126: CLINICAL RELEVANCE OF THE TUMOUR LOCATION-MODIFIED LAURÉN CLASSIFICATION SYSTEM OF GASTRIC CANCER IN A WESTERN POPULATION
Authors: Jonathan M , Davies A , Santaollala A , Van Hemelrijk M , Maisey N , Lagergren J , Gossage J , Kelly M , Baker C
Published: April 2022

Background and aim

The Tumour Location-Modified Laurén Classification (MLC) system of gastric cancer combines Laurén histological subtype and anatomical tumour location. It divides tumours into proximal non-diffuse (PND), distal non-diffuse (DND) and diffuse type. The optimum classification of patients with Laurén mixed tumours within this system is not clear, having been grouped with both diffuse and non-diffuse type in previous studies. The clinical relevance of the MLC has not previously been examined in a Western population.

Methods

Cohort study including 404 patients who underwent gastrectomy for gastric adenocarcinoma between 2005–2020. Receiver operating characteristic (ROC) curve analysis was performed to establish the optimal categorisation of Laurén mixed tumours within the MLC when used to predict survival. Survival analysis was performed using Kaplan–Meier and Cox regression.

Results

ROC curve analysis demonstrated higher area under the curve (AUC) for predicting overall survival when Laurén mixed tumours were grouped with non-diffuse rather than diffuse type (0.583 vs 0.569). This classification was therefore used for survival analysis. Distal non-diffuse tumours had the best 5-year survival (64.7% DND vs 56.1% PND vs 45.1% diffuse, P = 0.006) and were least likely to have recurrence (27.0% DND vs 34.3% PND vs 48.3% diffuse, P = 0.001). Multivariable analysis demonstrated the MLC was an independent prognostic factor for survival (PND HR 1.64, 95% CI 1.16–2.32, Diffuse HR 2.20, 95% CI 1.56–3.09).

Conclusion

The MLC was an independent marker for predicting survival in this Western cohort of patients with gastric adenocarcinoma. Patients with proximal non-diffuse and diffuse tumours had worse survival than those with distal non-diffuse tumours.

Table

https://secure.sem-2000.it/semUpload/OLC/file/9203828791100911681076702/94279_Table.jpg.
133: QUALITY OF RECOVERY AFTER SUBTOTAL GASTRECTOMY USING QOR-40
Authors: Feenstra M , Küçükçelebi S , Van Berge Henegouwen M , Hollmann M , Gisbertz S , Daams F , Albersen J , Ten Hoope W , Hermanides J , Eshuis W
Published: April 2022

Background and aim

Gastric cancer surgery highly impacts postoperative quality of life. The Quality of Recovery-40 (QoR-40) is a validated 40-item patient questionnaire, designed to evaluate the quality of recovery after anesthesia. QoR-40 is subcategorized in five dimensions; physical comfort, physical independence, psychological support, emotional state and pain. The aim of this study was to evaluate the quality of recovery after subtotal gastrectomy using the QoR-40 questionnaire and to establish a reference standard for the QoR-40 after gastrectomy to be used in future studies.

Methods

This prospective observational study included all patients undergoing subtotal gastrectomy between January 2020 and December 2020 in the Amsterdam UMC. Primary endpoint was the quality of recovery on day three after surgery, using the Dutch QoR-40. Secondary endpoint was the occurrence of poor quality of recovery (PQR), defined as impairment in 2 or more dimensions, or impairment in the global QoR-40.

Results

27 Patients were included in this study, the median total score of the QoR-40 questionnaire was 184 [IQR 176–192]. Eight patients had a PQR, of whom four patients (50.0%) developed postoperative complications. Furthermore, two patients without PQR developed complications (7.4%). Impairment occurred mainly in dimensions physical comfort, physical independence and emotional state.

Conclusion

This study presents a reference standard for quality of recovery based on the QoR-40 questionnaire in patients undergoing subtotal gastrectomy. PQR may be related to postoperative complications. Future studies should focus on enhancing physical comfort, physical independence and emotional state to improve patient reported quality of recovery.
137: LAPAROSCOPIC DISTAL GASTRECTOMY: JUST AN OPTION OR THE NEW GOLD STANDARD FOR ELDERLY PATIENTS?
Authors: Viganò J , Palmieri F , Peri A , Fugazzola P , De Stefano F , Sargenti B , Pietrabissa A
Published: April 2022

Background and aim

The application of laparoscopy in elderly patients with gastric cancer is controversial, especially in Western population. The aim of the study is to evaluate the feasibility of a laparoscopic approach and compare short-term outcomes with results obtained using traditional open surgery.

Methods

Data concerning 52 elderly patients (≥70 years), who underwent distal gastrectomy at our institution from January 2017 to August 2020, were retrospectively analyzed. We divided the population into two cohorts according to the surgical technique (laparoscopic or open surgery) and we compared the short-term outcomes. The open and laparoscopic cohorts were compared in terms of demographics, ASA score, pTNM stage, the pathological pattern according to Lauren classification, time of surgery, selected type of gastrointestinal reconstruction, the extension of lymphadenectomy and number of lymph nodes resected, postoperative complications classified according to modified Clavien-Dindo system, length of stay (LOS), postoperative mortality within 30 days. Univariate and multivariate analyses were performed for length of stay, including age, sex, duration of surgery, BMI, technique, tumor localization, grading, reconstruction, ASA, Lauren stage, extension of lymphadenectomy, TNM stage, and neoadjuvant chemotherapy as variables.

Results

Demographics, pathological characteristics and surgical outcomes were comparable in both cohorts, except for the length of hospital stay (LOS) that was significative longer in the open cohort (12,31 vs 8,42 P = 0.02). Number of harvested lymph nodes and complete resection (R0) rate were similar, leading to comparable oncological results. Based on the univariate analysis, in addition to the approach, ASA score was another factor significantly associated to LOS (ASA 2 8,4 ± 2,1 days vs ASA 3 13,5 ± 7,8 days). A multiple regression was run to predict LOS from ASA and surgical approach. The multiple regression model statistically significantly predicted LOS, F(3,44) = 6,906, P < 0,002. The surgical approach showed a certain trend to significance in predicting LOS, P = 0,09.

Conclusion

Laparoscopic distal gastrectomy is effective and safe in elderly patients with similar short-term outcomes compared to open distal gastrectomy. The main advantage of laparoscopic technique is a shorter length of hospital stay.
148: LAPAROSCOPIC FUNDOPLICATION FOR PARA-ESOPHAGEAL HERNIA REPAIR IMPROVES RESPIRATORY FUNCTION IN PATIENTS PRESENTING WITH DYSPNEA: A PROSPECTIVE COHORT STUDY
Authors: Bouriez D , Belaroussi Y , Boubaddi M , Martre P , Berger P , Gronnier C
Published: April 2022

Background and aim

Dyspnea in patients with a para-esophageal hernia (PEH) occurs in 7 to 32% of cases and is very disabling, especially in the elderly and its origin is poorly defined. The present study aims to assess the impact of laparoscopic fundoplication (LF) on dyspnea and respiratory function.

Methods

Dyspnea assessment through dyspnea visual analogic scale (DVAS) and modified medical research council score and pulmonary function test (PFT) with plethysmography were performed before and 2 months after LF in all consecutive patients undergoing LF for PEH from January 2019 to May 2021.

Results

All 43 patients included had pre-and postoperative dyspnea assessments and pulmonary PFT. Patients’ median age was 70 years (range 63–73.5 years), 37 (86%) were women, the median percentage of the intrathoracic stomach was 59.9% (range 44.2%–83.0%), the median length of hospital stay was 3 days (range 3–4 days). After surgery, the DVAS decreased statistically significantly (5.6 [4.7–6.7] vs 3.0 [2.3–4.4] P < 0.001), and 37 (86%) patients had a clinically significant decrease inMMRC. Absolute forced expiratory volume in one second (FEV1), total lung capacity, and forced vital capacity also statistically significantly increased after surgery respectively on average by +11.2% (SD 17.9), +5.0% (SD 13.9), and + 10.7% (SD 14.6).

Subgroup analysis highlighted patients with low preoperative FEV1 were more susceptible to improve it. No correlation was identified between improvement in dyspnea and FEV1. Also, no correlation was identified between the percentage of intrathoracic stomach and dyspnea or PFT parameters improvement.

Conclusion

PEH repair improves dyspnea and FEV1 in a statistically significant manner in a population of patients presenting with dyspnea. Patients with a low preoperative FEV1 are more likely to improve it after LF.
160: PATIENT-TAILORED ALGORITHM FOR POSTERIOR CRUROPLASTY: TECHNIQUE DESCRIPTION AND COMPARISON WITH HIATAL SURFACE AREA
Authors: Sozzi A , Aiolfi A , Lombardo F , Cavalli M , Campanelli G , Bona D
Published: April 2022

Background and aim

Different surgical techniques have been described for laparoscopic crural approximation, ranging from simple suture to mesh reinforced repair. Nowadays, the choice of the most appropriate surgical strategy is left to surgeon experience and lacks of standardization. Our objective is to describe a patient-tailored decisional algorithm based on intraoperative findings and measurements (Table 1). In addition, we aimed to compare this technique with the previously described Hiatal Surface Area (HSA) method.

Methods

Prospective single-center cohort study (November 2015–June 2021). Perioperative outcomes, timing of recurrence, and quality of life were analysed.

Results

Overall, 104 patients were included. Overall, 78 (75.0%) patients underwent simple suture repair (= < 5points) while crural mesh [Phasix ST®-Bard] repair as used in 26 (25.0%) patients (Figure 1). Our patient-tailored algorithm was compared to HSA method in 30 patients, with 93.3% of concordance. Toupet fundoplication was fashioned in all patients. No intraoperative complications occurred. The median postoperative stay was 1.8 days (range 1–7). The overall postoperative complication rate was 3.8%. The median follow-up was 29 months (range 1–58) with 95 patients having a minimum follow-up of 6 months. No mesh-related complication occurred. Recurrent hernia was diagnosed in three patients (2.9%) all managed with PPI. Compared to baseline, the median GERD-HRQL (P = 0.003) was significantly improved.

Conclusion

The application of a ‘patient-tailored’ decisional algorithm is safe and seems effective in the medium-term follow-up. The use of this algorithm may improve procedure reproducibility and standardization. The comparison with the HSA showed a high concordance, even though our algorithm is simpler and more manageable.

Table

https://secure.sem-2000.it/semUpload/OLC/file/9203828791100911681076702/94476_Table.jpg.