bluuebunny/crossref_metadata_2025 huggingface dataset:
Enhancing airport runways performance using composite systems numerically using unit cell concept.
Authors: Abdelaziz A. M. , Elshesheny Ahmed , Abdelmotaal Nabil , Nagy Nabil M.
Published: December 2023

One of the problems, which would affect airport runways is the settlement of soil. Such settlement would be controlled by enhancing the performance of the soil underneath the airport runway. The composite system consists of graded stone-reinforced soil and reinforcing layers. This system is defined as stone column, which is widely used to improve weak soils as one of the soil stabilization methods due to its simple construction and economic cost. It is used to reduce settlement and enhance soil-bearing capacity. By using such technique, part of the high-compressibility and low-shear strength soil is replaced with coarse filler materials with high-shear strength and extremely low compressibility. In this study, a 3D numerical model of a unit cell is created to examine the impact of changing the controlling parameters in the model, i.e. spacing between columns (S), weak soil cohesion (c), and angle of internal friction for stone column material (φ). It was established that the use of stone columns improves the soil-bearing capacity and reduces settlement, strengthening the stability of airport runways. The efficiency of the system is improved by increasing the column material’s internal friction angle and the cohesion of the surrounding soil. The ultimate bearing capacity of soil without SC and SC-soil systems were 150 kPa, and 460 kPa, respectively, which illustrates that the bearing capacity was increased by 306.7%.
Challenges with onboard strain measurements on a model Francis turbine runner
Authors: Kverno Johannes , Vefring Gaute Elde , Iliev Igor , Solemslie Bjørn Winther , Dahlhaug Ole Gunnar
Published: December 2023

As the world transitions towards more renewable energy sources, as a step to reduce the emissions of CO2, intermittent and non-dispatchable sources like solar and wind will take up a larger proportion of the energy production. With more unregulated power in the energy mix, a higher demand is put on the rest of the energy production system. Hydropower is in a unique position as it is both renewable and a highly flexible energy source. The increased use of flexible operation of Francis turbines especially, puts a higher dynamic load on the runner components which as a consequence leads to a reduced lifetime. In this paper we present the experimental setup and results from a measurement campaign performed on a model of a low specific speed Francis runner. Onboard measurements with strain gauges at the trailing edge of two runner blades were performed. The experiments were conducted as a part of the HydroFlex project with the goal of validating numerical simulations and to gain a better understanding of the reduction of lifetime on Francis turbines due to higher fatigue loading from more flexible operation. The results shows that there were a significant drift of the mean strain over time during the measurement campaign, and a lower measured strain at BEP than expected when compared to numerical simulations. In this paper, the experimental setup, results and challenges encountered are presented.
Numerical Analysis of Francis Turbine being operated in variable speed from sediment erosion perspective
Authors: Ghimire Amul , Kayastha Atmaram , Bijukchhe Pawan Lal , Chitrakar Sailesh , Neopane Hari Prasad
Published: December 2023

Sediment erosion in hydro turbines is one of the most daunting reasons incurring huge losses to power plant owners located in the Hindu Kush Himalayan region. Repetitive repair and maintenance of runners of Francis turbines installed in such power plants have been one of the major contributor to these losses. There is no measure of how much these power plant owners have lost due to reduction in efficiency brought about by the eroded surfaces of runners. Amidst several optimizations performed in changing the runner design, this study has been conducted to study the applicability of the pre-existing designs being operated in variable speed conditions, irrespective of its practical difficulties. Numerical simulations have been performed to determine the sediment erosion of the runners at different operating conditions. In addition to the guide vane angles, and the amount of sediment injected into the system; which is parametrized as a function of the guide vane angles; rotational speed of the runner has also been varied. Complete efficiency hill diagram and sediment erosion hill diagram have been developed to analyse the efficiency and sediment erosion at several operating conditions. Finally a comparison of the variations in efficiency and sediment erosion upon operating the turbine in synchronous speed and variable speed modes have been shown. Basically, the efficiency of the turbine and sediment erosion on blade surface can be increased and decreased respectively, at off design conditions by operating the turbine in variable speed.
Design and Fabrication of Automatic Voltage Stabilizer using Relay-Based Tap Changing of Transformer
Authors: Chaudhary C , Kshetri A , Shrestha A , Bista A , Bista D
Published: December 2023

The growing demand for power, and fluctuations in the load present challenges for maintaining a stable and continuous voltage supply. A voltage stabilizer is an electrical appliance that is designed in such a way that it delivers a constant output voltage regardless of the variation in the input supply voltage. This research explores various measures aimed at stabilizing the voltage supply in the face of increasing power demand and fluctuations in load, to ensure a constant output voltage. To this end, a microcontroller-based Automatic Voltage Stabilizer is presented as a robust solution. A prototype of the device, with a power rating of 1kVA and operating at a frequency of 50 Hz, has been fabricated and includes components such as an autotransformer, relay board, voltage sensors, and an Arduino microcontroller. The autotransformer’s taping is adjusted in response to changes in the input voltage. Experimental results show that the prototype can effectively regulate the voltage output between 190V to 250V under a load of 300W.
Review of Industrial Heating and Potential Low-carbon Fuels in the Context of Nepal.
Authors: Ghimire A , Pandey B , Ghimire R , Thapa B S
Published: December 2023

Process heating is an important step in manufacturing industries such as metal, cement, brick, food, etc., and accounts for a large share of the total energy consumption of those industries. In Nepal, process heating alone accounts for around 64% of the process energy of the manufacturing sector. Around 64% of Nepalese industries’ energy demand for process heating is supplied by high-carbon emitting fossil fuels such as coal, diesel, etc. The industrial sector is responsible for significant global greenhouse gas emissions. Nepalese manufacturing Industries emit around 0.002248 GT of CO2 annually. The movement toward carbon neutrality has prompted many countries around the world to look for clean and sustainable fuel to meet their decarbonization goal. This study overviews Nepalese industries’ different industrial heating processes in terms of energy consumption, emissions, energy efficiency measures and interventions, and renewable options from a literature review and using data from secondary sources. Based on the data collected and the literature review of the industries, the potential low-carbon fuels which can be compatible with heating applications in Nepalese industries are reviewed. This paper concludes with recommendations for the future decarbonization of process heating in Nepalese industries.
Evaluating natural degassing in a river to create a baseline for comparison to technical degassing methods.
Authors: Ludwig Kuhn W. , Solemslie Bjørn Winther , Hihn Jean-Yves , Dahlhaug Ole Gunnar
Published: December 2023

In Norway, a recent project used a risk matrix to identify about 200 hydropower plants ( 11 % of the total number) of being in high risk of producing air-supersaturated water. The combined installed capacity of these hydropower plants amounts to more than 45 % of Norway’s total installed hydropower capacity. Total dissolved gas (TDG) supersaturation in water is, dependent on the actual saturation value and the duration of the occurrence, lethal to certain types of fish and aquatic invertebrates. Natural degassing is highly dependent on the morphology of the downstream water system, but tends to be insufficiently slow with regard to lethality of TDG supersaturation. The Brokke power plant in southern Norway is known to create TDG supersaturation. Since 2012, continuous monitoring of the TDG level happens at the power plant outlet and several positions in the Otra river downstream. Measurement data has been evaluated and a method has been developed to calculate the liquid-gas mass transfer coefficient kLa as an indicator for the natural degassing efficiency within certain stretches of the river using assumptions for the river’s geometry. The results are in agreement with former evaluation of the measurements. At the Waterpower Laboratory at NTNU in Trondheim, Norway, a test rig has been designed and instrumented to prove the effectiveness of degassing methods. An in-house pressure system is used to produce air-supersaturated water, which is then channeled through an open flume. At the flume’s inlet, the degassing mechanism is installed. The TDG levels are monitored both upstream and at downstream the degassing device. The kLa will be used to compare natural degassing in the river downstream Brokke power plant to the experimental degassing methods in the Waterpower Laboratory.
Anomaly Identification Model of Power Battery Self-discharge Based on Deep Belief Networks
Authors: Wang Peng , Yan Wen , Shen Bin , Liang Xinmiao
Published: December 2023

Electric vehicles will receive signal data such as voltage and current while the vehicle is running, which can reflect the safety status of the vehicle. Therefore, a quantitative description of the safety status of power batteries during operation can be achieved by analyzing and mining the safety features contained in the historical data of the vehicle that is running. However, considering the physical characteristics of the battery system and factors such as sensor design and acquisition accuracy, there is inevitably information coupling, redundancy, and error between different signals, making it difficult to extract and quantify safety features accurately. To solve this problem, this paper combines the identification method of abnormal risk characteristics of self-discharge of power battery, constructs abnormal risk characteristics of self-discharge of power battery, and completes the calculation and safety quantification of self-discharge risk characteristics. On this basis, by combining multiple safety features with the vehicle safety status obtained from the above analysis, a supervised learning sample data set is constructed, and the deep confidence network (DBN) is used to map and describe the vehicle safety feature data and the vehicle safety status, so as to achieve accurate judgment and fault identification of the vehicle comprehensive status.
Research on Lean Improvement of a Powder Production Line Based on Contradiction Analysis
Authors: Guo Jidong , Chen Jie , Long Lijian , Huang Jie , Yang Yiben , Zhang Yongyang
Published: December 2023

The intelligent improvement of production and manufacturing plays an important role in providing automated production for a company. In response to the problems of low production efficiency, high defect rate, and slow mold change in a certain company’s powder production site, this study combines the ideas of quality management and lean improvement, and analyzes the equipment utilization and production capacity through methods such as contradiction analysis, process function analysis, and fishbone diagram, By using Flexsim simulation and analytic hierarchy process, an optimization plan was obtained, which shortened the processing time and mold change time, improved the production capacity of the production line, and provided specific solutions and new ideas for the company’s production and operation. This helps to improve the technical performance of process oriented manufacturing production.
Low-light Image Enhancement Method Based on Illumination Curve Adjustment
Authors: Cheng Fensen , Zhang Jun
Published: December 2023

This paper presents an advanced low-light image enhancement approach based on Zero-Reference Deep Curve Estimation. The technique enhances images through: (1) the integration of the Dynamic Stochastic Resonance equation for enhanced contrast and brightness, leveraging adjustable parameters for optimal image quality, and (2) application of an Anisotropic Diffusion function for image denoising and smoothing, preserving edges and texture details while effectively removing noise. This adaptive algorithm tailors diffusion intensity to local image features, further refining the resulting image quality. Experimental results confirm the efficacy of our approach in improving visual quality and noise removal in low-light images.
Can Explainable Artificial Intelligence Optimize the Data Quality of Machine Learning Model? Taking Meibomian Gland Dysfunction Detections as a Case Study
Authors: Wang Mini Han , Zhou Ruoyu , Lin Zhiyuan , Yu Yang , Zeng Peijin , Fang Xiaoxiao , yang Jie , Hou Guanghui , Li Yonghao , Yu Xiangrong , Chong Kelvin Kam-Lung
Published: December 2023

Data quality plays a crucial role in computer-aided diagnosis (CAD) for ophthalmic disease detection. Various methodologies for data enhancement and preprocessing exist, with varying effectiveness and impact on model performance. However, the process of identifying the most effective approach usually involves time-consuming and resource-intensive experiments to determine optimal parameters. To address this issue, this study introduces a novel guidance framework that utilizes Explainable Artificial Intelligence (XAI) to enhance data quality. This method provides evidence of the significant contribution of XAI in classifying meibomian gland dysfunction (MGD) by aiding in feature selection, improving model transparency, mitigating data biases, providing interpretability, enabling error analysis, and establishing trust in machine learning (ML) models using multi-source meibomian datasets. The experimental results demonstrate substantial performance improvements in ML models when utilizing enhanced datasets compared to original images, as indicated by increased accuracy (0.67 vs. 0.86), recall (0.46 vs. 0.89), F1 score (0.48 vs. 0.84), XAI indicator (0.51 vs. 0.81), and IOU score (0.44 vs. 0.79). These findings highlight the significant potential of XAI in ML model MGD classification, particularly in advancing interpretability, standardization, fairness, domain integration, and clinical adoption. Consequently, the proposed framework not only saves valuable resources but also provides interpretable evidence for decision-making in data enhancement strategies. This study contributes to the understanding of XAI’s role in ML model MGD classification and its potential for driving advancements in key areas such as interpretability, standardization, fairness, domain integration, and clinical adoption.
The Optimal Layout Combination of Radar Stations in Multi-station Passive Time Difference Positioning System
Authors: He Jian , Song Shuling , Pu Renwei
Published: December 2023

This paper investigates the problem of optimizing the selection of radar site in three-dimensional terrain for multi-site passive time-difference positioning system. First, the directness of the radar to the surveillance airspace is investigated. A judgment method based on planar convex closure is given to determine whether a terrain point obscures the radar site to be selected, based on it, a screening algorithm is given to find the region where the received signals are not blocked. Second, the problem of optimal position combination of multiple radar stations is investigated. Taking a convex polygonal surveillance airspace as the object of study, a planning model with the objective of selecting the optimal combination of radar positions is given, which takes into account the constraints on the radar’s directness to the surveillance airspace, as well as the constraints on the far bounds of the detections, and proposes a genetic algorithm for solving the model, which uses an individual coding of the real type and introduces the penalty coefficients, which transforms the constrained planning problem to an unconstrained planning problem.
Research on the Numerical Method of Pollutant Emission during Gas Turbine Start-up
Authors: Wang Gugofeng , Chen Kun , Fan Hongtao , Huang Sijia , Xie Zhiyuan , Shen Huixia
Published: December 2023

It was of great research value and significance to predict the pollutant emission from the gas turbine start-up process by numerical method, which could improve the operation and regulation of gas turbines. In the paper, the computational fluid dynamics(CFD)-chemical reaction network (CRN) method was used to study the pollutant emission of gas turbines. According to the control process of the start-up control module, the start-up process had been divided into 12 states, and the CFD numerical analysis was carried out. Based on the data of Damkohler number (Da), temperature and velocity obtained by CFD, the chemical reaction network model of each state point was established. The research showed that the design parameter value of the state point was the basis of compiling the calculation process and source code; The basic data and partition basis for the chemical reaction network could been provided by the results of CFD analysis, which was an important guarantee for accurate prediction of NOx; The method of CFD-CRN could accurately predict NOx emission of gas engine during start-up, and provided reasonable and reliable research means and mathematical methods.
Automatic Matching of Optical and SAR Images Based on Attention Structure Features
Authors: Deng Jiwei , Yang Chao , Gong Guoqin , Zhao Hai , Wang Lei , Ye Yuanxin
Published: December 2023

Due to the disparity in imaging techniques, significant radiometric and geometric variances exist among optical and Synthetic Aperture Radar (SAR) images, making it a challenging task for achieving automatic and accurate matching in contemporary international academic research. Handcrafted structural features have shown some success in heterogeneous image matching in recent years. However, improving its matching performance manually proves to be difficult. As a result, this work presents a matching strategy based on attention-enhanced structural feature representation to improve optical and SAR images matching accuracy. In this research, a novel multi-branch global attention module is built using handmade structural feature extraction. This module can focus on the common information of structural feature descriptors in space and channel, extracting finer and more robust image features. Then, the proposed method utilizes the sum of squared difference (SSD) learning metric, which is based on the fast Fourier transform, to develop a loss function. This loss function is then used to train positive and negative samples in order to enhance the discriminative ability of the model. Experimental results obtained from training and testing on numerous optical and SAR datasets demonstrate that the proposed method significantly improves the accuracy of matching optical and SAR images compared to both current structural feature matching methods and advanced deep learning matching models.
Design of Fully Differential Amplification Circuit and Analysis of Related Parameters Based on Feedback Mechanism
Authors: Zhu Liyong , Wang Hangyan
Published: December 2023

In this paper, a new feedback-based mismatch reduction method is proposed for CMOS process-based differential circuit design. The method combines an active feedback circuit and a differential amplifier circuit to reduce the error caused by device mismatch by utilizing the feedback signal, which is calculated to achieve higher circuit performance and accuracy. Meanwhile, based on the actual circuit simulation in Candence, it is concluded that under the conditions of input voltage of 5V, operating current of 100mA, and the same transistor parameters, the circuit with the introduction of the feedback mechanism is able to achieve a maximum gain of about 10dB and a lower common mode rejection ratio at the same frequency compared with the circuit without feedback.
Gaseous argon time projection chamber with electroluminescence enhanced optical readout
Authors: Amarinei R.M. , Sánchez F. , Bordoni S. , Lux T. , Giannessi L. , Roe E. , Radicioni E.
Published: December 2023

Systematic uncertainties in accelerator oscillation neutrino
experiments arise from nuclear models describing neutrino-nucleus
interactions. To mitigate these uncertainties, we can study
neutrino-nuclei interactions with detectors possessing enhanced
hadron detection capabilities at energies below the nuclear Fermi
level. Gaseous detectors not only lower the particle detection
threshold but also enable the investigation of nuclear effects on
various nuclei by allowing for changes in the gas composition. This
approach provides valuable insights into the modelling of
neutrino-nucleus interactions and significantly reduces associated
uncertainties. Here, we discuss the design and first operation of a
gaseous argon time projection chamber optically read. The detector
operates at atmospheric pressure and features a single stage of
electron amplification based on a thick GEM. Here, photons are
produced with wavelengths in the vacuum ultraviolet regime. In an
optical detector, the primary constraint is the light yield. This
study explores the possibility of increasing the light by applying a
low electric field downstream of the ThGEM. In this region, called
the electroluminescence gap, electrons propagate and excite the
argon atoms, leading to the subsequent emission of photons. This
process occurs without any further electron amplification, and it is
demonstrated that the total light yield increases up to three times
by applying moderate electric fields of the order of
3 kV/cm. Finally, an indirect method is discussed for determining
the photon yield/charge gain of a ThGEM, giving a value of
18.3 photons detected per secondary electron.
Impact of T
i/T
e ratio on ion transport based on EAST H-mode plasmas
Authors: LIU 刘 Jianwen 建文 , ZANG 臧 Qing 庆 , LIANG 梁 Yunfeng 云峰 , CHEN 陈 Jiale 佳乐 , WU 邬 Xiaohe 潇河 , KNIEPS Alexander , HU 扈 Jiahui 嘉辉 , JIN 金 Yifei 仡飞 , ZHANG 张 Bin 斌 , CHU 储 Yuqi 宇奇 , LIU 刘 Haiqing 海庆 , LYU 吕 Bo 波 , DUAN 段 Yanmin 艳敏 , LI 李 Miaohui 妙辉 , CHEN 陈 Yingjie 颖杰 , GONG 龚 Xianzu 先祖 , Team the EAST
Published: December 2023

At the EAST tokamak, the ion temperature (T
i) is observed to be clamped around 1.25 keV in electron cyclotron resonance (ECR)-heated plasmas, even at core electron temperatures up to 10 keV (depending on the ECR heating power and the plasma density). This clamping results from the lack of direct ion heating and high levels of turbulence-driven transport. Turbulent transport analysis shows that trapped electron mode and electron temperature gradient-driven modes are the most unstable modes in the core of ECR-heated H-mode plasmas. Nevertheless, recently it was found that the T
i/T
e ratio can increase further with the fraction of the neutral beam injection (NBI) power, which leads to a higher core ion temperature (T
i0). In NBI heating-dominant H-mode plasmas, the ion temperature gradient-driven modes become the most unstable modes. Furthermore, a strong and broad internal transport barrier (ITB) can form at the plasma core in high-power NBI-heated H-mode plasmas when the T
i/T
e ratio approaches ~1, which results in steep core T
e and T
i profiles, as well as a peaked n
e profile. Power balance analysis shows a weaker T
e profile stiffness after the formation of ITBs in the core plasma region, where T
i clamping is broken, and the core T
i can increase further above 2 keV, which is 80% higher than the value of T
i clamping in ECR-heated plasmas. This finding proposes a possible solution to the problem of T
i clamping on EAST and demonstrates an advanced operational regime with the formation of a strong and broad ITB for future fusion plasmas dominated by electron heating.
Solon and the Demos in his Poetry
Authors: Edwards Anthony T
Published: December 2023

I aim in this study to extract from the fragments of Solon’s poetry evidence for what the Athenian demos expected from Solon’s archonship. I assume that where Solon discusses the demos, he necessarily alludes to demotic demands. Solon’s testimony shows the demos to have been concerned primarily with three issues: the enslavement of Athenians, redistribution of land, and establishment of a tyranny. I conclude that the demos expected, vainly, Solon to end the enslavement of their numbers, to redistribute land, and to achieve these goals by establishing himself as a tyrant if necessary.
Outcomes following cardiac resynchronisation therapy in older people
Authors: Safdar Nawaz Z , Kamalathasan Stephe , Gupta Ankit , Wren Joshua , Bird Rory , Papp Dorothy , Latto Rebecca , Ahmed Ali , Palin Victoria , Gierula John , Witte Klaus K , Straw Sam
Published: December 2023

Introduction

Older patients may be less likely to receive cardiac resynchronisation therapy (CRT) for the management of heart failure. We aimed to describe the differences in clinical response, complications, and subsequent outcomes following CRT implantation compared to younger patients.

Methods

We conducted a retrospective cohort study of unselected, consecutive patients implanted with CRT devices between March 2008 and July 2017. We recorded complications, symptomatic and echocardiographic response, hospitalisation for heart failure, and all-cause mortality comparing patients aged <70, 70–79 and ≥ 80 years.

Results

Five hundred and seventy-four patients (median age 76 years [interquartile range 68–81], 73.3% male) received CRT. At baseline, patients aged ≥80 years had worse symptoms, were more likely to have co-morbidities, and less likely to be receiving comprehensive medical therapy, although left ventricular function was similar. Older patients were less likely to receive CRT-defibrillators compared to CRT-pacemakers. Complications were infrequent and not more common in older patients. Age was not a predictor of symptomatic or echocardiographic response to CRT (67.2%, 71.2% and 62.6% responders in patients aged <70, 70–79 and ≥ 80 years, respectively; P = 0.43), and time to first heart failure hospitalisation was similar across age groups (P = 0.28). Ten-year survival was lower for older patients (49.9%, 23.9% and 6.8% in patients aged <70, 70–79 and ≥ 80 years, respectively; P < 0.001).

Conclusions

The benefits of CRT on symptoms and left ventricular function were not different in older patients despite a greater burden of co-morbidities and less optimal medical therapy. These findings support the use of CRT in an ageing population.
Re-analysis and meta-analysis of summary statistics from gene–environment interaction studies
Authors: Pham Duy T , Westerman Kenneth E , Pan Cong , Chen Ling , Srinivasan Shylaja , Isganaitis Elvira , Vajravelu Mary Ellen , Bacha Fida , Chernausek Steve , Gubitosi-Klug Rose , Divers Jasmin , Pihoker Catherine , Marcovina Santica M , Manning Alisa K , Chen Han
Published: December 2023

Motivation

Summary statistics from genome-wide association studies enable many valuable downstream analyses that are more efficient than individual-level data analysis while also reducing privacy concerns. As growing sample sizes enable better-powered analysis of gene–environment interactions, there is a need for gene–environment interaction-specific methods that manipulate and use summary statistics.

Results

We introduce two tools to facilitate such analysis, with a focus on statistical models containing multiple gene–exposure and/or gene–covariate interaction terms. REGEM (RE-analysis of GEM summary statistics) uses summary statistics from a single, multi-exposure genome-wide interaction study to derive analogous sets of summary statistics with arbitrary sets of exposures and interaction covariate adjustments. METAGEM (META-analysis of GEM summary statistics) extends current fixed-effects meta-analysis models to incorporate multiple exposures from multiple studies. We demonstrate the value and efficiency of these tools by exploring alternative methods of accounting for ancestry-related population stratification in genome-wide interaction study in the UK Biobank as well as by conducting a multi-exposure genome-wide interaction study meta-analysis in cohorts from the diabetes-focused ProDiGY consortium. These programs help to maximize the value of summary statistics from diverse and complex gene–environment interaction studies.

Availability and implementation

REGEM and METAGEM are open-source projects freely available at https://github.com/large-scale-gxe-methods/REGEM and https://github.com/large-scale-gxe-methods/METAGEM.
TsImpute: an accurate two-step imputation method for single-cell RNA-seq data
Authors: Zheng Weihua , Min Wenwen , Wang Shunfang
Published: December 2023

Motivation

Single-cell RNA sequencing (scRNA-seq) technology has enabled discovering gene expression patterns at single cell resolution. However, due to technical limitations, there are usually excessive zeros, called “dropouts,” in scRNA-seq data, which may mislead the downstream analysis. Therefore, it is crucial to impute these dropouts to recover the biological information.

Results

We propose a two-step imputation method called tsImpute to impute scRNA-seq data. At the first step, tsImpute adopts zero-inflated negative binomial distribution to discriminate dropouts from true zeros and performs initial imputation by calculating the expected expression level. At the second step, it conducts clustering with this modified expression matrix, based on which the final distance weighted imputation is performed. Numerical results based on both simulated and real data show that tsImpute achieves favorable performance in terms of gene expression recovery, cell clustering, and differential expression analysis.

Availability and implementation

The R package of tsImpute is available at https://github.com/ZhengWeihuaYNU/tsImpute.
Adenosylhomocysteinase plays multiple roles in maintaining the identity and pluripotency of mouse embryonic stem cells
Authors: Jiang Qi , Lan Shubing , Tan Fancheng , Liang Yiping , Guo Zhencheng , Hou Yanlin , Zhang Hui , Wu Guangming , Liu Zhonghua
Published: December 2023

Adenosylhomocysteinase (AHCY), a key enzyme in the methionine cycle, is essential for the development of embryos and the maintenance of mouse embryonic stem cells (mESCs). However, the precise underlying mechanism of Ahcy in regulating pluripotency remains unclear. As the only enzyme that can hydrolyze S-adenosylhomocysteine in mammals, AHCY plays a critical role in the metabolic homeostasis, epigenetic remodeling, and transcriptional regulation. Here, we identified Ahcy as a direct target of OCT4 and unveiled that AHCY regulates the self-renewal and differentiation potency of mESCs through multiple mechanisms. Our study demonstrated that AHCY is required for the metabolic homeostasis of mESCs. We revealed the dual role of Ahcy in both transcriptional activation and inhibition, which is accomplished via the maintenance of H3K4me3 and H3K27me3, respectively. We found that Ahcy is required for H3K4me3-dependent transcriptional activation in mESCs. We also demonstrated that AHCY interacts with polycomb repressive complex 2 (PRC2), thereby maintaining the pluripotency of mESCs by sustaining the H3K27me3-regulated transcriptional repression of related genes. These results reveal a previously unrecognized OCT4–AHCY–PRC2 axis in the regulation of mESCs’ pluripotency and provide insights into the interplay between transcriptional factors, cellular metabolism, chromatin dynamics and pluripotency regulation.
Phylogenetic association analysis with conditional rank correlation
Authors: Wang Shulei , Yuan Bo , Tony Cai T , Li Hongzhe
Published: December 2023

Phylogenetic association analysis plays a crucial role in investigating the correlation between microbial compositions and specific outcomes of interest in microbiome studies. However, existing methods for testing such associations have limitations related to the assumption of a linear association in high-dimensional settings and the handling of confounding effects. Hence, there is a need for methods capable of characterizing complex associations, including nonmonotonic relationships. This article introduces a novel phylogenetic association analysis framework and associated tests to address these challenges by employing conditional rank correlation as a measure of association. The proposed tests account for confounders in a fully nonparametric manner, ensuring robustness against outliers and the ability to detect diverse dependencies. The proposed framework aggregates conditional rank correlations for subtrees using weighted sum and maximum approaches to capture both dense and sparse signals. The significance level of the test statistics is determined by calibration through a nearest-neighbour bootstrapping method, which is straightforward to implement and can accommodate additional datasets when these are available. The practical advantages of the proposed framework are demonstrated through numerical experiments using both simulated and real microbiome datasets.
IBC-Oxford University2023_BJSOral_3Tailored Bilio-Pancreatic Limb Length and Haemoglobin A1c Levels 10 years following Mini-Gastric Bypass Original Technique of One Anastomosis Gastric Bypass
Authors: Rutledge R , Kular K S , Manchanda N , Illan J
Published: December 2023

Introduction

The need for or the ideal length of the Biliopancreatic Bypass limb (BPL) length is a controversial topic. The Mini Gastric Bypass original technique (MGB-OT) version of the One Anastomosis Gastric Bypass (OAGB) includes a “Tailored” BPL length. This study aimed to investigate the 1 to 10-year outcomes of the “Tailored’ BPL length in patients undergoing MGB-OT in diabetic patients with Class III obesity.

Methods

The study is a retrospective chart review of 114 patients who underwent the Mini Gastric Bypass original technique (MGB-OT) with a tailored Biliopancreatic Limb length as described by Rutledge et al. These cases were performed between June 2008 and December 2009. The study investigated the relationship between the length of the BPLL and glycaemic control, primarily as measured by the change in (Delta) HbA1c levels, in morbidly obese diabetic patients undergoing the MGB-OT. The mean BPL length in the study was 185 cms, with a range of 120-350 cms. The study analysed preoperative, post-operative, and Delta HbA1c levels as the primary outcomes. The critical outcome goal for the study was HbA1c levels of less than 7%, which is a commonly used target for glycaemic control in diabetic patients.

Results

Only 89 of 114 (78%) patients completed the 10-year follow-up. The mean preoperative HbA1c was 9.2+/-1.6 (range 6.8-14.7). Longer BPL length were selected for patients based on a variety of patient factors including the patient’s preoperative HbA1c levels. Patients with longer BPL length had greater weight loss (R2 0.8.) The mean HbA1c levels were 5.50+/-0.36, 5.65+/-0.35, and 5.82+/-0.41 at 1, 5, and 10 years post-op. 100% of patients evaluated at 1 and 5 years had HbA1c levels below 7%, and only 1 out of 89 patients at 10 years had HbA1c levels above 7%. The correlation between BPL length and the 10-year Delta HbA1c was high, with a correlation coefficient (r) of 0.8. The Delta HbA1c was significantly greater in the patients with BPL length > 150 cm (3.99 +/- 1.87 vs 2.08 +/- 0.71 in the BP150 patients difference 1.91, SEM 0.40, 95% CI 1.12 to 2.69, P < 0.0001) i.e., longer BPL length (> 150cms) had significantly greater Delta HbA1c than 150 cm BPL length.

Conclusions

The study suggests that individualized tailoring of the biliopancreatic limb length in the OAGB procedure can potentially lead to a combination of excellent weight loss and near-complete normalization of HbA1c levels for up to 10 years. However, this a small and incomplete study and the optimal length may vary based on individual patient factors. Further research is needed to confirm these findings and establish standardized guidelines for determining the appropriate BPL length. Overall, the study highlights the importance and potential value of continued research and individualized treatment approaches for patients with obesity and diabetes.
IBC-Oxford University2023_BJSOral_5Comparative Effectiveness of Bupivacaine-Dexamethasone and Liposomal Bupivacaine for Autonomic Neural Blockade in Laparoscopic Sleeve Gastrectomy: A Study on Pain, Postoperative Nausea and Vomiting and Analgesic Consumption
Authors: Daes J , Rocha J , Luque E , Hanssen A
Published: December 2023

Background

Pain is increasingly recognised as a syndrome not merely a symptom, emphasizing the importance of pain management. Visceral pain impacts up to 75% of bariatric patients during recovery. Concurrently, postoperative nausea and vomiting (PONV) persist as challenges after laparoscopic sleeve gastrectomy (LSG). An earlier RCT demonstrated the safety and effectiveness of para-gastric autonomic neural blockade (ANB) as a novel strategy to manage these issues in the first 24 hours after a laparoscopic sleeve gastrectomy. A limitation of using bupivacaine for ANB is its half-life, with clinical effects limited to 14 to 18 hours. This study compares the effectiveness of ANB using a combination of bupivacaine and Dexamethasone with that of liposomal bupivacaine.

Methods

This research represents a secondary analysis of an earlier RCT titled "Impact on Anaesthetic Agents Consumption Following Autonomic Neural Blockade as Part of a Combined Anaesthesia Protocol," currently under review. This secondary analysis focuses on two patient groups; one where ANB was performed with a mix of 5% bupivacaine and Dexamethasone (47 patients), and another with liposomal bupivacaine (25 patients). Data on pain, PONV, and analgesic requirements at 1, 8, and 24 hour post-surgery were recorded and analysed.

Results

Both treatment groups demonstrated low levels of pain, PONV incidence, and analgesic usage. No significant differences in pain scores or analgesic use were found between the groups at the selected postoperative time points. However, the liposomal bupivacaine group exhibited a reduced incidence of PONV, statistically significant only for vomiting.

Discussion

Visceral pain and PONV significantly affects patients' quality of life, recovery time, nursing time allocation, the risk of opioid abuse and readmission rates. Various strategies have been explored to manage visceral pain and associated symptoms. ANB has proven safe and effective in reducing pain, PONV, and analgesic consumption post-LSG. This study confirms that application of either 5 % bupivacaine plus Dexamethasone or liposomal bupivacaine during ANB results in very low levels of pain, PONV incidence, and analgesic use, outperforming the results of the original RCT using only 5% bupivacaine. These results may be attributed to the local anaesthetic used or the improved proficiency in performing the ANB. The similar low pain level and analgesic needs in both groups may render any statistical difference undetected due to the sample size. However, liposomal bupivacaine demonstrated a clinical advantage in reducing PONV after LSG.

Conclusion

ANB utilizing 5% bupivacaine plus Dexamethasone or liposomal bupivacaine effectively mitigates pain, PONV, and analgesic use following LSG. Liposomal bupivacaine appears more effective in managing nausea and vomiting.
IBC-Oxford University2023_BJSOral_6Five years Follow up after Surgical Treatment of Type 2 Diabetes with Laparoscopic Sleeve Gastrectomy associated with a Duodenal Ileal Interposition
Authors: Tinoco A , Netto M , Benedito H , El-Kadre L
Published: December 2023

Introduction

Type 2 diabetes mellitus (T2D) is a chronic disease, primarily caused by a combination of defective insulin secretion and the inability of insulin-sensitive tissues to respond to insulin. Laparoscopic sleeve gastrectomy associated with duodenal ileal interposition (SGDII) has been shown to be a feasible treatment option for patients with T2D, as it provides improvement and control of glycaemia, dyslipidaemia and arterial hypertension. The aim of this study was to evaluate the mid and long-term results of SGDII for the treatment of diabetic patients, considering diabetic remission, weight loss and postoperative complications.

Materials and Methods

Retrospective study with 96 patients with T2D submitted to SGDII, between 2010 and 2016. The glycated haemoglobin (HbA1c) value < 6.5%, without the use of hypoglycaemic agents, was considered as remission of T2D.

Results

The five years follow up demonstrated that 80% of patients had T2D remission at one year, 74.5% at three years and 61.8% at five years. The average duration of the disease was nine years and the mean glycated haemoglobin before surgery was 8.95%. Sixty-one patients (62.8%) were male, and 36 patients (37.2%) were female. The average age was 50.9 years. Median BMI was 33.43 kg/m2. The incidence of major postoperative complications in the first 30 days was 2.1%, with no mortality. Dyslipidaemia control was sustained, after five years, in 62% of the patients.

Conclusion

SGDII resulted in good glycaemic control at 5-years follow-up and represents a valid alternative for the treatment of T2D.
IBC-Oxford University2023_BJSOral_9Calcitonin as a satiety inducer; normalizes in one year after LSG in morbidly obese patients.
Authors: Alasfar F S , Al Ozaiti E , Shinde G J , Arefanian H
Published: December 2023

Laparoscopic Sleeve Gastrectomy (LSG) is the commonest bariatric procedure done worldwide for morbid obesity. LSG benefits extend beyond it being just a restrictive procedure. Hormonal effects after LSG are well documented in literature. Calcitonin has been ascribed to induction of satiety in mammals. We studied calcium homeostasis in patients(N=21) suffering with morbid obesity who underwent LSG and compared them with non-obese candidates (N=15) who were age and sex matched. Blood samples were collected from patients on day before LSG (day-0), day-180, and day-360 after LSG. Blood sample was collected from non-obese group for comparison. We found that there was no significant difference of calcium in the patients compared to non-obese candidates. We observed that mean serum vitamin D increased on day-180 (M=55.33nM, SD=34.72, p=0.059) and day-360 (M=58.24nM, SD=36.19, p=0.038) from values on day-0 (M=29.48nM, SD=21.03, p=0.423) compared to non-obese candidates (M=35.4nM, SD=22.36). Decrease in mean parathyroid hormone (PTH) on day-180 (M=4.19pM, SD=1.8, p=0.83) and on day-360 (M=4.9pM, SD=2, p=0.31) from day-0 (M=6.19pM, SD=3.53, p=0.06) was observed, compared to non-obese candidates (M=4.31pM, SD=1.2). However, normalization of mean calcitonin was noted on day-180 (M=0.4pM, SD=0.8, p=0.22) and day-360 (M=0.8pM, SD=1.1, p=0.74) from day-0 (M=0.34pM, SD=0.4, p=0.02) compared to non-obese candidates (M=0.7pM, SD=0.41). Results of this study showed normalization of calcitonin, which may have role in satiety after LSG. Larger study is recommended to ascertain the trend of calcitonin after LSG.
IBC-Oxford University2023_BJSOral_12Conversion of Sleeve Gastrectomy to Roux-en-Y Gastric Bypass: Indications, Management and Results
Authors: Crozet J , Robert M
Published: December 2023

Introduction

Sleeve gastrectomy (SG) represents more than 60% of bariatric procedures worldwide. Conversion of SG to Roux-en-Y gastric bypass (RYGB) for weight loss failure (WLF) or gastro-oesophageal reflux disease (GERD) is increasing. Intrathoracic migration of the sleeve often seems associated.

Aim

The aim of our study was to analyse the relevance of the indications, the prevalence of an associated de novo hiatal hernia, and the outcomes of the conversion of SG to RYGB.

Methods

This is a retrospective study of prospectively collected data including all the patients who underwent a conversion of SG to RYGB from August 2013 to December 2022. 2 groups were compared: patients operated on because of weight loss failure (WLF group) and those operated on for GERD (GERD group).

Results

We analysed in both groups demographic data, the incidence of an associated hiatal hernia, morbidity, weight loss outcomes and resolution of symptoms. 59 patients were included with an average follow-up of 30.5 months: 46 patients in the GERD group (78%) were compared to 13 patients (22%) in the WLF group. Groups were comparable regarding age (47) and gender (women: 74%); BMI at conversion and prevalence of comorbidities were significantly higher in the WLF group (41.8 kg/m² vs 33.3, p=0.0001). In the GERD group: on preoperative gastroscopy, 30% (14/46) had a grade B esophagitis, 48% (22/46) had a significant hiatal hernia which required a posterior crural closure versus 23% (3/13) in the WLF group, not requiring a surgical treatment (p = 0.02). Conversion was very effective on GERD symptoms (93% of improvement), 52% of the patients stopped proton pump inhibitor treatment. In the WLF group, mean percentage total weight loss (% TWL) was 15.3%, significantly greater than in the GERD group (% TWL=4.6%, p = 0.01). The complication rate was 10% at 30 days and 3.4% after 30 days, not significantly different between groups (p = 1 and 1 respectively).

Conclusions

The main indication of conversion of SG to RYGB was because of GERD: in these indications, the incidence of intrathoracic migration of the sleeve is high requiring a surgical treatment with a very good efficacy on resolution of symptoms. Weight loss results were disappointing.
IBC-Oxford University2023_BJSOral_13Efficiency and Safety of Single Anastomosis Sleeve Ileal (SASI) Bypass in the Treatment of Obesity and associated Co-morbidities: A Systematic Review and Meta-analysis
Authors: Rodrigues Oliveira C , Santos-Sousa H , Pinho Costa M , Amorim-Cruz F , Bouça-Machado R , Resende F , Costa-Pinho A , Preto J , Lima-da-Costa E , Carneiro S , Sousa-Pinto B
Published: December 2023

Introduction

The Single Anastomosis Sleeve Ileal (SASI) bypass is a new bariatric surgery corresponding to an adaptation of the Santoro approach, consisting of a sleeve gastrectomy (SG) followed by loop gastro-ileostomy. Therefore, we aimed to systematically assess all the current literature on SASI bypass in terms of safety, weight loss, improvement in associated comorbidities, and complications.

Methods

Following the Preferred Reporting Items for Systematic Reviews and Meta- Analyses (PRISMA) recommendations, we conducted a systematic review and meta- analysis by searching three databases (PubMed, Scopus, and Web of Science). We performed a meta-analysis of risk ratios and mean differences to compare SASI bypass with SG and One-Anastomosis Gastric Bypass (OAGB) for percentage excessive weight loss, improvement/remission in type 2 diabetes mellitus (T2DM), hypertension (HT), dyslipidaemia (DL), obstructive sleep apnoea (OSA) and complications. Heterogeneity was assessed using the I2 statistic.

Results

Eighteen studies were included in the qualitative analysis and four in the quantitative analysis. Compared to SG, the SASI bypass was associated with improved weight loss (MD=11.32; 95% confidence interval (95%CI) [7.89;14.76]; p< 0.0001), and improvement or remission in T2DM (RR=1.35; 95%CI [1.07;1.69]; p=0.011), DL (RR=1.41; 95%CI [1.00;1.99]; p=0.048) and OSA (RR=1.50; 95%CI [1.01;2.22]; p=0.042). No statistically significant differences in any of the assessed outcomes was observed when compared with OAGB.

Conclusion

Although studies with longer follow-up periods are needed, this systematic review and meta-analysis showed that SASI bypass has a significant effect on weight loss and metabolic variables. Variations in outcomes between studies reinforce the need for standardisation.