Anatomical Factors Contributing to Troublesome Dysphagia After Antireflux Surgery

Laparoscopic anti-reflux surgery, which involves hiatal repair and fundoplication, is an effective treatment for gastro-oesophageal reflux disease. Hiatal repair refers to closure of the diaphragmatic hiatus with repair of hiatal hernia where present, whereas fundoplication entails wrapping of the fundus of the stomach around the distal oesophagus and securing it within the abdominal cavity. However, some patients develop new-onset or worsening dysphagia post-operatively. The cause of troublesome post-operative dysphagia remains unclear, especially in the setting of an intact fundoplication. In this thesis, I propose that objective measurements of post-fundoplication anatomy hold the key to understanding troublesome dysphagia after fundoplication. My aim is to determine if barium swallow, through objective measurements of post-fundoplication gastro-oesophageal junction anatomy, can be used to identify factors contributing to dysphagia after anti-reflux surgery. A review of anatomical factors previously evaluated or proposed as contributory to dysphagia was performed. Following this, novel objective measurements of select anatomical features on barium swallow studies were devised for the gastro-oesophageal junction in patients after fundoplication. Post-operative structured barium swallow studies with fluoroscopy along with pre- and post-operative dysphagia assessments obtained approximately 6-12 months after fundoplication were utilised. Over two scientific exploratory studies, I first sought to determine the level of inter- and intra-observer reproducibility of these objective measurements, followed by a second study determining if these anatomical features correlated with post-operative dysphagia. In the first study (Chapter 2), there was overall good inter- and high intra-observer reproducibility of objective measurements of gastro-oesophageal junction (GOJ) anatomy after fundoplication. Inter-observer reproducibility, using intra-class coefficient correlations, was good or excellent in 71% of all measurements. High agreement was found for measures of diameter, posterior distal oesophageal angle, displacement of the distal oesophagus anteriorly, and degree of angulation of the GOJ relative to the distal oesophagus, whereas measures of fundal wrap length were more variable. Greater anterior displacement and angulation of the distal oesophagus were subsequently found to be associated with troublesome dysphagia after a complete (360°) wrap of the fundus around the distal oesophagus (Chapter 3), the likely mechanism of which is through increasing oesophageal outflow resistance. After partial anterior (90°) fundoplication, patients with or without troublesome dysphagia had no significant difference in the extent of anterior displacement and angulation of the distal oesophagus. A small reduction in maximal distal oesophageal luminal diameter relative to wrap opening luminal diameter was associated with worsening dysphagia after partial fundoplication. In conclusion, barium swallow studies recorded with fluoroscopy show potential for detecting objective but subtle changes of post-fundoplication anatomy. Anatomical measurements were reproducible, increasing the validity of the measurements for use in further studies. Future studies need to confirm the association between troublesome dysphagia and greater anterior displacement and angulation, to inform a review of technical steps requiring care or modification during fundoplication and hiatal repair to further reduce post-surgical dysphagia.Thesis (MPhil) -- University of Adelaide, Adelaide Medical School, 202

Atomtronic multi-terminal Aharonov-Bohm interferometer

We study a multi-functional device for cold atoms consisting of a three-terminal ring circuit pierced by a synthetic magnetic flux. The flux controls the atomic current through the ring via the Aharonov-Bohm effect. Our device can measure the flux in-situ via a flux-induced transition of the reflections from an Andreev-like negative density to positive density. In the non-equilibrium regime, the flux directs the atomic current into specific output ports, realizing a flexible non-reciprocal switch to connect multiple atomic systems. By changing the flux linearly in time, we convert constant matter wave currents into alternating currents. This effect can be used to realize an atomic frequency generator and study fundamental problems related to the Aharonov-Bohm effect. We demonstrate the viability of the setup by loading a Bose-Einstein condensate into a light-shaped optical potential of the three-terminal ring. Our work opens up novel atomtronic devices for practical applications in quantum technologies.Comment: 11 pages, 9 figure

Size-selective purification of hepatitis B virus-like particle in flow-through chromatography: types of ion exchange adsorbent and grafted polymer architecture

Hepatitis B virus-like particles expressed in Escherichia coli were purified using anion exchange adsorbents grafted with polymer poly(oligo(ethylene glycol) methacrylate) in flow-through chromatography mode. The virus-like particles were selectively excluded, while the relatively smaller sized host cell proteins were absorbed. The exclusion of virus-like particles was governed by the accessibility of binding sites (the size of adsorbents and the charge of grafted dextran chains) as well as the architecture (branch-chain length) of the grafted polymer. The branch-chain length of grafted polymer was altered by changing the type of monomers used. The larger adsorbent (90 μm) had an approximately twofold increase in the flow-through recovery, as compared to the smaller adsorbent (30 μm). Generally, polymer-grafted adsorbents improved the exclusion of the virus-like particles. Overall, the middle branch-chain length polymer grafted on larger adsorbent showed optimal performance at 92% flow-through recovery with a purification factor of 1.53. A comparative study between the adsorbent with dextran grafts and the polymer-grafted adsorbent showed that a better exclusion of virus-like particles was achieved with the absorbent grafted with inert polymer. The grafted polymer was also shown to reduce strong interaction between binding sites and virus-like particles, which preserved the particles' structure

Sizing of battery energy storage system: A multi-objective optimization approach in DIgSILENT powerfactory

In the paradigm of the increasing trend to prevent global warming, renewable energy sources applications integrated with battery energy storage system (BESS) are gaining attention for reducing the usage of fossil fuels in electrical power generation. In this regard, a multi-objective optimization script in DIgSILENT Programming Language (DPL) which links with software modelling and scripting simulation is developed in this study. Formulation for multiple objectives for optimization of BESS sizing with particle swarm optimization (MOPSO) and load flow simulation are applied in the DPL script. The considered objective functions aim to improve the network performance by reducing power loss, voltage deviations and system costs.Pseudo code of BESS optimal sizing with multi-objective algorithm is presented in this research. The BESS with optimal sizing was discovered for improving the network performance in the tested reference network. The optimal BESS size obtained is 2.94 MW with a system cost of MYR 2404.76. The total energy losses can be reduced by approximately 16% from the base case energy losses with the optimal BESS size. The findings of the research reveal that the BESS sizing with MOPSO is applicable in DPL operations alone to solve power system problems

Adaptive structural design of river monitoring systems: Enhancing environmental monitoring capabilities and sustainability

The accelerating degradation of river ecosystems due to pollution necessitates the innovation of River Monitoring Systems (RMS) to protect these critical waterways. This research presents a novel design for adaptive RMS camera structures, aimed at enhancing monitoring capabilities and addressing the limitations of current systems. Highlighting the essential role rivers play in sustaining biodiversity, our study underscores the severe consequences of pollution, as exemplified by the deteriorating condition of Malaysia’s Klang River. We identify the need for a flexible RMS structure to overcome challenges such as excessive weight, corrosion susceptibility, and maintenance difficulties. Our methodology integrates advanced 3D Drawing Software for structural design, Fusion 360 for weight analysis, and a combination of manual calculations and simulations for vibration analysis. The findings reveal that Carbon Fiber Reinforced Polymers (CFRP) are the optimal material choice, offering an excellent balance of performance and cost-efficiency. This research successfully develops a structurally sound, user-friendly, and dynamically stable RMS camera structure, significantly advancing environmental monitoring practices. The study's contributions provide a foundation for future innovations in adaptive structural design, with broad implications for safeguarding river ecosystems worldwide

Impact of opioid-free analgesia on pain severity and patient satisfaction after discharge from surgery: multispecialty, prospective cohort study in 25 countries

Background: Balancing opioid stewardship and the need for adequate analgesia following discharge after surgery is challenging. This study aimed to compare the outcomes for patients discharged with opioid versus opioid-free analgesia after common surgical procedures.Methods: This international, multicentre, prospective cohort study collected data from patients undergoing common acute and elective general surgical, urological, gynaecological, and orthopaedic procedures. The primary outcomes were patient-reported time in severe pain measured on a numerical analogue scale from 0 to 100% and patient-reported satisfaction with pain relief during the first week following discharge. Data were collected by in-hospital chart review and patient telephone interview 1 week after discharge.Results: The study recruited 4273 patients from 144 centres in 25 countries; 1311 patients (30.7%) were prescribed opioid analgesia at discharge. Patients reported being in severe pain for 10 (i.q.r. 1-30)% of the first week after discharge and rated satisfaction with analgesia as 90 (i.q.r. 80-100) of 100. After adjustment for confounders, opioid analgesia on discharge was independently associated with increased pain severity (risk ratio 1.52, 95% c.i. 1.31 to 1.76; P < 0.001) and re-presentation to healthcare providers owing to side-effects of medication (OR 2.38, 95% c.i. 1.36 to 4.17; P = 0.004), but not with satisfaction with analgesia (beta coefficient 0.92, 95% c.i. -1.52 to 3.36; P = 0.468) compared with opioid-free analgesia. Although opioid prescribing varied greatly between high-income and low- and middle-income countries, patient-reported outcomes did not.Conclusion: Opioid analgesia prescription on surgical discharge is associated with a higher risk of re-presentation owing to side-effects of medication and increased patient-reported pain, but not with changes in patient-reported satisfaction. Opioid-free discharge analgesia should be adopted routinely

Neurological manifestations of COVID-19 in adults and children

Different neurological manifestations of coronavirus disease 2019 (COVID-19) in adults and children and their impact have not been well characterized. We aimed to determine the prevalence of neurological manifestations and in-hospital complications among hospitalized COVID-19 patients and ascertain differences between adults and children. We conducted a prospective multicentre observational study using the International Severe Acute Respiratory and emerging Infection Consortium (ISARIC) cohort across 1507 sites worldwide from 30 January 2020 to 25 May 2021. Analyses of neurological manifestations and neurological complications considered unadjusted prevalence estimates for predefined patient subgroups, and adjusted estimates as a function of patient age and time of hospitalization using generalized linear models. Overall, 161 239 patients (158 267 adults; 2972 children) hospitalized with COVID-19 and assessed for neurological manifestations and complications were included. In adults and children, the most frequent neurological manifestations at admission were fatigue (adults: 37.4%; children: 20.4%), altered consciousness (20.9%; 6.8%), myalgia (16.9%; 7.6%), dysgeusia (7.4%; 1.9%), anosmia (6.0%; 2.2%) and seizure (1.1%; 5.2%). In adults, the most frequent in-hospital neurological complications were stroke (1.5%), seizure (1%) and CNS infection (0.2%). Each occurred more frequently in intensive care unit (ICU) than in non-ICU patients. In children, seizure was the only neurological complication to occur more frequently in ICU versus non-ICU (7.1% versus 2.3%, P < 0.001). Stroke prevalence increased with increasing age, while CNS infection and seizure steadily decreased with age. There was a dramatic decrease in stroke over time during the pandemic. Hypertension, chronic neurological disease and the use of extracorporeal membrane oxygenation were associated with increased risk of stroke. Altered consciousness was associated with CNS infection, seizure and stroke. All in-hospital neurological complications were associated with increased odds of death. The likelihood of death rose with increasing age, especially after 25 years of age. In conclusion, adults and children have different neurological manifestations and in-hospital complications associated with COVID-19. Stroke risk increased with increasing age, while CNS infection and seizure risk decreased with age

Hybrid laparoscopic and open repair of post-nephrectomy flank hernia

AbstractSurgical repair of flank hernia is not routinely performed, due to perceived technical difficulties with the surgery and risk of recurrence, or the misconception that flank hernia is solely due to a denervation injury. Due to the rareness of flank hernia in the literature, there is no general consensus on the best method of surgical repair. We present the case of a patient with a symptomatic large flank hernia following open nephrectomy, in which a hybrid technique of open and laparoscopic flank hernia repair with sublay mesh and bone anchor fixation was successfully performed with good outcome. This case highlights the benefits of the hybrid approach, which allowed a laparoscopic assessment of the defect and adhesiolysis, followed by the open repair which enabled adequate mesh overlap, fixation to surrounding tissues and bone anchor fixation.</jats:p

Efficient in-line skyrmion injection method for synthetic antiferromagnetic systems

Although it has been proposed that antiferromagnetically-coupled skyrmions can be driven at extremely high speeds, such skyrmions are near impossible to inject with current methods. In this paper, we propose the use of DMI-induced edge magnetization tilting to perform in-line skyrmion injection in a synthetic antiferromagnetic branched nanostructure. The proposed method circumvents the skyrmion topological protection and lowers the required current density. By allowing additional domain walls (DWs) to form on the branch, the threshold injection current density was further reduced by 59%. The increased efficiency was attributed to inter-DW repulsion and DW compression. The former acts as a multiplier to the effective field experienced by the pinned DW while the latter allows DWs to accumulate enough energy for depinning. The branch geometry also enables skyrmions to be shifted and deleted with the use of only three terminals, thus acting as a highly scalable skyrmion memory block.NRF (Natl Research Foundation, S’pore)Published versio