151 research outputs found
Ultra-fast escape of a deformable jet-propelled body
No full textIn this work a cephalopod-like deformable body that fills an internal cavity with fluid and expels it to propel an escape manoeuvre, while undergoing a drastic external shape change through shrinking, is shown to employ viscous as well as mainly inviscid hydrodynamic mechanisms to power an impressively fast start. First, we show that recovery of added-mass energy enables a shrinking rocket in a dense inviscid flow to achieve greater escape speed than an identical rocket in a vacuum. Next, we extend the shrinking body results of Weymouth & Triantafyllou (J. Fluid Mech., vol. 702, 2012, pp. 470–487) to three-dimensional bodies and show that three hydrodynamic mechanisms must be combined to achieve rapid escape performance in a viscous fluid: added-mass energy recovery; flow separation elimination; and an optimized energy storage and recovery. In particular, we show that the mechanism of separation elimination achieved through rapid body shrinking, coordinated with the mechanism of recovering the initially imparted added-mass energy, is critical to achieving a high escape speed. Hence a flexible, collapsing body can be vastly superior to a rigid-shell jet-propelled body
Erratum: Corrigendum to “Esophageal remnant cancer 35 years after acidic caustic injury: A case report” (International Journal of Surgery Case Reports (2016) 25 (215–217) (S2210261216302358) (10.1016/j.ijscr.2016.06.051))
No full textThe authors regret to change the first name of the second author; more specifically we would like to change the first name “Stamatina” to “Tania”—the family name (“Triantafyllou”) remains as it is. On behalf of all the authors, I assure that we are in agreement with this change. The authors would like to apologise for any inconvenience caused. © 2016 The Author(s
Multidisciplinary treatment of esophageal cancer: The role of active surveillance after neoadjuvant chemoradiation
No full textThe optimal treatment of esophageal cancer is still controversial. Neoadjuvant chemoradiotherapy followed by radical esophagectomy is a standard treatment. Morbidity after esophagectomy however is still considerable and has an impact on patients' quality of life. Given a pathologic complete response rate of approximately 30% in patients after neoadjuvant chemoradiation followed by surgery, active surveillance has been introduced as a new alternative approach. Active surveillance involves regular clinical response evaluations in patients after neoadjuvant therapy to detect residual or recurrent disease. As long as there is no suspicion of disease activity, surgery is withheld. Esophagectomy is reserved for patients presenting with an incomplete response or resectable recurrent disease. Active surveillance after neoadjuvant treatment has been previously applied in other types of malignancy with encouraging results. This paper discusses its role in esophageal cancer
Isovist Fingerprinting as new way of Indoor Localisation
No full textNowadays, humans rely in technology more and more when it comes to navigation and localisation and in many aspects of life as well. While most concepts related to localisation and navigation of outdoors environments are already well derived from various researches and softwares, the indoor environment remains a significantly unexplored area. Nevertheless, lately there have been increased interest on Location Based Services (LBS) and Indoor Positioning Systems (IPS). There are already several methods available for indoor localisation such as Wi-Fi Fingerprinting and Bluetooth Beacons, but none of them is fully functional yet. It remains a field that requires more and further research and investigation in order to reach a satisfactory and complete Indoor Localisation-Navigation method. Therefore, this thesis's main objective is to investigate and explore a new method for Indoor Localisation based on Isovists. The exploration and evaluation of Isovist-Fingerprinting approach for Indoor Localisation can extend the fields of LBS and Geomatics. The main research question is “To what extent can isovist support Indoor Localisation” and through this and a series of sub-questions to analyse the Isovist concept in relation to the Indoor Localisation. This is achieved by forming a proof of concept and a methodology that investigates how the Isovists would benefit an LBS.To succeed that the methodology is divided into 4 main sections. The Data Acquisition for which the newly supported from smartphones Light Detection And Ranging (LiDAR) technology were used. The Space Syntax and Isovist Analysis Measures, where all the concepts related such as the Isovist Parameters were analysed in depth for better understanding of their effect. Then the Matching and Localisation Algorithms, where the possibilities and options on how to reach the localisation were investigated and analysed. And finally, the Tests and Experiments took place in order to evaluate all the prior stages of the methodology.The main conclusion of this research is that a method for Indoor Localisation based on Isovists is feasible and can indeed support an LBS. The analysis and evaluation of all related components has be done and if putting all the parts in the right order they can be of high value for LBS applications. Since is a new method of Indoor Localisation, there is plenty of future work to be done which mainly focuses on how to connect it with existing techniques and integrate all together into a user application.Geomatic
Correction to: Agent‑based models of human response to natural hazards: systematic review of tsunami evacuation (Natural Hazards, (2023), 115, 3, (1887-1908), 10.1007/s11069-022-05643-x)
No full textThe article “Agent-based models of human response to natural hazards: systematic review of tsunami evacuation”, written by Karel Mls · Milan Kořínek · Kamila Štekerová · Petr Tučník ·Vladimír Bureš · Pavel Čech · Martina Husáková · Peter Mikulecký ·Tomáš Nacházel · Daniela Ponce · Marek Zanker · František Babič ·Ioanna Triantafyllou., was originally published Online First without Open Access. After publication in volume 115, issue 3, page 1887–1908 the authors decided to opt for Open Choice and to make the article an Open Access publication. Therefore, the copyright of the article has been changed to © The Author(s) 2023 and the article is forthwith distributed under the terms of the Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit. The original article has been corrected. © 2023, Springer Nature B.V
Indoor localisation through Isovist fingerprinting from point clouds and floor plans
No full textThe objective of this paper is to investigate and propose a method for Indoor Localisation based on Isovists, with the aim of extending the fields of Location-based Services and Geomatics. Various methods and combinations incorporating Isovist concepts, Space Syntax, and visibility graphs are examined and assessed. By investigating these approaches, this study aims to create a comprehensive methodology to achieve localisation using Isovists. The main conclusion drawn from this research is that an Indoor Localisation method based on Isovists is not only feasible but can also effectively support Location-based Services. The analysis and evaluation of all the components have been thoroughly conducted, indicating that when properly integrated, they can provide substantial value for LBS applications. As this is a new method for Indoor Localisation, there is significant scope for future work, particularly in terms of connecting it with existing techniques and integrating them into user applications.Digital Technologie
Current status of esophageal cancer treatment
No full textEsophageal cancer (EC) remains one of the most common and aggressive diseases worldwide. This review discusses some debates in the modern management of the disease. Endoscopic procedures for early cancer (T1a-b) are now embedded in routine care and the challenge will be to more accurately select patients for endoscopic resection with or without adjuvant therapy. Perioperative multimodal therapies are associated with improved survival compared to surgery alone for locally advanced esophageal cancer. However, there is no global consensus on the optimal regimen. Furthermore, histological subtype (adenocarcinoma vs. squamous cell cancer) plays a role in the choice for treatment. New studies are underway to resolve some issues. The extent of the lymphadenectomy during esophagectomy remains controversial especially after neoadjuvant chemoradiation. The ideal operation balances between limiting surgical trauma and optimizing survival. Minimally invasive esophagectomy and enhanced recovery pathways are associated with decreased morbidity and faster recovery albeit there is no consensus yet what approach should be used. Finally, immune checkpoint inhibitors present promising preliminary results in the novel treatment of advanced or metastatic EC but their widespread application in clinical practice is still awaited
Influence of wing kinematics on aerodynamic performance in hovering insect flight
No full textThe influence of different wing kinematic models on the aerodynamic performance of a hovering insect is investigated by means of two-dimensional time-dependent Navier–Stokes simulations. For this, simplified models are compared with averaged representations of the hovering fruit fly wing kinematics. With increasing complexity, a harmonic model, a Robofly model and two more-realistic fruit fly models are considered, all dynamically scaled at Re = 110. To facilitate the comparison, the parameters of the models were selected such that their mean quasi-steady lift coefficients were matched. Details of the vortex dynamics, as well as the resulting lift and drag forces, were studied. The simulation results reveal that the fruit fly wing kinematics result in forces that differ significantly from those resulting from the simplified wing kinematic models. In addition, light is shed on the effect of different characteristic features of the insect wing motion. The angle of attack variation used by fruit flies increases aerodynamic performance, whereas the deviation is probably used for levelling the forces over the cycle.Aerospace Design, Integration and OperationsAerospace Engineerin
Optimal diagnostic strategy for coronavirus disease 2019 detection in liver transplant recipients: Critical review of available evidence
No full textLiver transplant recipients may face an unusually high risk for coronavirus disease 2019 (COVID-19). Observations of heightened risk, rapid progression of severe complications, greater infectivity, and potential for atypical disease presentations in transplant recipients underscore the critical importance of establishing an early diagnosis. Existing diagnostic approaches are marred by unreasonably high false-negative rates. Given the concerns for false-negative results, we performed a narrative review in effort to compile evidence for and against an optimal diagnostic algorithm for detecting COVID-19 in liver transplant recipients. In this algorithm, patients are triaged according to risk of severe acute respiratory syndrome coronavirus 2 infection. Initial testing is performed with reverse transcriptase-polymerase chain reaction, followed by chest computed tomography after 4 days. Repeat tests are performed as per the risk category, patient status, and urgency of transplant. Liver transplant centers should validate the algorithm presented herein, which is based on existing evidence and designed to maximize patient and provider safety, while assuring accuracy in diagnosis
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