172 research outputs found
Subject-specific functional model of hard and soft tissues; skull and spine
No full text© Cranfield University, 2018There is a strong demand for mechanically and morphologically accurate models of the human musculoskeletal system, particularly of the spine. Such models would have multiple applications, including surgical guides, the analysis of implant fitment and design, as well as individual strength evaluation. Current standards such as the ASTM F1717 (devised for the static and dynamic testing of implants) represent complex spine morphologies using simplified blocks of homogeneous material generally constructed from ultra-high-molecular-weight polyethylene (UHMWPE). These do not attempt to replicate morphological characteristics, and therefore do not reproduce mechanical loading properties, especially when considering the complexity of vertebral bodies and their facets. The work described in this thesis investigated the creation of a compressively accurate and validated model of a lumbar motion segment, specifically the validity of technologies such as computed tomography (CT) scanning, computer-aided scan reconstruction, rapid prototyping, digital image correlation (DIC) and finite element analysis (FEA) modelling. In particular, DIC (an optical measurement method) allowed full-field measurements of the displacements and strains. This was used to determine loading paths and magnitudes during the testing procedure. To complement this approach, FEA modelling identified the location and severity of maximum strains for subsequent comparison to the DIC and mechanical testing data. All FEA models were based on CT scan datasets of the modelled cadaveric material, and were validated against the ex vivo mechanical test measurements. The research followed a number of core stages: 1. First, the applicable technologies were tested and verified, with all channels indicating closely related data. This was achieved by the compressive loading of two types of analogue skulls, allowing the validation of DIC as a data acquisition technique in complex structures. Validation against FEA models demonstrated their potential to provide further insight into the experimental results. The initial testing identified a well-defined pathway for a sample manufacturing and preparation process, making it much easier to produce reliable analogues for subsequent experiments. ii 2. In the second stage, analogue motion segments (AMss) were created using the CT scan datasets obtained from the cadaveric porcine specimens. Motion analysis provided a better understanding of the loading paths again by using DIC as an appropriate data acquisition system. Following the creation of the AMS, different materials were considered for the creation of intervertebral discs (IVDs). The mechanically most biofidelic material was selected. 3. Finally, a sensitivity study was carried out to determine a relationship between the scanning resolution and model accuracy for both the mechanical analogue and the FEA model. The use of 3D printing was found to be an effective, efficient and economical strategy for the creation of accurate biomechanical analogues. Furthermore, DIC was a useful tool when looking at individual component strains and displacements. Finally, when considering a motion segment, the majority of the elastic loading – and thus its behaviour on the whole – was governed by the material properties of the IVD simulant. This research demonstrated a clear path towards the creation of a reliable, biofidelic motion segment, or even a partial lumbar spine analogue, that would comply in dynamic and static loading scenarios as well as conformity in compression. The capability of the techniques and the compliance and accuracy of the resulting models was confirmed by developing both analogue mechanical models and FE simulations. Given their potential advantages, it is only a matter of time before mechanical analogues and their corresponding digital models replace the outdated and inaccurate testing standards in our current medical facilities and research centres
Scalar soliton quantization with generic moduli
No full textThis article is distributed under the terms of the Creative Commons
Attribution License (CC-BY 4.0), which permits any use, distribution and reproduction in
any medium, provided the original author(s) and source are credArticle funded by SCOAP3. CP is
a Royal Society Research Fellow and partly supported by the U.S. Department of Energy
under grants DOE-SC0010008, DOE-ARRA-SC0003883 and DOE-DE-SC0007897. ABR
is supported by the Mitchell Family Foundation. We would like to thank the Mitchell
Institute at Texas A&M and the NHETC at Rutgers University respectively for hospitality
during the course of this work. We would also like to acknowledge the Aspen Center
for Physics and NSF grant 1066293 for a stimulating research environment which led to
questions addressed in this paper
Implications of vehicle automation for accessibility and social inclusion of people on low income, people with physical and sensory disabilities, and older people
No full textGreen Open Access added to TU Delft Institutional Repository ‘You share, we take care!’ – Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport and Logistic
Application of an operational audit model in a not for profit hospital Constantinos M. Piperis.
No full textThis thesis has examined the problems facing the not-for-profit sector and concluded that many relate to management deficiencies. One tool available to assist NFP managers is operational auditing. The author developed an operational audit model composed of four stages. The familiarization stage provides an overview of an organization and its operations. In the diagnostic stage, detailed questions are asked in order to identify specific practices and potential problems. In the critical evaluation and application stage, audit procedures are applied to problem areas identified. Finally, in the reporting stage the auditor presents findings and recommendations. This model was tested in an actual nonprofit hospital. Eleven specific problem arm were identified, and recommendations for improvement were offered. This test demonstrated that the audit model could be of significant help to a manager in improving the effectiveness and efficiency of his/her organization.Approved for public release; distribution is unlimited.Lieutenant, Hellenic Navyhttp://archive.org/details/applicationofnop109453973
Constantinos Chatzopoulos as a literary critic
No full textLa critique littéraire représente une part non négligeable de l’œuvre de Constantin Chatzopoulos (Agrinion 1868 - Brindisi 1920). Comparée aux autres genres littéraires, auxquels il a sacrifié (poésie, prose, traduction, essais politiques), elle demeure jusqu’à nos jours le volet le moins connu de son œuvre. La première démarche indispensable afin de proposer une étude de son œuvre critique la plus complète possible, était de réunir l’ensemble de ses articles, parallèlement à ceux qui déjà étaient connus. Tel est l’objectif de la première partie de ce travail qui fait le point de la recherche. La seconde partie, théorique, suit la critique littéraire de Chatzopoulos dans le cadre des deux périodes de son développement : a) l’influence symboliste et nietzschéenne (1898-1902) et b) l’influence sociologique et marxiste (1907-1916). Sont présentés, pour ces deux phases, les revues littéraires qui ont accueilli les textes de l’écrivain. Chatzopoulos représente un chapitre important de l’histoire de la pensée critique grecque, car son œuvre rend compte des courants esthétiques et idéologiques de son époque auxquels elle est intimement liée. Dans la Grèce des débuts du siècle passé, il fut le premier à introduire les principes sociologiques et marxistes dans l’approche d’une œuvre littéraire.Literary criticism represents an interesting part of the Constantinos Chatzopoulos’ (Agrinion 1968 - Prindisi 1920) writing creation. Until our days it remains the least known compared to other literature types, which he served (poetry, prose, translation, political essay). A condition for a fuller study of his work as a critic was the collection of his articles, in addition to those which were already known. Hence this is the aim of all the elements which compose the first research part of our thesis. The second, theoretical part of the thesis monitors the Chatzopoulos’ literary criticism works within the pale of the two phases it occurs: a) the symbolistic - nietzscheic (1898-1902) and sociological - marxist (1907-1916). In both stages the presentation of the literary publications in which works by the author appeared is preceded. Chatzopoulos represents an important asset in the history of the Greek critical thinking, because his work was associated with aesthetic and ideological movements of his time. In Greece of the early past century, he is the first to introduce the sociological and Marxist values into the approach of literary work
Simulated impact response of a 3-D printed skull, with an ellipsoidal excision, using finite element analysis
No full textThis paper investigates methods of determining the influence of an ellipsoidal excision (14.2x11.8 mm occipital region) on the structural integrity of a human skull when exposed to impact loading. Experimental and simulation-based analyses were conducted, using 3-D printed replicas and a finite element model; both were derived from a clinical CT scan of the patient (28 YO MC, with no previous health concerns). Previous simulation studies [1] have achieved managed to predict skull fracture locations effectively for nonexcised skulls
The Paradigm of Crowdsourced Systems
No full textTitle: The Paradigm of Crowdsourced Systems
Abstract:
High acceptance rates of truly personal, portable devices such as smartphones and smart gadgets, along with the successful introduction of DIY computer platforms, like Arduino's and Raspberry Pi's, have lead to an unprecedented abundance of well-connected and well-equipped devices. Crowdsourced Systems is a new system paradigm that seeks to exploit the high availability of such devices and thus change the way data is generated, processed and consumed. In this talk, we will discuss this new paradigm, the challenges and opportunities it poses, review real-world use-cases and present relative on-going standardization efforts.
Short CV:
Dr. Constantinos Marios Angelopoulos is Lecturer in Computing at Bournemouth University (U.K.) specializing in future and emerging paradigms of computer networks and distributed systems. He is also the Lead Editor of the ITU-T Work Item on Crowdsourced Systems; co-author of the ITU-T Technical Report on “Artificial Intelligence in IoT” and the Vocabulary Co-rapporteur for ITU-T SG20. In the past, he has worked for three years as a postdoctoral researcher at University of Geneva (CH) under the prestigious Swiss Government Excellence Scholarship for Foreign Researchers
SMART mobility via prediction, optimization and personalization
No full textIn this chapter, we present a methodological approach for Smart Mobility that integrates three key features: prediction, optimization, and personalization. They are integrated in such a way that when a travel menu is offered, predicted conditions are considered in the attributes of alternatives and optimized system-level policies are maintained. Similarly, user-level estimations and updates are used by prediction and optimization methods at the system-level in order to represent the population with most up-to-date behavioral estimates. Furthermore, a simulation-based evaluation methodology enables to validate the performance of prediction, optimization, and personalization before Smart Mobility is implemented in real-life. Two case studies are presented based on the proposed methodologies together with platforms that facilitate their application. Potential benefits of the proposed methodologies are evaluated which can be classified into user-level and system-level benefits. User-level benefits include consumer surplus, waiting times, etc., and system-level is concerned with congestion, throughput, system-wide travel time, etc. As there is normally a tradeoff between the individual decision-making and system-wide decision-making, Smart Mobility bridges them together with appropriate methodologies on each end. For example, for our Flexible Mobility on Demand case study, we observe 10%–20% reduction in volume-to-capacity ratio as a system-level benefit. Moreover, we see that the tradeoff between consumer surplus and operator profit can be managed with an appropriate objective function.Green Open Access added to TU Delft Institutional Repository 'You share, we take care!' - Taverne project https://www.openaccess.nl/en/you-share-we-take-care Otherwise as indicated in the copyright section: the publisher is the copyright holder of this work and the author uses the Dutch legislation to make this work public.Transport Engineering and Logistic
Software for "Large Scale Crowdsourcing and Characterization of Twitter Abusive Behavior"
No full textThis repository consists of the custom external platform for the annotation process of CrowdFlower, used on the "Large Scale Crowdsourcing and Characterization of Twitter Abusive Behavior" paper, published in ICWSM 2018. Full text of the paper can be found here:
Please cite the paper in any published work that uses any of these resources.
@article{founta2018large,
title={Large Scale Crowdsourcing and Characterization of Twitter Abusive Behavior},
author={Founta, Antigoni-Maria and Djouvas, Constantinos and Chatzakou, Despoina and Leontiadis, Ilias and Blackburn, Jeremy and Stringhini, Gianluca and Vakali, Athena and Sirivianos, Michael and Kourtellis, Nicolas},
journal={arXiv preprint arXiv:1802.00393},
year={2018}
}
For any further questions contact a.m.founta at gmail dot com.</p
Corrigendum to “Intestinal Preconditioning Ameliorates Ischemia-Reperfusion Induced Acute Lung Injury in Rats: An Experimental Study” [Journal of Surgical Research 160(2) (2010) 294–301](S002248040801576X)(10.1016/j.jss.2008.12.017)
No full textThe full name of the third author on the author list should be “Kostas Kostopanagiotou”, as we had incorrectly spelt as “Constantinos Costopanagiotou” in the published manuscripts.1,2 The correct author list for our above manuscript is “Efthimios D. Avgerinos, M.D., Ph.D., Georgia Kostopanagiotou, M.D., Ph.D., Kostas Kostopanagiotou, M.D., Nikolaos Kopanakis, M.D., Ioanna Andreadou, Ph.D., Marilena Lekka, Ph.D., George Nakos, M.D., Ph.D., and Vasilios Smyrniotis, M.D., Ph.D.” The authors would like to apologise for any inconvenience caused. © 2017 Elsevier Inc
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