87 research outputs found
Safety of pulsed field ablation in more than 17,000 patients with atrial fibrillation in the MANIFEST-17K study
No full textAbstract Pulsed field ablation (PFA) is an emerging technology for the treatment of atrial fibrillation (AF), for which pre-clinical and early-stage clinical data are suggestive of some degree of preferentiality to myocardial tissue ablation without damage to adjacent structures. Here in the MANIFEST-17K study we assessed the safety of PFA by studying the post-approval use of this treatment modality. Of the 116 centers performing post-approval PFA with a pentaspline catheter, data were received from 106 centers (91.4% participation) regarding 17,642 patients undergoing PFA (mean age 64, 34.7% female, 57.8% paroxysmal AF and 35.2% persistent AF). No esophageal complications, pulmonary vein stenosis or persistent phrenic palsy was reported (transient palsy was reported in 0.06% of patients; 11 of 17,642). Major complications, reported for ~1% of patients (173 of 17,642), were pericardial tamponade (0.36%; 63 of 17,642) and vascular events (0.30%; 53 of 17,642). Stroke was rare (0.12%; 22 of 17,642) and death was even rarer (0.03%; 5 of 17,642). Unexpected complications of PFA were coronary arterial spasm in 0.14% of patients (25 of 17,642) and hemolysis-related acute renal failure necessitating hemodialysis in 0.03% of patients (5 of 17,642). Taken together, these data indicate that PFA demonstrates a favorable safety profile by avoiding much of the collateral damage seen with conventional thermal ablation. PFA has the potential to be transformative for the management of patients with AF
Kompas op 2030 : Verduurzamingsrichtingen energievoorziening Westlandse glastuinbouw
No full textVoor de glastuinbouw in de regio Westland worden in drie afzonderlijke scenario’s voor 2030 op energiegebied vergaande veranderingen voorzien. Er is in de scenario’s onderscheid gemaakt tussen een pessimistische, een gematigde en een optimistische ontwikkeling van de glastuinbouw in de regio Westland. De veranderingen zijn in elk scenario het grootst op het vlak van de energievoorzieningen, die zullen minder steunen op aardgas en meer op duurzame bronnen en inkoop van warmte en elektriciteit bij derden. Deze veranderingen komen voort uit mutaties in de energievraag en de sectorstructuur, overheidsbeleid en verduurzamingsinspanningen van de glastuinbouwbedrijven en hun partners. De veranderingen hebben een gunstig effect op de verlaging van de CO2-emissie en de verhoging van het aandeel duurzame energie. Naar voren is gekomen dat energieverduurzaming samenhangt met de modernisering van kassen, dat samenwerking tussen bedrijven, hun partners en overheden essentieel is en dat levering van externe CO2 van groot belang is.---In three separate scenario’s far-reaching changes are foreseen for the energy-supply of the greenhouse horticulture industry situated in the region Westland in 2030. The scenario’s differentiate a pessimistic, a moderate and an optimistic approach towards the development of greenhouse horticulture business in the region Westland. The optimistic scenario brings the most far-reaching changes of the energy supply options. These options will rely less on natural gas and more on sustainable energy and purchase of heat and electricity from third parties. These changes are the result of changes in energy demand, changes in sector structure, governmental policies and sustainability efforts of the greenhouse horticulture industry and their partners. These changes will have an positive effect on CO2-emission reduction and increasing the proportion of sustainable energy. Also came forward that making energy supply more sustainable is linked to modern greenhouses, cooperation between greenhouse businesses, their partners and governments is essential and supply of external CO2 is of major importance
Improving the filling jet schematisation through a lock door by taking into account the presence of a ship
No full textThis study treats the calculation of longitudinal forces on a ship in a lock chamber due to the levelling procedure. The focus will be on the force resulting from the filling jet through the levelling door in the lock, with the main point of interest being the interaction between the ship and the flow resulting from the jet. To understand more about this interaction the following methods are used: the one-dimensional software model Lockfill, computational fluid dynamics (CFD) and scale model tests. The study was initiated in the context of improving the accuracy and applicability of the software Lockfill. Lockfill is based on the conservation laws of mass and momentum, while schematising the flow using a two-dimensional parameterization of the filling jet. A two dimensional situation was created for the scale model, neglecting variations over the width. The scaled situation was tested using a CFD model to prepare for the scale model measurements. This preparation revealed that the jet attaches to the bottom for the chosen geometry. The flow measurements consist of multiple point measurements and particle image velocimetry (PIV) measurements just downstream of the gate. The longitudinal forces on the ship were measured for variations in: keel clearance, downstream position of the ship with respect to the gate and water level difference over the gate. The presence of the ship reduces the deflection of the jet towards the bottom. The reason for the reduced deflection is the interference of the ship’s bow with the upper eddy limiting the fluid motion, resulting in a reduction of pressure and therefore a deflection of the jet in the upward direction. This means that the momentum flux in the jet for the situation without ship decreases faster because it attaches to the bottom closer to the gate. The measured forces were compared to the forces Lockfill would predict for the same situation. Both CFD and PIV predict the forces with a small relative error. Lockfill determines the force on the ship accurately as long as the momentum flux can be determined successfully. Determining the momentum flux comes down to a correct schematisation of the filling jet. Variations in keel clearance and discharge are covered quite well by Lockfill. However an increase in distance from the gate reveals big differences compared to the measurements. This is caused by an overestimation of momentum flux dissipation in the Lockfill jet schematisation. The reason for this is that in reality the jet stays more attached to the bottom, therefore maintaining a higher momentum flux. Taking into account the results from this study, the improvement of Lockfill should start with the schematisation of the filling jet. A start can be made by implementing the tendency of the jet to attach to a boundary.Natte kunstwerken van de toekoms
The performance of Earth System Models in simulating droughts
No full textThis research evaluated the performance of Land Surface Models (LSMs) in simulating droughts, examining Land-Hist offline simulations from the Land, Surface, Snow and Soil Moisture Intercomparison Project (LS3MIP). It is well known that LSMs possess uncertainties and biases due to oversimplifications or the absence of certain physical processes (e.g., groundwater interactions and lateral connectivity). Therefore, the objective of this research was to identify the strengths and weaknesses of various LSMs and how this relates to the performances in simulating soil moisture droughts. To address this objective, eight LSMs were evaluated: CESM2, CMCC-ESM2, E3SM-1-1, EC-Earth3-Veg, HadGEM3-GC31-LL, IPSL-CM6A-LR, MIROC6, and UKESM1-0-LL. Two reference evaporation data sets (DOLCE V3 and an ensemble of FLUXCOM-RS, BESS and PML) and a reference soil moisture data set (SoMo.ml) were utilized for the evaluation. After a global analysis on the LSM evaporation characteristics, six climate diverse study areas were selected for further investigation. A long-term analysis was performed by examining the water balance and implementing the LSMs into the Budyko Framework. Subsequently, soil moisture deficits were calculated for the driest periods in time, and the resulting accumulated deficits were compared with the reference evaporation data. The timing and progression of the deficits were evaluated utilizing the reference soil moisture data. Finally, the sensitivity of the model was evaluated by examining the response of evaporation anomalies to precipitation anomalies and comparing this with the reference evaporation data. The results showed that there was a large spread in output and performance among the LSMs across all parts of the evaluation. The greatest contrasts among the LSMs were found in the dry to wet transition zones within the tropics. In this latitudinal range, the worst performing LSMs overestimated the accumulation of soil moisture deficits and the severity of droughts, while the opposite was found for the extratropical regions. Additionally, the models showed, in general, to be overly sensitive to precipitation anomalies. When ranking the implemented model bases in the LSMs based on their performance during droughts, the findings showed that the Community Land Model (implemented in CMCC-ESM2, E3SM-1-1 and CESM2) was predominantly the best performing, followed by ORCHIDEE (IPSL-CM6A-LR) and HTESSEL (EC-Earth3-Veg). MATSIRO (MIROC6) and JULES (HadGEM3-GC31-LL and UKESM1-0-LL) were the least performing model bases. From a hydrological perspective, the findings of this research could be linked to some known limitations of LSMs. Oversimplified soil and vegetation dynamics could contribute to the LSMs being overly sensitive to precipitation anomalies while the contrasts between the tropical and extratropical regions could be attributed to the representation of the soil moisture-evaporation coupling, which plays a greater role in the tropical study areas. Ultimately, this research could contribute to LS3MIP and the Land Surface Modeling community, as the results highlight the strengths and weaknesses of the LSMs in simulating soil moisture droughts. From there, this research could contribute to improving LSMs, understanding drought mechanisms, and addressing climate change impacts, especially in drought-prone regions.Water Managemen
Assessing the impact of quay-wall renovations on the nautical traffic in Amsterdam: A simulation study
No full textThe canals of Amsterdam represent a draw for tourists and add to the value of real estate along the canals. More than 40 percent of Amsterdam tourists take a trip through the canals, accounting for more than 3 million canal travelers annually. Therefore, the tour boat sector is crucial for tourism in Amsterdam.Many of the quay walls on Amsterdam’s canals have either reached the end of their lifespan or need replacing because of damage caused by overloading and the overuse of heavy supply trucks. Currently, a length of 200 km out of the total length of 300 km of quay walls have reached the end of their 100-year service life, and some walls have even passed that limit. In 2017, five incidents of quay-wall failure occurred. In 2018, three such incidents occurred. Hence, these quay walls are in critical need of replacement. Many are located along busy canals, which means that closing these canals will almost certainly directly lead to the congestion of traffic flow on the water. This is highly undesirable for the tourist sector. At the moment, there is no research being conducted into how to manage quay-wall renovations without disturbing transport over water.The main goal of this research project was to develop a first version of a model through which the impact of the quay wall renovations on transport over water (e.g., passenger transport and pleasure craft) can be assessed. Thus, the main research question for this project was as follows: "How can the impact on nautical traffic flow and congestion patterns of quay wall upgrade works in the canals of the City of Amsterdam be assessed?” A model was constructed based on the Amsterdam canal traffic analysis. An agent-based modeling framework was selected as a suitable framework, because it could give insight into not only if and when congestion occurs, but also why congestion occurs. The ABM framework is able to represent the distinct sailing speed and route selection of each vessel type, can reproduce the (routing) behavior of the three vessel types that interact, and had the additional option to incorporate the irrational behavior. Each vessel was modeled as an entity with its own logic (step-by-step instructions) and making its own decisions while moving on a graph. In order to reproduce observed traffic flow and congestion patterns, modeled vessel objects needed to move through this network, calculate their routes based on the network structure and properties, and queue at crossings. Therefore, this study applied network logic (graph theory) and queueing theory. This project used the open-source NetworkX package in Python to construct a network (graph) based on the spatial coordinates of the Amsterdam canal network, with nodes at crossings and bridges and edges connecting the nodes. Each vessel object in the model used algorithms from the NetworkX package to calculate its route on the network. The model also used the SimPy package to simulate queueing and crossing congestion at crossings with discrete time steps. To summarize, the model simulated on a microscopic level, used discrete time steps, and applied the agent-based modeling framework. As this model is developed within a community setting at the TU Delft, this model, and other transport network analysis models, can be viewed and found at https://github.com/TUDelft- CITG/Transport- Network- AnalysisCivil Engineering | Hydraulic Engineerin
Constructing a Confidential, Authenticated, Forward Secure and Offline Logging Scheme
No full textIn IT systems, a logfile provides administrators with an audit trail which can be used to review a system’s activities and a way to discover and diagnose problems which have occurred within that system. When an attacker penetrates an IT system, commonly one of their first actions is tampering with the logs, so that they can hide their malicious activities. For most types of systems a suitable secure logging solution exists. These solutions prevent an adversary from tampering with the system logs, or make it infeasible to do so undetectably. However, the solutions that exist for devices with limited computing power, “resource-constrained” devices, are all unsuited for long-term unsupervised deployment. In this scenario a device is deployed in a hostile environment for prolonged periods of time, during which it cannot communicate or otherwise interact with another party. Existing solutions for this scenario are either, not secure against all known attacks on secure logging schemes, make assumptions that are not realistic given the aforementioned scenario, or fail to account for real-world constraints that these devices and scenario impose on the capabilities of a secure logging scheme.In this thesis we present two secure logging schemes called Immutable Forward Linked and Sealed Logging (IFLS) and Pseudorandom Indexed Forward Linked Logging (PIFL). Both schemes allow for tamper-resistant logging on low-powered devices while at the same time requiring only initial interaction with an external party. Furthermore we present a novel and efficient way of establishing an immutable link between consecutive log entries, which grants protection against most attacks on secure logging schemes. We additionally detail two methods to shield the last log entry, so that Truncation Attacks and Crash Attacks are mitigated. The combination of these techniques in IFLS and PIFL results in two schemes which are fully tamper-resistant. We find that PIFL’s pseudorandom indexing of log entries makes this scheme well-suited for use on flash storage, a storage medium that is ubiquitous in resource-constrained devices. Lastly, we confirm the real-world feasibility of our work by implementing and practically evaluating IFLS in the Rust programming language.Computer Scienc
UNDOCUMENTED: From Liminal Politics to Intimate Spaces
No full textThe protagonist of this work is the rightless, displaced person - a population of individuals in transition, hidden like a shadow in the contemporary city. Departing from the active oppression of this considerable group from the fabric of the city and the ways in which architecture contributes to enclosing or dividing populations, this work proposes a reconsideration of the role of the architect in civil society. After all, what is the current role of the architect when we talk about the socio-political tensions in the context of a marginalised existence in the contemporary city? The work proposes critical, nonmodernist and empathetic ways of thinking about the communication between the individuals at stake and their spaces of transition. The design suggests how a situated, highly visible and appropriable building in the city of Amsterdam could contribute to give meaning to the ongoing debate on Dutch immigration policy and the position of a marginalised population in society.Architecture, Urbanism and Building Sciences | Explorela
UN City Hub Beirut: A metro station in the city centre of Beirut
No full textArchitecture, Urbanism and Building Sciences | Complex Project
World Values Survey - eerste drie golven en longitudinaal bestand
No full textHet World Values Survey is een wereldomspannend onderzoek naar socioculturele en politieke verandering. Voor dit onderzoek worden ongeveer elke vijf jaar in een groot aantal landen gegevens verzameld voor crossnationale vergelijkingen voor inzicht in veranderingen in de loop der tijd. Het onderzoek komt voort uit onderzoek van de European Values Systems Study Group uit 1981. Onderwerpen zijn onder meer: werk, zin van het leven, gezinsleven en hedendaagse sociale kwesties.
Golven: 1: 1981-1984, 2: 1990-1993, 3: 1995-1998, 4: 1999-2001, 5: 2005-2008, 6: 2010-2014
Meer informatie op de webite van het World Values Survey: http://www.worldvaluessurvey.org/Suggestions for data usage: Deze dataset behoort tot het interne archief van het SCP en is niet beschikbaar voor externen. Zie 'Relation' voor eventuele beschikbaarheid van public use files. Bij vragen kunt u contact opnemen met het scp via [email protected]
Design & Innovation: The implications of embedding design within innovation processes
No full textCompanies and organisations are increasingly exposed to a market environment full of turbulence and disruption. Perry (2017), for instance, shows that only 60 companies were present in the Fortune 500 in 1955 as well as in 2017, meaning that 88% of the companies from 1955 went bankrupt, merged with (or were overtaken by) other firms or were not able to meet the Fortune 500 revenue threshold anymore. It can be stated that many companies have not been able to adapt or to take advantage of changing market situations as they fail to scout and invest in new areas of growth or keep applying existing business models to new market segments (Anthony et al.,2016; Zook, 2014)Lately, design has received increased attention from companies that want to anticipate on market turbulence. Design is seen as a way to overcome creative destruction, helping companies to maintain their competitiveness in the marketplace. From multiple accounts, design and design thinking are seen to add value to businesses, organisations, (innovation) processes, products and services. However, the fact that the added value of design and design thinking is mainly described by anecdotal cases of businesses and organisations that successfully make use of design and design thinking seems to ignore the process that precedes the situation whereby design is fully operationalised in and adds value to innovation processes.It is therefore that this research project is executed with the aim of exploring the implications of design when being embedded in a company’s innovation process. Based on current collaborations between the Delft University of Technology’s IDE faculty and various businesses, three companies have been found suitable for examination in the context of this research project. As a result, three cases can be described through conducting empirical research, whereby further insights into these cases are provided through conducting two rounds of interviews. The data derived during this research project show that a design project is seen to be initiated by a non-design project brief, that design is positioned in the Fuzzy Front End of innovation processes and that design is employed in a separated type of department. It also becomes clear that an emerging disconnection emerges between the design output and the innovation process that is already put in place. It is found that this disconnection can be traced back to a barrier that is positioned within the higher ranks of companies as well as a barrier is perceived in the way companies have set-up their organisational structure relative to the design output.It is concluded that design should become an ‘implemented reality’ and it should be incorporated into the ‘thought processes of a company’s organisational structure’ when companies want to successfully make use of design with the aim of arriving at outcomes other than their current innovation processes are producing. Therefore, companies should adapt, revise and/or redesign each aspect of their innovation process that is either preceding or coming after the embedded design element in order to fully facilitate an innovation cycle.Strategic Product Desig
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