203 research outputs found
Impact of premature coronary artery disease on adverse event risk following first percutaneous coronary intervention
No full textObjectivesWe assessed differences in risk profile and 3-year outcome between patients undergoing percutaneous coronary intervention (PCI) for premature and non-premature coronary artery disease (CAD).BackgroundThe prevalence of CAD increases with age, yet some individuals develop obstructive CAD at younger age.MethodsAmong participants in four randomized all-comers PCI trials, without previous coronary revascularization or myocardial infarction (MI), we compared patients with premature (men <50 years; women <55 years) and non-premature CAD. Various clinical endpoints were assessed, including multivariate analyses.ResultsOf 6,171 patients, 887(14.4%) suffered from premature CAD. These patients had fewer risk factors than patients with non-premature CAD, but were more often smokers (60.7% vs. 26.4%) and overweight (76.2% vs. 69.8%). In addition, premature CAD patients presented more often with ST-segment elevation MI and underwent less often treatment of multiple vessels, and calcified or bifurcated lesions. Furthermore, premature CAD patients had a lower all-cause mortality risk (adj.HR:0.23, 95%-CI: 0.10–0.52; p < 0.001), but target vessel revascularization (adj.HR:1.63, 95%-CI: 1.18–2.26; p = 0.003) and definite stent thrombosis risks (adj.HR:2.24, 95%-CI: 1.06–4.72; p = 0.034) were higher. MACE rates showed no statistically significant difference (6.6% vs. 9.4%; adj.HR:0.86, 95%-CI: 0.65–1.16; p = 0.33).ConclusionsAbout one out of seven PCI patients was treated for premature CAD. These patients had less complex risk profiles than patients with non-premature CAD; yet, their risk of repeated revascularization and stent thrombosis was higher. As lifetime event risk of patients with premature CAD is known to be particularly high, further efforts should be made to improve modifiable risk factors such as smoking and overweight.Clinical Trial Registration[clinicaltrials.gov], TWENTE [NCT01066650]; DUTCH PEERS [NCT01331707]; BIO-RESORT [NCT01674803]; BIONYX [NCT02508714]
Clinical outcome after bleeding events following coronary stenting in patients with and without comorbid peripheral arterial disease
No full textPatients undergoing percutaneous coronary intervention (PCI) may experience bleeding events. Bleeding risk is increased in patients with comorbid peripheral arterial disease (PADs). To evaluate whether PCI patients with PADs have worse outcome after bleeding, we assessed pooled patient-level data of 5,989 randomized all-comer trial participants and identified those who had a bleeding (BIO-RESORT:NCT01674803, BIONYX:NCT02508714). Major adverse cardiac events (MACE) and mortality were assessed from bleeding until 3 years after PCI. Of all 313 PCI patients with bleeding events, patients with PADs (n = 34, 10.9%) were older and had more complex lesions than those without PADs (n = 279, 89.1%). In patients with PADs, bleeding occurred more often during the first year after PCI (79.4% vs. 57.3%, p = 0.013). The proportion of major bleeding, and the severity and location of bleeding were similar between both groups. Multivariate analysis found no statistically significant between-group difference in MACE (43.1% vs. 34.7%, p = 0.53; adj.HR:0.86, 95%CI 0.45–1.63, p = 0.64) and mortality (33.5% vs. 22.3%, p = 0.12; adj.HR:1.45, 95%CI 0.73–2.91, p = 0.29). Bleeding occurred significantly more often during the first year after PCI in all-comer patients with concomitant PADs than in those without PADs, while we observed no significant between-group difference in bleeding severity and location, and the risk of adverse events after bleeding.</p
The node: Relationship between the street and the built environment
No full textThe fascination started with the idea that a street is a gettering place for everyone. It is an open space where everybody can come and where people can meet and interact with each other. But is the street designed as a place for interaction? Or is it intended to get from one place to the other? Is the street a logistical way of working, to structure the city and the flow of people? Research has been done about the street, what is a street, and how do we experience a street? To create a better understanding of how streets are designed different street typologies around the world are analyzed. The exciting part about the streets is that they are everywhere, they already designed in a certain way during medieval times. Everage cities exist 1/3 out of streets. Can we see the street still as a public space, or is it occupied by the car? Looking at Rotterdam, 75% of the public space exists of streets, and are mainly occupied by vehicles. So what if we can see the street again as a public space, rather than a place for movement. This research focuses on how the connection between houses and the place for social interaction can increase in the street in relation to the built environment. The research question for this paper: How can the street become a public space through the design of a building? The research question will be tested in Rotterdam city center. Rotterdam is after the bombing design in a car-oriented way, which makes the topic very interesting. Besides of urbanization the big cities becomes denser and denser, this also includes Rotterdam. So the city needs to extend to household all those people. What you can see in Rotterdam is that the centre of the city is slowly moving more to the south. The city’s municipality created a high-rise strategy that will make it possible to house 50.000 more people/houses in the future. But through so, the number of buildings in the center is increasing and the amount of public space decreases. Streets are playing a significant role in the design of the of new households, and to keep the city livable. To test the research question through the design of a building, a specific location in Rotterdam’s center is chosen, called the Kop van Zuid. Through analyzing streets around the world and researching the different aspects of the street. Three main ambitions are defined, which will play an essential role in this project: designing a place for social interaction, establishing a human scale in the city center, and creating a connection between the street and the building.Architecture, Urbanism and Building Science
Energy Harvesting from Slender FRP Pedestrian Bridges
No full textThe Rotterdam municipality is constantly busy replacing old footbridges that have reached their lifetime. Lately, this is done using modern materials, such as fibre-reinforced polymers (FRP). FRP is a relatively light-weight material that has a high yield strength, which allows for aesthetically pleasing, very slender designs. Governing for such designs is often the dynamic behaviour of the bridge: its eigenfrequency may very well lie within the `critical range' of common footfall frequencies. If the step frequency of a pedestrian crossing the bridge lies near the eigenfrequency, a high dynamic amplification factor occurs: high vertical acceleration values for the bridge deck will occur, which means discomfort for the pedestrians.In this thesis, a sustainable solution to that problem was sought. Rather than using pile foundations to clamp the bridgeheads (and thereby increase the eigenfrequency out of the critical range), it was investigated whether the kinetic energy can be harvested from the bridge. Ideally, this both dampens the vibrations and provides free, sustainable energy.Several theoretical models were developed to describe the behaviour of an existing footbridge for which data is available. Adaptations to these models were made in the form of either extra dashpots or a tuned mass damper (TMD). In both cases, the dampers are regenerative, i.e. able to harvest energy.It was shown that adding a TMD provides the best energy harvesting performance. From a practical perspective, it has some advantages as well, such as universal applicability. The parameters in the single degree of freedom (SDOF) model were optimized for maximum energy harvesting while still keeping the vertical deck acceleration at reasonable levels. Finite element analysis largely confirmed these design choices, and showed that reducing the vibration levels is certainly possible with only a relatively small TMD. For a single person crossing at near-resonant footfall frequency only leads to a vertical acceleration of about 1.5 m/s. The amount of energy that can be harvested in such a way is small but non-negligible: about 26 Joules worth of energy is estimated to be gained by an `average' person crossing the bridge. This is taking into account system efficiency as well.A literature study concerning real-world energy harvesting systems was performed, and showed the possibility to closely emulate the theoretical behaviour that was assumed for the regenerative dashpots. This can be done using electromagnetic dampers in combination with proper power electronics design.Civil Engineering | Structural Engineerin
The Proof of the Fundamental Group of the Circle in Homotopy Type Theory’s Dependence on the Univalence Axiom
No full textThe incorporation of the univalence axiom into homotopy type theory has facilitated a new way of proving a basic result in algebraic topology: that the fundamental group of the circle is the integers (π1(S1) ≃ Z). This proof is formalised by Licata and Shulman. However, while the authors note that the univalence axiom is essential, it is not clearly stated where and why. A step-by-step analysis of their proof, the purpose of which is to increase the readers’ understanding of the univalence axiom and its implications in homotopy type theory, shows that it relies on the univalence axiom for constructing the circle. When assuming axiom K instead of the univalence axiom, we can no longer construct the circle in the same way, leading to π1(S1) ≃ 1.CSE3000 Research ProjectComputer Science and Engineerin
Machine learning or Statistical discrete response modelling?: Webshop conversion rate maximization at Fatboy.com
No full textAdaptive website content is an increasingly popular method for e-commerce platforms to personalize the content shown to its visitors in an attempt to increase the conversion rates of their platforms. However, in order to select the content relevant for a specific customer, the online platform should be able to rapidly interpret the explicit choices, as well as the implicitly sensed context, in which the choices are made. Creating a so-called context-aware e-commerce platform thus requires not only the understanding of users’ content-preferences, but also of the users’ context influencing this decision-making and the opportunities of the e-commerce platform to actively respond to this, in addition to analysis of customer behaviour that goes beyond traditional A/B testing used by websites and online services to quickly evaluate hypothesis with real users. Statistical choice modelling and machine learning are both methods with the ability of doing such advanced analysis of choice behaviour. By inferring preferences and trade-offs from people’s choices observed in real life, or hypothetically stated choice experiments, choice models can be estimated with which future choices can be predicted. As statistical choice models provide insight into the most important parameters that influence decisionmaking, conversion rates of e-commerce platforms can be maximized by optimizing those parameters. Moreover, it has long been acknowledged in discrete choice literature that the context in which a decision is made affects one’s decision-making. Machine learning on the other hand, takes an algorithmic approach and bases its prediction on patterns found in the data. The characteristic of machine learning to allow for high-order interactions that are not pre-specified, could be beneficial as the context in which decisions are made, is often fuzzy and highdimensional. However, as this is a black box method, the method will not explicitly give insight into the parameters influencing behaviour, but instead, train itself to maximize the outcome. Although a substantial amount of research is conducted on the difference between statistical choice models and machine learning, and A/B testing and machine learning are both widely used methods for the dynamic content selection on e-commerce platforms, and thus for conversion optimization, less research however, has been done on the complementary use of the two methods within the boundaries of a simple context-aware system-experiment. Nowadays, it is often stated that machine learning has an accuracy far beyond statistical methods and that it is the recommended method for future data analytics and prediction, as machine learning enables determination of outcomes in which large number of variables with complex relationships are involved. However, should machine learning always be the recommended method for an e-commerce platform trying to maximize its conversion rate with the use of dynamic content, or is more traditional statistical choice modelling sometimes still a better solution for smaller organizations less experienced in data analytics? The scientific objective of this study was to investigate the applicability of both statistical discrete response modelling and machine learning methods to maximize, separately or complementary, conversion rate on ecommerce platforms. By using the e-commerce platform Fatboy.com as test environment, in which both methods were required to handle the context-aware opportunities of contemporary online platforms, the potential in applicability of both methods could be examined. The objective within the case study Fatboy® was to understand how the conversion rates of e-commerce platforms can be maximized using statistical discrete response modelling, machine learning, or complementary to each other.Complex Systems Engineering and Management (CoSEM
Adaptivity in program management: Identification of success factors for adaptive cooperation in program management
No full textLarge complex infrastructural projects and programs show cost overruns and delays. As these are often funded by governmental bodies, the cost overruns also have an economic impact for society. Where projects are focused on delivering their scope within time and budget, a program is focused on achieving a broader goal. To do so, a program consists of different projects that show interdependencies. This, complemented with many uncertainties and the program's long durations, make programs even more complex than projects. Program management needs to be flexible and able to adjust: adaptivity is a core characteristic of program management. An academic knowledge gap is seen on cooperation strategies that achieve adaptivity in programs. Therefore, this study focused on the identification of success factors for adaptive cooperation in programs. The different research methods have led to the identification of the following factor: mandate and formal structure that together determine the operational framework of teams and organisations. This factor influences the ability to be adaptive by setting rules for the teams. As adaptivity was often associated with social processes, this insight has an academic value and contributes to theory development on adaptivity in program management. In addition to this factor, factors focused on social processes can also influence the adaptivity. Program managers should define the mandate of teams and their formal structure before determining the social acts. This could enable adaptive cooperation in programs and reduce cost overruns and delays. This research provides a starting point for theory development on adaptive program management.Complex Systems Engineering and Management (CoSEM
Elderly patients treated with Onyx versus Orsiro drug-eluting coronary stents in a randomized clinical trial with long-term follow-up
No full textBackground Percutaneous coronary intervention (PCI) with new-generation drug-eluting stents is increasingly performed in elderly patients, who generally have more comorbidities and more technically challenging target lesions. Nevertheless, there is a paucity of reported data on the long-term safety and efficacy of PCI with contemporary stents in elderly all-comers. Methods This prespecified secondary analysis of a large-scale randomized clinical trial (BIONYX; clinicaltrials.gov:NCT02508714) compared in elderly all-comers (>= 75 years) the 5-year outcome after PCI with the novel, more radiopaque Onyx zotarolimus-eluting stent (ZES) versus the Orsiro sirolimus-eluting stent (SES). We assessed the main composite endpoint target vessel failure (TVF: cardiac death, target vessel myocardial infarction, or target vessel revascularization) and several secondary endpoints. Results Of 2,488 trial participants, 475(19.1%) were elderly (79.5 +/- 3.5 years), including 165(34.7%) women. There was a significant between-stent difference in the main endpoint TVF in favor of the Onyx ZES (14.4% vs. 24.2%, HR: 0.60, 95% CI 0.39-0.93, p(log-rank) = 0.02). The time-to-event curves displayed between-stent dissimilarities across all components of TVF, yet not statistically significant. Landmark analysis between 1- and 5-year follow-up showed in Onyx ZES-treated patients significantly lower rates of TVF (7.8% vs.8.9%, p = 0.002) and target vessel revascularization (3.0% vs.8.3%, p = 0.029). In addition, the 5-year rates of all-cause mortality and several composite endpoints were lower (p < 0.03) in Onyx ZES-treated patients. Conclusions In elderly all-comer patients, those treated with Onyx ZES showed a lower 5-year incidence of the main endpoint of safety and efficacy, as well as several secondary endpoints, than patients treated with Orsiro SES. Further research on this issue is warranted. Clinical trial registration information https://clinicaltrials.gov/study/NCT02508714.The present analysis was performed without any external financial support. The main BIONYX trial was equally funded by Biotronik and Medtronic
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