98 research outputs found
Intravascular Ultrasound and Peripheral Endovascular Interventions
No full textIn recent years the interest in minimal invasive surgery has been growing and the same trend
can be observed in vascular surgery, leading to what is commonly referred to as
lIendovascular surgery". Although the 1990s represent an era of technical revolution in
vascular surgery, it is a misunderstanding to consider endovascular treatment a recent
development. In 1947 J050 Cid dos Santos described the thrombo-endarterectomy'; this
technique was modified by Vollmar in 1964, to a semi-closed endarterectomy using ringstrippers'>
In the same year other pioneers, including Dotter and Judkins, published
prelinlinary results on what they called "angioplasty" of the femoropopliteal artery using coaxial
eatheters.3 This technique was later modified by Griintzig in 1974, who replaced the coaxial
catheters with dilatation balloons.' In the early 1990s, Volodos and Parodi introduced
the endovascular treatment of the abdominal aortic aneurysm with a device composed of a
Dacron graft and Palmaz stents.5
,6
The collaboration between interventional radiologists and vascular surgeons has been of
eminent importance for further evolution of endovascular teclmiques. Nowadays a great
variety of obstmctive and aneurysmal peripheral vascular diseases can be treated with
catheter-guided, endovascular and, therefore, less invasive techniques.
The development of these endovascular techniques prompted the need for improved vascular
imaging and better diagnostics. Since angiography displays only a "lumenogram II of the
vessel, tills prechldes qualitative evaluation of atherosclerotic plaque and quantitative
assessment of plaque and vessel. Sophisticated modalities such as colour duplex, computed
tomographic angiography and magnetic resonance imaging can be important in the pre- and
postintervention assessment of vascular disease. These techniques, however, do not always
give accurate information on the dimensions of the vessel or the extent of the disease and at
the present time cannot be used during intervention.7 Intravascular ultrasound depicts both the
vascular lumen and vascular wall: thus, information can be obtained on the atheromatous
plaque constituents and the size of the lumen, vessel wall and arterial disease
J.B.TowneL.H.HollierComplications in Vascular Surgery(2nd Edition)2004Marcel Dekker Inc.New York272pp., $165
No full textUnknow
Insights in the market of recycled plastic, with practical value chain research
No full textThe European Union (EU) landfilled and incinerated 600 million tons of waste in 2013, which could have been recycled and returned as raw material to the economy. Resource efficiency can regain this value and bring economic, environmental and social benefits. The EU has therefore adapted the Circular Economy Package with targets to stimulate the transition to a circular economy. These targets include reusing and recycling 55% of plastic packaging waste by 2025. Member states act to achieve those targets with subsidies and funding schemes. This enables entrepreneurs to enter the market of recycled plastic with innovations to gain Schumpeterian rent. However, only approximately 50% of starting companies are still operating after 4 years. It is crucial to increase the success rate of turning new technologies into innovations in order to reach the recycling targets. Market exploration and orientation strategies can aid entrepreneurs to gain insight in the recycled plastic market. Globalized value chain research is a commonly used method, but not suitable to address the recycling industry as it is not globalized but restricted by country borders and local governance. Value chain research methodology was used, according to a handbook written by Kaplinsky & Morris from 2001, which refers to and uses globalized value chain research methodology. For the recycling industry a specific selection was made from elements mentioned in the handbook. This enabled the execution of value chain research for the not globalized recycling industry. The interview questions and topics were made based on the required data for the selected elements. This thesis focussed on the biggest market segment of post-consumer plastic packaging waste in the Netherlands. In total 149 compounders, recyclers and converters were included in a database for a selection. Of which seven companies participated, which resulted in qualitative data that gives insight into the industry and enabled answering the research question.What is required from the value chain of the plastic recycling industry to increase the use of recycled post-consumer PPW? Converters must be able to get access to regranulate with stable MFI and crystallization time characteristics in higher quantities. Compounders can initiate this with joint design projects with branding companies thereby highlighting the possibilities of their regranulate. The optimization of the product and process for their regranulate lowers the switching costs for the converter and can bring rent opportunities. It furthermore showed to increase the sales of regranulate. The compounder requests higher quantities of mono streams recycled plastic from the recycler to comply with demand for regranulate to be used for high volume consumer goods. Recyclers however, upgrade their processes to maximize output for the Dutch ‘Raamovereenkomst’, which includes a mix stream next to the mono streams. This mix stream cannot be used by the compounders to make regranulate for the converters. The recyclers claim that they can technically increase the mono streams at the expense of the mix stream, although this leads to lower profits for them. A change is therefore required in the Dutch ‘Raamovereenkomst’ to optimize for mono stream output.Management of Technology (MoT
Standardized definitions and clinical endpoints in trials investigating endovascular repair of aortic dissections.
No full textOBJECTIVES
Endovascular therapy is a rapidly expanding option for the treatment of patients with aortic dissection (AD) and various studies have been published. These trials, however, are often difficult to interpret and compare because they do not utilize uniform clinical endpoint definitions.
METHODS
The DEFINE Group is a collaborative effort of an ad hoc multidisciplinary team from various specialties involved in AD therapy in Europe and the United States. DEFINE's goal was to arrive at a broad based consensus for baseline and endpoint definitions in trials for endovascular therapy of various vascular pathologies. In this project, which started in December 2006, the individual team members reviewed the existing pertinent literature. Following this, a series of telephone conferences and face-to-face meetings were held to agree upon definitions. Input was also obtained from regulatory (United States Food and Drug Administration) and industry (device manufacturers with an interest in peripheral endovascular revascularization) stakeholders, respectively.
RESULTS
These efforts resulted in the present document containing proposed baseline and endpoint definitions for clinical and morphological outcomes. Although the consensus has inevitably included certain arbitrary consensus choices and compromises, adherence to these proposed standard definitions would provide consistency across future trials, thereby facilitating evaluation of clinical effectiveness and safety of various endovascular revascularization techniques.
CONCLUSIONS
This current document is based on a broad based consensus involving relevant stakeholders from the medical community, industry and regulatory bodies. It is proposed that the consensus document may have value for study design of future clinical trials in endovascular AD therapy as well as for regulatory purposes
The functional flexibility of lock design: Applied on the Meuse route
No full textIn general, an inland navigation lock has a structural lifespan of about 100 years, while in most cases this lock is not big enough anymore after 25 - 50 years. This is caused by the growing ship dimensions and/or intensities. A functional flexible lock is the solution for extending the functional lifespan. This type of lock is, with or without a few structural adjustments, capable of serving the shipping traffic for its whole structural lifespan. This design approach will be applied on the lock complex ‘Sluis Sambeek’, which is located in the Meuse route. The first part of the study is carried out on the basis of the Life Cycle Management (LCM) approach. The LCM is started with a trend forecast, from which follows that the future ship sizes are normative for the required lock dimensions. After that, three alternatives are elaborated: 1. Zero-alternative: renovation of the lock. 2. Functional flexible lock: standard lock that is built large enough at once. 3. Structural flexible lock: a relatively easy extendable navigation lock. The maximum dimensions are reached stepwise. Alternative 2 appears to be the least expensive option for ‘Sluis Sambeek’. Although alternative 3 is the most expensive option, this alternative is elaborated further, because it is the most innovative option and could be a better solution for another lock reconstruction. The structural flexibility in alternative 3 is formed by the lock chamber which exists of relatively simple replaceable sheet pile walls, and by floatable lock heads that can be replaced by wider lock heads. The construction planning and the structural lock head design are the innovative parts that are elaborated most specifically. It is concluded that it is useful to consider both the possibilities of a functional and a structural flexible lock design for ‘Sluis Sambeek’ or for another lock location.Hydraulic EngineeringCivil Engineering and Geoscience
IJsverslag: Winter 1984-1985
No full textDe winter 1984/85 was in het algemeen streng met een bijzonder koude januarimaand, daarentegen waren de maanden november en december zacht. In deze winter kwamen twee ijsperioden voor van elk ongeveer 4 weken, waarbij in het gehele land veel ijs is opgetreden. Ook in het benedenrivierengebied is vrij veel ijs voorgekomen. In verband met het buiten gebruik stellen van een aantal stuwen ondervond de scheepvaart op de Nederrijn en Lek veel hinder van lage waterstanden. Op de Maas was hierdoor op het gedeelte Lith-Sambeek een aantal dagen de scheepvaart gehinderd.IJsversla
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