Early impact of aortic wrapping on patients undergoing aortic valve replacement with mild to moderate ascending aorta dilatation

<p>Abstract</p> <p>Background</p> <p>The management of mild to moderate dilatation of the ascending aorta of less than 5 cm is controversial, particularly when concomitant surgical correction of aortic valve is required. We investigate the impact of a simple method of aorta reduction using Dacron graft wrapping during aortic valve replacement on the rest of the aorta.</p> <p>Methods</p> <p>We studied 14 patients who had ascending aorta dilatation of 4-5 cm before undergoing aortic wrapping during their aortic valve replacement and compared with their post-operative imaging within a month.</p> <p>Results</p> <p>The diameters of the ascending aorta wrapped with the Dacron graft were significantly reduced within 4 weeks after surgery from 44.7 ± 2.6 to 33.6 ± 3.9 mm (p < 0.001). This was associated with significant reduction in the diameter of rest of ascending aorta: coronary sinuses (from 37.9 ± 4.9 mm to 33.3 ± 6.1 mm; p < 0.001), sinotubular junction (from 33.2 ± 4.7 mm to 30.6 ± 4.4 mm, p = 0.02), and aortic arch (from 34.7 ± 4.3 mm to 32.6 ± 4.1 mm, p = 0.03).</p> <p>Conclusions</p> <p>Reduction of ascending aortic dilatation by wrapping with a Dacron graft in this preliminary study is associated with favourable early reversed aortic remodelling. This supports the hypothesis that correction of mild-moderate dilatation of the ascending aorta with Dacron wrapping at the time of aortic valve surgery may prevent the progression of the dilatation, although the long-term study on a larger population is needed to confirm its benefits.</p

Open-loop intermittent feedback control: Practical continuous-time GPC

A conceptual, and practical difficulty with the continuous-time generalised predictive controller is solved by replacing the continuously moving horizon by an intermittently moving horizon. This allows slow optimisation to occur concurrently with a fast control action. Some nonlinear simulations illustrate the potential of this approach

An approach for developing sensitive design parameter guidelines to reduce the energy requirements of low-rise apartment buildings

High levels of energy consumption in residential buildings and global warming are important issues. Thus the energy performance of buildings should be improved in the early stages of design. This article describes an approach for developing guidelines on sensitive and robust design parameters for the present, the 2020s, the 2050s and the 2080s. Such guidelines can help architects to design low-rise apartment buildings that require less energy for various purposes, such as heating or cooling. The article consists of a general literature review, interviews with architects, the generation of case-specific information and a mock-up presentation and a meeting with professionals. An example guideline that aims to reduce annual cooling energy loads under global warming in low-rise apartment buildings located in hot-humid climates is presented to demonstrate how the proposed approach can be applied. For this guideline, case-specific information was generated, and a global sensitivity analysis based on Monte Carlo Analysis and the Latin Hypercube Sampling technique was performed. The results show that the suggested approach is feasible and could be used to provide helpful information to architects during the design of low-rise apartment buildings with high energy performance. The most sensitive design parameters that affect annual cooling energy loads in low-rise apartment buildings were natural ventilation, window area, and the solar heat-gain coefficient (SHGC) of the glazing. The results are relevant for the present, the 2020s, the 2050s and the 2080s. © 2011 Elsevier Ltd

Expanded geographical distribution of Myxobolus cerebralis: first detections from Alaska

The parasite responsible for salmonid whirling disease, Myxobolus cerebralis, was introduced to the USA in 1958. It has since spread across the country causing severe declines in wild trout populations, but has never been documented from Alaska. However, while assessing the risk of introduction of M cerebralis into the state, we detected the parasite using a species-specific polymerase chain reaction (PCR) assay. Testing of 180 hatchery rainbow trout, Oncorhynchus mykiss (Walbaum), by pepsin trypsin digest (PTD) and quantitative PCR (QPCR) revealed 14 positive samples. Infection was confirmed by sequencing the parasite 18S rRNA gene and by a nested PCR assay based on the same gene. Sequence comparison of M cerebralis from several locations demonstrated the Alaska isolates were genetically distinct and therefore not false-positives arising from contamination during processing. We were unable to visually identify myxospores, indicating that either infection was light or mature spores had not formed. A reference set of fish samples spiked with known numbers of myxospores verified the QPCR and PTD results. This paper presents DNA sequence data from the Alaska M. cerebralis isolates, provides a brief history of the fish and facility of origin, and discusses implications of different testing methods on asymptomatic fish populations