312 research outputs found
Coupling FEM, Bloch Waves and TMM in Meta Poroelastic Laminates
The propagation of airborne plane waves in the pres-
ence of a meta poroelastic laminate, that is a poroelas-
tic matrix coated with thin elastic layers at its facings
5 and periodically-embedded with inclusions, is studied.
Using the Finite Element Method (FEM) only would
result in a drastic increase of the degrees of freedom
due to the fine mesh required to account for the very
thin coatings. Here, the approach relies on: the Bloch
10 wave expansion of the fields in air; the modal Trans-
fer Matrix Method to account for the coatings; and
the coupling with the FEM model of the poroelas-
tic matrix and the resonant inclusions. The model
is developed for reflection and transmission problems
15 and it can account for coatings with multiple layers.
The procedure induces the addition of the Bloch co-
efficients in the FEMâs linear system at a negligible
additional computational cost. It is applied to the
meta poroelastic laminates with poroelastic inclusions
20 and rubber shell inclusions. The results are compared
with those from the Multiple Scattering Theory and
an excellent agreement between the methods is found.
The approach offers a numerically-efficient way to ac-
count for coatings applied to meta poroelastic layers,
25 and finds applications in industrial prototypes where
coatings are widely used
Amblyopia and quality of life: a systematic review
Background/Aims
Amblyopia is a common condition which can affect up to 5% of the general population. The health-related quality of life (HRQoL) implications of amblyopia and/or its treatment have been explored in the literature.
Methods
A systematic literature search was undertaken (16th-30th January 2007) to identify the HRQoL implications of amblyopia and/or its treatment.
Results
A total of 25 papers were included in the literature review. The HRQoL implications of amblyopia related specifically to amblyopia treatment, rather than the condition itself. These included the impact upon family life; social interactions; difficulties undertaking daily activities; and feelings and behaviour. The identified studies adopted a number of methodologies. The study populations included; children with the condition; parents of children with amblyopia; and adults who had undertaken amblyopia treatment as a child. Some studies developed their own measures of HRQoL, and others determined HRQoL through proxy measures.
Conclusions
The reported findings of the HRQoL implications are of importance when considering the management of cases of amblyopia. Further research is required to assess the immediate and long-term effects of amblyopia and/or its treatment upon HRQoL using a more standardised approach
Natural products in modern life science
With a realistic threat against biodiversity in rain forests and in the sea, a sustainable use of natural products is becoming more and more important. Basic research directed against different organisms in Nature could reveal unexpected insights into fundamental biological mechanisms but also new pharmaceutical or biotechnological possibilities of more immediate use. Many different strategies have been used prospecting the biodiversity of Earth in the search for novel structureâactivity relationships, which has resulted in important discoveries in drug development. However, we believe that the development of multidisciplinary incentives will be necessary for a future successful exploration of Nature. With this aim, one way would be a modernization and renewal of a venerable proven interdisciplinary science, Pharmacognosy, which represents an integrated way of studying biological systems. This has been demonstrated based on an explanatory model where the different parts of the model are explained by our ongoing research. Anti-inflammatory natural products have been discovered based on ethnopharmacological observations, marine sponges in cold water have resulted in substances with ecological impact, combinatory strategy of ecology and chemistry has revealed new insights into the biodiversity of fungi, in depth studies of cyclic peptides (cyclotides) has created new possibilities for engineering of bioactive peptides, development of new strategies using phylogeny and chemography has resulted in new possibilities for navigating chemical and biological space, and using bioinformatic tools for understanding of lateral gene transfer could provide potential drug targets. A multidisciplinary subject like Pharmacognosy, one of several scientific disciplines bridging biology and chemistry with medicine, has a strategic position for studies of complex scientific questions based on observations in Nature. Furthermore, natural product research based on intriguing scientific questions in Nature can be of value to increase the attraction for young students in modern life science
Opti-Owecs: Final Report Vol. 0: Executive Summary
It was the particular mission of the project 'Structural and Economic Optimisation of Bottom-Mounted Offshore Wind Energy Converters' (Opti-OWECS) to extend the state-of-the-art, to determine required methods and to demonstrate practical solutions which will significantly reduce the electricity cost. This will facilitate the exploitation of true offshore sites on a commercial base in a medium time scale of 5 to 10 years from now. In several fields, e.g. support structure design, installation of the offshore wind energy converters, operation and maintenance, dynamics of the entire offshore wind energy converter, structural reliability considerations, etc., the study demonstrated new propositions which will contribute significantly to a mature offshore wind energy technology. This was achieved due to a smooth cooperation of leading industrial engineers and researchers from the wind energy field, offshore technology and power management. Moreover, an innovative design methodology devoted particularly to offshore wind energy conversion systems (OWECS) was developed and successfully demonstrated. The so-called 'integrated OWECS design approach' considers the components of an offshore wind farm as parts of an entire system. Therefore interactions between sub-systems are considered in a complete and practical form as possible so that the design solution is governed by overall criteria such as: levelised production costs, adaptation to the actual site conditions, dynamics of the entire system, installation effort as well as OWECS availability. Furthermore, a novel OWECS cost model was developed which led among other work of the project to the identification of the main cost drivers, i.e. annual mean wind speed, distance from shore, operation and maintenance aspects including wind turbine reliability and availability. A link between these results and a database of the offshore wind energy potential in Europe, developed by the previous Joule project JOUR 0072, facilitated the first estimate of energy cost consistent over entire regions of Northern Europe. The European Commission has supported the project in the scope of the framework of the Non Nuclear Energy Programme JOULE Ill (Research and Technical Development) under grant JOR3-CT95-0087
A Paleolithic diet confers higher insulin sensitivity, lower C-reactive protein and lower blood pressure than a cereal-based diet in domestic pigs
BACKGROUND: A Paleolithic diet has been suggested to be more in concordance with human evolutionary legacy than a cereal based diet. This might explain the lower incidence among hunter-gatherers of diseases of affluence such as type 2 diabetes, obesity and cardiovascular disease. The aim of this study was to experimentally study the long-term effect of a Paleolithic diet on risk factors for these diseases in domestic pigs. We examined glucose tolerance, post-challenge insulin response, plasma C-reactive protein and blood pressure after 15 months on Paleolithic diet in comparison with a cereal based swine feed. METHODS: Upon weaning twenty-four piglets were randomly allocated either to cereal based swine feed (Cereal group) or cereal free Paleolithic diet consisting of vegetables, fruit, meat and a small amount of tubers (Paleolithic group). At 17 months of age an intravenous glucose tolerance test was performed and pancreas specimens were collected for immunohistochemistry. Group comparisons of continuous variables were made by use of the t-test. P < 0.05 was chosen for statistical significance. Simple and multivariate correlations were evaluated by use of linear regression analysis. RESULTS: At the end of the study the Paleolithic group weighed 22% less and had 43% lower subcutaneous fat thickness at mid sternum. No significant difference was seen in fasting glucose between groups. Dynamic insulin sensitivity was significantly higher (p = 0.004) and the insulin response was significantly lower in the Paleolithic group (p = 0.001). The geometric mean of C-reactive protein was 82% lower (p = 0.0007) and intra-arterial diastolic blood pressure was 13% lower in the Paleolithic group (p = 0.007). In evaluations of multivariate correlations, diet emerged as the strongest explanatory variable for the variations in dynamic insulin sensitivity, insulin response, C-reactive protein and diastolic blood pressure when compared to other relevant variables such as weight and subcutaneous fat thickness at mid sternum. There was no obvious immunohistochemical difference in pancreatic islets between the groups, but leukocytes were clearly more frequent in sampled pancreas from the Cereal group. CONCLUSION: This study in domestic pigs suggests that a Paleolithic diet conferred higher insulin sensitivity, lower C-reactive protein and lower blood pressure when compared to a cereal based diet
Evaluation of emergency department performance:A systematic review on recommended performance and quality-in-care measures
BACKGROUND: Evaluation of emergency department (ED) performance remains a difficult task due to the lack of consensus on performance measures that reflects high quality, efficiency, and sustainability. AIM: To describe, map, and critically evaluate which performance measures that the published literature regard as being most relevant in assessing overall ED performance. METHODS: Following the PRISMA guidelines, a systematic literature review of review articles reporting accentuated ED performance measures was conducted in the databases of PubMed, Cochrane Library, and Web of Science. Study eligibility criteria includes: 1) the main purpose was to discuss, analyse, or promote performance measures best reflecting ED performance, 2) the article was a review article, and 3) the article reported macro-level performance measures, thus reflecting an overall departmental performance level. RESULTS: A number of articles addresses this studyâs objective (nâ=â14 of 46 unique hits). Time intervals and patient-related measures were dominant in the identified performance measures in review articles from US, UK, Sweden and Canada. Length of stay (LOS), time between patient arrival to initial clinical assessment, and time between patient arrivals to admission were highlighted by the majority of articles. Concurrently, âpatients left without being seenâ (LWBS), unplanned re-attendance within a maximum of 72 hours, mortality/morbidity, and number of unintended incidents were the most highlighted performance measures that related directly to the patient. Performance measures related to employees were only stated in two of the 14 included articles. CONCLUSIONS: A total of 55 ED performance measures were identified. ED time intervals were the most recommended performance measures followed by patient centeredness and safety performance measures. ED employee related performance measures were rarely mentioned in the investigated literature. The studyâs results allow for advancement towards improved performance measurement and standardised assessment across EDs
AMP-activated protein kinase - not just an energy sensor
Orthologues of AMP-activated protein kinase (AMPK) occur in essentially all eukaryotes as heterotrimeric complexes comprising catalytic α subunits and regulatory ÎČ and Îł subunits. The canonical role of AMPK is as an energy sensor, monitoring levels of the nucleotides AMP, ADP, and ATP that bind competitively to the Îł subunit. Once activated, AMPK acts to restore energy homeostasis by switching on alternate ATP-generating catabolic pathways while switching off ATP-consuming anabolic pathways. However, its ancestral role in unicellular eukaryotes may have been in sensing of glucose rather than energy. In this article, we discuss a few interesting recent developments in the AMPK field. Firstly, we review recent findings on the canonical pathway by which AMPK is regulated by adenine nucleotides. Secondly, AMPK is now known to be activated in mammalian cells by glucose starvation by a mechanism that occurs in the absence of changes in adenine nucleotides, involving the formation of complexes with Axin and LKB1 on the surface of the lysosome. Thirdly, in addition to containing the nucleotide-binding sites on the Îł subunits, AMPK heterotrimers contain a site for binding of allosteric activators termed the allosteric drug and metabolite (ADaM) site. A large number of synthetic activators, some of which show promise as hypoglycaemic agents in pre-clinical studies, have now been shown to bind there. Fourthly, some kinase inhibitors paradoxically activate AMPK, including one (SU6656) that binds in the catalytic site. Finally, although downstream targets originally identified for AMPK were mainly concerned with metabolism, recently identified targets have roles in such diverse areas as mitochondrial fission, integrity of epithelial cell layers, and angiogenesis
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