Finite Element Modelling of Fluid-Structure Interaction

The dynamic interaction between non-viscid, compressible fluid and an elastic structure is studied. Finte element formulations, using the weighted residual method, are derived. Different primary variables in the fluid domain are used and different source functions are considered.When a potential field is used, the dynamic interaction between fluid and structure yields nonsymmetric matrices. I addition to these, new symmetric formulations for transient analysis are presented.Some nonlinear fluid behaviour is taken into consideration. Applications to a cavitating fluid due to elastic wave propagation are described.Numerical experiments show good agreement with what could be expected from a physical point of view. The nonlinear formulation shows good agreement with analytical results

Computer aided interactive histology - summary of 10 years

Different computer based learning/teaching aids in histology were developed and tested during a period of ten years. The following conclusions are drawn regarding the advantages of computers as compared to conventional methods. Solving a problem presented by a computer often encourages cooperation between students. Computerized expert systems are useful for the training of certain aspects of our subject, such as the difference in structure between various parts of the digestive system, between different lymphatic organs, skin on different locations of the body, and so on. Images with 'hot spots' and hidden explanatory texts are very useful. A possibility of distance learning of microscopic slides during a course is technically possible and is very much appreciated by students. By using hyperlinked text, information is easier to find and the study can be made more individual and interactive. It is possible to design systems with short answer questions that become very interactive. An immediate feedback about the performance of a student is often appreciated. A test can be more fun by designing it like an adventure game or by giving access to more complicated questions only after completing a qualification test. Presentation of the content of a lecture via the Internet (or a closed part of the home page of a course) is much appreciated and can improve learning. A program does not have to be technically advanced to function as long as there is a pedagogical value. Regarding possible disadvantages with computer programs, one is that everything you create has to be updated continuously. There is a risk that this may develop into a full time job. A conclusion is that it may be wise to concentrate on a few projects. Furthermore, although the students are usually very positive to the use of computers in teaching and learning, the effect on learning is often scored rather low. The reason for this will have to be explored

Coincident Fluorescence-Burst Analysis of the Loading Yields of Exosome-Mimetic Nanovesicles with Fluorescently-Labeled Cargo Molecules

The possible targeting functionality and low immunogenicity of exosomes and exosome-like nanovesicles make them promising as drug-delivery carriers. To tap into this potential, accurate non-destructive methods to load them and characterize their contents are of utmost importance. However, the small size, polydispersity, and aggregation of nanovesicles in solution make quantitative characterizations of their loading particularly challenging. Here, an ad-hoc methodology is developed based on burst analysis of dual-color confocal fluorescence microscopy experiments, suited for quantitative characterizations of exosome-like nanovesicles and of their fluorescently-labeled loading. It is applied to study exosome-mimetic nanovesicles derived from animal extracellular-vesicles and human red blood cell detergent-resistant membranes, loaded with fluorescently-tagged dUTP cargo molecules. For both classes of nanovesicles, successful loading is proved and by dual-color coincident fluorescence burst analysis, size statistics and loading yields are retrieved and quantified. The procedure affords single-vesicle characterizations well-suited for the investigation of a variety of cargo molecules and biological nanovesicle combinations besides the proof-of-principle demonstrations of this study. The results highlight a powerful characterization tool essential for optimizing the loading process and for advanced engineering of biomimetic nanovesicles for therapeutic drug delivery

CALFEM as a Tool for Teaching University Mechanics

Classical mechanics benefits greatly from the ability to demonstrate many concepts experimentally. However, modern mechanics relies more and more on new analysis methods such as the finite element method. In the teaching of mechanics these methods should be introduced, but the desire to experiment and build should be retained as a core issue. One tool for tackling this topic is given by CALFEM1. CALFEM is an acronym for Computer Aided Learning of the Finite Element Method. It is a tool developed for teaching the finite element method but it is also used in research as well as engineering design. The aim of CALFEM has been to provide a transparent link, such that the student can fully appreciate the intimate relationship between the mathematical models of a phenomenon, the finite element method and its computer implementation. This knowledge is not obtained by operation of commercial finite element programs. The pedagogical aspect of CALFEM has been part of the design from the beginning. In research, CALFEM has proven to be an efficient link between ideas and implemented solutions. CALFEM runs as a toolbox to MATLAB2 and provides all of the necessary tools for finite element calculations. The program has been carefully documented in an extensive manual that consists of a reference and a user's manual. The introduction and usage of CALFEM are strengthened by the close connection to teaching materials such as textbooks and exercises. The effectiveness of the system relies upon the widespread use of MATLAB at Lund University. The implementation of a web-based CALFEM has increased the availability of the package and allows for feedback and distribution of updates and additional material

Reinstating Vacated Findings in Employment Discrimination Class Actions: Reconciling General Telephone Co. v. Falcon With Hill v. Western Electric Co.

Type 2 T-helper cell (Th2)-skewed immunity is associated with successful pregnancy and the ability to easily direct immune responses to a Th2-polarised profile may be an evolutionary benefit. The Th2-like immunity associated with allergic disease might generate favourable effects for the maintenance of pregnancy, but could also promote development of Th2-like immune responses and allergic disease in the offspring. The aim of this study was to explore, by using IgE as a stable proxy for Th2, the Th1/Th2 balance in allergic and non-allergic women by measuring allergen-specific and total IgE antibody levels in plasma during pregnancy and after delivery. Specific and total IgE antibody levels were determined by ImmunoCAP technology at five occasions during pregnancy (gestational weeks 10-12, 15-16, 25, 35 and 39), as well as at 2 and 12 months after delivery. Thirty-six women without and 20 women with allergic symptoms were included, of whom 13 were sensitised with allergic symptoms and 30 were non-sensitised without allergic symptoms. The levels of total IgE, but not allergen-specific IgE, were increased during early pregnancy when compared to 12 months after delivery in the sensitised women with allergic symptoms, but not in the non-sensitised women without allergic symptoms (pandlt;0.01). This increase in total IgE levels during early pregnancy only in the sensitised women with allergic symptoms indicates that allergy is associated with an enhanced Th2 deviation during pregnancy.Original Publication: Martina Sandberg, Anne Frykman, Yvonne Jonsson, Marie Persson, Jan Ernerudh, Göran Berg, Leif Matthiesen, Christina Ekerfelt and Maria Jenmalm, Total and allergen-specific IgE levels during and after pregnancy in relation to maternal allergy, 2009, JOURNAL OF REPRODUCTIVE IMMUNOLOGY, (81), 1, 82-88. http://dx.doi.org/10.1016/j.jri.2009.04.003 Copyright: Elsevier Science B.V., Amsterdam. http://www.elsevier.com/</p

The Lyman alpha Reference Sample: Extended Lyman alpha Halos Produced at Low Dust Content

We report on new imaging observations of the Lyman alpha emission line (Lya), performed with the Hubble Space Telescope, that comprise the backbone of the Lyman alpha Reference Sample (LARS). We present images of 14 starburst galaxies at redshifts 0.028 < z < 0.18 in continuum-subtracted Lya, Halpha, and the far ultraviolet continuum. We show that Lya is emitted on scales that systematically exceed those of the massive stellar population and recombination nebulae: as measured by the Petrosian 20 percent radius, RP20, Lya radii are larger than those of Halpha by factors ranging from 1 to 3.6, with an average of 2.4. The average ratio of Lya-to-FUV radii is 2.9. This suggests that much of the Lya light is pushed to large radii by resonance scattering. Defining the "Relative Petrosian Extension" of Lya compared to Halpha, \xi_ext = RP20_Lya / RP20_Ha, we find \xi_ext to be uncorrelated with total Lya luminosity. However \xi_ext is strongly correlated with quantities that scale with dust content, in the sense that a low dust abundance is a necessary requirement (although not the only one) in order to spread Lya photons throughout the interstellar medium and drive a large extended Lya halo.Comment: Published in ApJ Letters ~~ 6 pages using emulateapj, 4 figures ~~ Higher-resolution, larger, nicer jpeg versions of Figures 1 and 2 can be found here: http://xayes.org/pub/press_lars.htm

The Lyman Alpha Reference Sample IX: Revelations from deep surface photometry

The Lyman Alpha Reference Sample (LARS) of 14 star-forming galaxies offers a wealth of insight into the workings of these local analogs to high-redshift star-forming galaxies. The sample has been well-studied in terms of LyA and other emission line properties, such as HI mass, gas kinematics, and morphology. We analyze deep surface photometry of the LARS sample in UBIK broadband imaging obtained at the Nordic Optical Telescope and the Canada-France-Hawaii Telescope, and juxtaposition their derived properties with a sample of local high-redshift galaxy analogs, namely, with blue compact galaxies (BCGs). We construct radial surface brightness and color profiles with both elliptical and isophotal integration, as well as RGB images, deep contours, color maps, a burst fraction estimate, and a radial mass-to-light ratio profile for each LARS galaxy. Standard morphological parameters like asymmetry, clumpiness, the Gini and M20 coefficients are [...] analyzed, as well as isophotal asymmetry profiles for each galaxy. [...] We compare the LARS to the properties of the BCG sample and highlight the differences. Several diagnostics indicate that the LARS galaxies have highly disturbed morphologies even at the level of the faintest isophotes [...]. The ground-based photometry [...] reveals previously unexplored isophotes [...]. The burst fraction estimate suggests a spatially more extended burst region in LARS than in the BCGs. [...] The galaxies in the LARS sample appear to be in earlier stages of a merger event compared to the BCGs. Standard morphological diagnostics like asymmetry, clumpiness, Gini and M20 coefficients cannot separate the two samples, although an isophotal asymmetry profile successfully captures the average difference in morphology. These morphological diagnostics do not show any correlation with the equivalent width or the escape fraction of Lyman Alpha. [abridged]Comment: 27 pages, 15 figures, accepted for publication in A&