A Variational Level Set Approach for Surface Area Minimization of Triply Periodic Surfaces

In this paper, we study triply periodic surfaces with minimal surface area under a constraint in the volume fraction of the regions (phases) that the surface separates. Using a variational level set method formulation, we present a theoretical characterization of and a numerical algorithm for computing these surfaces. We use our theoretical and computational formulation to study the optimality of the Schwartz P, Schwartz D, and Schoen G surfaces when the volume fractions of the two phases are equal and explore the properties of optimal structures when the volume fractions of the two phases not equal. Due to the computational cost of the fully, three-dimensional shape optimization problem, we implement our numerical simulations using a parallel level set method software package.Comment: 28 pages, 16 figures, 3 table

Self-Assembly in Monoelaidin Aqueous Dispersions: Direct Vesicles to Cubosomes Transition

Background: In the present study, synchrotron small-angle X-ray scattering (SAXS) and Cryo-TEM were used to characterize the temperature-induced structural transitions of monoelaidin (ME) aqueous dispersion in the presence of the polymeric stabilizer F127. We prove that the direct transition from vesicles to cubosomes by heating this dispersion is possible. The obtained results were compared with the fully hydrated bulk ME phase. Methodology/principal findings: Our results indicate the formation of ME dispersion, which is less stable than that based on the congener monoolein (MO). In addition, the temperature-dependence behavior significantly differs from the fully hydrated bulk phase. SAXS findings indicate a direct L(alpha)-V(2) internal transition in the dispersion. While the transition temperature is conserved in the dispersion, the formed cubosomes with internal Im3m symmetry clearly contain more water and this ordered interior is retained over a wider temperature range as compared to its fully hydrated bulk system. At 25 degrees C, Cryo-TEM observations reveal the formation of most likely closely packed onion-like vesicles. Above the lamellar to non-lamellar phase transition at 65 degrees C, flattened cubosomes with an internal nanostructure are observed. However, they have only arbitrary shapes and thus, their morphology is significantly different from that of the well-shaped analogous MO cubosome and hexosome particles. Conclusions/significance: Our study reveals a direct liposomes-cubosomes transition in ME dispersion. The obtained results suggest that the polymeric stabilizer F127 especially plays a significant role in the membrane fusion processes. F127 incorporates in considerable amount into the internal nanostructure and leads to the formation of a highly swollen Im3m phase

Tuning Curvature and Stability of Monoolein Bilayers by Designer Lipid-Like Peptide Surfactants

This study reports the effect of loading four different charged designer lipid-like short anionic and cationic peptide surfactants on the fully hydrated monoolein (MO)-based Pn3m phase (Q224). The studied peptide surfactants comprise seven amino acid residues, namely A6D, DA6, A6K, and KA6. D (aspartic acid) bears two negative charges, K (lysine) bears one positive charge, and A (alanine) constitutes the hydrophobic tail. To elucidate the impact of these peptide surfactants, the ternary MO/peptide/water system has been investigated using small-angle X-ray scattering (SAXS), within a certain range of peptide concentrations (R≤0.2) and temperatures (25 to 70°C). We demonstrate that the bilayer curvature and the stability are modulated by: i) the peptide/lipid molar ratio, ii) the peptide molecular structure (the degree of hydrophobicity, the type of the hydrophilic amino acid, and the headgroup location), and iii) the temperature. The anionic peptide surfactants, A6D and DA6, exhibit the strongest surface activity. At low peptide concentrations (R = 0.01), the Pn3m structure is still preserved, but its lattice increases due to the strong electrostatic repulsion between the negatively charged peptide molecules, which are incorporated into the interface. This means that the anionic peptides have the effect of enlarging the water channels and thus they serve to enhance the accommodation of positively charged water-soluble active molecules in the Pn3m phase. At higher peptide concentration (R = 0.10), the lipid bilayers are destabilized and the structural transition from the Pn3m to the inverted hexagonal phase (H2) is induced. For the cationic peptides, our study illustrates how even minor modifications, such as changing the location of the headgroup (A6K vs. KA6), affects significantly the peptide's effectiveness. Only KA6 displays a propensity to promote the formation of H2, which suggests that KA6 molecules have a higher degree of incorporation in the interface than those of A6K

The multiple faces of self-assembled lipidic systems

Lipids, the building blocks of cells, common to every living organisms, have the propensity to self-assemble into well-defined structures over short and long-range spatial scales. The driving forces have their roots mainly in the hydrophobic effect and electrostatic interactions. Membranes in lamellar phase are ubiquitous in cellular compartments and can phase-separate upon mixing lipids in different liquid-crystalline states. Hexagonal phases and especially cubic phases can be synthesized and observed in vivo as well. Membrane often closes up into a vesicle whose shape is determined by the interplay of curvature, area difference elasticity and line tension energies, and can adopt the form of a sphere, a tube, a prolate, a starfish and many more. Complexes made of lipids and polyelectrolytes or inorganic materials exhibit a rich diversity of structural morphologies due to additional interactions which become increasingly hard to track without the aid of suitable computer models. From the plasma membrane of archaebacteria to gene delivery, self-assembled lipidic systems have left their mark in cell biology and nanobiotechnology; however, the underlying physics is yet to be fully unraveled

Musik + NPF = Sant : Musiklärares arbete med elever med neuropsykiatriska funktionsnedsättningar (NPF)

Studien syftar till att bidra med ökad förståelse om musiklärares arbete med elever med NPF (neuropsykiatrisk funktionsnedsättning) i den ordinarie undervisningen. Jag har sökt finna både musiklärares arbetssätt och uppfattningar kring elever med NPF. Studien utgår från ett relationellt perspektiv. Jag har genomfört fyra kvalitativa intervjuer med musiklärare som arbetar på grundskolan samt en som jobbar på ett särgymnasium. Resultatet visade på en mängd arbetssätt och uppfattningar så som vikten av: anpassningar i miljön, struktur, samarbete med andra lärare, följa elevernas intresse och fysiska hjälpmedel. Resultatet visade också på vikten av att göra anpassningar som kommer alla till gagn. I slutsatsen tar jag bland annat upp att genom ordnad miljö, struktur, fysiska hjälpmedel, samverkan, flexibilitet, och adekvata lokaler och gruppstorlekar går det att möta elever med NPF på ett framgångsrikt sätt i musik i den ordinarie undervisningen.This thesis aims to contribute to an increased understanding of music teachers' work with students with special needs, such as ADHD and autism, (called NPF) in the ordinary school in Sweden. I have tried to find both music teachers' working methods and their perceptions about students with NPF. The study is based on a relational perspective. I have done four qualitative interviews with music teachers who work in the primary school and one teacher that works in a special high school. The results showed a variety of working methods and perceptions, such as the importance of: adjustments and changes in the environment, structure, collaboration with other teachers, following students' interests and physical tools. The results also showed the importance of making adjustments that benefit every student. In the conclusion I mention that through an orderly environment, structure, physical tools, collaboration, flexibility, and adequate premises and group sizes, it is possible to meet all students needs successfully in music in the regular school

Arrangering för vokalgrupp

Syftet med detta arbete är att synliggöra processen vid arrangerandet av en låt för vokalgrupp i den afroamerikanska genren. Bland annat musikteoriprofessorn Roine Janssons idéer om vokalgruppsarrangering, The Real Groups- och Trey McLaughlins vokalgruppsarrangemang har inspirerat detta arbete. För att undersöka processen har den dokumenterats genom loggboksskrivande, sparade sibeliusutkast och videoinspelningar från träffar med en ihopsatt vokalgrupp som testar arrangemanget allteftersom det utformats. Undersökandet av vad en kreativ process innebär har också stått i fokus. I mitt resultat har det kommit fram vad jag har lagt störst vikt vid. Det har varit variation, dynamisk balans, låta röster härma andra instrument, sociala aspekter vid arrangerandet och att ha tid och att bejaka och testa allt. Jag har till stor del arbetat efter eget tycke och smak med att arrangera och experimentera för att hitta en helhet så som jag vill ha den och som fungerar för sångare i målgruppen. I diskussionen tar jag upp insikter om arrangering och vad som har gynnat kreativiteten

Allergi påverkar det ett barns vistelse i förskola/skola? : Vilka kunskaper finns det idag angående barn och allergi?

Sammanfattning   Barn drabbas i allt större utsträckning av allergi i någon form. Det är viktigt att forska kring dess medicinska verkningar på barnen och påverkan av allergin i det dagliga livet. Det forskas mycket idag kring barn och allergi. Läkarna ser en uppgång under senaste decennierna och ingen bättring i sikte. Det kan bero på dagens livsstil och miljötänkande. En större förståelse i dagens samhälle för barnens sjukdom behövs i många sammanhang. Jag använde mig av en kvalitativ intervjumetod för att få reda på barnens kunskaper och tankar kring ämnet. Jag har även gått igenom tidigare forskning kring ämnet. I min litteratur/enkätstudie framkom det att barnen vet mycket om allergi och att de får försaka aktiviteter inom skola/fritid. De barn som hade någon närstående eller kamrat på förskolan med allergi hade goda kunskaper och insikter i hur det var att leva med allergi. Nyckelord: Allergi, Allergen, Immunförsvaret, Pollen och Överkänslighet.  Detta är den version som ska gälla, den gamla innehåller fel

The Coming of Age of a Woman : Proto-feminism and Female Bildung in Jane Austen’s Northanger Abbey

This thesis examines the influence of the proto-feminist ideas of the Enlightenment on Jane Austen’s Northanger Abbey, specifically their presence in the coming-of-age journey of the novel’s heroine Catherine Morland. In this thesis, the proto-feminist ideas of the Enlightenment discussed are based on the ideas of Mary Wollstonecraft as presented in A Vindication of the Rights of Woman. I focus on Wollstonecraft’s emphasis on the importance of reason for the emancipation of women as well as the role of virtue and modesty, but also on the existence of an ambivalent relationship between sense and sentiment. The aim of the thesis is to show that Catherine Morland’s coming-of-age journey in Northanger Abbey can be understood as a representation of the emancipation of women that Wollstonecraft hopes for, and that the obstacles standing in the way of Catherine’s maturation are parallel to the obstacles which, during the Enlightenment, prevented women from claiming reason for themselves. First, I draw upon Wollstonecraft’s criticism of sentimental fiction and its hampering effect on women’s minds and show that the same idea is present in the narrative of Northanger Abbey, in the shape of gothic fiction. Then, I show how Catherine’s ability to discern between virtuous and immodest behaviour improves drastically as she starts to exercise her reason, in concurrence with Wollstonecraft’s claim that all virtuous thought must stem from reason. I analyse the importance of Catherine’s choice of partner and its relationship to the proto-feminist critique of women’s inability to express ideas contrary to those of a man. Finally, I dissect the proto-feminist ambivalent relationship between sense and sentiment and connect it to the finale of Northanger Abbey. These elements put together all point toward Wollstonecraft and Austen being coextensive, and demonstrate how Austen makes use of Wollstonecraft’s ideas to promote the emergence of female bildung

Cubic Cell Membrane Architectures. Taking another look at membrane bound cell spaces

A systematic study of cell membrane morphologies whose structure is governed by cubic symmetries has been performed. It is suggested that they are described by periodic cubic surfaces for which space filling surface foliations given by truncated Fourier series defined by the space groups is used as structural representations. Using this a method is developed which enables a direct ultrastructural comparison between calculated projected electron density maps of a given periodic cubic surface and transmission electron micrographs of biological specimens displaying cubic membrane morphologies. Convincing results are given for the existence of three families of periodic cubic structures based on the surfaces known as the gyroid, double-diamond, and primitive. In each family balanced, unbalanced, and morphologies with a set of multiple membrane foliations are perceived. The accuracy to which these morphologies are described as periodic cubic surfaces, and the ease with which parameters such as surface area and volume ratios can be calculated, suggest their utility as a stereologic tool. A manifold of membrane morphologies with hitherto unknown cubic symmetries is identified and classified to form in conjunction with endoplasmic reticulum, inner nuclear envelope, mitochondria, trans-Golgi apparatus, chloroplasts, plasma membrane and lysosomes. Their occurrence is concluded to be of general nature and representative examples are given in cells ranging from protozoa to man in a large variety of species and tissue types thereof. In all cases studied, formation of cubic membrane morphologies can be explained by an intersection-free membrane folding model. From analysis of a vast number of electron micrographs of particular cases of cubic membranes the existence of structurally invariant morphologies is conjectured. Examples include the prolamellar body and the t-tubular honeycomb networks of skeletal muscles, which are invariantly described in reference to a double diamond and a gyroid surface, respectively. Plausible structure-function relations for these are discussed. Several theories regarding the function of cubic membranes as subcellular space-partitioners are put forward. Noticeably, the cubic membrane morphologies described by a set of n multiple membrane foliations defines n + 1 subspaces inherent to the organelle. It is postulated to be of global validity in cell space partitioning and its possible significance is addressed