Constant-angle surfaces in liquid crystals

We discuss some properties of surfaces in R3 whose unit normal has constant angle with an assigned direction field. The constant angle condition can be rewritten as an Hamilton-Jacobi equation correlating the surface and the direction field. We focus on examples motivated by the physics of interfaces in liquid crystals and of layered fluids, and discuss the properties of the constant-angle surfaces when the direction field is singular along a line (disclination) or at a point (hedgehog defect

Parity Breaking in Nematic Tactoids

We theoretically investigate under what conditions the director field in a spindle-shaped nematic droplet or tactoid obtains a twisted, parity-broken structure. By minimizing the sum of the bulk elastic and surface energies, we show that a twisted director field is stable if the twist and bend elastic constants are small enough compared to the splay elastic constant, but only if the droplet volume is larger than some minimum value. We furthermore show that the transition from an untwisted to a twisted director-field structure is a sharp function of the various control parameters. We predict that suspensions of rigid, rod-like particles cannot support droplets with a parity broken structure, whereas they could possibly occur in those of semi-flexible, worm-like particles.Comment: 20 pages, 9 figures, submitted to Journal of Physics: Condensed Matte

Mesoscale simulations of surfactant dissolution and mesophase formation

The evolution of the contact zone between pure surfactant and solvent has been studied by mesoscale simulation. It is found that mesophase formation becomes diffusion controlled and follows the equilibrium phase diagram adiabatically almost as soon as individual mesophases can be identified, corresponding to times in real systems of order 10 microseconds.Comment: 4 pages, 2 figures, ReVTeX

NHI Toetsing, Ontwikkeling en toepassing van methode voor toetsing van NHI 2.1 inclusief vergelijking met NHI 2.0.

Dit rapport beschrijft de achtergrond van de methode om NHI2.1 te toetsen aan de criteria die opgesteld zijn door Rijkswaterstaat Waterdienst geldend voor 2010 en bevat de resultaten van die toetsing en de vergelijking met resultaten van NHI2.0. Volgens de criteria is de berekende aan en afvoer van oppervlakte water verbeterd. Op enkele belangrijke meetpunten van de oppervlaktewaterverdeling zijn signifinante verbeteringen te zien

Perturbation of indole-3-butyric acid homeostasis by the UDP-glucosyltransferase UGT74E2 modulates Arabidopsis architecture and water stress tolerance

Reactive oxygen species and redox signaling undergo synergistic and antagonistic interactions with phytohormones to regulate protective responses of plants against biotic and abiotic stresses. However, molecular insight into the nature of this crosstalk remains scarce. We demonstrate that the hydrogen peroxide–responsive UDP-glucosyltransferase UGT74E2 of Arabidopsis thaliana is involved in the modulation of plant architecture and water stress response through its activity toward the auxin indole-3-butyric acid (IBA). Biochemical characterization of recombinant UGT74E2 demonstrated that it strongly favors IBA as a substrate. Assessment of indole-3-acetic acid (IAA), IBA, and their conjugates in transgenic plants ectopically expressing UGT74E2 indicated that the catalytic specificity was maintained in planta. In these transgenic plants, not only were IBA-Glc concentrations increased, but also free IBA levels were elevated and the conjugated IAA pattern was modified. This perturbed IBA and IAA homeostasis was associated with architectural changes, including increased shoot branching and altered rosette shape, and resulted in significantly improved survival during drought and salt stress treatments. Hence, our results reveal that IBA and IBA-Glc are important regulators of morphological and physiological stress adaptation mechanisms and provide molecular evidence for the interplay between hydrogen peroxide and auxin homeostasis through the action of an IBA UGT

Polymers pushing Polymers: Polymer Mixtures in Thermodynamic Equilibrium with a Pore

We investigate polymer partitioning from polymer mixtures into nanometer size cavities by formulating an equation of state for a binary polymer mixture assuming that only one (smaller) of the two polymer components can penetrate the cavity. Deriving the partitioning equilibrium equations and solving them numerically allows us to introduce the concept of "polymers-pushing-polymers" for the action of non-penetrating polymers on the partitioning of the penetrating polymers. Polymer partitioning into a pore even within a very simple model of a binary polymer mixture is shown to depend in a complicated way on the composition of the polymer mixture and/or the pore-penetration penalty. This can lead to enhanced as well as diminished partitioning, due to two separate energy scales that we analyse in detail.Comment: 10 pages, 6 figure

How simple can a model of an empty viral capsid be? Charge distributions in viral capsids

We investigate and quantify salient features of the charge distributions on viral capsids. Our analysis combines the experimentally determined capsid geometry with simple models for ionization of amino acids, thus yielding the detailed description of spatial distribution for positive and negative charge across the capsid wall. The obtained data is processed in order to extract the mean radii of distributions, surface charge densities and dipole moment densities. The results are evaluated and examined in light of previously proposed models of capsid charge distributions, which are shown to have to some extent limited value when applied to real viruses.Comment: 10 pages, 10 figures; accepted for publication in Journal of Biological Physic

Measurement properties of patient-reported outcome measures (PROMs) for women with Genitourinary Syndrome of Menopause: a systematic review

Background: Genitourinary Syndrome of Menopause (GSM) is a chronic and usually progressive skin disease which affects up to 50% of postmenopausal women. Symptoms, such as vaginal dryness, itching and burning have negative impacts on the women's sexual activity and often come along with urinary problems. Furthermore, these consequences influence the women's quality of life (QoL). Patient‐reported outcome measures can be used to measure the impact of GSM. Objectives: We aimed to identify all existing PROMs that were developed and/or validated for measuring patient‐reported outcomes in women with GSM or vulvovaginal symptoms during menopause and assess the quality of these PROMs in a transparent and structured way. Methods: We performed a systematic literature search in MEDLINE, EMBASE, Web of Science and smaller data bases, and hand‐searched reference lists of included studies. Only studies in English, German, French or Italian aiming at the evaluation of measurement properties, the development of a PROM, or the evaluation of the interpretability of the PROMs of interest were eligible. The methodological quality of eligible studies was evaluated with the COnsensus‐based Standards for the selection of health Measurement INstruments (COSMIN) risk of bias checklist. Quality criteria for good measurement properties were applied and the quality of evidence was graded using a GRADE approach. Information on interpretability and feasibility was extracted as well. PROMs were then categorized into three categories. PROMs of category A had evidence for sufficient content validity and at least low quality evidence for sufficient internal consistency, PROMs of category C had high‐quality evidence for an insufficient measurement property, and PROMs of category B could not be categorized in A or C. Results: Eight studies, two of which were found by reference list screening, were included. These studies reported on four PROMs. All of the included PROMs showed sufficient content validity. Two of the PROMs, the Vaginal Symptoms Questionnaire (VSQ) and the Day‐to‐Day Impact of Vaginal Aging (DIVA) showed moderate‐to‐high quality of evidence for sufficient structural validity and internal consistency, and were categorized as A. They can be therefore recommended for future use. The UGAQoL still has the opportunity to be recommended for use, but further validation is needed. The overall rating was often indeterminate since structural validity or important reliability parameters were not reported. The Urogenital symptom scale cannot be recommended for use since there was high quality of evidence for insufficient structural validity and internal consistency. Conclusion: Currently, two PROMs for women with GSM or vulvovaginal symptoms can be recommended. Nevertheless, those PROMs do not cover the urinary component of GSM. Future validation research should try to confirm and extend the measurement properties of those PROMs to strengthen this recommendation. PROSPERO registration CRD42018092384

Dietary iron intakes based on food composition data may underestimate the contribution of potentially exchangeable contaminant iron from soil

Iron intakes calculated from one-day weighed records were compared with those from same day analyzed duplicate diet composites collected from 120 Malawian women living in two rural districts with contrasting soil mineralogy and where threshing may contaminate cereals with soil iron. Soils and diet composites from the two districts were then subjected to a simulated gastrointestinal digestion and iron availability in the digests measured using a Caco-2 cell model. Median analyzed iron intakes (mg/d) were higher (p < 0.001) than calculated intakes in both Zombwe (16.6 vs. 10.1 mg/d) and Mikalango (29.6 vs. 19.1 mg/d), attributed to some soil contaminant iron based on high Al and Ti concentrations in diet composites. A small portion of iron in acidic soil from Zombwe, but not Mikalango calcareous soil, was bioavailable, as it induced ferritin expression in the cells, and may have contributed to higher plasma ferritin and total body iron for the Zombwe women reported earlier, despite lower iron intakes. In conclusion, iron intakes calculated from food composition data were underestimated, highlighting the importance of analyzing duplicate diet composites where extraneous contaminant iron from soil is likely. Acidic contaminant soil may make a small but useful contribution to iron nutrition