Accurate determination of elastic parameters for multi-component membranes

Heterogeneities in the cell membrane due to coexisting lipid phases have been conjectured to play a major functional role in cell signaling and membrane trafficking. Thereby the material properties of multiphase systems, such as the line tension and the bending moduli, are crucially involved in the kinetics and the asymptotic behavior of phase separation. In this Letter we present a combined analytical and experimental approach to determine the properties of phase-separated vesicle systems. First we develop an analytical model for the vesicle shape of weakly budded biphasic vesicles. Subsequently experimental data on vesicle shape and membrane fluctuations are taken and compared to the model. The combined approach allows for a reproducible and reliable determination of the physical parameters of complex vesicle systems. The parameters obtained set limits for the size and stability of nanodomains in the plasma membrane of living cells.Comment: (*) authors contributed equally, 6 pages, 3 figures, 1 table; added insets to figure

Quality Assessment of MORL Algorithms: A Utility-Based Approach

Sequential decision-making problems with multiple objectives occur often in practice. In such settings, the utility of a policy depends on how the user values different trade-offs between the objectives. Such valuations can be expressed by a so-called scalarisation function. However, the exact scalarisation function can be unknown when the agents should learn or plan. Therefore, instead of a single solution, the agents aim to produce a solution set that contains an optimal solution for all possible scalarisations. Because it is often not possible to produce an exact solution set, many algorithms have been proposed that produce approximate solution sets instead. We argue that when comparing these algorithms we should do so on the basis of user utility, and on a wide range of problems. In practice however, comparison of the quality of these algorithms have typically been done with only a few limited benchmarks and metrics that do not directly express the utility for the user. In this paper, we propose two metrics that express either the expected utility, or the maximal utility loss with respect to the optimal solution set. Furthermore, we propose a generalised benchmark in order to compare algorithms more reliably

Enhancing the Mass Sensitivity of Graphene Nanoresonators Via Nonlinear Oscillations: The Effective Strain Mechanism

We perform classical molecular dynamics simulations to investigate the enhancement of the mass sensitivity and resonant frequency of graphene nanomechanical resonators that is achieved by driving them into the nonlinear oscillation regime. The mass sensitivity as measured by the resonant frequency shift is found to triple if the actuation energy is about 2.5 times the initial kinetic energy of the nanoresonator. The mechanism underlying the enhanced mass sensitivity is found to be the effective strain that is induced in the nanoresonator due to the nonlinear oscillations, where we obtain an analytic relationship between the induced effective strain and the actuation energy that is applied to the graphene nanoresonator. An important implication of this work is that there is no need for experimentalists to apply tensile strain to the resonators before actuation in order to enhance the mass sensitivity. Instead, enhanced mass sensitivity can be obtained by the far simpler technique of actuating nonlinear oscillations of an existing graphene nanoresonator.Comment: published versio

Obesidad infantil y parámetros de composición corporal en niños de extremadura (españa).

Introducción En las sociedades desarrolladas la obesidad es uno de los trastornos nutricionales más frecuente en la infancia y la adolescencia (Serra Majem, 2003) y el quinto factor principal de riesgo de defunción en el mundo (Fernández-Bergés, 2012. Estudios previos establecen que 2 de cada 10 niños/as extremeños padecen obesidad o sobrepeso (Torres, 2008). El objetivo del estudio es describir la prevalencia de la obesidad en escolares extremeños y conocer la influencia de la obesidad sobre factores de parámetros de composición corporal. Métodos 242 niños/as (9 a 12 años) de centros de primaria de la Comunidad Autónoma de Extremadura fueron evaluados. Tras informar y recibir el consentimiento informado de los tutores legales de los sujetos, se llevaron a cabo mediciones individuales de parámetros antropométricos : peso, talla, IMC, masa grasa, masa libre de grasa, % grasa y peso óseo, índice cintura-cadera. Se llevó a cabo un análisis descriptivo para conocer el porcentaje de obesidad entre los escolares y un ANOVA de un factor con un test post hoc para comparar los resultados con los tres niveles del factor de estudio (normopeso, sobrepeso y obesidad). Resultados El 9,9% de los niños/as extremeños evaluados eran obesos, siendo este porcentaje mayor en el caso de los niños (11,2% frente a 8,54% de las niñas). Existen diferencias significativas (p> 0.05) en cuanto al nivel de composición corporal en las variables IMC, ICC, masa grasa y % masa grasa. Conclusiones 18% escolares extremeños presenta sobrepeso u obesidad, valor que se ha mantenido constante en los últimos años. Los niños/as con sobrepeso y obesidad presentan mayores niveles de IMC, ICC y niveles de grasa corporal

A comparison of food portion size estimation by older adults, young adults and nutritionists

Objectives To investigate the ability of older adults, younger adults and nutritionists to assess portion size using traditional methods versus a computer-based method. This was to inform the development of a novel dietary assessment method for older adults “The NANA system”. Design Older and younger adults assessed the portion size of self-served portions of foods from a buffet style set up using traditional and computerised portion size assessment aids. Nutritionists assessed the portion size of foods from digital photographs using computerised portion size aids. These estimates were compared to known weights of foods using univariate analyses of covariance (ANCOVA). Setting The University of Sheffield, United Kingdom. Subjects Forty older adults (aged 65 years and over), 41 younger adults (aged between 18 and 40 years) and 25 nutritionists. Results There was little difference in the abilities of older and younger adults to assess portion size using both assessment aids with the exception of small pieces morphology. Even though the methods were not directly comparable among the test groups, there was less variability in portion size estimates made by the nutritionists. Conclusion Older adults and younger adults are similar in their ability to assess food portion size and demonstrate wide variability of estimation compared to the ability of nutritionists to estimate portion size from photographs. The results suggest that the use of photographs of meals consumed for portion size assessment by a nutritionist may improve the accuracy of dietary assessment. Improved portion size assessment aids are required for all age groups

On T-Duality in Brane Gas Cosmology

In the context of homogeneous and isotropic superstring cosmology, the T-duality symmetry of string theory has been used to argue that for a background space-time described by dilaton gravity with strings as matter sources, the cosmological evolution of the Universe will be nonsingular. In this Letter we discuss how T-duality extends to brane gas cosmology, an approximation in which the background space-time is again described by dilaton gravity with a gas of branes as a matter source. We conclude that the arguments for nonsingular cosmological evolution remain valid.Comment: 8 pages, Appendix adde

Molecular detection of tick‐borne pathogens in bovine blood and ticks from Khentii, Mongolia

Recent studies reported the detection of DNA from tick‐borne pathogens (TBPs) of veterinary relevance such as Anaplasma marginale, Babesia bigemina, Babesia bovis and Theileria orientalis in bovine blood samples from Mongolia. These findings were unexpected, as the known tick vectors of these pathogens are not known to occur in Mongolia. We therefore conducted a study in May and June 2013 in six districts of Khentii province where DNA of the said TBPs was previously found. Ticks collected from the vegetation and rodents, as well as blood samples from cattle, were screened for the presence of TBPs by reverse line blot (RLB) hybridization. Tick larvae collected from rodents were pooled. A total of 310 adult ticks were collected from the vegetation, and 249 tick larvae were collected from 24 rodents. Adult ticks (n = 2,318) and blood samples were collected from 481 heads of cattle. All adult ticks were identified as Dermacentor nuttalli. DNA from Rickettsia raoultii (252/310; 81.3%), an uncharacterized Anaplasma species preliminary named Anaplasma sp. Mongolia (26/310; 8.4%), Candidatus Midichloria sp. (18/310; 5.8%), Theileria equi (16/310; 5.2%), Babesia caballi (5/310; 1.6%), T. orientalis (1/310; 0.3%), Borrelia afzelii (1/310; 0.3%) and Candidatus Neoehrlichia mikurensis (1/310; 0.3%) was detected in ticks collected from the vegetation. DNA of R. raoultii (27/28; 96.4%) and Midichloria sp. (2/28; 7.1%) was detected in the pooled tick larvae. Anaplasma sp. Mongolia, a species related to Anaplasma ovis based on a multi‐locus analysis, was also detected in 153/481 (31.8%) of the bovine blood samples. DNA of B. bovis, B. bigemina and A. marginale was not detected in the ticks or bovine blood samples from Khentii district

A review of the design and validation of web- and computer-based 24-h dietary recall tools

Technology-based dietary assessment offers solutions to many of the limitations of traditional dietary assessment methodologies including cost, participation rates and the accuracy of data collected. The 24-h dietary recall (24HDR) method is currently the most utilised method for the collection of dietary intake data at a national level. Recently there have been many developments using web-based platforms to collect food intake data using the principles of the 24HDR method. This review identifies web- and computer-based 24HDR tools that have been developed for both children and adult population groups, and examines common design features and the methods used to investigate the performance and validity of these tools. Overall, there is generally good to strong agreement between web-based 24HDR and respective reference measures for intakes of macro- and micronutrients