Wannier-based calculation of the orbital magnetization in crystals

We present a first-principles scheme that allows the orbital magnetization of a magnetic crystal to be evaluated accurately and efficiently even in the presence of complex Fermi surfaces. Starting from an initial electronic-structure calculation with a coarse ab initio k-point mesh, maximally localized Wannier functions are constructed and used to interpolate the necessary k-space quantities on a fine mesh, in parallel to a previously-developed formalism for the anomalous Hall conductivity [X.Wang, J. Yates, I. Souza, and D. Vanderbilt, Phys. Rev. B 74, 195118 (2006)]. We formulate our new approach in a manifestly gauge-invariant manner, expressing the orbital magnetization in terms of traces over matrices in Wannier space. Since only a few (e.g., of the order of 20) Wannier functions are typically needed to describe the occupied and partially occupied bands, these Wannier matrices are small, which makes the interpolation itself very efficient. The method has been used to calculate the orbital magnetization of bcc Fe, hcp Co, and fcc Ni. Unlike an approximate calculation based on integrating orbital currents inside atomic spheres, our results nicely reproduce the experimentally measured ordering of the orbital magnetization in these three materials.Comment: 13 pages, 3 figures, 4 table

HERA prospects on Compositeness and New Vector Bosons

The absence of deviations from the Standard Model for the differential cross section ${d\sigma}/{dQ^2}$ at HERA is used to set limits on electron quark compositeness scale and on new vector bosons, especially the hadrophilic one recently introduced as a possible explanation for LEP/SLC and CDF anomalies.Comment: Latex file, 7 pages and 1 ps fig, few comments on others experiments are added, results are unchanged. To appear in Phys. Let.

On Top of the Alveolar Epithelium: Surfactant and the Glycocalyx

Gas exchange in the lung takes place via the air-blood barrier in the septal walls of alveoli. The tissue elements that oxygen molecules have to cross are the alveolar epithelium, the interstitium and the capillary endothelium. The epithelium that lines the alveolar surface is covered by a thin and continuous liquid lining layer. Pulmonary surfactant acts at this air-liquid interface. By virtue of its biophysical and immunomodulatory functions, surfactant keeps alveoli open, dry and clean. What needs to be added to this picture is the glycocalyx of the alveolar epithelium. Here, we briefly review what is known about this glycocalyx and how it can be visualized using electron microscopy. The application of colloidal thorium dioxide as a staining agent reveals differences in the staining pattern between type I and type II alveolar epithelial cells and shows close associations of the glycocalyx with intraalveolar surfactant subtypes such as tubular myelin. These morphological findings indicate that specific spatial interactions between components of the surfactant system and those of the alveolar epithelial glycocalyx exist which may contribute to the maintenance of alveolar homeostasis, in particular to alveolar micromechanics, to the functional integrity of the air-blood barrier, to the regulation of the thickness and viscosity of the alveolar lining layer, and to the defence against inhaled pathogens. Exploring the alveolar epithelial glycocalyx in conjunction with the surfactant system opens novel physiological perspectives of potential clinical relevance for future research

Methods for estimating the size of Google Scholar

The emergence of academic search engines (mainly Google Scholar and Microsoft Academic Search) that aspire to index the entirety of current academic knowledge has revived and increased interest in the size of the academic web. The main objective of this paper is to propose various methods to estimate the current size (number of indexed documents) of Google Scholar (May 2014) and to determine its validity, precision and reliability. To do this, we present, apply and discuss three empirical methods: an external estimate based on empirical studies of Google Scholar coverage, and two internal estimate methods based on direct, empty and absurd queries, respectively. The results, despite providing disparate values, place the estimated size of Google Scholar at around 160 to 165 million documents. However, all the methods show considerable limitations and uncertainties due to inconsistencies in the Google Scholar search functionalities.Comment: 22 pages, 4 figures and 6 tables. arXiv admin note: text overlap with arXiv:1407.623

Active materials for adaptive architectural envelopes based on plant adaptation principles

In this paper, the authors present research into adaptive architectural envelopes that adapt to environmental changes using active materials, as a result of application of biomimetic principles from plants to architecture. Buildings use large amounts of energy in order to maintain their internal comfort, because conventional buildings are designed to provide a static design solution. Most of the current solutions for facades are not designed for optimum adaptation to contextual issues and needs, while biological solutions to adaptation are often complex, multi-functional and highly responsive. We focus on plant adaptations to the environment, as, due to their immobility, they have developed special means of protection against weather changing conditions. Furthermore, recent developments in new technologies are allowing the possibility to transfer these plant adaptation strategies to technical implementation. These technologies include: multi-material 3D printing, advances in materials science and new capabilities in simulation software. Unlike traditional mechanical activation used for dynamic systems in kinetic facades, adaptive architectural envelopes require no complex electronics, sensors, or actuators. The paper proposes a research of the relationship that can be developed between active materials and environmental issues in order to propose innovative and low-tech design strategies to achieve living envelopes according to plant adaptation principles

Analysis of data from a free-listing study of menus by different income-level populations

Free listing can help understand how a domain is perceived across a group of people by examining the average psychological saliency of items, in this case, menus elicited by a population. The objectives of the present work were: (a) compare different indexes used to analyze the saliency of items listed by individuals in a free-listing exercise, (b) test if time distance can be an improvement over rank distance in associating items mentioned by subjects, and (c) apply the above indexes and associations to gain insight in the menus listed by different income-level populations in Argentina. In the present study we surveyed a total of 200 women from low and medium/high-income levels who were asked to list all the menus they knew registering the mention order and time to mention. Smith's saliency index and cognitive salience index (CSI), previously not applied in the food science literature, proved useful in selecting the core menus listed by a population. The hypothesis that time distance would be a more adequate measure of the association of items in a list than order of mention was not sustained in the present study. Cluster analysis was also found useful in analyzing how menus were grouped by different income levels using a free-listing procedure. ANOVA on the CSI values showed a significant menu × income-level interaction, thus indicating that saliency was not the same for listed menus across income levels.Fil: Libertino, Luciano Martin. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; ArgentinaFil: Ferraris, Daniela Cristina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Lopez Osornio, M. M.. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; ArgentinaFil: Hough, Guillermo. Provincia de Buenos Aires. Gobernación. Comisión de Investigaciones Científicas; Argentina. Provincia de Buenos Aires. Dirección General de Cultura y Educación. Instituto Superior Experimental de Tecnología Alimentaria; Argentin