Symmetric surface waves along a metamaterial dielectric waveguide and a perfectly conducting cylinder covered by a metamaterial layer

Existence of symmetric complex waves in a metamaterial dielectric rod and a perfectly conducting cylinder of circular cross section covered by a concentric layer of metamaterial, a metamaterial Goubau line, is proved. Analytical investigation and numerical solution of dispersion equations reveal several important properties of running waves inherent to open metal-metamaterial waveguides which have not been reported for waveguides filled with standard media.

A N-Hop Concentric Clustering Algorithm with Sub-Clusters in a Wireless Sensor Network

In this paper, we aim to improve theenergy efficiency via a Clustering Algorithm based on Social Insect Colonies (CASIC), inorder to extend the lifetime of Wireless Sensor Networks(WSNs). We propose a CASIC with Sub-clusters (CASIC-S) for reducing the energyconsumption of sensor nodes within the concentric layer during transmission orreception. We also investigate the CASIC-S scheme with different numbers ofnodes in our simulations. The simulation results show that our proposed scheme performs better in terms of first node death and the number of nodes alive.

In silico analyses of pericycle cell populations reinforce their relation with associated vasculature in Arabidopsis

In Arabidopsis , lateral root initiation occurs in a subset of pericycle cells at the xylem pole that will divide asymmetrically to give rise to a new lateral root organ. While lateral roots never develop at the phloem pole, it is unclear how the interaction with xylem and phloem poles determines the distinct pericycle identities with different competences. Nevertheless, pericycle cells at these poles are marked by differences in size, by ultrastructural features and by specific proteins and gene expression. Here, we provide transcriptional evidence that pericycle cells are intimately associated with their vascular tissue instead of being a separate concentric layer. This has implications for the identification of cell- and tissue-specific promoters that are necessary to drive and/or alter gene expression locally, avoiding pleiotropic effects. We were able to identify a small set of genes that display specific expression in the phloem or xylem pole pericycle cells, and we were able to identify motifs that are likely to drive expression in either one of those tissues.

Wall structures of myocardial precapillary arterioles and postcapillary venules reexamined and reconstructed in vitro for studies on barrier functions

The barrier functions of myocardial precapillary arteriolar and postcapillary venular walls (PCA or PCV, respectively) are of considerable scientific and clinical interest (regulation of blood flow and recruitment of immune defense). Using enzyme histochemistry combined with confocal microscopy, we reexamined the cell architecture of human PCA and PVC and reconstructed appropriate in vitro models for studies of their barrier functions. Contrary to current opinion, the PCA endothelial tube is encompassed not by smooth muscle cells but rather by a concentric layer of pericytes cocooned in a thick, microparticle-containing extracellular matrix (ECM) that contributes substantially to the tightness of the arteriolar wall. This core tube extends upstream into the larger arterioles, there additionally enwrapped by smooth muscle. PCV consist of an inner layer of large, contractile endothelial cells encompassed by a fragile, wide-meshed pericyte network with a weakly developed ECM. Pure pericyte and endothelial cell preparations were isolated from PCA and PCV and grown in sandwich cultures. These in vitro models of the PCA and PCV walls exhibited typical histological and functional features. In both plasma-like (PLM) and serum-containing (SCM) media, the PCA model (including ECM) maintained its low hydraulic conductivity ( LP = 3.24 ± 0.52·10−8cm·s−1·cmH2O−1) and a high selectivity index for transmural passage of albumin (SIAlb = 0.95 ± 0.02). In contrast, LP and SIAlb in the PCV model (almost no ECM) were 2.55 ± 0.32·10−7cm·s−1·cmH2O−1 and 0.88 ± 0.03, respectively, in PLM, and 1.39 ± 0.10·10−6cm·s−1·cmH2O−1 and 0.49 ± 0.04 in SCM. With the use of these models, systematic, detailed studies on the regulation of microvascular barrier properties now appear to be feasible.

Self-healing of voids in the wax coating on plant surfaces

The cuticles of plants provide a multifunctional interface between the plants and their environments. The cuticle, with its associated waxes, is a protective layer that minimizes water loss by transpiration and provides several functions, such as hydrophobicity, light reflection and absorption of harmful radiation. The self-healing of voids in the epicuticular wax layer has been studied in 17 living plants by atomic force microscopy (AFM), and the process of wax film formation is described. Two modes of wax film formation, a concentric layer formation and striped layer formation, were found, and the process of multilayer wax film formation is discussed. A new method for the preparation of small pieces of fresh, water-containing plant specimens for AFM investigations is introduced. The technique allows AFM investigations of several hours duration without significant shrinkage or lateral drift of the specimen. This research shows how plants refill voids in their surface wax layers by wax self-assembly and should be useful for the design of self-healing materials.