Serially-regulated biological networks fully realize a constrained set of functions

We show that biological networks with serial regulation (each node regulated by at most one other node) are constrained to {\it direct functionality}, in which the sign of the effect of an environmental input on a target species depends only on the direct path from the input to the target, even when there is a feedback loop allowing for multiple interaction pathways. Using a stochastic model for a set of small transcriptional regulatory networks that have been studied experimentally, we further find that all networks can achieve all functions permitted by this constraint under reasonable settings of biochemical parameters. This underscores the functional versatility of the networks.Comment: 9 pages, 3 figure

Evaluation of surface-modified materials by model assisted analyses of Barkhausen effect signals

Barkhausen effect (BE) measurements offer a useful technique for evaluation of surface conditions of magnetic materials. Theoretical analysis of BE signals has nevertheless remained a challenge due to a lack of adequate model description of the phenomenon. This paper presents model‐assisted analysis of BE signals with an aim of evaluating surface‐modified materials whose magnetic properties vary continuously with depth. The approach is based on an extended BE model which describes the signal power spectrum. In the extended model, the local fluctuation of pinning field and correlation length parameters, which characterize domain wall motion and hence the generation of BE signals, are related to the domain wall pinning strength which vary with depth as described in terms of a parametrized function. In this study, the BE signals measured over a broad frequency range from carburized steels and oxidized Ni97Al3 were analyzed using multiple frequency passbands to extract signals generated at different depths. Depth profiles of the pinning field fluctuation and correlation length were determined by obtaining the best fit of the modeled BE signal power to the experimental data. The inverted profiles show changes at depths which agree with case depths of the carburized steel samples, and with the oxidization depths of the Ni97Al3 samples

Antiferromagnetic Heisenberg model on anisotropic triangular lattice in the presence of magnetic field

We use Schwinger boson mean field theory to study the antiferromagnetic spin-1/2 Heisenberg model on an anisotropic triangular lattice in the presence of a uniform external magnetic field. We calculate the field dependence of the spin incommensurability in the ordered spin spiral phase, and compare the results to the recent experiments in Cs$_{2}$CuCl$_{4}$ by Coldea et al. (Phys. Rev. Lett. 86, 1335 (2001)).Comment: 4 pages with 4 figures include

Patterns of Interactions in Complex Social Networks Based on Coloured Motifs Analysis

Coloured network motifs are small subgraphs that enable to discover and interpret the patterns of interaction within the complex networks. The analysis of three-nodes motifs where the colour of the node reflects its high – white node or low – black node centrality in the social network is presented in the paper. The importance of the vertices is assessed by utilizing two measures: degree prestige and degree centrality. The distribution of motifs in these two cases is compared to mine the interconnection patterns between nodes. The analysis is performed on the social network derived from email communication

Fermi surfaces and quasi-particle band dispersions of the iron pnictides superconductor KFe2As2 observed by angle-resolved photoemission spectroscopy

We have performed an angle-resolved photoemission study of the iron pnictide superconductor KFe2As2 with Tc 4 K. Most of the observed Fermi surfaces show almost two-dimensional shapes, while one of the quasi-particle bands near the Fermi level has a strong dispersion along the kz direction, consistent with the result of a band-structure calculation. However, hole Fermi surfaces \alpha and \zeta are smaller than those predicted by the calculation while other Fermi surfaces are larger. These observations are consistent with the result of a de Haas-van Alphen study and a theoretical prediction on inter-band scattering, possibly indicating many body effects on the electronic structure.Comment: 4 pages, 5 figures. Proceeding of the 9th International Conference on Spectroscopies in Novel Superconductors (SNS2010

The infection of primary avian tracheal epithelial cells with infectious bronchitis virus

Here we introduce a culture system for the isolation, passaging and amplification of avian tracheal epithelial (ATE) cells. The ATE medium, which contains chicken embryo extract and fetal bovine serum, supports the growth of ciliated cells, goblet cells and basal cells from chicken tracheas on fibronectin- or matrigel-coated dishes. Non-epithelial cells make up less than 10% of the total population. We further show that ATE cells support the replication and spread of infectious bronchitis virus (IBV). Interestingly, immunocytostaining revealed that basal cells are resistant to IBV infection. We also demonstrate that glycosaminoglycan had no effect on infection of the cells by IBV. Taken together, these findings suggest that primary ATE cells provide a novel cell culture system for the amplification of IBV and the in vitro characterization of viral cytopathogenesis

Environmental Effects on Glass Fiber Reinforced Polyester and Vinylester Composites

The effects of environment on glass fiber reinforced polyester and vinylester composites immersed in liquids and in humid air were investi gated. Tests were performed at temperatures 23 C and 93 C with the materials exposed to humid air at 50 and 100 percent relative humidities, and to five different liquids: saturated salt water, No. 2 diesel fuel, lubrica ting oil, antifreeze, and indolene. Changes in weight, ultimate tensile strength, tensile modulus, short beam shear strength, and shear modulus were measured over a six month period, and the effects of the environment on these parameters were assessed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66642/2/10.1177_002199838001400304.pd

Immunolocalization of chloride transporters to gill epithelia of euryhaline teleosts with opposite salinity-induced Na+/K+-ATPase responses

Opposite patterns of branchial Na+/K+-ATPase (NKA) responses were found in euryhaline milkfish (Chanos chanos) and pufferfish (Tetraodon nigroviridis) upon salinity challenge. Because the electrochemical gradient established by NKA is thought to be the driving force for transcellular Cl- transport in fish gills, the aim of this study was to explore whether the differential patterns of NKA responses found in milkfish and pufferfish would lead to distinct distribution of Cl- transporters in their gill epithelial cells indicating different Cl- transport mechanisms. In this study, immunolocalization of various Cl- transport proteins, including Na+/K+/2Cl(-) cotransporter (NKCC), cystic fibrosis transmembrane conductance regulator (CFTR), anion exchanger 1 (AE1), and chloride channel 3 (ClC-3), were double stained with NKA, the basolateral marker of branchial mitochondrion-rich cells (MRCs), to reveal the localization of these transporter proteins in gill MRC of FW- or SW-acclimated milkfish and pufferfish. Confocal microscopic observations showed that the localization of these transport proteins in the gill MRCs of the two studied species were similar. However, the number of gill NKA-immunoreactive (IR) cells in milkfish and pufferfish exhibited to vary with environmental salinities. An increase in the number of NKA-IR cells should lead to the elevation of NKA activity in FW milkfish and SW pufferfish. Taken together, the opposite branchial NKA responses observed in milkfish and pufferfish upon salinity challenge could be attributed to alterations in the number of NKA-IR cells. Furthermore, the localization of these Cl- transporters in gill MRCs of the two studied species was identical. It depicted the two studied euryhaline species possess the similar Cl- transport mechanisms in gills

Self-consistent swept frequency eddy current measurements for characterization of near surface material conditions

This paper reports on a self‐consistent, swept frequency eddy current (SFEC) technique for characterizing surface and sub‐surface conditions of materials, with specific applications to detecting residual stresses in shot‐peened Ni‐base superalloys and surface oxidation in engineering components. The technique involves measuring lift‐off normalized vertical component signal to suppress lift off noise and instrumentation effect. Theoretical study shows that the vertical component signals are insensitive to coil dimensions, thus enabling EC measurements in separate frequency bands using multiple coils, while yielding continuous broad‐band data so that both the bulk conductivity and near‐surface conductivity profile can be determined by model‐based inversion. We demonstrate the technique on two surface‐modified materials, namely Inconel 718 samples shot peened at 4 A to 8 A, and an Ag‐1.5at%Al alloy which was used as a model material for a fundamental study of internal oxidation. For each sample set, the vertical component signals measured using two dissimilar sets of coils and instruments were found to overlap, confirming that the signals are insensitive to coil dimensions and instrumentation. The bulk conductivities of the samples were determined by inverting the low frequency data. The results were then used to constrain model‐based inversion of the high frequency data to obtain near‐surface conductivity profiles, from which the residual stress profile of the shot‐peened Inconel 718 and the oxidization depth of the Ag‐Al alloy can be inferred