Shock waves on complex networks

Power grids, road maps, and river streams are examples of infrastructural networks which are highly vulnerable to external perturbations. An abrupt local change of load (voltage, traffic density, or water level) might propagate in a cascading way and affect a significant fraction of the network. Almost discontinuous perturbations can be modeled by shock waves which can eventually interfere constructively and endanger the normal functionality of the infrastructure. We study their dynamics by solving the Burgers equation under random perturbations on several real and artificial directed graphs. Even for graphs with a narrow distribution of node properties (e.g., degree or betweenness), a steady state is reached exhibiting a heterogeneous load distribution, having a difference of one order of magnitude between the highest and average loads. Unexpectedly we find for the European power grid and for finite Watts-Strogatz networks a broad pronounced bimodal distribution for the loads. To identify the most vulnerable nodes, we introduce the concept of node-basin size, a purely topological property which we show to be strongly correlated to the average load of a node

A Systems Biology Interpretation of Array Comparative Genomic Hybridization (aCGH) Data through Phylogenetics

Array Comparative Genomic Hybridization (aCGH) is a rapid screening technique to detect gene deletions and duplications, providing an overview of chromosomal aberrations throughout the entire genome of a tumor, without the need for cell culturing. However, the heterogeneity of aCGH data obfuscates existing methods of data analysis. Analysis of aCGH data from a systems biology perspective or in the context of total aberrations is largely absent in the published literature. We present here a novel alternative to the functional analysis of aCGH data using the phylogenetic paradigm that is well-suited to high dimensional datasets of heterogeneous nature, but has not been widely adapted to aCGH data. Maximum parsimony phylogenetic analysis sorts out genetic data through the simplest presentation of the data on a cladogram, a graphical evolutionary tree, thus providing a powerful and efficient method for aCGH data analysis. For example, the cladogram models the multiphasic changes in the cancer genome and identifies shared early mutations in the disease progression, providing a simple yet powerful means of aCGH data interpretation. As such, applying maximum parsimony phylogenetic analysis to aCGH results allows for the differentiation between drivers and passenger genes aberrations in cancer specimens. In addition to offering a novel methodology to analyze aCGH results, we present here a crucial software suite that we wrote to carry out the analysis. In a broader context, we wish to underscore that phylogenetic analysis of aCGH data is a non-parametric method that circumvents the pitfalls and frustrations of standard analytical techniques that rely on parametric statistics. Organizing the data in a cladogram as explained in this research article provides insights into the disease common aberrations, as well as the disease subtypes and their shared aberrations (the synapomorphies) of each subtype. Hence, we report the method and make the software suite publicly and freely available at http://software.phylomcs.com so that researchers can test alternative and innovative approaches to the analysis of aCGH data

Large random correlations in individual mean field spin glass samples

We argue that complex systems must possess long range correlations and illustrate this idea on the example of the mean field spin glass model. Defined on the complete graph, this model has no genuine concept of distance, but the long range character of correlations is translated into a broad distribution of the spin-spin correlation coefficients for almost all realizations of the random couplings. When we sample the whole phase space we find that this distribution is so broad indeed that at low temperatures it essentially becomes uniform, with all possible correlation values appearing with the same probability. The distribution of correlations inside a single phase space valley is also studied and found to be much narrower.Comment: Added a few references and a comment phras

Epithelial 3D-spheroids as a tool to study air pollutant-induced lung pathology

Cigarette smoke (CS) and air pollutants (AP) activate pathological processes in bronchial epithelial cells resulting in lung function decline which severely impacts human health. Knowledge about the molecular mechanism(s) by which CS and AP induce pathology is limited. Our previous studies in 2D cultures of human bronchial epithelial (BEAS-2B) cells showed that CS exposure activates transforming growth factor-β1 (TGF-β1) release and signaling. Furthermore, CS exposure reduced the expression of E-cadherin, which was prevented by applying a TGF-β1 neutralizing antibody. Exposure of BEAS-2B cells cultured in 2D to diesel exhaust particles (DEP) increased TGF-β1 protein expression and reduced the expression of epithelial cell markers, whereas mesenchymal markers are upregulated. Conventional 2D cell culture may, however, not fully reflect the physiology of bronchial epithelial cells in vivo. To simulate the in vivo situation more closely we cultured the bronchial epithelial cells in a 3D environment in the current study. Treatment of epithelial spheroids with TGF-β resulted in reduced E-cadherin and increased collagen I expression, indicating the activation of epithelial-to-mesenchymal transition (EMT). Similarly, exposure of spheroids to DEP induced and EMT-like phenotype. Collectively, our data indicate AP induces an EMT-like phenotype of BEAS-2B cells in 3D spheroid cultures. This opens new avenues for drug development for the treatment of lung diseases induced by AP. The 3D spheroid cell culture is a novel, innovative and physiologically relevant model for culturing a variety of cells. It is a versatile tool for both high-throughput studies and for identifying molecular mechanisms involved in bronchial epithelial cell (patho)physiology

Individualized Stabilization Criteria–Driven Ranibizumab versus Laser in Branch Retinal Vein Occlusion

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Injection into coal seams for simultaneous CO{sub 2} mitigation and enhanced recovery of coalbed methane. Topical report, March 1995--March 1996

The overall objective of this task is to test the technical viability of injecting CO{sub 2} into the Fruitland Coal to displace methane from the coal and to mitigate CO{sub 2} emissions that are a consequence of primary coalbed methane production from surrounding wells in the area. To evaluate this technical viability, a field test was conducted and the test is being interpreted using data measured in WRI`s laboratory, as well as using Amoco`s state-of-the-art coalbed methane simulator. Also, a second pilot of the process is being evaluated using the simulator. Ultimately, the technology developed will be applied to a Wyoming coal

Comparison of Serum IgG Antibody Test with Gastric Biopsy for the Detection of Helicobacter Pylori Infection among Egyptian Children

BACKGROUND: In developing countries, Helicobacter pylori (H. pylori) infection is mainly acquired during childhood and may be a predisposing factor for peptic ulcer or gastric cancer later in life. Noninvasive diagnostic tools are particularly useful in children for screening tests and epidemiological studies. Data on serologic testing of children are lacking. Accurate noninvasive tests for diagnosing Helicobacter pylori infection in children are strongly required.AIM: The aim of this study was to evaluate the performance of a serological test (serum IgG antibody for H. pylori) in Egyptian children with recurrent abdominal pain necessitating endoscopy.SUBJECTS AND METHODS: One hundred children, referred to the endoscopy unit at Mansoura University. Upper endoscopy was done for each with rapid urease test (RUT) and histological examination as the gold standard test for detection of H. pylori infection. Serum samples were collected for detecting IgG for H. pylori infection.RESULTS: The mean age of the subjects included in the study was 7.23 ± 1.94 year. Serological test (IgG to H. pylori) was positive in 60% of all cases. A highly significant association between the standard test and the serological test at a cutoff > 10 U/ml at p = 0.001 were detected for the diagnosis of H. pylori infection. The sensitivity, specificity, positive likelihood ratio, and negative likelihood ratio for the IgG antibody a cutoff > 10 U/ml, were 96.5%, 93%, 13.83, 0.038 respectively.CONCLUSION: Serum IgG antibody to H. pylori infection has a high diagnostic value and can be considered as a suitable and reliable noninvasive test for detection of H. pylori infection

Infrared luminescence for real time ionizing radiation detection

Radio-luminescence (RL) optical fiber sensors enable a remote, punctual, and real time detection of ionizing radiation. However, the employment of such systems for monitoring extended radiation fields with energies above the Cerenkov threshold is still challenging, since a spurious luminescence, namely, the "stem effect," is also generated in the passive fiber portion exposed to radiation. Here, we present experimental measurements on Yb-doped silica optical fibers irradiated with photon fields of different energies and sizes. The results demonstrate that the RL of Yb3+, displaying a sharp emission line at about 975 nm, is free from any spectral superposition with the spurious luminescence. This aspect, in addition with the suitable linearity, reproducibility, and sensitivity properties of the Yb-doped fibers, paves the way to their use in applications where an efficient stem effect removal is required