Deformed Gaussian Orthogonal Ensemble description of Small-World networks

The study of spectral behavior of networks has gained enthusiasm over the last few years. In particular, Random Matrix Theory (RMT) concepts have proven to be useful. In discussing transition from regular behavior to fully chaotic behavior it has been found that an extrapolation formula of the Brody type can be used. In the present paper we analyze the regular to chaotic behavior of Small World (SW) networks using an extension of the Gaussian Orthogonal Ensemble. This RMT ensemble, coined the Deformed Gaussian Orthogonal Ensemble (DGOE), supplies a natural foundation of the Brody formula. SW networks follow GOE statistics till certain range of eigenvalues correlations depending upon the strength of random connections. We show that for these regimes of SW networks where spectral correlations do not follow GOE beyond certain range, DGOE statistics models the correlations very well. The analysis performed in this paper proves the utility of the DGOE in network physics, as much as it has been useful in other physical systems.Comment: Replaced with the revised version, accepted for publication in Phys. Rev.

Vegetation of the coastal dunes and wetland of Schinias National Park (NE Attica, Sterea Ellas, Greece)

The vegetation developing on the coastal sand dunes and wetland of Schinias National Park, a Natura 2000 Site, was studied following the Braun-Blanquet method. Vegetation units were delimited using cluster analysis and by applying the fidelity measure; the phi-coefficient was used for the definition of diagnostic species. The vegetation types distinguished (twenty associations, two sub-associations and thirteen communities not assigned formal rank), which belong to 18 alliances, 16 orders and 12 classes, are discussed and presented in phytosociological tables. Among them Mathiolo tricuspidatae-Anthemidetum tomentosae, Pistacio lentisci-Pinetum halepensis pinetosum pineae, Puccinellio festuciformis-Aeluropetum litoralis cressetosum creticae and Tamaricetum tetrandrae are described for the first time. The vegetation types recognized in the study area are linked to twelve EUNIS habitat types, nine of which are related to 13 Annex I habitat types (Directive 92/43/EEC), and one to a habitat type of national interest (72A0). One Annex I habitat type occurring in the study area has scattered presence in the Natura 2000 network in Greece (1420), two are infrequent (2190, 2260), two are rare (2230, 2270) and three are priority habitat types (1150, 2250, 2270)

Self-organized and driven phase synchronization in coupled maps

We study the phase synchronization and cluster formation in coupled maps on different networks. We identify two different mechanisms of cluster formation; (a) {\it Self-organized} phase synchronization which leads to clusters with dominant intra-cluster couplings and (b) {\it driven} phase synchronization which leads to clusters with dominant inter-cluster couplings. In the novel driven synchronization the nodes of one cluster are driven by those of the others. We also discuss the dynamical origin of these two mechanisms for small networks with two and three nodes.Comment: 4 pages including 2 figure

Spectral analysis of deformed random networks

We study spectral behavior of sparsely connected random networks under the random matrix framework. Sub-networks without any connection among them form a network having perfect community structure. As connections among the sub-networks are introduced, the spacing distribution shows a transition from the Poisson statistics to the Gaussian orthogonal ensemble statistics of random matrix theory. The eigenvalue density distribution shows a transition to the Wigner's semicircular behavior for a completely deformed network. The range for which spectral rigidity, measured by the Dyson-Mehta $\Delta_3$ statistics, follows the Gaussian orthogonal ensemble statistics depends upon the deformation of the network from the perfect community structure. The spacing distribution is particularly useful to track very slight deformations of the network from a perfect community structure, whereas the density distribution and the $\Delta_3$ statistics remain identical to the undeformed network. On the other hand the $\Delta_3$ statistics is useful for the larger deformation strengths. Finally, we analyze the spectrum of a protein-protein interaction network for Helicobacter, and compare the spectral behavior with those of the model networks.Comment: accepted for publication in Phys. Rev. E (replaced with the final version

A novel amperometric catechol biosensor based on α-Fe2O3 nanocrystals-modified carbon paste electrode

In this work, we designed an amperometric catechol biosensor based on α-Fe2O3 nanocrystals (NCs) incorporated carbon-paste electrode. Laccase enzyme is then assembled onto the modified electrode surface to form a nanobiocomposite enhancing the electron transfer reactions at the enzyme’s active metal centers for catechol oxidation. The biosensor gave good sensitivity with a linear detection response in the range of 8–800 μM with limit of detection 4.28 μM. We successfully employed the sensor for real water sample analysis. The results illustrate that the metal oxide NCs have enormous potential in the construction of biosensors for sensitive determination of phenol derivatives

Characterisation of Schiff base and chromophore in green proteorhodopsin by solid-state NMR

The proteorhodopsin family consists of hundreds of homologous retinal containing membrane proteins found in bacteria in the photic zone of the oceans. They are colour tuned to their environment and act as light-driven proton pumps with a potential energetic and regulatory function. Precise structural details are still unknown. Here, the green proteorhodopsin variant has been selected for a chemical shift analysis of retinal and Schiff base by solid-state NMR. Our data show that the chromophore exists in mainly all-trans configuration in the proteorhodopsin ground state. The optical absorption maximum together with retinal and Schiff base chemical shifts indicate a strong interaction network between chromophore and opsin. © Springer Science+Business Media B.V. 2007

Histone deacetylase expression patterns in developing murine optic nerve

BACKGROUND: Histone deacetylases (HDACs) play important roles in glial cell development and in disease states within multiple regions of the central nervous system. However, little is known about HDAC expression or function within the optic nerve. As a first step in understanding the role of HDACs in optic nerve, this study examines the spatio-temporal expression patterns of methylated histone 3 (K9), acetylated histone 3 (K18), and HDACs 1–6 and 8–11 in the developing murine optic nerve head. RESULTS: Using RT-qPCR, western blot and immunofluorescence, three stages were analyzed: embryonic day 16 (E16), when astrocyte precursors are found in the optic stalk, postnatal day 5 (P5), when immature astrocytes and oligodendrocytes are found throughout the optic nerve, and P30, when optic nerve astrocytes and oligodendrocytes are mature. Acetylated and methylated histone H3 immunoreactivity was co-localized in the nuclei of most SOX2 positive glia within the optic nerve head and adjacent optic nerve at all developmental stages. HDACs 1–11 were expressed in the optic nerve glial cells at all three stages of optic nerve development in the mouse, but showed temporal differences in overall levels and subcellular localization. HDACs 1 and 2 were predominantly nuclear throughout optic nerve development and glial cell maturation. HDACs 3, 5, 6, 8, and 11 were predominantly cytoplasmic, but showed nuclear localization in at least one stage of optic nerve development. HDACs 4, 9 and10 were predominantly cytoplasmic, with little to no nuclear expression at any time during the developmental stages examined. CONCLUSIONS: Our results showing that HDACs 1, 2, 3, 5, 6, 8, and 11 were each localized to the nuclei of SOX2 positive glia at some stages of optic nerve development and maturation and extend previous reports of HDAC expression in the aging optic nerve. These HDACs are candidates for further research to understand how chromatin remodeling through acetylation, deacetylation and methylation contributes to glial development as well as their injury response

Class I histone deacetylases in retinal progenitors and differentiating ganglion cells

Background The acetylation state of histones has been used as an indicator of the developmental state of progenitor and differentiating cells. The goal of this study was to determine the nuclear localization patterns of Class I histone deacetylases (HDACs) in retinal progenitor cells (RPCs) and retinal ganglion cells (RGCs), as the first step in understanding their potential importance in cell fate determination within the murine retina. Results The only HDAC to label RPC nuclei at E16 and P5 was HDAC1. In contrast, there was generally increased nuclear localization of all Class I HDACs in differentiating RGCs. Between P5 and P30, SOX2 expression becomes restricted to Müller glial, cholinergic amacrine cells, and retinal astrocytes. Cholinergic amacrine showed a combination of changes in nuclear localization of Class I HDACs. Strikingly, although Müller glia and retinal astrocytes express many of the same genes, P30 Müller glial cells showed nuclear localization only of HDAC1, while retinal astrocytes were positive for HDACs 1, 2, and 3. Conclusion These results indicate there may be a role for one or more of the Class I HDACs in retinal cell type-specific differentiation

DARWIN CORE BASED DATA STREAMLINING WITH DigiMus 2.0

Cataloguing biological specimen is a important activity of biological museums world over. Software developed especially for this purpose have evolved overtime to achieve more accuracy in retrieving data from large and diverse datasets. Combining smaller datasets in to a larger information system requires uniformity of data based on a single data standard. In the developing world smaller datasets are maintained by individual researchers or small college and university groups. For standardizing data from such datasets, software needs to be developed, which require expertise and sufficient funds which are often unavailable. We present a simple open source web based tool developed using PHP to enable an individual with little or no knowledge of information systems or databases, to effectively streamline specimen data with data standard Darwin Core 1.2 ( DwC 1.2). Such data can then be shared and easily provided to larger datasets like Ocean Biogeographic Information Systems (OBIS) and Global Biodiversity Information Facility (GBIF). This tool can be accessed at http://www.niobioinformatics.in/digimus.php and its source code is freely available at http://www.niobioinformatics.in/digimus_source.ph

Severe flooding and cause-specific hospitalization in the United States

Flooding is one of the most disruptive and costliest climate-related disasters and presents an escalating threat to population health due to climate change and urbanization patterns. Previous studies have investigated the consequences of flood exposures on only a handful of health outcomes and focus on a single flood event or affected region. To address this gap, we conducted a nationwide, multi-decade analysis of the impacts of severe floods on a wide range of health outcomes in the United States by linking a novel satellite-based high-resolution flood exposure database with Medicare cause-specific hospitalization records over the period 2000- 2016. Using a self-matched study design with a distributed lag model, we examined how cause-specific hospitalization rates deviate from expected rates during and up to four weeks after severe flood exposure. Our results revealed that risk of hospitalization was consistently elevated during and for at least four weeks following severe flood exposure for nervous system diseases (3.5 %; 95 % confidence interval [CI]: 0.6 %, 6.4 %), skin and subcutaneous tissue diseases (3.4 %; 95 % CI: 0.3 %, 6.7 %), and injury and poisoning (1.5 %; 95 % CI: -0.07 %, 3.2 %). Increases in hospitalization rate for these causes, musculoskeletal system diseases, and mental health-related impacts varied based on proportion of Black residents in each ZIP Code. Our findings demonstrate the need for targeted preparedness strategies for hospital personnel before, during, and after severe flooding