Sewer networks monitoring through a topological backtracking.

The interest in wastewater monitoring is always growing, with applications mainly aimed at detection of pollutants and at the environmental epidemiological surveillance. However, it often happens that the strategies proposed to manage these problems are inapplicable due to the lack of information on the hydraulics of the systems. To overcome this problem, the present paper develops and proposes a topological backtracking strategy for the optimal monitoring of sewer networks, which acts by subrogating the hydraulic information with the geometric ones, e.g., diameter and slope, thus not requiring any hydraulic simulation. The topological backtracking approach aims at evaluating an impact coefficient for each node of the network used to face with the problems of sensor location and network coverage for purposes related to the spread of contaminants and pathogens. Finally, the positioning of the sensors for each monitoring scheme is addressed by a priority rank, based on the efficiency of each sensor in terms of network coverage with respect to a specific weight (e.g., length, flow). The main goal is to design a monitoring scheme that provide the required coverage of the network by minimizing the number of sensors with respect to specific measurement threshold value. The results show the effectiveness of the strategy in supporting the optimal design with the topological-based backtracking approach without the necessity of performing hydraulic simulations, with great advantage in terms of required data and computational time.

Embedding the intrinsic relevance of vertices in network analysis: the case of centrality metrics.

Complex network theory (CNT) is gaining a lot of attention in the scientific community, due to its capability to model and interpret an impressive number of natural and anthropic phenomena. One of the most active CNT field concerns the evaluation of the centrality of vertices and edges in the network. Several metrics have been proposed, but all of them share a topological point of view, namely centrality descends from the local or global connectivity structure of the network. However, vertices can exhibit their own intrinsic relevance independent from topology; e.g., vertices representing strategic locations (e.g., hospitals, water and energy sources, etc.) or institutional roles (e.g., presidents, agencies, etc.). In these cases, the connectivity network structure and vertex intrinsic relevance mutually concur to define the centrality of vertices and edges. The purpose of this work is to embed the information about the intrinsic relevance of vertices into CNT tools to enhance the network analysis. We focus on the degree, closeness and betweenness metrics, being among the most used. Two examples, concerning a social (the historical Florence family's marriage network) and an infrastructure (a water supply system) network, demonstrate the effectiveness of the proposed relevance-embedding extension of the centrality metrics.

Methylphenidate administration determines enduring changes in neuroglial network in rats.

Repeated exposure to psychostimulant drugs induces complex molecular and structural modifications in discrete brain regions of the meso-cortico-limbic system. This structural remodeling is thought to underlie neurobehavioral adaptive responses. Administration to adolescent rats of methylphenidate (MPH), commonly used in attention deficit and hyperactivity disorder (ADHD), triggers alterations of reward-based behavior paralleled by persistent and plastic synaptic changes of neuronal and glial markers within key areas of the reward circuits. By immunohistochemistry, we observe a marked increase of glial fibrillary acidic protein (GFAP) and neuronal nitric oxide synthase (nNOS) expression and a down-regulation of glial glutamate transporter GLAST in dorso-lateral and ventro-medial striatum. Using electron microscopy, we find in the prefrontal cortex a significant reduction of the synaptic active zone length, paralleled by an increase of dendritic spines. We demonstrate that in limbic areas the MPH-induced reactive astrocytosis affects the glial glutamatergic uptake system that in turn could determine glutamate receptor sensitization. These processes could be sustained by NO production and synaptic rearrangement and contribute to MPH neuroglial induced rewiring.

Intrathecal NGF administration reduces reactive astrocytosis and changes neurotrophin receptors expression pattern in a rat model of neuropathic pain.

Nerve growth factor (NGF), an essential peptide for sensory neurons, seems to have opposite effects when administered peripherally or directly to the central nervous system. We investigated the effects of 7-days intrathecal (i.t.) infusion of NGF on neuronal and glial spinal markers relevant to neuropathic behavior induced by chronic constriction injury (CCI) of the sciatic nerve. Allodynic and hyperalgesic behaviors were investigated by Von Frey and thermal Plantar tests, respectively. NGF-treated animals showed reduced allodynia and thermal hyperalgesia, compared to control animals. We evaluated on lumbar spinal cord the expression of microglial (ED-1), astrocytic (GFAP and S-100beta), and C- and Adelta-fibers (SubP, IB-4 and Cb) markers. I.t. NGF treatment reduced reactive astrocytosis and the density of SubP, IB4 and Cb positive fibers in the dorsal horn of injured animals. Morphometric parameters of proximal sciatic nerve stump fibers and cells in DRG were also analyzed in CCI rats: myelin thickness was reduced and DRG neurons and satellite cells appeared hypertrophic. I.t. NGF treatment showed a beneficial effect in reversing these molecular and morphological alterations. Finally, we analyzed by immunohistochemistry the expression pattern of neurotrophin receptors TrkA, pTrkA, TrkB and p75(NTR). Substantial alterations in neurotrophin receptors expression were observed in the spinal cord of CCI and NGF-treated animals. Our results indicate that i.t. NGF administration reverses the neuro-glial morphomolecular changes occurring in neuropathic animals paralleled by alterations in neurotrophin receptors ratio, and suggest that NGF is effective in restoring homeostatic conditions in the spinal cord and maintaining analgesia in neuropathic pain.

Occurrence and neuroendocrine role of D-aspartic acid and N-methyl-D-aspartic acid in Ciona intestinalis.

Probes for the occurrence of endogenous D-aspartic acid (D-Asp) and N-methyl-D-aspartic acid (NMDA) in the neural complex and gonads of a protochordate, the ascidian Ciona intestinalis, have confirmed the presence of these two excitatory amino acids and their involvement in hormonal activity. A hormonal pathway similar to that which occurs in vertebrates has been discovered. In the cerebral ganglion D-Asp is synthesized from L-Asp by an aspartate racemase. Then, D-Asp is transferred through the blood stream into the neural gland where it gives rise to NMDA by means of an NMDA synthase. NMDA, in turn, passes from the neuronal gland into the gonads where it induces the synthesis and release of a gonadotropin-releasing hormone (GnRH). The GnRH in turn modulates the release and synthesis of testosterone and progesterone in the gonads, which are implicated in reproduction.