Brain responses to strong desire to void with synchronous urodynamics in healthy adults: a functional magnetic resonance imaging study based on graph theory

Background The alternations of brain responses to strong desire to void during a urodynamic study were unclear. The present study aims to identify the functional brain network's topologic property changes evoked by a strong desire to void in healthy male and female adults with synchronous urodynamics using a graph theory analysis. Methods The bladders of eleven healthy males and eleven females were filled with a catheter in a specific infusion and withdrawal pattern. The resting-state functional magnetic resonance imaging (fMRI) of the enrolled subjects was scanned under the empty bladder and strong desire to void states. Automated anatomical labeling (AAL) atlas was used to identify the ninety cortical and subcortical regions. Pearson's correlation calculations were performed to establish a brain connection matrix. A paired t-test (P < 0.05) and Bonferroni correction were applied to identify the significant statistical differences in topologic properties between the two states, including small-world network property parameters [gamma (γ) and lambda (λ)], characteristic path length (Lp), clustering coefficient (Cp), global efficiency (Eglob), local efficiency (Eloc) and regional nodal efficiency (Enodal). Results Significantly, a small-world network property was presented in all subjects. The significantly decreased Cp, Lp, Eloc, and increased Eglob were detected in the female subjects under the strong desire to void. Notably, the increased Enodal was observed in left the orbital part of middle frontal gyrus and inferior frontal gyrus, right middle temporal gyrus, median cingulate and middle occipital gyrus, and bilateral inferior parietal gyrus, gyrus rectus and supramarginal gyrus. In the male subjects, the increased Enodal presented in right frontal operculum and medial superior frontal gyrus, left supplementary motor area and the bilateral supramarginal gyrus. On the other hand, the significant decreased Enodal in female subjects was detected in the bilateral calcarine fissure and surrounding cortex, lingual gyrus, and fusiform gyrus. The decreased Enodal in male subjects presented in right inferior occipital gyrus and thalamus. Conclusions In the study, there were potential gender differences in functional brain network's topologic property alternations in response to the strong desire to void under a repetitive infusion and withdrawal pattern.

Pseudo-Darwinian evolution of physical flows in complex networks

The evolution of complex transport networks is investigated under three strategies of link removal: random, intentional attack and “Pseudo-Darwinian” strategy. At each evolution step and regarding the selected strategy, one removes either a randomly chosen link, or the link carrying the strongest flux, or the link with the weakest flux, respectively. We study how the network structure and the total flux between randomly chosen source and drain nodes evolve. We discover a universal power-law decrease of the total flux, followed by an abrupt transport collapse. The time of collapse is shown to be determined by the average number of links per node in the initial network, highlighting the importance of this network property for ensuring safe and robust transport against random failures, intentional attacks and maintenance cost optimizations.

Entanglement generation in a quantum network at distance-independent rate

We develop a protocol for entanglement generation in the quantum internet that allows a repeater node to use n-qubit Greenberger-Horne-Zeilinger (GHZ) projective measurements that can fuse n successfully-entangled links, i.e., two-qubit entangled Bell pairs shared across n network edges, incident at that node. Implementing n-fusion, for n≥3, is in principle not much harder than 2-fusions (Bell-basis measurements) in solid-state qubit memories. If we allow even 3-fusions at the nodes, we find---by developing a connection to a modified version of the site-bond percolation problem---that despite lossy (hence probabilistic) link-level entanglement generation, and probabilistic success of the fusion measurements at nodes, one can generate entanglement between end parties Alice and Bob at a rate that stays constant as the distance between them increases. We prove that this powerful network property is not possible to attain with any quantum networking protocol built with Bell measurements and multiplexing alone. We also design a two-party quantum key distribution protocol that converts the entangled states shared between two nodes into a shared secret, at a key generation rate that is independent of the distance between the two parties.

Network and Agent Dynamics with Evolving Protection against Systemic Risk

The dynamics of protection processes has been a fundamental challenge in systemic risk analysis. The conceptual principle and methodological techniques behind the mechanisms involved (in such dynamics) have been harder to grasp than researchers understood them to be. In this paper, we show how to construct a large variety of behaviors by applying a simple algorithm to networked agents, which could, conceivably, offer a straightforward way out of the complexity. The model starts with the probability that systemic risk spreads. Even in a very random social structure, the propagation of risk is guaranteed by an arbitrary network property of a set of elements. Despite intensive systemic risk, the potential of the absence of failure could also be driven when there has been a strong investment in protection through a heuristically evolved protection level. It is very interesting to discover that many applications are still seeking the mechanisms through which networked individuals build many of these protection processes or mechanisms based on fitness due to evolutionary drift. At the same time, this approach could be useful for researchers and those who need to use protection dynamics to guard against systemic risk under intrinsic randomness in artificial circumstances.