End-to-End Real-Time Demonstration of the Slotted, SDN-Controlled NEPHELE Optical Datacenter Network
PHOTONICS
Authors: Tokas, Konstantinos; Patronas, Giannis; Spatharakis, Christos; Bakopoulos, Paraskevas; Kyriakos, Angelos; Landi, Giada; Zahavi, Eitan; Christodoulopoulos, Kostas; Aziz, Muzzamil; Pitwon, Richard; Gallico, Domenico; Reisis, Dionysios; Varvarigos, Emmanouel; Avramopoulos, Hercules
Abstract
The NEPHELE hybrid electro-optical datacenter network (DCN) architecture is proposed as a dynamic network solution to provide high capacity, scalability, and cost efficiency in comparison to the existing DCN infrastructures. The details of the NEPHELE DCN architecture and its various key parts are introduced, and the performance of its implementation is evaluated through an end-to-end NEPHELE demonstrator, which was built at the National Technical University of Athens. Several communication scenarios are demonstrated in real time, exploiting a scalable optical data-plane architecture with a software-defined network (SDN) control plane capable of slotted operation for dynamic allocation of network resources. Real-time end-to-end functionality and integration of various software and hardware components are verified in a six-host prototype datacenter cluster.
Amino acid and acetylcholine chemistry in mountain beaver cochlear nucleus and comparisons to pocket gopher, other rodents, and cat
HEARING RESEARCH
Authors: Godfrey, Donald A.; Mikesell, Nikki L.; Godfrey, Timothy G.; Kaltenbach, James A.
Abstract
The mountain beaver and pocket gopher are two rodents that live mostly underground in tunnel systems. Previous studies have suggested that their cochlear nucleus structure, particularly that of the dorsal cochlear nucleus (DCN), differs significantly from that of other mammals, that the hearing ability of the pocket gopher is deficient compared to that of other rodents, and that the DCN of the mountain beaver is more responsive to slow oscillations of air pressure than to sounds. We conducted some electrophysiological recordings from mountain beaver DCN and then used microchemical methods to map in mountain beaver cochlear nuclei the distributions of amino acids, including the major neurotransmitters of the brain, and enzyme activities related to the metabolism of the neurotransmitter acetylcholine, which functions in centrifugal pathways to the cochlear nucleus. Similar measurements were made for a pocket gopher cochlear nucleus. Responses to tonal stimuli were found in mountain beaver DCN. Distributions and magnitudes of neurotransmitter and related amino acids within mountain beaver and pocket gopher cochlear nuclei were not very different from those of other rodents and cat. However, the enzyme of synthesis for acetylcholine, choline acetyltransferase, had only low activities in the DCN of both mountain beaver and pocket gopher. The chemical distributions in the mountain beaver DCN support a conclusion that it corresponds to just the superficial DCN portion of other mammals. High correlations between the concentrations of gamma-aminobutyrate (GABA) and glycine were found for both mountain beaver and pocket gopher cochlear nuclei, suggesting that their co-localization in cochlear nucleus synapses may be especially prominent in these animals. Previous evidence suggests convergence of somatosensory and auditory information in the DCN, and this may be especially true in animals spending most of their time underground. Our results suggest that the enlarged DCN of the mountain beaver and that of the pocket gopher are not very different from those of other rodents with respect to involvement of amino acid neurotransmitters, but they appear to have reduced cholinergic innervation. (C) 2019 Elsevier B.V. All rights reserved.