EIGEN: Ecologically-Inspired GENetic Approach for Neural Network Structure Searching from Scratch

Designing the structure of neural networks is considered one of the most challenging tasks in deep learning, especially when there is few prior knowledge about the task domain. In this paper, we propose an Ecologically-Inspired GENetic (EIGEN) approach that uses the concept of succession, extinction, mimicry, and gene duplication to search neural network structure from scratch with poorly initialized simple network and few constraints forced during the evolution, as we assume no prior knowledge about the task domain. Specifically, we first use primary succession to rapidly evolve a population of poorly initialized neural network structures into a more diverse population, followed by a secondary succession stage for fine-grained searching based on the networks from the primary succession. Extinction is applied in both stages to reduce computational cost. Mimicry is employed during the entire evolution process to help the inferior networks imitate the behavior of a superior network and gene duplication is utilized to duplicate the learned blocks of novel structures, both of which help to find better network structures. Experimental results show that our proposed approach can achieve similar or better performance compared to the existing genetic approaches with dramatically reduced computation cost. For example, the network discovered by our approach on CIFAR-100 dataset achieves 78.1% test accuracy under 120 GPU hours, compared to 77.0% test accuracy in more than 65, 536 GPU hours in [35].Comment: CVPR 201

Extended x-ray absorption fine structure study of porous GaSb formed by ion implantation

Porous GaSb has been formed by Ga ion implantation into crystalline GaSb substrates at either room temperature or −180 °C. The morphology has been characterized using scanning electron microscopy and the atomic structure was determined using extended x-ray absorption fine structure spectroscopy. Room-temperature implantation at low fluences leads to the formation of ∼20-nm voids though the material remains crystalline. Higher fluences cause the microstructure to evolve into a network of amorphous GaSb rods ∼15 nm in diameter. In contrast, implantation at −180 °C generates large, elongated voids but no rods. Upon exposure to air, the surface of the porous material is readily oxidized yielding Ga₂O₃ and metallic Sb precipitates, the latter resulting from the reduction of unstable Sb₂O₃. We consider and discuss the atomic-scale mechanisms potentially operative during the concurrent crystalline-to-amorphous and continuous-to-porous transformations

Neonatal exposure to monosodium glutamate results in dysmorphology of orofacial lower motor neurons

Glutamate is the most abundant excitatory neurotransmitter in the central nervous system, and is stored and released by both neurons and astrocytes. Despite the important role of glutamate as a neurotransmitter, high levels of extracellular glutamate can result in excitotoxicity and apoptosis. Monosodium glutamate (MSG) is a naturally occurring sodium salt of glutamic acid that is used as a flavour enhancer in many processed foods. Neonatal exposure to MSG has been shown to result in neurodegeneration in several forebrain regions, characterised by neuronal loss and neuroendocrine abnormalities. However, the brainstem effects of neonatal MSG exposure have not been investigated. It is therefore hypothesized that MSG exposure during the early postnatal period would impact brainstem lower motor neurons involved in feeding behaviour. The effect of neonatal MSG exposure on brainstem lower motor neurons was investigated by exposing rat pups to either 4 mg/g MSG or saline from postnatal day (P) 4 through 10. On P28, brains were preserved by vascular perfusion with fixative, frozen sectioned and stained for Nïssl substance. The number, size and shape of brainstem motor neurons were compared between MSG and saline-exposed animals. MSG exposure had no impact on the total number of neurons in the nuclei examined. However, MSG exposure was associated with a significant increase in the number of round somata in both the trigeminal and facial nuclei. Furthermore, MSG exposure resulted in significantly smaller neurons in all motor nuclei examined. These results suggest that neonatal exposure to MSG impacts the development of brainstem lower motor neurons which may impact feeding and swallowing behaviours in young animals.

Improving Mekong water resources investment and allocation choices

The CPWF Project PN67 “Improving Mekong Water Allocation” was a key, collaborative activity of the Mekong Program on Water, Environment and Resilience (M-POWER). The goal of contributing to water allocation policy and practice which results in a more optimal and equitable use of water by society has been pursued by research across the Mekong Region and active engagement with policymakers. The project team have examined the use of a wide range of decision-support tools, in many decision-making arenas. In doing so, they have sought to understand decision contexts and drivers