26 research outputs found
Perspective: Uniform switching of artificial synapses for large-scale neuromorphic arrays
No full textResistive random-access memories are promising analog synaptic devices for efficient bio-inspired neuromorphic computing arrays. Here we first describe working principles for phase-change random-access memory, oxide random-access memory, and conductive-bridging random-access memory for artificial synapses. These devices could allow for dense and efficient storage of analog synapse connections between CMOS neuron circuits. We also discuss challenges and opportunities for analog synaptic devices toward the goal of realizing passive neuromorphic computing arrays. Finally, we focus on reducing spatial and temporal variations, which is critical to experimentally realize powerful and efficient neuromorphic computing systems
SiGe epitaxial memory for neuromorphic computing with reproducible high performance based on engineered dislocations
No full textAlthough several types of architecture combining memory cells and transistors have been used to demonstrate artificial synaptic arrays, they usually present limited scalability and high power consumption. Transistor-free analog switching devices may overcome these limitations, yet the typical switching process they rely on-formation of filaments in an amorphous medium-is not easily controlled and hence hampers the spatial and temporal reproducibility of the performance. Here, we demonstrate analog resistive switching devices that possess desired characteristics for neuromorphic computing networks with minimal performance variations using a single-crystalline SiGe layer epitaxially grown on Si as a switching medium. Such epitaxial random access memories utilize threading dislocations in SiGe to confine metal filaments in a defined, one-dimensional channel. This confinement results in drastically enhanced switching uniformity and long retention/high endurance with a high analog on/off ratio. Simulations using the MNIST handwritten recognition data set prove that epitaxial random access memories can operate with an online learning accuracy of 95.1%.
Increased Excitatory Synaptic Transmission of Dentate Granule Neurons in Mice Lacking PSD-95-Interacting Adhesion Molecule Neph2/Kirrel3 during the Early Postnatal Period
No full textCopy number variants and point mutations of NEPH2 (also called KIRREL3) gene encoding an immunoglobulin (Ig) superfamily adhesion molecule have been linked to autism spectrum disorders, intellectual disability and neurocognitive delay associated with Jacobsen syndrome, but the physiological roles of Neph2 in the mammalian brain remain largely unknown. Neph2 is highly expressed in the dentate granule (DG) neurons of the hippocampus and is localized in both dendrites and axons. It was recently shown that Neph2 is required for the formation of mossy fiber filopodia, the axon terminal structure of DG neurons forming synapses with GABAergic neurons of CA3. In contrast, however, it is unknown whether Neph2 also has any roles in the postsynaptic compartments of DG neurons. We here report that, through its C-terminal PDZ domain-binding motif, Neph2 directly interacts with postsynaptic density (PSD)-95, an abundant excitatory postsynaptic scaffolding protein. Moreover, Neph2 protein is detected in the brain PSD fraction and interacts with PSD-95 in synaptosomal lysates. Functionally, loss of Neph2 in mice leads to age-specific defects in the synaptic connectivity of DG neurons. Specifically, Neph2−/− mice show significantly increased spontaneous excitatory synaptic events in DG neurons at postnatal week 2 when the endogenous Neph2 protein expression peaks, but show normal excitatory synaptic transmission at postnatal week 3. The evoked excitatory synaptic transmission and synaptic plasticity of medial perforant pathway (MPP)-DG synapses are also normal in Neph2−/− mice at postnatal week 3, further confirming the age-specific synaptic defects. Together, our results provide some evidence for the postsynaptic function of Neph2 in DG neurons during the early postnatal period, which might be implicated in neurodevelopmental and cognitive disorders caused by NEPH2 mutations.
Copyright © 2017 Roh, Choi, Cho, Choi, Park, Cutforth, Chung, Park, Lee, Kim, Lee,
Mo, Rhee, Kim, Ko, Choi, Bae, Shen, Kim and Han. This is an open-access article
distributed under the terms of the Creative Commons Attribution License (CC BY).
The use, distribution and reproduction in other forums is permitted, provided the
original author(s) or licensor are credited and that the original publication in this
journal is cited, in accordance with accepted academic practice. No use, distribution
or reproduction is permitted which does not comply with these terms.
© 2017 Roh, Choi, Cho, Choi, Park, Cutforth, Chung, Park, Lee, Kim, Lee,
Mo, Rhee, Kim, Ko, Choi, Bae, Shen, Kim and Han. This is an open-access article
distributed under the terms of the Creative Commons Attribution License (CC BY).
The use, distribution and reproduction in other forums is permitted, provided the
original author(s) or licensor are credited and that the original publication in this
journal is cited, in accordance with accepted academic practice. No use, distribution
or reproduction is permitted which does not comply with these terms.
Frontiers1321sciescopu
Sexually dimorphic behavior, neuronal activity, and gene expression in Chd8-mutant mice
No full textAutism spectrum disorders (ASDs) are four times more common in males than in females, but the underlying mechanisms are poorly understood. We characterized sexually dimorphic changes in mice carrying a heterozygous mutation in Chd8 (Chd8+/N2373K) that was first identified in human CHD8 (Asn2373LysfsX2), a strong ASD-risk gene that encodes a chromatin remodeler. Notably, although male mutant mice displayed a range of abnormal behaviors during pup, juvenile, and adult stages, including enhanced mother-seeking ultrasonic vocalization, enhanced attachment to reunited mothers, and isolation-induced self-grooming, their female counterparts do not. This behavioral divergence was associated with sexually dimorphic changes in neuronal activity, synaptic transmission, and transcriptomic profiles. Specifically, female mice displayed suppressed baseline neuronal excitation, enhanced inhibitory synaptic transmission and neuronal firing, and increased expression of genes associated with extracellular vesicles and the extracellular matrix. Our results suggest that a human CHD8 mutation leads to sexually dimorphic changes ranging from transcription to behavior in mice. © 2018, The Author(s
Comparison of <i>Enterococcus faecium</i> Bacteremic Isolates from Hematologic and Non-hematologic Patients: Differences in Antimicrobial Resistance and Molecular Characteristics
No full textFirst Case of Skin and Soft Tissue Infection Caused by <i>Mycoplasma hominis</i> in a Pediatric Immunocompromised Patient
No full textPerspective: Uniform switching of artificial synapses for large-scale neuromorphic arrays
No full textResistive random-Access memories are promising analog synaptic devices for efficient bio-inspired neuromorphic computing arrays. Here we first describe working principles for phase-change random-Access memory, oxide random-Access memory, and conductive-bridging random-Access memory for artificial synapses. These devices could allow for dense and efficient storage of analog synapse connections between CMOS neuron circuits. We also discuss challenges and opportunities for analog synaptic devices toward the goal of realizing passive neuromorphic computing arrays. Finally, we focus on reducing spatial and temporal variations, which is critical to experimentally realize powerful and efficient neuromorphic computing systems
Understanding children's active school commute, independent mobility, and physical activity in Austin, Texas, USA: Roles of physical environments
No full text© 2024 The Author(s) cc-by-nc-ndWalking to/from school (WTS) is an important form of habitual and healthful physical activity (PA). This cross-sectional study examined the multilevel correlates of WTS among elementary school children in Austin, Texas, and whether WTS and neighborhood environmental factors were associated with increased independent mobility and PA. A parent survey was conducted, and geographic information systems were used to calculate the shortest home-to-school distance. Binary logistic regressions were used to predict the outcomes. Distance, physical barriers (e.g., highway/freeway/busy roads), neighborhood environmental quality, and traffic concerns were significant predictors for WTS. Having a school within the neighborhood and unsupervised play increased the likelihood of independent travel to non-school destinations. Sidewalk availability and condition, having a friend's/relative's house in the neighborhood that the child visits frequently, and independent travel to non-school destinations predicted an increased likelihood of unsupervised outdoor play. Stranger danger reduced the likelihood of both independent travel and unsupervised play. Easy access to services and unsupervised play increased the likelihood of meeting PA guidelines. This study identified modifiable environmental predictors of WTS, independent mobility, and meeting PA guidelines. Future PA promotion should consider strategies that can encourage not only WTS but also independent travel to non-school destinations and unsupervised outdoor play
The Inbetweeners: The Korean Animation Industry Negotiates the Global and the National
No full textThis thesis examines the (South) Korean animation industry in between the global and the national. Since the 1990s, the Korean animation industry has tried to shift from being a subordinated ‘in-betweener’ (i.e. subcontracting for the USA and Japan) to becoming an autonomous agent (i.e. producing its own animations). What exactly initiated this change? Can it be perhaps understood as the response to the globalisation process? Or, can it be, in fact, Korea’s constantly contested nationalism under the guise of capital force of globalisation? How does this change our understanding of globalisation as process? More importantly, how do animators experience globalisation in their daily lives and work conditions?
To answer these questions, the thesis focuses on (1) how the local creative industry recognises and realises the dynamics between the global and national; (2) how the local creative producers experience negotiating local and global values in their daily lives and work. As Korea is a globally challenged nation with constantly contested national identity, the Korean animation industry is a potent site for examining ambivalent identity formation through these ‘in-between’ negotiation processes. People’s everyday experiences and ‘emotional’ struggles in-between the two major forces of nationalism and globalisation have been relatively neglected in research so far. This focus leads me to suggest the idea of ‘in-between’ not just as subcontracting but as a concept. In contrast to celebration of hybridity as ambivalence and/or resistance to both globalisation and nationalism, ‘in-betweeness’ captures the subjective experience generated from hybridity and realised through social and emotional tension in lived experiences and work. Being in-between is understood as a negotiation, transition and dis/juncture of different experiences of globalisation, along which Korean animators experience conflicts, dilemmas and confusion and hesitations about which direction to head in. It results in the creation of an ambivalent and often agonized in between identity
Evaluation of the BioFire Gastrointestinal Panel to Detect Diarrheal Pathogens in Pediatric Patients
No full textInfectious diarrhea is a global pediatric health concern; therefore, rapid and accurate detection of enteropathogens is vital. We evaluated the BioFire® FilmArray® Gastrointestinal (GI) Panel with that of comparator laboratory tests. Stool samples of pediatric patients with diarrhea were prospectively collected and tested. As a comparator method for bacteria, culture, conventional PCR for diarrheagenic E. coli, and Allplex GI-Bacteria(I) Assay were tested. For discrepancy analysis, BD MAX Enteric Bacterial Panel was used. As a comparator method for virus, BD MAX Enteric Virus Panel and immunochromatography was used and Allplex GI-Virus Assay was used for discrepancy analysis. The “true positive” was defined as culture-positive and/or positive results from more than two molecular tests. Of the 184 stool samples tested, 93 (50.5%) were true positive for 128 pathogens, and 31 (16.9%) were positive for multiple pathogens. The BioFire GI Panel detected 123 pathogens in 90 of samples. The BioFire GI Panel demonstrated a sensitivity of 100% for 12 targets and a specificity of >95% for 16 targets. The overall positive rate and multiple pathogen rate among patients in the group without underlying diseases were significantly higher than those in the group with hematologic disease (57.0% vs. 28.6% (p = 0.001) and 20.4% vs. 4.8% (p = 0.02), respectively). The BioFire GI Panel provides comprehensive results within 2 h and may be useful for the rapid identification of enteropathogens
