A caloritronics-based Mott neuristor

Machine learning imitates the basic features of biological neural networks to efficiently perform tasks such as pattern recognition. This has been mostly achieved at a software level, and a strong effort is currently being made to mimic neurons and synapses with hardware components, an approach known as neuromorphic computing. CMOS-based circuits have been used for this purpose, but they are non-scalable, limiting the device density and motivating the search for neuromorphic materials. While recent advances in resistive switching have provided a path to emulate synapses at the 10 nm scale, a scalable neuron analogue is yet to be found. Here, we show how heat transfer can be utilized to mimic neuron functionalities in Mott nanodevices. We use the Joule heating created by current spikes to trigger the insulator-to-metal transition in a biased VO2 nanogap. We show that thermal dynamics allow the implementation of the basic neuron functionalities: activity, leaky integrate-and-fire, volatility and rate coding. By using local temperature as the internal variable, we avoid the need of external capacitors, which reduces neuristor size by several orders of magnitude. This approach could enable neuromorphic hardware to take full advantage of the rapid advances in memristive synapses, allowing for much denser and complex neural networks. More generally, we show that heat dissipation is not always an undesirable effect: it can perform computing tasks if properly engineered

Faith and Justice: A Platonic Reading of Pauline Justification

Abstract This dissertation is a broad work of philosophical theology that examines the Christian Doctrine of Justification by Faith in light of the Platonic framework for constructing ethics. Prescinding from specific Post-Reformation debates on justification, it seeks to position the philosophic problem of justification in terms of Platonism’s preoccupation with human assimilation to the Divine. It sets out the rich background of Platonism in the Christian tradition, including the heavily monotheistic Middle-Platonism. Relying much on the work of Lloyd Gerson, it lays down a schema of how understand Platonic ethics and Platonism more generally; and draws on the work of George Van Kooten in discerning Platonic motifs in Paul. Through a reading of key Platonic dialogues, especially the Phaedrus, Symposium, and the Republic, the work discerns a schema of Platonic ethics as it relates to justification: the end of all human beings is likeness unto/harmonization with God, but this cannot happen without divine aid. Those who receive this divine aid, or ‘divine gift’ are philosophers, but the philosopher is no mere intellectual, but a lover of God, who lives by a kind of ‘faith that works by love’ (Gal 5:6). The philosopher is finally reconciled to God by the justification of his soul, which consists in the harmonization of his soul after the pattern of divine justice. This schema for Platonic ethics is used as a heuristic tool for exegesis of Romans 1-6, and Galatians 2-3, 5. In Romans, the attempt is made to reconcile language in Romans 2, which speaks of every man being rewarded for his works, who ‘perseveres in doing good’ (2:7), and in Romans 3, which commends justification by faith ‘apart from the law’ (3:21). Platonic concepts concerning the nature of the just soul are used to help clarify the meaning of Christian justification. Paul’s critique of the Law in Galatians is understood against the background of Platonic themes on the inadequacy of written law to provide a complete moral guide. In Galatians, it is understood that Pauline justification is never through faith alone, but specifically by a faith, given by the Spirit, that works by Love (Gal 5-6). The primacy which Platonic ethics gives to divine gift, as the primary author of our love of God, and our striving to see Him, is therefore shown to prefigure the Pauline doctrine of Justification, which, nevertheless, can only be fully understood in light of Christian revelation

Inverse proximity effect at superconductor-ferromagnet interfaces: Evidence for induced triplet pairing in the superconductor

Considerable evidence for proximity-induced triplet superconductivity on the ferromagnetic side of a superconductor-ferromagnet (S-F) interface now exists; however, the corresponding effect on the superconductor side has hardly been addressed. We have performed scanning tunneling spectroscopy measurements on NbN superconducting thin films proximity coupled to the half-metallic ferromagnet La2/3Ca1/3MnO3 (LCMO) as a function of magnetic field. We have found that at zero and low applied magnetic fields the tunneling spectra on NbN typically show an anomalous gap structure with suppressed coherence peaks and, in some cases, a zero-bias conductance peak. As the field increases to the magnetic saturation of LCMO where the magnetization is homogeneous, the spectra become more BCS-like and the critical temperature of the NbN increases, implying a reduced proximity effect. Our results therefore suggest that triplet-pairing correlations are also induced in the S side of an S-F bilayer.Comment: 12 pages, 3 figure

Notch and bone morphogenetic protein differentially act on dermomyotome cells to generate endothelium, smooth, and striated muscle

We address the mechanisms underlying generation of skeletal muscle, smooth muscle, and endothelium from epithelial progenitors in the dermomyotome. Lineage analysis shows that of all epithelial domains, the lateral region is the most prolific producer of smooth muscle and endothelium. Importantly, individual labeled lateral somitic cells give rise to only endothelial or mural cells (not both), and endothelial and mural cell differentiation is driven by distinct signaling systems. Notch activity is necessary for smooth muscle production while inhibiting striated muscle differentiation, yet it does not affect initial development of endothelial cells. On the other hand, bone morphogenetic protein signaling is required for endothelial cell differentiation and/or migration but inhibits striated muscle differentiation and fails to impact smooth muscle cell production. Hence, although different mechanisms are responsible for smooth muscle and endothelium generation, the choice to become smooth versus striated muscle depends on a single signaling system. Altogether, these findings underscore the spatial and temporal complexity of lineage diversification in an apparently homogeneous epithelium

Segregation of striated and smooth muscle lineages by a Notch-dependent regulatory network

Background: Lineage segregation from multipotent epithelia is a central theme in development and in adult stem cell plasticity. Previously, we demonstrated that striated and smooth muscle cells share a common progenitor within their epithelium of origin, the lateral domain of the somite-derived dermomyotome. However, what controls the segregation of these muscle subtypes remains unknown. We use this in vivo bifurcation of fates as an experimental model to uncover the underlying mechanisms of lineage diversification from bipotent progenitors. Results: Using the strength of spatio-temporally controlled gene missexpression in avian embryos, we report that Notch harbors distinct pro-smooth muscle activities depending on the duration of the signal; short periods prevent striated muscle development and extended periods, through Snail1, promote cell emigration from the dermomyotome towards a smooth muscle fate. Furthermore, we define a Muscle Regulatory Network, consisting of Id2, Id3, FoxC2 and Snail1, which acts in concert to promote smooth muscle by antagonizing the pro-myogenic activities of Myf5 and Pax7, which induce striated muscle fate. Notch and BMP closely regulate the network and reciprocally reinforce each other’s signal. In turn, components of the network strengthen Notch signaling, while Pax7 silences this signaling. These feedbacks augment the robustness and flexibility of the network regulating muscle subtype segregation. Conclusions: Our results demarcate the details of the Muscle Regulatory Network, underlying the segregation of muscle sublineages from the lateral dermomyotome, and exhibit how factors within the network promote the smooth muscle at the expense of the striated muscle fate. This network acts as an exemplar demonstrating how lineage segregation occurs within epithelial primordia by integrating inputs from competing factors