All-Optical Reinforcement Learning in Solitonic X-Junctions

L'etologia ha dimostrato che gruppi di animali o colonie possono eseguire calcoli complessi distribuendo semplici processi decisionali ai membri del gruppo. Ad esempio, le colonie di formiche possono ottimizzare le traiettorie verso il cibo eseguendo sia un rinforzo (o una cancellazione) delle tracce di feromone sia spostarsi da una traiettoria ad un'altra con feromone più forte. Questa procedura delle formiche possono essere implementati in un hardware fotonico per riprodurre l'elaborazione del segnale stigmergico. Presentiamo qui innovative giunzioni a X completamente integrate realizzate utilizzando guide d'onda solitoniche in grado di fornire entrambi i processi decisionali delle formiche. Le giunzioni a X proposte possono passare da comportamenti simmetrici (50/50) ad asimmetrici (80/20) utilizzando feedback ottici, cancellando i canali di uscita inutilizzati o rinforzando quelli usati.Ethology has shown that animal groups or colonies can perform complex calculation distributing simple decision-making processes to the group members. For example ant colonies can optimize the trajectories towards the food by performing both a reinforcement (or a cancellation) of the pheromone traces and a switch from one path to another with stronger pheromone. Such ant's processes can be implemented in a photonic hardware to reproduce stigmergic signal processing. We present innovative, completely integrated X-junctions realized using solitonic waveguides which can provide both ant's decision-making processes. The proposed X-junctions can switch from symmetric (50/50) to asymmetric behaviors (80/20) using optical feedbacks, vanishing unused output channels or reinforcing the used ones

Pathfinding by growth cones in the central nervous system of the grasshopper embryo

Journal ArticleIn the grasshopper embryo the morphological development of individually identified neurons can be traced prior to the onset of axonogenesis on through maturity (eg., Goodman and Spitzer, 1979). The behavior of individual growth cones can be characterized in their natural environment as they extend towards their targets

Guidance of neuronal growth cones: selective fasciculation in the grasshopper embryo

Journal ArticleOne of the central questions of developmental neurobiology concerns how the diversity and specificity of individual neurons are generated during embryonic development. One major component of neuronal diversity is the complex axonal morphology of individual neurons, largely generated early in development and intimately involved in the ability of neurons to find their correct synaptic targets

Pathfinding by neuronal growth cones in grasshopper embryos I. Divergent choices made by the growth cones of sibling neurons

Journal ArticleWe are interested in how the growth cones of identified neurons navigate in the central nervous system of the grasshopper embryo. The behavior of identified growth cones was observed as a function of developmental time by (i) periodically removing embryos from synchronized clutches of eggs and (ii) filling identified neurons in the central nervous system with the fluorescent dye Lucifer Yellow

A study of laser plasmas as X-ray sources in the 1-10 keV spectral region

An experimental investigation on X-ray emission from laser-produced plasmas is presented and the properties of such an emission of interest for application purposes are examined. Plasmas were generated by focusing 1 μm, 3 ns Nd laser pulses onto Al and Cu targets at an intensity of 1013 W/cm2. The temporal evolution of the emission and its spectral features were investigated by using an X-ray streak-camera and an X-ray photodiode. In the case of Cu targets, the analysis of the emission showed two spectral components. The main component was centered at ≈ 1.2 keV and a minor component, whose intensity was measured to be 10-3 of the previous component, was observed at ≈7 keV. The X-ray conversion efficiency, in the investigated spectral region, was measured to be 1% for Cu targets and 0.3% for Al targets

Pathfinding by neuronal growth cones in grasshopper embryo: III. Selective affinity of the G growth cone for the P cells within the A/P fascicle

Journal ArticleThe growth cone of the G neuron selectively fasciculates upon specific axon bundles in a stereotypic sequence as it navigates through the developing central nervous system of the grasshopper embryo. It turns and extends anteriorly in the contralateral neuropil of the second thoracic ganglion at a specific choice point where it fasciculates with the A/P axon bundle which contains the axons of the A1, A2, P1, and P2 neurons

Pathfinding by neuronal growth cones in grasshopper embryos: II. Selective fasciculation onto specific axonal pathways

Journal ArticleIn the previous paper (Raper, J. A., M. Bastiani, and C. S. Goodman (1983) J. Neurosci. 3: 20-30) we showed that the growth cones of two sibling neurons, the G and C cells, follow the same route in the developing grasshopper neuropil until they reach a stereotypic choice point. Here their growth cones diverge from each other as G turns and extends anteriorly and C turns and extends posteriorly. In this paper we show that the G and C growth cones fasciculate and extend in opposite directions upon a specific bundle of four axons

Pathfinding by neuronal growth cones in grasshopper embryos: IV. The effects of ablating the A and P axons upon the behavior of the G growth cone

Journal ArticleIn the companion paper (Bastiani, M. J., J. A. Raper, and C. S. Goodman (1984) J. Neurosci. 4: 2311-2328), we show that as the G growth cone reaches its choice point and turns anteriorly on the A/P fascicle, its filopodia demonstrate selective affinity for the A/P fascicle as compared to the other approximately 25 longitudinal axon fascicles, and within the A/P fascicle itself, G's filopodia selectively contact the P axons as compared to the A axons

GAMLSS: a distributional regression approach

A tutorial of the generalized additive models for location, scale and shape (GAMLSS) is given here using two examples. GAMLSS is a general framework for performing regression analysis where not only the location (e.g., the mean) of the distribution but also the scale and shape of the distribution can be modelled by explanatory variables

Caenorhabditis elegans Gα_q Regulates Egg-Laying Behavior via a PLCβ-Independent and Serotonin-Dependent Signaling Pathway and Likely Functions Both in the Nervous System and in Muscle

egl-30 encodes the single C. elegans ortholog of vertebrate Gα_q family members. We analyzed the expression pattern of EGL-30 and found that it is broadly expressed, with highest expression in the nervous system and in pharyngeal muscle. We isolated dominant, gain-of-function alleles of egl-30 as intragenic revertants of an egl-30reduction-of-function mutation. Using these gain-of-function mutants and existing reduction-of-function mutants, we examined the site and mode of action of EGL-30. On the basis of pharmacological analysis, it has been determined that egl-30 functions both in the nervous system and in the vulval muscles for egg-laying behavior. Genetic epistasis over mutations that eliminate detectable levels of serotonin reveals that egl-30requires serotonin to regulate egg laying. Furthermore, pharmacological response assays strongly suggest that EGL-30 may directly couple to a serotonin receptor to mediate egg laying. We also examined genetic interactions with mutations in the gene that encodes the single C. elegans homolog of PLCβ and mutations in genes that encode signaling molecules downstream of PLCβ. We conclude that PLCβ functions in parallel with egl-30 with respect to egg laying or is not the major effector of EGL-30. In contrast, PLCβ-mediated signaling is likely downstream of EGL-30 with respect to pharyngeal-pumping behavior. Our data indicate that there are multiple signaling pathways downstream of EGL-30 and that different pathways could predominate with respect to the regulation of different behaviors