A perturbative approach to non-linearities in the information carried by a two layer neural network

We evaluate the mutual information between the input and the output of a two layer network in the case of a noisy and non-linear analogue channel. In the case where the non-linearity is small with respect to the variability in the noise, we derive an exact expression for the contribution to the mutual information given by the non-linear term in first order of perturbation theory. Finally we show how the calculation can be simplified by means of a diagrammatic expansion. Our results suggest that the use of perturbation theories applied to neural systems might give an insight on the contribution of non-linearities to the information transmission and in general to the neuronal dynamics.Comment: Accepted as a preprint of ICTP, Triest

Community supported agriculture farmers' perceptions of management benefits and drawbacks

Community Supported Agriculture (CSA) is a direct partnership between producer(s) and a group of consumers/members to share the risks and responsibilities of farming activities. CSA aims at producing and providing environmentally, socially, economically, and nutritionally sustainable food. Past research has focused on CSA members\u2019 motivations. This research aims to gain a better understanding of CSA farmers\u2019 perceived benefits and drawbacks in managing a CSA farm, and whether CSA management perception varies in dierent countries. The research collected data from 35 farmers that were based in the United States (US) and Hungary (HU). Data elaboration includes a one-way Anova test, Chi-square test, principal component analysis, and multiple multivariate linear regressions. The results support that US and HU farmers have similar positive perceptions of CSA farming management, especially in food quality, nutritional value products, environmental, and community benefits. The main dierences concentrate on economic, financial, and management perceptions. CSA success as an alternative agro-food production and distribution system relies on the capability to involve CSA members. Therefore, CSA farmers\u2019 management skills may evolve to ensure the performance of communication and community engaging practices. The main CSA concern is ensuring a fair income and living wage for the farmers and labor force. There is a need for better balancing non-monetary and monetary benefits for the farmers

Improved models of melting temperature and thermal conductivity for mixed oxide fuels doped with low minor actinide contents

Recycling and burning minor actinides (MA, e.g., americium, neptunium) in mixed-oxide (MOX) nuclear fuel is a strategic option for fast reactor concepts of Generation IV to improve the sustainability of nuclear energy by reducing ultimate radioactive waste and improving the exploitation of fuel resources. Thermal conductivity and melting temperature are fundamental properties of nuclear fuels, since they determine the fuel temperature profile and the melting safety margin, respectively and affect the overall fuel performance under irradiation. The available literature on thermal properties of Am or Np- containing MOX, both experimental data and models, is currently scarce. Moreover, state-of-the-art fuel performance codes (FPCs), e.g., GERMINAL and TRANSURANUS, do not account for the effects of minor actinides on MOX fuel properties. This deliverable presents the development and validation of original correlations for the thermal conductivity and melting temperature of minor actinide-bearing MOX (U,Pu,Am,Np)O2-x based on available literature data. These correlations are derived by extending those obtained in the project for U-Pu MOX fuels with the inclusion of the effect of Am and Np content, while preserving the physically- grounded formulation depending on the most relevant parameters. Ways to improve these correlations further in the future are also discussed

The puzzle of quasi prima \u2018almost before\u2019 and quasi dopo \u2018almost after\u2019

This paper focuses on a puzzling asymmetry which arises when the Italian approximative adverb quasi \u201ealmost\u201f modifies the temporal connectives prima \u201ebefore\u201f and dopo \u201eafter\u201f. By looking at naturally occurring data, we observe that A quasi prima che B \u201eA almost before B\u201f can be used to convey that an A-eventuality occurs early, only a little bit after a B-eventuality occurs. A sentence of the form A quasi dopo che B \u201eA almost after B\u201f, however, cannot be used to convey that an A-eventuality occurs late, only a little bit before a B-eventuality. We propose a solution for this puzzle that relies on an analysis of quasi as a scale-sensitive adverb and on an asymmetric semantic account of prima and dopo: prima has the meaning of the temporal comparative \u201eearlier\u201f, while dopo denotes a binary relation of temporal succession between events. We show that our account of quasi prima reveals a more general pattern of interpretation found when quasi modifies a comparative

Replica symmetric evaluation of the information transfer in a two-layer network in presence of continuous+discrete stimuli

In a previous report we have evaluated analytically the mutual information between the firing rates of N independent units and a set of multi-dimensional continuous+discrete stimuli, for a finite population size and in the limit of large noise. Here, we extend the analysis to the case of two interconnected populations, where input units activate output ones via gaussian weights and a threshold linear transfer function. We evaluate the information carried by a population of M output units, again about continuous+discrete correlates. The mutual information is evaluated solving saddle point equations under the assumption of replica symmetry, a method which, by taking into account only the term linear in N of the input information, is equivalent to assuming the noise to be large. Within this limitation, we analyze the dependence of the information on the ratio M/N, on the selectivity of the input units and on the level of the output noise. We show analytically, and confirm numerically, that in the limit of a linear transfer function and of a small ratio between output and input noise, the output information approaches asymptotically the information carried in input. Finally, we show that the information loss in output does not depend much on the structure of the stimulus, whether purely continuous, purely discrete or mixed, but only on the position of the threshold nonlinearity, and on the ratio between input and output noise.Comment: 19 pages, 4 figure

Pure hydrogen production by steam-iron process. The synergic effect of MnO2 and Fe2O3

In the energy transition from fossil to clean fuels, hydrogen plays a key role. Proton-exchange membrane fuel cells (PEMFCs) represent the most promising hydrogen application, but they require a pure hydrogen stream (CO < 10 ppm). The steam iron process represents a technology for the production of pure H2, exploiting iron redox cycles. If renewable reducing agents are used, the process can be considered completely green. In this context, bio-ethanol can be an interesting solution that is still not thoroughly explored. In this work, the use of ethanol as a reducing agent in the steam iron process will be investigated. Ethanol, at high temperature, decomposes mainly in syngas but can also form coke, which can compromise the process effectiveness, reacting with water and producing CO together with H2. In this work, the deposition of coke is avoided by controlling the duration of the reduction step; in fact, the data demonstrated that coke deposition is significantly dependent on reduction time. Tests were carried out in a fixed bed reactor using hematite (Fe2O3) as raw iron oxide adopting several reduction times (7 minutes-25 minutes), which correspond to different amount of ethanol fed (5 mmolC2H5OH/gFe2O3-17,95 mmolC2H5OH/gFe2O3). The effect of the addition of MnO2 to increase the reduction degree of iron oxides was explored using different amount of MnO2 (10 wt% and 40 wt% with respect to Fe2O3). The tests were performed at fixed temperatures of 675°C and atmospheric pressure. The optimization of the reduction time, in the chosen operating condition, performed only with Fe2O3, shows that, feeding an amount of 5 mmolC2H5OH/gFe2O3, coke deposition is avoided and, therefore, a pure H2 stream in oxidation is obtained. The addition of MnO2 leads to increased H2 yield and process efficiency, confirming its positive effect on the reduction degree of the solid bed. A reaction pathway to demonstrate the synergic effect of Fe2O3 and MnO2 in the reduction step was proposed in this article

Thyroid nodules treated with percutaneous radiofrequency thermal ablation: a comparative study

Percutaneous radiofrequency thermal ablation (RTA) was reported as an effective tool for the management of thyroid nodules (TNs). The aim of this study was to investigate the effects of RTA and to establish whether they were treatment-related by comparison with a matched, untreated control group