Gamma ray spectra simulation and optimization in neutron activation analysis

A software package for the simulation of neutron activation spectra has been developed. The simulation of the 14 MeV neutron activation gamma ray spectra has been carried out both for cyclic and conventional modes. The simulation allows the prediction of the optimum parameters for a low level of detection. The parameters are irradiation, counting and decay times. The simulation was based on an accurate calculation of various parameters such as the photoelectric yield, detector efficiency and background estimation. Compton effect, single and double escape are also taken into account. This software was extensively tested using the IAEA certified material Sll lake sediment and AI(OH)3 chemical standard. A high agreement between the theoretical simulated spectra and those measured is obtained. The second part of the package implements the optimization of the timing parameters. The Monte Carlo method was used to search within a constrained time space for the optimum condition resulting in the lowest detection limit for a given reaction. In order to illustrate the validity of the optimisation routine, sodium is determined in SL1 using the reaction 23Na(n,u)20F

Autonomous Service Drones for Multimodal Detection and Monitoring of Archaeological Sites

Constant detection and monitoring of archaeological sites and objects have always been an important national goal for many countries. The early identification of changes is crucial to preventive conservation. Archaeologists have always considered using service drones to automate collecting data on and below the ground surface of archaeological sites, with cost and technical barriers being the main hurdles against the wide-scale deployment. Advances in thermal imaging, depth imaging, drones, and artificial intelligence have driven the cost down and improved the quality and volume of data collected and processed. This paper proposes an end-to-end framework for archaeological sites detection and monitoring using autonomous service drones. We mount RGB, depth, and thermal cameras on an autonomous drone for low-altitude data acquisition. To align and aggregate collected images, we propose two-stage multimodal depth-to-RGB and thermal-to-RGB mosaicking algorithms. We then apply detection algorithms to the stitched images to identify change regions and design a user interface to monitor these regions over time. Our results show we can create overlays of aligned thermal and depth data on RGB mosaics of archaeological sites. We tested our change detection algorithm and found it has a root mean square error of 0.04. To validate the proposed framework, we tested our thermal image stitching pipeline against state-of-the-art commercial software. We cost-effectively replicated its functionality while adding a new depth-based modality and created a user interface for temporally monitoring changes in multimodal views of archaeological sites

Analyse de la variabilité germinative de la vesce commune sous l’impact d’un stress Ferrique-Cadmique-Salin

Ce travail a pour but de voir l’impact de l’application d’une combinaison de stress abiotique sur la germination des graines de vesce commune ainsi que de visualiser les modifications physiologiques et histologiques au niveau des tissus racinaires sous l’influence de ces contraintes. De ce fait, une conduite de germination a été réalisée avec des graines de vesce commune dans différentes situations de combinaisons entre trois types de stress métallique-cadmique-salin et un suivi a été fait en se basant sur des caractères végétatifs bien déterminés. Les résultats montrent bien une nette différence entre les réponses des graines à l’application de stress séparément et entre les combinaisons de stress ainsi qu’une variabilité intra-espèce énorme vis-à-vis de différentes types de contraintes.Mots-clés : vesce commune, stress métallique-cadmique-salin, caractères végétatifs, modifications physiologiques et histologiques

Effects of water volume rates on spray deposition and control of tarnished plant bug [Hemiptera : Miridae] in strawberry crops

Des expériences ont été effectuées pour vérifier l'effet de trois volumes d'application de bouillie sur la couverture de fraisiers ( Fragaria ananassa: cultivars Kent et Chambly) et sur l'efficacité d'un insecticide contre la punaise terne ( Lygus lineolaris). Les expériences ont été réalisées à un taux constant de matière active pour des volumes de bouillie de 500 et 1500 L ha-1. La couverture des plants a été mesurée à l'aide d'un traceur fluorescent pour des volumes d'application de 500, 1000 et 1500 L ha-1 sur des échantillons pris au sol et sur différentes parties des plants. Les populations de punaise terne ont été évaluées 24 heures avant et après les traitements avec du malathion (4,5 kg m.a. ha-1) en utilisant 0, 500 et 1500 L ha-1. Les données normalisées pour un taux constant de matière active ont montré qu'une augmentation du volume de bouillie de 500 à 1500 L ha-1 n'avait généralement pas d'effet sur les quantités de traceur retrouvées. À quelques occasions, une augmentation du volume d'application a entraîné une baisse des quantités de traceur retrouvées, par exemple sur les feuilles du bas et du sommet du feuillage (Kent) et des sépales (Kent). Le contrôle des populations de punaise terne était acceptable sur le plan commercial à 500 et à 1500 L ha-1.Field experiments were performed on the effect of three volumes of application on spray deposition and insecticidal efficacy against the tarnished plant bug (Lygus lineolaris) in two strawberry (Fragaria ananassa) cultivars, Kent and Chambly. The rate of application of malathion was kept constant at 4.5 kg a.i. ha-1 for volumes of application of 500 and 1500 L ha-1. Plant coverage was measured using a fluorescent tracer applied at volumes of application of 500, 1000 and 1500 L ha-1. The tracer was recovered from samples taken from different plant locations and on the ground. Tarnished plant bug populations were evaluated 24 hours before and after insecticidal treatment. When coverage data were normalized for a fixed active ingredient rate, an increase in the volume of application from 500 to 1500 L ha-1 frequently had no effect on the amount of tracer recovered at the various locations. On some occasions, an increase in volume of application resulted in a decrease in the amount of tracer recovered, i.e. leaves at the top and bottom of the canopy (Kent), sepals (Kent). Tarnished plant bug population control was commercially acceptable at 500 and 1500 L ha-1

Modeling active electrolocation in weakly electric fish

In this paper, we provide a mathematical model for the electrolocation in weakly electric fishes. We first investigate the forward complex conductivity problem and derive the approximate boundary conditions on the skin of the fish. Then we provide a dipole approximation for small targets away from the fish. Based on this approximation, we obtain a non-iterative location search algorithm using multi-frequency measurements. We present numerical experiments to illustrate the performance and the stability of the proposed multi-frequency location search algorithm. Finally, in the case of disk- and ellipse-shaped targets, we provide a method to reconstruct separately the conductivity, the permittivity, and the size of the targets from multi-frequency measurements.Comment: 37 pages, 11 figure

Automated Archaeological Feature Detection Using Deep Learning on Optical UAV Imagery: Preliminary Results

This communication article provides a call for unmanned aerial vehicle (UAV) users in archaeology to make imagery data more publicly available while developing a new application to facilitate the use of a common deep learning algorithm (mask region-based convolutional neural network; Mask R-CNN) for instance segmentation. The intent is to provide specialists with a GUI-based tool that can apply annotation used for training for neural network models, enable training and development of segmentation models, and allow classification of imagery data to facilitate auto-discovery of features. The tool is generic and can be used for a variety of settings, although the tool was tested using datasets from the United Arab Emirates (UAE), Oman, Iran, Iraq, and Jordan. Current outputs suggest that trained data are able to help identify ruined structures, that is, structures such as burials, exposed building ruins, and other surface features that are in some degraded state. Additionally, qanat(s), or ancient underground channels having surface access holes, and mounded sites, which have distinctive hill-shaped features, are also identified. Other classes are also possible, and the tool helps users make their own training-based approach and feature identification classes. To improve accuracy, we strongly urge greater publication of UAV imagery data by projects using open journal publications and public repositories. This is something done in other fields with UAV data and is now needed in heritage and archaeology. Our tool is provided as part of the outputs given

Fluorescence Measurements of Aromatic Amino Acids in the Presence of Lipid Membranes

Amphiphilic peptides are capable of finding their way to, and occasionally through, cellular membranes using a mechanism that includes specific amino acid sequences. Physical measurements of amino acid-lipid interactions are of interest for a quantitative description of peptide affinities to biological membranes. In this study, we investigate small peptide-lipid interactions using the fluorescence of the aromatic amino acids tyrosine (Tyr), tryptophan (Trp) and phenylalanine (Phe). Reference spectra in deuterated isopropanol solutions are obtained to mimic hydrophobic environments and are used to quantify the interaction of Lys-Tyr-Lys, Trp-Gly, and Gly-Phe with 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) and palmitoyl-oleoyl phosphatidylserine (POPS) lipid membranes. These fluorescence data complement previously reported UV absorption data and have the advantage of eliminating background and scatter from solution. Together with NMR data, these results can be used to more fully characterize lipid-aromatic amino residue interactions