A new algorithm and system for the extraction of delta-lognormal parameters

In this report, we present a new analytical method to estimate the parameters of Delta-lognormal functions. According to the Kinematic Theory of rapid human movements, these parameters contain information both on the motor commands and on the timing properties of a neuromuscular system. The new algorithm, called XZERO, exploits relationships between the zero crossings of the first and the second time-derivatives of a lognormal function and its four basic parameters. The methodology is described and evaluated in various testing conditions. Furthermore, for the first time, the extraction accuracy is quantified empirically, taking advantage of the exponential relationships that link the disperssion of the extraction errors with its signal to noise ratio. A new extraction system, which uses a benchmark of three estimation methods, is also proposed and evaluated in the mid-term perspective of developing machine intelligence applications that rely on lognormal functions

The convergence of a neuromuscular impulse response towards a lognormal, from theory to practice

Lognormal functions have been found among the best descriptors of the impulse response of neuromuscular systems under various experimental conditions. This arises from the fact that lognormal patterns automatically emerge when a large number of coupled systems interact to produce a response. This paper evaluates the error of convergence towards a lognormal. Under the umbrella of the Central Limit Theorem, the error functions for lognormal and delta-lognormal equations are derived and analyzed. It is shown that these errors can be computed from the estimated values of the lognormal parameters, without any explicit reference to the number of subsystems involved. The resulting theoretical framework is then exploited in three applications: the comparative benchmarking of parameter extraction algorithms, the validation of the results in analysis-by-synthesis experiments and the estimation of the range of acceptable movement times in tests involving rapid movements

Experimental observation of the proportional effect hypothesis of the kinematic theory : preliminary report

For more than ten years, the Kinematic Theory has been exploited successfully in applications dealing with handwriting processing. The theory uses Delta-Lognormal profiles to model the behaviors of the motor control and the neuromuscular system involved in the production of rapid movements. Its main underlying assumption is that the cumulative time delays of the propagated impulse responses, recorded along different points on a neuromuscular system are linked by proportional relationships. The study reported in this paper aims at using the physiological knowledge of the upper arm to deeply investigate this assumption. First, the concept of a subsystem is clarified and justified. Then, to observe the proportionality hypothesis, surface electromyographic signals (SEMG) recorded from the upper limb, during the execution of rapid handwriting movements, are analyzed. The results reveal proportional regressions, with strong correlation, between the cumulative time delays of the muscle activities, calculated from SEMG envelopes. This finding highlights the relationships that exist between the macro-delays observed on the SEMG bursts and constitutes an observation proof of the proportionality hypothesis. These developments add further support to the usefulness of the Kinematic Theory as a tool for the study and understanding of human movement

Système de synthèse de l'écriture manuscrite par l'utilisation du modèle Sigma-lognormal : bilan de la conception et documentation de l'application SIMSCRIPT

An application was built to simulate complex movements with the use of the sigmalognormal model. The theory used to conduct simulation is shortly described, the built application interface and the applications functionalities are shown and discussed. Finally some simulations results are compared with typical handwritten data acquired from a subject with the use of a digitizer

Neuronal Variability during Handwriting: Lognormal Distribution

We examined time-dependent statistical properties of electromyographic (EMG) signals recorded from intrinsic hand muscles during handwriting. Our analysis showed that trial-to-trial neuronal variability of EMG signals is well described by the lognormal distribution clearly distinguished from the Gaussian (normal) distribution. This finding indicates that EMG formation cannot be described by a conventional model where the signal is normally distributed because it is composed by summation of many random sources. We found that the variability of temporal parameters of handwriting - handwriting duration and response time - is also well described by a lognormal distribution. Although, the exact mechanism of lognormal statistics remains an open question, the results obtained should significantly impact experimental research, theoretical modeling and bioengineering applications of motor networks. In particular, our results suggest that accounting for lognormal distribution of EMGs can improve biomimetic systems that strive to reproduce EMG signals in artificial actuators

Potential of chitosan coating in delaying the postharvest anthracnose (Colletotrichum gloeosporioides Penz.) of Eksotika II papaya

The in vitro and in vivo fungicidal activity of chitosan was studied against Colletotrichum gloeosporioides, the causal agent of anthracnose in papaya fruits. Chitosan at 1.5% and 2.0% concentrations showed a fungistatic effect with 90–100% inhibition (significant at P ≤ 0.05) of the fungal mycelial growth. Changes in the conidial morphology were also observed with the higher chitosan concentrations after 7-h incubation. In vivo studies showed that 1.5% and 2.0% chitosan coatings on papaya not only controlled the fruit decay but also delayed the onset of disease symptoms by 3–4 weeks during 5 weeks storage at 12 ± 1°C and slowed down the subsequent disease development. However, when leaving the fruits to ripen at ambient temperature (28 ± 2°C), 2.0% chitosan was less effective than 1.5% in controlling the disease development. Chitosan coatings also delayed the ripening process by maintaining the firmness levels, soluble solids concentration and titratable acidity values during and after storage

Effect of an edible nanomultilayer coating by electrostatic self-assembly on the shelf life of fresh-cut mangoes

This work aims at evaluating the effect of an alginate-chitosan nanomultilayer coating, obtained by electrostatic layer-by-layer self-assembling, in the quality and shelf life of fresh-cut mangoes. Coated and uncoated fresh-cut mangoes were stored under refrigeration (8 °C) for 14 days. The changes in mass loss, titratable acidity, pH, ascorbic acid content, total soluble solids, malondialdehyde content, browning rate, and microbial count were evaluated during storage. At the end of the storage period, lower values of mass loss, pH, malondialdehyde content, browning rate, soluble solids, microorganisms proliferation, and higher titratable acidity were observed in the coated mangoes. The nanomultilayer coating did not improve the retention of vitamin C during storage of fresh-cut mangoes. Results suggest that chitosan-alginate nanomultilayer edible coating extends the shelf life of fresh-cut mangoes up to 8 days.Author Marthyna Pessoa de Souza thanks Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES/PDEE-Brazil) and Fundacao de Amparo a Ciencia e Tecnologia do Estado de Pernambuco (FACEPE, Brazil) for granting her scholarships. The authors thank the Fundacao para a Ciencia e a Tecnologia (FCT) Strategic Project PEst-OE/EQB/LA0023/2013 and the Project "BioInd-Biotechnology and Bioengineering for improved Industrial and Agro-Food processes", REF. NORTE-07-0124-FEDER-000028, co-funded by the Programa Operacional Regional do Norte (ON.2-O Novo Norte), QREN, and FEDER (Portugal)

Improving the storage of minimally processed mangoes (Mangifera indica L.) by hot water treatments and modified atmosphere packaging

La conservation des mangues 4ème gamme est limitée par le brunissement enzymatique et la perte de fermeté dus aux différentes opérations de transformation. Cette thèse propose un nouvelle approche pour améliorer la conservation de mangues 4ème gamme : l’application de traitements thermiques par immersion et/ou la conservation sous atmosphère modifiée : passive ou active (5% O2 – 5 % CO2) ou des enrobages (chitosane). Ce travail a permis tout d’abord de déterminer un couple température / temps optimal: 50 °C / 30 min qui permet de maintenir la qualité de plusieurs variétés de mangue (Keitt, Kent, Tommy Atkins). Les effets du traitement thermique sur l’intensité respiratoire, la couleur, la fermeté, les teneurs en antioxydants : vitamine C, caroténoïdes et phénols totaux, et sur l’activité de plusieurs enzymes (pour la fermeté : PME, PG, b-GAL ; et pour la couleur : PPO et PAL) ont été étudiés. Ces travaux ont montré que durant 9 jours à 6 °C, le traitement thermique maintient principalement la couleur par réduction de l’activité de la PPO et réduit la perte en fermeté par réduction de l’activité des enzymes pectolytiques (PME et b-GAL). Par ailleurs, les atmosphères modifiées semblent moins efficaces pour le maintien de la couleur et de la fermeté des mangues 4ème gamme. L’association du traitement 50°C/ 30 min avec une conservation sous atmosphère modifiée apporte peu d’effets additionnels et a même parfois un effet inhibiteurThe storage of fresh-cut mangoes is limited by the enzymatic browning and the loss of firmness due to the various operations of process. This work proposes a new approache to improve the storage of fresh-cut mangoes by: application of heat treatments by dipping with, or not, a storage under modified atmosphere: passive or active (5% O2 - 5% CO2) or using coatings (chitosane). The first step of this work was to determine the traitement 50 °C/30 min as an optimal treatment which maintian the quality of several varieties of mango (Keitt, Kent, Tommy Atkins). Effects of the heat treatment on the respiratory intensity, the color, firmness, the contents antioxydants: vitamin C, carotenoids and phenols total, and on the activity of several enzymes (PME, PG, b-GAL: for firmness; and PPO and PAL for colour changes) were studied. This work showed that during 9 days at 6 °C, the heat treatment maintains mainly the color by reduction of the activity of PPO and reduces the loss in firmness by reduction of the activity of the pectolytic enzymes (PME et b-GAL). In addition, the modified atmospheres seem less effective for the maintenance of the color and the firmness of freshcut mangoes. Combination of heat treatment with a modified atmosphere storage and have less additional effects and has even sometimes an inhibiting effec