Allometric relationships for predicting the stem volume of Acer monspessulanum and evaluation of NDVI values to estimate some stand parameters using Sentinel-2 satellite image

The objectives of this work are to evaluate allometric models for predicting stem volume and use NDVI index to estimate stand parameters of Acer monspessulanum, using Sentinel-2 images for the determination of NDVI index. Forty-nine (49) sample plots of 20 x 20 m were used as ground truth data and randomly split into two groups: 70% for fitting data and 30% for data validation. We determined 12 dendrometric characters and the spectral index NDVI for each tree. The heights of the trees varied between 2.2 and 10.8 m and the DBH (Diameter at Breast Height) varied between 0.15 and 1.2 m. The analyzed relationships were between: (i) individual stem volume and dendrometric parameters, (ii) individual tree NDVI and the dendrometric parameters and (iii) individual crown diameter and NDVI. The relationships were evaluated using ten allometric models. The regression study showed that the diameter and the height presented the robust relationship with tree volume in cubic and power models (R2=0.997). Power and cubic equations were also confirmed as good predictors using NDVI. With these models, we can estimate dendrometric parameters and predict tree volume. Keywords: Maple tree, NDVI, allometric model, dendrometric parameters, remote Sensin

Prevalence of infectious multi-drug resistant bacteria isolated from immunocompromised patients in Tunisia

Objectives: A retrospective study was conducted in the Bone Marrow Transplant Center of Tunisia during a period of 10 years (from 2002 to 2011) in order to report the prevalence of infectious multi-drug resistant bacteria.Methods: Bacterial identification was carried on the basis of biochemical characteristics and API identification systems. Antibiotic susceptibility was tested by disc diffusion method on Muller-Hinton agar.Results: During the study period, 34.5% of 142 Klebsiella pneumoniae strains and 11.46% of 218 Escherichia coli strains were extended-spectrum beta-lactamase (ESBL) producers. Also, 32.8% of 210 strains of Pseudomonas aeruginosa were imipenem and/or ceftazidime resistant and 20.75% of 106 strains of Staphylococcus aureus were methicillin resistant. A rising trend was observed for the prevalence of the selected multidrug resistant bacteria.Conclusion: These findings may have important clinical implications in prophylaxis and selection of antibiotic treatment. Continuous surveillance is needed, especially for onco-hematological patients.Keywords: Infectious multi-drug resistant bacteria, immunocompromised patients, Tunisia

Effets d’un stress hydrique modéré et de l’ombrage sur la survie, la croissance et l’allocation des ressources de deux provenances de Chêne-liège (Quercus suber L.)

Deux provenances (64 plants) de Chêne-liège (Quercus suber L.) originaires de l’Espagne et de la Tunisie ont été élevées sous deux niveaux d’intensité lumineuse (15 % (ombre modérée) et 5 % (ombre profonde) de pleine lumière) et deux régimes hydriques (plants irrigués à 100 % de la capacité au champ et plants soumis à un stress hydrique modéré) dans une pépinière en Espagne. Dix variables comprenant la survie des plants, la hauteur, le diamètre, le rapport hauteur/diamètre, les biomasses aérienne, souterraine et totale, le rapport biomasse tige/racine, le nombre et la longueur des unités de croissance ont été mesurées pour chaque provenance. Le taux de survie des plants a été de 89 % indépendamment des facteurs étudiés (provenance, lumière, régime hydrique). La hauteur des plants a été similaire pour les deux provenances, alors que leur diamètre a été significativement plus grand pour la provenance Espagnole. Le stress hydrique a affecté l’équilibre de croissance entre la hauteur et le diamètre des plants mais seulement pour la provenance Espagnole, alors que la lumière, et indépendamment de la provenance des plants, a affecté 80 % (8/10) des traits étudiés. Ainsi, la provenance Tunisienne a semblé plus tolérante au stress hydrique, alors qu’aucune des deux provenances n’a semblé plus tolérante que l’autre à l’ombrage. Cependant, lorsqu’on considère les deux facteurs, la provenance Espagnole a montré une plus grande capacité à s’acclimater au stress hydrique sous de faibles conditions lumineuses, ce qui lui confère ainsi un intérêt potentiel pour le reboisement puisqu’en conditions méditerranéennes, comme nos résultats le montrent, la lumière et le stress hydrique peuvent agir d’une façon conjuguée. Cette variabilité serait essentiellement de nature génétique, puisque les deux provenances ont été cultivées dans les mêmes conditions pédoclimatiques.Sixty-four plants of Cork oak (Quercus suber L.) originating from Spain and Tunisia provenances were grown under a combination of two light levels (15 % (moderate shade) versus 5 % (deep shade) of full-light) and two water regimes (well-watered versus moderate water stress) in a nursery in Spain. Ten response variables including seedling survival, height, diameter, height-to-diameter ratio, above- and below-ground biomass, total biomass, shoot-to-root ratio, number and length of growth unit were measured for each provenance. In average, seedling survival was 89 % and was independent of the studied factors (provenance, light, water regime). Seedling height was similar in both provenances, while diameter was significantly larger in the Spanish provenance. Water stress adversely affected the balance between height and diameter for the Spanish provenance, but not for the Tunisian provenance, while light, and independently of seedlings’ provenance, affected 80 % (8/10) of traits studied. Thus, the Tunisian provenance seemed to be more tolerant to water stress while none of both provenances seemed to be more tolerant to shade. However, when considering both factors the Spanish provenance showed a better seedlings’ acclimation to water stress under deep shade and may constitute accordingly a better material for afforestation as in Mediterranean conditions, as our results show, light and water stress may act in a coordinate manner. This variability would be mainly genetically controlled, as both provenances were cultivated under the same environmental conditions. Our results may be helpful in regeneration, cultivation and afforestation of cork oak

Effet du paillage et des abris-serres sur la survie et la croissance de plants de Chêne-liège (Quercus suber L.) durant quatre saison de croissance

Cinq modalités de paillage (Pin pignon, Lentisque, mélange de Pin pignon et de Lentisque (paillages organiques), gravier (paillage inorganique) et témoin), ainsi que trois modalités d’abris-serres (non aérés, aérés et témoins) ont été testées. Aucun des deux types d’abris-serres aéré et non aéré n’a eu d’effet significatif sur le taux de survie des plants, alors qu’ils ont significativement augmenté la croissance en hauteur moyenne des plants, par rapport au témoin, respectivement de 74-104 % et 93-106 % durant les quatre années. Contrairement à la croissance en hauteur, le diamètre moyen de la tige à la base des plants des abris-serres aéré et non-aéré a été significativement plus petit que celui du témoin, durant toute la période d’étude, respectivement de 23-31 % et 38-42 %. Les abris-serres ont significativement affecté le microclimat autour des plants par augmentation ou diminution de la température, de l’humidité relative et du déficit de pression de vapeur de l’air. Ils ont réduit, par ailleurs, le taux de photosynthèse, et donc la production en biomasse totale, en raison du faible niveau lumineux. L’augmentation de la largeur et l’aération des abris pourraient aider à diminuer la température et augmenter la transmission de la lumière, ce qui pourrait les rendre plus favorables à la croissance des plants. Le paillage n’a pas eu d’effet significatif sur la croissance des plants durant toute la période d’étude. L’utilisation combinée des abris-serres et du paillage n’a pas amélioré la croissance des plants.We evaluated the effect of mulching and tree shelters on survival and growth of planted Cork oak (Quercus suber L.) seedlings during four growing seasons. Five mulch types (Italian Stone Pine, Lentisk, and a combination of Italian Stone Pine and Lentisk (organic mulches), gravel (inorganic mulch) and no mulch) and three tree shelter types (non-vented, vented and control) were tested. Tree shelters did not have a significant effect on seedling survival rate during the study period, whereas both vented and non-vented shelters significantly increased seedling mean height during the four years by 74-104 % and 93-106 %, respectively, compared to unsheltered seedlings (control). Contrary to height growth, mean basal diameter in vented and non-vented shelters was significantly lower by 23-31 % and 38-42 %, respectively, than in controls in all the years. Tree shelters significantly affected the microclimate surrounding the seedlings by increasing/decreasing temperature, relative humidity and vapour pressure deficit. Both shelters reduced photosynthesis rate, and therefore total biomass, as a result of low light availability. Increasing shelter width and aeration may help to decrease temperature and increase light transmission, which could make shelters more conducive to seedling growth. Mulching had no significant effects on seedlings growth during the study. The combined use of mulching and tree shelters did not improve seedling growth

Simulation results of a 1 kW photovoltaic system with MPPT function in the inverter

Photovoltaic pumping systems are commonly used in remote regions, where the access to electrical energy is difficult or very expensive. This paper presents simulation results of a 1 kW photovoltaic system proposed in a cascade topology, consisting of a DC-DC boost converter followed by a single-phase inverter. The Maximum Power Point Tracking (MPPT) function is performed by the inverter, instead of by the DC-DC converter, as usually is done. The MPPT function uses an Incremental Conductance algorithm. This paper presents simulation results, in steady state and transient conditions, for the proposed photovoltaic system operating in different circumstances, which in real facilities can be caused by solar radiation variations.FEDER Funds - Operational Program for Competitiveness Factors (COMPETE), FCOMP-01-0124-FEDER-022674 and the project PTDC/EEA-EEL/104569/2008.Fundação para a Ciência e a Tecnologia (FCT) - FCOMP-01-0124-FEDER-022674, PTDC/EEA-EEL/104569/2008

Single phase NPC inverter controller with Integrated MPPT for PV grid connection

This paper presents a single-stage three-level Neutral Point Clamped (NPC) inverter for connection to the electrical power grid, with integrated Maximum Power Point Tracking (MPPT) algorithm to extract the maximum power available from solar photovoltaic (PV) panels. This single-stage topology is more compact than the traditional topology, it was chosen because with the proper control strategy. It is suitable to connect the PV panels to the power grid. The paper describes the design of a 5 kW NPC inverter for the interface of PV panels with the power grid, presenting the circuit parameters and the description of the control algorithms. A phase locked loop control is used to connect the inverter into the grid. Then, a proposed DC Link voltage control to regulate the input voltage of the inverter. Although an MPPT algorithm was used to optimize the energy extraction and the system efficiency. Inverter Output Current control to produce an output current (current injected in the power grid) with low Total Harmonic Distortion (THD) implemented in a DSP. Simulation and experimental results verify the correct operation of the proposed system, even with fluctuations in the solar radiation.info:eu-repo/semantics/publishedVersio

Modeling and thermal energy management in smart homes

In this paper, it is demonstrated the importance of the information concerning the power flow and the state of a building’s thermal system for the management and control of electricity consumption. The proposed approach is evaluated simulating the heating exchange behavior of a configurable base model for an isolated and non-thermally insulated habitat in order to determine the influence of the energy losses on the control system. Based on the results obtained with this study, some improvements were carried-out for the management system of the heating flow by introducing appropriated parameters into the control algorithm.- (undefined

Dynamique de la croissance juvénile du pin d'Alep (Pinus halepensis) sous deux techniques de reboisement dans la zone subhumide du Cap-Bon tunisien

Le comportement végétatif du pin d'Alep a été étudié pour deux techniques de plantations et deux types de sols sous des conditions climatiques méditerranéennes subhumides. Ces deux techniques comportent un défrichement identique du maquis avec la lame du bulldozer suivi pour la première par deux ripages choisis jusqu'à soixante centimètres de profondeur et pour la deuxième part un labour profond de quatre vingt dix centimètres à la charrue défonceuse et un nivellement des sillons avec la lame débroussailleuse du bulldozer

Essential oils of Origanum vulgare L. subsp glandulosum (Desf.) letswaart from Tunisia: chemical composition and antioxidant activity

BACKGROUND: Characterisation of the essential oils from O. glandulosum collected in three locations of Tunisia, chemical composition and the evaluation of their antioxidant activities were carried out. RESULTS: The essential oils from Origanum vulgare L. subsp. glandulosum (Desf.) letswaart collected from three localities of north Tunisia - Krib, Bargou and Nefza - were obtained in yields of 2.5, 3.0 and 4.6% (v/w), respectively. The essential oils were analysed by GC and GC/MS and assayed for their total phenolics content, by the Folin-Ciocalteu method, and antioxidant effectiveness, using the 2,2-diphenyl-1-picrylhydrazil (DPPH) radical scavenging assay. The main components of these essential oils, from Nefza, Bargou and Krib, were p-cymene (36%, 40% and 46%), thymol (32%, 39% and 18%), gamma-terpinene (24%, 12% and 16%) and carvacrol (2%, 2% and 15%), respectively). The ability to scavenge the DPPH radicals, expressed by IC50, ranged from 59 to 80 mg L-1. The total phenolic content, expressed in gallic acid equivalent (GAE) g kg(-1) dry weight, varied from 9.37 to 17.70 g kg(-1) dw. CONCLUSIONS: A correlation was identified between the total phenolic content of the essential oils and DPPH radical scavenger capacity. The occurrence of a p-cymene chemotype of O. glandulosum in the northern region of Tunisia is demonstrated

Perception of mental health and professional quality of life in Tunisian doctors during the COVID-19 pandemic: a descriptive cross-sectional study

Introduction: few research studies about mental health problems in medical staff during the first wave of the COVID-19 pandemic have been reported. The Aim of the study is to assess the prevalence of anxiety and insomnia, affecting the professional quality of life of physicians during COVID-19 pandemic. Methods: doctors answered an online questionnaire regarding their perception of insomnia, anxiety and professional quality of life during COVID-19 pandemic with psychological parameters including the Generalized Anxiety Disorder (GAD-7), Insomnia Severity Index (ISI) and Professional quality of life version 5 (ProQOL5). Results: anxiety was found in 64.8% of the participants. This disorder was respectively moderate and severe in 12.4% and 6.7% of cases. Insomnia was found in 51.4% of respondents, 29.5% of whom worked in the COVID circuit (p=0.17). Insomnia was assessed as mild, moderate and severe in respectively 38.1%, 11.4% and 1.9% of cases. Compassion satisfaction was moderate in 72.4 of cases and high in 24.8% of cases. The entire population with low CS belonged to the 20-29 age group (p=0.019). Compassion satisfaction was statistically higher in married people (32.7%) (p=0.004). This entity varied significantly with occupational grade (p=0.003), seniority in grade (p=0.011) and working in the private health sector (p=0.046). Burnout was moderate in 73.3% and low in 26.7% of cases. Burnout was significantly higher among single people (p=0.03) and statistically altered in the staff working in the COVID unit (p=0.028). Secondary traumatic disorder was above moderate in 69.6%. Conclusion: a high prevalence of psychological symptoms was found among doctors during COVID-19. Medical health workers are in need of health protection and adequate working conditions