32 research outputs found

    Crowdequity and Crowdlending : two alternative funding solutions for entrepreneurial ventures. The case of the French firm Gifts for change

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    International audienceFinancial return crowdfunding (crowdlending and equity crowdfunding) has thrived in recent years. It is proposed as an alternative solution to the problem of funding entrepreneurial ventures. This research studies the advantages and drawbacks of financial return crowdfunding, compared with traditional funding. It highlights the special features of crowdlending and equity crowdfunding. The study is based on the case of the firm Gifts for Change - Treez, which is distinctive in that it was funded by both types of financial return crowdfunding. Our analysis shows that financial return crowdfunding uses different mechanisms that are only appropriate for certain projects. Thus, the choice between crowdlending and equity crowdfunding does not arise at the same stage of the firm's development. We also make several recommendations, based on our study, for entrepreneurs hoping to obtain funding via financial return crowdfunding

    A New Algorithm For Solving Isothermal Carbonization Of Wood Particle

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    A new algorithm based on the lattice Boltzmann method (LBM) is proposed as a potential solver for one-dimensional heat and mass transfer for isothermal carbonization of thick wood particles. To check the validity of this algorithm, computational results have been compared with the published data and a good agreement is obtained. Then, the model is used to study the effect of reactor temperature and particle size on the evolution of the local temperature and mass loss inside the wood particle

    Radiation heat transfer effect in solid oxide fuel cell: Application of the Lattice Boltzmann Method

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    the radiation effect within the solid anode, electrolyte, and cathode SOFC layers problem has been investigated in this paper. Energy equation is solved by the Lattice Boltzmann method (LBM). The Rosseland method is used to model the radiative transfer in the electrodes. The Schuster-Schwarzschild method is used to model the radiative transfer in the electrolyte. Without radiatve effect, the found results are in good agreement with those published. The obtained results show that the radiative effect can be neglected

    Effect of Previous Incubation of Aeromonas hydrophila in Wastewater Prior to Its Transfer Into Marine Water Microcosms

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    The occurrence of the mesophilic motile Gram negative non enterobacterial species A. hydrophila in the wild is a major problem that deserves to be resolved since it is a potentially pathogen able to enter into a non-culturable state on routine bacteriological plating media. These non-culturable forms can be detected by several direct or indirect visualization methods. This species has frequently been isolated from pathological forms in fish farming marine areas, especially near wastewater discharges. Consequently, we studied A. hydrophila in marine water microcosms placed during a 24 hour period in treated waste waters and compared with the homologous strain not placed in the same conditions. Thus, two kinds of microcosms were prepared using filtered and autoclaved marine water or waste water, inoculated by A. hydrophila and maintained at 25°C in darkness. The results obtained indicated that A. hydrophila population incubated at 25°C in marine water declined rapidly (3.21 log units in plate count number) during the first three days. Additionally, we noted that A. hydrophila incubated in marine water after a previous treatment in waste water declined progressively to 2.74 log units (in plate count number). Nevertheless, we showed no significant variations of the number of total bacterial cells for A. hydrophila developed in marine water after prior treatment in waste water, despite the appearance of the VBNC form. During this state, rods of normal size, elongated cells and cocci were obtained. Concomitantly, we determined several changes in biochemical and antimicrobial patterns of stressed A. hydrophila, notably the acquisition of adipate metabolization and an increase of resistance to antimicrobial compounds, especially for A. hydrophila incubated in marine water after treatment in waste water.A. hydrophila (mésophile, Gram négative, mobile) compte parmi les espèces non entérobactériennes opportunistes du milieu aquatique. Son isolement ou son dénombrement en milieu marin selon les méthodes classiques est compromis par l’acquisition de la forme viable non cultivable (VNC) chez la bactérie dont la visualisation repose sur des méthodes moins usuelles, notamment la cytométrie en image ou en flux. En pathologie aquacole, A. hydrophila compte parmi les espèces les plus fréquemment isolées, notamment dans les zones de rejets. Le présent travail a été effectué en vue d’étudier la survie d’A. hydrophila en eau de mer après transit en eaux usées domestique. Ainsi, deux types de microcosmes ont été utilisés, le premier rempli d’eau de mer filtrée, stérile et placé à 25 °C à l’obscurité; le second est rempli d’eau usée filtrée, stérile et placée pendant 24 h à l’obscurité avant transfert en eau de mer. Les caractéristiques intrinséques : cultivabilité, forme cellulaire, profils biochimiques et antibiotypiques ont été suivis au cours de ce stress. Les résultats obtenus indiquent que la cultivabilité d’A. hydrophila placée directement dans l’eau de mer diminue rapidement durant les trois premiers jours d’incubation (3,21 Ulog). Aussi, nous avons noté une réduction progressive de la cultivabilité d’A. hydrophila placée en eau de mer après transit en eaux usées (2,74 Ulog). Néanmoins, le nombre de cellules totales ne montre pas de variation significative tout le long de la période de suivi (30 jours), avec l’apparition de la forme Viable Non Cultivable (VNC). Au cours de ce stress, nous avons observé des cellules de formes bacillaires, allongées et arrondies réduites. Parallèlement, nous avons trouvé qu’A. hydrophila ayant séjourné en eau de mer (avec ou sans passage en eaux usées) a subi différentes modifications ayant porté aux caractéristiques biochimiques et antibiotypiques, dont les plus remarquables sont la capacité à métaboliser l’adipate et l’acquisition de nouvelles résistances aux antibiotiques, notamment après passage en eaux usées

    Potential of Rhizobia in Improving Nitrogen Fixation and Yields of Legumes

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    Strong demand for food requires specific efforts by researchers involved in the agricultural sector to develop means for sufficient production. While, agriculture today faces challenges such as soil fertility loss, climate change and increased attacks of pathogens and pests. The production of sufficient quantities in a sustainable and healthy farming system is based on environmentally friendly approaches such as the use of biofertilizers, biopesticides and the return of crop residues. The multiplicity of beneficial effects of soil microorganisms, particularly plant growth promotion (PGP), highlights the need to further strengthen the research and its use in modern agriculture. Rhizobia are considered as PGP comes in symbiosis with legumes taking advantage of nutrients from plant root exudates. When interacting with legumes, rhizobia help in increased plant growth through enriching nutrients by nitrogen fixation, solubilizing phosphates and producing phytohormones, and rhizobia can increase plants’ protection by influencing the production of metabolites, improve plant defense by triggering systemic resistance induced against pests and pathogens. In addition, rhizobia contain useful variations to tolerate abiotic stresses such as extreme temperatures, pH, salinity and drought. The search for rhizobium tolerant strains is expected to improve plant growth and yield, even under a combination of constraints. This chapter summarizes the use of rhizobia in agriculture and its benefits

    Biochemical analysis of induced resistance in chickpea against broomrape (Orobanche foetida) by rhizobia inoculation

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    This study examined the capacity of Rhizobium sp. strain PchAZM to reduce parasitism of chickpea by Orobanche foetida under greenhouse conditions, and assessed the relative impact of rhizobia on the expression of chickpea defense response against broomrape. Growth chamber experiments using Petri dishes revealed that rhizobia infection on chickpea roots reduced broomrape seed germination, and restricted the broomrape attachment to host roots while retarding tubercle formation and development by the parasite. In pot experiments, chickpea roots inoculated with rhizobia reduced the total number of broomrape by up to 90%. Broomrape necrosis was observed both before and after parasite attachment to inoculated chickpea roots in Petri dishes and pot experiments. Reduction in infection was accompanied by enhanced levels of the defence-related enzymes phenylalanine ammonia lyase (PAL) and peroxidase (POX). Increased levels of phenolics were recorded in the roots of rhizobia-inoculated plants grown in the presence of broomrape. The results suggest that rhizobia could be used for protection of chickpea against O. foetida

    Evaluation of Antibacterial Activity of Various Commercial Essential Oils

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    Essential oils and their components are becoming increasingly popular as naturally occurring antimicrobial agents. In this work the chemical composition and the antibacterial properties of the essential oils of rosemary (Rosmarinus officinalis), lemon (Citrus limonum), oregano (Corydothymus capitatus) and thyme (Thymus vulgaris) were determined. The essential oil components were identified by GC/MS analysis. The antibacterial activity of the oils was investigated in order to evaluate its efficacy against a panel of standard reference strains, using disc diffusion and minimum inhibitory concentration (MIC) methods. The GC/MS analysis showed that the major constituents of the oils were monoterpene hydrocarbons and phenolic monoterpenes, but the concentration of these compounds varied greatly among the oils examined. The results of the antibacterial assay showed that Corydothymus capitatus and Thymus vulgaris have the strongest antibacterial activity against all microorganisms tested. The MIC values obtained in the presence of Escherichia coli, Listeria monocytogenes, Staphylococcus aureus and Salmonella arizonae were ≤ 0.25% (v/v) for oregano and thyme essential oils

    Étude de l’influence des facteurs environnementaux sur la distribution de différentes populations bactériennes dans une station mytilicole de la lagune de Bizerte (Nord-Tunisie)

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    La présente étude a été effectuée en vue d’évaluer l’effet des fluctuations des paramètres abiotiques sur la distribution de différentes populations bactériennes viables dans la station mytilicole la plus productrice de la lagune de Bizerte (Nord‑Tunisie). Le suivi a été établi pendant une année (septembre 2004 ‑ août 2005) au niveau des neuf tables du site.Les dénombrements bactériens des coliformes totaux (CT), des entérocoques fécaux (EF), des Vibrionaceaes (VB) et des bactéries hétérotrophes cultivables (BHC) ont été effectués pour l’eau de surface, les moules (Mytilus galloprovincialis) ainsi que pour les sédiments. Ces charges bactériennes ont été corrélées à la température de l’eau, l’oxygène dissous, la salinité, le pH, la pluviométrie et l’ensoleillement, mesurés périodiquement en tout point du site.Le suivi des paramètres bactériologiques a révélé une présence assez importante de charges bactériennes pendant toute la période d’étude, notamment dans les moules et les sédiments, avec une distribution temporelle saisonnière. L’étude statistique a montré des corrélations positives, d’une part, entre les charges en polluants fécaux et la pluviométrie et, d’autre part, entre les charges en Vibrionaceaes et la salinité et la température.Ces résultats révèlent l’effet anthropique bactérien au niveau du site mytilicole : les rejets continentaux en hiver et la remontée des bactéries autochtones en période estivale ont une influence considérable sur la mytiliculture et son devenir dans la lagune de Bizerte.The present study aimed to assess the influence of abiotic parameters on the distribution of various viable bacterial populations in the most productive mussel farming area in the Bizerte Lagoon (Northern Tunisia). A monitoring survey was carried out over one year (September 2004 ‑ August 2005), within all the farming tables at the station. Bacterial enumerations of total coliforms (CT), fecal enterococci (EF), Vibrionaceae (VB) and cultivable heterotrophic bacteria (BHC) were carried out for surface water, mussels (Mytilus galloprovincialis) and sediments. These bacterial counts were correlated with water temperature, dissolved oxygen, salinity, pH, rainfall and sunshine, which were periodically measured at all points within the sampling area.The survey of the bacteriological parameters revealed high bacterial counts during the whole monitoring period, especially in the mussels and sediments, as well as seasonal variability. Statistical analyses revealed positive correlation between the loads of fecal pollutants and rainfall during the winter period, and between the loads of Vibrionaceae and salinity and temperature during the summer period.These results highlight the negative anthropogenic bacterial effect within the mussel farming areas: sewage discharges in winter, and the growth of autochthonous pathogenic bacteria during the summer period, have a considerable influence on the mussel culture in the Bizerte Lagoon

    Optimal timing of venture capital-backed IPO

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    International audienceThis paper investigates the optimal exit time for a venture capitalist (VC) through an initial public offering (IPO). We use a real options approach and develop a model based on the uncertainty of the VC-backed firm’s cash flows. We assume that the VC sells his stake in two stages, i.e., at the IPO date (taking underpricing into account) and at the expiration of the lock-up period. We find a closed-form solution of the threshold at which it is optimal for the VC to exit and determine the expected first hitting time. Our main results show that more risk averse VC brings firms public earlier even if firm’s cash flows are negative; the IPO is more rapid if the VC required rate of return and firm cash flows’ volatility are high. However, underpricing does not play an important role in the VC decision regarding exit timing

    Optimal timing of venture capital-backed IPO

    No full text
    International audienceThis paper investigates the optimal exit time for a venture capitalist (VC) through an initial public offering (IPO). We use a real options approach and develop a model based on the uncertainty of the VC-backed firm’s cash flows. We assume that the VC sells his stake in two stages, i.e., at the IPO date (taking underpricing into account) and at the expiration of the lock-up period. We find a closed-form solution of the threshold at which it is optimal for the VC to exit and determine the expected first hitting time. Our main results show that more risk averse VC brings firms public earlier even if firm’s cash flows are negative; the IPO is more rapid if the VC required rate of return and firm cash flows’ volatility are high. However, underpricing does not play an important role in the VC decision regarding exit timing
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