Le réseau relationnel de l’entreprise familiale : une ressource non négligeable pour sa performance

Les entreprises familiales bien qu’étant l’une des formes d’organisation les plus ancienne dans l’histoire économique (Gersick et al., 1997 ; Bienaymé, 2009) connaissent des difficultés dans leurs évolutions. Car en effet, entre disparitions et absorption par les grandes entreprises non familiales, on observe l’échec dans la transition à la seconde génération, taux de croissance faible, vulnérabilité et inertie dans la prise de décision, couts d’agence élevés (Lin et Hu, 2007 ; Litz, 2008 ; Lester et Cannella, 2006). Ces difficultés marquantes ainsi le point de réflexion de cette recherche pose ainsi le problème de la performance des entreprises familiale.  En vue de trouver des stratégies pour répondre à ces difficultés on se propose de recourir au réseau relationnel de l’entreprise familiale. L’objectif de cette étude est donc d’apprécier l’apport du réseau relationnel de l’entreprise familiale sur leur performance. Pour mener à bien cette recherche, nous avons opté pour une démarche quantitative. Les données recueillies à partir d’un questionnaire destiné aux dirigeants et cadres des entreprises familiales des villes de Bafoussam, Douala et Yaoundé, ont permis de collecter 94 questionnaires et soumettre aux différents analyses descriptives, factorielle et explicatives à l’aide du test de corrélation de Pearson et de régression linéaire multiple, ceci grâce aux au logiciel SPSS 20. Les principaux résultats nous permettent de faire mention d’une influence significative et positive du réseau relationnel de l’entreprise familiale sur la performance globale des entreprises familiale

Sorption behavior of four tropical woods using a dynamic vapor sorption standard analysis system

Sorption behavior of four tropical woods coming from Cameroon is studied using a Dynamic Vapor Sorption-Intrinsic apparatus. Sorption isotherms at 20°C and 40°C of Triplochiton scleroxylon (obeche), Entandrophragma cylindricum (sapele), Sterculia rhinopetala (lotofa) and Terminalia superba (frake also called limba) are compared to those in the literature with methods using saturated salts for lotofa and frake with satisfactory results. Experimental values are fitted using two sorption isotherm models. Sorption hysteresis is greatest in sapele and least in frake. When temperature increases, differences in the hysteresis of sorption among the woods decreases. Hystereses of all studied woods ranged from 0,5 to 3%. Our studied woods have lower equilibrium moisture content probably caused by the higher values of extractives content. The water sorbed molecules on multilayer during both adsorption and desorption at 20°C and 40°C is greater in the case of frake and lower in the case of lotofa. The water sorbed molecules on multilayer of sapele is greater than those of obeche. The predominance of multilayer over monolayer of our woods is from 0,2 to 0,4 relative humidity in adsorption phase, and from 0,3 to 0,4 relative humidity in desorption phase

Modeling and simulation of an industrial indirect solar dryer for Iroko wood (Chlorophora excelsa) in a tropical environment

This paper presents a modeling of an instrumental indirect solar wood dryer less expensive functioning in a Cameroonian climate applied to the climate of Yaoundé. The dryer is easy to build and electric energy is only used for the fan. Applications are done on Iroko wood (Chlorophora excelsa), a tropical wood 50mm thick most utilized in Africa. A satisfactory agreement between experimental and numerical results was found. Influences of thickness, wood initial water content and airflow rate were studied

Characterization of sorption behavior and mass transfer properties of four central africa tropical woods: Ayous, Sapele, Frake, Lotofa

This study provides the sorption isotherm, its hysteresis and their mass transfer properties of four Central Africa Tropical woods widely used for building construction: frake (Terminalia Superba), lotofa (Sterculia Rhinopetala), sapele (Entandrophragma Cylindricum) and ayous (Triplochiton Scleroxylon). Characterization of these four species in particular and Central Africa tropical woods in general were necessary to develop conservation and treatment of wood after first transformation using the drying. Also, moisture transport on wooden material used such as wall buildings can be facilitating to found the thermal comfort. Measurements of isotherms were performed using a dynamic vapor sorption apparatus (Surface Measurement Systems) at 20 and 40°C with air relative humidity ranged from 0% to 90%. Mass diffusivity was determined in steady state using a specific vaporimeter. Air permeability was determined using a specialized device developed to measure over a wide range of permeability values. Permeability and mass transfer properties were determined in the tangential direction with a ‘’false’’ quartersawn board (sapele and lotofa) and in the radial direction with a flatsawn board (ayous and frake). Samples of sapele, ayous and frake are heartwood when lotofa contains as well as heartwood than sapwood. Results obtained showed that the temperature effect on sorption behavior was quite low. We observed also a low difference between the sorption behavior of these different species and hysteresis of sorption decreases when temperature increases. Hailwood-Horrobin model’s explains plausibly the experimental sorption isotherms data. Results on characterization of mass transfer properties showed that, in the steady state, mass diffusivity decreases exponentially when basal density increases. Mass diffusivity was higher in desorption than in adsorption phase. The gaseous permeability of these species was between than those of Australian hardwoods and temperate woods. It was difficult to define a relationship between permeability and mass diffusivity

Comparison of teak wood properties according to forest management: short versus long rotation

Key message: Teak (Tectona grandis L.f.) is one of the most important tropical hardwood tree species, which is widely planted in Indonesia. Wood properties are strongly influenced by forest management conditioning further utilization of wood. Context: In Indonesia, teak wood has been supplied from the state forests (Perhutani) for long rotation teak and from community teak plantations for short rotation teak. Short rotation teak has been harvested at 7–10 years and long rotation teak at 40–60 years. Aims: This paper discusses the characterization of technical properties of short and long rotation teak wood based on the chemical, anatomical, physical, and mechanical properties. Methods: The properties of short rotation and long rotation teak woods were characterized by measuring their density, extractive contents, chemical composition, swelling, wettability, water sorption isotherm, decay resistance, anatomical properties, bending strength (modulus of rupture (MOR), modulus of elasticity (MOE)), and hardness. Results: The results indicate that short rotation teak was not particularly different in swelling, MOE and MOR, and Brinell hardness compared to long rotation teak, although it was less dense and less durable due to lower heartwood and extractive contents. Therefore, careful attention should be given to the use of short rotation teak in some wood-processing technologies. Conclusion: Lower wood density and durability of the short rotation compared to the long rotation teak will restrict its utilization to some extent for both indoor and outdoor applications. Fast-growing teak from community cannot be used as usual heartwood teak from Perhutani because of the very low proportion of useful heartwood in the stem

Characterization of thermally modified short and long rotation teaks and the effects on coatings performance

Many wood processing industries use short rotation teak, which has lower quality especially in durability and dimensional stability. Heat treatment is an eco-friendly method to improve dimensional stability and durability of wood. The objectives of the study were to investigate the effects of thermal modification on chemical composition, colour, dimensional stability and durability as well as coating’s performance after accelerated weathering of short and long rotation teak for exterior utilization. In this study, the samples were heated in oven at 220 °C for 20 h under nitrogen atmosphere. Results showed that independently of growth conditions teak woods underwent hemicelluloses degradation and an increase of lignin content after heat treatment. Extractives contents were lower in short rotation than in long rotation teak, and decreased in all cases after heat treatments. Dimensional stability was considerably improved as indicated by anti-swelling efficiency values of 64.9% and 58.9% for short and long rotation teak, respectively. Heated teak woods were more resistant against Trametes versicolor and the durability of short-rotation teak increased from moderate to very durable. Coatings on heat treated teaks had better bonding quality and better photo-stability when compared to unheated. Heated short rotation teak could be considered for exterior application

Motor ability and attention span among individuals dependent on illicit psychotropic drugs

Psychoactive substances act on the central nervous system producing mental and behavioral changes leading to clinical manifestations associated with drug abuse. Objective: To evaluate the motor ability and attention span among individuals dependent on psychotropic drugs, who were in treatment in a psychiatric hospital. Method: A single case study, whose unit of analysis was a hospital, assessed the motor skills and attention span of 10 male individuals addicted to illicit psychotropic drugs, with mean age of 31.9 ± 7.07 years and average hospitalization of 23.9 days. The following instruments were used: a structured socio-demographic interview, the Motor Scale for Elderly (EMTI) adapted, and the Trail Making Test (TMT A and B). The average age at first consumption was 15.1 years; and there was a slower performance in the TMT A and B in all age groups. In general motor ability, individuals were classified as follows: two “superior”, two “above average”, five “average”, and one “below average”. Results: Their temporal organization was the variable with the lowest performance. Conclusion: Attention deficits were encountered along with average general motor ability and a strong negative association or correlation between motor performance and attention span.As substâncias psicoativas atuam no sistema nervoso central produzindo alterações mentais e de comportamento levando a manifestações clínicas associadas ao uso abusivo de drogas. Objetivo: Avaliar a aptidão motora e a atenção em indivíduos dependentes de drogas psicotrópicas ilícitas, que se encontravam internados em Hospital Psiquiátrico. Método: Estudo de caso único, cuja unidade de análise foi uma unidade hospitalar, o qual avaliou a aptidão motora e a atenção em 10 indivíduos dependentes de drogas psicotrópicas ilícitas, do sexo masculino, com média de idade de 31,9 ± 7,07 anos e média de internação de 23,9 dias. Utilizados os seguintes instrumentos: entrevista estruturada sócio-demográfica e Escala Motora para Terceira Idade (EMTI) adaptada e Teste de Traços (TMT A e B). A idade média de início do consumo 15,1 anos; maior tempo de execução do TMT A e B em todas as faixas etárias. Resultados: Na aptidão motora geral os indivíduos foram classificados: dois como “superior”, dois “normal alto”, cinco “normal médio” e um “inferior”. A organização temporal foi a variável com desempenho mais baixo. Conclusão: Foi encontrado déficit na atenção, com média da aptidão motora geral normal e forte associação negativa ou correlação entre o desempenho motor e atenção

Differential limit on the extremely-high-energy cosmic neutrino flux in the presence of astrophysical background from nine years of IceCube data

We report a quasi-differential upper limit on the extremely-high-energy (EHE) neutrino flux above $5\times 10^{6}$ GeV based on an analysis of nine years of IceCube data. The astrophysical neutrino flux measured by IceCube extends to PeV energies, and it is a background flux when searching for an independent signal flux at higher energies, such as the cosmogenic neutrino signal. We have developed a new method to place robust limits on the EHE neutrino flux in the presence of an astrophysical background, whose spectrum has yet to be understood with high precision at PeV energies. A distinct event with a deposited energy above $10^{6}$ GeV was found in the new two-year sample, in addition to the one event previously found in the seven-year EHE neutrino search. These two events represent a neutrino flux that is incompatible with predictions for a cosmogenic neutrino flux and are considered to be an astrophysical background in the current study. The obtained limit is the most stringent to date in the energy range between $5 \times 10^{6}$ and $5 \times 10^{10}$ GeV. This result constrains neutrino models predicting a three-flavor neutrino flux of $E_\nu^2\phi_{\nu_e+\nu_\mu+\nu_\tau}\simeq2\times 10^{-8}\ {\rm GeV}/{\rm cm}^2\ \sec\ {\rm sr}$at$10^9\ {\rm GeV}$. A significant part of the parameter-space for EHE neutrino production scenarios assuming a proton-dominated composition of ultra-high-energy cosmic rays is excluded.Comment: The version accepted for publication in Physical Review