Choice of the Empirical Definition of Zero in the Translog Multiproduct Cost Functional Form

This study examines the impacts of empirical definition of zero output values on price elasticities, economy of scope, and scale using the Translog cost function. A system of cost and factor share equations with regularity conditions imposed is estimated. Results show that the choice of default values affects policy recommendations.Research Methods/ Statistical Methods,

Combining indoor residual spraying with chlorfenapyr and long-lasting insecticidal bed nets for improved control of pyrethroid-resistant Anopheles gambiae: an experimental hut trial in Benin.

BACKGROUND: Neither indoor residual spraying (IRS) nor long-lasting insecticidal nets (LLINs) are able to fully interrupt transmission in holoendemic Africa as single interventions. The combining of IRS and LLINs presents an opportunity for improved control and management of pyrethroid resistance through the simultaneous presentation of unrelated insecticides. METHOD: Chlorfenapyr IRS and a pyrethroid-impregnated polyester LLIN (WHO approved) were tested separately and together in experimental huts in southern Benin against pyrethroid resistant Anopheles gambiae and Culex quinquefasciatus. The bed nets were deliberately holed with either six or 80 holes to examine the effect of increasing wear and tear on protectiveness. Anopheles gambiae were genotyped for the kdr gene to assess the combination's potential to prevent the selection of pyrethroid resistance. RESULTS: The frequency of kdr was 84%. The overall mortality rates of An. gambiae were 37% and 49% with the six-hole and 80-hole LLINs, respectively, and reached 57% with chlorfenapyr IRS. Overall mortality rates were significantly higher with the combination treatments (82-83%) than with the LLIN or IRS individual treatments. Blood feeding (mosquito biting) rates were lowest with the 6-hole LLIN (12%), intermediate with the 80-hole LLIN (32%) and highest with untreated nets (56% with the 6-hole and 54% with the 80-hole nets). Blood feeding (biting) rates and repellency of mosquitoes with the combination of LLIN and chlorfenapyr IRS showed significant improvement compared to the IRS treatment but did not differ from the LLIN treatments indicating that the LLINs were the primary agents of personal protection. The combination killed significantly higher proportions of Cx. quinquefasciatus (51%, 41%) than the LLIN (15%, 13%) or IRS (32%) treatments. CONCLUSION: The chlorfenapyr IRS component was largely responsible for controlling pyrethroid-resistant mosquitoes and the LLIN component was largely responsible for blood feeding inhibition and personal protection. Together, the combination shows potential to provide additional levels of transmission control and personal protection against pyrethroid-resistant mosquitoes, thereby justifying the additional resources required. Chlorfenapyr has potential to manage pyrethroid resistance in the context of an expanding LLIN/IRS strategy

Evaluation de quelques caractéristiques dendrométriques de trois clones d’Hevea brasiliensis Muell Arg. (PR 107, PB 86, GT 1)

L'Hevea brasiliensis Muell Arg. (Euphorbiaceae) est cultivé pour son latex dont on extrait le caoutchouc naturel. Cependant, l'hévéa peut être exploité comme bois d'oeuvre et d'énergie. Pour diversifier les produits tirés de cette espèce, une étude des caractéristiques dendrométriques et de quantification du volume de bois extractible par arbre a été conduite chez 3 clones (PR 107, PB 86 et GT 1), à Toupah au sud-est de la Côte d'Ivoire. Les résultats montrent qu'à l'exception de la hauteur et du volume de fût utile, les caractéristiques dendrométriques sont homogènes d'un clone à l'autre. Les arbres présentent un tronc cylindrique (Kf = 0,89 ± 0,02), se ramifient relativement haut (5,68 ± 0,51 m) et offrent ainsi une bonne partie de fût exploitable en bois d'oeuvre. Les vitesses de croissance continue en épaisseur (0,7 à 1cm an-1) conduisent à des diamètres acceptables de 40 à 45 cm, en fin de récolte de latex. Les volumes moyens extractibles par arbre sont de 0,464 ± 0,041 m3 en bois d'oeuvre, 0,519 ± 0,058 m3 en bois d'énergie et 0,983 ± 0,076 m3 en bois fort. Les clones d'hévéa présentent des caractéristiques dendrométriques comparables à celles des espèces de reboisement industriel.Hevea brasiliensis Muell Arg. (Euphorbiaceae) is grown for its latex from which is extracted natural rubber. However, rubberwood timber may be operated as lumber and wood energy. To diversify the products from this species, a study of dendrometric characteristics and quantification of extractable wood tree volume was conducted on 3 clones (PR 107, PB 86 and GT 1) at Toupah, south-east Côte d’Ivoire. Results show that, except for height and volume of useful drum, assessed characteristics were homogeneous from one clone to another. Trees show a cylindrical trunk (Kf = 0.89 ± 0.02), branch at relatively high level from the ground (5.68 ± 0.51 m), thus providing a important part of exploitable lumber drum. The rates of growth in thickness (0.7 to 1 cm yr-1) following late harvest of latex led to acceptable diameters of 40 to 45 cm. Extractable average volumes per tree were of 0,464 ± 0.041 m3 for lumber, 0,519 ± 0.058 m3 for fuelwood and 0,983 ± 0.076 m3 for strong wood. Rubber tree clones had dendrometric characteristics comparable to those of the industrial afforestation species.Keywords: Rubberwood, dendrometric charactristics, wood volume, Côte d’Ivoir

Measurement of overall insecticidal effects in experimental hut trials

BACKGROUND: The 'overall insecticidal effect' is a key measure used to evaluate public health pesticides for indoor use in experimental hut trials. It depends on the proportion of mosquitoes that are killed out of those that enter the treated hut, intrinsic mortality in the control hut, and the ratio of mosquitoes entering the treatment hut to those entering the control hut. This paper critically examines the way the effect is defined, and discusses how it can be used to infer effectiveness of intervention programmes. FINDINGS: The overall insecticidal effect, as defined by the World Health Organization in 2006, can be negative when deterrence from entering the treated hut is high, even if all mosquitoes that enter are killed, wrongly suggesting that the insecticide enhances mosquito survival. Also in the absence of deterrence, even if the insecticide kills all mosquitoes in the treatment hut, the insecticidal effect is less than 100%, unless intrinsic mortality is nil. A proposed alternative definition for the measurement of the overall insecticidal effect has the desirable range of 0 to 1 (100%), provided mortality among non-repelled mosquitoes in the treated hut is less than the corresponding mortality in the control hut. This definition can be built upon to formulate the coverage-dependent insecticidal effectiveness of an intervention programme. Coverage-dependent population protection against feeding can be formulated similarly. CONCLUSIONS: This paper shows that the 2006 recommended quantity for measuring the overall insecticidal effect is problematic, and proposes an alternative quantity with more desirable propertie

Dosage De Quelques Composantes Biochimiques Des Feuilles De Lippia multiflora (Verbenacee) a Deux Stades De Developpement Et Qualite Des Infusions, En Fonction De La Dose D’uree

Les feuilles de Lippia multiflora (verbénacée) récoltées simultanément sur des plantes d’un mois et demi et des plantes d’un an, cultivées sur des parcelles ayant reçu différentes doses d’urée ont été analysées. Les résultats indiquent que les feuilles des jeunes plantes ont un taux d’humidité élevé que celles des plantes adultes, surtout quand elles sont séchées à l’ombre. Elles sont plus riches en protéines (12 - 13 % MS) et en sucres totaux (0,013 - 0,015 % MS) avec une infusion plus astringente, plus colorée et plus parfumée. Les feuilles des plantes adultes par contre sont riches en glucides (≈ 0,6 % MS), en cellulose (≈ 0,85 % MS), en cendre (12 - 15 % MS) avec un taux d’humidité assez bas. Leur infusion est moins astringente, claire et moins parfumée. L’analyse de ces résultats révèle que les feuilles prélevées au stade d’un mois et demi sont de meilleures qualités organoleptiques à cause de leur richesse en protéine, en sucre totaux et surtout l’astringence, l’amertume et le parfum de leur infusion qui sont des critères d’appréciation du thé. Cependant, ces dernières seront conservées moins longtemps du fait de leur taux d’humidité élevés favorable à la croissance microbienne. Par ailleurs, la dose d’urée n’a pas eu d’effet significatif sur la composition chimique des feuilles et des infusions.The leaves of Lippia multiflora (verbenaceae) harvested at the same time on plants of one and a half month and the plants of one year cultivated on plots having accepted different doses of urea were analyzed. The results show that the leaves of the young plants have a well brought up rate of humidity that those of the adults plants, especially when they are dried in shade. They are richer in proteins (12 - 13 %) and in complete sugars (0.013 - 0.015 %) with a more astringent, more coloured and more sweet- scented infusion. The leaves of the adults plants are on the contrary rich in carbohydrates (0.6 %), in cellulose (0.85 %) and ash (12 - 15 %) with a low rate of humidity. Their infusion is less astringent, clear and less sweet- scented. The analysis of these results reveals that leaves taken at the stage of one and a half month are better quality because of their wealth in protein, in total sugar and especially the astringency, bitterness and the perfume of their infusion which are criteria of evaluation of tea. However, these last will be less kept for a long time because of to their hight humidity favourable to microbic growth. Moreover, the dose of urea did not have significant effect on the chemical composition of leaves and infusion. Keywords: Lippia multiflora, leaves, brewing, biochemical components, ure

In vitro antifungal activity of the soap formulation of the hexane leaf extract of morinda morindoides (morinda; rubiaceae)

Purpose: The aim of this study was to formulate the hexane extract of the leaves of Morinda morindoides (Baker) Milne-Redh (Rubiaceae) as soap and evaluate its antifungal activity against fungal isolates of human origin. Method: The hexane extract of Morinda morindoides was incorporated as an antifungal agent in soap (SMM) and tested against 4 strains of dermatophytes (Candida albicans, Trichophyton rubrum, Trichophyton mentagrophytes and Aspergillus fumigatus) using basic soap (BS) as control. Agar dilution method at serial concentrations ranging from 125 mg/ml to 3.9 mg/ml was used for the determination of the antimicrobial parameters - MIC (minimum inhibitory concentration) and IC50 (concentration producing 50 % inhibition) for these strains.Result: The growth of all fungal strains tested was inhibited by the Morinda morindoides extract soap (SMM) at MIC of 31.25 mg/ml. On the other hand, basic soap (control) inhibited Candida albicans at MIC of 125 mg/ml and at MIC of 62.50 mg/ml for the other 3 strains tested. Thus, SMM showed stronger antifungal activity against the strains tested than the control (basic soap). Conclusion: The hexane extract of Morinda morindoides leaves incorporated in soap exerted antifungal activity against the fungal strains tested. Thus, this soap formulation may find use in the treatment of dermatomycoses.Keywords: Morinda morindoides; Antifungal activity; Hexane extract; Soap; Dermatophyte