Abstract Purpose: The authors aim to examine the mean and volatility linkages between the gold market and the Latin American equity markets in the entire sample period and two crises periods, namely the US financial crisis and the Chinese crash. Design/methodology/approach: To examine the return and volatility spillovers, the authors employ VARBEKK-GARCH model on the daily data of four emerging Latin American equity markets which include Peru, Chile, Brazil and Mexico, which ranges from January 2000 to June 2018. Findings: The results show that the return transmissions vary across the stock markets and the crises periods. The volatility transmission is found to be bidirectional between the gold and stock markets of Brazil and Chile during the US financial crisis. Furthermore, the volatility spillover is unidirectional from Brazil to gold and from gold to Peru stock market during the Chinese crash. We also calculate the optimal weights hedge ratios for gold and stock portfolio. The result suggests that portfolio managers need to increase the weight of gold for the equity portfolios of Peru and Mexico during the US financial crisis. Furthermore, during the Chinese crisis, investors may raise the investment in gold for the equity portfolios of Brazil and Chile. Finally, the cheapest hedging strategy is CHIL/GOLD during the US financial crisis, whereas MEXI/GOLD during the Chinese crash. Practical implications: These findings have useful insights for portfolio diversification, asset pricing and risk management. Originality/value: The study’s outcome provides policymakers and investors with in-depth insights regarding hedging, risk management and portfolio management.

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RésuméObjectif Enquêter pour déterminer la concentration en chlore résiduel des approvisionnements en eau potable de plusieurs camps de réfugiés, au Sud Soudan, entre mars et avril 2013.Méthodes Pour chacun des trois camps de réfugiés étudiés, nous avons mesuré les caractéristiques physiques et chimiques des approvisionnements en eau, à quatre points de mesure à partir du point de distribution : (i) directement aux bornes-fontaines ; (ii) après la collecte ;(iii) après le transport jusqu'aux ménages ; et (iv) après plusieurs heures de stockage par les ménages. Les paramètres suivants ont été mesurés : chlore résiduel libre et chlore résiduel total, température, turbidité, pH, conductivité électrique et potentiel d'oxydoréduction. Nous avons documenté les pratiques de manipulation de l'eau à l'aide de contrôles par sondages et grâce aux auto-déclarations des personnes enquêtées. Nous avons analysé les facteurs affectant les concentrations en chlore résiduel à l'aide de modèles mathématiques et de régression linéaire.Résultats Pour des concentrations initiales en chlore résiduel libre comprises entre 0,5 et 1,5 mg/L, une vitesse de dégradation d'environ 5x10-3 L/mg/min a été observée dans tous les camps. Les modèles de régression ont montré que la dégradation du chlore résiduel était liée aux concentrations initiales en chlore, à la conductivité électrique et à la température de l'air. Le fait de couvrir les conteneurs de stockage de l'eau (mais aucune autre pratique en termes de manipulation de l'eau) a entraîné une amélioration des concentrations en chlore résiduel.Conclusion Les concentrations en chlore résiduel que nous avons mesurées dans les eaux approvisionnées dans les camps de réfugiés au Sud Soudan ont été trop faibles. En guise d'essai, nous recommandons d'élever la teneur en chlore résiduel préconisée à 1,0 mg/L dans toutes les situations, qu'il y ait une épidémie de maladies diarrhéiques ou pas et quels que soient le pH et la turbidité des eaux alimentées. D'après nos résultats, cela permettrait de garantir un taux de chlore résiduel libre de 0,2 mg/L pendant au moins 10 heures après la distribution. Néanmoins, nous ne savons pas si nos résultats sont généralisables à d'autres camps. D'autres études sont donc nécessaires.

AbstractObjective To investigate the concentration of residual chlorine in drinking water supplies in refugee camps, South Sudan, March-April 2013.Methods For each of three refugee camps, we measured physical and chemical characteristics of water supplies at four points after distribution: (i) directly from tapstands; (ii) after collection; (iii) after transport to households; and (iv) after several hours of household storage. The following parameters were measured: free and total residual chlorine, temperature, turbidity, pH, electrical conductivity and oxidation reduction potential. We documented water handling practices with spot checks and respondent self-reports. We analysed factors affecting residual chlorine concentrations using mathematical and linear regression models.Findings For initial free residual chlorine concentrations in the 0.5-1.5 mg/L range, a decay rate of ~5x10-3 L/mg/min was found across all camps. Regression models showed that the decay of residual chlorine was related to initial chlorine levels, electrical conductivity and air temperature. Covering water storage containers, but not other water handling practices, improved the residual chlorine levels.Conclusion The concentrations of residual chlorine that we measured in water supplies in refugee camps in South Sudan were too low. We tentatively recommend that the free residual chlorine guideline be increased to 1.0 mg/L in all situations, irrespective of diarrhoeal disease outbreaks and the pH or turbidity of water supplies. According to our findings, this would ensure a free residual chlorine level of 0.2 mg/L for at least 10 hours after distribution. However, it is unknown whether our findings are generalizable to other camps and further studies are therefore required.

ResumenObjetivo Investigar la concentración de cloro residual en los suministros de agua potable en los campos de refugiados de Sudán del Sur, entre marzo y abril de 2013.Métodos Para cada uno de los tres campos de refugiados, se midieron las características físicas y químicas de los suministros de agua en cuatro puntos después de la distribución: (i) directamente de las tomas de agua; (ii) después de la recogida; (iii) tras transportarla a los hogares; y (iv) tras varias horas de almacenaje en los hogares. Se midieron los siguientes parámetros: el cloro residual libre y total, la temperatura, la turbiedad, el pH, la conductividad eléctrica y el potencial de reducción de oxidación. Se documentaron las prácticas de tratamiento del agua con verificaciones y autoinformes de los encuestados. Se analizaron los factores que afectan a las concentraciones de cloro residual mediante modelos de regresión matemáticos y lineales.Resultados Para las concentraciones iniciales de cloro residual libre en el rango 0,5-1,5 mg/l, se encontró una tasa de depreciación de ~5x10-3 l/mg/min en todos los campos. Los modelos de regresión mostraron que la depreciación del cloro residual estaba relacionado con los niveles de cloro iniciales, la conductividad eléctrica y la temperatura ambiente. Los niveles de cloro residual mejoraron tras cubrir los contenedores de agua, pero no tras aplicar otras prácticas de tratamiento del agua.Conclusión Las concentraciones de cloro residual que se midieron en los suministros de agua en los campos de refugiados de Sudán del Sur eran demasiado bajas. Se recomendó provisionalmente que la directriz de cloro residual libre se incrementara a 1,0 mg/l en todas las situaciones, independientemente de los brotes de la enfermedad diarreica y del pH o la turbidez de los suministros de agua. De acuerdo con nuestros resultados, esto debería garantizar un nivel de cloro residual libre de 0,2 mg/l hasta al menos 10 horas después de la distribución. Sin embargo, no sabemos si nuestros resultados son generalizables a otros campos y, por lo tanto, se requieren más estudios.

Um mutante de Hemicola lanuginosa resistente a 2-deoxiglucose(M7) foi obtido através de exposição de conídios a raios γ, permitindo a expressão em caldo contendo 0,6% de 2-deoxiglucose (DG) e celobiose (1%) antes da semeadura em ágar DG esculina citrato de ferro amoniacal, da qual foram selecionadas as colônias com halo negro. Os parâmetros cinéticos para produção aumentada de ß-glucosidase (BGL) foram obtidos empregando-se sabugo de milho como fonte de carbono. A combinação de espiga de milho com água de maceração de milho foi a que forneceu os valores mais altos nos parâmetros cinéticos de formação de todos os produtos. O efeito da temperatura na cinética e atributos termodinâmicos da produção de BGL pelas cepas selvagem e M7 foi avaliado empregando-se processo de batelada em oito temperaturas diferentes in frascos em agitação. O melhor desempenho foi observado a 45ºC e 20g.l-1 de espiga de milho em 64h. Tanto a multiplicação quanto a formação do produto foram muito altas a 45ºC e ambas estavam ligadas em condições ótimas de trabalho. O rendimento de BGL produzido pelo mutante M7 (1556 U.g-1 de espiga seca) foi significativamente superior aos valores reportados para todos os sistemas fúngicos e bacterianos. A mutação influenciou a termoestabilização no microrganismo, sendo que o mutante necessitou de energia de ativação mais baixa para multiplicação e valores mais baixos de entalpia e entropia para a formação do produto quando comparado à cepa selvagem e a outros microrganismos mesofilicos e termotolerantes. Na fase de inativação, os microrganismos necessitaram valores mais baixos de energia de ativação, entalpia e entropia para o equilíbrio da formação de produto, confirmando a natureza termofílica da máquina metabólica do mutante.

A 2-deoxyglucose-resistant mutant (M7) of Humicola lanuginosa was obtained by exposing conidia to γ-rays and permitting expression in broth containing 0.6% 2-deoxyglucose (DG) and cellobiose (1%) before plating on DG esculin-ferric ammonium citrate agar medium from which colonies showing faster and bigger blackening zones were selected. Kinetic parameters for enhanced ß-glucosidase (BGL) synthesis by M7 were achieved when corncobs acted as the carbon source. The combination between corncobs and corn steep liquor was the best to support higher values of all product formation kinetic parameters. Effect of temperature on the kinetic and thermodynamic attributes of BGL production equilibrium in the wild organismand M7was studied using batch process at eight different temperatures in shake-flask studies. The best performance was found at 45ºC and 20 g L-1 corncobs in 64 h. Both growth and product formation (17.93 U mL-1) were remarkably high at 45ºC and both were coupled under optimum working conditions. Product yield of BGL from the mutant M7 (1556.5 U g-1 dry corncobs) was significantly higher than the values reported on all fungal and bacterial systems. Mutation had thermo-stabilization influence on the organism and mutant required lower activation energy for growth and lower magnitudes of enthalpy and entropy for product formation than those demanded by the wild organism, other mesophilic and thermo-tolerant organisms. In the inactivation phase, the organisms needed lower values of activation energy, enthalpy and entropy for product formation equilibrium, confirming thermophilic nature of metabolic network possessed by the mutant organism.