Stochastic trends in crop yield density estimation

The search for improved methods of estimating crop yield density functions has been a theme of recurrent research interest in agricultural economics. Crop yield density functions are the statistical instrument that generates probability estimates of yield risk, and risk is an important decision variable in production agriculture. Recent research in crop yield density estimation suggests that yield probability estimates can be sensitive to the way yield data are filtered, and if true, then the search for an “adequate filter” is warranted. Such a quest is pursued in this study. It is proposed that unit-root tests can be used to identify the time-series properties of yields and that the outcome of these tests makes the choice of an appropriate filter trivial. Once a filter has been chosen, then nonparametric methods can be used to more flexibly fit a crop yield density function. The study uses state and county level (aggregated) yield data for corn and soybeans in Arkansas and Louisiana for the period 1960-2008, comprising 121 yield series. The results identify three main types of yield processes (and filters), namely, a unit-root (first differences), a trend stationary process (detrending), and stationary (remove the mean). More specifically, the study finds that for Louisiana soybeans, for example, 73% of the county yields studied can be represented by a unit-root process, 12% followed a trend stationary process, and the remaining 15% were stationary. One important implication of this finding is that the use of a universal yield filter may generate inaccurate yield probability estimates, which translates into inaccurate estimates of crop insurance risk premia. To shed light into relevance of these findings, yield density functions were estimated under alternative filtering scenarios and pairwise probability estimates compared. In particular, the results suggest sizeable differences in the two estimates, which at times can reach -1,153.65%. In addition to providing a detailed analysis of the findings, the study assessed the relevance of the findings in the context of two current risk management programs, namely a group risk plan (GRP) and average crop revenue election (ACRE) program. Limitations of the study are also highlighted

Exchange Rate Volatility in BRICS Countries

This paper measures the impact of bilateral exchange rates, the world agricultural GDP and third-country exchange rate volatilities (Yen/USD and Euro/USD) on the BRICS agricultural exports using a vector autoregressive (VAR) model. Two measures of volatility are used: the standard deviation and the coefficient of variation of the rates of change of the real exchange rates. We found that most variables are integrated of order two except the third-country exchange rate volatilities which are stationary and thus considered as exogenous in the VAR models. The causality between I(2) variables was tested using the modified Wald test introduced by Toda and Yamamoto (1995). We found that both volatilities (Yen/USD and Euro/USD) Granger cause Brazilian agricultural exports and that the Yen/USD causes Chinese agricultural exports.BRICS, Currency Exchange Rate, Volatility, Trade, Agricultural Exports, U.S. Dollar, Risk, International Relations/Trade,

Energía: Desde un modelo de derroche, hacia un modelo sostenible mediante energía renovable

Energías renovables se relaciona a la concepción de desarrollo sostenible, que a su vez tiene que ver con los principios de conservar el capital natural, equidad, calidad de vida, paradoja ética, ecoforma, gestión integral, solidaridad inter e intrageneracional, utopía y agenda política global. Así mismo, su conexión con las dimensiones ambientales, demográficas, de consumo, global, local, tecno social y cultural. No se puede entender este paradigma sino se entiende primeramente el modelo capitalista consumista, en que está sumergida la sociedad desde la época de la revolución industrial. Este escrito analiza críticamente el rol de la ciencia, tecnología y energía en el ámbito mundial, vinculado al contexto latinoamericano en general y nicaragüense en particular. Se hace énfasis en las perspectivas de las energías renovables, propiamente en los sistemas a baja escala constituidos por tecnologías hibridas, como la eólico solar fotovoltaica para su uso en zonas rurales y urbanas

Impact of cross-fostering on the intestinal microbiome and mucosal immune gene expression in neonatal pigs

Colostrum is vital to the newborn pig. Hence, cross-fostering is employed to equalize the number of piglet between litters ensuring colostrum intake for their survival and growth. However, little is known about the impact of cross-fostering on the intestinal microbiome and mucosal immune gene expression of the neonatal pig. Twenty-four piglets were enrolled in the study to determine the influence of maternal microbial communities and to establish a baseline for mucosal immune gene expression in young pigs reared in cross-fostering model given high quality colostrum from birth dam or foster dam upon birth. Piglets were randomly assigned to 1 of 3 treatments according to colostrum source and postcolostral milk feeding for 21 days, as follow: treatment 1 (n = 8), received colostrum and post-colostral milk feeding from their own dam; treatment 2 (n = 8), received colostrum from foster dam and returned to their own dam for post-colostral milk feeding; and treatment 3 (n = 8), received colostrum and post-colostral milk feeding from foster dam. DNA was extracted from nasal, fecal, and gastrointestinal (GI) tract of the piglets and from colostrum, vaginal, and fecal samples of the sows. Tissues from intestinal mucosa in jejunum, ileum, colon, peyer’s patches, and associated lymph nodes were utilized. Quantitative real-time PCR analysis was performed to quantify the expression of toll-like receptors (TLR) 2, 4, and 10, tumor necrosis factor alpha (TNFα), interferon gamma (IFNγ), and interleukin (IL) 4 and 10. Discriminant analysis revealed that bacterial communities varied with biogeographical location in the GI tract, with colon being the most diverse section. Firmicutes and Bacteroidetes were the dominant phyla in the GI tract of the young pig. Bacterial communities in both maternal colostrum and vaginal samples were significantly associated with those present in the GI tract, feces, and nasal passage of piglets. Treatment did not affect bacterial communities present in the piglet GI tract, however, the bacterial communities present in piglet fecal and nasal samples changed over time. The mRNA expression of TLRs and inflammatory cytokines changed (P < 0.05) with biogeographical location in the GI tract. Higher mRNA expression of TLRs and inflammatory cytokines was observed in ileum, ileum lymph nodes and peyer’s patches tissues. Although cross-fostering did not impact microbial communities in the piglet, this study suggests an impact of colostrum and maternal influence on the development of the microbiome of the piglet. This study revealed novel information about the distribution and expression patterns of TLRs and inflammatory cytokines in the GI tract of the young pig

Modelling and data validation for the energy analysis of absorption refrigeration systems

Data validation and reconciliation techniques have been extensively used in the process industry to improve the data accuracy. These techniques exploit the redundancy in the measurements in order to obtain a set of adjusted measurements that satisfy the plant model. Nevertheless, not many applications deal with closed cycles with complex connectivity and recycle loops, as in absorption refrigeration cycles. This thesis proposes a methodology for the steady-state data validation of absorption refrigeration systems. This methodology includes the identification of steady-state, resolution of the data reconciliation and parameter estimation problems and the detection and elimination of gross errors. The methodology developed through this thesis will be useful for generating a set of coherent measurements and operation parameters of an absorption chiller for downstream applications: performance calculation, development of empirical models, optimisation, etc. The methodology is demonstrated using experimental data of different types of absorption refrigeration systems with different levels of redundancy.Los procedimientos de validación y reconciliación de datos se han utilizado en la industria de procesos para mejorar la precisión de los datos. Estos procedimientos aprovechan la redundancia enlas mediciones para obtener un conjunto de datos ajustados que satisfacen el modelo de la planta. Sin embargo, no hay muchas aplicaciones que traten con ciclos cerrados, y configuraciones complejas, como los ciclos de refrigeración por absorción. Esta tesis propone una metodología para la validación de datos en estado estacionario de enfriadoras de absorción. Estametodología incluye la identificación del estado estacionario, la resolución de los problemas de reconciliación de datos y estimación de parámetrosy la detección de errores sistemáticos. Esta metodología será útil para generar un conjunto de medidas coherentes para aplicaciones como: cálculo de prestaciones, desarrollo de modelos empíricos, optimización, etc. La metodología es demostrada utilizando datos experimentales de diferentes enfriadoras de absorción, con diferentes niveles de redundancia

Síntomas y factores de riesgo músculo esqueléticos en extremidades superiores, presentes en las trabajadoras de una industria de alimentos. Managua, Nicaragua. Abril a Mayo 2015.

Se encontró que el 100% de las trabajadoras presentan molestias músculo esquelético, siendo su principal molestia el dolor. De los factores de riesgos músculo esqueléticos el 96.4% realizan movimientos repetitivos de miembro superior, mantienen posturas forzadas siendo las más frecuentes la flexión de cuello entre 10 a 200 en el 66.9%, flexión de brazo o extensión de 20 a 900 95.5%, flexión de la muñeca menor de 150 en el 75% asociado a rotación en el 60.7%. En relación al tipo de agarre se encontró que el 59.8% es cómodo, el 40.1% es incómodo con fuerza. Los sitios anatómicos más afectados es el hombro y cuello, la intensidad del dolor es moderada, el 41% ha presentado incapacidad laboral y el 43.7% ha necesitado cambiar de puesto de trabajo a causa de las molestias, el 80.3% ha tenido molestias en los últimos 7 días

Exchange Rate Volatility Effects on BRICS Countries Exports

The leaders of the leading emerging economies Brazil, Russia, India, China, and South Africa (BRICS) claim that increased currency exchange rate volatility (CERV) from USD, EUR, and JPY (G-3) negatively impacts their exports, and expressed their desire for less trade dependence on these currencies. The literature on the impact of CERV on trade is vast. However, no consensus on the impact’s direction and significance has been reached yet. The motivation of this study was: first, to contribute to the existing empirical literature by using an alternative methodology; and second, to provide empirical evidence to the claim’s validity or nullity by focusing on the case of BRICS, Turkey and Honduras. To this end, two general null hypotheses (objectives) were tested: 1) Unconditional (constant) CERV does not Granger cause exports, and 2) Conditional (stochastic) CERV does not impact exports. To achieve the first objective, an export demand model was specified as a VAR dynamic system of exports, World GDP, relative prices, and own or third CERV. Quarterly time-series from 1973 to 2013 were used. Using a battery of unit root tests, including the latest developments, different orders of integration were identified. Therefore, to test this hypothesis it was opted for the Toda Yamamoto, and Dolado and Lütkepohl procedure. It consists in estimating an augmented VAR and test for Granger non-causality using MWald tests. In total 84 models were estimated. To accomplish the second objective, Bivariate VAR-GARCH(1,1)-M models of exports and exchange rates were estimated and the significance of the volatility coefficient was tested via t-tests. Data were log first-differenced as monthly exports and exchange rates were I(1) for the 1973 to 2013 period. In total, 42 estimations were performed. The major results provide empirical evidence that support the claim for some countries. Model results indicate that Brazilian agricultural and total exports have been significantly and negatively impacted by own and third country currency volatility, while Chinese and Honduran exports have been positively or not significantly affected. In the case of Turkey no significant effects were found. And the remaining countries Russia, India, and South Africa presented mixed results

A century of crop yield density estimation with perspectives

Crop Production/Industries,

An Indicator-Based Approach to Assess the Readiness of Urban Forests for Future Challenges: Case Study of a Mediterranean Compact City

Urban Forests (UFs) are key elements in Mediterranean compact cities, as they provide numerous ecosystem benefits and increase the resilience of cities against the anticipated impacts of climate change. It is, thus, necessary to review all the aspects that may have a negative effect on their ecosystem functions and the services that they provide. In this paper, a set of indicators is proposed that allow for a preliminary evaluation of some of the main disservices and factors that Mediterranean UFs present and the ways to maximize their benefits for users. For this purpose, 20 indicators, divided into three categories—Biodiversity, Accessibility/Facilities, and Infrastructure— were selected. Within these three categories, a range of values was established, from low to high or absence/presence. The indicators were tested in 24 urban forests of different types, all of which are representative of a medium-sized compact Mediterranean city. The results highlight that the UFs have adequate species richness and diversity, but among the species present are quite a few that emit BVOCs and allergens, as well as some that have invasive behavior. Poor cleaning, absence of night lightning, and scarcity of water points are aspects to improve in a good number of UFs; while a high surface area of impermeable soil, low tree cover, and extensive areas of grass that require large amounts of water for maintenance are the main issues of the infrastructure block that need medium-term planning to be addressed. It can be concluded that the proposed set of indicators allows for a general assessment of the readiness of UFTs in Mediterranean cities for the upcoming climatic, social, and ecological challenges

Evaluación de la calidad del sistema contable Mónica 8.5 de acuerdo con criterios medibles por el usuario según el estándar ISO 9126 en “Inversiones Gutiérrez Amador S.A”, Matagalpa, primer semestre del 2015

El presente trabajo investigativo se fundamenta en la evaluación del sistema contable Mónica 8.5 para la gestión de la información mediante los criterios medibles por el usuario según el estándar ISO 9126; dicho sistema se está utilizando en Inversiones Gutiérrez Amador S.A en la ciudad de Matagalpa durante el primer semestre del año 2015. Esta investigación permitió encontrar diferentes fallas y problemas en el sistema contable Mónica 8.5. Para obtener las conclusiones antes mencionadas los investigadores utilizamos diversas técnicas para la recolección de información tales como: entrevista a contadora general y auxiliares de contabilidad en Inversiones Gutiérrez Amador S.A, test de evaluación basado en los criterios medibles por el usuario del estándar ISO 9126 el cual fue también realizada a los profesores de contabilidad de la UNAN Managua FAREM Matagalpa que saben utilizar este sistema. Las principales fallas encontradas en el sistema contable Mónica 8.5 se exponen y se presentan las posibles soluciones enfocándose en los criterios medibles por el usuario debido a que el sistema contable Mónica 8.5 no cuenta con el código fuente disponible. Se hacen las siguientes recomendaciones: utilizar hojas de cálculos en versiones actuales de Microsoft Excel o utilizar formatos abiertos como el de Open office, mejorar la legibilidad de la interfaz de respald