Study soil analysis in Alamo, Temapache and Veracruz, to generate doses of fertilization in orange

A nivel mundial los cítricos son el principal frutal cultivado, en México la producción de naranja es de gran importancia económica, los principales municipios productores del estado de Veracruz se encuentran Álamo, Papantla, Martínez de la Torre, Tihuatlán, Chicontepec y Temapache. Estas zonas, mantienen un rendimiento promedio bajo en comparación con otros países productores y un factor que puede mejorar los rendimientos es la óptima fertilización la cual tiene que ser respaldada con análisis de suelos para poder definir una dosis. Se realizaron 646 muestreos de suelo a una profundidad de 30 cm, en el municipio de Temapache, Veracruz, mediante un muestreo aleatorio simple, el tamaño de la muestra se adaptó a las condiciones de cada comunidad. Los análisis fueron enviados a dos laboratorios. Se evaluaron el pH, materia orgánica, nitrógeno, fósforo, potasio. Los resultados se analizaron con estadística no paramétrica mediante un análisis de frecuencias para lo que se plantearon diez rangos, se utilizó R stadistic package versión 64 3.2.0. El pH en más del 70% de los suelos fue alcalino, la concentración de materia orgánica solo en el 34.44% se encontró en condiciones adecuadas, los macroelementos se encuentran en condiciones óptimas a excepción del nitrógeno el cual se presentó en niveles bajos

Modelación espacial de la estructura y distribución de la población de caracol rosado (Aliger gigas) en Pedro Bank, Jamaica

The estimation of reliable indices of abundance for sedentary stocks requires the incorporation of the underlying spatial population structure, including issues arising from the sampling design and zero inflation. We applied seven spatial interpolation techniques [ordinary kriging (OK), kriging with external drift (KED), a negative binomial generalized additive model (NBGAM), NBGAM plus OK (NBGAM+OK), a general additive mixed model (GAMM), GAMM plus OK (GAMM+OK) and a zero-inflated negative binomial model (ZINB) ] to three survey datasets to estimate biomass for the gastropod Aliger gigas on the Pedro Bank Jamaica. The models were evaluated using 10-fold cross-validation diagnostics criteria for choosing the best model. We also compared the best model estimations against two common design methods to assess the consequences of ignoring the spatial structure of the species distribution. GAMM and ZINB were overall the best models but were strongly affected by the sampling design, sample size, the coefficient of variation of the sample and the quality of the available covariates used to model the distribution (geographic location, depth and habitat). More reliable abundance indices can help to improve stock assessments and the development of spatial management using an ecosystem approach.Las estimaciones de índices de abundancia relativa para evaluar poblaciones de especies sedentarias requieren tener en cuenta su estructura espacial, el diseño del muestreo y el alto número de ceros registrados a la hora del muestreo. Para obtener un índice confiable de abundancia para el gasterópodo Aliger gigas en Pedro Bank, Jamaica, se aplicaron siete técnicas de interpolación espacial a tres conjuntos de datos: kriging ordinario (OK), kriging con desviación externa (KED), modelo aditivo generalizado binomial negativo (NBGAM), NBGAM más OK (NBGAM+OK), modelo mixto aditivo general (GAMM), GAMM más OK (GAMM+OK) y modelo binomial negativo con ceros inflados (ZINB). La selección de los mejores modelos espaciales se basó en el criterio de validación cruzada con 10 iteraciones; asimismo, se aplicaron métodos de evaluación comúnmente usados, para destacar la importancia de tener en cuenta la estructura espacial de la distribución de la especie. Los mejores modelos fueron GAMM y ZINB, los cuales fueron fuertemente influenciados por el diseño de muestreo, el tamaño de muestra, el coeficiente de variación y la calidad de las covariables empleadas en la modelación (ubicación geográfica, profundidad y hábitat). Los índices de abundancia más confiables pueden contribuir a mejorar las evaluaciones y desarrollar el manejo espacial con enfoque de ecosistema

Intruder States and their Local Effect on Spectral Statistics

The effect on spectral statistics and on the revival probability of intruder states in a random background is analysed numerically and with perturbative methods. For random coupling the intruder does not affect the GOE spectral statistics of the background significantly, while a constant coupling causes very strong correlations at short range with a fourth power dependence of the spectral two-point function at the origin.The revival probability is significantly depressed for constant coupling as compared to random coupling.Comment: 18 pages, 10 Postscript figure

The effects of superior ovarian nerve sectioning on ovulation in the guinea pig

The effects on spontaneous ovulation associated with the unilateral or bilateral sectioning of the superior ovarian nerves (SON) were analyzed in guinea pigs at different time intervals of the estrous cycle. Day 1 of the estrous cycle was defined as the day when the animal presents complete loss of the vaginal membrane (open vagina). Subsequent phases of the cycle were determined by counting the days after Day 1. All animals were autopsied on the fifth day of the estrous cycle after surgery. Sectioning the right, left, or both SONs on day 5 (early luteal phase) resulted in a significant increase in the number of fresh corpora lutea. Ovulation increased significantly when the left SON (L-SON) was sectioned during late follicular phase (day 1) and medium luteal phase (day 8). When surgery was performed on days 1 or 8, neither sectioning the right SON (R-SON) nor sectioning the SON bilaterally had an apparent effect on ovulation rates. Similarly, ovulation rates were not affected when unilateral (right or left) or bilateral sectioning of the SON was performed during late luteal phase two (day 12). Unilateral or bilateral sectioning of the SON performed during the early luteal phase (day 5) was associated with a significant decrease in uterine weight. A comparable effect was observed when the L-SON was sectioned during late follicular phase (day 1), or medium luteal phase (day 8). No effects on uterine weight were observed when unilateral or bilateral sectioning of the SON was performed during late luteal phase. Our results suggest that in the guinea pig the SON modulates ovulation, and that the degree of modulation varies along the estrous cycle. The strongest influence of the SONs on ovulation occurs during early luteal phase, and decrease thereafter, being absent by late luteal phase. In addition, sectioning the left or the right SON caused different responses by the ovaries of adult guinea pigs. This paper discusses the mechanisms by which ovulation increased when the SON was surgically cut

Zinacantán y los conflictos por la tierra: una problemática de largo aliento

Una carta de 1848 del párroco de Zinacantán, Patricio Correa, conservada en el Archivo Histórico Diocesano de San Cristóbal de Las Casas, remite a un conflicto agrario de largo aliento entre Chiapa y Zinacantán que se remonta al siglo xvi y que todavía en el siglo xix tenía relevancia para los pueblos de Chiapas. En este artículo analizaremos la configuración territorial de Zinacantán y su relación con la legislación agraria: la misiva expone una larga experiencia histórica de negociación de los indígenas de Chiapas con fuerzas políticas de mayor amplitud en el campo legal, lo que les permitió defender sus intereses y apuntalar sus estrategias territoriales, al tiempo que ilustra la profundidad de la memoria histórica de los pueblos en relación con la tierra

Academic Procrastination, Self-Esteem and Self-Efficacy in University Students: Comparative Study in Two Peruvian Cities

The present study aims to determine the relationship between academic procrastination, self-esteem and self-efficacy in undergraduate students in two Peruvian cities. The population consisted of 13,767 students, from which a sample of 1,494 was extracted. The subjects were selected from eight universities: five private and one public, from the city of Metropolitan Lima; and two universities, one public and one private, from the city of Arequipa. The instruments used were the Academic Procrastination Scale (EPA), the Scale of Specific Perceived Self-Efficacy in Academic Situations (EAPESA) and the Rosemberg Self-Esteem Scale. The results allow us to conclude that, in terms of perceived effectiveness, the relationship is slightly higher in the city of Arequipa, reiterating this with respect to academic procrastination, where the relationship is also slightly higher. Finally, with regard to self-esteem, the trend continues to indicate a greater relationship in Arequip