Effects of Method and Level of Nitrogen Fertilizer Application on Soil pH, Electrical Conductivity, and Availability of Ammonium and Nitrate in Blueberry

Blueberries (Vaccinium spp.) require low soil pH and prefer N primarily as ammonium for optimum production. Nitrogen fertilizer methods and rates were evaluated in a new field of `Bluecrop" blueberry (Vaccinium corymbosum L.) to determine their effects on soil pH and availability of ammonium and nitrate in soil solution. Treatments included four application methods (split fertigation, continuous fertigation, and two non-fertigated controls) and four rates of N application (0, 50, 100, and 150 kg/ha N). Fertigation treatments were irrigated by drip and injected with liquid urea fertilizer; split fertigation was applied as a triple-split from April to June while continuous fertigation was applied weekly from leaf emergence to approximately 2 months prior to the end of the growing season. Non-fertigated controls were fertilized with a triple-split of granular ammonium sulfate and irrigated by drip or microsprays. Soil pH was usually lower with microsprays than with drip, even when no N fertilizer was applied; however, soil pH was also reduced with higher N applications and, in fact, was similar between continuous fertigation and granular fertilizer (microspray) treatments when 150 kg/ha N was added. Nitrogen application with granular fertilizer, whether irrigated by microspray or drip, maintained much higher ammonium concentrations than continuous or split fertigation but often increased electrical conductivity (salinity) of the soil solution (ECw) to >2 dS/m. By comparison, ECw was always <1.5 dS/m with either fertigation method. Granular N application coupled with microsprays also resulted in higher nitrate concentrations than any other treatment, which may lead to more N leaching since the ability of blueberry to acquire nitrate-N is limited

THE PRE-EXHAUSTION METHOD SEEMS INEFFECTIVE TO INCREASE ELECTROMYOGRAPHIC ACTIVITY

The purpose of this study was to investigate the effects of the pre-exhaustion method on the electromyographic activity (temporal and spectral domain) at different intervals of a set of resistance training. Twenty adults with little or no experience in strength training performed two sets of the seated row exercise at 70%1RM until muscular failure, in a randomized order. Surface electrodes were placed over the latissimus dorsi, teres major, biceps brachii, and posterior deltoid muscles of the dominant side. Results showed that the pre-exhaustion did not increase EMG activity of all muscle analyzed at any intervals of a set. Furthermore, the EMG median frequency decreased in teres major and posterior deltoid muscles during initial and intermediate repetitions. Results suggest that the pre-exhaustion induces more fatigue when compared to traditional training

Visual art inspired by the collective feeding behavior of sand-bubbler crabs

Sand--bubblers are crabs of the genera Dotilla and Scopimera which are known to produce remarkable patterns and structures at tropical beaches. From these pattern-making abilities, we may draw inspiration for digital visual art. A simple mathematical model is proposed and an algorithm is designed that may create such sand-bubbler patterns artificially. In addition, design parameters to modify the patterns are identified and analyzed by computational aesthetic measures. Finally, an extension of the algorithm is discussed that may enable controlling and guiding generative evolution of the art-making process

El aprendizaje basado en problema para activar la resolución de problemas con el uso de herramientas informáticas (Revisión).

Problem-based learning is characterized by the fact that learning is student-centered, and that it is meaningful; The process of solving problems with the use of computer tools is developed based on small work groups, which learn collaboratively in their learning process. For the development of this work, techniques such as observation of classes, interviews with students are used. The objective is to describe the implementation of Problem-Based Learning in solving problems based on data at the Pre-university educational level.El aprendizaje basado en problemas se caracteriza por ser significativo y estar centrado en el estudiante; el proceso de resolución de problemas con el uso de herramientas informáticas se desarrolla en base a grupos pequeños de trabajo que aprenden de manera colaborativa en su proceso de aprendizaje. Para el desarrollo de este trabajo se emplean técnicas como observación a clases y entrevista a estudiantes. El objetivo es describir la implementación del aprendizaje basado en problemas en la resolución de problemas sobre base de datos en el nivel educativo Preuniversitario

Cultura de la urgencia y asimetrías municipales en la contribución territorial del desarrollo

Objetivo: Valorar los grados de simetría que se manifiestan en las decisiones relacionadas con el empleo de la contribución territorial al desarrollo local en la provincia Villa Clara, Cuba y los dilemas de lo urgente frente a lo estratégico en la práctica de la cultura decisional de asignar recursos limitados, para el desarrollo.  Métodos y técnicas: Se aplicó el método de estudio de caso de una provincia en Cuba y sus respectivos municipios respecto a la utilización de los recursos captados por la contribución territorial del desarrollo local. Se emplearon técnicas estadístico-matemáticas relacionadas con el diagnóstico de la situación actual. Se construyen índices para medir los grados de simetría alcanzada en la gestión de gobierno municipal, relacionada con la contribución territorial del desarrollo local.  Principales resultados: Se evaluó la eficacia del proceso decisional de asignación de recursos a escala municipal de los recursos captados como contribución territorial para el desarrollo local; se destacaron las debilidades observadas en este proceso que guardan relación con la cultura en la toma de decisiones.  Conclusiones: El futuro de Cuba y su prosperidad tendrá en cada localidad un escenario decisivo. Los actores emergidos en la transformación constitucional cubana  son ya realidad, junto a ellos operan cambios institucionales. La descentralización de la toma de decisiones en el empleo de recursos críticos para el desarrollo endógeno de cada localidad, exige un cambio cultural esencial, donde la evaluación de impactos presida cada decisión que comprometa el futuro. Se corroboraron asimetrías significativas en el impacto alcanzado

Parametric hazard rate models for long-term sickness absence

PURPOSE: In research on the time to onset of sickness absence and the duration of sickness absence episodes, Cox proportional hazard models are in common use. However, parametric models are to be preferred when time in itself is considered as independent variable. This study compares parametric hazard rate models for the onset of long-term sickness absence and return to work. METHOD: Prospective cohort study on sickness absence with four follow-up years of 53,830 employees working in the private sector in the Netherlands. The time to onset of long-term (>6 weeks) sickness absence and return to work were modelled by parametric hazard rate models. RESULTS: The exponential parametric model with a constant hazard rate most accurately described the time to onset of long-term sickness absence. Gompertz-Makeham models with monotonically declining hazard rates best described return to work. CONCLUSIONS: Parametric models offer more possibilities than commonly used models for time-dependent processes as sickness absence and return to work. However, the advantages of parametric models above Cox models apply mainly for return to work and less for onset of long-term sickness absence

Nonparametric estimation of conditional transition probabilities in a non-Markov illness-death model

One important goal in multi-state modeling is the estimation of transition probabilities. In longitudinal medical studies these quantities are particularly of interest since they allow for long-term predictions of the process. In recent years signi ficant contributions have been made regarding this topic. However, most of the approaches assume independent censoring and do not account for the influence of covariates. The goal of the paper is to introduce feasible estimation methods for the transition probabilities in an illness-death model conditionally on current or past covariate measures. All approaches are evaluated through a simulation study, leading to a comparison of two di erent estimators. The proposed methods are illustrated using real a colon cancer data set.This research was nanced by FEDER Funds through Programa Operacional Factores de Competitividade COMPETE and by Portuguese Funds through FCT - Funda ção para a Cência e a Tecnologia, within Projects Est-C/MAT/UI0013/2011 and PTDC/MAT/104879/2008. We also acknowledge nancial support from the project Grants MTM2008-03129 and MTM2011-23204 (FEDER support included) of the Spanish Ministerio de Ciencia e Innovaci on and 10PXIB300068PR of the Xunta de Galicia. Partial support from a grant from the US National Security Agency (H98230-11-1-0168) is greatly appreciated