Una explicación del comportamiento errático del intervalo de Wald en el modelo binomial

Recoge los contenidos presentados a: ASEPELT España. Reunión anual (21. 2007. Valladolid).Es conocido que el intervalo de Wald para estimar la proporción de éxito en una distribución binomial presenta un comportamiento muy errático con respecto a su probabilidad de cubrimiento al hacer variar los parámetros n y p. Habitualmente se ha considerado que este comportamiento es “esencialmente impredecible”. Sin embargo, el análisis de la causa de estos descensos permite obtener una fórmula que proporciona, fijado p, todos los valores de n en los que se produce un brusco descenso de la probabilidad de cubrimiento. Dicho análisis también permite comprender por qué el intervalo de Wilson presenta un comportamiento menos errático que el de Wald.The erratic behaviour of the coverage probability of the Wald interval of a binomial proportion has previously been remarke on the literture. In addition, “unlucky" values of n again arise in the same “unpredictable” way. In section 4, we present an explication on the “unlucky" of n and, also, we propos a method to calculate, fixed p, the values of n where significant change in coverage probability occurs. From the analysis of the Wald interval, we show that the performance the Wilson interval is less erratic

Potencial de conservación de la biodiversidad de bosques y árboles en fincas del paisaje ganadero Catacamas, Honduras

El estudio evaluó el potencial de conservación de biodiversidad arbórea de diferentes usos de la tierra en el paisaje ganadero Catacamas, Honduras. Se planteó la hipótesis de que los diferentes usos contribuyen en la misma medida a la conservación de la diversidad de árboles a escala de parcela y paisaje. Se muestrearon árboles con un dap mínimo de medición de 10 cm en 448 parcelas (área total de 84,2 ha) ubicadas en diferentes usos forestales y agrícolas característicos del paisaje Catacamas: bosques secundarios continuos (BS), fragmentos de bosque secundario (BSF), plantaciones de café rústico (PLANT), agricultura (AGRI), pasturas (PAST), cercas vivas (CV) y bosques ribereños (BR). Con los datos se caracterizó la estructura, composición y diversidad arbórea en el paisaje y se comparó entre los usos de la tierra

Can robotic-based top-down rehabilitation therapies improve motor control in children with cerebral palsy? A perspective on the CPWalker project

[EN] Cerebral Palsy (CP) is one of the most severe disabilities in childhood, and it demands important costs in health, education, and social services. CP is caused by damage to or abnormalities inside the developing brain that disrupt the brain's ability to control movement and maintain posture. Furthermore, CP is often associated with sensory deficits, cognition impairments, communication and motor disabilities, behavior issues, seizure disorder, pain, and secondary musculoskeletal problems. According to the literature, motor modules are peripheral measurements related to automatic motor control. There is a lack of evidence of change in motor modules in children with CP when different treatment approaches have been evaluated. Thus, new strategies are needed to improve motor control in this population. Robotic-based therapies are emerging as an effective intervention for gait rehabilitation in motor disorders such as stroke, spinal cord injury, and CP. There is vast clinical evidence that neural plasticity is the central core of motor recovery and development, and on-going studies suggest that robot-mediated intensive therapy could be beneficial for improved functional recovery. However, current robotic strategies are focused on the peripheral neural system (PNS) facilitating the performance of repetitive movements (a bottom-up approach). Since CP affects primarily brain structures, both the PNS and the central nervous system (CNS) should to be integrated in a physical and cognitive rehabilitation therapy (a top-down approach). This paper discusses perspectives of the top-down approach based on a novel robot-assisted rehabilitative system. Accordingly, the CPWalker robotic platform was developed to support novel therapies for CP rehabilitation. This robotic platform (Smart Walker + exoskeleton) is controlled by a multimodal interface enabling the interaction of CP infants with robot-based therapies. The aim of these therapies is to improve the physical skills of infants with CP using a top-down approach, in which motor related brain activity is used to drive robotic physical rehabilitation therapies. Our hypothesis is that the CPWalker concept will promote motor learning and this improvement will lead to significant improvements in automatic motor control.Lerma Lara, S.; Martínez Caballero, I.; Bayón, C.; Del Castillo, M.; Serrano, I.; Raya, R.; Belda Lois, JM.... (2016). Can robotic-based top-down rehabilitation therapies improve motor control in children with cerebral palsy? A perspective on the CPWalker project. Biomedical Research and Clinical Practice. 22-26. doi:10.15761/BRCP.1000106S222

Risk analysis and cacao pod survivorship curves to improve yield forecasting methods

Cocoa attainable yields are affected by a complex of pests and diseases in a particular agro-environment. Estimation of yield loss is critical for agronomic and economic decision-making at the farm level. For over 15 months, we monitored 1100 pods from six cocoa clones (PMCT-58, CC-137, CATIE-R1 CATIE-R4, ICS-95, and CCN-51) to assess the incidence of pests and diseases and to elucidate their survival behavior. Cocoa clones grow in a 12-year timber-based cocoa agroforestry plot (1330 cocoa plants ha-1, 100 shade trees ha-1, and 65% shade cover), in La Montaña, Turrialba, Costa Rica. Between 6-12 trees and 120-140 pods per clone of four size classes (very small – 2.5-7 cm, small – 7.1-14 cm, medium – 14.1-21 cm, and large – ≥21 cm) were tagged and measured fortnightly. Pods were selected at two vertical strata along the tree trunk (below and above 1.5 m) and grouped into three generations (rainy, transition, and dry). Competitive risk and survival analysis were performed per clone, generation, pod size class, and pod position along the tree trunk. Overall, pods reached maturity at the age of 155-165 days and were exposed to several hazards that disrupted their development. The Cox model that better described the cumulative risk during pod development included two covariables with substantial explicative power, generation, and clones. Regardless of clone and pod generation, a combination of diseases/pests accounted for about 45% to 65% of yield losses. The Kaplan-Meier survival analysis showed that pod survival was similar between generations but differed among clones within generations. Pods from CATIE-R1, CATIE-R4 and CC-137 clones showed greater survival rates than those of ICS-95, CCN-51 and PMCT-58 clones. The position of the pod along the tree trunk did not influence pod survival rates. We combined pod counting and pod survival rates calculated in this study and contrasted our yield estimations against a widely used prediction method proposed by a certification body. Overall, yield estimated using the UTZ method applied to 90-day-old pods of CATIE-R1 clone consistently overestimated yield predictions in the range of 27-45%. We proposed the combination of pod counting and pod index with a set of clone-specific discount factors; the survival rates, to reliably forecast on-farm cacao yields over time