Transformation of a grid of quadrats to cope with perspective artifacts

The direct superimposition of a standard test grid of congruent quadrats onto an image bearing a population of particles exhibiting perspective artifacts, tends to increase the variance of the population size estimator, because the quadrat contents become unbalanced. If the quadrats are transformed according to the same projection mechanism affecting the particles, however, then the variance is restored into moderate values. Our purpose was to provide exact, easily programmable equations for the relevant transform

On the precisión of the nucleator

Abstract The nucleator is a design unbiased method of local stereology for estimating the volume of a bounded object. The only information required lies in the intersection of the object with an isotropic random ray emanating from a fixed point (called the pivotal point) associated with the object. For instance, the volume of a neuron can be estimated from a random ray emanating from its nucleolus. The nucleator is extensively used in biosciences because it is efficient and easy to apply. The estimator variance can be reduced by increasing the number of rays. In an earlier paper a systematic sampling design was proposed, and theoretical variance predictors were derived, for the corresponding volume estimator. Being the only variance predictors hitherto available for the nucleator, our basic goal was to check their statistical performance by means of Monte Carlo resampling on computer reconstructions of real objects. As a plus, the empirical distribution of the volume estimator revealed statistical properties of practical relevance

On the precision of the isotropic Cavalieri design

ABSTRACT: The isotropic Cavalieri design is based on a isotropically oriented set of parallel systematic sections a constant distance apart. Its advantage over the ordinary Cavalieri design is twofold - first, besides volume it allows the unbiased estimation of surface area, and second, the error variance predictor for the volume estimator is much simpler, involving only the surface area of the object, and the distance between sections. In an earlier paper, the two hemispheres of a rat brain were arranged perpendicular to each other before sectioning, aiming at reducing the error variance with respect to other arrangements (such as the aligned one) by exploiting an intuitively plausible antithetic effect. Because the total surface area of the objects is unchanged under any arrangements, however, the error variance predictor for the volume estimator does not depend on object shape, which looks intriguing. Using reconstructions of the mentioned hemispheres, we dilucidate the aparent paradox by means of automatic Monte Carlo replications of the relevant volume estimates under the antithetic and the aligned arrangements.The authors acknowledge financial support from the Spanish project AYA2015-66357-R (MINECO/FEDER)

Variance prediction for population size estimation

Design unbiased estimation of population size by stereological methods is an efficient alternative to automatic computer vision methods, which are generally biased. Moreover, stereological methods offer the possibility of predicting the error variance from a single sample. Here we explore the statistical performance of two alternative variance estimators on a dataset of 26 labelled crowd pictures. The empirical mean square errors of the variance predictors are compared by means of Monte Carlo resampling

UNIQUENESS PROPERTIES OF THE INVARIATOR, LEADING TO SIMPLE COMPUTATIONS

It is shown that, for a three dimensional particle  (namely an arbitrary compact domain with piecewise smooth boundary in R^3) the mean wedge volume defined on a given pivotal section is equal to the average nucleator estimator of the particle volume defined on that section. Further, if the particle is convex and it contains the pivotal point, then the flower area of a given pivotal section equals the average surfactor estimator defined on that section. These results are intended to throw some light on the standing conjecture that the functional defined on a pivotal section according to the invariator has a unique general expression. As a plus, the former result leads to a computational formula for the mean wedge volume of a convex polygon which is much simpler than the one published recently, and it is valid whether the fixed pivotal point is interior or exterior to the particle

STEREOLOGICAL ANALYSIS OF THE COCHLEAR NUCLEI OF MONKEY (MACACA FASCICULARIS) AFTER DEAFFERENTATION

The cochlear nuclei (CN) in the brainstem receive the input signals from the inner ear through the cochlear nerve, and transmit these signals to higher auditory centres. A variety of lesions of the cochlear nerve cause deafness. As reported in the literature, artificial removal of auditive input, or 'deafferentation', induces structural alterations in the CN. The purpose of this study was to estimate a number of relevant stereological parameters of the CN in control and deafferented Macaca fascicularis monkeys

Admission, discharge and triage guidelines for paediatric intensive care units in Spain

La unidad de cuidados intensivos pediátricos (UCIP) es una unidad física asistencial hospitalaria independiente especialmente diseñada para el tratamiento de pacientes pediátricos quienes debido su gravedad o condiciones potencialmente letales requieren observación y asistencia médica intensiva integral y continua por un equipo médico que haya obtenido competencia especial en medicina intensiva pediátrica. La aplicación oportuna de terapia intensiva a los pacientes críticos reduce la mortalidad, el tiempo de estancia y los costes asistenciales. Con los objetivos de respetar el derecho del niño al disfrute del más alto nivel posible de salud y a servicios para el tratamiento de las enfermedades y la rehabilitación de la salud y de garantizar la calidad asistencial y la seguridad de los pacientes pediátricos críticos, la Asociación Española de Pediatría (AEP), la Sociedad Española de Cuidados Intensivos Pediátricos (SECIP) y la Sociedad Española de Medicina Intensiva, Crítica y Unidades Coronarias (SEMICYUC) han desarrollado y aprobado las guías de ingreso, alta y triage para las UCIP en España. Mediante la aplicación de estas guías se puede optimizar el uso de las UCIP españolas de forma que los pacientes pediátricos reciban el nivel de cuidados médicos más apropiado para su situación clínicaA paediatric intensive care unit (PICU) is a separate physical facility or unit specifically designed for the treatment of paediatric patients who, because of the severity of illness or other life-threatening conditions, require comprehensive and continuous inten-sive care by a medical team with special skills in paediatric intensive care medicine. Timely and personal intervention in intensive care reduces mortality, reduces length of stay, and decreases cost of care. With the aim of defending the right of the child to receive the highest attainable standard of health and the facilities for the treatment of illness and rehabilitation, as well as ensuring the quality of care and the safety of critically ill paediatric patients, the Spanish Association of Paediatrics (AEP), Spanish Society of Paediatric Intensive Care (SECIP) and Spanish Society of Critical Care (SEMICYUC) have approved the guidelines for the admission, discharge and triage for Spanish PICUs. By using these guidelines, the performance of Spanish paediatric intensive care units can be optimised and paediatric patients can receive the appropriate level of care for their clinical conditio