Four-dimensional homogeneous critical metrics for quadratic curvature functionals

We determine all homogeneous metrics which are critical for some quadratic curvature functional in dimension four

Long- term effects of fire and three fire-fighting chemicals on a soil-plant system.

The impacts of fire and fire-fighting chemicals (FFC) on soil properties and the soil-plant system were evaluated five years after treatment application. Unburnt soils (US) were compared with burnt soils treated with water alone (BS) or with foaming agent (BS+Fo), Firesorb polymer (BS+Fi), or ammonium polyphosphate (BS+Ap). Soils (0-2 cm depth) and foliar material (Ulex micranthus, Pterospartum tridentatum, Erica umbellata and Pinus pinaster) were analysed for total-C, total-N, δ 15N, nutrients (soil-available; plant-total), pH and inorganic-N (soils) and vegetation cover and height. No long-term effects of FFC on soil properties were found except for pH (BS+Fo > BS+Ap), inorganic-N and P (BS+Ap > other treatments). BS+Ap plants usually showed higher values of δ 15N, N, P and Na, but less K. Soil coverage by Pterospartum and Ulex was higher in BS+Ap than in other treatments, while the opposite was observed for Erica; shrubs were always taller in BS+Ap. After 3 years of growth, the size of pine seedlings followed the order BS+Ap > US > other treatments. Foliar N and P, scrub regeneration and growth of pines showed the long-term fertilizing effect of ammonium polyphosphate, although the second highest pine mortality was found in the BS+Ap treatment. The foaming agent did not affect vegetation cover, and Firesorb had no noticeable effect on shrubs but the highest pine mortality.Peer reviewe

Examples of signature (2,2) manifolds with commuting curvature operators

We exhibit Walker manifolds of signature (2,2) with various commutativity properties for the Ricci operator, the skew-symmetric curvature operator, and the Jacobi operator. If the Walker metric is a Riemannian extension of an underlying affine structure A, these properties are related to the Ricci tensor of A

Aborto epidémico y endémico asociado a la infección por Neospora caninum en el ganado bovino: relación entre la respuesta inmune y las consecuencias de la infección a lo largo de la gestación

Neospora caninum es un protozoo intracelular obligado perteneciente al Phylum Apicomplexa. La neosporosis bovina se considera una de las principales causas de fallo reproductivo en el ganado bovino. La transmisión transplacentaria del parásito puede originar aborto ó el nacimiento de terneros congénitamente infectados. La transmisión transplacentaria endógena ocurre tras la recrudescencia de una infección crónica en la hembra durante la gestación, mientras que la exógena se da tras una primoinfección adquirida de forma postnatal. Un mayor conocimiento de la epidemiología, integrado con el empleo de adecuadas técnicas de diagnóstico serológico son la base del control. El objetivo del presente estudio fue determinar mediante diferentes pruebas diagnósticas la relación existente entre la respuesta serológica desarrollada por reproductoras bovinas infectadas a lo largo de una gestación, el origen de la infección y sus repercusiones reproductivas.Neospora caninum is an apicomplexan protozoan parasite. At present bovine neosporosis is one of the main causes of reproductive failure in cattle worldwide. Transplacental transmission of the parasite can lead to abortion or birth of congenitally infected calves. Endogenous transplacental transmission occurs as a consequence of the recrudescence of a previous chronic infection in the cow during gestation. On the other hand, exogenous transplacental transmission occurs after an acquired postnatal primo infection. Control programmes are based on updated knowledge about the epidemiology together with the employment of appropriate diagnostic serological tests. The aim of the present study was to determine the relationship between the serologic response developed by infected breeding cattle along gestation, the mode of transmission and the future consequences in reproduction

Using Task-Evoked Pupillary Response to Predict Clinical Performance during a Simulation Training

[EN] Training in healthcare skills can be affected by trainees’ workload when completing a task. Due to cognitive processing demands being negatively correlated to clinical performance, assessing mental workload through objective measures is crucial. This study aimed to investigate task-evoked changes in pupil size as reliable markers of mental workload and clinical performance. A sample of 49 nursing students participated in a cardiac arrest simulation-based practice. Measurements of cognitive demands (NASA-Task Load Index), physiological parameters (blood pressure, oxygen saturation, and heart rate), and pupil responses (minimum, maximum, and difference diameters) throughout revealed statistically significant differences according to performance scores. The analysis of a multiple regression model produced a statistically significant pattern between pupil diameter differences and heart rate, systolic blood pressure, workload, and performance (R2 = 0.280; F (6, 41) = 2.660; p < 0.028; d = 2.042). Findings suggest that pupil variations are promising markers to complement physiological metrics for predicting mental workload and clinical performance in medical practice.S