Un procedimiento Bootstrap en el contexto del Análisis de Correspondencias: Aproximación numérica para medir la estabilidad de los ejes

[EN] Bootstrap procedures are commonly used to evaluate the stability of principal axes methods. In our research, attention is focussed on the particular case of Correspondence Analysis (CA). As in classical CA the metrics are induced by table margins and thus would vary over the replicated tables, we suggest here a specific Bootstrap procedure in which a generalised CA is performed on the replicated tables imposing as metrics those issued from the original table. The contribution of our paper is to provide a numerical procedure to quantify the stability of principal axes which is suitable for this context. We give a bounded measure of the stability of axes. Furthermore, as any fixed threshold handled to label an axis as stable or unstable would be arbitrary, our procedure is based on the comparison of real and randomly permuted data to determine stability thresholds. Computational results obtained on several data sets are offered.[ES] Los procedimientos Bootstrap se utilizan habitualmente para evaluar la estabilidad de los métodos basados en ejes principales. En nuestra investigación, la atención se centra en el caso particular del Análisis de Correspondencias. Dado que en el Análisis de Correspondencias clásico las métricas están determinadas por las frecuencias marginales de las tablas y, por tanto, variarían a través de las tablas replicadas, sugerimos aquí un procedimiento Bootstrap específico en el que se lleva a cabo un Análisis de Correspondencias generalizado de las tablas replicadas imponiendo como métricas las procedentes de la tabla original. La contribución de nuestro trabajo es proporcionar un procedimiento numérico para cuantificar la estabilidad de los ejes principales que es adecuado para este contexto. Proponemos una medida acotada de la estabilidad de los ejes. Además, teniendo en cuenta que cualquier umbral fijo considerado para etiquetar un eje como estable o inestable sería arbitrario, nuestro procedimiento se basa en la comparación de datos reales y datos permutados aleatoriamente para determinar umbrales de estabilidad. Se presentan los resultados computacionales obtenidos en varios conjuntos de datos

Reduced glutathione and Trolox (vitamin E) as extender supplements in cryopreservation of red deer epididymal spermatozoa

P. 37-46The use of assisted reproductive techniques in cervids is increasing as the commercial use of these species increase. We have tested the suitability of the antioxidants Trolox and reduced glutathione (GSH) for freezing red deer epididymal spermatozoa, aiming at improving post-thawing quality. Samples from 19 stags were frozen in a TES-Tris-fructose extender (20% egg yolk, 8% glycerol), with 1 or 5 mM of antioxidant. Motility (CASA), lipoperoxidation (malondialdehyde –MDA– production), membrane status, mitochondrial activity, acrosomal status (flow cytometry) and chromatin status (SCSA: %DFI and %HDS; flow cytometry) were assessed after thawing and after 6 h at 39 °C. There were few differences between treatments after thawing, with Trolox reducing MDA production in a dose–response manner. After the incubation, sperm quality decreased and %DFI increased moderately, with no change for MDA. GSH improved motility, kinematic parameters and mitochondrial status, with a slight increase in %HDS. GSH 5 mM also increased moderately MDA production and %DFI, possibly due to enhanced metabolic activity and reducing power. Trolox maintained MDA low, but was detrimental to sperm quality. Trolox might not be appropriate for the cryopreservation of red deer epididymal spermatozoa, at least at the millimolar range. GSH results are promising, especially regarding motility improvement after the post-thawing incubation, and should be selected for future fertility trials.S

Influence of metacognitive variables on paranoid ideation

Based on the Self-Regulatory Executive Function (S-REF) model, the aim of the present correlational study is to investigate whether metacognitive variables have any influence on paranoid ideation in non-clinical subjects. For this purpose, a battery of tests was administered to 148 participants in an attempt to identify the type of metacognitive beliefs that characterized them and to measure their levels of paranoid ideation and trait anxiety. The results show that, once the subject’s level of anxiety is controlled, loss of cognitive confidence is the only metacognitive variable that predicts subjects’ scores in paranoid ideation. Without this statistical control of trait anxiety, the regression equation would include two more metacognitive factors related to uncontrollability and danger of thoughts and positive beliefs about worry. These results are discussed in the light of recent contributions supporting the extension of models already consolidated in the field of emotional disorders, as the S-REF model, to that of psychotic symptoms.Con base en el modelo conocido como “Self-Regulatory Executive Function” (S-REF) el presente estudio correlacional pretende averiguar si las variables metacognitivas tienen alguna influencia sobre la ideación paranoide en sujetos no-clínicos. Con este fin se administró una batería de tests a 148 participantes dirigida a indagar el tipo de creencias metacognitivas por el que se caracterizaban así como su nivel de ideación paranoide y su nivel de ansiedad-rasgo. Los resultados muestran que, una vez controlado el nivel de ansiedad de los sujetos, la pérdida de la confianza cognitiva es la única variable metacognitiva que predice la puntuación de los sujetos en ideación paranoide. De no efectuarse este control estadístico de la ansiedad-rasgo, se incluirían en la ecuación de regresión dos factores metacognitivos más relativos a la incontrolabilidad y peligro de los pensamientos y a las creencias positivas sobre la preocupación. Estos resultados son discutidos a la luz de recientes aportaciones favorables a la extensión de modelos ya consolidados en el campo de los trastornos emocionales, como el modelo S-REF, a los síntomas psicóticos.Com base no modelo conhecido por “Função Executiva de Auto-regulação” (S-REF) o presente estudo correlacional pretende averiguar se as variáveis metacognitivas têm alguma influência sobre a ideação paranoide em sujeitos não clínicos. Com este fim, administrou-se uma bateria de testes a 148 participantes destinada a questionar o tipo de crenças metacognitivas pelas quais se caracterizavam, assim como o seu nível de ideação paranoide e o seu nível de ansiedade-traço. Os resultados mostram que, uma vez controlado o nível de ansiedade dos sujeitos, a perda de confiança cognitiva é a única variável metacognitiva que prediz a pontuação dos sujeitos em ideação paranoide. Sem se efectuar este controlo estadístico da ansiedade-traço, incluíram-se na equação de regressão dois factores metacognitivos mais relativos à incontrolabilidade e perigo dos pensamentos e às crenças positivas sobre a preocupação. Estes resultados são discutidos à luz de recentes contribuições favoráveis à extensão de modelos já consolidados no campo das perturbações emocionais, como o modelo S-REF, aos sintomas psicóticos.This work was carried out within framework of Research Grnat MCT-02-BSO-01173, whose principal researcher is Marino Pérez-Álvarez

The role of meta-cognitions and thought control techniques in predisposition to auditory and visual hallucinations

Objectives. This study examines the relationship between a predisposition to hallucinations and meta-cognitive variables and thought-control techniques, controlling for the possible effect of anxiety. In order to do so, we start out with the hypothesis that anxiety does not, in itself, explain the association between meta-cognitions and a predisposition to auditory and visual hallucinations. Design. A within-participants correlational design was employed. Methods. Four psychometric tests relating to predisposition to hallucinations, anxiety, meta-cognitions and thought-control techniques were administered to 150 participants. Results. It was found that, after controlling for participants' anxiety levels, the ‘loss of cognitive confidence’ factor predicted the score on the scale of predisposition to both auditory and visual hallucinations. Thought-control strategies based on worry were also found to be predictive of a greater predisposition to hallucinations, regardless of whether or not participants' anxiety level was controlled. Conclusions. Meta-cognitive variables of cognitive confidence and thought control through worry are positively associated with a predisposition to hallucinations. Limitations. The correlational nature of the design does not allow inferences about causal relationships

Presentación. Agricultura familiar a debate

[ES] Sin resumenMoreno Pérez, OM.; García Álvarez-Coque, JM. (2014). Presentation. Family farming on debate. Economía Agraria y Recursos Naturales - Agricultural and Resource Economics. 14(1):131-132. http://hdl.handle.net/10251/118023SWORD13113214

Evidence of learning on the insertion and care of peripheral venous catheters in nursing students: A mixed study

Objectives: 1) To assess nursing students' evidence-based knowledge on the use of PVCs, and 2) to examine the perception of learning and teaching strategies aimed at this skill. Background: Insertion and care of Peripheral Venous Catheters (PVCs) are essential skills in undergraduate nursing education. Appropriate knowledge of this skill is crucial to improve clinical practice and patient safety. Therefore, training becomes an enabler for safe practice. Design: A multi-centre convergent parallel mixed-methods. Setting and participants: A total of 675 second-, third- and fourth-year nursing students from 3 nursing schools took part in the study. Methods: Quantitative data collection used a validated 15-question survey on knowledge of PVC management, and a descriptive and inferential analysis was carried out. Qualitative data were collected via a questionnaire consisting of 4 open-ended questions assessing knowledge, teaching methodologies and scenarios, and points for improvement. Results: Most participants were female (74.04%), with a mean age of 22.45 (SD = 4.65), who had no experience in the health field (61.8%). They obtained a mean knowledge score of 7.27 (SD = 2.64) out of 15. The students who obtained higher scores had a mean professional experience of 7.96, SD = 2.66 (p 0.000) and were in their final year, with a mean of 8.59, SD = 2.56, (p 0.000). On the other hand, the students assessed their knowledge as basic but improving year by year. They also identified a need to apply more active and experiential methodologies that would allow for reflection. Conclusion: Level of educational level and experience is associated with increased knowledge. In order to improve knowledge, changes must be made in the training process to incorporate methodologies such as simulation and online training. There is a need to develop programmes that favour the alignment of theory with clinical practice

Organizing pneumonia

En su Glosario de Términos de Radiología Torácica, la Sociedad Fleischner (1) define este hallazgo como una entidad patológica y clínica bien definida. Previamente llamada bronquiolitis obliterante neumonía en organización, ahora se prefiere el término neumonía en organización, ya que este describe mejor las características esenciales de esta entidad y elimina la confusión con enfermedades de la vía aérea distal como la bronquiolitis constrictiva (2).Glosario radiológico46-5

Cryopreservation of Iberian red deer (Cervus elaphus hispanicus) spermatozoa obtained by electroejaculation

P. 628-638We tested extenders and freezing protocols for Iberian red deer semen. Samples were obtained by electroejaculation (10 stags), and analyzed for motility (CASA), viability (propidium ioide), acrosomal (PNA-FITC) and mitochondrial status (JC-1). Samples were diluted in extender, cooled and adjusted for glycerol (extender with higher glycerol concentration), brought to mL−1 and frozen. Four experiments were carried out, repeating sperm analysis after thawing to compare treatments. In a first experiment, seven samples were frozen using Triladyl® (20% egg yolk) and UL extender (Tes–Tris–fructose, 15% egg yolk, 4% glycerol). Triladyl® yielded higher motility after thawing. In a second trial, 17 samples were frozen using Triladyl®, Andromed®, Bioxcell®, and UL with 8% LDL (low-density lipoproteins). Triladyl® and Andromed® performed better than Bioxcell® on motility, and than UL-LDL on viability and acrosomal status. In a third experiment, the performance of freezing the sperm-rich ejaculate fraction versus the whole ejaculate was tested on nine samples. The sperm-rich ejaculate fraction not only rendered more motile and viable spermatozoa but also showed higher freezability (higher motile spermatozoa recovery). In a fourth experiment, we tried three modifications of the freezing protocol, for improving the freezability of low concentration samples: prior removal of seminal plasma; replacing extender (second fraction) for pure glycerol to reduce dilution; and performing only the dilution, not the second dilution. No differences were found, although only three samples could be used. Both Triladyl® and Andromed® were deemed appropriate for freezing Iberian red deer semen, and the rich fraction should be selected for freezing.S

A cost for high levels of sperm competition in rodents: Increased sperm DNA fragmentation

Spermcompetition, a prevalent evolutionary process inwhich the spermatozoa of two or more males compete for the fertilization of the same ovum, leads to morphological and physiological adaptations, including increases in energetic metabolism that may serve to propel sperm faster but that may have negative effects onDNA integrity. SpermDNA damage is associated with reduced rates of fertilization, embryo and fetal loss, offspring mortality, and mutations leading to genetic disease. We tested whether high levels of sperm competition affect sperm DNA integrity. We evaluated sperm DNA integrity in 18 species of rodents that differ in their levels of spermcompetition using the spermchromatin structure assay. DNA integrity was assessed upon sperm collection, in response to incubation under capacitating or non-capacitating conditions, and after exposure to physical and chemical stressors. Sperm DNA was very resistant to physical and chemical stressors, whereas incubation in noncapacitating and capacitating conditions resulted in only a small increase in spermDNA damage. Importantly, levels of spermcompetition were positively associated with sperm DNA fragmentation across rodent species. This is the first evidence showing that high levels of sperm competition lead to an important cost in the form of increased sperm DNA damage.Peer Reviewe