Viscoelastic vibration damping identification methods. Application to laminated glass.

Laminatedglass is composed of two glass layers and a thin intermediate PVB layer, strongly influencing PVB's viscoelastic behaviour its dynamic response. While natural frequencies are relatively easily identified even with simplified FE models, damping ratios are not identified with such an ease. In order to determine to what extent external factors influence dampingidentification, different tests have been carried out. The external factors considered, apart from temperature, are accelerometers, connection cables and the effect of the glass layers. To analyse the influence of the accelerometers and their connection cables a laser measuring device was employed considering three possibilities: sample without instrumentation, sample with the accelerometers fixed and sample completely instrumented. When the sample is completely instrumented, accelerometer readings are also analysed. To take into consideration the effect of the glass layers, tests were realised both for laminatedglass and monolithic samples. This paper presents in depth data analysis of the different configurations and establishes criteria for data acquisition when testing laminatedglass

Improving a Satellite Mission System by means of a Semantic Grid Architecture

The use of a semantic grid architecture can make easier the deployment of complex applications, in which several organizations are involved and diverse resources are shared. This paper presents the application of the architecture defined in the Ontogrid project (S-OGSA) into a scenario for the analysis of the quality of the products of satellite missions

Equivalence between Zwanziger's horizon function and Gribov's no-pole ghost form factor

The ghost form factor entering the Gribov no-pole condition is evaluated till the third order in the gauge fields. The resulting expression turns out to coincide with Zwanziger's horizon function implementing the restriction to the Gribov region in the functional integral.Comment: 9 pp. No figures. Final version to appear in Physics Letters

Determination of faecal dry matter digestibility two weeks after weaning in twenty five day old weaned rabbits

[EN] The aim of this work was to analyse the evolution from 26 to 40 d of age of apparent faecal dry matter digestibility (DMd) in rabbits weaned at 25 d of age to define how to determine nutrient digestibility in the post-weaning period. Fifteen New Zealand ' Californian rabbits from five litters (3 rabbits/litter) weaned at 25 d of age and weighing 602±75g were fed ad libitum a commercial diet containing 20.0% crude protein and 33.5% NDF (on DM basis). Feed intake and faeces excretion were recorded daily from 25 to 40 d of age and DM digestibility determined. Litter affected DM intake and excretion (P = 0.013 and 0.014, respectively), and tended to affect DMd (P = 0.061), whereas age influenced all these traits (P < 0.001). Dry matter intake and DM excretion increased from 26 to 40 d of age by 158 and 480%, respectively. During the first week after weaning, DM intake increased more slowly than DM excretion (55 vs. 245%), but in the second week after weaning both increased by 67%. The correlation between daily feed intake was higher with the faeces excretion of the same day than with faeces excretion of the next day, and the first values were used to determine daily DMd. A broken line regression model was fitted to daily DMd, which decreased linearly from weaning to 32 d of age (2.17 ± 0.25 percentage units per day), whereas from 32 to 40 d it remained constant (69.4 ± 0.47%). Accordingly, for 25-d old weaned rabbits it would be advisable to begin a digestibility trial not before 32 d of age, using the first week after weaning as adaptation period. Average standard deviation of DMd decreased by 54% when the length of the collection period increased from 2 to 6 d. Consequently, the number of animals required to detect a significant difference among means depends on the length of the collection period. For a conventional collection period of four days, a difference of 2 percentage units could be detected by using 14 animals/treatment.Gómez-Conde, M.; García, J.; Villamide, M.; Carabaño, R. (2011). Determination of faecal dry matter digestibility two weeks after weaning in twenty five day old weaned rabbits. World Rabbit Science. 19(1):43-48. doi:10.4995/wrs.2011.816SWORD434819

Misleading signatures of quantum chaos

The main signature of chaos in a quantum system is provided by spectral statistical analysis of the nearest neighbor spacing distribution and the spectral rigidity given by $\Delta_3(L)$. It is shown that some standard unfolding procedures, like local unfolding and Gaussian broadening, lead to a spurious increase of the spectral rigidity that spoils the $\Delta_3(L)$ relationship with the regular or chaotic motion of the system. This effect can also be misinterpreted as Berry's saturation.Comment: 4 pages, 5 figures, submitted to Physical Review

Impedancias dinámicas en zapatas rígidas y flexibles sobre medios viscoelásticos

Se presentan aplicaciones recientes del Método de los Elementos de Contorno al cálculo de impedancias de cimentaciones en terrenos viscoelásticos, haciendo especial hincapié en el tratamiento de medios estratificados para problemas con simetría de revolución y en la forma de tratar zapatas flexibles

Ordenadores en el aula: ¿estamos preparados los profesores?

Integrar les TIC a les aules de Física i Química suposa un gran repte i els factors involucrats són molts i complexos. El problema fonamental rau en com s'utilitzen les TIC per part dels estudiants i, en això, tenen un paper molt important l'escola i l'ús que els professors fan d'elles. Hem realitzat una investigació amb 138 professors de Física i Química per analitzar com utilitzen les TIC en el seu treball d'aula, la percepció que tenen sobre com les utilitzen seus alumnes i les dificultats que sorgeixen en tractar i integrar les TIC en el treball d'aula. Els resultats mostren que les TIC s'utilitzen poc i que el seu ús genera incertesa en molts professors, per el que es pot concloure que cal una formació que faciliti la seva integració a les aules.Integrating Information and Communication Technology (ICT) into Physics and Chemistry classroom poses an important challenge. Factors involved are numerous and complex. The key problem is how the students use ICT and their high-schools and the use that teachers make of these technologies in the classroom play a fundamental role. Research was carried out with 138 Physics and Chemistry teachers in order to analyze how they include ICT in their classroom work, their perception about how the students use ICT and the difficulties that arise when trying to incorporate it to their daily work. The results indicate that ICT is slightly integrated into the classroom work and that their use generates uncertainty in many teachers. It can be concluded that appropriate training of the teachers to facilitate their use in classroom is required.Integrar las TIC en las aulas de Física y Química supone un gran reto y los factores involucrados son muchos y complejos. El problema fundamental radica en cómo se utilizan las TIC por parte de los estudiantes y, en esto, tienen un papel muy importante la escuela y el uso que los profesores hacen de ellas. Hemos realizado una investigación con 138 profesores de Física y Química para analizar cómo utilizan las TIC en su trabajo de aula, la percepción que tienen sobre cómo las utilizan sus alumnos y las dificultades que surgen al tratar e integrar las TIC en el trabajo de aula. Los resultados muestran que las TIC se utilizan poco y que su uso genera incertidumbre en muchos profesores, por lo que se puede concluir que es necesaria una formación que facilite su integración en las aulas

Antimicrobial activity of silver-carbon nanoparticles on the bacterial flora of bull semen

The spermicidal effects of silver nanoparticles (AgNPs) hinder its application in the field of artificial insemination. In this study, silver-carbon NPs (Ag@C NPs) was synthesized and applied as an alternative antibiotic agent for bull semen extender. Ag@C NPs were characterized using X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), atomic absorption flame spectroscopy, transmission electron microscope (TEM), and high-resolution TEM (HR-TEM). Data analysis revealed the successful synthesis of Ag@C NPs with a particle size of 1–5 nm (average particle size of 2.5 nm) embedded into carbon. The antimicrobial activity of Ag@C NPs was tested against bacteriospermia of fresh semen collected from five fertile bulls (three ejaculates/bull). Escherichia coli (E. Coli), Staphylococcus aureus (S. aureus), and Pseudomonas aeruginosa (P. aeruginosa) were isolated from fresh semen samples and identified by culture, staining, and conventional biochemical tests. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of Ag@C NPs against bacteriospermia was determined at 5 and 37 °C. Ag@C NPs showed efficient antimicrobial activity (MIC: 3.125–12.5 μg/mL) against the tested strains and strong bactericidal effect on S. aureus, and P. aeruginosa (MBC: 3.125 μg/mL), with no detrimental effect (P ˃ 0.05) on the percentage of sperm motility (70.71 ± 4.82; 74.65 ± 4.46), plasma membrane integrity (68.39 ± 4.31; 72.38 ± 4.91), acrosome integrity (88.40 ± 13.21; 86.77 ± 14.23), and normal sperm morphology (86.85 ± 7.43; 87.82 ± 8.15) at concentrations of 15 and 30 μg/mL, respectively, after a cold storage of 48 h. However, Ag@C NPs showed a detrimental effect on sperm parameters in a dose dependent manner at concentrations ≥60 μg/mL. Ag@C NPs showed no adverse effect on the sperm’s ultrastructure with limited sperm internalization at MIC. In conclusion, Ag@C NPs could be used as an alternative antibiotic agent for bull semen extender without a significant cytotoxic effect on the sperm during cold storage. However, further investigations for their effects on embryo production and female genitalia are still required

Evaluation of explotation system in an autochthonous goat group of milk production

In the present study we have done an evaluation of the farms in an region of the north of Córdoba (Spain). Twenty five farms with principally murciano-granadina breed, have been visited. In these farms, we have done an inquiry with 310 questions. This inquiry is structured in three sections; one of those has 150 management variables, another one has 100 health variables and the last one has 60 technologic variables. Farms have been clasiffied in three groups in relation to the succesfull events distribution for each group of variables. The clasification system, which has been contrasted by discriminant analysis, let us include the farms while they are incorporating in the program. This is a results in a simple way to apply a different action plan in each group of farms.En este estudio se ha realizado una evaluación de las ganaderías de una comarca del norte de la provincia de Córdoba. Se han visitado 25 explotaciones de ganado caprino lechero, principalmente de raza Murciano-Granadina, en las que se ha realizado una encuesta que contiene un total de 310 preguntas. Dicha encuesta se encuentra estructurada en tres partes, 150 aspectos de manejo, 100 aspectos sanitarios y 60 aspectos tecnológicos. Las explotaciones se han clasificado en tres grupos según la distribución de los sucesos favorables para cada grupo de variables. Este sistema de clasificación, que ha sido contrastado mediante análisis discriminante, permite ir incluyendo ganaderías que se incorporen en un futuro, y resulta una forma sencilla de aplicar un plan de actuaciones diferente para cada grupo de ganaderías