Gloria Sanchez

Abstract“The Book of Secrets in the Results of Ideas”, usually called “The Book of Secrets” is a codex containing drawings and descriptions of thirty-one artifacts attributed to the engineer Alī Ibn Khalaf al-Murādī, who lived in Andalusia in southern Spain at the beginning of the 11th century. This manuscript is one of the first written testimonies that describe medieval mechanisms with complex precision. The aim of this work is to reconstruct and study from a historical and technological point of view two of the ancient artifacts contained in the “Book of Secrets”, the “Fortress Demolisher” and the “Magic Well”. The “Fortress Demolisher” is a war machine designed to demolish the upper part of the walls or towers and consists of a battering ram mounted on a platform that can be raised several meters above the ground using a scissor mechanism. The “Magic Well” is a mechanism with several pulleys whose purpose is to raise water several meters from the bottom of a well by collecting a small portion of rope. To reconstruct the two artifacts, a digital model and a detailed study of the geometry and operation of the mechanisms, were first carried out. 3D printing, using the Fused Deposition Modelling technology, made the physical reproduction. The digitization and physical reproduction by 3D printing of the mechanisms represent an update of the traditional ways of transmitting knowledge. The use of these new technologies makes the knowledge more accessible, understandable and attractive.

The first European settlements in the new world faced technical issues with the help of the XVI century scientific advances. Besides briefly exposing the scientific and technological situation, this paper explores, with the help of reverse engineering, two singular mechanical wits representative of the technological advances introduced in America to overcome different problems. Firstly, a pump, based on an alternative movement system through crankshafts and pistons used against the continuous flooding suffered in the Ciudad de México valley. Although flooding remained a problem (it was solved in the XX century), hydraulic pumps were essential for continuous soil drainage. Secondly, a port crane for handling cannons, military devices, and construction materials during the Lima fortification in the XVII century. For both cases, reverse engineering, through engineering methods, Computer-Aided Design CAD programs, and additive manufacturing, provides virtual and/or tangible mockups that help to analyze and improve our knowledge about the dimensions, materials, and functions of used (and currently lost) mechanical systems during the American colonization.

There is no doubt that the use of Internet for purchasing products and services has constituted a crucial change in how people go about buying them. In the era of digital transformation, the possibility of accessing information provided by other users about their personal experiences has taken on more weight in the selection and buying processes. On these lines, traditional word-of-mouth has given way to electronic word-of-mouth, which constitutes a major social change. This behavior is particularly relevant in the services area, where potential users cannot in advance assess what is on offer. There is an abundant literature analyzing the effects of eWOM on different variables of interest in this sector. However, little is known about the factors that determine eWOM. Thus, the main objective of the present paper is to analyze the impact of two variables on eWOM. Both of them are crucial for potential customers in the process of finding hotel accommodations and they can motivate people to make such comments. The results demonstrate that these variables truly have a significant impact on whether or not users make comments on line. Moreover, it proved possible to observe certain differences according to the profile of the tourist involved and the destination where the hotel is located. In the current changing environment, this information is of great use for hotel managers in order to design strategies according to the type of guest they wish to attract.

Los principales patógenos víricos que podemos ad­quirir ingiriendo alimentos contaminados son los norovirus, el virus de la hepatitis A y el virus de la hepatitis E que se propagan principalmente a través de la vía fecal oral. En los últimos años, la incidencia de brotes de transmisión alimentaria causados por estos patógenos ha experimentado un aumento considerable, en parte debido al comercio globalizado y a los cambios en los hábitos de consumo. Las matrices alimentarias que mayor riesgo representan para el consumidor son los moluscos bivalvos, ve­getales de IV gama, frutas tipo baya y platos listos para comer. Actualmente las técnicas moleculares son las más habituales para la detección de estos patógenos en alimentos, aunque toda­vía existen dudas acerca del significado de la presencia de estos genomas víricos en términos de seguridad alimentaria. La infec­tividad de estos patógenos en alimentos viene también determi­nada por su elevada persistencia ambiental y por su resistencia a los tratamientos aplicados para la conservación de los alimentos.