La arqueología hoy

Se recogen, en la primera parte de la ponencia, algunas de las transformaciones que ha conocido la arqueología en los últimos decenios: la ampliación de los límites cronológicos hasta umbrales contemporáneos, la caída del enfoque tradicional que concebía la arqueología como una disciplina ocupada básicamente en trabajar bajo cota 0 y la ampliación de escala del objeto de estudio desde la cultura material mueble y el yacimiento hacia el territorio. En una segunda parte se hace un esfuerzo por redefinir el perfil de la arqueología en la actualidad llevando a cabo una reflexión fundamentalmente ontológica y axiológica, sin renunciar sin embargo a algunas consideraciones de carácter epistemológico. Para terminar, se presenta la “cadena de valor” como herramienta metodológica que sirve mejor que ninguna otra al tratamiento del Patrimonio desde una perspectiva integral e interdisciplinaria.

Parametric & nonparametric approaches to event studies: an application to a hotel’s market value

The main objective of this paper is twofold: on the one hand, to analyse the impact that the announcement of the opening of a new hotel has on the performance of its chain by carrying out an event study, and on the other hand, to compare the results of two different approaches to this method: a parametric specification based on the autoregressive conditional heteroskedasticity models to estimate the market model, and a nonparametric approach, which implies employing Theil’s nonparametric regression technique, which in turn, leads to the so-called complete nonparametric approach to event studies. The results that the empirical application arrives at are noteworthy as, on average, the reaction to such news releases is highly positive, both approaches reaching the same level of significance. However, a word of caution must be said when one is not only interested in detecting whether the market reacts, but also in obtaining an exhaustive calculation of the abnormal returns to further examine its determining factors.

Calibration of the length of a chain of single gold atoms

Using a scanning tunnelling microscope or mechanically controllable break junction it has been shown that it is possible to control the formation of a wire made of single gold atoms. In these experiments an interatomic distance between atoms in the chain of ∼3.6 Å was reported which is not consistent with recent theoretical calculations. Here, using precise calibration procedures for both techniques, we measure the length of the atomic chains. Based on the distance between the peaks observed in the chain length histogram we find the mean value of the interatomic distance before chain rupture to be 2.5±0.2 Å. This value agrees with the theoretical calculations for the bond length. The discrepancy with the previous experimental measurements was due to the presence of He gas, that was used to promote the thermal contact, and which affects the value of the work function that is commonly used to calibrate distances in scanning tunnelling microscopy and mechanically controllable break junctions at low temperatures.