Parametric downconversion with optimized spectral properties in nonlinear photonic crystals

We study the joint spectral properties of photon pairs generated by spontaneous parametric down-conversion in a one-dimensional nonlinear photonic crystal in a collinear, degenerate, type-II geometry. We show that the photonic crystal properties may be exploited to compensate for material dispersion and obtain photon pairs that are nearly factorable, in principle, for arbitrary materials and spectral regions, limited by the ability to fabricate the nonlinear crystal with the required periodic variation in the refractive indices for the ordinary and extraordinary waves.Comment: 9 pages, 6 figure

The Historical Development of the Port of Livorno (Italy) and Its New Port Plan 2010 in Advanced Stage of Elaboration

The geographical location makes the port of Livorno one of the most important in Italy. The port, in fact, benefits of an extended network of roads and rails connecting it with the rest of Italy, and central and southern Europe as well. The history of Livorno and its port is inextricably linked to that of Pisa and Florence, and to the complexity of events that determined the political set-up of the region along several centuries. Looking at the new port plan of Livorno has made it necessary an extensive overview of the history of both the port, and of its planning. This analysis has allowed: to understand the reason for the different choices made in the past for the development of the port, highlighting, when necessary, the errors made; to identify the strengths and weaknesses of the existing port infrastructure; to identify the works needed to boost the port in the European context. The purpose of this paper is to provide a summary of the analysis performed for the implementation of the new Livorno port plan 2010 and show how the port planning in Italy is often conditioned by hundreds of centuries of history

Coyote drums and jaguar altars: Ontologies of the living and the artificial among the K’iche’ Maya

For the current-day K’iche’ Maya of the Highland community of Momostenango, Guatemala, animals are conceived as having not human, but artificial souls: they are, in fact, objects that exist in the mountain dwellings of their gods. Conversely, artefacts like sacred altars are seen as being wild animals of the gods and ancestors, which can bring illness and death to people when not fed by ritual offerings. Based on this and other data that the author gathered during his recent ethnographic fieldwork among the K’iche’, in this article he explores the ontological paradoxes of living beings and artefacts among current-day Maya and other Mesoamerican peoples of the past to propose a version of perspectivism that incorporates the ideas of technology, asymmetry and material culture to the more horizontal and personhood-based model proposed for Amazon cultures by Viveiros de Castro in his article, ‘Cosmological deixis and Amerindian perspectivism’ (1998)

Calibration of a 400 mm helical master gear at INRIM

A complete - and first ever at INRIM - calibration of a master gear is described. This includes the evaluation of the uncertainty of measurement, which is particularly challenging for this type of complex calibration

Mi Casa Linda

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