Gauge invariant cosmological perturbations for the nonminimally coupled inflaton field

We construct the gauge invariant free action for cosmological perturbations for the nonminimally coupled inflaton field in the Jordan frame. For this the phase space formalism is used, which keeps track of all the dynamical and constraint fields. We perform explicit conformal transformations to demonstrate the physical equivalence between the Jordan and Einstein frames at the level of quadratic perturbations. We show how to generalize the formalism to the case of a more complicated scalar sector with an internal symmetry, such as Higgs inflation. This work represents a first step in developing gauge invariant perturbation theory for nonminimally coupled inflationary models.Comment: 21 pages, references added, typos corrected, extended section IV on Higgs inflatio

The (Un-) Homely in Bogotá

The Architectural Embrace aims to build a metaphorical bridge between socio-economic, political and architectural contradictions in Bogotá by means of a hybrid layer – an alien object in the rigid urban grid of the city, rupturing the existing notions of what and who is valuable in the city. It thus criticizes the current and past practices of neglect and disdain towards the lowest classes of society and explores the role of architecture in challenging political and societal problems. But how does one progress in such a notorious place as El Bronx, where the urban memory is built on transgression and felt by the (architectural) uncanny without erasing the past? How does one respect and commemorate (pre-) existing conditions without dictating a collective meaning? And how does one create an architectural alternative that does not colonize the place? The Architectural Embrace approaches these paradoxes by offering a place of reflection amidst the roaring city life and its power struggles. By means of a new type of architecture, unfamiliar to and disrupting the context and its hierarchies on both urban and architectural scale, the building criticizes existing practices and paves a way toward a new perception of the location. It thus lies on the verge of the uncanny and transgressional space. In The Architectural Embrace, the city of Bogotá is presented with a monumental architecture representing the abolished fourth block of El Bronx. Instead of erasing ‘the hell of Bogotá’, it recognizes the importance of this area in the city and it emphasizes the value of the lower classes of society, while addressing the history of neglect of the location. Thus, as a tool of (and place for) reflection, the project may work as a catalyst for sustainable change and an alternative to the gentrification that brings about a vicious cycle of displacement, decay and demolition in the city

Three-phase packed bed reactor with an evaporating solvent—II. Modelling of the reactor

In this paper two models are presented for a three-phase catalytic packed bed reactor in which in evaporating solvent is used to absorb and remove most of the reaction heat. A plug flow model and a model comprising mass and heat dispersion in the reactor are discussed. The results of both models are compared to each other and to experimental data obtained in a miniplant on the hydrogenation of 2,4,6-trinitrotoluene to triaminotoluene described in Part I. The influence of reactor pressure, feed temperature and the molar ratio of hydrogen to the reactant in the feed are discussed. It is concluded that both models can well describe the influence of the operating variables on the reactor behaviour and that a large part of the reaction heat can be removed by evaporation of the solvent. From a comparison with the experimental results it is concluded that the dispersion model can well describe the experimental data for a fresh catalyst. The agreement between the model and the experimental data for a deactivated catalyst is not good. As long as no quantitative description of the local deactivation in the packed bed is available, any model will fail to predict local concentrations in the reactor. Despite this drawback recommendations can be given how to use this reactor type of optimize the selectivity in producing an intermediate product

Coded SQUID arrays

We report on a superconducting quantum interference device (SQUID) system to read out large arrays of cryogenic detectors. In order to reduce the number of SQUIDs required for an array of these detectors, we used code-division multiplexing. This simplifies the electronics because of a significantly reduced number of wires from the cryogenic detectors to the SQUIDs and the room temperature electronics. Several prototype chips based on SQUIDs with multiple inputs coils have been developed and direct and indirect crosstalk properties are discussed