Polymerically Modified Layered Silicates: An Effective Route to Nanocomposites

Polymer/clay nanocomposites have been under an extensive investigation for about 15 years. Traditional methods to modify the clay are usually limited to small organic cations, preferably containing long alkyl chain(s), which are exchanged with the inorganic cations in the clay gallery. This article provides a comprehensive review on the strategies for clay modification using polymeric surfactants or polycations: from the synthesis of such surfactants, through the preparation of the polymerically modified clays, and to the fabrication of the respective polymer nanocomposites and their properties

You don't have to be poor to be an artist: Rejecting the old ways of the London Art market, many artists are starting their own alternative business models

The study for this MRes thesis investigates London’s contemporary art market as a form of enquiry about contemporary management practices in art environments (small galleries, artist studios, online galleries) covering the main aspects of the art leadership role and extending the enquiry into the interdependence between the traditional practices in the art market and contemporary changes in society (technological, economic, financial, social), also exploring new ways for positioning art works in the market and ways of engaging the public implemented by artists. The research thereby, responds to the question of to what extent the traditional model of gallery management is continuing to serve the artist or how it is being superseded by innovative approaches employed directly by the artist. The research surveys the perspective of emerging artists on how to enter the contemporary art market, in order to evaluate if the traditional business model of commercial galleries is still current and valid. It investigates the extent to which the role of the artist is evolving and it aims towards an improved perception of the role of the art manager. First, it identifies the role of the art manager as perceived by practitioners and researchers. Secondly, it presents funding on how contemporary artists are increasingly developing an entrepreneurial perspective, employing innovative forms of business model approaches. Thirdly, it explores how art management practices are evolving and artists are employing new approaches in promoting and selling their art. The following insights can be drawn from the research. The London Art market is prolific and competitive, yet dominated by the traditional gallery model. Artists struggle to achieve recognition and support from galleries, yet their endorsement remains essential. In response to this, a new figure of “artist entrepreneur” has emerged, challenging the tradition with new ways of working and selling art. Additionally, disruptive changes in technology are enabling artists to sell in innovative ways that bypass the system

Stick and Slip Behaviour of Confined Oligomer Melts under Shear. A Molecular-Dynamics Study.

The flow behaviour of melts of short chains, confined in molecularly thin Couette flow geometries, is studied with molecular-dynamics simulations. The effect of wall attraction and confinement on the density and velocity profiles is analysed. In these highly inhomogeneous films, a strong correlation between the density and velocity profile is found. Sticking of the interfacial layer on the wall and slip on the wall and inside the film is manifested by changes in the velocity profile. The location of the slip is determined by the strength of the wall attraction.

Atomic Force Microscopy and Real Atomic Resolution. Simple Computer Simulations.

Using a simple computer simulation for AFM imaging in the contact mode, pictures with true and false atomic resolution are demonstrated. The surface probed consists of two f.c.c. (111) planes and an atomic vacancy is introduced in the upper layer. Changing the size of the effective tip and its registry with respect to the atoms of the crystal probed, images with completely different qualitative features are obtained. If the effective tip is a single atom the vacancy is clearly imaged. However, if the tip consists of several atoms and is in registry with the sample, a virtual atom appears instead of the vacancy and the crystal lattice is perfectly reproduced. If the tip is out of registry with respect to the sample, artifacts having the size of the effective tip are reported.

Simulations of second order microphones in audio coding

6 pagesThe method of array processing involves the use of multiple microphones to receive a signal carried by propagating waves. Microphone arrays have a variety of applications such as sonars, radars and acoustic tomography. The main objective of this work is the implementation of higher order microphone arrays in Audio Coding. Prototype arrays are constructed and evaluated within a such system. Simulating the various microphone arrays revealed the advantages and possible drawbacks of each design. Various higher order designs have been implemented in the past and can be used as guidelines. Various spatial sound systems have been developed during the last 3 decades as a way for representing a sound field as accurately as possible. Some of them are based on the accurate reconstruction of the sound eld i.e. ambisonics, WFS while others are perception based. A good example of a latter systems is DirAC which is developed in the Laboratory of Acoustics and Audio Signal Processing, Helsinki University of Technology

Factored coset approach to bosonization in the context of topological backgrounds and massive fermions

We consider a recently proposed approach to bosonization in which the original fermionic partition function is expressed as a product of a $G/G$-coset model and a bosonic piece that contains the dynamics. In particular we show how the method works when topological backgrounds are taken into account. We also discuss the application of this technique to the case of massive fermions.Comment: 10 pages, latex, no figures, To appear in Mod.Phys.Lett.

Profile of digital slow journalism audiences in Argentina, Colombia, and Mexico

The aim of this work is to study slow journalism audiences, with a particular interest in Latin America, specifically Argentina, Colombia, and Mexico. Five case studies were carried out, covering Anfibia (Argentina), Arcadia (Colombia), Gatopardo (Mexico), La silla vacía (Colombia), and Letras libres (Mexico), along with a Delphi study (double round with 27 participants) and a structured questionnaire (of 1,500 people between the ages of 18 and 65 years). The results indicate that 75% of the surveyed population obtain their information from all kinds of digital media, among whom 84% use social media for this purpose. Slow journalism is still mainly unknown to a large fraction (17%) of the population, although once given its definition and some named examples, 40% of those surveyed claimed to have read the slow press at some time. Quality is the main reason for its consumption (62%), followed by searching for specific subjects (46%), especially for young people (65%) and in Colombia (52%). Experts in slow journalism agree that the key to consolidating an audience involves listening to and interacting with its members, together with their active participation in the media

Parametric spatial audio processing utilising compact microphone arrays

This dissertation focuses on the development of novel parametric spatial audio techniques using compact microphone arrays. Compact arrays are of special interest since they can be adapted to fit in portable devices, opening the possibility of exploiting the potential of immersive spatial audio algorithms in our daily lives. The techniques developed in this thesis consider the use of signal processing algorithms adapted for human listeners, thus exploiting the capabilities and limitations of human spatial hearing. The findings of this research are in the following three areas of spatial audio processing: directional filtering, spatial audio reproduction, and direction of arrival estimation.  In directional filtering, two novel algorithms have been developed based on the cross-pattern coherence (CroPaC). The method essentially exploits the directional response of two different types of beamformers by using their cross-spectrum to estimate a soft masker. The soft masker provides a probability-like parameter that indicates whether there is sound present in specific directions. It is then used as a post-filter to provide further suppression of directionally distributed noise at the output of a beamformer. The performance of these algorithms represent a significant improvement over previous state-of-the-art methods.  In parametric spatial audio reproduction, an algorithm is developed for multi-channel loudspeaker and headphone rendering. Current limitations in spatial audio reproduction are related to high inter-channel coherence between the channels, which is common in signal-independent systems, or time-frequency artefacts in parametric systems. The developed algorithm focuses on solving these limitations by utilising two sets of beamformers. The first set of beamformers, namely analysis beamformers, is used to estimate a set of perceptually-relevant sound-field parameters, such as the separate channel energies, inter-channel time differences and inter-channel coherences of the target-output-setup signals. The directionality of the analysis beamformers is defined so that it follows that of typical loudspeaker panning functions and, for headphone reproduction, that of the head-related transfer functions (HRTFs). The directionality of the second set of high audio quality beamformers is then enhanced with the parametric information derived from the analysis beamformers. Listening tests confirm the perceptual benefit of such type of processing. In direction of arrival (DOA) estimation, histogram analysis of beamforming and active intensity based DOA estimators has been proposed. Numerical simulations and experiments with prototype and commercial microphone arrays show that the accuracy of DOA estimation is improved