Global experts 'off radar'

This issue of ABE Journal, which takes inspiration from a 2008 conference session as well as from the many conversations that took place within one of the working groups of the European funded COST-action “European Architecture beyond Europe,”1 seeks to contribute to a more thorough understanding of a particular type of professional who emerged in architecture and planning milieus from 1945 onwards: the “global expert”. Through a series of contributions, some resulting from long-lasting, in-depth study while others draw on work-in-progress research, a number of individuals are brought to the fore who, despite their often extensive production or prominent roles on a global scale, have remained “off the radar”. Included in this issue are discussions pertaining to people such as Michel Kalt, Henri-Jean Calsat, David Oakley, Erica Mann, or Max Lock, as well as other, more well-known figures such as Louis Kahn, Jacqueline Tyrwhitt and Hassan Fathy. Through this variety, this ABE-journal issue stresses the need to distinguish between various types of such “global experts”, from embedded practitioners to foreign consultants just passing through. More importantly, the issue also seeks to outline some of the challenges confronting architectural historians in writing the history of this new kind of professional. This is done explicitly in the lengthy editorial, which, through a discussion of recent literature, serves as an introduction to the current state of research on the theme. As such, we hope that this issue will help set a possible research agenda on a topic that in the last several years has triggered scholarly attention, yet still requires a sound theoretical and methodological framing

Building the rainbow nation : a critical analysis of the role of architecture in materializing a post-apartheid South African identity

Soon after apartheid was abolished in 1994, the quest for a new, ‘authentic’ South African identity resulted in the emergence of the "Rainbow Nation" idea, picturing an equal, multicultural and reconciled society. As architecture is considered a crucial element in the promotion of this Rainbow identity, the country witnessed a remarkable "building boom" with its apogee roughly between 1998 and 2010. Huge investments have been made in state-driven projects which place the apartheid memory at the center of the architectural debate – mostly museums and memorials. However, the focus of this paper shall lie on another, less highlighted tendency in current architectural practice. This paper demonstrates that, through the construction of urban community services, South African architects attempt to materialize the Rainbow Nation in a way that might be closer to the everyday reality of society

Correction to: The interplay between self-esteem, expectancy, cognitive control, rumination, and the experience of stress: A network analysis

The original version of this article unfortunately contained a mistake. In Table 1 of this article, bulleted data in the column 1 were incorrectly aligned. Thus, this erratum is presented to fix this error. The original article has been correcte

Polaron features of the one-dimensional Holstein Molecular Crystal Model

The polaron features of the one-dimensional Holstein Molecular Crystal Model are investigated by improving a variational method introduced recently and based on a linear superposition of Bloch states that describe large and small polaron wave functions. The mean number of phonons, the polaron kinetic energy, the electron-phonon local correlation function, and the ground state spectral weight are calculated and discussed. A crossover regime between large and small polaron for any value of the adiabatic parameter $\omega_0/t$ is found and a polaron phase diagram is proposed.Comment: 12 pages, 2 figure

Polaron Formation in the Three-Band Peierls-Hubbard Model for Cuprate Superconductors

Exact diagonalization calculations show a continuous transition from delocalized to small polaron behavior as a function of intersite electron-lattice coupling. A transition, found previously at Hartree-Fock level [Yonemitsu et al., Phys. Rev. Lett. {\bf 69}, 965 (1992)], between a magnetic and a non magnetic state does not subsist when fluctuations are included. Local phonon modes become softer close to the polaron and by comparison with optical measurements of doped cuprates we conclude that they are close to the transition region between polaronic and non-polaronic behavior. The barrier to adiabatically move a hole vanishes in that region suggesting large mobilities.Comment: 7 pages + 3 poscript figures, Revtex 3.0, MSC-199

Dynamical mean-field theory of the small polaron

A dynamical mean-field theory of the small polaron problem is presented, which becomes exact in the limit of infinite dimensions. The ground state properties and the one-electron spectral function are obtained for a single electron interacting with Einstein phonons by a mapping of the lattice problem onto a polaronic impurity model. The one-electron propagator of the impurity model is calculated through a continued fraction expansion (CFE), both at zero and finite temperature, for any electron-phonon coupling and phonon energy. In contrast to the ground state properties such as the effective polaron mass, which have a smooth behaviour, spectral properties exhibit a sharp qualitative change at low enough phonon frequency: beyond a critical coupling, one energy gap and then more and more open in the density of states at low energy, while the high energy part of the spectrum is broad and can be explained by a strong coupling adiabatic approximation. As a consequence narrow and coherent low-energy subbands coexist with an incoherent featureless structure at high energy. The subbands denote the formation of quasiparticle polaron states. Also, divergencies of the self-energy may occur in the gaps. At finite temperature such effect triggers an important damping and broadening of the polaron subbands. On the other hand, in the large phonon frequency regime such a separation of energy scales does not exist and the spectrum has always a multipeaked structure.Comment: 21 Pages Latex, 19 PostScript figure

Quantum Monte Carlo Loop Algorithm for the t-J Model

We propose a generalization of the Quantum Monte Carlo loop algorithm to the t-J model by a mapping to three coupled six-vertex models. The autocorrelation times are reduced by orders of magnitude compared to the conventional local algorithms. The method is completely ergodic and can be formulated directly in continuous time. We introduce improved estimators for simulations with a local sign problem. Some first results of finite temperature simulations are presented for a t-J chain, a frustrated Heisenberg chain, and t-J ladder models.Comment: 22 pages, including 12 figures. RevTex v3.0, uses psf.te

Polaron and bipolaron formation in the Hubbard-Holstein model: role of next-nearest neighbor electron hopping

The influence of next-nearest neighbor electron hopping, $t^{\prime}$, on the polaron and bipolaron formation in a square Hubbard-Holstein model is investigated within a variational approach. The results for electron-phonon and electron-electron correlation functions show that a negative value of $t^{\prime}$ induces a strong anisotropy in the lattice distortions favoring the formation of nearest neighbor intersite bipolaron. The role of $t^{\prime}$, electron-phonon and electron-electron interactions is briefly discussed in view of the formation of charged striped domains.Comment: 4 figure

Using ILP to Identify Pathway Activation Patterns in Systems Biology

We show a logical aggregation method that, combined with propositionalization methods, can construct novel structured biological features from gene expression data. We do this to gain understanding of pathway mechanisms, for instance, those associated with a particular disease. We illustrate this method on the task of distinguishing between two types of lung cancer; Squamous Cell Carcinoma (SCC) and Adenocarcinoma (AC). We identify pathway activation patterns in pathways previously implicated in the development of cancers. Our method identified a model with comparable predictive performance to the winning algorithm of a recent challenge, while providing biologically relevant explanations that may be useful to a biologist