Finite size effects on the phase diagram of a binary mixture confined between competing walls

A symmetrical binary mixture AB that exhibits a critical temperature T_{cb} of phase separation into an A-rich and a B-rich phase in the bulk is considered in a geometry confined between two parallel plates a distance D apart. It is assumed that one wall preferentially attracts A while the other wall preferentially attracts B with the same strength (''competing walls''). In the limit $D\to \infty$, one then may have a wetting transition of first order at a temperature T_{w}, from which prewetting lines extend into the one phase region both of the A-rich and the B-rich phase. It is discussed how this phase diagram gets distorted due to the finiteness of D% : the phase transition at T_{cb} immediately disappears for D<\infty due to finite size rounding, and the phase diagram instead exhibit two two-phase coexistence regions in a temperature range T_{trip}<T<T_{c1}=T_{c2}. In the limit D\to \infty T_{c1},T_{c2} become the prewetting critical points and T_{trip}\to T_{w}. For small enough D it may occur that at a tricritical value D_{t} the temperatures T_{c1}=T_{c2} and T_{trip} merge, and then for D<D_{t} there is a single unmixing critical point as in the bulk but with T_{c}(D) near T_{w}. As an example, for the experimentally relevant case of a polymer mixture a phase diagram with two unmixing critical points is calculated explicitly from self-consistent field methods

Iterative Interplay between Aharonov-Bohm Deficit Angle and Berry Phase

Geometric phases can be observed by interference as preferred scattering directions in the Aharonov-Bohm (AB) effect or as Berry phase shifts leading to precession on cyclic paths. Without curvature single-valuedness is lost in both case. It is shown how the deficit angle of the AB conic metric and the geometric precession cone vertex angle of the Berry phase can be adjusted to restore single-valuedness. The resulting interplay between both phases confirms the non--linear iterative system providing for generalized fine structure constants obtained in the preliminary work. Topological solitons of the scalar coupling field emerge as localized, non-dispersive and non-singular solutions of the (complex) sine-Gordon equation with a relation to the Thirring coupling constant and non-linear optics

Critique [of Fascism: A Review of Its History and Its Present Cultural Reality in the Americas]

Professor Forbes’ article represents a timely and important contribution. It should, if need be, serve as a means of raising the readers’ historical consciousnesses during a period in which dramatic changes in U.S. economic and social policies are under way, in a time when unabashed power politics seem to be imposed on half the globe by the ruling classes of both great imperial powers

Travellerscapes : tourism research and transnational anthropology ; paper for the conference 'Alltag der Globalisierung. Perspektiven einer transnationalen Anthropologie', January 16-18, 2003, Institute of Cultural Anthropology and European Ethnology, Johann Wolfgang Goethe University, Frankfurt am Main

Even though tourism has been recognised as an important field for transnational research today, there are few attempts to place tourism in the context of transnational theories or to think about transnationalism from the perspective of tourists. I argue that in researching tourist practices one can add important aspects to transnational approaches. The prerequisites of mobility and interaction for example are the features chosen by backpackers to describe what their Round-The-World-Trip is about. A form of tourism is adopted, or created, that itself confronts many aspects of globalisation: First of all there is the immense dynamic that is involved. Backpackers try to cover as many places and experiences as possible, travelling at high speed. They adopt all kinds of touristic experiences ranging from beach to adventure to culture tourism. They don't focus on a specific area or country but travel the world. They cross national borders perpetually. Additionally they form a transnational network in which they interact with strangers of similar backgrounds (other backpackers, tourist professionals). This network helps them interacting with people from different backgrounds (the socalled hosts or locals). Considering my research Backpackers forge a certain identity from these transnational practices which I want to name globedentity. Globedentity expresses a type of identity construction that not only refers to the individual (I) but reflects the world (globe) in this identity. This globedentity is not fixed but is perpetually re-created and re-defined. It also embraces the increasing popular awareness of globalisation which backpackers, coming from highly educated middle class backgrounds, in particular have identified with. Due to the constant awareness of the latest global social, cultural and economic developments in these educated milieus they know exactly which tools to use to become successful parts of their societies

[Review of] Sandra Maria Esteves, Yerba Buena

With this, her first anthology, the New York born Puerto Rican poet Sandra Maria Esteves should establish herself as the first lady among the Latin poets in that city. Esteves, thirty-three, whose poetry has appeared before in twenty magazines1 and who is an acknowledged painter, combines in her best work her own ghetto experience with nature symbolism, political, cultural and racial awareness and a determined woman\u27s perspective