Clifford geometric parameterization of inequivalent vacua

We propose a geometric method to parameterize inequivalent vacua by dynamical data. Introducing quantum Clifford algebras with arbitrary bilinear forms we distinguish isomorphic algebras --as Clifford algebras-- by different filtrations resp. induced gradings. The idea of a vacuum is introduced as the unique algebraic projection on the base field embedded in the Clifford algebra, which is however equivalent to the term vacuum in axiomatic quantum field theory and the GNS construction in C^*-algebras. This approach is shown to be equivalent to the usual picture which fixes one product but employs a variety of GNS states. The most striking novelty of the geometric approach is the fact that dynamical data fix uniquely the vacuum and that positivity is not required. The usual concept of a statistical quantum state can be generalized to geometric meaningful but non-statistical, non-definite, situations. Furthermore, an algebraization of states takes place. An application to physics is provided by an U(2)-symmetry producing a gap-equation which governs a phase transition. The parameterization of all vacua is explicitly calculated from propagator matrix elements. A discussion of the relation to BCS theory and Bogoliubov-Valatin transformations is given.Comment: Major update, new chapters, 30 pages one Fig. (prev. 15p, no Fig.

More than just trees: Assessing reforestation success in tropical developing countries

Rural communities in many parts of the tropics are dependent of forests for their livelihoods and for environmental services. Forest resources in the tropics have declined rapidly over the past century and therefore many developing countries in the tropics have reforestation programs. Although reforestation is a long-term process with long-term benefits, existing evaluations of the success of these programs tends to focus on short-term establishment success indicators. This paper presents a review of reforestation assessment that highlights the need to not only consider short-term establishment success, but also longer-term growth and maturation success, environmental success and socio-economic success. In addition, we argue that reforestation assessment should not be based on success indicators alone, but should incorporate the drivers of success, which encompasses an array of biophysical, socio-economic, institutional and project characteristics. This is needed in order to understand the reasons why reforestation projects succeed or fail and therefore to design more successful projects in future. The paper presents a conceptual model for reforestation success assessment that links key groups of success indicators and drivers. This conceptual model provides the basis for a more comprehensive evaluation of reforestation success and the basis for the development of predictive systems-based assessment models. These models will be needed to better guide reforestation project planning and policy design and therefore assist rural communities in tropical developing countries to alleviate poverty and achieve a better quality of life

Figurillas de encapuchados hispanorromanos: Definición, clasificación e interpretación

Representations of hooded individuals or <em>cucullati</em> were frequent in the Roman world. The characteristic <em>cucullus</em> was worn by both male individuals of a low social rank and patricians who wore hoods to avoid being recognised; also divine beings known as <em>genii</em> and other divinities were represented with a hood and cloak-hood, in this case with a special meaning. When studying ancient <em>Hispania</em>, such representations have often gone unobserved due to publication problems rather than to their absence in the archaeological record. A historiographic review of terracotta and bronze figurines or small sculptures of <em>cucullati</em> documented so far in the Iberian Peninsula has made it possible to analyse their origin, character, and the materials used in their manufacturing, in such a way that new knowledge is gained from a context-based analysis.<br><br>Las figurillas de encapuchados o <em>cucullati</em> fueron frecuentes en el mundo romano. El característico <em>cucullus</em> fue usado tanto por hombres de baja consideración social como por personas pudientes que deseaban no ser reconocidos; y con esta capucha y manto-capucha, dotados de un significado especial, fueron también representados <em>genii</em>, seres divinos y otras pequeñas divinidades, así como figuraciones que servían como ahuyentadores de espíritus y símbolos protectores. En el ámbito de la antigua <em>Hispania</em> estas representaciones han pasado bastante desapercibidas, lo que obedece a un problema de publicación más que de una ausencia en el registro arqueológico. La revisión historiográfica de las esculturillas de <em>cucullati</em> de terracota y bronce, documentadas hasta el momento en la Península Ibérica, nos permite analizar su procedencia, características técnicas, aportando hipótesis sobre su significado en su contexto arqueológico

Multiple Forms of Endocytosis In Bovine Adrenal Chromaffin Cells

We studied endocytosis in chromaffin cells with both perforated patch and whole cell configurations of the patch clamp technique using cell capacitance measurements in combination with amperometric catecholamine detection. We found that chromaffin cells exhibit two relatively rapid, kinetically distinct forms of stimulus-coupled endocytosis. A more prevalent “compensatory” retrieval occurs reproducibly after stimulation, recovering an approximately equivalent amount of membrane as added through the immediately preceding exocytosis. Membrane is retrieved through compensatory endocytosis at an initial rate of ∼6 fF/s. Compensatory endocytotic activity vanishes within a few minutes in the whole cell configuration. A second form of triggered membrane retrieval, termed “excess” retrieval, occurs only above a certain stimulus threshold and proceeds at a faster initial rate of ∼248 fF/s. It typically undershoots the capacitance value preceding the stimulus, and its magnitude has no clear relationship to the amount of membrane added through the immediately preceding exocytotic event. Excess endocytotic activity persists in the whole cell configuration. Thus, two kinetically distinct forms of endocytosis coexist in intact cells during perforated patch recording. Both are fast enough to retrieve membrane after exocytosis within a few seconds. We argue that the slower one, termed compensatory endocytosis, exhibits properties that make it the most likely mechanism for membrane recycling during normal secretory activity