Moss and liverwort epiphytes on trunks of Cyathea delgadii in a fragment of tropical rain forest, São Paulo State, Brazil

This study is a survey of the bryophyte species that occur on the trunks of Cyathea delgadii Sternb. (Cyatheaceae), a native tree fern, encountered in a fragment of Atlantic forest located in the area of the „Parque Estadual das Fontes do Ipiranga (PEFI)“, São Paulo State, Brazil. Specimens of bryophytes were collected from March 2001 to October 2003. We found 35 bryophyte species (12 spp. of mosses and 23 of liverworts). Ceratolejeuenea dentacornuta Steph. is presented as a new record for Brazil. A brief discussion about previous records of bryophyte species growing on trunks of tree ferns in Brazil is also presented

Quantum Broadening of k-Strings from the AdS/CFT Correspondence

We study the quantum broadening (width) of k-strings. We generalise an old result by Luscher, Munster and Weisz to the case of a k-string, by using the gauge/gravity correspondence. When the fundamental QCD-string is replaced by a bound state of k strings, the bound state is better described by a wrapped D-brane. We calculate the width of the k-string (the wrapped D-brane) in several AdS/CFT backgrounds by using a D-brane probe and find universally that omega_k ^2 = 1 / (2\pi \sigma_k) log R/r .Comment: 13 pages, LaTex. v2: minor changes, references added. To appear in Nucl.Phys.

Editorial: Research as practice: on critical methodologies

Isabelle Stengers, perhaps unwittingly, perhaps knowingly, echoes a theme of the work of American philosopher Stanley Cavell (1995, p. 136) when she invites in the first edition of the journal Subjectivity, her readers to join her in slowing down, in hesitating, pausing, taking a breath in the face of our own endeavours to ‘produce subjectivity’ (Stengers, 2008, p. 49). Cavell’s gesture of hesitation is similarly evocative and provocative. Where Stengers pushes for an approach which betrays or reveals rather than denounces, Cavell suggests that in the face of apparently constitutive philosophical oppositions, in stead of seeking to decide we should seek to dismantle. Betrayal rather than denunciation; revelation rather than condemnation; dismantling rather than deciding. Alluring and seductive ideas but the question is begged: where is the critical edge? This volume grapples with this question. It hesitates in the face of the complex relations between theory, research methods and practice, and the persons and places, or milieus, they are embedded in. It represents an attempt to revive the question as to what it means to do psychology critically, or for that matter, to practice critical theory

DataWarp: Building Applications which Make Progress in an Inconsistent World

The usual approach to dealing with imperfections in data is to attempt to eliminate them. However, the nature of modern systems means this is often futile. This paper describes an approach which permits applications to operate notwithstanding inconsistent data. Instead of attempting to extract a single, correct view of the world from its data, a DataWarp application constructs a collection of interpretations. It adopts one of these and continues work. Since it acts on assumptions, the DataWarp application considers its recent work to be provisional, expecting eventually most of these actions will become definitive. Should the application decide to adopt an alternative data view, it may then need to void provisional actions before resuming work. We describe the DataWarp architecture, discuss its implementation and describe an experiment in which a DataWarp application in an environment containing inconsistent data achieves better results than its conventional counterpart

Structure, energetics, and mechanical stability of Fe-Cu bcc alloys from first-principles calculations

Atomic volumes, magnetic moments, mixing energies, and the elastic properties of bcc Fe1–xCux solid solutions are studied by ab initio calculations based on the cluster expansion framework. For the calculation of concentration-dependent elastic moduli in disordered solid solutions, we introduce a generalization of the cluster expansion technique that is designed to handle tensorial quantities in high-symmetry phases. Calculated mixing energies, atomic volumes, and magnetic moments are found to be in good agreement with available measurements for metastable alloys prepared through nonequilibrium processing techniques. Additionally, the predicted variations of the bulk modulus and shear moduli C44 and C[prime] with respect to copper concentration are calculated for the disordered bcc phase. While the bulk modulus and C44 are positive for all concentrations, C[prime] is predicted to be positive only for Cu concentration less than 50 atomic %, and negative otherwise. Our results thus indicate that the mechanical instability of bcc Cu persists over a wide range of compositions. The implications of the present results are discussed in relation to the observed metastability of bcc Fe-Cu alloys, and the strengthening mechanism of nanoscale bcc precipitates in an alpha-Fe matrix