Expedições alemães que fundaram a etnologia da Amazônia

Resenhas: KRAUS, Michael. Bildungsbürger im Urwald: Die deutsche ethnologische Amazonienforschung (1884–1929). Marburg: Curupira, 2004. 539 p.: il. ISBN 3-8185-0397-4.Rezension zu: KRAUS, Michael. Bildungsbürger im Urwald: Die deutsche ethnologische Amazonienforschung (1884–1929). Marburg: Curupira, 2004. 539 p.: il. ISBN 3-8185-0397-4

Exact expression for Drude conductivity in one-dimension with an arbitrary potential

An exact expression for the Drude conductivity in one dimension is derived under the presence of an arbitrary potential. In getting the conductivity the influence of the electric field on the crystal potential is taken into account. This coupling leads to a systematic deformation of the potential and consequently to a significant modification of the charge transport. The corrections to the conventional Drude conductivity are determined by the configurational part of the partition function. The activation energy for the conductivity process is expressed by a combination of the free energy of the underlying equilibrium system. The electric current is calculated in the linear response regime by solving the Smoluchowski equation. The steady state solution differs significantly from the equilibrium distribution. In case of a tight binding potential the conductivity offers corrections depending on the amplitude of the potential. As a further application we discuss nanocontacts with piecewise constant potentials. The electric conductivity is corrected by the potential height.Comment: 12 pages, 3 figure

Charting Vanishing Voices: A Collaborative Workshop to Map Endangered Oral Cultures

This presentation was given at the World Oral Literature Project 2012 workshop Charting Vanishing Voices: A Collaborative Workshop to Map Endangered Oral Cultures.Language endangerment is by now a well-known topic, and language documentation one well-established academic discipline that aims at addressing this urgent issue. Language documentation in the modern sense is concerned with creating lasting records of language in the natural environment by building annotated multi-media corpora, among other resources. A crucial point here is to ensure that the data are archived in a sustainable way – they ought to be available and usable for years and decades to come, as the basis for further research, educational projects or language revitalisation activities. Generally there is yet little awareness of the fact that the data about endangered languages are endangered themselves. This talk presents the activities and solutions being developed at The Language Archive at the Max-Planck-Institute for Psycholinguistics in Nijmegen that aim at providing tools and an infrastructure that supports the creation and long-term archiving of precious language data

Optical Conductivity of Clean Metals

We briefly review some basic aspects of transport in clean metals focusing on the role of electron-electron interactions and neglecting the effects of impurities, phonons and interband transitions. Both for small Fermi surfaces of two and three-dimensional metals and open Fermi surfaces of quasi one-dimensional metals the dc conductivity sigma is largely dominated by momentum and pseudo-momentum conservation, respectively. In general, the frequency and temperature dependencies of sigma(w,T) have very little in common. For small Fermi surfaces in three dimensions we find for example that the scattering rate is quadratic in frequency, Gamma \propto w^2, even in the absence of a T^2 contribution.Comment: invited paper for a special edition of Annalen der Physik commemorating P. Drud

Nasal harmony in Awetí ‐ A declarative account

This article describes and analyses nasal harmony (or spreading of nasality) in Awetí. It first shows generally how sounds in prefixes adapt to nasality or orality of stems, and how nasality in stems also ‘extends’ to the left. With abstract templates we show which phonetically nasal or oral sequences are possible in Awetí (focusing on stops, pre-nasalized stops and nasals) and which phonological analysis is appropriate for account for this regularities. In Awetí, there are intrinsically nasal and oral vowels and ‘neutral’ vowels which adapt phonetically to a following vowel or consonant, as is the case of sonorant consonants. Pre-nasalized stops such as “nt” are nasalized variants of stops, not post-oralized variants of nasals as in Tupí-Guaranian languages. For nasals and stops in syllable coda (end of morphemes), we postulate arqui-phonemes which adapt to the preceding vowel or a following consonant. Finally, using a declarative approach, the analysis formulates ‘rules’ (statements) which account for the ‘behavior’ of nasality in Awetí words, making use of “structured sequences” on both the phonetic and phonological levels. So, each unit (syllable, morpheme, word etc.) on any level has three components, a sequence of segments, a constituent structure (where pre-nasalized stops, like diphthongs, correspond to two segments), and an intonation structure. The statements describe which phonetic variants can be combined (concatenated) with which other variants, depending on their nasality or orality

Unified description of ballistic and diffusive carrier transport in semiconductor structures

A unified theoretical description of ballistic and diffusive carrier transport in parallel-plane semiconductor structures is developed within the semiclassical model. The approach is based on the introduction of a thermo-ballistic current consisting of carriers which move ballistically in the electric field provided by the band edge potential, and are thermalized at certain randomly distributed equilibration points by coupling to the background of impurity atoms and carriers in equilibrium. The sum of the thermo-ballistic and background currents is conserved, and is identified with the physical current. The current-voltage characteristic for nondegenerate systems and the zero-bias conductance for degenerate systems are expressed in terms of a reduced resistance. For arbitrary mean free path and arbitrary shape of the band edge potential profile, this quantity is determined from the solution of an integral equation, which also provides the quasi-Fermi level and the thermo-ballistic current. To illustrate the formalism, a number of simple examples are considered explicitly. The present work is compared with previous attempts towards a unified description of ballistic and diffusive transport.Comment: 23 pages, 10 figures, REVTEX

Psycholinguistik

5.1 Einführung in den Forschungsbereich Die Psycholinguistik ist der Bereich der Linguistik, der sich mit dem Zusammenhang zwischen menschlicher Sprache und dem Denken und anderen mentalen Prozessen beschäftigt, d.h. sie stellt sich einer Reihe von essentiellen Fragen wie etwa (1) Wie schafft es unser Gehirn, im Wesentlichen akustische und visuelle kommunikative Informationen zu verstehen und in mentale Repräsentationen umzusetzen? (2) Wie kann unser Gehirn einen komplexen Sachverhalt, den wir anderen übermitteln wollen, in eine von anderen verarbeitbare Sequenz von verbalen und nonverbalen Aktionen umsetzen? (3) Wie gelingt es uns, in den verschiedenen Phasen des Lebens Sprachen zu erlernen? (4) Sind die kognitiven Prozesse der Sprachverarbeitung universell, obwohl die Sprachsysteme derart unterschiedlich sind, dass sich in den Strukturen kaum Universalien finden lassen

Pinning and depinning of a classic quasi-one-dimensional Wigner crystal in the presence of a constriction

We studied the dynamics of a quasi-one-dimensional chain-like system of charged particles at low temperature, interacting through a screened Coulomb potential in the presence of a local constriction. The response of the system when an external electric field is applied was investigated. We performed Langevin molecular dynamics simulations for different values of the driving force and for different temperatures. We found that the friction together with the constriction pins the particles up to a critical value of the driving force. The system can depin \emph{elastically} or \emph{quasi-elastically} depending on the strength of the constriction. The elastic (quasi-elastic) depinning is characterized by a critical exponent $\beta\sim0.66$ ($\beta\sim0.95$). The dc conductivity is zero in the pinned regime, it has non-ohmic characteristics after the activation of the motion and then it is constant. Furthermore, the dependence of the conductivity with temperature and strength of the constriction was investigated in detail. We found interesting differences between the single and the multi-chain regimes as the temperature is increased.Comment: 18 pages, 16 figures, accepted for publication in PR