A review of the findings of the plasma diagnostic package and associated laboratory experiments: Implications of large body/plasma interactions for future space technology

The discoveries and experiments of the Plasma Diagnostic Package (PDP) on the OSS 1 and Spacelab 2 missions are reviewed, these results are compared with those of other space and laboratory experiments, and the implications for the understanding of large body interactions in a low Earth orbit (LEO) plasma environment are discussed. First a brief review of the PDP investigation, its instrumentation and experiments is presented. Next a summary of PDP results along with a comparison of those results with similar space or laboratory experiments is given. Last of all the implications of these results in terms of understanding fundamental physical processes that take place with large bodies in LEO is discussed and experiments to deal with these vital questions are suggested

The Investigation of Code-Switching in a Computerised Corpus of Child Bilingual Language

This dissertation describes the investigation of codeswitching in a computerised corpus of child bilingual language, the LOBILL Corpus, which consists of twenty-five hours of recordings of naturalistic interactions between two bilingual Brazilian/English siblings (JAM, 3;6 and MEG, 5;10) and their family members. Collected over three years, the data was transcribed and coded using the CHAT (Codes for the Human Analysis of Transcripts) transcription system developed by MacWhinney and colleagues (MacWhinney, 1991). In addition to standard CHAT coding, language codes were inserted throughout the corpus and a specially developed postcode was added to all bilingual utterances. Addressee information for each utterance was also included. The longitudinal and heterogenous nature of the corpus and its specific coding allowed for the comprehensive investigation of the children's code-switching practices from both grammatical and pragmatic perspectives. Three levels of analyses were performed using the CLAN (Computerized Language ANalysis) software (ibid). First, quantitative analyses were carried out using the commands FREQ (which outputs frequency word lists), VOCD (which outputs vocabulary diversity scores) and WDLEN (which outputs mean word and utterance lengths). An analysis of the results pointed to the existence of relationships between the various values found and the participatory roles of English and Portuguese in code-switched utterances. The second level of analysis involved the examination and interpretation of word lists and code lists produced by the use of FREQ. Using Myers-Scotton's 4-Morpheme Model (4-M Model) (Jake & Myers-Scotton, 2009) to interpret the word lists, comparisons of morpheme types revealed the existence of an asymmetry in terms of the contributions of both languages to bilingual utterances. These results were seen to lend support to the Matrix Language/Embedded Language asymmetry proposed in the Matrix Frame Language Model (MFL Model) (ibid). The quantitative analysis of four types of codes (used to code instances of retracings and reformulations, errors, tag questions and metalinguistic usage) provided evidence for the existence of potential relationships between these features of spoken discourse and code-switching

Dynamics of modulationally unstable ionacoustic wave packets in plasmas with negative ions

In this paper we study the propagation of nonlinear ion-acoustic waves in plasmas with negative ions. The Gardner equation governing these waves in plasmas with the negative ion concentration close to critical is derived. The weakly nonlinear theory of modulational instability based on the use of the nonlinear Schrödinger equation is discussed. The investigation of the nonlinear dynamics of modulationally unstable quasi-harmonic wavepackets is carried out by the numerical solution of the Gardner equation. The results are compared with the predictions of the weakly nonlinear theory

Self‐Refraction of Nonlinear Capillary‐Gravity Waves

Self‐refraction effects have been observed during the propagation of deep‐water capillary‐gravity waves. The observations are shown to be in qualitative agreement with the theory of self‐focusing and defocusing in a cubically nonlinear medium in the presence of diffraction

Spreading of waves in nonlinear disordered media

We analyze mechanisms and regimes of wave packet spreading in nonlinear disordered media. We predict that wave packets can spread in two regimes of strong and weak chaos. We discuss resonance probabilities, nonlinear diffusion equations, and predict a dynamical crossover from strong to weak chaos. The crossover is controlled by the ratio of nonlinear frequency shifts and the average eigenvalue spacing of eigenstates of the linear equations within one localization volume. We consider generalized models in higher lattice dimensions and obtain critical values for the nonlinearity power, the dimension, and norm density, which influence possible dynamical outcomes in a qualitative way.Comment: 24 pages, 3 figures. arXiv admin note: text overlap with arXiv:0901.441