Dissipative solitons in pattern-forming nonlinear optical systems : cavity solitons and feedback solitons

Many dissipative optical systems support patterns. Dissipative solitons are generally found where a pattern coexists with a stable unpatterned state. We consider such phenomena in driven optical cavities containing a nonlinear medium (cavity solitons) and rather similar phenomena (feedback solitons) where a driven nonlinear optical medium is in front of a single feedback mirror. The history, theory, experimental status, and potential application of such solitons is reviewed

Fundamentals and applications of spatial dissipative solitons in photonic devices : [Chapter 6]

We review the properties of optical spatial dissipative solitons (SDS). These are stable, self‐localized optical excitations sitting on a uniform, or quasi‐uniform, background in a dissipative environment like a nonlinear optical cavity. Indeed, in optics they are often termed “cavity solitons.” We discuss their dynamics and interactions in both ideal and imperfect systems, making comparison with experiments. SDS in lasers offer important advantages for applications. We review candidate schemes and the tremendous recent progress in semiconductor‐based cavity soliton lasers. We examine SDS in periodic structures, and we show how SDS can be quantitatively related to the locking of fronts. We conclude with an assessment of potential applications of SDS in photonics, arguing that best use of their particular features is made by exploiting their mobility, for example in all‐optical delay lines

Economic organisation of Polynesian societies: wealth and work of the Maori

This thesis is a study in economic anthropology. Opening with a critical estimate of the work previously done in the subject, it proceeds to an analysis of the economic life of the Maori, the method of functional observation and the correlation being followed. An account is first given of the environmental conditions of the native and the natural resources at his command. The social structure of the Maori community is then analysed and its relation to the economic organisation shown, special consideration being given to the problem of the position of the family in native life. By following the sequence of operation in a typical industry - bird snaring - it is shown how complex is the psychology of the Maori in his work, how motives of pleasure, pride, vanity and ambition round off the more purely utilitarian interests. Reference to other activities again proves that the native is capable of steady and industrious labour, when the proper stimuli are provided. The different forms of organisation in production are next described, with attention to the nature of leadership. The place of magic in economic life is reviewed at length, owing to its vital importance in assisting the stability and organisation of the work. A further set of problems is opened by consideration of the methods and principles of sharing out the product of labour as well as those of the ownership of the property, and the tenure of land. The nature of primitive economic values and of the system of exchange examined, while with the aid of maps the extensive nature of communication in oldern times is revealed. The radical alteration in the Maori economic structure consequent upon the coming of the European is analysed with its phases of initial impact, enthusiastic adoption of new culture forms, reaction, and renewed acceptance of the ways of white man. Finally it is emphasised how economic activity enlists forces of other social types to promote its own efficiency

Stability of multi-hump optical solitons

We demonstrate that, in contrast with what was previously believed, multi-hump solitary waves can be stable. By means of linear stability analysis and numerical simulations, we investigate the stability of two- and three-hump solitary waves governed by incoherent beam interaction in a saturable medium, providing a theoretical background for the experimental results reported by M. Mitchell, M. Segev, and D. Christodoulides [Phys. Rev. Lett. v. 80, p. 4657 (1998)].Comment: 4 pages, 5 figures, to appear in PR

Jacob G. Mulder Papers

The Jacob G. Mulder Papers document the life of Jacob (Jake) Mulder during the years of his military service in the First World War, 1918-1919. The collection includes correspondence between Jacob and his family and friends, newspaper clippings, army issued materials and papers, and a photograph. Collectively, these materials provide an insight of an enlisted Dutch-American farmer of the American Expeditionary Force (AEF) in Europe

Interaction of cavity solitons in degenerate optical parametric oscillators

Numerical studies together with asymptotic and spectral analysis establish regimes where soliton pairs in degenerate optical parametric oscillators fuse, repel, or form bound states. A novel bound state stabilized by coupled internal oscillations is predicted.Comment: 3 page

Rheology of protein-stabilised emulsion gels envisioned as composite networks. 1 - Comparison of pure droplet gels and protein gels

Protein-stabilised emulsion gels can be studied in the theoretical framework of colloidal gels, because both protein assemblies and droplets may be considered as soft colloids. These particles differ in their nature, size and softness, and these differences may have an influence on the rheological properties of the gels they form. Pure gels made of milk proteins (sodium caseinate), or of sub-micron protein-stabilised droplets, were prepared by slow acidification of suspensions at various concentrations. Their microstructure was characterised, their viscoelasticity, both in the linear and non-linear regime, and their frequency dependence were measured, and the behaviour of the two types of gels was compared. Protein gels and droplet gels were found to have broadly similar microstructure and rheological properties when compared at fixed volume fraction, a parameter derived from the study of the viscosity of the suspensions formed by proteins and by droplets. The viscoelasticity displayed a power law behaviour in concentration, as did the storage modulus in frequency. Additionally, strain hardening was found to occur at low concentration. These behaviours differed slightly between protein gels and droplet gels, showing that some specific properties of the primary colloidal particles play a role in the development of the rheological properties of the gels.Comment: 27 pages, 6 figure

The theory behind evidence-based practice : going beyond the surface level

When preparing teachers for practice, there are various options regarding the level of theoretical depth that teacher-educators provide, with some suggesting that guidance should eschew theory and focus on findings. In this article, I argue that developing a theoretical understanding of human cognition can help teachers to make better decisions about which strategy to use, and when. Research in cognitive psychology has uncovered a number of promising techniques that stand to improve classroom attainment (e.g. Dunlosky et al., 2013). For example, the spacing effect is where practice is distributed over a longer period of time rather than being intensive, and interleaving is where diverse examples are contrasted rather than examples presented in blocks of the same type. Teacher education should aim to develop an accurate understanding of the underlying theory among teachers. Without such a foundation, their judgements of techniques such as the spacing effect and interleaving are likely to be informed by flawed assumptions due to the fundamentally counterintuitive nature of human memory

Teachers' beliefs about memory : a vignette study of trainee and in-service teachers

Previous research has indicated that laypeople, students and legal professionals often hold flawed beliefs about memory, and the present study sought to extend this area of research to the teaching profession. Are teachers' beliefs about learning in line with the scientific consensus? A set of vignettes with contrasting options for classroom practice were presented to trainee (n = 77) and in-service (n = 44) teachers, and in each case a 7-point Likert scale prompted them to predict which would be the best course of action in terms of student outcomes. As hypothesized, responses were often out of line with research on 'desirable difficulties' in memory and learning such as retrieval practice, spacing, and interleaving, with choices indicating a lack of awareness of these evidence-based approaches, although they were more accurate than previous studies of students. Surprisingly, accuracy of response did not correlate with the duration of a teachers' classroom experience; trainee teachers outscored in-service teachers in certain areas, suggesting that recent familiarity with technical literature on learning could be advantageous

The application of spacing and interleaving approaches in the classroom

Interleving refers to the benefits of sequencing learning tasks so that similar items - two examples of the same concept, say - are interspersed with different types of itemss rather than being consecutive. This results in a more variable and challenging task but is associated with benerits in terms of memory and transfer, which to apply to conecpt learning as well as other domains. (Kang, 2016)