Phase dependent forward three wave amplification in photorefractive BSO

The results of three wave mixing experiments in photorefractive Bi12SiO20 are presented. The results confirm theoretical predictions that amplification by three wave mixing is strongly dependent on the phase relationship between the three beams at the input to the medium.

Phase dependent forward three wave amplification in photorefractive BSO

The results of three wave mixing experiments in photorefractive Bi12SiO20 are presented. The results confirm theoretical predictions that amplification by three wave mixing is strongly dependent on the phase relationship between the three beams at the input to the medium.

One-dimensional optical wave turbulence:experiment and theory

We present a review of the latest developments in one-dimensional (1D) optical wave turbulence (OWT). Based on an original experimental setup that allows for the implementation of 1D OWT, we are able to show that an inverse cascade occurs through the spontaneous evolution of the nonlinear field up to the point when modulational instability leads to soliton formation. After solitons are formed, further interaction of the solitons among themselves and with incoherent waves leads to a final condensate state dominated by a single strong soliton. Motivated by the observations, we develop a theoretical description, showing that the inverse cascade develops through six-wave interaction, and that this is the basic mechanism of nonlinear wave coupling for 1D OWT. We describe theory, numerics and experimental observations while trying to incorporate all the different aspects into a consistent context. The experimental system is described by two coupled nonlinear equations, which we explore within two wave limits allowing for the expression of the evolution of the complex amplitude in a single dynamical equation. The long-wave limit corresponds to waves with wave numbers smaller than the electrical coherence length of the liquid crystal, and the opposite limit, when wave numbers are larger. We show that both of these systems are of a dual cascade type, analogous to two-dimensional (2D) turbulence, which can be described by wave turbulence (WT) theory, and conclude that the cascades are induced by a six-wave resonant interaction process. WT theory predicts several stationary solutions (non-equilibrium and thermodynamic) to both the long- and short-wave systems, and we investigate the necessary conditions required for their realization. Interestingly, the long-wave system is close to the integrable 1D nonlinear Schrödinger equation (NLSE) (which contains exact nonlinear soliton solutions), and as a result during the inverse cascade, nonlinearity of the system at low wave numbers becomes strong. Subsequently, due to the focusing nature of the nonlinearity, this leads to modulational instability (MI) of the condensate and the formation of solitons. Finally, with the aid of the probability density function (PDF) description of WT theory, we explain the coexistence and mutual interactions between solitons and the weakly nonlinear random wave background in the form of a wave turbulence life cycle (WTLC).

Dynamics of vector rogue waves in a fiber laser with a ring cavity

A pulse–pulse interaction that leads to rogue wave (RW) generation in lasers was previously attributed either to soliton–soliton or soliton–dispersive-wave interaction. The beating between polarization modes in the absence of a saturable absorber causes similar effects. Accounting for these polarization modes in a laser resonator is the purpose of the distributed vector model of laser resonators. Furthermore, high pump power, high amplitude, and short pulse duration are not necessary conditions to observe pulse attraction, repulsion, and collisions and the resonance exchange of energy between among them. The regimes of interest can be tuned just by changing the birefringence in the cavity with the pump power slightly higher than the laser threshold. This allows the observation of a wide range of RW patterns in the same experiment, as well as to classify them. The dynamics of the interaction between pulses leads us to the conclusion that all of these effects occur due to nonlinearity induced by the inverse population in the active fiber as well as an intrinsic nonlinearity in the passive part of the cavity. Most of the mechanisms of pulse–pulse interaction were found to be mutually exclusive. This means that all the observed RW patterns, namely, the “lonely,” “twins,” “three sisters,” and “cross,” are probably different cases of the same process.

Employee social responsibility:development of an ESR measure and a multi-level investigation of antecedent and boundary conditions

The following thesis instigates the discussion on corporate social responsibility (CSR) through a review of literature on the conceptualisation, determinants, and remunerations of organisational CSR engagement. The case is made for the need to draw attention to the micro-levels of CSR, and consequently focus on employee social responsibility at multiple levels of analysis. In order to further research efforts in this area, the prerequisite of an employee social responsibility behavioural measurement tool is acknowledged. Accordingly, the subsequent chapters outline the process of scale development and validation, resulting in a robust, reliable and valid employee social responsibility scale. This scale is then put to use in a field study, and the noteworthy roles of the antecedent and boundary conditions of transformational leadership, assigned CSR priority, and CSR climate are confirmed at the group and individual level. Directionality of these relationships is subsequently alluded to in a time-lagged investigation, set within a simulated business environment. The thesis collates and discusses the contributions of the findings from the research series, which highlight a consistent three-way interaction effect of transformational leadership, assigned CSR priority and CSR climate. Specifically, efforts are made to outline various avenues for future research, given the infancy of the micro-level study of employee social responsibility.

The Role of the big five personality traits, proactive behaviour, and socialisation influences in newcomer adjustment

During the early stages of employment, newly hired employees find out what their new organisations are like. Their first impressions are extremely important in determining the course of subsequent attitudes and behaviour. Recently, a considerable progress has been made towards the understanding of adjustment process, however, the literature remain divided along a number of fronts. Moreover, newcomer research has been conducted independent and irrespective of newcomer personality individual differences. This seems to be a critical oversight because there is overlap in predictions involving these constructs. The current research extended the previous one by examining these multiple antecedents, including Big Five personality traits of newcomer to the tandem process of adjustment as well as outcomes that immediate, or ?proximal? to the process of newcomer adjustment. Following a cross sectional pilot study of recent college graduate, a three- wave longitudinal study of newcomers in seven organisations examined Big Five personality traits, proactive behaviour, and socialisation influence (formal training, leaders, co-workers) as antecedents of proximal adjustment outcomes (group integration, political knowledge of organisation, and task performance). The main study results suggested that personality traits were related to proximal adjustment outcomes, specifically, Conscientiousness was positively related to all proximal adjustment outcomes. Openness to experience was related to task performance and political knowledge. Group integration is independently related to Agreeableness, Extraversion and Neuroticism. The socialisation influence moderate these relations, for example, leader socialisation moderate Conscientiousness as it relates to political knowledge and group integration, while co-worker moderate Extraversion as it relates to task performance. Finally, it was found that, the relationship between proximal adjustment outcomes and the personality dimensions Openness was mediated by proactive behaviour. Overall, the results suggested that individual differences have a role in newcomer adjustment as it facilitate the socialisation influence, and Big Five was one of the key determinants of newcomer adjustment.

How brand attribute typicality and consumer commitment moderate the influence of comparative advertising

This study examines how product attribute typicality and brand commitment influence the effects of comparative versus non-comparative ads on brand attitudes. Employing perspectives from the literatures on typicality and commitment, the study examines the effects of commitment to the comparison brand on the effectiveness of comparative versus non-comparative advertising. A between-informants experiment uses data from 466 student informants. It is hypothesized that (a) when the attribute under consideration is typical (atypical), among comparison brand committed informants, a non-comparative ad is more (no more) persuasive than a comparative ad, (b) when the attribute under consideration is typical, among comparison brand non-committed informants, a comparative ad is more persuasive than a non-comparative ad, and (c) when the attribute under consideration is atypical, among comparison brand non-committed informants, a comparative ad is likely to be more persuasive than a non-comparative ad, but the effect will be weaker than in the case of a typical attribute. Hypothesis (a) is supported while (b) has directional support. The results support a three-way interaction between consumer commitment, attribute typicality, and type of advertisement. The findings are relevant to a variety of contexts, such as markets characterized by high levels of market share and commitment for the market leader as well as fragmented markets where market share and commitment levels are low.

Trust in leader-follower relationships:how and when trust building enhances dyadic and organisational outcomes

Guided by theory in both the trust and leadership domains, the overarching aim of this thesis was to answer a fundamental question. Namely, how and when does trust-building between leaders and followers enhance leader-member exchange (LMX) development and organisational trust? Although trust is considered to be at the crux of the leader-follower relationship, surprisingly little theoretical or empirical attention has been devoted to understanding the precise nature of this relationship. By integrating both a typology of trustworthy behaviour and a process model of trust development with LMX theory, study one developed and tested a new model of LMX development with leader-follower trust-building as the primary mechanism. In a three wave cross-lagged design, 294 student dyads in a business simulation completed measures of trust perceptions and LMX across the first 6 months of the LMX relationship. Trust-building was found to account for unexplained variance in the LMX construct over time, while controlling for initial relationship quality, thus confirming the critical role of the trust-building process in LMX development. The strongest evidence was found for the role of integrity-based trust-building behaviour, albeit only when such behaviour was not attributed to insincere motives. The results for ability and benevolence-based trustworthy behaviour revealed valued insights into the developmental nature of trustworthiness perceptions within LMX relationships. Thus, the pattern of results in study one provided a more comprehensive and nuanced understanding of the dynamic interplay between trust and LMX. In study two, leader trust-building was investigated cross-sectionally within an organisational sample of 201 employees. The central aim of this study was to investigate whether leader trust-building within leader-follower relationships could be leveraged for organisational trust. As expected, the trust-building process instigated by members in study one was replicated for leaders in study two. In addition, the results were most consistent for benevolence-based trust building, whereas both integrity- and ability-based trust-building were moderated by the position of the leader within the organisation’s hierarchy. Overall, the findings of this thesis shed considerable light on the richness of trusting perceptions in organisations, and the critical role of trust-building in LMX development and organisational trust.

Wave chaotic behaviour generated by linear systems

It is shown that regimes with dynamical chaos are inherent not only to nonlinear system but they can be generated by initially linear systems and the requirements for chaotic dynamics and characteristics need further elaboration. Three simplest physical models are considered as examples. In the first, dynamic chaos in the interaction of three linear oscillators is investigated. Analogous process is shown in the second model of electromagnetic wave scattering in a double periodical inhomogeneous medium occupying half-space. The third model is a linear parametric problem for the electromagnetic field in homogeneous dielectric medium which permittivity is modulated in time. © 2008 Springer Science+Business Media, LLC.

Interaction of calcitonin-gene-related peptide with its receptors

The receptor for calcitonin-gene-related peptide (CGRP) is a heterodimer formed by calcitonin-receptor-like receptor (CRLR), a type II (family B) G-protein-coupled receptor, and receptor-activity-modifying protein 1 (RAMP1), a single-membrane-pass protein. It is likely that the first seven or so amino acids of CGRP (which form a disulphide-bonded loop) interact with the transmembrane domain of CRLR to cause receptor activation. The rest of the CGRP molecule falls into three domains. Residues 28-37 and 8-18 are normally required for high-affinity binding, while residues 19-27 form a hinge region. The 28-37 region is almost certainly in direct contact with the receptor; 8-18 may make additional receptor contacts or may stabilize an appropriate conformation of 28-37. It is likely that these regions of CGRP interact both with CRLR and with the extracellular domain of RAMP1.

Probing three-way interactions in moderated multiple regression:Development and application of a slope difference test

Researchers often use 3-way interactions in moderated multiple regression analysis to test the joint effect of 3 independent variables on a dependent variable. However, further probing of significant interaction terms varies considerably and is sometimes error prone. The authors developed a significance test for slope differences in 3-way interactions and illustrate its importance for testing psychological hypotheses. Monte Carlo simulations revealed that sample size, magnitude of the slope difference, and data reliability affected test power. Application of the test to published data yielded detection of some slope differences that were undetected by alternative probing techniques and led to changes of results and conclusions. The authors conclude by discussing the test's applicability for psychological research. Copyright 2006 by the American Psychological Association.

Three-factor models versus time series models:quantifying time-dependencies of interactions between stimuli in cell biology and psychobiology for short longitudinal data

Signal integration determines cell fate on the cellular level, affects cognitive processes and affective responses on the behavioural level, and is likely to be involved in psychoneurobiological processes underlying mood disorders. Interactions between stimuli may subjected to time effects. Time-dependencies of interactions between stimuli typically lead to complex cell responses and complex responses on the behavioural level. We show that both three-factor models and time series models can be used to uncover such time-dependencies. However, we argue that for short longitudinal data the three factor modelling approach is more suitable. In order to illustrate both approaches, we re-analysed previously published short longitudinal data sets. We found that in human embryonic kidney 293 cells cells the interaction effect in the regulation of extracellular signal-regulated kinase (ERK) 1 signalling activation by insulin and epidermal growth factor is subjected to a time effect and dramatically decays at peak values of ERK activation. In contrast, we found that the interaction effect induced by hypoxia and tumour necrosis factor-alpha for the transcriptional activity of the human cyclo-oxygenase-2 promoter in HEK293 cells is time invariant at least in the first 12-h time window after stimulation. Furthermore, we applied the three-factor model to previously reported animal studies. In these studies, memory storage was found to be subjected to an interaction effect of the beta-adrenoceptor agonist clenbuterol and certain antagonists acting on the alpha-1-adrenoceptor / glucocorticoid-receptor system. Our model-based analysis suggests that only if the antagonist drug is administer in a critical time window, then the interaction effect is relevant.