Spatiotemporal dynamics and optical vortices in a photorefractive phase-conjugate resonator

A truncated modal expansion approach is used to study the spatiotemporal dynamics of a phase-conjugate resonator as a function of Bragg detuning. The numerical results reveal a rich variety of behaviors. Emphasis is given to the spatial distribution of optical vortices, their trajectories and their relationship to the beam's spatial coherence. The limitations of the model are discussed and experimental results are presented for comparison with the model's predictions and assessment of its soundness

Sex difference in the endocrine response of adult domestic chickens to gonadotrophin-releasing hormone-I

The responsiveness and sensitivity to an injection of chicken [G ln8]-gonadotrophinreleasing hormone (GnRH-I) is lower, and the duration of increased plasm a luteinizing horm one (LH) is more prolonged, in laying hens than in adult cockerels (G a llu s dom esticus). This thesis sought to further characterise and establish an oestrogendependency of these sex differences in vivo and in vitro, and to determine the mechanism for sexual differentiation of GnRH-I-induced LH secretion.The magnitude and profile of the GnRH-I-stimulated LH response, and the sensitivity to GnRH-I were shown to be functions of the anterior pituitary gland. There was less LH in gonadotroph cells from laying hens than from adult cockerels, but no sex difference between juveniles. The low responsiveness to GnRH-I of laying hens was reproduced by oestrogen treatment of adult cockerels in vivo and pituitary cells from juvenile chickens in vitro, through depression of the total and readily releaseable pool (RRP) of pituitary LH. The secretion of LH from G nRH -I-stim ulated isolated pituitary glands was biphasic, consisting of a spike and a plateau. Sexual differentiation of the magnitude of the spike of LH release was determined by the smaller RRP of LH, and the absence of an extracellular Ca2+-independent and an L-type-Ca2+ channel-dependent component of LH secretion from pituitary glands from laying hens, compared with that from adult cockerels. A decrease in spike-to-plateau phase ratio of G nRH-I-induced LH secretion was observed in vitro in pituitary glands from hens at onset of sexual maturity. This decrease in ratio was simulated in pituitary glands from adult cockerels in vitro after incubation with 17B-oestradiol. The membrane fluidity of pituitary cells from laying hens was low er than that from adult cockerels and shown to be induced in pituitary cells from juvenile chickens by treatment with 176-oestradiol. A ttem pts to establish an oestrogen-dependency of the sexually differentiated sensitivity of adult chickens to GnRH-I, or to relate it to a sex difference in pituitary G nRH -receptors were unsuccessful. The sex difference in G nRH -I-induced duration of increased plasma LH could not be reproduced in vitro and therefore depends on an extrapituitary mechanism.These sex differences becam e fully established after sexual m aturation, with sim ilar GnRH-I-induced LH responses being found in adult cockerels and juveniles o f both sex. It is therefore concluded that sexual differentiation of these LH responses results from the maturational increase in plasma 1713-oestradiol in hens

Spatiotemporal behavior and nonlinear dynamics in a phase conjugate resonator

The work described can be divided into two parts. The first part is an investigation of the transient behavior and stability property of a phase conjugate resonator (PCR) below threshold. The second part is an experimental and theoretical study of the PCR's spatiotemporal dynamics above threshold. The time-dependent coupled wave equations for four-wave mixing (FWM) in a photorefractive crystal, with two distinct interaction regions caused by feedback from an ordinary mirror, was used to model the transient dynamics of a PCR below threshold. The conditions for self-oscillation were determined and the solutions were used to define the PCR's transfer function and analyze its stability. Experimental results for the buildup and decay times confirmed qualitatively the predicted behavior. Experiments were carried out above threshold to study the spatiotemporal dynamics of the PCR as a function of Pragg detuning and the resonator's Fresnel number. The existence of optical vortices in the wavefront were identified by optical interferometry. It was possible to describe the transverse dynamics and the spatiotemporal instabilities by modeling the three-dimensional-coupled wave equations in photorefractive FWM using a truncated modal expansion approach

The Integrated Process Model For Learning Organization

This paper proposes an integrated process model of a learning organization, which consists of six processes - “sensing”, “innovating”, “selecting”, “implementing”, “diffusing”, “feedback”, and one base - “knowledge base & knowledge management”. Based on the literature review and the interviews with multinational corporations in China, this model integrates the important organizational learning processes and knowledge management to reflect the reality of learning organizations comprehensively. Based on the integrated model, key elements that affect organizational learning processes are identified. Finally, the contributions, implications, limitation, and future research of the integrated process model are discussed

An Empirical Study of the Impact of Social Media on Consumer Music Advocacy

Social media is widely used to build social network to promote product and service brands. It is very important to examine how people’s online community activities and motivation influence their positive word-of-mouth behavior. In this study, we build a framework on how music consumers’ consumption experience, consumer online engagement, and consumer online motivation influence their advocacy behavior. With more than 1000 respondents in a nation-wide survey, we have validated our measures, tested our model, and confirmed our hypotheses. Furthermore, we have discussed the theoretical and managerial implications. Finally, the limit of the research and future research are indicated