Robert J. Williams

Human Vascular Smooth Muscle Cells Express Receptors for CC Chemokines

Arteriosclerotic lesions are characterized by the accumulation of T lymphocytes and monocytes and the proliferation of intimal smooth muscle cells. Expression of the chemokine monocyte chemoattractant protein-1 (MCP- 1) has been observed in arteriosclerotic plaques and has been proposed to mediate the transendothelial migration of mononuclear cells. More recently, MCP-1 has been proposed to affect the proliferation and migration of vascular smooth muscle cells (VSMCs). We have used reverse transcription-polymerase chain reaction (RT-PCR) to investigate chemokine mRNA expression in human arteriosclerotic lesions obtained from surgical biopsy of diseased vascular tissue and show, in addition to MCP-1, expression of the chemokine macrophage inflammatory protein-1alpha (MIP-1alpha) at higher levels than in normal aortic tissue. We have also used RT-PCR to characterize the expression of known chemokine receptors by primary human VSMCs. Messenger RNA for the MIP-1alpha/RANTES receptor, CCR-1, and the MCP-1/MCP-3 receptor, CCR-2, was expressed by unstimulated VSMCs grown under serum-free culture conditions for 24 hours. The receptors CCR-3, CCR-4, CCR-5, CXCR-1, and CXCR-2 were not expressed by VSMCs. The presence of functionally coupled receptors for MIP-1alpha on VSMCs was demonstrated by specific binding of biotinylated MIP-1alpha and increases in intracellular Ca2+ levels after exposure to this chemokine. Taken together, these results suggest that chemokines are likely to be involved in arteriosclerosis and may play a role in modulating the function of VSMCs in vivo.

Point-by-point written fiber-Bragg gratings and their application in complex grating designs

The point-by-point technique of fabricating fibre-Bragg gratings using an ultrafast laser enables complete control of the position of each index modification that comprises the grating. By tailoring the local phase, amplitude and spacing of the gratings refractive index modulations it is possible to create gratings with complex transmission and reflection spectra. We report a series of grating structures that were realized by exploiting these flexibilities. Such structures include gratings with controlled bandwidth, and amplitude- and phase-modulated sampled (or superstructured) gratings. A model based on coupled-mode theory provides important insights into the manufacture of such gratings. Our approach offers a quick and easy method of producing complex, non-uniform grating structures in both fibres and other mono-mode waveguiding structures.

Role of Sexual Orientation and Gender-Related Traits in Disordered Eating

This study was designed to examine the role of both sexual orientation and gender-related personality traits in disordered eating attitudes and behavior, including body dissatisfaction. Self-report measures assessing negative and positive gender traits,body dissatisfaction, drive for thinness, dietary restraint, and bulimic symptoms were administered to 266 participants (64 lesbians, 73 heterosexual women, 69 gay men, and 60 heterosexual men; 85% Anglo-Australian Caucasians, 15% Caucasians from Non-English-speaking backgrounds). Consistent with previous research, gay men scored significantly higher than heterosexual men on body dissatisfaction and dietary restraint, whereas lesbians scored significantly lower in comparison to the heterosexual women on body dissatisfaction, drive for thinness, dietary restraint, and bulimia. For men, the additional amount of variance accounted by the gender traits was significantly higher than that accounted for by sexual orientation. For the women, the gender traits also accounted for an additional significant amount of variance; however, overall the amount of variance accounted for by sexual orientation was greater. However, for both men and women, irrespective of their sexual orientation, it was higher scores on negative femininity that predicted higher levels of disordered eating. These results are consistent with previous studies that have found support for the femininity hypothesis in disordered eating.

Gender Traits and Self-Concept as Indicators of Problem Eating and Body Dissatisfaction Among Children

The present study was designed to examine the role of gender traits, body mass index (BMI), and self-concept in predicting levels of problem eating and body dissatisfaction among both girls and boys aged between 8 and 10 (85% were Anglo-Australian Caucasian, 15% were Caucasians from non-English backgrounds). Two hundred and two children completed questionnaires, which examined problem-eating attitudes and behaviors, body dissatisfaction, gender traits, and self-concept. Childrens height and weight were measured to determine childrens BMI. Gender traits predicted problem eating for boys but not for girls. Self-concept was found to predict problem eating for both boys and girls. BMI was also a predictor of problems for girls. The only predictor of body dissatisfaction for boys and girls was BMI. The findings are discussed in light of previous research, which has been conducted, on adolescents. Further studies are needed to understand more fully the development of problem eating and body dissatisfaction before the onset of puberty and adolescence.

Body Dissatisfaction as a Mediator of the Relationship between Dietary Restraint and Bulimic Eating Patterns

The present study was designed to test whether dietary restraint mediates the relationship between body dissatisfaction and bulimic eating patterns in a sample of 172 university females. Contrary to what was expected the results showed that body dissatisfaction mediated the relationship between dietary restraint and bulimic patterns of eating. Thus the results highlight the primary importance of body dissatisfaction as a predictor of bulimic behavior. Body dissatisfaction encompasses a broad array of dimensions such as self-perceptions, cognitions, affect and behavior and it carries enormous explanatory power but its different components remain largely unexplored.

Gender stereotypes and drinking cognitions as indicators of moderate and high risk drinking among young women and men

The study examined differences in gender stereotypes, restrained drinking and self-efficacy for alcohol refusal between moderate and high risk drinkers among a university sample of 301 women and 118 men. Both female and male high risk drinkers displayed a response conflict, typified by high scores on restrained drinking but low scores on self-efficacy. This pattern of response conflict was more pronounced for high risk drinking women, who also identified poorly with feminine traits (e.g. nurturing, love children, appreciative). The findings are discussed in relation to societys double standard that accepts intoxication in men but condemns it in women.

Femtosecond direct-writing of low-loss fiber Bragg gratings using a continuous core-scanning technique.

We report the inscription of low-loss fiber Bragg gratings using focused femtosecond (fs) pulses and a continuous core-scanning technique. This direct-write technique produces high-fidelity Type I-IR gratings that share the inherent advantages of other direct-write methods, such as the point-by-point (PbP) method, for which the grating period is a free parameter. However, here we demonstrate an order of magnitude improvement in scattering loss compared to PbP gratings, to a level comparable with that of phase-mask-based fs inscription. A first-order grating was inscribed in standard telecommunications fiber with -49 dB transmission at the Bragg wavelength and 0.1 dB broadband scattering loss. Potential application of these gratings to large-mode-area fibers and chirped grating fabrication are highlighted.

Polarization-dependent effects in point-by-point fiber Bragg gratings enable simple, linearly polarized fiber lasers

Fiber Bragg gratings inscribed with a femtosecond laser using the point-by-point (PbP) technique have polarization dependent grating strength (PDGS) and exhibit birefringence. In this paper we quantify the dependence of these two properties on the ellipticity, position in the core and size of the micro-voids at the center of each refractive index modulation. We demonstrate that the effective modal index for type II gratings written with a femtosecond laser using the PbP method must be lower than that of the pristine fiber, and for the first time associate an axis with a polarization such that the long axis of the elliptically-shaped index modulations corresponds to the slow axis of the gratings. We exploit the PDGS of two gratings used as frequency-selective feedback elements as well as appropriate coiling, to realize a linearly-polarized fiber laser with a low birefringence fiber cavity. We show that the polarization-dependent grating strength is a function of the writing pulse energy and that only gratings optimized for this property will linearly polarize the fiber laser. The fiber lasers have high extinction ratios (>30 dB) for fiber lengths of up to 10 m and very stable polarized output powers (<0.5% amplitude fluctuations) in the range of 20-65 mW at 1540 nm. This method of polarization discrimination allows the realization of highly robust and simplified linearly polarized fiber lasers.

All-optical, actively Q-switched fiber laser

All-fiber lasers offer increased robustness and simplicity over other fiber laser systems. Current active Q-switching techniques for all-fiber lasers rely on electro-mechanical transducers to strain-tune an intra-cavity fiber-Bragg grating, which adds complexity and can lead to vibrational sensitivity. An all-optical technique for achieving active Q-switched operation is a more elegant approach and would maintain the inherent robustness and simplicity of an all-fiber laser system. In this work, we studied the optical tuning of a fiber-Bragg grating by resonant optical pumping and optimized it for application to active systems. We incorporated an optically-tunable fiber-Bragg grating into a fiber laser and demonstrated active Q-switching at 35 kHz with this all-optical, all-fiber laser system. We highlight the potential to operate at >300 kHz with the current embodiment. To our knowledge, this is the first demonstration of an optically-driven active Q-switch in a fiber laser. Further potential to operate at MHz frequencies is discussed.

Desirable and undesirable gender traits in three behavioral domains

The present study investigated the factorial validity of a four-factor model of gender stereotypes in 888 subjects (97% Anglo-Australian Caucasian). The scale reflected the constructs desirable masculinity, desirable femininity, undesirable masculinity and undesirable femininity. LISREL analyses showed that this four-factor model fitted the data better than either a two-factor model consisting of overall masculinity and femininity or an one-factor bipolar model. Furthermore, the study highlights the utility of studying both desirable and undesirable gender traits as they generally predicted different behaviors for males and females.