Two different operation regimes of fiber laser based on nonlinear polarization rotation : passive mode-locking and multiwavelength emission

We have proposed and demonstrated a nonlinear polarization-rotation-based fiber laser with two different operation states: passive mode-locking and multiwavelength emission. The intensity-dependent transmission or loss induced by nonlinear polarization rotation accounts for the distinct operation regimes. Our experiment results indicate that both passively mode-locked pulses and continuous-wave multiwavelength can be generated from the same fiber laser just through adjusting polarizations. Another characteristic of the current multiwavelength laser is that the used periodic filter is a birefringence fiber filter, which facilitates all-fiber integration of the fiber laser, so it is a potential multifunction laser source with all-fiber configuration and convenient manipulation. © 2008 IEEE.

Multiwavelength fiber laser based on nonlinear polarization rotation

Multiwavelength fiber laser is a perfect light source for future wavelength-division-multiplexing optical communication systems. A multiwavelength fiber laser based on nonlinear polarization rotation with up to 18 wavelengths has been proposed and demonstrated. The intensity- and wavelength-dependent loss induced by nonlinear polarization rotation effect is used to alleviate the mode competition in the homogeneous broadening gain medium of erbium-doped fiber. Instead of traditional filters, a polarization-maintaining fiber is inserted into the laser cavity, with which the polarization-dependent isolator composes an equivalent Lyot birefringent fiber filter. The in-line birefringence fiber filter is used to simplify the laser configuration, which benefits systematic integration. The effect of the 980 nm pump power on the multiwavelength generation is investigated. It is shown that the pump power contributes a lot to the evenness of the multiwavelength spectra due to the intensity dependence of nonlinear polarization rotation effect.

Nonlinear pulse shaping and polarization dynamics in mode-locked fibre lasers

We review our recent progress on the study of new nonlinear mechanisms of pulse shaping in passively mode-locked fibre lasers. These include a mode-locking regime featuring pulses with a triangular distribution of the intensity, and spectral compression arising from nonlinear pulse propagation. We also report on our recent experimental studies unveiling new families of vector solitons with precessing states of polarization for multipulsing and bound-state soliton operations in a carbon nanotube mode-locked fibre laser with anomalous dispersion cavity. © 2013 IEEE.

Diversity in goal-orientation, team reflexivity, and team performance

Although recent research highlights the role of team member goalorientation in team functioning, research has neglected the effects of diversity in goalorientation. In a laboratory study with groups working on a problem-solving task, we show that diversity in learning and performanceorientation are related to decreased group performance. Moreover, we find that the effect of diversity in learning orientation is mediated by group information elaboration and the effect of diversity in performanceorientation by group efficiency. In addition, we demonstrate that teamreflexivity can counteract the negative effects of diversity in goalorientation. These results suggest that models of goal orientation in groups should incorporate the effects of diversity in goal orientation.

Celiac disease patient IgA antibodies induce endothelial adhesion and cell polarization defects via extracellular transglutaminase 2

We have recently found that celiac disease patient serum-derived autoantibodies targeted against transglutaminase 2 interfere with several steps of angiogenesis, including endothelial sprouting and migration, though the mechanism involved remained to be fully characterized. This study now investigated the processes underlying the antiangiogenic effects exerted by celiac disease patient antibodies on endothelial cells, with particular regard to the adhesion, migration, and polarization signaling pathway. We observed that celiac IgA reduced endothelial cell numbers by affecting adhesion without increasing apoptosis. Endothelial cells in the presence of celiac IgA showed weak attachment, a high susceptibility to detach from fibronectin, and a disorganized extracellular matrix due to a reduction of protein cross-links. Furthermore, celiac patient IgA led to secretion of active transglutaminase 2 from endothelial cells into the culture supernatants. Additionally, cell surface transglutaminase 2 mediated integrin clustering in the presence of celiac IgA was coupled to augmented expression of ß1-integrin. We also observed that celiac patient IgA-treated endothelial cells had migratory defects and a less polarized phenotype when compared to control groups, and this was associated with the RhoA signaling pathway. These biological effects mediated by celiac IgA on endothelial cells were partially influenced but not completely abolished by R281, an irreversible extracellular transglutaminase 2 enzymatic activity inhibitor. Taken together, our results imply that celiac patient IgA antibodies disturb the extracellular protein cross-linking function of transglutaminase 2, thus altering cell-extracellular matrix interactions and thereby affecting endothelial cell adhesion, polarization, and motility. © 2013 Springer Basel.

Tunable multiwavelength SOA fiber laser with ultra-narrow wavelength spacing based on nonlinear polarization rotation

A tunable multiwavelength fiber laser with ultra-narrow wavelength spacing and large wavelength number using a semiconductor optical amplifier (SOA) has been demonstrated. Intensity-dependent transmission induced by nonlinear polarization rotation in the SOA accounts for stable multiwavelength operation with wavelength spacing less than the homogenous broadening linewidth of the SOA. Stable multiwavelength lasing with wavelength spacing as small as 0.08 nm and wavelength number up to 126 is achieved at room temperature. Moreover, wavelength tuning of 20.2 nm is implemented via polarization tuning.

All-fiber normal-dispersion single-polarization passively mode-locked laser based on a 45°-tilted fiber grating

An all-fiber normal-dispersion Yb-doped fiber laser with 45- tilted fiber grating (TFG) isto the best of our knowledgeexperimentally demonstrated for the first time. Stable linearly-chirped pulses with the duration of 4 ps and the bandwidth of 9 nm can be directly generated from the laser cavity. By employing the 45 TFG with the polarization-dependent loss of 33 dBoutput pulses with high polarization extinction ratio of 26 dB are implemented in the experiment. Our result shows that the 45 TFG can work effectively as a polarizerwhich could be exploited to singlepolarization all-fiber lasers.

Nonlinear pulse shaping and polarization dynamics in mode-locked fibre lasers

We review our recent progress on the study of new nonlinear mechanisms of pulse shaping in passively mode-locked fibre lasers. These include a mode-locking regime featuring pulses with a triangular distribution of the intensity, and spectral compression arising from nonlinear pulse propagation. We also report on our recent experimental studies unveiling new families of vector solitons with precessing states of polarization for multipulsing and bound-state soliton operations in a carbon nanotube mode-locked fibre laser with anomalous dispersion cavity. © 2013 IEEE.

Audience design in the police interview:the interactional and judicial consequences of audience orientation

Police-suspect interviews in England & Wales are a multi-audience, multi-purpose, transcontextual mode of discourse. They are conducted as part of the initial investigation into a crime, but are subsequently recontextualised through the judicial process, ultimately being presented in court as evidence against the interviewee. The communicative challenges posed by multiple future audiences are investigated by applying Bell’s (1984) audience design model to the police interview, and the resulting "poor fit" demonstrates why this context is discursively counter-intuitive to participants. Further, data analysis indicates that interviewer and interviewee, although ostensibly addressing each other, may orientate to different audiences, with potentially serious consequences. As well as providing new insight into police-suspect interview interaction, this article seeks to extend understanding of the influence of audience on interaction at the discourse level, and to contribute to the development of theoretical models for contexts with multiple or asynchronous audiences.

Polarization attractors in harmonic mode-locked fiber laser

We report on a polarimetry of harmonic mode-locked erbium-doped fiber laser with carbon nanotubes saturable absorber. We find new types of vector solitons with locked, switching and precessing states of polarization. The underlying physics presents interplay between birefringence of a laser cavity created by polarization controller along with light induced anisotropy caused by polarization hole burning. © 2014 Optical Society of America.

The social and entrepreneurial orientation of small businesses:mutually exclusive or reinforcing? (INTERACTIVE PAPER)

Principal Topic - As argued by Acs and Phillips (2002) it is not only “the creation of wealth (entrepreneurship)” but also “the reconstitution of wealth (philanthropy)”, which has been essential for the inherent dynamism of the market economy (Ibid., p.201). However, we understand little about the entrepreneurship – philanthropy link in institutional contexts that differ from that of leading developed market economies. Accordingly our research agenda is to investigate the entrepreneurship-philanthropy nexus in a very different context of Lithuania, a country which shed a command economy system twenty years ago. In particular, we are interested to see if the cluster of attitudes and strategies of firms conducive to entrepreneurship, i.e. their entrepreneurial orientation (Covin & Slevin, 1989), is consistent or contradictory with philanthropy? In other words, is philanthropy strongly associated with some core components of entrepreneurship, or is it an entrepreneurial anomaly, relying on a minority of economic actors that provide important links with wider, non-economic communities. Method - The study draws on 270 randomly sampled, phone interviews with owners and ownermanagers of small and medium-sized enterprises (SMEs), i.e. firms with less than 250 employees. Interviews were conducted in Lithuania during January- March, 2008. Our results are based on confirmatory factor analysis combined with regression analysis. Results and Implications - Despite the legacy of informal institutions that is conducive neither to entrepreneurship nor to civic society, we found that by now, (i) the companies that score highest on entrepreneurial orientation construct, (ii) that perform best and those (iii) that have foreign owners are also most likely to declare their commitment to philanthropy. Our findings that most entrepreneurial firms are also involved in philanthropy are consistent with the perspective on the pattern of development in an entrepreneurial economy as outlined by Acs and Phillips (2002).

Bending characteristics of fiber long-period gratings with cladding index modified by femtosecond laser

A femtosecond laser has been used to asymmetrically modify the cladding of fiber containing long-period gratings. Following modification, devices in single-mode fiber are shown to be capable of sensing the magnitude and direction of bending in one plane by producing blue and red wavelength shifts depending upon the orientation of the bend. The resulting curvature sensitivities were -1.62 and +3.82 nm·m. Devices have also been produced using an elliptical core fiber to study the effects of the cladding modification on the two polarization eigenstates. A cladding modification applied on the fast axis of the fiber is shown to affect the light in the fast axis much more significantly than the light in the orthogonal state; this behavior may ultimately lead to a sensor capable of detecting the direction of bending in two dimensions for applications in shape sensing. © 2006 IEEE.

Cognitive orientation type as a source of individual differences in information processing

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Preferred orientation in 18/10, 18/12 and 18/14 chromium/nickel steels and its relation to tensile and press forming properties

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