Spatial beam self-cleaning in second-harmonic generation

We experimentally demonstrate the spatial self-cleaning of a highly multimode optical beam, in the process of second-harmonic generation in a quadratic nonlinear potassium titanyl phosphate crystal. As the beam energy grows larger, the output beam from the crystal evolves from a highly speckled intensity pattern into a single, bell-shaped spot, sitting on a low energy background. We demonstrate that quadratic beam cleanup is accompanied by significant self-focusing of the fundamental beam, for both positive and negative signs of the linear phase mismatch close to the phase-matching condition

Analytical design of densely dispersion-managed optical fiber transmission systems with Gaussian and raised cosine return-to-zero Ansätze

Author name used in this publication: Y. H. C. KwanAuthor name used in this publication: P. K. A. Wai2004-2005 > Academic research: refereed > Publication in refereed journalVersion of RecordPublishe

Gender, migration and the ambiguous enterprise of professionalizing domestic service: the case of vocational training for the unemployed in France

Drawing on ethnographic data concerning migrant male domestic workers, this article examines the gendered dimensions of the process of racialization in Italy and France. First, it shows that specific racialized constructions of masculinity are mobilized by the employers as well as by training and recruitment agencies. These constructions of masculinity are related to different forms of organization of the sector in each country and to different ideologies about the integration of migrants. Second, the data presented reveal the strategies used by migrant male domestic workers to reaffirm their masculinity in a traditionally feminized sector. In doing so, this article intends to explore the connections between international migration and the gendering of occupations, with regard to the construction and management of masculinities in domestic service. Finally, by examining men’s experiences, this article aims to contribute to a more complex definition of the international division of care work

An ex-vivo Human Intestinal Model to Study Entamoeba histolytica Pathogenesis

Amoebiasis (a human intestinal infection affecting 50 million people every year) is caused by the protozoan parasite Entamoeba histolytica. To study the molecular mechanisms underlying human colon invasion by E. histolytica, we have set up an ex vivo human colon model to study the early steps in amoebiasis. Using scanning electron microscopy and histological analyses, we have established that E. histolytica caused the removal of the protective mucus coat during the first two hours of incubation, detached the enterocytes, and then penetrated into the lamina propria by following the crypts of Lieberkühn. Significant cell lysis (determined by the release of lactodehydrogenase) and inflammation (marked by the secretion of pro-inflammatory molecules such as interleukin 1 beta, interferon gamma, interleukin 6, interleukin 8 and tumour necrosis factor) were detected after four hours of incubation. Entamoeba dispar (a closely related non-pathogenic amoeba that also colonizes the human colon) was unable to invade colonic mucosa, lyse cells or induce an inflammatory response. We also examined the behaviour of trophozoites in which genes coding for known virulent factors (such as amoebapores, the Gal/GalNAc lectin and the cysteine protease 5 (CP-A5), which have major roles in cell death, adhesion (to target cells or mucus) and mucus degradation, respectively) were silenced, together with the corresponding tissue responses. Our data revealed that the signalling via the heavy chain Hgl2 or via the light chain Lgl1 of the Gal/GalNAc lectin is not essential to penetrate the human colonic mucosa. In addition, our study demonstrates that E. histolytica silenced for CP-A5 does not penetrate the colonic lamina propria and does not induce the host's pro-inflammatory cytokine secretion

Pediatric rehabilitation therapies differ in intensity: Pilot study to highlight the implications for dose-response relationships

OBJECTIVE When investigating dose-response relationships in rehabilitation studies, dose is often equated with duration of therapy. However, according to the American College of Sports Medicine, dose consists of the factors frequency, intensity, time and type. Thereby, especially quantification of intensity needs improvement to have a more precise estimate of the dose. Thus, the aim was to investigate the intensity during mobility-focused, real-life pediatric rehabilitation therapies. DESIGN Eleven participants (5 girls; 12.5±2.1y old) with neurological disorders and independent mobility wore accelerometers at wrists and ankles and a portable heart rate monitor during several of the following therapies: sports therapy, mobility-focused physiotherapy, medical training therapy, and robot-assisted gait training. Intensity of physical activity was quantified by activity counts (measured via accelerometers) and heart rate. RESULTS Therapy duration did not correlate with intensity. At the same time we found significant differences between intensities of different therapies. CONCLUSION Different therapies elicit different levels of intensity in children with neuromotor disorders. Heart rate and activity counts are suited to estimate the intensity of a therapy and provide complementary information. We recommend against using the duration of a therapy as a proxy for the dose to make statements about dose-response relationships

Analytical design of nonlinear optical loop mirrors for fiber-optic communication systems

International audienceWe propose an easy and efficient method for analytically designing nonlinear optical loop mirrors (NOLMs) for fiber-optic communication systems. This analytical design is based on a Taylor series expansion of the transfer function of the NOLM, from which highly stable dynamical regimes can be readily obtained for any desired pulse parameters. We present numerical simulations showing dramatically improved performances in a 160 Gb/s transmission system that incorporates the NOLMs designed analytically

Transmission performance of N X 160 Gbits(-1) densely dispersion-managed optical fibre systems

International audienceWe carefully analyse the feasibility of N x 160 Gbit s(-1) ultra- long haul transmissions in densely dispersion-managed ( DDM) fibre systems. By using a novel analytical approach, we design highly optimized configurations of DDM fibre systems. Transmission performances of the analytically designed DDM fibre systems are evaluated using numerical simulations. We show that single-channel transoceanic transmissions at 160 Gbit s(-1) may be achievable in DDM fibre systems, whereas multi-channel transmissions result in dramatically poor performances

Strength training versus robot-assisted gait training after incomplete spinal cord injury: a randomized pilot study in patients depending on walking assistance

BACKGROUND Task-specific locomotor training has been promoted to improve walking-related outcome after incomplete spinal cord injury (iSCI). However, there is also evidence that lower extremity strength training might lead to such improvements. The aim of this randomized cross-over pilot study was to compare changes in a broad spectrum of walking-related outcome measures and pain between robot-assisted gait training (RAGT) and strength training in patients with chronic iSCI, who depended on walking assistance. We hypothesized that task-specific locomotor training would result in better improvements compared to strength training. METHODS Nine participants with a chronic iSCI were randomized to group 1 or 2. Group 1 received 16 sessions of RAGT (45 min each) within 4 weeks followed by 16 sessions of strength training (45 min each) within 4 weeks. Group 2 received the same interventions in reversed order. Main outcome measures were the 10 m Walk Test (10MWT) at preferred and maximal speed. Furthermore, we assessed several measures such as walking speed under different conditions, balance, strength, and 2 questionnaires that evaluate risk of falling and pain. Data were collected at baseline, between interventions after 4 weeks, directly after the interventions and at follow-up 6 months after the interventions. Pain was assessed repeatedly throughout the study. RESULTS There were no significant differences in changes in scores between the 2 interventions, except for maximal walking speed (10MWT), which improved significantly more after strength training than after RAGT. Pain reduced after both interventions. CONCLUSION In patients with chronic iSCI dependent on walking assistance, RAGT was not more effective in improving walking-related outcome compared to lower extremity strength training. However, the low sample size limits generalizability and precision of data interpretation. TRIAL REGISTRATION This study was registered at Clinicaltrials.gov (NCT01087918)