All-optical silicon simplified passive modulation

In this paper we present an all-optical silicon based modulator suggested also for high power operation and for pulse picker application being used as part of fiber lasers system. The paper theoretically and experimentally investigates several new and important insights involving the dependence of the relative transmission on the pump pulse energy for different finesse values of the constructed cavity as well as the dependence of the response rate of the device to the pump wavelength due to coexistence of two physical recombination processes: fast surface effect and slow bulk recombination. To adapt the constructed silicon based cavity to be used in lasers applications, we aligned the pump and the signal beams to co-propagate through the device while the usage of a cavity allowed a low power pump to yield a significant extinction ratio at the output of the device

Veterinary students' usage and perception of video teaching resources

<p>Abstract</p> <p>Background</p> <p>The purpose of our study was to use a student-centred approach to develop an online video learning resource (called 'Moo Tube') at the School of Veterinary Medicine and Science, University of Nottingham, UK and also to provide guidance for other academics in the School wishing to develop a similar resource in the future.</p> <p>Methods</p> <p>A focus group in the format of the nominal group technique was used to garner the opinions of 12 undergraduate students (3 from year-1, 4 from year-2 and 5 from year-3). Students generated lists of items in response to key questions, these responses were thematically analysed to generate key themes which were compared between the different year groups. The number of visits to 'Moo Tube' before and after an objective structured practical examination (OSPE) was also analysed to provide data on video usage.</p> <p>Results</p> <p>Students highlighted a number of strengths of video resources which can be grouped into four overarching themes: (1) teaching enhancement, (2) accessibility, (3) technical quality and (4) video content. Of these themes, students rated teaching enhancement and accessibility most highly. Video usage was seen to significantly increase (P < 0.05) prior to an examination and significantly decrease (P < 0.05) following the examination.</p> <p>Conclusions</p> <p>The students had a positive perception of video usage in higher education. Video usage increases prior to practical examinations. Image quality was a greater concern with year-3 students than with either year-1 or 2 students but all groups highlighted the following as important issues: i) good sound quality, ii) accessibility, including location of videos within electronic libraries, and iii) video content. Based on the findings from this study, guidelines are suggested for those developing undergraduate veterinary videos. We believe that many aspects of our list will have resonance in other areas of medicine education and higher education.</p

Melanoma-associated hypopigmentation: Where are the antibodies?

Antibodies to the B16 melanoma cell line and to tyrosinase have been recently defined in our laboratory in sera of patients with vitiligo, melanoma, melanoma-associated hypopigmentation (MAH), and in healthy subjects. The antibody titers in each subject were measured by enzyme-linked immunosorbent assay, were compared with the mean optical density (OD) of the control group, and were expressed as relative OD. The titers of anti-B16 antibodies (relative OD � standard error) were 1.000 (0.058) in the controls, 1.025 (0.077) in patients with metastatic melanoma, 0.5862 (0.15) in MAH, 1.377 in surgery-induced MAH, 1.087 in vaccination with anti-idiotypic antibodies, and 2.098 (0.15) in autoimmune vitiligo. The titers in vitiligo were significantly higher (p < 0.0001) than in MAH or in healthy controls. Antityrosinase antibodies were found in titers of 1.000 (0.1024) in the controls, 1.516 (0.225) in metastatic melanoma, 1.027 (0.180) in MAH, 1.075 in surgery-induced MAH, 2.308 in vaccination-induced MAH, and 4.536 in vitiligo. Differences were found between vitiligo and MAH (p = 0.008), surgery-induced MAH (p = 0.009), vaccination-induced MAH (p = 0.059), and healthy subjects (p < 0.0001). The results of this study point to the cross-antigenicity between melanocytes and melanoma cells, and to participation of antibodies against melanoma-associated membrane antigens in the mechanism leading to the development of MAH in patients with melanoma

Anti-Tyrosinase Antibodies participate in the immune-response to vaccination with antiidiotypic antibodies mimicking the the High-Molecular-Weight-Melanoma-Associated-Antigen

Seven patients with metastatic melanoma were vaccinated with anti-idiotypic monoclonal antibody (mAb) MK2-23 which mimics the high-molecular-weight melanoma-associated antigen (HMW MAA), Sera samples were assayed for anti-anti-idiotypic antibodies, by Ab1-Ab2 complex inhibition test, for anti-Bls epitope antibodies, which are a heterogeneous group against various antigens presented on B16 melanoma cells and for anti-tyrosinase antibodies, which are specific against tyrosinase. Our results pointed to the participation of anti-tyrosinase antibodies in the immune response to vaccination by antiidiotypic antibodies mimicking the HMW MAA. The antityrosinase antibody kinetic curves presented an initial increase in titres in five cases followed by decreasing titres; in two cases a constant decrease was noted. The inhibition assay demonstrated an increasing percentage of inhibition (range 17-100%) within 100-400 days of treatment, The titre of the anti-tyrosinase antibodies increased following the vaccination, then decreased - probably due to absorption of the antibodies to melanoma cells and normal melanocytes. A positive slope in the percentage of inhibition was roughly associated with a negative slope of anti-tyrosinase antibodies. In one case, a long-standing complete clinical response was accompanied by development of melanoma-associated hypopigmentation. Anti-ale epitope antibodies had no role in the response to vaccination, The development of anti-tyrosinase antibodies in response to vaccination by anti-idiotypic antibodies mimicking another antigen may be explained by induction of non-specific polyclonal B lymphocytes activation, a well-recognized phenomenon in autoimmune disorders, While in autoimmune diseases the production of a second autoantibody may aggravate the course, in melanoma it may contribute to the regression of the disease in some patients

Tyrosinase as an autoantigen in patients with vitiligo

Vitiligo is considered an autoimmune disorder due to the generation and presence of autoantibodies directed against melanocyte antigens in the patients' sera. In the present study we point towards a newly defined autoantigen in vitiligo, the enzyme tyrosinase, which participates in the process of melanogenesis. Anti-tyrosinase antibodies were detected in the sera of seven patients with diffuse and 11 patients with localized vitiligo. Employing solid-phase ELISA to mushroom tyrosinase, we found that patients with diffuse vitiligo had significantly higher titres of IgG anti-tyrosinase autoantibodies than patients with localized disease or healthy subjects. These anti-tyrosinase autoantibodies have relatively high functional affinity to tyrosinase and can be recovered from vitiligo patients’ sera by affinity purification. The anti-tyrosinase antibodies do not cross-react with other enzymes recognized as autoantigens in different autoimmune disorders and the autoantibodies do not block the enzymatic activity of tyrosinase, indicating that they are not reacting with the catalytic site of the enzyme. These data point to tyrosinase as an autoantigen in vitiligo and suggest that anti-tyrosinase titres can serve as a marker for disease activity