Laser emission from transversely pumped dye-doped free-standing polymer film

We present a compact solid-state laser based on leaky mode propagation from a dye-doped polymer free-standing film waveguide. The edge emitted spectrum clearly indicated the existence of periodic resonant modes. The reflections from the lateral faces of the free-standing film provided the optical feedback thus giving rise to a Fabry–Perot like optical cavity. This together with the guidance through the gain medium gave rise to intense narrow emission lines. For a pump energy of 1.82 mJ/pulse, an intense line with FWHM ∼0.4 nmwas observed at 576.5 nm.

Laser emission from transversely pumped dye-doped free-standing polymer film

We present a compact solid-state laser based on leaky mode propagation from a dye-doped polymer free-standing film waveguide. The edge emitted spectrum clearly indicated the existence of periodic resonant modes. The reflections from the lateral faces of the free-standing film provided the optical feedback thus giving rise to a Fabry–Perot like optical cavity. This together with the guidance through the gain medium gave rise to intense narrow emission lines. For a pump energy of 1.82 mJ/pulse, an intense line with FWHM ∼0.4 nmwas observed at 576.5 nm.

Loss characterization in rhodamine 6G doped polymer film waveguide by side illumination fluorescence

We report the position dependent tuning of fluorescence emission from rhodamine 6G doped polymethylmethacrylate film waveguide using a side illumination technique. The transmitted fluorescence as a function of the distance from the point of illumination is measured by translating the waveguide horizontally across a monochromatic light source. This technique has been utilized to characterize the optical loss in dye doped waveguides. We observe that the optical loss coefficients for shorter and longer distances of propagation through the dye doped waveguide are different. At longer distance of propagation a decrease in optical loss coefficient is observed

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process. The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser emitting at 532 nm and a CCD-spectrograph in the 400–3800 cm−1 range. The variation of the Raman intensity with the length of the optical fibre is studied. Investigations are carried out on the variation of FWHM of the Raman peak at 2957 cm−1 with the length of the optical fibre and pump power. The differential scattering cross section and gain coefficient of the Raman peak at 2957 cm−1 in PMMA are calculated in relation to that of toluene.

Raman spectra of polymethyl methacrylate optical fibres excited by a 532 nm diode pumped solid state laser

Polymethyl methacrylate (PMMA) optical fibres are fabricated by a preform drawing process. The Raman spectra of PMMA fibres are recorded using a diode pumped solid state laser emitting at 532 nm and a CCD-spectrograph in the 400–3800 cm−1 range. The variation of the Raman intensity with the length of the optical fibre is studied. Investigations are carried out on the variation of FWHM of the Raman peak at 2957 cm−1 with the length of the optical fibre and pump power. The differential scattering cross section and gain coefficient of the Raman peak at 2957 cm−1 in PMMA are calculated in relation to that of toluene

Fabrication And Parametric Measurements Of N2 Laser Pumped Dye Laser And Its Application To Energy Transfer Studies In Mixed Dyes

Eventhough a large number of schemes have been proposed and develoned for N9 laser ouined dye lasers the relatively low efficiency compelled the scientists to device new methods to improve the system efficiencs. Energy transfer mechanism has been shown to he a convenien tool for the enhancement of efficiency of dye lasers. Th p resent work covers a detailed study of the performance characteristics of a N2 laser pumped dye laser in the con— ventional mode and also, when pumped by the energy transfer mechanism. For .th.e present investigations a dye laser pumped by a'N2 laser (A4200 kw peak power) was fabricated. The grating at grazing incidence was used as the beam expanding device; A t its best performance the system was giving an output peak power of l5 kW for a 5 X lC"3H/l Rh—€ solution in methanol. T he conversion efficiency was 7.5; The output beam was having 3 divergence of 2 mrad and bandwidth o.9 A. Suitable modifications were suggested for obtaining better conversion efficiency and bandwidth.

IRP Poster - Side-effects in Software Transactional Memory

Poster for IRP project 'Side-effects in Software Transactional Memory: Extending Deuce with TwilightSTM'

WAIS Seminar:Evaluating the Cognitive Side of Information Interaction

Abstract In this talk, I'll focus on the work we've been doing on evaluating the cognitive side of dealing with information resources and increasingly complex user interfaces. While we can build increasingly powerful user interfaces, they often come at the cost of simple design and ease of use. I'll describe two specific studies: 1) work on the ORCHID project focused on measuring mental workload during tasks using fNIRS (a blood-oxygen-based brain scanner), and 2) a evaluation metric for measuring how much people learn during tasks. Together these provide advances towards understanding the cognitive side of information interaction, in working towards building better tools for users.

Empregabilidade e side-bets: uma realidade dos estudantes universitários do mestrado

O conceito de empregabilidade tem sido crucial nos dias de hoje devido às mudanças que têm ocorrido na sociedade em geral. É imprescindível conhecer o este conceito bem como as transformações que têm ocorrido à volta dele e principalmente quais os seus antecedentes. Partindo da ideia que existe um investimento na procura de emprego, os side-bets foram considerados antecedentes da empregabilidade. O presente estudo teve como objectivo estudar a relação de antecedência dos side-bets com a percepção da empregabilidade, num contexto universitário, nomeadamente dos estudantes do mestrado. Os resultados permitiram concluir que os side-bets são antecedentes da empregabilidade. Contudo foram identificadas várias limitações que permitem encontrar estudos futuros bastante interessantes. Foram discutidas as implicações do presente estudo

The dark side of the Mediterranean : expression of fear from the inquisition to the present

Inside the stones of its most famous buildings, Évora keeps mysteries and secrets which constitute the most hidden side of its cultural identity. A World Heritage site, this town seems to preserve, in its medieval walls, a precious knowledge of the most universal and ancient human emotion: fear. Trying to transcend many of its past and future fears, some of its historical monuments in Gothic style were erected against the fear of death, the most terrible of all fears, which the famous inscription, in the Bones Chapel of the Church of São Francisco, insistently reminds us, through the most disturbing words: “Nós ossos que aqui estamos pelos vossos esperamos”. If the first inquisitors worked in central Europe (Germany, northern Italy, eastern France), later the centres of the Inquisition were established in the Mediterranean regions, especially southern France, Italy, Portugal, and Spain. Consequently, the roots of fear in Évora are common to other towns, where the Inquisition developed a culture of fear, through which we can penetrate into the dark side of the Mediterranean, where people were subjected to the same terrifying methods of persecution and torture. This common geographical and historical context was not ignored by one of the most famous masters of American gothic fiction, Edgar Allan Poe. Through the pages of The Pit and the Pendulum, readers get precise images of the fearful instruments of terror that were able to produce the legend that has made the first grand inquisitor, Tomas de Torquemada, a symbol of ultimate cruelty, bigotry, intolerance, and religious fanaticism, which unfortunately are still the source of our present fears in a time when religious beliefs can be used again as a motif of war and destruction. As Krishnamurti once suggested, only a fundamental realization of the root of all fear can free our minds.

Synthesis and characterization of thermally stable second-order nonlinear optical side-chain polyimides containing thiazole and benzothiazole push-pull chromophores

Push-pull nonlinear optical (NLO) chromophores containing thiazole and benzothiazole acceptors were synthesized and characterized. Using these chromophores a series of second-order NLO polyimides were Successfully prepared from 4,4'-(hexafluoroisopropylidene) diphthalic anhydride (6FDA), pyromellitic dianhydride (PMDA) and 3,3'4,4'-benzophenone tetracarboxylic dianhydride (BTDA) by a standard condensation polymerization technique. These polyimides exhibit high glass transition temperatures ranging from 160 to 188 degrees C. UV-vis spectrum of polyimide exhibited a slight blue shift and decreases in absorption due to birefringence. From the order parameters, it was found that chromophores were aligned effectively. Using in situ poling and temperature ramping technique, the optical temperatures for corona poling were obtained. It was found that the optimal temperatures of polyimides approach their glass transition temperatures. These polyimides demonstrate relatively large d(33) values range between 35.15 and 45.20 pm/V at 532 nm. (C) 2008 Elsevier B.V. All rights reserved.

Provision of information about drug side-effects to patients

To make informed decisions about taking medicinal drugs, people need accurate information about side-effects. A European Union guideline now recommends use of qualitative descriptions for five bands of risk, ranging from very rare (affecting < 0·01% of the population), to very common (>10%). We did four studies of more than 750 people, whom we asked to estimate the probability of having a side-effect on the basis of qualitative and quantitative descriptions. Our results showed that qualitative descriptions led to gross overestimation of risk. Until further work is done on how patients taking the drugs interpret these terms, the terms should not be used in drug information leaflets.

Communicating information about medication side effects: effects on satisfaction, perceived risk to health, and intention to comply

Previous research has shown that people's evaluations of explanations about medication and their intention to comply with the prescription are detrimentally affected by the inclusion of information about adverse side effects of the medication. The present study (Experiment 1) examined which particular aspects of information about side effects (their number, likelihood of occurrence, or severity) are likely to have the greatest effect on people's satisfaction, perception of risk, and intention to comply, as well as how the information about side effects interacts with information about the severity of the illness for which the medication was prescribed. Across all measures, it was found that manipulations of side effect severity had the greatest impact on people's judgements, followed by manipulations of side effect likelihood and then number. Experiments 2 and 3 examined how the severity of the diagnosed illness and information about negative side effects interact with two other factors suggested by Social Cognition models of health behaviour to affect people's intention to comply: namely, perceived benefit of taking the prescribed drug, and the perceived level of control over preventing or alleviating the side effects. It was found that providing people with a statement about the positive benefit of taking the medication had relatively little effect on judgements, whereas informing them about how to reduce the chances of experiencing the side effects had an overall beneficial effect on ratings.

Is 15 per cent very common? Informing people about the risks of medication side effects

Objectives - To assess the general public's interpretation of the verbal descriptors for side effect frequency recommended for use in medicine information leaflets by a European Union (EU) guideline, and to examine the extent to which differences in interpretation affect people's perception of risk and their judgments of intention to comply with the prescribed treatment. Method - Two studies used a controlled empirical methodology in which people were presented with a hypothetical, but realistic, scenario about visiting their general practitioner and being prescribed medication. They were given an explanation that focused on the side effects of the medicine, together with information about the probability of occurrence using either numerical percentages or the corresponding EU verbal descriptors. Interpretation of the descriptors was assessed. In study 2, participants were also required to make various judgments, including risk to health and intention to comply. Key findings - In both studies, use of the EU recommended descriptors led to significant overestimations of the likelihood of particular side effects occurring. Study 2 further showed that the "overestimation" resulted in significantly increased ratings of perceived severity of side effects and risk to health, as well as significantly reduced ratings of intention to comply, compared with those for people who received the probability information in numerical form. Conclusion - While it is recognised that the current findings require replication in a clinical setting, the European and national authorities should suspend the use of the EU recommended terms until further research is available to allow the use of an evidence-based approach.