12,805 research outputs found
Wavelength tunable 10-GHz 3-ps pulse source using a dispersion decreasing fiber-based nonlinear optical loop mirror
Full text linkWe experimentally demonstrate the use of a dispersion decreasing fiber (DDF)-based nonlinear optical loop mirror (NOLM) for the generation of wavelength tunable soliton-like pulses at a repetition rate of 10 GHz. We compress ~12 ps Gaussian pulses from an electro-absorption modulator (EAM) (followed by 125 m of DCF for preliminary linear dispersion compensation) into 3 ps pedestal-free pulses using both high-order soliton compression and nonlinear switching effects within an 8.5 km DDF-based loop mirror. The output pulses from the DDF-based NOLM show considerable pedestal reduction compared to those obtained by directly compressing the EAM seed pulses via a single passage through the DDF. Wavelength tuning of the compressed pulses over a ~15 nm bandwidth (from 1541 to 1556 nm) is demonstrated without a significant increase in pulse duration or degradation in pulse quality
All-optical TDM data demultiplexing at 80 Gbit/s with significant timing jitter tolerance using a fiber Bragg grating based rectangular pulse switching technology
No full textWe demonstrate the use of fiber Bragg grating based pulse-shaping technology to provide timing jitter tolerant data demultiplexing in an 80 Gb/s all-optical time division multiplexing (OTDM) system. Error-free demultiplexing operation is achieved with ~6 ps timing jitter tolerance using superstructured fiber Bragg grating based 1.7 ps soliton to 10 ps rectangular pulse conversion at the switching pulse input to a nonlinear optical loop mirror (NOLM) demultiplexer comprising highly nonlinear dispersion shifted fiber (HNLF). A 2-dB power-penalty improvement is obtained compared to demultiplexing without the pulse-shaping grating. <br/
Wavelength and duration tunable 10 GHz 1.3ps pulse source using dispersion decreasing fiber based distributed Raman amplification
Full text linkWe experimentally demonstrate a novel pulse compression scheme using dispersion decreasing fiber (DDF) based distributed Raman amplification. We adiabatically compress 10GHz, 13ps seed pulses generated using a commercially available electro-absorption modulator into high-quality 1.3ps pulses in a 20km DDF based, diode-pumped, Raman amplifier. The usual DDF adiabatic soliton compression process is assisted by the distributed Raman gain along the fiber and by control of the input pulse chirp. Both wavelength tunability of about 30 nm and pulse-duration tunability from 1 to 5 ps are also demonstrated
Player agency in interactive narrative: audience, actor & author
Full text linkThe question motivating this review paper is, how can
computer-based interactive narrative be used as a constructivist learn-
ing activity? The paper proposes that player agency can be used to
link interactive narrative to learner agency in constructivist theory,
and to classify approaches to interactive narrative. The traditional
question driving research in interactive narrative is, ‘how can an in-
teractive narrative deal with a high degree of player agency, while
maintaining a coherent and well-formed narrative?’ This question
derives from an Aristotelian approach to interactive narrative that,
as the question shows, is inherently antagonistic to player agency.
Within this approach, player agency must be restricted and manip-
ulated to maintain the narrative. Two alternative approaches based
on Brecht’s Epic Theatre and Boal’s Theatre of the Oppressed are
reviewed. If a Boalian approach to interactive narrative is taken the
conflict between narrative and player agency dissolves. The question
that emerges from this approach is quite different from the traditional
question above, and presents a more useful approach to applying in-
teractive narrative as a constructivist learning activity
Effects of electromyography biofeedback-assisted relaxation on pain in patients with advanced cancer in a palliative care unit.
No full textA conformal nano-adhesive via initiated chemical vapor deposition for microfluidic devices
No full textA novel high-strength nano-adhesive is demonstrated for fabricating nano-and microfluidic devices. While the traditional plasma sealing methods are specific for sealing glass to poly(dimethylsiloxane) (PDMS), the new method is compatible with a wide variety of polymeric and inorganic materials, including flexible substrates. Additionally, the traditional method requires that sealing occur within minutes after the plasma treatment. In contrast, the individual parts treated with the nano-adhesive could be aged for at least three months prior to joining with no measurable deterioration of post-cure adhesive strength. The nano-adhesive is comprised of a complementary pair of polymeric nanolayers. An epoxy-containing polymer, poly(glycidyl methacrylate) (PGMA) was grown via initiated chemical vapor deposition (iCVD) on the substrate containing the channels. A plasma polymerized polyallylamine (PAAm) layer was grown on the opposing flat surface. Both CVD monomers are commercially available. The PGMA nano-adhesive layer displayed conformal coverage over the channels and was firmly tethered to the substrate. Contacting the complementary PGMA and PAAm surfaces, followed by curing at 70 degrees C, resulted in nano-and micro-channel structures. The formation of the covalent tethers between the complementary surfaces produces no gaseous by-products which would need to outgas. The nano-adhesive layers did not flow significantly as a result of curing, allowing the cross-sectional profile of the channel to be maintained. This enabled fabrication of channels with widths as small as 200 nm. Seals able to withstand > 50 psia were fabricated employing many types of substrates, including silicon wafer, glass, quartz, PDMS, polystyrene petri dishes, poly(ethylene terephthalate) (PET), polycarbonate (PC), and poly(tetrafluoro ethylene) (PTFE).This research was supported by, or supported in part by, the US
Army through the Institute for Soldier Nanotechnologies, under
Contract DAAD-19-02-0002 with the US Army Research Office
Reciclagem de poliestireno expandido (EPS) para o uso na fabricação de perfilados de poliestireno (PS)
Full text linkDissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico, Programa de Pós-graduação em Ciência e Engenharia de Materiais, Florianópolis, 2009Mesmo presente em pequena percentagem de massa nos resíduos sólidos urbanos gerados, o poliestireno expandido (EPS) ocupa um grande espaço nos depósitos de lixo devido à sua baixa relação massa/volume, tornando necessária a busca de tecnologias para a viabilização econômica da sua cadeia de reciclagem. O EPS reciclado por processo de extrusão, quando ocorre então a sua degaseificação, poderia ser utilizado em muitas das aplicações do poliestireno (PS) cristal (ou de uso geral). Com a grande oferta de produtos eletro-eletrônicos, principalmente componentes de computadores, nas cooperativas e associações de catadores que recebem o material proveniente da coleta seletiva dos municípios da grande Florianópolis, neste trabalho estudou-se como uma alternativa para a reciclagem do EPS a produção de perfis de PS para aplicação na construção civil. Devido as propriedades mecânicas insatisfatórias do poliestireno para tal aplicação, blendas com PSAI e ABS foram obtidas. A incorporação de PSAI e ABS no PS (obtido a partir do EPS reciclado) incrementa a sua tenacidade, possibilitando a ampliação da gama de aplicações. Diversas composições da mistura PS/PSAI/ABS foram preparadas buscando-se a relação que apresente as melhores propriedades na fabricação de perfis de PS extrudados. Borracha termoplástica do tipo SBS foi utilizada como agente compatibilizante. Tais resultados permitem concluir que a reciclagem do EPS possibilita a fabricação de produtos com valor agregado diferenciado, viabilizando a sua cadeia de reciclagemDespite being present in small percentage of mass at the municipal solid waste generated, the expanded polystyrene (EPS) occupies a large space in landfills due to its low relation weight / volume, making necessary to search technologies for the economic feasibility of its chain recycling. The EPS recycled by extrusion process, when it occurs its degassing, could be used in many applications of general purpose polystyrene (GPPS). With the wide offer of electronic products waste, especially computer components, in cooperatives and associations of collectors that receive material from the waste collection in the municipalities of Florianopolis, in this work was studied, as an alternative for the EPS recycling, the production of profiles of PS for application in construction. Because of the lower mechanical properties of PS for this application, PS blends with HIPS and ABS were obtained. The blend of HIPS and ABS with the PS (obtained from recycled EPS) increases its toughness, allowing wider range of applications. Several compositions of the mixture PS / HIPS / ABS were prepared aiming for the relation which has the best mechanical properties in the manufacture of extruded profiles of PS. Thermoplastic rubber SBS type was used as compatibilizing agent. The results indicate that the recycling of EPS allows the manufacture of products with differentiated value-added, enabling its recycling chai
Elimination of the chirp of optical pulses through cascaded nonlinearities in periodically poled lithium niobate waveguides
No full textWe propose and demonstrate a novel method for the elimination of arbitrary frequency chirp from short optical pulses. The technique is based on the combination of two cascaded second-order nonlinearities in two individual periodically poled lithium niobate waveguides
Nuclear translocation and signalling of L1-CAM in human carcinoma cells requires ADAM10 and presenilin/gamma-secretase activity
No full textL1-CAM (L1 cell-adhesion molecule), or more simply L1, plays an important role in the progression of human carcinoma. Overexpression promotes tumour-cell invasion and motility, growth in nude mice and tumour metastasis. It is feasible that L1-dependent signalling contributes to these effects. However, little is known about its mechanism in tumour cells. We reported previously that L1 is cleaved by ADAM (a disintegrin and metalloprotease) and that the cytoplasmic part is essential for L1 function. Here we analysed more closely the role of proteolytic cleavage in L1-mediated nuclear signalling. Using OVMz carcinoma cells and L1-transfected cells as a model, we found that ADAM10-mediated cleavage of L1 proceeds in lipid raft and non-raft domains. The cleavage product, L1-32, is further processed by PS (presenilin)/gamma-secretase to release L1-ICD, an L1 intracellular domain of 28 kDa. Overexpression of dominantnegative PS1 or use of a specific gamma-secretase inhibitor leads to an accumulation of L1-32. Fluorescence and biochemical analysis revealed a nuclear localization for L1-ICD. Moreover, inhibition of ADAM10 and/or gamma-secretase blocks nuclear translocation of L1-ICD and L1-dependent gene regulation. Overexpression of recombinant L1-ICD mediates gene regulation in a similar manner to full-length L1. Our results establish for the first time that regulated proteolytic processing by ADAM10 and PS/gamma-secretase is essential for the nuclear signalling of L1 in human carcinoma cell lines. Key words: a disintegrin and metalloprotease 10 (ADAM10), L1 cell-adhesion molecule (L1-CAM), nuclear translocation, presenilin (PS)/gamma-secretase activity, raft, signalling
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