67 research outputs found

    Enhancement in Electro-Optic Properties of Dynamic Scattering Systems through Addition of Dichroic Dyes

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    Electro-optic properties of dynamic scattering in homeotropically aligned pure and dichroic dye-doped nematic liquid crystal samples are examined. The optical properties of the two systems are quantified using transmission properties of scattered and unscattered as a function of amplitude and frequency of an applied voltage. Auto-correlation of the scattered signal at different applied voltages is used to compare the decay times in the two systems. Lastly, the histogram of the scattered signal reveals a wavevector dependent large light scattering event. The dye-doped system shows a significant enhancement of light blocking property in both normal and off-axis light propagation. The characteristics of the system are compared to other scattering technologies. The results suggest that dye-doped system can overcome shortcomings in scattering based devices used for near-eye applications

    Intermittent in-situ high-resolution X-ray microscopy of 400-nm porous glass under uniaxial compression: study of pore changes and crack formation

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    The properties of porous glasses and their field of application strongly depend on the characteristics of the void space. Understanding the relationship between their porous structure and failure behaviour can contribute to the development of porous glasses with long-term reliability optimized for specific applications. In the present work, we used X-ray computed tomography with nanometric resolution (nano-CT) to image a controlled pore glass (CPG) with 400 nm-sized pores whilst undergoing uniaxial compression in-situ to emulate a stress process. Our results show that in-situ nano-CT provides an ideal platform for identifying the mechanisms of damage within glass with pores of 400 nm, as it allowed the tracking of the pores and struts change of shape during compression until specimen failure. We have also applied computational tools to quantify the microstructural changes within the CPG sample by mapping the displacements and strain fields, and to numerically simulate the behaviour of the CPG using a Fast Fourier Transform/phase-field method. Both experimental and numerical data show local shear deformation, organized along bands, consistent with the appearance and propagation of +/- 45 degrees cracks.Comment: 14 pages, 6 figure

    Safety, Immunogenicity, and Protective Efficacy of Intradermal Immunization with Aseptic, Purified, Cryopreserved Plasmodium falciparum Sporozoites in Volunteers Under Chloroquine Prophylaxis

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    Immunization of volunteers under chloroquine prophylaxis by bites of *Plasmodium falciparum* sporozoite (PfSPZ)–infected mosquitoes induces > 90% protection against controlled human malaria infection (CHMI). We studied intradermal immunization with cryopreserved, infectious PfSPZ in volunteers taking chloroquine (PfSPZ chemoprophylaxis vaccine [CVac]). Vaccine groups 1 and 3 received 3x monthly immunizations with 7.5 x 10^4 PfSPZ. Control groups 2 and 4 received normal saline. Groups 1 and 2 underwent CHMI (#1) by mosquito bite 60 days after the third immunization. Groups 3 and 4 were boosted 168 days after the third immunization and underwent CHMI (#2) 137 days later. Vaccinees (11/20, 55%) and controls (6/10, 60%) had the same percentage of mild to moderate solicited adverse events. After CHMI #1, 8/10 vaccinees (group 1) and 5/5 controls (group 2) became parasitemic by microscopy; the two negatives were positive by quantitative real-time polymerase chain reaction (qPCR). After CHMI #2, all vaccinees in group 3 and controls in group 4 were parasitemic by qPCR. Vaccinees showed weak antibody and no detectable cellular immune responses. Intradermal immunization with up to 3 x 10^5 PfSPZ-CVac was safe, but induced only minimal immune responses and no sterile protection against Pf CHMI. INTRODUCTIO

    Enhancement in electro-optic properties of dynamic scattering systems through addition of dichroic dyes

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    Electro-optic properties of dynamic scattering in homeotropically aligned pure and dichroic dye doped nematic liquid crystal samples are examined. The optical properties of the two systems are quantified using transmission properties of scattered and unscattered as a function of amplitude and frequency of an applied voltage. Auto-correlation of the scattered signal at different applied voltages is used to compare the decay times in the two systems. Lastly, histogram of the scattered signal reveals a wavevector dependent large light scattering event. The dye doped system shows a significant enhancement of light blocking property in both normal and off-axis light propagation. The characteristics of the system are compared to other scattering technologies. The results suggest that dye doped system can overcome shortcomings in scattering based devices used for near eye applications

    ON THE SEPARABILITY BETWEEN SIGNAL AND NOISE IN SINGULAR SPECTRUM ANALYSIS

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    The optimal value of the window length in singular spectrum analysis (SSA) is considered with respect to the concept of separability between signal and noise component, from the theoretical and practical perspective. The theoretical results confirm that for a wide class of time series of length N, the suitable value of this parameter is median{1, …, N}. The results of both simulated and real data verify the effectiveness of the theoretical results. The theoretical results obtained here coincide with those obtained previously from the empirical point of view
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