Impact of Laser Guide Star Fratricide on TMT MCAO System

Laser beams projected from the ground to form laser guide stars (LGS) experience scattering and absorption that reduce their intensity as they propagate through the atmosphere. Some fraction of the scattered light will be collected by the other LGS wavefront sensors and causes additional background in parts of the pupil. This cross-talk is referred to as the fratricide effect. In this paper we quantify the magnitude of four different sources of scattering/absorption and back scattering, and evaluate their impact on performance with various zenith angles and turbulence profiles for the Thirty Meter Telescope (TMT) MCAO system, NFIRAOS. The resulting wavefront error is on the order of 5 to 20 nm RMS, provided that the mean background from the fratricide can be calibrated and subtracted with an accuracy of 80%. We have also found that the impact of fratricide is a weak function of LGS asterism radius

Impact of sodium laser guide star fratricide on multi-conjugate adaptive optics systems

Laser beams projected from the ground to form sodium layer laser guide stars (LGSs) for adaptive optics (AO) systems experience scattering and absorption that reduce their intensity as they propagate upward through the atmosphere. Some fraction of the scattered light will be collected by the other wavefront sensors and causes additional background in parts of the pupil. This cross-talk between different LGS wavefront sensors is referred to as the fratricide effect. In this paper we quantify the magnitude of four different sources of scattering/absorption and backscattering, and we evaluate their impact on performance with various zenith angles and turbulence profiles for one particular AO system. The resulting wavefront error for the Thirty Meter Telescope (TMT) multi-conjugate AO (MCAO) system, NFIRAOS, is on the order of 5 to 20 nm RMS, provided that the mean background from the fratricide effect can be calibrated and subtracted with an accuracy of 80%. We also present the impact on system performance of momentary variations in LGS signal levels due to variations in cirrus absorption or laser power, and we show that this affects the performance more than does an equal variation in the level of the fratricide

"I Took the Photograph Just to Show You a Little Bit of Perspective": Photo-Elicitation Interviewing With Family Caregivers in the Dementia Context

Photo-Elicitation-Interviews (PEI) sind ein bekannter Ansatz in der qualitativen Forschung. In der vorhandenen Literatur fehlt es jedoch an ausreichenden Informationen über die Perspektiven der Teilnehmer*innen, die Fotos verwenden, um ihre Erfahrungen zu erläutern, und darüber, wie die von ihnen aufgenommenen Fotos das Verständnis des untersuchten Phänomens verbessern können, dies insbesondere im Kontext von Demenzerkrankungen. In diesem Artikel berichte ich über die Erfahrungen von Teilnehmer*innen, die in einer qualitativen Studie über die familiären Pflegeerfahrungen mit einem an Demenz erkrankten Angehörigen teilgenommen haben. Insgesamt handelte es sich um fünf pflegende Angehörige, die an dem PEI-Prozess teilnahmen und 28 Fotos zur Verfügung stellten, um ihre Erfahrungen präsentieren. Mittels thematischer Analyse wurde ein übergreifendes Thema, Erleichterung eines tieferen gemeinsamen Verständnisses, identifiziert, das drei Hauptthemen über die Erfahrungen der Teilnehmer*innen unterlag: PEI förderten 1. eine eingehendere Reflexion und neue Perspektiven, 2. ermöglichten sie einen reichhaltigeren Dialog und 3. konnten durch sie komplexe und ansonsten verborgene Erfahrungen aufgedeckt werden. Die Ergebnisse zeigen, dass PEI eine wirksame Methode sind, um die komplexen und vielschichtigen Erfahrungen bei der Pflege von demenzkranken Angehörigen besser zu verstehen. Die durchdachte Verwendung von Fotografien der Teilnehmer*innen in Interviews kann zu einem umfassenderen Verständnis führen und den pflegenden Angehörigen die Möglichkeit geben, zur Bedeutungsgebung beizutragen, die für die relationalen Aspekte der Pflege im Demenzkontext relevant ist.Photo-elicitation interviewing (PEI) is a well-known approach in qualitative inquiry. Yet existing literature lacks sufficient information on participants' perspectives on using photographs to explicate their experiences and ways in which their captured photographs can enhance understanding of the phenomenon under study, especially in the dementia context. In this article, I report on participants' experiences of partaking in the auto-driven approach of PEI in a qualitative descriptive study on family caregiving experiences to a relative living with dementia. Five family caregivers participated in the PEI process and provided 28 photographs that represented their experiences. Using thematic analysis, an overarching theme, facilitated deeper shared understandings was identified, underpinning three main themes about the participants' experiences of PEI, i.e., it 1. promoted more in-depth reflection and new perspectives; 2. enabled richer dialogue; and 3. revealed complex and otherwise hidden experiences. Findings show that PEI is an effective method for researchers to further understand the complex and multifaceted experiences involved in caring for a relative, living with dementia. Thoughtful implementation of using participant-taken photographs in interviews can provide a richer level of understanding and the means through which family caregivers can contribute to meaning-making relevant to the relational aspects of caregiving in the dementia context

Soft Lithographic Fabrication of Micro Optic and Guided Wave Devices

The design and development of guided wave devices based on soft lithographic fabrication techniques was examined. Notably, a novel vacuum assisted microfluidic technique for fabrication of guided wave and integrated optical devices was described. Importantly, the technique eliminates the polymer background residue inherent to traditional soft molding fabrication techniques. In addition, UV curable resins with tunable index control specifically tailored for soft lithography were developed. Comparisons to conventional soft lithography demonstrate that the VAM approach results in lower propagation losses, lower crosstalk, and improved waveguide structures. More importantly, microscope analysis portrays improved device formation, sidewall edges and the elimination of the polymer background residue intrinsic to conventional soft lithography. As a low-cost rapid prototyping technique the VAM soft lithographic method allows guided wave devices to be implemented rapidly and inexpensively. Moreover, through adoption of our VAM technique we were able to successfully fabricate several integrated optic and guided wave devices. The VAM technique is used to develop single and multi-mode channel waveguides, and array waveguide evanescent coupler (AWEC) ribbons for high-speed optical interconnection. Notably, through a soft lithographic approach the overall fabrication costs were reduced (without sacrificing ribbon quality and performance) and data rates of up to 10 Gbps per channel were demonstrated. We expect that the AWEC scheme will be significant for high-speed optical interconnects in advanced computing and backplane systems. Overall, we believe that the novel VAM technique can yield lower production costs and manufacturing complexity for polymer based photonic integrated circuits

Intrahost Selection Pressures Drive Rapid Dengue Virus Microevolution in Acute Human Infections.

Dengue, caused by four dengue virus serotypes (DENV-1 to DENV-4), is a highly prevalent mosquito-borne viral disease in humans. Yet, selection pressures driving DENV microevolution within human hosts (intrahost) remain unknown. We employed a whole-genome segmented amplification approach coupled with deep sequencing to profile DENV-3 intrahost diversity in peripheral blood mononuclear cell (PBMC) and plasma samples from 77 dengue patients. DENV-3 intrahost diversity appears to be driven by immune pressures as well as replicative success in PBMCs and potentially other replication sites. Hotspots for intrahost variation were detected in 59%-78% of patients in the viral Envelope and pre-Membrane/Membrane proteins, which together form the virion surface. Dominant variants at the hotspots arose via convergent microevolution, appear to be immune-escape variants, and were evolutionarily constrained at the macro level due to viral replication defects. Dengue is thus an example of an acute infection in which selection pressures within infected individuals drive rapid intrahost virus microevolution

ARGONAUTE PIWI domain and microRNA duplex structure regulate small RNA sorting in Arabidopsis.

Small RNAs (sRNAs) are loaded into ARGONAUTE (AGO) proteins to induce gene silencing. In plants, the 5'-terminal nucleotide is important for sRNA sorting into different AGOs. Here we show that microRNA (miRNA) duplex structure also contributes to miRNA sorting. Base pairing at the 15th nucleotide of a miRNA duplex is important for miRNA sorting in both Arabidopsis AGO1 and AGO2. AGO2 favours miRNA duplexes with no middle mismatches, whereas AGO1 tolerates, or prefers, duplexes with central mismatches. AGO structure modelling and mutational analyses reveal that the QF-V motif within the conserved PIWI domain contributes to recognition of base pairing at the 15th nucleotide of a duplex, while the DDDE catalytic core of AtAGO2 is important for recognition of the central nucleotides. Finally, we rescued the adaxialized phenotype of ago1-12, which is largely due to miR165 loss-of-function, by changing miR165 duplex structure which we predict redirects it to AGO2

Microstructure and texture analysis of δ-hydride precipitation in Zircaloy-4 materials by electron microscopy and neutron diffraction

This work presents a detailed microstructure and texture study of various hydrided Zircaloy-4 materials by neutron diffraction and microscopy. The results show that the precipitated δ-ZrH1.66 generally follows the δ (111) //α (0001) and δ[]//α[] orientation relationship with the α-Zr matrix. The δ-hydride displays a weak texture that is determined by the texture of the α-Zr matrix, and this dependence essentially originates from the observed orientation correlation between α-Zr and δ-hydride. Neutron diffraction line profile analysis and high-resolution transmission electron microscopy observations reveal a significant number of dislocations present in the δ-hydride, with an estimated average density one order of magnitude higher than that in the α-Zr matrix, which contributes to the accommodation of the substantial misfit strains associated with hydride precipitation in the α-Zr matrix. The present observations provide an insight into the behaviour of δ-hydride precipitation in zirconium alloys and may help with understanding the induced embrittling effect of hydrides.Fil: Wang, Zhiyang. University of Wollongong; Australia. Australian Nuclear Science and Technology Organisation; AustraliaFil: Garbe, Ulf. Australian Nuclear Science and Technology Organisation; AustraliaFil: Li, Huijun. University of Wollongong; AustraliaFil: Wang, Yanbo. University of Sydney; AustraliaFil: Studer, Andrew J.. Australian Nuclear Science and Technology Organisation; AustraliaFil: Sun, Guangai. Institute of Nuclear Physics and Chemistry, CAEP; ChinaFil: Harrison, Robert P.. Australian Nuclear Science and Technology Organisation, Institute of Materials Engineering; AustraliaFil: Liao, Xiaozhou. University of Sydney; AustraliaFil: Vicente Alvarez, Miguel Angel. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Santisteban, Javier Roberto. Comisión Nacional de Energía Atómica. Gerencia del Área de Energía Nuclear. Instituto Balseiro; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Kong, Charlie. University of New South Wales; Australi

Mechanical Turk-based Experiment vs Laboratory-based Experiment: A Case Study on the Comparison of Semantic Transparency Rating Data

In this paper, we conducted semantic trans-parency rating experiments using both the traditional laboratory-based method and the crowdsourcing-based method. Then we com-pared the rating data obtained from these two experiments. We observed very strong cor-relation coefficients for both overall seman-tic transparency rating data and constituent se-mantic transparency data (rho> 0:9) which means the two experiments may yield com-parable data and crowdsourcing-based experi-ment is a feasible alternative to the laboratory-based experiment in linguistic studies. We also observed a scale shrinkage phenomenon in both experiments: the actual scale of the rat-ing results cannot cover the ideal scale [0; 1], both ends of the actual scale shrink towards the center. However, the scale shrinkage of the crowdsourcing-based experiment is stronger than that of the laboratory-based experiment, this makes the rating results obtained in these two experiments not directly comparable. In order to make the results directly compara-ble, we explored two data transformation al-gorithms, z-score transformation and adjusted normalization to unify the scales. We also in-vestigated the uncertainty of semantic trans-parency judgment among raters, we found that it had a regular relation with semantic trans-parency magnitude and this may further reveal a general cognitivemechanism of human judg-ment.