206 research outputs found
An investigation of the Eigenvalue Calibration Method (ECM) using GASP for non-imaging and imaging detectors
Polarised light from astronomical targets can yield a wealth of information
about their source radiation mechanisms, and about the geometry of the
scattered light regions. Optical observations, of both the linear and circular
polarisation components, have been impeded due to non-optimised
instrumentation. The need for suitable observing conditions and the
availability of luminous targets are also limiting factors. GASP uses division
of amplitude polarimeter (DOAP) (Compain and Drevillon) to measure the four
components of the Stokes vector simultaneously, which eliminates the
constraints placed upon the need for moving parts during observation, and
offers a real-time complete measurement of polarisation. Results from the GASP
calibration are presented in this work for both a 1D detector system, and a
pixel-by-pixel analysis on a 2D detector system. Following Compain et al. we
use the Eigenvalue Calibration Method (ECM) to measure the polarimetric
limitations of the instrument for each of the two systems. Consequently, the
ECM is able to compensate for systematic errors introduced by the calibration
optics, and it also accounts for all optical elements of the polarimeter in the
output. Initial laboratory results of the ECM are presented, using APD
detectors, where errors of 0.2% and 0.1{\deg} were measured for the degree of
linear polarisation and polarisation angle respectively. Channel-to-channel
image registration is an important aspect of 2-D polarimetry. We present our
calibration results of the measured Mueller matrix of each sample, used by the
ECM. A set of Zenith flat-field images were recorded during an observing
campaign at the Palomar 200 inch telescope in November 2012. From these we show
the polarimetric errors from the spatial polarimetry indicating both the
stability and absolute accuracy of GASP.Comment: Accepted for publication in Experimental Astronom
Phase Transitions in Zeolitic Imidazolate Framework 7: The Importance of Framework Flexibility and Guest-Induced Instability
A study of the phase transitions in ZIF-7 (zeolitic imidazolate frameworks- (Zn(PhIm)2, PhIm = benzimidazolate)) as a function of guest occupancy and temperature was reported. Raman spectra of an as-synthesized sample were collected in air between 297 and 421 K. The major contributions of the spectra come from the vibrational modes of the benzimidazolate ligand. Upon heating, most of the Raman bands remain similar and keep the same frequencies until 357 K, indicating that the structure of ZIF-7 seems to be stable in this temperature range. Above 357 K, strong modifications are observed in the regions corresponding to the lattice modes. The formation of ZIF-7-II is attributed to the loss of dimethylformamide (DMF) solvent molecules from the ZIF-7-I framework. This can be confirmed by the differential scanning calorimetry and thermogravimetric analysis traces of ZIF-7-I. The highly-distorted and locally-strained nature of ZIF-7-II leads to its poor crystallinity, reflected by X-ray powder diffraction and scanning electron microscope
Embedding Changemaker Skills and Social Innovation into Design Student Learning
Building on entrepreneurship education and the United Kingdom (UK) government review on creativity in business, this paper discusses a case study of a funded project to develop design students' future skills by collaborating on transitioning student projects into start-up venture and commercialisation for the common good. Undergraduate students are shown to gain insights from different faculties and each other’s subject expertise using a variety of set activities throughout the academic year to challenge and support them. The learning for students included scheduled workshops with the possibility of new venture creation based on the new product development (NPD) methodology, student networking and applying their soft skills in a new context. Four workshop tasks (Enterprise, innovation and you, enterprise development, prototyping and venture articulation) were developed for this project and visualised in a route map. The collaboration of product design students with entrepreneurship students has been observed at the commencement stage, during and after the experience to understand their personal development and identify key learnings captured through opinion polls, focus groups and observation. Triangulation resulted through focus group and feedback from wider project team and academics reflecting on learning models in design/engineering versus entrepreneurship/business. This project is timely due to its year-long inter-faculty student experience during a pandemic using and developing ‘changemaker’ competencies and social innovation
Optical phonons, OH vibrations, and structural modifications of phlogopite at high temperatures: An in-situ infrared spectroscopic study
The thermal behavior of optical phonons and OH vibrations of phlogopite (a trioctahedral mica) was examined at temperatures up to 1000 K using in situ infrared spectroscopy. The results showed that with increasing temperature, O–K bands in phlogopite exhibited a relatively strong variation in frequency in a manner similar to those in muscovite. The work revealed that different types of OH bands (fundamentals and combinations) have very different thermal behavior or temperature dependence, and their absorption coefficients are commonly not constant on heating. OH combination bands that are associated with summation processes of multi-phonon interactions commonly show a decrease in their intensities on heating, but in contrast combination bands due to difference processes generally exhibit an increase. This means that temperature dependencies of their absorption coefficients need to be considered when using the Beer-Lambert law to determine or estimate OH contents or hydrogen concentrations at high temperatures. The results showed a structural anomaly associated with a discontinuity in the temperature derivative of the wavenumber of Al–O and Si–O vibrations and O–H stretching near 600 K. However, framework-related phonon modes in the FIR and MIR regions do not suggest a break of the original monoclinic structural symmetry in the investigated temperature region. The complex changes are attributed to temperature-induced alteration of local configuration involving TO4 tetrahedra and a possible change of the orientation of OH dipoles, in addition to a previously reported distortion of MO6 octahedra. Increasing temperature to 1000 K also causes partial dehydroxylation, as evidenced by the disappearance of the OH band near 3623 cm−1 and the decrease in OH band height and area of other OH bands. The study did not record the formation of H2O inside phlogopite as a result of partial dehydroxylation. The work offers new data and findings that have important implications in understanding the complex structural modifications and the behavior of phonon modes and the thermal stability of hydroxyls on approaching the dehydroxylation, as well as the way hydrogen is released from micas at high temperatures. Our data also show that phologpite becomes less transparent with increasing temperature suggesting a change of radiative properties and ability to transmit heat, which could be of interest for modeling thermal-transmission in crustal rocks
The CATH Domain Structure Database and related resources Gene3D and DHS provide comprehensive domain family information for genome analysis
The CATH database of protein domain structures (http://www.biochem.ucl.ac.uk/bsm/cath/) currently contains 43 229 domains classified into 1467 superfamilies and 5107 sequence families. Each structural family is expanded with sequence relatives from GenBank and completed genomes, using a variety of efficient sequence search protocols and reliable thresholds. This extended CATH protein family database contains 616 470 domain sequences classified into 23 876 sequence families. This results in the significant expansion of the CATHHMMmodel library to include models built from the CATH sequence relatives, giving a10%increase in coveragefor detecting remote homologues. An improved Dictionary of Homologous superfamilies (DHS) (http://www.biochem.ucl.ac.uk/bsm/dhs/) containing specific sequence, structural and functional information for each superfamily in CATH considerably assists manual validation of homologues. Information on sequence relatives in CATH superfamilies, GenBank and completed genomes is presented in the CATH associated DHS and Gene3D resources. Domain partnership information can be obtained from Gene3D (http://www.biochem.ucl.ac.uk/bsm/cath/Gene3D/). A new CATH server has been implemented (http://www.biochem.ucl.ac.uk/cgi-bin/cath/CathServer.pl) providing automatic classification of newly determined sequences and structures using a suite of rapid sequence and structure comparison methods. The statistical significance of matches is assessed and links are provided to the putative superfamily or fold group to which the query sequence or structure is assigned
A supportive text message intervention for individuals living with endometriosis (EndoSMS) : randomized controlled pilot and feasibility trial
Introduction: As a high symptom burden chronic condition, endometriosis is associated with diminished quality of life (QoL) and psychological distress. The EndoSMS text message intervention was developed to inform and support individuals living with endometriosis. The primary aim of this study is to assess the acceptability, feasibility and preliminary efficacy of EndoSMS, to improve endometriosis-specific QoL and reduce psychological distress in a randomised controlled trial, compared with care as usual. We will additionally assess the impact of EndoSMS on self-efficacy for managing endometriosis. Methodology: A two-arm parallel pilot randomised controlled trial with waitlist control was conducted. Baseline assessments included QoL, psychological distress, self-efficacy, demographic and medical variables. Following baseline survey completion, participants were randomised to either the Intervention (EndoSMS: 3-months of text messaging) or Control condition. At 3-month follow-up, all participants completed an online survey reassessing outcomes, and Intervention participants provided quantitative and qualitative user feedback on EndoSMS. Results: Data collection commenced on 18 November 2021 and was completed on 30 March 2022. Descriptive statistics will be used to analyse feasibility and acceptability of the intervention. Preliminary efficacy analyses will be conducted using linear mixed models for QoL, psychological distress and self-efficacy outcomes. Subgroup analyses will also be conducted for typically underserved populations (e.g., rural/regional). Conclusion: This pilot will provide acceptability, feasibility and preliminary efficacy evidence for the impact of a supportive text messaging program for endometriosis. It will contribute to understanding how to optimally support individuals in living with and managing their endometriosis. Trial Registration: Australian New Zealand Clinical Trials Registry
Optical phonons, OH vibrations, and structural modifications of phlogopite at high temperatures: An in-situ infrared spectroscopic study
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