44 research outputs found
Improved Sensitivity for Space Domain Awareness Observations with the Murchison Widefield Array
Our previously reported survey of the Low Earth Orbit (LEO) environment using
the Murchison Widefield Array (MWA) detected over 70 unique Resident Space
Objects (RSOs) over multiple passes, from 20 hours of observations in passive
radar mode. In this paper, we extend this work by demonstrating two methods
that improve the detection sensitivity of the system. The first method, called
shift-stacking, increases the statistical significance of faint RSO signals
through the spatially coherent integration of the reflected signal along the
RSO's trajectory across the sky. This method was tested on the observations
used during our previous blind survey, and we obtained a increase in the
total number of detections. The second method re-focuses the MWA to the
near-field RSO's position (post-observation), by applying a complex phase
correction to each visibility to account for the curved wave-front. The method
was tested successfully on an MWA extended array observation of an ISS pass.
However, the method is currently limited by signal de-coherence on the
long-baselines (due to the hardware constraints of the current correlator). We
discuss the sensitivity improvement for RSO detections we expect from the MWA
Phase 3 correlator upgrade. We conclude the paper by briefly commenting on
future dedicated Space Domain Awareness (SDA) systems that will incorporate MWA
technologies.Comment: Accepted in Advances in Space Research. 16 pages, 10 figures, and 1
Tabl
Recommendations for using Artificial Intelligence and Machine Learning for Holocaust Memory and Education
Activity pacing: moving beyond taking breaks and slowing down
This brief communication responds to the paper by Jeong and Cho (Qual Life Res 26(4):903–911, 2017) that has described activity pacing in limited terms of adjusting activities through going at a slower rate and taking breaks. Activity pacing was reported as not involving goal setting, in comparison to other strategies for long-term conditions such as Acceptance and Commitment Therapy. This brief communication aims to challenge this limited perception of activity pacing in light of numerous studies that recognise pacing to be a more complex strategy. Pacing is considered to be a multifaceted coping strategy, including broad themes of not only adjusting activities, but also planning activities, having consistent activity levels, acceptance of current abilities and gradually increasing activities, and one that includes goal setting as a key facet. It is essential that pacing is both defined and measured as a multifaceted strategy in order to assess the outcomes of pacing, and for meaningful comparisons with other strategies regarding efficacy for the management of long-term conditions
Emotion and ethics: an inter-(en)active approach
The original publication is available at www.springerlink.comIn this paper we start exploring the affective and ethical dimension of what De Jaegher and Di
Paolo (2007) have called ‘participatory sense-making’. In the first part, we distinguish
various ways in which we are, and feel, affectively inter-connected in interpersonal
encounters. In the second part, we discuss the ethical character of this affective interconnectedness,
as well as the implications that taking an ‘inter-(en)active approach’ has for
ethical theory itself
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Complete vertebrate mitogenomes reveal widespread repeats and gene duplications
Abstract: Background: Modern sequencing technologies should make the assembly of the relatively small mitochondrial genomes an easy undertaking. However, few tools exist that address mitochondrial assembly directly. Results: As part of the Vertebrate Genomes Project (VGP) we develop mitoVGP, a fully automated pipeline for similarity-based identification of mitochondrial reads and de novo assembly of mitochondrial genomes that incorporates both long (> 10 kbp, PacBio or Nanopore) and short (100–300 bp, Illumina) reads. Our pipeline leads to successful complete mitogenome assemblies of 100 vertebrate species of the VGP. We observe that tissue type and library size selection have considerable impact on mitogenome sequencing and assembly. Comparing our assemblies to purportedly complete reference mitogenomes based on short-read sequencing, we identify errors, missing sequences, and incomplete genes in those references, particularly in repetitive regions. Our assemblies also identify novel gene region duplications. The presence of repeats and duplications in over half of the species herein assembled indicates that their occurrence is a principle of mitochondrial structure rather than an exception, shedding new light on mitochondrial genome evolution and organization. Conclusions: Our results indicate that even in the “simple” case of vertebrate mitogenomes the completeness of many currently available reference sequences can be further improved, and caution should be exercised before claiming the complete assembly of a mitogenome, particularly from short reads alone