CNN-Based Spectral Super-Resolution of Panchromatic Night-Time Light Imagery: City-Size-Associated Neighborhood Effects

Data on artificial night-time light (NTL), emitted from the areas, and captured by satellites, are available at a global scale in panchromatic format. In the meantime, data on spectral properties of NTL give more information for further analysis. Such data, however, are available locally or on a commercial basis only. In our recent work, we examined several machine learning techniques, such as linear regression, kernel regression, random forest, and elastic map models, to convert the panchromatic NTL images into colored ones. We compared red, green, and blue light levels for eight geographical areas all over the world with panchromatic light intensities and characteristics of built-up extent from spatially corresponding pixels and their nearest neighbors. In the meantime, information from more distant neighboring pixels might improve the predictive power of models. In the present study, we explore this neighborhood effect using convolutional neural networks (CNN). The main outcome of our analysis is that the neighborhood effect goes in line with the geographical extent of metropolitan areas under analysis: For smaller areas, optimal input image size is smaller than for bigger ones. At that, for relatively large cities, the optimal input image size tends to differ for different colors, being on average higher for red and lower for blue lights. Compared to other machine learning techniques, CNN models emerged comparable in terms of Pearson’s correlation but showed performed better in terms of WMSE, especially for testing datasets.

Methylobacterium ajmalii sp. nov., Isolated From the International Space Station

Four strains belonging to the family of Methylobacteriaceae were isolated from different locations on the International Space Station (ISS) across two consecutive flights. Of these, three were identified as Gram-negative, rod-shaped, catalase-positive, oxidase-positive, motile bacteria, designated as IF7SW-B2^T, IIF1SW-B5, and IIF4SW-B5, whereas the fourth was identified as Methylorubrum rhodesianum. The sequence similarity of these three ISS strains, designated as IF7SW-B2^T, IIF1SW-B5, and IIF4SW-B5, was <99.4% for 16S rRNA genes and <97.3% for gyrB gene, with the closest being Methylobacterium indicum SE2.11^T. Furthermore, the multi-locus sequence analysis placed these three ISS strains in the same clade of M. indicum. The average nucleotide identity (ANI) values of these three ISS strains were <93% and digital DNA-DNA hybridization (dDDH) values were <46.4% with any described Methylobacterium species. Based on the ANI and dDDH analyses, these three ISS strains were considered as novel species belonging to the genus Methylobacterium. The three ISS strains showed 100% ANI similarity and dDDH values with each other, indicating that these three ISS strains, isolated during various flights and from different locations, belong to the same species. These three ISS strains were found to grow optimally at temperatures from 25 to 30°C, pH 6.0 to 8.0, and NaCl 0 to 1%. Phenotypically, these three ISS strains resemble M. aquaticum and M. terrae since they assimilate similar sugars as sole carbon substrate when compared to other Methylobacterium species. Fatty acid analysis showed that the major fatty acid produced by the ISS strains are C_18:1−ω7c and C_18:1−ω6c. The predominant quinone was ubiquinone 10, and the major polar lipids were diphosphatidylglycerol, phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and an unidentified lipid. Therefore, based on genomic, phylogenetic, biochemical, and fatty acid analyses, strains IF7SW-B2^T, IIF1SW-B5, and IIF4SW-B5, are assigned to a novel species within the genus Methylobacterium, and the name Methylobacterium ajmalii sp. nov. is proposed. The type strain is IF7SW-B2^T (NRRL B-65601^T and LMG 32165^T).

Persistent Globe Flattening in Astronauts following Long-Duration Spaceflight

Posterior globe flattening has been well-documented in astronauts both during and after long-duration space flight (LDSF) and has been observed as early as 10 days into a mission on the International Space Station. Globe flattening (GF) is thought to be caused by the disc centred anterior forces created by elevated volume and/or pressure within the optic nerve sheath (ONS). This might be the result of increased intracranial pressure, increased intraorbital ONS pressure from compartmentalisation or a combination of these mechanisms. We report posterior GF in three astronauts that has persisted for 7 years or more following their return from LDSFs suggesting that permanent scleral remodelling may have occurred.

Fused Filament Fabrication of PEEK: A Review of Process-Structure-Property Relationships

Poly (ether ether ketone) (PEEK) is a high-performance engineering thermoplastic polymer with potential for use in a variety of metal replacement applications due to its high strength to weight ratio. This combination of properties makes it an ideal material for use in the production of bespoke replacement parts for out-of-earth manufacturing purposes, in particular on the International Space Station (ISS). Additive manufacturing (AM) may be employed for the production of these parts, as it has enabled new fabrication pathways for articles with complex design considerations. However, AM of PEEK via fused filament fabrication (FFF) encounters significant challenges, mostly stemming from the semi crystalline nature of PEEK and its associated high melting temperature. This makes PEEK highly susceptible to changes in processing conditions which leads to a large reported variation in the literature on the final performance of PEEK. This has limited the adaption of FFF printing of PEEK in space applications where quality assurance and reproducibility are paramount. In recent years, several research studies have examined the effect of printing parameters on the performance of the 3D-printed PEEK parts. The aim of the current review is to provide comprehensive information in relation to the process-structure-property relationships in FFF 3D-printing of PEEK to provide a clear baseline to the research community and assesses its potential for space applications, including out-of-earth manufacturing.