Shotgun metagenomics of dust microbiome from flight deck and cabin in civil aviation aircraft

Microbial exposure is related to the health of passengers on commercial aircraft, but no studies characterized the microbial composition at the species level and identified their ecological determinants. We collected vacuum dust from floor and seat surfaces in flight decks and cabins of 18 aircraft, and amplification-free shotgun metagenomics was conducted to characterize the microbial composition. In total, 7437 microbial taxa were identified. The relative abundance for bacteria, eukaryote, viruses, and archaea was 96.9%, 1.8%, 0.3%, and 0.03%, respectively. The top bacterial species mainly derived from outdoor air and human skin included Sphingomonas, Corynebacterium, Micrococcus luteus, Variovorax paradoxus, Paracoccus dentrificans, and Propionibacterium acnes. The abundance of NIAID-defined pathogens was low, accounted for only 0.23% of total microbes. The microbial species and functional composition were structured by the indoor surface type (R² = 0.38, Adonis), followed by the manufacturer of the aircraft (R² = 0.12) and flight duration (R² = 0.07). Indoor surfaces affected species derived from different habitats; the abundance of dry skin and desiccated species was higher on textile surfaces, whereas the abundance of moist and oily skin species was higher on leather surfaces. The growth rates for most microbes were stopped and almost stopped.     

Modelling of two-dimensional flame spread across a sloping fuel bed

A significant contributing factor to wildland fire development is the slope effect which causes the fire spread rate to increase considerably as compared to horizontal spread. This leads to difficulties in determining the development of the fires hence in coordinating forest fighting efforts. In the present study, a two-dimensional non-stationary model for a fire spreading across a sloping fuel bed made up of Pinus pinaster litter is described. Based on a series of hypotheses, we first defined a medium equivalent to the pine needle litter for which we provided a thermal balance. By coupling this balance to a diffusion flame model we obtained the fire spread model numerically solved by means of the SIMPLEC procedure. The fire spread rates given by the simulations were then compared to experimental results generated by small-scale laboratory fires for a range of slope values. Predicted flow field structure, and temperature field are also discussed.     

Interface instability in the drawing process of copper/tantalum conductors

Copper/tantalum test billets have been cold drawn, using the process developed for the elaboration of copper/niobium multifilamentary conductors, for the development of high strength and high conductivity conductors for high pulsed magnetic fields. After a section reduction of 60%, a macroscopic roughness of the tantalum surface has been observed: two sets of perpendicular undulations developed (parallel and perpendicular to the drawing axis), with wavelengths in the 100 μm range. This phenomenon, observed for the first time on bulk materials, is interpreted in terms of the Grinfeld instability: the associated wavelength, calculated in the case of a shear stress discontinuity at the interface between b.c.c. tantalum and f.c.c. copper, is found in the right magnitude range.     

Generation Adequacy: Who Decides?

While market-based methods for generation expansion are the preferred long-term approach, there is currently too much uncertainty regarding how consumers and suppliers will respond to spot price signals. Therefore, policymakers should encourage demand-side experiments and investments to ensure that, when prices rise, customers will be able to respond.     

Automatic devices' resolution in nuclear emulsion observation

Some results on the precision obtainable using automatic devices in nuclear emulsion measurements and simplified methods for their application in standard work are presented.     

Survival analysis,consumer perception and physico-chemical analysis of low fat UHT milk stored for different time periods

Survival analysis based on consumers' acceptance or rejection of milk of different storage ages, was used to validate the shelf-life of low fat ultra-high temperature treated (UHT) milk in high density polyethylene bottles, as previously determined by a multivariate accelerated shelf-life test (MASLT). UHT milk between 120 and 290 d of storage were evaluated. Based on 50% of consumers rejecting the product, the shelf-life was estimated to be 214 d, validating the shelf-life of 211 d estimated by the MASLT. In addition, consumers completed check-all-that-apply attribute questions and rated the acceptability of the milk. The consumers noted positive sensory attributes more frequently in fresher milk samples with an increase in negative attributes with storage. Along with this, hedonic scores for the milk decreased and physicochemical and enzymatic reactions associated with the deterioration of UHT milk increased with storage.