In addition to precise 3D coordinates, most light detection and ranging (LIDAR) systems also record "intensity", loosely defined as the strength of the backscattered echo for each measured point. To ...date, LIDAR intensity data have proven beneficial in a wide range of applications because they are related to surface parameters, such as reflectance. While numerous procedures have been introduced in the scientific literature, and even commercial software, to enhance the utility of intensity data through a variety of "normalization", "correction", or "calibration" techniques, the current situation is complicated by a lack of standardization, as well as confusing, inconsistent use of terminology. In this paper, we first provide an overview of basic principles of LIDAR intensity measurements and applications utilizing intensity information from terrestrial, airborne topographic, and airborne bathymetric LIDAR. Next, we review effective parameters on intensity measurements, basic theory, and current intensity processing methods. We define terminology adopted from the most commonly-used conventions based on a review of current literature. Finally, we identify topics in need of further research. Ultimately, the presented information helps lay the foundation for future standards and specifications for LIDAR radiometric calibration.
Freedom of design, mass customisation, waste minimisation and the ability to manufacture complex structures, as well as fast prototyping, are the main benefits of additive manufacturing (AM) or 3D ...printing. A comprehensive review of the main 3D printing methods, materials and their development in trending applications was carried out. In particular, the revolutionary applications of AM in biomedical, aerospace, buildings and protective structures were discussed. The current state of materials development, including metal alloys, polymer composites, ceramics and concrete, was presented. In addition, this paper discussed the main processing challenges with void formation, anisotropic behaviour, the limitation of computer design and layer-by-layer appearance. Overall, this paper gives an overview of 3D printing, including a survey on its benefits and drawbacks as a benchmark for future research and development.
Association studies have linked microbiome alterations with many human diseases. However, they have not always reported consistent results, thereby necessitating cross-study comparisons. Here, a ...meta-analysis of eight geographically and technically diverse fecal shotgun metagenomic studies of colorectal cancer (CRC, n = 768), which was controlled for several confounders, identified a core set of 29 species significantly enriched in CRC metagenomes (false discovery rate (FDR) < 1 × 10
). CRC signatures derived from single studies maintained their accuracy in other studies. By training on multiple studies, we improved detection accuracy and disease specificity for CRC. Functional analysis of CRC metagenomes revealed enriched protein and mucin catabolism genes and depleted carbohydrate degradation genes. Moreover, we inferred elevated production of secondary bile acids from CRC metagenomes, suggesting a metabolic link between cancer-associated gut microbes and a fat- and meat-rich diet. Through extensive validations, this meta-analysis firmly establishes globally generalizable, predictive taxonomic and functional microbiome CRC signatures as a basis for future diagnostics.
The effect of the alkali activation reaction on the characteristics of slag-based foams made by the mechanical foaming technique is investigated. The mechanical foaming method is selected in order to ...control the density and quantity of the pre-made foam and minimise the impact of alkali reaction on the amount of initial foaming. Despite the similarity of the pre-made foams mixed with the altered binder formulae, a change in the alkali reaction is shown to affect the pore size distribution, pore homogeneity, density and properties of the inorganic foams. The water content of the binders is shown to be the key factor affecting the bubble breakage and foam sorting during the mechanical mixing stage. Later in the reaction, the reaction rate of the binders and the size of the gel particulates govern the pore size distribution and directional homogeneity of pore distribution within the matrix. Also, the reaction rate and the size of the gel particulates regulate the final density of the inorganic foams. The thermal conductivity is higher in the samples with higher density, but it is largely affected by the directional homogeneity of pore distribution. Apart from the strength of binding matrix and size distribution of pores, the directional homogeneity of porosity is shown to be the vital factor for high strength development.
Same amount of premade foam with the same density is added to three different mix formulations of alkali activated slag binders, and the impact of alkali reaction on foam characteristics is investigated. It is shown that characteristics of the inorganic foams don't have to be controlled by the quality and quantity of pre-made foam blended with them. It is possible to control the density and properties of inorganic binders by manipulating their mix formulation. Display omitted
•Alkali reaction can be altered to control the characteristics of slag-based foams.•The water content is the key factor in bubble arrangement during mixing stage.•Thermal conductivity is largely affected by homogeneity of pore distribution.•Homogeneity of porosity is the vital factor for high strength development.
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•Surface chemistry controls rheology in alkali-activated slag cements.•Particle–particle interactions and gelation influenced by activator nature.•Yield stress depends on square of ...zeta potential.•Silicate and hydroxide activators differ notably in behavior.•Influence of pH on fresh paste chemistry is indirect.
Ground granulated blast furnace slag can react with an alkaline activating solution to form a cement-like binder based on a calcium–sodium aluminosilicate gel, which is a potential alternative to Portland cement in many applications. This study provides new information regarding the effect of activator type and dosage on rheology by monitoring changes in pH, particle surface charge (zeta potential), and heat evolution in the early stages of the reaction process. Sodium and potassium hydroxide silicate solutions, at two different M2O (M: Na, K) dosages, are used here as activators. Alkali hydroxide activators cause a significant increase in the yield stress of an activated slag paste, especially at higher dosages as reactions take place rapidly, while within the same timeframe, the yield stress of the silicate activated slag remains unchanged. The results imply a direct relationship between a higher reaction rate with the formation of solid products (causing both spatial blockage effects and consumption of free water), and a rapid yield stress increase. However, the dependence of reaction rate on pH for different alkali-activated pastes is, at most, indirect. All activators induce a highly alkaline pH and a concentrated electrolyte solution environment in the fluid paste. As a result of complexation of poorly-hydrated ions on the surfaces of the particles, the magnitude of the zeta potential increases. A direct relationship is observed between the dosage of the activators and zeta potential. A zeta potential further from neutrality generally reduces yield stress by increasing the magnitude of double layer repulsive forces, with the exception of a higher dosage of silicate activator, which shows an indication of some attractive double layer forces.
Methods that integrate molecular network information and tumor genome data could complement gene-based statistical tests to identify likely new cancer genes; but such approaches are challenging to ...validate at scale, and their predictive value remains unclear. We developed a robust statistic (NetSig) that integrates protein interaction networks with data from 4,742 tumor exomes. NetSig can accurately classify known driver genes in 60% of tested tumor types and predicts 62 new driver candidates. Using a quantitative experimental framework to determine in vivo tumorigenic potential in mice, we found that NetSig candidates induce tumors at rates that are comparable to those of known oncogenes and are ten-fold higher than those of random genes. By reanalyzing nine tumor-inducing NetSig candidates in 242 patients with oncogene-negative lung adenocarcinomas, we find that two (AKT2 and TFDP2) are significantly amplified. Our study presents a scalable integrated computational and experimental workflow to expand discovery from cancer genomes.
Little is known about the effect of long-term diet patterns on the composition and functional potential of the human salivary microbiota. In the present study, we sought to contribute to the ongoing ...elucidation of dietary effects on the oral microbial community by examining the diversity, composition and functional potential of the salivary microbiota in 160 healthy vegans and omnivores using 16S rRNA gene amplicon sequencing. We further sought to identify bacterial taxa in saliva associated with host inflammatory markers. We show that compositional differences in the salivary microbiota of vegans and omnivores is present at all taxonomic levels below phylum level and includes upper respiratory tract commensals (e.g. Neisseria subflava, Haemophilus parainfluenzae, and Rothia mucilaginosa) and species associated with periodontal disease (e.g. Campylobacter rectus and Porphyromonas endodontalis). Dietary intake of medium chain fatty acids, piscine mono- and polyunsaturated fatty acids, and dietary fibre was associated with bacterial diversity, community structure, as well as relative abundance of several species-level operational taxonomic units. Analysis of imputed genomic potential revealed several metabolic pathways differentially abundant in vegans and omnivores indicating possible effects of macro- and micro-nutrient intake. We also show that certain oral bacteria are associated with the systemic inflammatory state of the host.
Using solar systems is increasing due to oil shortage, environmental effects, and renewability. Solar thermal combisystems use the energy taken to provide for both domestic hot water (DHW) and space ...heating (SH), which is under investigation by energy researchers. This study uses a dynamic energy analysis of the solar system to evaluate the solar parameters. Also, the environmental and economic effects of using solar systems are discussed. The study is done on four different consumption usages in four different climates of Iran. Energy simulation shows that hot & humid climates, office, and mall usages have the largest solar fraction (minimum of 95.2, 38.5, and 35%, respectively). The lowest optimal collector surface area belongs to a hot and humid climate with 4–21.5 m2 and office usage with 4–159 m2. Also, collector efficiency decreases with higher collector area amounts. 20-year economic analysis shows that the net present value of hospital usage with a maximum of $2216.8, cold climate with a maximum of $768.4, and hot & humid climate with a maximum of $2765.9 are the most affordable. The environmental analysis illustrates that CO2 emission avoidance is highest in hospital usage with a maximum of 1924.5 kg, residential usage with a maximum of 1707.8 kg, and hot & dry climate with a maximum of 1349.2 kg. Lastly, the preference selection index (PSI) method is used to rank all application possibilities, which shows that using systems is highly recommended in cold, hot & humid climates with the best ranks of 1 and 3 and hospital usage with the best rank of 1.
•Solar fraction of solar thermal combisystems can reach up to 95% in hot and humid climate.•Collector efficiency is higher in low collector areas.•Economic analysis shows that cold and hot and humid climates are mostly affordable.•Environmental analysis indicates that residential and hospital usages avoids more CO2 emissions.•PSI method of mathematical prioritizing is used to rank choices.
•Computed tomography showed thermally induced changes in pores of concrete.•Expansion of pores reduced surface cracking via water vapour pressure release.•Higher Na/Al decreased strength but ...increased post-heated strength retention.•Lower Si/Al exhibited the lowest strength but the best thermal stability.•Thermal performance of alkali-activated slag-fly ash is better than Portland cement.
The effects of Si/Al, Na/Al and water/solids ratios on thermal performance of alkali-activated materials (AAM) based on fly ash-slag blends are investigated. Higher Na/Al decreased compressive strength but increased post-heated strength retention and mass loss while reducing cracking at 1000°C. Lower Si/Al resulted in lowest initial strength but highest thermal stability, with an increase in strength after exposure to 1000°C, while a high degree of cracking was observed at higher Si/Al ratio. The effect of w/s on thermal performance was subtle. Computed tomography analysis showed for the first time thermally induced expansion of pores which reduced surface cracking via water vapour pressure release. Thermal performance of alkali-activated materials (AAM) is significantly better than Portland cement (PC) of the same compressive strength because of the very low bound water content. The porosity, pore connectivity and number of pores of the AAM were considerably higher than those in the PC binder.
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•Developed framework to utilize 3D laser scanning data to evaluate sight distances.•Compared framework to conventional techniques for validation.•Evaluated visibility changes during ...vehicle turning movements.•Considered multi-modal visibility.•Provided 3D viewsheds that can help agencies manage sight distance obstructions.
Sight distance analyses require careful and detailed field measurements to facilitate proper engineering decision making regarding the removal of obstructions, establishment of regulatory and advisory speed limits, and the location of new access points, among numerous other purposes. However, conventional field measurements for these analyses present safety concerns because they require personnel to be in or adjacent to traffic lanes. They can also be time consuming, costly, and labor intensive. Furthermore, the predominantly two-dimensional (2D) methods involve simplifying assumptions such as a “standard” vehicle heights and lengths without considering the wide range of vehicles and drivers present on the road. Recently, many transportation agencies worldwide have begun to acquire mobile lidar data to map their roadway assets. These data provide a rich three-dimensional (3D) environment that enables one to virtually visit a site at any frequency and efficiently evaluate sight distances from the safety of the office. This study investigates advanced safety analysis methodologies for drivers’ sight distance based on high resolution lidar data. The developed simulation method enables users to virtually evaluate available sight distances in a 3D context considering a variety of objects, vehicle types, and multi-modal forms of transportation (e.g., bicycle, pedestrian). The feasibility of this technique was analyzed with a case study at an intersection located in Corvallis, Oregon, USA. The experimental results demonstrated the ability of the proposed methodology to capture significantly more detail on visibility constraints when compared with conventional measurements as well as provide more flexibility in the analysis.
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