Forests account for a substantial part of the terrestrial biomass storage and productivity. To better understand forest productivity, we need to disentangle the processes underlying net biomass ...change. We tested how above‐ground net biomass change and its underlying biomass dynamics (biomass recruitment, growth and mortality) can be explained by four alternative and contested hypotheses; the soil fertility, biomass ratio, niche complementarity and vegetation quantity hypotheses. Above‐ground biomass dynamics were evaluated over a 5‐year period in 200 permanent sample plots in 8 tropical dry forests in Brazil, and related to soil fertility, community‐weighted mean (CWM) traits that are important for carbon storage and sequestration (wood density, specific leaf area, maximum stem diameter and deciduousness), species richness, functional diversity and initial stand biomass. Initial stand biomass was the best predictor of all three processes of biomass dynamics, providing strong support for the vegetation quantity hypothesis. In these dry forests, the dominance of conservative species, rather than of acquisitive species, is associated with high biomass growth and storage, probably because their low specific leaf area and high wood density allow them to keep on functioning during drought stress. Paradoxically, high soil fertility (Ca) led to low biomass productivity, probably because of nutrient imbalance. In contrast to what is shown for controlled experiments, we found no support for niche complementarity (in terms of functional diversity or species richness) for forest productivity. Biomass storage was favoured by low‐ rather than high trait diversity, as most of the biomass is concentrated in species with large stem diameter and high wood density. Synthesis. Biomass dynamics are mainly shaped by vegetation quantity, and then by vegetation quality, in line with the mass ratio hypothesis. Dry forests show different trait‐productivity relationships than wet forests, as stands with ‘slow’ trait values are ‘fast’ in terms of productivity. Diversity matters, but in a different way than expected; high trait diversity does not enhance productivity, but instead, does low trait diversity enhance carbon storage.
Mosquito control with bednets, residual sprays or fumigation remains the most effective tool for preventing vector-borne diseases such as malaria, dengue and Zika, though there are no widely used ...entomological methods for directly assessing its efficacy. Mosquito age is the most informative metric for evaluating interventions that kill adult mosquitoes but there is no simple or reliable way of measuring it in the field. Near-Infrared Spectroscopy (NIRS) has been shown to be a promising, high-throughput method that can estimate the age of mosquitoes. Currently the ability of NIRS to measure mosquito age is biased, and has relatively high individual mosquito measurement error, though its capacity to rigorously monitor mosquito populations in the field has never been assessed. In this study, we use machine learning methods from the chemometric literature to generate more accurate, unbiased estimates of individual mosquito age. These unbiased estimates produce precise population-level measurements, which are relatively insensitive to further increases in NIRS accuracy when feasible numbers of mosquitoes are sampled. The utility of NIRS to directly measure the impact of pyrethroid resistance on mosquito control is illustrated, showing how the technology has potential as a highly valuable tool for directly assessing the efficacy of mosquito control interventions.
•1-D numerical TEG model in diesel freight vehicles exhaust pipe.•Over 800W of electrical power for the heavy-duty vehicle.•Plain fins provide better performance than offset strip fins.•The height of ...the thermocouple legs plays a significant role.•2% maximum efficiency needs further improvements.
A parametric study and optimization approaches of a thermoelectric generator (TEG) for the recovery of energy from the exhaust gas in Diesel vehicles used in freight transport is reported. The TEG is installed in the tailpipe of a commercial vehicle (3.5tonnes) and a heavy-duty vehicle (40tonnes). The exhaust gas is used as the heat source and the cooling water as the heat sink. Two different heat exchanger configurations are considered: plain fins and offset strip fins. The influence of the height, length and spacing of the fins on the electrical and net power is analysed for the fixed width and length of the TEG. The influence of the length and width of the TEG and of the height of the thermocouple legs is also investigated. According to the criteria used in this study, plain fins are the best choice, yielding a maximum electrical power of 188W for the commercial vehicle and 886W for the heavy-duty vehicle. The best recovery efficiency is about 2%, with an average thermoelectric material efficiency of approximately 4.4%, for the light-duty vehicle. Accordingly, there is significant room for further improvement and optimisation based on the thermoelectric modules and the system design.
•Lactobacilli are a prolific source of functional, human-associated enzymes.•Lactase, proteases, fructanases, amylases, bile salt hydrolases, phytases, and esterases are the main enzymes ...reported.•Lactobacilli inhibit harmful enzymes secreted by pathogenic organisms.•Enzymatic activity of lactobacilli is exerted in a strain-dependent manner.•Lactobacilli selection, patents, commercial products, and administration are discussed in this review.
Complex carbohydrates, proteins, and other food components require a longer digestion process to be absorbed by the lining of the alimentary canal. In addition to the enzymes of the gastrointestinal tract, gut microbiota, comprising a large range of bacteria and fungi, has complementary action on the production of digestive enzymes. Within this universe of "hidden soldiers", lactobacilli are extensively studied because of their ability to produce lactase, proteases, peptidases, fructanases, amylases, bile salt hydrolases, phytases, and esterases. The administration of living lactobacilli cells has been shown to increase nutrient digestibility. However, it is still little known how these microbial-derived enzymes act in the human body. Enzyme secretion may be affected by variations in temperature, pH, and other extreme conditions faced by the bacterial cells in the human body. Besides, lactobacilli administration cannot itself be considered the only factor interfering with enzyme secretion, human diet (microbial substrate) being determinant in their metabolism. This review highlights the potential of lactobacilli to release functional enzymes associated with the digestive process and how this complex metabolism can be explored to contribute to the human diet. Enzymatic activity of lactobacilli is exerted in a strain-dependent manner, i.e., within the same lactobacilli species, there are different enzyme contents, leading to a large variety of enzymatic activities. Thus, we report current methods to select the most promising lactobacilli strains as sources of bioactive enzymes. Finally, a patent landscape and commercial products are described to provide the state of art of the transfer of knowledge from the scientific sphere to the industrial application.
Knowledge of sediment movement throughout a catchment environment is essential due to its influence on the character and form of our landscape relating to agricultural productivity and ecological ...health. Sediment fingerprinting is a well-used tool for evaluating sediment sources within a fluvial catchment but still faces areas of uncertainty for applications to large catchments that have a complex arrangement of sources. Sediment fingerprinting was applied to the Manawatu River Catchment to differentiate 8 geological and geomorphological sources. The source categories were Mudstone, Hill Subsurface, Hill Surface, Channel Bank, Mountain Range, Gravel Terrace, Loess and Limestone. Geochemical analysis was conducted using XRF and LA-ICP-MS. Geochemical concentrations were analysed using Discriminant Function Analysis and sediment un-mixing models. Two mixing models were used in conjunction with GRG non-linear and Evolutionary optimization methods for comparison. Discriminant Function Analysis required 16 variables to correctly classify 92.6% of sediment sources. Geological explanations were achieved for some of the variables selected, although there is a need for mineralogical information to confirm causes for the geochemical signatures. Consistent source estimates were achieved between models with optimization techniques providing globally optimal solutions for sediment quantification. Sediment sources was attributed primarily to Mudstone, ≈38–46%; followed by the Mountain Range, ≈15–18%; Hill Surface, ≈12–16%; Hill Subsurface, ≈9–11%; Loess, ≈9–15%; Gravel Terrace, ≈0–4%; Channel Bank, ≈0–5%; and Limestone, ≈0%. Sediment source apportionment fits with the conceptual understanding of the catchment which has recognized soft sedimentary mudstone to be highly susceptible to erosion. Inference of the processes responsible for sediment generation can be made for processes where there is a clear relationship with the geomorphology, but is problematic for processes which occur within multiple terrains.
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•16 geochemical variables classified 8 sediment sources with 92.6% accuracy.•Mudstone was the dominant source of sediment of ≈38–46%.•The four un-mixing model scenarios exhibited consistent estimates.•Erosion process—source sediment connections remain unclear in complex environments.
Suspended fine sediment has a significant impact on freshwater quality variables such as visual clarity (VC). However, freshwater quality is related to the attributes of the catchment sources ...contributing fine sediment to the stream network. Here, the extent to which an array of sources defined spatially according to erosion process and geological parent material may be discriminated and classified based on sediment-related water quality (SRWQ) attributes that potentially affect VC was examined. Erosion sources were sampled across two New Zealand catchments representing six types of erosion and eight parent materials. Erosion source measurements focused on particle size, organic matter content, and light beam attenuation (which is convertible to VC). The source data were analysed to: 1) evaluate source variability using a combination of Kruskal-Wallis and principal component analysis; 2) reclassify sources using a Random Forest model; and 3) demonstrate how erosion source affects VC for a range of theoretical sediment concentrations (SC) using a simple empirical model. The results indicate that SRWQ attributes show significant variation across erosion sources. The extent to which attributes differed between sources often related to whether there was a strong association between a specific erosion process and parent material. The 19 a priori source classifications were reduced to 5 distinct sources that combined erosion process and parent material (i.e., bank erosion–alluvium; mass movement–ancient volcanics; mass movement–sedimentary; surficial erosion; gully–unconsolidated sandstone). At low SC, the impact of erosion source on VC became most evident ranging from 2.6 to 5.6 m at SC of 5 g m−3. These findings show how catchment sources of sediment, in addition to sediment concentration, influence VC, and highlight the need to consider quality as well as quantity of material supplied to stream networks when planning erosion control.
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•Sediment-related water quality (SRWQ) attributes affect visual clarity.•SRWQ attributes showed significant variation across all erosion sources.•Most sources showed considerable overlap in their SRWQ attributes.•19 a priori source classifications could be reduced to 5 distinct sources.•Erosion sources may potentially produce a large visual clarity range at low flow.
Active accessibility Vale, David S.; Saraiva, Miguel; Pereira, Mauro
Journal of transport and land use,
01/2016, Volume:
9, Issue:
1
Journal Article
Peer reviewed
Open access
Active travel is enthusiastically promoted in the Western world due to its clear and demonstrated individual and collective benefits. While active travel has been shown to be associated with features ...of the built environment such as density and land-use mix, it is also associated with walking and cycling accessibility-which we designate as active accessibility. However, the measurement of active accessibility is not straightforward and it can represent significantly different features of the built environment. This paper presents an extensive review of published research that measures active accessibility. We classified the literature into four categories based on the methodology used: distance-based, gravity-based or potential, topological or infrastructure-based, and walkability and walk score-type measures. A fifth category was created to classify outliers consisting of distinct methodological approaches or hybrids of the four main categories. We argue that almost all of these methods have conceptual and computational limitations, and that there are inconsistencies in the use of concepts and terms. Furthermore, no sensitivity analysis was carried out on the selected parameters. We conclude by presenting some guidelines that might improve the value and clarity of active accessibility research, theory, and practice.
As a result of mounting concerns over the adverse ecological and socio-economic effects of mobility systems dominated by individual motorized transport, metropolitan areas worldwide have expressed a ...renewed interest in the role of public transport. Like many other metropolitan areas, the Brussels Capital Region (BCR) faces the problem of an increasingly congested transport system. Against this backdrop, the Regional Express Railway (RER) network is intended as a rapid-transit railway system serving an area of 30 km around the region, with the objective of improving the capacity and frequency of the railway services between the BCR and its periphery. In order to inform policy prescription, this paper reports on a systematic empirical assessment of all RER railway stations in terms of transport and land use characteristics, by drawing on the node-place modeling and transit oriented development literature. The proposed accessibility instrument considers different catchment area sizes in order to increase its empirical basis. Based on this systematic railway station inventory, cluster analysis was conducted revealing seven comparative accessibility profiles, of which some prove highly robust over the different precinct sizes. When combining the quantitative analyses reported in this paper with the more intuitive expertise of practitioners and stakeholders involved in the planning process, the accessibility instrument may effectively assist the identification of differentiated development opportunities for the RER stations.
•We combined the node-place model with pedestrian friendliness evaluation.•Results show it is useful to identify and classify a station area.•We suggest a typology of station areas based on the three ...components.•It can be used as a planning tool for the development of balanced TOD areas.
Transit-oriented development is being actively promoted as an urban design model for areas around transit stations. In addition, planning for accessibility is being promoted, which requires integrating land use with transportation planning, and to match the transportation features with the intensity and diversity of land use of the station areas. Nevertheless, and despite the evident similarities between the two approaches, an integrated evaluation tool of a station area in terms of its transportation, land use, and urban design features is missing. In this paper, we bring into the literature on integration of land use and transport a key feature of the transit-oriented development literature: the urban design features of the station areas, in particular their pedestrian friendliness. By complementing the node-place model with an evaluation of the pedestrian connectivity of station areas of Lisbon, we combine these two perspectives in order to evaluate and classify station areas in three different aspects: land use, transportation, and walkability conditions. Our results show that a balanced node-place is not necessarily a transit-oriented development, and vice versa, and so a complementary analysis of both is useful to identify and classify a station area. Therefore, we suggest a typology of station areas based on the three components, which might be used as a planning tool for the development of the station areas into balanced transit-oriented development areas.
Road network connectivity determines the accessibility of urban activities for pedestrians, while streetscape characteristics have an impact on route attractiveness. Methods used to measure the ...influence of connectivity and streetscape characteristics on walking behavior differ substantially, while trip purpose is a key factor. This paper explores the respective contributions of network connectivity and streetscape features to explain leisure walking and utilitarian trips on 740 street segments in Santarém (Portugal). The indicators cover the most commonly used factors in walkability indexes, such as density, diversity, design, and accessibility. The streetscape features measure imageability, enclosure, human scale, transparency, and complexity. The walking trip information was collected via survey. The results show that connectivity measures have a greater overall explanatory power for both trip motives. However, the findings highlight the need to consider a variety of design indicators to explain walking behavior due to the higher explanation power of the model with two types of indicators.
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