The inaccuracy of traffic forecasts has long stood as a central research theme in the field of infrastructure and transportation studies. The literature presents several motives for this phenomenon, ...ranging from a political bias, insufficient technical preparation, changing urban patterns, and economic dynamics. Uncertainty due to the inaccuracy of forecasts can have a profound impact on the infrastructure development process, right through from the preliminary studies up until the operation and re-negotiation of contracts (in cases when projects are developed using a concessions model). This paper provides an extensive systematic review of forecast inaccuracy in roads and railways projects (analyzing trends, causes, and results). The research found that: (1) forecasts in rail projects are generally more optimistic than in road projects; (2) over the last couple of decades the accuracy of forecasts has not improved significantly, and; (3) there has been a generalized ramp-up effect in forecasts.
An agent-based simulation framework is extended to design efficient large-scale public transport networks. It goes beyond existing approaches by incorporating a dynamic demand response towards both ...changes in the network and exogenous factors. The framework is based on an agent-based (MATSim) simulation and tested for the city of Zurich. In contrast to most existing public transport network optimization approaches, this framework is part of a city-level, multi-modal transport simulation tool. Compared to the existing public transport system, it proposes a sparser network with smaller vehicles and substantially higher frequencies. By doing so, the approach predicts a higher transit ridership at a lower level of subsidies. Moreover, it reliably identifies corridors for potential capacity upgrades. The method may help transport planners to assess their existing public transport networks and to plan public transport infrastructure for the era of automated vehicles.
Compared to lower‐gradient channels, steep mountain streams typically have rougher beds and shallower flow depths, making macro‐scale flow resistance (due to, e.g., immobile boulders and irregular ...bedforms) more important as controls on sediment transport. The marked differences in hydraulics, flow resistance, and grain mobility between steep and lower‐gradient streams raise the question of whether the same equations can predict bed load transport rates across wide ranges of channel gradients. We studied a steep, glacier‐fed mountain stream (Riedbach, Ct. Valais, Switzerland) that provides a natural experiment for exploring how stream gradients affect bed load transport rates. The streambed gradient increases over a 1 km stream reach by roughly one order of magnitude (from 3% to 38%), while flow discharge and width remain approximately constant. Sediment transport rates were determined in the 3% reach using Bunte bed load traps and in the 38% reach using the Swiss plate geophone system. Despite a ten‐fold increase in bed gradient, bed load transport rates did not increase substantially. Observed transport rates for these two very different bed gradients could be predicted reasonably well by using a flow resistance partitioning approach to account for increasing bed roughness (D84 changes from 0.17 m to 0.91 m) within a fractional bed load transport equation. This suggests that sediment transport behavior across this large range of steep slopes agrees with patterns established in previous studies for both lower‐gradient and steep reaches, and confirms the applicability of the flow resistance and bed load transport equations at very steep slopes.
Key Points
Fluvial bed load transport measured at bed gradients from 3% up to 38%
Bed load transport approximately constant with increasing bed gradient
Bed load transport equations for flat streams also apply in steep channels
A partner protein, NAR2, is essential for high‐affinity nitrate transport of the NRT2 protein in plants. However, the NAR2 motifs that interact with NRT2s for their plasma membrane (PM) localization ...and nitrate transporter activity have not been functionally characterized. In this study, OsNAR2.1 mutations with different carbon (C)‐terminal deletions and nine different point mutations in the conserved regions of NAR2 homologs in plants were generated to explore the essential motifs involved in the interaction with OsNRT2.3a. Screening using the membrane yeast two‐hybrid system and Xenopus oocytes for nitrogen‐15 (¹⁵N) uptake demonstrated that either R100G or D109N point mutations impaired the OsNAR2.1 interaction with OsNRT2.3a. Western blotting and visualization using green fluorescent protein fused to either the N‐ or C‐terminus of OsNAR2.1 indicated that OsNAR2.1 is expressed in both the PM and cytoplasm. The split‐yellow fluorescent protein (YFP)/BiFC analyses indicated that OsNRT2.3a was targeted to the PM in the presence of OsNAR2.1, while either R100G or D109N mutation resulted in the loss of OsNRT2.3a‐YFP signal in the PM. Based on these results, arginine 100 and aspartic acid 109 of the OsNAR2.1 protein are key amino acids in the interaction with OsNRT2.3a, and their interaction occurs in the PM but not cytoplasm.
Ready for takeoff? Schlumberger, Charles E; Weisskopf, Nora
2014., 2014, 10-2-2014, 2014-09-10
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The emergence of low-cost carriers (LCCs) has been a key catalyst for the development of the aviation industry in the last decade. Indeed, extensive research has been undertaken to analyze the ...business model and impact on the aviation sector and beyond. Despite recent developments in the LCC markets in Asia and Latin America, much of the research has been focused on developed countries. Therefore, the purpose of this book is to identify the premises and prerequisites of the LCC model, and assess whether this business model could be successful in other less-developed countries, in particular the countries of Sub-Saharan Africa. This book identifies various definitions that have been applied to describe the LCC business model. In essence the majority of researchers define LCCs as carriers which, through a variety of operational processes, have achieved a cost advantage over full-service carriers (FSCs). This cost advantage is, in most cases, translated to the consumers by a lower fare offering. Although many carriers are defined as LCCs, the LCC model has developed into many different variations since the original Southwest Airlines model, the first U.S. LCC, which began operations in the 1960s.
Cases of congenital disorders of glycosylation (CDG) have been associated with specific mutations within the gene encoding the human Golgi TMEM165 (transmembrane protein 165), belonging to UPF0016 ...(uncharacterized protein family 0016), a family of secondary ion transporters. To date, members of this family have been reported to be involved in calcium, manganese, and pH homeostases. Although it has been suggested that TMEM165 has cation transport activity, direct evidence for its Ca2+- and Mn2+-transporting activities is still lacking. Here, we functionally characterized human TMEM165 by heterologously expressing it in budding yeast (Saccharomyces cerevisiae) and in the bacterium Lactococcus lactis. Protein production in these two microbial hosts was enhanced by codon optimization and truncation of the putatively autoregulatory N terminus of TMEM165. We show that TMEM165 expression in a yeast strain devoid of Golgi Ca2+ and Mn2+ transporters abrogates Ca2+- and Mn2+-induced growth defects, excessive Mn2+ accumulation in the cell, and glycosylation defects. Using bacterial cells loaded with the fluorescent Fura-2 probe, we further obtained direct biochemical evidence that TMEM165 mediates Ca2+ and Mn2+ influxes. We also used the yeast and bacterial systems to evaluate the impact of four disease-causing missense mutations identified in individuals with TMEM165-associated CDG. We found that a mutation leading to a E108G substitution within the conserved UPF0016 family motif significantly reduces TMEM165 activity. These results indicate that TMEM165 can transport Ca2+ and Mn2+, which are both required for proper protein glycosylation in cells. Our work also provides tools to better understand the pathogenicity of CDG-associated TMEM165 mutations.
A growing concern for mobility-related social inclusion and equity is evident from both academic research and planning best practices. Scholarly research promotes accessibility as the main aim of ...transport planning, assuming it as the evaluative approach that better conveys how mobility contributes to individuals' well-being and participation in social life. Accessibility can be crucial to address the socio-spatial inequalities that characterise manifold settings across the world. Amongst them, Latin American countries have been keen in tackling such imbalances through mobility-related interventions, as the renowned cases of Curitiba, Medellin and Bogotá show. The widespread interest in mobility as both a cause and effect of social disparities has generated an increasing stream of work that examines Latin American settings through the lenses of accessibility. This paper aims at critically reviewing the growing scholarly works that, providing accessibility-based evaluations, has examined issues of transport and equity in Latin America. Proposing a novel conceptual framework that considers the underlying ethical stance, components of accessibility and implications for planning and policy, this work examines what approaches, features and indicators are present in the current literature, as well as what settings have been taken into consideration by scholarly research. Moreover, the review has an explicit operational interest, to define what indicators are relevant or missing to assess accessibility in the light of social concerns, as well as to consider the current and potential implications that such research findings have on transport planning and policy. The review highlights how a growing but still limited body of work has examined transport and equity in Latin America, suggesting academic, technical and operational avenues to enhance theoretical and practical approaches to the issue.
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BFBNIB, DOBA, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
Thermoelectrics, which can generate electricity from a temperature difference, or vice versa, is a key technology for solid‐state cooling and energy harvesting; however, its applications are ...constrained owing to low efficiency. Since the conversion efficiency of thermoelectric devices is directly obtained via a figure of merit of materials, zT, which is related to the electronic and thermal transport characteristics, the aim here is to elucidate physical parameters that should be considered to understand transport phenomena in semiconducting materials. It is found that the weighted mobility ratio of the majority and minority carrier bands is an important parameter that determines zT. For nanograined Bi–Sb–Te alloy, the unremarked role of this parameter on temperature‐dependent electronic transport properties is demonstrated. This analysis shows that the control of the weighted mobility ratio is a promising way to enhance zT of narrow bandgap thermoelectric materials.
Suppression of the bipolar conduction in narrow‐bandgap thermoelectric materials is crucial for improving their device efficiency. This work correlates the weighted mobility ratio in thermoelectric figure of merit and bipolar conduction in bismuth‐telluride‐based alloys. The results suggest that increasing the weighted mobility ratio suppresses the bipolar conduction most effectively among other parameters like carrier concentration and bandgap.
•Paraquat uptake into Caco-2 cells is partially mediated by the y+ transport system.•PQ uptake is regulated by a Ca++/calmodulin complex-dependent mechanism.•The carrier-mediated transport system for ...choline is involved on PQ uptake.•Several transport systems contribute to the intestinal uptake of paraquat.•Specific and potent inhibitors of these transporters may be potential new antidotes.
Paraquat (PQ) is an extremely toxic herbicide upon oral ingestion that lacks a specific antidote. In case of intoxication, treatment primarily relies on limiting its intestinal absorption. In this study, we elucidate the intestinal transport mechanisms of PQ uptake using Caco-2 cells as a model of the human intestinal epithelium. The cells were incubated with a wide range of PQ concentrations (0–5000μM) for 24h with or without simultaneous exposure to different transporters substrates/inhibitors including, choline or hemicolinium-3 (for choline carrier-mediated transport system inhibition) and putrescine, trifluoperazine, valine, lysine, arginine or N-ethylmaleimide (for basic amino acid transport systems inhibition). PQ cytotoxicity was evaluated by the MTT reduction assay and correlated with PQ intracellular levels quantified by gas chromatography-ion trap-mass spectrometry (GC–IT/MS). Potential interactions of PQ with the substrates/inhibitors of the transport systems were investigated and discarded by infrared spectroscopy.
Our results showed a significant reduction in PQ intracellular accumulation and, consequently, in PQ cytotoxicity, in the presence of both choline and hemicolinium-3, demonstrating that the choline carrier-mediated transport system is partially involved in PQ intestinal uptake. Likewise, PQ cytotoxicity and intracellular accumulation were significantly attenuated by simultaneous exposure to putrescine, trifluoperazine, valine, lysine, arginine and N-ethylmaleimide. These data suggested the involvement of more than one of the basic amino acids transport systems, including the y+, b0,+ or y+L systems.
In conclusion, this study demonstrated that several transport systems mediate PQ intestinal absorption and, therefore, their modulation may provide alternative efficient pathways for limiting PQ toxicity in intoxication scenarios.
SLC35A4 has been classified in the SLC35A subfamily based on amino acid sequence homology. Most of the proteins belonging to the SLC35 family act as transporters of nucleotide sugars. In this study, ...the subcellular localization of endogenous SLC35A4 was determined via immunofluorescence staining, and it was demonstrated that SLC35A4 localizes mainly to the Golgi apparatus. In silico topology prediction suggests that SLC35A4 has an uneven number of transmembrane domains and its N-terminus is directed towards the Golgi lumen. However, an experimental assay refuted this prediction: SLC35A4 has an even number of transmembrane regions with both termini facing the cytosol. In vivo interaction analysis using the FLIM–FRET approach revealed that SLC35A4 neither forms homomers nor associates with other members of the SLC35A subfamily except SLC35A5. Additional assays demonstrated that endogenous SLC35A4 is 10 to 40nm proximal to SLC35A2 and SLC35A3. To determine SLC35A4 function SLC35A4 knock-out cells were generated with the CRISPR-Cas9 approach. Although no significant changes in glycosylation were observed, the introduced mutation influenced the subcellular distribution of the SLC35A2/SLC35A3 complexes. Additional FLIM–FRET experiments revealed that overexpression of SLC35A4-BFP together with SLC35A3 and the SLC35A2-Golgi splice variant negatively affects the interaction between the two latter proteins. The results presented here strongly indicate a modulatory role for SLC35A4 in intracellular trafficking of SLC35A2/SLC35A3 complexes.
•Endogenous SLC35A4 localizes mainly to the Golgi apparatus.•Both N- and C-termini of SLC35A4 are directed towards the cytosol.•SLC35A4 directly associates with SLC35A5.•SLC35A4 knock-out triggers relocalization of SLC35A2/SLC35A3 complex.•SLC35A2-deficient cells are unable to co-express SLC35A3 and SLC35A4.
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