941 resultados para Urban public transport system


Relevância:

100.00% 100.00%

Publicador:

Resumo:

This paper applies an integrated modeling approach to the case of Spain; the approach is based on a random utility-based multiregional input-output model and a road transport network model for assessing the effect of introducing longer and heavier vehicles (LHVs) on the regional consumer price index (CPI) and on the transportation system. The approach strongly supports the concept that changes in transport costs derived from the LHV allowance as well as the economic structure of regions have direct and indirect effects on the economy and on the transportation system. Results show that the introduction of LHVs might reduce prices paid by consumers for a representative basket of goods and services in the regions of Spain and would also lead to a reduction in the regional CPI. In addition, the magnitude and extent of changes in the transportation system are estimated by using the commodity-based structure of the approach to identify the effect of traffic changes on traffic flows and on pollutant emissions over the whole network.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Growth of a glutamate transport-deficient mutant of Rhodobacter sphaeroides on glutamate as sole carbon and nitrogen source can be restored by the addition of millimolar amounts of Na+. Uptake of glutamate (Kt of 0.2 μM) by the mutant strictly requires Na+ (Km of 25 mM) and is inhibited by ionophores that collapse the proton motive force (pmf). The activity is osmotic-shock-sensitive and can be restored in spheroplasts by the addition of osmotic shock fluid. Transport of glutamate is also observed in membrane vesicles when Na+, a proton motive force, and purified glutamate binding protein are present. Both transport and binding is highly specific for glutamate. The Na+-dependent glutamate transporter of Rb. sphaeroides is an example of a secondary transport system that requires a periplasmic binding protein and may define a new family of bacterial transport proteins.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Membrane preparations enriched in plasma membrane vesicles prepared from promastigotes of Leishmania tarentolae were shown to accumulate thiolate derivatives of 73As(III). Free arsenite was transported at a low rate, but rapid accumulation was observed after reaction with reduced glutathione (GSH) conditions that favor the formation of As(GS)3. Accumulation required ATP but not electrochemical energy, indicating that As(GS)3 is transported by an ATP-coupled pump. Pentostam, a Sb(V)-containing drug that is one of the first-line therapeutic agents for treatment of leishmaniasis, inhibited uptake after reaction with GSH. Vesicles prepared from a strain in which both copies of the pgpA genes were disrupted accumulated As(GS)3 at wild-type levels, demonstrating that the PgpA protein is not the As(GS)3 pump. These results have important implications for the mechanism of drug resistance in the trypanosomatidae, suggesting that a plasma membrane As(GS)3 pump catalyzes active extrusion of metal thiolates, including the Pentostam-glutathione conjugate.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

We have developed a system for the isolation of Neurospora crassa mutants that shows altered responses to blue light. To this end we have used the light-regulated promoter of the albino-3 gene fused to the neutral amino acid permease gene mtr. The product of the mtr gene is required for the uptake of neutral aliphatic and aromatic amino acids, as well as toxic analogs such as p-flurophenylalanine or 4-methyltryptophan. mtr trp-2-carrying cells were transformed with the al-3 promoter-mtr wild-type gene (al-3p-mtr+) to obtain a strain with a light-regulated tryptophan uptake. This strain is sensitive to p-fluorophenylalanine when grown under illumination and resistant when grown in the dark. UV mutagenesis of the al-3p-mtr(+)-carrying strain allowed us to isolate two mutant strains, BLR-1 and BLR-2 (blue light regulator), that are light-resistant to p-fluorophenylalanine and have lost the ability to grow on tryptophan. These two strains have a pale-orange phenotype and show down-regulation of all the photoregulated genes tested (al-3, al-1, con-8, and con-10). Mutations in the BLR strains are not allelic with white collar 1 or white collar 2, regulatory genes that are also involved in the response to blue light.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

The interaction between globally available information and public library users is a changing one. Global information is readily available yet provider and user struggle to find efficiencies of time and resources. As a primary resource of global information the Denver Public Library (DPL) is approaching this challenge by providing changing technology to a changing user and by providing a customized approach to immigrant populations. DPL provides global information to library users through collections, programs and Internet. Internet and collections global information usage cannot be directly measured due to privacy restrictions. Only 12.5% of general user programs focus on global information. Four percent of budget serves the immigrant users. This is greater than national averages.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

At head of title: University of Illinois.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

At head of title: Department of the interior. General land office.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mode of access: Internet.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Description based on: 1988-89; title from caption.

Relevância:

100.00% 100.00%

Publicador:

Resumo:

Mode of access: Internet.