Alternative Transport Routes Research Articles

A systems-level methodology for the analysis of inland waterway infrastructure disruptions

Inland waterways are vital to the Nation’s economic strength, and to the health and welfare of the American people. This paper describes an end-to-end systems analysis methodology for inland waterways that incorporates infrastructure interdependencies and cascading impacts due to loss of a key asset. The methodology leverages available Federal, State, and private-sector data, methods, tools, expertise, and existing studies to minimize duplication and ensure broad acceptance and applicability. The approach determined potential adverse scenarios and impacts upon directly affected assets (e.g., downtime of a lock, dam, or bridge), and identified industrial sites that would be affected by the loss of normal transport capability (e.g., loss of barge transport). Origin and destination information along an inland waterway was correlated with the port and dock locations of industrial sites. Practical alternative transportation modes and routes for each affected industrial site were identified, based on existing railheads and estimated alternative mode system surge capacity. Reasonable assumptions were developed and applied where specific data were unavailable, and consequences such as additional transportation costs, costs of transportation delays, jobs losses, and economic impacts on other sectors locally and regionally were determined for unique inland waterway facilities critical to the Illinois Waterway.

The Economic Value of Novel Means of Ascending High Mountain Peaks: A Travel Cost Demand Model of Pikes Peak Cog Railway Riders, Automobile Users and Hikers

In addition to hiking trails, some peaks have alternative transportation routes such as cog railways, trams or roads to reach the summit. The authors use a count data travel cost model to estimate the recreational demand for traditional and novel means of ascending Pikes Peak in Colorado. Their analysis shows statistically significant differences in the demand curve slopes and in the net willingness to pay (consumer surplus) for three categories of recreationists who take alternative means to ascend the mountain. The more exotic or unique the means of ascent, the higher the visitor benefits are. Cog railway and automobile users and those ascending by hiking receive consumer surpluses of US$98, US$54 and US$31, respectively, per day trip.

Simultaneous Optimization of Storage Allocation and Routing Problems for Belt-conveyor Transportation

Raw materials for industrial steel-making plants need to be stored in material yards in order to satisfy various production requirements. The stored materials are supplied to production plants by belt-conveyors with multiple alternative transportation routes. The simultaneous optimization of the storage allocation and transportation routing for the raw materials yard is required for achieving production that is flexible to changes in demand. In this paper, we propose a Lagrangian decomposition and coordination approach for storage allocation and routing for a belt-conveyor transportation system to handle demand changes. The overall problem is decomposed into an allocation planning subproblem and a transportation routing subproblem. A near-optimal solution for allocation planning and transportation routing is derived by repeating each optimization of subproblems and multiplier updates. The effectiveness of the proposed approach is confirmed in numerical experiments.

Modulating Effect of Far-Red Light on Activities of Alternative Electron Transport Pathways Related to Photosystem I

Barley (Hordeum vulgare L.) leaves were irradiated with far-red (FR) light of various intensities after different periods of dark adaptation in order to investigate activities of alternative electron transport pathways related to photosystem I (PSI). Photooxidation of P700, the primary electron donor of PSI, was saturated at FR light intensity of 0.15 µmol quanta/(m2 s). As the photon flux density was raised in this range, the slow and middle components in the kinetics of P700+ dark reduction increased, whereas the fast component remained indiscernible. The amplitudes of the slow and middle components diminished upon further increase of FR photon flux density in the range 0.15–0.35 µmol quanta/(m2 s) and remained constant at higher intensities. The fast component of P700+ reduction was only detected after FR irradiation with intensities above 0.15 µmol quanta/(m2 s); the light-response curve for this component was clearly sigmoid. In dark-adapted barley leaves, three stages were distinguished in the kinetics of P700 photooxidation, with the steady state for P700+ achieved within about 3 min. In leaves predarkened for a short time, the onset of FR irradiation produced a very rapid photooxidation of P700. As the duration of dark exposure was prolonged, the amplitude of the first peak in the kinetic curve of photoinduced P700 photooxidation was diminished and the time for attaining the steady-state oxidation level was shortened. After a brief dark adaptation of leaves, ferredoxin-dependent electron flow did not appreciably contributed to the kinetics of P700+ dark reduction, whereas the components related to electron donation from stromal reductants were strongly retarded. It is concluded that FR light irradiation, selectively exciting PSI, suffices to modulate activities of alternative electron transport routes; this modulation reflects the depletion of stromal reductants due to continuous efflux of electrons from PSI to oxygen under the action of FR light.

Evidence for the operation of alternative electron transport routes through photosystem I in intact barley leaves under weak and moderate white light

The functioning of alternative routes of photosynthetic electron transport was analyzed from the kinetics of dark reduction of P700+ , an oxidized primary donor of PSI, in barley (Hordeum vulgare L.) leaves irradiated by white light of various intensities. Redox changes of P700 were monitored as absorbance changes at 830 nm using PAM 101 specialized device. Irradiation of dark-adapted leaves caused a gradual P700+ accumulation, and the steady-state level of oxidized P700 increased with intensity of actinic light. The kinetics of P700+ dark reduction after a pulse of strong actinic light, assayed from the absorbance changes at 830 nm, was fitted by a single exponential term with a halftime of 10–12 ms. Two slower components were observed in the kinetics of P700+ dark reduction after leaf irradiation by attenuated actinic light. The contribution of slow components to P700+ reduction increased with the decrease in actinic light intensity. Two slow components characterized by halftimes similar to those observed after leaf irradiation by weak white light were found in the kinetics of dark reduction of P700+ oxidized in leaves with far-red light specifically absorbed by PSI. The treatment of leaves with methyl viologen, an artificial PSI electron acceptor, significantly accelerated the accumulation of P700+ under light. At the same time, the presence of methyl viologen, which inhibits ferredoxin-dependent electron transport around PSI, did not affect three components of the kinetics of P700+ dark reduction obtained after irradiations with various actinic light intensities. It was concluded that some part of PSI reaction centers was not reduced by electron transfer from PSII under weak or moderate intensities of actinic light. In this population of PSI centers, P700+ was reduced via alternative electron transport routes. Insensitivity of the kinetics of P700+ dark reduction to methyl viologen evidences that the input of electrons to PSI from the reductants (NADPH or NADH) localized in the chloroplast stroma was effective under those light conditions.

Recovery of photosystem I and II activities during re-hydration of lichen Hypogymnia physodes thalli.

Photochemical efficiencies of photosystem I (PSI) and photosystem II (PSII) were studied in dry thalli of the lichen Hypogymnia physodes and during their re-hydration. In dry thalli, PSII reaction centers are photochemically inactive, as evidenced by the absence of variable chlorophyll (Chl) fluorescence, whereas the primary electron donor of PSI, P700, exhibits irreversible oxidation under continuous light. Upon application of multiple- and, particularly, single-turnover pulses in dry lichen, P700 oxidation partially reversed, which indicated recombination between P700(+) and the reduced acceptor F(X) of PSI. Re-wetting of air-dried H. physodes initiated the gradual restoration of reversible light-induced redox reactions in both PSII and PSI, but the recovery was faster in PSI. Two slow components of P700(+) reduction occurred after irradiation of partially and completely hydrated thalli with strong white light. In contrast, no slow component was found in the kinetics of re-oxidation of Q(A)(-), the reduced primary acceptor of PSII, after exposure of such thalli to white light. This finding indicated the inability of PSII in H. physodes to provide the reduction of the plastoquinone pool to significant levels. It is concluded that slow alternative electron transport routes may contribute to the energetics of photosynthesis to a larger extent in H. physodes than in higher plants.

Deletion of the tobacco plastid psbA gene triggers an upregulation of the thylakoid-associated NAD(P)H dehydrogenase complex and the plastid terminal oxidase (PTOX).

We have constructed a tobacco psbA gene deletion mutant that is devoid of photosystem II (PSII) complex. Analysis of thylakoid membranes revealed comparable amounts, on a chlorophyll basis, of photosystem I (PSI), the cytochrome b6f complex and the PSII light-harvesting complex (LHCII) antenna proteins in wild-type (WT) and DeltapsbA leaves. Lack of PSII in the mutant, however, resulted in over 10-fold higher relative amounts of the thylakoid-associated plastid terminal oxidase (PTOX) and the NAD(P)H dehydrogenase (NDH) complex. Increased amounts of Ndh polypeptides were accompanied with a more than fourfold enhancement of NDH activity in the mutant thylakoids, as revealed by in-gel NADH dehydrogenase measurements. NADH also had a specific stimulating effect on P700+ re-reduction in the DeltapsbA thylakoids. Altogether, our results suggest that enhancement of electron flow via the NDH complex and possibly other alternative electron transport routes partly compensates for the loss of PSII function in the DeltapsbA mutant. As mRNA levels were comparable in WT and DeltapsbA plants, upregulation of the alternative electron transport pathways (NDH complex and PTOX) occurs apparently by translational or post-translational mechanisms.

Heterogeneous Rieske Proteins in the Cytochrome b6f Complex of Synechocystis PCC6803?

The completely sequenced genome of the cyanobacterium Synechocystis PCC6803 contains three open reading frames, petC1, petC2, and petC3, encoding putative Rieske iron-sulfur proteins. After heterologous overexpression, all three gene products have been characterized and shown to be Rieske proteins as typified by sequence analysis and EPR spectroscopy. Two of the overproduced proteins contained already incorporated iron-sulfur clusters, whereas the third one formed unstable aggregates, in which the FeS cluster had to be reconstituted after refolding of the denatured protein. Although EPR spectroscopy showed typical FeS signals for all Rieske proteins, an unusual low midpoint potential was revealed for PetC3 by EPR redox titration. Detailed characterization of Synechocystis membranes indicated that all three Rieske proteins are expressed under physiological conditions. Both for PetC1 and PetC3 the association with the thylakoid membrane was shown, and both could be identified, although in different amounts, in the isolated cytochrome b(6)f complex. The considerably lower redox potential determined for PetC3 indicates heterogeneous cytochrome b(6)f complexes in Synechocystis and suggests still to be established alternative electron transport routes.

Yol082p, a Novel CVT Protein Involved in the Selective Targeting of Aminopeptidase I to the Yeast Vacuole

The yeast vacuolar enzyme aminopeptidase I (API) is synthesized in the cytoplasm as a precursor (pAPI). Upon its assembly into dodecamers, pAPI is wrapped by double-membrane saccular structures for its further transport within vesicles that fuse with the vacuolar membrane and release their content in the vacuolar lumen. Targeting of API to the vacuole occurs by two alternative transport routes, the cvt and the autophagy pathways, which although mechanistically similar specifically operate under vegetative growth or nitrogen starvation conditions, respectively. We have studied the role of Yol082p, a protein identified by its ability to interact with API, in the transport of its precursor to the vacuole. We show that Yol082p interacts with mature API, an interaction that is strengthened by the amino extension of the API protein. Yol082p is required for targeting of pAPI to the vacuole, both under growing and short term nitrogen starvation conditions. Absence of Yol082p does not impede the assembly of pAPI into dodecamers, but precludes the enclosure of pAPI within transport vesicles. Microscopy studies show that during vegetative growth Yol082p is distributed between a cytoplasmic pool and a variable number of 0.13--0.27-microm round, mobile structures, which are no longer observed under conditions of nitrogen starvation, and become larger in cells expressing the inactive Yol082 Delta C32p, or lacking Apg12p. In contrast to the autophagy mutants involved in API transport, a Delta yol082 strain does not lose viability under nitrogen starvation conditions, indicating normal function of the autophagy pathway. The data are consistent with a role of Yol082p in an early step of the API transport, after its assembly into dodecamers. Because Yol082p fulfills the functional requisites that define the CVT proteins, we propose to name it Cvt19.

Strategic Management Decision Support System: An Analysis of the Environmental Policy Issues

In this paper we present a new approach for modeling environmental problem as a bilevel programming problem. To the authors best knowledge, this is the first attempt to use bilivel techniques to tackle such problems. We derive at solution to help decision makers to cope with environmental policy issues. San Francisco, Bay Area is used as a real world example with the solution to their environmental problem. California is presently faced with a serious deficit of solid waste treatment and disposal facilities. Federal legislation has sought to compel the States to assure the capacity to treat and dispose of their own wastes and the California Legislature has enacted laws requiring the counties to initiate programs so that they can treat and dispose of their own wastes. Neither the federal nor the State programs have met with success in California. California continues to ship greater and greater amounts of waste out-of-state, and the majority of California counties have not instituted plans acceptable to the State government regarding the treatment and disposal of their own wastes. In the few cases where sitting and licensing programs have been proposed, the policy-makers charged with their evaluation have proceeded with largely intuitive, non-quantitative evaluation of policy options, often ignoring most of the financial and environmental implication of their decisions. We have developed a strategic management decision model that can evaluate multiple solid waste management options from both economic and environmental standpoints. Examples of problems a quantitative model might evaluate include the economic and environmental impacts of multiple treatment or disposal facilities as opposed to only one site; the environmental impact of taxing “dirty” waste streams, thus encouraging waste treatment and/or minimization on-site; and the social risk resulting from transportation risks assuming one or more multiple treatment or disposal sites or the use of alternative transportation routes. Because of extensive information presently available for the San Francisco Bay region, we have investigated the regional waste management problem there under several different treatment and disposal scenarios. As appropriate, results from this regional model and from authors earlier work [1] will be applied to California as a whole.

Transport Issues in Post-Soviet Central Asia

After the collapse of the Soviet Union the Central Asianproducers have been actively and partly successfully looking forcompensating markets. Howeve1; the transport infrastructurewas built to se1ve interests of the Soviet state. New transportCOJTidors to the west, east and south are being constructed orplanned reducing in the long run the transport costs of CentralAsian products, which still today pw1ly use traditional and longerSoviet time outlets (pipelines, railways, ports). For both economicand geopolitical reasons Central Asian states wish tofind alternative transport routes. The EU and geopolitical rivalsof Russia, the USA and China, are helping in this, also Iran hasvested interests in the issue. Still long haulage remain a constantproblem for landlocked Central Asia and the high cost ofmany projects planned (Transcaspian or Chinese pipelines) islikely to postpone them to a distant future.

An alternative non-cytochrome containing branch in the respiratory system of free-living Rhizobium phaseoli

The existence of a NADH oxidase catalyzed by a non-cytochrome containing pathway in membranes of free-living Rhizobium phaseoli was explored. This alternative electron transport route was distinguished from the cytochrome-oxidase linked pathway by its low affinity towards O2 (K\(\left( {K_{m_{app} } = 75 - 80{\text{ }}\mu M} \right)\), higher Km for NADH (75 μM), a hundred-fold lower sensitivity to quinarine inhibition, and resistance to UV (360 nm) photoinactivation. In addition to NADH, tetramethyl-p-phenylenediamine (TMPD) donates electrons to this low-O2 affinity pathway, causing reduction bleaching of a flavoprotein absorption band at 455 nm. Ascorbate-TMPD dependent respiration was partially (25%) inhibited by 200 μM quinacrine. The low O2-affinity oxidase activity promoted by NADH, or ascorbate plus TMPD was present in aerobic and microaerophilic grown cells and absent in anaerobic and bacteroid cells. Thus, a NADH linked flavoprotein type oxidase is suggested.