Measurement of uncertainty costs with dynamic traffic simulations

Non-recurrent congestion in transportation networks occurs as a consequence of stochastic factors affecting demand and supply. Intelligent Transportation Systems such as Advanced Traveler Information Systems (ATIS) and Advanced Traffic Management Systems (ATMS) are designed in order to reduce the impacts of non-recurrent congestion by providing information to a fraction of users or by controlling the variability of traffic flows. For these reasons, the design of ATIS and ATMS requires reliable forecast of non-recurrent congestion. This paper proposes a new method to measure the impacts of non-recurrent congestion on travel costs by taking risk aversion into account. The traffic model is based on the dynamic traffic simulations model METROPOLIS. Incidents are generated randomly by reducing the capacity of the network. Users can instantaneously adapt to the unexpected travel conditions or can also change their behavior via a day-to-day adjustment process. Comparisons with incident-free simulations provide a benchmark for potential travel time savings that can be brought in by a state-of-the-art information system. We measure the impact of variable travel conditions by describing the willingness to pay to avoid risky or unreliable journeys. Indeed, for risk averse drivers, any uncertainty corresponds to a utility loss. This utility loss is computed for several levels of network disruption. The main results of the paper is that the utility loss due to uncertainty is of the same order of magnitude as the total travel costs.

Trip chaining - who wins, who loses?.

In this paper we study how trip chaining affects the pricing and equilibrium number of firms. We use a monopolistic competition model where firms offer differentiated products as well as differentiated jobs to households who are all located at some distance from the firms. Trip chaining means that shopping and commuting can be combined in one trip. The symmetric equilibriums with and without the option of trip chaining are compared. We show analytically that introducing the trip chaining option can, in the short run, only decrease the profit margin of the firms and will increase welfare. The welfare gains are however smaller than the transport cost savings. In the long run, with free entry, the number of firms decreases but welfare with trip chaining possible is still higher than when it is excluded. A numerical illustration gives orders of magnitude of the different effects.Trip chaining; Discrete choice model; General equilibrium model; Imperfect competition; Wage competition;

Asymmetric duopoly - what policies work?.

In this paper we study the problem of a city with access to two subcentres selling a differentiated product. The first subcentre has low free flow transport costs but is easily congested (near city centre, access by road). The second one has higher free flow transport costs but is less prone to congestion (ample public transport capacity, parking etc.). Both subcentres need to attract customers and employees by offering prices and wages that are sufficiently attractive to cover their fixed costs. In the absence of any government regulation, there will be an asymmetric duopoly game that can be solved for a Nash equilibrium in prices and wages offered by the two subcentres. This solution is typically characterised by excessive congestion for the nearby subcentre. We study the welfare effects of a number of stylised policies by setting up a general model and illustrating the model using competition between airports as an example. The first stylised policy is to extend the congested road to subcentre 1. This policy will not necessarily lead to less congestion as more customers will be attracted by the lower transport costs. The second policy option is to add congestion pricing (or parking pricing (etc.) for the congested subcentre. This will decrease its profit margin and attract more customers. The third policy is acceptable for politicians: providing a direct subsidy to the remote subcentre, reducing its marginal costs. This policy will again ease the congestion problem for the nearby subcentre but will do this in a very costly way.Duopoly; Policy; Work;

Asymmetric duopoly in space - what policies work?.

Duopoly; Policy; Space; Work; Working;

Integrating a finantial module in the Web-Ecoyield-SAFE model for bioeconomic assessment of agroforestry systems

N/

Normal form decomposition for Gaussian-to-Gaussian superoperators

In this paper we explore the set of linear maps sending the set of quantum Gaussian states into itself. These maps are in general not positive, a feature which can be exploited as a test to check whether a given quantum state belongs to the convex hull of Gaussian states (if one of the considered maps sends it into a non positive operator, the above state is certified not to belong to the set). Generalizing a result known to be valid under the assumption of complete positivity, we provide a characterization of these Gaussian-to-Gaussian (not necessarily positive) superoperators in terms of their action on the characteristic function of the inputs. For the special case of one-mode mappings we also show that any Gaussian-to-Gaussian superoperator can be expressed as a concatenation of a phase-space dilatation, followed by the action of a completely positive Gaussian channel, possibly composed with a transposition. While a similar decomposition is shown to fail in the multi-mode scenario, we prove that it still holds at least under the further hypothesis of homogeneous action on the covariance matrix

Experimental candidiasis in mice: evaluation of the histopathology and the effect of cysteine on the virulence of candida albicans

Thesis (M.A.)--Boston University.Normal strains of Candida albicans reproduce by budding when conditions are favorable for growth. In animal tissues a rapid morphological chance takes place budding cells fail to detach and pseudouyphae develop. The addition of cysteine to the normal growth medium of a genetically blocked, filamentous strain of Candida albicans results in a suppresion of the filamentous phase and an increased number of budding yeast forms. Filamentous variants of Candida albicans have not demonstrated appreciable virulence in experimental infections, but tLere is evidence that induced yeast growth under the influence of cysteine accompanies an increase in virulence

Influence of electromagnetic interferences on the gravimetric sensitivity of surface acoustic waveguides

Surface acoustic waveguides are increasing in interest for (bio)chemical detection. The surface mass modification leads to measurable changes in the propagation properties of the waveguide. Among a wide variety of waveguides, Love mode has been investigated because of its high gravimetric sensitivity. The acoustic signal launched and detected in the waveguide by electrical transducers is accompanied by an electromagnetic wave; the interaction of the two signals, easily enhanced by the open structure of the sensor, creates interference patterns in the transfer function of the sensor. The influence of these interferences on the gravimetric sensitivity is presented, whereby the structure of the entire sensor is modelled. We show that electromagnetic interferences generate an error in the experimental value of the sensitivity. This error is different for the open and the closed loop configurations of the sensor. The theoretical approach is completed by the experimentation of an actual Love mode sensor operated under liquid in open loop configuration. The experiment indicates that the interaction depends on the frequency and the mass modifications.Comment: 28 pages, 8 figure

Developments of the pinned photodiode terahertz rectifier

This paper presents we presents a development of the structure of the pinned photodiode terahertz rectifier, in which the metal whisker of the antenna is separated from the semiconductor by a silane oxide layer, in order to reduce the surface defectiveness. The rectifies is the basic component of an image detection system based on the structure of actual CMOS image detectors. The structure combines a nano-antenna, fabricated on the top of a standard image sensor, the rectifier, and the readout electronics. The rectifier device proposed has vertical extension of some tenths of nanometers, can be created at the foot of the nano-whisker at the end of the terahertz antenna, above the storage well