EVALUATING NON-PRICE WATER DEMAND POLICIES DURING SEVERE DROUGHTS

This research examines how differing frequencies of water use restrictions affected per-capita water demand in three medium-sized municipalities along the Front Range of Colorado during the 2002 drought. Preliminary results indicate that while one- or two-day per week watering restrictions limit per capita water use, voluntary restrictions may actually promote overuse of water as consumers prepare for more stringent restrictions.Resource /Energy Economics and Policy,

Evaluating Non-Price Water Demand Policies During Severe Droughts

Western states and provinces live under constant drought threat. When and how to time restrictions on outdoor watering are crucial management issues. The effectiveness of various policies is assessed using experience from Colorado during a severe drought.Environmental Economics and Policy,

A combined experimental-numerical study to tensile behaviour of limestone

In this paper, a combined experimental-computational study of double-edge notched stone specimen subject to cyclic tensile loading is presented. In the experimental part, the load-deformation response and the local displacement field are recorded. Both experimental results are used to validate a numerical model for the description of fracture within finite elements. The model uses displacement discontinuities to model cracks. These discontinuities are implemented using the partition of unity property of finite element shape functions. In the discontinuity, a combined damage-plasticity cohesive law is used. Numerical simulations are compared with experimental observations

A posteriori discontinuous Galerkin error estimates for transient convection–diffusion equations

AbstractA posteriori error estimates are derived for unsteady convection–diffusion equations discretized with the non-symmetric interior penalty and the local discontinuous Galerkin methods. First, an error representation formula in a user specified output functional is derived using duality techniques. Then, an Lt2(Lx2) a posteriori estimate consisting of elementwise residual-based error indicators is obtained by eliminating the dual solution. Numerical experiments are performed to assess the convergence rates of the various error indicators on a model problem

Assessment of atomic charge models for gas-phase computations on polypeptides

The concept of the atomic charge is extensively used to model the electrostatic properties of proteins. Atomic charges are not only the basis for the electrostatic energy term in biomolecular force fields but are also derived from quantum mechanical computations on protein fragments to get more insight into their electronic structure. Unfortunately there are many atomic charge schemes which lead to significantly different results, and it is not trivial to determine which scheme is most suitable for biomolecular studies. Therefore, we present an extensive methodological benchmark using a selection of atomic charge schemes [Mulliken, natural, restrained electrostatic potential, Hirshfeld-I, electronegativity equalization method (EEM), and split-charge equilibration (SQE)] applied to two sets of penta-alanine conformers. Our analysis clearly shows that Hirshfeld-I charges offer the best compromise between transferability (robustness with respect to conformational changes) and the ability to reproduce electrostatic properties of the penta-alanine. The benchmark also considers two charge equilibration models (EEM and SQE), which both clearly fail to describe the locally charged moieties in the zwitterionic form of penta-alanine. This issue is analyzed in detail because charge equilibration models are computationally much more attractive than the Hirshfeld-I scheme. Based on the latter analysis, a straightforward extension of the SQE model is proposed, SQE+Q0, that is suitable to describe biological systems bearing many locally charged functional groups

Impact des successions culturales (y compris intercultures) sur l'utilisation de produits phytosanitaires

Impact of crop sequences (including intercropping) on the use of pesticides. Crop sequences and the introduction of catch crops influence the development of agricultural pests (weeds, pests and diseases). This paper gives an overview of the problems that may arise for farmers in practice. Adaptation of crop interventions is often based on the use of plant protection products in the following crop, and these changes serve to solve problems that have been previously generated. Nevertheless, the poorly reasoned introduction of a catch crop can cause unwanted effects in terms of pest management and in relation to the protection of water resources

Regulation of the pleiotropic drug resistance transcription factors Pdr1 and Pdr3 in yeast

Aim: To understand how transcriptional factors Pdr1 and Pdr3, belonging to the pleiotropic drug resistance system, are activated, and regulated after introducing chemical toxins to the cell in the model organism Saccharomyces cerevisiae. Methods: Series of molecular methods were applied using different strains of S. cerevisiae over-expressing proteins of interest as a eukaryotic cell model. The chemical stress introduced to the cell is represented by menadione. Results were obtained performing protein detection and analysis. Additionally, the regulation of the DNA binding of the transcriptional activators after stimulation is quantified using chromatin immunoprecipitation, employing epitope-tagged factors and real-time qPCR. Results: Our results indicated higher expression levels of the Pdr1 transcriptional factor, compared to its homologous Pdr3 after treatment with menadione. The yeast-cell defence system was tested against various organic solvents to exclude the possibility of their presence potentially affecting the results. The results indicate that Pdr1 is most abundant after 30 minutes from the beginning of the treatment, compared with 240 minutes after the treatment when the function of the transcription factor is faded. It appears that Pdr1 binding to the PDR5 and SNQ2 promoters, which are both activated by Pdr1, peaks around the same time, or more precisely after 40 minutes from the start of the treatment. Conclusion: The tendency of Pdr1 reduction after its activation by menadione is detected. One possibility is that Pdr1, after recognizing the xenobiotic menadione, is removed by a degradation mechanism. Given the fact that Pdr1 directly binds the xenobiotic molecule, its destruction might help the cells to remove toxic levels of menadione. It is possible that overexpressing the part of Pdr1 which recognizes menadione alone was sufficient to detoxify and hence produce a tolerance towards menadione

Reactivity of three-membered heterocyclic rings with respect to sodium methoxide

Aziridines can be ‘activated’ or ‘non-activated’, depending on whether their N-substituent is an electron-withdrawing group or an electron-donating group, respectively. Activated aziridines are much more susceptible to ring opening than non-activated aziridines and epoxides are even more reactive. The difference in reactivity between activated 2-(bromomethyl)-1-tosylaziridines, non-activated 1-benzyl-2-(bromomethyl)aziridines and epibromohydrins with respect to sodium methoxide was comparatively analysed by means of DFT calculations, such as BMK, MPW1K and MPWB95 [1]. Nucleophilic substitution reactions are known to be influenced by the solvent environment. Therefore, the gas-phase results were extended towards a discrete solvent approach. The solvent effect was taken into account by inspecting the convergence behaviour of the energy of solvation in terms of a systematically increasing number of solvent molecules. To model each of the reactive profiles of the various substrates, a supermolecule model was used with five explicit methanol molecules. Solvation has significantly changed the landscape of the energy profiles, which nicely shows the necessity of taking into account explicit solvation molecules to obtain the correct reaction profiles. The barriers for direct displacement of bromide by methoxide in methanol are comparable for all three heterocyclic species under study. However, ring opening is only feasible for the epoxide and the activated aziridine and not for the non-activated aziridine