Bounded Arithmetic in Free Logic

One of the central open questions in bounded arithmetic is whether Buss' hierarchy of theories of bounded arithmetic collapses or not. In this paper, we reformulate Buss' theories using free logic and conjecture that such theories are easier to handle. To show this, we first prove that Buss' theories prove consistencies of induction-free fragments of our theories whose formulae have bounded complexity. Next, we prove that although our theories are based on an apparently weaker logic, we can interpret theories in Buss' hierarchy by our theories using a simple translation. Finally, we investigate finitistic G\"odel sentences in our systems in the hope of proving that a theory in a lower level of Buss' hierarchy cannot prove consistency of induction-free fragments of our theories whose formulae have higher complexity

Waste Management Behaviour of Households: A Case Study of a Strike in Saskatchewan

Environmental Economics and Policy,

Conserving Water in Irrigated Agriculture: The Economics and Valuation of Water Rights

The effective management of water resources in Alberta is crucial to sustainable agriculture, industrial development, and environmental management. The historical water allocation mechanism, administrative apportionment, has been viewed in recent years as ineffective and cumbersome. Accordingly, the revision of the Water Act in 1996, included an attempt to improve the efficiency of water allocation. By making the transfer of water rights possible, the revised Act provides many new options for water use and flexibility. The implications of transferable water rights in Alberta water policy must be carefully considered in order to determine the viability and suitability of such a system in the provincial context. This project examines some of the economic aspects of transferable water rights and the potential for effective water allocation by way of transfers in an Alberta setting. As a major part of this project, a hedonic price model, focusing on land values in southern Alberta, was constructed based on similar models, which have been used elsewhere to value water rights or agricultural products. The hedonic approach to market analysis uses the relationship between the price of land and the attributes of the land, such as water availability, soil quality and location, to explain differences in land prices. In this process, the hedonic model is used to estimate the implicit marginal price or value of each land attribute -- in our case, the marginal value of irrigation water. This value will provide us with an indirect estimate of the value of water rights in the region studied. An advantage of the technique is that it estimates the value that farmers express for irrigation water in the market place for land. Such values, then, give us an indication of the anticipated prices, which might prevail for water rights in southern Alberta. The focus of the study was an area of southern Alberta encompassing the counties of Wheatland, Newell, Cypress, Forty Mile, Taber, Warner, Lethbridge and Vulcan and the irrigation districts of Western, Eastern, St.Mary's, Taber, Lethbridge Northern, and portions of Raymond. Information was collected on the physical and economic characteristics of 230 land parcels, which were sold in this region in 1993 and early 1994. A crude comparison of the value of irrigated agricultural land and non-irrigated agricultural land in the sample reveals that irrigated land was worth, on average, $325 more per acre than non-irrigated land. In the ensuing analysis, it was estimated that the value of a parcel of land was determined largely by the buildings on it, the number of acres in the parcel, the proximity of the parcel to a major city (in this case Calgary or Lethbridge), and by the availability of irrigation water. In the hedonic model, the coefficient values of the variables included represent the marginal impact of each of these characteristics on land prices holding all other things constant. For example, the value of water rights represents the average difference between land values of farms that have access to irrigation and farms that do not. This study estimated that every dollar of improvements to farm buildings translates to a one cent increase in the per acre price of the land parcel, where the addition of one extra acre of land to a land parcel lowers the price per acre by$5.17 per acre. Land prices were seen to increase with the proximity of the parcel to large cities. Similarly, the results of the preferred model indicate that the implicit value of having access to irrigation water in southern Alberta is approximately $190 per acre, or, using the conventional estimate that irrigating one acre of land requires 1.5 acre feet of water, this translates to$126 per acre foot of irrigation water. Accordingly, it is revealed that the existence of water rights adds approximately 35% to the value of non-irrigated land. Since this value represents the implicit amount farmers are willing to pay for access to water, it could also be construed as an indirect measure of the value of water rights. From these results, it is reasonable to conclude that water rights do have a measurable impact on land values. Accordingly, proper incentives may be needed to ensure that water is used efficiently and not incorrectly treated as a relatively free or cheap good. One possible method of policy reform to achieve such a system would be the institution of a system of transferable water rights, permitting water to be traded, or effectively sold, at its market price or scarcity value. Further work was done to determine the potential effects of transferable water rights on the Eastern Irrigation District in southern Alberta. Farm budget information was used to gather information and create twelve representative farm types whose financial performance was analysed using linear programming with increasing water quantity constraints. The resulting productive water values were then used to imply potential reallocations of water among farm types and cropping systems. Analysis of the data gathered revealed that all representative farms faced downward sloping demand functions for water. The overall value of water for a 1% reduction ranged from $8 to$250 per acre foot, with the lowest value belonging to largely pasture operations and the highest value attributed to specialty crop producers. This large range in water values for the region indicates that there is sufficient heterogeneity within the EID to accommodate a transferable rights system. Further analysis of the data reveals that the implementation of a transfer system would result in water being transferred to specialty crop producers and the acreage devoted to specialty crops would increase. Small irrigated pasture operations and cereal crop producers would be the first to give up their water allocations under a transfer system. The analysis indicates that there is considerable potential for economic gains from water trade within this district, the main constraint being the market limitations to expanded specialty crop production. Using these two major studies and other sources, this report concludes with a brief evaluation of the economic advantages, disadvantages and other issues involved in instituting a system of transferable water rights in Alberta. Experience elsewhere, primarily in Australia and the western United States, strongly suggests that transferable water rights, despite some drawbacks and problems of implementation, can be a very worthwhile water policy tool. Now that such tradable water rights are permissible under the revised Water Resources Act of 1996, it is recommended that a pilot project involving transferable water rights be instituted in a water short basin or sub-basin in southern Alberta once a water management plan for that basin is completed.Resource /Energy Economics and Policy,

High-pressure Raman study of L-alanine crystal

Pressure-dependent Raman scattering studies in the range 0.0 -- 32 kbar were carried out in L-alanine in order to investigate its external mode phonon spectra in relation to the phase transitions in the crystal. A careful analysis of the spectra shows that the low-energy Raman modes exhibit variation both in frequency and in intensity and between 26 and 28 kbar it is observed a splitting of a external mode, indicating that the D_2 normal phase undergoes a transition. Pressure coefficients for external modes are also given.Comment: 11 pages, Latex, 2 figure

Riemann-Cartan Space-times of G\"odel Type

A class of Riemann-Cartan G\"odel-type space-times are examined in the light of the equivalence problem techniques. The conditions for local space-time homogeneity are derived, generalizing previous works on Riemannian G\"odel-type space-times. The equivalence of Riemann-Cartan G\"odel-type space-times of this class is studied. It is shown that they admit a five-dimensional group of affine-isometries and are characterized by three essential parameters $\ell, m^2, \omega$: identical triads ($\ell, m^2, \omega$) correspond to locally equivalent manifolds. The algebraic types of the irreducible parts of the curvature and torsion tensors are also presented.Comment: 24 pages, LaTeX fil

Quantum Monte Carlo calculations of the one-body density matrix and excitation energies of silicon

Quantum Monte Carlo (QMC) techniques are used to calculate the one-body density matrix and excitation energies for the valence electrons of bulk silicon. The one-body density matrix and energies are obtained from a Slater-Jastrow wave function with a determinant of local density approximation (LDA) orbitals. The QMC density matrix evaluated in a basis of LDA orbitals is strongly diagonally dominant. The natural orbitals obtained by diagonalizing the QMC density matrix resemble the LDA orbitals very closely. Replacing the determinant of LDA orbitals in the wave function by a determinant of natural orbitals makes no significant difference to the quality of the wave function's nodal surface, leaving the diffusion Monte Carlo energy unchanged. The Extended Koopmans' Theorem for correlated wave functions is used to calculate excitation energies for silicon, which are in reasonable agreement with the available experimental data. A diagonal approximation to the theorem, evaluated in the basis of LDA orbitals, works quite well for both the quasihole and quasielectron states. We have found that this approximation has an advantageous scaling with system size, allowing more efficient studies of larger systems.Comment: 13 pages, 4 figures. To appear in Phys. Rev.

Stimulation of sphingosine 1-phosphate signaling as an alveolar cell survival strategy in emphysema

RATIONALE: Vascular endothelial growth factor receptor (VEGFR) inhibition increases ceramides in lung structural cells of the alveolus, initiating apoptosis and alveolar destruction morphologically resembling emphysema. The effects of increased endogenous ceramides could be offset by sphingosine 1-phosphate (S1P), a prosurvival by-product of ceramide metabolism. OBJECTIVES: The aims of our work were to investigate the sphingosine-S1P-S1P receptor axis in the VEGFR inhibition model of emphysema and to determine whether stimulation of S1P signaling is sufficient to functionally antagonize alveolar space enlargement. METHODS: Concurrent to VEGFR blockade in mice, S1P signaling augmentation was achieved via treatment with the S1P precursor sphingosine, S1P agonist FTY720, or S1P receptor-1 (S1PR1) agonist SEW2871. Outcomes included sphingosine kinase-1 RNA expression and activity, sphingolipid measurements by combined liquid chromatography-tandem mass spectrometry, immunoblotting for prosurvival signaling pathways, caspase-3 activity and terminal deoxynucleotidyltransferase-mediated dUTP nick end labeling assays, and airspace morphometry. MEASUREMENTS AND MAIN RESULTS: Consistent with previously reported de novo activation of ceramide synthesis, VEGFR inhibition triggered increases in lung ceramides, dihydroceramides, and dihydrosphingosine, but did not alter sphingosine kinase activity or S1P levels. Administration of sphingosine decreased the ceramide-to-S1P ratio in the lung and inhibited alveolar space enlargement, along with activation of prosurvival signaling pathways and decreased lung parenchyma cell apoptosis. Sphingosine significantly opposed ceramide-induced apoptosis in cultured lung endothelial cells, but not epithelial cells. FTY720 or SEW2871 recapitulated the protective effects of sphingosine on airspace enlargement concomitant with attenuation of VEGFR inhibitor-induced lung apoptosis. CONCLUSIONS: Strategies aimed at augmenting the S1P-S1PR1 signaling may be effective in ameliorating the apoptotic mechanisms of emphysema development

Activity profiles of elite wheelchair rugby players during competition

To quantify the activity profiles of elite wheelchair rugby and establish classification-specific arbitrary speed zones. Additionally, indicators of fatigue during full matches were explored. Methods: Seventy-five elite wheelchair rugby players from eleven national teams were monitored using a radio-frequency based, indoor tracking system across two international tournaments. Players who participated in complete quarters (n = 75) and full matches (n = 25) were included and grouped by their International Wheelchair Rugby Federation functional classification: group I (0-0.5), II (1.0-1.5), III (2.0-2.5) and IV (3.0-3.5). Results: During a typical quarter, significant increases in total distance (m), relative distance (m·minˉ¹), and mean speed (m·sˉ¹) were associated with an increase in classification group (P < 0.001), with the exception of group III and IV. However, group IV players achieved significantly higher peak speeds (3.82 ± 0.31 m·sˉ¹) than groups I (2.99 ± 0.28 m·sˉ¹), II (3.44 ± 0.26 m·sˉ¹) and III (3.67 ± 0.32 m·sˉ¹). Groups I and II differed significantly in match intensity during very low/low speed zones and the number of high-intensity activities in comparison with groups III and IV (P < 0.001). Full match analysis revealed that activity profiles did not differ significantly between quarters. Conclusions: Notable differences in the volume of activity were displayed across the functional classification groups. However, the specific on-court requirements of defensive (I and II) and offensive (III and IV) match roles appeared to influence the intensity of match activities and consequently training prescription should be structured accordingly