Conservativeness of non-symmetric diffusion processes generated by perturbed divergence forms

Let E be an unbounded open (or closed) domain in Euclidean space of dimension greater or equal to two. We present conservativeness criteria for (possibly reflected) diffusions with state space E that are associated to fairly general perturbed divergence form operators. Our main tool is a recently extended forward and backward martingale decomposition, which reduces to the well-known Lyons-Zheng decomposition in the symmetric case.Comment: Corrected typos, minor modification

Experimental tests of reaction rate theory: Mu+H2 and Mu+D2

Copyright @ 1987 American Institute of Physics.Bimolecular rate constants for the thermal chemical reactions of muonium (Mu) with hydrogen and deuterium—Mu+H2→MuH+H and Mu+D2→MuD+D—over the temperature range 473–843 K are reported. The Arrhenius parameters and 1σ uncertainties for the H2 reaction are log A (cm3 molecule-1 s-1)=-9.605±0.074 and Ea =13.29±0.22 kcal mol-1, while for D2 the values are -9.67±0.12 and 14.73±0.40, respectively. These results are significantly more precise than those reported earlier by Garner et al. For the Mu reaction with H2 our results are in excellent agreement with the 3D quantum mechanical calculations of Schatz on the Liu–Siegbahn–Truhlar–Horowitz potential surface, but the data for both reactions compare less favorably with variational transition-state theory, particularly at the lower temperatures.NSERC (Canada) and the Petroleum Research Foundation of the Americal Chemical Society

Sub-diffraction thin-film sensing with planar terahertz metamaterials

Planar metamaterials have been recently proposed for thin dielectric film sensing in the terahertz frequency range. Although the thickness of the dielectric film can be very small compared with the wavelength, the required area of sensed material is still determined by the diffraction-limited spot size of the terahertz beam excitation. In this article, terahertz near-field sensing is utilized to reduce the spot size. By positioning the metamaterial sensing platform close to the sub-diffraction terahertz source, the number of excited resonators, and hence minimal film area, are significantly reduced. As an additional advantage, a reduction in the number of excited resonators decreases the inter-cell coupling strength, and consequently the resonance Q factor is remarkably increased. The experimental results show that the resonance Q factor is improved by 113%. Moreover, for a film with a thickness of \lambda/375 the minimal area can be as small as 0.2\lambda by 0.2\lambda. The success of this work provides a platform for future metamaterial-based sensors for biomolecular detection.Comment: 8 pages, 6 figure

THE URUGUAY ROUND AGREEMENT ON AGRICULTURE: AN EVALUATION

Contact for this paper: Laura Bipes/University of Minnesota/Department of Applied Economics/ 1994 Buford Avenue./ St. Paul, MN 55108 USA. From the start, agriculture played a central role in the Uruguay Round of GATT trade negotiations. The Punta del Este Declaration called for a solution to the problems facing agricultural trade through modified trade rules and an agreement to lower protection levels. It was recognized that such an improvement implied negotiations on the national farm policies as well as just trade policies. The time that it took to reach agreement reflected the political sensitivity and technical complexity of this task. The Agreement embodied in the Final Act of the Uruguay Round breaks new ground for agriculture, and takes a big step towards placing this sector of world trade under rules more consistent with those in operation in other areas. However, the degree of liberalization of markets is modest, and much remains to be done in future rounds of negotiations. The most far-reaching element in the Agreement is a change in the rules regarding market access. With very few exceptions, all participating countries have agreed to convert all existing non-tariff barriers (along with unbound tariffs) into bound duties and not to introduce new non-tariff measures. Negotiations agreed to reduce these new bound tariffs, as well as tariffs already bound earlier, according to Schedules included as a part of the Agreement. "Tariffication" will impose changes in import policies for a number of countries. Canada will replace import quotas for dairy and poultry products with tariffs, initially at a high level. The European Union will replace its variable levy with tariffs, though a maximum duty-paid price for cereals has been negotiated which puts a limit on the tariff charged. Latin American countries have generally engaged in tariffication in recent years in advance of the Uruguay Round Agreement: for these, and other countries their tariffs will now be bound. The US will forgo the use of Section 22 import quotas and the negotiation of voluntary export restraint agreements with beef suppliers, but the impact on these markets is likely to be small. Japan and Korea have been allowed to delay tariffication in the case of rice for the next few years. The Agreement provides in cases of tariffication for "minimum access opportunities", to guard against the impact of high initial tariff rates. This will open up reduced-tariff quotas for a number of products including beef, cereals and fruits and vegetables. The quotas will be expanded to about 5 percent of consumption over the 6 year period. Japan and Korea have agreed to a greater expansion of market access for rice in compensation for the delay in introducing tariffs. The ability of countries to control export subsidies in agricultural markets was one of the main issues under discussion in the negotiation. Under the Agreement, countries accept commitments on reducing expenditure on export subsidies as well on the quantity of subsidized exports. This will limit export subsidies by the EU and other countries, for such products as wheat, dairy products and beef, and should lead to firmer world market prices in these commodities. These quantities are also expressed in the Schedules which form part of the Agreement. Countries have also agreed not to apply export subsidies to commodities not subsidized in the base period. The Agreement also sets rules and commitments for domestic support policies. It defines a set of policies which are deemed to be less trade-distorting than others, and allocates them to a "green box" which is broadly immune to challenge. Other policies not sheltered in this way are subject to reduction through a limit on the total support given by domestic subsidies and administered prices. It was decided that neither the U.S. deficiency payments (under current legislation) nor the new hectarage compensation payments under the reformed Common Agricultural Policy of the EU need to be reduced. It was also agreed that subsidies that conform to the new rules are sheltered from international challenge under the GATT. Developing Countries generally face less stringent commitments, having 10 years rather than six to make the changes, and having to meet only two-thirds of the reduction targets. In addition, development policies are included broadly in the "green box". Along with the provisions on domestic and trade policies in the Agreement, participants also concluded an Agreement on Sanitary and Phytosanitary Measures (SPS Agreement). The goal was to make it easier to distinguish between genuine health and safety issues and disguised protection. The right of countries to set their own safety and health standards is reaffirmed, but with the provision that such standards should be based on scientific justification and that use be made of international standards where possible. The extent to which the Agreement will lead to greater market access, curb export subsidies and modify domestic policies in the next few years can only be determined from a detailed inspection of the Schedule of commitments made by the individual countries. Paradoxically, the immediate impact on national policies is likely in most cases to be small. Many countries have been engaged in a process of reducing government support to agriculture, and making such support more closely targetted to needs, in advance of the outcome of the Round. Policy reforms in the EU, Canada, Sweden, Australia and New Zealand, along with much of Latin America, have been strongly influenced by the negotiations in the Uruguay Round. The Agreement thus takes on the task of supporting and locking-in such reforms, and encouraging them in other countries. In some aspects the Agreement falls short of expectations (or at least initial demands). It does not constitute a major move toward free trade in agricultural products: the cost of changing the rules has been to give up some degree of liberalization. The tariffs which countries will impose in place of non-tariff barriers are in many cases so high that trade will be restricted to the agreed access quantities. Export subsidy programs will continue though at a reduced level. The major pressure to reinstrument farm policies will continue to be from domestic budget constraints. It will take further rounds of negotiations to reduce protection in agricultural markets to a level comparable to that for most manufactured products. However, with the rule changes and the new types of country commitments agreed, a much more promising basis bas been created for future negotiations.International Relations/Trade,

Snow chemistry of Agassiz Ice Cap, Ellesmere Island, Northwest Territories, Canada

AbstractPit-wall samples were collected from two sites about 2 km apart on Agassiz Ice Cap, Ellesmere Island, Northwest Territories, Canada, in 1992, 1993 and 1994, and from a site a further 1 km distant, in order to study spatial and seasonal variations in snow chemistry. Two of the pits were dug in wind-scoured zones and one in an unscoured zone. Although a large part of the winter snow is removed from the scoured zones (which do not show very negativeδ18O values) the winter/spring anion peaks are still evident; this may be due to the predominance of dry deposition in mid-winter. The Cl−and SO42–ions peak in late winter/early spring, while NO3−peaks both in late winter/early spring and in summer. Vertical concentration profiles of all anions did not significantly alter over a 2 year period, indicating that there are no serious post-depositional changes due to evaporation, snow melting or photochemical reactions. However, comparisons between stake/board snow-accumulation measurements and those derived from the least scoured pit indicate that a single pit will represent annual accumulation rates for a local area only

Non-BPS Solutions of the Noncommutative CP^1 Model in 2+1 Dimensions

We find non-BPS solutions of the noncommutative CP^1 model in 2+1 dimensions. These solutions correspond to soliton anti-soliton configurations. We show that the one-soliton one-anti-soliton solution is unstable when the distance between the soliton and the anti-soliton is small. We also construct time-dependent solutions and other types of solutions.Comment: 11 pages, minor correction

Reaction kinetics of muonium with the halogen gases (F2, Cl2, and Br2)

Copyright @ 1989 American Institute of PhysicsBimolecular rate constants for the thermal chemical reactions of muonium (Mu) with the halogen gases—Mu+X2→MuX+X—are reported over the temperature ranges from 500 down to 100, 160, and 200 K for X2=F2,Cl2, and Br2, respectively. The Arrhenius plots for both the chlorine and fluorine reactions show positive activation energies Ea over the whole temperature ranges studied, but which decrease to near zero at low temperature, indicative of the dominant role played by quantum tunneling of the ultralight muonium atom. In the case of Mu+F2, the bimolecular rate constant k(T) is essentially independent of temperature below 150 K, likely the first observation of Wigner threshold tunneling in gas phase (H atom) kinetics. A similar trend is seen in the Mu+Cl2 reaction. The Br2 data exhibit an apparent negative activation energy [Ea=(−0.095±0.020) kcal mol−1], constant over the temperature range of ∼200–400 K, but which decreases at higher temperatures, indicative of a highly attractive potential energy surface. This result is consistent with the energy dependence in the reactive cross section found some years ago in the atomic beam data of Hepburn et al. [J. Chem. Phys. 69, 4311 (1978)]. In comparing the present Mu data with the corresponding H atom kinetic data, it is found that Mu invariably reacts considerably faster than H at all temperatures, but particularly so at low temperatures in the cases of F2 and Cl2. The current transition state calculations of Steckler, Garrett, and Truhlar [Hyperfine Interact. 32, 779 (986)] for Mu+X2 account reasonably well for the rate constants for F2 and Cl2 near room temperature, but their calculated value for Mu+Br2 is much too high. Moreover, these calculations seemingly fail to account for the trend in the Mu+F2 and Mu+Cl2 data toward pronounced quantum tunneling at low temperatures. It is noted that the Mu kinetics provide a crucial test of the accuracy of transition state treatments of tunneling on these early barrier HX2 potential energy surfaces.NSERC (Canada), Donors of the Petroleum Research Fund, administered by the American Chemical Society, for their partial support of this research and the Canada Council

Recovery of herbicide-resistant Azuki bean [Vigna angularis (Wild.), Ohwi & Ohashi] plants via Agrobacterium-mediated transformation

Transgenic azuki bean [Vigna angularis (Willd.) Ohwi & Ohashi] plants expressing the hygromycin phosphotransferase (hpt), green fluorescent protein (sgfp) and phosphinothricin acetyltransferase (bar) genes were obtained by Agrobacterium- tumefacients - mediated transformation. A total of 210 epicotyl explants were inoculated with A. tumefaciens strain EHA105, harboring the binary plasmid pZHBG on MS co-cultivation medium supplemented with 100 mM acetosyringone and 10 mg/l of BA. Following selection on MS medium with 15 mg/l of hygromycin, the regenerated adventitious shoots that formed on the induced calli were further screened for sgfp expression before transferred to rooting medium. 31 transgenic plants were obtained with transformation frequency of 14%. The presence of transgenes in transformed azuki bean plants was confirmed by polymerase chain reaction (PCR) and southern blot analysis. Transcription of the bar and hpt genes was assessed by reverse transcription polymerase chain reaction (RT-PCR) analysis. sgfp- positive transgenic plants exhibited functional expression of the bar gene as determined by assaying for resistance to bialaphos applied directly to leaves. This result demonstrates the feasibility of introducing potentially useful agronomic traits into azuki bean through genetic engineering. Key Words: Agrobacterium tumefaciens, bar gene, bialaphos, transgenic, Vigna angulazris. African Journal of Biotechnology Vol.4(1) 2005: 61-6