An alternative approach for determining suction of polyethyleneglycols for soil testing

Determination of suction of Polyethylenglycol (PEG) is vital for unsaturated laboratory testing that use osmotic technique to study the hydro-mechanical behaviour of fine-grained soils. To date, suctions of PEG solutions are either experimentally measured or calculated from established semi-empirical relationships between concentration of PEG and suction. The current paper presents an alternative approach to determine suctions of aqueous PEG solutions based on a modified Flory-Huggins equation. Using the proposed method, suctions of various PEGs can be precisely calculated by knowing the average molar mass, concentration of the solution and an interaction coefficient which represents the quality of PEG-solvent interaction. The suggested method relies on the characteristics and thermodynamical behaviour of PEGs in solution. Experimental data of several PEG-water mixtures reported in the literature were analysed. The superiority of the current approach remains with abilities to verify molar of mass of PEGs and estimate suctions of PEG at high concentrations

Dynamically Triangulated Ising Spins in Flat Space

A model describing Ising spins with short range interactions moving randomly in a plane is considered. In the presence of a hard core repulsion, which prevents the Ising spins from overlapping, the model is analogous to a dynamically triangulated Ising model with spins constrained to move on a flat surface. It is found that as a function of coupling strength and hard core repulsion the model exhibits multicritical behavior, with first and second order transition lines terminating at a tricritical point. The thermal and magnetic exponents computed at the tricritical point are consistent with the exact two-matrix model solution of the random Ising model, introduced previously to describe the effects of fluctuating geometries.Comment: (10 pages + 4 figures), CERN-Th-7577/9

Electron exchange model potential: Application to positronium-helium scattering

The formulation of a suitable nonlocal model potential for electron exchange is presented, checked with electron-hydrogen and electron-helium scattering, and applied to the study of elastic and inelastic scattering and ionization of ortho positronium (Ps) by helium. The elastic scattering and the $n = 2$ excitations of Ps are investigated using a three-Ps-state close-coupling approximation. The higher ($n\ge 3$) excitations and ionization of Ps atom are treated in the framework of Born approximation with present exchange. Calculations are reported of phase shifts, and elastic, Ps-excitation, and total cross sections. The present target elastic total cross section agrees well with experimental results at thermal to medium energies.Comment: 16 latex pages, 7 postscript figure

Reduced costs with bisoprolol treatment for heart failure - An economic analysis of the second Cardiac Insufficiency Bisoprolol Study (CIBIS-II)

Background Beta-blockers, used as an adjunctive to diuretics, digoxin and angiotensin converting enzyme inhibitors, improve survival in chronic heart failure. We report a prospectively planned economic analysis of the cost of adjunctive beta-blocker therapy in the second Cardiac Insufficiency BIsoprolol Study (CIBIS II). Methods Resource utilization data (drug therapy, number of hospital admissions, length of hospital stay, ward type) were collected prospectively in all patients in CIBIS . These data were used to determine the additional direct costs incurred, and savings made, with bisoprolol therapy. As well as the cost of the drug, additional costs related to bisoprolol therapy were added to cover the supervision of treatment initiation and titration (four outpatient clinic/office visits). Per them (hospital bed day) costings were carried out for France, Germany and the U.K. Diagnosis related group costings were performed for France and the U.K. Our analyses took the perspective of a third party payer in France and Germany and the National Health Service in the U.K. Results Overall, fewer patients were hospitalized in the bisoprolol group, there were fewer hospital admissions perpatient hospitalized, fewer hospital admissions overall, fewer days spent in hospital and fewer days spent in the most expensive type of ward. As a consequence the cost of care in the bisoprolol group was 5-10% less in all three countries, in the per them analysis, even taking into account the cost of bisoprolol and the extra initiation/up-titration visits. The cost per patient treated in the placebo and bisoprolol groups was FF35 009 vs FF31 762 in France, DM11 563 vs DM10 784 in Germany and pound 4987 vs pound 4722 in the U.K. The diagnosis related group analysis gave similar results. Interpretation Not only did bisoprolol increase survival and reduce hospital admissions in CIBIS II, it also cut the cost of care in so doing. This `win-win' situation of positive health benefits associated with cost savings is Favourable from the point of view of both the patient and health care systems. These findings add further support for the use of beta-blockers in chronic heart failure

Engineering education for social and environmental justice: Scaffolding multidisciplinary knowledge through multiliteracies

This paper reports findings of a project funded by the Australian Learning and Teaching Council and titled Engineering Education for Social and Environmental Justice (EESEJ). In a context of rapid globalisation, the EESEJ project aims to increase tertiary student learning for social and environmental justice through a new critical approach to engineering education, encouraging student engineers to situate their technical expertise and respond ethically in social, economic and environmental contexts, both locally and globally (see Baillie & Catalano, 2009). A multidisciplinary research team in Australia, the UK and USA engaged in a range of activities, such as designing and implementing critical problem solving in undergraduate engineering courses and undertaking collaborative writing tasks in small research teams. The EESEJ project is based on several assumptions: that social and environmental justice are interwoven and the holistic curriculum approach recommended by Engineers Australia is valid, with students undertaking community projects in ways that responsibly consider social, economic, cultural, environmental and ethical factors. The work of socially just engineers is integrated with community consultation and governed by anti-oppressive principles (Young, 2000), so as to avoid exploitation, marginalization, cultural imperialism, powerlessness and violence in communities. The aim of this paper is to describe the experience of a group of participants in the EESEJ project, the methods they used and the outcomes they achieved

Swelling pressures and one-dimensional compressibility behaviour of bentonite at large pressures

In this study, the swelling pressures and one-dimensional compressibility behaviour of several compacted saturated bentonite specimens were determined. Laboratory oedometer tests were carried out on a bentonite from Germany, using distilled water as the bulk fluid. A newly developed high pressure oedometer device was used that enabled measurement of swelling pressures of initially unsaturated compacted bentonite specimens (strain-controlled tests) and then facilitated subsequent loading the specimens up to 25 MPa. Several initial compaction conditions (i.e., dry density and water content) of the bentonite were considered. The test results showed that both initial water content and compaction dry density influenced the swelling pressure of the bentonite. For the range of void ratio considered in this study, the swelling pressures of compacted saturated specimens were found to be significantly smaller than the applied vertical pressures during the consolidation tests. Also, the compression paths of compacted saturated specimens remained distinctly below that of the compression path for the initially saturated bentonite specimen even at very large pressures. The initial compaction conditions affected the compression index of the bentonite, whereas the effects were found to be less significant on the decompression index. The effect of initial compaction conditions on the coefficient of consolidation was found to be significant at void ratios greater than 0.5. The variation of the coefficient of permeability with the void ratio was found to be distinctly bilinear for an initially saturated bentonite specimen, whereas the permeability varied linearly with the void ratio for compacted saturated specimens. In general, the compacted saturated bentonite specimens were found to be more permeable than the initially saturated bentonite

Geoenvironmental Application of Bentonites in Underground Disposal of Nuclear Waste: Characterization and Laboratory Tests

In the context of underground storage of nuclear waste, this paper presents the characterization and laboratory tests on compacted MX80 bentonite. Various laboratory testing techniques were used for establishing the water retention behavior of the bentonite. Compacted bentonite specimens were hydrated with fluids of low and high salt concentrations both at ambient and an elevated temperature of 70°C. The swelling behavior of the bentonite was also studied by stepwise wetting compacted specimens at various suctions under isochoric condition. The influence of thermal and thermohydraulic gradients on the mechanical behavior of the bentonite was studied in a thermohydraulic column cell. The investigation showed that the development of swelling pressure in compacted bentonites upon a decrease in the applied suction is accompanied by a decrease in the magnitude suction stress, which gets manifested in the development of the interparticle repulsive pressure and a decrease in the effective stress. The influence of an elevated temperature and an increase in concentration of salt in the hydrating fluid was found to reduce the swelling pressure of the bentonite. Both thermal and thermohydraulic gradients were found to be manifested on the development of axial pressures. Applications of thermal and thermohydraulic gradients were found to cause redistributions of water content, dry density, degree of saturation, and suction within compacted bentonites