The velocity of shear waves in unsaturated soil

The velocities of shear waves Vs in two soils, a loamy sand and a sandy clay loam, were measured at various matric potentials and confining pressures. We used a combination of Haines apparatus, pressure plate apparatus and a Bishop and Wesley tri-axial cell to obtain a range of saturation and consolidation states. We proposed a single effective stress variable based on a modification to Bishop’s equation which could be used in a published empirical model (Santamarina et al., 2001) to relate shear wave velocity to soil physical conditions. Net stress required a nonlinear transformation. Matric potential was converted into suction stress with the function proposed by Khallili and Khabbaz (1998), thus requiring an estimate of the air entry potential. We found it was possible to fit Vs to void ratio, net stress and matric potential with a set of four parameters which were common to all soils at various states of saturation and consolidation. In addition to the data collected for this study we also used previously published data (Whalley et al., 2011). The utility of shear wave measurements to deduce soil physical properties is discussed

2003-05 Taxes and Traffic in Asian Cities: Ownership and Use Taxes on Autos in Singapore

This paper presents a simple general equilibrium model involving trips from residential areas to a central business district, along with modal choice between cars and public transit. Using a calibrated numerical model, we investigate the relative merits of ownership and use taxes. The proposed model is used to evaluate traffic control policies in Singapore and can be used in other Asian countries. We compare full internalisation of congestion externalities to optimal tax outcomes for the different tax types. In our framework, use taxes restore Pareto optimality since congestion damage rises with more trips. Ownership taxes only partially internalise congestion externalities. However, in terms of revenue-raising ability, the marginal excess burdens in the neighbourhood of optimal taxes are typically lower for ownership taxes than use taxes

OPE Constraints and the Leading Order Hadronic Contribution to (g-2)_mu

OPE constraints are studied as a means of distinguishing between the versions of the I=1 vector spectral function extracted from (i) inclusive I=1 hadronic electroproduction cross-sections and (ii) inclusive I=1 hadronic tau decay data, with the goal of clarifying expectations for the leading order hadronic contribution to a_mu = (g-2)_mu /2 in the Standard Model. The constraints are shown to, at present, favor the tau decay data, and hence a Standard Model prediction for a_mu compatible with the BNL E821 experimental result. The relative role of the 2pi and 4pi contributions to the discrepancy between the integrated electroproduction results and the corresponding OPE constraints is also investigated, and the significance, in this context, of forthcoming re-measurements of the e^+e^- --> pi^+ pi^- pi^0 pi^0 cross-sections pointed out.Comment: 6 pages, 5 figures, prepared for the Proceedings of the 9th International Workshop on Tau Lepton Physic

Livestock Producers and Researchers - A Case Study of an Effective Partnership

The Sustainable Grazing Systems Programme (SGS) ran from 1996-2002 with 11 regional producer committees (Regional Producer Network - Simpson et al., 2003) and 6 research sites (National Experiment Andrew & Lodge, 2003) distributed throughout the high rainfall zone of temperate Australia. Each regional committee had a core of producers, with invited scientists and extension practitioners and a paid facilitator. The chair was always a producer and rotated annually. Each regional committee conducted a number of paddock-sized demonstrations of improved grazing management practices on a number of farms within the themes; grazing management and weeds, high input systems, innovative grazing methods for production and the SGS adoption process. Each demonstration was on a producer\u27s property assisted by a local management committee with objective data collected by the regional facilitator. The National research sites investigated the effects of grazing management on sustainable livestock production through five themes; water, nutrients, pastures, animals and biodiversity. Producers had a significant input into the design of the National Experiment and each site had a local advisory committee

An overlooked mechanism underlying the attenuated temperature response of soil heterotrophic respiration

Biogeochemical reactions occurring in soil pore space underpin gaseous emissions measured at macroscopic scales but are difficult to quantify due to their complexity and heterogeneity. We develop a volumetric-average method to calculate aerobic respiration rates analytically from soil with microscopic soil structure represented explicitly. Soil water content in the model is the result of the volumetric-average of the microscopic processes, and it is nonlinearly coupled with temperature and other factors. Since many biogeochemical reactions are driven by oxygen (O2) which must overcome various resistances before reaching reactive microsites from the atmosphere, the volumetric-average results in negative feedback between temperature and soil respiration, with the magnitude of the feedback increasing with soil water content and substrate quality. Comparisons with various experiments show the model reproduces the variation of carbon dioxide emission from soils under different water content and temperature gradients, indicating that it captures the key microscopic processes underpinning soil respiration. We show that alongside thermal microbial adaptation, substrate heterogeneity and microbial turnover and carbon use efficiency, O2 dissolution and diffusion in water associated with soil pore space is another key explanation for the attenuated temperature response of soil respiration and should be considered in developing soil organic carbon models

Implication of the PAMELA antiproton data for dark matter indirect detection at LHC

Since the PAMELA results on the "anomalously" high positron fraction and the lack of antiproton excess in our Galaxy, there has been a tremendous number of studies advocating new types of dark matter, with larger couplings to electrons than to quarks. This raises the question of the production of dark matter particles (and heavy associated coloured states) at LHC. Here, we explore a very simple benchmark dark matter model and show that, in spite of the agreement between the PAMELA antiproton measurements and the expected astrophysical secondary background, there is room for large couplings of a WIMP candidate to heavy quarks. Contrary to what could have been naively anticipated, the PAMELA pbar/p measurements do not challenge dark matter model building, as far as the quark sector is concerned. A quarkophillic species is therefore not forbidden.Owing to these large couplings, one would expect that a new production channel opens up at the LHC, through quark--quark and quark--gluon interactions. Alas, when the PDF of the quark is taken into account, prospects for a copious production fade away.Comment: 7 pages, 2 figures, captions of some figures modified, main conclusion unchange

Excavations and the afterlife of a professional football stadium, Peel Park, Accrington, Lancashire: towards an archaeology of football

Association football is now a multi-billion dollar global industry whose emergence spans the post-medieval to the modern world. With its professional roots in late 19th-century industrial Lancashire, stadiums built for the professionalization of football first appear in frequency in the North of England. While many historians of sport focus on consumerism and ‘topophilia’ (attachment to place) regarding these local football grounds, archaeological research that has been conducted on the spectator experience suggests status differentiation within them. Our excavations at Peel Park confirm this impression while also showing a significant afterlife to this stadium, particularly through children’s play

Optimisation and analysis of streamwise-varying wall-normal blowing in a turbulent boundary layer

Skin-friction drag is a major engineering concern, with wide-ranging consequences across many industries. Active flow-control techniques targeted at minimising skin friction have the potential to significantly enhance aerodynamic efficiency, reduce operating costs, and assist in meeting emission targets. However, they are difficult to design and optimise. Furthermore, any performance benefits must be balanced against the input power required to drive the control. Bayesian optimisation is a technique that is ideally suited to problems with a moderate number of input dimensions and where the objective function is expensive to evaluate, such as with high-fidelity computational fluid dynamics simulations. In light of this, this work investigates the potential of low-intensity wall-normal blowing as a skin-friction drag reduction strategy for turbulent boundary layers by combining a high-order flow solver (Incompact3d) with a Bayesian optimisation framework. The optimisation campaign focuses on streamwise-varying wall-normal blowing, parameterised by a cubic spline. The inputs to be optimised are the amplitudes of the spline control points, whereas the objective function is the net-energy saving (NES), which accounts for both the skin-friction drag reduction and the input power required to drive the control (with the input power estimated from real-world data). The results of the optimisation campaign are mixed, with significant drag reduction reported but no improvement over the canonical case in terms of NES. Selected cases are chosen for further analysis and the drag reduction mechanisms and flow physics are highlighted. The results demonstrate that low-intensity wall-normal blowing is an effective strategy for skin-friction drag reduction and that Bayesian optimisation is an effective tool for optimising such strategies. Furthermore, the results show that even a minor improvement in the blowing efficiency of the device used in the present work will lead to meaningful NES