Wear and Friction Modeling on Lifeboat Launch Systems

The RNLI provides search and rescue cover along the UK and RoI coast using a variety of lifeboats and launch techniques. In locations where there is no natural harbour it is necessary to use a slipway to launch the lifeboat into the sea. Lifeboat slipway stations consist of an initial section where the boat is held on rollers followed by an inclined keelway lined with low friction composite materials, the lifeboat is released from the top of the slipway and proceeds under its own weight into the water. The lifeboat is later recovered using a winch line. It is common to manually apply grease to the composite slipway lining before each launch and recovery in order to ensure sufficiently low friction for successful operation. With the introduction of the Tamar class lifeboat it is necessary to upgrade existing boathouses and standardise slipway operational procedures to ensure consistent operation. The higher contact pressures associated with the new lifeboat have led to issues of high friction and wear on the composite slipway linings and the manual application of grease to reduce friction is to be restricted due to environmental impact and cost factors. This paper presents a multidisciplinary approach to modelling slipway panel wear and friction using tribometer testing in conjunction with finite element analysis and slipway condition surveys to incorporate common real-world effects such as panel misalignments. Finally, it is shown that a freshwater lubrication system is effective, reducing cost and environmental impacts while maintaining good friction and wear performance

Physical Baryon Resonance Spectroscopy from Lattice QCD

We complement recent advances in the calculation of the masses of excited baryons in quenched lattice QCD with finite-range regulated chiral effective field theory enabling contact with the physical quark mass region. We examine the P-wave contributions to the low-lying nucleon and delta resonances.Comment: Contributed paper at FB17, the 17th International Conference on Few-Body Problems in Physics, Durham, NC, June 5-10, 2003. 3 pages, 6 figure

Lattice QCD Calculations of Hadron Structure: Constituent Quarks and Chiral Symmetry

New data from parity-violating experiments on the deuteron now allow isolation of the strange-quark contribution to the nucleon magnetic moment, G_M^s(0), without the uncertainty surrounding the anapole moment of the nucleon. Still, best estimates place G_M^s(0) > 0. It is illustrated how this experimental result challenges the very cornerstone of the constituent quark model. The chiral physics giving rise to G_M^s(0) \sim 0 is illustrated.Comment: Invited talk presented by DBL at the 16th Int. Conf. on Few Body Problems (Taipei, March 6-10, 2000); 9 pages, 5 figure

Inequalities in premature mortality in Britain: observational study from 1921 to 2007

Objective To report on the extent of inequality in premature mortality as measured between geographical areas in Britain. Design Observational study of routinely collected mortality data and public records. Population subdivided by age, sex, and geographical area (parliamentary constituencies from 1991 to 2007, pre-1974 local authorities over a longer time span). Setting Great Britain. Participants Entire population aged under 75 from 1990 to 2007, and entire population aged under 65 in the periods 1921-39, 1950-3, 1959-63, 1969-73, and 1981-2007. Main outcome measure Relative index of inequality (RII) and ratios of inequality in age-sex standardised mortality ratios under ages 75 and 65. The relative index of inequality is the relative rate of mortality for the hypothetically worst-off compared with the hypothetically best-off person in the population, assuming a linear association between socioeconomic position and risk of mortality. The ratio of inequality is the ratio of the standardised mortality ratio of the most deprived 10% to the least deprived 10%. Results When measured by the relative index of inequality, geographical inequalities in age-sex standardised rates of mortality below age 75 have increased every two years from 1990-1 to 2006-7 without exception. Over this period the relative index of inequality increased from 1.61 (95% confidence interval 1.52 to 1.69) in 1990-1 to 2.14 (2.02 to 2.27) in 2006-7. Simple ratios indicated a brief period around 2001 when a small reduction in inequality was recorded, but this was quickly reversed and inequalities up to the age of 75 have now reached the highest levels reported since at least 1990. Similarly, inequalities in mortality ratios under the age of 65 improved slightly in the early years of this century but the latest figures surpass the most extreme previously reported. Comparison of crudely age-sex standardised rates for those below age 65 from historical records showed that geographical inequalities in mortality are higher in the most recent decade than in any similar time period for which records are available since at least 1921. Conclusions Inequalities in premature mortality between areas of Britain continued to rise steadily during the first decade of the 21st century. The last time in the long economic record that inequalities were almost as high was in the lead up to the economic crash of 1929 and the economic depression of the 1930s. The economic crash of 2008 might precede even greater inequalities in mortality between areas in Britain

Chiral extrapolation and physical insights

It has recently been established that finite-range regularisation in chiral effective field theory enables the accurate extrapolation of modern lattice QCD results to the chiral regime. We review some of the highlights of extrapolations of quenched lattice QCD results, including spectroscopy and magnetic moments. The $\Delta$ resonance displays peculiar chiral features in the quenched theory which can be exploited to demonstrate the presence of significant chiral corrections.Comment: 6 pages, 5 figures, presented at LHP2003, Cairns, Australi

Hadron structure on the back of an envelope

In order to remove a little of the mysticism surrounding the issue of strangeness in the nucleon, we present simple, physically transparent estimates of both the strange magnetic moment and charge radius of the proton. Although simple, the estimates are in quite good agreement with sophisticated calculations using the latest input from lattice QCD. We further explore the possible size of systematic uncertainties associated with charge symmetry violation (CSV) in the recent precise determination of the strange magnetic moment of the proton. We find that CSV acts to increase the error estimate by 0.003 \mu_N such that G_M^s = -0.046 +/- 0.022 \mu_N.Comment: 9 pages, 1 figure, Invited talk at First Workshop on Quark-Hadron Duality and the Transition to pQCD, Frascati, June 6-8 200

Performing joint measurements and transformations on several qubits by operating on a single control qubit

An n-qubit quantum register can in principle be completely controlled by operating on a single qubit that interacts with the register via an appropriate fixed interaction. We consider a hypothetical system consisting of n spin-1/2 nuclei that interact with an electron spin via a magnetic interaction. We describe algorithms that measure non-trivial joint observables on the register by acting on the control spin only. For large n this is not an efficient model for universal quantum computation but it can be modified to an efficient one if one allows n possible positions of the control particle. This toy model of measurements illustrates in which way specific interactions between the register and a probe particle support specific types of joint measurements in the sense that some joint observables can be measured by simple sequences of operations on the probe particle.Comment: 7 pages, revtex, 3 figure

Chiral Symmetry and the Intrinsic Structure of the Nucleon

Understanding hadron structure within the framework of QCD is an extremely challenging problem. In order to solve it, it is vital that our thinking should be guided by the best available insight. Our purpose here is to explain the model independent consequences of the approximate chiral symmetry of QCD for two famous results concerning the structure of the nucleon. We show that both the apparent success of the constituent quark model in reproducing the ratio of the proton to neutron magnetic moments and the apparent success of the Foldy term in reproducing the observed charge radius of the neutron are coincidental. That is, a relatively small change of the current quark mass would spoil both results.Comment: RevTeX, 10 pages, 2 figure