The Problem with the Dock Case

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Absorption, Photoluminescence and Resonant Rayleigh Scattering Probes of Condensed Microcavity Polaritons

We investigate and compare different optical probes of a condensed state of microcavity polaritons in expected experimental conditions of non-resonant pumping. We show that the energy- and momentum-resolved resonant Rayleigh signal provide a distinctive probe of condensation as compared to, e.g., photoluminescence emission. In particular, the presence of a collective sound mode both above and below the chemical potential can be observed, as well as features directly related to the density of states of particle-hole like excitations. Both resonant Rayleigh response and the absorption and photoluminescence, are affected by the presence of quantum well disorder, which introduces a distribution of oscillator strengths between quantum well excitons at a given energy and cavity photons at a given momentum. As we show, this distribution makes it important that in the condensed regime, scattering by disorder is taken into account to all orders. We show that, in the low density linear limit, this approach correctly describes inhomogeneous broadening of polaritons. In addition, in this limit, we extract a linear blue-shift of the lower polariton versus density, with a coefficient determined by temperature and by a characteristic disorder length.Comment: 16 pages, 11 figures; minor correction

The Law Commission presumption concerning the dependability of computer evidence

We consider the condition set out in section 69(1)(b) of the Police and Criminal Evidence Act 1984 (PACE 1984) that reliance on computer evidence should be subject to proof of its correctness, and compare it to the 1997 Law Commission recommendation that acommon law presumption be used that a computer operated correctly unless there is explicit evidence to the contrary (LC Presumption). We understand the LC Presumption prevails in current legal proceedings. We demonstrate that neither section 69(1)(b) of PACE 1984 nor the LC presumption reflects the reality of general software-based system behaviour

Now we are six: lessons from New Zealand’s KiwiSaver

New Zealand’s KiwiSaver was introduced on 1 July 2007. New Zealand’s success with the ‘soft compulsion’ of automatic enrolment has been and is continuing to be an influence in the design of opt-out schemes in the UK and Ireland. While there have been numerous changes to KiwiSaver as outlined in this paper, six years on, the retirement saving scheme appears well accepted by the public and membership has exceeded most expectations. New Zealand’s experience suggests that auto-enrolment and large incentives to entice people to remain opted-in may ensure initial take-up is high. It also suggests the incentives may be reduced significantly ex post with little impact on membership. Core tax-funded KiwiSaver subsidies have been both substantially reduced and not indexed while membership has continued to grow strongly. Whether this auto-enrolment scheme, featuring generous provisions for withdrawals and contributions holidays, is sufficient to ensure that those who should be saving for their retirement are saving, and saving enough, is open to debate. If KiwiSaver is made compulsory, as some powerful lobbies propose, there are large complexities to resolve, including the future role of the universal state pension, New Zealand Superannuation. Lessons from KiwiSaver on what to avoid in the design of a national retirement saving scheme may include: opening it to children; offering housing subsidies; allowing too many providers and privileging some of these as ‘default providers’; ignoring the issue of decumulation; and obscure objectives. Advantages over previous work-based retirement saving schemes include the portability of KiwiSaver accounts facilitated by the IRD’s role as a clearing house. New Zealand has also limited regressivity in the design of its very modest tax incentives, but at a cost: many save just the minimum required to maximise the subsidies. The Working Paper surveys the first six years of KiwiSaver’s evolution to July 2013. In that time, the fundamental questions around its purpose and design have not been resolved. Is its purpose to enhance access to suitable wealth accumulation vehicles for those who have missed out on traditional work-based schemes? Or is it to reduce the pressures on the economy of an ageing population; or to solve the national saving problem? Will KiwiSavers in fact have more to spend during their retirement, or will they simply reduce other savings to compensate? In the long term, what are the implications for New Zealand’s overall pensions framework, and in particular the very successful universal state pension? As 2014 is an election year, political parties are positioning themselves on KiwiSaver policy. In the meantime there is strong international interest in New Zealand’s retirement saving scheme, with its unique features such as auto-enrolment. The Retirement Policy and Research Centre is pleased to publish KiwiSaver: Now we are six. It updates earlier working papers, including Working Paper 2010 KiwiSaver: lessons for Ireland. TheviewsinthisWorkingPaper’scommentaryarethoseoftheauthors

Solitonic Phase in Manganites

Whenever a symmetry in the ground state of a system is broken, topological defects will exist. These defects are essential for understanding phase transitions in low dimensional systems[1]. Excitingly in some unique condensed matter systems the defects are also the low energy electric charge excitations. This is the case of skyrmions in quantum Hall ferromagnets[2] and solitons in polymers[3]. Orbital order present in several transitions metal compounds[4-6] could give rise to topological defects. Here we argue that the topological defects in orbital ordered half doped manganites are orbital solitons. Surprisingly, these solitons carry a fractional charge of $\pm$e/2, and whenever extra charge is added to the system an array of solitons is formed and an incommensurate solitonic phase occurs. The striking experimental asymmetry in the phase diagram as electrons or holes are added to half doped manganites[7-12], is explained by the energy difference between positive and negative charged solitons. Contrary to existent models that explain coexistence between phases in manganites as an extrinsic effect[13-14], the presence of inhomogeneities is naturally explained by the existence of solitonic phases. The occurrence and relevance of orbital solitons might be a general phenomena in strongly correlated systems.Comment: 10 pages, 5 figures include

Conflicting Commemotations: The Saint John war memorial and the Women's Christian Temperance Union fountain, 1922–1925

This article explores the construction of the war memorial in Saint John, New Brunswick. There was intense debate surrounding the location of the memorial because many in the community wanted to remove the Women’s Christian Temperance Union’s fountain, which had been built to honour the Loyalist women who founded the city. Some prominent Saint John citizens, including the mayor, thought that removing the fountain would be erasing that “sacred” memory. This debate reveals that even though the country was in the wake of a deadly global conflict, local memories and identities held strong.Le présent article explore la construction du monument de guerre à Saint John, au Nouveau-Brunswick. Il y a eu d’intenses débats au sujet de l’emplacement de ce monument, car de nombreuses personnes de la collectivité voulaient retirer la fontaine du Women’s Christian Temperance Union, qui avait été construite pour honorer les femmes loyalistes qui avaient fondé la ville. Certains citoyens influents de Saint John, y compris le maire, pensaient que le fait de retirer la fontaine effacerait le souvenir « sacré ». Un tel débat révèle que, même si le pays était dans le sillage d’un conflit mondial meurtrier, les souvenirs et les identités collectifs restaient vivants