Rationality and the Foundations of Positive Political Theory

In this paper, we discuss and debunk the four most common critiques of the rational choice research program (which we prefer to call Positive Political Theory) by explaining and advocating its foundations: the rationality assumption, component analysis (abstraction), strategic behavior, and theory building, in turn. We argue that the rationality assumption and component analysis, properly understood, can be seen to underlie all social science, despite the protestations of critics. We then discuss the two ways that PPT most clearly contributes to political science (i.e., what distinguishes it from other research programs), namely the introduction of strategic behavior (people do not just act; they interact) and PPT’s more careful attention to the theory-building step within the scientific method. We explain the roles of theory- building and of empirical “testing,” respectively, in scientific inquiry, and the criteria by which theories should and should not be judged

As a Matter of Factions: The Budgetary Implications of Shifting Factional Control in Japan’s LDP

For 38 years, the Liberal Democratic Party (LDP) maintained single-party control over the Japanese government. This lack of partisan turnover in government has frustrated attempts to explain Japanese government policy changes using political variables. In this paper, we look for intraparty changes that may have led to changes in Japanese budgetary policy. Using a simple model of agenda-setting, we hypothesize that changes in which intraparty factions “control” the LDP affect the party’s decisions over spending priorities systematically. This runs contrary to the received wisdom in the voluminous literature on LDP factions, which asserts that factions, whatever their raison d’être, do not exhibit different policy preferences. We find that strong correlations do exist between which factions comprise the agenda-setting party “mainstream” and how the government allocates spending across pork-barrel and public goods items

Integrating out the Dirac sea: Effective field theory approach to exactly solvable four-fermion models

We use 1+1 dimensional large N Gross-Neveu models as a laboratory to derive microscopically effective Lagrangians for positive energy fermions only. When applied to baryons, the Euler-Lagrange equation for these effective theories assumes the form of a non-linear Dirac equation. Its solution reproduces the full semi-classical results including the Dirac sea to any desired accuracy. Dynamical effects from the Dirac sea are encoded in higher order derivative terms and multi-fermion interactions with perturbatively calculable, finite coefficients. Characteristic differences between models with discrete and continuous chiral symmetry are observed and clarified.Comment: 13 pages, 11 figures; v2: typos corrected (Eqs. 4 and 44

A natural formation scenario for misaligned and short-period eccentric extrasolar planets

Recent discoveries of strongly misaligned transiting exoplanets pose a challenge to the established planet formation theory which assumes planetary systems to form and evolve in isolation. However, the fact that the majority of stars actually do form in star clusters raises the question how isolated forming planetary systems really are. Besides radiative and tidal forces the presence of dense gas aggregates in star-forming regions are potential sources for perturbations to protoplanetary discs or systems. Here we show that subsequent capture of gas from large extended accretion envelopes onto a passing star with a typical circumstellar disc can tilt the disc plane to retrograde orientation, naturally explaining the formation of strongly inclined planetary systems. Furthermore, the inner disc regions may become denser, and thus more prone to speedy coagulation and planet formation. Pre-existing planetary systems are compressed by gas inflows leading to a natural occurrence of close-in misaligned hot Jupiters and short-period eccentric planets. The likelihood of such events mainly depends on the gas content of the cluster and is thus expected to be highest in the youngest star clusters.Comment: 7 pages, 4 figures. Accepted for publication in MNRAS. Updated to match published versio

An Alliance Unravels

On 1 September 1951, representatives of Australia , New Zealand , and the United States met in San Fran cisco to sign a treaty of alliance commonly known as the Anzus pact.1 The signing ceremony had been preceded by two years of sporadic negotiations during which the Australians had pressed hard for joint military planning and discu ssion of global strategy. The Americans, however, had been determined to limit formal security arrangements to the minimum necessary to win the consent of their negotiating partners to the relatively mild peace treaty the United States intended to sign with Japan.2 The American view prevailed, and Anzus thus came into being with a council charged with considering matters related to the implementation of the treaty but with no standing military organization and no integrated military force

Are older people putting themselves at risk when using their walking frames?

Background Walking aids are issued to older adults to prevent falls, however, paradoxically their use has been identified as a risk factor for falling. To prevent falls, walking aids must be used in a stable manner, but it remains unknown to what extent associated clinical guidance is adhered to at home, and whether following guidance facilitates a stable walking pattern. It was the aim of this study to investigate adherence to guidance on walking frame use, and to quantify user stability whilst using walking frames. Additionally, we explored the views of users and healthcare professionals on walking aid use, and regarding the instrumented walking frames (‘Smart Walkers’) utilized in this study. Methods This observational study used Smart Walkers and pressure-sensing insoles to investigate usage patterns of 17 older people in their home environment; corresponding video captured contextual information. Additionally, stability when following, or not, clinical guidance was quantified for a subset of users during walking in an Activities of Daily Living Flat and in a gait laboratory. Two focus groups (users, healthcare professionals) shared their experiences with walking aids and provided feedback on the Smart Walkers. Results Incorrect use was observed for 16% of single support periods and for 29% of dual support periods, and was associated with environmental constraints and a specific frame design feature. Incorrect use was associated with reduced stability. Participants and healthcare professionals perceived the Smart Walker technology positively. Conclusions Clinical guidance cannot easily be adhered to and self-selected strategies reduce stability, hence are placing the user at risk. Current guidance needs to be improved to address environmental constraints whilst facilitating stable walking. The research is highly relevant considering the rising number of walking aid users, their increased falls-risk, and the costs of falls. Trial Registration Not applicable

A novel mooring tether for highly dynamic offshore applications; mitigating peak and fatigue loads via selectable axial stiffness (conference paper)

PublishedHighly dynamic floating bodies such as wave energy convertors (WECs) require mooring lines with particular mechanical properties; the mooring system must achieve adequate station keeping whilst controlling mooring tensions within acceptable limits. Currently, fibre ropes are commonly used but many mooring designers are seeking alternative solutions that can offer more favourable mechanical properties. The compliance offered by a mooring system will depend largely on the axial stiffness of the mooring lines. Whilst fibre ropes can offer lower axial stiffness than alternatives such as chain and wire rope, there remains a fundamental conflict which prohibits the free selection of axial stiffness properties. This conflict exists because the axial stiffness is strongly governed by the minimum breaking load (MBL) of the rope. The specified MBL must be sufficient to accommodate the predicted peak tension loads with an appropriate factor of safety (FOS) to cater for uncertainties and degradations. In achieving a sufficient MBL, the designer is often forced to accept a higher axial stiffness than is preferred. A potential benefit of reducing the axial stiffness of a mooring line is the reduction of peak loads and fatigue loads. This allows a reduction in mass of both the floating body and the mooring system, thus reducing costs and improving system reliability. This work describes the 'Exeter Tether', an innovation in mooring tether design which decouples the axial stiffness properties from the MBL of the tether. Removing this constraint allows a tether to be specified according to both MBL and axial stiffness. The principals behind the novel tether design are introduced along with an outline of 10 prototype tether variants manufactured in collaboration with Lankhorst Ropes. Results from the proof of concept tests at the University of Exeter's Dynamic Marine Component Test Facility (DMaC) are presented together with preliminary findings from sea trials at the South West Moorings Test Facility (SWMTF). The anticipated load mitigation introduced via the mooring tether is investigated and the implications for system design are discussed.UK Centre for Marine Energy Research (UKCMER) through the SuperGen programme funded by the EPSR

Biomechanics for inclusive urban design : effects of tactile paving on older adults’ gait when crossing the street

In light of our ageing population it is important that the urban environment is easily accessible and hence supports older adults’ independence. Tactile ‘blister’ paving was originally designed to provide guidance for visually impaired people at pedestrian crossings. However, as research links irregular surfaces to falls in older adults, such paving may have an adverse effect on older people. We investigated the effects of tactile paving on older adults’ gait in a scenario closely resembling “crossing the street”. Gait analysis of 32 healthy older adults showed that tactile, as compared to smooth, paving increases the variability in timing of foot placement by 20%, thereby indicating a disturbance of the rhythmic gait pattern. Moreover, toe-clearance during the swing phase increased by 7% on tactile paving, and the ability to stop upon cue from the traffic light was compromised. These results need to be viewed under consideration of the limitations associated with laboratory studies and real world analysis is needed to fully understand their implications for urban design