Is APEC Irresistible?

This paper will discuss two aspects of APEC: the model of regional integration that it promotes; and the difficulties of resisting or even shaping the trend towards economic liberalisation of which it is a part

Was Scotland deglaciated during the Younger Dryas?

Recent work has produced data that challenges the canonical view that the Younger Dryas (c.12.9–11.7 ka) was a time of glacier expansion across the North Atlantic. Boulders on moraines located within the inner sector of the Scottish Loch Lomond Stadial (≈Younger Dryas) ice cap yield cosmogenic exposure ages 12.8–11.3 ka with a best estimate moraine age of 11.5 ± 0.6 ka. This age contradicts the interpretation that Scotland was completely deglaciated as early as 12,580 cal yr BP and no later than 12,200 cal yr BP. Our data supports the previously accepted scenario, supported by a wide variety of data, that final deglaciation of Scotland did not occur until late in the Loch Lomond Stadial or the early Holocene

Aerodynamic tests and analysis of a turbojet-boosted launch vehicle concept (spacejet) over a Mach number range of 1.50 to 2.86

Results from analytical and experimental studies of the aerodynamic characteristics of a turbojet-boosted launch vehicle concept through a Mach number range of 1.50 to 2.86 are presented. The vehicle consists of a winged orbiter utilizing an area-ruled axisymmetric body and two winged turbojet boosters mounted underneath the orbiter wing. Drag characteristics near zero lift were of prime interest. Force measurements and flow visualization techniques were employed. Estimates from wave drag theory, supersonic lifting surface theory, and impact theory are compared with data and indicate the ability of these theories to adequately predict the aerodynamic characteristics of the vehicle. Despite the existence of multiple wings and bodies in close proximity to each other, no large scale effects of boundary layer separation on drag or lift could be discerned. Total drag levels were, however, sensitive to booster locations

Essays on Fiscal Policy and Tax Compliance

This dissertation comprises three essays that examine critical aspects of fiscal policy and explores important determinants of tax compliance in a developing country context. The first essay examines the fiscal response to changes in debt-to-GDP for a panel of developing countries. Our empirical strategy adopts a dynamic difference generalized methods of moments (DGMM) model with forward orthogonal deviation. We find a positive and significant response for the primary balance and ‘fiscal effort’ to changes in debt-to-GDP. For the fiscal components, we find a positive relationship between debt-to-GDP and general and tax revenues, and a negative relationship with primary spending. We also find evidence of nonlinearities, with countries making larger increases in the primary balance and fiscal effort at higher levels of debt, largely driven by increases in revenues. Higher income countries demonstrate a greater propensity to adjust along the revenue margins, compared to lower income countries. This might be indicative of systemic revenue mobilization challenges facing the latter. The second essay examines the effect of the provision of taxpayer services on filing and payment of the corporate income tax (CIT) and general consumption tax (GCT) for large taxpayers in Jamaica. We use a regression discontinuity design (RDD) that exploits an exogenous jump in the intensity of taxpayer service delivery, which occurs when a taxpayer reaches gross receipts of J$500 million (US$5.7 million) and is selected into the large taxpayer office (LTO). The results indicate null effects for the CIT but positive filing and payment compliance effects for the GCT. The contrasting results for the CIT and GCT may be due to the relatively weaker legal enforcement framework of the former. The results provide suggestive evidence of a complementarity between the strength of the legal enforcement framework of the taxing regime and the provision of taxpayer services. In the third essay we implement public goods messaging experiments to examine the effects on personal income tax (PIT) compliance among self-employed individuals in Jamaica. In the first sub-experiment we examine the effect of the standard public goods message on payment of quarterly PIT obligations. In the second sub-experiment we focus on payment of PIT arrears and expand the message context to include a variant of the standard public goods message – which provides additional information on actual spending on key public goods and services. The compliance outcomes in sub-experiment two relate to established PIT delinquencies, compared to sub-experiment one where there is no legal obligation to comply. We find that the standard public goods message had no effect on compliance with quarterly PIT payments in sub-experiment one. However results from sub-experiment two indicate positive compliance effects from the standard and augmented public goods messages on the probability of making a payment and the amount of PIT arrears paid after nineteen weeks. Point estimates from the standard and augmented public goods messages are not statistically different for any of the outcomes examined; suggesting that additional information on public spending allocations does not matter

The generalized identification of truly interfacial molecules (ITIM) algorithm for nonplanar interfaces

We present a generalized version of the ITIM algorithm for the identification of interfacial molecules, which is able to treat arbitrarily shaped interfaces. The algorithm exploits the similarities between the concept of probe sphere used in ITIM and the circumsphere criterion used in the α-shapes approach, and can be regarded either as a reference-frame independent version of the former, or as an extended version of the latter that includes the atomic excluded volume. The new algorithm is applied to compute the intrinsic orientational order parameters of water around a dodecylphosphocholine and a cholic acid micelle in aqueous environment, and to the identification of solvent-reachable sites in four model structures for soot. The additional algorithm introduced for the calculation of intrinsic density profiles in arbitrary geometries proved to be extremely useful also for planar interfaces, as it allows to solve the paradox of smeared intrinsic profiles far from the interface. © 2013 American Institute of Physics

Estimating the distribution of dynamic invariants: illustrated with an application to human photo-plethysmographic time series

Dynamic invariants are often estimated from experimental time series with the aim of differentiating between different physical states in the underlying system. The most popular schemes for estimating dynamic invariants are capable of estimating confidence intervals, however, such confidence intervals do not reflect variability in the underlying dynamics. We propose a surrogate based method to estimate the expected distribution of values under the null hypothesis that the underlying deterministic dynamics are stationary. We demonstrate the application of this method by considering four recordings of human pulse waveforms in differing physiological states and show that correlation dimension and entropy are insufficient to differentiate between these states. In contrast, algorithmic complexity can clearly differentiate between all four rhythms