Borders, Common Currencies, Trade, and Welfare: What Can We Learn from the Evidence?

Recent evidence indicates that the intensity of economic exchange within and across borders is significantly different: linkages are much tighter within, than among, nation-states. These findings, however, do not necessarily imply that borders and separate national currencies represent significant barriers to trade that should be removed, since the evidence is also consistent with the alternative hypothesis, that domestic exchange is more efficient because domestic producers are better able to satisfy the requirements of local consumers, owing to common tastes and institutions and the existence of local information and social networks. Focusing primarily on trade linkages within and between Canada and the United States, the authors review the evidence on the extent to which national borders lessen the intensity of international economic linkages, primarily trade in goods and services, and the effects on domestic welfare. They also examine the evidence on the impact of common currencies on trade and welfare. They determine that, since the empirical models employed to date in this research cannot distinguish between alternative explanations of the evidence, it is not yet possible to draw firm conclusions for policy-making.

Quantum singularity of Levi-Civita spacetimes

Quantum singularities in general relativistic spacetimes are determined by the behavior of quantum test particles. A static spacetime is quantum mechanically singular if the spatial portion of the wave operator is not essentially self-adjoint. Here Weyl's limit point-limit circle criterion is used to determine whether a wave operator is essentially self-adjoint. This test is then applied to scalar wave packets in Levi-Civita spacetimes to help elucidate the physical properties of the spacetimes in terms of their metric parameters

Aged riverine particulate organic carbon in four UK catchments

The riverine transport of particulate organic matter (POM) is a significant flux in the carbon cycle, and affects macronutrients and contaminants. We used radiocarbon to characterise POM in 9 rivers of four UK catchments (Avon, Conwy, Dee, Ribble) over a one-year period. High-discharge samples were collected on three or four occasions at each site. Suspended particulate matter (SPM) was obtained by centrifugation, and the samples were analysed for carbon isotopes. Concentrations of SPM and SPM organic carbon (OC) contents were also determined, and were found to have a significant negative correlation. For the 7 rivers draining predominantly rural catchments, PO14C values, expressed as percent modern carbon absolute (pMC), varied little among samplings at each site, and there was no significant difference in the average values among the sites. The overall average PO14C value for all 7 sites of 91.2 pMC corresponded to an average age of 680 14C years, but this value arises from the mixing of differently-aged components, and therefore significant amounts of organic matter older than the average value are present in the samples. Although topsoil erosion is probably the major source of the riverine POM, the average PO14C value is appreciably lower than topsoil values (which are typically 100 pMC). This is most likely explained by inputs of older subsoil OC from bank erosion, or the preferential loss of high-14C topsoil organic matter by mineralisation during riverine transport. The significantly lower average PO14C of samples from the River Calder (76.6 pMC), can be ascribed to components containing little or no radiocarbon, derived either from industrial sources or historical coal mining, and this effect is also seen in the River Ribble, downstream of its confluence with the Calder. At the global scale, the results significantly expand available information for PO14C in rivers draining catchments with low erosion rates

The Effect of Sources on the Inner Horizon of Black Holes

Single pulse of null dust and colliding null dusts both transform a regular horizon into a space-like singularity in the space of colliding waves. The local isometry between such space-times and black holes extrapolates these results to the realm of black holes. However, inclusion of particular scalar fields instead of null dusts creates null singularities rather than space-like ones on the inner horizons of black holes.Comment: Final version to appear in PR

Chlamydia protein Pgp3 studied at high resolution in a new crystal form

The protein Pgp3 is implicated in the sexually transmitted disease chlamydia and comprises an extended complex arrangement of a C terminal domain (CTD) and an N terminal domain (NTD), each linked by a triple helix coiled coil (THCC). We report the X-ray crystal structure of Pgp3 from a LGV1 strain at the highest X-ray diffraction resolution obtained to date for the full protein. The protein was crystallised using a high KBr salt concentration, which resulted in a new crystal form with relatively low solvent content diffracting to a resolution of 1.98 Å. We describe the 3D structure of this new crystal form, compare it with other crystal forms, describe the KBr salt binding sites and the relevance to chlamydia isolates from around the globe. The crystal packing is apparently driven by the CTDs. Since the three fold axes of the THCC and NTD are not collinear with a CTD’s three fold axis this naturally leads to a disorder in the THCC and the portion of the NTD not directly interacting with the CTD via crystal packing. The key avenue to resolve these oddities of the crystal structure analysis was a complete new analysis in space group P1 and determining the space group as P212121. This space group assignment was the one originally determined from the diffraction pattern but perhaps complicated by a translational non crystallographic symmetry. We found this crystal structure of a three domain multi macromolecular complex, with two misaligned three fold axes, a unique challenge, something not encountered before. A specific intermolecular interaction, possibly of functional significance in receptor binding in chlamydia, we suggest might allow design of a new chemotherapeutic agent against chlamydia

Land use influences on acidification and recovery of freshwaters in Galloway, south-west Scotland

International audienceThe long term response of surface waters to changes in sulphur deposition and afforestation is investigated for three upland river systems in the Galloway region of south-west Scotland. From 1984-1999, these rivers exhibited a statistically significant decline in non-marine sulphate concentrations in response to reduced acid deposition. This reduction in non-marine sulphate was, however, insufficient to induce a pH recovery over the period. A statistically significant increase in river pH was observed between 1956-1970 (0.05 yr-1) when subsidised agricultural lime payments were at a maximum. In 1976, this subsidy ceased and surface waters have progressively acidified. In addition, climatic change is found to influence long-term trends in pH. Mean annual pH was greatest during a dry period between 1969-1973 when total annual discharge was low. Thereafter, pH declined gradually in response to higher rainfall and increased total annual discharge. Overall, surface waters draining the afforested catchments of the Rivers Cree and Bladnoch are more acid than those draining the moorland catchment of the Luce. These results indicate that in afforested catchments, current reductions in sulphur emissions have not led to an observed improvement in the acid status of surface waters. Forestry, therefore, represents a confounding factor with regard to chemical recovery from acidification in this region. Keywords: acidification, afforestation, deposition, rivers, lochs, non-marine sulphate, p

Mining metrics for buried treasure

The same but different: That might describe two metrics. On the surface CLASSI may show two metrics are locally equivalent, but buried beneath one may be a wealth of further structure. This was beautifully described in a paper by M.A.H. MacCallum in 1998. Here I will illustrate the effect with two flat metrics -- one describing ordinary Minkowski spacetime and the other describing a three-parameter family of Gal'tsov-Letelier-Tod spacetimes. I will dig out the beautiful hidden classical singularity structure of the latter (a structure first noticed by Tod in 1994) and then show how quantum considerations can illuminate the riches. I will then discuss how quantum structure can help us understand classical singularities and metric parameters in a variety of exact solutions mined from the Exact Solutions book.Comment: 16 pages, no figures, minor grammatical changes, submitted to Proceedings of the Malcolm@60 Conference (London, July 2004

Energy Production in the Formation of a Finite Thickness Cosmic String

The classical electromagnetic modes outside a long, straight, superconducting cosmic string are calculated, assuming the string to be surrounded by a superconducting cylindric surface of radius R. Thereafter, by use of a Bogoliubov-type argument, the electromagnetic energy W produced per unit length in the lowest two modes is calculated when the string is formed "suddenly". The essential new element in the present analysis as compared with prior work of Parker [Phys. Rev. Lett. {\bf 59}, 1369 (1987)] and Brevik and Toverud [Phys. Rev. D {\bf 51}, 691 (1995)], is that the radius {\it a} of the string is assumed finite, thus necessitating Neumann functions to be included in the fundamental modes. We find that the theory is changed significantly: W is now strongly concentrated in the lowest mode $(m,s)=(0,1)$, whereas the proportionality $W \propto (G\mu /t)^2$ that is characteristic for zero-width strings is found in the next mode (1,1). Here G is the gravitational constant, $\mu$ the string mass per unit length, and t the GUT time.Comment: 20 pages, LaTeX, no figure