Regularisation of classical self interaction in strings

A general method of regularisation of classical self interaction in strings is extended from the electromagnetic case (for which it was originally developed) to the gravitation case, for which the result can also be represented as a renormalisation.Comment: 4 pages, Latex. Contribution to proceedings of 1997 Cargese A.S.I. ``Strings, branes, and dualities'', ed. L. Baulieu, P. Winde

Autism genes are selectively targeted by environmental pollutants including pesticides, heavy metals, bisphenol A, phthalates and many others in food, cosmetics or household products

The increasing incidence of autism suggests a major environmental influence. Epidemiology has implicated many candidates and genetics many susceptibility genes. Gene/environment interactions in autism were analysed using 206 autism susceptibility genes (ASG's) from the Autworks database to interrogate ∼1 million chemical/gene interactions in the comparative toxicogenomics database. Any bias towards ASG's was statistically determined for each chemical. Many suspect compounds identified in epidemiology, including tetrachlorodibenzodioxin, pesticides, particulate matter, benzo(a)pyrene, heavy metals, valproate, acetaminophen, SSRI's, cocaine, bisphenol A, phthalates, polyhalogenated biphenyls, flame retardants, diesel constituents, terbutaline and oxytocin, inter alia showed a significant degree of bias towards ASG's, as did relevant endogenous agents (retinoids, sex steroids, thyroxine, melatonin, folate, dopamine, serotonin). Numerous other suspected endocrine disruptors (over 100) selectively targeted ASG's including paraquat, atrazine and other pesticides not yet studied in autism and many compounds used in food, cosmetics or household products, including tretinoin, soy phytoestrogens, aspartame, titanium dioxide and sodium fluoride. Autism polymorphisms influence the sensitivity to some of these chemicals and these same genes play an important role in barrier function and control of respiratory cilia sweeping particulate matter from the airways. Pesticides, heavy metals and pollutants also disrupt barrier and/or ciliary function, which is regulated by sex steroids and by bitter/sweet taste receptors. Further epidemiological studies and neurodevelopmental and behavioural research is warranted to determine the relevance of large number of suspect candidates whose addition to the environment, household, food and cosmetics might be fuelling the autism epidemic in a gene-dependent manner

Mapping the Growth of an Arabian Gulf Town: The Case of Doha, Qatar

This paper is based on research undertaken for the Origins of Doha Project. It is a unique attempt to interrogate the construct of the Arab city against rigorously collected evidence and meticulous analysis of historical urban geography. We have found that Doha in its urban layout, physical development, architecture, and pre-oil demographics, combined its disparate cosmopolitan elements into a blend that probably typified the historic Gulf town, simultaneously encapsulating aspects of the generalised “Arab and Islamic town.” We have found strong structural principles at work in both the traditional and the early modern town, many of which correlate strongly with tribal social organisation, although the historic population of Doha was neither overwhelmingly tribal in character nor entirely Arab in origin. Rather, these constituted prevailing ideologies, social structures, and identities in a diverse and cosmopolitan populatio

Use of archival aerial photographs for archaeological research in the Arabian Gulf

A valuable archaeological and historical resource is contained within recently declassified aerial imagery from the UK’s Joint Aerial Reconnaissance Intelligence Centre (JARIC), now held at the National Collection of Aerial Photography in Edinburgh (NCAP). A project at UCL-Qatar has begun to exploit this to acquire and research the historical aerial photography of Qatar and the wider Gulf region. The JARIC collection, comprising perhaps as many as 25 million photographs from British intelligence sources in the twentieth century, mainly from Royal Air Force reconnaissance missions, is known to include large quantities of aerial photography from the Gulf that have never been seen outside intelligence circles, dating from 1939 to 1989. This paper will demonstrate how others may gain access to this valuable resource, not only for the Gulf but for the entire MENA (Middle East and North Africa) region. We will explore the research value of these resources and demonstrate how they enrich our understanding of the area. The archive is likely to be of equal value to archaeologists and historians of other regions

The rise and ruin of a medieval port town: A reconsideration of the development of Julfar

Arabian Archaeology and Epigraphy published by John Wiley & Sons Ltd Julfar was a major port town of the Persian Gulf during the fourteenth and fifteenth centuries AD. A possession of the Hormuzi empire, it was a lucrative source of taxes and pearls, and a port of trade for northern Oman, tapping into maritime trading networks connecting the Middle East with Africa, India, Southeast Asia and China. The site is found north of modern Ras Al-Khaimah, UAE. Julfar Al-Nudud was previously considered to be a late suburb of an urban core, Julfar Al-Mataf, and is located on a creek opposite the latter. However, excavations in 2010 indicated that Al-Nudud was part of the original urban core, which had grown up on either side of the creek. Moreover, re-examination of previous work in Al-Mataf, where a large mosque and fortification were excavated (by British and French teams), shows that the two areas followed different trajectories. Significant occupation in Al-Nudud and southern Al-Mataf (revealed by previous Japanese excavations) ended before the start of the sixteenth century, while use of the mosque and fort in central Al-Mataf continued into the seventeenth century, albeit discontinuously. A revised concordance of the phases derived from the work of various archaeological teams is therefore proposed

Anisotropic P‐wave attenuation measured from a multi‐azimuth surface seismic reflection survey

A system of aligned vertical fractures produces azimuthal variations in stacking velocity and amplitude variation with offset, characteristics often reported in seismic reflection data for hydrocarbon exploration. Studies of associated attenuation anisotropy have been mostly theoretical, laboratory or vertical seismic profiling based. We used an 11 common‐midpoint‐long portion of each of four marine surface‐seismic reflection profiles, intersecting each other at 45° within circa 100 m of a common location, to measure the azimuthal variation of effective attenuation, Q−1eff and stacking velocity, in a shallow interval, about 100 m thick, in which consistently orientated vertical fracturing was expected due to an underlying salt diapirism. We found qualitative and quantitative consistency between the azimuthal variation in the attenuation and stacking velocity, and published amplitude variation with offset results. The 135° azimuth line showed the least apparent attenuation (1000 Q−1eff= 16 ± 7) and the fastest stacking velocity, hence we infer it to be closest to the fracture trend: the orthogonal 45° line showed the most apparent attenuation (1000Q−1eff= 52 ± 15) and slowest stacking velocity. The variation of Q−1eff with azimuth φ is well fitted by 1000Q−1eff= 34 − 18cos[2(φ+40°)] giving a fracture direction of 140 ± 23° (±1SD, derived from ‘bootstrapping’ fits to all 114 combinations of individual common‐midpoint/azimuth measurements), compared to 134 ± 47° from published amplitude variation with offset data. The effects of short‐window spectral estimation and choices of spectral ratio bandwidth and offset ranges used in attenuation analysis, individually give uncertainties of up to ±13° in fracture direction. This magnitude of azimuthal variation can be produced by credible crack geometries (e.g., dry cracks, radius 6.5 m, aspect ratio 3 × 10−5, crack density 0.2) but we do not claim these to be the actual properties of the interval studied, because of the lack of well control (and its consequences for the choice of theoretical model and host rock physical properties) and the small number of azimuths available here

Ultraviolet singularities in classical brane theory

We construct for the first time an energy-momentum tensor for the electromagnetic field of a p-brane in arbitrary dimensions, entailing finite energy-momentum integrals. The construction relies on distribution theory and is based on a Lorentz-invariant regularization, followed by the subtraction of divergent and finite counterterms supported on the brane. The resulting energy-momentum tensor turns out to be uniquely determined. We perform the construction explicitly for a generic flat brane. For a brane in arbitrary motion our approach provides a new paradigm for the derivation of the, otherwise divergent, self-force of the brane. The so derived self-force is automatically finite and guarantees, by construction, energy-momentum conservation.Comment: 41 pages, no figures, minor change