Minimal Standard Heterotic String Models

Three generation heterotic-string vacua in the free fermionic formulation gave rise to models with solely the MSSM states in the observable Standard Model charged sector. The relation of these models to Z_2 x Z_2 orbifold compactifications dictates that they produce three pairs of untwisted Higgs multiplets. The reduction to one pair relies on the analysis of supersymmetric flat directions, that give superheavy mass to the dispensable Higgs states. We explore the removal of the extra Higgs representations by using the free fermion boundary conditions and hence directly at the string level, rather than in the effective low energy field theory. We present a general mechanism that achieves this reduction by using asymmetric boundary conditions between the left- and right-moving internal fermions. We incorporate this mechanism in explicit string models containing three twisted generations and a single untwisted Higgs doublet pair. We further demonstrate that an additional effect of the asymmetric boundary conditions is to substantially reduce the supersymmetric moduli space.Comment: 20 pages, LaTeX; added reference

MEDIN Feasibility Study : archiving oil and gas industry site survey data

This report was commissioned by the Marine Environmental and Information Network (MEDIN) to investigate the feasibility of collecting oil and gas industry site surveys conducted on the UKCS (UK Continental Shelf) for archive in the MEDIN DAC (Data Archive Centre) network. The archive of three principle data types is explored; information about legacy site surveys, catalogues of information about data products associated with site surveys and actual site survey data, which may include a survey report and enclosures and/or a selection of data e.g. side-scan or multibeam, sample descriptions and seismic profiles. The merits of the collection of these data types are explored alongside the cost implications, from both an oil and gas industry contractor’s and a marine geoscientist’s perspective, thereby enabling MEDIN to better understand and make decisions as to which data to concentrate on. The principles and proposed procedures for carrying out the collection of these data types are outlined however the practical details of these will require agreement should any decision be made to proceed. At this stage a further thorough detailed scope will be required in order to formulate procedures, qualify numbers, define activities, identify resources and plan timescales. The time period for the collection of legacy site surveys will require consideration i.e. how far back it is feasible to collect this information, and whether requests should be phased to include surveys acquired within predetermined time intervals. The size of the actual site survey data holdings, the storage capacity required to archive these and the amount of work involved in processing this data into useable and useful formats will require review. Some of these issues may need to be considered on a case-by-case basis. The procedures themselves will require regular review dependent on the response i.e. the volume, types and condition of data received

The Application of Minicomputers to Problems of Information Retrieval

Although minicomputers can be used in many types of information retrieval facilities, this paper deals primarily with bibliographic reference re- trieval systems. There are two main reasons why it is attractive to consider using a minicomputer for on-line applications: (1) the relatively low cost and (2) the hardware and software provided.published or submitted for publicatio

OPERA data and The Equivalence Postulate of Quantum Mechanics

An interpretation of the recent results reported by the OPERA collaboration is that neutrinos propagation in vacuum exceeds the speed of light. It has been further been suggested that this interpretation can be attributed to the variation of the particle speed arising from the Relativistic Quantum Hamilton Jacobi Equation. I show that this is in general not the case. I derive an expression for the quantum correction to the instantaneous relativistic velocity in the framework of the relativistic quantum Hamilton-Jacobi equation, which is derived from the equivalence postulate of quantum mechanics. While the quantum correction does indicate deviations from the classical energy--momentum relation, it does not necessarily lead to superluminal speeds. The quantum correction found herein has a non-trivial dependence on the energy and mass of the particle, as well as on distance travelled. I speculate on other possible observational consequences of the equivalence postulate approach.Comment: 8 pages. Standard LaTex. References adde

Book Review of Ignacio De Leon's An Institutional Assessment of Antitrust Policy The Latin American Experience

Book Review of Ignacio De Leon's "An Institutional Assessment of Antitrust Policy The Latin American Experience" (Wolters Kluwer 2009) Reviewed by A.E. RodriguezAntitrust; DeLeon; Rule of Law; Latin American Antitrust;

Soil profiles: the more we see, the more we understand

The aesthetics of soils have fascinated soil scientists in all times. Since the late 1800s soil profile drawings, paintings and photographs have been depicted in hundreds of text books. The first soil profile depictions were simple diagrams illustrating different layers and soil processes. Photographs started to appear in textbooks at the end of the nineteenth century. In the 1950s, several books contained water paintings and from the 1970s onwards text books had colour photographs. Soil profile depictions were merely used to illustrate different orders in a classification system. Since the 1990s, efforts have been made to depict the soil profile in 3D. The depiction of soil profiles follows the understanding of the key properties and processes that have formed a soil