Z_2 x Z_2 Heterotic Orbifold Models of Non Factorisable Six Dimensional Toroidal Manifolds

We discuss heterotic strings on Z_2 x Z_2 orbifolds of non factorisable six-tori. Although the number of fixed tori is reduced as compared to the factorisable case, Wilson lines are still needed for the construction of three generation models. An essential new feature is the straightforward appearance of three generation models with one generation per twisted sector. We illustrate our general arguments for the occurrence of that property by an explicit example. Our findings give further support for the conjecture that four dimensional heterotic strings formulated at the free fermionic point are related to Z_2 x Z_2 orbifolds.Comment: 33 pages, LaTeX; discussion of modular invariance added in section four; added references; to be published in JHE

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

Quantum theory and the mind brain relation

In reductionist biology, mental states are brain states and the brain obeys the laws of a physical world existing independently of and prior to minds. This account is invalidated if the physical laws themselves involve essential reference to mental states.. The quantum theory has usually been presented in a form making such reference. .To remove the need for this, the first step is to accept that quantum theory applies only to fields and to entities embedded in fields. Ehrenfest's theorem then shows how systems obeying Newtonian mechanics, including objects of everyday life, appear as persistent patterns showing none of the indeterminacy associated with features of the underlying field. The theorems of Gleason, Kocken and Specker demand that the quantum theory should leave a degree of indeterminacy in the pattern of the fields it describes. Any interaction of a quantum system with its environment therefore requires a definite selection of a unique pattern of behaviour within the range of indeterminacy. Such interaction is continuous, and there is no role for a mental state in this selection. It would be consistent with the formalism of quantum theory if a localised interaction in a system caused an instantaneous removal of indeterminacy over an arbitrarily large volume, in apparent conflict with the special theory of relativity. This conflict is not removed by any appeal to the effects of mental states.. However, a consistent interpretation of quantum systems as fields throws doubt on the claim that the event correlations in the experiments of Aspect and his colllaborators are evidence of causal propagation at speeds greater than that of light

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

Consistency and composite numeraires in joint production input-output analysis; an application of ideas of T.L. Saaty

In this paper we show that Saaty consistency analysis can be applied to problems in joint production input-output analysis. We discuss problems of merging use and make matrices into one matrix of input coefficients, either of commodity × commodity or industry × industry type. The Saaty approach we propose is shown to point to the U.N.'s commodity-technology method as the most appropriate among a number of competing constructs. Some evidence regarding the empirical relevance of the U.N.'s method is discussed

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