System integration report

Several areas that arise from the system integration issue were examined. Intersystem analysis is discussed as it relates to software development, shared data bases and interfaces between TEMPUS and PLAID, shaded graphics rendering systems, object design (BUILD), the TEMPUS animation system, anthropometric lab integration, ongoing TEMPUS support and maintenance, and the impact of UNIX and local workstations on the OSDS environment

Aspects of the study of heat dissipation using models

The Author had been engaged on a model study of the dissipation and the possible recirculation of heated water which was to be discharged from the circulating water system of a steam power station sited on a tidal river, He has described this investigation in a paper "A hydraulic model study of heat dissipation at Kincardine power station". It seemed that further work on the basis of design of such models would be worth while and that the various modes of flow involved might be examined for scale effects in isolation (1). Various aspects of small density difference phenomena which affect free surface hydraulics are reviewed (2), together with the present status of model simulation of these phenomena (3). In describing the circuit of flume and tank which was built for the studies, the general requirements for apparatus for small density difference studies are discussed (4). A thermopile recording system was chosen from the various possible means of indicating the mixing and dilution of introduced water, and the construction (5), use (8) (9) and possible development (13) of the indicating probes is described. This system is thought to be very suitable for any future ad hoc or basic studies. The first mode of flow to be studied was the pure density current exchange flow as found in idealised lock experiments. Some additional information on the overall characteristics of the overflow was obtained, and a scale effect, caused by small variations in surface tension, was noted. This easily obviated phenomena might seriously impair similarity in heat dissipation models. It was found that the requirements for similarity in lock experiments are applicable to internal gravitational advance in open water, and some success was achieved in the simulation of small scale prototype phenomena in very small scale models (7) (9). Vertical mixing was studied using the recording apparatus and the applicability of the general Froude model law was confirmed (8). Modified forms of lock flow are suggested as being pertinent to the spread of less dense water over more dense water, when both are combined as an external gravitational current (1O). The effect of heat losses on model simulation is considered (11) and the economics of heat dissipation are reviewed in some detail (12) After summarising, the possible form of future ad hoc studies is discussed and recommendations made for future basic studies (13). A comprehensive list of references (14), the tables and figures collected at the start of the second volume (15), the test recordings (16) and the notation (17) follow. A subsidiary outfall scour model had been run in conjunction with the main Kincardine model and this also left some uncertainties which were partially elucidated in a series of tests described in an appendix (18). In a further appendix, some minor aspects of the Kincardine investigation are discussed (19)

Cohomological descent theory for a morphism of stacks and for equivariant derived categories

In the paper we answer the following question: for a morphism of varieties (or, more generally, stacks), when the derived category of the base can be recovered from the derived category of the covering variety by means of descent theory? As a corollary, we show that for an action of a reductive group on a scheme, the derived category of equivariant sheaves is equivalent to the category of objects, equipped with an action of the group, in the ordinary derived category.Comment: 28 page

Sqrt{shat}_{min} resurrected

We discuss the use of the variable sqrt{shat}_{min}, which has been proposed in order to measure the hard scale of a multi parton final state event using inclusive quantities only, on a SUSY data sample for a 14 TeV LHC. In its original version, where this variable was proposed on calorimeter level, the direct correlation to the hard scattering scale does not survive when effects from soft physics are taken into account. We here show that when using reconstructed objects instead of calorimeter energy and momenta as input, we manage to actually recover this correlation for the parameter point considered here. We furthermore discuss the effect of including W + jets and t tbar+jets background in our analysis and the use of sqrt{shat}_{min} for the suppression of SM induced background in new physics searches.Comment: 23 pages, 9 figures; v2: 1 figure, several subsections and references as well as new author affiliation added. Corresponds to published versio

Visible Sector Supersymmetry Breaking Revisited

We revisit the possibility of "visible sector" SUSY models: models which are straightforward renormalizable extensions of the Minimal Supersymmetric Standard Model (MSSM), where SUSY is broken at tree level. Models of this type were abandoned twenty years ago due to phenomenological problems, which we review. We then demonstrate that it is possible to construct simple phenomenologically viable visible sector SUSY models. Such models are indeed very constrained, and have some inelegant features. They also have interesting and distinctive phenomenology. Our models predict light gauginos and very heavy squarks and sleptons. The squarks and sleptons may not be observable at the LHC. The LSP is a stable very light gravitino with a significant Higgsino admixture. The NLSP is mostly Bino. The Higgs boson is naturally heavy. Proton decay is sufficently and naturally suppressed, even for a cutoff scale as low as 10^8 GeV. The lightest particle of the O'Raifeartaigh sector (the LOP) is stable, and is an interesting cold dark matter candidate.Comment: 23 pages, 3 figures, LaTe

Geometric CP Violation with Extra Dimensions

We discuss how CP symmetry can be broken geometrically through orbifold projections in hidden extra dimensions in the context of D-brane models for particle unifications. We present a few toy models to illustrate the idea and suggest ways to incorporate this technique in the context of realistic models.Comment: 6 pages, one figure; references updated and a new model adde

Paying to play - the pricing policies of casinos

Wherever gambling activity is permitted it becomes a major competitor for the household budget.*(3) The growth in gambling in the US has become an important social and political issue and the subject of a National Commission, the National Gambling Impact Study Commission (NGISC 1999).*(4) The Commission indicates that more than 86 per cent of all Americans have gambled at least once and that over $50 bn. was spent (amount wagered minus prizes received) on gambling activities in the US in 1998. Lotteries accounted for 52 per cent of this in 1998, casinos 29 per cent and horse racing 7 per cent (NGICS Overview (1999): 72-75). In 1996 the gross revenues of all the organisations providing gambling or gaming opportunities in the US were estimated at$46.07 bn. or just under about 0.09 per cent of all private consumption expenditures for that year

Natural Suppression of Higgsino-Mediated Proton Decay in Supersymmetric SO(10)

In supersymmetric Grand Unified Theories, proton decay mediated by the color--triplet higgsino is generally problematic and requires some fine--tuning of parameters. We present a mechanism which naturally suppresses such dimension 5 operators in the context of SUSY $SO(10)$. The mechanism, which implements natural doublet--triplet splitting using the adjoint higgs, converts these dimension 5 operators effectively into dimension 6. By explicitly computing the higgs spectrum and the resulting threshold uncertainties we show that the successful prediction of $\sin^2\theta_W$ is maintained {\it as a prediction} in this scheme. It is argued that only a weak suppression of the higgsino mediated proton decay is achievable within SUSY $SU(5)$ without fine--tuning, in contrast to a strong suppression in SUSY $SO(10)$.Comment: 39 pages (3 Feynman graphs not included), in Plain LaTeX, BA-93-2

STIS Echelle Observations of the Seyfert Galaxy NGC 4151: Physical Conditions in the Ultraviolet Absorbers

We have examined the physical conditions in intrinsic UV-absorbing gas in the Seyfert galaxy NGC 4151, using echelle spectra obtained with the Space Telescope Imaging Spectrograph (STIS). We confirm the presence of the kinematic components detected in earlier GHRS observations as well as a new broad absorption feature at a radial velocity of -1680 km/s. The UV continuum of NGC 4151 decreased by a factor of 4 over the previous two years, and we argue the changes in the column density of the low ionization absorption lines associated with the broad component at -490 km/s reflect the decrease in the ionizing flux. Most of the strong absorption lines (e.g., N V, C IV, Si IV) from this component are saturated, but show substantial residual flux in their cores, indicating that the absorber does not fully cover the source of emission. Our interpretation is that the unocculted light is due to scattering by free electrons from an extended region, which reflects continuum, emission lines, and absorption lines. We have been able to constrain the densities for the kinematic components based on absorption lines from metastable states of C III and Fe II, and/or the ratios of ground and fine structure lines of O I,C II, and Si II. We have generated a set of photoionization models which match the ionic column densities for each component during the present low flux state and those seen in previous high flux states with the GHRS and STIS, confirming that the absorbers are photoionized and respond to the changes in the continuum flux. We have been able to map the relative radial positions of the absorbers, and find that the gas decreases in density with distance. None of the UV absorbers is of sufficiently large column density or high enough ionization state to account for the X-ray absorption.Comment: 46 pages (Latex), 14 figures (postscript), plus a landscape table (Latex), to appear in the Astrophysical Journa

A new limit on the permanent electric dipole moment of ^{199}Hg

We present the first results of a new search for a permanent electric dipole moment of the ^{199}Hg atom using a UV laser. Our measurements give d(Hg)= - (1.06 +/- 0.49 +/- 0.40) 10^{-28} e cm. We interpret the result as an upper limit |d(Hg)| < 2.1 10^{-28} e cm (95% C.L.), which sets new constraints on theta_{QCD}, chromo-EDMs of the quarks, and CP violation in Supersymmetric models.Comment: 4 pages, 4 figures, submitted to Phys. Rev. Let