A Study of the LEP and SLD Measurements of AbA_b

A systematic study is made of the data dependence of the parameter $A_{\rm{b}}$, that, since 1995, has shown a deviation from the Standard Model prediction of between 2.4 and 3.1 standard deviations. Issues addressed include: the effect of particular measurements, values found by individual experiments, LEP/SLD comparison, and the treatment of systematic errors. The effect, currently at the 2.4$\sigma$ level, is found to vary in the range from 1.7$\sigma$ to 2.9$\sigma$ by excluding marginal or particularly sensitive data. Since essentially the full LEP and SLD Z decay data sets are now analysed the meaning of the deviation, (new physics, or marginal statistical fluctuation) is unlikely to be given by the present generation of colliders.Comment: 15 pages 7 figures 7 table

The Underlying Event in Hard Scattering Processes

We study the behavior of the "underlying event" in hard scattering proton-antiproton collisions at 1.8 TeV and compare with the QCD Monte-Carlo models. The "underlying event" is everything except the two outgoing hard scattered "jets" and receives contributions from the "beam-beam remnants" plus initial and final-state radiation. The data indicate that neither ISAJET or HERWIG produce enough charged particles (with PT > 0.5 GeV/c) from the "beam-beam remnant" component and that ISAJET produces too many charged particles from initial-state radiation. PYTHIA which uses multiple parton scattering to enhance the "underlying event" does the best job describing the data.Comment: RevTex4, 18 pages, 29 figures, contribution to Snowmass 200

DIVERSITY OF RURAL PLACES - TEXAS

Labor and Human Capital,

Compton Polarimetry at a TEV Collider

An electron beam polarization of 80% or greater will be a key feature of a 1 TeV Linear Collider. Accurate measurements of the beam polarization will therefore be needed. We discuss design considerations and capabilities for a Compton-scattering polarimeter located in the extraction line from the Interaction Point. Polarization measurements with 1% accuracy taken parasitic to collision data look feasible, but detailed simulations are needed. Polarimeter design issues are similar for both electron-positron and electron-electron collider modes, though beam disruption creates more difficulties for the electron-electron mode.Comment: 7 pages, 5 figure

Using Collider Event Topology in the Search for the Six-Jet Decay of Top Quark-Antiquark Pairs

We investigate the use of the event topology as a tool in the search for the six-jet decay of top-pair production in proton-antiproton collisions at 1.8 TeV. Modified Fox-Wolfram "shape" variables, H_i, are employed to help distinguish the top-pair signal from the ordinary QCD multi-jet background. The H's can be constructed directly from the calorimeter cells or from jets. Events are required to lie in a region of H-space defined by L_i < H_i < R_i for i=1,...,,6, where the left, L_i, and right, R_i, cuts are determined by a genetic algorithm (GA) procedure to maximize the signal over the square root of the background. We are able to reduce the background over the signal to less than a factor of 100 using purely topological methods without using jet multiplicity cuts and without the aid of b-quark tagging.Comment: LaTeX, 19 pages, 13 figure

Targeting chromatin aging - the epigenetic impact of longevity-associated interventions

A rapidly growing body of evidence has shown that chromatin undergoes radical alterations as an organism ages, but how these changes relate to aging itself is an open question. It is likely that these processes contribute to genomic instability and loss of transcriptional fidelity, which in turn drives deleterious age-related phenotypes. Interventions associated with increased healthspan and longevity such as reduced insulin/IGF signalling (IIS), inhibition of mTOR and energy depletion resulting in SIRT1/AMPK activation, all have beneficial effects which ameliorate multiple facets of age-associated decline. The impact of these interventions on the epigenome is less certain. In this review we highlight the potential of these interventions to act directly upon the epigenome and promote a youthful chromatin landscape, maintaining genetic and transcriptional memory throughout the lifecourse. We propose that this is a fundamental mechanism through which these interventions are able to curtail the incidence of age-related disease. By revisiting these well characterised interventions, we may be able to identify targetable effectors of chromatin function and use this knowledge to enhance healthspan and longevity in human populations through the measured application of dietary and small molecule interventions

Space shuttle: Longitudinal and lateral directional stability characteristics of the MDAC high cross range delta wing orbiter

Low speed wind tunnel tests on longitudinal and lateral stability of high cross range delta wing space shuttle

Facebook surveillance of former romantic partners: Associations with post-breakup recovery and personal growth

Copyright @ 2012 Mary Ann Liebert, Inc.This article has been made available through the Brunel Open Access Publishing Fund.Previous research has found that continuing offline contact with an ex-romantic partner following a breakup may disrupt emotional recovery. The present study examined whether continuing online contact with an ex-partner through remaining Facebook friends and/or engaging in surveillance of the ex-partner's Facebook page inhibited postbreakup adjustment and growth above and beyond offline contact. Analysis of the data provided by 464 participants revealed that Facebook surveillance was associated with greater current distress over the breakup, more negative feelings, sexual desire, and longing for the ex-partner, and lower personal growth. Participants who remained Facebook friends with the ex-partner, relative to those who did not remain Facebook friends, reported less negative feelings, sexual desire, and longing for the former partner, but lower personal growth. All of these results emerged after controlling for offline contact, personality traits, and characteristics of the former relationship and breakup that tend to predict postbreakup adjustment. Overall, these findings suggest that exposure to an ex-partner through Facebook may obstruct the process of healing and moving on from a past relationship

The effect of a concentration-dependent viscosity on\ud particle transport in a channel flow with porous walls

We analyse the transport of a dilute suspension of particles through a channel with porous walls accounting for the concentration dependence of the viscosity. Two cases of leakage flow of fluid through the porous channel walls are studied: (i) constant flux, and (ii) dependent on the pressure drop across the wall. The effect of mixing the suspension first compared with point injection is examined by considering inlet concentration distributions of different widths. We find that a pessimal distribution width exists that maximizes the required hydrodynamic pressure for a constant fluid influx. We also show that the presence of an osmotic pressure may lead to fluid being sucked into the channel. We consider how the application of an external hydrodynamic pressure affects this observation and discuss the significance of our results for water filtration

Death of Stellar Baryonic Dark Matter

The nature of the dark matter in the haloes of galaxies is one of the outstanding questions in astrophysics. All stellar candidates, until recently thought to be likely baryonic contributions to the Halo of our Galaxy, are shown to be ruled out. Faint stars and brown dwarfs are found to constitute only a few percent of the mass of the Galaxy. Stellar remnants, including white dwarfs and neutron stars, are shown to be very constrained as well. High energy gamma-rays observed in HEGRA data place the strongest constraints, $\Omega_{WD} < 3 \times 10^{-3} h^{-1}$, where $h$ is the Hubble constant in units of 100 km s$^{-1}$ Mpc$^{-1}$. Hence one is left with several unanswered questions: 1) What are MACHOs seen in microlensing surveys? 2) What is the dark matter in our Galaxy? Indeed a nonbaryonic component in the Halo seems to be required.Comment: 6 pages ps fil