PC1643+4631A,B: The Lyman-Alpha Forest at the Edge of Coherence

This is the first measurement and detection of coherence in the intergalactic medium (IGM) at substantially high redshift (z~3.8) and on large physical scales (~2.5 h^-1 Mpc). We perform the measurement by presenting new observations from Keck LRIS of the high redshift quasar pair PC 1643+4631A, B and their Ly-alpha absorber coincidences. This experiment extends multiple sightline quasar absorber studies to higher redshift, higher opacity, larger transverse separation, and into a regime where coherence across the IGM becomes weak and difficult to detect. We fit 222 discrete Ly-alpha absorbers to sightline A and 211 to sightline B. Relative to a Monte Carlo pairing test (using symmetric, nearest neighbor matching) the data exhibit a 4sigma excess of pairs at low velocity splitting (<150 km/s), thus detecting coherence on transverse scales of ~2.5 h^-1 Mpc. We use spectra extracted from an SPH simulation to analyze symmetric pair matching, transmission distributions as a function of redshift and compute zero-lag cross-correlations to compare with the quasar pair data. The simulations agree with the data with the same strength (~4sigma) at similarly low velocity splitting above random chance pairings. In cross-correlation tests, the simulations agree when the mean flux (as a function of redshift) is assumed to follow the prescription given by Kirkman et al. (2005). While the detection of flux correlation (measured through coincident absorbers and cross-correlation amplitude) is only marginally significant, the agreement between data and simulations is encouraging for future work in which even better quality data will provide the best insight into the overarching structure of the IGM and its understanding as shown by SPH simulations.Comment: 15 pages, 11 figures; accepted for publication in Astronomical Journa

COMMUNICATION APPREHENSION AFFECTS PERFORMANCE

The research outlined in this work is founded on the notion that every individual is affected by a degree of Communication Apprehension (CA), and the level of apprehension individuals experience has the potential to either positively or negatively influence their ability to perform in the workplace. Specifically, this research examines the relationships between the constructs of communication apprehension, performance anxiety, organizational role, and employee performance. The results found that individuals in sales-related professional roles have a significantly lower level of overall CA than the general population; individuals in customer-facing roles displayed no difference in CA level based on sex, organizational level, or region of the country; and there is no correlation between overall CA level and sales performance. The findings offer practical implications for those who recruit and manage sales professionals

Helicity amplitudes and electromagnetic decays of strange baryon resonances

We present results for the helicity amplitudes of the lowest-lying hyperon resonances Y*, computed within the framework of the Bonn constituent-quark model, which is based on the Bethe-Salpeter approach. The seven parameters entering the model are fitted against the best known baryon masses. Accordingly, the results for the helicity amplitudes are genuine predictions. Some hyperon resonances are seen to couple more strongly to a virtual photon with finite Q^2 than to a real photon. Other Y*'s, such as the S_{01}(1670) Lambda resonance or the S_{11}(1620) Sigma resonance, have large electromagnetic decay widths and couple very strongly to real photons. The negatively-charged and neutral members of a Sigma* triplet may couple only moderately to the Sigma(1193), while the positively-charged member of the same Sigma* triplet displays a relatively large coupling to the Sigma^+(1193) state. This illustrates the necessity of investigating all isospin channels in order to obtain a complete picture of the hyperon spectrum.Comment: 4 pages, 1 figure, 1 table, Proceedings of the Conference "International Workshop on the Physics of Excited Baryons NSTAR 05", Tallahassee, Florida (USA), Oct. 2005, contributed tal

Ocean feature recognition using genetic algorithms with fuzzy fitness functions (GA/F3)

A model for genetic algorithms with semantic nets is derived for which the relationships between concepts is depicted as a semantic net. An organism represents the manner in which objects in a scene are attached to concepts in the net. Predicates between object pairs are continuous valued truth functions in the form of an inverse exponential function (e sub beta lxl). 1:n relationships are combined via the fuzzy OR (Max (...)). Finally, predicates between pairs of concepts are resolved by taking the average of the combined predicate values of the objects attached to the concept at the tail of the arc representing the predicate in the semantic net. The method is illustrated by applying it to the identification of oceanic features in the North Atlantic

Probing Split Supersymmetry with Cosmic Rays

A striking aspect of the recently proposed split supersymmetry is the existence of heavy gluinos which are metastable because of the very heavy squarks which mediate their decay. In this paper we correlate the expected flux of these particles with the accompanying neutrino flux produced in inelastic $pp$ collisions in distant astrophysical sources. We show that an event rate at the Pierre Auger Observatory of approximately 1 yr$^{-1}$ for gluino masses of about 500 GeV is consistent with existing limits on neutrino fluxes. The extremely low inelasticity of the gluino-containing hadrons in their collisions with the air molecules makes possible a distinct characterization of the showers induced in the atmosphere. Should such anomalous events be observed, we show that their cosmogenic origin, in concert with the requirement that they reach the Earth before decay, leads to a lower bound on their proper lifetime of the order of 100 years, and consequently, to a lower bound on the scale of supersymmetry breaking, $\Lambda_{\rm SUSY} >2.6 \times 10^{11}$ GeV. Obtaining such a bound is not possible in collider experiments.Comment: Version to be published in Phys. Rev.

Instanton Effects in the Decay of Scalar Mesons

We show that instanton effects may play a crucial role in the decay of scalar mesons into two pseudoscalars. Particularly the branching ratios of two meson decays of the $f_0(1500)$, which is considered as a glue-ball candidate, are then compatible with an ordinary $q \bar{q}$-structure of this resonance and a small positive SU(3) mixing angle, close to a result recently calculated with the same instanton-induced force.Comment: 9 pages, uuencoded latex including two figure

Feasibility of Establishing Small Livestock Slaughter Plants in North Dakota

Agribusiness,

Comparing Simulations and Observations of the Lyman-Alpha Forest I. Methodology

We describe techniques for comparing spectra extracted from cosmological simulations and observational data, using the same methodology to link Lyman-alpha properties derived from the simulations with properties derived from observational data. The eventual goal is to measure the coherence or clustering properties of Lyman-alpha absorbers using observations of quasar pairs and groups. We quantify the systematic underestimate in opacity that is inherent in the continuum fitting process of observed spectra over a range of resolution and signal-to-noise ratio. We present an automated process for detecting and selecting absorption features over the range of resolution and signal-to-noise of typical observational data on the Lyman-alpha "forest". Using these techniques, we detect coherence over transverse scales out to 500 h^{-1}_{50} kpc in spectra extracted from a cosmological simulation at z = 2.Comment: 52 pages, includes 14 figures, to appear in ApJ v566 Feb 200