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Search for Leptoquarks and 4th generation Quarks at CDF
At Run II of the Fermilab Tevatron, the CDF experiment provides good sensitivity for either discovery or setting limits on 1st and 2nd generation scalar, or 3rd generation vector, leptoquark pair-production, where each leptoquark decays to a charged lepton and a quark with variable branching ratio {beta}, or decays to a neutrino and quark with branching ratio (1 - {beta}). By comparison with the theoretical expectations, we set mass limits, in some cases as a function of {beta}. New quark generations are predicted in various scenarios for physics beyond the Standard Model. Here we include results from searches for t' and for b' production. The t' is searched for in decays to W{sub q} and the b' in decays to Z{sup 0}b. All of these measurements are based on an integrated luminosity of 200-350 pb{sup -1}, taken at {radical}s = 1.96 TeV
A Steady State Approach to a Network Externality Market With Switching Costs
We study duopoly pricing in the market for mobile phone service, which
features network externalities, switching costs, and consumer
heterogeneity. We introduce a steady state approach that enables a
tractable analysis without endgame effects. The model can generate a
variety of testable predictions, of which we focus on the comparative
statics with respect to switching costs. Using data on the mobile phone
service industries in 52 countries, we use the variation in market
structure at the time switching costs were suddenly reduced by the
regulatory imposition of mobile number portability (MNP). Firms that
grew more rapidly prior to MNP respond to MNP by pricing more
aggressively; firms facing large competitors respond less aggressively.
Exploration of the model and its implications is an object of ongoing research
The Gamma-ray Albedo of the Moon
We use the GEANT4 Monte Carlo framework to calculate the gamma-ray albedo of
the Moon due to interactions of cosmic ray (CR) nuclei with moon rock. Our
calculation of the albedo spectrum agrees with the EGRET data. We show that the
spectrum of gamma rays from the Moon is very steep with an effective cutoff
around 3-4 GeV (600 MeV for the inner part of the Moon disk) and exhibits a
narrow pion-decay line at 67.5 MeV, perhaps unique in astrophysics. Apart from
other astrophysical sources, the albedo spectrum of the Moon is well
understood, including its absolute normalisation; this makes it a useful
"standard candle" for gamma-ray telescopes. The steep albedo spectrum also
provides a unique opportunity for energy calibration of gamma-ray telescopes,
such as the forthcoming Gamma Ray Large Area Space Telescope (GLAST). Since the
albedo flux depends on the incident CR spectrum which changes over the solar
cycle, it is possible to monitor the CR spectrum using the albedo gamma-ray
flux. Simultaneous measurements of CR proton and helium spectra by the Payload
for Antimatter-Matter Exploration and Light-nuclei Astrophysics (PAMELA), and
observations of the albedo gamma rays by the GLAST Large Area Telescope (LAT),
can be used to test the model predictions and will enable the LAT to monitor
the CR spectrum near the Earth beyond the lifetime of the PAMELA.Comment: 6 pages, 4 figures, emulateapj.cls; to appear in the Astrophysical
Journa
Anomaly-Free Sets of Fermions
We present new techniques for finding anomaly-free sets of fermions. Although
the anomaly cancellation conditions typically include cubic equations with
integer variables that cannot be solved in general, we prove by construction
that any chiral set of fermions can be embedded in a larger set of fermions
which is chiral and anomaly-free. Applying these techniques to extensions of
the Standard Model, we find anomaly-free models that have arbitrary quark and
lepton charges under an additional U(1) gauge group.Comment: 21 (+1) page
Isolating Triggered Star Formation
Galaxy pairs provide a potentially powerful means of studying triggered star
formation from galaxy interactions. We use a large cosmological N-body
simulation coupled with a well-tested semi-analytic substructure model to
demonstrate that the majority of galaxies in close pairs reside within cluster
or group-size halos and therefore represent a biased population, poorly suited
for direct comparison to ``field'' galaxies. Thus, the frequent observation
that some types of galaxies in pairs have redder colors than ``field'' galaxies
is primarily a selection effect. We select galaxy pairs that are isolated in
their dark matter halos with respect to other massive subhalos (N=2 halos) and
a control sample of isolated galaxies (N=1 halos) for comparison. We then apply
these selection criteria to a volume-limited subset of the 2dF Galaxy Redshift
Survey with M_Bj <= -19 and obtain the first clean measure of the typical
fraction of galaxies affected by triggered star formation and the average
elevation in the star formation rate. We find that 24% (30.5%) of these L^\star
and sub-L^{\star} galaxies in isolated 50 (30) kpc/h pairs exhibit star
formation that is boosted by a factor of >~ 5 above their average past value,
while only 10% of isolated galaxies in the control sample show this level of
enhancement. Thus, 14% (20 %) of the galaxies in these close pairs show clear
triggered star formation. The isolation criteria we develop provide a means to
constrain star formation and feedback prescriptions in hydrodynamic simulations
and a very general method of understanding the importance of triggered star
formation in a cosmological context. (Abridged.)Comment: 12 pages, 10 figures, emulateapj format, accepted by Ap
Constitutional Officers, Agencies, Boards and Commissions in California State Government, 1849-1975
This paper is designed primarily to present data on the formal organizational history of governmental units created by statute or constitutional provision by California state government since 1849
Monte Carlo Comparisons to a Cryogenic Dark Matter Search Detector with low Transition-Edge-Sensor Transition Temperature
We present results on phonon quasidiffusion and Transition Edge Sensor (TES)
studies in a large, 3 inch diameter, 1 inch thick [100] high purity germanium
crystal, cooled to 50 mK in the vacuum of a dilution refrigerator, and exposed
with 59.5 keV gamma-rays from an Am-241 calibration source. We compare
calibration data with results from a Monte Carlo which includes phonon
quasidiffusion and the generation of phonons created by charge carriers as they
are drifted across the detector by ionization readout channels. The phonon
energy is then parsed into TES based phonon readout channels and input into a
TES simulator
Age of Sexual Debut and Patterns of Sexual Behaviour in Two Local Government Areas in Southern Nigeria
The study examines the age of sexual debut and patterns of sexual behavior in Ugep, Cross River State, and Badeku and Olunloyo in Oyo State. A survey of households and individuals was conducted in the three communities; qualitative data were also collected through in-depth interviews and focus group discussion. The median age of first sex among never-married males and females were 17 years and 18 years respectively; more than one in five adolescents have had sex before age 16. Nevermarried males and females initiated sex earlier than ever-married, older respondents. That 14 percent of married men keep other sexual partners besides their wives is indicative of substantial extramarital relationship; also 12 percent of never-married male respondents with regular sex partners have other sexual partners. Condom use is fairly high, especially in sexual relations involving non-regular partners. The higher likelihood of alcohol use in sexual liaison with non-regular sex partners is suggestive of high prevalence of transactional sex and spontaneous or unplanned sex under the influence of alcohol, with their implications for the spread of HIV and AIDS. The study underscores the need for adolescent sexual and reproductive health education and behaviour change communication among all segments of the population and inculcation of values less favourable for the spreadof sexually transmitted infection.(Afr J Reprod Health 2012; 16[4]: 81-94)
Standard Anatomical and Visual Space for the Mouse Retina: Computational Reconstruction and Transformation of Flattened Retinae with the Retistruct Package
The concept of topographic mapping is central to the understanding of the visual system at many levels, from the developmental to the computational. It is important to be able to relate different coordinate systems, e.g. maps of the visual field and maps of the retina. Retinal maps are frequently based on flat-mount preparations. These use dissection and relaxing cuts to render the quasi-spherical retina into a 2D preparation. The variable nature of relaxing cuts and associated tears limits quantitative cross-animal comparisons. We present an algorithm, "Retistruct," that reconstructs retinal flat-mounts by mapping them into a standard, spherical retinal space. This is achieved by: stitching the marked-up cuts of the flat-mount outline; dividing the stitched outline into a mesh whose vertices then are mapped onto a curtailed sphere; and finally moving the vertices so as to minimise a physically-inspired deformation energy function. Our validation studies indicate that the algorithm can estimate the position of a point on the intact adult retina to within 8° of arc (3.6% of nasotemporal axis). The coordinates in reconstructed retinae can be transformed to visuotopic coordinates. Retistruct is used to investigate the organisation of the adult mouse visual system. We orient the retina relative to the nictitating membrane and compare this to eye muscle insertions. To align the retinotopic and visuotopic coordinate systems in the mouse, we utilised the geometry of binocular vision. In standard retinal space, the composite decussation line for the uncrossed retinal projection is located 64° away from the retinal pole. Projecting anatomically defined uncrossed retinal projections into visual space gives binocular congruence if the optical axis of the mouse eye is oriented at 64° azimuth and 22° elevation, in concordance with previous results. Moreover, using these coordinates, the dorsoventral boundary for S-opsin expressing cones closely matches the horizontal meridian
Machine learning enabled Raman amplifiers
Ultra-wideband (UWB) optical communication systems, envision to operate in O+E+S+C+l band, are a viable solution to cope with the networkâs exponential traffic growth [1] . One of the main challenges to provide beyond C-band transmission is a lack of optical amplifiers. Since the erbium-doped fiber amplifiers (EDFAs) are limited to C and L bands only, new technologies will have to be explored to cover the remaining bands. Some examples of amplifiers able to provide amplification beyond Câband are: bismuth doped fibre amplifiers (BDFA) [2] , semiconductor optical amplifiers, (SOAs) [3] and Raman amplifiers (RAs) [4] . Compared to the solutions based on BDFA and SOA, optical amplifiers based RAs offer a higher degree of commercial maturity [5] . Most importantly, RA amplifiers can provide gain in any band provided a proper allocation of pump powers and wavelength
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