2,397 research outputs found
Glueball mass measurements from improved staggered fermion simulations
We present the first 2+1 flavour spectrum measurements of glueball states
using high statistics simulations with improved staggered fermions. We find a
spectrum consistent with quenched measurements of scalar, pseudoscalar
andtensor glueball states. The measurements were made using 5000 configurations
at a lattice spacing of 0.123 fm and pion mass of 280 MeV and 3000
configurations at 0.092 fm with a pion mass of 360 MeV. We see some evidence of
coupling to 2 pion states. We compare our results with the experimental
glueball candidate spectrum as well as quenched glueball estimates.Comment: 22 pages, 19 figures and 8 tables, minor additions on mixing
post-refere
The Intrinsic Fractions and Radio Properties of Low Ionization Broad Absorption Line Quasars
Low-ionization (MgII, FeII, FeIII) broad absorption line quasars (LoBALs)
probe a relatively obscured quasar population, and could be at an early
evolutionary stage for quasars. We study the intrinsic fractions of LoBALs
using the SDSS, 2MASS, and FIRST surveys. We find that the LoBAL fractions of
the near infra-red (NIR) and radio samples are approximately 5--7 times higher
than those measured in the optical sample. This suggests that the fractions
measured in the NIR and radio bands are closer to the intrinsic fractions of
the populations, and that the optical fractions are significantly biased due to
obscuration effects, similar to high-ionization broad absorption line quasars
(HiBALs). We also find that the LoBAL fractions decrease with increasing radio
luminosities, again, similar to HiBALs. In addition, we find tentative evidence
for high fractions of LoBALs at high NIR luminosities, especially for FeLoBALs
with a fraction of ~18 per cent at M_K_s < -31 mag. This population of NIR
luminous LoBALs may be at an early evolutionary stage of quasar evolution. We
use a two-component model of LoBALs including a pure geometric component and a
luminosity dependent component at high NIR luminosities, and obtain better fits
than those from a pure geometric model. Therefore, the LoBAL population can be
modelled as a hybrid of both the geometric and evolutionary models, where the
geometric component constitutes 3.4\pm0.3, 5.8\pm0.4, and 1.5\pm0.3 per cent of
the quasar population for BI-LoBALs, AI-LoBALs, and FeLoBALs, respectively.
Considering a population of obscured quasars that do not enter the SDSS survey,
which could have a much higher LoBAL fraction, we expect that intrinsic
fraction of LoBALs could be even higher.Comment: 10 pages, 6 figures, submitted to MNRA
Discovery of a Radio-Selected z ~ 6 Quasar
We present the discovery of only the second radio-selected, z ~ 6 quasar. We
identified SDSS J222843.54+011032.2 (z=5.95) by matching the optical detections
of the deep Sloan Digital Sky Survey (SDSS) Stripe 82 with their radio
counterparts in the Stripe82 VLA Survey. We also matched the
Canadian-France-Hawaiian Telescope Legacy Survey Wide (CFHTLS Wide) with the
Faint Images of the Radio Sky at Twenty-cm (FIRST) survey but have yet to find
any z ~ 6 quasars in this survey area. The discovered quasar is
optically-faint, z = 22.3 and M_{1450} ~ -24.5, but radio-bright, with a flux
density of f = 0.31mJy and a radio-loudness of R ~ 1100 (where
R = f_{5GHz}/f_{2500}). The i-z color of the discovered quasar places it
outside the color selection criteria for existing optical surveys. We conclude
by discussing the need for deeper wide-area radio surveys in the context of
high-redshift quasars.Comment: 20 pages, 6 figures, and ApJ accepte
Excited States in Staggered Meson Propagators
We report on preliminary results from multi-particle fits to meson
propagators with three flavors of light dynamical quarks. We are able to
measure excited states in propagators with pion quantum numbers, which we
interpret as the pion 2S state, and is evidence of locality of the action. In
the a_0 (0^{++}) propagators we find evidence for excited states which are
probably the expected decay channels, pi+eta and K+Kbar.Comment: Lattice2003(spectrum) 3 pages, 4 figure
effect of electrical water bath stunning on physical reflexes of broilers evaluation of stunning efficacy under field conditions
Abstract The effects of different amounts and frequencies of stunning sine wave alternating current were investigated under field conditions. Seven hundred and fifty broilers were stunned in an electrical water bath with an average root mean square (RMS) current of 150, 200, and 250 mA and frequencies of 200, 400, 600, 800, and 1,200 Hz. The occurrence of corneal reflex, spontaneous eye blinking, and a positive response to a painful stimulus were monitored and recorded immediately after the stunning and at 20 s post-stun. Statistical analysis showed that the electrical stunning frequency (P = 0.0004), the stunning RMS current (P At a current of 150 mA, the probability of a successful stun was over 90% at 200 Hz, approximately 40% at 400 Hz, and below 5% for frequencies greater than 600 Hz. So, stunning at frequencies greater than 600 Hz cannot be recommended when a RMS current of 150 mA is applied. The maximum probability of a successful stun was obtained for a current level of 200 mA at 400 Hz and for a current level of 250 mA at 400 and 600 Hz, whereas the stunning treatments at 1,200 Hz provided the lowest probability of a successful stun. Assessment of spontaneous eye blinking and responses to comb pinching confirmed the indications coming from the analysis of corneal reflex
Quantifying the Detrimental Impacts of Land-Use and Management Change on European Forest Bird Populations
The ecological impacts of changing forest management practices in Europe are poorly understood despite European forests being highly managed. Furthermore, the effects of potential drivers of forest biodiversity decline are rarely considered in concert, thus limiting effective conservation or sustainable forest management. We present a trait-based framework that we use to assess the detrimental impact of multiple land-use and management changes in forests on bird populations across Europe. Major changes to forest habitats occurring in recent decades, and their impact on resource availability for birds were identified. Risk associated with these changes for 52 species of forest birds, defined as the proportion of each species' key resources detrimentally affected through changes in abundance and/or availability, was quantified and compared to their pan-European population growth rates between 1980 and 2009. Relationships between risk and population growth were found to be significantly negative, indicating that resource loss in European forests is an important driver of decline for both resident and migrant birds. Our results demonstrate that coarse quantification of resource use and ecological change can be valuable in understanding causes of biodiversity decline, and thus in informing conservation strategy and policy. Such an approach has good potential to be extended for predictive use in assessing the impact of possible future changes to forest management and to develop more precise indicators of forest health
- …