619 research outputs found
A CROSS SECTIONAL ANALYSIS OF CONSUMER TRENDS IN RED MEAT CONSUMPTION
Food consumption patterns have received considerable attention lately, especially changes in red meat consumption. This article examines and analyzes changes in meat consumption patterns in a southern state. Differences are reported based on demographics and consumer expressed preferences. The results reaffirm the negative role of health concerns and fat on red meat consumption and the positive influence on poultry and seafood. The findings agree with related other studies and suggest that further research into the changing meat consumption patterns is warranted.Food Consumption/Nutrition/Food Safety,
A Closed-Form Shave from Occam's Quantum Razor: Exact Results for Quantum Compression
The causal structure of a stochastic process can be more efficiently
transmitted via a quantum channel than a classical one, an advantage that
increases with codeword length. While previously difficult to compute, we
express the quantum advantage in closed form using spectral decomposition,
leading to direct computation of the quantum communication cost at all encoding
lengths, including infinite. This makes clear how finite-codeword compression
is controlled by the classical process' cryptic order and allows us to analyze
structure within the length-asymptotic regime of infinite-cryptic order (and
infinite Markov order) processes.Comment: 21 pages, 13 figures;
http://csc.ucdavis.edu/~cmg/compmech/pubs/eqc.ht
A Kiloparsec-Scale Hyper-Starburst in a Quasar Host Less than 1 Gigayear after the Big Bang
The host galaxy of the quasar SDSS J114816.64+525150.3 (at redshift z=6.42,
when the Universe was <1 billion years old) has an infrared luminosity of
2.2x10^13 L_sun, presumably significantly powered by a massive burst of star
formation. In local examples of extremely luminous galaxies such as Arp220, the
burst of star formation is concentrated in the relatively small central region
of <100pc radius. It is unknown on which scales stars are forming in active
galaxies in the early Universe, which are likely undergoing their initial burst
of star formation. We do know that at some early point structures comparable to
the spheroidal bulge of the Milky Way must have formed. Here we report a
spatially resolved image of [CII] emission of the host galaxy of
J114816.64+525150.3 that demonstrates that its star forming gas is distributed
over a radius of ~750pc around the centre. The surface density of the star
formation rate averaged over this region is ~1000 M_sun/yr/kpc^2. This surface
density is comparable to the peak in Arp220, though ~2 orders of magnitudes
larger in area. This vigorous star forming event will likely give rise to a
massive spheroidal component in this system.Comment: Nature, in press, Feb 5 issue, p. 699-70
A Detailed Gravitational Lens Model Based on Submillimeter Array and Keck Adaptive Optics Imaging of a Herschel-ATLAS Submillimeter Galaxy at z = 4.243
We present high-spatial resolution imaging obtained with the Submillimeter Array (SMA) at 880 μm and the Keck
adaptive optics (AO) system at the KS-band of a gravitationally lensed submillimeter galaxy (SMG) at z = 4.243 discovered in the Herschel Astrophysical Terahertz Large Area Survey. The SMA data (angular resolution ≈0".
6) resolve the dust emission into multiple lensed images, while the Keck AO K_S-band data (angular resolution ≈0".
1) resolve the lens into a pair of galaxies separated by 0".
3. We present an optical spectrum of the foreground lens
obtained with the Gemini-South telescope that provides a lens redshift of z_(lens) = 0.595 ± 0.005. We develop and
apply a new lens modeling technique in the visibility plane that shows that the SMG is magnified by a factor
of μ = 4.1 ± 0.2 and has an intrinsic infrared (IR) luminosity of L_(IR) = (2.1 ± 0.2) × 10_(13) L_☉. We measure a half-light radius of the background source of r_s = 4.4 ± 0.5 kpc which implies an IR luminosity surface density of Σ_(IR) = (3.4 ± 0.9) × 10^(11) L_☉ kpc^(−2), a value that is typical of z > 2 SMGs but significantly lower than IR luminous galaxies at z ∼ 0. The two lens galaxies are compact (r_(lens) ≈ 0.9 kpc) early-types with Einstein
radii of θ_(E1) = 0.57 ± 0.01 and θ_(E2) = 0.40 ± 0.01 that imply masses of M_(lens1) = (7.4 ± 0.5) × 10^(10)M_☉ and
M_(lens2) = (3.7 ± 0.3) × 10^(10) M_☉. The two lensing galaxies are likely about to undergo a dissipationless merger, and the mass and size of the resultant system should be similar to other early-type galaxies at z ∼ 0.6. This work highlights the importance of high spatial resolution imaging in developing models of strongly lensed galaxies discovered by Herschel
Observations of Dense Molecular Gas in a Quasar Host Galaxy at z=6.42: Further Evidence for a Non-Linear Dense Gas - Star Formation Relation at Early Cosmic Times
We report a sensitive search for the HCN(J=2-1) emission line towards SDSS
J1148+5251 at z=6.42 with the VLA. HCN emission is a star formation indicator,
tracing dense molecular hydrogen gas (n(H2) >= 10^4 cm^-3) within star-forming
molecular clouds. No emission was detected in the deep interferometer maps of
J1148+5251. We derive a limit for the HCN line luminosity of L'(HCN) < 3.3 x
10^9 K km/s pc^2, corresponding to a HCN/CO luminosity ratio of L'(HCN)/L'(CO)
< 0.13. This limit is consistent with a fraction of dense molecular gas in
J1148+5251 within the range of nearby ultraluminous infrared galaxies (ULIRGs;
median value: L'(HCN)/L'(CO) = 0.17 {+0.05/-0.08}) and HCN-detected z>2
galaxies (0.17 {+0.09/-0.08}). The relationship between L'(HCN) and L(FIR) is
considered to be a measure for the efficiency at which stars form out of dense
gas. In the nearby universe, these quantities show a linear correlation, and
thus, a practically constant average ratio. In J1148+5251, we find
L(FIR)/L'(HCN) > 6600. This is significantly higher than the average ratios for
normal nearby spiral galaxies (L(FIR)/L'(HCN) = 580 {+510/-270}) and ULIRGs
(740 {+505/-50}), but consistent with a rising trend as indicated by other z>2
galaxies (predominantly quasars; 1525 {+1300/-475}). It is unlikely that this
rising trend can be accounted for by a contribution of AGN heating to L(FIR)
alone, and may hint at a higher median gas density and/or elevated
star-formation efficiency toward the more luminous high-redshift systems. There
is marginal evidence that the L(FIR)/L'(HCN) ratio in J1148+5251 may even
exceed the rising trend set by other z>2 galaxies; however, only future
facilities with very large collecting areas such as the SKA will offer the
sensitivity required to further investigate this question.Comment: 5 pages, 2 figures, 2 tables, to appear in ApJL (accepted October 24,
2007
Metal Loss Characterization in 55-Gallon Drum Steel by the Magnetic Flux Leakage Method
Estimates indicate the number of 55-gallon carbon steel drums, storing various waste forms, total in the millions and are distributed in localized waste storage sites all across the US. Other nations are expected to have similar situations as well. Figure 1 shows steel drums in a burial trench at Hanford. Each Government site working on radioactive weapons production store their drums differently but each site is beginning to experience problems with leaking drums
Molecular Gas in Redshift 6 Quasar Host Galaxies
We report our new observations of redshifted carbon monoxide emission from
six z~6 quasars, using the PdBI. CO (6-5) or (5-4) line emission was detected
in all six sources. Together with two other previous CO detections, these
observations provide unique constraints on the molecular gas emission
properties in these quasar systems close to the end of the cosmic reionization.
Complementary results are also presented for low-J CO lines observed at the GBT
and the VLA, and dust continuum from five of these sources with the SHARC-II
bolometer camera at the CSO. We then present a study of the molecular gas
properties in our combined sample of eight CO-detected quasars at z~6. The
detections of high-order CO line emission in these objects indicates the
presence of highly excited molecular gas, with estimated masses on the order of
10^10 M_sun within the quasar host galaxies. No significant difference is found
in the gas mass and CO line width distributions between our z~6 quasars and
samples of CO-detected quasars and submillimeter galaxies.
Most of the CO-detected quasars at z~6 follow the far infrared-CO luminosity
relationship defined by actively star-forming galaxies at low and high
redshifts. This suggests that ongoing star formation in their hosts contributes
significantly to the dust heating at FIR wavelengths. The result is consistent
with the picture of galaxy formation co-eval with supermassive black hole
(SMBH) accretion in the earliest quasar-host systems. We investigate the black
hole--bulge relationships of our quasar sample, using the CO dynamics as a
tracer for the dynamical mass of the quasar host. The results place important
constraints on the formation and evolution of the most massive SMBH-spheroidal
host systems at the highest redshift.Comment: 34 pages, 8 figures, accepted for publication in Ap
The kiloparsec-scale star formation law at redshift 4: wide-spread, highly efficient star formation in the dust-obscured starburst galaxy GN20
We present high-resolution observations of the 880 m (rest-frame FIR)
continuum emission in the z4.05 submillimeter galaxy GN20 from the IRAM
Plateau de Bure Interferometer (PdBI). These data resolve the obscured star
formation in this unlensed galaxy on scales of
0.30.2 (2.11.3 kpc).
The observations reveal a bright (161 mJy) dusty starburst centered on the
cold molecular gas reservoir and showing a bar-like extension along the major
axis. The striking anti-correlation with the HST/WFC3 imaging suggests that the
copious dust surrounding the starburst heavily obscures the rest-frame
UV/optical emission. A comparison with 1.2 mm PdBI continuum data reveals no
evidence for variations in the dust properties across the source within the
uncertainties, consistent with extended star formation, and the peak star
formation rate surface density (1198 M yr kpc)
implies that the star formation in GN20 remains sub-Eddington on scales down to
3 kpc. We find that the star formation efficiency is highest in the central
regions of GN20, leading to a resolved star formation law with a power law
slope of , and that
GN20 lies above the sequence of normal star-forming disks, implying that the
dispersion in the star formation law is not due solely to morphology or choice
of conversion factor. These data extend previous evidence for a fixed star
formation efficiency per free-fall time to include the star-forming medium on
kpc-scales in a galaxy 12 Gyr ago.Comment: 6 pages, 5 figures, accepted to ApJ
COLDz: Karl G. Jansky Very Large Array discovery of a gas-rich galaxy in COSMOS
The broad spectral bandwidth at mm and cm-wavelengths provided by the recent upgrades to the Karl G. Jansky Very Large Array (VLA) has made it possible to conduct unbiased searches for molecular CO line emission at redshifts, z > 1.31. We present the discovery of a gas-rich, star-forming galaxy at z = 2.48, through the detection of CO(1-0) line emission in the COLDz survey, through a sensitive, Ka-band (31 to 39 GHz) VLA survey of a 6.5 square arcminute region of the COSMOS field. We argue that the broad line (FWHM ~570 +/- 80 km/s) is most likely to be CO(1-0) at z=2.48, as the integrated emission is spatially coincident with an infrared-detected galaxy with a photometric redshift estimate of z = 3.2 +/- 0.4. The CO(1-0) line luminosity is L'_CO = (2.2 +/- 0.3) x 10^{10} K km/s pc^2, suggesting a cold molecular gas mass of M_gas ~ (2 - 8)x10^{10}M_solar depending on the assumed value of the molecular gas mass to CO luminosity ratio alpha_CO. The estimated infrared luminosity from the (rest-frame) far-infrared spectral energy distribution (SED) is L_IR = 2.5x10^{12} L_solar and the star-formation rate is ~250 M_solar/yr, with the SED shape indicating substantial dust obscuration of the stellar light. The infrared to CO line luminosity ratio is ~114+/-19 L_solar/(K km/s pc^2), similar to galaxies with similar SFRs selected at UV/optical to radio wavelengths. This discovery confirms the potential for molecular emission line surveys as a route to study populations of gas-rich galaxies in the future
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