1,592,503 research outputs found
The Radio Continuum, Far-Infrared Emission, And Dense Molecular Gas In Galaxies
A tight linear correlation is established between the HCN line luminosity and
the radio continuum (RC) luminosity for a sample of 65 galaxies (from Gao &
Solomon's HCN survey), including normal spiral galaxies and luminous and
ultraluminous infrared galaxies (LIRGs/ULIRGs). After analyzing the various
correlations among the global far-infrared (FIR), RC, CO, and HCN luminosities
and their various ratios, we conclude that the FIR-RC and FIR-HCN correlations
appear to be linear and are the tightest among all correlations. The
combination of these two correlations could result in the tight RC-HCN
correlation we observed. Meanwhile, the non-linear RC-CO correlation shows
slightly larger scatter as compared with the RC-HCN correlation, and there is
no correlation between ratios of either RC/HCN-CO/HCN or RC/FIR-CO/FIR. In
comparison, a meaningful correlation is still observed between ratios of
RC/CO-HCN/CO. Nevertheless, the correlation between RC/FIR and HCN/FIR also
disappears, reflecting again the two tightest FIR-RC and FIR-HCN correlations
as well as suggesting that FIR seems to be the bridge that connects HCN with
RC. Interestingly, despite obvious HCN-RC and RC-CO correlations,
multi-parameter fits hint that while both RC and HCN contribute significantly
(with no contribution from CO) to FIR, yet RC is primarily determined from FIR
with a very small contribution from CO and essentially no contribution from
HCN. These analyses confirm independently the former conclusions that it is
practical to use RC luminosity instead of FIR luminosity, at least globally, as
an indicator of star formation rate in galaxies including LIRGs/ULIRGs, and HCN
is a much better tracer of star-forming molecular gas and correlates with FIR
much better than that of CO.Comment: 11 ApJ pages, 7 figures; ApJ in pres
Effect of forage legumes on feed intake, milk production and milk quality – a review
Literature data from experiments with lactating dairy cows offered silage-based diets was reviewed to evaluate the effects of the grassland legume species Trifolium repens (WC, white clover), Trifolium pratense (RC, red clover) and Medicago sativa (M, lucerne) on feed intake, milk production and milk quality. Seven data sets were created to compare grass silage (G) with grassland legumes in general(L), G with RC, G with WC, G with M, RC with WC, RC with M and different silage proportions of RC. Daily dry matter intake and milk yield were on average 1.6 and 1.6 kg, respectively, higher and milk fat content 1.2 g/kg milk lower on L than on G based diets. Similar differences were found when G was compared with RC or WC diets. Cows offered WC yielded 1.1 kg/d more milk than RC, and milk produced on WC and M contained 0.7 g more protein per kg than milk from RC diets. Increasing the silage diet RC proportion from 0.5 to 1.0 also decreased the milk protein content by 0.8 g/kg milk. RC increased the level of poly-unsaturated fatty acids, particularly C18:3n-3, and isoflavones, particularly equol, in milk. Effects are discussed in relation to plant cell wall characteristics, plant chemical constituents and changes in rumen digestion to explain the origin of the differences in intake, milk yield and milk compositio
Structural behaviour of beam with HDPE plastic balls subjected to flexure load
This paper presents the structural behavior of reinforced concrete beam embedded with high density polyethylene balls (HDPE) subjected to flexural load. The HDPE balls with 180 mm diameter were embedded to create the spherical voids in the beam which lead to reduction in its self-weight. Two beam specimens with HDPE balls (RC-HDPE) and one solid beam (RC-S) with dimension 250 mm x 300 mm x 1100 mm were cast and tested until failure. The results are analysed in the context of its ultimate load, load-deflection profile, and crack pattern and failure mode. It was found that the ultimate load of RC-HDPE was reduced by 32% compared to RC-S beam while the maximum deflection at its mid span was increased by 4%. However, RC-HDPE is noticed to be more ductile compared to RC-S beam. Both types of beams experienced flexure cracks and diagonal tension cracks before failur
Constant-amplitude RC oscillator
Sinusoidal oscillator has a frequency determined by resistance-capacitance /RC/ values of two charge control devices and a constant-amplitude voltage independent of frequency and RC values. RC elements provide either voltage-control, resistance-control, or capacitance-control of the frequency
An analysis of the FIR/RADIO Continuum Correlation in the Small Magellanic Cloud
The local correlation between far-infrared (FIR) emission and radio-continuum
(RC) emission for the Small Magellanic Cloud (SMC) is investigated over scales
from 3 kpc to 0.01 kpc. Here, we report good FIR/RC correlation down to ~15 pc.
The reciprocal slope of the FIR/RC emission correlation (RC/FIR) in the SMC is
shown to be greatest in the most active star forming regions with a power law
slope of ~1.14 indicating that the RC emission increases faster than the FIR
emission. The slope of the other regions and the SMC are much flatter and in
the range of 0.63-0.85. The slopes tend to follow the thermal fractions of the
regions which range from 0.5 to 0.95. The thermal fraction of the RC emission
alone can provide the expected FIR/RC correlation. The results are consistent
with a common source for ultraviolet (UV) photons heating dust and Cosmic Ray
electrons (CRe-s) diffusing away from the star forming regions. Since the CRe-s
appear to escape the SMC so readily, the results here may not provide support
for coupling between the local gas density and the magnetic field intensity.Comment: 19 pages, 7 Figure
Testing asteroseismology with Gaia DR2: Hierarchical models of the Red Clump
Asteroseismology provides fundamental stellar parameters independent of
distance, but subject to systematics under calibration. Gaia DR2 has provided
parallaxes for a billion stars, which are offset by a parallax zero-point. Red
Clump (RC) stars have a narrow spread in luminosity, thus functioning as
standard candles to calibrate these systematics. This work measures how the
magnitude and spread of the RC in the Kepler field are affected by changes to
temperature and scaling relations for seismology, and changes to the parallax
zero-point for Gaia. We use a sample of 5576 RC stars classified through
asteroseismology. We apply hierarchical Bayesian latent variable models,
finding the population level properties of the RC with seismology, and use
those as priors on Gaia parallaxes to find the parallax zero-point offset. We
then find the position of the RC using published values for the zero-point. We
find a seismic temperature insensitive spread of the RC of ~0.03 mag in the
2MASS K band and a larger and slightly temperature-dependent spread of ~0.13
mag in the Gaia G band. This intrinsic dispersion in the K band provides a
distance precision of ~1% for RC stars. Using Gaia data alone, we find a mean
zero-point of -41 10 as. This offset yields RC absolute magnitudes
of -1.634 0.018 in K and 0.546 0.016 in G. Obtaining these same
values through seismology would require a global temperature shift of ~-70 K,
which is compatible with known systematics in spectroscopy.Comment: Accepted for publication in MNRA
A Measurement of Rb using a Double Tagging Method
The fraction of Z to bbbar events in hadronic Z decays has been measured by
the OPAL experiment using the data collected at LEP between 1992 and 1995. The
Z to bbbar decays were tagged using displaced secondary vertices, and high
momentum electrons and muons. Systematic uncertainties were reduced by
measuring the b-tagging efficiency using a double tagging technique. Efficiency
correlations between opposite hemispheres of an event are small, and are well
understood through comparisons between real and simulated data samples. A value
of Rb = 0.2178 +- 0.0011 +- 0.0013 was obtained, where the first error is
statistical and the second systematic. The uncertainty on Rc, the fraction of Z
to ccbar events in hadronic Z decays, is not included in the errors. The
dependence on Rc is Delta(Rb)/Rb = -0.056*Delta(Rc)/Rc where Delta(Rc) is the
deviation of Rc from the value 0.172 predicted by the Standard Model. The
result for Rb agrees with the value of 0.2155 +- 0.0003 predicted by the
Standard Model.Comment: 42 pages, LaTeX, 14 eps figures included, submitted to European
Physical Journal
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