217 research outputs found
growth performance and behaviour of finishing beef cattle illegally treated with growth promoters
The study aimed at evaluating growth performance, feeding and social behaviour of finishing beef cattle treated with Dexamethasone per os alone or in association with Estradiol. Twenty-four French cross-bred beef bulls were allotted to 3 balanced treatment groups: Control (C); Dexamethasone (D) and Dexamethasone + Estradiol (D+E). All the bulls received the same diet and the experimental period lasted 43 days. All the productive traits and eating behaviour were similar among treatments. Bulls provided with D+E showed a prolonged rumination during the 8 h following diet distribution but this behaviour was partially performed in standing position, since lying was significantly reduced in both treated groups as compared to Control. However, difference in behaviour were too limited to be considered a reliable indicator of these illegal treatments
Characteristics of dairy farms in the North-Eastern part of Italy: rations, milk yield and nutrients excretion
This survey was aimed to evaluate the characteristics of dairy farms in the North- Eastern part of Po valley in terms of ration composition, milk yield and N and P excretions. Eightynine farms, with Italian Holstein Friesian cows, were selected in order to cover different situations in term of farm size and milk yield (MY). MY and quality were obtained from the national database of functional controls. Each farm was visited in order to collect information about ingredients and chemical composition of rations used. Farms were classified in four groups differing for dietary crude protein density (LCP15.3% DM) and for MY (LMY30 kg/d). N and P excretions were quantified by following a mass balance approach. Dietary crude protein content (CP) was not correlated to milk yield (MY) and quality. The estimated amounts of N excreted, discounted for 28% of N losses in atmosphere, were 78.5, 78.2, 87.2 and 89.1 kg/cow/year, and P excreted were 20.2, 18.6, 18.7 and 19.8 kg/cow/year for the LCPLMY, LCPHMY, HCPLMY, HCPHMY groups, respectively. On corn silage and cereals based rations, a dietary CP of 14.3% DM can support 31 kg MY/cow/day
Constraining the radial drift of millimeter-sized grains in the protoplanetary disks in Lupus
Directly tracing the vertical stratification of molecules in protoplanetary disks
We aim to directly trace the vertical location of the emitting surface of
multiple molecular tracers in protoplanetary disks. Our sample of disks
includes Elias 2-27, WaOph 6 and the sources targeted by the MAPS ALMA Large
Program. The set of molecules studied include CO isotopologues in various
transitions, HCN, CN, H2CO, HCO+, C2H and c-C3H2. The vertical emitting region
is determined directly from the channel maps, implementing accurate masking of
the channel emission to recover the vertical location of the emission surface
even at large radial distances from the star and for low-SNR lines. The
vertical location of the emitting layer is obtained for 4-10 lines in each
disk. IM Lup, HD163296 and MWC 480 12CO and 13CO show vertical modulations,
which are coincident with dust gaps and kinematical perturbations. We also
present estimates of the gas pressure scale height in the disks from the MAPS
sample. Compared to physical-chemical models we find good agreement with the
vertical location of CO isotopologues. In HD 163296 CN and HCN trace a similar
intermediate layer, for the other disks, the UV flux tracers and the vertical
profiles of HCN and C2H are lower than predicted in theoretical models. HCN and
H2CO show a highly structured vertical profile, possibly indicative of
different formation pathways. It is possible to trace the vertical locations of
multiple molecular species that trace a wide variety of physical and chemical
disk properties. The distribution of CO isotopologues are found at a wide range
of vertical heights 0.5-0.05. Other molecular lines are mostly found
at 0.15. The vertical layering of molecules is in agreement with
theory in some systems, but not in all, therefore dedicated chemical-physical
models are needed to further study and understand the emission surfaces.Comment: Accepted for publication in A&A. 29 pages, 28 figure
Constraining the radial drift of millimeter-sized grains in the protoplanetary disks in Lupus
Recent ALMA surveys of protoplanetary disks have shown that for most disks
the extent of the gas emission is greater than the extent of the thermal
emission of the millimeter-sized dust. Both line optical depth and the combined
effect of radially dependent grain growth and radial drift may contribute to
this observed effect. For a sample of 10 disks from the Lupus survey we
investigate how well dust-based models without radial dust evolution reproduce
the observed 12CO outer radius, and determine whether radial dust evolution is
required to match the observed gas-dust size difference. We used the
thermochemical code DALI to obtain 12CO synthetic emission maps and measure gas
and dust outer radii (Rco, Rmm) using the same methods as applied to the
observations, which were compared to observations on a source-by-source basis.
For 5 disks we find that the observed gas-dust size difference is larger than
the gas-dust size difference due to optical depth, indicating that we need both
dust evolution and optical depth effects to explain the observed gas-dust size
difference. For the other 5 disks the observed gas-dust size difference can be
explained using only line optical depth effects. We also identify 6 disks not
included in our initial sample but part of a survey of the same star-forming
region that show significant 12CO emission beyond 4 x Rmm. These disks, for
which no Rco is available, likely have gas-dust size differences greater than 4
and are difficult to explain without substantial dust evolution. Our results
suggest that radial drift and grain growth are common features among both
bright and fain disks. The effects of radial drift and grain growth can be
observed in disks where the dust and gas radii are significantly different,
while more detailed models and deeper observations are needed to see this
effect in disks with smaller differences.Comment: 17 pages, 11 figures, accepted in A&
Gas Density Perturbations Induced by One or More Forming Planets in the AS 209 Protoplanetary Disk as Seen with ALMA
The formation of planets occurs within protoplanetary disks surrounding young
stars, resulting in perturbation of the gas and dust surface densities. Here,
we report the first evidence of spatially resolved gas surface density
() perturbation towards the AS~209 protoplanetary disk from the
optically thin CO () emission. The observations were carried out
at 1.3~mm with ALMA at a spatial resolution of about 0.3\arcsec
0.2\arcsec (corresponding to 38 25 au). The CO
emission shows a compact (60~au), centrally peaked emission and an outer
ring peaking at 140~au, consistent with that observed in the continuum emission
and, its azimuthally averaged radial intensity profile presents a deficit that
is spatially coincident with the previously reported dust map. This deficit can
only be reproduced with our physico-thermochemical disk model by lowering
by nearly an order of magnitude in the dust gaps. Another
salient result is that contrary to CO, the DCO () emission
peaks between the two dust gaps. We infer that the best scenario to explain our
observations (CO deficit and DCO enhancement) is a gas
perturbation due to forming-planet(s), that is commensurate with previous
continuum observations of the source along with hydrodynamical simulations. Our
findings confirm that the previously observed dust gaps are very likely due to
perturbation of the gas surface density that is induced by a planet of at least
0.2~M in formation. Finally, our observations also show the
potential of using CO isotopologues to probe the presence of saturn mass
planet(s)
ALMA unveils rings and gaps in the protoplanetary system HD 169142: signatures of two giant protoplanets
The protoplanetary system HD 169142 is one of the few cases where a potential candidate protoplanet has recently been detected by direct imaging in the near-infrared. To study the interaction between the protoplanet and the disk itself, observations of the gas and dust surface density structure are needed. This paper reports new ALMA observations of the dust continuum at 1.3 mm, 12CO, 13CO, and C18O J = 2−1 emission from the system HD 169142 (which is observed almost face-on) at an angular resolution of ∼0.3"×0.2′′ (∼35 × 20 au). The dust continuum emission reveals a double-ring structure with an inner ring between 0.17"−0.28" (∼20−35 au) and an outer ring between 0.48−0.64 (∼56−83 au). The size and position of the inner ring is in good agreement with previous polarimetric observations in the near-infrared and is consistent with dust trapping by a massive planet. No dust emission is detected inside the inner dust cavity (R μm size). Using the thermo-chemical disk code dali, we modeled the continuum and the CO isotopolog emission to quantitatively measure the gas and dust surface densities. The resulting gas surface density is reduced by a factor of ∼30−40 inward of the dust gap. The gas and dust distribution indicate that two giant planets shape the disk structure through dynamical clearing (dust cavity and gap) and dust trapping (double-ring dust distribution)
Vertically extended and asymmetric CN emission in the Elias 2-27 protoplanetary disk
Elias 2-27 is a young star that hosts an extended, bright and inclined disk
of dust and gas. The inclination and extreme flaring of the disk make Elias
2-27 an ideal target to study the vertical distribution of molecules,
particularly CN. We directly trace the emission of CN in Elias 2-27 and compare
it to previously published CO isotopologue data. CN emission is
analyzed in two different transitions and , for
which we detect two hyperfine group transitions. The vertical location of CN
emission is traced directly from the channel maps, following geometrical
methods that have been previously used to analyze the CO emission of Elias
2-27. Analytical models are used to parametrize the vertical profile of each
molecule and study the extent of each tracer, additionally we compute radial
profiles of column density and optical depth. We show that the vertical
location of CN and CO isotopologues in Elias 2-27 is layered and consistent
with predictions from thermochemical models. A north/south asymmetry in the
radial extent of CN is detected and we find that the CN emission is mostly
optically thin and constrained vertically to a thin slab at 0.5. A
column density of 10\,cm is measured in the inner disk which for
the north side decreases to 10\,cm and for the south side to
10\,cm in the outer regions. In Elias 2-27, CN traces a
vertically elevated region above the midplane, very similar to that traced by
CO. The inferred CN properties are consistent with thermo-chemical disk
models, in which CN formation is initiated by the reaction of N with UV-pumped
H. The observed north/south asymmetry may be caused by either ongoing
infall or by a warped inner disk. This study highlights the importance of
tracing the vertical location of various molecules to constrain the disk
physical conditions.Comment: Accepted for publication in A&A, 19 pages, 14 figure
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