936 research outputs found
Observations of Global and Local Infall in NGC 1333
We report ``infall asymmetry'' in the HCO (1--0) and (3--2) lines toward
NGC 1333, extended over , a larger extent than has been
reported be fore, for any star-forming region. The infall asymmetry extends
over a major portion of the star-forming complex, and is not limited to a
single protostar, or to a single dense core, or to a single spectral line. It
seems likely that the infall asymmetry represents inward motions, and that
these motions are physically associated with the complex. Both blue-asymmetric
and red-asymmetric lines are seen, but in both the (3--2) and (1--0) lines of
HCO the vast majority of the asymmetric lines are blue, indicating inward
motions. The (3--2) line, tracing denser gas, has the spectra with the
strongest asymmetry and these spectra are associated with the protostars IRAS
4A and 4B, which most likely indicates a warm central source is affecting the
line profiles. The (3--2) and (1--0) lines usually have the same sense of
asymmetry in common positions, but their profiles differ significantly, and the
(1--0) line appears to trace motions on much larger spatial scales than does
the (3--2) line. Line profile models fit the spectra well, but do not strongly
constrain their parameters. The mass accretion rate of the inward motions is of
order 10 M/yr, similar to the ratio of stellar mass to cluster
age.Comment: 28 pages, 11 figures, 1 colour figur
An S-shaped outflow from IRAS 03256+3055 in NGC 1333
The IRAS source 03256+3055 in the NGC 1333 star forming region is associated
with extended sub-millimeter emission of complex morphology, showing multiple
clumps. One of these is found to coincide with the driving source of a bipolar
jet of S-shaped morphology seen in the emission lines of H_alpha and [SII] as
well as in the H2 emission lines in the K-band. Detailed images of the driving
source at the wavelengths of H_alpha and [SII] and in the I, J, H, and K bands
as well as a K-band spectrum and polarimetry are discussed. The near-infrared
morphology is characterized by a combination of line emission from the jet and
scattered light from a source with a steep continuum spectrum. The morphology
and proper motion of the jet are discussed in the context of a binary system
with a precessing disk. We conclude that the molecular core associated with
IRAS 03256+3055 consists of several clumps, only one of which shows evidence of
recent star formation at optical and near-infrared wavelengths.We also briefly
discuss a second, newly found near-infrared source associated with a compact
sub-millimeter continuum source near IRAS 03256+3055, and conclude that this
source may be physically unrelated the cluster of molecular clumps.Comment: 25 pages, including 5 figures. Accepted for publication in The
Astronomical Journa
Acute stress induced by the preslaughter use of electric prodders causes tougher beef meat
Adrenergic activation and hormone release preslaughter is an inevitable outcome of the systems used to move cattle to slaughter. The aim of this experiment was to investigate the effects of acute preslaughter stress in beef cattle on postmortem muscle metabolism and the meat quality, including consumer-assessed eating quality. Eighty-four cattle were used on three separate days, with ‘mobs’ of four cattle allocated to either a ‘control’ (no electric goads used preslaughter) or a ‘stress’ (six prods given with an electric goad over 5–10 min) treatment at 15 min preslaughter. Cattle undergoing the ‘stress’ treatment had higher plasma lactate at slaughter. The prerigor pH and temperature, ultimate pH and temperature at rigor of the longissimus thoracis muscle were similar between treatments (P\u3e0.05 for all). The water-holding capacity of the longissimus lumborum was reduced by the ‘stress’ treatment, as indicated by higher levels of water lost during suspension (drip loss), storage (purge) for 21 days and cooking (cooking loss at 1 day postslaughter) (P\u3c0.05 for all). ‘Stress’ cattle produced longissimus lumborum muscle with similar sarcomere lengths andWarner–Bratzler shear force at 2, 6 and 21 days , compared to ‘control’ cattle (P\u3c0.05 for all). The longissimus lumborum muscle of cattle undergoing the ‘stress’ treatment was rated less tender, less juicy, with a less acceptable flavour, a lower ‘liking’ and a lower MQ4 score (P\u3c0.05 for all). The ‘bloomed’ surface colour (CIE L*, a*, b*) of the longissimus lumborum muscle at 2, 6 and 21 days postslaughter was similar between the ‘stress’ and ‘control’ treatments (P\u3e0.05 for all). In conclusion, cattle subjected to acute preslaughter stress using electric goads produced meat which the consumer rated as tougher with inferior quality. The inferior quality induced by the acute stress treatment was associated with reduced water-holding capacity but was independent of muscle pH and temperature
Opening up the Quantum Three-Box Problem with Undetectable Measurements
One of the most striking features of quantum mechanics is the profound effect
exerted by measurements alone. Sophisticated quantum control is now available
in several experimental systems, exposing discrepancies between quantum and
classical mechanics whenever measurement induces disturbance of the
interrogated system. In practice, such discrepancies may frequently be
explained as the back-action required by quantum mechanics adding quantum noise
to a classical signal. Here we implement the 'three-box' quantum game of
Aharonov and Vaidman in which quantum measurements add no detectable noise to a
classical signal, by utilising state-of-the-art control and measurement of the
nitrogen vacancy centre in diamond.
Quantum and classical mechanics then make contradictory predictions for the
same experimental procedure, however classical observers cannot invoke
measurement-induced disturbance to explain this discrepancy. We quantify the
residual disturbance of our measurements and obtain data that rule out any
classical model by > 7.8 standard deviations, allowing us for the first time to
exclude the property of macroscopic state-definiteness from our system. Our
experiment is then equivalent to a Kochen-Spekker test of quantum
non-contextuality that successfully addresses the measurement detectability
loophole
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