169 research outputs found
Relative effectiveness of several simulated jet engine noise spectral treatments in reducing annoyance in a TV-viewing situation
An experiment was conducted in order to determine the relative effectiveness of several hypothetical jet engine noise treatments and to test hypothesis that speech interference, at least in part, mediates annoyance in a TV-viewing situation. Twenty-four subjects watched television in a simulated living room. Recorded jet flyover noises were presented in such a way as to create the illusion that aircraft were actually flying overhead. There were 27 stimuli (nine spectra at three overall levels) presented at an average rate of approximately one flight every 2 minutes. Subjects judged the annoyance value of individual stimuli using either a category rating method or magnitude estimation method in each of two 1-hour sessions. The spectral treatments most effective in reducing annoyance were at 1.6 Khz and 800 Hz, in that order. The degree of annoyance reduction resulting from all treatments was affected by the overall sound level of the stimuli, with the greatest reduction at the intermediate overall sound level, about 88 to 89 db(A), peak value. The results are interpreted as supporting the hypothesis that speech interference, at least in part, mediates annoyance with aircraft noise in a TV-viewing situation
Specific antigen of tumor cell transformed by DNA extracted from SV-40 virus
In the immunofluorescent study it has been revealed that rabbit sera immunized with transformed cells induced by SV-40 DNA, produce circulating antibody capable of re:lcting with intranuclear antigens synthesized by SV-40 complyte virus transforming process, In addition, the result confirmed that SV-40 DNA replicates DNA-containing
viruses in the host cell and that also the genome coding for the synthesis of SV-40 tumor antigen is resposible for viral DNA.</p
Angular Momentum Exchange by Gravitational Torques and Infall in the Circumbinary Disk of the Protostellar System L1551 NE
We report the ALMA observation of the Class I binary protostellar system
L1551 NE in the 0.9-mm continuum, C18O (3-2), and 13CO (3-2) lines at a ~1.6
times higher resolution and a ~6 times higher sensitivity than those of our
previous SMA observations, which revealed a r ~300 AU-scale circumbinary disk
in Keplerian rotation. The 0.9-mm continuum shows two opposing U-shaped
brightenings in the circumbinary disk, and exhibits a depression between the
circumbinary disk and the circumstellar disk of the primary protostar. The
molecular lines trace non-axisymmetric deviations from Keplerian rotation in
the circumbinary disk at higher velocities relative to the systemic velocity,
where our previous SMA observations could not detect the lines. In addition, we
detect inward motion along the minor axis of the circumbinary disk. To explain
the newly-observed features, we performed a numerical simulation of gas orbits
in a Roche potential tailored to the inferred properties of L1551 NE. The
observed U-shaped dust features coincide with locations where gravitational
torques from the central binary system are predicted to impart angular momentum
to the circumbinary disk, producing shocks and hence density enhancements seen
as a pair of spiral arms. The observed inward gas motion coincides with
locations where angular momentum is predicted to be lowered by the
gravitational torques. The good agreement between our observation and model
indicates that gravitational torques from the binary stars constitute the
primary driver for exchanging angular momentum so as to permit infall through
the circumbinary disk of L1551 NE.Comment: 38 pages, 11 figures, accepted for publication in Ap
Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. III. An Extensive Survey for Molecular Outflows
Using the ASTE 10 m submillimeter telescope and the 1.4 m Infrared Survey
Facility (IRSF), we performed an extensive outflow survey in the Orion
Molecular Cloud -2 and -3 region. Our survey, which includes 41 potential
star-forming sites, has been newly compiled using multi-wavelength data based
on millimeter- and submillimeter-continuum observations as well as radio
continuum observations. From the CO (3-2) observations performed with the ASTE
10 m telescope, we detected 14 CO molecular outflows, seven of which were newly
identified. This higher detection rate, as compared to previous CO (1-0)
results in the same region, suggests that CO (3-2) may be a better outflow
tracer. Physical properties of these outflows and their possible driving
sources were derived. Derived parameters were compared with those of CO
outflows in low- and high-mass starforming regions. We show that the CO outflow
momentum correlates with the bolometric luminosity of the driving source and
with the envelope mass, regardless of the mass of the driving sources. In
addition to these CO outflows, seven sources having NIR features suggestive of
outflows were also identified.Comment: Accepted to Astrophysical Journal, high resolution images at
http://www.asiaa.sinica.edu.tw/~satoko_t/papers/ms.ST.pd
Millimeter- and Submillimeter-Wave Observations of the OMC-2/3 Region. II. Observational Evidence for Outflow-Triggered Star Formation in the OMC-2 FIR 3/4 Region
We have carried out the observations of the OMC-2 FIR 3/4 region with the NMA
and ASTE in the HCO (1--0), CO (3--2, 1--0), SiO (=0,
=2--1), CS (2--1), and CHOH (=7--6) lines and in the 3.3 mm
continuum emission. Our NMA observations in the HCO emission have
revealed 0.07 pc-scale dense gas associated with FIR 4. The CO
(3--2,1--0) emission shows high-velocity blue and red shifted components at the
both north-east and south-west of FIR 3, suggesting a molecular outflow nearly
along the plane of the sky driven by FIR 3. The SiO and the CHOH emission
are detected around the interface between the outflow and the dense gas.
Furthermore, the CO (1--0) emission shows an L-shaped structure in the
P-V diagram. These results imply presence of the shock due to the interaction
between the molecular outflow driven by FIR 3 and the dense gas associated with
FIR 4. Moreover, our high angular-resolution observations of FIR 4 in the 3.3
mm continuum emission have first found that FIR 4 consists of eleven dusty
cores. The separation among these cores is on the same order of the Jeans
length, suggesting that the fragmentation into these cores has been caused by
the gravitational instability. The time scale of the fragmentation is similar
to the time scale of the interaction between the molecular outflow and the
dense gas. We suggest that the interaction between the molecular outflow from
FIR 3 and the dense gas associated with FIR 4 triggered the fragmentation into
these dusty cores, and hence the next generation the cluster formation.Comment: 13 pages, 9 figures. Accepted by Ap
Molecular Evolution in Collapsing Prestellar Cores
We have investigated the evolution and distribution of molecules in
collapsing prestellar cores via numerical chemical models, adopting the
Larson-Penston solution and its delayed analogues to study collapse. Molecular
abundances and distributions in a collapsing core are determined by the balance
among the dynamical, chemical and adsorption time scales. When the central
density n_H of a prestellar core with the Larson-Penston flow rises to 3 10^6
cm^{-3}, the CCS and CO column densities are calculated to show central holes
of radius 7000 AU and 4000 AU, respectively, while the column density of N2H+
is centrally peaked. These predictions are consistent with observations of
L1544. If the dynamical time scale of the core is larger than that of the
Larson-Penston solution owing to magnetic fields, rotation, or turbulence, the
column densities of CO and CCS are smaller, and their holes are larger than in
the Larson-Penston core with the same central gas density. On the other hand,
N2H+ and NH3 are more abundant in the more slowly collapsing core. Therefore,
molecular distributions can probe the collapse time scale of prestellar cores.
Deuterium fractionation has also been studied via numerical calculations. The
deuterium fraction in molecules increases as a core evolves and molecular
depletion onto grains proceeds. When the central density of the core is n_H=3
10^6 cm^{-3}, the ratio DCO+/HCO+ at the center is in the range 0.06-0.27,
depending on the collapse time scale and adsorption energy; this range is in
reasonable agreement with the observed value in L1544.Comment: 21 pages, 17 figure
Imaging the Disk around TW Hydrae with the Submillimeter Array
We present ~2"-4" aperture synthesis observations of the circumstellar disk surrounding the nearby young star TW Hya in the CO J = 2-1 and J = 3-2 lines and associated dust continuum obtained with the partially completed Submillimeter Array. The extent and peak flux of the 230 and 345 GHz dust emission follow closely the predictions of the irradiated accretion disk model of Calvet et al. The resolved molecular line emission extends to a radius of at least 200 AU, the full extent of the disk visible in scattered light, and shows a clear pattern of Keplerian rotation. Comparison of the images with two-dimensional Monte Carlo models constrains the disk inclination angle to 7° ± 1°. The CO emission is optically thick in both lines, and the kinetic temperature in the line formation region is ~20 K. Substantial CO depletion, by an order of magnitude or more from canonical dark cloud values, is required to explain the characteristics of the line emission
The CO Molecular Outflows of IRAS 16293-2422 Probed by the Submillimeter Array
We have mapped the proto-binary source IRAS 16293-2422 in CO 2-1, 13CO 2-1,
and CO 3-2 with the Submillimeter Array (SMA). The maps with resolution of
1".5-5" reveal a single small scale (~3000 AU) bipolar molecular outflow along
the east-west direction. We found that the blueshifted emission of this small
scale outflow mainly extends to the east and the redshifted emission to the
west from the position of IRAS 16293A. A comparison with the morphology of the
large scale outflows previously observed by single-dish telescopes at
millimeter wavelengths suggests that the small scale outflow may be the inner
part of the large scale (~15000 AU) E-W outflow. On the other hand, there is no
clear counterpart of the large scale NE-SW outflow in our SMA maps. Comparing
analytical models to the data suggests that the morphology and kinematics of
the small scale outflow can be explained by a wide-angle wind with an
inclination angle of ~30-40 degrees with respect to the plane of the sky. The
high resolution CO maps show that there are two compact, bright spots in the
blueshifted velocity range. An LVG analysis shows that the one located 1" to
the east of source A is extremely dense, n(H_2)~10^7 cm^-3, and warm, T_kin >55
K. The other one located 1" southeast of source B has a higher temperature of
T_kin >65 K but slightly lower density of n(H_2)~10^6 cm^-3. It is likely that
these bright spots are associated with the hot core-like emission observed
toward IRAS 16293. Since both two bright spots are blueshifted from the
systemic velocity and are offset from the protostellar positions, they are
likely formed by shocks.Comment: 27 pages, 8 figures, accepted for publication in ApJ, minor typos
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