274 research outputs found
Commensal observing with the Allen Telescope array: software command and control
The Allen Telescope Array (ATA) is a Large-Number-Small-Diameter radio
telescope array currently with 42 individual antennas and 5 independent
back-end science systems (2 imaging FX correlators and 3 time domain beam
formers) located at the Hat Creek Radio Observatory (HCRO). The goal of the ATA
is to run multiple back-ends simultaneously, supporting multiple science
projects commensally. The primary software control systems are based on a
combination of Java, JRuby and Ruby on Rails. The primary control API is
simplified to provide easy integration with new back-end systems while the
lower layers of the software stack are handled by a master observing system.
Scheduling observations for the ATA is based on finding a union between the
science needs of multiple projects and automatically determining an efficient
path to operating the various sub-components to meet those needs. When
completed, the ATA is expected to be a world-class radio telescope, combining
dedicated SETI projects with numerous radio astronomy science projects.Comment: SPIE Conference Proceedings, Software and Cyberinfrastructure for
Astronomy, Nicole M. Radziwill; Alan Bridger, Editors, 77400Z, Vol 774
A Bima Array Survey of Molecules in Comets Linear (C/2002 T7) and Neat (C/2001 Q4)
We present an interferometric search for large molecules, including methanol,
methyl cyanide, ethyl cyanide, ethanol, and methyl formate in comets LINEAR
(C/2002 T7) and NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland
Association (BIMA) array. In addition, we also searched for transitions of the
simpler molecules CS, SiO, HNC, HN13C and 13CO . We detected transitions of
methanol and CS around Comet LINEAR and one transition of methanol around Comet
NEAT within a synthesized beam of ~20''. We calculated the total column density
and production rate of each molecular species using the variable temperature
and outflow velocity (VTOV) model described by Friedel et al.(2005).Considering
the molecular production rate ratios with respect to water, Comet T7 LINEAR is
more similar to Comet Hale-Bopp while Comet Q4 NEAT is more similar to Comet
Hyakutake. It is unclear, however, due to such a small sample size, whether
there is a clear distinction between a Hale-Bopp and Hyakutake class of comet
or whether comets have a continuous range of molecular production rate ratios.Comment: Accepted for Publication in the Astrophysical Journa
Allen Telescope Array Multi-Frequency Observations of the Sun
We present the first observations of the Sun with the Allen Telescope Array
(ATA). We used up to six frequencies, from 1.43 to 6 GHz, and baselines from 6
to 300 m. To our knowledge, these are the first simultaneous multifrequency
full-Sun maps obtained at microwave frequencies without mosaicing. The
observations took place when the Sun was relatively quiet, although at least
one active region was present each time. We present multi-frequency flux
budgets for each sources on the Sun. Outside of active regions, assuming
optically thin bremsstrahlung (free--free) coronal emission on top of an
optically thick ~10 000 K chromosphere, the multi-frequency information can be
condensed into a single, frequency-independent, "coronal bremsstrahlung
contribution function" [EM/sqrt(T)] map. This technique allows the separation
of the physics of emission as well as a measurement of the density structure of
the corona. Deviations from this simple relationship usually indicate the
presence of an additional gyroresonance-emission component, as is typical in
active regions.Comment: 16 pages, 11 figures. Accepted for publication in Solar Physic
The Medium Is the Danger: Discourse about Television among Amish and Ultra-Orthodox (Haredi) Women
This study shows how Old Order Amish and ultra-Orthodox women’s discourse about television can help develop a better understanding of the creation, construction, and strengthening of limits and boundaries separating enclave cultures from the world. Based on questionnaires containing both closed- and open-ended questions completed by 82 participants, approximately half from each community, I argue that both communities can be understood as interpretive communities that negatively interpret not only television content, like other religious communities, but also the medium itself. Their various negative interpretive strategies is discussed and the article shows how they are part of an “us-versus-them” attitude created to mark the boundaries and walls that enclave cultures build around themselves. The comparison between the two communities found only a few small differences but one marked similarity: The communities perceive avoidance of a tool for communication, in this case television, as part of the communities’ sharing, participation, and common culture
Negotiating agency: Amish and ultra-Orthodox women’s responses to the Internet
This study explores how women in two devout religious communities cope with the Internet and its apparent incompatibility with their communities’ values and practices. Questionnaires containing both closed and open-ended questions were completed by 82 participants, approximately half from each community. While their discourses included similar framings of danger and threat, the two groups manifested different patterns of Internet use (and nonuse). Rigorous adherence to religious dictates is greatly admired in these communities, and the women take pride in manipulating their status in them. Their agency is reflected in how they negotiate the tension inherent in their roles as both gatekeepers and agents-of-change, which are analyzed as valuable currencies in their cultural and religious markets
Thromboembolic Events Associated with Thalidomide and Multimodality Therapy for Soft Tissue Sarcomas: Results of RTOG 0330
Introduction. RTOG 0330 was developed to address the toxicity of RTOG 9514 and to add thalidomide (THAL) to MAID chemoradiation for intermediate/high grade soft tissue sarcomas (STSs) and to preoperative radiation (XRT) for low-grade STS. Methods. Primary/locally recurrent extremity/trunk STS: ≥8 cm, intermediate/high grade (cohort A): >5 cm, low grade (cohort B). Cohort A: 3 cycles of neoadjuvant MAID, 2 cycles of interdigitated THAL (200 mg/day)/concurrent 22 Gy XRT, resection, 12 months of adjuvant THAL. Cohort B: neoadjuvant THAL/concurrent 50 Gy XRT, resection, 6 months of adjuvant THAL. Planned accrual 44 patients. Results. 22 primary STS patients (cohort A/B 15/7). Cohort A/B: median age of 49/47 years; median tumor size 12.8/10 cm. 100% preoperative THAL/XRT and surgical resection. Three cycles of MAID were delivered in 93% cohort A. Positive margins: 27% cohort A/29% cohort B. Adjuvant THAL: 60% cohort A/57% cohort B. Grade 3/4 venous thromboembolic (VTE) events: 40% cohort A (1 catheter thrombus and 5 DVT or PE) versus 0% cohort B. RTOG 0330 closed early due to cohort A VTE risk and cohort B poor accrual. Conclusion. Neoadjuvant MAID with THAL/XRT was associated with increased VTE events not seen with THAL/XRT alone or in RTOG 9514 with neoadjuvant MAID/XRT
The Allen Telescope Array: The First Widefield, Panchromatic, Snapshot Radio Camera for Radio Astronomy and SETI
The first 42 elements of the Allen Telescope Array (ATA-42) are beginning to
deliver data at the Hat Creek Radio Observatory in Northern California.
Scientists and engineers are actively exploiting all of the flexibility
designed into this innovative instrument for simultaneously conducting surveys
of the astrophysical sky and conducting searches for distant technological
civilizations. This paper summarizes the design elements of the ATA, the cost
savings made possible by the use of COTS components, and the cost/performance
trades that eventually enabled this first snapshot radio camera. The
fundamental scientific program of this new telescope is varied and exciting;
some of the first astronomical results will be discussed.Comment: Special Issue of Proceedings of the IEEE: "Advances in Radio
Telescopes", Baars,J. Thompson,R., D'Addario, L., eds, 2009, in pres
BIMA Array Detections of HCN in Comets LINEAR (C/2002 T7) and NEAT (C/2001 Q4)
We present interferometric detections of HCN in comets LINEAR (C/2002 T7) and
NEAT (C/2001 Q4) with the Berkeley-Illinois-Maryland Association (BIMA) Array.
With a 25.4"x20.3" synthesized beam around Comet LINEAR and using a variable
temperature and outflow velocity (VTOV) model, we found an HCN column density
of N_T=6.4+-2.1x10^12 cm^-2, and a production rate of Q(HCN)=6.5+-2.2x10^26
s^-1, giving a production rate ratio of HCN relative to H_2O of ~3.3+-1.1x10^-3
and relative to CN of ~4.6+-1.5. With a 21.3"x17.5" synthesized beam around
Comet NEAT and using a VTOV model, we found an HCN column density of
N_T=8.5+-4.5x10^11 cm^-2, and a production rate of Q(HCN)=8.9+-4.7x10^25 s^-1,
giving a production rate ratio of HCN relative to H_2O of ~7.4+-3.9x10^-4 and
relative to CN of ~0.3+-0.2. For both comets, the production rates relative to
H_2O are similar to those found in previous comet observations. For Comet
LINEAR the production rate relative to CN is consistent with HCN being the
primary parent species of CN, while for Comet NEAT it is too low for this to be
the case.Comment: 20 pages, 2 figures, to be published in the Astrophysical Journa
Millisecond Imaging of Radio Transients with the Pocket Correlator
We demonstrate a signal processing concept for imaging the sky at millisecond
rates with radio interferometers. The "Pocket Correlator" (PoCo) correlates the
signals from multiple elements of a radio interferometer fast enough to image
brief, dispersed pulses. By the nature of interferometry, a millisecond
correlator functions like a large, single-dish telescope, but with improved
survey speed, spatial localization, calibration, and interference rejection. To
test the concept, we installed PoCo at the Allen Telescope Array (ATA) to
search for dispersed pulses from the Crab pulsar, B0329+54, and M31 using
total-power, visibility-based, and image-plane techniques. In 1.7 hours of
observing, PoCo detected 191 giant pulses from the Crab pulsar brighter than a
typical 5 sigma sensitivity limit of 60 Jy over pulse widths of 3 milliseconds.
Roughly 40% of pulses from pulsar B0329+54 were detected by using novel
visibility-based techniques. Observations of M31 constrain the rate of pulses
brighter than 190 Jy in a three degree region surrounding the galaxy to
<4.3/hr. We calculate the computational demand of various visibility-based
pulse search algorithms and demonstrate how compute clusters can help meet this
demand. Larger implementations of the fast imaging concept will conduct blind
searches for millisecond pulses in our Galaxy and beyond, providing a valuable
probe of the interstellar/intergalactic media, discovering new kinds of radio
transients, and localizing them to constrain models of their origin.Comment: 13 pages, accepted to Ap
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