459 research outputs found

    Acoustically evoked potentials in two cephalopods inferred using the auditory brainstem response (ABR) approach

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    It is still a matter of debate whether cephalopods can detect sound frequencies above 400 Hz. So far there is no proof for the detection of underwater sound above 400 Hz via a physiological approach. The controversy of whether cephalopods have a sound detection ability above 400 Hz was tested using the auditory brainstem response (ABR) approach, which has been successfully applied in fish, crustaceans, amphibians, reptiles and birds. Using ABR we found that auditory evoked potentials can be obtained in the frequency range 400 to 1500 Hz (Sepiotheutis lessoniana) and 400 to 1000 Hz (Octopus vulgaris), respectively. The thresholds of S. lessoniana were generally lower than those of O. vulgaris

    Low early ototoxicity rates for pediatric medulloblastoma patients treated with proton radiotherapy

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    <p>Abstract</p> <p>Background</p> <p>Hearing loss is common following chemoradiotherapy for children with medulloblastoma. Compared to photons, proton radiotherapy reduces radiation dose to the cochlea for these patients. Here we examine whether this dosimetric advantage leads to a clinical benefit in audiometric outcomes.</p> <p>Methods</p> <p>From 2006-2009, 23 children treated with proton radiotherapy for medulloblastoma were enrolled on a prospective observational study, through which they underwent pre- and 1 year post-radiotherapy pure-tone audiometric testing. Ears with moderate to severe hearing loss prior to therapy were censored, leaving 35 ears in 19 patients available for analysis.</p> <p>Results</p> <p>The predicted mean cochlear radiation dose was 30 <sup>60</sup>Co-Gy Equivalents (range 19-43), and the mean cumulative cisplatin dose was 303 mg/m<sup>2 </sup>(range 298-330). Hearing sensitivity significantly declined following radiotherapy across all frequencies analyzed (<it>P </it>< 0.05). There was partial sparing of mean post-radiation hearing thresholds at low-to-midrange frequencies and, consequently, the rate of high-grade (grade 3 or 4) ototoxicity at 1 year was favorable (5%). Ototoxicity did not correlate with predicted dose to the auditory apparatus for proton-treated patients, potentially reflecting a lower-limit threshold for radiation effect on the cochlea.</p> <p>Conclusions</p> <p>Rates of high-grade early post-radiation ototoxicity following proton radiotherapy for pediatric medulloblastoma are low. Preservation of hearing in the audible speech range, as observed here, may improve both quality of life and cognitive functioning for these patients.</p

    First Acetic Acid Survey with CARMA in Hot Molecular Cores

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    Acetic acid (CH3_3COOH) has been detected mainly in hot molecular cores where the distribution between oxygen (O) and nitrogen (N) containing molecular species is co-spatial within the telescope beam. Previous work has presumed that similar cores with co-spatial O and N species may be an indicator for detecting acetic acid. However, does this presumption hold as higher spatial resolution observations become available of large O and N-containing molecules? As the number of detected acetic acid sources is still low, more observations are needed to support this postulate. In this paper, we report the first acetic acid survey conducted with the Combined Array for Research in Millimeter-wave Astronomy (CARMA) at 3 mm wavelengths towards G19.61-0.23, G29.96-0.02 and IRAS 16293-2422. We have successfully detected CH3_3COOH via two transitions toward G19.61-0.23 and tentatively confirmed the detection toward IRAS 16293-2422 A. The determined column density of CH3_3COOH is 2.0(1.0)×1016\times 10^{16} cm2^{-2} and the abundance ratio of CH3_3COOH to methyl formate (HCOOCH3_3) is 2.2(0.1)×101\times 10^{-1} toward G19.61-0.23. Toward IRAS 16293 A, the determined column density of CH3_3COOH is \sim 1.6 ×1015\times 10^{15} cm2^{-2} and the abundance ratio of CH3_3COOH to methyl formate (HCOOCH3_3) is \sim 1.0 ×101\times 10^{-1} both of which are consistent with abundance ratios determined toward other hot cores. Finally, we model all known line emission in our passband to determine physical conditions in the regions and introduce a new metric to better reveal weak spectral features that are blended with stronger lines or that may be near the 1-2σ\sigma detection limit.Comment: 28 pages, 8 figures, accepted for publication in the ApJ; Revised citation in session 2, references remove

    Performance of two Askaryan Radio Array stations and first results in the search for ultra-high energy neutrinos

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    Ultra-high energy neutrinos are interesting messenger particles since, if detected, they can transmit exclusive information about ultra-high energy processes in the Universe. These particles, with energies above 1016eV10^{16}\mathrm{eV}, interact very rarely. Therefore, detectors that instrument several gigatons of matter are needed to discover them. The ARA detector is currently being constructed at South Pole. It is designed to use the Askaryan effect, the emission of radio waves from neutrino-induced cascades in the South Pole ice, to detect neutrino interactions at very high energies. With antennas distributed among 37 widely-separated stations in the ice, such interactions can be observed in a volume of several hundred cubic kilometers. Currently 3 deep ARA stations are deployed in the ice of which two have been taking data since the beginning of the year 2013. In this publication, the ARA detector "as-built" and calibrations are described. Furthermore, the data reduction methods used to distinguish the rare radio signals from overwhelming backgrounds of thermal and anthropogenic origin are presented. Using data from only two stations over a short exposure time of 10 months, a neutrino flux limit of 3106GeV/(cm2 s sr)3 \cdot 10^{-6} \mathrm{GeV} / (\mathrm{cm^2 \ s \ sr}) is calculated for a particle energy of 10^{18}eV, which offers promise for the full ARA detector.Comment: 21 pages, 34 figures, 1 table, includes supplementary materia

    ASME 88-1CE-6, presented at the Energy-Source Technology Conference and Exhibition

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    Fig. 5 Velocity versus anguiar dispiacement (V8 engine) attained from the inertia value using the least squares method is consistently smaller than the reference data, and eventually leads to larger velocity estimation error than the average method Some precautions are needed when applying the least squares method to compute the engine inertia value. For engines operating at high speeds, the velocity related term in Eq. (1) could be very large compared with the other terms. This could result in some confusing situations. For instance, engines might decelerate over some portion of the engine operation cycle while the net external torque accelerating the engine is positive; or engines might accelerate while the net external torque is negative. These operation situations might make negative engine inertia value estimations possible, which is not feasible. In other cases, engines might have very small accelerations or decelerations while net external torque is moderate to large. For these cases, the calculation might lead to very large engine inertia values, which is not feasible either. The cases mentioned above are most likely to occur when engines operate at high speeds. Those erroneous data corresponding the situations above must be Altered out before applying the least squares method to the engine inertia value computation. The criterion used in this study to decide whether data should be used to calculate the engine inertia values is to check the quotient of the net external torque divided by the engine acceleration. This quotient should not be too large or too small relative to the average engine inertia value. Those data whose quotient are significantly away from the average engine inertia value are likely to fall in the situations mentioned above, and those data should not be used in the engine inertia value computation. V Conclusions The engine inertia values calculated by the least squares method guarantees minimum acceleration and velocity estimation errors for engine operating at constant average velocities. As for monotonically accelerating and decelerating engines, simulations in the study show that the engine model with an inertia calculated by the least squares method leads to smaller estimation errors in acceleration but larger estimation errors in velocity than the constant inertia engine model with an average inertia. It is important that the user knows the type of engine, its range of operation, and the type of loading in order to calculate an optimal engine inertia for the control purpose. This study has provided guidance in understanding the effects of engine performance variables and in calculating an appropriate estimate for the engine inertia. Acknowledgment

    White Paper: ARIANNA-200 high energy neutrino telescope

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    The proposed ARIANNA-200 neutrino detector, located at sea-level on the Ross Ice Shelf, Antarctica, consists of 200 autonomous and independent detector stations separated by 1 kilometer in a uniform triangular mesh, and serves as a pathfinder mission for the future IceCube-Gen2 project. The primary science mission of ARIANNA-200 is to search for sources of neutrinos with energies greater than 10^17 eV, complementing the reach of IceCube. An ARIANNA observation of a neutrino source would provide strong insight into the enigmatic sources of cosmic rays. ARIANNA observes the radio emission from high energy neutrino interactions in the Antarctic ice. Among radio based concepts under current investigation, ARIANNA-200 would uniquely survey the vast majority of the southern sky at any instant in time, and an important region of the northern sky, by virtue of its location on the surface of the Ross Ice Shelf in Antarctica. The broad sky coverage is specific to the Moore's Bay site, and makes ARIANNA-200 ideally suited to contribute to the multi-messenger thrust by the US National Science Foundation, Windows on the Universe - Multi-Messenger Astrophysics, providing capabilities to observe explosive sources from unknown directions. The ARIANNA architecture is designed to measure the angular direction to within 3 degrees for every neutrino candidate, which too plays an important role in the pursuit of multi-messenger observations of astrophysical sources

    The Payload for Ultrahigh Energy Observations (PUEO): A White Paper

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    The Payload for Ultrahigh Energy Observations (PUEO) long-duration balloon experiment is designed to have world-leading sensitivity to ultrahigh-energy neutrinos at energies above 1 EeV. Probing this energy region is essential for understanding the extreme-energy universe at all distance scales. PUEO leverages experience from and supersedes the successful Antarctic Impulsive Transient Antenna (ANITA) program, with an improved design that drastically improves sensitivity by more than an order of magnitude at energies below 30 EeV. PUEO will either make the first significant detection of or set the best limits on ultrahigh-energy neutrino fluxes.Comment: 37 pages, 17 figures. Minor updates, version submitted to JINS
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