4,819 research outputs found
Interagency telemetry arraying for Voyager-Neptune encounter
The reception capability of the Deep Space Network (DSN) has been improved over the years by increasing both the size and number of antennas at each complex to meet spacecraft-support requirements. However, even more aperture was required for the final planetary encounters of the Voyager 2 spacecraft. This need was met by arraying one radio astronomy observatory with the DSN complex in the United States and another with the complex in Australia. Following a review of augmentation for the Uranus encounter, both the preparation at the National Radio Astronomy (NRAO) Very Large Array (VLA) and the Neptune encounter results for the Parkes-Canberra and VLA-Goldstone arrays are presented
Genomics goes chromosomal to explore the wheat genome
OBJECTIVES: The implant design and surface modification are independent conditions that can alter the implant bone response. The objective of this study is to compare the bone response to roughened tapered and cylindrical screw-type implants with and without hydroxyapatite (HA) surface coating in the femoral trabecular bone of rabbits. MATERIAL AND METHOD: Thirty-two implants (8 x 3.5 mm) consisting of four different types (eight implants in each group), that is, tapered implants, cylindrical implants, HA-coated tapered implants, and HA-coated cylindrical implants were installed in the femoral condyle of 16 rabbits. After 8 weeks of healing, the femoral condyles were retrieved and studied histologically. The bone-to-implant contact percentage was assessed and analyzed statistically. Results : The histomorphometric analysis revealed that the bone-to-implant contact (BIC) values seemed to be higher for HA-coated tapered implants (65.62 +/- 13.02) followed by cylindrical non-coated implants. All four types of implants showed wide distribution of BIC with no statistical significance between different types of implants. CONCLUSION: It can be concluded that under the current experimental conditions, implant design and surface composition had little effect on the bone-to-implant interface
Recurrent Neutrino Emission from Supermassive Black Hole Mergers
The recent detection of possible neutrino emission from the blazar TXS
0506+056 was the first high-energy neutrino associated with an astrophysical
source, making this special type of active galaxies promising neutrino
emitters. The fact that two distinct episodes of neutrino emission were
detected with a separation of around 3 years suggests that emission could be
periodic. Periodic emission is expected from supermassive binary black hole
systems due to jet precession close to the binary's merger. Here we show that
if TXS 0506+056 is a binary source then the next neutrino flare could occur
before the end of 2021. We derive the binary properties that would lead to the
detection of gravitational waves from this system by LISA. Our results for the
first time quantify the time scale of these correlations for the example of TXS
0506+056, providing clear predictions for both the neutrino and
gravitational-wave signatures of such sources.Comment: 6 pages, 3 figures, submitte
Conservação a médio-longo prazo de sementes de Piper aduncum e Piper hispidinervum em temperaturas subzero e criogênica.
Supercooled Liquid Dynamics Studied via Shear-Mechanical Spectroscopy
We report dynamical shear-modulus measurements for five glass-forming liquids
(pentaphenyl trimethyl trisiloxane, diethyl phthalate, dibutyl phthalate,
1,2-propanediol, and m-touluidine). The shear-mechanical spectra are obtained
by the piezoelectric shear-modulus gauge (PSG) method. This technique allows
one to measure the shear modulus ( Pa) of the liquid within a
frequency range from 1 mHz to 10 kHz. We analyze the frequency-dependent
response functions to investigate whether time-temperature superposition (TTS)
is obeyed. We also study the shear-modulus loss-peak position and its
high-frequency part. It has been suggested that when TTS applies, the
high-frequency side of the imaginary part of the dielectric response decreases
like a power law of the frequency with an exponent -1/2. This conjecture is
analyzed on the basis of the shear mechanical data. We find that TTS is obeyed
for pentaphenyl trimethyl trisiloxane and in 1,2-propanediol while in the
remaining liquids evidence of a mechanical process is found. Although
the the high-frequency power law behavior of the shear-loss
may approach a limiting value of when lowering the temperature, we
find that the exponent lies systematically above this value (around 0.4). For
the two liquids without beta relaxation (pentaphenyl trimethyl trisiloxane and
1,2-propanediol) we also test the shoving model prediction, according to which
the the relaxation-time activation energy is proportional to the instantaneous
shear modulus. We find that the data are well described by this model.Comment: 7 pages, 6 figure
Neurino Cadence of TXS~0506+056 Consistent with Supermassive Binary Origin
On September 18, 2022, an alert by ceCube indicated that a ~170TeV neutrino
arrived in directional coincidence with the blazar TXS 0506+056. This event
adds to two previous ones: a neutrino alert from its direction on September 22,
2017, and a 3sigma signature of a dozen neutrinos in 2014/2015. deBruijn 2020
showed that these two previous neutrino emission episodes could be due to a
supermassive binary black hole (SMBBH) where jet precession close to final
coalescence results in periodic emission. This model predicted a new emission
episode consistent with the September 18, 2022 neutrino observation. Here, we
show that the neutrino cadence of TXS 0506+056 is consistent with a SMBBH
origin with mass ratios q3e8Msun. For the
first time, we calculate the characteristic strain of the gravitational wave
emission of the binary, and show that the merger could be detectable by LISA
for black hole masses <5e8Msun if the mass ratios are in the range 0.1<q<0.3.
We predict that there can be a neutrino flare existing in the still to be
analyzed IceCube data peaking some time between 08/2019 and 01/2021 if a
precessing jet is responsible for all three detected emission episodes. The
next flare is expected to peak in the period 01/2023 to 08/2026. Further
observation will make it possible to constrain the mass ratio as a function of
the black hole mass more precisely and would open the window toward the
preparation of the detection of SMBBH mergers.Comment: 10 pages, 2 figures, submitte
Multiplicação de calos embriogênicos de dendezeiro (Elaeis guineensis) em biorreatores de imersão temporária.
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