ABSTRACT We present results of a stellar occultation by the Jupiter Trojan asteroid Patroclus and its nearly equal size moon, Menoetius. The geocentric mid-time of the event was 2013 October 21 ...06:43:02 UT. Eleven sites out of 36 successfully recorded an occultation. Seven chords across Patroclus yielded an elliptical limb fit of 124.6 by 98.2 km. There were six chords across Menoetius that yielded an elliptical limb fit of 117.2 by 93.0 km. There were three sites that got chords on both objects. At the time of the occultation we measured a separation of 664.6 km (0.247 arcsec) and a position angle for Menoetius of 265 7 measured eastward from J2000 north. Combining this occultation data with previous light curve data, the axial ratios of both objects are 1.3 : 1.21 : 1, indicative of a mostly oblate ellipsoid with a slight asymmetry in its equatorial projection. The oblate shape is not an equilibrium shape for the current rotation period, but would be if it were rotating with an ∼8 h period. This faster period is consistent with a pre-evolved state of the system with an orbital separation that is 50% smaller. Our best estimate of the system density is 0.88 g cm−3.
The composition of ultra-high-energy cosmic rays is measured with the High Resolution Fly's Eye cosmic-ray observatory data using the X sub(max) technique. Data were collected in stereo between 1999 ...November and 2001 September. The data are reconstructed with well-determined geometry. Measurements of the atmospheric transmission are incorporated in the reconstruction. The detector resolution is found to be 30 g cm super(-2) in X sub(max) and 13% in energy. The X sub(max) elongation rate between 10 super(18.0) and 10 super(19.4) eV is measured to be 54.5 c 6.5 (stat) c 4.5 (sys) g cm super(-2) per decade. This is compared with predictions using the QGSJet01 and SIBYLL 2.1 hadronic interaction models for both protons and iron nuclei. CORSIKA-generated extensive air showers are incorporated directly into a detailed detector Monte Carlo program. The elongation rate and the X sub(max) distribution widths are consistent with a constant or slowly changing and predominantly light composition. A simple model containing only protons and iron nuclei is compared with QGSJet and SIBYLL. The best agreement between the model and the data is for 80% protons for QGSJet and 60% protons for SIBYLL.
Gadfly petrels (genus
Pterodroma
) are one of the most threatened groups of birds. They are exceptionally well adapted to forage over enormous areas to maximize chances of encountering prey. Their ...wide-ranging travel, extensive use of oceanic habitats beyond national jurisdictions (the high seas), and limited information on their at-sea distributions and foraging ecology pose several management challenges. Here, we examined the foraging distributions and habitat preferences of three gadfly petrels that breed on Phillip Island (Norfolk Island Group), in the southwest Pacific Ocean, and tested the ability of species distribution models (SDMs) to predict important marine habitats. GPS loggers were deployed in 2018 and 2019 on chick-provisioning black-winged petrels (
P. nigripennis
) and white-necked petrels (
P. cervicalis
) and in 2020 on Kermadec petrels (
P. neglecta
), and hidden Markov models (HMMs) were used to estimate behavioral states across 387 foraging trips. SDMs were built using six algorithms and the predictive performance of models constructed using conventional random cross-validation (CV) was compared to those constructed with spatially independent CV. All three species demonstrated dual-foraging strategies with short trips closer to the colony and longer, presumably self-provisioning, trips with maximum distances from the colony of several thousand kilometers for black-winged and white-necked petrels. Foraging areas of each species were distinctly partitioned across the Tasman Sea during long trips, but there was high overlap during short trips. Black-winged and white-necked petrels exhibited area-restricted search foraging behavior throughout their foraging ranges which spanned almost the entire Tasman Sea and into the western Pacific, whereas the foraging range of Kermadec petrels was restricted closer to the colony. Approximately half of each species’ foraging range extended into the high seas. Response curves and variable importance between the two SDM CV approaches were similar, suggesting that model fitting was robust to the CV approach. However, evaluation using spatially independent CV indicated that generalizability of ensemble SDMs to new data ranged from poor to fair for all three species. This suggests that the maximal-area foraging strategy of gadfly petrels (whereby they search opportunistically for resources across expansive oceanic habitats) results in weak or wide associations with environmental features making predicting important habitats extremely challenging.
The Sydney University Giant Air-shower Recorder(SUGAR) measured the energy spectrum of ultra-high-energy cosmic rays reconstructed from muon detector reading. Comparison of their spectra SUGAR and ...Pierre Auger Observatory allows us to reconstruct the empirical dependence of the number of muons in a vertical shower on the primary energy for energies between 10
17
and 10
18
eV. We compared this dependence with the predictions of hadronic interaction models QGSJET-II-04, EPOS-LHC and SIBYLL-2.3c. In addition, we analyzed the response of the array of muon detectors in order to determine the slope of the muon lateral distribution function. It is important to understand how much the number of muons differs from the predictions of modeling at different distances from the shower axis.
Nectarin I, a protein that accumulates in the nectar of Nicotiana sp. , was determined to contain superoxide dismutase activity by colorimetric and in-gel assays. This activity was found to be ...remarkably thermostable. Extended incubations at temperatures up to 90 degrees C did not diminish the superoxide dismutase activity of nectarin I. This attribute allowed nectarin I to be purified to homogeneity by heat denaturation of the other nectar proteins. By SDS-polyacrylamide gel electrophoresis, nectarin I appeared as a 29-kDa monomer. If the protein sample was not boiled prior to loading the gel, then nectarin I migrated as 165-kDa oligomeric protein. By matrix-assisted laser desorption/ionization time-of-flight mass spectrometry, the protomer subunit was found to be a 22.5-kDa protein. Purified nectarin I contained 0.5 atoms of manganese/monomer, and the superoxide dismutase activity of nectarin I was not inhibited by either H(2)O(2) or NaCN. Following denaturation, the superoxide dismutase activity was restored after Mn(2+) addition. Addition of Fe(2+), Cu(2+), Zn(2+), and Cu(2+)/Zn(2+) did not restore superoxide dismutase activity. The quaternary structure of the reconstituted enzyme was examined, and only tetrameric and pentameric aggregates were enzymatically active. The reconstituted enzyme was also shown to generate H(2)O(2). Putative nectarin I homologues were found in the nectars of several other plant species.
We have measured the cosmic ray spectrum at energies above 1017eV using the two air fluorescence detectors of the High Resolution Fly's Eye experiment operating in monocular mode. We describe the ...detector, PMT and atmospheric calibrations, and the analysis techniques for the two detectors. We fit the spectrum to models describing galactic and extragalactic sources. Our measured spectrum gives an observation of a feature known as the “ankle” near 3×1018eV, and strong evidence for a suppression near 6×1019eV.
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