54 research outputs found
A Search for Technosignatures Around 11,680 Stars with the Green Bank Telescope at 1.15-1.73 GHz
We conducted a search for narrowband radio signals over four observing
sessions in 2020-2023 with the L-band receiver (1.15-1.73 GHz) of the 100 m
diameter Green Bank Telescope. We pointed the telescope in the directions of 62
TESS Objects of Interest, capturing radio emissions from a total of ~11,680
stars and planetary systems in the ~9 arcminute beam of the telescope. All
detections were either automatically rejected or visually inspected and
confirmed to be of anthropogenic nature. In this work, we also quantified the
end-to-end efficiency of radio SETI pipelines with a signal injection and
recovery analysis. The UCLA SETI pipeline recovers 94.0% of the injected
signals over the usable frequency range of the receiver and 98.7% of the
injections when regions of dense RFI are excluded. In another pipeline that
uses incoherent sums of 51 consecutive spectra, the recovery rate is ~15 times
smaller at ~6%. The pipeline efficiency affects calculations of transmitter
prevalence and SETI search volume. Accordingly, we developed an improved Drake
Figure of Merit and a formalism to place upper limits on transmitter prevalence
that take the pipeline efficiency and transmitter duty cycle into account.
Based on our observations, we can state at the 95% confidence level that fewer
than 6.6% of stars within 100 pc host a transmitter that is detectable in our
search (EIRP > 1e13 W). For stars within 20,000 ly, the fraction of stars with
detectable transmitters (EIRP > 5e16 W) is at most 3e-4. Finally, we showed
that the UCLA SETI pipeline natively detects the signals detected with AI
techniques by Ma et al. (2023).Comment: 22 pages, 9 figures, submitted to AJ, revise
An Unexpected Ring-opening in the Reissert Reaction On 2,3-diphenylquinoxaline-n-oxide
When quinoxaline-N-oxide 1 is reacted with KCN and benzoyl chloride in water (the Reissert reaction) or methanol, the products are 2-,5- and 6- chloroquinoxaline (the latter being the major product: 42±6 %) and small amounts of 2-cyanoquinoxaline. Using three equivalents of trimethylsilyl cyanide instead of KCN, and dichloromethane as the solvent, leads to a 72 % yield of 2-cyanoquinoxaline. The reaction of trimethylsilyl cyanide and benzoyl chloride with 2,3-diphenylquinoxaline-N-oxide 2 leads to an unexpected ring-opening product 13; its structure is based on spectroscopic data and on an X-ray crystallographic analysis
Synthesis of a series of racemic tetraorganotin compounds
info:eu-repo/semantics/publishe
Organometallic compounds. Part IX: Synthesis of a series of racemic tetraorganotin compounds
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Laser-induced photoelectrochemical transients at a dye solution-SnO2 interface
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Influence of organic sulfur reducing agents on the photoanodic behavior of polycrystalline CdS. Improvement of the photoelectrochemical characteristics
Symposia organisés par The Electrochemical Societyinfo:eu-repo/semantics/publishe
Diastereotopic nonequivalence in organotin compounds: Preliminary communication
SCOPUS: ar.jinfo:eu-repo/semantics/publishe
Possible structural criterion for phenomenon of specific nucleophilic coordination at a metal atom
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