Abstract
Flat-spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies but only rarely emit detectable fluxes of TeV gamma rays, typically during bright GeV flares. We explore the ...gamma-ray variability and spectral characteristics of three FSRQs that have been observed at GeV and TeV energies by Fermi-LAT and VERITAS, making use of almost 100 hr of VERITAS observations spread over 10 yr: 3C 279, PKS 1222+216, and Ton 599. We explain the GeV flux distributions of the sources in terms of a model derived from a stochastic differential equation describing fluctuations in the magnetic field in the accretion disk and estimate the timescales of magnetic flux accumulation and stochastic instabilities in their accretion disks. We identify distinct flares using a procedure based on Bayesian blocks and analyze their daily and subdaily variability and gamma-ray energy spectra. Using observations from VERITAS, as well as Fermi, Swift, and the Steward Observatory, we model the broadband spectral energy distributions of PKS 1222+216 and Ton 599 during very high energy (VHE)–detected flares in 2014 and 2017, respectively, strongly constraining the jet Doppler factors and gamma-ray emission region locations during these events. Finally, we place theoretical constraints on the potential production of PeV-scale neutrinos during these VHE flares.
Flat spectrum radio quasars (FSRQs) are the most luminous blazars at GeV energies, but only rarely emit detectable fluxes of TeV gamma rays, typically during bright GeV flares. We explore the ...gamma-ray variability and spectral characteristics of three FSRQs that have been observed at GeV and TeV energies by Fermi-LAT and VERITAS, making use of almost 100 hours of VERITAS observations spread over 10 years: 3C 279, PKS 1222+216, and Ton 599. We explain the GeV flux distributions of the sources in terms of a model derived from a stochastic differential equation describing fluctuations in the magnetic field in the accretion disk, and estimate the timescales of magnetic flux accumulation and stochastic instabilities in their accretion disks. We identify distinct flares using a procedure based on Bayesian blocks and analyze their daily and sub-daily variability and gamma-ray energy spectra. Using observations from VERITAS as well as Fermi, Swift, and the Steward Observatory, we model the broadband spectral energy distributions of PKS 1222+216 and Ton 599 during VHE-detected flares in 2014 and 2017, respectively, strongly constraining the jet Doppler factors and gamma-ray emission region locations during these events. Finally, we place theoretical constraints on the potential production of PeV-scale neutrinos during these VHE flares.
Most commercial and university substrate testing laboratories' recommended floriculture nutritional values are based on the saturated media extract (SME) method. With the recent gain in popularity of ...pour-through nutritional monitoring, alternative recommended values are needed for nutrient analyses based on pour-through extracts. Pour-through nutritional values were compared to the SME values to develop calibration curves and recommended nutritional values. Euphorbia pulcherrima 'Freedom Red' Willd. ex Klotzch. were grown for two consecutive growing seasons in 16.5 cm plastic pots with Fafard 4 P root substrate and fertigated with 200, 300, or 400 mg.L(-1) N from a 13N-0.88P-10.8K fertilizer. Linear relationships existed and inverse calibration curves for pour-through and SME comparisons were developed for (r2): EC (0.98), NO3(-) (0.98), P (0.97 to 0.99), K (0.99), Ca (0.94 to 0.97), and Mg (0.91). In addition, recommended pour-through substrate value ranges were developed for comparison with SME values. The established calibration curves and pour-through substrate value ranges will allow substrate-testing laboratories to make nutritional recommendations based on pour-through extractions.
The time between irrigation and PourThru sampling had not been extensively examined for affects on pH, electrical conductivity (EC), and leachate volume in greenhouse production. A greenhouse study ...with 16.5 and 19.2 cm wide containers using Fafard 4P and Metro Mix 320 soilless substrates was implemented, and PourThru leachates were extracted and tested for pH, EC, and volume at 15, 30, 60, 120, and 240 minutes after irrigation. Substrates and pot sizes affected PourThru pH and EC; however, timing did not affect these values in this study. The elapsed time between irrigation and sampling affected leachate volumes and mass wetness of the substrates such that values decreased when 120 or 240 minutes elapsed from irrigation to sampling. Based upon the fluctuations in leachate volumes and mass wetness values, it is recommended that 60 minutes elapse from time of irrigation to PourThru sampling. Sixty minutes is sufficient time to allow for nutrient equilibration so the greenhouse crop producers can obtain a representative sample of the plant available nutrient status, yet maintain sufficient moisture status to prevent EC shifts due to moisture content variation leachate volumes from becoming too low.
Flurprimidol substrate drenches at 2 mg a.i. per 15.3 cm (6 inch) pot were more effective on 'Pacino' pot sunflowers (Helianthus annuus) than flurprimidol foliar sprays of greater than or equal to 30 ...mg.L(-1) (ppm), but both treatments resulted in significantly smaller plant height and diameter than the control (28,350 mg = 1 oz). Flurprimidol drenches of 2 mg were comparable in controlling plant height and diameter to the commercial drench recommendations of 2 mg paclobutrazol. The commercial recommendation of daminozide foliar sprays at 4000 mg.L(-1) had greater efficacy in controlling plant height than the most effective flurprimidol foliar sprays of greater than or equal to 30 mg.L(-1). Daminozide had no effect on plant diameter, while flurprimidol resulted in narrower plants. Flurprimidol and paclobutrazol drenches of 2 mg offer the economic advantage to producers of increased plant density on greenhouse benches, while plants treated with daminozide would require a greater amount of bench area. Producers should evaluate the trade-offs between the added costs of a drench vs. the higher cost-per-square-foot-week of production space required for a daminozide foliar spray. With these options, producers can select a plant growth regulator (PGR) that best fits their production and market requirements.
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