2 research outputs found
The sub-TeV transient Gamma-Ray sky: challenges and opportunities
The detection of gravitational waves and neutrinos from astrophysical sources
with gamma-ray counterparts officially started the era of Multi-Messenger
Astronomy. Their transient and extreme nature implies that monitoring the VHE
sky is fundamental to investigate the non-electromagnetic signals. However, the
limited effective area of space-borne instruments prevents observations above a
few hundred GeV, while the small field of view and low duty cycle of IACTs make
them unsuited for extensive monitoring activities and prompt response to
transients. Extensive Air Shower arrays (EAS) can provide a large field of
view, a wide effective area and a very high duty cycle. Their main difficulty
is the distinction between gamma-ray and cosmic-ray initiated air showers,
especially below the TeV range. Here we present some case studies stressing the
importance that a new EAS array in the Southern Hemisphere will be able to
survey the sky from below 100 GeV up to several TeV. In the energy domain
between 100 and 400 GeV we expect the strongest electromagnetic signatures of
the acceleration of ultra-relativistic particles in sources like SNRs, blazar
jets and gamma-ray bursts, as recently proved by IACT observations. This
spectral window is also crucial to understand the Universe opacity to high
energy radiation, thus providing constraints on the cosmological parameters. We
will discuss the implications of VHE radiation on the mechanisms at work and we
will focus on the advantages resulting from the ability to monitor the energy
window lying between the domain of space-borne detectors and ground-based
facilities
Cultivation of marine shrimp in biofloc technology (BFT) system under different water alkalinities
AbstractThe aim of this study was to evaluate the influence of different levels of alkalinity for the superintensive cultivation of marine shrimp Litopenaeus vannamei in biofloc system. A total of 12 experimental circular units of 1000L were used supplied with 850L water from a nursery, populated at a density of 165 shrimps.m–3 and average weight of 5.6 g. The treatments, in triplicate, consisted in four levels of alkalinity in the water: 40, 80, 120 and 160 mg.L–1 of calcium carbonate. To correct the alkalinity was used calcium hydroxide (CaOH). It was observed a decrease in pH of the water in the treatments with lower alkalinity (p<0.05). The total suspended settleable solids were also lower in the treatment of low alkalinity. No significant difference was observed in other physico-chemical and biological parameters in the water quality assessed, as well as the zootechnical parameters of cultivation between treatments (p≥0.05). The results of survival and growth rate of shrimps were considered suitable for the cultivation system used in the different treatments. The cultivation of marine shrimp Litopenaeus vannamei in biofloc at density of 165 shrimps.m–3 can be performed in waters with alkalinity between 40 and 160 mg.L–1 of CaCO3, without compromising the zootechnical indexes of cultivation