35 research outputs found
Feasibility of compensatory growth in early juveniles of "red claw" crayfish Cherax quadricarinatus under high density conditions
The aim of this work is to study the feasibility to induce compensatory growth in Cherax quaricarinatus crayfish at an early stage of development under high density, the typical conditions of nursery phase. An advantageous characteristic of this species is the capacity to face temporary starvation, especially at early stages of development. This would help to design feeding strategies avoiding overfeeding, and diminishing operating costs in aquaculture. In this sense, during the last 8 years it was analyzed in this species the application of intermittent feeding, known as unfavorable feeding condition followed by daily feeding (favorable feeding condition). This alternative feeding protocol was used in the present study to trigger compensatory growth. Juveniles weighing 0.07 ± 0.01 g were distributed in 2 feeding regimes: C (control): juveniles fed daily during 60 days, and IF (intermittent feeding): juveniles deprived of food for 4 days and then fed for the following 4 days, these 4 daysâ cycles were repeated during the first 20 days, on day 21 they were daily fed until day 60. Juveniles were stocked in each tank under 0.0096 crayfish/cm2 density, and zootechnical and biochemical parameters were evaluated throughout 60 days. A very suitable and similar survival (~ 65%) was maintained between feeding regimes, and the previously unfavorable feeding condition did not promote greater aggression among juveniles. There was a small compensatory response, but no recovery occurred probably because the favorable feeding condition was too short to trigger a strong compensatory response. Hyperphagia and improvement of feed conversion were not observed in juveniles of IF, suggesting that the high density was the key for these primary compensatory mechanisms to be absent. The competition for food, could have affected and changed the priority in allocating energy resources for accelerated growth. Lipids and glycogen content from body mass were strongly depleted after unfavorable feeding condition, but there was almost a 100% recovery during favorable feeding condition. We suggest that this response was detrimental to body mass as a priority and as a strategy for juveniles to extend survival during the âdoubleâ nutritional stress caused by intermittent feeding and high density. The applicability of this alternative feeding strategy during an intensive production system can be viable, however, some changes must be considered in order to trigger compensatory growth. We suggest that a long-term of the favorable feeding condition could trigger a strong compensatory response if the high density tested in the study is maintained. We believe that juveniles of the current study had to face two nutritionally stressful factors: food restriction and high density. This could change the priority in allocation of energetic reserves and then the other suggestion would be to reduce the density if the same alternative feeding protocol is maintained.Fil: Stumpf, Liane. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada; ArgentinaFil: Sarmiento CĂĄrdenas, Paul NicolĂĄs. Universidad Nacional de Colombia; ColombiaFil: Timpanaro, Santiago. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada; ArgentinaFil: Lopez, Laura Susana. Consejo Nacional de Investigaciones CientĂficas y TĂ©cnicas. Oficina de CoordinaciĂłn Administrativa Ciudad Universitaria. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Biodiversidad y BiologĂa Experimental y Aplicada; Argentin
Energy Estimation of Cosmic Rays with the Engineering Radio Array of the Pierre Auger Observatory
The Auger Engineering Radio Array (AERA) is part of the Pierre Auger
Observatory and is used to detect the radio emission of cosmic-ray air showers.
These observations are compared to the data of the surface detector stations of
the Observatory, which provide well-calibrated information on the cosmic-ray
energies and arrival directions. The response of the radio stations in the 30
to 80 MHz regime has been thoroughly calibrated to enable the reconstruction of
the incoming electric field. For the latter, the energy deposit per area is
determined from the radio pulses at each observer position and is interpolated
using a two-dimensional function that takes into account signal asymmetries due
to interference between the geomagnetic and charge-excess emission components.
The spatial integral over the signal distribution gives a direct measurement of
the energy transferred from the primary cosmic ray into radio emission in the
AERA frequency range. We measure 15.8 MeV of radiation energy for a 1 EeV air
shower arriving perpendicularly to the geomagnetic field. This radiation energy
-- corrected for geometrical effects -- is used as a cosmic-ray energy
estimator. Performing an absolute energy calibration against the
surface-detector information, we observe that this radio-energy estimator
scales quadratically with the cosmic-ray energy as expected for coherent
emission. We find an energy resolution of the radio reconstruction of 22% for
the data set and 17% for a high-quality subset containing only events with at
least five radio stations with signal.Comment: Replaced with published version. Added journal reference and DO
Measurement of the Radiation Energy in the Radio Signal of Extensive Air Showers as a Universal Estimator of Cosmic-Ray Energy
We measure the energy emitted by extensive air showers in the form of radio
emission in the frequency range from 30 to 80 MHz. Exploiting the accurate
energy scale of the Pierre Auger Observatory, we obtain a radiation energy of
15.8 \pm 0.7 (stat) \pm 6.7 (sys) MeV for cosmic rays with an energy of 1 EeV
arriving perpendicularly to a geomagnetic field of 0.24 G, scaling
quadratically with the cosmic-ray energy. A comparison with predictions from
state-of-the-art first-principle calculations shows agreement with our
measurement. The radiation energy provides direct access to the calorimetric
energy in the electromagnetic cascade of extensive air showers. Comparison with
our result thus allows the direct calibration of any cosmic-ray radio detector
against the well-established energy scale of the Pierre Auger Observatory.Comment: Replaced with published version. Added journal reference and DOI.
Supplemental material in the ancillary file
5to. Congreso Internacional de Ciencia, TecnologĂa e InnovaciĂłn para la Sociedad. Memoria acadĂ©mica
El V Congreso Internacional de Ciencia, TecnologĂa e InnovaciĂłn para la Sociedad, CITIS 2019, realizado del 6 al 8 de febrero de 2019 y organizado por la Universidad PolitĂ©cnica Salesiana, ofreciĂł a la comunidad acadĂ©mica nacional e internacional una plataforma de comunicaciĂłn unificada, dirigida a cubrir los problemas teĂłricos y prĂĄcticos de mayor impacto en la sociedad moderna desde la ingenierĂa.
En esta edición, dedicada a los 25 años de vida de la UPS, los ejes temåticos estuvieron relacionados con la aplicación de la ciencia, el desarrollo tecnológico y la innovación en cinco pilares fundamentales de nuestra sociedad: la industria, la movilidad, la sostenibilidad ambiental, la información y las telecomunicaciones.
El comitĂ© cientĂfico estuvo conformado formado por 48 investigadores procedentes de diez paĂses: España, Reino Unido, Italia, BĂ©lgica, MĂ©xico, Venezuela, Colombia, Brasil, Estados Unidos y Ecuador.
Fueron recibidas un centenar de contribuciones, de las cuales 39 fueron aprobadas en forma de ponencias y 15 en formato poster. Estas contribuciones fueron presentadas de forma oral ante toda la comunidad acadĂ©mica que se dio cita en el Congreso, quienes desde el aula magna, el auditorio y la sala de usos mĂșltiples de la Universidad PolitĂ©cnica Salesiana, cumplieron respetuosamente la responsabilidad de representar a toda la sociedad en la revisiĂłn, aceptaciĂłn y validaciĂłn del conocimiento nuevo que fue presentado en cada exposiciĂłn por los investigadores.
Paralelo a las sesiones tĂ©cnicas, el Congreso contĂł con espacios de presentaciĂłn de posters cientĂficos y cinco workshops en temĂĄticas de vanguardia que cautivaron la atenciĂłn de nuestros docentes y estudiantes. TambiĂ©n en el marco del evento se impartieron un total de ocho conferencias magistrales en temas tan actuales como la gestiĂłn del conocimiento en la universidad-ecosistema, los retos y oportunidades de la industria 4.0, los avances de la investigaciĂłn bĂĄsica y aplicada en mecatrĂłnica para el estudio de robots de nueva generaciĂłn, la optimizaciĂłn en ingenierĂa con tĂ©cnicas multi-objetivo, el desarrollo de las redes avanzadas en LatinoamĂ©rica y los mundos, la contaminaciĂłn del aire debido al trĂĄnsito vehicular, el radĂłn y los riesgos que representa este gas radiactivo para la salud humana, entre otros
Multiple Scenario Generation of Subsurface Models:Consistent Integration of Information from Geophysical and Geological Data throuh Combination of Probabilistic Inverse Problem Theory and Geostatistics
Neutrinos with energies above 1017 eV are detectable with the Surface Detector Array of the Pierre Auger Observatory. The identification is efficiently performed for neutrinos of all flavors interacting in the atmosphere at large zenith angles, as well as for Earth-skimming \u3c4 neutrinos with nearly tangential trajectories relative to the Earth. No neutrino candidates were found in 3c 14.7 years of data taken up to 31 August 2018. This leads to restrictive upper bounds on their flux. The 90% C.L. single-flavor limit to the diffuse flux of ultra-high-energy neutrinos with an E\u3bd-2 spectrum in the energy range 1.0
7 1017 eV -2.5
7 1019 eV is E2 dN\u3bd/dE\u3bd < 4.4
7 10-9 GeV cm-2 s-1 sr-1, placing strong constraints on several models of neutrino production at EeV energies and on the properties of the sources of ultra-high-energy cosmic rays
Ultrahigh-energy neutrino follow-up of gravitational wave events GW150914 and GW151226 with the Pierre Auger Observatory
International audienceOn September 14, 2015 the Advanced LIGO detectors observed their first gravitational-wave (GW) transient GW150914. This was followed by a second GW event observed on December 26, 2015. Both events were inferred to have arisen from the merger of black holes in binary systems. Such a system may emit neutrinos if there are magnetic fields and disk debris remaining from the formation of the two black holes. With the surface detector array of the Pierre Auger Observatory we can search for neutrinos with energy above 100 PeV from point-like sources across the sky with equatorial declination from about -65 deg. to +60 deg., and in particular from a fraction of the 90% confidence-level (CL) inferred positions in the sky of GW150914 and GW151226. A targeted search for highly-inclined extensive air showers, produced either by interactions of downward-going neutrinos of all flavors in the atmosphere or by the decays of tau leptons originating from tau-neutrino interactions in the Earth's crust (Earth-skimming neutrinos), yielded no candidates in the Auger data collected within s around or 1 day after the coordinated universal time (UTC) of GW150914 and GW151226, as well as in the same search periods relative to the UTC time of the GW candidate event LVT151012. From the non-observation we constrain the amount of energy radiated in ultrahigh-energy neutrinos from such remarkable events
Impact of atmospheric effects on the energy reconstruction of air showers observed by the surface detectors of the Pierre Auger Observatory
Impact of atmospheric effects on the energy reconstruction of air showers observed by the surface detectors of the Pierre Auger Observatory
Horse Population by Province, 2009-2016
We present a search for ultrarelativistic magnetic monopoles with the Pierre Auger observatory. Such particles, possibly a relic of phase transitions in the early Universe, would deposit a large amount of energy along their path through the atmosphere, comparable to that of ultrahigh-energy cosmic rays (UHECRs). The air-shower profile of a magnetic monopole can be effectively distinguished by the fluorescence detector from that of standard UHECRs. No candidate was found in the data collected between 2004 and 2012, with an expected background of less than 0.1 event from UHECRs. The corresponding 90%Â confidence level (C.L.) upper limits on the flux of ultrarelativistic magnetic monopoles range from 10(cm sr s) for a Lorentz factor Îł=10 to 2.5Ă10(cm sr s) for Îł=10. These resultsâthe first obtained with a UHECR detectorâimprove previously published limits by up to an order of magnitude