88 research outputs found
Plant Health and the Science of Pests and Diseases
The health/disease duality has developed alongside human history either as a struggle for survival or as a challenge of the human being to effectively get to know himself. To speak about pests and diseases of plants may not be as exciting as when speaking of human beings; however, entomology and phytopathology hold methodological similarities to conventional medicine, which, thus, allow for correlations among them. After all, plant protection and human medical science are based under common epistemological principles of modern scientific thought. Hence, the goal of this essay is to disclose certain disagreements of the disciplines of phytopathology and entomology with agroecological based science; yet, giving way to a discussion according to ecological principles. This is a theoretical essay, based on bibliographical research and on the direct experience of the authors with family farmers in the South of Brazil during the last 20 years
Adsorption of fluorobenzene onto granular activated carbon: Isotherm and bioavailability studies
The adsorption of a recalcitran fluoroaromatic compound, fluorobenzene (FB), onto granular activated carbon (GAC) was evaluated. The respective isotherm was obtained and the Langmuir, Freundlich and RedlichâPeterson models were fitted to the experimental data, with the RedlichâPeterson model giving the best fitting. Freundlich model also provided a good fit but the Langmuir model could not adequately fit the experimental data, especially at high FB concentrations. Maximal adsorption capacity of FB onto GAC was foundto be 388 mg of FB per gram of GAC. The reversibility of the adsorption of FB onto GAC was investigated, both in the absence and presence of microorganisms. Abiotic desorption of FB occurred to a small extent (between 3% and 22%, for amounts of FB initially adsorbed to the GAC between 37 and 388 mg g 1), and bioregeneration of GAC was shown to occur when the matrix was exposed to a FB degrading culture, with 58â80% of the adsorbed FB being biodegraded. A residual amount of FB showed not to be bioavailable,
suggesting that part of the adsorbed FB may be irreversibly bound. The fraction of the non-bioavailable FB increased at higher amounts of adsorbed FB, from 19% to 33%. The results indicate that the GAC employed in this study has a good capacity to adsorb FB and that bioregeneration of this matrix is a feasible process
Ecofisiologia da germinação de Lavandula luisieri (Roseira) Rivaz-MartĂnez
A capacidade germinativa de Lavandula luisieri (Rozeira) Rivas-MartĂnez,
espĂ©cie endĂ©mica da PenĂnsula IbĂ©rica, pertencente Ă famĂlia Lamiaceae, cujos
diĂĄsporos foram colhidas em quatro locais da Beira Interior-Portugal (Casal da Fraga,
Mata, Penamacor e Vila Velha de RĂłdĂŁo), foi avaliada durante dois anos.
Sementes conservadas durante diferentes tempos apĂłs colheita, foram ensaiadas
em condiçÔes controladas de temperatura e luz. As modalidades seleccionadas foram:
para um tempo de conservação de 40 dias a temperatura contĂnua de 25ÂșC e fotoperĂodo
de 16h e para a alternĂąncia de 8Âș/18ÂșC o fotoperĂodo de 8h que coincidiu com a
temperatura mais elevada; para um tempo de conservação de 75 dias, a temperatura
contĂnua de 25ÂșC e os fotoperĂodos de 8h e 16h; para um tempo de conservação de 110
dias a alternĂąncia de 8Âș/18ÂșC e fotoperĂodo de 8h; para um tempo de conservação de 288
dias, a alternĂąncia de 8Âș/18ÂșC e fotoperĂodo de 8h e a temperatura contĂnua de 25ÂșC e
um fotoperĂodo de 16h.
Os resultados confirmam que as condiçÔes de Outono (temperaturas alternas de
8Âș/18ÂȘC ) foram as mais adequadas para a germinação desta espĂ©cie durante os
diferentes tempos de conservação
Avaliação de biofertilizantes, extratos vegetais e diferentes substùncias alternativas no manejo de tripes em cebola em sistema orgùnico.
Avaliou-se substĂąncias alternativas no manejo de tripes (Thrips tabaci Lind.), em cebola, cv, Crioula, no sistema orgĂąnico. Os experimentos foram conduzidos na EPAGRI, Ituporanga (SC). Os perĂodos entre transplante e colheita foram de 11/09/1996 a 10/01/1997 e 13/08/1997 a 11/12/1997. O delineamento foi de blocos ao acaso com 8 tratamentos em 1996 e 12 tratamentos em 1997 e quatro repetiçÔes. Em 1996 os tratamentos incluĂram o biofertilizante anaerĂłbico 50%, biofertilizante aerĂłbico 5%, sulfato de manganĂȘs 1%, extrato hidroalcoĂłlico de prĂłpolis 0,2%, macerado de ervas (âfersoralâ) 2% e 4%, extrato de fumo (Nicotiana tabacum) 2 L ha-1 + 1% detergente neutro, testemunha sem aplicação. Em 1997 os tratamentos incluĂram o macerado de ervas (âfersoralâ) 5% 10%, enxofre pĂł molhĂĄvel 0,25% + extrato hidroalcoĂłlico de prĂłpolis 0,2% + extrato de samambaia 3%, biofertilizante anaerĂłbico 50%, biofertilizante aerĂłbico 5%, extrato de losna (Artemisia verlotorum) 3%, extrato de timbĂł (Ateleia glazioviana) 0,5%, extrato de samambaia (Pteridium aquilinum) 10%, extrato de erva-de-santa-maria (Chenopodium ambrosioides) 10%, extrato de cinamomo (Melia azedarach) 10%,extrato de camomila (Matricaria chamomilla) 5%, testemunha sem aplicação. Para aplicação dos produtos empregou-se pulverizador de pressĂŁo constante a base de CO2. Os tratamentos nĂŁo causaram redução significativa na incidĂȘncia de tripes e aumentos significativos na produtividade
Atmospheric effects on extensive air showers observed with the Surface Detector of the Pierre Auger Observatory
Atmospheric parameters, such as pressure (P), temperature (T) and density,
affect the development of extensive air showers initiated by energetic cosmic
rays. We have studied the impact of atmospheric variations on extensive air
showers by means of the surface detector of the Pierre Auger Observatory. The
rate of events shows a ~10% seasonal modulation and ~2% diurnal one. We find
that the observed behaviour is explained by a model including the effects
associated with the variations of pressure and density. The former affects the
longitudinal development of air showers while the latter influences the Moliere
radius and hence the lateral distribution of the shower particles. The model is
validated with full simulations of extensive air showers using atmospheric
profiles measured at the site of the Pierre Auger Observatory.Comment: 24 pages, 9 figures, accepted for publication in Astroparticle
Physic
The Fluorescence Detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a hybrid detector for ultra-high energy
cosmic rays. It combines a surface array to measure secondary particles at
ground level together with a fluorescence detector to measure the development
of air showers in the atmosphere above the array. The fluorescence detector
comprises 24 large telescopes specialized for measuring the nitrogen
fluorescence caused by charged particles of cosmic ray air showers. In this
paper we describe the components of the fluorescence detector including its
optical system, the design of the camera, the electronics, and the systems for
relative and absolute calibration. We also discuss the operation and the
monitoring of the detector. Finally, we evaluate the detector performance and
precision of shower reconstructions.Comment: 53 pages. Submitted to Nuclear Instruments and Methods in Physics
Research Section
Anisotropy studies around the galactic centre at EeV energies with the Auger Observatory
Data from the Pierre Auger Observatory are analyzed to search for
anisotropies near the direction of the Galactic Centre at EeV energies. The
exposure of the surface array in this part of the sky is already significantly
larger than that of the fore-runner experiments. Our results do not support
previous findings of localized excesses in the AGASA and SUGAR data. We set an
upper bound on a point-like flux of cosmic rays arriving from the Galactic
Centre which excludes several scenarios predicting sources of EeV neutrons from
Sagittarius . Also the events detected simultaneously by the surface and
fluorescence detectors (the `hybrid' data set), which have better pointing
accuracy but are less numerous than those of the surface array alone, do not
show any significant localized excess from this direction.Comment: Matches published versio
The exposure of the hybrid detector of the Pierre Auger Observatory
The Pierre Auger Observatory is a detector for ultra-high energy cosmic rays.
It consists of a surface array to measure secondary particles at ground level
and a fluorescence detector to measure the development of air showers in the
atmosphere above the array. The "hybrid" detection mode combines the
information from the two subsystems. We describe the determination of the
hybrid exposure for events observed by the fluorescence telescopes in
coincidence with at least one water-Cherenkov detector of the surface array. A
detailed knowledge of the time dependence of the detection operations is
crucial for an accurate evaluation of the exposure. We discuss the relevance of
monitoring data collected during operations, such as the status of the
fluorescence detector, background light and atmospheric conditions, that are
used in both simulation and reconstruction.Comment: Paper accepted by Astroparticle Physic
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