12,352 research outputs found
Evaluación de los efectos del herbicida glifosato en el pez Prochilodus lineatus a través del test de aberración cromosómica.
The widespread use of glyphosate has been subject of numerous controversies since the prolonged exposure to low concentrations of this substance could lead to toxic effects. Then, the appearance of pathologies in medium and long term progressively will increase because of the exposure of people and animals through the consumption of contaminated water or food. Considering this, the aim of this study was to evaluate the potential mutagenicity of glyphosate herbicide in fish (Prochilodus lineatus) using the test of chromosome aberrations. The fish were exposed to 0,1 ug/l of glyphosate for 70 days. After this period, samples of the anterior portion of the kidney were extracted for chromosomal aberrations (CAs) analysis. A greater number of CAs (gaps, breaks, stickiness, endomitosis, fragmentations, and pulverizations) were observed in individuals exposed to the pesticide. The statistical analysis of the data showed significant differences between the control and treated groups. In this way, the results suggested the existence of a genetic response as a consequence of pesticide exposure in fish.El uso generalizado del glifosato ha sido objeto de numerosas controversias, ya que la exposición prolongada a bajas concentraciones de este agroquímico podría dar lugar a efectos no deseados o nocivos. Ello favorecería la aparición de patologías en el mediano y largo plazo, lo que aumenta progresivamente el riesgo de exposición en seres humanos y animales, a través del consumo de agua y alimentos contaminados. Teniendo en cuenta esta premisa, el objetivo del trabajo fue evaluar el posible efecto mutagénico del herbicida a través de la prueba de aberraciones cromosómicas en peces de la especie Prochilodus lineatus. Los peces fueron expuestos a 0,1 ug/l de glifosato durante 70 días. Después de este período una muestra de la porción anterior del riñón fue extraída para el análisis de aberraciones cromosómicas (AC). En los individuos expuestos al pesticida se registró mayor número de AC. El análisis estadístico de los datos mostró diferencias significativas entre los grupos control y tratado. Los resultados sugieren la existencia de una respuesta genética causada por la exposición y el contacto de los especímenes con el herbicida
Linear Theory of Electron-Plasma Waves at Arbitrary Collisionality
The dynamics of electron-plasma waves are described at arbitrary
collisionality by considering the full Coulomb collision operator. The
description is based on a Hermite-Laguerre decomposition of the velocity
dependence of the electron distribution function. The damping rate, frequency,
and eigenmode spectrum of electron-plasma waves are found as functions of the
collision frequency and wavelength. A comparison is made between the
collisionless Landau damping limit, the Lenard-Bernstein and Dougherty
collision operators, and the electron-ion collision operator, finding large
deviations in the damping rates and eigenmode spectra. A purely damped entropy
mode, characteristic of a plasma where pitch-angle scattering effects are
dominant with respect to collisionless effects, is shown to emerge numerically,
and its dispersion relation is analytically derived. It is shown that such a
mode is absent when simplified collision operators are used, and that
like-particle collisions strongly influence the damping rate of the entropy
mode.Comment: 23 pages, 10 figures, accepted for publication on Journal of Plasma
Physic
First in-beam studies of a Resistive-Plate WELL gaseous multiplier
We present the results of the first in-beam studies of a medium size
(1010 cm) Resistive-Plate WELL (RPWELL): a single-sided THGEM
coupled to a pad anode through a resistive layer of high bulk resistivity
(10cm). The 6.2~mm thick (excluding readout electronics)
single-stage detector was studied with 150~GeV muons and pions. Signals were
recorded from 11 cm square copper pads with APV25-SRS readout
electronics. The single-element detector was operated in Ne\(5%
) at a gas gain of a few times 10, reaching 99
detection efficiency at average pad multiplicity of 1.2. Operation at
particle fluxes up to 10 Hz/cm resulted in 23 gain drop
leading to 5 efficiency loss. The striking feature was the
discharge-free operation, also in intense pion beams. These results pave the
way towards robust, efficient large-scale detectors for applications requiring
economic solutions at moderate spatial and energy resolutions.Comment: Accepted by JINS
Giant Shapiro Resonances in a Flux Driven Josephson Junction Necklace
We present a detailed study of the dynamic response of a ring of equally
spaced Josephson junctions to a time-periodic external flux, including
screening current effects. The dynamics are described by the resistively
shunted Josephson junction model, appropriate for proximity effect junctions,
and we include Faraday's law for the flux. We find that the time-averaged
characteristics show novel {\em subharmonic giant Shapiro voltage resonances},
which strongly depend on having phase slips or not, on , on the inductance
and on the external drive frequency. We include an estimate of the possible
experimental parameters needed to observe these quantized voltage spikes.Comment: 8 pages RevTeX, 3 figures available upon reques
Toxicological Study Employing Repeated Doses of Garcinielliptone FC, a Polyisoprenylated-Benzophenone Isolated from Seed of Platonia Insignis Mart
The major constituent from the hexane extract of the seeds of P. insignis is GFC (garcinielliptone FC). Doses of 25, 50and 75 mg/kg of GFC were aseptically suspended in 0.05% Tween 80 dissolved in 0.9% saline (vehicle) and orally administered for30, 90 and 120 consecutive days to adult Swiss mice. In this work, the repeated oral administration, in animals of both sexes,demonstrates that this compound is not able to induce mortality and/or behavioral changes in adult mice. In addition, body weightgain, feed intake and disposal of excreta were not altered by the administration of this compound with repeated doses. Furthermore,no differences in weight and macroscopic structure of the brain, liver, kidney, lung, heart and spleen between groups of male andfemale adult mice were observed after treatment. During the periods of treatment, GFC produced no significant changes onhaematological and biochemical parameters in male and female mice treated with all doses used. The aim of this study was toinvestigate the toxicological potential of GFC through behavioral, hematological, biochemical and morphological parameters inanimals in order to ensure the safe use of Platonia insignis in folk medicine.Fil: Silva, Ana P.. Federal University of Piauí; BrasilFil: Filho, José Carlos C. L. S.. North Union of Parana; BrasilFil: da Costa Júnior, Joaquim S.. Federal Institute of Piauí; BrasilFil: Peláez, Walter José. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Faillace, Martín Sebastián. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Córdoba. Instituto de Investigaciones en Físico-química de Córdoba. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas. Instituto de Investigaciones en Físico-química de Córdoba; ArgentinaFil: Falcão Ferraz, Alexandre de B.. Lutheran University of Brazil; BrasilFil: David, Jorge M.. Institute Of Chemistry, Federal University Of Bahia; Brasil. Universidade Federal da Bahia; BrasilFil: Freitas, Rivelilson M.. Federal University of Bahia; Brasi
Quantum pattern recognition with liquid-state nuclear magnetic resonance
A novel quantum pattern recognition scheme is presented, which combines the
idea of a classic Hopfield neural network with adiabatic quantum computation.
Both the input and the memorized patterns are represented by means of the
problem Hamiltonian. In contrast to classic neural networks, the algorithm can
return a quantum superposition of multiple recognized patterns. A proof of
principle for the algorithm for two qubits is provided using a liquid state NMR
quantum computer.Comment: updated version, Journal-ref adde
Emergence of macroscopic temperatures in systems that are not thermodynamical microscopically: towards a thermodynamical description of slow granular rheology
A scenario for systems with slow dynamics is characterised by stating that
there are several temperatures coexisting in the sample, with a single
temperature shared by all observables at each (widely separate) time-scale.
In preparation for the study of granular rheology, we show within this
framework that glassy systems with driving and friction that are generic and do
not correspond to a thermal bath --- and whose microscopic `fast' motion is
hence not thermal --- have a well-defined macroscopic temperature associated to
the slow degrees of freedom.
This temperature is what a thermometer coupled to the system will measure if
tuned to respond to low frequencies, and since it can be related to the number
of stationary configurations, it is the formalisation of Edwards'
`compactivity' ideas.Comment: Revised version: treatment of `tapping' deferre
Density Matrix Renormalization Group Study of One-Dimensional Acoustic Phonons
We study the application of the density matrix renormalization group (DMRG)
to systems with one-dimensional acoustic phonons. We show how the use of a
local oscillator basis circumvents the difficulties with the long-range
interactions generated in real space using the normal phonon basis. When
applied to a harmonic atomic chain, we find excellent agreement with the exact
solution even when using a modest number of oscillator and block states (a few
times ten). We discuss the use of this algorithm in more complex cases and
point out its value when other techniques are deficient.Comment: 12 pages. To be published in PRB rapid co
Plant-nematode co-cultures in the screening of sustainable nematicides against soil-dwelling parasitic nematodes of plants
The diseases caused by plant parasitic nematodes are still a serious constraint to modern global crop production. An
increasing number of active compounds in commercial nematicidal formulations is being banned from use by common
policies of pest management. Farmer communities report a low efficiency for the replacement pesticides, which reflects
on crop yield and productivity. Novel sustainable biopesticides are urgently needed to cope with global food demands
while respecting the most recent environmental policies. Plant-nematode co-cultures offer a stable biotechnological
screening tool able to assess the active compound’s nematicidal activity and its effect on host tissues, simultaneously,
in an easily accessible system that simulates natural infection. These systems are being developed and optimized at the
Nematology laboratory of INIAV. Preliminary results were obtained for co-cultures of Solanum lycopersicum with the
nematode Meloidogyne ethiopica and S. tuberosum with Globodera pallida. Future studies will target other plant parasitic
nematodes, e.g., the root lesion nematodes (Pratylenchus penetrans) in transgenic roots of potato and the pinewood
nematode (Bursaphelenchus xylophilus) on in vitro pine shoots (Pinus sp.)
Biological treatment of a contaminated gaseous emission containing monochlorobenzene
This study presents the operation of a biotrickling filter when treating a monochlorobenzene (MCB) contaminated gaseous
emission. Treatment dynamics were characterised by exposing the reactor to various MCB Organic Loads (OL). The use of
different growth support materials, namely limestone, sand, ceramic and PVC pall-rings, was investigated. Limestone led to
clogging of the reactor due to the accumulation of surface precipitates, but PVC pall-rings allowed for a uniform biofilm
growth. The biotrickling filter presented maximum removal efficiency (RE, 95%) under OL regimes of 10 g m-3-reactor h-1.
Treatment inhibition was observed when the reactor was exposed to OL of 45 g m-3-reactor h-1 with RE reaching a minimum
value (8%) and elimination capacity of 8 g m3-reactor h-1 The first half of the reactor height was the predominant section for
MCB biodegradation and increasing the mineral medium redrculation rate was beneficial for the overall treatment
- …