The Argentine stretch of the del Plata basin crosses regions devoted to extensive and intensive agriculture mostly with chemical pest control. The utilization of pesticides in the region has ...increased 900% in the last two decades associated with the introduction of biotech crops and direct-seeding techniques. Our objective was to study the occurrence, concentration, and fate of pesticides in surface water and bottom sediments of the principal tributaries and main watercourse of the Paraguay-Paraná River. We sampled 22 sites in the distal positions of the main affluents and main watercourse of the Paraná and report here results from two monitoring campaigns (2010–2012). Surface water and bottom sediments were analyzed according to standardized methods by matrix-solid-phase dispersion and liquid-liquid extraction, respectively. Twenty-three pesticide compounds were analyzed by gas chromatography. The results from both campaigns indicated a generalized but variable distribution in the concentrations detected throughout the basin. The ranges of total measured pesticide concentrations in water and sediments were, respectively, 0.004–6.62 μg/l and 0.16–221.3 μg/kg dry weight. Endosulfans, cypermethrin, and chlorpyrifos were ubiquitous compounds in both environmental compartments and quantitatively the most relevant. All concentrations detected in water were over the recommended guidelines for the protection of aquatic biota. The partitioning indicated a higher affinity for the sediments. Agricultural activity is the source of pesticide-pollution loads, transported by tributaries that reach the main watercourse and alter the quality of the aquatic ecosystem.
This work reports the performance evaluation of an SDR readout system based on the latest generation (Gen3) of AMD’s Radio-Frequency System-on-Chip (RFSoC) processing platform, which integrates a ...full-stack processing system and a powerful FPGA with up to 32 high-speed and high-resolution 14-bit Digital-to-Analog Converters and 14-bit Analog-to-Digital Converters. The proposed readout system uses a previously developed multi-band, double-conversion IQ RF-mixing board targeting a multiplexing factor of approximately 1000 bolometers in a bandwidth between 4 and 8 GHz, in line with state-of-the-art microwave SQUID multiplexers. The characterization of the system was performed in two stages, under the conditions typically imposed by the multiplexer and the cold readout circuit: first, in transmission, showing that noise and spurious levels of the generated tones are close to the values imposed by the cold readout, and second, in RF loopback, presenting noise values better than −100 dBc/Hz totally in agreement with the state-of-the-art readout systems. It was demonstrated that the RFSoC Gen3 device is a suitable enabling technology for the next generation of superconducting detector readout systems, reducing system complexity, increasing system integration, and achieving these goals without performance degradation.
The transition between the Galactic and extragalactic cosmic ray components could take place either in the region of the spectrum known as the second knee or in the ankle. There are several models of ...the transition but it is not possible to confirm or even rule out any of them from the flux measurement alone. Therefore, the measurement of the composition as a function of primary energy will play a fundamental role for the understanding of this phenomenon.
In this work we study the possibility of primary identification in an event by event basis in the ankle region, around
E
=
10
18
eV
. We consider as case study the enhancements of the Pierre Auger Southern Observatory, which are under construction in Malagüe, Province of Mendoza, Argentina. We use a non-parametric technique to estimate the density functions, from Monte Carlo data, corresponding to different combination of mass sensitive parameters and type of primaries. These estimates are used to obtain the classification probability of protons and iron nuclei for the different combination of parameters considered. We find that, after considering all relevant fluctuations, the maximum classification probability obtained combining surface and fluorescence detectors parameters is of order of 90%.
The transition energy from galactic to extragalactic cosmic ray sources is still uncertain, but it should be associated either with the region of the spectrum known as the second knee or with the ...ankle. The baseline design of the Pierre Auger Observatory was optimized for the highest energies. The surface array is fully efficient above 3
×
10
18
eV and, even if the hybrid mode can extend this range below 10
18
eV, the second knee and a considerable portion of the wide ankle structure are left outside its operating range. Therefore, in order to encompass these spectral features and gain further insight into the cosmic ray composition variation along the transition region, enhancements to the surface and fluorescence components of the baseline design are being implemented that will lower the full efficiency regime of the Observatory down to ∼10
17
eV. The surface enhancements consist of a graded infilled area of standard Auger water Cherenkov detectors deployed in two triangular grids of 433
m and 750
m of spacing. Each surface station inside this area will have an associated muon counter detector. The fluorescence enhancement, on the other hand, consists of three additional fluorescence telescopes with higher elevation angle (30°–58°) than the ones in operation at present. The aim of this paper is threefold. We study the effect of the segmentation of the muon counters and find an analytical expression to correct for the under counting due to muon pile-up. We also present a detailed method to reconstruct the muon lateral distribution function for the 750
m spacing array. Finally, we study the mass discrimination potential of a new parameter, the number of muons at 600
m from the shower axis, obtained by fitting the muon data with the above mentioned reconstruction method.
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