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.
We describe a technique to optimize the dynamic performance of microwave SQUID multiplexer (µMUX)-based systems. These systems proved to be adequate for reading out multiple cryogenic detectors ...simultaneously. However, the requirement for denser detector arrays to increase the sensitivity of scientific experiments makes its design a challenge. When modifying the readout power, there is a trade-off between decreasing the signal-to-noise ratio (SNR) and boosting the nonlinearities of the active devices. The latter is characterized by the spurious free dynamic range (SFDR) parameter and manifests as an increment in the intermodulation products and harmonics power. We estimate the optimal spectral location of the SQUID signal containing the detector information for different channels. Through the technique, what we refer to as
Spectral Engineering
, it is possible to minimize the SNR degradation while maximizing the SFDR of the detector signal, thus, overcoming the trade-off.
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%.
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