A multiprobe heat pulse sensor for soil moisture measurement based on PCB technology

Heat dissipation sensors operate based on the temperature dependence of the transient heat conduction within the soil, which is a function of the soil characteristics and its water content. After a heat pulse with controlled energy is applied to a heater, it is possible to show that the maximum temperature rise AT M measured in the temperature sensing element can be related to the volumetric water content of the soil θ v [m 3 m -3 ]. The design and fabrication of a low-cost soil moisture multiprobe heat pulse sensor system using conventional printed circuit boards and surface-mount devices is presented. The proposed sensor is free of the needles' deflection problem present in conventional multiprobe sensors and is manufactured using conventional off-the-shelf electronic components. A precision lowpower electronic signal conditioning circuit, using an instrumentation switched-capacitor building block, was developed and successfully used in the prototype. Due to an energy-efficient topology for the sensor and a low-power signal conditioning circuit, the average current consumption of the system (with one measurement per day) is only 3 μA. To demonstrate the feasibility of the concept, a prototype of the sensor was tested in soils with volumetric humidity in the range from θ v = 0.05 m 3 m -3 to θ v = 0.41 m 3 m -3 and, with a very low heating energy pulse (3 J), showed a sensitivity, normalized by the total energy applied, Γ = 211 × 10 -3 °C m 3 m -3 J -1 . Compared with a button heat pulse probe sensor which has Γ = 192 × 10 -3 °Cm 3 m -3 J -1 , the developed sensor shows a higher normalized sensitivity68260661

Current threats faced by Neotropical parrot populations

Psittaciformes (parrots, cockatoos) are among the most endangered birds, with 31% of Neotropical species under threat. The drivers of this situation appear to be manifold and mainly of anthropogenic origin. However, this assessment is based on the last extensive consultation about the conservation situation of parrots carried out in the 1990s. Given the rapid development of anthropogenic threats, updated data are needed to strategize conservation actions. Using a population approach, we addressed this need through a wide-ranging consultation involving biologists, wildlife managers, government agencies and non-governmental conservation organizations. We gathered up-to-date information on threats affecting 192 populations of 96 Neotropical parrot species across 21 countries. Moreover, we investigated associations among current threats and population trends. Many populations were affected by multiple threats. Agriculture, Capture for the Pet Trade, Logging, each of them affected > 55% of the populations, suggesting a higher degree of risk than previously thought. In contrast to previous studies at the species level, our study showed that the threat most closely associated with decreasing population trends is now Capture for the local Pet Trade. Other threats associated with decreasing populations include Small-holder Farming, Rural Population Pressure, Nest Destruction by Poachers, Agro-industry Grazing, Small-holder Grazing, and Capture for the international Pet Trade. Conservation actions have been implemented on < 20% of populations. Our results highlight the importance of a population-level approach in revealing the extent of threats to wild populations. It is critical to increase the scope of conservation actions to reduce the capture of wild parrots for pets.We would also like to thank the European Network on Invasive Parakeets (ParrotNet. Cost Actions: ES1304-240316-071371, ES1304-240316-071371), Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET-PIP 112-201501-0598), Agencia Nacional de Promoción Científica y Tecnológica (FONCyT-PICT 2015-2281), and Brazilian National Council of Research (CNPq) for financial support