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Drones: Innovative Technology for Use in Precision Pest Management.
Arthropod pest outbreaks are unpredictable and not uniformly distributed within fields. Early outbreak detection and treatment application are inherent to effective pest management, allowing management decisions to be implemented before pests are well-established and crop losses accrue. Pest monitoring is time-consuming and may be hampered by lack of reliable or cost-effective sampling techniques. Thus, we argue that an important research challenge associated with enhanced sustainability of pest management in modern agriculture is developing and promoting improved crop monitoring procedures. Biotic stress, such as herbivory by arthropod pests, elicits physiological defense responses in plants, leading to changes in leaf reflectance. Advanced imaging technologies can detect such changes, and can, therefore, be used as noninvasive crop monitoring methods. Furthermore, novel methods of treatment precision application are required. Both sensing and actuation technologies can be mounted on equipment moving through fields (e.g., irrigation equipment), on (un)manned driving vehicles, and on small drones. In this review, we focus specifically on use of small unmanned aerial robots, or small drones, in agricultural systems. Acquired and processed canopy reflectance data obtained with sensing drones could potentially be transmitted as a digital map to guide a second type of drone, actuation drones, to deliver solutions to the identified pest hotspots, such as precision releases of natural enemies and/or precision-sprays of pesticides. We emphasize how sustainable pest management in 21st-century agriculture will depend heavily on novel technologies, and how this trend will lead to a growing need for multi-disciplinary research collaborations between agronomists, ecologists, software programmers, and engineers
The friendship paradox in scale-free networks
Our friends have more friends than we do. That is the basis of the friendship
paradox. In mathematical terms, the mean number of friends of friends is higher
than the mean number of friends. In the present study, we analyzed the
relationship between the mean degree of vertices (individuals), , and the
mean number of friends of friends, , in scale-free networks with degrees
ranging from a minimum degree (k_min) to a maximum degree (k_max). We deduced
an expression for - for scale-free networks following a power-law
distribution with a given scaling parameter (alpha). Based on this expression,
we can quantify how the degree distribution of a scale-free network affects the
mean number of friends of friends.Comment: 9 pages, 2 figure
Optical Pumping of TeH+: Implications for the Search for Varying mp/me
Molecular overtone transitions provide optical frequency transitions
sensitive to variation in the proton-to-electron mass ratio (). However, robust molecular state preparation presents a challenge
critical for achieving high precision. Here, we characterize infrared and
optical-frequency broadband laser cooling schemes for TeH, a species with
multiple electronic transitions amenable to sustained laser control. Using rate
equations to simulate laser cooling population dynamics, we estimate the
fractional sensitivity to attainable using TeH. We find that laser
cooling of TeH can lead to significant improvements on current
variation limits
Structural and magnetic behavior of the S=2 layered ferromagnet CsMnF4 under hydrostatic pressure
Under the terms of the Creative Commons Attribution License 3.0 (CC-BY).Pressure-induced transformations in the structural and magnetic properties of CsMnF4 are reported. This behavior is analyzed in the framework of magnetostructural correlations within the layered perovskite AMnF4 (A=Cs,Rb,K) series by using magnetic susceptibility and synchrotron x-ray powder-diffraction techniques as a function of temperature and hydrostatic pressure.We would like to thank C.I.C.Y.T. for Grants Nos. MAT94-43 and MAT91-681, U.K. Science Ez. Engineering Research Council for providing Synchrotron Radiation beam
time under the E.C. Large Scale Facilities Programme, CNPq and the Programa de Cooperacion Cientifica con Iberoamerica.Peer Reviewe
The Kardar-Parisi-Zhang exponents for the dimensions
The Kardar-Parisi-Zhang (KPZ) equation has been connected to a large number
of important stochastic processes in physics, chemistry and growth phenomena,
ranging from classical to quantum physics. The central quest in this field is
the search for ever more precise universal growth exponents. Notably, exact
growth exponents are only known for dimensions. In this work, we present
physical and geometric analytical methods that directly associate these
exponents to the fractal dimension of the rough interface. Based on this, we
determine the growth exponents for the dimensions, which are in agreement
with the results of thin films experiments and precise simulations. We also
make a first step towards a solution in dimensions, where our results
suggest the inexistence of an upper critical dimension
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