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384 results on '"Mankin, R."'

2. Responses of Asian Citrus Psyllids to Substrate-borne Vibrational Communication Signals

Author

Mankin, R. W., Rohde, B., Hetherington, E., and McNeill, S.

Abstract

The Asian Citrus Psyllid (ACP), Diaphorina citri Kuwayama, vectors a harmful bacterium, Candidatus Liberibacter asiaticus, which causes huanglongbing, an economically devastating disease of citrus. Improved methods for detection and trapping of ACP could significantly reduce the damage associated with the spread of this disease. One previously unexploited method of detection involves the vibratory, substrate-borne signals by which adult male and female ACP communicate over 10-50-cm distances within their citrus tree hosts. Mate-seeking males begin calling while moving along the tree branches, searching for females. A receptive female replies to these signals within about 0.5-s, which helps the male to find her position (Wenninger et al. 2009, Rohde et al. 2013). A series of studies was conducted in a noise- and vibration-shielded anechoic chamber (Fig. 1) to manipulate these communications in a way that could be used to attract and trap ACP males in field environments. Male recorded calls were played back to females through the vibration exciter and the replies were monitored with the accelerometer. The frequencies, durations, and loudness of calls that elicited the greatest female response were analyzed for further study. In addition, recorded replies from females were played back to males, attracting them to the signal source. Based on the successful results with the laboratory accelerometer and vibration exciter systems (Rohde et al. 2013), we began development of a portable, automated system with a piezoelectric vibratory element that replies to male calls immediately after they are detected by a microphone attached to a small, inexpensive microcomputer. Searching males move towards the source of such calls (Fig. 2) and can thereby be trapped. To facilitate trap development we have begun testing the relative attractiveness of carefully constructed synthetic calls, some of which are described in (Rohde et al. 2013). In addition, we are beginning to conduct field studies under conditions of moderate background noise.

Published
2014

6. A new approach to electromagnetic wave tails on a curved spacetime

Author

Mankin, R., Laas, T., and Tammelo, R.

Subjects
General Relativity and Quantum Cosmology
Abstract

We present an alternative method for constructing the exact and approximate solutions of electromagnetic wave equations whose source terms are arbitrary order multipoles on a curved spacetime. The developed method is based on the higher-order Green's functions for wave equations which are defined as distributions that satisfy wave equations with the corresponding order covariant derivatives of the Dirac delta function as the source terms. The constructed solution is applied to the study of various geometric effects on the generation and propagation of electromagnetic wave tails to first order in the Riemann tensor. Generally the received radiation tail occurs after a time delay which represents geometrical backscattering by the central gravitational source. It is shown that the truly nonlocal wave-propagation correction (the tail term) takes a universal form which is independent of multipole order. In a particular case, if the radiation pulse is generated by the source during a finite time interval, the tail term after the primary pulse is entirely determined by the energy-momentum vector of the gravitational field source: the form of the tail term is independent of the multipole structure of the gravitational source. We apply the results to a compact binary system and conclude that under certain conditions the tail energy can be a noticeable fraction of the primary pulse energy. We argue that the wave tails should be carefully considered in energy calculations of such systems., Comment: RevTex, 28 pages, 5 eps figures, http://www.tpu.ee/~tony/texdocs/, 4 changes made (pp. 2, 4, 22, 24), 2 references added

Published
2000
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10. Stochastic resonance of the spectral amplification for a fractional oscillator in a fluctuating magnetic field.

Author

Laas, K., Laas, T., and Mankin, R.

Subjects
MAGNETIC fields, STOCHASTIC resonance, WHITE noise, ELECTRIC fields
Abstract

The long-time limit behavior of the stochastic dynamics for an underdamped charged fractional oscillator with a power-law memory kernel under the action of crossed electric field and a fluctuating magnetic field is investigated. The influence of an electric field is considered as a superposition of an external periodic force and a stationary noise. Fluctuations of the magnetic field are modeled by a colored dichotomous noise. The exact expressions of the first-order statistical moments of the fluctuating position for the particle in the plane perpendicular to the magnetic field have been calculated. It is established the non-monotonic depen-dence of the amplitude of the mean oscillator displacement on the parameters of the dichotomous noise (stochastic resonance). Particularly, it is shown that at small values of the memory exponent (strong memory) the spectral amplification displays in some parameter regimes a very sensitive response to variations of the noise amplitude. Also a detailed analysis has been undertaken for the properties of the spectral amplification in the case if the fluctuations of the magnetic field are modeled by the white noise. [ABSTRACT FROM AUTHOR]

Published
2023
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11. Influence of a fluctuating magnetic field on the statistical moments of a charged oscillator driven by a periodic force.

Author

Laas, T., Laas, K., and Mankin, R.

Subjects
MAGNETIC fields, WHITE noise, FLUCTUATIONS (Physics), STOCHASTIC resonance, ANGULAR momentum (Mechanics), POTENTIAL well, ELECTRIC fields
Abstract

We have considered the long-time behavior of the second-order statistical moments for a charged Brownian particle in a harmonic potential well, which is simultaneously exposed to a fluctuating magnetic field. Fluctuations of the magnetic field are modeled by the white noise. Moreover, to make the model more general, we add an external electrical force, which is expressed as a sum of two contributions: a stationary colored noise, and a periodic electric field. In the long-time limit, we provide exact formulas for the analytic treatment of the dependence of second-order statistical moments of fluctuating position of the Brownian particle on system parameters. Also, the particle's mean angular momentum is found. It is shown that an interplay of external periodic forcing and fluctuations of the magnetic field can generate a variety of cooperation effects, such as the dependence of central moments on the parameters of external periodic driving, a stochastic resonance versus the intensity of magnetic fluctuations, a cross-correlation between particle's fluctuations along orthogonal directions, and stochastic magnetic field induced oscillations of second-order central moments. [ABSTRACT FROM AUTHOR]

Published
2023
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21. Fano factor of output spike trains for a neuron model driven by dichotomous noise.

Author

Rekker, A., Paekivi, S., and Mankin, R.

Subjects
NOISE
Abstract

The behavior of Fano factor (FF) of output spike trains for a stochatic perfect integrate-and-fire model of neurons is considered. The effect of temporally correlated random activity of synaptic inputs is modeled as an asymmetric dichotomous noise. It is shown that the dependence of the Fano factor on the observation window behaves significantly different from the one for renewal processes. Further, the models extended by including a random operational time in the form of an inverse strictly increasing Lévy-type subordinator, and formulas for FF are given also in this case. Particularly, it is shown that highly nonmonotonic dependence of the FF on the observation time generated by the input dichotomous noise in the model without subordination is removed due to memory effects in the model with subordination. Moreover, in the case with a subordination the FF demonstrates at sufficiently large values of the observation time a nonmonotonic dependence on the mean input current μ with a clear minimum at an intermediate value of μ, which indicates that the output spike train regularity is maximized at this value of the input current. [ABSTRACT FROM AUTHOR]

Published
2022
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37. Performance of a Low-Cost Acoustic Insect Detector System with Sitophilus oryzae(Coleoptera: Curculionidae) in Stored Grain and Tribolium castaneum(Coleoptera: Tenebrionidae) in Flour

Author

Mankin, R W, Jetter, E, Rohde, B, and Yasir, M

Abstract

Reduction of postharvest losses is gaining increased priority in warm regions where insect infestation may cause rapid deterioration of staple commodities. Acoustic detection can be used to assess the likelihood of insect infestations in bags of grain, flour, and other commodities that are stored in small holdings in developing countries, enabling rapid targeting of treatments. A portable postharvest insect detection system was developed with the goal to provide low-cost capability to acoustically assess infestations in small-scale storage facilities. Electret microphones input pest insect sounds to a 32-bit microcontroller platform that digitized and stored the signals on a digital memory card transferable to a portable laptop computer. The insect sounds then were analyzed by custom-written software that matched their spectra to those of known pests. Infestations of Sitophilus oryzae(L) in 2.6-kg bags could be detected down to densities of 1.9 adults/kg in grain and Tribolium castaneum(Herbst) down to 3.8 adults/kg in flour in laboratory settings. Also, differences in the rates of sounds per insect in treatments with different numbers ranging from 5 to 50 insects suggested that the sound rates of adults of different species at different population densities may be noticeably affected by aggregation pheromones or other behaviorally active semiochemicals. Further testing is needed but previous experience with acoustic detection systems suggests that the prototype has potential for use in small storage facilities where early detection of infestations is difficult to provide.

Published
2020
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45. Characterization of sounds in maize produced by internally feeding insects: investigations to develop inexpensive devices for detection of Prostephanus truncatus (Coleoptera: Bostrichidae) and Sitophilus zeamais (Coleoptera: Curculionidae) in small-scale storage facilities in sub-Saharan Africa

Author

Biological Systems Engineering, Kiobia, D. O., Tumbo, Siza D., Cantillo, J., Rohde, B. B., Mallikarjunan, P. K., Mankin, R. W., Biological Systems Engineering, Kiobia, D. O., Tumbo, Siza D., Cantillo, J., Rohde, B. B., Mallikarjunan, P. K., and Mankin, R. W.

Abstract

Infestations by Prostephanus truncatus Horn (Coleoptera: Bostrichidae) and Sitophilus zeamais Motschulsky (Coleoptera: Curculionidae) are prevalent in small-scale Zea mays L. storage facilities in Tanzania and other regions of sub-Saharan Africa. It is especially difficult to detect these species' larvae, which feed unseen inside the grain kernels. An electronic device that acoustically detects and reliably indicates the presence of such larvae could assist pest managers in maintaining the quality of the stored maize. A study was conducted in a sound-and vibration-controlled environment to estimate the amplitudes and spectral ranges of signals that an inexpensive electronic system would encounter while detecting insects in maize storage facilities. Larva-infested wheat kernels from a laboratory colony of Sitophilus oryzae (L.), a species similar in size and behavior to S. zeamais, were placed in a pouch and inserted near the side or the bottom of a bag of maize. An acoustic probe was inserted into the bag, and recordings were made at multiple positions, 5-35 cm from the pouch. Numerous sounds of 4 different types were detected over a range of frequencies extending to 7 kHz, well within the signal-processing capabilities of currently available low-cost microcontroller platforms. Larval sound impulses were detected frequently within 25 cm from the pouch, but not at 35 cm. However, adjustable-length probes could be used to reach within 30 cm of all maize kernels in the types of containers commonly used in regional storage facilities. Thus, there is considerable potential to develop an inexpensive sensor/ microcontroller system useful for managing stored product insect pests in sub-Saharan Africa.

Published
2015

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