A new approach to electromagnetic wave tails on a curved spacetime

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 adde

Three and four current reversals versus temperature in correlation ratchets with a simple sawtooh potential

Transport of Brownian particles on a simple sawtooth potential subjected to both unbiased thermal and nonequilibrium symmetric three-level Markovian noise is considered. The new effects of three and four current reversals as a function of temperature are established in such correlation ratchets. The parameter space coordinates of the fixed points associated with these current reversals and the necessary and sufficient conditions for the existence of the novel current reversals are found.Comment: 4 pages, 5 figures; some changes introduced; accepted for publication in Physical Review

Behavioral responses of male \u3ci\u3eDiaphorina citri\u3c/i\u3e (Hemiptera: Liviidae) to mating communication signals from vibration traps in citrus (Sapindales: Rutaceae) trees

The Asian citrus psyllid, Diaphorina citri Kuwayama (Hemiptera: Liviidae), vectors the bacterium causing citrus greening disease, which has devastated citrus production worldwide wherever it has been introduced. To help monitor and target D. citri populations in commercial groves, thereby facilitating more effective management of citrus greening disease, a prototype device has been developed that mimics D. citri female vibrational communication signals, attracting males to a trap. For this report, effects of the device on male D. citri searching behavior were assessed to consider potential improvements in field applications. Forty-five percent of the males that searched towards the female signal mimic reached the source. In addition, the mean latencies before the initiation of calling and searching responses by males that reached the source were significantly lower than for those that missed, which suggests that trapping efficiency is strongly influenced by variability in male responsiveness to searching cues. Consequently, it is likely that the trapping efficiency of vibration traps could be increased further if they were modified to make use of additional cues strongly attractive to males, such as citrus flush olfactory and visual cues. El sílido asiático de los cítricos Diaphorina citri Kuwayama (Hemiptera: Liviidae) es un vector de la bacteria causante de la enfermedad del enverdecimiento de los cítricos, que ha devastado la producción de cítricos en todo el mundo dondequiera que este ha sido introducido. Para ayudar a monitorear y enfocarse a las poblaciones de D. citri en los bosques comerciales, facilitando así un manejo más efectivo de la enfermedad del enverdecimiento de los cítricos, se ha desarrollado un aparato prototipo que imita las señales vibracionales de comunicación de las hembras de D. citri, que atraen a machos a las trampas. Para este informe, se evaluaron los efectos del aparato sobre el comportamiento de búsqueda de los machos de D. citri para considerar posibles mejoras en las aplicaciones de campo. El 45% de los machos que buscaban hacia la señal que imitaba la hembra llegaron a la fuente. Además, el promedio de la latencia antes de la iniciación de la llamada y las respuestas de búsqueda por los machos que llegaron a la fuente fueron significativamente más bajos que para los que se fallaron, lo que sugiere que la eficiencia de captura está fuertemente influenciada por la variabilidad en la capacidad de respuesta de los machos a buscar señales. En consecuencia, es probable que la eficacia de captura de trampas de vibración podría aumentar aún más si se modificaron para hacer uso de señales adicionales fuertemente atractivas para los machos, tales como señales olfativas y visuales de los brotes de nuevas hojas en cítricos

Comparison of QG-Induced Dispersion with Standard Physics Effects

One of the predictions of quantum gravity phenomenology is that, in situations where Planck-scale physics and the notion of a quantum spacetime are relevant, field propagation will be described by a modified set of laws. Descriptions of the underlying mechanism differ from model to model, but a general feature is that electromagnetic waves will have non-trivial dispersion relations. A physical phenomenon that offers the possibility of experimentally testing these ideas in the foreseeable future is the propagation of high-energy gamma rays from GRB's at cosmological distances. With the observation of non-standard dispersion relations within experimental reach, it is thus important to find out whether there are competing effects that could either mask or be mistaken for this one. In this letter, we consider possible effects from standard physics, due to electromagnetic interactions, classical as well as quantum, and coupling to classical geometry. Our results indicate that, for currently observed gamma-ray energies and estimates of cosmological parameter values, those effects are much smaller than the quantum gravity one if the latter is first-order in the energy; some corrections are comparable in magnitude with the second-order quantum gravity ones, but they have a very different energy dependence.Comment: 8 pages; Version to be published in CQG as a letter; Includes some new comments and references, but no changes in the result

Can Schwarzschildean gravitational fields suppress gravitational waves?

Gravitational waves in the linear approximation propagate in the Schwarzschild spacetime similarly as electromagnetic waves. A fraction of the radiation scatters off the curvature of the geometry. The energy of the backscattered part of an initially outgoing pulse of the quadrupole gravitational radiation is estimated by compact formulas depending on the initial energy, the Schwarzschild radius, and the location and width of the pulse. The backscatter becomes negligible in the short wavelength regime.Comment: 18 pages, Revtex. Added three references; a new comment in Sec. 7; several misprints corrected. To appear in the Phys. Rev.

Bioacoustics of Acanthoscelides obtectus (Coleoptera: Chrysomelidae: Bruchinae) on Phaseolus vulgaris (Fabaceae)

Acanthoscelides obtectus (Say) (Coleoptera: Chrysomelidae) is an economically important pest of common bean, Phaseolus vulgaris L. (Fabaceae), in the tropics and subtropics. The larvae are cryptic and spend most of their development time inside the bean seeds. Their presence is almost imperceptible except for circular emergence holes created by the last instar larvae in preparation for their exit as adults. We considered a hypothesis that readily available acoustic detection devices can be used to detect larvae and adults in stored beans. Laboratory experiments were conducted in an anechoic chamber to characterize the sounds of movement and feeding and estimate whether they could be distinguished from background noise in storage environments. The larvae produced low-amplitude insect sound impulses frequently occurring in trains (bursts) of 2 or more impulses (mean = 3.6). The adults produced lower-amplitude impulses, although at a higher rate than the larvae, and there were significantly fewer impulses per burst. These features of the acoustic signals were useful for real-time detection of A. obtectus infestation and discrimination from background noise in stored common beans in sub-Saharan Africa. The use of such technology in the future, especially if its costs can be reduced further, may contribute to efforts to alleviate hunger and poverty in the region

Frequency and time pattern differences in acoustic signals produced by Prostephanus truncatus (Horn) (Coleoptera: Bostrichidae) and Sitophilus zeamais (Motschulsky) (Coleoptera: Curculionidae) in stored maize

Frequency spectra and timing patterns of brief, 1–10 ms broadband sound impulses produced by movement and feeding activities of Prostephanus truncatus and Sitophilus zeamais last instars and adults in maize were investigated to find spectral and temporal pattern information useful for distinguishing among these species and stages. The impulse spectra were categorized into five different types of frequency patterns (profiles), designated Broadband, HighF, MidF1, MidF2 and LowF to indicate differences in their peak energies and broadness of frequency range. Groups (trains) of three or more closely spaced impulses, termed bursts, were observed to occur frequently in all recordings, as has been reported for sounds produced by other insects. Mean rates of bursts, mean counts of impulses per burst, and mean rates of impulses in bursts were calculated and compared among the two species and stages. The counts of broadband and MidF2 impulses per burst and the rates of broadband and MidF2 impulses in bursts were significantly different for adult than for 4th instar S. zeamais and either stage of P. truncatus. These findings can be useful in developing an acoustic sensor system for automated detection of hidden insects including P. truncatus and S. zeamais in bulk storage warehouses. The findings are discussed in relation to different movement and feeding behavior patterns that have been identified in these important pests

The Influence of Chronotype and Grit on Lifestyle and Physical Activity

Background:  The chronotype of a person refers to an individual's natural sleep-wake cycle and whether that individual prefers morning or evening activities, and grit is an individual's perseverance and passion for long-term goals.Aim: The purpose of this study was to investigate the relationship between grit, chronotype, physical activity, and leading a healthy lifestyle in college-age students.Methods:  Health and fitness data (i.e., chronotype, grit, lifestyle assessment score, and daily steps) from 431 first-semester university students at a private college were collected and analyzed. Results: This study found that grit and chronotype both have significant correlations with living a healthy lifestyle and with physical activity. Grit more accurately predicts a person's lifestyle (β = -13.712, r = 0.39, p < 0.0001) while chronotype more accurately predicts the physical activity, or steps, of a person (β = 66.48, r = .19, p = .0001). Chronotype can also accurately predict the grit of a person (r = .25, p < .0001), and it was found that morning people tend to have more grit.Conclusions:  This study concluded that grit, chronotype, steps, and a healthy lifestyle are all significantly correlated with each other. Knowing the relationship between endogenous chronotype, grit, and living a physically active and healthy lifestyle can help inform policy decisions related to the goal of strengthening an institution's inclusive and healthy academic community

Design and management of an orthopaedic bone bank in the Netherlands

The design and management of an orthopaedic bone bank is a complex process in which medical organisation and legislation intertwine. Neither in the Netherlands, nor in any other European country, there are official guidelines for the organisation and management of an orthopaedic bone bank. In the Netherlands, the recently modified ‘law of security and quality for using human materials’ (WVKL) dictates requirements for technical and organisational aspects for the use of human tissue and cells. The bone bank procedures include a thorough questionnaire for donor selection, extensive serological, bacteriological and histopathological examination, as well as standard procedures for registration, processing, preservation, storage and distribution of bone allografts. This article describes the organisation of an accredited bone bank and can be used as a proposition for an official guideline or can be useful as an example for other orthopaedic bone banks in Europe