Decoherence of quantum wavepackets due to interaction with conformal spacetime fluctuations

One of the biggest problems faced by those attempting to combine quantum theory and general relativity is the experimental inaccessibility of the unification scale. In this paper we show how incoherent conformal waves in the gravitational field, which may be produced by quantum mechanical zero-point fluctuations, interact with the wavepackets of massive particles. The result of this interaction is to produce decoherence within the wavepackets which could be accessible in experiments at the atomic scale. Using a simple model for the coherence properties of the gravitational field we derive an equation for the evolution of the density matrix of such a wavepacket. Following the primary state diffusion programme, the most promising source of spacetime fluctuations for detection are the above zero-point energy fluctuations. According to our model, the absence of intrinsic irremoveable decoherence in matter interferometry experiments puts bounds on some of the parameters of quantum gravity theories. Current experiments give \lambda > 18. , where \lambda t_{Planck} is an effective cut-off for the validity of low-energy quantum gravity theories.Comment: REVTeX forma

The Effects of Tree Density on Pasture Production Under Acacia Melanoxylon

Silvi-pastoral systems could contribute to greater total productivity and more sustainable land management of grazed pastures in New Zealand. Despite this potential, little is known of the interactions of tree species and environment on pasture growth. In this paper we report the effects of tree density on pasture yield in an Acacia melanoxylon silvi-pastoral system. The results show decreasing pasture yield with increasing tree density, although the extent of the reduction is less than would be expected under Pinus radiata. Results suggest that shade is the dominant factor causing yield decline in this study, while reduced N availability is clearly implicated in previous studies with pine trees. This study will provide more data on which a mechanistic model of tree-pasture interactions can be based

Detection of exogenous double-stranded RNA movement in \u3ci\u3ein vitro\u3c/i\u3e peanut plants

New technologies are needed to eliminate mycotoxins and/or fungal pathogens from agricultural products. RNA interference (RNAi) has shown potential to control fungi associated with crops. In RNAi, double-stranded RNA (dsRNA) targets homologous mRNA for cleavage, and can reach the mRNA of pathogens in contact with the plant. The key element in this process is the movement of RNA signals cell-to-cell and over long distances within the plant, and between host plants and parasites. • In this study, we selected a regulatory gene in the aflatoxin biosynthesis pathway, aflS/ aflR, necessary for the production of aflatoxins in Aspergillus spp. We designed a Dicersubstrate RNA (DsiRNA) to study the movement and stability of the duplex over time in in vitro peanut plants using stem-loop primers and RT-PCR for DsiRNA detection. • The preliminary results demonstrated that DsiRNA was absorbed and moved away from the point of application, spread systemically and was transported rapidly, most likely through the phloem of the shoot, to the sink tissues, such as new auxiliary shoots, flowers and newly formed pegs. The DsiRNA remained detectable for at least 30 days after treatment. •This is the first time that movement of exogenous DsiRNA in in vitro peanut plants has been described. Since DsiRNA was detectable in the pegs 15 days after treatment, aflatoxin reduction may be possible if the duplexes containing part of the aflatoxin biosynthesis pathogen gene induce silencing in the peanut seeds colonised by Aspergillus spp. The application of small RNAs could be a non-transformative option for mycotoxin contamination control

Detection of exogenous double-stranded RNA movement in \u3ci\u3ein vitro\u3c/i\u3e peanut plants

• New technologies are needed to eliminate mycotoxins and/or fungal pathogens from agricultural products. RNA interference (RNAi) has shown potential to control fungi associated with crops. In RNAi, double-stranded RNA (dsRNA) targets homologous mRNA for cleavage, and can reach the mRNA of pathogens in contact with the plant. The key element in this process is the movement of RNA signals cell-to-cell and over long distances within the plant, and between host plants and parasites. • In this study, we selected a regulatory gene in the aflatoxin biosynthesis pathway, aflS/aflR, necessary for the production of aflatoxins in Aspergillus spp. We designed a Dicersubstrate RNA (DsiRNA) to study the movement and stability of the duplex over time in in vitro peanut plants using stem-loop primers and RT-PCR for DsiRNA detection. • The preliminary results demonstrated that DsiRNA was absorbed and moved away from the point of application, spread systemically and was transported rapidly, most likely through the phloem of the shoot, to the sink tissues, such as new auxiliary shoots, flowers and newly formed pegs. The DsiRNA remained detectable for at least 30 days after treatment. • This is the first time that movement of exogenous DsiRNA in in vitro peanut plants has been described. Since DsiRNA was detectable in the pegs 15 days after treatment, aflatoxin reduction may be possible if the duplexes containing part of the aflatoxin biosynthesis pathogen gene induce silencing in the peanut seeds colonised by Aspergillus spp. The application of small RNAs could be a non-transformative option for mycotoxin contamination control

Exponential beams of electromagnetic radiation

We show that in addition to well known Bessel, Hermite-Gauss, and Laguerre-Gauss beams of electromagnetic radiation, one may also construct exponential beams. These beams are characterized by a fall-off in the transverse direction described by an exponential function of rho. Exponential beams, like Bessel beams, carry definite angular momentum and are periodic along the direction of propagation, but unlike Bessel beams they have a finite energy per unit beam length. The analysis of these beams is greatly simplified by an extensive use of the Riemann-Silberstein vector and the Whittaker representation of the solutions of the Maxwell equations in terms of just one complex function. The connection between the Bessel beams and the exponential beams is made explicit by constructing the exponential beams as wave packets of Bessel beams.Comment: Dedicated to the memory of Edwin Powe

Development of the dry tape battery concept

High energy anode and cathode for dry tape battery - incapsulation of electrolyte - manufacturing and testing of devic

Tsunami vulnerability of buildings and people in South Java ? field observations after the July 2006 Java tsunami

International audienceA team of scientists from New Zealand and Indonesia undertook a reconnaissance mission to the South Java area affected by the tsunami of 17 July 2006. The team used GPS-based surveying equipment to measure ground profiles and inundation depths along 17 transects across affected areas near the port city of Cilacap and the resort town of Pangandaran. The purpose of the work was to acquire data for calibration of models used to estimate tsunami inundations, casualty rates and damage levels. Additional information was gathered from interviews with eyewitnesses. The degree of damage observed was diverse, being primarily dependant on water depth and the building construction type. Water depths were typically 2 to 4 m where housing was seriously damaged. Damage levels ranged from total for older brick houses, to about 50% for newer buildings with rudimentary reinforced-concrete beams and columns, to 5?20% for engineered residential houses and multi-storey hotels with heavier RC columns. "Punchout" of weak brick walls was widespread. Despite various natural warning signs very few people were alerted to the impending tsunami. Hence, the death toll was significant, with average death and injury rates both being about 10% of the people exposed, for water depths of about 3 m

Stochastic simulations of the quantum Zeno effect

Published versio

Photon wave mechanics and position eigenvectors

One and two photon wave functions are derived by projecting the quantum state vector onto simultaneous eigenvectors of the number operator and a recently constructed photon position operator [Phys. Rev A 59, 954 (1999)] that couples spin and orbital angular momentum. While only the Landau-Peierls wave function defines a positive definite photon density, a similarity transformation to a biorthogonal field-potential pair of positive frequency solutions of Maxwell's equations preserves eigenvalues and expectation values. We show that this real space description of photons is compatible with all of the usual rules of quantum mechanics and provides a framework for understanding the relationships amongst different forms of the photon wave function in the literature. It also gives a quantum picture of the optical angular momentum of beams that applies to both one photon and coherent states. According to the rules of qunatum mechanics, this wave function gives the probability to count a photon at any position in space.Comment: 14 pages, to be published in Phys. Rev.