Horn antenna with v-shaped corrugated surface

Corrugated shape is easily machined for millimeter wave application and is better suited for folding antenna designs. Measured performance showed ""V'' corrugations and rectangular corrugations have nearly the same pattern beamwidth, gain, and impedance. Also, ""V'' corrugations have higher relative power loss

Evidence for RNA recombination between distinct isolates of Pepino mosaic virus.

Genetic recombination plays an important role in the evolution of virus genomes. In this study we analyzed publicly available genomic sequences of Pepino mosaic virus (PepMV) for recombination events using several bioinformatics tools. The genome-wide analyses not only confirm the presence of previously found recombination events in PepMV but also provide the first evidence for double recombinant origin of the US2 isolate

Representations of C*-dynamical systems implemented by Cuntz families

Given a dynamical system (A,\al) where $A$ is a unital \ca-algebra and \al is a (possibly non-unital) *-endomorphism of $A$, we examine families $(\pi,\{T_i\})$ such that $\pi$ is a representation of $A$, $\{T_i\}$ is a Toeplitz-Cuntz family and a covariance relation holds. We compute a variety of non-selfadjoint operator algebras that depend on the choice of the covariance relation, along with the smallest \ca-algebra they generate, namely the \ca-envelope. We then relate each occurrence of the \ca-envelope to (a full corner of) an appropriate twisted crossed product. We provide a counterexample to show the extent of this variety. In the context of \ca-algebras, these results can be interpreted as analogues of Stacey's famous result, for non-automorphic systems and $n>1$. Our study involves also the one variable generalized crossed products of Stacey and Exel. In particular, we refine a result that appears in the pioneering paper of Exel on (what is now known as) Exel systems.Comment: 29 pages; changes in subsection 1.2; close to publicatio

Hydrogen masers with cavity frequency switching servos

The stability of the free-running hydrogen maser is limited by pulling of the unperturbed hydrogen transition frequency due to instability of the cavity resonance frequency. While automatic spin-exchange tuning is in principle the more basic and accurate method, the required beam intensity switching and the long servo time constant result in reduced stability for measuring intervals up to 10(exp 6) seconds. More importantly, the spin-exchange tuning method requires a second stable frequency source as a reference, ideally a second hydrogen maser, to get the best results. The cavity frequency switching servo, on the other hand, has very little effect on the maser short term stability, and is fast enough to correct for cavity drift while maintaining the cavity at the spin-exchange tuned offset required to minimize instability due to beam intensity fluctuations. Not only does the cavity frequency switching servo not require a second stable frequency source, but the frequency reference is the atomic hydrogen radiated beam signal, so that no extra RF connections need be made to the cavity, and externally generated signals that would perturb the hydrogen atom need not be transmitted through the cavity. The operation of the cavity frequency switching stabilization method is discussed and the transient response of the servo and certain other aspects of the technique that have potential for achieving improved basic accuracy are illustrated

Test of the isotropy of the speed of light using a continuously rotating optical resonator

We report on a test of Lorentz invariance performed by comparing the resonance frequencies of one stationary optical resonator and one continuously rotating on a precision air bearing turntable. Special attention is paid to the control of rotation induced systematic effects. Within the photon sector of the Standard Model Extension, we obtain improved limits on combinations of 8 parameters at a level of a few parts in $10^{-16}$. For the previously least well known parameter we find $\tilde \kappa_{e-}^{ZZ} =(-1.9 \pm 5.2)\times 10^{-15}$. Within the Robertson-Mansouri-Sexl test theory, our measurement restricts the isotropy violation parameter $\beta -\delta -\frac 12$ to $(-2.1\pm 1.9)\times 10^{-10}$, corresponding to an eightfold improvement with respect to previous non-rotating measurements.Comment: 4 pages, 3 figures, to appear in Phys. Rev. Let

Quantifying loss of yield potential due to leaf disease.

To determine the impact of Septoria and barley yellow dwarf virus on wheat grown under the package approach on the south coast using different levels of fungicide and insecticide control on a susceptible variety of an appropriate maturity for early sowing. Examine if there is any benefit for disease control of S. tritici from Baytan seed dressing. 92AL16. Time of sowing and variety effects on the Septoria diseases of wheat. 92AL17. Time of sowing effect on barley foliar diseases. 92AL19. Evaluating variety mixtures to reduce Septoria using a range of lines. 92AL24. Fungicides for control of Septoria nodorum of wheat. 92BA19. Evaluating variety mixtures to reduce Septoria using a range of lines. 92BA20. Effects of Septoria avenae blotch on oat lines and cultivars varying in resistance, maturity and height. 92BA21. Fungicide control of leaf disease in early sown spear wheat. 92ES44 Effects of straw inoculum on leaf disease of wheat. 92BA52. Fungicide control of leaf disease in early sown spear wheat. 92ES44. Rates and timing of fungicides for control of leaf rust and Septoria. 92ES48. To evaluate a range of fungicides for control of leaf rust and other leaf diseases. 92GE90. To evaluate different rates and spray volumes of fungicide for control of leaf rust and Septoria. 92LG62. To evaluate different rates of fungicides for control of leaf rust and other Septoria. 92LG63. Evaluating variety mixtures to reduce Septoria using a range of lines. 92MT34. Effects of Septoria avenae blotch on oat lines and cultivars varying in resistance, maturity and height. 92MT35. Inoculum potential of 18 month old wheat stubbles. 92PE24.\ Response of elite breeding lines to Septoria nodorum. 92PE31. Fungicide control of leaf rust in Corrigin wheat. 92NA79. Fungicide control of wheat leaf rust. 92NO82. Effects of fungicide application on leaf rust and other diseases. 92NO99. Effect of fungicide on wheat leaf rust and Septoria in early sown dagger wheat. 92NO101. Rates and timing of tilt for control of leaf rust and Septoria in early sown spear. 92TS42. Rates and timing of tilt for control of leaf rust in late sown kulin. 92TS43

Scaling in the Bombay Stock Exchange Index

In this paper we study BSE Index financial time series for fractal and multifractal behaviour. We show that Bombay stock Exchange (BSE)Index time series is mono-fractal and can be represented by a fractional Brownian motion.Comment: 11 pages,3 figure