Victor R. Velasco

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Yellow rust of barley is an invasive disease that was found in the past 10 years in North America. The causal agent, Puccinia striiformis f. sp. hordei, was introduced into Colombia, South America, from Europe in 1975. It spread to all major barley-producing areas in South America by 1982. In 1988 it was found in Mexico and in 1991 in Texas. Since then it(More)
Classical systems containing cleverly devised combinations of loss and gain elements constitute extremely rich building units that can mimic non-Hermitian properties, which conventionally are attainable in quantum mechanics only. Parity-time (PT) symmetric media, also referred to as synthetic media, have been devised in many optical systems with the ground(More)
This paper describes the use of IP spoofing as a method of attacking a network in order to gain unauthorized access. The attack is based on the fact that Internet communication between distant computers is routinely handled by routers which find the best route by examining the destination address, but generally ignore the origination address. The(More)
In this paper, electrochemical behaviour of phenol in a carbon felt electrode is studied. An adsorption process on electrode surface that inhibits polymer formation after oxidation of phenol was confirmed. In this work we propose a phenol determination method based on direct electrochemical oxidation on carbon felt electrodes after an accumulation process.
We study the propagation of electromagnetic waves in one-dimensional quasiperiodic photonic band gap structures made of serial loop structures separated by segments. Different quasiperiodic structures such as Fibonacci, Thue-Morse, Rudin-Shapiro, and double period are investigated with special focus on the Fibonacci structure. Depending on the lengths of(More)
We study theoretically the propagation and localization of acoustic waves in quasi-periodic structures made of solid and fluid layers arranged according to a Fibonacci sequence. We consider two types of structures: either a given Fibonacci sequence or a periodic repetition of a given sequence called Fibonacci superlattice. Various properties of these(More)
We study theoretically and experimentally the properties of quasiperiodic one-dimensional serial loop structures made of segments and loops arranged according to a Fibonacci sequence (FS). Two systems are considered. (i) By inserting the FS horizontally between two waveguides, we give experimental evidence of the scaling behaviour of the amplitude and the(More)
The absorption coefficient and the photoluminescence of (001) GaN/AlN quantum wells are calculated for several values of the well width, with and without the excitonic effect corrections, in the usual monoelectronic approach and as a many-body problem. The calculation was performed considering separate isolated bands for electrons, heavy and light holes.(More)