Estimation of the Traffic Intensity in a Piecewise-stationary Mt/Gt/1 Queue with Probing

We use a probing strategy to estimate the time dependent traffic intensity in an Mt/Gt/1 queue, where the arrival rate and the general service-time distribution change from one time interval to another, and derive statistical properties of the proposed estimator. We present a method to detect a switch from a stationary interval to another using a sequence of probes to improve the estimation. At the end, we compare our results with two estimators proposed in the literature for the M/G/1 queue.

OfficialDiscourses in theeducationalsystems. Competencies: thenew curriculum password

The utility of knowledge has always been assumed to be one of the essential and structural questions in any educational and curriculum narrative. In fact, the utility of knowledge frames different designs for educational systems. Knowledge, as presented in public education systems, originates in the mainstream culture as an “accumulated capital for a future time or cultural ornament” (Beane, 2002, p.19). It is shaped and sequentially arranged in a compartmentalized way that often is far removed from everyday context of students. Moreover, knowledge is frequently framed as being needed for a certain or eventual future requirement. Historically there has always been a hierarchical relation within the formal structure of learning, involving contents (what), time (when), and utility (what for). The traditional difference in social status of the different kinds of knowledge and their utilities is connected with the way education emerges institutionally, as well as the demands of the economy. The concept of competence was born at the center of this tension and has been developing there, and there is must be rebuilt.

Satellite DNA as a target for TaqMan real-time PCR detection of the pinewood nematode, Bursaphelenchus xylophilus

The pinewood nematode (PWN), Bursaphelenchus xylophilus , is a major pathogen of conifers, which impacts on forest health, natural ecosystem stability and international trade. As a consequence, it has been listed as a quarantine organism in Europe. A real-time PCR approach based on TaqMan chemistry was developed to detect this organism. Specific probe and primers were designed based on the sequence of the Msp I satellite DNA family previously characterized in the genome of the nematode. The method proved to be specific in tests with target DNA from PWN isolates from worldwide origin. From a practical point of view, detection limit was 1 pg of target DNA or one individual nematode. In addition, PWN genomic DNA or single individuals were positively detected in mixed samples in which B. xylophilius was associated with the closely related non-pathogenic species B. mucronatus , up to the limit of 0.01% or 1% of the mixture, respectively. The real-time PCR assay was also used in conjunction with a simple DNA extraction method to detect PWN directly in artificially infested wood samples. These results demonstrate the potential of this assay to provide rapid, accurate and sensitive molecular identification of the PWN in relation to pest risk assessment in the field and quarantine regulation.