Kochen-Specker set with seven contexts

The Kochen-Specker (KS) theorem is a central result in quantum theory and has applications in quantum information. Its proof requires several yes-no tests that can be grouped in contexts or subsets of jointly measurable tests. Arguably, the best measure of simplicity of a KS set is the number of contexts. The smaller this number is, the smaller the number of experiments needed to reveal the conflict between quantum theory and noncontextual theories and to get a quantum vs classical outperformance. The original KS set had 132 contexts. Here we introduce a KS set with seven contexts and prove that this is the simplest KS set that admits a symmetric parity proof.Comment: REVTeX4, 7 pages, 1 figur

Quantum social networks

We introduce a physical approach to social networks (SNs) in which each actor is characterized by a yes-no test on a physical system. This allows us to consider SNs beyond those originated by interactions based on pre-existing properties, as in a classical SN (CSN). As an example of SNs beyond CSNs, we introduce quantum SNs (QSNs) in which actor is characterized by a test of whether or not the system is in a quantum state. We show that QSNs outperform CSNs for a certain task and some graphs. We identify the simplest of these graphs and show that graphs in which QSNs outperform CSNs are increasingly frequent as the number of vertices increases. We also discuss more general SNs and identify the simplest graphs in which QSNs cannot be outperformed.Comment: REVTeX4, 6 pages, 3 figure

Memory cost of quantum contextuality

The simulation of quantum effects requires certain classical resources, and quantifying them is an important step in order to characterize the difference between quantum and classical physics. For a simulation of the phenomenon of state-independent quantum contextuality, we show that the minimal amount of memory used by the simulation is the critical resource. We derive optimal simulation strategies for important cases and prove that reproducing the results of sequential measurements on a two-qubit system requires more memory than the information carrying capacity of the system.Comment: 18 pages, no figures, v2: revised for clarit

Approximate performance analysis of production lines with continuous material flows and finite buffers

In this paper, we analyze production lines consisting of a number of machines or servers in series with a finite buffer between each pair of machines. The flow of products through the machines is continuous. Each machine suffers from breakdowns, because of, for example, failures, cleaning and changeover. The up- and downtimes are independent and generally distributed. We develop a new method to efficiently and accurately estimate the throughput and the mean buffer content of the production line. This method relies on decomposition of the production line into two-stage, one-buffer subsystems aggregating the up- and downstream part of the line. For each subsystem, the parameters of the aggregate up- and downtimes are determined iteratively by employing matrix-analytic techniques. The proposed method performs very well on a large test set consisting of over 49,000 cases. Remarkably, the performance of the method does not deteriorate in case of highly unpredictable up- and downtimes, as often seen in practice. We apply the method to a bottling line at brewery Heineken Den Bosch and an assembly line at NXP Semiconductors

Performance analysis of production lines with continuous material flows and finite buffers

This paper deals with the approximative analysis of production lines with continuous material flow consisting of a number of machines or servers in series and finite buffers in between. Each server suffers from operational dependent breakdowns, characterized by exponentially distributed up- and down-times. We construct an iterative method to efficiently and accurately estimate performance characteristics such as throughput and mean total buffer content. The method is based on decomposition of the production line into single-buffer subsystems. Novel features of the method are (i) modeling of the aggregate servers in each subsystem, (ii) equations to iteratively determine the processing behavior of these servers, and (iii) use of modern matrix-analytic techniques to analyze each subsystem. The proposed method performs very well on a large test set, including long and imbalanced production lines. For production lines with imbalance in mean down-times, we show that a more refined modeling of the servers in each subsystem performs significantly better. Lastly, we apply the iterative method to predict the throughput of a bottle line at brewery Heineken Den Bosch yielding errors of less than two percent

Is emamectin benzoate effective against the different stages of Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae)?

peer-reviewedThis work was partially supported by the Spanish Ministry of Science and Innovation (project AGL 2007-66130-C03-02 to P. Medina). F. Amor and P. Bengochea acknowledge the ministry of Education and Culture and the Technical University of Madrid (UPM) for the doctoral fellowships. Special thanks to Syngenta Agro S.A. for their support.The beet armyworm, Spodoptera exigua (Hübner) (Lepidoptera, Noctuidae), is a major polyphagous pest in greenhouses and open fields worldwide and also a main problem in sweet pepper greenhouses. The effectiveness of the pesticide emamectin benzoate was tested in the laboratory on different stages of S. exigua using different concentrations and uptake routes. After dipping young (48-h-old) S. exigua eggs in emamectin benzoate at 0.5, 1 and 1.5 mg/L a.i. the chemical did not exhibit any ovicidal activity. There was, however, progressive neonate mortality at all concentrations, culminating at 72 hours after hatching, when 100% of the larvae from the treated young eggs died. Second and fourth instar S. exigua larvae did not exhibit significant mortality when exposed to the inert surfaces which were treated. In contrast, ingesting a diet contaminated with 0.5 mg/L a.i. of emamectin benzoate caused 100% mortality in L2 and L4 larvae 24 and 72 hours after ingestion, respectively. The LC50 value of the compound against L4 larvae that fed on sprayed sweet pepper leaves for 24 hours was 0.81 mg/L a.i.. When adults were fed on a solution of 0.5 mg/L a.i., there was a reduction in the female and male lifespan of 29.3% and 55.3%, respectively. Fecundity was reduced by more than 99%. These data suggest that emamectin benzoate is not only a useful insecticide when ingested by beet armyworm larvae but it also has ovolarvicidal and adult activity.Spanish Ministry of Science and Innovatio