Is implicit motor imagery a reliable strategy for a brain computer interface?

Explicit motor imagery (eMI) is a widely used brain computer interface (BCI) paradigm, but not everybody can accomplish this task. Here we propose a BCI based on implicit motor imagery (iMI). We compared classification accuracy between eMI and iMI of hands. Fifteen able bodied people were asked to judge the laterality of hand images presented on a computer screen in a lateral or medial orientation. This judgement task is known to require mental rotation of a person’s own hands which in turn is thought to involve iMI. The subjects were also asked to perform eMI of the hands. Their electroencephalography (EEG) was recorded. Linear classifiers were designed based on common spatial patterns. For discrimination between left and right hand the classifier achieved maximum of 81 ± 8% accuracy for eMI and 83 ± 3% for iMI. These results show that iMI can be used to achieve similar classification accuracy as eMI. Additional classification was performed between iMI in medial and lateral orientations of a single hand; the classifier achieved 81 ± 7% for the left and 78 ± 7% for the right hand which indicate distinctive spatial patterns of cortical activity for iMI of a single hand in different directions. These results suggest that a special brain computer interface based on iMI may be constructed, for people who cannot perform explicit imagination, for rehabilitation of movement or for treatment of bodily spatial neglect

Do Addicts Behave Rationally?

Addicts, Rational Behavior

A Diffie-Hellman based key management scheme for hierarchical access control

All organizations share data in a carefully managed fashion\ud by using access control mechanisms. We focus on enforcing access control by encrypting the data and managing the encryption keys. We make the realistic assumption that the structure of any organization is a hierarchy of security classes. Data from a certain security class can only be accessed by another security class, if it is higher or at the same level in the hierarchy. Otherwise access is denied. Our solution is based on the Die-Hellman key exchange protocol. We show, that the theoretical worst case performance of our solution is slightly better than that of all other existing solutions. We also show, that our performance in practical cases is linear in the size of the hierarchy, whereas the best results from the literature are quadratic

PLAIN LANGUAGE W TEKSTACH PRAWNYCH – PERSPEKTYWA Z POLSKI

The purpose of this research is to explore plain-language postulates reflecting on legal drafting assumptions since legal acts should be precise, clear and express with no doubts the intention of the legislator. The aim of this project is to commence discussion about improving the clarity of Polish consumer law based on selected plain-language techniques. This article agrees that the aspiration to make the law comprehensible for all subjects is an idealistic postulate. Ultimately, despite this, legislators’ obligation is to make an effort to increase the intelligibility of legislation wherever it is possible.Przedmiotem artykułu, jest omówienie ruchu „plain legal language” czyli zrozumiałej i efektywnej komunikacji w tekstach prawnych. Zaprezentowany zostanie rozwój ruchu „plain language” oraz postulat powszechnego rozumienia prawa, w odniesieniu do polskich dyrektyw redagowania tekstu prawnego. Wybrane techniki i narzędzia standardu „plain language” zostaną w formie eksperymentu zaimplementowane do ustawy konsumenckiej. Artykuł opisuje rozwiązania, które potencjalnie mogą zwiększyć komunikatywność tekstów prawnych

Gifts for the afterlife: Evidence of mortuary practices on the necropolis at Marina el-Alamein

The paper considers the evidence for mortuary practices in the form of grave accompaniments and grave offerings recorded during excavations of the Graeco-Roman necropolis at Marina el-Alamein. Grave goods accompanying burials are modest and scarce. On the other hand, the evidence for offerings confirms that leaving symbolic food and liquids, as well as incense-burning at the graveside were a regular part of mortuary practices, both during the funeral and during later memorial rites. The prevalence of cooking-related and banqueting facilities underscore the importance of memorial feasts for the local community.Iwona Zyc