Kochen-Specker Vectors

We give a constructive and exhaustive definition of Kochen-Specker (KS) vectors in a Hilbert space of any dimension as well as of all the remaining vectors of the space. KS vectors are elements of any set of orthonormal states, i.e., vectors in n-dim Hilbert space, H^n, n>3 to which it is impossible to assign 1s and 0s in such a way that no two mutually orthogonal vectors from the set are both assigned 1 and that not all mutually orthogonal vectors are assigned 0. Our constructive definition of such KS vectors is based on algorithms that generate MMP diagrams corresponding to blocks of orthogonal vectors in R^n, on algorithms that single out those diagrams on which algebraic 0-1 states cannot be defined, and on algorithms that solve nonlinear equations describing the orthogonalities of the vectors by means of statistically polynomially complex interval analysis and self-teaching programs. The algorithms are limited neither by the number of dimensions nor by the number of vectors. To demonstrate the power of the algorithms, all 4-dim KS vector systems containing up to 24 vectors were generated and described, all 3-dim vector systems containing up to 30 vectors were scanned, and several general properties of KS vectors were found.Comment: 19 pages, 6 figures, title changed, introduction thoroughly rewritten, n-dim rotation of KS vectors defined, original Kochen-Specker 192 (117) vector system translated into MMP diagram notation with a new graphical representation, results on Tkadlec's dual diagrams added, several other new results added, journal version: to be published in J. Phys. A, 38 (2005). Web page: http://m3k.grad.hr/pavici

Dental anxiety and dental attendance among 25-year-olds in Norway: time trends from 1997 to 2007

<p>Abstract</p> <p>Background</p> <p>So far, there are few studies considering the development of dental anxiety and dental attendance patterns across time in the general population of Norwegian adults. This study aimed to 1) determine the frequency of dental anxiety and regular dental attendance among 25-year-olds in Norway in 1997 and 2007, 2) to study the development (time trend) of dental anxiety and the socio-behavioral distribution of dental anxiety from 1997 to 2007.</p> <p>Method</p> <p>Random samples of 1,190 and 8,000 25-yr-olds were drawn from the populations of three counties in Western Norway in 1997 and 2007, respectively. The eligible participants received questionnaires by mail including questions on socio-demographics, dental anxiety (DAS) and dental attendance.</p> <p>Results</p> <p>In 1997, 11.5% males versus 23% females reported high dental anxiety (DAS ≥ 13). Corresponding figures in 2007 were 11.3% and 19.8%. The proportions who had attended yearly for a dental check-up during the past 5 years fell from 62% in 1997 (men 56.9% and women 66.4%) to 44.6% (men 38.1% and women 48.6%) in 2007. After controlling for potential confounding factors, the 25-year-olds were 1.4 times more likely to report dental anxiety in 1997 compared to 2007. The decrease was largely attributable to a lower mean DAS score among higher educated females in 2007 than in 1997. The discrepancy in dental anxiety between regular and non-regular dental attendees had decreased, largely attributable to a decline in dental anxiety among irregular dental attendees.</p> <p>Conclusion</p> <p>The study showed reduced dental anxiety and dental attendance among 25 year-olds in Norway from 1997 to 2007. This study points to the importance of controlling for possible changes in socio-demographic distributions when different cohorts are compared.</p

Factors influencing prescribing behaviour of physicians in Greece and Cyprus: results from a questionnaire based survey

<p>Abstract</p> <p>Background</p> <p>Over the past few decades, drug and overall healthcare expenditure have risen rapidly in most countries. The present study investigates the attitudes and the factors which influence physician prescribing decisions and practice in Greece and Cyprus.</p> <p>Methods</p> <p>A postal questionnaire was developed by researchers at the Department of Health Economics at the National School of Public Health in Greece, specifically for the purposes of the study. This was then administered to a sample of 1,463 physicians in Greece and 240 physicians in Cyprus, stratified by sex, specialty and geographic region.</p> <p>Results</p> <p>The response rate was 82.3% in Greece and 80.4% in Cyprus. There were similarities but also many differences between the countries. Clinical effectiveness is the most important factor considered in drug prescription choice in both countries. Greek physicians were significantly more likely to take additional criteria under consideration, such as the drug form and recommended daily dose and the individual patient preferences. The list of main sources of information for physicians includes: peer-reviewed medical journals, medical textbooks, proceedings of conferences and pharmaceutical sales representatives. Only half of prescribers considered the cost carried by their patients. The majority of doctors in both countries agreed that the effectiveness, safety and efficacy of generic drugs may not be excellent but it is acceptable. However, only Cypriot physicians actually prescribe them. Physicians believe that new drugs are not always better and their higher prices are not necessarily justified. Finally, doctors get information regarding adverse drug reactions primarily from the National Organisation for Medicines. However, it is notable that the majority of them do not inform the authorities on such reactions.</p> <p>Conclusion</p> <p>The present study highlights the attitudes and the factors influencing physician behaviour in the two countries and may be used for developing policies to improve their choices and hence to increase clinical and economic effectiveness and efficiency.</p

The validity of the EQ-5D-3L items: An investigation with type 2 diabetes patients from six European countries

Background: Most previous studies concerning the validity of the EQ-5D-3L items refer to applications of only a single language version of the EQ-5D-3L in only one country. Therefore, there is little information concerning the extent to which the results can be generalised across different language versions and