Compact conical strain gauge probe for borehole over-coring rock massif stress measurement (CCBO), based on experiences of K. Sugavara and Y. Obara, has been developed in Institute of Geonics ASCR, v.v.i. from 2004. First generation of CCBO is equipped by simple electronic circuit which requires continuous communication with control computer in the course of measurement. Prototypes of this type probes are used for long term stress changes monitoring induced by longwall advancement in mine. Solving of continuous data communication through rotating drilling tool filled by wash water in course of over-coring is very difficult technical task, which is not possible to solve in terms of grant project. To avoid this problem a development of second generation of CCBO equipped by microprocessor and internal data logger was initialised. Simplified modification of CCBO is developed as a probe for long-term monitoring of rock massif stress changes (Compact Conical Ended Borehole Monitoring - CCBM). Design of both models probes, discussion of measurement errors and technique of sensitivity self-calibration is described., Jaromír Knejzlík, Zdeněk Rambouský, Kamil Souček and Lubomír Staš., and Obsahuje bibliografii
A secret sharing scheme is ideal if the size of each share is equal to the size of the secret. Brickell and Davenport showed that the access structure of an ideal secret sharing scheme is determined by a matroid. Namely, the minimal authorized subsets of an ideal secret sharing scheme are in correspondence with the circuits of a matroid containing a fixed point. In this case, we say that the access structure is a matroid port. It is known that, for an access structure, being a matroid port is not a sufficient condition to admit an ideal secret sharing scheme. In this work we present a linear secret sharing scheme construction for ports of matroids of rank 3 in which the size of each share is at most nn times the size of the secret. Using the previously known secret sharing constructions, the size of each share was O(n2/logn) the size of the secret. Our construction is extended to ports of matroids of any rank k≥2, obtaining secret sharing schemes in which the size of each share is at most nk-2 times the size of the secret. This work is complemented by presenting lower bounds: There exist matroid ports that require (Fq,ℓ)-linear secret schemes with total information ratio Ω(2n/2/ℓn3/4logq)., Oriol Farràs., and Obsahuje bibliografické odkazy
BACKGROUND: The male-female ratio at birth (M/F: male births divided by total births), which is anticipated to approximate 0.515, has been shown to exhibit latitude gradients and secular trends. METHODS: Annual national data for male and female live births for the 15 countries that comprise the former Soviet Union were obtained from the World Health Organisation for the period 1980-2009 (115,167,569 total live births) and analysed with contingency tables. Spearman correlation was also carried out to compare percentage annual gross domestic product growth (GDP%--downloaded from the World Bank) and M/F. In this context, GDP% is used as a measure for economic hardship or wellbeing within the populace. RESULTS: There have been overall highly significant secular increases in M/F (p < 0.0001) in the countries and regions investigated. M/F is significantly lower in the three more northern regions (Russian Federation, Baltic States and Central Asia. M/F 0.51324, 0.51335-0.51314) than the two more southern regions (Southern Caucasus and Eastern Europe. M/F 0.51654, 0.51635-0.51672). There was a male excess of 113,818 live births.There was a significant positive correlation between GDP% and M/F for Armenia, Azerbaijan and Uzbekistan. There was a significant negative correlation in Estonia. CONCLUSION: Previous studies have shown that improving socioeconomic conditions increase M/F, and the converse has also been demonstrated. This is a potential influence in this geographical area since this region has relatively recently emerged from communist rule and experienced an overall economic upturn, but is only partially supported using GDP%. Another factor may be the selective termination of female pregnancies. The latitude gradient parallels that of neighbouring Europe but no theory has been put forward to convincingly explain this finding to date. and V. Grech
BACKGROUND: Latitude gradients and secular trends in Europe and North America have been found in the male-female ratio at birth (M/F: male births divided by total births) which approximates 0.515. METHODS: Annual national data for Yugoslavia and the post-Yugoslavia States for male and female live births were obtained from the World Health Organisation and analysed with contingency tables. RESULTS: This study analysed 22,020,729 live births. There was a increasing trend in M/F prior to the breakup of the former Yugoslavia (1950-1990, p = 0.002), followed by a decreasing trend after 1990 (p = 0.02). A latitude gradient was also noted, with more males being born in southern, warmer latitudes (p < 0.0001). There was an overall excess of 42,753 male births based on an anticipated M/F of 0.515. CONCLUSION: M/F is decreasing in this region, similar to the rest of Europe and North America. A latitude gradient is also present with more males being born in warmer (more Southern) latitudes (p < 0.0001), even in this small region and over the short time-frame studied. and V. Grech