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4052. Secret sharing schemes for ports of matroids of rank 3
- Creator:
- Farràs, Oriol
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- teorie matroidů, matroid theory, secret sharing schemes, matroid ports, 23, and 007
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
4053. Secular trends and latitude gradients in sex ratios at birth in the former Soviet Republics
- Creator:
- Grech, Victor
- Format:
- print, text, and regular print
- Type:
- model:article, article, Text, časopisecké články, and TEXT
- Subject:
- porodnost--trendy, interpretace statistických dat, ženské pohlaví, lidé, novorozenec, mužské pohlaví, poměr pohlaví, and Světová zdravotnická organizace
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
4054. Secular trends and latitude gradients in the male-female ratio at birth in Yugoslavia and the ex-Yugoslavian States
- Creator:
- Grech, Victor
- Format:
- print, text, and regular print
- Type:
- model:article, article, Text, časopisecké články, and TEXT
- Subject:
- porodnost--etnologie--trendy, ženské pohlaví, zeměpis, lidé, mužské pohlaví, sekularismus, poměr pohlaví, and epidemiologie
- Language:
- English
- Description:
- 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
- Rights:
- http://creativecommons.org/publicdomain/mark/1.0/ and policy:public
4055. Segregace příměsí na hranicích zrn a mezikrystalová křehkost: významná česká stopa ve fyzice materiálů
- Creator:
- Lejček, Pavel, Šob, Mojmír, and Paidar, Václav
- Format:
- print, bez média, and svazek
- Type:
- model:article and TEXT
- Subject:
- fyzika, physics, fyzika materiálů, physics of materials, 6, and 53
- Language:
- Czech and English
- Description:
- Kovy a jejich slitiny jsou jedním ze základních konstrukčních materiálů používaných v technické praxi. Přestpže jsou jejich vlastnosti dostatečně známé, stále hrozí, že u kovových konstrukcí nebo jiejich součástí dojde k náhlému kolapsu v důsledku mezikrystalového křehkého lomu, který je způsoben postupnou změnou chemického složení oblastí mezi jednotlivými krystaly. Této problematice se po léta věnuje řada odborníků včetně českých specialistů. Článek pojednává o vztahu mezi chemií mezikrystalových oblastí - hranic zrn - a jejich soudružností a o tom, jakou stopu v této oblasti zanechali čeští vědci., Metals and their alloys belong to the basic construction materials used in technology and building. Although their properties are very well-known, there is always a danger that a sudden collapse occurs in metallic constructions, or in their parts, as a result of intergranular embrittlement. Such an embrittlement may be caused by a progressive change in chemical composition in the regions between individual crystals, i.e. grain boundaries. Many specialists, including Czechs, are engaged in finding a solution for this issue. This article deals with the relationship between the chemistry of grain boundaries and their cohesion, and demonstrates the footprint bequeathed by Czech scientists., Pavel Lejček, Mojmír Šob, Václav Paidar., and Obsahuje seznam literatury
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4056. Seismic activity in West Bohemia from 2001 - 2006
- Creator:
- Nehybka, Vladimír and Tilšarová, Radka
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, seizmologie, zemětřesení, seismology, earthquake, Čechy západní (Česko), Vogtland (Německo), Nový Kostel (Česko), Vogtland (Germany), Bohemia, Western (Czechia), Nový Kostel (Czechia), earthquake swarm, microearthquake, en echelon, tectonic line, 7, and 551
- Language:
- English
- Description:
- This article is concerned with seismicity in the region of West Bohemia - Vogtland after the Nový Kostel swarm of 2000. Seismicity during the period 2001 - 2006 is weak, though with several clusters of earthquakes; although these do not meet the criteria for a seismic swarm, their groupi ng in time and spacing along a line give an impression of tectonic disturbances and their behaviour in a period between swarms., Vladimír Nehybka and Radka Tilšarová., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4057. Seismic events in the Orawa-Nowy Targ Basin, Western Carpathians, November 30, 2004 - December 2005
- Creator:
- Guterch, Barbara
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, zemětřesení, earthquake, macroseismic data, Orawa-Nowy Targ Basin, Pieniny Klippen Belt, series of earthquakes, 7, and 551
- Language:
- English
- Description:
- An earthquake of magnitude M = 4.4, macroseismic intensity Io = 7 in the EMS scale, followed by a long series of aftershocks occurred on November 30, 2004 in southern margin of the Orawa-Nowy Targ Basin, Western Carpathians. Macroseismic epicentral data were determined for the main earthquake and the strongest aftershocks. The foci were shallow, less than 5 km i.e., originated in the Podhale Flysch. An array of seismic stations located in this seismically active area is necessary for better recognizing of the ongoing tectonic process., Barbara Guterch., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4058. Seismic measurements on a rock massif surface at short distances
- Creator:
- Vilhelm, Jan, Rudajev, Vladimír, Roman Živor, and Lokajíček, Tomáš
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, seizmicita, seismicity, repeatability of measurement, velocity measurement, seismic source, seismic P- and S-waves, 7, and 551
- Language:
- English
- Description:
- Various geotechnical tasks require the knowledge of rock properties, e.g., of elastic moduli, fracture systems, inhomogeneities, etc. Seismic measurements usually provide these parameters. To describe the detailed properties of small rock volumes, it is necessary to use high-frequency signals and suitable registration systems. Seismic measurements are carried out directly on rock surfaces. Although the conditions, under which measuremen ts are carried out, seem to be simple and convenient, practical measurements themselves are often complicated. The various measuring systems, including seismic sources and seismic receivers used for different base lengths, are discussed in this paper. It was found that, for the repeatability of measurements, the fixing of the sensors with plaster plays most significant role. Repeatability of hammer blow as seismic source is adversely affected namely by signal amplitude triggering. Pencil lead breaking tests with lead 1 and 6 mm in diameter were found as suitable for testing of the hi gh-frequency measuring systems. Measuring directly on the rock massif surface is different compared to exploration seismic measurements. Due to absence of a low-velocity layer it necessary to use a special choice of mutual orientation of sources and receivers. Polarization analysis may be advantageous to identify the arrival of P and S seismic waves. It was also found that the rock massif behaves as a narrow frequency-b and pass filter. For exciting frequencies of 0.1 and 1 MHz the transmitted signal displayed the same frequency of 25 kHz at a distance of 1.1 m., Jan Vilhelm, Vladimír Rudajev, Roman Živor and Tomáš Lokajíček., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4059. Seismicity and 10-years recent crustal deformation studies at Aswan region, Egypt
- Creator:
- Abdel-Monem, Mohamed S., Mohamed, Haggag H., Saleh, Mohamed, and Abou-Aly, Nadia
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, seizmicita, GPS sítě, seismicity, GPS netwoks, Asuán (Egypt), Aswan (Egypt), recent crustal deformation, Aswan region, 7, and 551
- Language:
- English
- Description:
- Since 1982, several study programs were in itiated for monitoring seismicity, unde rground water behavior and recent crustal movements. The main characteristics of the seismic activity and the seismotectonics of the Aswan region are investigated based on the recently recorded seismic activity from 1982 to 2010 and the geodetic results. The results from these data sets are compared and combined in order to determine the main characteristics of deformation and hazard estimation in the Aswan region. GPS observations are being carried out by Aswan ge odetic network twice a year since 1997 and still until now. Analysis of the repeated 10-years GPS campaigns from the network revealed horizont al movements at the level of 7 - 10 mm/a. The estimated strain rate tensors show compression and tension components in the directions WNW-ESE and NNE- SSW which consistent with the P- and T-axes derived from ear thquake fault plane solutions, respectively. The network are a has been suffered from post-seismic deformation during the present interval; hence an increase in the general earthquake activity in the area could be expected., Mohamed S. Abdel-Monem, Haggag H. Mohamed, Mohamed Saleh and Nadia Abou-Aly., and Obsahuje bibliografické odkazy
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public
4060. Seismicity and seismic hazard analysis in and around the proposed Tushka New City site, South Egypt
- Creator:
- Fat-Helbary, Raafat E., Khashab, Hussein M. El, Dojcinovski, Dragi, Faragawy, Karrar O. El, and Abdel-Motaal, Abdel-nasser M.
- Format:
- print, bez média, and svazek
- Type:
- article, články, model:article, and TEXT
- Subject:
- Geologie. Meteorologie. Klimatologie, seizmicita, seismicity, Egypt, seismic hazard, proposed Tushka New City site, acceleration, Kalabsha, 7, and 551
- Language:
- English
- Description:
- For the last decade the Egyptian government has planned to implement the Tushka project at the southeastern part of the western Desert. This project includes the construction of a number of new cities. Tushka New City is one of these cities. Tushka area has a complex tectonic and geological history. Although no historical earthquakes are known to have occurred in the Tushka area, five large earthquakes of magnitude between 5.1 and 6.2 were recently observed from four active zones located around Tushka area. In addition to these four zones many microearthquakes have been detected in and around Tushak area. The main purpose of this research is to elucidate the seismicity and estimate the seismic hazard due to this activity in the study area. According to the spatial distribution of earthquakes that located in and around the study area, 9 seismic zones are defined on the seismotectonic map. For each seismic zone the seismic hazard parameters are estimated and used as input data for seismic hazard analysis. The resulting probability distributions are taken to produce iso-acceleration map for specific periods and economic life of public structures. The hazard at the proposed Tushka New City site is given by the hazard curve that is represented by the relationship between the peak ground acceleration and its annual exceedance probability. The maximum peak ground acceleration is 49, 137, 157 and 177 cm/s2 (gal) for zones Z-1, Z-6, Z-9 and Z-4 respectively. Although the values of PGA in zones Z-4, Z-6 and Z-9 are almost the same, Z-4 has a significant effect on the proposed Tushka New City site due to its location about 140 km northeast to the study area, while the calculated maximum acceleration with 90 percent probability of not being exceeded in 50 years of exposure time (475 years return period) at the proposed Tushka New City site was about 22 cm/s2., Raafat E. Fat-Helbary, Hussein M. El Khashab, Dragi Dojcinovski, Karrar O. El Faragawy and Abdel-nasser M. Abdel-Motaal., and Obsahuje bibliografii
- Rights:
- http://creativecommons.org/licenses/by-nc-sa/4.0/ and policy:public