Thermoelectric performance of weakly coupled granular materials

We study thermoelectric properties of inhomogeneous nanogranular materials for weak tunneling conductance between the grains, g_t < 1. We calculate the thermopower and figure of merit taking into account the shift of the chemical potential and the asymmetry of the density of states in the vicinity of the Fermi surface. We show that the weak coupling between the grains leads to a high thermopower and low thermal conductivity resulting in relatively high values of the figure of merit on the order of one. We estimate the temperature at which the figure of merit has its maximum value for two- and three-dimensional samples. Our results are applicable for many emerging materials, including artificially self-assembled nanoparticle arrays.Comment: 4 pages, 3 figure

Spatial distribution of breeding Pied Flycatchers Ficedula hypoleuca in respect to their natal sites

Study of philopatry and dispersal of pied flycatchers Ficedula hypoleuca was launched on the Courish Spit (SE Baltic) in 1981. Since then, ca. 9,000 nestlings were ringed at different sites in the Russian part of the Courish Spit. A total of 557 individuals ringed as pulli were recaptured in subsequent seasons in the study area. Both males and females are more often recaptured in the plots where they were ringed than in other plots. These results were interpreted in the framework of the hypothesis forwarded by Löhrl (1959) and supported by Berndt & Winkel (1979). These authors suggested that cavity nesters (pied flycatchers and collared flycatchers F. albicollis) imprint their future local breeding area during the period of postfledging exploration. Birds that survive until the next spring, return to these imprinted areas to breed. A similar study done by Sokolov et al. (1984) on the Courish Spit in an open nesting species, the chaffinch Fringilla coelebs, confirmed this finding. We assumed that juvenile pied flycatchers disperse for varying distances during their postfledging movements and imprint a local area, some 1–5 kilometres in diameter. This area is the goal of their migration next spring. It is suggested that in spring, yearlings are non–randomly distributed in respect to the area they have imprinted as juveniles. Recently, Vysotsky (2000, 2001) re–analysed the same data on philopatry of pied flycatchers on the Courish Spit and forwarded an alternative hypothesis. He suggests that juveniles, both males and females, do not imprint any local area during the postfledging period, but are distributed randomly across the area of several dozens of kilometres in spring. Vysotsky was able to show that distribution of distances of natal dispersal did not differ from the random pattern the study plot which was an 8.5 km long line of nest boxes along the Courish Spit. The aim of this study was to test these two alternative hypotheses. To do so, we set up nine new study plots in 2000. Over 800 nest–boxes were made available for the birds (in addition to the old 400) in the 44 km long area. We recaptured pied flycatchers returning for breeding during four years, 2000–2003. The distribution of natal dispersal distances was compared with the null model which assumes that pied flycatchers settle randomly in the study area. We took all nest boxes from which pied flycatchers successfully fledged in a particular year and all next boxes where we were able to capture either a male or a female in the subsequent year, and calculated the distances between each pair of such nest boxes. Simulations were run separately for each sex. Theoretical distributions already include control efficiency. If some nest boxes were not checked in some year, or if we failed to capture one or both members of a breeding pair, we did not include this nest box in the model. Some birds could settle outside the study plot. Therefore, the theoretical distribution may underestimate the actual range of natal dispersal, but is unlikely to overestimate it. The number of females ringed as nestlings and recaptured as one–year–old birds was 43. The distribution of their natal distances (mean 6,8 km, SE = 0,81; median 5,4 km) was not significantly different from the pattern predicted by the null model (Wilcoxon matched pairs test: z = 1,25; p = 0,21). Conversely, males settled significantly closer to their natal nest box (n = 83; mean 4,3 km, SE = 0,57; median 2,5 km) than predicted by the model (Wilcoxon matched pairs test: z = 2,45; p = 0,014). For example, 24% of males settle within one km from their natal site, as compared with 7% predicted by the model. Males are found with a greater than chance probability within the 7 km zone around their natal site. The hypothesis by Vysotsky (2000) can thus be rejected for pied flycatcher males. Pied flycatcher females are known to settle at larger distances from their natal nest box. The very fact that were controlled 83 males and only 43 females suggests, assumed that sex ratio at fledging is close to being equal and that true survival rates during the first year of life do not differ greatly between the sexes, that many females emigrated from of our study plot. This does not mean that juvenile females do not imprint a home area during the postfledging period, as suggested by Vysotsky (2000). We think that the reason for this is not the inadequate navigational ability of the females but the fact that they were attracted by a prospecting male at some distance from their migratory destination and settle there. Such intercepting was suggested by Fedorov (1996) for Acrocephalus warblers, and it may exist in other migratory passerines. This is supported by the data on natal site fidelity from Spain which show that in Spanish pied flycatcher populations, recruitment rate did not differ between female and male juveniles (Potti & Montalvo, 1991). Females from these southern populations have a limited chance to be attracted by prospecting males in even more southern areas

Improving the accuracy of determining the character saturation reservoirs on the results of log interpretation in the oil field "K"(Tomsk region)

Log interpretation has revealed a number of factors that have a significant impact on the determination of reservoir fluid content (oil saturation factor). The presented research paper is focused on the analysis of petrophysical properties of reservoir fluids considering laboratory studies of core samples. Based on core sample analysis, data of laboratory studies have been correlated to estimates of radioactive logging and high-frequency induction logging. To determine the oil saturation factor a method which considers the effect of mixed clay on reservoir fluid saturation has been proposed

Результаты многолетних измерений на линейном базисе Коштице

Currently, electronic total stations based on the principles of laser long-range distance measurement are used for collecting geospatial information. As time goes, in the process of using the electronic total stations, their technical parameters vary, necessitating periodic calibration of the instruments. Calibration of the long-range distance measurement laser component of the electronic total stations is carried out at specialized baselines and consists in testing the constant component of an electronic total station, determining the scale error and determining the cyclic error. In the territory of the Czech Republic, two geodetic baselines are operated, the National Calibration Baseline Hvězda and Koštice. Koštice is the Czech State Long Distances Measuring Standard, where electronic total stations are calibrated. From 2017 to 2020, about 600 electronic total stations by different manufacturers Leica Geosystems, Trimble, Topcon, Sokkia, Nikon, Pentax, South and Geomax were calibrated. The total number of measurements performed under the program in all combinations has equaled about 40000. In this paper, results of analysis many years’ measurements performed at the geodetic baseline Koštice from 2017 to 2020 with electronic total stations manufactured by Leica Geosystems are presented. In total, 9186 measurements between the baseline sections 1–2, 1–3, 1–4, 1–5, 1–6, 1–7 and 1–8 have been analyzed. For each section, measurements have been detected which did not pass the Grubbs test criterion (the Smirnov – Grubbs test). Altogether, 261 outliers have been detected, totaling 3 % of the total number of measurements. After excluding the detected outliers with the algorithm of the parametric version of least squares optimization, the length of each section of the baseline was found, and the accuracy of the results obtained was evaluated. The calculated values of the length of the baseline sections are in generally good agreement with the results of the measurements performed at the geodetic baseline Koštice by the specialists from the laboratory of the Bundeswehr University in Munich (Germany) and the results of similar measurements conducted at the same baseline by the specialists from the Research Institute of Geodesy, Topography and Cartography (Czech Republic). For section 1–5, based on the results of both verifications, differences have been obtained exceeding the permissible values of the accuracy of determining baseline characteristics. This may be related to the fact that there are displacements of certain pillars, which mainly have a periodic character and depend on the season. To allow more specific assumptions regarding instability of certain pillars, it is recommended to verify the lengths of the baseline sections once in three months, according to the program in all combinations, which will allow comparison of the values of the confidence limits of the baseline section lengths and putting forward hypotheses regarding variations in the position of individual centers, so that the deviations revealed should be included into the residual uncertainty of length measurement.В настоящее время для сбора геопространственной информации широко используются электронные тахеометры, основанные на принципах лазерной дальнометрии. В процессе эксплуатации изменяются их технические параметры и возникает необходимость периодической калибровки. Она осуществляется на специальных линейных базисах и состоит в поверке постоянной cоставляющей электронного тахеометра, определении ошибки масштаба и циклической ошибки. На территории Чешской Республики действуют два линейных базиса – Гвезда и Коштице. Последний является национальным государственным эталоном длины дальних расстояний, на котором осуществляются поверки электронных тахеометров. С 2017 по 2020 год здесь выполнена калибровка порядка 600 тахеометров различных фирм (Leica Geosystems, Trimble, Topcon, Sokkia, Nikon, Pentax, South и Geomax), общее количество измерений во всех комбинациях около 40000. В статье представлены результаты анализа многолетних измерений, проведенных на линейном базисе Коштице тахеометрами фирмы Leica Geosystems. Исследованы 9186 измерений между секциями базиса 1–2, 1–3, 1–4, 1–5, 1–6, 1–7 и 1–8. По каждой секции выявлялись измерения, которые не прошли заданный критерий Смирнова – Граббса, обнаружен 261 выброс, что составляет 3 % всех измерений. После исключения выбросов с помощью алгоритма параметрической версии МНК-оптимизации определена длина каждой секции базиса и выполнена оценка точности полученных результатов. Вычисленные значения длин секций в целом хорошо согласуются с результатами измерений, проведенных на линейном базисе Коштице Лабораторией геодезии Военного университета Мюнхена (Германия) и Научно-исследовательского института геодезии, топографии и картографии. По секции 1–5 в ходе обоих сравнений получены разности, превышающие допустимые значения точности определения характеристик базиса. Это может быть связано с тем, что по отдельным пунктам наблюдаются смещения, которые носят в основном периодический характер и зависят от времени года. Для более конкретных предположений о нестабильности отдельных пунктов рекомендуется проводить поверку длин секций базиса один раз в три месяца по программе во всех комбинациях, что позволит сопоставлять значения доверительных границ длин секций базиса и выдвигать гипотезы о колебаниях положения отдельных центров. В дальнейшем это позволит включать полученные смещения в остаточную неопределенность измерения длины.    

Results of Many Years’ Measurements Conducted at the Czech State Long Distances Measuring Standard Koštice

Currently, electronic total stations based on the principles of laser long-range distance measurement are used for collecting geospatial information. As time goes, in the process of using the electronic total stations, their technical parameters vary, necessitating periodic calibration of the instruments. Calibration of the long-range distance measurement laser component of the electronic total stations is carried out at specialized baselines and consists in testing the constant component of an electronic total station, determining the scale error and determining the cyclic error. In the territory of the Czech Republic, two geodetic baselines are operated, the National Calibration Baseline Hvězda and Koštice. Koštice is the Czech State Long Distances Measuring Standard, where electronic total stations are calibrated. From 2017 to 2020, about 600 electronic total stations by different manufacturers Leica Geosystems, Trimble, Topcon, Sokkia, Nikon, Pentax, South and Geomax were calibrated. The total number of measurements performed under the program in all combinations has equaled about 40000. In this paper, results of analysis many years’ measurements performed at the geodetic baseline Koštice from 2017 to 2020 with electronic total stations manufactured by Leica Geosystems are presented. In total, 9186 measurements between the baseline sections 1–2, 1–3, 1–4, 1–5, 1–6, 1–7 and 1–8 have been analyzed. For each section, measurements have been detected which did not pass the Grubbs test criterion (the Smirnov – Grubbs test). Altogether, 261 outliers have been detected, totaling 3 % of the total number of measurements. After excluding the detected outliers with the algorithm of the parametric version of least squares optimization, the length of each section of the baseline was found, and the accuracy of the results obtained was evaluted. The calculated values of the length of the baseline sections are in generally good agreement with the results of the measurements performed at the geodetic baseline Koštice by the specialists from the laboratory of the Bundeswehr University in Munich (Germany) and the results of similar measurements conducted at the same baseline by the specialists from the Research Institute of Geodesy, Topography and Cartography (Czech Republic). For section 1–5, based on the results of both verifications, differences have been obtained exceeding the permissible values of the accuracy of determining baseline characteristics. This may be related to the fact that there are displacements of certain pillars, which mainly have a periodic character and depend on the season. To allow more specific assumptions regarding instability of certain pillars, it is recommended to verify the lengths of the baseline sections once in three months, according to the program in all combinations, which will allow comparison of the values of the confidence limits of the baseline section lengths and putting forward hypotheses regarding variations in the position of individual centers, so that the deviations revealed should be included into the residual uncertainty of length measurement

Alexandre Rumin, « Trappeur » du Paléolithique de la grotte de Kapova (Oural, Russie)

Pendant 24 ans, de 1934 à 1958, A.V. Rumin, docteur en biologie et spécialiste en zoologie, a élaboré une théorie de l’existence de l’art paléolithique dans les grottes de l’Oural méridional, supportée par deux collègues et amis : le paléontologue I.A. Efremov et l’archéologue A.Y. Brusov. Les recherches d’Alexandre Rumin sur le Paléolithique ont été couronnées de succès à partir du mois de janvier 1959, quand les premiers dessins et peintures anciennes murales, peintes à l’ocre (ours, loup, lion, cheval) ont été découvertes dans la grotte de Kapova (Choulgan-Tach). Cet article présente les descriptions de la faune du Paléolithique ainsi représentée. Une biographie de l’auteur est réalisée.During 24 years, from 1934 to 1958, A.V. Rumin, Doctor of biology with the speciality of the zoologist, elaborated his theory of the Palaeolithic art existence in caves of the Southern Ural, being supported by two of his friends: palaeontologist I.A. Efremov and archaeologist A. Ya. Brusov. The Palaeolithic trapper explorations has been successful in January 1959, when the first ancient images, painted with ochre, have been discovered in Kapova Cave (Shulgan-Tash). The descriptions of the cave fauna by the drawings and the several pictures, effectuated by A.V. Rumin, as well as his biography are presented

Accurate photon echo timing by optical freezing of exciton dephasing and rephasing in quantum dots

Semiconductor quantum dots are excellent candidates for ultrafast coherent manipulation of qubits by laser pulses on picosecond timescales or even faster. In inhomogeneous ensembles a macroscopic optical polarization decays rapidly due to dephasing, which, however, is reversible in photon echoes carrying complete information about the coherent ensemble dynamics. Control of the echo emission time is mandatory for applications. Here, we propose a concept to reach this goal. In a two-pulse photon echo sequence, we apply an additional resonant control pulse with multiple of 2π area. Depending on its arrival time, the control slows down dephasing or rephasing of the exciton ensemble during its action. We demonstrate for self-assembled (In,Ga)As quantum dots that the photon echo emission time can be retarded or advanced by up to 5 ps relative to its nominal appearance time without control. This versatile protocol may be used to obtain significantly longer temporal shifts for suitably tailored control pulses