243 research outputs found
Middle Permian U-Pb Zircon Ages of the Glacial Deposits of the Atkan Formation, Ayan-Yuryakh Anticlinorium, Magadan Province, NE Russia: Their Significance for Global Climatic Interpretations
The Atkan Formation in the Ayan-Yuryakh anticlinorium, Magadan province, northeastern Russia, is of great interest because of the occurrence of deposits of apparent “dropstones” and “ice rafted debris” that have been previously interpreted as glacial. Two high-precision U-Pb zircon ages, one for an intercalated volcanic tuff (262.5 ± 0.2 Ma) and the other for a boulder clast (269.8 ± 0.1 Ma) within a diamictite of the Atkan Formation, constrain the age of the Atkan Formation as Guadalupian (middle Permian). Sedimentologic study of the Atkan Formation casts doubt on the glacial nature of the diamictites. Deposition of rocks of the Atkan Formation temporally correlates with the Capitanian interglacial event in the southern hemisphere that recently was calibrated with high precision CA-TIMS. The previously proposed climate proxy record based upon warm-water foraminifera, which corresponds closely to global climate fluctuations, is compared with the glacial record of eastern Australia and indicates that the Capitanian was a time of globally warm climate. The sedimentology of Atkan Formation, the record of diversification of both fusulinids and rugosa corals, global sea-water temperature, and sea-level fluctuations agree well with high latitude paleoclimate records in northeastern Russia and eastern Australia. Major components of the Atkan Formation, the volcanic rocks, are syngenetic with the sedimentation process. The volcanic activity in the nearby regions during middle-late Permian was quite extensive
New results of U–Pb SHRIMP dating of zircons from upper Wuchiapingian (Upper Permian) deposits in northeastern Russia
© 2017, Pleiades Publishing, Ltd. The first results are presented for U-Pb SHRIMP-II dating of zircons from the upper part of the Khivachian regional horizon (stage) of the Regional Stratigraphic Scale (RSS) of the Permian in northeastern Russia. The obtained isotope age of 255 ± 2 Ma is close to that of the present boundary between the Wuchiapingian and Changhsingian stages of the Permian system in the International Stratigraphic Scale (254.1 Ma). Based on the distribution of bivalves—Intomodesma spp. and Claraioides aff. primitivus (Yin)—in the sections considered, their relations to the stratigraphic positions of the samples considered and dated formerly, and in view of the interregional correlation of recent δ 13 С org data for clayey rocks, one may assume with certainty that most of the regional zone of Intomodesma costatum corresponds to the upper part of the Wuchiapingian stage. Here, the Changhsingian stage in northeastern Asia complies only with the uppermost part of this zone within the I. postevenicum subzone and, partially, of Otoceras layers within the Otoceras concavum zone
The first detailed δ<sup>13</sup>С<inf>оrg</inf>record in Permo-Triassic boundary deposits in the Kolyma–Omolon region (Northeast Asia)
© 2017, Pleiades Publishing, Ltd. We have obtained the first detailed δ 13 С org record in Permian-Triassic boundary sediments in deepwater facies in Northeast Asia (Kolyma–Omolon region, Balygychan Basin). Our data show good convergence both with the Setorym River section (South Verkoyansk region), where the Permian-Triassic boundary has been determined approximately, and with a number of other sections of Permian-Triassic boundary sediments in the Boreal and Tethyan Superrealms, in particular, in the Buchanan Lake section in Arctic Canada, the Festningen section on Spitsbergen, the Wadi Shahha section on the Arabian Peninsula, and published sections in the Dolomites
Permian diamictites in northeastern Asia: Their significance concerning the bipolarity of the late Paleozoic ice age
© 2015 Elsevier B.V. Despite a lack of detailed sedimentologic analyses, diamictites in the Middle Permian Atkan Formation were previously interpreted as glaciomarine and glacially-influenced marine deposits. This interpretation allowed this unit to play a prominent role in paleoclimatic and biogeographical reconstructions associated with presumed bipolar glaciation during the late Paleozoic ice age (LPIA). In this sense, the LPIA is considered to be a close analog to bipolar glaciation and climate change during the Cenozoic. Here, results are presented that challenge the glacigenic interpretation for these strata and negate interpretations of the bipolar nature of the LPIA. The 400 to 1500-m-thick Atkan Formation was deposited in back-arc basins associated with activity of the Okhotsk-Taigonos volcanic arc along the leading edge of Pangea as it drifted across the North Polar Circle. The occurrence of tuffs, volcanic clasts, and glass shards indicate derivation from a nearby arc. Cooling and solidification of some clasts during sedimentation is suggested by the occurrence of clasts with embayments and protrusions that extend into the surrounding matrix, clasts with columnar-like jointing, and alteration of the matrix surrounding some clasts. CA-TIMS dating of tuff zircons indicate a late Capitanian age, which is consistent with fossils within the strata. Bedded diamictites deposited as debrites dominate. These diamictites, which occur as tens of m thick downlapping packages that thicken then thin upward, were deposited as prograding and abandoning sediment gravity-flow fans. Chaotic and folded strata formed as slumps. Graded sandstones and conglomerates were deposited as turbidites, and mudstones were deposited as mudflows, low-density turbidites, and hemipelagic deposits. Striated clasts and outsized clasts piercing bedding were not observed in the study area. Strata above and below the Atkan Formation contain abundant graded beds and deep-water trace fossils indicating deposition as turbidites. The combination of debrites, turbidites, slumps, volcanic grains (clasts, glass, and tuffs), and an absence of glacigenic indicators suggest that Atkan strata were deposited in deep-water basins associated with the development of the volcanic arc rather than due to glacial activity. These findings are significant as they require reconsideration of current views of LPIA glaciation and suggest that ice sheets were limited to Gondwana
Middle Permian U-Pb zircon ages of the "glacial" deposits of the Atkan Formation, Ayan-Yuryakh anticlinorium, Magadan province, NE Russia: Their significance for global climatic interpretations
© 2015 International Association for Gondwana Research. The Atkan Formation in the Ayan-Yuryakh anticlinorium, Magadan province, northeastern Russia, is of great interest because of the occurrence of deposits of apparent "dropstones" and "ice rafted debris" that have been previously interpreted as glacial. Two high-precision U-Pb zircon ages, one for an intercalated volcanic tuff (262.5. ±. 0.2. Ma) and the other for a boulder clast (269.8. ±. 0.1. Ma) within a diamictite of the Atkan Formation, constrain the age of the Atkan Formation as Guadalupian (middle Permian). Sedimentologic study of the Atkan Formation casts doubt on the glacial nature of the diamictites. Deposition of rocks of the Atkan Formation temporally correlates with the Capitanian interglacial event in the southern hemisphere that recently was calibrated with high precision CA-TIMS. The previously proposed climate proxy record based upon warm-water foraminifera, which corresponds closely to global climate fluctuations, is compared with the glacial record of eastern Australia and indicates that the Capitanian was a time of globally warm climate. The sedimentology of Atkan Formation, the record of diversification of both fusulinids and rugosa corals, global sea-water temperature, and sea-level fluctuations agree well with high latitude paleoclimate records in northeastern Russia and eastern Australia. Major components of the Atkan Formation, the volcanic rocks, are syngenetic with the sedimentation process. The volcanic activity in the nearby regions during middle-late Permian was quite extensive
Middle Permian U–Pb zircon ages of the “glacial” deposits of the Atkan Formation, Ayan-Yuryakh anticlinorium, Magadan province, NE Russia: Their significance for global climatic interpretations
© 2015 International Association for Gondwana ResearchThe Atkan Formation in the Ayan-Yuryakh anticlinorium, Magadan province, northeastern Russia, is of great interest because of the occurrence of deposits of apparent “dropstones” and “ice rafted debris” that have been previously interpreted as glacial. Two high-precision U–Pb zircon ages, one for an intercalated volcanic tuff (262.5 ± 0.2 Ma) and the other for a boulder clast (269.8 ± 0.1 Ma) within a diamictite of the Atkan Formation, constrain the age of the Atkan Formation as Guadalupian (middle Permian). Sedimentologic study of the Atkan Formation casts doubt on the glacial nature of the diamictites. Deposition of rocks of the Atkan Formation temporally correlates with the Capitanian interglacial event in the southern hemisphere that recently was calibrated with high precision CA-TIMS. The previously proposed climate proxy record based upon warm-water foraminifera, which corresponds closely to global climate fluctuations, is compared with the glacial record of eastern Australia and indicates that the Capitanian was a time of globally warm climate. The sedimentology of Atkan Formation, the record of diversification of both fusulinids and rugosa corals, global sea-water temperature, and sea-level fluctuations agree well with high latitude paleoclimate records in northeastern Russia and eastern Australia. Major components of the Atkan Formation, the volcanic rocks, are syngenetic with the sedimentation process. The volcanic activity in the nearby regions during middle–late Permian was quite extensive
The model and the planning method of volume and variety assessment of innovative products in an industrial enterprise
In the long term, the innovative development strategy efficiency is considered as the most crucial condition for assurance of economic system competitiveness in market conditions. It determines the problem relevance of such justification strategies with regard to specific systems features and conditions of their operation. The problem solution for industrial enterprises can be based on mathematical models of supporting the decision-making on the elements of the innovative manufacturing program. An optimization model and the planning method of innovative products volume and variety are suggested. The feature of the suggested model lies in the nonlinear nature of the objective function. It allows taking into consideration the law of diminishing marginal utility. The suggested method of optimization takes into account the system features and enables the effective implementation of manufacturing capabilities in modern conditions of production organization and sales in terms of market saturation
Конусно-лучевая компьютерная томография в диагностике плоских деформаций стопы: проспективное исследование
INTRODUCTION: Flat deformities are one of the most common pathological changes of the feet. Flatfeet is a disease with high social significance, since it not only affects on the quality of life, but is also an important factor in classification of fitness for military service. The main method of diagnosis of these diseases is radiography of the feet in a lateral projection in the standing position. Despite numerous publications describing various methods for assessing the ratio of the bones of the foot, there is no consensus in the scientific community about the exact criteria for flatfoot and its degrees. At the same time, it is noted that the final conclusion is influenced not only by the method of evaluating the finished image, but also by the method of conducting the study. The construction of modern digital X-ray systems in most cases is not adapted for classical X-ray podography, and the study without special devices and the impossibility of strict adherence to the methodology lead to significant distortions of the results. It follows from this that specialized equipment is required for the diagnosis of flatfoot deformities, which allows developing a unified methodology for conducting research and limiting the possibilities of simulations and aggravations.OBJECTIVE: To determine the possibilities of cone-beam computed tomography in the diagnosis of flatfoot deformities in a standing position with a natural load.MATERIALS AND METHODS: This study included 100 patients underwent examination at the S.M.Kirov Military Medical Academy. All patients were examined using the classical radiography and using the cone-beam computed tomograph (CBCT) «ATRISS» (Electron, Russia). Tomograms were evaluated by two methods: using an averaged image and using a thin slice. The study was conducted by two doctors with the determination of the height and angle of the arch of the foot, followed by an assessment of the degree of flatfoot. Statistics. Statistical analysis was performed using Medcalc software (version 18.2.1). The absolute results of measurements for longitudinal and transverse flatfoot obtained by various methods were compared, as well as the time spent on the study (Wilcoxon and Friedman criteria), the degree of correlation between measurements (Spearman’s criterion), as well as the degree of consistency of the conclusions of two experts to identify longitudinal and transverse flat feet (Kappa-Cohen coefficient). RESULTS: Angle measurements in absolute values did not differ significantly between all the methods used (p=0.1803). There were significant differences between measurements of the height of the arch of the foot between the X-ray method and CBCT (p<0.01). In a comparative analysis of radiography and CBCT, two experts noted a high consistency of research results. CBCT made it possible to perform studies with less time (p<0.01). The effective dose for CBCT is significantly higher than for radiography (p<0.01), but does not exceed 0.12 mSv.DISCUSSION: According to the results of the study, it was found that the effectiveness of CBCT in the diagnosis of flatfoot deformities is not worse than classical radiography. At the same time, the CBCT allows you to avoid positioning errors, stacking and cases of attempted simulation. The effective dose for CBCT allows using the technique as a preventive study. Also, CBCT has a high throughput and allows you to get significantly more information in one scan than with radiography.CONCLUSION: CBCT in a standing position with a natural load is not worse then classical radiography techniques in the accuracy of diagnosis of flatfoot deformities. At the same time, the CBCT has extensive postprocessing capabilities, higher throughput, low radiation load, and also reduces the likelihood of methodological errors and cases of aggravation. CBCT is promising in the consciousness of a universal methodology for measuring and classifying of flatfoot with a more precise formulation of setting points for measuring the angles of the arch and deviation of the hallux.ВВЕДЕНИЕ: Плоские деформации являются одними из наиболее часто встречающихся патологических изменений стоп. Плоскостопие является заболеванием с высоким социальным значением, поскольку не только оказывает влияние на качество жизни отдельного человека, но и является важным фактором классификации на различные категории годности к военной службе. Основным методом диагностики этих заболеваний является рентгенография стоп в боковой проекции в условиях естественной нагрузки. Несмотря на многочисленные публикации, в которых описываются различные методики оценки соотношения костей стопы, в научной среде отсутствует единое мнение о точных критериях плоскостопия и его степеней. При этом отмечается, что на итоговое заключение влияет не только способ оценки готового изображения, но и особенности его получения. Конструкция современных цифровых рентгеновских аппаратов в большинстве случаев не приспособлена для проведения классической рентгеновской подографии, а выполнение исследования без специальных устройств и невозможность строгого соблюдения методики приводят к значительным искажениям результатов. Из этого следует, что для диагностики плоских деформаций стоп требуется специализированное оборудование, позволяющее разработать единую методику проведения исследования и ограничивающую возможности симуляций и агграваций.ЦЕЛЬ: Определить возможности конусно-лучевой компьютерной томографии в диагностике плоской деформации стоп в положении стоя с естественной нагрузкой.МАТЕРИАЛЫ И МЕТОДЫ: В данном исследовании принимали участие 100 пациентов, проходивших обследование в Военно-медицинской академии им. С. М. Кирова. Все пациенты были обследованы с использованием классической методики рентгенографии и с использованием конусно-лучевого компьютерного томографа (КЛКТ) «АТРИСС» («Электрон», Россия). Томограммы оценивались двумя методиками: с использованием усредненного изображения и с использованием тонкого среза. Исследование проводилось двумя врачами с определением высоты и угла свода стопы с последующей оценкой степени плоскостопия.Статистика. Статистический анализ проводился с использованием программного обеспечения Medcalc (версия 18.2.1). Сравнивались абсолютные результаты измерений на продольное и поперечное плоскостопие, полученные различными методиками, а также врем, затраченное на исследование (критерии Уилкоксона и Фридмана), степень корреляции между измерениями (критерий Спирмена), а также степень согласованности заключений двух экспертов на выявление продольного и поперечного плоскостопия (коэффициент Каппа-Коэна).РЕЗУЛЬТАТЫ: Измерения углов в абсолютных значениях значимо не различались между всеми используемыми методиками (p=0,1803). Отмечались значимые различия между измерениями высоты свода стопы между рентгенологическим методом и КЛКТ (p<0,01). При сравнительном анализе рентгенографии и КЛКТ двумя экспертами отмечалась высокая согласованность результатов исследований. КЛКТ позволяла выполнять исследования с меньшими затратами времени (р<0,01). Эффективная доза при КЛКТ значимо больше, чем при рентгенографии (р<0,01), но не превышает 0,12 мЗв.ОБСУЖДЕНИЕ: По итогам исследования было установлено, что эффективность КЛКТ в диагностике плоских деформаций стопы не уступает классической рентгенографии. При этом КЛКТ позволяет избежать ошибок позиционирования, укладки и случаев попытки симуляции. Эффективная доза при КЛКТ позволяет использовать методику в качестве профилактического исследования. Также КЛКТ обладает высокой пропускной способностью и позволяет за одно сканирование получить существенно больше информации, чем при рентгенографии.ЗАКЛЮЧЕНИЕ: КЛКТ с вертикальной нагрузкой не уступает классическим методикам рентгенографии в точности диагностики плоских деформаций стопы. При этом КЛКТ обладает широкими возможностями постпроцессорной обработки, более высокой пропускной способностью, низкой лучевой нагрузкой, а также позволяет снизить вероятность методологических ошибок и случаев аггравации. КЛКТ перспективна в сознании универсальной методики измерения и классификации плоскостопия с более точной формулировкой постановки точек для измерения углов свода и отклонения большого пальца стопы
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