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Ballesteros, Daniel, Andrew Farrant, Carole Nehme, Mark Woods, Dominique Todisco i Damase Mouralis. "Stratigraphical influence on chalk cave development in Upper Normandy, France: implications for chalk hydrogeology". International Journal of Speleology 49, nr 3 (wrzesień 2020): 187–208. http://dx.doi.org/10.5038/1827-806x.49.3.2319.
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Classically, the Upper Cretaceous Chalk Group aquifer of northwest Europe is conceptualized as a homogenous dual-porosity aquifer, with high porosity related to its fine-grained porous matrix, and intermediate hydraulic conductivity associated with fractures. However, an increasing number of hydrological studies visualize the Chalk as a heterogeneous karst aquifer due to the localised presence of dissolutionally enlarged conduits. Field investigation suggests that cave development is guided by distinct stratigraphical and tectonic discontinuities within the rock mass. Identifying which potential inception horizons within the Chalk aquifer are favoured, and why, is important for developing future robust conceptual models of groundwater behaviour. This study focusses on the Chalk of the Upper Normandy region in France where karstic conduits are common and are linked to major sources of groundwater for public water supply. We analyse the geometry and geomorphology of six chalk caves exposed in the Seine Valley with an aggregated length of over 5.7 km, along with other caves in southern England, and identify the key inception horizons associated with their development. The data shows that prominent Turonian, Coniacian and Santonian hardgrounds have influenced the development of 68% of the studied caves length, with sheet-flints and marl seams also playing a prominent role. Caves developed on or between hardgrounds typically display a complex interlinked anastomotic passage network, whereas passages subjected to paragenetic conditions caused by a high sediment flux tend to be concentrated into fewer, larger conduits. The new evidence from Normandy and Southern England demonstrates the role of lithostratigraphy, and in particular stratigraphical discontinuities on conduit development. The data reinforces the idea that the Chalk aquifer should be viewed as a heterogeneous triple porosity karstic aquifer, in which conduit development is influenced by key stratigraphical discontinuities. This improved conceptual model can be used to develop better groundwater flow models and improved catchment delineation.
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Ozgambaev, Kuralbay, i Dana Mun. "EXPERIENCE OF RESTORATION OF MONUMENTS OF FOLK ARCHITECTURE OF THE MANGYSTAU REGION". Bulletin of Kazakh Leading Academy of Architecture and Construction 83, nr 1 (15.01.2022): 55–63. http://dx.doi.org/10.51488/1680-080x/2022.1-08.
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The article examines examples of traditional memorial architecture, typical for the Mangistau region, made of local natural chalk stone. Methods and technologies of their restoration are studied on certain types of buildings, such as mausoleums, saganatams, cave mosques. Materials of natural and historical archival research were used. The data from the experience of the authors on the implementation of restoration work on these monuments, on the features of the restoration depending on the type of the monument of folk architecture are presented.
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Степкин, Виталий Викторович. "Мария Шерстюкова: к 200-летию преставления основательницы Белогорской пещеры". Традиции и современность, nr 32 (29.05.2023): 30–45. http://dx.doi.org/10.33876/2687-119x/2023-32/30-45.
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Поводом к написанию статьи стала знаменательная дата: 200-летие со дня кончины подвижницы благочестия Марии Константиновны Шерстюковой, основательницы Белогорской пещеры в Воронежской губ., самого протяженного культового подземелья в Восточной Европе. Целью исследования является рассмотрение формирования культа Марии-пещерницы на различных этапах истории Русской Православной Церкви. В работе рассматривается исторический контекст событий, связанных с основанием Белогорской пещеры в 1796 г. в меловом склоне долины реки Дон; анализируются различные архивные варианты биографии Марии Шерстюковой; затрагиваются народные легенды о Марии-пещернице; изучается развитие культа подвижницы благочестия, выясняется отношение к ней сегодня в Белогорском Воскресенском монастыре. Делается вывод об устоявшейся народной и церковной традиции почитания данной подвижницы благочестия. The article was written on the occasion of a memorable date: the 200th anniversary year from the death of Maria Konstantinovna Sherstjukova, who was a pious hermit and a founder of Belogorye cave in Voronezh region, the longest cult caves in Eastern Europe. The research objective is to consider Maria’s cult as a cave digger on different stages of the Russian Orthodox Church. The research paper deals with historical context of events connected with Belogorye cave foundation in 1796 in a chalk hillside of the Don river valley; analyzes different archival variants of Maria Sherstjukova’s biography; addresses folk tales about cave digger Maria; studies the development of the pious hermit cult, explores today attitude to her in Belogorie Resurrection Monastery. It is concluded about an established folk and church tradition to acknowledge the pious hermit.
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Stepkin, Vitaliy Viktorovich, i Aleksey Aleksandrovich Gunko. "Caves in catacomb movement of the Russian Orthodox Church on the territory of the Don and the Volga Region in 1920-1940s". Samara Journal of Science 7, nr 1 (1.03.2018): 197–201. http://dx.doi.org/10.17816/snv201871213.
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The paper examines creation and application history of cave space in catacomb movement of the Russian Orthodox Church on the territory of the Don and the Volga Region in 1920-1940s. Development of cave digging on these territories was promoted by the fact of their frontier position, allowing searching for a hiding place for the ideas, differing from the mainstream society. The caves use as shelters and places of worship in the Don Region is exemplified by the territory of Voronezh Region, where in the revolution period caves were dug in the chalk mass near the village of Karayashnik, and traditionally honored by the people loci of sacred space were used like caves in Divnogorye and on Shatrishche Mount. Caves near the village of Karayashnik were used as a place of worship by a conservative part of peasants being supporters of both the Patriarchal Church and the Fedorovtsy sect. Caves in Divnogorye were used by Joanites sect, caves on Shatrishche Mount were used by so-called True Orthodox Church. In addition to the chalk caves in the Don Region people used underground of houses as secret places of worship. Examples of such undergrounds are hidden caves in the villages of Troitskoe and Novopokrovka, equipped by one of communities of so-called True Orthodox Christians. The paper considers caves use in the Volga Region through the example of the territory of the Republic of Tatarstan, where communities of the True Orthodox Church acted, creating cult undergrounds under houses in the town of Bugulma and villages of Akkireevo, Zabugorovka, Crym-Saray Naumovka and Novoe Ilmovo. Together with territories of personal farmsteads, caves were created outside villages, usually in a forest zone. For example, near the village of Novosheshminsk there was an underground monastery, near villages of Volchya Sloboda and Elantovo there were underground temples. Activities of the underground religious communities referred to in the paper were ceased due to state punitive measures.
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Stepkin, Vitalii, i Ivan Smirnov. "An attempt at making a cave monastery in Kalach, Voronezh guberniya, in the late 19th — early 20th centuries". St. Tikhons' University Review 116 (29.02.2024): 55–63. http://dx.doi.org/10.15382/sturii2024116.55-63.
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Kalach caves dug out in a chalk relic in the town of Kalach, Voronezh region, is an underinvestigated historical and cultural heritage site. The archive materials found in the funds of RSHA, together with evidence of local people, provide insight into the final period of the cult dungeon functioning in the late XIX – early XX centuries. At that time the rural community of Kalach made an attempt to establish there an official orthodox cave monastery. On the 11th of August, 1885, residents of Kalach authorized peasants Ivan Serjakov, Matvey Bezugly and Gavriil Lebedinsky to solicit different authorities for a monastery foundation. The community also allocated 1300 roubles and 36 dessiatines of land area for the monastery arrangement. The rural community request was examined in Voronezh Ecclesiastical Consistory, Voronezh Provincial Government, Voronezh Provincial Peasant Council and in the Second (Peasant) Senate Department. The attempt was not successful, it encountered resistance of authorities. Meanwhile the cave diggers managed to accommodate the caves and arrange regular divine service by the local secular clergy. Functioning of the caves as a sacred locus for the rural community was interrupted by revolution events of early XX century. At present Kalach caves are put on Russian cultural heritage register.
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Kamruzzaman, Asm, Manika Prasad i Stephen Sonnenberg. "Petrophysical rock typing in unconventional shale plays: The Niobrara Formation case study". Interpretation 7, nr 4 (1.11.2019): SJ7—SJ22. http://dx.doi.org/10.1190/int-2018-0231.1.
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Production from organic-rich shale petroleum systems is extremely challenging due to the complex rock and flow characteristics. An accurate characterization of shale reservoir rock properties would positively impact hydrocarbon exploration and production planning. We integrate large-scale geologic components with small-scale petrophysical rock properties to categorize distinct rock types in low-porosity and low-permeability shales. We then use this workflow to distinguish three rock types in the reservoir interval of the Niobrara Shale in the Denver Basin of the United States: the Upper Chalks (A, B, and C Chalk), the Marls (A, B, and C Marl), and the Lower Chalks (D Chalk and Fort Hays Limestone). In our study area, we find that the Upper Chalk has better reservoir-rock quality, moderate source-rock potential, stiffer rocks, and a higher fraction of compliant micro- and nanopores. On the other hand, the Marls have moderate reservoir-rock quality and a higher source-rock potential. The Upper Chalks and the Marls should have major economic potential. The Lower Chalk has higher porosity and a higher fraction of micro- and nanopores; however, it exhibits poor source-rock potential. The measured core data indicate large mineralogy, organic richness, and porosity heterogeneities throughout the Niobrara interval at all scales.
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Степкин, В. В., i И. А. Смирнов. "Letters from D.M. Strukov’s fund in the Russian State Historical Archive and the dating of Via Dolorosa in Kalach caves, Voronezh Region". Proceedings in Archaeology and History of Ancient and Medieval Black Sea Region, nr 14 (23.09.2022): 263–70. http://dx.doi.org/10.53737/2713-2021.2022.85.17.011.
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Калачеевская культовая пещера в г. Калач Воронежской области вырублена в меловом останце. Суммарная протяжённость её ходов составляет 892 м. В ней имеются помещения различного назначения: храмы, часовни, кельи, коридоры и пр. Центральные и северные отрезки пещерных лабиринтов калькируют улицу Виа Долороза в Иерусалиме, символизирующую Крестный путь Иисуса Христа. Письма, обнаруженные в фонде Д.М. Струкова в РГИА, позволяют углубить и уточнить знания о датировке калачеевских лабиринтов. Вместе с тем, противоречивый характер этих сведений не позволяет сделать окончательный вывод о времени возникновения пещеры. Kalach cult caves are dug out in a chalk butte in the town of Kalach, Voronezh Region. Their total length makes 892 m. The caves contain rooms of different use: temples, chapels, cells, corridors, and more. Central and northern sections of cave labyrinths are known to replicate the Via Dolorosa in Jerusalemrepresenting Christ’s way of the Cross. The letters found in D.M. Strukov’s fund in the Russian State Historical Archive may enhance our insights into Kalach labyrinths dating. Concurrently, because of a contradictory character of the accounts under study, it is inconclusive exactly what the time of Kalach caves construction is.
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Peng, Bo, Jia-Qi Liang, Ran Zhang, Xia-Yu Tian, Chao Dong, Cuifeng Tang, Xin-Xiang A i in. "Determination and Analysis of the Content and Distribution of Mineral Elements in Black Rice by SEM-EDS". Journal of Agricultural Science 13, nr 9 (15.08.2021): 122. http://dx.doi.org/10.5539/jas.v13n9p122.
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Black rice has very superior medicinal value. Since ancient times, it has been used as a nourishing and health-care rice for medicine and food. It has powerful functions such as disease prevention, regulation of circadian rhythm, and promotion of physical recovery. It is suitable for long-term consumption. In this paper, optical microscope, scanning electron microscope and energy dispersive spectrometer (SEM-EDS) were used successively to visualize and quantitatively analyze the element distribution in the chalky and non-chalky areas of two indica rice varieties in Southern Henan. The results showed that black rice has rich C and O content, followed by N, P, S content, Mg, K, Ca, Mn, Zn content is less. The content of the O element in the chalky area is higher than that of the non-chalky area, while many elements such as C, N, P, S are significantly higher in the non-chalk areas than in the chalk areas; especially the N and S elements are the best indicators of protein, the content in chalkiness area was lower than that in non-chalky area. It can be inferred that the protein content in non-chalky part was higher than that in chalky part, that is, chalkiness character of black rice would affect the nutritional quality of rice. Therefore, our results showed the distribution of elements and protein in black rice, which is helpful for the cultivation of new high-quality black rice varieties in the future.
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WOOLHOUSE, G., J. E. ANDREWS, A. MARCA-BELL i P. F. DENNIS. "Geochemical constraints on the origin of enigmatic cemented chalks, Norfolk, UK". Geological Magazine 146, nr 2 (17.09.2008): 291–99. http://dx.doi.org/10.1017/s0016756808005487.
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AbstractVery hard cemented chalk stacks and crusts found locally in the upper part of the Cretaceous Chalk of north Norfolk, UK, are related to solution features. The solution features, mainly pipes and caves, formed after deposition of the overlying Middle Pleistocene Wroxham Crag, probably by routing of sub-glacial, or glacial, melt-waters derived from late Pleistocene glaciers. New geochemical (particularly stable isotope) data shows that cementation of the chalks, although related spatially to the solution features, was not caused by glacier-derived waters. The carbon isotope composition of the chalk cements is typically around −9.5‰, indicative of biologically active soils. Moreover, the oxygen isotope compositions of the cements, around −5‰, are incompatible with water δ18O values much below −9 to −10‰ (which probably precludes isotopically negative glacier-derived water), as resulting palaeo-temperatures are below zero. Taken together, the isotope data suggest chalk cementation occurred under interglacial conditions similar to the present. Dissolved calcium carbonate for cementation came from dissolution of reworked chalk in overlying MIS 12 glacial tills.
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Laignel, Benoit, i Robert Meyer. "La desilicification des silex des formations residuelles a silex de l'ouest du bassin de Paris". Bulletin de la Société Géologique de France 171, nr 5 (1.09.2000): 569–76. http://dx.doi.org/10.2113/171.5.569.
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Abstract In NW Europe, chalk areas are generally covered with clay-with-flints (CWF). These formations are made of flints with a clayey or silty-clayey matrix. In the literature devoted to CWF, the flint dissolution during the weathering of chalk was poorly studied. In this study, we provide an estimation of this phenomenon in the western Paris Basin, by comparisons between the flints of CWF and those of chalks based on mineralogy, size, cortex and surface cavities of flints. Our results show that the mineralogy and thickness of flints have not been affected by the weathering. Only the volumes of cortex and surface cavities have increased. These two parametres allow us to quantify the flint dissolution. Flint dissolution is low: the amount of dissolved silica in flints varies between 0.9 and 7.3%. These low values show that weathering of chalk who has led to the creation of CWF has not reached the intensity of a lateritic type weathering, as is the case in the ferralitic soil.
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Bell, F. G. "A survey of the geotechnical properties of some till deposits on the north coast of Norfolk". Geological Society, London, Engineering Geology Special Publications 7, nr 1 (1991): 103–10. http://dx.doi.org/10.1144/gsl.eng.1991.007.01.06.
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AbstractDeposits of till occur in the Anglian and Devensian stages of the Quaternary succession in Norfolk. These are the Cromer Till, the Chalky Boulder Clay and the Hunstanton Till, the former two occur in the Anglian stage and the latter in the Devensian stage. On the north coast of Norfolk the Chalky Boulder Clay has in the past been referred to as the Contorted Drift around Trimingham and further west, because of its chalk content, as the Marly Drift.Little work on the geotechnical properties of these tills in north Norfolk has been published. Accordingly an investigation was undertaken to determine their engineering behaviour. All these tills are matrix-dominated with clay forming less than a third of the matrix except in the case of the Marly Drift. They are either firm or stiff with low or intermediate plasticity and have shear strength values ranging between 50 and 115 kN/m2. The tills are either inactive or have normal activity and all have low sensitivity. Their consolidation properties are characteristic of stiff clays.
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Vyzhva, Z., V. Demidov i A. Vyzhva. "THE STATISTICAL SIMULATION OF DATASET IN 3D AREA WITH SPHERICAL СОRRELATION FUNCTION ON RIVNE NPP EXAMPLE". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 4 (91) (2020): 85–93. http://dx.doi.org/10.17721/1728-2713.91.12.
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Due to the increasing number of natural and technogenic disasters, the development of geological environment monitoring system is actual in using modern mathematical tools and information technology. The local monitoring of potentially dangerous objects is an important part of the overall environment monitoring system. The complex geophysical research was conducted on Rivne NPP area. The monitoring observations radioisotope study of soil density and humidity near the perimeter of buildings is of the greatest interest among these. In this case a problem occurred to supplement simulated data that were received at the control of chalky strata density changes at the research industrial area with use of radioisotope methods on a grid that included 29 wells. This problem was solved in this work by statistical simulation method that provides the ability to display values (the random field of a research object in 3D area) in any point of the monitoring area. The chalk strata averaged density at the industrial area was simulated using the built model and the involvement optimal in the mean square sense spherical correlation function. In this paper, the method is used and the model and procedure were developed with enough adequate data forsphericalcorrelation function. The model and algorithm were developed and examples of karst-suffusion phenomena statistical simulation were given in the problem of density chalk strata monitoring at the Rivne NPP area. The statistical model of averaged density chalk strata distribution was built in 3D area and statistical simulation algorithm was developed using spherical correlation functionbased on spectral decomposition. The research subject realizations were obtained with required detail and regularity at the observation grid based on the developed software. Statistical analysis of the numerical simulation results was done and tested for its adequacy.
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Vyzhva, Z., V. Demidov i A. Vyzhva. "STATISTICAL SIMULATION OF RANDOM FIELD ON 2D AREA WITH WHITTLE-MATERN TYPECORRELATION FUNCTION IN THE GEOPHYSICAL PROBLEM OF ENVIRONMENT MONITORING". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 3 (86) (2019): 55–61. http://dx.doi.org/10.17721/1728-2713.86.08.
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Due to the increasing number of natural and technogenic disasters the development of geological environment monitoring system is actual one using modern mathematical tools and information technology. The local monitoring of potentially dangerous objects is an important part of the overall environment monitoring system. The complex geophysical research was conducted on Rivne NPP area. The monitoring observations radioisotope study of soil density and humidity near the perimeter of buildings is of the greatest interest among these. In this case a problem occurred to supplement simulated data that were received at the control of chalky strata density changes at the research industrial area with use of radioisotope methods on a grid that included 29 wells. This problem was solved in this work by statistical simulation method that provides the ability to display values (the random field of a research object on a plane) in any point of the monitoring area. The chalk strata averaged density at the industrial area was simulated using the built model and the involvement optimal in the mean square sense Whittle-Matern type correlation function. In this paper the method is used and the model and procedure were developed with enough adequate data for Whittle-Matern type correlation function. The model and algorithm were developed and examples of karst-suffusion phenomena statistical simulation were given in the problem of density chalk strata monitoring at the Rivne NPP area. The statistical model of averaged density chalk strata distribution was built in the plane and statistical simulation algorithm was developed using Whittle-Matern type correlation function on the basis of spectral decomposition. The research subject realizations were obtained with required detail and regularity at the observation grid based on the developed software. Statistical analysis of the numerical simulation results was done and tested for its adequacy.
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Vyzhva, Z., V. Demidov i A. Vyzhva. "STATISTICAL SIMULATION OF RANDOM FIELD ON 2D AREA WITH GENERALIZED GNEITING TYPE CORRELATION FUNCTION IN THE GEOPHYSICAL PROBLEM OF ENVIRONMENT MONITORING". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 3(98) (2022): 86–91. http://dx.doi.org/10.17721/1728-2713.98.11.
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Due to the increasing number of natural and technogenic disasters the development of geological environment monitoring system is actual using modern mathematical tools and information technology. The local monitoring of potentially dangerous objects is an important part of the overall environment monitoring system. Complex geophysical research was conducted on Rivne NPP area. Among these monitoring observations radioisotope study of soil density and humidity near the perimeter of buildings is of the greatest interest. In this case a problem was occurred to supplement simulated data that were received at the control of chalky strata density changes at the research industrial area with use of radioisotope methods on a grid that included 29 wells. This problem was solved in this work by statistical simulation method that provides the ability to display values (random field on a plane) in any point of the monitoring area. The chalk strata averaged density at the industrial area was simulated using the built model and the involvement optimal in the mean square sense correlation function generalized Gneiting type. In this paper the method is used and the model and procedure were developed with enough adequate data for generalized Gneiting type correlation function. The model and algorithm were developed and examples of karst-suffusion phenomena statistical simulation were given in the problem of density chalk strata monitoring at the Rivne NPP area. The statistical model of averaged density chalk strata distribution was built in the plane and statistical simulation algorithm was developed using generalized Gneiting type correlation function based on spectral decomposition. The research subject realizations were obtained with required detail and regularity at the observation grid based on the developed software. Statistical analysis of the numerical simulation results was done and tested for its adequacy.
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VYZHVA, Zoya, Vsevolod DEMIDOV i Andrii VYZHVA. "THE STATISTICAL SIMULATION OF DATASET IN 3D AREA WITH "CUBIC" СОRRELATION FUNCTION ON EXAMPLE RIVNE NPP GEOPHYSICAL MONITORING". Visnyk of Taras Shevchenko National University of Kyiv. Geology, nr 3 (106) (2024): 90–98. http://dx.doi.org/10.17721/1728-2713.106.12.
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Background. The model and algorithm were developed by using optimal in the mean square sense "cubic" correlation function. An example of supplementing the results of geophysical studies of karst-suffuses phenomena with simulated data in the task of monitoring the density of the chalk stratum on the territory of the Rivne NPP is presented. The complex geophysical research was conducted on Rivne NPP area. The monitoring observations radioisotope study of soil density and humidity near the perimeter of buildings is of the greatest interest among these. In this case a problem was occurred to supplement simulated data that were received at the control of chalky strata density changes at the research industrial area with use of radioisotope methods on a grid that included 29 wells. This problem was solved in this work by statistical simulation method that provides the ability to display values (the random field of a research object in 3D area) in any point of the monitoring area. Methods. Based on the spectral decomposition of random fields in 3D space, a statistical model of the distribution of the average density of the chalk layer in the 3D observation area was built. Results. An algorithm for statistical simulation of random fields with a "cubic" correlation function is formulated. On the basis of the developed software, additional simulated realizations of the random component of the research subject on the grid of observations of the necessary detail and regularity were obtained. A statistical analysis of the results of the numerical simulation of the distribution of the average density of the chalk layer was carried out and their adequacy was tested. Conclusions. The method of statistical modeling of random fields with "cubic" correlation functions allows you to supplement data with a given accuracy.
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Dietrich, James K., i John Donald Scott. "Modeling Thermally Induced Strain in Diatomite". SPE Journal 12, nr 01 (1.03.2007): 130–44. http://dx.doi.org/10.2118/97849-pa.
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Summary Diatoms and radiolarians are microorganisms that precipitate Opal-A to form siliceous tests that accumulate on the seafloor to form siliceous oozes. Progressive diagenesis of these deposits during burial results in thick, highly compressible reservoirs of exceptionally high porosity and low permeability, not unlike the chalk reservoirs of the North Sea. During burial and over time, the amorphous silica phase (Opal-A) becomes unstable and gradually changes in its structure to more stable, ordered Opal-A' and crystalline forms or phases of silica, namely Opal-CT and quartz. The Opal-A ? Opal-A' ? Opal-CT ? quartz transformation results in a naturally occurring densification and compaction process that is accelerated by an application of heat. Reservoir compaction and surface subsidence can usually be controlled by injecting fluid to control the effective stress. However, in heavy-oil diatomite reservoirs undergoing steam injection, the injected fluid causes competing effects: it controls effective stress to some degree, yet at the same time it accelerates compaction and subsidence. This paper describes selected results of a diatomite laboratory testing program and features of a unique thermal reservoir simulator formulated to handle the effects on compaction caused by stress, temperature, and time-dependent strain (creep). Elevated temperature in amorphous Opal-A diatomite is shown to be capable of causing a sample compression of 25% or more and a severe reduction in permeability. The effects of thermally induced compaction are expected to accelerate surface subsidence as diatomite steam projects mature. Introduction There is a class of problems involving reservoir compaction of cohesive rocks (e.g. chalk, shale, and diatomite) in which the effects of stress are of a second-order importance compared to those of temperature. The injection of cold seawater in North Sea chalk reservoirs under conditions of invariant effective stress has led to continued compaction and subsidence (Cook et al. 2001; Sylte et al. 1999). The North Sea chalks are nearly pure calcium carbonate, and it is well known that the solubility of calcium carbonate increases as the water temperature decreases. Thus, even under conditions of unchanging effective stress, one would expect gradually increasing dissolution of calcium carbonate and compaction as the reservoir temperature of the chalk (~ 270°F) is gradually lowered by cold seawater injection (Dietrich 2001). In the giant Wilmington field of California, the shaly siltstones that are interbedded with the unconsolidated sands have recently been shown to be much more susceptible to thermally induced compaction than to stress-induced compaction (Dietrich and Norman 2003). And finally, diatomite is known to undergo a silica-phase transformation as temperature is raised, whereby amorphous Opal-A is converted to a more dense, crystalline Opal-CT. The injection of steam into California diatomite reservoirs is expected to accelerate this naturally occurring process and lead to rapid densification and compaction. In each case, for chalk, shaly rocks, and diatomite, there is both a laboratory and field basis that demonstrates the dominant role played by temperature.
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Patitsas, A. J. "Squeal vibrations, glass sounds, and the stick-slip effect". Canadian Journal of Physics 88, nr 11 (listopad 2010): 863–76. http://dx.doi.org/10.1139/p10-077.
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The origin of the squeal acoustic emissions when a chalk is rubbed on a blackboard or better on a ceramic plate, and those when a wet finger is rubbed on a smooth surface, such as a glass surface, is sought in the stick-slip effect between the rubbing surfaces. In the case of the squealing chalk, the stick-slip effect is anchored by shear modes of vibration in about a 0.3 mm thick chalk powder band at the rubbing interface, while in the case of the wet finger on glass, by such modes in a band comprising the finger skin. Furthermore, there are the interfacial bands at the contact areas that result in the decrease of the friction coefficient with relative velocity of slide, i.e., the condition for the stick-slip effect to occur. Such bands are basically composed of the asperities on the surface of the chalk band and of the epidermis ridges and the water layer, respectively.
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Doghman, Mirna, Hussein Mroueh i Sébastien Burlon. "Piles in chalk under axial loading". MATEC Web of Conferences 281 (2019): 01002. http://dx.doi.org/10.1051/matecconf/201928101002.
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Chalk exhibits a viscous behavior depending on time and it presents a noticeable creep under constant load. Consequently, piles founded in chalk media may have their design greatly affected. However, the different standards of the design of deep foundations don’t take into account this viscous behavior and its effect on the pile settlement in the long term. This paper deals with the case of piles under monotonic axial loads in chalk. Two methods of predicting pile settlement are developed: the transfer curves method tz, taking into account the viscosity, and the macroelement technique.
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Szász, Zsuzsánna Ágnes, Enikő Székely-Vass, Gyopár Horváth i Mădălina Hozoi. "Chalk-induced Lung Fibrosis — Case Report". Journal of Interdisciplinary Medicine 2, nr 4 (1.12.2017): 357–61. http://dx.doi.org/10.1515/jim-2017-0089.
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Abstract Introduction: Our article underlines the importance of a good professional anamnesis, knowing all the chemical components with which the patient had been exposed to during her active life as a teacher. Case presentation: A 64-year-old female patient, teacher for 27 years, who had been retired for six years, presented cough with white phlegm and shortness of breath occurring during physical exertion, diffuse thoracic pain, and fatigue. Several lung functional tests were performed, which established the diagnosis of irreversible minor mixed ventilatory dysfunction. In order to establish the etiology of the patient’s symptoms, multiple clinical, laboratory, imaging, and functional investigations were performed including a chest radiograph, pulmonary functional testing, bronchial reversibility testing, a thoracic CT scan, fibrobronchoscopy, alveolar-capillary diffusion capacity measurement, otorhinolaryngology examination, thyroid ultrasound, as well as a cardiological consult. Finally, a positive diagnosis was established: bronchial hyperreactivity syndrome, chalk dust-induced diffuse pulmonary fibrosis. Conclusion: An essential part of clinical practice is a proper anamnesis, including detailed information on the professional history and exposure, as well as the composition of the dust/particles with which the patient had been in contact with.
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Way, Der-Lor, i Cheng-Han Hsieh. "3D street art illusions: embedding chalk stylized rendering of 3D objects into a pavement photo". Computer Animation and Virtual Worlds 26, nr 6 (7.10.2014): 563–75. http://dx.doi.org/10.1002/cav.1624.
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Stollsteiner, P., H. Bessiere, J. Nicolas, D. Allier i O. Berthet. "Contribution of piezometric measurement to knowledge and management of low water levels: examples on the chalk aquifer in the Champagne Ardennes region". Proceedings of the International Association of Hydrological Sciences 366 (10.04.2015): 161. http://dx.doi.org/10.5194/piahs-366-161-2015.
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Abstract. This article is based on a BRGM study on piezometric indicators, threshold values of discharge and groundwater levels for the assessment of potentially-exploitable water resources of chalky watersheds. A method for estimating low water levels based on groundwater levels is presented from three examples representing chalk aquifers with different cycles: annual, combined and interannual. The first is located in Picardy and the two others in the Champagne-Ardennes region. Piezometers with annual cycles, used in these examples, are supposed to be representative of the aquifer hydro-dynamics. Except for multi-annual systems, the analysis between discharge measurements at a hydrometric station and groundwater levels measured at a piezometer representative of the main aquifer, leads to relatively precise and satisfactory relationships within a chalky context. These relationships may be useful for monitoring, validation, extension or reconstruction of the low water flow data. On the one hand, they allow definition of the piezometric levels corresponding to the different alert thresholds of river discharges. On the other hand, they clarify the proportions of low surface water flow from runoff or drainage of the aquifer. Finally, these correlations give an assessment of the minimum flow for the coming weeks. However, these correlations cannot be used to optimize the value of the exploitable water resource because it seems to be difficult to integrate the value of the effective rainfall that could occur during the draining period. Moreover, in the case of multi-annual systems, the solution is to attempt a comprehensive system modelling and, if it is satisfactory, using the simulated values to get rid of parasites or running the model for forecasting purposes.
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Montgomery, William. "Charles Darwin's Theory of Coral Reefs and the Problem of the Chalk". Earth Sciences History 7, nr 2 (1.01.1988): 111–20. http://dx.doi.org/10.17704/eshi.7.2.48j0677wp2p7mx62.
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Darwin's effort to relate his theory of coral reefs to global tectonic concepts failed to impress geologists more immediately interested in European phenomena. Charles Lyell had initially regarded coral reefs as a way to explain the European Chalk formation. However, he encountered criticism from catastrophist authors who thought the Chalk was a result of chemical precipitation. Lyell embraced Darwin's coral reef theory in an effort to strengthen his argument; and though C. G. Ehrenberg explained the Chalk as the product of fossil Foramanifera, he reinforced the general case in favor of organic deposition as opposed to chemical precipitation. As a result geologists tended to follow Lyell in discussing coral reef formation in the larger context of carbonate deposition generally.
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Kosolapov, Vladimir M., Vladmir I. Cherniavskih, Elena V. Dumacheva, Luiza D. Sajfutdinova, Alexander A. Zhuchenko, Alexey P. Glinushkin, Helena V. Grishina i in. "Using Microorganismal Consortium and Bioactive Substances to Treat Seeds of Two Scots Pine Ecotypes as a Technique to Increase Re-Afforestation Efficiency on Chalk Outcrops". Forests 14, nr 6 (25.05.2023): 1093. http://dx.doi.org/10.3390/f14061093.
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The present research is focused on various pine ecotypes’ seed reproduction in the chalky substrate, challenging environmental conditions on the carbonate soils on chalk outcrops in the south of the Central Russian Upland in relation to pine woods re-afforestation. The winter and spring sowing methods were studied, along with a pre-seeding treatment, by biopreparations based on a consortium of Glomales fungi, bacteria of the genus Bacillus, and bioactive substances. The seeds of two pine ecotypes, Pinus sylvestris L.; Pinus sylvestris var. cretacea Kalenicz exKom, underwent treatment. The study revealed that biopreparations and bioactive substances promote higher pine seed germination rates and ensure the stability and survivability of seedlings in an environment that is unfavorable for plant and tree ontogenesis. Applying biopreparations proved effective during spring sowing, whereas, in the case of winter sowing, their positive impact was not statistically significant. The net effect size of the three organized factors studied in the experiment (pine ecotype, biopreparation, sowing term) (h2x) on the “survivability of P. sylvestris seedlings” effective feature significantly increased from 90.8 to 93.8%. The effect size of the “pine ecotype” factor on seedling survivability in P. sylvestris was at its highest (14.4%) during the seedlings’ first-year growth period. The effect size of the “sowing term” factor was at its highest (79.4%) at the stage of seed germination. The effect size of the “biopreparation” factor was at its highest (44.0%) during the seedlings’ second-year growth stage. Our results indicate that it is preferable to create forest plantations on chalk outcrops using Pinus sylvestris var. cretacea ecotypes and with pre-sowing seed treatment via biopreparations based on a microorganismal consortium and Biogor KM. The Spearman correlation between the nitrification capacity of soil substrate and seedling survivability during the first three growth periods (from planting till the next year’s springtime) was of a moderate size (rs = 0.617–0.673, p < 0.05). To improve the growth and productivity of young and mature Scots pine stands, a Biogeosystem Technique (BGT*) methodology was developed.
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Andreassen, Katrine Alling, i Ida Lykke Fabricius. "Biot critical frequency applied to description of failure and yield of highly porous chalk with different pore fluids". GEOPHYSICS 75, nr 6 (listopad 2010): E205—E213. http://dx.doi.org/10.1190/1.3504188.
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Injection of water into chalk hydrocarbon reservoirs has led to mechanical yield and failure. Laboratory experiments on chalk samples correspondingly show that the mechanical properties of porous chalk depend on pore fluid and temperature. In case of water-saturated samples, the concentration and nature of dissolved salts have an effect. Water has a significant softening effect on elastic properties of chalk as calculated from wave data, and the softening increases with increasing critical frequency as defined by Biot. The critical frequency is the highest frequency where elastic wave propagation is controlled by solid-fluid friction. The reference frequency is thus a measure of this friction, and we propose that the fluid effect on mechanical properties of chalk may be the result of liquid-solid friction. We reviewed 622 published experiments on mechanical properties of porouschalk. The data include chalk samples that were tested at temperatures from [Formula: see text] with the following pore fluids: fresh water, synthetic seawater, glycol, and oil of varying viscosity. The critical frequency is calculated for each experiment. For each specimen, we calculate the thickness to the slipping plane outside the Stern layer on the pore surface. For electrolytes, the thickness of this layer is calculated based on Debye-Hückel theory. The layer reduces the porosity available for fluid flow. We find that the Biot critical frequency based on pore scale data can be used to explain effects on the macro scale. We find that the effective yield stress and also the effective stress of failure in tension as well as in compression are log-linearly related to log reference frequency. This opens the possibility to predict yield and failure under reservoir conditions from mechanical tests made under laboratory conditions. It also opens the possibility of predicting the effects of water flooding on chalk stability.
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Portal, Angélie, Baptiste Meire, Erwan Idée i Pierre-Yann David. "How can an integrated multi-method geophysical approach optimise the groundwater management in the Chalk aquifer? Case study of the Seine fault system (France, Normandy)". E3S Web of Conferences 504 (2024): 05002. http://dx.doi.org/10.1051/e3sconf/202450405002.
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The Cretaceous chalk aquifer is a strategic water resource in the north of France, especially in Normandy where it faces increasing pressure in terms of its quality and availability. The effective and sustainable manage of this resource relies on a deep understanding of its complex geological and hydrogeological nature. However, modelling this hydrosystem has its limitations due to the spatial and qualitative heterogeneity of the data available. The integration of geophysical data using various methods and scales has improved the geological knowledge by identifying the different chalk formation and highlighting the geometry of the Seine fault system near Rouen. Geophysical analysis has revealed highly complex fault geometries in this area and clarified their impact on the chalk formations. Additionally, it has provided detailed information about the vertical heterogeneity of the chalk, both geologically and hydrogeologically. This new knowledge feeds into the existing 3-D regional geological model, especially in areas with limited data. Supporting hydrogeological modelling, this updated model has already enabled to drill new boreholes. In the future, it will contribute to a better understanding and management of groundwater resources in this region.
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Grader, Abraham, Knut Arne Birkedal, Robert Engelman, Kristoffer Birkeland i Nils-Andre Aarseth. "Integrated Physical and Digital Chalk Relative Permeability Evaluation: A Case Study". Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description 65, nr 2 (1.04.2024): 149–57. http://dx.doi.org/10.30632/pjv65n2-2024a1.
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The Valhall chalk field has produced more than 1 billion barrels of oil equivalents over the last 40 years, primarily from the homogeneous Tor Formation. The underlying Hod Formation is more heterogeneous and is less maturely developed. The extent of heterogeneity poses a challenge in the evaluation of multiphase fluid flow properties. The objective of the work was to use digital core analysis to generate early relative permeability data to leverage and compare with conventional physical steady-state relative permeability data. Accurate digital and physical description of capillary pressure and relative permeability in the high-porosity chalk is complicated by both low permeabilities and heterogeneity. The main challenge with chalk is that flow occurs in a nano-environment. Physically, the nano-environment translates to low permeability, difficult rock preparation, and extensive experimental time, especiallyfor steady-state flow experiments. Representative three-dimensional (3D) digital rocks were generated using a combination of X-ray computed tomography (CT) and focused ion beam-scanning electron microscopy (FIB-SEM) methods. The digital rocks were used to simulate two-phase flow and generate relative permeabilities and sensitivity to wettability. Physical steady-state and digital relative permeabilities on several core plugs and subsets are compared in this study, which discusses the advantages of performing both as part of the formation evaluation process. The physical and digital results compare reasonably well. The physical results provide a relative permeability anchor, and the digital results provide the leverage of early results, parametric sensitivities, and quality assurance. Hence, integration between digital and physical core analysis yields a robust understanding and input for uncertainty modeling.
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Gale, Julia F. W. "Specifying Lengths of Horizontal Wells in Fractured Reservoirs". SPE Reservoir Evaluation & Engineering 5, nr 03 (1.06.2002): 266–72. http://dx.doi.org/10.2118/78600-pa.
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Summary New methods have been developed to constrain optimal horizontal drilling distance in fractured reservoirs in which opening-mode fractures are dominant. Studies of opening-mode fractures in Austin Chalk outcrops and core reveal that open fractures are commonly clustered, with the distance between clusters ranging from approximately 1 m to more than 300 m, depending on the horizon in question. Aperture-size distributions follow power laws, and spacing-size distributions are negative logarithmic or log-normal. The aperture size at which fractures are open to fluids is variable and site-specific (0.14 to 11 mm). Scaling properties of fracture attributes were used to calculate fracture permeability and to constrain well-length fracture-permeability relationships. Fracture permeability depends on the scale of measurement; it has been determined at 9.2 darcies for 14 m of lower Austin Chalk core and 286 darcies for 300 m of upper Austin Chalk outcrop. Introduction The Upper Cretaceous Austin Chalk, which crops out in a swath across central Texas, is renowned as a horizontal play and is well documented as such.1,2 Most workers regard Austin Chalk reservoirs as being low-porosity, fractured reservoirs, although there is debate concerning the relative storage capacities of matrix vs. fractures. When drilling a horizontal well in a fractured reservoir, the usual aim is to intersect fractures that are capable of providing a conduit for fluid flow. Although many horizontal wells have been drilled in the Austin Chalk,3 there are still questions over where it is best to locate new operations and how to optimize three critical parameters: wellbore azimuth, vertical depth, and wellbore length.4 This paper focuses on the question of wellbore length, although information pertaining to azimuth and depth choices also has been obtained. The choice of wellbore length has, in the past, been guided by experience and by field rules established by the Texas Railroad Commission, whereby the length of wells is linked to the acreage allocation of proration units and the permissible producing rate.4 Although these guidelines are practical, they lack direct geological input. The aim of this contribution is to develop techniques in which well-length determination is based on direct observation of fracture systems in the Austin Chalk, in addition to the Texas Railroad Commission guidelines. The objective of the outcrop and core studies was to characterize the opening-mode fracture system. Aperture-size distribution, spacing-size distribution, and fracture fill were determined in each case, allowing characterization of the spatial architecture of large, open fractures. This approach enabled us to calculate fracture permeability for different well lengths and to constrain optimal drilling distance for horizontal wells. The relationship between opening-mode fractures and normal faults in the outcrop is documented, and the relative importance of fractures and faults to reservoir permeability is considered. The connectivity and vertical height of fractures, and their impact on permeability, are discussed. Study Areas Data are presented from two outcrop analogs: one is near Waxahachie, north central Texas (Grove Creek); the other is from McKinney Falls State Park, central Texas (McKinney Falls), and from two laterals of a horizontal core drilled by the Kinlaw Oil Corp. in Frio County, Pearsall field (Kinlaw core) (Fig. 1). This well is currently operated by BASA Resources Inc. Although this study relates to the Austin Chalk specifically, the techniques used are transferable and could be applied in other horizontal targets. Geology The Austin Chalk is variable in terms of mineralogy, texture, and stratigraphy in part because of the effect of a basement high, the San Marcos Arch,5 on the paleobathymetry of its depositional basin. The updip portions of the Chalk in the Austin and San Antonio regions are relatively shallow water deposits containing considerable quantities of benthic skeletal material. Deeper-water planktonic microfossils and nanofossils dominate the basin equivalents, although some benthic material was transported basinward in debris flows.5 Drake6 reports the updip portions of the chalk in Burleson County, Giddings field, to be less fractured than the downdip portions, with wells in the updip portions being poor producers. At McKinney Falls State Park, a pavement in the McKown formation is exposed where Onion Creek flows over the lower falls. The McKown formation is a lateral equivalent of the Austin Chalk and comprises chalk intercalated with pyroclastic deposits derived from Pilot Knob, a Cretaceous volcanic center 3 km to the southeast.7 The Grove Creek outcrop is stratigraphically at the top of the Upper Chalk, just below the overlying Ozan formation. The McKinney Falls outcrop is close to the overlying Taylor Marl. The horizontal Kinlaw core from Pearsall field is from the base of the lower Chalk in the Atco Member. Thus, stratigraphically and with respect to the basin architecture, the studied sites are disparate. It is not the intention of this paper to make definitive recommendations for drilling distance in the Austin Chalk based on so few sites, but rather to show with these examples how site-specific information may be used to this end. Data-Collection Methodology An important consideration in fracture studies is whether the fractures observed in a particular core or outcrop are representative of those fractures that occur in the subsurface and contribute to fluid flow. In the case of core studies, the main pitfalls surround the distinction of natural fractures from those induced by drilling or by the core-handling process. Kulander et al.8 provided a comprehensive guide to natural and induced fracture identification in cores, and their criteria were used here. In outcrop studies, the challenge is to distinguish those fractures that would have been formed in the subsurface, at an appropriate depth to be considered as a reservoir analog, from those fractures that developed during uplift and erosion. The fracture systems documented here are confined to those that exhibit partial or total mineral fill and that would have developed in the subsurface.
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Denimal, Sophie, Florent Barbecot, Laurent Dever, Nicolas Tribovillard i Francis Meilliez. "Tracage chimique et isotopique des eaux souterraines en relation avec les eaux de lixiviation de terrils, bassin minier du Nord-Pas-de-Calais (France)". Bulletin de la Société Géologique de France 172, nr 1 (1.01.2001): 111–20. http://dx.doi.org/10.2113/172.1.111.
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Abstract Introduction. - In the Nord-Pas-de-Calais region (northern France), the mining activity linked to the coal extraction resulted in the existence of many mine spoils. Most of the time, the choice of the mine spoil location has been made without knowing the potential contamination of the aquifers contained in the underlying formations by substances which can be solubilized and released in relation with the weathering of these mine spoils. The aim of this study is to determine the possible role of the mine spoils in the sulfate mineralization of the chalk aquifer. Previous works [Bernard, 1979; Droz, 1985] allow to consider several possible sources of sulfate in the coal basin: the dissolution of evaporitic minerals present in the Carboniferous limestones Formation which can locally contaminate per ascensum the chalk aquifer; the dissolution of gypsum contained in the Tertiary formations (Argiles de Louvil, Sables d'Ostricourt); sulfates of anthropic origin linked to the waste water discharge and/or to the agricultural practices; finally, the weathering of mine spoils which leads to the oxydation of the pyrite contained in the Carboniferous shales, and can release sulfate ions that may be transferred to the aquifer. Two sites have been selected 30 km to the south of Lille: site 1 lies directly on the Senonian-Turonian chalk while site 2 lies on the sandy-clayey Tertiary formations overlying the chalk formations (fig. 1-3). Geology and hydrogeology. - The waters have been sampled within the chalk aquifer (fig. 2). This water table forms the main resource in drinking water, currently exploited. The chalk aquifer is a free water table except where the Tertiary formations make this water table confined, as is the case for site 2. The recharge of the chalk aquifer is made by the percolation of the impluvium through the microporosity of the chalk with an infiltration velocity of 0.5 to 0.7 m per year [Vachier et al., 1979]. The chalk aquifer flow is schematically SW-NE to the Orchies basin (fig. 1). This flow is caused by the piezometric depression in the Orchies basin linked to industrial pumpage. Since the decrease of these pumpages, we can observe a rise of the chalk aquifer piezometric level evaluated to 10 m in the studied area. Material and methods. - Rock samples have been collected on the surface of the two sites and below it at site 1. Mineralogical analyses have been carried out on the bulk fraction as on the clayey fraction, the elementary analysis of total carbon and total sulphur has also been performed. Two water sampling surveys have been carried out on 19 sites. Sampling has been made from piezometers which reach the chalk aquifer and that are placed close to the mine spoils but also in a radius of 5 to 10 km around. Chemical and isotopic analyses have been made on the waters sampled at hydraulic upstream and dowstream of the mine spoils. In situ measurements have been carried out during the sampling. Piezometric levels have been taken at all the sampling sites. Results and discussion. - The carbon and sulphur contents have shown a superficial leaching of these elements on the mine spoils (fig. 9). The use of isotopic geochemistry and in particular the sulphur isotopes as tracers of the sulfate origin has permitted to identify two contribution sources at the two sites: a "mine spoil" source with a delta 34 S weakly negative (delta 34 S = -2,8 per mil, -3,9 per mil) which corresponds to the oxidation of sulfides contained by the Carboniferous shales and another source (delta 34 S = -20 per mil) corresponding to the gypsum of the "Sables d'Ostricourt" which is present only at site 2 (fig. 7, 10 & 11). This study has revealed the different behaviour of the two sites: for site 1, with a free water-table zone, the mine spoil leaching carries sulfate ions directly to the table whereas in the second site, with a confined aquifer zone, a part of the sulfate ions are reduced once exported to the table (the redox potential presents negative values; fig. 6). This bacterial reduction is made possible by the organic carbon leaching concomitant to the sulphur leaching on the mine spoils. This carbon contribution has been confirmed by the 14 C activity analysis: 14 C activity is characteristic of the chalk aquifer waters at the upstream of the mine spoil and noticeably lower downstream, this decrease can be linked to the "dead carbon" supply from the mine spoils (fig. 8). This organic carbon is involved in bacterially-mediated sulfate reduction (2CH 2 O + SO 4 (super 2-) --> 2HSO 3 (super -) + H (super +) + HS (super -) ). Conclusion. - Both studied mine spoils release sulfate ions to the Chalk aquifer, in response to the weathering and leaching of their surficial part. Using an isotope study-grounded approach, the influence of the mine spoils upon the sulfate enrichment of the water table can be distinguished from that of Cenozoic formations sometimes present between the chalk aquifer and the mine spoil basis. No other sulfate source seems to be involved in the studied area. Together with sulfate ions, the mine spoils export dissolved organic carbon. Both chemical species sustain bacterial activity (sulfate reducers) that develops where the water table is made confined by overlying, almost impervious, Cenozoic deposits. In that case, reducing conditions in the aquifer decrease the amount of sulfate ions present. Thus the simultaneous supply of sulfate and carbon by the mine spoils leads to a self-purification process where the aquifer is confined.
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Law, Kwok Cheung. "Chalk fill platform for house construction: a case study". Proceedings of the Institution of Civil Engineers - Geotechnical Engineering 164, nr 6 (grudzień 2011): 373–83. http://dx.doi.org/10.1680/geng.9.00038.
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Maycock, Keith W. "Chalk and talk versus flipped learning: A case study". Journal of Computer Assisted Learning 35, nr 1 (28.09.2018): 121–26. http://dx.doi.org/10.1111/jcal.12317.
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Dargan, P. I. "A case of lead poisoning due to snooker chalk". Archives of Disease in Childhood 83, nr 6 (1.12.2000): 519–20. http://dx.doi.org/10.1136/adc.83.6.519.
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Buijsen, Edwin. "Roodkrijttekeningen naar schilderijen van Adriaen van de Venne en hun mogelijke functie". Oud Holland - Quarterly for Dutch Art History 118, nr 3-4 (2005): 131–202. http://dx.doi.org/10.1163/187501705x00330.
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AbstractThis article presents for the first time fifteen red chalk drawings by Adriaen Pietersz. van de Venne (I589-I662) as a cohesive group (catalogue in appendix i). Not only do they share the same drawing material, but they are also characterized by a careful execution and a high degree of finish. A distinct connection with Adriaen van de Venne's painted œuvre can be established: in no fewer than nine cases (cat. nos. 4, 5, 6, 7, 8, 9, II, I2 and I4) do the representation and measurements of the red chalk drawing correspond with a painting by Van de Venne. Although no paintings could yet be found which correspond with the remaining red chalk drawings it is highly likely that they did exist because the measurements of four of them (cat. nos. I, 2, 3 and I0) are consistent with panel formats frequently used by Van de Venne. Are these red chalk drawings detailed preliminary studies for the paintings, or faithful copies made afterwards? To answer this question four of the paintings which correspond with red chalk drawings were examined with infrared reflectography (IRR) or infrared photography so as to reveal the underdrawing. Three of the examined paintings (cat. no. 4, fig. a; cat. no. 7, fig. a; cat. I2, fig. a) show roughly executed underdrawings with numerous differences from the finished paintings. On the other hand, the corresponding red chalk drawings are highly detailed and identical with the finished paintings, without any visible alterations. Therefore we may conclude that they were not meant as preliminary studies but made subsequently. In the case of the fourth examined painting (cat. 9, fig. a) the situation is more complicated because the underdrawing has a more accurate and definitive character. However, this is exceptional in Van de Venne's œuvre : IRR research into a large number of his paintings has shown that he customarily made a sketchy underdrawing which was elaborated during the painting stage. This makes it all the more likely that in general the detailed red chalk drawings had no part in the genesis of the paintings, but were made subsequently. For reproducing the finished paintings the artist may have used mechanical transfer methods such as pouncing or tracing. Only one of the red chalk drawings (cat. no. I5) can be identified as a design made especially for a print. This small drawing which shows the portrait of Van de Venne himself also occupies a special position within the group because of its subject matter and size. An inscription on the reverse led Martin Royalton-Kisch to suggest that this and all other red chalk drawings were not executed by Adriaen van de Venne but by the engraver Daniel van den Bremden (I586/I587 -in or after I650?), as designs for prints. However, the reliability of the inscription on the reverse of cat. no. I5 is doubtful and because of the representative character of the portrait it seems most likely that Van de Venne himself was the author. While the style of the red chalk drawings differs from most of the drawings which Van de Venne executed in other materials (chiefly pen and ink), as was already noticed by Royalton-Kisch, there is a connection with a large drawing on parchment dated I638 and entitled 'Elk sijn gading' (Something for everyone; fig. I4) which is also carefully executed and displays a high degree of finish. An additional argument to exclude the engraver Van den Bremden as the author of the red chalk drawings is the fact that with the exception of the aforementioned portrait (cat. no. I5) none of them ever appeared in print. If the red chalk drawings after paintings by van de Venne were not meant for prints, what function can they have had? An obvious possibility is that the artist wanted to document his works visually before they left the studio. Other seventeenth-century painters, such as members of the De Braij family, are known to have created similar studio archives. Because Van de Venne's artistic production was characterized by countless repetitions and variants of the same compositions, not only in his paintings but also in his designs for book illustrations, he will certainly have wanted to register successful inventions for the purpose of making repeated use of them. Furthermore, the red chalk drawings may have served other purposes, for example to enable prospective clients to select variants or copies of existing works. Proceeding from a function as a studio archive, there is sufficient reason for localizing the red chalk drawings in Van de Venne's studio. In view of the high quality of their craftsmanship, by far the majority appears to be authentic; in a few cases a pupil may have been recruited for copying one of his master's paintings. That more red chalk drawings must have existed than the fifteen currently known can be deduced from the survey of drawings in this material for which only written sources survive (appendix II). It is to be hoped that the discovery of as yet unknown examples will provide a deeper insight into this aspect of Van de Venne's artistic output.
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&NA;. "Chalk up another use for aspirin". Nursing 34, nr 8 (sierpień 2004): 30. http://dx.doi.org/10.1097/00152193-200408000-00030.
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Davlatova, S. "Official Words in Dictionary Diwan Lughat at-Turk by M. Kashgari and Their Relationship With the Modern Kyrgyz Language". Bulletin of Science and Practice 7, nr 4 (15.04.2021): 500–507. http://dx.doi.org/10.33619/2414-2948/65/61.
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The relevance of the research: defining the role of the modern Kyrgyz language as one of the ancient Turkic languages and defining the development process of the Kyrgyz language. Purpose of the research: to analyze the types of official words in the written monument of the XI century in the dictionary Diwan Lughat at-Turk by Mahmud Kashgari by types, to compare the facts with the modern Kyrgyz language and determine the level of their use. The object of the research is M. Kashkari’s dictionaries translated into the Kyrgyz language. The research was carried out using the historical-comparative method. The vocabulary of the dictionary has been studied in comparison with the materials of the modern Kyrgyz language. In some cases, facts from related languages were also used. As a result, the words in the M. Kashgari dictionary are divided into the following types: particles, after words, conjunctions, modal words. In addition, the level of use of official words in the dictionary of the modern Kyrgyz language was determined: words that occur in the dictionary and are used in the modern Kyrgyz language without semantic and phonetic changes: köp kök – kөpkөk, sap sarɪğ — yellow, qup–kup, çulq–chylk, ҫaq – dal, chak, üçün — for, etc.; service words used in the case of phonetic change: ҫɪm-chylk, la — yes, taky — one more, shu — chu, ärdi — so, birlän — with someone (something), yana — and so on; unused service words by their appearance in the dictionary: uș — exactly like, yama — yes, — yes, isrä — then, son, ärinç — maybe etc. Dictionary Diwan Lughat at-Turk by Mahmud Kashgari contains information about the history of the Kyrgyz language, historical lexicology, comparative study of the official words of the Turkic languages.
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Powrie, W., i T. O. L. Roberts. "Case history of a dewatering and recharge system in chalk". Géotechnique 45, nr 4 (grudzień 1995): 599–609. http://dx.doi.org/10.1680/geot.1995.45.4.599.
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Katsimpari, Chaido, Sofia Koutsoviti, Alexia Mpalanika, Eleni Kalavri, Evangelos Theotikos, Antonis Fanouriakis i Antonia Elezoglou. "Spontaneous Chalk-Stick Fracture in Ankylosing Spondylitis: A Case Report". Mediterranean Journal of Rheumatology 33, nr 3 (wrzesień 2022): 346. http://dx.doi.org/10.31138/mjr.33.3.346.
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Li, Kexin, Wei Hong, Hengwu Jiao, Guo-Dong Wang, Karl A. Rodriguez, Rochelle Buffenstein, Yang Zhao, Eviatar Nevo i Huabin Zhao. "Sympatric speciation revealed by genome-wide divergence in the blind mole rat Spalax". Proceedings of the National Academy of Sciences 112, nr 38 (4.09.2015): 11905–10. http://dx.doi.org/10.1073/pnas.1514896112.
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Sympatric speciation (SS), i.e., speciation within a freely breeding population or in contiguous populations, was first proposed by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection] and is still controversial despite theoretical support [Gavrilets S (2004) Fitness Landscapes and the Origin of Species (MPB-41)] and mounting empirical evidence. Speciation of subterranean mammals generally, including the genus Spalax, was considered hitherto allopatric, whereby new species arise primarily through geographic isolation. Here we show in Spalax a case of genome-wide divergence analysis in mammals, demonstrating that SS in continuous populations, with gene flow, encompasses multiple widespread genomic adaptive complexes, associated with the sharply divergent ecologies. The two abutting soil populations of S. galili in northern Israel habituate the ancestral Senonian chalk population and abutting derivative Plio-Pleistocene basalt population. Population divergence originated ∼0.2–0.4 Mya based on both nuclear and mitochondrial genome analyses. Population structure analysis displayed two distinctly divergent clusters of chalk and basalt populations. Natural selection has acted on 300+ genes across the genome, diverging Spalax chalk and basalt soil populations. Gene ontology enrichment analysis highlights strong but differential soil population adaptive complexes: in basalt, sensory perception, musculature, metabolism, and energetics, and in chalk, nutrition and neurogenetics are outstanding. Population differentiation of chemoreceptor genes suggests intersoil population's mate and habitat choice substantiating SS. Importantly, distinctions in protein degradation may also contribute to SS. Natural selection and natural genetic engineering [Shapiro JA (2011) Evolution: A View From the 21st Century] overrule gene flow, evolving divergent ecological adaptive complexes. Sharp ecological divergences abound in nature; therefore, SS appears to be an important mode of speciation as first envisaged by Darwin [Darwin C (1859) On the Origins of Species by Means of Natural Selection].
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Mogielnicki, Krzysztof. "Two names of white colour of a victim in Roman sacrificial rituals : the case of cretatus and calidus". Graeco-Latina Brunensia, nr 2 (2023): 139–50. http://dx.doi.org/10.5817/glb2023-2-9.
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The aim of this paper is to present a new perspective on the religious function of the Latin adjectives cretatus (whitened with chalk) and calidus (having a white spot on the forehead). The researchers of Roman religion have attributed to the former a specific role. Whitening chalk was used to cover any imperfections in the appearance of the sacrificial animal. According to them, cretatus could also have a pejorative meaning. The author of the article, however, disagrees with this view and suggests to examine more closely the context in which the adjective was used and references to the white colour of the victims. He argues for a different, positive interpretation, namely that the adjective cretatus was used to indicate the effect of a ceremonial act intended to emphasise Roman piety. In the case of the other adjective, calidus, the examination of the context in which the word appeared proves that it most likely did not serve as a technical religious term and animals with a white spot on their foreheads were not considered pars pro toto as white victims in Rome.
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Atul, Mohd, i Sourabh Lalotra. "A Study on Cement Partially Replaced with Chalk Powder and Coconut Fiber Ash with the Addition of Asbestos Fiber". International Journal for Research in Applied Science and Engineering Technology 11, nr 6 (30.06.2023): 1398–407. http://dx.doi.org/10.22214/ijraset.2023.53860.
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Abstract: Concrete can be defined as a building material that can be composed by mixing gravel or broken stone, sand, cement, and water. The mixture can be poured into any shape, size of mould, which on hardening gives a solid stone like mass, the strength of hardened solid mass can be increased by adding admixtures. The main aim of the admixtures is to enhance the properties to some extend of the desired solid mass. In common man language concrete can be defined as mixture of paste and aggregates. The partial replacement of aggregates is need for the future generation of concrete structures for the environment supportable. The depletion of the natural resources gets exhausted. We have think over the alternate replacement of the materials. In present work the cement partially replaced by Chalk Powder, Coconut Fiber Ash with the addition of Asbestos Fibres. Optimum value of strength in compression, split tensile and flexure came at 18% replacement with 0.6% addition the strength is higher than conventional concrete. The workability of mixture increases and after that there is decrease in the workability of the concrete when we increase the percentage of Chalk Powder, Coconut Fiber Ash. A series of experiment were carried out to measure the compressive strength, split tensile strength and flexural strength of the concrete. The results showed that the compressive strength, split tensile strength and flexural strength increases with the adding of the Chalk Powder, Coconut Fiber Ash with the addition of Asbestos Fibres.
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Bennett, S. Christopher. "New smallest specimen of the pterosaurPteranodonand ontogenetic niches in pterosaurs". Journal of Paleontology 92, nr 2 (19.09.2017): 254–71. http://dx.doi.org/10.1017/jpa.2017.84.
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AbstractA new juvenile specimen ofPteranodonfrom the Smoky Hill Chalk Member of the Niobrara Formation of western Kansas had an estimated wingspan in life of 1.76 m, ~45% smaller than the smallest previously known specimens, but does not differ in morphology from larger specimens. Its presence indicates that juveniles were capable of flying long distances, so it falsifies the interpretation ofPteranodonas growing rapidly to adult size under parental care before flying. Instead juveniles were precocial, growing more slowly to adult size while flying and feeding independently for several years before going to sea. Because juveniles are otherwise unknown in the Smoky Hill Chalk Member, they must have occupied different environments and ecological niches than adults; thusPteranodonexhibited ontogenetic niches. Evidence is presented that most other pterosaurs (e.g.,Rhamphorhynchus,Pterodactylus,Anhanguera) also exhibited various ontogenetic niches, which, along with their large body size, suggests that pterosaur taxonomic diversity was rather low, like that of crocodilians.
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Ponchillia, Paul E., Nancy MacKenzie, Richard G. Long, Pamela Denton-Smith, Thomas L. Hicks i Priscilla Miley. "Finding a Target with an Accessible Global Positioning System". Journal of Visual Impairment & Blindness 101, nr 8 (sierpień 2007): 479–88. http://dx.doi.org/10.1177/0145482x0710100804.
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This article presents two target-location experiments. In the first experiment, 19 participants located a 25-foot chalk circle 93% of the time with a Global Positioning System (GPS) compared to 12% of the time without it. In a single-subject follow-up experiment, the participant came within 1 foot of the target on all GPS trials. Target-location techniques are described.
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Pastore, Nicola, Claudia Cherubini i Concetta I. Giasi. "Kinematic diffusion approach to describe recharge phenomena in unsaturated fractured chalk". Journal of Hydrology and Hydromechanics 65, nr 3 (1.09.2017): 287–96. http://dx.doi.org/10.1515/johh-2017-0033.
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AbstractWhen dealing with groundwater resources, a better knowledge of the hydrological processes governing flow in the unsaturated zone would improve the assessment of the natural aquifer recharge and its vulnerability to contamination. In North West Europe groundwater from unconfined chalk aquifers constitutes a major water resource, therefore the need for a good hydrological understanding of the chalk unsaturated zone is essential, as it is the main control for aquifer recharge. In the North Paris Basin, much of the recharge must pass through a regional chalk bed that is composed of a porous matrix with embedded fractures. The case study regards the role of the thick unsaturated zone of the Cretaceous chalk aquifer in Picardy (North of France) that controls the hydraulic response to rainfall. In order to describe the flow rate that reaches the water table, the kinematic diffusion theory has been applied that treats the unsaturated water flow equation as a wave equation composed of diffusive and gravitational components. The kinematic diffusion model has proved to be a convenient method to study groundwater recharge processes in that it was able to provide a satisfactory fitting both for rising and falling periods of water table fluctuation. It has also proved to give an answer to the question whether unsaturated flow can be described using the theory of kinematic waves. The answer to the question depends principally on the status of soil moisture. For higher values of hydraulic Peclet number (increasing saturation), the pressure wave velocities dominate and the preferential flow paths is provided by the shallow fractures in the vadose zone. With decreasing values of hydraulic Peclet number (increasing water tension), rapid wave velocities are mostly due to the diffusion of the flow wave. Diffusive phenomena are provided by matrix and fracture-matrix interaction.The use of a kinematic wave in this context constitutes a good simplified approach especially in cases when there is a lack of information concerning the hydraulic properties of the fractures/macropores close to saturation.
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Nosnikau, Vadzim, Ivan Kimeichuk, Siarhei Rabko, Oleksandr Kaidyk Kaidyk i Vasyl Khryk Khryk. "Growth and Development of Seedlings of Scots Pine and European Spruce Container Seedlings Using Various Materials to Neutralise the Substrate". Scientific Horizons 24, nr 4 (28.10.2020): 54–62. http://dx.doi.org/10.48077/scihor.24(4).2021.54-62.
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The article analyses the features of growth and development of seedlings of Scots pine and European spruce on substrates in which various materials were used to neutralise them, affecting the reaction of the environment. According to the research results, the highest germination of seeds of both woody species was established on substrates with a ratio of dolomite flour of 30% and chalk of 70%, while in the case of using pure chalk, seed germination was significantly lower. Scots pine seeds germination in the substrate ranged from 77.6% to 90.1%, and European spruce seeds – from 66.4% to 94.3%. During the cultivation of seedlings of Scots pine and European spruce container seedlings, differences in the content of mobile forms of phosphorus are noted in all variants of the experiment. However, no definite pattern was found depending on the share of participation of various types of lime material. In the substrate of seedlings of Scots pine at the end of the growing season, the content of nitrate nitrogen naturally increases from 1069.1 to 1323.6 mg/100 g of absolutely dry substrate with a decrease in the proportion of dolomite and an increase in the proportion of chalk in the lime neutralising material. Another pattern is manifested when growing seedlings of European spruce container seedlings: the lowest content of nitrate nitrogen (412.1 mg/100 g of absolutely dry substrate) is established in the case of mixing dolomite flour and chalk in equal proportions (option 3). Differences in the content of mobile forms of iron were revealed in all experimental versions of the substrate of both woody species. For the cultivation of Scots pine, its amount ranges from 16.67 to 28.81 mg/100 g of absolutely dry substrate, and European spruce – from 18.40 to 20.99 mg/100 g of absolutely dry substrate. In general, low content of mobile iron was observed in the substrate of growing pine and spruce seedlings in containers. In all experimental variants, the height of seedlings of Scots pine container seedlings exceeds the required average height of the aboveground part in accordance with national standard by 1.3-2.0 times, and for seedlings of European spruce the excess was 1.2-1.5 times. In seedlings of Scots pine and European spruce, according to the variants of the experiment, the average height of the aboveground part rises with an increase in the concentration of dolomite in the mixture of neutralising material from 50% and higher
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Mehta, Maulin, Sandeep Adwal i Ashutosh Chourishi. "Evaluation of different teaching-learning methods according to students’ preference and perception". International Journal of Basic & Clinical Pharmacology 6, nr 1 (24.12.2016): 76. http://dx.doi.org/10.18203/2319-2003.ijbcp20164755.
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Background: Improved teaching methodology is prerequisite for education systems so that students learn effectively. The present study was done with the objectives of evaluation of different teaching-learning methods according to students’ preference and perception.Methods: It was observational, non-interventional questionnaire based study. Total 100 students were selected randomly from second MBBS as participants of it. They filled questionnaires with 11 questions, by selecting appropriate options.Results: All students were interested in Pharmacology. Cardio-Vascular System and autocoids were the most interesting topics according to 40% of students. Total 53% of students preferred combination of chalk and board with PowerPoint presentation for understanding, while chalk and board alone (65%) as more interactive teaching method. Total 80% of students preferred interactive lecture session. Clinical case/bed side study was preferred by 89% of students. Total 40% of students preferred combination of teachers’ note and standard textbooks as reading materials. Total 80% of students mentioned that revision at the end of lecture is necessary. One and half year as ideal time to learn second MBBS, has been selected by 60% of students. Teaching with more clinical orientation is one of the changes suggested by 28% of students.Conclusions: Combination of traditional chalk and board method with modern powerpoint method, wherever necessary, is ideal for interactive and understandable lecture session. Integration/correlation of clinical cases with clinical Pharmacology will be more helpful in understanding and learning. Proper and effective management of time is essential for maximum utilization of MBBS duration with optimum output for students.
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Phipps, P. J., i B. T. McGinnity. "Classification and stability assessment for chalk cuttings: the Metropolitan Line case study". Quarterly Journal of Engineering Geology and Hydrogeology 34, nr 4 (listopad 2001): 353–70. http://dx.doi.org/10.1144/qjegh.34.4.353.
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Montross-Thomas, Lori P., Emily Merryweather, Andrea N. Trejo i Emily K. Porensky. "Sidewalk Chalk Art: A Creative Way To Engage Millennials in Palliative Care". Journal of Palliative Medicine 20, nr 4 (kwiecień 2017): 314–15. http://dx.doi.org/10.1089/jpm.2016.0529.
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Corazza, M., S. Zauli, A. Pagnoni i A. Virgili. "Allergic Contact Dermatitis Caused by Metals in Blackboard Chalk: A Case Report". Acta Dermato Venereologica 92, nr 4 (2012): 436–37. http://dx.doi.org/10.2340/00015555-1296.
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Holden, Thomas M. "The First Two Decades of Neutron Scattering at the Chalk River Laboratories". Quantum Beam Science 5, nr 1 (18.01.2021): 3. http://dx.doi.org/10.3390/qubs5010003.
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The early advances in neutron scattering at the Chalk River Laboratories of Atomic Energy of Canada are recorded. From initial nuclear physics measurements at the National Research Experimental (NRX) reactor came the realization that, with the flux available and improvements in monochromator technology, direct measurements of the normal modes of vibrations of solids and the structure and dynamics of liquids would be feasible. With further flux increases at the National Research Universal (NRU) reactor, the development of the triple-axis crystal spectrometer, and the invention of the constant-Q technique, the fields of lattice dynamics and magnetism and their interpretation in terms of the long-range forces between atoms and exchange interactions between spins took a major step forward. Experiments were performed over a seven-year period on simple metals such as potassium, complex metals such as lead, transition metals, semiconductors, and alkali halides. These were analyzed in terms of the atomic forces and demonstrated the long-range nature of the forces. The first measurements of spin wave excitations, in magnetite and in the 3D metal alloy CoFe, also came in this period. The first numerical estimates of the superfluid fraction of liquid helium II came from extensive measurements of the phonon–roton and multiphonon parts of the inelastic scattering. After the first two decades, neutron experiments continued at Chalk River until the shut-down of the NRU reactor in 2018 and the disbanding of the neutron effort in 2019, seventy years after the first experiments.
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Alam, M. Monzurul, Ida Lykke Fabricius i Helle Foged Christensen. "Static and dynamic effective stress coefficient of chalk". GEOPHYSICS 77, nr 2 (marzec 2012): L1—L11. http://dx.doi.org/10.1190/geo2010-0414.1.
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Deformation of a hydrocarbon reservoir can ideally be used to estimate the effective stress acting on it. The effective stress in the subsurface is the difference between the stress due to the weight of the sediment and a fraction (effective stress coefficient) of the pore pressure. The effective stress coefficient is thus relevant for studying reservoir deformation and for evaluating 4D seismic for the correct pore pressure prediction. The static effective stress coefficient [Formula: see text] is estimated from mechanical tests and is highly relevant for effective stress prediction because it is directly related to mechanical strain in the elastic stress regime. The corresponding dynamic effective stress coefficient [Formula: see text] is easy to estimate from density and velocity of acoustic (elastic) waves. We studied [Formula: see text] and [Formula: see text] of chalk from the reservoir zone of the Valhall field, North Sea, and found that [Formula: see text] and [Formula: see text] vary with differential stress (overburden stress-pore pressure). For Valhall reservoir chalk with 40% porosity, [Formula: see text] ranges between 0.98 and 0.85 and decreases by 10% if the differential stress is increased by 25 MPa. In contrast, for chalk with 15% porosity from the same reservoir, [Formula: see text] ranges between 0.85 and 0.70 and decreases by 5% due to a similar increase in differential stress. Our data indicate that [Formula: see text] measured from sonic velocity data falls in the same range as for [Formula: see text], and that [Formula: see text] is always below unity. Stress-dependent behavior of [Formula: see text] is similar (decrease with increasing differential stress) to that of [Formula: see text] during elastic deformation caused by pore pressure buildup, for example, during waterflooding. By contrast, during the increase in differential stress, as in the case of pore pressure depletion due to production, [Formula: see text] increases with stress while [Formula: see text] decreases.
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Tuvikene, Tauri, i Aleksandra Ianchenko. "Olematud trammiteed linnamaastikus: atmosfäärialased kunstiprojektid Turus ja Tallinnas". Mäetagused 84 (grudzień 2022): 37–52. http://dx.doi.org/10.7592/mt2022.84.tuvikene_ianchenko.
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The article brings together public transport, art, landscape, and atmosphere. The article aims to demonstrate landscape thinking, a way to attend to the multi-faceted nature of landscape, using two artistic interventions in the urban landscape as case studies: Invisible Tramline in Tallinn and Tram Chalk Walk in Turku, created by one of the co-authors of the paper (researcher and artist Aleksandra Ianchenko). Here, we look at atmosphere as a concept that can be used to bring the material and the sensory aspects of landscape together. In both artworks, atmosphere emerged in the metaphorical (re)creation of infrastructure through material interventions: in one case, the tram was made to appear as tracks skied in the snow, in the other as chalk lines. Lasnamäe tram is a case of planned but unfinished tramline whereas Turku had an active tram service for almost a century before it was discontinued in 1972. Yet, as in the case of Lasnamäe, sentiments echoing a desire to have the tram in active function are present. These artworks resonated with these sentiments although they did not have a desire to make a political statement. Instead, they artfully played with the ephemeral nature of landscape by generating atmospheres of tramlines. The article shows how atmosphere can emerge in the interaction between material aspects and being present in this environment, more specifically in the activities that metaphorically animate infrastructures in the landscape. Although the tram itself was not present in either intervention, the holistic landscape experience brought present an idea of the tram created by the interventions.