Academic literature on the topic 'Microforms Use studies'
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Journal articles on the topic "Microforms Use studies"
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Graham, Jake D., Nancy F. Glenn, Lucas P. Spaete, and Paul J. Hanson. "Characterizing Peatland Microtopography Using Gradient and Microform-Based Approaches." Ecosystems 23, no. 7 (February 10, 2020): 1464–80. http://dx.doi.org/10.1007/s10021-020-00481-z.
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AbstractPeatlands represent an important component of the global carbon cycle, storing 180–621 Gt of carbon (C). Small-scale spatial variations in elevation, frequently referred to as microtopography, influence ecological processes associated with the peatland C cycle, including Sphagnum photosynthesis and methane flux. Microtopography can be characterized with measures of topographic variability and by using conceptual classes (microforms) linked to function: most commonly hummocks and hollows. However, the criteria used to define these conceptual classes are often poorly described, if at all, and vary between studies. Such inconsistencies compel development of explicit quantitative methods to classify microforms. Furthermore, gradient-based characterizations that describe spatial variability without the use of microforms are lacking in the literature. Therefore, the objectives of this study were to (1) calculate peatland microtopographical elevation gradients and measures of spatial variability, (2) develop three microform classification methods intended for specific purposes, and (3) evaluate and contrast classification methods. Our results suggest that at spatial scales much larger than microforms, elevation distributions are unimodal and are well approximated with parametric probability density functions. Results from classifications were variable between methods and years and exhibited significant differences in mean hollow areal coverages of a raised ombrotrophic bog. Our results suggest that the conceptualization and classification of microforms can significantly influence microtopographic structural metrics. The three explicit methods for microform classification described here may be used and built upon for future applications.
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Gladkov, Gennadii L., Viktor M. Katolikov, and Pachom V. Belyakov. "PARAMETERS OF SEDIMENTS TRANSPORT IN RIVERS WITH A SIDE TYPE OF THE CHANNEL PROCESS." Vestnik Gosudarstvennogo universiteta morskogo i rechnogo flota imeni admirala S. O. Makarova 14, no. 4 (September 13, 2022): 493–507. http://dx.doi.org/10.21821/2309-5180-2022-14-4-493-507.
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At present, in practice, to model channel reformations in rivers with a deformable bottom, a large number of different formulas are used to calculate the flow of bottom sediments. However, the reliability of channel forecasts performed using the apparatus of mathematical modeling, in most cases, still remains quite low. The quality of channel forecasts performed when designing engineering measures to ensure navigation on rivers is determined, on the one hand, by the correct assessment of the physical nature of sediment transport in natural channel flows, and, on the other hand, by the quality of the applied numerical models. This work is devoted to the verification of the sediment transport model based on studies in hydraulic flumes, in which microforms and mesoforms of a river channel with a secondary type of channel process were simultaneously reproduced. Such problems have not been considered yet. The previous experiments were carried out with a uniform steady-state mode of water movement at one structural level of bottom sediment movement - with the movement of bottom sediments in the form of microforms (dunes) - i. e. on a flat day. The results obtained in the course of the research make it possible to obtain new data, using which it seems possible to improve the quality of modeling of sediment transport in natural channel flows. This line of research, based on the use of the methodology for calculating the discharge of channel sediments using the parameters of dunes, can objectively lead to an increase in the reliability of forecasts of channel reformations when keeping navigation on free and regulated rivers with a moving bottom.
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Danelyan, B. A., H. P. Manjikian, Z. A. Adyrkhaev, S. V. Sapelkin, and A. M. Isaev. "Combined microfoam sclerotherapy and miniphlebectomy as an optimal method of treating varicose vein tributaries after endovenous laser ablation." Ambulatornaya khirurgiya = Ambulatory Surgery (Russia) 19, no. 2 (November 18, 2022): 22–28. http://dx.doi.org/10.21518/1995-1477-2022-19-2-22-28.
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Introduction. The development of phlebology and mainstreaming of ultrasonic techniques has led to the emergence of microfoam sclerotherapy, which proved itself as a more effective technique. In the world literature, there are isolated publications that say about the effectiveness and safety of the microfoam sclerotherapy combined with mini-phlebectomy, but no specific studies comparing the combination treatment for the elimination of varicose syndrome with separate use of each of the techniques are described.Aim. To increase the effectiveness of invasive treatment and to reduce the rate of complications in patients with varicose veins using a combination of microfoam sclerotherapy and mini-phlebectomy of tributaries after endovenous laser ablation.Material and methods. Simple single- center, non-randomized, retrospective study was conducted at the A.K. Eramishantsev Moscow State Hospital. It included 52 patients with varicose veins (a total of 77 lower limbs, 22 patients had bilateral disease), who had no previous invasive treatment for this disease. They underwent endovenous laser ablation of truncal vein combined with microfoam sclerotherapy and mini-phlebectomy of tributaries. Microfoam sclerotherapy was performed with 0.5–2.0% of polidocanol foam, and mini-phlebectomy per Varady technique. The patients had a postprocedural follow-up clinical examination and duplex ultrasound the day after the intervention, then at 1, 6, and 12 months.Results. Endovenous laser ablation of truncal veins was acutely successful in all cases. No cases of great saphenous vein recanalization were detected in follow-up period. In the early postprocedural period, the combined microfoam sclerotherapy and miniphlebectomy also showed 100% success rate, however redo sclerotherapy was required in 4 (5.2%) cases for new varicose tributaries developed in late postprocedural period.Conclusion. Combined microfoam sclerotherapy and mini-phlebectomy, as a method of treatment for various veins syndrome, can provide additional benefit such as reducing the volume of mini-phlebectomy and the resultant tissue damage, the varicosity recurrence rate, the number of subcutaneous hematomas and ecchymoses, the discomfort of the tumescent anesthesia, the risk of postprocedural varicose veins thrombosis and pigmentation rate.
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Musaev, F. B., and S. L. Beletskiy. "History and Prospects for the Application of X-Ray Diffraction Analysis in Seed Breeding and Seed Study." Journal of the Russian Universities. Radioelectronics 24, no. 6 (December 28, 2021): 6–15. http://dx.doi.org/10.32603/1993-8985-2021-24-6-6-15.
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Introduction. X-ray analysis has been applied for visualizing the internal structure of various objects for over 100 years. However, this method began to be used for assessing the quality of plant seeds only in the early 1980s. The main impediment was a lack of specialized instruments, particularly X-ray sources, that could provide informative images. Advancements in the field of microfocus radiography allowed significant results to be achieved, including the preparation of the National Standard GOST R 596032021 "Agricultural Seeds. Methods of digital radiography".Aim. An analytical review of Russian research studies in the field of X-ray diffraction analysis of plant seeds.Materials and methods. Key stages in the development of microfocus X-ray diffraction analysis of seeds and individual parts of plants for agricultural and other purposes are considered. The design of instruments, including digital ones, created for the implementation of the method are described.Results. In order to obtain informative X-ray diffraction images of plant seeds, which objects are generally characterized by small sizes and small density, the focal spot of the X-ray tube should not exceed several tens of microns under the voltage of not higher than several tens of kilovolts. As a system for visualizing a latent X-ray image, it is preferable to use image receivers based on a screen with a photostimulated phosphor or flat-panel solid-state X-ray detectors. These instruments have been successfully used to identify and describe the radiographic signs of a normal seed and nine main types of defects for 600 plant species.Conclusion. In comparison with the conventional contact radiography, microfocus radiography produces X-ray images of seeds with a projection magnification of the image up to several tens of times. Such images permit highly detailed visualization of the structure of seeds that differ slightly in density.
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McCarthy, J. J., and D. J. McMillan. "Application of X-Ray Optics to Energy Dispersive Spectroscopy." Microscopy and Microanalysis 4, S2 (July 1998): 178–79. http://dx.doi.org/10.1017/s1431927600021012.
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The application of x-ray optics for focusing x-rays into high intensity spots or for collimation of x-ray beams has been reported by several authors. Example applications for x-ray optics include microfluorescence, microdiffraction, tomography and lithography, and WDS. Kirkland et al. pointed out that the use of an optic, in a collimating configuration could provide enhanced detection sensitivity in wavelength dispersive spectroscopy. In these proceedings last year, Agnello et al. presented data from a new WDS device specifically designed to use a grazing incidence collimating x-ray optic that confirmed and extended the work of Kirkland.A few studies have appeared reporting the use X-ray optics in applications using EDS. Focusing x-ray optics have been used on both the excitation and detection side of EDS systems. In a series of papers, Carpenter and his collaborators describe an x-ray microprobe which uses capillary optics to provide an intense convergent beam of x-rays from a microfocus x-ray tube to excite the sample for x-ray microfluorescence studies. Wollman et al.
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Moreira Andrade, Vanessa, Thais Uenoyama Dezem, Andreia Cristina Breda de Souza, Casimiro Abreu Possante de Almeida, Luiz Francesquini Junior, and Eduardo Daruge Junior. "Three-Dimensional Radiological Methods for Age Estimation in Adults by Using the Pulp/Tooth Relation: an Integrative Review." Brazilian Journal of Forensic Sciences, Medical Law and Bioethics 10, no. 2 (February 16, 2021): 97–110. http://dx.doi.org/10.17063/bjfs10(2)y202197-110.
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Assessment of secondary dentin apposition is an observable phenomenon widely used to estimate age. An integrative review was performed by searching the keywords "computed tomography AND age estimation AND pulp tooth volume ratio" and "microfocus x-ray AND age estimation AND pulp tooth volume ratio" in the electronic platforms Embase, PubMed, Scopus and Web of Science, in July 2020. Studies included: complete articles with age estimation from human teeth by use of computed tomography or micro-computed tomography, written in English, without time restriction. Excluded studies: not written in English or not in form of an article, clinical cases, literature reviews, if did not realize age estimations or if age estimation is done in animals teeth. The search resulted in 32 different articles. With application of the above criteria only 26 were reviewed. Data collected included: reference, year, country, tooth type, number of subjects, number of teeth, age group, image type, measuring instrument/software, type of analysis, coefficient of determination, correlation coefficient with age and accuracy. These data provided a quick global comparison of various methodologies that use the pulp/tooth relation, being practical for researchers and forensic team to which method they can use accordingly to a specific case and its expected accuracy.
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Mariën, An, Elie Valcke, Nele Bleyen, Maarten Van Geet, and Martine Wevers. "The Use of μCT and ESEM in the Study of the Osmosis-Induced Water Uptake by Eurobitum Bituminized Radioactive Waste." Microscopy and Microanalysis 18, no. 5 (October 2012): 1163–80. http://dx.doi.org/10.1017/s1431927612001092.
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AbstractLaboratory water uptake tests are performed at the Belgian Nuclear Research Centre SCK•CEN to obtain insight into the hydromechanical behavior of Eurobitum bituminized radioactive waste under geological disposal conditions. Small nonradioactive and radioactive Eurobitum samples are hydrated in restricted swelling conditions (i.e., nearly constant volume conditions and constant stress conditions). Microfocus X-ray computer tomography (μCT) proves to be a very suitable technique to follow up the ingress of water in the samples. μCT analyses demonstrate that, under the studied hydration conditions, the water uptake by Eurobitum samples is a diffusion controlled process. A characterization of the partially leached samples with environmental scanning electron microscopy (ESEM) shows that the hydration of salt crystals and the subsequent dilution of the salt solution result in an increase in pore size that is limited to a few tens of μm in restricted swelling conditions. The μCT and ESEM analyses allow improvement in the understanding of water uptake by Eurobitum in restricted swelling conditions. In this article we discuss the μCT and ESEM analyses of nonradioactive Eurobitum samples that were hydrated for 2 to 4 years at a constant stress of 1, 22, 33, and 44 bar or in nearly constant volume conditions.
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Arndt, U. W. "Instrumentation in X-ray crystallography: Past, present and future." Notes and Records of the Royal Society of London 55, no. 3 (September 22, 2001): 457–72. http://dx.doi.org/10.1098/rsnr.2001.0157.
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This paper deals with the very great changes in X–ray crystallographic techniques and apparatus over a period of approximately the last 60 years. This is not a general history; it is a personal account of the developments with which I have been directly involved; it is, therefore, biased towards apparatus developments in the field of macromolecular crystallography in which I have worked during most of this period. The bias needs little excuse: many of the new techniques of X–ray crystallography were devised initially for large–molecule structure determinations which had most need of such advances in order to be feasible at all. Among them are the uses of computers in calculating electron density maps, the construction of automatic diffractometers and microdensitometers, the introduction of rotating-anode X–ray generators and of microfocus X–ray tubes, the development of electronic X–ray area detectors, the pioneering work on the use of synchrotron radiation for diffraction studies, the building of three–dimensional atomic models by computer and the complete automation of the mounting, selection and alignment of crystals on the diffractometer.
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Krause, Lennard, Regine Herbst-Irmer, George M. Sheldrick, and Dietmar Stalke. "Comparison of silver and molybdenum microfocus X-ray sources for single-crystal structure determination." Journal of Applied Crystallography 48, no. 1 (January 30, 2015): 3–10. http://dx.doi.org/10.1107/s1600576714022985.
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The quality of diffraction data obtained using silver and molybdenum microsources has been compared for six model compounds with a wide range of absorption factors. The experiments were performed on two 30 W air-cooled Incoatec IµS microfocus sources with multilayer optics mounted on a Bruker D8 goniometer with a SMART APEX II CCD detector. All data were analysed, processed and refined using standard Bruker software. The results show that Ag Kα radiation can be beneficial when heavy elements are involved. A numerical absorption correction based on the positions and indices of the crystal faces is shown to be of limited use for the highly focused microsource beams, presumably because the assumption that the crystal is completely bathed in a (top-hat profile) beam of uniform intensity is no longer valid. Fortunately the empirical corrections implemented inSADABS, although originally intended as a correction for absorption, also correct rather well for the variations in the effective volume of the crystal irradiated. In three of the cases studied (two Ag and one Mo) the finalSHELXL R1 against all data after application of empirical corrections implemented inSADABSwas below 1%. Since such corrections are designed to optimize the agreement of the intensities of equivalent reflections with different paths through the crystal but the same Bragg 2θ angles, a further correction is required for the 2θ dependence of the absorption. For this,SADABSuses the transmission factor of a spherical crystal with a user-defined value of μr(where μ is the linear absorption coefficient andris the effective radius of the crystal); the best results are obtained whenris biased towards the smallest crystal dimension. The results presented here suggest that the IUCr publication requirement that a numerical absorption correction must be applied for strongly absorbing crystals is in need of revision.
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Ditter, Alexander S., William M. Holden, Samantha K. Cary, Veronika Mocko, Matthew J. Latimer, Erik J. Nelson, Stosh A. Kozimor, and Gerald T. Seidler. "Resonant inelastic X-ray scattering using a miniature dispersive Rowland refocusing spectrometer." Journal of Synchrotron Radiation 27, no. 2 (February 20, 2020): 446–54. http://dx.doi.org/10.1107/s1600577520001022.
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X-ray absorption spectroscopy (XAS) beamlines worldwide are steadily increasing their emphasis on full photon-in/photon-out spectroscopies, such as resonant inelastic X-ray scattering (RIXS), resonant X-ray emission spectroscopy (RXES) and high energy resolution fluorescence detection XAS (HERFD-XAS). In such cases, each beamline must match the choice of emission spectrometer to the scientific mission of its users. Previous work has recently reported a miniature tender X-ray spectrometer using a dispersive Rowland refocusing (DRR) geometry that functions with high energy resolution even with a large X-ray spot size on the sample [Holden et al. (2017). Rev. Sci. Instrum. 88, 073904]. This instrument has been used in the laboratory in multiple studies of non-resonant X-ray emission spectroscopy using a conventional X-ray tube, though only for preliminary measurements at a low-intensity microfocus synchrotron beamline. This paper reports an extensive study of the performance of a miniature DRR spectrometer at an unfocused wiggler beamline, where the incident monochromatic flux allows for resonant studies which are impossible in the laboratory. The results support the broader use of the present design and also suggest that the DRR method with an unfocused beam could have important applications for materials with low radiation damage thresholds and that would not survive analysis on focused beamlines.
Books on the topic "Microforms Use studies"
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Brayford, Susan. A library use study of the Microforms Division of the Social Sciences Library of the University of Calgary Libraries. Edmonton: Faculty of Library Science, University of Alberta, 1988.
Find full textConference papers on the topic "Microforms Use studies"
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Bossi, R. H., D. A. Cross, and R. A. Mickelsen. "X-Ray Microfocus Radioscopy and Computed Tomography for Failure Analysis." In ISTFA 1996. ASM International, 1996. http://dx.doi.org/10.31399/asm.cp.istfa1996p0077.
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Abstract X-ray microfocus radioscopy and computed tomography (CT) offer detailed information on the internal assembly and material condition of objects under failure analysis investigation. Using advanced systems for the acquisition of radioscopic and CT images, failure analysis investigations are improved in technical accuracy at a reduced schedule and cost over alternative approaches. A versatile microfocus radioscopic system with CT capability has been successfully implemented as a standard tool in the Boeing Defense & Space Group Failure Analysis Laboratory. Using this tool, studies of electronic, electromechanical and composite material items have been performed. Such a system can pay for itself within two years through higher productivity of the laboratory, increased laboratory value to the company and resolution of critical problems whose worth far exceeds the value of the equipment. The microfocus X-ray source provides projection magnification images that exceed the sensitivity to fine detail that can be obtained with conventional film radiography. Radioscopy, which provides real-time images on a video monitor, allows objects to be readily manipulated and oriented for optimum x-ray evaluation, or monitored during dynamic processes to check performance. Combined with an accurate manipulating stage and data acquisition system x-ray measurements can be used for CT image reconstruction. The CT image provides a cross sectional view of the interior of an object without the interference of superposition of features found in conventional radiography. Accurate dimensional measurements and material constituent identification are possible from the CT images. By taking multiple, contiguous CT slices entire three dimensional data files can be generated of objects.
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Jaecques, Siegfried V. N., Els De Smet, Luiza Muraru, John A. Jansen, Martine Wevers, Jos Vander Sloten, and Ignace E. Naert. "Peri-Implant Bone Adaptation Under Dynamic Mechanical Stimulation: The Guinea Pig Model." In ASME 7th Biennial Conference on Engineering Systems Design and Analysis. ASMEDC, 2004. http://dx.doi.org/10.1115/esda2004-58582.
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The present work is part of a larger project to analyse adaptive bone remodelling around implants that receive controlled mechanical stimulation immediately post-operatively. Percutaneous implants in the tibiae of guinea pigs are used as an implant model [1]. For evaluation, microfocus computed tomography (μCT) can be used to complement or partially substitute conventional histology [2]. In the studied model implant system, μCT-based histomorphometry can be used as a substitute for histology in regions at a distance of more than 1000 μm from the titanium implant. Within this limitation, a significant effect of mechanical stimulation can be observed also under in vivo μCT conditions. The optimally osteogenic stimulus in the studied model should cause a strain rate amplitude of 1600 microstrain/s or less in the cortical bone at a distance of 2.3 mm from the implant centre. Future work will include a detailed study of strains in the peri-implant bone with in vivo micro CT-based finite element models.