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Bursztyn, Henrique, Francesco Noseda i Chenchang Zhu. "Principal Actions of Stacky Lie Groupoids". International Mathematics Research Notices 2020, nr 16 (5.07.2018): 5055–125. http://dx.doi.org/10.1093/imrn/rny142.
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Abstract Stacky Lie groupoids are generalizations of Lie groupoids in which the “space of arrows” of the groupoid is a differentiable stack. In this paper, we consider actions of stacky Lie groupoids on differentiable stacks and their associated quotients. We provide a characterization of principal actions of stacky Lie groupoids, that is, actions whose quotients are again differentiable stacks in such a way that the projection onto the quotient is a principal bundle. As an application, we extend the notion of Morita equivalence of Lie groupoids to the realm of stacky Lie groupoids, providing examples that naturally arise from non-integrable Lie algebroids.
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Crainic, Marius, i João Nuno Mestre. "Measures on differentiable stacks". Journal of Noncommutative Geometry 13, nr 4 (20.01.2020): 1235–94. http://dx.doi.org/10.4171/jncg/362.
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Behrend, Kai, i Ping Xu. "Differentiable stacks and gerbes". Journal of Symplectic Geometry 9, nr 3 (2011): 285–341. http://dx.doi.org/10.4310/jsg.2011.v9.n3.a2.
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Barbosa-Torres, Luis Alejandro, i Frank Neumann. "Equivariant cohomology for differentiable stacks". Journal of Geometry and Physics 160 (luty 2021): 103974. http://dx.doi.org/10.1016/j.geomphys.2020.103974.
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Cabrera, Alejandro, Matias del Hoyo i Enrique Pujals. "Discrete dynamics and differentiable stacks". Revista Matemática Iberoamericana 36, nr 7 (3.04.2020): 2121–46. http://dx.doi.org/10.4171/rmi/1194.
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del Hoyo, Matias, i Rui Loja Fernandes. "Riemannian metrics on differentiable stacks". Mathematische Zeitschrift 292, nr 1-2 (25.10.2018): 103–32. http://dx.doi.org/10.1007/s00209-018-2154-6.
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TU, J., P. XU i C. LAURENTGENGOUX. "Twisted K-theory of differentiable stacks". Annales Scientifiques de l’École Normale Supérieure 37, nr 6 (listopad 2004): 841–910. http://dx.doi.org/10.1016/j.ansens.2004.10.002.
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Trentinaglia, Giorgio, i Chenchang Zhu. "Strictification of étale stacky Lie groups". Compositio Mathematica 148, nr 3 (30.11.2011): 807–34. http://dx.doi.org/10.1112/s0010437x11007020.
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AbstractWe define stacky Lie groups to be group objects in the 2-category of differentiable stacks. We show that every connected and étale stacky Lie group is equivalent to a crossed module of the form (Γ,G) where Γ is the fundamental group of the given stacky Lie group and G is the connected and simply connected Lie group integrating the Lie algebra of the stacky group. Our result is closely related to a strictification result of Baez and Lauda.
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Behrend, Kai, i Ping Xu. "S1-bundles and gerbes over differentiable stacks". Comptes Rendus Mathematique 336, nr 2 (styczeń 2003): 163–68. http://dx.doi.org/10.1016/s1631-073x(02)00025-0.
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Rouse, Paulo Carrillo, i Bai-Ling. "Geometric Baum-Connes assembly map for twisted Differentiable Stacks". Annales scientifiques de l'École normale supérieure 49, nr 2 (2016): 277–323. http://dx.doi.org/10.24033/asens.2283.
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Kim, Junghee, Siyeong Lee i Suk-Ju Kang. "End-to-End Differentiable Learning to HDR Image Synthesis for Multi-exposure Images". Proceedings of the AAAI Conference on Artificial Intelligence 35, nr 2 (18.05.2021): 1780–88. http://dx.doi.org/10.1609/aaai.v35i2.16272.
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Recently, high dynamic range (HDR) image reconstruction based on the multiple exposure stack from a given single exposure utilizes a deep learning framework to generate high-quality HDR images. These conventional networks focus on the exposure transfer task to reconstruct the multi-exposure stack. Therefore, they often fail to fuse the multi-exposure stack into a perceptually pleasant HDR image as the inversion artifacts occur. We tackle the problem in stack reconstruction-based methods by proposing a novel framework with a fully differentiable high dynamic range imaging (HDRI) process. By explicitly using the loss, which compares the network's output with the ground truth HDR image, our framework enables a neural network that generates the multiple exposure stack for HDRI to train stably. In other words, our differentiable HDR synthesis layer helps the deep neural network to train to create multi-exposure stacks while reflecting the precise correlations between multi-exposure images in the HDRI process. In addition, our network uses the image decomposition and the recursive process to facilitate the exposure transfer task and to adaptively respond to recursion frequency. The experimental results show that the proposed network outperforms the state-of-the-art quantitative and qualitative results in terms of both the exposure transfer tasks and the whole HDRI process.
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del Hoyo, Matias, i Cristian Ortiz. "Morita Equivalences of Vector Bundles". International Mathematics Research Notices 2020, nr 14 (26.06.2018): 4395–432. http://dx.doi.org/10.1093/imrn/rny149.
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Abstract We study vector bundles over Lie groupoids, known as VB-groupoids, and their induced geometric objects over differentiable stacks. We establish a fundamental theorem that characterizes VB-Morita maps in terms of fiber and basic data, and use it to prove the Morita invariance of VB-cohomology, with implications to deformation cohomology of Lie groupoids and of classic geometries. We discuss applications of our theory to Poisson geometry, providing a new insight over Marsden–Weinstein reduction and the integration of Dirac structures. We conclude by proving that the derived category of VB-groupoids is a Morita invariant, which leads to a notion of VB-stacks, and solves (an instance of) an open question on representations up to homotopy.
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Diamond, Steven, Vincent Sitzmann, Frank Julca-Aguilar, Stephen Boyd, Gordon Wetzstein i Felix Heide. "Dirty Pixels: Towards End-to-end Image Processing and Perception". ACM Transactions on Graphics 40, nr 3 (6.05.2021): 1–15. http://dx.doi.org/10.1145/3446918.
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Real-world, imaging systems acquire measurements that are degraded by noise, optical aberrations, and other imperfections that make image processing for human viewing and higher-level perception tasks challenging. Conventional cameras address this problem by compartmentalizing imaging from high-level task processing. As such, conventional imaging involves processing the RAW sensor measurements in a sequential pipeline of steps, such as demosaicking, denoising, deblurring, tone-mapping, and compression. This pipeline is optimized to obtain a visually pleasing image. High-level processing, however, involves steps such as feature extraction, classification, tracking, and fusion. While this silo-ed design approach allows for efficient development, it also dictates compartmentalized performance metrics without knowledge of the higher-level task of the camera system. For example, today’s demosaicking and denoising algorithms are designed using perceptual image quality metrics but not with domain-specific tasks such as object detection in mind. We propose an end-to-end differentiable architecture that jointly performs demosaicking, denoising, deblurring, tone-mapping, and classification (see Figure 1). The architecture does not require any intermediate losses based on perceived image quality and learns processing pipelines whose outputs differ from those of existing ISPs optimized for perceptual quality, preserving fine detail at the cost of increased noise and artifacts. We show that state-of-the-art ISPs discard information that is essential in corner cases, such as extremely low-light conditions, where conventional imaging and perception stacks fail. We demonstrate on captured and simulated data that our model substantially improves perception in low light and other challenging conditions, which is imperative for real-world applications such as autonomous driving, robotics, and surveillance. Finally, we found that the proposed model also achieves state-of-the-art accuracy when optimized for image reconstruction in low-light conditions, validating the architecture itself as a potentially useful drop-in network for reconstruction and analysis tasks beyond the applications demonstrated in this work. Our proposed models, datasets, and calibration data are available at https://github.com/princeton-computational-imaging/DirtyPixels .
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Ventura Matos, Rita, Filipa Ferreira i José Saldanha Matos. "Influence of Intermittence and Pressure Differentials in Hydrogen Sulfide Concentration in a Gravity Sewer". Water 11, nr 9 (27.08.2019): 1780. http://dx.doi.org/10.3390/w11091780.
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The work presented herein was carried out to assess the effect of intermittent pumping events in sewer headspace pressure differentials, as well as their relationship with hydrogen sulfide gas concentration. A full scale gravity sewer in Portugal, located downstream of several pumping stations, was used as the guiding case study. Under normal system operation, pressure difference between the outside atmosphere and the sewer headspace seemed to influence the in and out-gassing of gas pollutants emitted through the venting stack. Wastewater pumping cycles generated maximum pressure differentials of roughly 100 Pa, which in turn originated maximum air velocities of 1.76 m s−1 exiting the venting stack. Each pumping event was followed by a pressure drop of about 50 Pa, quickly attaining null concentrations of H2S at the venting stack. A statistically significant relationship between pressure differentials and air exit velocity was observed, which allowed obtaining an empirical equation for expedite prediction of airflows emitted to the outside atmosphere (R2 = 0.77). Conversely, the same effect was not observed along the length of the sewer pipe, unlike the findings of other studies. The effect of a full flowing pipe at the downstream end of the gravity trunk sewer was also noticeable in downstream sewer pressurization and gas build-up. It was concluded that the magnitude of the gas pollutant emissions may heavily depend on the impacts of hydraulic flows and pumping characteristics in headspace pressure differences, denoting the need for better approaches when designing and installing venting stacks.
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Wang, Jili, Weidong Yu, Yunkai Deng, Robert Wang, Yingjie Wang, Heng Zhang i Mingjie Zheng. "Demonstration of Time-Series InSAR Processing in Beijing Using a Small Stack of Gaofen-3 Differential Interferograms". Journal of Sensors 2019 (8.04.2019): 1–13. http://dx.doi.org/10.1155/2019/4204580.
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More and more synthetic aperture radar (SAR) satellites in orbit provide abundant data for remote sensing applications. In August 2016, China launched a new Earth observation SAR satellite, Gaofen-3 (GF-3). In this paper, we utilize a small stack of GF-3 differential interferograms to map land subsidence in Beijing (China) using the time-series SAR interferometry (InSAR) technique. The small stack of differential interferograms is generated with 5 GF-3 SAR images from March 2017 to January 2018. Orbit errors are carefully addressed and removed during differential InSAR (DInSAR) processing. Truncated singular-value decomposition (TSVD) is applied to strengthen the robustness of deformation rate estimation. To validate the results of GF-3 data, an additional deformation measurement using 26 Sentinel-1B images from March 2017 to February 2018 is carried out using the persistent scatterer interferometry (PSI) technique. By implementing a cross-comparison, we find that the retrieved results from GF-3 images and Sentinel-1 images are spatially consistent. The standard deviation of vertical deformation rate differences between two data stacks is 11.24 mm/y in the study area. The results shown in this paper demonstrate the reasonable potential of GF-3 SAR images to monitor land subsidence.
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Bulnes, Francisco. "Cycles Cohomology and Geometrical Correspondences of Derived Categories to Field Equations". JOURNAL OF ADVANCES IN MATHEMATICS 14, nr 2 (30.08.2018): 7880–92. http://dx.doi.org/10.24297/jam.v14i2.7581.
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The integral geometry methods are the techniques could be the more naturally applied to study of the characterization of the moduli stacks and solution classes (represented cohomologically) obtained under the study of the kernels of the differential operators of the corresponding field theory equations to the space-time. Then through a functorial process a classification of differential operators is obtained through of the co-cycles spaces that are generalized Verma modules to the space-time, characterizing the solutions of the field equations. This extension can be given by a global Langlands correspondence between the Hecke sheaves category on an adequate moduli stack and the holomorphic bundles category with a special connection (Deligne connection). Using the classification theorem given by geometrical Langlands correspondences are given various examples on the information that the geometrical invariants and dualities give through moduli problems and Lie groups acting.
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Wang, Ziyun, Timo Balz, Lu Zhang, Daniele Perissin i Mingsheng Liao. "Using TSX/TDX Pursuit Monostatic SAR Stacks for PS-InSAR Analysis in Urban Areas". Remote Sensing 11, nr 1 (24.12.2018): 26. http://dx.doi.org/10.3390/rs11010026.
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Persistent Scatterer Interferometry (PS-InSAR) has become an indispensable tool for monitoring surface motion in urban environments. The interferometric configuration of PS-InSAR tends to mix topographic and deformation components in differential interferometric observations. When the upcoming constellation missions such as, e.g., TanDEM-L or TWIN-L provide new standard operating modes, bi-static stacks for deformation monitoring will be more commonly available in the near future. In this paper, we present an analysis of the applicability of such data sets for urban monitoring, using a stack of pursuit monostatic data obtained during the scientific testing phase of the TanDEM-X (TDX) mission. These stacks are characterized by extremely short temporal baselines between the TerraSAR-X (TSX) and TanDEM-X acquisitions at the same interval. We evaluate the advantages of this acquisition mode for urban deformation monitoring with several of the available acquisition pairs. Our proposed method exploits the special properties of this data using a modified processing chain based on the standard PS-InSAR deformation monitoring procedure. We test our approach with a TSX/TDX mono-static pursuit stack over Guangzhou, using both the proposed method and the standard deformation monitoring procedure, and compare the two results. The performance of topographic and deformation estimation is improved by using the proposed processing method, especially regarding high-rise buildings, given the quantitative statistic on temporal coherence, detectable numbers, as well as the PS point density of persistent scatters points, among which the persistent scatter numbers increased by 107.2% and the detectable height span increased by 78% over the standard processing results.
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Le, G. T., L. Mastropasqua, J. Brouwer i S. B. Adler. "Simulation-Informed Machine Learning Diagnostics of Solid Oxide Fuel Cell Stack with Electrochemical Impedance Spectroscopy". Journal of The Electrochemical Society 169, nr 3 (1.03.2022): 034530. http://dx.doi.org/10.1149/1945-7111/ac59f4.
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This paper reports our initial development of simulation-informed machine learning algorithms for failure diagnostics in solid oxide fuel cell (SOFC) systems. We used physics-based models to simulate electrochemical impedance spectroscopy (EIS) response of a short SOFC stack under normal conditions and under three different failure modes: fuel maldistribution, delamination, and oxidant gas crossover to the anode channel. These data were used to train a support vector machine (SVM) model, which is able to detect and differentiate these failures in simulated data under various conditions. The SVM model can also distinguish these failures from simulated uniform degradation that often occurs with long-term operation. These encouraging results are guiding our ongoing efforts to apply EIS as a failure diagnostic for real SOFC cells and short stacks.
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Pao, Yi-Hsin, i Ellen Eisele. "Interfacial Shear and Peel Stresses in Multilayered Thin Stacks Subjected to Uniform Thermal Loading". Journal of Electronic Packaging 113, nr 2 (1.06.1991): 164–72. http://dx.doi.org/10.1115/1.2905382.
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An analytical approach has been developed to evaluate the interfacial shear and peel stresses in multilayered thin stacks subjected to uniform temperature variation. The approach, which is based on an extension of Suhir’s bimetal thermostat model, provides a system of coupled linear second order differential equations used in solving for the interfacial stresses. Once these stresses have been determined, the normal stress in each layer and the deflection of the stack can be readily obtained. Two numerical examples are used to demonstrate the capability of the approach. The first example deals with a five-layered symmetric double-shear solder joint. The results are compared to a nonsymmetric three-layered solder joint to study the effect of bending and the interactions of material properties. One of the interesting features observed is that the maximum interfacial shear stress does not necessarily occur at the edge. The other numerical example is a four-layered transistor stack mounted on a substrate. The structural behavior is analyzed, and the effect of geometric dimension is examined. The present approach is shown to provide more accurate results than those of others based on the same assumptions. In addition, applications of the approach to more general stack configurations are also discussed.
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FIORENZA, DOMENICO, CHRISTOPHER L. ROGERS i URS SCHREIBER. "A HIGHER CHERN–WEIL DERIVATION OF AKSZ σ-MODELS". International Journal of Geometric Methods in Modern Physics 10, nr 01 (15.11.2012): 1250078. http://dx.doi.org/10.1142/s0219887812500788.
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Chern–Weil theory provides for each invariant polynomial on a Lie algebra 𝔤 a map from 𝔤-connections to differential cocycles whose volume holonomy is the corresponding Chern–Simons theory action functional. Kotov and Strobl have observed that this naturally generalizes from Lie algebras to dg-manifolds and to dg-bundles and that the Chern–Simons action functional associated this way to an n-symplectic manifold is the action functional of the AKSZ σ-model whose target space is the given n-symplectic manifold (examples of this are the Poisson σ-model or the Courant σ-model, including ordinary Chern–Simons theory, or higher-dimensional Abelian Chern–Simons theory). Here we show how, within the framework of the higher Chern–Weil theory in smooth ∞-groupoids, this result can be naturally recovered and enhanced to a morphism of higher stacks, the same way as ordinary Chern–Simons theory is enhanced to a morphism from the stack of principal G-bundles with connections to the 3-stack of line 3-bundles with connections.
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Nikolić, Dragan D. "Parallelisation of equation-based simulation programs on heterogeneous computing systems". PeerJ Computer Science 4 (13.08.2018): e160. http://dx.doi.org/10.7717/peerj-cs.160.
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Numerical solutions of equation-based simulations require computationally intensive tasks such as evaluation of model equations, linear algebra operations and solution of systems of linear equations. The focus in this work is on parallel evaluation of model equations on shared memory systems such as general purpose processors (multi-core CPUs and manycore devices), streaming processors (Graphics Processing Units and Field Programmable Gate Arrays) and heterogeneous systems. The current approaches for evaluation of model equations are reviewed and their capabilities and shortcomings analysed. Since stream computing differs from traditional computing in that the system processes a sequential stream of elements, equations must be transformed into a data structure suitable for both types. The postfix notation expression stacks are recognised as a platform and programming language independent method to describe, store in computer memory and evaluate general systems of differential and algebraic equations of any size. Each mathematical operation and its operands are described by a specially designed data structure, and every equation is transformed into an array of these structures (a Compute Stack). Compute Stacks are evaluated by a stack machine using a Last In First Out queue. The stack machine is implemented in the DAE Tools modelling software in the C99 language using two Application Programming Interface (APIs)/frameworks for parallelism. The Open Multi-Processing (OpenMP) API is used for parallelisation on general purpose processors, and the Open Computing Language (OpenCL) framework is used for parallelisation on streaming processors and heterogeneous systems. The performance of the sequential Compute Stack approach is compared to the direct C++ implementation and to the previous approach that uses evaluation trees. The new approach is 45% slower than the C++ implementation and more than five times faster than the previous one. The OpenMP and OpenCL implementations are tested on three medium-scale models using a multi-core CPU, a discrete GPU, an integrated GPU and heterogeneous computing setups. Execution times are compared and analysed and the advantages of the OpenCL implementation running on a discrete GPU and heterogeneous systems are discussed. It is found that the evaluation of model equations using the parallel OpenCL implementation running on a discrete GPU is up to twelve times faster than the sequential version while the overall simulation speed-up gained is more than three times.
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Grady, Daniel, i Hisham Sati. "Massey products in differential cohomology via stacks". Journal of Homotopy and Related Structures 13, nr 1 (27.05.2017): 169–223. http://dx.doi.org/10.1007/s40062-017-0178-y.
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Weinstein, Alan. "The Volume of a Differentiable Stack". Letters in Mathematical Physics 90, nr 1-3 (22.09.2009): 353–71. http://dx.doi.org/10.1007/s11005-009-0343-2.
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Kim, Youngkyu, Jeongmin Oh, Seung-Ho Choi, Ahra Jung, June-Goo Lee, Yoon Se Lee i Jun Ki Kim. "A Portable Smartphone-Based Laryngoscope System for High-Speed Vocal Cord Imaging of Patients With Throat Disorders: Instrument Validation Study". JMIR mHealth and uHealth 9, nr 6 (18.06.2021): e25816. http://dx.doi.org/10.2196/25816.
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Background Currently, high-speed digital imaging (HSDI), especially endoscopic HSDI, is routinely used for the diagnosis of vocal cord disorders. However, endoscopic HSDI devices are usually large and costly, which limits access to patients in underdeveloped countries and in regions with inadequate medical infrastructure. Modern smartphones have sufficient functionality to process the complex calculations that are required for processing high-resolution images and videos with a high frame rate. Recently, several attempts have been made to integrate medical endoscopes with smartphones to make them more accessible to people in underdeveloped countries. Objective This study aims to develop a smartphone adaptor for endoscopes, which enables smartphone-based vocal cord imaging, to demonstrate the feasibility of performing high-speed vocal cord imaging via the high-speed imaging functions of a high-performance smartphone camera, and to determine the acceptability of the smartphone-based high-speed vocal cord imaging system for clinical applications in developing countries. Methods A customized smartphone adaptor optical relay was designed for clinical endoscopy using selective laser melting–based 3D printing. A standard laryngoscope was attached to the smartphone adaptor to acquire high-speed vocal cord endoscopic images. Only existing basic functions of the smartphone camera were used for HSDI of the vocal cords. Extracted still frames were observed for qualitative glottal volume and shape. For image processing, segmented glottal and vocal cord areas were calculated from whole HSDI frames to characterize the amplitude of the vibrations on each side of the glottis, including the frequency, edge length, glottal areas, base cord, and lateral phase differences over the acquisition time. The device was incorporated into a preclinical videokymography diagnosis routine to compare functionality. Results Smartphone-based HSDI with the smartphone-endoscope adaptor could achieve 940 frames per second and a resolution of 1280 by 720 frames, which corresponds to the detection of 3 to 8 frames per vocal cycle at double the spatial resolution of existing devices. The device was used to image the vocal cords of 4 volunteers: 1 healthy individual and 3 patients with vocal cord paralysis, chronic laryngitis, or vocal cord polyps. The resultant image stacks were sufficient for most diagnostic purposes. The cost of the device including the smartphone was lower than that of existing HSDI devices. The image processing and analytics demonstrated the successful calculation of relevant diagnostic variables from the acquired images. Patients with vocal pathologies were easily differentiable in the quantitative data. Conclusions A smartphone-based HSDI endoscope system can function as a point-of-care clinical diagnostic device. The resulting analysis is of higher quality than that accessible by videostroboscopy and promises comparable quality and greater accessibility than HSDI. In particular, this system is suitable for use as an accessible diagnostic tool in underdeveloped areas with inadequate medical service infrastructure.
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Jakoby, Rolf, Alexander Gaebler i Christian Weickhmann. "Microwave Liquid Crystal Enabling Technology for Electronically Steerable Antennas in SATCOM and 5G Millimeter-Wave Systems". Crystals 10, nr 6 (16.06.2020): 514. http://dx.doi.org/10.3390/cryst10060514.
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Future satellite platforms and 5G millimeter wave systems require Electronically Steerable Antennas (ESAs), which can be enabled by Microwave Liquid Crystal (MLC) technology. This paper reviews some fundamentals and the progress of microwave LCs concerning its performance metric, and it also reviews the MLC technology to deploy phase shifters in different topologies, starting from well-known toward innovative concepts with the newest results. Two of these phase shifter topologies are dedicated for implementation in array antennas: (1) wideband, high-performance metallic waveguide phase shifters to plug into a waveguide horn array for a relay satellite in geostationary orbit to track low Earth orbit satellites with maximum phase change rates of 5.1°/s to 45.4°/s, depending on the applied voltages, and (2) low-profile planar delay-line phase shifter stacks with very thin integrated MLC varactors for fast tuning, which are assembled into a multi-stack, flat-panel, beam-steering phased array, being able to scan the beam from −60° to +60° in about 10 ms. The loaded-line phase shifters have an insertion loss of about 3 dB at 30 GHz for a 400° differential phase shift and a figure-of-merit (FoM) > 120°/dB over a bandwidth of about 2.5 GHz. The critical switch-off response time to change the orientation of the microwave LCs from parallel to perpendicular with respect to the RF field (worst case), which corresponds to the time for 90 to 10% decay in the differential phase shift, is in the range of 30 ms for a LC layer height of about 4 µm. These MLC phase shifter stacks are fabricated in a standard Liquid Crystal Display (LCD) process for manufacturing low-cost large-scale ESAs, featuring single- and multiple-beam steering with very low power consumption, high linearity, and high power-handling capability. With a modular concept and hybrid analog/digital architecture, these smart antennas are flexible in size to meet the specific requirements for operating in satellite ground and user terminals, but also in 5G mm-wave systems.
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Kim, Myong-Hwan, Youngmo Goo i Seung Eul Yoo. "A Study on Performance According to Differential Pressure of 1kW PEMFC Stack for Fuel Cell Vehicles". ECS Meeting Abstracts MA2018-01, nr 32 (13.04.2018): 1977. http://dx.doi.org/10.1149/ma2018-01/32/1977.
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In this study, HDP(High Differential Pressure) and LDP(Low Differential Pressure) bipolar plates which had difference from inner pressure was designed for analyzing the correlation about differential pressure and performance of stack. The increase of inner pressure different was shown by increasing of flow rate according to current density about 1kW class stack using the designed bipolar plates and the inner pressure of stack was lower than unit cell. The anode inner pressure of HDP stack was 1.0, 1.4 and 1.7 kPa on SR(Stoichiometric Rate) 1.5, 2.0 and 2.5, respectively. Also, cathode side appeared to 9.0, 11.8 and 14.9 kPa on SR 2.0, 2.5 and 3.0 at 1,000mA/cm2. The LDP stack was shown as inner pressure of sextuple compared with HDP stack. The performance of 1kW class HDP stack and LDP stack was 0.585 V and 0.593 V on average voltage of each cell at atmosphere pressure, anode SR 1.5, cathode SR 2.0 and 1,000mA/cm2. These results showed that LDP stack with low inner pressure were superior to HDP stack about power consumption of BOP(Balance of Plant) like compressor and blower. However, performance of LDP stack at low current density was decreased by channel flooding. To supplementation of this phenomenon, increase of flow rate was necessary to stable operation of LDP stack.
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Behrend, Kai A. "On the de Rham cohomology of differential and algebraic stacks". Advances in Mathematics 198, nr 2 (grudzień 2005): 583–622. http://dx.doi.org/10.1016/j.aim.2005.05.025.
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Borisov, Dennis, Ludmil Katzarkov i Artan Sheshmani. "Shifted symplectic structures on derived Quot-stacks I – Differential graded manifolds –". Advances in Mathematics 403 (lipiec 2022): 108369. http://dx.doi.org/10.1016/j.aim.2022.108369.
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Akhmetov, K. M., G. S. Shaikhova, V. V. Zhurov, E. N. Khmyrova i A. R. Yarullina. "Mathematical model of coal self-heating in a stack". Kompleksnoe Ispolʹzovanie Mineralʹnogo syrʹâ/Complex Use of Mineral Resources/Mineraldik Shikisattardy Keshendi Paidalanu 318, nr 3 (12.09.2021): 90–96. http://dx.doi.org/10.31643/2021/6445.32.
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The article presents a mathematical model of coal self-heating in the stack in which the heat exchange and gas exchange processes are described by a system of two non-linear differential equations of the second order with respect to the temperature t of coal self-heating and the volume fraction C of oxygen in the voids of the stack with boundary and initial conditions. The differential equations took into account that self-heating of coal in the stack and appearance of spontaneous combustion are observed in a relatively small layer adjacent to the surface of its contact with the air and called the zone of oxygen influence. In the mathematical model, the influence on the process of coal self-heating of parameter F- specific heat release power was taken into account, which in addition characterises the stability of coal during storage. When compiling the differential equations, such physical parameters as thermal conductivity, diffusion coefficient, specific heat capacity of coal in the stack, bulk density, thermal effect of oxidation, stack voidness, temperature coefficient of exponential growth of heat release power were also used. For numerical implementation of the mathematical model, dimensionless variables and criteria were introduced, which allowed us to apply the net method. Analysis of the obtained results allowed to get: change in the stack temperature profiles with time; change in the stack oxygen concentration profiles with time; influence on the stack temperature profile of the specific heat release power; influence on the stack temperature profile of the parameter characterizing exponential growth of heat release intensity with temperature increase. It has been determined that the dynamics of coal self-heating in the stack is mostly influenced by the Lykov criterion, proportional to the diffusion coefficient, and the Nusselt criterion related to the effective thermal conductivity and to the effective thermal diffusivity of coal. The obtained results suggest that self-heating in the stack is due on the one hand to intensive penetration of air oxygen and on the other hand to a weakened heat transfer. Self-heating and the transition of self-heating into ignition are associated with the occurrence of turbulent diffusion in the stack, arising from increased thermal blowing, whose impact can be enhanced by directing it perpendicular to the surface of the stack.
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Jayaraman, C. P., J. A. Kirk, D. K. Anand i M. Anjanappa. "Rotor Dynamics of Flywheel Energy Storage Systems". Journal of Solar Energy Engineering 113, nr 1 (1.02.1991): 11–18. http://dx.doi.org/10.1115/1.2929944.
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This paper deals with the dynamic analysis of the magnetic bearing stack system. The stack consists of a single flywheel supported by two magnetic bearings. To model the system, the dynamic equations of a magnetically suspended flywheel are derived. Next, the four control systems controlling the four degrees-of-freedom of the stack are incorporated into the model. The resulting dynamic equations are represented as first-order differential equations in a matrix form. A computer simulation program was then used to simulate the working of the magnetic bearing stack. Real time plots from the simulation are used to show the effect of dynamic coupling on torque response. Frequency response is used to determine the resonance frequencies of the stack system. It is found that system stability depends on flywheel speed. On the basis of the above results suggestions are made to improve stability and allow the stack to be spun beyond 60,000 rpm.
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Zhou, Jinlong, Linghua Dong i Weidong Yang. "A Double-Acting Piezoelectric Actuator for Helicopter Active Rotor". Actuators 10, nr 10 (24.09.2021): 247. http://dx.doi.org/10.3390/act10100247.
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An active rotor with trailing-edge flaps is an effective approach to alleviate vibrations and noise in helicopters. In this study, a compact piezoelectric actuator is proposed to drive trailing-edge flaps. The two groups of piezoelectric stacks accommodated in the actuator operate in opposition, and double-acting output can be realized through the differential motion of these stacks. A theoretical model and a finite element model are established to predict the output capability of this actuator, and structural optimization is performed using the finite element model. A prototype is built and tested on a benchtop to assess its performance. Test results demonstrate that the actuator stiffness reaches 801 N/mm, and its output stroke is up to ±0.27 mm when subjected to actuation voltage of 120 V. Agreement between measurements and simulations validates the accuracy of the established models. In addition, actuator outputs in failure modes are measured by canceling the supply voltage of one group of piezoelectric stacks. In this condition, the actuator can still generate acceptable outputs, and the initial position of the output end remains unchanged. Simulations and test results reveal that the proposed actuator achieves promising performance, and it is capable to be applied to a helicopter active rotor.
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Fan, Zhen, Tianming Chen, Guolin Cai, Xiaoyu Huang, Suchuan Zhong, Xiaoming Li i Enping Zhang. "Effect of Aspergillus niger Fermentation on the Metabolites in Corn Stalks". Fermentation 9, nr 1 (7.01.2023): 50. http://dx.doi.org/10.3390/fermentation9010050.
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Fermentation has been considered as an effective means to improve the feed nutrient digestibility of corn stalks, and it is beneficial to animal growth performance and health. The beneficial functions of fermented corn stalks are related to the variety of metabolites produced through fermentation, but the nature of these components is still unclear. In this study, gas chromatography–mass spectrometry, combined with principal component analysis and partial least squares discriminant analysis, was used to explore the differential metabolites of corn stalks before and after Aspergillus niger fermentation. A total of 32 potential characteristic compounds were obtained, mainly including sugar and glycoside derivatives, organic acids and their derivatives, alcohol compounds, benzene and its substituted derivatives, amino acids, phenolic compounds, and flavonoids. Compared with the metabolites in corn straw before fermentation, the relative content of D-threitol, mannitol-1-phosphate, coniferin, citrazinic, oxoglutaric acid, chenodeoxycholic acid, naproxen, 5-aminovaleric acid, vanillin, catechin, and UDP-glucuronic acid was significantly increased, and the relative content of N-acetylgalactosamine, heneicosanoic acid, chlorogenic acid, and adenosine was significantly decreased. Kyoto Encyclopedia of Genes and Genomes pathway analysis showed that 20 metabolic pathways corresponded to the differential characteristic metabolites. The results of this study will provide theoretical support for the quality evaluation of fermented corn stalks and high-value product development in the future.
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Villa, A., P. Podini, D. O. Clegg, T. Pozzan i J. Meldolesi. "Intracellular Ca2+ stores in chicken Purkinje neurons: differential distribution of the low affinity-high capacity Ca2+ binding protein, calsequestrin, of Ca2+ ATPase and of the ER lumenal protein, Bip." Journal of Cell Biology 113, nr 4 (15.05.1991): 779–91. http://dx.doi.org/10.1083/jcb.113.4.779.
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To identify intracellular Ca2+ stores, we have mapped (by cryosection immunofluorescence and immunogold labeling) the distribution in the chicken cerebellar cortex of an essential component, the main low affinity-high capacity Ca2+ binding protein which in this tissue has been recently shown undistinguishable from muscle calsequestrin (Volpe, P., B. H. Alderson-Lang, L. Madeddu, E. Damiani, J. H. Collins, and A. Margreth. 1990. Neuron. 5:713-721). Appreciable levels of the protein were found exclusively within Purkinje neurons, distributed to the cell body, the axon, and the elaborate dendritic tree, with little labeling, however, of dendritic spines. At the EM level the protein displayed a dual localization: within the ER (rough- and smooth-surfaced cisternae, including the cisternal stacks recently shown [in the rat] to be highly enriched in receptors for inositol 1,4,5-triphosphate) and, over 10-fold more concentrated, within a population of moderately dense, membrane-bound small vacuoles and tubules, identified as calciosomes. These latter structures were widely distributed both in the cell body (approximately 1% of the cross-sectional area, particularly concentrated near the Golgi complex) and in the dendrites, up to the entrance of the spines. The distribution of calsequestrin was compared to those of another putative component of the Ca2+ stores, the membrane pump Ca2+ ATPase, and of the ER resident lumenal protein, Bip. Ca2+ ATPase was expressed by both calciosomes and regular ER cisternae, but excluded from cisternal stacks; Bip was abundant within the ER lumena (cisternae and stacks) and very low within calciosomes (average calsequestrin/Bip immunolabeling ratios were approximately 0.5 and 36.5 in the two types of structure, respectively). These results suggest that ER cisternal stacks do not represent independent Ca2+ stores, but operate coordinately with the adjacent, lumenally continuous ER cisternae. The ER and calciosomes could serve as rapidly exchanging Ca2+ stores, characterized however by different properties, in particular, by the greater Ca2+ accumulation potential of calciosomes. Hypotheses of calciosome biogenesis (directly from the ER or via the Golgi complex) are discussed.
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IN 'T PANHUIS, P. H. M. W., S. W. RIENSTRA, J. MOLENAAR i J. J. M. SLOT. "Weakly nonlinear thermoacoustics for stacks with slowly varying pore cross-sections". Journal of Fluid Mechanics 618 (10.01.2009): 41–70. http://dx.doi.org/10.1017/s0022112008004291.
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A general theory of thermoacoustics is derived for arbitrary stack pores. Previous theoretical treatments of porous media are extended by considering arbitrarily shaped pores with the only restriction that the pore cross-sections vary slowly in the longitudinal direction. No boundary-layer approximation is necessary. Furthermore, the model allows temperature variations in the pore wall. By means of a systematic approach based on dimensional analysis and small parameter asymptotics, we derive a set of ordinary differential equations for the mean temperature and the acoustic pressure and velocity, where the equation for the mean temperature follows as a consistency condition of the assumed asymptotic expansion. The problem of determining the transverse variation is reduced to finding a Green's function for a modified Helmholtz equation and solving two additional integral equations. Similarly the derivation of streaming is reduced to finding a single Green's function for the Poisson equation on the desired geometry.
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Lequette, Yannick, i E. P. Greenberg. "Timing and Localization of Rhamnolipid Synthesis Gene Expression in Pseudomonas aeruginosa Biofilms". Journal of Bacteriology 187, nr 1 (1.01.2005): 37–44. http://dx.doi.org/10.1128/jb.187.1.37-44.2005.
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ABSTRACT Pseudomonas aeruginosa biofilms can develop mushroom-like structures with stalks and caps consisting of discrete subpopulations of cells. Self-produced rhamnolipid surfactants have been shown to be important in development of the mushroom-like structures. The quorum-sensing-controlled rhlAB operon is required for rhamnolipid synthesis. We have introduced an rhlA-gfp fusion into a neutral site in the P. aeruginosa genome to study rhlAB promoter activity in rhamnolipid-producing biofilms. Expression of the rhlA-gfp fusion in biofilms requires the quorum-sensing signal butanoyl-homoserine lactone, but other factors are also required for expression. Early in biofilm development rhlA-gfp expression is low, even in the presence of added butanoyl-homoserine lactone. Expression of the fusion becomes apparent after microcolonies with a depth of >20 μm have formed and, as shown by differential labeling with rfp or fluorescent dyes, rhlA-gfp is preferentially expressed in the stalks rather than the caps of mature mushrooms. The rhlA-gfp expression pattern is not greatly influenced by addition of butanoyl-homoserine lactone to the biofilm growth medium. We propose that rhamnolipid synthesis occurs in biofilms after stalks have formed but prior to capping in the mushroom-like structures. The differential expression of rhlAB may play a role in the development of normal biofilm architecture.
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Zhou, Qian, Dié Tang, Wu Huang, Zhongmin Yang, Yu Zhang, John P. Hamilton, Richard G. F. Visser i in. "Haplotype-resolved genome analyses of a heterozygous diploid potato". Nature Genetics 52, nr 10 (28.09.2020): 1018–23. http://dx.doi.org/10.1038/s41588-020-0699-x.
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Abstract Potato (Solanum tuberosum L.) is the most important tuber crop worldwide. Efforts are underway to transform the crop from a clonally propagated tetraploid into a seed-propagated, inbred-line-based hybrid, but this process requires a better understanding of potato genome. Here, we report the 1.67-Gb haplotype-resolved assembly of a diploid potato, RH89-039-16, using a combination of multiple sequencing strategies, including circular consensus sequencing. Comparison of the two haplotypes revealed ~2.1% intragenomic diversity, including 22,134 predicted deleterious mutations in 10,642 annotated genes. In 20,583 pairs of allelic genes, 16.6% and 30.8% exhibited differential expression and methylation between alleles, respectively. Deleterious mutations and differentially expressed alleles were dispersed throughout both haplotypes, complicating strategies to eradicate deleterious alleles or stack beneficial alleles via meiotic recombination. This study offers a holistic view of the genome organization of a clonally propagated diploid species and provides insights into technological evolution in resolving complex genomes.
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Na, Mi, Cai Fu, Zhang Yushu, Ji Ruipeng, Zhang Shujie i Wang Yang. "Differential responses of maize yield to drought at vegetative and reproductive stages". Plant, Soil and Environment 64, No. 6 (31.05.2018): 260–67. http://dx.doi.org/10.17221/141/2018-pse.
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Determining the effects of progressive drought (PD) on dry matter production, partitioning, and grain yield of maize will help in designing a suitable strategy for water management. Though influences of drought on maize growth and development have been investigated extensively, few of them focused on the effects of different duration and occurrence stage of PD on yield formation of maize. Six variations of PD, in the form of withholding irrigation for varying lengths of time from jointing or tasselling, were tested in the field, using a mobile rain shelter, in terms of their effects on aboveground biomass accumulation, partitioning, and grain yield in 2015–2016. The results showed that grain yield was significantly reduced by PD during either vegetative or reproductive stage, and the reduction in grain yield from reproductive PD (41.6–46.6%) was greater than that from vegetative PD (18.6–26.2%). The decrease in grain yield was largely caused by the decrease in kernels per ear (r<sup>2</sup> = 0.88, P < 0.001). This research implied that guaranteeing water supply for maize during reproductive stage is crucially important to avoid the reduction in kernels per ear and grain yield.
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Vishwesh, J., i P. Raviraj. "Improved Differential Evolution with Stacked Auto Encoder for EEG Motor Imagery Classification". Indian Journal Of Science And Technology 16, nr 6 (12.02.2023): 391–400. http://dx.doi.org/10.17485/ijst/v16i6.2076.
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Hancke, Ragnhild, Piotr Bujlo, Thomas Holm i Øystein Ulleberg. "High-Pressure PEMWE Stack and System Characterization". ECS Meeting Abstracts MA2022-01, nr 39 (7.07.2022): 1748. http://dx.doi.org/10.1149/ma2022-01391748mtgabs.
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As the urgency to decarbonize the industry and transport sector intensifies, renewable energy-based hydrogen production via advanced low temperature water electrolysis is attracting increased interest. Proton exchange membrane water electrolysers (PEMWE) offer several benefits over the more mature alkaline water electrolysis technology, including its load-following capability and the ability to operate at higher pressures. The latter is important because significant benefits can be harvested by adopting systems operating at pressure-levels compatible with the end use applications and thereby render the mechanical compressor redundant. At IFE we have developed a methodology which encompasses detailed energy- and techno-economic calculations of high-pressure systems, and a comparison between high-pressure electrolysis and state-of-the-art electrolysis at 30 bar in combination with a compressor has been carried out. Here, direct pressurization to 80 and 200 bar (relevant for, e.g., methanol and ammonia production) was found to be economically viable. To realize high-pressure H2 generation systems, many challenges related to system operability, efficiency and safety needs to be addressed. As part of the national infrastructure “The Norwegian Fuel Cell and Hydrogen Centre”, Institute for Energy Technology (IFE) has installed a flexible PEM water electrolyzer system platform for testing of small-scale prototype electrolyzers up to 33 kW and 200 bar differential pressure. The test rig is integrated with a sophisticated power conditioning system which consists of three custom-built DC/DC-converters (for PEMWE, PEMFC, and Li-ion battery systems), all coupled to the same DC-bus. This configuration makes it possible to test different hybrid electric topologies and to emulate different loads (e.g., grid load profiles, wind generation). This one-of-a-kind high-pressure PEMWE test facility at IFE is well suited to study performances of next-generation PEMWE stacks and systems, and to tailor and test control strategies that safeguards the system and maximizes efficiency and durability The test rig has been commissioned with a prototype high-pressure stack with a production capacity of 2 Nm3/h (Nel Hydrogen), and the identified economically viable pressure range of 80-200 bar has been the main target for an experimental test campaign. The experimental results are presented from stack testing including polarization curves and EIS data as a function of temperature, pressure and current density. The results are discussed in relation to the techno-economic model, in order to identify pathways towards more efficient hydrogen production. Figure 1
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Schiff, H. I. "1995 Fisher Scientific Award Lecture Reflections of an atmospheric chemist wondering why he won an analytical chemistry award". Canadian Journal of Chemistry 74, nr 10 (1.10.1996): 1765–73. http://dx.doi.org/10.1139/v96-196.
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The author recalls his scientific career starting with electrochemistry and gas phase kinetics and leading, largely by serendipity, to atmospheric chemistry and measurements in the atmosphere using rockets and stratospheric balloons. The scientific problems met along the way required measurements with instruments that were not commercially available and required development of new methods and techniques. These included mass spectrometry, chemiluminescence, and tunable Diode Laser Absorption Spectrometry (TDLAS) to measure trace concentrations of gases in the lower and upper atmosphere. TDLAS is considered to be the method of choice where freedom from interferences, high sensitivity, and fast time response are required. Lead salt laser diodes operate in the near infrared where most molecules of atmospheric interest have strong fundamental absorptions. The research groups at York University and at Unisearch Associates have been pioneers in applying this powerful technique to atmospheric measurements in a variety of environments including the pristine air over the Pacific, at the top of Mauna Loa, at the Grand Canyon, and the polluted air of Los Angeles and other major cities. The results of recent measurements of the emissions of two strong greenhouse gases, CF4 and C2F6, from Quebec aluminium refineries are described. More recently a family of instruments based on near-infrared laser diodes have been developed that can make remote-sensing measurements of a number of pollutants in ambient air and industrial stacks. Examples of passive, on-road, remote-sensing measurements of automobile exhaust emissions of CO and CO2, and of in-stack emissions of HF are presented. Another remote-sensing instrument that has been developed is an improved visible and UV Differential Optical Absorption Spectrometer (DOAS) capable of measuring, remotely and simultaneously, a number of important pollutants. Examples of measurements of NO, NO2, O3, benzene, and toluene are presented. Key words: air measurements, instruments, remote sensing.
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Beraldo, Dario. "Sheaves of categories with local actions of Hochschild cochains". Compositio Mathematica 155, nr 08 (4.07.2019): 1521–67. http://dx.doi.org/10.1112/s0010437x19007413.
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The notion of Hochschild cochains induces an assignment from $\mathsf{Aff}$ , affine DG schemes, to monoidal DG categories. We show that this assignment extends, under appropriate finiteness conditions, to a functor $\mathbb{H}:\mathsf{Aff}\rightarrow \mathsf{Alg}^{\text{bimod}}(\mathsf{DGCat})$ , where the latter denotes the category of monoidal DG categories and bimodules. Any functor $\mathbb{A}:\mathsf{Aff}\rightarrow \mathsf{Alg}^{\text{bimod}}(\mathsf{DGCat})$ gives rise, by taking modules, to a theory of sheaves of categories $\mathsf{ShvCat}^{\mathbb{A}}$ . In this paper, we study $\mathsf{ShvCat}^{\mathbb{H}}$ . Loosely speaking, this theory categorifies the theory of $\mathfrak{D}$ -modules, in the same way as Gaitsgory’s original $\mathsf{ShvCat}$ categorifies the theory of quasi-coherent sheaves. We develop the functoriality of $\mathsf{ShvCat}^{\mathbb{H}}$ , its descent properties and the notion of $\mathbb{H}$ -affineness. We then prove the $\mathbb{H}$ -affineness of algebraic stacks: for ${\mathcal{Y}}$ a stack satisfying some mild conditions, the $\infty$ -category $\mathsf{ShvCat}^{\mathbb{H}}({\mathcal{Y}})$ is equivalent to the $\infty$ -category of modules for $\mathbb{H}({\mathcal{Y}})$ , the monoidal DG category of higher differential operators. The main consequence, for ${\mathcal{Y}}$ quasi-smooth, is the following: if ${\mathcal{C}}$ is a DG category acted on by $\mathbb{H}({\mathcal{Y}})$ , then ${\mathcal{C}}$ admits a theory of singular support in $\operatorname{Sing}({\mathcal{Y}})$ , where $\operatorname{Sing}({\mathcal{Y}})$ is the space of singularities of ${\mathcal{Y}}$ . As an application to the geometric Langlands programme, we indicate how derived Satake yields an action of $\mathbb{H}(\operatorname{LS}_{{\check{G}}})$ on $\mathfrak{D}(\operatorname{Bun}_{G})$ , thereby equipping objects of $\mathfrak{D}(\operatorname{Bun}_{G})$ with singular support in $\operatorname{Sing}(\operatorname{LS}_{{\check{G}}})$ .
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Patrascu, Monica, Tudor Baracu, Viorel Badescu, Marius-Victor Birsan, Catalin Teodosiu, Mircea Degeratu, Elena Rita Avram, Mihnea Udrea, Lidia Calancea i Calin Mesteru. "Modeling air leakage in buildings caused by the cyclic variation of the atmospheric pressure". Building Services Engineering Research and Technology 39, nr 4 (23.01.2018): 430–62. http://dx.doi.org/10.1177/0143624417749536.
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This article considers a new type of air infiltration through building envelopes caused by the barometric pressure variation. This process is independent from wind action or stack effect. A new building–atmosphere differential equation of air exchange is established. Based on the solution of the differential equation of air exchange, we propose the notion of pressure equilibration time [Formula: see text] that characterizes the dynamic response of the building. Furthermore, experimental climatic data were processed using Fourier analysis methods in order to build an identification model based on the regular harmonics of external pressure oscillation. The barometric pressure reconstructed in its parameterized form was introduced in the differential equation of air exchange as a term that models the dynamics of the external action. The analytic solution of the differential equation of air exchange demonstrates that the indoor–outdoor pressure difference is insignificant at less than 10−3 Pa for any harmonic of the external pressure variation. At the same time, it is concluded that the airtightness of the envelope has little influence on the process, as the indoor–outdoor pressure equilibration is almost instantaneous in a continuous regime of variation. The described mechanism of air infiltration explains the alternation of infiltration and exfiltration of air in buildings. For this, a mass balance of air exchange for the specific ranges of time is performed. We prove that the barometric pressure variation has an effect that accounts for 3.19% of the total quantity of air exchanged. The advances provided by this paper constitute a useful instrument for further studies concerning the stack effect in thermal dynamic conditions. Practical application: The paper proposes a novel methodology of determining the air exchange building–environment by considering a new component of infiltration and its cyclic variation: the barometric pressure. A new mechanism of natural air infiltration is determined and modeled and it should be added to the existing ones: wind action and stack effect. A complete methodology of analysis and extraction of the cyclic processes hidden in an envelope of stochastic variations is defined and applied with the support of signal processing techniques and spectral analysis. The refinement of the mathematical instrument was able to distinguish through a deterministic approach an influence of 3.19% of the new barometric component. Furthermore, with few adaptations, the methodology constructed in this study can be applied for investigation of the stack effect by considering the cyclic variation of the atmospheric temperature. Currently, the stack effect is analyzed only for average conditions of temperature, a simplistic approach that suggests a large potential for further improvement.
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Sukarni, Sukarni, i M. Rifqi Ramadhan. "Pyrolytic Characteristics and Kinetic Parameters Evaluation of Cassava Stalks Using Thermogravimetric Analyzer". Key Engineering Materials 851 (lipiec 2020): 137–41. http://dx.doi.org/10.4028/www.scientific.net/kem.851.137.
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Pyrolytic characteristics and kinetics of cassava stalks as a renewable energy source were delved via a thermogravimetric (TG) analyzer. About 10 mg powder of the sample was heated up in the TG cavity under inert conditions with 50 ml.min-1 nitrogen flow rate and operated at 20 °C min-1 of heating program. The pyrolysis process of cassava stalks was taken place into three main stages, in which the peak reaction occurred at the second stage with 70% of the mass was degraded. The differential method of Arrhenius kinetic evaluation resulted in the values of reaction order (n) that was 0.99, activation energy that was 89.46 kJ/mol and logarithmic frequency factor (log A) was 7.7 min-1.
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Subramanian, Madhumalar, Charlotte Kielar, Satoru Tsushima, Karim Fahmy i Jana Oertel. "DNA-Mediated Stack Formation of Nanodiscs". Molecules 26, nr 6 (16.03.2021): 1647. http://dx.doi.org/10.3390/molecules26061647.
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Membrane-scaffolding proteins (MSPs) derived from apolipoprotein A-1 have become a versatile tool in generating nano-sized discoidal membrane mimetics (nanodiscs) for membrane protein research. Recent efforts have aimed at exploiting their controlled lipid protein ratio and size distribution to arrange membrane proteins in regular supramolecular structures for diffraction studies. Thereby, direct membrane protein crystallization, which has remained the limiting factor in structure determination of membrane proteins, would be circumvented. We describe here the formation of multimers of membrane-scaffolding protein MSP1D1-bounded nanodiscs using the thiol reactivity of engineered cysteines. The mutated positions N42 and K163 in MSP1D1 were chosen to support chemical modification as evidenced by fluorescent labeling with pyrene. Minimal interference with the nanodisc formation and structure was demonstrated by circular dichroism spectroscopy, differential light scattering and size exclusion chromatography. The direct disulphide bond formation of nanodiscs formed by the MSP1D1_N42C variant led to dimers and trimers with low yield. In contrast, transmission electron microscopy revealed that the attachment of oligonucleotides to the engineered cysteines of MSP1D1 allowed the growth of submicron-sized tracts of stacked nanodiscs through the hybridization of nanodisc populations carrying complementary strands and a flexible spacer.
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Majumder, Aurpan, i Mrityunjay Sarkar. "Exploring Different Stages of Alzheimer's Disease through Topological Analysis of Differentially Expressed Genetic Networks". International Journal of Computer Theory and Engineering 6, nr 5 (październik 2014): 386–91. http://dx.doi.org/10.7763/ijcte.2014.v6.895.
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Endres, H., H. J. Keller, R. Swietlik, D. Schweitzer, K. Angermund i C. Krüger. "X-Ray Investigations of the Low-Temperature Phases of the Organic Metals α- and β-(BEDT-TTF)2I3". Zeitschrift für Naturforschung A 41, nr 11 (1.11.1986): 1319–24. http://dx.doi.org/10.1515/zna-1986-1110.
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The structure of single crystals of the organic metals α- and β-(BEDT-TTF)2I3* was determined at 100 K, well below the phase transitions indicated by resistivity and thermopower measurements as well as by differential thermal analysis. In the α-phase no unusual change of the room temperature unit cell but a slight variation in the triiodide network and especially a more pronounced dimerization in one of the two donor stacks have been found. The β-phase develops a superstructure with a unit cell volume three times as large as that at room temperature and with pronounced distortions of the I3--ions.
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Celano, Umberto, Lennaert Wouters, Alexis Franquet, Valentina Spampinato, Paul van der Heide, Marc Schaekers, Abhijeet Joshi i Bulent M. Basol. "Dopant Activation Depth Profiling for Highly Doped Si:P By Scanning Spreading Resistance Microscopy (SSRM) and Differential Hall Effect Metrology (DHEM)". ECS Transactions 108, nr 5 (20.05.2022): 9–15. http://dx.doi.org/10.1149/10805.0009ecst.
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Heavily P-doped epitaxial Si layers were deposited over counter-doped Si substrates. P dopant activation was studied as a function of various processes used to prepare the samples. For electrical characterization, depth profiles of carrier concentration values were obtained using SSRM and DHEM techniques. Samples studied included an in-situ doped sample, a sample that was spike annealed at 1000ºC, a sample that was first coated with a Ti/TiN stack and then annealed for silicide formation before the Ti/TiN stack was removed, and a sample that was spike annealed + coated with Ti/TiN + annealed for silicide formation before the removal of the Ti/TiN stack. DHEM analysis showed substantial increase in dopant activation for spike annealed samples. SSRM results suggested lower carrier concentration values and more limited degree of activation. Formation of Ti/TiN contacts and its removal did not affect the carrier concentration values for the as-deposited epi layer. Sample that was first spike annealed and then subjected to contact formation process displaced a reduction in carrier concentration values as measured by DHEM.
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Cohen, Roni, Oded Yarden i Yitzhak Hadar. "Lignocellulose Affects Mn2+ Regulation of Peroxidase Transcript Levels in Solid-State Cultures of Pleurotus ostreatus". Applied and Environmental Microbiology 68, nr 6 (czerwiec 2002): 3156–58. http://dx.doi.org/10.1128/aem.68.6.3156-3158.2002.
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ABSTRACT The effect of Mn2+ amendment on peroxidase gene expression was studied during Pleurotus ostreatus growth on cotton stalks. Four peroxidase-encoding genes were expressed differentially and in a manner different from that observed in defined media. Mn2+ affects mnp3 expression even 2 h after its addition to the cultures, suggesting a direct effect of the metal ion on expression.
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Pawar, Priya, Deying Zhang, Xiaoying Wu i Werner Lang. "Thermal performance of a non–segmented and segmented tall atrium in hot and humid climate". Journal of Physics: Conference Series 2042, nr 1 (1.11.2021): 012162. http://dx.doi.org/10.1088/1742-6596/2042/1/012162.
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Abstract The study was designed to quantify the thermal conditions in tall atria in office buildings to serve as a starting point towards understanding their performance. The simulation study of a non-segmented and segmented atrium of 250 m height reveals indoor air temperature, wind velocity contours and wind pressure coefficients at various heights of each atrium type. In a hot and humid climate like that of Singapore, the internal temperatures within each atrium stack remain constant at 27°C. However, the wind velocity in the non-segmented atrium (of 0.5 - 0.7 m/s) is lower than acceptable (0.9 m/s) for human occupancy. Adding segments and a larger inlet to the atrium solves the problem of low wind velocity without increasing the effective ambient temperature within the atrium stack. Additionally, the segmented atrium offers the advantage of displaying lower buoyancy forces by lowering the pressure differential within a tall stack thereby providing better comfort conditions.
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Varizhuk, A. M., A. V. Sekridova, M. V. Tankevich, V. S. Podgorsky, I. P. Smirnov i G. E. Pozmogova. "Conformational polymorphysm of G-rich fragments of DNA Alu-repeats. II. the putative role of G-quadruplex structures in genomic rearrangements". Biomeditsinskaya Khimiya 62, nr 6 (2016): 630–37. http://dx.doi.org/10.18097/pbmc20166206630.
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Three evolutionary conserved sites of Alu repeats (PQS2, PQS3 and PQS4) were shown to form stable inter- and intramolecular G-quadruplexes (GQs) in vitro. Structures and topologies of these GQs were elucidated using spectral methods. Self-association of G-rich Alu fragments was studied. Dimeric GQ formation from two distal identical or different putative quadruplex sites – (PQS2)2, (PQS3)2 or PQS2-PQS3 – within one lengthy DNA strand was demonstrated by a FRET-based method. Oligomer PQS4 (folded into a parallel intramolecular GQ) was shown to form stacks of quadruplexes that are stabilized by stacking interactions of external G-tetrads (this was confirmed by DOSY NMR, AFM microscopy and differential CD spectroscopy). Comparative analysis of the properties of various GQs allowed us to put forward a hypothesis of two general mechanisms of intermolecular GQ-dependant genomic rearrangements: 1) formation of a dimeric GQs; 2) association of pre-folded intramolecular parallel GQs from different strands into GQ-stacks. Thus, the observed co-localization of G-rich motifs of Alu elements with double-strand break hotspots and rearrangement hotspots may be accounted for by the specific secondary structure of these motifs. At the same time, this is likely primarily due to high abundance of such G-rich Alu fragments in the genome.