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Park, Kyu-Won, Juman Kim, Jisung Seo, Songky Moon e Kabgyun Jeong. "Indicators of wavefunction (de)localisation for avoided crossing in a quadrupole quantum billiard". Journal of Physics Communications 5, n. 11 (1 novembre 2021): 115009. http://dx.doi.org/10.1088/2399-6528/ac34a3.
Testo completoAbstract (sommario):
Abstract The relationship between wavefunction (de)localisation and avoided crossing in a quadrupole billiard is analysed. The following three-types of measures are employed for wavefunction (de)localisation: inverse participation ratio, inverse of Rényi entropy, and root-mean-square (RMS) image contrast. All these measures exhibit minimal values at the centre of the avoided crossing, where the wavefunction is maximally delocalised. Our results indicate that these quantities can be sufficient for the indication of wavefunction (de)localisation.
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Baydoun, Ibrahim. "Localisation Inverse Problem of Absorbing Laplacian Transport". Journal of Modern Physics 04, n. 05 (2013): 572–78. http://dx.doi.org/10.4236/jmp.2013.45080.
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Vogeleer, Svetlana. "Quand inverse". Revue québécoise de linguistique 26, n. 1 (30 aprile 2009): 79–101. http://dx.doi.org/10.7202/603145ar.
Testo completoAbstract (sommario):
RÉSUMÉL’objectif de l’étude est d’établir les conditions sémantiques, discursives et pragmatiques qui favorisent ou, au contraire, empêchent l’interprétation dite « inverse » de la subordonnée temporelle postposée introduite parquandoulorsque. Les phrases à subordonnée temporelle postposée qui permettent une interprétation « inverse » sont soumises au traitement à l’aide du concept de point de vue. Ce traitement vise à mettre en évidence le rapport entre la localisation spatio-temporelle du sujet de conscience (porteur du point de vue) et la possibilité de l’interprétation « inverse » de la subordonnée, ainsi qu’à éclaircir les causes sémantiques, discursives et pragmatiques des deux effets de sens les plus saillants de l’interprétation « inverse » : l’effet de surprise (l’événement décrit dans la subordonnée est ressenti comme inattendu) et l’effet d’interruption (l’événement décrit dans la subordonnée semble interrompre l’action décrite dans la principale).
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Velísková, Yvetta, Marek Sokáč e Maryam Barati Moghaddam. "Inverse task of pollution spreading – Localization of source in extensive open channel network structure". Journal of Hydrology and Hydromechanics 71, n. 4 (14 novembre 2023): 475–85. http://dx.doi.org/10.2478/johh-2023-0029.
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Abstract This paper is focused on the problem of the pollutant source localisation in streams in other words the solution of the inverse problem of pollution spreading with in an extensive open channel network structure, i.e. in a complex system of rivers, channels and creeks in natural catchments or sewer systems in urban catchments. The design of the overall localisation procedure is based on the requirement that the entire localization system be operative and fast enough to enable quick operative interventions and help prevent the spread of pollution. The proposed model, as well as, the overall localisation procedure was calibrated and tested on a real sewer system, which represents in this case an extensive open channel network structure with free surface flow. The test results are successful and confirmed applicability of proposed localization tool in simple real conditions. However, the localisation procedure has pros and cons, which are discussed in the paper.
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Spencer, Troy A., Rodney A. Walker e Richard M. Hawkes. "Inverse Diffraction Parabolic Wave Equation Localisation System (IDPELS)". Journal of Global Positioning Systems 4, n. 1&2 (31 dicembre 2005): 245–57. http://dx.doi.org/10.5081/jgps.4.1.245.
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Carboni, Margherita, Denis Brunet, Martin Seeber, Christoph M. Michel, Serge Vulliemoz e Bernd J. Vorderwülbecke. "Linear distributed inverse solutions for interictal EEG source localisation". Clinical Neurophysiology 133 (gennaio 2022): 58–67. http://dx.doi.org/10.1016/j.clinph.2021.10.008.
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Bonin-Font, F., A. Burguera, A. Ortiz e G. Oliver. "Concurrent visual navigation and localisation using inverse perspective transformation". Electronics Letters 48, n. 5 (2012): 264. http://dx.doi.org/10.1049/el.2011.3577.
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Anderssen, R. S., B. G. Osborne e I. J. Wesley. "The Application of Localisation to near Infrared Calibration and Prediction through Partial Least Squares Regression". Journal of Near Infrared Spectroscopy 11, n. 1 (febbraio 2003): 39–48. http://dx.doi.org/10.1255/jnirs.352.
Testo completoAbstract (sommario):
Near infrared (NIR) calibration and prediction represents a strategy for solving the inverse problem of determining the input sample property from its output NIR spectrum. The spectrum is an indirect measurement of the property that has been smoothed, leading to a loss of information. As a result, small changes in the spectra can, on occasions, correspond to large changes in the property. However, the well-established mathematical theory of regularisation has been developed for the solution of indirect measurement and inverse problems. Regularisation seeks an approximation to the input that simultaneously forces the model output to agree closely with the observed output and guarantees that appropriate constraints about the behaviour of the input are satisfied. In partial least squares regression, this is achieved through the simultaneous fitting of a model to the measured spectra and another to the property data, with the models coupled through the same set of regression factors. It is this idea that must be carried over to localisation in order to transform it into a stabilised algorithm. In other words, localisation should be carried out with respect to both the spectrum and the property. This paper presents a theoretical basis for this concept together with the results of simulation experiments that compares the effects of localisation with respect to both the spectra and the property with spectrum only and property only localisation.
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De Meutter, Pieter, Ian Hoffman e Andy W. Delcloo. "A baseline for source localisation using the inverse modelling tool FREAR". Journal of Environmental Radioactivity 273 (marzo 2024): 107372. http://dx.doi.org/10.1016/j.jenvrad.2024.107372.
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Pérez, R., V. Puig, J. Pascual, A. Peralta, E. Landeros e Ll Jordanas. "Pressure sensor distribution for leak detection in Barcelona water distribution network". Water Supply 9, n. 6 (1 dicembre 2009): 715–21. http://dx.doi.org/10.2166/ws.2009.372.
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This paper proposes a leakage detection method based on detecting significant discrepancies between pressure measurements and their estimations obtained from the simulation of a calibrated water distribution network model. Every sensor in the network will allow to detect a discrepancy in pressure due to leakage depending on its location. Then, a set of well distributed pressure sensors will generate a leakage signature that allows leakage localisation. This paper presents the methodology used in the Barcelona network for distributing properly the sensors for a good discrimination in the leakage localisation process. The methodology for sensor placement uses the pressure sensitivity matrix to the leakage presence. This matrix is normalised and binarised in order to be used as a leakage signature matrix using the standard model based fault diagnosis approach. Sensors may be installed in any node and leakages are simulated as a constant demand that can appear in any node too. The problem of deciding which are the best localisations for a small number of sensors in order to detect and localise leakages is an inverse problem that should be solved using optimisation. The resulting optimisation problem is of discrete nature and very huge for a real network. This type of problem is, in general, hard to solve and very time consuming. The use of GA (Genetic Algorithms) has been proved adequate according to the formulation of the signatures in the sensitivity matrix.
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Baydoun, Ibrahim. "Localisation Inverse Problem and Dirichlet-to-Neumann Operator for Absorbing Laplacian Transport". Journal of Modern Physics 04, n. 06 (2013): 772–79. http://dx.doi.org/10.4236/jmp.2013.46106.
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Partridge, P. W., e L. C. Wrobel. "An inverse geometry problem for the localisation of skin tumours by thermal analysis". Engineering Analysis with Boundary Elements 31, n. 10 (ottobre 2007): 803–11. http://dx.doi.org/10.1016/j.enganabound.2007.02.002.
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Phillips, Christophe, Michael D. Rugg e K. J. Friston. "Systematic noise regularisation for linear inverse solution of the source localisation problem in EEG". NeuroImage 13, n. 6 (giugno 2001): 220. http://dx.doi.org/10.1016/s1053-8119(01)91563-0.
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Dell’Aversano, Angela, Giovanni Leone e Raffaele Solimene. "Comparing Two Approaches for Point-Like Scatterer Detection". International Journal of Antennas and Propagation 2015 (2015): 1–10. http://dx.doi.org/10.1155/2015/139235.
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Many inverse scattering problems concern the detection and localisation of point-like scatterers which are sparsely enclosed within a prescribed investigation domain. Therefore, it looks like a good option to tackle the problem by applying reconstruction methods that are properly tailored for such a type of scatterers or that naturally enforce sparsity in the reconstructions. Accordingly, in this paper we compare the time reversal-MUSIC and the compressed sensing. The study develops through numerical examples and focuses on the role of noise in data and mutual coupling between the scatterers.
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Magnani, Ivana, Chiara Novielli, Laura Fontana, Silvia Tabano, Davide Rovina, Ramona F. Moroni, Dario Bauer et al. "Differential Signature of the Centrosomal MARK4 Isoforms in Glioma". Analytical Cellular Pathology 34, n. 6 (2011): 319–38. http://dx.doi.org/10.1155/2011/206756.
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Background: MAP/microtubule affinity-regulating kinase 4 (MARK4) is a serine-threonine kinase expressed in two spliced isoforms, MARK4L and MARK4S, of which MARK4L is a candidate for a role in neoplastic transformation. Methods: We performed mutation analysis to identify sequence alterations possibly affecting MARK4 expression. We then investigated the MARK4L and MARK4S expression profile in 21 glioma cell lines and 36 tissues of different malignancy grades, glioblastoma-derived cancer stem cells (GBM CSCs) and mouse neural stem cells (NSCs) by real-time PCR, immunoblotting and immunohistochemistry. We also analyzed the sub-cellular localisation of MARK4 isoforms in glioma and normal cell lines by immunofluorescence. Results: Mutation analysis rules out sequence variations as the cause of the altered MARK4 expression in glioma. Expression profiling confirms that MARK4L is the predominant isoform, whereas MARK4S levels are significantly decreased in comparison and show an inverse correlation with tumour grade. A high MARK4L/MARK4S ratio also characterizes undifferentiated cells, such as GBM CSCs and NSCs. Accordingly, only MARK4L is expressed in brain neurogenic regions. Moreover, while both MARK4 isoforms are localised to the centrosome and midbody in glioma and normal cells, the L isoform exhibits an additional nucleolar localisation in tumour cells. Conclusions: The observed switch towards MARK4L suggests that the balance between the MARK4 isoforms is carefully guarded during neural differentiation but may be subverted in gliomagenesis. Moreover, the MARK4L nucleolar localisation in tumour cells features this MARK4 isoform as a nucleolus-associated tumour marker.
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Nikitenko, Agris, Aleksis Liekna, Martins Ekmanis, Guntis Kulikovskis e Ilze Andersone. "Single Robot Localisation Approach for Indoor Robotic Systems through Integration of Odometry and Artificial Landmarks". Applied Computer Systems 14, n. 1 (1 giugno 2013): 50–58. http://dx.doi.org/10.2478/acss-2013-0006.
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Abstract we present an integrated approach for robot localization that allows to integrate for the artificial landmark localization data with odometric sensors and signal transfer function data to provide means for different practical application scenarios. The sensor data fusion deals with asynchronous sensor data using inverse Laplace transform. We demonstrate a simulation software system that ensures smooth integration of the odometry-based and signal transfer - based localization into one approach.
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Ulimoen, Magnus, e Heiko Klein. "Localisation of atmospheric release of radioisotopes using inverse methods and footprints of receptors as sources". Journal of Hazardous Materials 451 (giugno 2023): 131156. http://dx.doi.org/10.1016/j.jhazmat.2023.131156.
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Tondin Ferreira Dias, Eduardo, Hugo Vieira Neto e Fábio Kurt Schneider. "A Compressed Sensing Approach for Multiple Obstacle Localisation Using Sonar Sensors in Air". Sensors 20, n. 19 (26 settembre 2020): 5511. http://dx.doi.org/10.3390/s20195511.
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Methods for autonomous navigation systems using sonars in air traditionally use the time-of-flight technique for obstacle detection and environment mapping. However, this technique suffers from constructive and destructive interference of ultrasonic reflections from multiple obstacles in the environment, requiring several acquisitions for proper mapping. This paper presents a novel approach for obstacle detection and localisation using inverse problems and compressed sensing concepts. Experiments were conducted with multiple obstacles present in a controlled environment using a hardware platform with four transducers, which was specially designed for sending, receiving and acquiring raw ultrasonic signals. A comparison between the performance of compressed sensing using Orthogonal Matching Pursuit and two traditional image reconstruction methods was conducted. The reconstructed 2D images representing the cross-section of the sensed environment were quantitatively assessed, showing promising results for robotic mapping tasks using compressed sensing.
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Rejani, Sofia, Abdellatif Khamlichi e Abdellah El-Hajjaji. "Robustness of ultrasonic detection of flaws by using synthetic aperture focusing technique". MATEC Web of Conferences 191 (2018): 00012. http://dx.doi.org/10.1051/matecconf/201819100012.
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One of the challenging problems in non-destructive evaluation is related to identification and sizing of flaws. A high resolution image of the scanned part is required. This allows, through using adequate post-processing of data, to perform localisation and sizing of a flaw. Several techniques have been introduced recently for this purpose. These include among others the synthetic aperture focusing technique, inverse wave-field extrapolation and the total focusing method. However, large uncertainties are affecting the inverse problem solution as provided by these methods when dealing with small defects. It was recognized that reconstruction based on the ultrasonic synthetic aperture focusing technique elaborated in frequency domain provides high resolution imaging even at large distances. This work focused on this promising procedure for the special case of ultrasonic imaging of flaws in 2D elastic medium under plane strain conditions, where the image is provided by a B-scan. Robustness of detection was investigated through perturbing the radargram by white noise and assessed as function of noise energy. It was found that synthetic aperture focusing technique is insensitive to noise.
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Laville, Bastien, Laure Blanc-Féraud e Gilles Aubert. "Off-The-Grid Variational Sparse Spike Recovery: Methods and Algorithms". Journal of Imaging 7, n. 12 (6 dicembre 2021): 266. http://dx.doi.org/10.3390/jimaging7120266.
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Gridless sparse spike reconstruction is a rather new research field with significant results for the super-resolution problem, where we want to retrieve fine-scale details from a noisy and filtered acquisition. To tackle this problem, we are interested in optimisation under some prior, typically the sparsity i.e., the source is composed of spikes. Following the seminal work on the generalised LASSO for measures called the Beurling-Lasso (BLASSO), we will give a review on the chief theoretical and numerical breakthrough of the off-the-grid inverse problem, as we illustrate its usefulness to the super-resolution problem in Single Molecule Localisation Microscopy (SMLM) through new reconstruction metrics and tests on synthetic and real SMLM data we performed for this review.
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Baker, C. R., e V. Hardy. "Provision of IMRT in the UK. Part 1: A review of planning, delivery and related technologies". Journal of Radiotherapy in Practice 3, n. 4 (marzo 2003): 175–80. http://dx.doi.org/10.1017/s1460396903000529.
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The concept of intensity-modulated radiotherapy is now familiar to everyone working in radiotherapy in the UK. To date however, the majority of UK radiotherapy departments have yet to offer this technique clinically. Implementation of IMRT represents a significant change in practice from the delivery of conventional or conformal treatment, requiring careful planning and a full understanding of the issues and new technology involved.This paper provides a review of the stages involved in the IMRT process; from localisation and immobilisation through inverse treatment planning and quality control to delivery and verification, highlighting those aspects that represent a significant change in practice or approach.Current and future developments that are expected to enhance or provide alternatives to IMRT, such as developments in radiobiological modelling, functional imaging, tomotherapy and proton therapy are discussed.
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Bos, Frédéric, Laurent Le Magorou e Frédéric Rouger. "An approach to viscoelastic behaviour analysis of wood-based panels by an inverse method of characterisation". Holzforschung 59, n. 5 (1 settembre 2005): 546–51. http://dx.doi.org/10.1515/hf.2005.090.
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Abstract The main objective of this paper is to propose an alternative method for viscoelastic characterisation of wood-based panels. Our approach, based on inverse identification methods, allows simultaneous estimation of the whole bending/torsion stiffness matrix of orthotropic plates. Elastic or viscoelastic characterisations are carried out according to the same protocol. The first step consists of optimisation of the experimental set-up, i.e., determination of the best localisation and intensity of the applied stresses and of the best position for boundary conditions. This step is realised for each type of panel using generic algorithms to obtain sensitivities satisfying the test for each stiffness matrix component. An identification procedure is then performed using a finite element program. The measurement of the whole displacement field (500×500 mm2) is made using an optical system. Validation of the elastic identification is carried out by comparison with the mechanical properties obtained from a vibrating test and a simulation tool. Non-conventional analysis of the viscoelastic behaviour of wood-based panels is illustrated for two particular plywood panels.
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Mitra, Sachinath, Tapan Pal e Taraknath Pal. "Electron “localisation” at B-site: A concomitant process for oxidation of Cr-spinels to a “partly inverse” form". Solid State Communications 77, n. 4 (gennaio 1991): 297–301. http://dx.doi.org/10.1016/0038-1098(91)90838-m.
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Venditti, Paola, Paolo Bergamo, Riccardo Talevi, Giovanni sansone e Paolo Abrescia. "Localisation and capacitation-dependent loss of buffalo sperm-coating antigens shared with rat sperm". Zygote 2, n. 1 (febbraio 1994): 5–13. http://dx.doi.org/10.1017/s0967199400001714.
Testo completoAbstract (sommario):
SummaryThe heterodimeric sperm-coating protein CFS was previously localised on the middle-piece region of rat spermatozoa by anti-CFS rabbit antibodies. CFS-immunorelated antigens were detected in the secretion of the water buffalo seminal vesicle by protein electrophoresis and Western blotting. Spermatozoa from buffalo epididymal cauda were incubated with the rat antigen and, upon immunostaining with anti-CFS antibodies and goat anti-rabbit fluorescein isothiocyanate (FITC)-conjugated IgGs, CFS was found attached on both the post-acrosomal region and the tail. Indirect immunofluorescence analysis permitted the localisation of CFS-related antigens on the same domains of buffalo ejaculated spermatozoa. These results suggest that the buffalo antigens not only share some epitopes with the homologous rat antigen but may also have some of its functional properties. Ejaculated spermatozoa were capacitated in vitro and then assayed for their content of CFS-like antigens. An inverse relationship was found between the levels of capacitation and the amounts of antigens detected, thus suggesting that the in vitro treatment was effective at removing CFS-related proteins from the cell surface. Titration of these proteins to proteins to monitor plasma membrane changes during sperm manipulation or to evaluate sperm quality is proposed.
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Vanni, S. "A Neuromagnetic View of the Human Visual Brain". Perception 26, n. 1_suppl (agosto 1997): 25. http://dx.doi.org/10.1068/v970022.
Testo completoAbstract (sommario):
A visual stimulus typically activates several cortical areas, both sequentially and overlapping in time. Characterisation of this temporal activation sequence has significantly improved with the recent development of whole-scalp neuromagnetometers. The magnetoencephalographic (MEG) signals mainly arise from time-locked cortical activity. Although the spatial localisation of several simultaneously active areas is ambiguous because of the non-uniqueness of the inverse problem, the comparison of estimated source regions across observers and utilisation of previous functional knowledge can usually resolve this ambiguity. Visual object naming, for example, generates cortical activation progressing bilaterally from occipital to temporal and frontal lobes. Simultaneously, the parieto-occipital alpha rhythm dampens as a function of task demands. Similarly, this rhythm is at a lower level after objects than non-objects in an object-detection task, which suggests that the parieto-occipital area is active when attending to visual form. In addition, this area generates evoked responses after voluntary blinks, saccades, and luminance increments, which in turn suggests that it participates in the updating of visual percepts. The sources of extrastriate MEG signals are generally in good agreement with the location of activation found with other imaging methods: visual motion activates the V5 in the ascending limb of the inferior temporal sulcus, faces the ventral temporo-occipital cortex, and objects the lateral occipital (LO) regions. Interestingly, the strength of the right LO activity closely follows the proportion of correctly detected objects. The future neuromagnetic studies will focus not only on functional localisation of the active areas, but also on how the brain processes various stimuli.
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Holder, D. S., M. Mansouri e C. Binnie. "Experimental validation of the localisation accuracy of inverse dipole modelling of the EEG in a saline filled spherical tank". Electroencephalography and Clinical Neurophysiology 98, n. 2 (febbraio 1996): P2. http://dx.doi.org/10.1016/0013-4694(96)84517-2.
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Pal, Tapan, Hi-Soo Moon e Sachinath Mitra. "Distribution of Iron Cations in Natural Chromites at Different Stages of Oxidatio - A57Fe Mossbauer Investigation". Journal Geological Society of India 44, n. 1 (1 luglio 1994): 53–64. http://dx.doi.org/10.17491/jgsi/1994/440105.
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Abstract 57Fe Mossbauer spectroscopic investigation of natural chromites from two chromite deposits of India (Sukinda and Byrapur) documents partly inverse spinel structure arising out of oxidation. The spectral fitting was based on allowing a disordering distribution of Fe2+ and Fe3+ ions at tetrahedral (A) and octahedral (B) sites. Mossbauer investigation of the samples taken from the physico-chemically distinct two horizons of Sukinda viz. brown are and grey ores, and Byrapur area revealed three types of iron ion distribution as: Fe2+(A), Fe3+(A) and Fe2+(B) (GC-group); (b) Fe3+(A1), Fe3+(A2) and Fe2+(B) (BC-2 group), and (c) Fe3+(A1), Fe3+(A2) and Fe3+(B) (BC-1 group). The distribution pattern of iron cations at A and B sites was linked to the degree of oxidation. The stages of oxidation could be modelled from normal to inverse fonn. A model suggesting 'electron localisation' at the B-sites makes the intermediate stage. Iron site occupancy determined by Mossbauer spectroscopy of the presently studied samples indicates that these fall under three groups of oxidation stages. An early stage of oxidation is shown by samples of group GC, intermediate stage by group BC-2 and final stage by BC-1 group of chromite samples. The imprint of progressive oxidation manifested by Fe cation site occupancy has been correlated with the Fe2+/S:Fe ratios, obtained for each group of samples.
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Cruz Ulloa, Christyan, Anne Krus, Antonio Barrientos, Jaime Del Cerro e Constantino Valero. "Robotic Fertilisation Using Localisation Systems Based on Point Clouds in Strip-Cropping Fields". Agronomy 11, n. 1 (23 dicembre 2020): 11. http://dx.doi.org/10.3390/agronomy11010011.
Testo completoAbstract (sommario):
The use of robotic systems in organic farming has taken on a leading role in recent years; the Sureveg CORE Organic Cofund ERA-Net project seeks to evaluate the benefits of strip-cropping to produce organic vegetables. This includes, among other objectives, the development of a robotic tool that facilitates the automation of the fertilisation process, allowing the individual treatment (at the plant level). In organic production, the slower nutrient release of the used fertilisers poses additional difficulties, as a tardy detection of deficiencies can no longer be corrected. To improve the detection, as well as counter the additional labour stemming from the strip-cropping configuration, an integrated robotic tool is proposed to detect individual crop deficiencies and react on a single-crop basis. For the development of this proof-of-concept, one of the main objectives of this work is implementing a robust localisation method within the vegetative environment based on point clouds, through the generation of general point cloud maps (G-PC) and local point cloud maps (L-PC) of a crop row. The plants’ geometric characteristics were extracted from the G-PC as a framework in which the robot’s positioning is defined. Through the processing of real-time lidar data, the L-PC is then defined and compared to the predefined reference system previously deduced. Both subsystems are integrated with ROS (Robot Operating System), alongside motion planning, and an inverse kinematics CCD (Cyclic Coordinate Descent) solver, among others. Tests were performed using a simulated environment of the crop row developed in Gazebo, followed by actual measurements in a strip-cropping field. During real-time data-acquisition, the localisation error is reduced from 13 mm to 11 mm within the first 120 cm of measurement. The encountered real-time geometric characteristics were found to coincide with those in the G-PC to an extend of 98.6%.
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McCann, Hannah, e Leandro Beltrachini. "Impact of skull sutures, spongiform bone distribution, and aging skull conductivities on the EEG forward and inverse problems". Journal of Neural Engineering 19, n. 1 (1 febbraio 2022): 016014. http://dx.doi.org/10.1088/1741-2552/ac43f7.
Testo completoAbstract (sommario):
Abstract Objective. Source imaging is a principal objective for electroencephalography (EEG), the solutions of which require forward problem (FP) computations characterising the electric potential distribution on the scalp due to known sources. Additionally, the EEG-FP is dependent upon realistic, anatomically correct volume conductors and accurate tissue conductivities, where the skull is particularly important. Skull conductivity, however, deviates according to bone composition and the presence of adult sutures. The presented study therefore analyses the effect the presence of adult sutures and differing bone composition have on the EEG-FP and inverse problem (IP) solutions. Approach. Utilising a well-established head atlas, detailed head models were generated including compact and spongiform bone and adult sutures. The true skull conductivity was considered as inhomogeneous according to spongiform bone proportion and sutures. The EEG-FP and EEG-IP were solved and compared to results employing homogeneous skull models, with varying conductivities and omitting sutures, as well as using a hypothesised aging skull conductivity model. Main results. Significant localised FP errors, with relative error up to 85%, were revealed, particularly evident along suture lines and directly related to the proportion of spongiform bone. This remained evident at various ages. Similar EEG-IP inaccuracies were found, with the largest (maximum 4.14 cm) across suture lines. Significance. It is concluded that modelling the skull as an inhomogeneous layer that varies according to spongiform bone proportion and includes differing suture conductivity is imperative for accurate EEG-FP and source localisation calculations. Their omission can result in significant errors, relevant for EEG research and clinical diagnosis.
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MARTINS, ANA RITA, TERESA MONTEIRO FERNANDES e DAVID RAIMUNDO. "EXTENSION OF FUNCTORS FOR ALGEBRAS OF FORMAL DEFORMATION". Glasgow Mathematical Journal 56, n. 1 (20 agosto 2013): 103–41. http://dx.doi.org/10.1017/s0017089513000116.
Testo completoAbstract (sommario):
AbstractSuppose we are given complex manifoldsXandYtogether with substacks$\mathcal{S}$and$\mathcal{S}'$of modules over algebras of formal deformation$\mathcal{A}$onXand$\mathcal{A}'$onY, respectively. Also, suppose we are given a functor Φ from the category of open subsets ofXto the category of open subsets ofYtogether with a functorFof prestacks from$\mathcal{S}$to$\mathcal{S}'\circ\Phi$. Then we give conditions for the existence of a canonical functor, extension ofFto the category of coherent$\mathcal{A}$-modules such that the cohomology associated to the action of the formal parameter$\hbar$takes values in$\mathcal{S}$. We give an explicit construction and prove that when the initial functorFis exact on each open subset, so is its extension. Our construction permits to extend the functors of inverse image, Fourier transform, specialisation and micro-localisation, nearby and vanishing cycles in the framework of$\mathcal{D}[[\hbar]]$-modules. We also obtain the Cauchy–Kowalewskaia–Kashiwara theorem in the non-characteristic case as well as comparison theorems for regular holonomic$\mathcal{D}[[\hbar]]$-modules and a coherency criterion for proper direct images of good$\mathcal{D}[[\hbar]]$-modules.
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Korda, David, Michal Švanda e Junwei Zhao. "Comparison of time–distance inversion methods applied to SDO/HMI Dopplergrams". Astronomy & Astrophysics 629 (settembre 2019): A55. http://dx.doi.org/10.1051/0004-6361/201936268.
Testo completoAbstract (sommario):
Context. The Helioseismic and Magnetic Imager (HMI) onboard the Solar Dynamics Observatory (SDO) satellite has been observing the Sun since 2010. The uninterrupted series of Dopplergrams are ideal for studying the dynamics of the upper solar convection zone. Within the Joint Science Operations Center (JSOC) the time–distance inversions for flows and sound-speed perturbations were introduced. The automatic pipeline has produced flow and sound-speed maps every 8 h. We verify the results of JSOC inversions by comparing the data products to equivalent results from inverse modelling obtained by an independent inversion pipeline. Aims. We compared the results from the JSOC pipeline for horizontal flow components and the perturbations of the speed of sound at set of depths with equivalent results from an independently implemented pipeline using a different time–distance inversion scheme. Our inversion pipeline allows inversion for all quantities at once while allowing minimisation of the crosstalk between them. This gives us an opportunity to discuss the possible biases present in the JSOC data products. Methods. For the tests we used the subtractive optimally localised averaging (SOLA) method with a minimisation of the cross-talk. We compared three test inversions for each quantity at each target depth. At first, we used the JSOC setup to reproduce the JSOC results. Subsequently, we used the extended pipeline to improve these results by incorporating more independent travel-time measurements but keeping the JSOC-indicated localisation in the Sun. Finally, we inverted for flow components and sound-speed perturbations using a localisation kernel with properties advertised in the JSOC metadata. Results. We successfully reproduced the horizontal flow components. The sound-speed perturbations are strongly affected by the high level of the cross-talk in JSOC products. This leads to larger amplitudes in the inversions for the sound-speed perturbations. Different results were obtained when a target function localised around the target depth was used. This is a consequence of non-localised JSOC averaging kernels. We add that our methodology also allows inversion for the vertical flow.
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Butz, Henriett, Viktória Vereczki, Barna Budai, Gábor Rubovszky, Rebeka Gyebrovszki, Ramóna Vida, Erika Szőcs et al. "Glucocorticoid Receptor Isoforms in Breast Cancer Raise Implications for Personalised Supportive Therapies". International Journal of Molecular Sciences 25, n. 21 (3 novembre 2024): 11813. http://dx.doi.org/10.3390/ijms252111813.
Testo completoAbstract (sommario):
Glucocorticoid receptor (GR) activation may promote metastasis in oestrogen receptor-negative and triple-negative breast cancer (TNBC). However, the role of the GRβ isoform, which has opposing effects to the main isoform, has not been studied in clinical samples. We aimed to analyse the intracellular localisation of total GR and GRβ in vitro using plasmid constructs and fluorescent immunocytochemistry. Additionally, our goal was to perform immunostaining for total GR and GRβ on two cohorts: (i) on 194 clinical breast cancer samples to compare the expression in different molecular subtypes, and (ii) on 161 TNBC samples to analyse the association of GR with survival. We supplemented our analysis with RNA data from 1097 TNBC cases. We found that in the absence of the ligand, GR resided in the cytoplasm of breast cancer cells, while upon ligand activation, it translocated to the nucleus. A negative correlation was found between cytoplasmic GRtotal and Ki67 in luminal A tumours, while the opposite trend was observed in TNBC samples. Tumours with strong lymphoid infiltration showed higher cytoplasmic GRtotal staining compared to those with weaker infiltration. Patients with high nuclear GRtotal staining had shorter progression-free survival in univariate analysis. High cytoplasmic GRβ was a marker for better overall survival in multivariate analysis (10-year overall survival HR [95% CI]: 0.46 [0.22–0.95], p = 0.036). As a conclusions, this study is the first to investigate GRβ expression in breast tumours. Different expression and cellular localisation of GRtotal and GRβ were observed in the context of molecular subtypes, underscoring the complex role of GR in breast cancer. An inverse association between cytoplasmic GRtotal and the Ki67 proliferation index was observed in luminal A and TNBC. Regarding the impact of GR on outcomes in TNBC patients, while cytoplasmic GRβ was associated with a better prognosis, patients with nuclear GRtotal staining may be at a higher risk of disease progression, as it negatively affects survival. Caution should be exercised when using glucocorticoids in patients with nuclear GR staining, as it may negatively impact survival.
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McDonald, Thomas, Mark Robinson e GuiYun Tian. "Spatial resolution enhancement of rotational-radar subsurface datasets using combined processing method". Journal of Physics: Conference Series 2090, n. 1 (1 novembre 2021): 012001. http://dx.doi.org/10.1088/1742-6596/2090/1/012001.
Testo completoAbstract (sommario):
Abstract Effective visualisation of railway tunnel subsurface features (e.g. voids, utilities) provides critical insight into structural health and underpins planning of essential targeted predictive maintenance. Subsurface visualisation here utilises a rotating ground penetrating radar antenna system for 360° point cloud data capture. This technology has been constructed by our industry partner Railview Ltd, and requires the development of complimentary signal processing algorithms to improve feature localisation. The main novelty of this work is extension of Shrestha and Arai’s Combined Processing Method (CPM) to 360° Ground Penetrating Radar (360GPR) datasets, for first-time application in the context of railway tunnel structural health inspection. Initial experimental acquisition of a sample rotational transect for CPM enhancement is achieved by scanning a test section of tunnel sidewall - featuring predefined target geometry - with the rotating antenna. Next, frequency data separately undergo Inverse Fast Fourier Transform (IFFT) and Multiple Signal Classification (MUSIC) processing to recover temporal responses. Numerical implementation steps are explicitly provided for both MUSIC and two associated spatial smoothing algorithms, addressing an identified information deficit in the field. Described IFFT amplitude is combined with high spatial resolution of MUSIC via the CPM relation. Finally, temporal responses are compared qualitatively and quantitatively, evidencing the significant enhancement capabilities of CPM.
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Erice, Borja, Daniel Thomson, Sathiskumar A. Ponnusami, Mehtab V. Pathan e Nik Petrinic. "On the Rate-dependent Plasticity Modelling of Unidirectional Fibre-reinforced Polymeric Matrix Composites". EPJ Web of Conferences 183 (2018): 01055. http://dx.doi.org/10.1051/epjconf/201818301055.
Testo completoAbstract (sommario):
Three different approaches to plasticity are investigated to model the experimentally-observed non-linear behaviour of unidirectional fibre-reinforced polymeric matrix materials. The first and simplest approach consists on assuming independent one-dimensional rate-dependent plasticity on in-plane (12) and through-thickness longitudinal (13) shear components of the Cauchy stress tensor. The second, employs a 3D extension of the plane stress Hill’48 anisotropic plastic surface. The third and the last is formulated as a quadratic yield function inspired by Puck’s fracture initiation criterion. It searches for a plastic localisation plane in which a certain combination of normal and shear stresses is maximum. Numerical simulations are conducted to analyse the off-axis compression behaviour of carbon fibre reinforced epoxy composite under varying loading rates. The afore-mentioned three different approaches are explored with an aim to predict the experimentally-observed non-linear response of such composites. The model parameters are determined using a deterministic inverse modelling strategy employing an iterative domain reduction optimisation technique. As far as the experiments are concerned, the quasi-static and medium rate tests were carried out in universal testing machines, while the experiments at high rate were conducted in a Split Hopkinson Pressure Bar system. The effectiveness in terms of accuracy and robustness of the three approaches are discussed.
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Sharpley, Christopher F., Ian D. Evans, Vicki Bitsika, Wayne M. Arnold, Emmanuel Jesulola e Linda L. Agnew. "Frontal Alpha Asymmetry Argues for the Heterogeneity of Psychological Resilience". Brain Sciences 13, n. 9 (21 settembre 2023): 1354. http://dx.doi.org/10.3390/brainsci13091354.
Testo completoAbstract (sommario):
Depression is associated with frontal alpha asymmetry (FAA) and Psychological Resilience (PR), although in different ways. Only cursory attention has been given to how these three constructs interact despite the possible clinical and research implications of those associations. One limitation of recent research into these associations has been conceptualising PR as a unitary construct, whereas it has been shown to be multi-component. This study investigated the underlying components of PR, their correlations with FAA, and the effect that participants’ depressive status had upon those correlations in a community sample of 54 males and 46 females aged between 18 yr and 75 years. Results confirmed the overall inverse association between total PR and depression for four of the original five PR components and for one of the two components found in this sample. Similarly, there were differences between the ways that FAA and PR components were associated, depending upon the depressive status of participants. Source localisation data indicated that the PR components were not uniformly correlated with alpha activity in the same brain regions. These findings of content, efficacy, and neurophysiological differences between the five components of PR and their associations with FAA argue against consideration of PR as a unitary construct.
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Friedlein, Johannes, Max Böhnke, Malte Schlichter, Mathias Bobbert, Gerson Meschut, Julia Mergheim e Paul Steinmann. "Material Parameter Identification for a Stress-State-Dependent Ductile Damage and Failure Model Applied to Clinch Joining". Journal of Manufacturing and Materials Processing 8, n. 4 (24 luglio 2024): 157. http://dx.doi.org/10.3390/jmmp8040157.
Testo completoAbstract (sommario):
Similar to bulk metal forming, clinch joining is characterised by large plastic deformations and a variety of different 3D stress states, including severe compression. However, inherent to plastic forming is the nucleation and growth of defects, whose detrimental effects on the material behaviour can be described by continuum damage models and eventually lead to material failure. As the damage evolution strongly depends on the stress state, a stress-state-dependent model is utilised to correctly track the accumulation. To formulate and parameterise this model, besides classical experiments, so-called modified punch tests are also integrated herein to enhance the calibration of the failure model by capturing a larger range of stress states and metal-forming-specific loading conditions. Moreover, when highly ductile materials are considered, such as the dual-phase steel HCT590X and the aluminium alloy EN AW-6014 T4 investigated here, strong necking and localisation might occur prior to fracture. This can alter the stress state and affect the actual strain at failure. This influence is captured by coupling plasticity and damage to incorporate the damage-induced softening effect. Its relative importance is shown by conducting inverse parameter identifications to determine damage and failure parameters for both mentioned ductile metals based on up to 12 different experiments.
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CHAMBON, Joannès, Paillasseur SéBASTIEN, Olivier MINCK, Jeroen LANSLOTS e Laurent DE RYCK. "Assessment of planar array accuracy for 3D sound source reconstruction with Bayesian Focusing". INTER-NOISE and NOISE-CON Congress and Conference Proceedings 270, n. 7 (4 ottobre 2024): 4551–59. http://dx.doi.org/10.3397/in_2024_3477.
Testo completoAbstract (sommario):
As planar microphone arrays were initially designed for bidimensional sound source localisation, their use for three-dimensional acoustic imaging consistently suffers from a poor resolution along the normal axis. Such a statement is already well documented for beamforming approaches and their declensions. Bearing this in mind, this paper delves into the possibilities offered by inverse methods and especially iterative Bayesian Focusing to tackle this issue and deliver accurate source positions in three dimensions based on planar array measurements only. To this end, an experimental set up is designed: omnidirectional sources are mounted in a wooden mock-up featuring faces at different distances from an 81 MEMs planar array. Based on this measurements, a benchmark study of sound source reconstruction on a 3D mesh of the mock-up is conducted and compared to classical 2D acoustic maps set at different depths. The latter process is declined for various source correlation values and at extended frequency ranges. By doing so, the current paper delivers an overview of the ability to discriminate acoustic sources along the normal axis of a planar array, on a simple and well controlled test case, with a view to provide guidelines for further applications of 3D acoustic imaging on complex geometries.
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Rodriguez, Valeria, Gabriela Diaz de Barboza, Ruben Ponce, Valeria Merico, Silvia Garagna e Nori Tolosa de Talamoni. "Spermatocyte apoptosis, which involves both intrinsic and extrinsic pathways, explains the sterility of Graomys griseoflavus × Graomys centralis male hybrids". Reproduction, Fertility and Development 22, n. 2 (2010): 478. http://dx.doi.org/10.1071/rd09106.
Testo completoAbstract (sommario):
Spermatogenic impairment and the apoptotic pathways involved in establishing sterility of male hybrids obtained from crossing Graomys griseoflavus females with Graomys centralis males were studied. Testes from G. centralis, G. griseoflavus and hybrids were compared at different ages. Terminal transferase-mediated dUTP nick-end labelling assay (TUNEL), Fas, Bax and cytochrome c labelling were used for apoptosis evaluation, and calbindin D28k staining as an anti-apoptotic molecule. In 1-month-old animals, spermatocytes were positive for all apoptotic markers, but moderate TUNEL (+) spermatocyte frequency was only found in G. centralis. At subsequent ages, the apoptotic markers were downregulated in testes from parental cytotypes, but not in hybrid testes. TUNEL (+) spermatocytes were present at 78% and 44% per tubule cross-section in 2- and 3-month-old hybrid animals, respectively. Pachytene spermatocyte death in adult hybrids occurs via apoptosis, as revealed by high caspase-3 expression. Calbindin was highly expressed in spermatocytes of adult hybrids, in which massive cell death occurs via apoptosis. Calbindin co-localisation with TUNEL or Fas, Bax and cytochrome c was very limited, suggesting an inverse regulation of calbindin and apoptotic markers. Hybrid sterility is due to breakdown of spermatogenesis at the pachytene spermatocyte stage. Both extrinsic and intrinsic pathways are involved in apoptosis of spermatocytes, which are the most sensitive cell type to apoptotic stimuli.
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Farrag, K., J. Woldeab, J. M. Stein e A. Aksan. "P642 Crossroads of vitamin B6 deficiency and inflammation in inflammatory bowel disease: Preliminary results of a cross-sectional study". Journal of Crohn's and Colitis 16, Supplement_1 (1 gennaio 2022): i558—i559. http://dx.doi.org/10.1093/ecco-jcc/jjab232.764.
Testo completoAbstract (sommario):
Abstract Background The robust relationship between vitamin B6 and inflammation has become apparent over the last decade. However, the mechanistic nature of this relationship remains unclear. Evidence suggests an inverse relationship between blood levels of B6 and inflammation, but also a potential two-way relationship between the two. Thus, whereas inflammation can deplete serum vitamin B6, vitamin B6 insufficiency can attenuate inflammation. This study aimed to assess vitamin B status in patients with IBD in routine clinical practice and identify possible relationships between vitamin B6 status and clinical disease characteristics. Methods In a comparative, retrospective cross-sectional study, serum samples of patients with IBD were studied. CBC, albumin and hsCRP were determined and samples assessed for presence/absence of inflammation (serum hsCRP, cut-off <5mg/L). Vitamin B6 status was determined via direct measurement of pyridoxal 5′-phosphate (PLP) by enzymatic assay. Results 149 patients with IBD (64f/85m; 82CD/67UC; 39.9±14.6y) were included. Of these, 44/149 had inflammation (19f/25m; 22CD/22UC; 41.2±14.9y) and 105/149 no inflammation (45f/60m; 60CD/45UC; 39.3±14.4y). In patients with inflammation, mean serum PLP levels were significantly lower (7.2[1.9–46.0] µg/L) vs. patients without inflammation (9.8[0.1–88.0] µg/L) (p<0.05). Accordingly, vitamin B6 deficiency occurred significantly more frequently in patients with vs. without inflammation (34.1% vs. 19.0%, p<0.05). A higher incidence of vitamin B6 deficiency was seen in patients with CD vs. UC, though without statistical significance (26.8% vs. 19.4%, p>0.05). The frequency of vitamin B6 deficiency did not differ according to disease localisation (p>0.05). Serum PLP levels inversely correlated with the inflammatory markers hsCRP and ESR (r=-0.306, p<0.001 and r=-0.203, p<0.001, respectively). Furthermore, there was a significant positive correlation between blood PLP levels and other selected acute-phase reactants, e.g., TSAT% (r= 0.207, p<0.05). However, no significant correlation was found with ferritin (r=-0.152, p=0.064). Conclusion Low serum total vitamin B6 levels were associated with inflammation but not disease type or localisation in patients with IBD. In line with preclinical findings and previous observational studies, vitamin B6 deficiency was more pronounced in patients with inflammation. Our findings suggest vitamin B6 may have a bigger role than thought in IBD; besides its relationship with inflammation, a possible involvement of vitamin B6 deficiency as cause or effect in IBD pathogenesis warrants investigation. Routine assessment and correction of vitamin B6 status may ameliorate IBD and help maintain intestinal integrity.
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Pilia, Nicolas, Christian Ritter, Danila Potyagaylo, Walther H. W. Schulze, Olaf Dössel e Gustavo Lenis. "Determination of the excitation origin in the ventricles from the ECG using support vector regression". Current Directions in Biomedical Engineering 3, n. 2 (7 settembre 2017): 257–60. http://dx.doi.org/10.1515/cdbme-2017-0180.
Testo completoAbstract (sommario):
AbstractA common treatment of focal ventricular tachycardia is the catheter ablation of triggering sites. They have to be found manually by the physician during an intervention in a catheter lab. Thus, a method for determining the position of the focus automatically is desired. The inverse problem of electrocardiography addresses this problem by reconstructing the source of the ectopic beats using the surface ECG. This problem is ill-posed and therefore needs specific methods for solving it. We propose a machine learning approach for localisation of the ectopic foci in the heart to assist cardiologists with their therapy planning.We simulated 600 120-lead ECGs with different known excitation origins in the heart using a cellular automaton followed by a forward calculation. Features from the ECGs were used as input for a support vector regression (SVR). We assumed a functional relation between features from the ECG and the excitation origin. To benchmark SVR, we also used the well-known Tikhonov 0th order regularisation to reconstruct the transmembrane potentials in the heart and detect the location of the ectopic foci. Parameters for SVR and regularisation were chosen using a grid search minimising the error between estimated and true excitation origin. Compared to the Tikhonov regularisation method, SVR achieved a smaller deviation between estimated and real excitation origin evaluated with 6-fold cross validation. Future work could investigate on the behaviour on data from simulations with other torso and electrophysiological models, the influence of other methods for feature extraction and finally the evaluation with clinical data.
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Min, Haigen, Xia Wu, Chaoyi Cheng e Xiangmo Zhao. "Kinematic and Dynamic Vehicle Model-Assisted Global Positioning Method for Autonomous Vehicles with Low-Cost GPS/Camera/In-Vehicle Sensors". Sensors 19, n. 24 (9 dicembre 2019): 5430. http://dx.doi.org/10.3390/s19245430.
Testo completoAbstract (sommario):
Real-time, precise and low-cost vehicular positioning systems associated with global continuous coordinates are needed for path planning and motion control in autonomous vehicles. However, existing positioning systems do not perform well in urban canyons, tunnels and indoor parking lots. To address this issue, this paper proposes a multi-sensor positioning system that combines a global positioning system (GPS), a camera and in-vehicle sensors assisted by kinematic and dynamic vehicle models. First, the system eliminates image blurring and removes false feature correspondences to ensure the local accuracy and stability of the visual simultaneous localisation and mapping (SLAM) algorithm. Next, the global GPS coordinates are transferred to a local coordinate system that is consistent with the visual SLAM process, and the GPS and visual SLAM tracks are calibrated with the improved weighted iterative closest point and least absolute deviation methods. Finally, an inverse coordinate system conversion is conducted to obtain the position in the global coordinate system. To improve the positioning accuracy, information from the in-vehicle sensors is fused with the interacting multiple-model extended Kalman filter based on kinematic and dynamic vehicle models. The developed algorithm was verified via intensive simulations and evaluated through experiments using KITTI benchmarks (A project of Karlsruhe Institute of Technology and Toyota Technological Institute at Chicago) and data captured using our autonomous vehicle platform. The results show that the proposed positioning system improves the accuracy and reliability of positioning in environments in which the Global Navigation Satellite System is not available. The developed system is suitable for the positioning and navigation of autonomous vehicles.
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Bosse, Stefan, Dennis Weiss e Daniel Schmidt. "Supervised Distributed Multi-Instance and Unsupervised Single-Instance Autoencoder Machine Learning for Damage Diagnostics with High-Dimensional Data—A Hybrid Approach and Comparison Study". Computers 10, n. 3 (18 marzo 2021): 34. http://dx.doi.org/10.3390/computers10030034.
Testo completoAbstract (sommario):
Structural health monitoring (SHM) is a promising technique for in-service inspection of technical structures in a broad field of applications in order to reduce maintenance efforts as well as the overall structural weight. SHM is basically an inverse problem deriving physical properties such as damages or material inhomogeneity (target features) from sensor data. Often models defining the relationship between predictable features and sensors are required but not available. The main objective of this work is the investigation of model-free distributed machine learning (DML) for damage diagnostics under resource and failure constraints by using multi-instance ensemble and model fusion strategies and featuring improved scaling and stability compared with centralised single-instance approaches. The diagnostic system delivers two features: A binary damage classification (damaged or non-damaged) and an estimation of the spatial damage position in case of a damaged structure. The proposed damage diagnostics architecture should be able to be used in low-resource sensor networks with soft real-time capabilities. Two different machine learning methodologies and architectures are evaluated and compared posing low- and high-resolution sensor processing for low- and high-resolution damage diagnostics, i.e., a dedicated supervised trained low-resource and an unsupervised trained high-resource deep learning approach, respectively. In both architectures state-based recurrent artificial neural networks are used that process spatially and time-resolved sensor data from experimental ultrasonic guided wave measurements of a hybrid material (carbon fibre laminate) plate with pseudo defects. Finally, both architectures can be fused to a hybrid architecture with improved damage detection accuracy and reliability. An extensive evaluation of the damage prediction by both systems shows high reliability and accuracy of damage detection and localisation, even by the distributed multi-instance architecture with a resolution in the order of the sensor distance.
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Zubov, Ilya G. "Method for Automatic Segmentation of Vehicles in Digital Images". Journal of the Russian Universities. Radioelectronics 22, n. 5 (4 dicembre 2019): 6–16. http://dx.doi.org/10.32603/1993-8985-2019-22-5-6-16.
Testo completoAbstract (sommario):
Introduction. Modern systems for active vehicle safety are designed to significantly reduce the number of road accidents. Sensors based on monocular cameras are increasingly being introduced by the world's leading automakers as an effective tool for improving traffic safety. Modern methods of localisation and classification, combined with semantic segmentation algorithms, allow for image division into independent groups of pixels corresponding to each object. However, the problem of developing segmentation algorithms ensuring improved quality of image segmentation remains to be solved.Aim. To develop an automatic method for segmenting a given object during image analysis.Materials and methods. An automatic method for segmenting vehicles in an image was proposed. The method presented herein allows semantic segmentation of the object of interest, based upon a priori information about the bounding boxes, which frame the objects in the image. Bounding box information is used to transform an image into a polar coordinate system where the pixels of the image act as the edges of a weighted graph. A closed contour is obtained around the object of interest by using the shortest path search algorithm and inverse transformation to the Cartesian coordinate system.Results. The experiments confirmed the correctness of the selected area of interest based on this algorithm. Jacquard’s similarity coefficient for the Carvana open database is 85 %. Furthermore, the proposed method was applied to different classes of images from the Pascal VOC database, thus demonstrating the ability to segment objects of other classes.Conclusion. The main contribution of the proposed method was as follows: 1) segmentation of the object of interest at the level of modern methods, and in some cases in excess thereof; 2) the study presents a new look at the way of tracking object contours.
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Boczar, J., A. Dorobczynski e J. Miakotoi. "Modèle de transfert et de diffusion de masse dans un écoulement, en présence de gradients de vitesse et de gradients du coefficient de diffusion turbulente". Revue des sciences de l'eau 5, n. 3 (12 aprile 2005): 353–79. http://dx.doi.org/10.7202/705136ar.
Testo completoAbstract (sommario):
Le travail présente un modèle mathématique conceptuel de transfert et de diffusion de masse destiné à l'étude des migrations d'effluents en rivière. Ce modèle prend en compte l'existence d'écoulements cisaillés ainsi que la présence de gradients de diffusion turbulente. Il permet de calculer les champs de concentrations et les valeurs moyennes de concentration à travers toute section transversale de l'écoulement. La localisation et la taille relative du rejet sont respectées. L'influence des rives sur les processus de dispersion est prise en considération.Pour quantifier l'influence des berges, une relation est établie entre les concentrations calculées en écoulement de largeur infinie et les concentrations en écoulement d'extension limitée. La méthode utilisée est fondée sur l'emploi d'un champ de vitesse et d'un champ de coefficient de diffusion, symétriques par rapport à des lignes riveraines séparant le courant nul d'un courant fictif situé de part et d'autre de ces limites.Les résultats des tests du modèle mathématique, réalisés à l'aide du programme moniteur « Gradient 2 », sont présentés. Dans le cas d'écoulements cisaillés, on a constaté que la valeur moyenne de concentration d'effluent calculée au travers de sections transversales à l'écoulement n'était pas une quantité invariante tout au long de l'écoulement. Un gradient de vitesse négatif induit une augmentation de cette moyenne à mesure que l'on s'éloigne du rejet alors qu'un gradient positif produit l'effet inverse. Un gradient du coefficient de diffusion turbulente détermine un changement du profil de concentration à l'intérieur d'une section transversale donnée, sans en changer cependant la valeur moyenne. Un gradient négatif augmente la valeur maximale de la distribution des concentrations. Un gradient positif fait diminuer la valeur maximale en aplatissant l'allure du profil.Le modèle mathématique a ensuite été vérifié à l'aide d'un modèle physique. Un modèle réduit respectant les similitudes d'écoulement a été bâti. Les gradients de vitesse du fluide et les gradients du coefficient de diffusion étaient provoqués par l'introduction de tirants d'eau non uniformes dans chaque section transversale. Les mesures réalisées ont permis d'estimer les coefficients de diffusion turbulente.
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Graziosi, Francesco, Jgor Arduini, Paolo Bonasoni, Francesco Furlani, Umberto Giostra, Alistair J. Manning, Archie McCulloch et al. "Emissions of carbon tetrachloride from Europe". Atmospheric Chemistry and Physics 16, n. 20 (18 ottobre 2016): 12849–59. http://dx.doi.org/10.5194/acp-16-12849-2016.
Testo completoAbstract (sommario):
Abstract. Carbon tetrachloride (CCl4) is a long-lived radiatively active compound with the ability to destroy stratospheric ozone. Due to its inclusion in the Montreal Protocol on Substances that Deplete the Ozone Layer (MP), the last two decades have seen a sharp decrease in its large-scale emissive use with a consequent decline in its atmospheric mole fractions. However, the MP restrictions do not apply to the use of carbon tetrachloride as feedstock for the production of other chemicals, implying the risk of fugitive emissions from the industry sector. The occurrence of such unintended emissions is suggested by a significant discrepancy between global emissions as derived from reported production and feedstock usage (bottom-up emissions), and those based on atmospheric observations (top-down emissions). In order to better constrain the atmospheric budget of carbon tetrachloride, several studies based on a combination of atmospheric observations and inverse modelling have been conducted in recent years in various regions of the world. This study is focused on the European scale and based on long-term high-frequency observations at three European sites, combined with a Bayesian inversion methodology. We estimated that average European emissions for 2006–2014 were 2.2 (± 0.8) Gg yr−1, with an average decreasing trend of 6.9 % per year. Our analysis identified France as the main source of emissions over the whole study period, with an average contribution to total European emissions of approximately 26 %. The inversion was also able to allow the localisation of emission "hot spots" in the domain, with major source areas in southern France, central England (UK) and Benelux (Belgium, the Netherlands, Luxembourg), where most industrial-scale production of basic organic chemicals is located. According to our results, European emissions correspond, on average, to 4.0 % of global emissions for 2006–2012. Together with other regional studies, our results allow a better constraint of the global budget of carbon tetrachloride and a better quantification of the gap between top-down and bottom-up estimates.
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Prud’homme, C., S. Espinoza, C. Badoual, O. Laccourreye, P. Bonfils e D. Malinvaud. "Récidive tardive ou localisation secondaire ? Vers une meilleure compréhension de la physiopathologie du papillome inversé". Annales françaises d'Oto-rhino-laryngologie et de Pathologie Cervico-faciale 130, n. 5 (novembre 2013): 295–98. http://dx.doi.org/10.1016/j.aforl.2013.02.008.
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Kowalski, Matthieu, e Alexandre Gramfort. "A priori par normes mixtes pour les problèmes inverses. Application à la localisation de sources en M/EEG". Traitement du signal 27, n. 1 (28 febbraio 2010): 53–78. http://dx.doi.org/10.3166/ts.27.53-78.
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Djurdjevic, Gordan. "Solve et Coagula: Attitudes Toward the Ambrosial Aspects of Human Seed in Certain Yogic Traditions and in the Sexual Magick of Aleister Crowley Solve et Coagula: Attitudes envers les aspects ambroisiens de la semence humaine dans certaines traditions yogiques et dans la magie sexuelle d'Aleister Crowley". Aries 10, n. 1 (2010): 85–106. http://dx.doi.org/10.1163/156798910x12584583444952.
Testo completoAbstract (sommario):
AbstractCertaines traditions du yoga voient dans la semence mâle l'élixir potentiel d'immortalité. L'éjaculation du sperme, lequel devrait retourner à son lieu d'origine, la tête, est une perte de ce potentiel. Dans celle-ci, en effet, cette substance acquiert sa forme subtile par transformation, devenant ainsi l'élixir. La méthode consiste en une spiritualisation du matériel. Cela correspondrait au solve selon la terminologie alchimique.La magie sexuelle d'Aleister Crowley part d'un point de vue similaire, mais ici la méthode se trouve inversée, car la semence est éjectée et consommée. Le sperme matériel est sanctifié, et vu comme une théophanie. Le spirituel est matérialisé: coagula.L'objet de cet article est de comparer ces deux orientations et d'en explorer les implications, la question essentielle étant ici celle de la localisation du sacré; en effet, l'une reflète l'acosmisme des traditions indiennes, et l'autre la tendance, propre à la magie d'Aleister Crowley, de valoriser l'existence matérielle.
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Fraser, Jonathan M., e Liam Stuart. "Refined horoball counting and conformal measure for Kleinian group actions". Annales Fennici Mathematici 48, n. 1 (8 maggio 2023): 325–44. http://dx.doi.org/10.54330/afm.129606.
Testo completoAbstract (sommario):
Parabolic fixed points form a countable dense subset of the limit set of a non-elementary geometrically finite Kleinian group with at least one parabolic element. Given such a group, one may associate a standard set of pairwise disjoint horoballs, each tangent to the boundary at a parabolic fixed point. The diameter of such a horoball can be thought of as the 'inverse cost' of approximating an arbitrary point in the limit set by the associated parabolic point. A result of Stratmann and Velani allows one to count horoballs of a given size and, roughly speaking, for small \(r>0\) there are \(r^{-\delta}\) many horoballs of size approximately \(r\), where \(\delta\) is the Poincaré exponent of the group. We investigate localisations of this result, where we seek to count horoballs of size approximately \(r\) inside a given ball \(B(z,R)\). Roughly speaking, if \(r \lesssim R^2\), then we obtain an analogue of the Stratmann-Velani result (normalised by the Patterson-Sullivan measure of \(B(z,R)\)). However, for larger values of \(r\), the count depends in a subtle way on \(z\).
Our counting results have several applications, especially to the geometry of conformal measures supported on the limit set. For example, we compute or estimate several 'fractal dimensions' of certain \(s\)-conformal measures for \(s>\delta\) and use this to examine continuity properties of \(s\)-conformal measures at \(s=\delta\).
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Attard, G., Y. Rossier, J. Bardonnet e L. Eisenlohr. "Quantifier la contribution des parcelles et les temps de transit de l’eau souterraine pour protéger la qualité des captages d’eau potable". Techniques Sciences Méthodes, n. 6 (giugno 2019): 39–50. http://dx.doi.org/10.1051/tsm/201906039.
Testo completoAbstract (sommario):
En France, plusieurs milliers de captages d’eau potable présentent une dégradation avérée de la qualité de l’eau due aux pollutions diffuses, par exemple liée aux nitrates ou aux micropolluants. Une bonne partie d’entre eux exploite une ressource de nappe libre, en milieu poreux. Les gestionnaires de ces captages ont besoin de connaître les secteurs sur lesquels agir en priorité pour améliorer la qualité de l’eau prélevée et le temps de retour sur investissement des actions engagées sur les aires d’alimentation de captage (AAC). Cet article présente une méthode cartographique simple d’utilisation permettant d’optimiser les programmes d’actions consacrés à la reconquête qualitative de ces captages. Cette méthode repose sur le choix, la projection et le traitement dans un système d’information géographique (SIG) d’abaques mis à disposition par le Centre d’études et d’expertise sur les risques, l’environnement, la mobilité et l’aménagement (Cerema). Ces abaques ont été élaborés par modélisation numérique déterministe en résolvant l’équation d’advection-dispersion en écoulement inversé. Les données nécessaires pour l’application de cette méthode sont : une cartographie de l’AAC avec la localisation du captage, une carte piézométrique de l’aquifère et sa perméabilité, la recharge pluviométrique de la nappe et le débit du captage. La projection d’un abaque sur une AAC permet d’obtenir une cartographie des parcelles qui ont la plus forte contribution à l’alimentation du captage ainsi que les temps de transit de l’eau souterraine jusqu’au captage les plus courts. Ainsi, la méthode proposée constitue une aide à la décision pour la construction des programmes d’actions destinés à reconquérir la qualité des captages d’eau potable et permet le suivi et l’analyse des actions déjà mises en œuvre.