Articles de revues : « Pics spectraux »

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LAURA, C., et X. RODET. « APPARIEMENT DES PICS SPECTRAUX ET RÈGLES POUR LA SYNTHÈSE DE LA PAROLE PAR CONCATÉNATION DE DIPHONES ». Le Journal de Physique Colloques 51, n^o C2 (février 1990) : C2–531—C2–536. http://dx.doi.org/10.1051/jphyscol:19902125.

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Braun, Victoire, Sorilla Prey, Carlotta Gurioli, Franck Boralevi, Alain Taieb, Nicolas Grenier, Maya Loot, Marie-Laure Jullie et Christine Léauté-Labrèze. « Congenital haemangiomas : a single-centre retrospective review ». BMJ Paediatrics Open 4, n^o 1 (décembre 2020) : e000816. http://dx.doi.org/10.1136/bmjpo-2020-000816.

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ObjectiveCongenital haemangiomas (CHs) are rare, benign vascular tumours that are fully developed at birth. Three subtypes of CHs have been described based on clinical behaviour: rapidly involuting CHs (RICHs), non-involuting CHs (NICHs) and partially involuting CHs (PICHs). We explore in our study clinical, evolutionary and paraclinical characteristics of the three CH subtypes.DesignChildren with CH attending our department of paediatric dermatology at Bordeaux University Hospital over a 13-year period were retrospectively included. Epidemiological, clinical and evolutionary data, photographs and imaging results were reviewed. All available tissue samples were histologically examined.ResultsWe included 57 patients: 22 with RICH, 22 with NICH and 13 with PICH. Males predominated (ratio 1.7); the most common CH location was on the limbs. RICH, NICH and PICH exhibited overlapping characteristics; all were single telangiectatic lesions with pale peripheral halos. At birth, NICHs were flat but RICHs and PICHs bulky. The median age at complete RICH involution was 12 months. One-third of CHs that appeared RICH-like at birth underwent incomplete involution to become PICHs. Heart failure and thrombocytopenia were rare complications. PICHs were frequently ulcerated. Pain was common for NICH and PICH. The imaging and histological data of the three CH subtypes were rather similar.ConclusionsWe describe the characteristics and evolution of the three CH subtypes using a case series. Certain overlapping features were apparent, reinforcing the hypothesis that RICH, NICH and PICH lie on the same pathological spectrum.

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Morano, Giacomo Salvatore, Caterina Mercanti, Vincenzo Federico, Angela Matturro, Alessandra Micozzi, Roberto Latagliata, Massimo Breccia et al. « Clinical Usefulness and Safety of Peripherally-Inserted Central Catethers (PICC) in Hematological Patients. » Blood 114, n^o 22 (20 novembre 2009) : 4545. http://dx.doi.org/10.1182/blood.v114.22.4545.4545.

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Abstract Abstract 4545 The use of Peripherally-Inserted Central Catheters (PICC) as an alternative to Central Venous Catethers (CVC) is becoming very frequent in different setting of patients. To highlight the role of PICC also in patients with haematological malignancies, we revised our single Institute experience from 11/2008 to 7/2009. On the whole, 33 PICCs (BARD Groshong 4 Fr) were inserted in 32 patients [M/F 11/21, median age 59.9 years, Interquartile Range (IR) 47.1 – 74.7] for a total number of 1979 days. Twelve patients had Acute Myelogenous Leukemia (AML), 3 Acute Lymphoblastic Leukemia (ALL), 6 Non-Hodgkin Lymphoma (NHL), 5 Hodgkin Lymphoma (HD), 6 Myelodysplastic/Myeloproliferative Disorders (MDS/MPD); as to disease phase, 6 patients were at onset, 10 in complete response (3 before consolidation therapy and 7 before autologous peripheral stem-cell transplantation), 5 at disease relapse, 7 in chronic phase with transfusional requirement and 4 in advanced phase. PICC was successfully inserted in all cases with US-guide (in 21 cases via basilica vein, in 11 via brachial vein and in 1 via cephalic vein). At insertion, platelets count was < 50 × 109/l in 17/33 cases (51.5%) while WBC count was < 1.0 × 109/l in 6/33 cases (18.1%). An accidental PICC extraction occurred after 13 days; in addition, there were 2/33 (6.0%) (0,03/1000 gg) thrombophlebitic complications after 15 and 21 days respectively and 6/33 (18.1%)(0.10/1000 gg) infective complications [4 sepsis catheter-related from Staphylococci (3) or Acromobacter (1) and 2 local flogistic infiltration]. On the whole, 17/33 PICCs (51.5%) were removed after a median period of 39 days (IR 17 – 64); the reasons for removal were completion of treatment in 4 patients, death unrelated to the PICC in 6 and catheter-related complications in 7 (5 for infection, 1 for thrombosis and 1 for accidental extraction). The remaining 16/33 PICCs (48.5%) are still in use after a median period of 73 days (IR 30 – 93). In conclusion, PICC seems to be a useful, safe and promising alternative to conventional CVC for many haematological malignancies in a wide spectrum of clinical settings, ranging from intensive chemotherapy (including autotransplant procedure) to chronic management and very advanced phases requiring palliative approach. Disclosures: No relevant conflicts of interest to declare.

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Viallefont-Robinet, Bacour, Bouvet, Kheireddine, Ouhssain, Idoughi, Grignon, Munesa, Lemaître et Rivière. « Contribution to Sandy Site Characterization : Spectro-Directional Signature, Grain Size Distribution and Mineralogy Extracted from Sand Samples ». Remote Sensing 11, n^o 20 (21 octobre 2019) : 2446. http://dx.doi.org/10.3390/rs11202446.

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The characterization of sands detailed in this paper has been performed in order to support the in-flight radiometric performance assessment of space-borne optical sensors over the so-called Pseudo-Invariant Calibration Sites (PICS). Although the physical properties of PICS surface are fairly stable in time, the signal measured from space varies with the illumination and the viewing geometries. Thus, there is a need to characterize the spectro-directional properties of PICS. This could be done on a broad scale, thanks to multi-spectral multi-directional space-borne sensors such as the POLDER instrument (with old data). However, interpolating or extrapolating the spectro-directional reflectance measured from space to spectral bands of another sensor is not straightforward. The hyperspectral characterization of sand samples collected within or nearby PICS could contribute to a solution. In this context, a set of 31 sand samples was compiled. The BiConical Reflectance Factor (BCRF), linked to Bidirectional Reflectance Distribution Function (BRDF), was measured between 0.4 and 2.5 µm, over a half hemisphere when the amount of sand in the sample was large enough and for only a single fixed angular configuration for small samples. These optical measurements were complemented by grain size distribution measurements and mineralogical analysis and compiled together with previously published measurements in the so-called PICSAND database, freely available online.

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Takemura, T., A. Takada, T. Kishimoto, S. Komura, H. Kubo, Y. Matsuoka, K. Miuchi et al. « Development of the micro pixel chamber based on MEMS technology ». EPJ Web of Conferences 174 (2018) : 02010. http://dx.doi.org/10.1051/epjconf/201817402010.

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Micro pixel chambers (μ-PIC) are gaseous two-dimensional imaging detectors originally manufactured using printed circuit board (PCB) technology. They are used in MeV gamma-ray astronomy, medicalimaging, neutron imaging, the search for dark matter, and dose monitoring. The position resolution of the present μ-PIC is approximately 120 μm (RMS), however some applications require a fine position resolution of less than 100 μm. To this end, we have started to develop a μ-PIC based on micro electro mechanical system (MEMS) technology, which provides better manufacturing accuracy than PCB technology. Our simulation predicted the gains of MEMS μ-PICs to be twice those of PCB μ-PICs at the same anode voltage. We manufactured two MEMS μ-PICs and tested them to study their behavior. In these experiments, we successfully operated the fabricatedMEMS μ-PICs and we achieved a maximum gain of approximately 7×103 and collected their energy spectra under irradiation of X-rays from 55Fe. However, the measured gains of the MEMS μ-PICs were less than half of the values predicted in the simulations. We postulated that the gains of the MEMS μ-PICs are diminished by the effect of the silicon used as a semiconducting substrate.

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Du, Lin, Shuo Shi, Wei Gong, Jian Yang, Jia Sun et Feiyue Mao. « WAVELENGTH SELECTION OF HYPERSPECTRAL LIDAR BASED ON FEATURE WEIGHTING FOR ESTIMATION OF LEAF NITROGEN CONTENT IN RICE ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B1 (2 juin 2016) : 9–13. http://dx.doi.org/10.5194/isprs-archives-xli-b1-9-2016.

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Hyperspectral LiDAR (HSL) is a novel tool in the field of active remote sensing, which has been widely used in many domains because of its advantageous ability of spectrum-gained. Especially in the precise monitoring of nitrogen in green plants, the HSL plays a dispensable role. The exiting HSL system used for nitrogen status monitoring has a multi-channel detector, which can improve the spectral resolution and receiving range, but maybe result in data redundancy, difficulty in system integration and high cost as well. Thus, it is necessary and urgent to pick out the nitrogen-sensitive feature wavelengths among the spectral range. The present study, aiming at solving this problem, assigns a feature weighting to each centre wavelength of HSL system by using matrix coefficient analysis and divergence threshold. The feature weighting is a criterion to amend the centre wavelength of the detector to accommodate different purpose, especially the estimation of leaf nitrogen content (LNC) in rice. By this way, the wavelengths high-correlated to the LNC can be ranked in a descending order, which are used to estimate rice LNC sequentially. In this paper, a HSL system which works based on a wide spectrum emission and a 32-channel detector is conducted to collect the reflectance spectra of rice leaf. These spectra collected by HSL cover a range of 538 nm – 910 nm with a resolution of 12 nm. These 32 wavelengths are strong absorbed by chlorophyll in green plant among this range. The relationship between the rice LNC and reflectance-based spectra is modeled using partial least squares (PLS) and support vector machines (SVMs) based on calibration and validation datasets respectively. The results indicate that I) wavelength selection method of HSL based on feature weighting is effective to choose the nitrogen-sensitive wavelengths, which can also be co-adapted with the hardware of HSL system friendly. II) The chosen wavelength has a high correlation with rice LNC which can be retrieved by using PLS and SVMs regression methods.

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Du, Lin, Shuo Shi, Wei Gong, Jian Yang, Jia Sun et Feiyue Mao. « WAVELENGTH SELECTION OF HYPERSPECTRAL LIDAR BASED ON FEATURE WEIGHTING FOR ESTIMATION OF LEAF NITROGEN CONTENT IN RICE ». ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLI-B1 (2 juin 2016) : 9–13. http://dx.doi.org/10.5194/isprsarchives-xli-b1-9-2016.

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Hyperspectral LiDAR (HSL) is a novel tool in the field of active remote sensing, which has been widely used in many domains because of its advantageous ability of spectrum-gained. Especially in the precise monitoring of nitrogen in green plants, the HSL plays a dispensable role. The exiting HSL system used for nitrogen status monitoring has a multi-channel detector, which can improve the spectral resolution and receiving range, but maybe result in data redundancy, difficulty in system integration and high cost as well. Thus, it is necessary and urgent to pick out the nitrogen-sensitive feature wavelengths among the spectral range. The present study, aiming at solving this problem, assigns a feature weighting to each centre wavelength of HSL system by using matrix coefficient analysis and divergence threshold. The feature weighting is a criterion to amend the centre wavelength of the detector to accommodate different purpose, especially the estimation of leaf nitrogen content (LNC) in rice. By this way, the wavelengths high-correlated to the LNC can be ranked in a descending order, which are used to estimate rice LNC sequentially. In this paper, a HSL system which works based on a wide spectrum emission and a 32-channel detector is conducted to collect the reflectance spectra of rice leaf. These spectra collected by HSL cover a range of 538 nm – 910 nm with a resolution of 12 nm. These 32 wavelengths are strong absorbed by chlorophyll in green plant among this range. The relationship between the rice LNC and reflectance-based spectra is modeled using partial least squares (PLS) and support vector machines (SVMs) based on calibration and validation datasets respectively. The results indicate that I) wavelength selection method of HSL based on feature weighting is effective to choose the nitrogen-sensitive wavelengths, which can also be co-adapted with the hardware of HSL system friendly. II) The chosen wavelength has a high correlation with rice LNC which can be retrieved by using PLS and SVMs regression methods.

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Costara, Constantin. « On the spectral Nevanlinna–Pick problem ». Studia Mathematica 170, n^o 1 (2005) : 23–55. http://dx.doi.org/10.4064/sm170-1-2.

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Georgiou, Tryphon T., et Pramod P. Khargonekar. « Spectral Factorization and Nevanlinna–Pick Interpolation ». SIAM Journal on Control and Optimization 25, n^o 3 (mai 1987) : 754–66. http://dx.doi.org/10.1137/0325043.

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Bercovici, Hari, Ciprian Foias et Allen Tannenbaum. « On spectral tangential Nevanlinna-Pick interpolation ». Journal of Mathematical Analysis and Applications 155, n^o 1 (février 1991) : 156–76. http://dx.doi.org/10.1016/0022-247x(91)90033-v.

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Woodruff, Alan G., et Karen Choong. « Long-Term Outcomes and the Post-Intensive Care Syndrome in Critically Ill Children : A North American Perspective ». Children 8, n^o 4 (24 mars 2021) : 254. http://dx.doi.org/10.3390/children8040254.

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Advances in medical and surgical care for children in the pediatric intensive care unit (PICU) have led to vast reductions in mortality, but survivors often leave with newly acquired or worsened morbidity. Emerging evidence reveals that survivors of pediatric critical illness may experience a constellation of physical, emotional, cognitive, and social impairments, collectively known as the “post-intensive care syndrome in pediatrics” (PICs-P). The spectrum of PICs-P manifestations within each domain are heterogeneous. This is attributed to the wide age and developmental diversity of children admitted to PICUs and the high prevalence of chronic complex conditions. PICs-P recovery follows variable trajectories based on numerous patient, family, and environmental factors. Those who improve tend to do so within less than a year of discharge. A small proportion, however, may actually worsen over time. There are many gaps in our current understanding of PICs-P. A unified approach to screening, preventing, and treating PICs-P-related morbidity has been hindered by disparate research methodology. Initiatives are underway to harmonize clinical and research priorities, validate new and existing epidemiologic and patient-specific tools for the prediction or monitoring of outcomes, and define research priorities for investigators interested in long-term outcomes.

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Сафин, Ф. М., et В. Г. Маслов. « Об интерпретации спектров фотохимически индуцированного кругового дихроизма полупроводниковых нанокристаллов ». Журнал технической физики 128, n^o 6 (2020) : 722. http://dx.doi.org/10.21883/os.2020.06.49402.57-20.

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An approach to the analysis and interpretation of the spectra of photoinduced circular dichroism (PICD) of semiconductor nanocrystals, in particular quantum dots, based on their comparison with the spectra of magnetic circular dichroism (MCD), is proposed. It was shown that the MCD and PICD spectra have similar features. The values of parameters similar to the known parameters A and B of the MCD spectra characterizing the splitting and mixing of states were determined from the PICD spectra.

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Chiang, C. H., et C. C. Cheng. « Detecting Rebars and Tubes Inside Concrete Slabs Using Continuous Wavelet Transform of Elastic Waves ». Journal of Mechanics 20, n^o 4 (décembre 2004) : 297–302. http://dx.doi.org/10.1017/s172771910000352x.

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AbstractA typical problem of elastic wave methods, such as the impact echo method, is due to peak detection based solely on amplitude spectrum. Current study aims to improve the feature identification of impact-echo signals obtained from buried objects in concrete slabs. Steel rebar, steel tubes, and PVC tubes embedded in a concrete slab are tested. Numerical simulations are carried out based on models constructed using the finite element method. The received signals, both experimental and simulated, are analyzed using both fast Fourier transform and continuous wavelet transform (CWT). The amplitude spectra can only provide global information and lose some important local effects of frequency components. This can be resolved by continuous wavelet transform for preserving the transient effects in the frequency domain. Localized spectral contents are analyzed and thus better understanding is achieved for the impulse responses due to different objects below the surface of the concrete slab. Features related to steel rebar, PVC and steel tubes are readily identified in the coefficient plot of wavelet coefficients. Multiple reflections and vibration modes related to various characteristics of wave propagation in the concrete slab can now be decomposed into distinctive frequency bands with different time durations. The result of CWT provides more information and is easier to interpret than that of the spectral analysis. The same peak frequency found in the amplitude spectrum is now distinguishable between PVC and steel tubes at a resolution of 0.1kHz or better. Such findings provide a more effective way to pick up true rebar signals using the impact-echo method.

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Campbell, P. E. K., K. F. Huemmrich, E. M. Middleton, J. Alfieri, C. van der Tol et C. S. R. Neigh. « USING DESIS AND EO-1 HYPERION REFLECTANCE TIME SERIES FOR THE ASSESSMENT OF VEGETATION TRAITS AND GROSS PRIMARY PRODUCTION (GPP) ». International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XLVI-1/W1-2021 (11 février 2022) : 1–8. http://dx.doi.org/10.5194/isprs-archives-xlvi-1-w1-2021-1-2022.

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Abstract. This study evaluates the potential of the DLR Earth Sensing Imaging Spectrometer (DESIS) visible through near-infrared (VNIR) surface reflectance to augment the EO-1 Hyperion full spectrum (400–2400 nm) reflectance collection over vegetated flux sites, to extend the reflectance time series up to the present. We compared DESIS and Hyperion surface reflectance magnitude and variability at a pseudo-invariant site (PICS) and a vegetated flux site (VFS). VNIR reflectance magnitudes between the two sensors did not significantly differ at the PICS. However, DESIS variability was higher, likely due to differences in the data acquisition time and observation geometry. Using empirical and biophysical models, both DESIS and Hyperion datasets captured the seasonal variations in gross primary production (GPP) and canopy bio-physical parameters such as chlorophyll content, leaf area index (LAI), and senescent material at the VFS. Differences in the magnitudes of the bio-physical parameters were observed, likely due to the differences in the sensors spectral range and resolution. Using together VNIR reflectance from EO-1 Hyperion and DESIS convolved to Hyperion spectral resolution to estimate canopy chlorophyll and GPP, we demonstrate that combining historic and current space-based reflectance data in a common multi-sensor approach is feasible. This is of importance for extending the reflectance record established with EO-1 Hyperion to provide continuity with the current orbital instruments (e.g., DESIS/ISS, PRISMA/ASI) and the forthcoming NASA Surface Biology and Geology (SBG), ESA CHIME and DLR EnMAP satellite missions, which is of key importance for comparisons of current and past trends in the seasonal dynamics of vegetation traits and photosynthetic function.

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Son, ChangHee, Subin Jeong, Sangyeop Lee, Placid M. Ferreira et Seok Kim. « Tunable Adhesion of Shape Memory Polymer Dry Adhesive Soft Robotic Gripper via Stiffness Control ». Robotics 12, n^o 2 (17 avril 2023) : 59. http://dx.doi.org/10.3390/robotics12020059.

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A shape memory polymer (SMP) has been intensively researched in terms of its exceptional reversible dry adhesive characteristics and related smart adhesive applications over the last decade. However, its unique adhesive properties have rarely been taken into account for other potential applications, such as robotic pick-and-place, which might otherwise improve robotic manipulation and contribute to the related fields. This work explores the use of an SMP to design an adhesive gripper that picks and places a target solid object employing the reversible dry adhesion of an SMP. The numerical and experimental results reveal that an ideal compositional and topological SMP adhesive design can significantly improve its adhesion strength and reversibility, leading to a strong grip force and a minimal release force. Next, a radially averaged power spectrum density (RAPSD) analysis proves that active heating and cooling with a thermoelectric Peltier module (TEC) substantially enhances the conformal adhesive contact of an SMP. Based on these findings, an adhesive gripper is designed, fabricated, and tested. Remarkably, the SMP adhesive gripper interacts not only with flat and smooth dry surfaces, but also moderately rough and even wet surfaces for pick-and-place, showing high adhesion strength (>2 standard atmospheres) which is comparable to or exceeds those of other single-surface contact grippers, such as vacuum, electromagnetic, electroadhesion, and gecko grippers. Lastly, the versatility and utility of the SMP adhesive gripper are highlighted through diverse pick-and-place demonstrations. Associated studies on physical mechanisms, SMP adhesive mechanics, and thermal conditions are also presented.

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Raut, Bipin, Morakot Kaewmanee, Amit Angal, Xiaoxiong Xiong et Dennis Helder. « Empirical Absolute Calibration Model for Multiple Pseudo-Invariant Calibration Sites ». Remote Sensing 11, n^o 9 (9 mai 2019) : 1105. http://dx.doi.org/10.3390/rs11091105.

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This work extends an empirical absolute calibration model initially developed for the Libya 4 Pseudo-Invariant Calibration Site (PICS) to five additional Saharan Desert PICS (Egypt 1, Libya 1, Niger 1, Niger 2, and Sudan 1), and demonstrates the efficacy of the resulting models at predicting sensor top-of-atmosphere (TOA) reflectance. It attempts to generate absolute calibration models for these PICS that have an accuracy and precision comparable to or better than the current Libya 4 model, with the intent of providing additional opportunities for sensor calibration. In addition, this work attempts to validate the general applicability of the model to other sites. The method uses Terra Moderate Resolution Imaging Spectroradiometer (MODIS) as the reference radiometer and Earth Observing-1 (EO-1) Hyperion image data to provide a representative hyperspectral reflectance profile of the PICS. Data from a region of interest (ROI) in an “optimal region” of 3% temporal, spatial, and spectral stability within the PICS are used for developing the model. The developed models were used to simulate observations of the Landsat 7 (L7) Enhanced Thematic Mapper Plus (ETM+), Landsat 8 (L8) Operational Land Imager (OLI), Sentinel 2A (S2A) MultiSpectral Instrument (MSI) and Sentinel 2B (S2B) MultiSpectral Instrument (MSI) from their respective launch date through 2018. The models developed for the Egypt 1, Libya 1 and Sudan 1 PICS have an estimated accuracy of approximately 3% and precision of approximately 2% for the sensors used in the study, comparable to the current Libya 4 model. The models developed for the Niger 1 and Niger 2 sites are significantly less accurate with similar precision.

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Agler, J., et N. J. Young. « The two-point spectral Nevanlinna-Pick problem ». Integral Equations and Operator Theory 37, n^o 4 (décembre 2000) : 375–85. http://dx.doi.org/10.1007/bf01192826.

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Quast, Ralf, Ralf Giering, Yves Govaerts, Frank Rüthrich et Rob Roebeling. « Climate Data Records from Meteosat First Generation Part II : Retrieval of the In-Flight Visible Spectral Response ». Remote Sensing 11, n^o 5 (26 février 2019) : 480. http://dx.doi.org/10.3390/rs11050480.

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How can the in-flight spectral response functions of a series of decades-old broad band radiometers in Space be retrieved post-flight? This question is the key to developing Climate Data Records from the Meteosat Visible and Infrared Imager on board the Meteosat First Generation (MFG) of geostationary satellites, which acquired Earth radiance images in the Visible (VIS) broad band from 1977 to 2017. This article presents a new metrologically sound method for retrieving the VIS spectral response from matchups of pseudo-invariant calibration site (PICS) pixels with datasets of simulated top-of-atmosphere spectral radiance used as reference. Calibration sites include bright desert, open ocean and deep convective cloud targets. The absolute instrument spectral response function is decomposed into generalised Bernstein basis polynomials and a degradation function that is based on plain physical considerations and able to represent typical chromatic ageing characteristics. Retrieval uncertainties are specified in terms of an error covariance matrix, which is projected from model parameter space into the spectral response function domain and range. The retrieval method considers target type-specific biases due to errors in, e.g., the selection of PICS target pixels and the spectral radiance simulation explicitly. It has been tested with artificial and well-comprehended observational data from the Spinning Enhanced Visible and Infrared Imager on-board Meteosat Second Generation and has retrieved meaningful results for all MFG satellites apart from Meteosat-1, which was not available for analysis.

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COSTARA, CONSTANTIN. « THE $2\times 2$ SPECTRAL NEVANLINNA–PICK PROBLEM ». Journal of the London Mathematical Society 71, n^o 03 (24 mai 2005) : 684–702. http://dx.doi.org/10.1112/s002461070500640x.

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Agler, Jim, et N. J. Young. « The two-by-two spectral Nevanlinna-Pick problem ». Transactions of the American Mathematical Society 356, n^o 2 (22 septembre 2003) : 573–85. http://dx.doi.org/10.1090/s0002-9947-03-03083-6.

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Mazurenko, Yu T., S. E. Putilin, V. L. Bogdanov, G. V. Lukomskij, M. V. Smirnov et Yu A. Cherkasov. « Spectral holography of pico- and nanosecond optical pulses ». Optics & ; Laser Technology 28, n^o 4 (juin 1996) : 285–90. http://dx.doi.org/10.1016/0030-3992(95)00095-x.

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Bacour, Cédric, Xavier Briottet, François-Marie Bréon, Françoise Viallefont-Robinet et Marc Bouvet. « Revisiting Pseudo Invariant Calibration Sites (PICS) Over Sand Deserts for Vicarious Calibration of Optical Imagers at 20 km and 100 km Scales ». Remote Sensing 11, n^o 10 (15 mai 2019) : 1166. http://dx.doi.org/10.3390/rs11101166.

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In-flight assessment of the radiometric performances of space-borne instruments can be achieved by means of vicarious calibration over Pseudo-Invariant Calibration Sites (PICS). PICS are chosen for the high temporal stability of their surface optical properties combined with a high spatial homogeneity. A first list of the main desert PIC sites was identified 20 years ago for the calibration of medium/coarse spatial resolution instruments in the solar spectral range (400–2500 nm). They are located in the Saharan desert and in the Arabian Peninsula. Six of them have since been endorsed by the CEOS/WGCV/IVOS as reference Calibration/Validation test sites. In this study, we have revisited the list of desert PIC sites at the global scale with the aim of (1) assessing if these twenty PICS are still “optimal”, in terms of temporal stability and spatial uniformity, and using up-to-date multi-spectral remote sensing data, and (2) identifying new calibration sites distributed over other areas of the world. We verified that the original sites remain very relevant, although alternate locations in their close vicinity have slightly better characteristics. We proposed four additional targets with similar characteristics, some of which may offer easier logistical access. In order to support radiative transfer simulations of satellite sensor measurements over the sites, we assessed the abilities of several semi-empirical models to reproduce the spectro-directional signatures of six IVOS sites and the four new candidate sites, and we derived climatologies of the main atmospheric properties (trace gas column load and aerosol optical depth).

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Chaity, Manisha Das, Morakot Kaewmanee, Larry Leigh et Cibele Teixeira Pinto. « Hyperspectral Empirical Absolute Calibration Model Using Libya 4 Pseudo Invariant Calibration Site ». Remote Sensing 13, n^o 8 (15 avril 2021) : 1538. http://dx.doi.org/10.3390/rs13081538.

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The objective of this paper is to find an empirical hyperspectral absolute calibration model using Libya 4 pseudo invariant calibration site (PICS). The approach involves using the Landsat 8 (L8) Operational Land Imager (OLI) as the reference radiometer and using Earth Observing One (EO-1) Hyperion, with a spectral resolution of 10 nm as a hyperspectral source. This model utilizes data from a region of interest (ROI) in an “optimal region” of 3% temporal, spatial, and spectral stability within the Libya 4 PICS. It uses an improved, simple, empirical, hyperspectral Bidirectional Reflectance Distribution function (BRDF) model accounting for four angles: solar zenith and azimuth, and view zenith and azimuth angles. This model can perform absolute calibration in 1 nm spectral resolution by predicting TOA reflectance in all existing spectral bands of the sensors. The resultant model was validated with image data acquired from satellite sensors such as Landsat 7, Sentinel 2A, and Sentinel 2B, Terra MODIS, Aqua MODIS, from their launch date to 2020. These satellite sensors differ in terms of the width of their spectral bandpass, overpass time, off-nadir viewing capabilities, spatial resolution, and temporal revisit time, etc. The result demonstrates the efficacy of the proposed model has an accuracy of the order of 3% with a precision of about 3% for the nadir viewing sensors (with view zenith angle up to 5°) used in the study. For the off-nadir viewing satellites with view zenith angle up to 20°, it can have an estimated accuracy of 6% and precision of 4%.

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Beltz, Hayley, Emily Rauscher, Eliza M. R. Kempton, Isaac Malsky, Grace Ochs, Mireya Arora et Arjun Savel. « Magnetic Drag and 3D Effects in Theoretical High-resolution Emission Spectra of Ultrahot Jupiters : the Case of WASP-76b ». Astronomical Journal 164, n^o 4 (15 septembre 2022) : 140. http://dx.doi.org/10.3847/1538-3881/ac897b.

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Abstract Ultrahot Jupiters are ideal candidates to explore with high-resolution emission spectra. Detailed theoretical studies are necessary to investigate the range of spectra that we can expect to see from these objects throughout their orbit, because of the extreme temperature and chemical longitudinal gradients that exist across their dayside and nightside regions. Using previously published 3D general circulation models of WASP-76b with different treatments of magnetic drag, we postprocess the 3D atmospheres to generate high-resolution emission spectra for two wavelength ranges, throughout the planet’s orbit. We find that the high-resolution emission spectra vary strongly as a function of phase, at times showing emission features, absorption features, or both, which are a direct result of the 3D structure of the planet. At phases exhibiting both emission and absorption features, the Doppler shift differs in direction between the two spectral features, making them differentiable, instead of canceling each other out. Through the use of cross correlation, we find different patterns in net Doppler shift for models with different treatments of drag: the nightside spectra show opposite signs in their Doppler shift, while the dayside phases display a reversal in the trend of net shift with phase. Finally, we caution researchers against using a single spectral template throughout the planet’s orbit; this can bias the corresponding net Doppler shift returned, as it can pick up on a bright region on the edge of the planet disk that is highly redshifted or blueshifted.

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Liu, Chun Sheng, Chun Ping Ren et Fei Han. « Study on Time-Frequency Spectrum Characteristic of Dynamic Cutting Load Based on Wavelet Regularization ». Applied Mechanics and Materials 577 (juillet 2014) : 196–200. http://dx.doi.org/10.4028/www.scientific.net/amm.577.196.

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Aimed at investigating time-frequency spectrum characteristic laws of conical pick rotary crushing coal and rock, this paper determines the mapping relationship of load spectrum between energy distribution and cutting process, and achieves quantitative reconstruction of the cutting coal and rock load spectrum. The experimental load spectrum is used as the object of research, utilizing wavelet regularization method to establish load spectrum reconstruction model of the pick cutting coal and rock, which will achieve its reconstruction load spectrum, so that it will discuss the variation of reconstruction load spectrum. Finally, it determines energy distribution of the load spectrum in different frequency band. The results show that the experimental load spectrum energy increases with the increasing of the cutting cycle number, and then decreases, so the characteristics of energy can characterize the cutting process. Energy of reconstruction load spectrum is mainly distributed in the low frequency range, which focuses on 1Hz and 3Hz, the amplitude of the high frequency energy is smaller than others.

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Hu, Xiuqing, Ling Wang, Junwei Wang, Lingli He, Lin Chen, Na Xu, Bingcheng Tao, Lu Zhang, Peng Zhang et Naimeng Lu. « Preliminary Selection and Characterization of Pseudo-Invariant Calibration Sites in Northwest China ». Remote Sensing 12, n^o 16 (5 août 2020) : 2517. http://dx.doi.org/10.3390/rs12162517.

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Pseudo-invariant calibration sites (PICS) have been used for the radiometric calibration and stability monitoring of satellite optical sensors. Several stable PICS, such as those in the Sahara Desert in North Africa, were selected for the vicarious calibration of earth remote sensing satellites. However, the selection procedure of PICSs in the whole of Northwest China has not been fully explored before. This paper presents a novel technique for selecting PICS in Northwest China by combined using the coefficient of variation (CV) and the iteratively reweighted multivariate alteration detection (IR-MAD) technique. IR-MAD, which calculates the differences between two multispectral N-band images from the same scene acquired at different times, is used to identify no-change pixels (NCPs) of the scene through one image pair. The NCPs from IR-MAD using the long-term data of FY-3 visible infrared radiometer (VIRR) and aqua Moderate Resolution Imaging Spectroradiometer (MODIS) were aggregated into the contiguously stable sites. The traditional spatial uniformity and temporal stability from MODIS surface products were used to select the potential PICS. By combining the results of both methods, over thirty PICSs with a wider brightness range of the scene types were selected. To confirm and characterize these PICSs over Northwest China, Landsat operational land imager (OLI) high-spatial-resolution images were used to check the spatial uniformity of the selected site to determine the specific location and the size of these sites. Additionally, the surface spectral reflectance and bidirectional reflectance distribution function (BRDF) were obtained from the field campaign at Chaidamu Basin, 2018. To demonstrate the practical utilization and usability of these PICSs, they were employed in the multi-site top of atmosphere (TOA) reflectance simulation to validate the operational calibration performance of Aqua/MODIS and FY-3D/MERSI-II (Medium Resolution Spectral Imager II). The simulation results showed good consistency compared with the observations from both MODIS and MERSI-II, with a relative bias and root mean square error (RMSE) of <5% and <0.05%, respectively. These sites provide prospects for multi-site vicarious calibrations of solar reflective bands, which may help to evaluate or characterize instrumental nonlinear responses using a wider signal dynamic from the sites in different seasons.

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Yu, Zhicong, Shuai Leng, Zhoubo Li et Cynthia H. McCollough. « Spectral prior image constrained compressed sensing (spectral PICCS) for photon-counting computed tomography ». Physics in Medicine and Biology 61, n^o 18 (23 août 2016) : 6707–32. http://dx.doi.org/10.1088/0031-9155/61/18/6707.

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Kong, Huihua, Xiaoxue Lei, Lei Lei, Yanbo Zhang et Hengyong Yu. « Spectral CT Reconstruction Based on PICCS and Dictionary Learning ». IEEE Access 8 (2020) : 133367–76. http://dx.doi.org/10.1109/access.2020.3010228.

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Patil, Basavaraj, Savita Patil et Harsha S. « Spectrum of Acute Kidney Injury and its Clinical Profile and Outcome in Children Admitted to PICU ». Pediatric Education and Research 6, n^o 2 (2018) : 90–94. http://dx.doi.org/10.21088/per.2321.1644.6218.8.

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Pietrzak, Ryszard, et Roman Szatanik. « The Effect of Impact Pressure on Positron Lifetime in Ultra High Molecular Weight Polyethylene (PE-UHMW)Chirulen®1120 ». Materials Science Forum 666 (décembre 2010) : 85–88. http://dx.doi.org/10.4028/www.scientific.net/msf.666.85.

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The paper presents the results of investigations of the effect of impact pressure (in the range of both elastic and plastic deformations) on the parameters of the positron lifetime spectra in PE-UMHW polymer known under the trade mark Chirulen1120. The changes in the long-living component of the positron lifetime spectrum, connected with the annihilation of o-Ps in the pick-off process, are analyzed in dependence on the impact energy. The impact duration in the Charpy’s tests depending on the impact energy was measured, too. The dependencies of the radius of the volume of empty spaces in which the positronium annihilates, on the impact pressure were determined applying the Eldrup-Tao model.

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Belikova, Juliia. « THE RELATIONSHIP OF THE RATIO TAURINE/ALANINE IN SERUM AND INDICATORS OF HEART RATE VARIABILITY IN PATIENTS WITH POSTINFARCTION CARDIOSCLEROSIS AND DIABETES MELLITUS TYPE 2 ». Ukrainian Scientific Medical Youth Journal, n^o 1(109) (5 avril 2019) : 6–10. http://dx.doi.org/10.32345/usmyj.1(109).2019.6-10.

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The aim of the article : to determine the relationship of the ratio taurine/alanine (Tau/Ala) serum indicators of heart rate variability (HRV) in patients with postinfarction cardiosclerosis (PICS) and diabetes mellitus type 2 (DM 2). Materials and methods: we examined 87 patients with PICS and DM 2 – 50 women and 37 men, median age of the patients was 65.2 years (microtile interval 61-69 years). Amino acids were determined and the ratio between them. According to the results of Holter ECG monitoring (of HMCG) evaluated HRV. Results: in patients with PICS compared with healthy individuals observed a significant decrease in the blood levels of Tau/Ala (at 51.01%, p<0.001). The presence of comorbid diabetes is accompanied by more significant decrease in Tau/Ala (for the accounting period 82.22%, p<0.001) compared to healthy individuals. Between Tau/Ala and SDNN, LF, TP, VLF power of communication has been high, between Tau/Ala and RMSSD, HF, pNN 50.%, ULF, – moderate strength. Conclusions: the lower values of Tau/Ala in the blood of patients Pxs diabetes compared with patients without disorders of carbohydrate metabolism, accompanied by a decrease in spectral and temporal parameters of HRV, but that does not mean a causal relationship, may be associated with pathogenetic mechanisms of disorders of carbohydrate metabolism and requires further research.

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Alexander, D. D., S. E. Lunde et D. E. Berger. « Gastrointestinal Tract Symptomatology in Adults with Pica and Autism ». Autism and Developmental Disorders 18, n^o 4 (2020) : 3–12. http://dx.doi.org/10.17759/autdd.2020180401.

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This study investigated pica behavior in those with and without autism in relation to gastrointestinal (GI) tract symptomatology and disease. A chart review of 64 residential adults with developmental disabilities indicated that individuals with pica had more GI tract diseases, and those with autism and pica had a higher rate of GI diseases compared to those with autism and no pica behavior. These data suggest that individuals with both autism and pica disorders may be a phenotypic subgroup in the autistic spectrum characterized by GI symptomatology, requiring a clinical algorithm for categorization and effective treatment. A behavior-analytic model is presented that conceptualizes pica as part of a chain of events that begins with exploratory behavior and culminates in GI symptomatology and disease. Issues of sensory processing are addressed within this model. Individuals exhibiting pica may benefit from gastrointestinal evaluation, including assessment of the microbiome, and, if indicated, microbiota transfer therapy to

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Fajardo Rueda, Juliana, Larry Leigh, Cibele Teixeira Pinto, Morakot Kaewmanee et Dennis Helder. « Classification and Evaluation of Extended PICS (EPICS) on a Global Scale for Calibration and Stability Monitoring of Optical Satellite Sensors ». Remote Sensing 13, n^o 17 (24 août 2021) : 3350. http://dx.doi.org/10.3390/rs13173350.

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Historically stable areas across North Africa, known as pseudo invariant calibration sites (PICS), have been used as targets for the calibration and monitoring of optical satellite sensors. However, two major drawbacks exist for these sites: first is the dependency on a single location to be always invariant, and second is the limited amount of observation achieved using these sites. As a result, longer time periods are necessary to construct a dense dataset to assess the radiometric performance of on-orbit optical sensors and confirm that the change detected is sensor-specific rather than site-specific. This work presents a global land cover classification to obtain an extended pseudo invariant calibration site (EPICS) on a global scale using Landsat-8 Operational Land Imager (OLI) data. This technique provides multiple calibration sites across the globe, allowing for the building of richer datasets in a shorter time frame compared to the traditional approach (PICS), with the advantage of assessing the calibration and stability of the sensors faster, detecting possible changes sooner and correcting them accordingly. This work identified 23 World Reference System two (WRS-2) path/row locations around the globe as part of the global EPICS. These EPICS have the advantage of achieving multiple observations per day, with similar spectral characteristics compared to traditional PICS, while still producing a temporal coefficient of variation (ratio of temporal standard deviation and temporal mean) less than 4% for all bands, with some as low as 2.7%.

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Nikolov, Nikolai, Peter Pflug et Pascal J. Thomas. « Spectral Nevanlinna-Pick and Caratheodory-Fejer problems for $n\geq3$ ». Indiana University Mathematics Journal 60, n^o 3 (2011) : 883–94. http://dx.doi.org/10.1512/iumj.2011.60.4310.

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Baribeau, Line, et Adama S. Kamara. « A Refined Schwarz Lemma for the Spectral Nevanlinna-Pick Problem ». Complex Analysis and Operator Theory 8, n^o 2 (16 mai 2013) : 529–36. http://dx.doi.org/10.1007/s11785-013-0306-6.

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Wang, Shaoyu, Weiwen Wu, Jian Feng, Fenglin Liu et Hengyong Yu. « Low-dose spectral CT reconstruction based on image-gradient L0-norm and adaptive spectral PICCS ». Physics in Medicine & ; Biology 65, n^o 24 (5 décembre 2020) : 245005. http://dx.doi.org/10.1088/1361-6560/aba7cf.

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Härer, L., M. L. Parker, A. Joyce, Z. Igo, W. N. Alston, F. Fürst, A. P. Lobban, G. A. Matzeu et J. N. Reeves. « Modelling X-ray RMS spectra II : the ultrafast outflow of PDS 456 ». Monthly Notices of the Royal Astronomical Society 500, n^o 4 (17 novembre 2020) : 4506–13. http://dx.doi.org/10.1093/mnras/staa3559.

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ABSTRACT We present an improved model for excess variance spectra describing ultrafast outflows and successfully apply it to the luminous ($L_{\rm bol}\sim 10^{47}\mathrm{erg}\, \mathrm{s}^{-1}$) low-redshift (z = 0.184) quasar Pico del Dias Survey (PDS) 456. The model is able to account well for the broadening of the spike-like features of these outflows in the excess variance spectrum of PDS 456, by considering two effects: a correlation between the outflow velocity and the logarithmic X-ray flux and intrinsic Doppler broadening with $v_\mathrm{int} = 10^4\, \mathrm{km}\, \mathrm{s}^{-1}$. The models were generated by calculating the fractional excess variance of count spectra from a Monte Carlo simulation. We find evidence that the outflow in PDS 456 is structured, i.e. there exist two or more layers with outflow velocities $0.27\!-\!0.30\, c$, $0.41\!-\!0.49\, c$, and $0.15\!-\!0.20\, c$ for a possible third layer, which agrees well with the literature. We discuss the prospects of generally applicable models for excess variance spectra for detecting ultrafast outflows and investigating their structure. We provide an estimate for the strength of the correlation between the outflow velocity and the logarithmic X-ray flux and investigate its validity.

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Lou, Bin Chao. « W722 Lathe of Fault Detection and Diagnosis ». Advanced Materials Research 328-330 (septembre 2011) : 672–76. http://dx.doi.org/10.4028/www.scientific.net/amr.328-330.672.

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Shanghai YinChaoChang a W722 lathe processing of metal parts, workpiece surface machining quality external circular no obvious problem, and the machine's vibration is small. But in the processing of main parts - rubber managers stamped drum, workpiece surface appear periodically outside round the chatter marks, general examination of hard to find the failure causes of machine tools. We adopt mechanical fault diagnosis technology to find fault location and fault machine of the machine, first nature of transmission chain of analysis and calculation, obtains each train parts, use characteristic frequency JGZY - 1C type mechanical failure diagnosis in the daily use of the lathe spindle 560 turn/points and 735 turn/cent two kinds of rotating speed sensor separately carried on the test, pick up the spindle box, respectively go knife box and slip board box to collect the vibration signal of signal filtered (stationary fault) and demodulation spectral analysis, got a lot of lathe vibration signal spectrum diagram. And the calculated value and vibration signal spectrum diagram compares analysis, find out the fault location and machine determine the fault properties. Replace the corresponding gear and bearing, fault phenomena disappear.

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Morozov, Igor B., et Alan Levander. « Depth image focusing in traveltime map‐based wide‐angle migration ». GEOPHYSICS 67, n^o 6 (novembre 2002) : 1903–12. http://dx.doi.org/10.1190/1.1527090.

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Wide‐aperture, prestack depth migration requires application of challenging and time‐consuming velocity analysis and depth focusing, collectively referred to here as depth focusing. We present an approach to depth focusing using (1) a detailed starting velocity model obtained by a 1‐D transformation of the first‐arrival times, followed iteratively by (2) interactive analysis of the common‐image gathers, (3) computation of coherency attributes of the wavefield in the depth domain, and (4) 2‐D traveltime tomography to update the background velocity model. We employ two interactive method of migration velocities refinement. In the first method (similar to the common‐midpoint velocity spectrum approach), residual velocity updates are picked directly from the common‐image gathers. In another method (analogous to the common velocity stacks), we pick the velocity updates from the areas of maximum coherency in depth sections that are migrated using rescaled traveltime maps. Both types of migration velocity picks, optionally combined with the first arrivals, are inputs for a 2‐D traveltime inversion scheme that uses either the infinite‐frequency or a finite‐bandwidth approximation. This flexible and versatile depth focusing approach is implemented for several prestack depth migration algorithms and illustrated on an application to a real, ultrashallow seismic data set. The technique resolves overburden velocity variations and facilitates reliable high‐resolution reflection imaging of a paleochannel that was the target of the study.

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Chalov, S. V., et H. J. Fahr. « Different solar wind types reflected in pick-up ion spectral signatures ». Astronomy & ; Astrophysics 384, n^o 1 (mars 2002) : 299–302. http://dx.doi.org/10.1051/0004-6361:20011825.

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Battaglia, Alessandro, Pavlos Kollias, Ranvir Dhillon, Katia Lamer, Marat Khairoutdinov et Daniel Watters. « Mind the gap – Part 2 : Improving quantitative estimates of cloud and rain water path in oceanic warm rain using spaceborne radars ». Atmospheric Measurement Techniques 13, n^o 9 (15 septembre 2020) : 4865–83. http://dx.doi.org/10.5194/amt-13-4865-2020.

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Abstract. The intrinsic small spatial scales and low-reflectivity structure of oceanic warm precipitating clouds suggest that millimeter spaceborne radars are best suited to providing quantitative estimates of cloud and rain liquid water paths (LWPs). This assertion is based on their smaller horizontal footprint; high sensitivities; and a wide dynamic range of path-integrated attenuations associated with warm-rain cells across the millimeter wavelength spectrum, with diverse spectral responses to rain and cloud partitioning. State-of-the-art single-frequency radar profiling algorithms of warm rain seem to be inadequate because of their dependence on uncertain assumptions about the rain–cloud partitioning and because of the rain microphysics. Here, high-resolution cloud-resolving model simulations for the Rain in Cumulus over the Ocean field study and a spaceborne forward radar simulator are exploited to assess the potential of existing and future spaceborne radar systems for quantitative warm-rain microphysical retrievals. Specifically, the detrimental effects of nonuniform beam filling on estimates of path-integrated attenuation (PIA), the added value of brightness temperature (TB) derived adopting radiometric radar modes, and the performances of multifrequency PIA and/or TB combinations when retrieving liquid water paths partitioned into cloud (c-LWPs) and rain (r-LWPs) are assessed. Results show that (1) Ka- and W-band TB values add useful constraints and are effective at lower LWPs than the same-frequency PIAs; (2) matched-beam combined TB values and PIAs from single-frequency or multifrequency radars can significantly narrow down uncertainties in retrieved cloud and rain liquid water paths; and (3) the configuration including PIAs, TB values and near-surface reflectivities for the Ka-band–W-band pairs in our synthetic retrieval can achieve an RMSE of better than 30 % for c-LWPs and r-LWPs exceeding 100 g m−2.

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Takenaka, Mitsuru, Ziqiang Zhao, Chong Pei Ho, Takumi Fujigaki, Tipat Piyapatarakul, Yuto Miyatake, Rui Tang, Kasidit Toprasertpong et Shinichi Takagi. « Ge-on-insulator Platform for Mid-infrared Photonic Integrated Circuits ». ECS Transactions 109, n^o 4 (30 septembre 2022) : 47–58. http://dx.doi.org/10.1149/10904.0047ecst.

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Since mid-infrared (MIR) wavelengths have a great potential for optical communication, sensing, and quantum information, Si-based MIR photonic integrated circuits (PICs) have been developed by leveraging Si photonics technology for near-infrared wavelengths. However, the transparency wavelength window of Si is from 1.2 μm to 8 μm, limiting the available wavelengths in the MIR spectrum. Ge is emerging as a waveguide material to overcome this difficulty because Ge is transparent in the entire MIR spectrum. We have developed a Ge-on-insulator (GeOI) platform for MIR integrated photonics. The strong optical confinement in a GeOI waveguide enables an ultracompact MIR PIC. Using wafer bonding and Smart-cut, a GeOI wafer was successfully fabricated. As a result, we have demonstrated various Ge passive devices, thermo-optic phase shifters, modulators, and photodetectors on a GeOI platform.

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Shrestha, Mahesh, Nahid Hasan, Larry Leigh et Dennis Helder. « Derivation of Hyperspectral Profile of Extended Pseudo Invariant Calibration Sites (EPICS) for Use in Sensor Calibration ». Remote Sensing 11, n^o 19 (29 septembre 2019) : 2279. http://dx.doi.org/10.3390/rs11192279.

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Reference of Earth-observing satellite sensor data to a common, consistent radiometric scale is an increasingly critical issue as more of these sensors are launched; such consistency can be achieved through radiometric cross-calibration of the sensors. A common cross-calibration approach uses a small set of regions of interest (ROIs) in established Pseudo-Invariant Calibration Sites (PICS) mainly located throughout North Africa. The number of available cloud-free coincident scene pairs available for these regions limits the usefulness of this approach; furthermore, the temporal stability of most regions throughout North Africa is not known, and limited hyperspectral information exists for these regions. As a result, it takes more time to construct an appropriate cross-calibration dataset. In a previous work, Shrestha et al. presented an analysis identifying 19 distinct “clusters” of spectrally similar surface cover that are widely distributed across North Africa, with the potential to provide near-daily cloud-free imaging for most sensors. This paper proposes a technique to generate a representative hyperspectral profile for these clusters. The technique was used to generate the profile for the cluster containing the largest number of aggregated pixels. The resulting profile was found to have temporal uncertainties within 5% across all the spectral regions. Overall, this technique shows great potential for generation of representative hyperspectral profiles for any North African cluster, which could allow the use of the entire North Africa Saharan region as an extended PICS (EPICS) dataset for sensor cross-calibration. This should result in the increased temporal resolution of cross-calibration datasets and should help to achieve a cross-calibration quality similar to that of individual PICS in a significantly shorter time interval. It also facilitates the development of an EPICS based absolute calibration model, which can improve the accuracy and consistency in simulating any sensor’s top of atmosphere (TOA) reflectance.

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Liu, Bin, Chang-Hong Wang, Wei Li et Zhuo Li. « Robust Controller Design Using the Nevanlinna-Pick Interpolation in Gyro Stabilized Pod ». Discrete Dynamics in Nature and Society 2010 (2010) : 1–16. http://dx.doi.org/10.1155/2010/569850.

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The sensitivity minimization of feedback system is solved based on the theory of Nevanlinna-Pick interpolation with degree constraint without using weighting functions. More details of the dynamic characteristic of second-order system investigated, which is determined by the location of spectral zeroes, the upper boundγofS, the length of the spectral radius and the additional interpolation constraints. And the guidelines on how to tune the design parameters are provided. Gyro stabilized pod as a typical tracking system is studied, which is based on the typical structure of two-axis and four-frame. The robust controller is designed based on Nevanlinna-Pick interpolation with degree constraint. When both friction of LuGre model and disturbance exist, the closed-loop system has stronger disturbance rejection ability and high tracking precision. Numerical examples illustrate the potential of the method in designing robust controllers with relatively low degrees.

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Wiertel, Marek, Zbigniew Surowiec, Mieczysław Budzyński et Wojciech Gac. « Study on the effect of atmospheric gases adsorbed in MnFe2O4/MCM-41 nanocomposite on ortho-positronium annihilation ». Nukleonika 60, n^o 4 (1 décembre 2015) : 783–87. http://dx.doi.org/10.1515/nuka-2015-0141.

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Abstract In this paper, results of positron annihilation lifetime spectroscopy (PALS) studies of MnFe2O4/MCM-41 nanocomposites in N2 and O2 atmosphere have been presented. In particular, the influence of manganese ferrite loading and gas filling on pick-off ortho-positronium (o-Ps) annihilation processes in the investigated samples was a point of interest. Disappearance of the longest-lived o-Ps component with τ5 present in the PAL spectrum of initial MCM-41 mesoporous material in the PAL spectra of MnFe2O4-impregnated MCM-41 measured in vacuum is a result of either a strong chemical o-Ps quenching or the Ps inhibition effects. The intensity I4 of the medium-lived component initially increases, reaching a maximum value for the sample with minimum manganese ferrite content, and then decreases monotonically. Analogous dependence for the intensity I3 of the shortest-lived component shows a maximum at higher MnFe2O4 content. Filling of open pores present in the studied nanocomposites by N2 or O2 at ambient pressure causes partial reappearance of the τ4 and τ5 components, except a sample with maximum ferrite content. The lifetimes of these components measured in O2 are shortened in comparison to that observed in N2 because of paramagnetic quenching. Anti-inhibition and anti-quenching effects of atmospheric gases observed in the MnFe2O4/MCM-41 samples are a result of neutralization of some surface active centers acting as inhibitors and weakening of pick-off annihilation mechanism, respectively.

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Porto de Mello, Gustavo F., Riano E. Giribaldi, Diego Lorenzo-Oliveira et Nathália M. Paes Leme. « Atmospheric Parameters and Luminosities of Nearby M Dwarfs – Estimating Habitable Exoplanet Detectability with the E-ELT ». Proceedings of the International Astronomical Union 12, S328 (octobre 2016) : 371–73. http://dx.doi.org/10.1017/s1743921317003696.

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AbstractWe derive Teff and [Fe/H] for a sample of 72 nearby M-dwarfs with Hipparcos parallaxes and δ < +30. Spectra, acquired at the Observatório do Pico dos Dias, Brazil, have R = 10,000 and S/N ≳ 100 for nearly all targets in the λλ8380-8880 range. Atmospheric parameters were derived from VJHK colors and a system of spectral line indices calibrated against sample stars with interferometric Teff and [Fe/H] from detailed analysis of FGK binary companions. A PCA method of calibration yields internal errors within 70 K and 0.1 dex for Teff and [Fe/H]. For 18 stars we present the first Teff or [Fe/H] derivation in the literature. We compute the star's luminosities, calculate the position of their habitable zones and estimate that, were all of they to harbour rocky planets inside their HZ, 15–20 of these would be detectable by the E-ELT Planetary Camera and Spectrograph.

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Syed, Rafeel, Amina Rehman, Gautam Valecha et Suzanne El-Sayegh. « Pauci-Immune Crescentic Glomerulonephritis : An ANCA-Associated Vasculitis ». BioMed Research International 2015 (2015) : 1–8. http://dx.doi.org/10.1155/2015/402826.

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Rapidly progressive glomerulonephritis(RPGN) is a syndrome signified by a precipitous loss of renal function, with features of glomerulonephritis including dysmorphic erythrocyturia and glomerular proteinuria. RPGN is associated with extensive crescent formation, and, thus, the clinical term RPGN is often used interchangeably with the pathologic termcrescentic glomerulonephritis(CGN). From an immunopathologic standpoint, primary RPGN is divided intopauci-immune GN(PICG), anti-GBM GN, and immune complex GN. PICG, the most common etiology of primary RPGN, refers to a necrotizing glomerulonephritis with few or no immune deposits by immunofluorescence (IF) or electron microscopy (EM). In most patients, pauci-immune CGN is a component of a systemic small vessel vasculitis such as granulomatosis with polyangiitis (GPA). Approximately 90% of patients with PICG have circulating ANCA antibodies, leading to the nomenclatureANCA-associated vasculitis(AAV). Recent research has identified several other antibodies associated with PICG, which is now understood to be a complex spectrum of disease with considerable overlap in terms of clinical phenotype and outcomes. In addition, several genetic and environmental factors have recently been implicated in the pathogenesis of this disorder. With new prognostic classifications, enhanced understanding of immunopathologic mechanisms, and novel treatment paradigms, clinical and experimental interest in PICG remains high.

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Sinkorova, Z., J. Sinkora, L. Zarybnicka, Z. Vilasova et J. Pejchal. « Radiosensitivity of peripheral blood B cells in pigs ». Veterinární Medicína 54, No. 5 (1 juin 2009) : 223–35. http://dx.doi.org/10.17221/59/2009-vetmed.

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: Swine are here introduced to biodosimetry in an attempt to develop a large animal model allowing for comparison of in vitro experiments with the in vivo processes occurring after exposure to gamma radiation. This work investigates the radiosensitivity of the B cell compartment in peripheral blood. Four-week-old piglets were irradiated using the whole body protocol or full blood samples were irradiated in vitro in the dose range of 0–10 Gy. Relative radioresistance of B cell subpopulations and subsets was determined by measuring their relative numbers in leukocyte preparations at selected time intervals after irradiation using two color immunophenotyping and flow cytometry. Porcine B cells represent the most radiosensitive lymphocyte population in peripheral blood. Among B cell subpopulations and subsets investigated, the CD21+SWC7+ and CD21+CD1+ cells are highly radiosensitive and possess biodosimetric potential, at least in the range of low doses. Differences between cultures irradiated in vitro and lymphocyte dynamics in peripheral blood of irradiated animals clearly document the limits of in vitro data extrapolation in biodosimetry. We have shown that pigs can successfully be used in radiobiology and experimental biodosimetry due mainly to their availability, size and a relatively broad spectrum of available immunoreagents for lymphocyte classification.

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Xu, Y. G., L. Wang, Y. Chen et W. Tiu. « Load Sequence Effect on Fatigue Damage ». Key Engineering Materials 488-489 (septembre 2011) : 545–48. http://dx.doi.org/10.4028/www.scientific.net/kem.488-489.545.

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Reliable damage tolerant design of airframe structures relies on the accurate life prediction of fatigue cracks propagating from a detectable size to the critical size, which is challenging due to the complex load sequence effect under spectrum loading. This paper aims at gaining a further understanding of the complex influence of the loading history on fatigue damage through a detailed numerical simulation of the near-tip crack behaviour using the crack closure concept. The spectrum loading is broken down into a number of simple yet representative loading scenarios with overload/underload superimposed onto the baseline constant amplitude fatigue loading. Detailed finite element (FE) simulation of the plasticity-induced crack closure (PICC) has been carried out to catch the transient behaviour of PICC and link it to the fatigue damage. The load interaction effect has been analysed with the aim to identify the possible dominant loading cycle which could simplify the fatigue life prediction process in the industry. It is concluded that more reliable damage tolerant design can be achieved if the load sequence effect on fatigue damage can be taken into account more accurately for a structure under spectrum loadings.

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Picazzio, Enos, Klim I. Churyumov, Larissa S. Chubko, Igor V. Lukyanyk, Valery V. Kleshchonok, Amaury A. de Almeida et Roberto D. D. Costa. « Spectroscopic Studies of Comets 9P/Tempel 1, 37P/Forbes and C/2004 Q2 (Machholz) ». Proceedings of the International Astronomical Union 5, S263 (août 2009) : 277–80. http://dx.doi.org/10.1017/s1743921310001924.

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AbstractThe results of the analysis of the spectra of comets 9P/Tempel 1, 37P/Forbes and C/2004 Q2 (Machholz) observed in 2004-2005 at Observatório do Pico dos Dias (Brazil), and at Mount Pastukhov (SAO, Russia) are presented.

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Articles de revues sur le sujet « Pics spectraux »

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