Academic literature on the topic 'Signaux radioactives'
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Journal articles on the topic "Signaux radioactives":
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Han, Yongchao, Shoulong Xu, and Youjun Huang. "Real-Time Monitoring Method for Radioactive Substances Using Monolithic Active Pixel Sensors (MAPS)." Sensors 22, no. 10 (May 22, 2022): 3919. http://dx.doi.org/10.3390/s22103919.
Abstract:
This study presents a real-time monitoring technique for radioactive substances that meets safety management needs. We studied the accumulation characteristics of radiation response signals of monolithic active pixel sensors (MAPSs) based on their response and discrimination ability to gamma (γ) photon or neutron radiation. The radiation status of the radioactive substances was determined by monitoring the accumulation data of radiation responses. As per the results, Am-Be and 252Cf radiation response signals are primarily concentrated in the range of 0–70 pixels. Response signals of 60Co and 137Cs γ-ray were concentrated in two regions; there was a peak in the region with a pixel value of less than 50, and a plateau in the region with a pixel value of more than 75. Therefore, the results are able to discriminate between spectra. Furthermore, we designed a radioactivity monitoring system that is able to examine multiple radioactive materials. Its working principle is that a change in the accumulation of radioactivity monitoring data indicates a radiation change during the last accumulation cycle. This study provides vital technical support for the long-term supervision of radioactive substances.
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Durrant, I. "Radioactive and Non-Radioactive In Situ Hybridization Techniques." Proceedings, annual meeting, Electron Microscopy Society of America 54 (August 11, 1996): 8–9. http://dx.doi.org/10.1017/s0424820100162508.
Abstract:
In situ hybridization is a powerful technique that has found multiple applications in the biological sciences. The most widely used technique is in the analysis of mRNA species in cell populations. This is particularly useful for the analysis of relative amounts, site of transcription, timing and induction of transcription. Recent advances have lead the technique into the areas of relative quantification, dual signal detection and disease diagnosis. DNA targets can also be visualised by in situ hybridization both in cells and tissues and on isolated chromosomes and nuclei. There are a variety of systems that can be used to detect hybridization signals in situ. These choices are based in two areas, probe type and label type and this selection process holds true for both radioactive and non-radioactive systems.Probe selection is important and plays a part in the overall success of the application (see Table 1). RNA probes and oligonucleotide probes are the most widely used in cells and tissues whereas DNA probes are routinely used for chromosome and nuclei targets. RNA probes are used due to the higher sensitivity obtained but oligonucleotide probes are gaining in popularity due to ease of use. The lower sensitivity seen with these probes, due to lower labelling capacity, can be overcome by use of probe cocktails.
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Guyette, Frank, Joe Suyama, Jerry Rosen, and Michael Allswede. "Prevalence of Radioactive Signals from Surveillance of an Emergency Department." Prehospital and Disaster Medicine 21, no. 4 (August 2006): 276–81. http://dx.doi.org/10.1017/s1049023x00003836.
Abstract:
AbstractIntroduction:Since the 11 September 2001 terrorist attacks in the United States, concerns have been raised regarding the threat of a radiological terrorist weapon. Although the probability of the employment of a nuclear device is remote, the potential of a radiological dispersal device (RDD) or “dirty bomb” is of concern. While it is unlikely that such a device would produce massive numbers of casualties, it is far more likely that it would result in pub- lic panic and perhaps even disable the local healthcare system. The utility of surveillance with radiation detectors in the healthcare setting has not been fully evaluated.Objective:The objective of this study was to characterize the prevalence of radioactive sources entering an urban emergency department (ED).Methods:A retrospective review of data obtained from a radiation detector positioned to detect radioactive people entering an ED of an urban academic hospital that serves 45,000 patients/year was performed. Graphical outputs of radioactivity were recorded in Microsoft ExcelTM (Microsoft, Redmond, WA, US) spreadsheets in microREM/hour. Data were collected continuous-ly from 22 December 2003 to 22 January 2004. An event was defined as any elevation in radiation levels >95% confidence interval from the mean level of background radiation over 72 hours (h).Results:A total of 215 events were observed over a 28-day period, with a mean value of 7.7 events/day, and a maximum of 15 events/day. During the 28-day period, the baseline mean level of background radiation was 2–4 microREM/h. Readings ranged from 2,148.28–17,292.25 microREM/h with a maximum sustained detector exposure of 684.37 microREM. Distinct signal patterns were seen at both detectors including tonic, phasic, dual, and short duration spikes.Conclusion:The number of radioactive signals detected from persons entering the ED was much higher than expected. While the vast majority of these signals pose no health threat, they may make routine screening for a radiological terrorist event difficult.Further study is needed to determine this correlation.
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Min, Sujung, Kwang-Hoon Ko, Bumkyung Seo, JaeHak Cheong, Changhyun Roh, and Sangbum Hong. "Wireless Backpack System for Detection of Radioactive Cesium on Contaminated Soil Using Portable Plastic Scintillator with Efficient Readout Device." Electronics 10, no. 22 (November 18, 2021): 2833. http://dx.doi.org/10.3390/electronics10222833.
Abstract:
The miniaturization and usability of radiation detectors make it increasingly possible to use mobile instruments to detect and monitor gamma radiations. Here, a Bluetooth-based mobile detection system for integrated interaction in a backpack was designed and implemented to smart equipment for the detection of radioactive cesium on contaminated soil. The radiation measurement system was demonstrated in the form of a backpack using a quantum dot (QD)-loaded plastic scintillator manufactured and prepared directly in this study, and it can be measured by a person in the wireless framework of integrated interaction. The QD-loaded plastic scintillator was measured after setting the distance from the contaminated soil to 20, 50, and 100 mm. As a result, the detection efficiency of the commercial plastic scintillator (EJ-200) was calculated to be 11.81% and that of the QD-loaded plastic scintillator was 15.22%, which proved the higher detection efficiency performance than the commercial plastic scintillator. The measurement result was transmitted to a personal computer using Bluetooth as a portable system. In the future, this wireless system design could be expanded as a wireless communication system equipped with a global positioning system to detect and measure radioactively contaminated environments.
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Zhang, Lei, Chenkai Qiao, Jingjun Zhu, Yu Liu, Yulu Yan, Shin-Ted Lin, Shukui Liu, Changjian Tang, and Haoyang Xing. "Preparation of Large Volume Solid Argon Crystal and Its Feasibility Test as a Scintillation Material." Crystals 12, no. 10 (October 7, 2022): 1416. http://dx.doi.org/10.3390/cryst12101416.
Abstract:
An important background to the liquid argon detectors is that they are caused by the diffusion of radioactive isotopes in a scintillator (liquid phase). This radioactive isotope is produced in argon’s surrounding devices, such as circulation pipelines and liquid argon containers. The solid argon as a scintillation material in the detector can inhibit the diffusion and drift of radioactive isotopes in a solid phase scintillator. Additionally, the structure of a solid argon detector is simple and reduces the total source of radioactive background. In the CDEX-300 detection system, solid argon could substitute for liquid argon as the veto detector, preventing radioactive isotopes drifting to the central main detector (HPGe detectors array) surface to reduce backgrounds. Therefore, solid argon has great potential in the experiments since it is especially helpful to get the lower background in a larger active volume than liquid argon required in those low background detection experiments. This work introduces the preparation process and device of the large volume transparent crystalline argon, the acquisition of scintillation light, and the pulse amplitude spectrum of 137Cs obtained from a prototype detector of transparent solid argon crystal. The results show that the scheme proposed in this study can successfully produce a large volume transparent crystalline argon detector, the scintillation light signals can be effectively obtained from the solid argon scintillator, and the corresponding pulse amplitude spectrum is given. This work indicates that it is feasible to develop a solid argon crystal scintillation detector by using our approach.
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Babińska, Joanna, Krystyna Dyrek, and Piotr Wyszomirski. "EPR Study of Paramagnetic Defects in Clay Minerals." Mineralogia 38, no. 2 (January 1, 2007): 125–38. http://dx.doi.org/10.2478/v10002-007-0021-x.
Abstract:
EPR Study of Paramagnetic Defects in Clay MineralsRadiation induced defects (RID-s) and transition metal ion impurities were revealed by EPR (Electron Paramagnetic Resonance) spectroscopy in kaolinites from a number of Polish deposits. Arelationship between the intensity of the EPR signals of the RID-s and quantity of radioactive elements was defined in these minerals. In one of the deposits of kaolinites (Wyszonowice) the EPR signal intensity depends on grain size. Other clay minerals studied (illites, montmorillonites) only show weak signals of the RID type.
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Arakelyan, N. V., and Yu A. Kutoyants. "ON THE IDENTIFICATION OF THE SOURCE OF EMISSION ON THE PLANE." Proceedings of the YSU A: Physical and Mathematical Sciences 53, no. 2 (249) (August 15, 2019): 75–81. http://dx.doi.org/10.46991/pysu:a/2019.53.2.075.
Abstract:
We consider the problem of identification of the position and the moment of the beginning of a radioactive source emission on the plane. The acts of emission constitute inhomogeneous Poisson processes and are registered by $ K $ detectors on the plane. We suppose that the moments of arriving of the signals at the detectors are measured with some small errors. Then, using these estimate, we construct the estimators of the position of source and the moment of the beginning of emission. We study the asymptotic properties of these estimators for large signals and prove their consistency.
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Wulandari, H., F. Von Feilitzsch, M. Huber, Th Jagemann, J. Jochum, T. Lachenmaier, J. C. Lanfranchi, et al. "Study on Neutron-induced Background in the CRESST Experiment." Symposium - International Astronomical Union 220 (2004): 491–92. http://dx.doi.org/10.1017/s0074180900183895.
Abstract:
CRESST II is an experiment for direct WIMP search, using cryogenic detectors. the ratio of the two signals (temperature rise and scintillation light) measured for each interaction is an excellent parameter for discrimination of the radioactive background. the main remaining background is the neutron flux present at the experimental site, since neutrons produce the same signals as WIMPs do. Based on Monte Carlo simulations the present work shows how neutrons from different origins affect CRESST and which measures have to be taken into account to reach the sensitivity goal.
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KOUMANOV, Françoise, Jing YANG, E. Alison JONES, Yasumaru HATANAKA, and D. Geoffrey HOLMAN. "Cell-surface biotinylation of GLUT4 using bis-mannose photolabels." Biochemical Journal 330, no. 3 (March 15, 1998): 1209–15. http://dx.doi.org/10.1042/bj3301209.
Abstract:
New cell-impermeant bis-mannose photolabels have been developed with biotinyl groups attached to 4-(1-azi-2,2,2-trifluoroethyl)-benzoyl-1,3-bis(d-mannos-4-yloxy)-2-propylamine (ATB-BMPA) by either a polyethoxy spacer (Bio-ATB-BMPA) or an additional hexanoic acid spacer (Bio-LC-ATB-BMPA). The half-maximal inhibition constants, Ki values, for inhibition of glucose transport activity in insulin-stimulated rat adipocytes were determined to be 359±10 and 273±28 μM for Bio-ATB-BMPA and Bio-LC-ATB-BMPA, respectively. These values are similar to those previously reported for the non-biotinylated compound ATB-BMPA. Following UV-irradiation-induced cross-linking of the biotinylated photolabels to rat adipocytes, the biotinylated glucose transporter isoform 4 (GLUT4) could be detected by non-radioactive and radioactive methods that utilized the interaction with streptavidin. Biotinylated GLUT4 from 1-2 μg of adipose cell membranes, precipitated onto magnetic streptavidin beads, could be sensitively and quantitatively detected using an electrochemiluminescent assay method. This utilized a ruthenium-tagged anti-GLUT4 antibody that on excitation at an electrode generated an electrochemiluminescent signal in an ORIGEN analyser. Alternatively, surface-biotinylated GLUT4 could be easily, but less sensitively, detected in streptavidin agarose precipitates which were analysed by conventional GLUT4 Western blotting. Data obtained using the non-radioactive methods compared favourably with those using tritiated versions of the biotinylated probes. Insulin treatment of adipocytes increased the levels of signals from surface biotinylated GLUT4 by ~ 10-fold or ~ 20-fold, respectively, when the electrochemiluminescent or the Western blot detection methods were used and these signals were blocked by cytochalasin B.
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Steinitz, G., M. C. Martín, N. Gazit-Yaari, M. L. Quesada, J. de la Nuez, R. Casillas, U. Malik, and Z. B. Begin. "Multi-day radon signals with a radioactive decay limb—Occurrence and geophysical significance." Applied Radiation and Isotopes 64, no. 4 (April 2006): 520–24. http://dx.doi.org/10.1016/j.apradiso.2005.10.004.
Dissertations / Theses on the topic "Signaux radioactives":
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Hachem, Ali. "Characterization of radioactivity signals by embedded machine learning." Electronic Thesis or Diss., université Paris-Saclay, 2024. http://www.theses.fr/2024UPASP017.
Abstract:
Dans diverses applications, la classification des signaux de détecteurs de rayonnements revêt une importance cruciale. Cette thèse se concentre sur un cas d'utilisation spécifique et complexe, à savoir la discrimination des neutrons et des rayonnements gamma dans un scintillateur plastique organique, en utilisant l'apprentissage automatique embarqué. Les solutions explorées dans cette étude pourraient potentiellement être étendues à la discrimination d'autres types de radiations dans des détecteurs différents. Nous présentons tout d'abord une méthode pour créer des ensembles de données neutron-gamma étiquetés, acquis par un scintillateur organique. Ce point est crucial car toutes les sources de neutrons émettent des rayonnements gamma. Les modèles Multilayer Perceptron (MLP) et 1D Convolution Neural Network (CNN) supervisés sont entraînés et évalués avec les signaux bruts préparés en utilisant la méthode d'étiquetage. Le modèle 1D CNN surpasse le modèle MLP, qui, à son tour, surpasse l'état de l'art, en particulier pour les radiations à faible énergie ([100, 250] keVee). Une deuxième approche d'apprentissage basée sur l'extraction d'attributs a été explorée pour faire la discrimination, permettant à un signal d'être représenté par une dimension indépendante de la chaîne d'acquisition, facilitant ainsi l'utilisation de méthodes d'adaptation non supervisées. Les résultats montrent que les modèles supervisés sur les signaux bruts sont plus performants que l'approche basée sur les attributs extraits. Dans cette étude, l'attribut de "Form Factor" est exploré en tant que nouvelle méthode de discrimination, offrant des performances similaires à l'algorithme de l'état de l'art sans nécessiter d'ajustement de paramètres. Enfin, nous avons implémenté les modèles d'apprentissage proposés et l'algorithme de l'état de l'art sur Field Programmable Gate Array (FPGA), pour une discrimination en temps réel, en respectant une latence inférieure à la durée du signal. En prenant en compte la latence et la consommation de ressources comme une référence de comparaison, l'order des méthodes s'inverseIn various applications, the classification of radiation detector signals is of crucial importance. This thesis focuses on a specific and complex use case, namely the discrimination of neutrons and gamma-rays in an organic plastic scintillator using integrated machine learning (ML). The solutions explored in this study could potentially be extended to the discrimination of other types of radiations in different detectors. We present a method for creating labeled neutron-gamma datasets acquired through an organic scintillator. This is critical as all neutron sources emit gamma-rays. Supervised Multilayer Perceptron (MLP) and 1D Convolution Neural (CNN) models are trained and evaluated with the prepared dataset using the labeling method. The 1D CNN model outperforms the MLP model, which, in turn, surpasses the state-of-the-art, especially for low-energy radiations ([100, 250] keVee). A second ML approach based on features extraction was explored for discrimination, allowing a signal to be represented by a dimension independent of the acquisition chain, thus facilitating the use of unsupervised adaptation methods. The results indicate that supervised models on raw signals perform better than the attribute-based approach. In this study, the "Form Factor" attribute is explored as a novel discrimination method, offering performance similar to the state-of-the-art algorithm without requiring parameter tuning. Finally, we implemented the proposed ML models and state-of-art algorithm on Field Programmable Gate Array (FPGA) for a discrimination on the fly, while maintaining latency below less than the signal duration. Considering latency and resource consumption as a basis for comparison, the order of the methods is reversed
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Fontbonne, Cathy. "Acquisition multiparamétrique de signaux de décroissance radioactive pour la correction des défauts instrumentaux : application à la mesure de la durée de vie du 19Ne." Thesis, Normandie, 2017. http://www.theses.fr/2017NORMC204/document.
Abstract:
L’objectif de cette thèse est de proposer une méthode de mesure précise d’une période radioactive de l’ordre de quelques secondes. L’acquisition numérique temps réel FASTER permet d’accéder aux caractéristiques physiques du signal induit par la détection de chaque désintégration lors de la décroissance radioactive. La sélection des données de comptage peut se faire par une analyse optimisée post-expérience. Ainsi, après avoir établi les facteurs d’influence de la mesure (variation d’empilements, de gain des tubes photomultiplicateurs, de la ligne de base électronique), il est possible, a posteriori, de calculer leur impact sur l’estimation de la période radioactive, et de choisir un seuil en énergie déposée, ainsi qu’un temps mort qui minimisent leurs influences. Cette thèse propose, par ailleurs, une méthode pour mesurer, puis compenser les variations de ses grandeurs. Cette méthode a été appliquée pour l’estimation de la période radioactive du 19Ne avec une incertitude relative de 1,2.10-4 : T1/2=17,2569(21) sThe aim of this thesis is to propose a method for precise half-life measurements adapted to nuclides with half-lives of a few seconds. The FASTER real-time digital acquisition system gives access to the physical characteristics of the signal induced by the detection of each decay during the counting period following beam implantation. The selection of the counting data can be carried out by an optimized post-experimental offline analysis. Thus, after establishing the influence factors impacting the measurement (pile up, gain and base line fluctuations), we are able to estimate, a posteriori, their impact on the half-life estimation. This way, we can choose the deposited energy threshold and dead time in order to minimize their effect. This thesis also proposes a method for measuring and then compensating for influence factors variations. This method was applied to estimate the 19Ne half-life with a relative uncertainty of 1.2 10-4 leading to T1 / 2 = 17.2569 (21) s. This is the most precise measurement to date for this isotope
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Yosief, Kidane Ogbaghebriel. "Source localization and tracking for possibly unknown signal propagation model." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/1521.
Abstract:
This thesis considers source localization and tracking when both the signal propagation model and the source motion dynamics are unknown. Algorithms are developed for different scenarios. The algorithms are discussed when a source is stationary or mobile, under the condition when sensors are fixed or mobile. These algorithms exploit the strictly decreasing properties of the model in terms of distance, but do not depend on the form and the values of the models. Therefore, these algorithms could be applied when the signal propagation models and the source motion are unknown. The only assumption made is that the signal propagation strength decreases in distance. For a given performance specification, the optimal number and placement of the sensors is also discussed. Convergence and other properties of the algorithms are established under various noise assumptions.
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Casiraghi, Marina. "Functional modulation of a G protein-coupled receptor conformational landscape in a lipid bilayer." Thesis, Sorbonne Paris Cité, 2016. http://www.theses.fr/2016USPCC138/document.
Abstract:
Les récepteurs couplés aux protéines G (GPCRs en anglais) représentent la famille de récepteurs intégrales de membrane plus vaste dans la majorité des cellules eucaryotes. Ils jouent un rôle clé dans la transduction de signal, ainsi que la compréhension de leur mécanisme de signalisation représente une des questions principales dans la biologie d'aujourd'hui. Dans la caractérisation du paysage énergétique de ces récepteurs à l'échelle atomique, les structures cristallographiques publiées pendant la décennie dernière par cristallographie aux rayons X représentent la percée scientifique majeure et donnent une contribution fondamentale dans la biologie structurelle de GPCRS. Ces structures représentent un point de départ précieux dans la compréhension du mécanisme de transduction de signal, en plaçant des structures dans l'ensemble conformationnel de ces récepteurs le long du processus d'activation. Pour compléter ce cadre de structures statiques qui correspondent aux états à basse l'énergie et fortement peuplés, une caractérisation de l'ensemble conformationnel et des barrières cinétiques qui sont associées est un point nécessaire et fondamentale. À ce but nous proposons une approche innovant avec la finalité d'observer le paysage conformationnel dynamique des GPCR et étudier la modulation de ces récepteurs par des ligands et des lipides, qui sont connus pour jouer un rôle clé dans la structure et les fonctions des protéines de membrane (e.g.). Un des outilles le plus approprié pour explorer les barrières cinétiques de GPCR c'est la résonance magnétique nucléaire (RMN) en solution. Pour tirer profit au mieux de cette technique, nous avons utilisé des sondes marqués 13CH3 immergées dans un environnement perdeuteré, qui constitue le marquage isotopique le plus approprié en RMN pour examiner les paysages conformationnels des protéines de grosses dimensionnes ou des complexes de protéines. Nous avons choisi Escherichia coli comme système d'expression pour sa capacité de pousser dans des conditions très hostiles comme des solutions 100%-D2O. Pour surmonter les difficultés habituellement rencontrées lors de l'expression des GPCRs, nous avons appliqué un protocole innovant qui cible l'expression de GPCRs directement aux corps d'inclusion. Ceci permet la production des bonnes quantités de protéines (jusqu’à 6 mg/litres de culture de pur 13CH3-u-2H-GPCRs). Une fois purifié, le récepteur est foldé en amphipols et transféré ensuite à une double couche lipidique appelée nanometric lipid bilayer ou nanodisc (NLB). De façon très important, les mesures pharmacologiques quantitatives indiquent que les récepteurs incorporés dans des NLBs après ce protocole sont stables et entièrement actifs dans les conditions des expériences de NMR.Les investigations par RMN conduites sur le GPCR en NLB ont donné lieu à une résolution jamais obtenue dans le domaine, grâce à la biochimie finement accordée et à la perdeuteration du récepteur. Selon les données obtenues, notre récepteur modèle, le récepteur 2 pour le leukotriene B4 (BLT2), est capable d'explorer plusieurs conformations différentes, même dans l'état pas lié aux ligands, y compris l'état actif. Ce paysage conformationnel est également modulé par des ligands et des lipides. Dans le cas spécifiques, nous avons observé que un incrément dans le contenu de stérol dans la membrane modifie la distribution des différents états conformationnels du récepteur, en favorisant l'état actif, qui indique une régulation allosteric positif du stérol sur l'activation de ce récepteur, comme confirmé aussi par les mesures de liaison du GTP à la protéine G. Cette propriété du stérol est probablement importante pour le contrôle de mécanisme de signalisation de GPCRsG protein-coupled receptors (GPCRs) are the largest family of integral membrane protein receptors present in most eukaryotic cells. They play a key role in signal transduction and understanding their signalling mechanism represents one of the main issues in biology today. In the characterization of the energy landscape of these receptors, at the atomic scale, X-ray crystal atomic structures published during the last decade represent the major breakthrough and contribution in the structural biology of GPCRs. They represent a precious starting point in the understanding of the mechanism of signal transduction by placing structures in the conformational ensemble of these receptors along the activation pathway. To complete these static snapshots that correspond to low energy and highly populated states, a characterization of the whole conformational ensemble and associated kinetic barriers is fundamental to complete the picture. To this aim we proposed an innovative approach to observe GPCRs dynamic conformational landscape and how it is modulated by ligands and lipids, that are known to play a key role in membrane protein structures and functions (e.g.). One of the most appropriate tool to explore GPCR kinetic barriers is solution state NMR. To do so, we used 13CH3 probes immersed in a perdeuterated environment, the most appropriate isotope-labelling scheme to investigate conformational landscapes of large proteins or protein complexes with this spectroscopy. We chose Escherichia coli as expression system for its ability to grow in very hostile conditions like 100%-D2O solutions. In order to overcome the usual expression issues concerning GPCRs, we applied an innovative protocol which targets the expression directly to inclusion bodies. This allows the production of high amounts of proteins (up to 6 mg/litre of culture of pure 13CH3-u-2H-GPCRs). Once purified, receptors are folded in amphipols and then transferred to nanometric lipid bilayers or nanodiscs. Importantly quantitative pharmacological measurements indicate that receptors embedded in NLBs following this protocol are stable and fully active in the conditions of the NMR experiments. NMR investigation of a GPCR in a NLB gave rise to a resolution never achieved in the field thanks to a fine tuned biochemistry and a perdeuteration of the receptor. According to our data, the prototypical receptor, the leukotriene B4 receptor (BLT2), is able to explore multiple different conformations, even in the unliganded state, including the active state. This conformational landscape is further modulated by ligands and lipids. In particular, we observed that an increment in the sterol content of the membrane modifies the distribution of the different conformational states of the receptor in favour of the active one, indicating a positive allosteric regulation of the sterol on the activation of this receptor, as confirmed by GTP-to-G protein binding measurements. This property of the sterol is likely important for the control of the signalling properties of GPCRs
Books on the topic "Signaux radioactives":
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Garcia, Ernest V., James R. Galt, and Ji Chen. SPECT and PET Instrumentation. Oxford University Press, 2015. http://dx.doi.org/10.1093/med/9780199392094.003.0003.
Abstract:
Nuclear cardiac imaging is solidly based on many branches of science and engineering, including nuclear, optical and mathematical physics, electrical and mechanical engineering, chemistry and biology. This chapter uses principles from these scientific fields to provide an understanding of both the signals used, and the imaging system that captures these signals. Nuclear cardiology’s signals are the x-rays or ?-rays photons emitted from a radioactive tracer and its imaging systems are either single-photon emission computed tomography (SPECT) or positron emission tomography (PET) cameras. This combination has met with remarkable success in clinical cardiology. This success is due to the combination of sophisticated electronic nuclear instruments with a highly specific and thus powerful signal. The signal is as important as or more important than the imaging system. There is a misconception that cardiac magnetic resonance (CMR) cardiac computed tomography (CCT) and echocardiography are superior to nuclear cardiology imaging because of their superior spatial resolution. Yet, in detecting perfusion defects what is really necessary is superior contrast resolution. It is this superior contrast resolution that allows us to differentiate between normal and hypoperfused myocardium facilitating the visual analysis of nuclear cardiology perfusion images. Because these objects are bright compared to the background radioactivity, computer algorithms have been developed that allow us to automatically and objectively process and quantify our images. This chapter explains many of the important scientific principles necessary to understand nuclear cardiology imaging in general, i.e., how these sophisticated imaging systems detect the radiation emitted from the radiotracers.
Book chapters on the topic "Signaux radioactives":
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"Signal enzyme detection." In Non-Radioactive Labelling, 124–25. Elsevier, 1997. http://dx.doi.org/10.1016/b978-012276045-7/50020-9.
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"Use of Eigenvector Centrality for Mobile Target Tracking." In Advances in Wireless Technologies and Telecommunication, 111–28. IGI Global, 2018. http://dx.doi.org/10.4018/978-1-5225-3802-8.ch006.
Abstract:
The author proposes an eigenvector centrality (EVC)-based tracking algorithm to trace the trajectory of a mobile radioactive dispersal device (RDD) in a wireless sensor network. They propose that the sensor nodes simply sum up the strengths of the signals (including those emanating from a RDD) sensed in the neighborhood over a sampling time period and forward the sum of the signals to a control center (called sink). For every sampling time period, the sink constructs an adjacency matrix in which the entry for edge (i, j) is the sum of the signal strengths reported by sensor nodes i and j, and uses this adjacency matrix as the basis to determine the principal eigenvector whose entries represents the EVCs of the vertices with respect to the radioactive signals sensed in the neighborhood. The author proposes that the arithmetic mean (calculated by the sink) of the X and Y coordinates of the suspect sensor nodes (those with higher EVCs) be considered as the predicted location of the RDD at a time instant corresponding to the middle of the sampling time period.
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Garman, A. J. "Introduction to non-radioactive signals and labels." In Non-Radioactive Labelling, 1–19. Elsevier, 1997. http://dx.doi.org/10.1016/b978-012276045-7/50004-0.
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Emson, P. C., D. J. Nunez,, and A. P. Davenport. "In situ hybridization for the localization and quantification of peptide mRNAs." In Peptide Hormone Secretion, 159–87. Oxford University PressOxford, 1990. http://dx.doi.org/10.1093/oso/9780199630684.003.0006.
Abstract:
Abstract In situ hybridization (or hybridization histochemistry) is the application of nucleic acid hybridization techniques to the detection of DNA or RNA sequences in cytological and histochemical preparations. The method is inherently more sensitive than other nucleic acid hybridization techniques which depend on the preparation of DNA or RNA samples from homogenized tissue, in that the signal may be detected within an individual cell or group of cells. Thus, it is possible, for example, to detect which cells in a brain nucleus are expressing a particular gene and also to use a combination of radioactive and non-radioactive probes to identify several gene transcripts in a single tissue section. The sensitivity of the technique is such that a few copies of an mRNA can be detected within a cell and with the use of suitable densitometric methods, it is also possible to make data assessment quantitative. The technique of in situ hybridization for detection of nuclear DNA will not be considered here, but details can be found in a companion volume (Nucleic Acids Hybridization) (I). In this chapter we will concentrate on the procedures for radioactive and non-radioactive in situ hybridization used in our laboratory for the detection of peptide mRNAs and we will discuss our attempts at quantifying the signals. For further discussion of the method, its limitations and alternative protocols, the reader should consult reviews (1—5).
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Ababou, Rachid, Hassane Fatmi, Jean-Michel Matray, Christophe Nussbaum, and David Bailly. "Statistical Analyses of Pore Pressure Signals in Claystone During Excavation Works at the Mont Terri Underground Research Laboratory." In Radioactive Waste. InTech, 2012. http://dx.doi.org/10.5772/33187.
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Meghanathan, Natarajan. "Eigenvector Centrality-Based Mobile Target Tracking in Wireless Sensor Networks." In Sensor Technology, 1150–67. IGI Global, 2020. http://dx.doi.org/10.4018/978-1-7998-2454-1.ch054.
Abstract:
We propose an eigenvector centrality-based tracking algorithm to trace the trajectory of a mobile Radioactive Dispersal Device (RDD) in a wireless sensor network. The sink constructs an adjacency matrix in which the entry for edge (i, j) is the sum of the signal strengths reported by sensor nodes i and j in their respective neighborhoods over a sampling time period. The sink uses this adjacency matrix as the basis to determine the Eigenvector Centralities (EVC) of the vertices with respect to the radioactive signals sensed in the neighborhood. We hypothesize that sensor nodes that have a high EVC (suspect nodes) for the sampling time period are within the vicinity of the RDD within that period. We propose that the arithmetic mean (calculated by the sink) of the X and Y coordinates of the suspect sensor nodes be considered as the predicted location of the RDD at a time instant corresponding to the middle of the sampling time period. We evaluate the difference between the predicted and exact locations of the RDD trajectory over time as a function of different operating parameters.
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Meghanathan, Natarajan. "Eigenvector Centrality-Based Mobile Target Tracking in Wireless Sensor Networks." In Advances in Wireless Technologies and Telecommunication, 395–412. IGI Global, 2017. http://dx.doi.org/10.4018/978-1-5225-0501-3.ch016.
Abstract:
We propose an eigenvector centrality-based tracking algorithm to trace the trajectory of a mobile Radioactive Dispersal Device (RDD) in a wireless sensor network. The sink constructs an adjacency matrix in which the entry for edge (i, j) is the sum of the signal strengths reported by sensor nodes i and j in their respective neighborhoods over a sampling time period. The sink uses this adjacency matrix as the basis to determine the Eigenvector Centralities (EVC) of the vertices with respect to the radioactive signals sensed in the neighborhood. We hypothesize that sensor nodes that have a high EVC (suspect nodes) for the sampling time period are within the vicinity of the RDD within that period. We propose that the arithmetic mean (calculated by the sink) of the X and Y coordinates of the suspect sensor nodes be considered as the predicted location of the RDD at a time instant corresponding to the middle of the sampling time period. We evaluate the difference between the predicted and exact locations of the RDD trajectory over time as a function of different operating parameters.
8
Self, Colin H., David L. Bates, and David B. Cook. "Enzyme amplification systems in ELISA." In Immunochemistry 1, 177–92. Oxford University PressOxford, 1997. http://dx.doi.org/10.1093/oso/9780199636068.003.0009.
Abstract:
Abstract Enzyme amplification was devised to allow the development of highly sensitive and rapid immunoassays (1).Enzyme labels were amongst the earliest alternative labels to radioisotopes introduced to immunoassay. With the limited specific activity of radioisotopes, it had been realized that, theoretically, enzymes had a much more sensitive detection capability because of their capacity for continuous catalysis of transformation of substrate to deliver some form of signal; for example colour, fluorescence, or electric current. The original concept of enzyme amplification was developed in response to the fact that, in routinely used tests, enzyme labels were not able to generate sufficient signal to compete with the then much more widely employed radioactive labels. Increasing substrate incubation times to days rather than minutes or hours simply served to increase background signals. Enzyme labels capable of much greater powers of signal generation were required to enable the development of not only more sensitive, but faster immunoassays. The major advantage of employing a sensitive enzyme measurement even in a competitive method with its inherently limited sensitivity (2), was seen to be the ability to deliver a very rapid assay system (3).
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Nayak, Richi. "Wireless Technologies to Enable Electronic Business." In Encyclopedia of Information Science and Technology, First Edition, 3101–5. IGI Global, 2005. http://dx.doi.org/10.4018/978-1-59140-553-5.ch552.
Abstract:
Research and practices in electronic business (e-business) have witnessed an exponential growth in the last few years (Liautand & Hammond, 2001). Wireless technology has also evolved from simple analog products designed for business use to emerging radioactive, signal-based wireless communications (Shafi, 2001). The tremendous potential of mobile computing and e-business has created a new concept of mobile e-business or e-business over wireless devices (m-business).
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Nayak, Richi. "Wireless Technologies to Enable Electronic Business." In Business Information Systems, 511–17. IGI Global, 2010. http://dx.doi.org/10.4018/978-1-61520-969-9.ch032.
Abstract:
Research and practices in electronic business (e-business) have witnessed an exponential growth in the last few years (Liautand & Hammond, 2001). Wireless technology has also evolved from simple analog products designed for business use to emerging radioactive, signal-based wireless communications (Shafi, 2001). The tremendous potential of mobile computing and e-business has created a new concept of mobile e-business or e-business over wireless devices (m-business).
Conference papers on the topic "Signaux radioactives":
1
Miller, D., D. Ackermann, R. Grzywacz, S. Heinz, F. P. Heßberger, S. Hofmann, M. Madurga, et al. "Digital signal processing for radioactive decay studies." In THE 4TH INTERNATIONAL CONFERENCE ON PROTON EMITTING NUCLEI AND RELATED TOPICS. AIP, 2011. http://dx.doi.org/10.1063/1.3664167.
2
Spasova, L. M., M. I. Ojovan, M. Hayes, and H. Godfrey. "Acoustic Emission Monitoring of Cement-Based Structures Immobilising Radioactive Waste." In The 11th International Conference on Environmental Remediation and Radioactive Waste Management. ASMEDC, 2007. http://dx.doi.org/10.1115/icem2007-7049.
Abstract:
The long term performance of cementitious structures immobilising radioactive waste can be affected by physical and chemical processes within the encapsulating materials such as formation of new phases (e.g., vaterite, brucite), degradation of cement phases (e.g., CSH gel, portlandite), degradation of some waste components (e.g., organics), corrosion of metallic constituents (aluminium, magnesium), gas emission, further hydration etc. The corrosion of metals in the high pH cementitious environment is of especial concern as it can potentially cause wasteform cracking. One of the perspective non-destructive methods used to monitor and assess the mechanical properties of materials and structures is based on an acoustic emission (AE) technique. In this study an AE non-destructive technique was used to evaluate the mechanical performance of cementitious structures with encapsulated metallic waste such as aluminium. AE signals generated as a result of aluminium corrosion in a small-size blast furnace slag (BFS)/ordinary Portland cement (OPC) sample were detected, recorded and analysed. A procedure for AE data analysis including conventional parameter-based AE approach and signal-based analysis was applied and demonstrated to provide information on the aluminium corrosion process and its impact on the mechanical performance of the encapsulating cement matrix.
3
Li-xia, He, Hao Xiao-yong, and He Gao-kui. "Study on TlBr Radioactive Detector." In 2017 25th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2017. http://dx.doi.org/10.1115/icone25-66120.
Abstract:
TlBr is a kind of semiconductor material. Due to its promising physical properties and can be used at room temperature, it is continually studied as X and gamma ray detectors candidate material. Both of its atomic number and density are high. It also has large band-gap (B = 2.68eV) and low ionization energy. TlBr device exhibits high detection efficiency and excellent energy resolution. It can be easily fabricated or compacted in small housing. So it is a reasonable selection in the fields of nuclear material inspection and safeguards property, national security, spatial and high energy physics researches. The paper investigates the TlBr radioactive detector development and fabrication procedures. The processing detail information and signals collection are emphasized in different section. The prototype detectors were irradiated by Am-241 and corresponding spectrum was obtained. The photoelectric peak at 59.5keV is distinguished visible and the best resolution at 59.5keV is 4.15keV (7%).
4
Yang, Hui, Hao Zhou, Bing Dong, Wentao Zhou, Weiguo Gu, Xinyu Zhang, Qingxin Lei, Chenyu Shan, and Dezhong Wang. "A Novel Transmission Reconstruction Algorithm for Radioactive Drum Characterization." In 2022 29th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2022. http://dx.doi.org/10.1115/icone29-90126.
Abstract:
Abstract The accuracy of tomographic gamma scanning transmission reconstruction is a critical factor in reconstructing the activity of a radioactive drum. Traditional reconstruction algorithms produce severe grid artifacts and a high level of noise, thereby increasing the reconstruction error for both the density map and the activity. This paper proposes a novel algorithm for transmission reconstruction by combining maximum-likelihood expectation maximization and a convolutional neural network (CNN). Our experimental results indicate that the proposed reconstruction algorithm is capable of significantly reducing measurement errors, increasing spatial resolution while also eliminating grid artifacts, and being sufficiently robust when dealing with a noisy input image. The mean squared error of the output image decreased by 52.70% compared with the conventional reconstruction method, and the peak signal-to-noise ratio and structural similarity index improved by 21.89% and 17.33%, respectively. The spatial resolution was improved by 28 times, which demonstrates that CNN is a potentially useful new method for radioactive waste drum transmission image reconstruction.
5
Luo, Bin, and Shuangquan Ge. "Augmented reality for material processing within shielded radioactive environment." In 2015 8th International Congress on Image and Signal Processing (CISP). IEEE, 2015. http://dx.doi.org/10.1109/cisp.2015.7407856.
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Mueterthies, M. J., D. E. Krause, A. Longman, V. E. Barnes, and E. Fischbach. "Is There a Signal for Lorentz Noninvariance in Existing Radioactive Decay Data?" In Seventh Meeting on CPT and Lorentz Symmetry. WORLD SCIENTIFIC, 2017. http://dx.doi.org/10.1142/9789813148505_0050.
7
May, R., R. Strange, M. Bruggeman, and W. De Boeck. "Independent Quality Checking of UK Low Level Radioactive Waste for Plutonium Using the SCK•CEN Hexagon 2000 Passive Neutron Coincidence Counter." In ASME 2003 9th International Conference on Radioactive Waste Management and Environmental Remediation. ASMEDC, 2003. http://dx.doi.org/10.1115/icem2003-4954.
Abstract:
Checking low level wastes requires the detection of sub-milligram levels of plutonium. This is an extreme challenge for passive neutron coincidence counting as the levels of true signal are close to the background signal caused by cosmic ray interactions. The origin of cosmic-induced background is discussed. We describe the Hexagon 2000 passive neutron coincidence counter that has been designed and built for waste quality checking of low-level radioactive waste in the UK for the Environment Agency. The instrument uses computed neutron coincidence counting and improved filtering of high multiplicity cosmic-induced events. The instrument also correlates background signal with atmospheric pressure to further increase sensitivity. Preliminary measurements of background data and of test drums containing small amounts of plutonium are described.
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Castoldi, A., and C. Guazzoni. "Simulation of the Induced Signals in SiC Detectors for Radioactive Ion Beam Tagging." In 2023 IEEE Nuclear Science Symposium, Medical Imaging Conference and International Symposium on Room-Temperature Semiconductor Detectors (NSS MIC RTSD). IEEE, 2023. http://dx.doi.org/10.1109/nssmicrtsd49126.2023.10337825.
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Brandys, Irad, Yeshayahu Levin, Rahamim Atias, Yair Ifergan, and Yosef Cohen. "Experimental Heat Transfer Spectrum Shift Prevention of a Portable Radiation Spectrometry System." In ASME 2011 International Mechanical Engineering Congress and Exposition. ASMEDC, 2011. http://dx.doi.org/10.1115/imece2011-62929.
Abstract:
Each radioactive material has its unique energy signature (spectrum). Spectrum shift during measurements is a well know phenomenon which occurs due to environmental temperature changes which affect the electronics, and can lead to misidentification of the radioactive material. We developed a new portable spectroscopy workstation based on Digital Signal Processing (DSP) technology, which includes an analog circuit, a Multi Channel Analyzer (MCA), 7 power suppliers and a laptop. The designed system, to which wide range of radioactive detectors can be attached, uses to identify a sampled radioactive material according to its spectrum. In order to prevent the spectrum shift phenomena, both natural and forced convection heat transfer experiments were carried out. Few configurations were tested during these experiments whose results yielded the final electronic packaging configuration of the system as well as the definition of the stabilization time of the system.
10
Bamberger, Judith A., and Margaret S. Greenwood. "Evolution of a Non-Invasive Sensor for Fluid Density and Solids Concentration Measurement Using Ultrasound." In ASME/JSME 2003 4th Joint Fluids Summer Engineering Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/fedsm2003-45590.
Abstract:
This paper describes the evolution of an ultrasonic sensor to non-invasively measure slurry density and solids concentration. Three generations of probe are discussed: 1) density sensor, 2) densimeter, and 3) fluid and solids monitor. The initial application was to measure slurry density during radioactive waste transport. The probe uses ultrasonic signal reflection at the fluid-pipe wall interface to quantify density in situ in real time and signal attenuation to evaluate solid concentration. In the latest configuration, the transducers are mounted on the wall of the pipe spool piece. This instrument was selected for monitoring radioactive waste transport based on several characteristic features: the sensing surface is non-intrusive and does not disrupt the slurry flow, instrument performance is not affected by slight amounts of entrained air that could be present during waste retrieval and transfer; nor is it affected by electromagnetic noise from nearby pumps and other equipment; and the instrument is compact. The densimeter has been deployed at Hanford tank SY-101 in the prefabricated pump pit process manifold to monitor slurry properties during radioactive waste transfers. To qualify densimeter performance prior to manifold installation in the radioactive pipeline, the probe was installed in the process manifold and performance was evaluated during tests using non-radioactive waste simulants over the density range from 1000 to 1500 kg/m3. The probe predicted density within ± 2%. The sensor is installed in a nominal 5-cm-diameter (2-in.) pipe spool piece; the design pressure is 2.8 MPa (400 psi). To ensure operability during prolonged contact with radioactive waste, the probe wedge in contact with the slurry was selected to operate up to pH 14, and the probe components were radiation tested at exposures of 1×106 R.