Measuring count rates free from correlated noise in digital silicon photomultipliers

Abstract : The characterization of nuisance parameters in digital silicon photomultipliers (SiPMs) is important to their understanding and future development. Methods able to distinguish the types of events are necessary to obtain fair and legitimate measurements. In this work, the zero photon probability (ZPP) method and the time delay (TD) method are used to measure the dark noise of digital SiPMs free from the contribution of correlated noise such as afterpulsing and crosstalk. It highlights the unique features of digital SiPMs such as the holdoff delay, the digital output signal, and the embedded processing (e.g. the selection of the interval sampling width). The two methods correctly separate the correlated and uncorrelated events in digital SiPMs and therefore the determination of a true photon detection efficiency (PDE) is possible. The ZPP method is also implemented inside a digital SiPM using embedded digital signal processing

Five-year outcomes of the First Distal Uninstrumented Vertebra after posterior fusion for Adolescent Idiopathic Scoliosis Lenke 1 or 2

BACKGROUND: Tilt of the First Distal Uninstrumented Vertebra (FDUV) reflects changes in the main curve and compensatory lumbar curve after posterior fusion to treat thoracic Adolescent Idiopathic Scoliosis (AIS). HYPOTHESIS: FDUV tilt 5 years or more post-fusion depends chiefly on reduction of the main curve and on other factors such as selection of the last instrumented vertebra. MATERIAL AND METHOD: A multicenter retrospective cohort of 182 patients with Lenke 1 or 2 AIS treated with posterior instrumentation and followed up for a mean of 8 years and a minimum of 5 years was studied. The patients were divided into two groups based on whether tilt of the upper endplate of the FDUV was ≤5° or >5°at last follow-up. Variables associated with tilt were identified by multiple logistic regression. RESULTS: Six variables were significantly associated with FDUVtilt: percentage of correction at last follow-up, correction loss, lumbar modifier B, number of instrumented vertebrae, inclusion within the instrumentation of the distal neutral vertebra, and inclusion within the instrumentation of the lowest vertebra intersected by the central sacral vertical line. DISCUSSION AND CONCLUSION: The main variables associated with FDUVtilt ≤5° were a final correction percentage ≥60% and absence of correction loss between the postoperative period and last follow-up. Given the stable reduction provided by contemporary instrumentations, we recommend selective thoracic fusion of Lenke 1 or 2 AIS with lumbar modifiers A, B, and C. The lowest instrumented vertebra should be either the neutral vertebra or the vertebra intersected by the central sacral vertical line if it is distal to the neutral vertebra. LEVEL OF EVIDENCE IV: Retrospective multicenter study

Lower Extremity Arterial Disease and Lumbar Spinal Stenosis: A Study of Exercise-Induced Arterial Ischemia in 5197 Patients Complaining of Claudication

Only few studies have analyzed the associations of lower extremity artery disease (LEAD) with lumbar spinal stenosis (LSS), although it is expected to be a frequent association. With exercise-oximetry, we determined the presence of exercise-induced regional blood flow impairment (ischemia) in 5197 different patients complaining of claudication and referred for treadmill testing. We recorded height, weight, age, sex, ongoing treatments, cardiovascular risk factor (diabetes, high blood pressure, current smoking habit), and history of suspected or treated LSS and/or lower limb revascularization. An ankle-brachial index at rest 1.40 on at least one side was considered indicative of the presence of LEAD (ABI+). Ischemia was defined as a minimal DROP (Limb-changes minus chest-changes from rest) value 2, age ≤ 64 years old, and a history of lower limb arterial revascularization, were associated to the presence of ischemia. The value of the score derived from these factors was associated with the probability of exercise-induced ischemia in the 507 patients with a history of LSS. This score may help to suspect the presence of ischemia as a factor of walking impairment in patients with a history of lumbar spinal stenosis

3D Photon-To-Digital Converter for Radiation Instrumentation: Motivation and Future Works

Analog and digital SiPMs have revolutionized the field of radiation instrumentation by replacing both avalanche photodiodes and photomultiplier tubes in many applications. However, multiple applications require greater performance than the current SiPMs are capable of, for example timing resolution for time-of-flight positron emission tomography and time-of-flight computed tomography, and mitigation of the large output capacitance of SiPM array for large-scale time projection chambers for liquid argon and liquid xenon experiments. In this contribution, the case will be made that 3D photon-to-digital converters, also known as 3D digital SiPMs, have a potentially superior performance over analog and 2D digital SiPMs. A review of 3D photon-to-digital converters is presented along with various applications where they can make a difference, such as time-of-flight medical imaging systems and low-background experiments in noble liquids. Finally, a review of the key design choices that must be made to obtain an optimized 3D photon-to-digital converter for radiation instrumentation, more specifically the single-photon avalanche diode array, the CMOS technology, the quenching circuit, the time-to-digital converter, the digital signal processing and the system level integration, are discussed in detail

3D Photon-To-Digital Converter for Radiation Instrumentation: Motivation and Future Works

Analog and digital SiPMs have revolutionized the field of radiation instrumentation by replacing both avalanche photodiodes and photomultiplier tubes in many applications. However, multiple applications require greater performance than the current SiPMs are capable of, for example timing resolution for time-of-flight positron emission tomography and time-of-flight computed tomography, and mitigation of the large output capacitance of SiPM array for large-scale time projection chambers for liquid argon and liquid xenon experiments. In this contribution, the case will be made that 3D photon-to-digital converters, also known as 3D digital SiPMs, have a potentially superior performance over analog and 2D digital SiPMs. A review of 3D photon-to-digital converters is presented along with various applications where they can make a difference, such as time-of-flight medical imaging systems and low-background experiments in noble liquids. Finally, a review of the key design choices that must be made to obtain an optimized 3D photon-to-digital converter for radiation instrumentation, more specifically the single-photon avalanche diode array, the CMOS technology, the quenching circuit, the time-to-digital converter, the digital signal processing and the system level integration, are discussed in detail

Questions d’éthique

Comme tout chercheur, l’ethnomusicologue se doit de respecter certains principes déontologiques en différentes phases de son activité, notamment la collecte, l’archivage, l’analyse, la communication et la publication. Comment la recherche a-t-elle évolué pour s’adapter aux conditions de terrains souvent marqués par les migrations, les conflits ou les tensions économiques et religieuses ? L’éthique du métier s’applique aussi aux droits des individus et des communautés produisant les musiques étudiées par les ethnomusicologues. Comment les instances internationales régulant le « patrimoine immatériel », sa « sauvegarde » ou encore la « propriété intellectuelle » (UNESCO, OMPI…) influent-t-elles sur la production des documents de recherche ? Comment ces différents facteurs contribuent-ils à redéfinir la relation enquêteur/enquêté ? Telles sont les questions auxquelles les ethnomusicologues sont constamment confrontés dans leur pratique, et sur lesquelles ce volume propose quelques pistes de réflexio

La géoarchéologie française au xxie siècle

La géoarchéologie s’impose aujourd’hui comme une composante majeure de la compréhension des interactions complexes Sociétés-Environnement sur le temps long. Cet ouvrage, le premier du genre, dresse un bilan des recherches géoarchéologiques conduites dans les universités, au CNRS (Centre National de la Recherche Scientifique), à l’INRAP (Institut National de Recherches Archéologiques Préventives) et dans les SRA (Services Régionaux de l’Archéologie) depuis trente ans. Les cinq parties de l’ouvrage étayent l’ensemble des champs d’application de la géoarchéologie française : « Paléoenvironnements, biogéographie et paysages » ; « Les hydrosystèmes fluviaux, entre climat et anthropisation » ; « Alluvionnement, peuplement, stratégies et formes d’adaptation » ; « Ressources en eau, risque et aménagement » ; « De la mobilité du trait de côte à la contrainte portuaire ». Une attention particulière est accordée aux attendus épistémologiques, aux concepts et aux méthodes d’investigation sur le « terrain » de la géoarchéologie moderne, par essence interdisciplinaire. Les sites archéologiques sont étudiés dans des contextes environnementaux variés : fluvial, deltaïque et littoral, zones humides, îles et environnements urbains. Chaque « grand chantier » présenté, qu’il se situe en France ou à l’étranger (Albanie, Égypte, Grèce, Italie, Luxembourg, Mali, Maroc, Turquie), fait état des dernières découvertes, des méthodes les plus pertinentes, des synthèses les plus à jour, des hypothèses les plus solides sur les interactions spécifiques entre l’Homme et son environnement depuis des milliers d’années. Conçu à partir d’une pratique forte du terrain, de l’enseignement et de la diffusion scientifique, ce livre s’adresse à un large public : enseignants, chercheurs, étudiants L-M-D, archéologie préventive, conservatoires du patrimoine, musées archéologiques, grand public curieux de connaissances pluridisciplinaires de son patrimoine archéologique replacé dans son contexte environnemental. L’étudiant y trouvera un véritable support de cours dispensés à l’Université et dans les écoles d’urbanisme, d’architecture et de paysage, le chercheur disposera d’un ouvrage exhaustif mettant en exergue des méthodes choisies et transposables à ses propres sites d’étude. L’ouvrage fait également valoir un engagement théorique, des choix d’approche et une perspective débouchant sur une meilleure connaissance de nos « patrimoines territoriaux », désormais pris en compte dans toute démarche d’aménagement (archéologie préventive). Cette connaissance est devenue « l’incontournable » du géographe, de l’urbaniste, de l’architecte, du paysagiste, du responsable de projet d’aménagement