Detector readout systems for medium- to large-scale physics experiments, and instruments in some other fields as well, are generally composed of multiple front-end digitizer boards distributed over a ...certain area. Often, this hardware has to be synchronized to a common reference clock with minimal skew and low jitter. Today's mainstream solutions to precise clock distribution and deterministic latency messaging rely on the capabilities of high-speed serial transceivers (a.k.a. SerDes) embedded in modern field-programmable gate arrays (FPGAs). An alternative option uses distinct clock and data links. This can potentially reach higher synchronization accuracy, at significant hardware expenses. This work reports some first steps to explore a third scheme for clock and synchronous message distribution. Like the standard approach, the same medium is used to convey clock and data, but instead of using today's "data-centric" links where the recovered clock is only a by-product of a SerDes, this article defines and investigates "clock-centric" links where, at the opposite, a clock is carried by the link, and synchronous data are embedded into it by a modulation technique. After defining the concepts and principles of data-centric links, experimental studies are presented. Finally, the merits and limitations of the proposed approach are discussed.
The detector readout architecture introduced in this paper is intended for small to medium size physics experiments that have moderate bandwidth needs and applications that only tolerate an ...ultimately low background radioactivity for the parts close to the detector. The first idea to simplify the readout system and minimize the material budget is to use a common fan-out structure to transport from off-detector back-end electronics to the front ends all the traffic required for the synchronization, configuration, and readout. The second idea is to use between each front-end card and the back-end electronics a point-to-point link that runs at the relatively low speed that suffices for the target application. This broadens the possible choices of physical media, e.g., glass fiber, plastic optical fiber, or copper. This paper presents a communication protocol adequate for the proposed asymmetric network. It shows the design of a back-end unit capable of controlling 32 front-end units at up to 12.8 Gb/s of aggregate bandwidth. This back-end unit uses an inexpensive commercial field-programmable gate array (FPGA) module where a large number of regular I/O pins interface to the front-end links, while the few available multigigabit per second capable transceivers are assigned to the communication with the upper stage of the data acquisition (DAQ) system.
Ischemic stroke is not rare in young adults since one in ten stroke patients are less than 50 years old. This incidence increased over the past last years, mainly due to the rise in the prevalence of ...traditional vascular risk factors in this sub-group of age but also of illegal drug use. Even though both survival and functional outcome of young stroke patients are better than those observed in older patients, socio-economic and quality of life consequences make this disease a main objective in terms of primary and secondary prevention. Identifying the cause of ischemic stroke in young adults is of major importance to prevent stroke recurrence. However, given the wide variety of potential underlying causes, the etiologic work-up of stroke in young adults requires a different approach from that in the elderly. In this context, a sequential diagnostic work-up is needed in order to optimize the yield of diagnostic tests, to reduce their cost and risks for the patient. Arterial dissection is the most frequent cause of stroke in young adults but other less frequent causes are numerous. Despite a comprehensive work-up, about one third of cases remains unexplained leading to the diagnosis of cryptogenic ischemic stroke.
Infarctus cérébral du sujet jeune Calvet, D.
La revue de medecine interne,
January 2016, 2016-01-00, Letnik:
37, Številka:
1
Journal Article
Recenzirano
L’infarctus cérébral chez le sujet jeune n’est pas rare puisqu’un patient sur 10 ayant un infarctus cérébral a moins de 50ans. Cette incidence a augmenté ces dernières années du fait de la hausse de ...la prévalence des facteurs de risque vasculaire traditionnels mais aussi du fait de l’augmentation de la consommation de substances illicites dans cette catégorie d’âge. Bien que le pronostic vital et fonctionnel soit meilleur que celui des patients plus âgés, les conséquences socio-économiques en termes de qualité de vie font de cette pathologie un enjeu majeur de prévention primaire et secondaire. Dans un objectif de prévention secondaire, l’identification de la cause est un enjeu majeur. Cependant, du fait de la multiplicité des causes potentielles, il est important, chez les patients jeunes ayant eu un infarctus cérébral, de suivre une démarche diagnostique permettant d’établir une hiérarchie parmi les nombreux examens complémentaires existants afin d’en optimiser le rendement et d’en réduire les risques et le coût. Une dissection des artères cervicales est la cause la plus souvent rencontrée mais les autres causes moins fréquentes sont nombreuses. Cependant, en dépit d’un bilan étiologique détaillé, la cause de l’infarctus cérébral reste indéterminée dans 1/3 des cas. On parle alors d’infarctus cérébral cryptogénique.
Ischemic stroke is not rare in young adults since one in ten stroke patients are less than 50years old. This incidence increased over the past last years, mainly due to the rise in the prevalence of traditional vascular risk factors in this sub-group of age but also of illegal drug use. Even though both survival and functional outcome of young stroke patients are better than those observed in older patients, socio-economic and quality of life consequences make this disease a main objective in terms of primary and secondary prevention. Identifying the cause of ischemic stroke in young adults is of major importance to prevent stroke recurrence. However, given the wide variety of potential underlying causes, the etiologic work-up of stroke in young adults requires a different approach from that in the elderly. In this context, a sequential diagnostic work-up is needed in order to optimize the yield of diagnostic tests, to reduce their cost and risks for the patient. Arterial dissection is the most frequent cause of stroke in young adults but other less frequent causes are numerous. Despite a comprehensive work-up, about one third of cases remains unexplained leading to the diagnosis of cryptogenic ischemic stroke.
This paper reports about the first Micromegas-based telescope built for applications in muon tomography. The telescope consists of four, 50×50cm2 resistive multiplexed Micromegas with a 2D layout and ...a self-triggering electronics based on the Dream chip. Thanks to the multiplexing, the four detectors were readout with a single Front-End Unit. The high voltages were provided by a dedicated card using low consumption CAEN miniaturized modules. A nano-PC (Hummingboard) ensured the HV control and monitoring coupled with a temperature feedback as well as the data acquisition and storage. The overall consumption of the instrument yielded 30W only, i.e. the equivalent of a standard bulb. The telescope was operated outside during 3.5months to image the water tower of the CEA-Saclay research center, including a 1.5-month campaign with solar panels. The development of autonomous, low consumption muon telescopes with unprecedented accuracy opens new applications in imaging as well as in the field of muon metrology.
Objective To decrease the procedural risk of carotid revascularisation it is crucial to understand the mechanisms of procedural stroke. This study analysed the features of procedural strokes ...associated with carotid artery stenting (CAS) and carotid endarterectomy (CEA) within the International Carotid Stenting Study (ICSS) to identify the underlying pathophysiological mechanism. Materials and methods Patients with recently symptomatic carotid stenosis (1,713) were randomly allocated to CAS or CEA. Procedural strokes were classified by type (ischaemic or haemorrhagic), time of onset (intraprocedural or after the procedure), side (ipsilateral or contralateral), severity (disabling or non-disabling), and patency of the treated artery. Only patients in whom the allocated treatment was initiated were included. The most likely pathophysiological mechanism was determined using the following classification system: (1) carotid-embolic, (2) haemodynamic, (3) thrombosis or occlusion of the revascularised carotid artery, (4) hyperperfusion, (5) cardio-embolic, (6) multiple, and (7) undetermined. Results Procedural stroke occurred within 30 days of revascularisation in 85 patients (CAS 58 out of 791 and CEA 27 out of 819). Strokes were predominately ischaemic (77; 56 CAS and 21 CEA), after the procedure (57; 37 CAS and 20 CEA), ipsilateral to the treated artery (77; 52 CAS and 25 CEA), and non-disabling (47; 36 CAS and 11 CEA). Mechanisms of stroke were carotid-embolic (14; 10 CAS and 4 CEA), haemodynamic (20; 15 CAS and 5 CEA), thrombosis or occlusion of the carotid artery (15; 11 CAS and 4 CEA), hyperperfusion (9; 3 CAS and 6 CEA), cardio-embolic (5; 2 CAS and 3 CEA) and multiple causes (3; 3 CAS). In 19 patients (14 CAS and 5 CEA) the cause of stroke remained undetermined. Conclusion Although the mechanism of procedural stroke in both CAS and CEA is diverse, haemodynamic disturbance is an important mechanism. Careful attention to blood pressure control could lower the incidence of procedural stroke.
Why do we flush gas in gaseous detectors? Procureur, S.; Attié, D.; Bouteille, S. ...
Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment,
03/2020, Letnik:
955
Journal Article
Recenzirano
Odprti dostop
The effects and the origin of the gas degradation in a gaseous detector-based tracker are investigated. The study focused on the so-called T2K gas, which turned out to be highly sensitive to ...pollutants. In particular the H2O and O2 concentrations were monitored online in different conditions to establish their influence on the gain of the detectors. This pollution was first mitigated by a recirculating and accelerating gas system with the use of a turbine and different absorbers. Further measurements revealed that this pollution originates from a continuous permeation process through the different materials of the gas circuit. In particular, polyurethane-based gas pipes or polyester materials largely increase the level of humidity. As a direct consequence of this work, the gas autonomy of the muon telescopes currently deployed inside the Khufu’s pyramid have been dramatically improved.
For measuring gamma rays from low energy to high energy and cover the gap between 1 MeV and 300 MeV in space measurements, Time Projection Chambers (TPC) are a promising solution. In order to read ...the data out of these TPCs, one needs a dedicated electronics to be flexible to cover a wide range of detectors types, with a good resolution over a large dynamic range of incoming charges. The ASTRE chip, a radiation tolerant chip for these applications is described in this article. This Application Specified Integrated Circuit (ASIC) permits the amplification, filtering, triggering and analog storage of 512 samples at a flexible sampling frequency up to 100 MHz. The power consumption is less than 10 mW/channel, with 64 channels per ASIC. The charge range of ASTRE is from 120 fC to 10 pC with 4 programmable gains. The filtering supports 16 peaking times (from 60 ns to 8μs). The ASIC can read negative or positive signals and return a multiplicity signal for triggering and selective readout. In addition it has a programmable internal trigger readable with Low Differential Voltage Signal (LVDS) outputs. The chip was fabricated in August 2016 and is under test. The results of this ASIC to Single Event Latchups, made at the Universite Catholique de Louvain (UCL) are detailed below.
Randomized clinical trials show higher 30-day risk of stroke or death after carotid artery stenting compared with surgery. We examined whether operator experience is associated with 30-day risk of ...stroke or death in the Carotid Stenting Trialists' Collaboration database.
The Carotid Stenting Trialists' Collaboration is a pooled individual patient database including all patients recruited in 3 randomized trials of stenting versus endarterectomy for symptomatic carotid stenosis (Endarterectomy Versus Angioplasty in patients with Symptomatic Severe Carotid Stenosis trial, Stent-Protected Angioplasty versus Carotid Endarterectomy trial, and International Carotid Stenting Study). Lifetime carotid artery stenting experience, lifetime experience in stenting procedures excluding the carotid, and annual number of procedures performed within the trial (in-trial volume), divided into tertiles, were used to measure operator experience. The outcome event was the occurrence of any stroke or death within 30 days of the procedure. The analysis was done per protocol.
Among 1546 patients who underwent carotid artery stenting, 120 (7.8%) had a stroke or death within 30 days of the procedure. The 30-day risk of stroke or death did not differ according to operator lifetime carotid artery stenting experience (P=0.8) or operator lifetime stenting experience excluding the carotid (P=0.7). In contrast, the 30-day risk of stroke or death was significantly higher in patients treated by operators with low (mean ≤3.2 procedures/y; risk 10.1%; adjusted risk ratio=2.30 1.36-3.87) and intermediate annual in-trial volumes (3.2-5.6 procedures/y; 8.4%; adjusted risk ratio=1.93 1.14-3.27) compared with patients treated by high annual in-trial volume operators (>5.6 procedures/y; 5.1%).
Carotid stenting should only be performed by operators with annual procedure volume ≥6 cases per year.
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