113 research outputs found
FlashCam: A fully digital camera for CTA telescopes
The future Cherenkov Telescope Array (CTA) will consist of several tens of
telescopes of different mirror sizes. CTA will provide next generation
sensitivity to very high energy photons from few tens of GeV to >100 TeV.
Several focal plane instrumentation options are currently being evaluated
inside the CTA consortium. In this paper, the current status of the FlashCam
prototyping project is described. FlashCam is based on a fully digital camera
readout concept and features a clean separation between photon detector plane
and signal digitization/triggering electronics.Comment: In Proceedings of the 2012 Heidelberg Symposium on High Energy
Gamma-Ray Astronomy. All CTA contributions at arXiv:1211.184
Six-minute walk distance after coronary artery bypass grafting compared with medical therapy in ischaemic cardiomyopathy
Background: In patients with ischaemic left ventricular dysfunction, coronary artery bypass surgery (CABG) may decrease mortality, but it is not known whether CABG improves functional capacity.
Objective: To determine whether CABG compared with medical therapy alone (MED) increases 6 min walk distance in patients with ischaemic left ventricular dysfunction and coronary artery disease amenable to revascularisation.
Methods: The Surgical Treatment in Ischemic Heart disease trial randomised 1212 patients with ischaemic left ventricular dysfunction to CABG or MED. A 6 min walk distance test was performed both at baseline and at least one follow-up assessment at 4, 12, 24 and/or 36 months in 409 patients randomised to CABG and 466 to MED. Change in 6 min walk distance between baseline and follow-up were compared by treatment allocation.
Results: 6 min walk distance at baseline for CABG was mean 340±117 m and for MED 339±118 m. Change in walk distance from baseline was similar for CABG and MED groups at 4 months (mean +38 vs +28 m), 12 months (+47 vs +36 m), 24 months (+31 vs +34 m) and 36 months (−7 vs +7 m), P>0.10 for all. Change in walk distance between CABG and MED groups over all assessments was also similar after adjusting for covariates and imputation for missing values (+8 m, 95% CI −7 to 23 m, P=0.29). Results were consistent for subgroups defined by angina, New York Heart Association class ≥3, left ventricular ejection fraction, baseline walk distance and geographic region.
Conclusion: In patients with ischaemic left ventricular dysfunction CABG compared with MED alone is known to reduce mortality but is unlikely to result in a clinically significant improvement in functional capacity
FlashCam: a fully-digital camera for the medium-sized telescopes of the Cherenkov Telescope Array
The FlashCam group is currently preparing photomultiplier-tube based cameras
proposed for the medium-sized telescopes (MST) of the Cherenkov Telescope Array
(CTA). The cameras are designed around the FlashCam readout concept which is
the first fully-digital readout system for Cherenkov cameras, based on
commercial FADCs and FPGAs as key components for the front-end electronics
modules and a high performance camera server as back-end. This contribution
describes the progress of the full-scale FlashCam camera prototype currently
under construction, as well as performance results also obtained with earlier
demonstrator setups. Plans towards the production and implementation of
FlashCams on site are also briefly presented.Comment: 8 pages, 6 figures. In Proceedings of the 34th International Cosmic
Ray Conference (ICRC2015), The Hague, The Netherlands. All CTA contributions
at arXiv:1508.0589
Performance Verification of the FlashCam Prototype Camera for the Cherenkov Telescope Array
The Cherenkov Telescope Array (CTA) is a future gamma-ray observatory that is
planned to significantly improve upon the sensitivity and precision of the
current generation of Cherenkov telescopes. The observatory will consist of
several dozens of telescopes with different sizes and equipped with different
types of cameras. Of these, the FlashCam camera system is the first to
implement a fully digital signal processing chain which allows for a traceable,
configurable trigger scheme and flexible signal reconstruction. As of autumn
2016, a prototype FlashCam camera for the medium-sized telescopes of CTA nears
completion. First results of the ongoing system tests demonstrate that the
signal chain and the readout system surpass CTA requirements. The stability of
the system is shown using long-term temperature cycling.Comment: 5 pages, 13 figures, Proceedings of the 9th International Workshop on
Ring Imaging Cherenkov Detectors (RICH 2016), Lake Bled, Sloveni
Evaluation of Single-Chip, Real-Time Tomographic Data Processing on FPGA - SoC Devices
A novel approach to tomographic data processing has been developed and
evaluated using the Jagiellonian PET (J-PET) scanner as an example. We propose
a system in which there is no need for powerful, local to the scanner
processing facility, capable to reconstruct images on the fly. Instead we
introduce a Field Programmable Gate Array (FPGA) System-on-Chip (SoC) platform
connected directly to data streams coming from the scanner, which can perform
event building, filtering, coincidence search and Region-Of-Response (ROR)
reconstruction by the programmable logic and visualization by the integrated
processors. The platform significantly reduces data volume converting raw data
to a list-mode representation, while generating visualization on the fly.Comment: IEEE Transactions on Medical Imaging, 17 May 201
Kappa free light chains is a valid tool in the diagnostics of MS: A large multicenter study
To validate kappa free light chain (KFLC) and lambda free light chain (LFLC) indices as a diagnostic biomarker in multiple sclerosis (MS).We performed a multicenter study including 745 patients from 18 centers (219 controls and 526 clinically isolated syndrome (CIS)/MS patients) with a known oligoclonal IgG band (OCB) status. KFLC and LFLC were measured in paired cerebrospinal fluid (CSF) and serum samples. Gaussian mixture modeling was used to define a cut-off for KFLC and LFLC indexes.The cut-off for the KFLC index was 6.6 (95% confidence interval (CI) = 5.2-138.1). The cut-off for the LFLC index was 6.9 (95% CI = 4.5-22.2). For CIS/MS patients, sensitivity of the KFLC index (0.88; 95% CI = 0.85-0.90) was higher than OCB (0.82; 95%CI = 0.79-0.85; p < 0.001), but specificity (0.83; 95% CI = 0.78-0.88) was lower (OCB = 0.92; 95% CI = 0.89-0.96; p < 0.001). Both sensitivity and specificity for the LFLC index were lower than OCB.Compared with OCB, the KFLC index is more sensitive but less specific for diagnosing CIS/MS. Lacking an elevated KFLC index is more powerful for excluding MS compared with OCB but the latter is more important for ruling in a diagnosis of CIS/MS
Performance of a small size telescope (SST-1M) camera for gamma-ray astronomy with the Cherenkov Telescope Array
The foreseen implementations of the Small Size Telescopes (SST) in CTA will
provide unique insights into the highest energy gamma rays offering fundamental
means to discover and under- stand the sources populating the Galaxy and our
local neighborhood. Aiming at such a goal, the SST-1M is one of the three
different implementations that are being prototyped and tested for CTA. SST-1M
is a Davies-Cotton single mirror telescope equipped with a unique camera
technology based on SiPMs with demonstrated advantages over classical
photomultipliers in terms of duty-cycle. In this contribution, we describe the
telescope components, the camera, and the trigger and readout system. The
results of the commissioning of the camera using a dedicated test setup are
then presented. The performances of the camera first prototype in terms of
expected trigger rates and trigger efficiencies for different night-sky
background conditions are presented, and the camera response is compared to
end-to-end simulations.Comment: All CTA contributions at arXiv:1709.0348
Development of a strategy for calibrating the novel SiPM camera of the SST-1M telescope proposed for the Cherenkov Telescope Array
CTA will comprise a sub-array of up to 70 small size telescopes (SSTs) at the
southern array. The SST-1M project, a 4 m-diameter Davies Cotton telescope with
9 degrees FoV and a 1296 pixels SiPM camera, is designed to meet the
requirements of the next generation ground based gamma-ray observatory CTA in
the energy range above 3 TeV. Silicon photomultipliers (SiPM) cameras of
gamma-ray telescopes can achieve good performance even during high night sky
background conditions. Defining a fully automated calibration strategy of SiPM
cameras is of great importance for large scale production validation and online
calibration. The SST-1M sub-consortium developed a software compatible with CTA
pipeline software (CTApipe). The calibration of the SST-1M camera is based on
the Camera Test Setup (CTS), a set of LED boards mounted in front of the
camera. The CTS LEDs are operated in pulsed or continuous mode to emulate
signal and night sky background respectively. Continuous and pulsed light data
analysis allows us to extract single pixel calibration parameters to be used
during CTA operation.Comment: All CTA contributions at arXiv:1709.0348
Control Software for the SST-1M Small-Size Telescope prototype for the Cherenkov Telescope Array
The SST-1M is a 4-m Davies--Cotton atmospheric Cherenkov telescope optimized
to provide gamma-ray sensitivity above a few TeV. The SST-1M is proposed as
part of the Small-Size Telescope array for the Cherenkov Telescope Array (CTA),
the first prototype has already been deployed. The SST-1M control software of
all subsystems (active mirror control, drive system, safety system,
photo-detection plane, DigiCam, CCD cameras) and the whole telescope itself
(master controller) uses the standard software design proposed for all CTA
telescopes based on the ALMA Common Software (ACS) developed to control the
Atacama Large Millimeter Array (ALMA). Each subsystem is represented by a
separate ACS component, which handles the communication to and the operation of
the subsystem. Interfacing with the actual hardware is performed via the OPC UA
communication protocol, supported either natively by dedicated industrial
standard servers (PLCs) or separate service applications developed to wrap
lower level protocols (e.g. CAN bus, camera slow control) into OPC UA. Early
operations of the telescope without the camera were already carried out. The
camera is fully assembled and is capable to perform data acquisition using
artificial light source.Comment: In Proceedings of the 35th International Cosmic Ray Conference
(ICRC2017), Busan, Korea. All CTA contributions at arXiv:1709.0348
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