6,589 research outputs found
Founder's lecture of the ISS 2006: borderlands of normal and early pathological findings in MRI of the foot and ankle
The purpose of this article is to highlight the anatomical variants, technical pitfalls, and the prevalence of abnormal conditions in the asymptomatic population in magnetic resonance imaging of the foot and ankle. Special attention is drawn to the complex anatomy of the deltoid ligament (the superficial tibionavicular ligament, tibiospring ligament, the tibiocalcaneal ligament, and the deep anterior and posterior tibiotalar ligaments) and the posterior tibial tendon insertion including the magic angle artifact and the high prevalence of asymptomatic findings such as "hypertrophied” peroneal tubercle (abnormal only when larger than 5mm), peroneus quartus (prevalence 17%), and cysts (vascular remnants) just inferior to the angle of Gissan
The CMS High Level Trigger: Commissioning and First Operation with LHC Beams
The CMS experiment will collect data from the proton-proton collisions
delivered by the Large Hadron Collider (LHC) at a centre-of-mass energy up to
14 TeV. The CMS trigger system is designed to cope with unprecedented
luminosities and LHC bunch-crossing rates up to 40 MHz. The unique CMS trigger
architecture only employs two trigger levels. The Level-1 trigger is
implemented using custom electronics. The High Level Trigger is implemented on
a large cluster of commercial processors, the Filter Farm. Trigger menus have
been developed for detector calibration and for fulfilment of the CMS physics
program, at start-up of LHC operations, as well as for operations with higher
luminosities. A complete multipurpose trigger menu developed for an early
instantaneous luminosity of 10^{32}cm{-2}s{-1} has been tested in the HLT
system under realistic online running conditions. The required computing power
needed to process with no dead time a maximum HLT input rate of 50 kHz, as
expected at startup, has been measured, using the most recent commercially
available processors. The Filter Farm has been equipped with 720 such
processors, providing a computing power at least a factor two larger than
expected to be needed at startup. Results for the commissioning of the
full-scale trigger and data acquisition system with cosmic muon runs are
reported. The trigger performance during operations with LHC circulating proton
beams, delivered in September 2008, is outlined and first results are shown.Comment: Published in the Proceedings of the IEEE Nuclear Science
Symposium,October 18-25, 2008,Dresden,German
Snake and spider toxins induce a rapid recovery of function of botulinum neurotoxin paralysed neuromuscular junction
Botulinum neurotoxins (BoNTs) and some animal neurotoxins (-Bungarotoxin, -Btx, from elapid snakes and -Latrotoxin, -Ltx, from black widow spiders) are pre-synaptic neurotoxins that paralyse motor axon terminals with similar clinical outcomes in patients. However, their mechanism of action is different, leading to a largely-different duration of neuromuscular junction (NMJ) blockade. BoNTs induce a long-lasting paralysis without nerve terminal degeneration acting via proteolytic cleavage of SNARE proteins, whereas animal neurotoxins cause an acute and complete degeneration of motor axon terminals, followed by a rapid recovery. In this study, the injection of animal neurotoxins in mice muscles previously paralyzed by BoNT/A or /B accelerates the recovery of neurotransmission, as assessed by electrophysiology and morphological analysis. This result provides a proof of principle that, by causing the complete degeneration, reabsorption, and regeneration of a paralysed nerve terminal, one could favour the recovery of function of a biochemically- or genetically-altered motor axon terminal. These observations might be relevant to dying-back neuropathies, where pathological changes first occur at the neuromuscular junction and then progress proximally toward the cell body
Role of MR imaging in chronic wrist pain
Magnetic resonance (MR) imaging for chronic wrist pain is challenging. Correct assessment of the triangular fibrocartilage, hyaline cartilage, ligaments, and tendons has become mandatory for comprehensive decision making in wrist surgery. The MR technique, potential and limits of MR imaging in patients with chronic wrist pain will be discussed. MR arthrography with injection of gadolinium-containing contrast material into the distal radioulnar joint is suggested for evaluation of the triangular fibrocartilage. The clinically meaningful ulnar-sided peripheral tears are otherwise hard to diagnose. The diagnostic performance of MR imaging for interosseous ligament tears varies considerably. The sensitivity for scapholunate ligament tears is consistently better than for lunotriquetral ligament tears. Gadolinium-enhanced MR imaging is considered to be the best technique for detecting established avascularity of bone, but the assessment of the MR results remains challenging. Most cases of ulnar impaction syndrome have characteristic focal signal intensity changes in the ulnar aspect of the lunate. Avascular necrosis of the lunate (Kienböck's disease) is characterized by signal changes starting in the proximal radial aspect of the lunate. MR imaging is extremely sensitive for occult fractures. Questions arise if occult posttraumatic bone lesions seen on MR images only necessarily require the same treatment as fractures evident on plain films or computed tomography (CT) images. MR imaging and ultrasound are equally effective for detecting occult carpal ganglia. Carpe bossu (carpal boss) is a bony protuberance of a carpometacarpal joint II and III which may be associated with pai
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