A. Bruni

Cathepsin F mutations cause Type B Kufs disease, an adult-onset neuronal ceroid lipofuscinosis

Kufs disease, an adult-onset neuronal ceroid lipofuscinosis, is challenging to diagnose and genetically heterogeneous. Mutations in CLN6 were recently identified in recessive Kufs disease presenting as progressive myoclonus epilepsy (Type A), whereas the molecular basis of cases presenting with dementia and motor features (Type B) is unknown. We performed genome-wide linkage mapping of two families with recessive Type B Kufs disease and identified a single region on chromosome 11 to which both families showed linkage. Exome sequencing of five samples from the two families identified homozygous and compound heterozygous missense mutations in CTSF within this linkage region. We subsequently sequenced CTSF in 22 unrelated individuals with suspected recessive Kufs disease, and identified an additional patient with compound heterozygous mutations. CTSF encodes cathepsin F, a lysosomal cysteine protease, dysfunction of which is a highly plausible candidate mechanism for a storage disorder like ceroid lipofuscinosis. In silico modeling suggested the missense mutations would alter protein structure and function. Moreover, re-examination of a previously published mouse knockout of Ctsf shows that it recapitulates the light and electron-microscopic pathological features of Kufs disease. Although CTSF mutations account for a minority of cases of type B Kufs, CTSF screening should be considered in cases with early-onset dementia and may avoid the need for invasive biopsies.

A high resolution, low power time-of-flight system for the space experiment AMS

The system of plastic scintillator counters for the AMS experiment is described. The main characteristics of the detector are: (a) large sensitive area (four 1.6 m2 planes) with small dead space; (b) low-power consumption (150 W for the power and the read-out electronics of 336 PMs); (c) 120 ps time resolution. ( 1999 Elsevier Science B.V. All rights reserved.

The ATLAS LVL1 Barrel Muon Trigger Commissioning with Cosmic Rays

The ATLAS muon spectrometer, currently in the installation phase, uses dedicated detectors to be able to trigger on high transverse momentum muons in the range 6-20 GeV/c resistive plate chambers (RPC) are equipping the barrel region in the middle and outer station, while precision chambers (monitored drift tubes, MDT) are present also in the inner layer. The RPCs have the required timing and spatial resolution of about 2 ns times 1 cm, to be able to associate the muon to the correct bunch crossing and provide the second coordinate measurements to the MDTs. In order to successfully commission the chambers, cosmic runs are taken to check and validate the readout and trigger chain, and cosmic rates are measured and compared against values obtained with a cosmic ray Monte Carlo generator and full detector simulation. The first part of the detector under commission is the set of horizontal chambers positioned between the feet of the detector. The first results obtained in the ATLAS cavern will be presented. The first cosmic data taking collects signals from chambers arranged in six trigger towers, covering about one quarter of the full detector length. The experience gained on this small part of the detector will be very useful to define the commissioning work for the whole detector.

Study of the performances of the level-1 trigger system for muons in the barrel of ATLAS with cosmic rays

The muon trigger in ATLAS is crucial for all the main physics channels to be studied at the design center of mass energy and luminosity of LHC and also for the initial phase of data taking with beams for the calibration of all the detectors. The level-1 trigger system for muons in ATLAS is performed using dedicated RPC chambers in the |η| ≪ 1 region. The trigger electronics provides both trigger and readout information. This system is being commissioned using cosmic rays with the full trigger and data acquisition chains. Monitoring tools have been developed in order to spot problems during data taking and determine the quality of the data and the trigger performance. Moreover, using the data taken during the commissioning phase, with partial availability of the detector, some studies have been performed to allow the optimization of the trigger system, based on different choises of the configuration parameters, also as a function of the detector working point. In this paper we would like to describe the extensive tests performed on the system and illustrate the possible performances with different conditions.