5,668 research outputs found
A Statistical Prescription to Estimate Properly Normalized Distributions of Different Particle Species
We describe a statistical method to avoid biased estimation of the content of
different particle species. We consider the case when the particle
identification information strongly depends on some kinematical variables,
whose distributions are unknown and different for each particles species. We
show that the proposed procedure provides properly normalized and completely
data-driven estimation of the unknown distributions without any a priori
assumption on their functional form. Moreover, we demonstrate that the method
can be generalized to any kinematical distribution of the particles
Surface displacement of the Mw 7 Machaze earthquake (Mozambique): Complementary use of multiband InSAR and radar amplitude image correlation with elastic modelling.
International audienceIn this paper we investigate the surface displacement related to the 2006 Machaze earthquake using Synthetic Aperture Radar Interferometry (InSAR) and sub-pixel correlation (SPC) of radar amplitude images. We focus on surface displacement measurement during three stages of the seismic cycle. First, we examined the co-seismic stage, using an Advanced SAR (ASAR) sensor onboard the Envisat satellite. Then we investigated the post-seismic stage using the Phase Array L-band SAR sensor (PALSAR) onboard the ALOS satellite. Lastly, we focussed on the inter-seismic stage, prior to the earthquake by analysing the L20 and JERS-1 SAR data. The high degree of signal decorrelation in the C-band co-seismic interferogram hinders a correct positioning of the surface rupture and correct phase unwrapping. The post-seismic L-band interferograms reveal a time-constant surface displacement, causing subsidence of the surface at a ~ 5 cm/yr rate. This phenomenon continued to affect the close rupture field for at least two years following the earthquake and intrinsically reveals a candidate seismogenic fault trace that we use as a proxy for an inversion against an elastic dislocation model. Prior to the earthquake, the JERS interferograms do not indicate any traces of pre-seismic slip on the sismogenic fault. Therefore, slip after the earthquake is post seismic, and it was triggered by the Machaze earthquake. This feature represents a prominent post-seismic slip event rarely observed in such a geodynamic context
Simulation and performance of an artificial retina for 40 MHz track reconstruction
We present the results of a detailed simulation of the artificial retina
pattern-recognition algorithm, designed to reconstruct events with hundreds of
charged-particle tracks in pixel and silicon detectors at LHCb with LHC
crossing frequency of . Performances of the artificial retina
algorithm are assessed using the official Monte Carlo samples of the LHCb
experiment. We found performances for the retina pattern-recognition algorithm
comparable with the full LHCb reconstruction algorithm.Comment: Final draft of WIT proceedings modified according to JINST referee's
comment
The artificial retina for track reconstruction at the LHC crossing rate
We present the results of an R&D study for a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel and silicon strip detectors at , thus suitable for
processing LHC events at the full crossing frequency. For this purpose we
design and test a massively parallel pattern-recognition algorithm, inspired to
the current understanding of the mechanisms adopted by the primary visual
cortex of mammals in the early stages of visual-information processing. The
detailed geometry and charged-particle's activity of a large tracking detector
are simulated and used to assess the performance of the artificial retina
algorithm. We find that high-quality tracking in large detectors is possible
with sub-microsecond latencies when the algorithm is implemented in modern,
high-speed, high-bandwidth FPGA devices.Comment: 3 pages, 3 figures, ICHEP14. arXiv admin note: text overlap with
arXiv:1409.089
A Specialized Processor for Track Reconstruction at the LHC Crossing Rate
We present the results of an R&D study of a specialized processor capable of
precisely reconstructing events with hundreds of charged-particle tracks in
pixel detectors at 40 MHz, thus suitable for processing LHC events at the full
crossing frequency. For this purpose we design and test a massively parallel
pattern-recognition algorithm, inspired by studies of the processing of visual
images by the brain as it happens in nature. We find that high-quality tracking
in large detectors is possible with sub-s latencies when this algorithm is
implemented in modern, high-speed, high-bandwidth FPGA devices. This opens a
possibility of making track reconstruction happen transparently as part of the
detector readout.Comment: Presented by G.Punzi at the conference on "Instrumentation for
Colliding Beam Physics" (INSTR14), 24 Feb to 1 Mar 2014, Novosibirsk, Russia.
Submitted to JINST proceeding
First prototype of a silicon tracker using an artificial retina for fast track finding
We report on the R\&D for a first prototype of a silicon tracker based on an
alternative approach for fast track finding. The working principle is inspired
from neurobiology, in particular by the processing of visual images by the
brain as it happens in nature. It is based on extensive parallelisation of data
distribution and pattern recognition. In this work we present the design of a
practical device that consists of a telescope based on single-sided silicon
detectors; we describe the data acquisition system and the implementation of
the track finding algorithms using available digital logic of commercial FPGA
devices. Tracking performance and trigger capabilities of the device are
discussed along with perspectives for future applications.Comment: 9 pages, 7 figures, Technology and Instrumentation in Particle
Physics 2014 (TIPP 2014), conference proceeding
The artificial retina processor for track reconstruction at the LHC crossing rate
We present results of an R&D study for a specialized processor capable of
precisely reconstructing, in pixel detectors, hundreds of charged-particle
tracks from high-energy collisions at 40 MHz rate. We apply a highly parallel
pattern-recognition algorithm, inspired by studies of the processing of visual
images by the brain as it happens in nature, and describe in detail an
efficient hardware implementation in high-speed, high-bandwidth FPGA devices.
This is the first detailed demonstration of reconstruction of offline-quality
tracks at 40 MHz and makes the device suitable for processing Large Hadron
Collider events at the full crossing frequency.Comment: 4th draft of WIT proceedings modified according to JINST referee's
comments. 10 pages, 6 figures, 2 table
Progression of motor subtypes in Huntington’s disease. a 6-year follow-up study
The objective of this study is to investigate the progression of predominantly choreatic and hypokinetic-rigid signs in Huntington's disease (HD) and their relationship with cognitive and general functioning over time. The motor signs in HD can be divided into predominantly choreatic and hypokinetic-rigid subtypes. It has been reported in cross-sectional studies that predominantly choreatic HD patients perform better on functional and cognitive assessments compared to predominantly hypokinetic-rigid HD patients. The course of these motor subtypes and their clinical profiles has not been investigated longitudinally. A total of 4135 subjects who participated in the European HD Network REGISTRY study were included and classified at baseline as either predominantly choreatic (n = 891), hypokinetic-rigid (n = 916), or mixed-motor (n = 2328), based on a previously used method. The maximum follow-up period was 6 years. The mixed-motor group was not included in the analyses. Linear mixed models were constructed to investigate changes in motor subtypes over time and their relationship with cognitive and functional decline. Over the 6-year follow-up period, the predominantly choreatic group showed a significant decrease in chorea, while hypokinetic-rigid symptoms slightly increased in the hypokinetic-rigid group. On the Total Functional Capacity, Stroop test, and Verbal fluency task the rate of change over time was significantly faster in the predominantly choreatic group, while on all other clinical assessments the decline was comparable for both groups. Our results suggest that choreatic symptoms decrease over time, whereas hypokinetic-rigid symptoms slightly increase in a large cohort of HD patients. Moreover, different motor subtypes can be related to different clinical profiles
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