Objectives
To compare the efficacy of natalizumab or fingolimod in a nationwide observational cohort using prospectively collected data.
Materials and methods
We included all patients starting ...treatment with natalizumab or fingolimod documented in the Austrian MS Treatment Registry (AMSTR) from 2011 and staying on therapy for at least 24 months. We used propensity scores for several matching methods and as a covariate in multivariate models to correct for the bias of this non‐randomized registry study.
Results
The study cohort includes 588 patients with RRMS. Ten patients did not produce a propensity score in the common support region, thus leaving 578 cases for final analyses, 332 in the fingolimod and 246 in the natalizumab group. Mean annualized relapse rates (ARR) during the 24 months observation period were 0.19 under fingolimod and 0.12 under natalizumab treatment (P = .005). No statistical significant differences were found analysing the log‐transformed ARR, probability for experiencing a relapse, EDSS progression and EDSS regression. The hazard ratio for switching treatment from fingolimod comparing with natalizumab was 0.36 (95% CI: 0.247‐0.523), P < .001.
Conclusions
The generalized linear model (GLM) for relapse count as Poisson distributed dependent variable and propensity score as covariate showed a statistically significant reduction for the mean relapse count in the natalizumab group compared with fingolimod. This effect was smaller in the analyses of log‐transformed ARR with propensity score matching, loosing statistical significance although showing the same direction for the effect. We assume that the GLM was the more sensitive model analysing this question.
The ALICE High Level Trigger comprises a large computing cluster, dedicated interfaces and software applications. It allows on-line event reconstruction of the full data stream of the ALICE ...experiment at up to 25 GByte/s. The commissioning campaign has passed an important phase since the startup of the Large Hadron Collider in November 2009. The system has been transferred into continuous operation with focus on the event reconstruction and first simple trigger applications. The paper reports for the first time on the achieved event reconstruction performance in the ALICE central barrel region.
ALICE HLT High Speed Tracking on GPU Gorbunov, S.; Rohr, D.; Aamodt, K. ...
IEEE transactions on nuclear science,
08/2011, Letnik:
58, Številka:
4
Journal Article
Recenzirano
The on-line event reconstruction in ALICE is performed by the High Level Trigger, which should process up to 2000 events per second in proton-proton collisions and up to 300 central events per second ...in heavy-ion collisions, corresponding to an input data stream of 30 GB/s. In order to fulfill the time requirements, a fast on-line tracker has been developed. The algorithm combines a Cellular Automaton method being used for a fast pattern recognition and the Kalman Filter method for fitting of found trajectories and for the final track selection. The tracker was adapted to run on Graphics Processing Units (GPU) using the NVIDIA Compute Unified Device Architecture (CUDA) framework. The implementation of the algorithm had to be adjusted at many points to allow for an efficient usage of the graphics cards. In particular, achieving a good overall workload for many processor cores, efficient transfer to and from the GPU, as well as optimized utilization of the different memories the GPU offers turned out to be critical. To cope with these problems a dynamic scheduler was introduced, which redistributes the workload among the processor cores. Additionally a pipeline was implemented so that the tracking on the GPU, the initialization and the output processed by the CPU, as well as the DMA transfer can overlap. The GPU tracking algorithm significantly outperforms the CPU version for large events while it entirely maintains its efficiency.
Galois fields (also called finite fields) play an essential role in the areas of cryptography and coding theory. They are the foundation of various error- and erasure-correcting codes and therefore ...central to the design of reliable storage systems. The efficiency and performance of these systems depend considerably on the implementation of Galois field arithmetic, in particular on the implementation of the multiplication. In current software implementations multiplication is typically performed by using pre-calculated lookup tables for the logarithm and its inverse or even for the full multiplication result. However, today the memory subsystem has become one of the main bottlenecks in commodity systems and relying on large in-memory data structures accessed from inner loop code can severely impact the overall performance and deteriorate scalability. In this paper, we study the execution of Galois field multiplication on modern processor architectures without using lookup tables. Instead we propose to trade computation for memory references and, therefore, to perform full polynomial multiplication with modular reduction using the generator polynomial of the Galois field. We present a SIMDized (vectorized) implementation of the polynomial multiplication algorithm in GF(2^16) and show the performance on commodity processors and on GPGPU accelerators.
ALICE (A Large Ion Collider Experiment) is a detector dedicated to the studies with heavy ion collisions exploring the physics of strongly interacting nuclear matter and the quark-gluon plasma at the ...CERN LHC (Large Hadron Collider). After the second long shutdown of the LHC, the ALICE Experiment will be upgraded to make high precision measurements of rare probes at low pT, which cannot be selected with a trigger, and therefore require a very large sample of events recorded on tape. The online computing system will be completely redesigned to address the major challenge of sampling the full 50 kHz Pb-Pb interaction rate increasing the present limit by a factor of 100. This upgrade will also include the continuous un-triggered read-out of two detectors: ITS (Inner Tracking System) and TPC (Time Projection Chamber)) producing a sustained throughput of 1 TB/s. This unprecedented data rate will be reduced by adopting an entirely new strategy where calibration and reconstruction are performed online, and only the reconstruction results are stored while the raw data are discarded. This system, already demonstrated in production on the TPC data since 2011, will be optimized for the online usage of reconstruction algorithms. This implies much tighter coupling between online and offline computing systems. An R&D program has been set up to meet this huge challenge. The object of this paper is to present this program and its first results.
The ALICE High Level Trigger comprises a large computing cluster, dedicated interfaces and software applications. It allows on-line event reconstruction of the full data stream of the ALICE ...experiment at up to 25 GByte/s. The commissioning campaign has passed an important phase since the startup of the Large Hadron Collider in November 2009. The system has been transferred into continuous operation with focus on the event reconstruction and first simple trigger applications. The paper reports for the first time on the achieved event reconstruction performance in the ALICE central barrel region.
The ALICE High Level Trigger (HLT) is designed to perform event analysis of heavy ion and proton-proton collisions as well as calibration calculations online. A large PC farm, currently under ...installation, enables analysis algorithms to process these computationally intensive tasks. The HLT receives event data from all major detectors in ALICE. Interfaces to the various other systems provide the analysis software with required additional information. Processed results are sent back to the corresponding systems. To allow online performance monitoring of the detectors an interface for visualizing these results has been developed.
Computers are essential in research and industry, but they are also significant contributors to the worldwide power consumption. The LOEWE-CSC supercomputer addresses this problem by setting new ...standards in environmental compatibility as well as energy and cooling efficiency for high-performance and general-purpose computing. Designing a pervasively energy efficient compute center requires improvements in multiple fields. The hosting low-loss compute-center operates at a cooling overhead below 8% of the computer power. General purpose graphics processing units provide more compute performance per watt than standard processors. A balanced hardware configuration ensures that most of the compute power is available to the user when he employs optimized applications. Clever algorithms enable the user to fully exploit the computational potential and avoids to waste power when the processors idles, which is often a cause of inefficient programming. The LOEWE-CSC operated at 740MFlops/W during a Linpack benchmark run, by using commodity servers and ranked place 8 in the Green500 list of November 2010. These innovations provide a fundamental step towards cost-effective, environment-friendly exascale computing and IT operation.
The on-line event reconstruction in ALICE is performed by the High Level Trigger, which should process up to 2000 events per second in proton-proton collisions and up to 200 central events per second ...in heavy-ion collisions, corresponding to an input data stream of 30 GB/s. In order to fulfil the time requirements, a fast on-line tracker has been developed which can optionally use GPU hardware accelerators. The algorithm combines a Cellular Automaton method being used for a fast pattern recognition and the Kalman Filter method for fit of found trajectories and for the final track selection. A fast estimate of the vertex position is based on measurements from the Silicon Pixel Detector. The vertexer is used for the on line monitoring of the ALICE interaction point.
PDF
