Investigation of parallel programming on heterogeneous multiprocessors

Multi-core processors have become ordinary in modern commodity computers. Computationally intensive applications, like video processing, that previously only ran on specialized hardware, are now common on home computers. However, the demand for more computing power is ever-increasing, and with the introduction of high definition video, more performance is desired. As an alternative to having multiple identical processor cores, heterogeneous multiprocessors have cores with different capabilities. This allows tasks to be processed on simple cores with specialized functionality. The simplicity furthers low power consumption, small die usage, and low price. Dealing with heterogeneous cores increases the complexity of writing programs for the architecture. The reasons for this includes different capabilities of the cores, and some heterogeneous architectures do not have shared memory. Without shared memory, accessing main memory requires explicit transfers to local memory. In this thesis, we consider two architectures, the STI Cell/B.E. and Intel IXP2400, and evaluate parallelization strategies and performance for real-world problems. Our tests show promising throughput for some applications, and we propose a scheme for offloading computationally intensive parts of an existing application

The Nornir run-time system for parallel programs using Kahn process networks on multi-core machines – A flexible alternative to MapReduce

Even though shared-memory concurrency is a paradigm frequently used for developing parallel applications on small- and middle-sized machines, experience has shown that it is hard to use. This is largely caused by synchronization primitives which are low-level, inherently non-deterministic, and, consequently, non-intuitive to use. In this paper, we present the Nornir run-time system. Nornir is comparable to well-known frameworks such as MapReduce and Dryad that are recognized for their efficiency and simplicity. Unlike these frameworks, Nornir also supports process structures containing branches and cycles. Nornir is based on the formalism of Kahn process networks, which is a shared-nothing, message-passing model of concurrency. We deem this model a simple and deterministic alternative to shared-memory concurrency. Experiments with real and synthetic benchmarks on up to 8 CPUs show that performance in most cases scales almost linearly with the number of CPUs, when not limited by data dependencies. We also show that the modeling flexibility allows Nornir to outperform its MapReduce counterparts using well-known benchmarks. This article is distributed under the terms of the Creative Commons Attribution Noncommercial License which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and source are credited

Kvasir-Capsule, a video capsule endoscopy dataset

Artificial intelligence (AI) is predicted to have profound effects on the future of video capsule endoscopy (VCE) technology. The potential lies in improving anomaly detection while reducing manual labour. Existing work demonstrates the promising benefits of AI-based computer-assisted diagnosis systems for VCE. They also show great potential for improvements to achieve even better results. Also, medical data is often sparse and unavailable to the research community, and qualified medical personnel rarely have time for the tedious labelling work. We present Kvasir-Capsule, a large VCE dataset collected from examinations at a Norwegian Hospital. Kvasir-Capsule consists of 117 videos which can be used to extract a total of 4,741,504 image frames. We have labelled and medically verified 47,238 frames with a bounding box around findings from 14 different classes. In addition to these labelled images, there are 4,694,266 unlabelled frames included in the dataset. The Kvasir-Capsule dataset can play a valuable role in developing better algorithms in order to reach true potential of VCE technology

Antibiotic-loaded bone cement in prevention of periprosthetic joint infections in primary total knee arthroplasty: A register-based multicentre randomised controlled non-inferiority trial (ALBA trial)

Introduction The current evidence on the efficacy of antibiotic-loaded bone cement (ALBC) in reducing the risk of periprosthetic joint infections (PJI) after primary joint reconstruction is insufficient. In several European countries, the use of ALBC is routine practice unlike in the USA where ALBC use is not approved in low-risk patients. Therefore, we designed a double-blinded pragmatic multicentre register-based randomised controlled non-inferiority trial to investigate the effects of ALBC compared with plain bone cement in primary total knee arthroplasty (TKA). Methods and analysis A minimum of 9,172 patients undergoing full-cemented primary TKA will be recruited and equally randomised into the ALBC group and the plain bone cement group. This trial will be conducted in Norwegian hospitals that routinely perform cemented primary TKA. The primary outcome will be risk of revision surgery due to PJI at 1-year of follow-up. Secondary outcomes will be: risk of revision due to any reason including aseptic loosening at 1, 6, 10 and 20 years of follow-up; patient-related outcome measures like function, pain, satisfaction and health-related quality of life at 1, 6 and 10 years of follow-up; risk of changes in the microbial pattern and resistance profiles of organisms cultured in subsequent revisions at 1, 6, 10 and 20 years of follow-up; cost-effectiveness of routine ALBC versus plain bone cement use in primary TKA. We will use 1:1 randomisation with random permuted blocks and stratify by participating hospitals to randomise patients to receive ALBC or plain bone cement. Inclusion, randomisation and follow-up will be through the Norwegian Arthroplasty Register. Ethics and dissemination The trial was approved by the Western Norway Regional Committees on Medical and Health Research Ethics (reference number: 2019/751/REK vest) on 21 June 2019. The findings of this trial will be disseminated through peer-reviewed publications and conference presentations. Trial registration number NCT04135170.publishedVersio

Adopsjon av tekstmeldingstjenester og hvordan dette er med på å bygge og opprettholde det sosiale nettverket i ungdomssegmentet

Denne rapporten har to hovedmål. Det ene er å forklare ungdommens adopsjon av sosiale medieringstjenester i en mobil setting. Arbeidet blir utføret ved å benytte en adopsjonsmodell som er basert på tidligere studier innenfor ungdom og mobiltelefoni. De tidligere studiene blir gjennomgått for å danne grunnlag for en adopsjonsmodell som er tilpasset ungdomssegmentet. Med utgangspunkt i denne adopsjonsmodellen blir det utarbeidet et spørreskjema som gir oss de nødvendige data for videre arbeid med å utarbeide den endelige adopsjonsmodellen som forklarer bruk og intensjon om bruk. Det andre hovedmålet er å forklare observert adferd ved å se på svarene fra spørreskjemaet og forklare forskjeller mellom alder, kjønn og sted. Konklusjonen til første hovedmål av arbeidet ble at en utvidelse av eksisterende modell med hensyn på ungdomssegmentet var nødvendige for å få økt forklaringsevne i modellen. For det andre hovedmålet ble konklusjonen at adferd kan forklares ut i fra de tidligere studier da våre funn samsvarer med teorien hentet derfra

The Nornir run-time system for parallel programs using Kahn process networks on multi-core machines-a flexible alternative to MapReduce

Even though shared-memory concurrency is a paradigm frequently used for developing parallel applications on small- and middle-sized machines, experience has shown that it is hard to use. This is largely caused by synchronization primitives which are low-level, inherently non-deterministic, and, consequently, non-intuitive to use. In this paper, we present the Nornir run-time system. Nornir is comparable to well-known frameworks such as MapReduce and Dryad that are recognized for their efficiency and simplicity. Unlike these frameworks, Nornir also supports process structures containing branches and cycles. Nornir is based on the formalism of Kahn process networks, which is a shared-nothing, message-passing model of concurrency. We deem this model a simple and deterministic alternative to shared-memory concurrency. Experiments with real and synthetic benchmarks on up to 8 CPUs show that performance in most cases scales almost linearly with the number of CPUs, when not limited by data dependencies. We also show that the modeling flexibility allows Nornir to outperform its MapReduce counterparts using well-known benchmark

Facet arthropathy evaluation: CT or MRI?

Objective To assess the reliability of lumbar facet arthropathy evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) in patients with and without lumbar disc prosthesis and to estimate the reliability for individual CT and MRI findings indicating facet arthropathy. Methods Metal-artifact reducing CT and MRI protocols were performed at follow-up of 114 chronic back pain patients treated with (n = 66) or without (n = 48) lumbar disc prosthesis. Three experienced radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade facet arthropathy at each of the three lower lumbar levels on both CT and MRI, using Weishaupt et al’s rating system. CT and MRI examinations were randomly mixed and rated independently. Findings were dichotomized before analysis. Overall kappa and (due to low prevalence) prevalence- and bias-adjusted kappa were calculated to assess interobserver agreement. Results Interobserver agreement on total grade facet arthropathy was moderate at all levels with CT (kappa 0.47–0.48) and poor to fair with MRI (kappa 0.20–0.32). Mean prevalence- and bias-adjusted kappa was lower for osteophyte/hypertrophy versus other individual findings (CT 0.58 versus 0.79–0.86, MRI 0.35 versus 0.81–0.90), higher with CT versus MRI when rating osteophyte/hypertrophy (0.58 versus 0.35) and total grade facet arthropathy (0.54 versus 0.31), and generally similar at levels with versus levels without disc prosthesis. Conclusion Interobserver agreement on facet arthropathy was moderate with CT and better with CT than with MRI. Disc prosthesis did not influence agreement. A more reliable grading of facet arthropathy requires a more consistent evaluation of osteophytes/hypertrophy

Facet arthropathy evaluation: CT or MRI?

Objective - To assess the reliability of lumbar facet arthropathy evaluation with computed tomography (CT) or magnetic resonance imaging (MRI) in patients with and without lumbar disc prosthesis and to estimate the reliability for individual CT and MRI findings indicating facet arthropathy. Methods - Metal-artifact reducing CT and MRI protocols were performed at follow-up of 114 chronic back pain patients treated with (n = 66) or without (n = 48) lumbar disc prosthesis. Three experienced radiologists independently rated facet joint space narrowing, osteophyte/hypertrophy, erosions, subchondral cysts, and total grade facet arthropathy at each of the three lower lumbar levels on both CT and MRI, using Weishaupt et al’s rating system. CT and MRI examinations were randomly mixed and rated independently. Findings were dichotomized before analysis. Overall kappa and (due to low prevalence) prevalence- and bias-adjusted kappa were calculated to assess interobserver agreement. Results - Interobserver agreement on total grade facet arthropathy was moderate at all levels with CT (kappa 0.47–0.48) and poor to fair with MRI (kappa 0.20–0.32). Mean prevalence- and bias-adjusted kappa was lower for osteophyte/hypertrophy versus other individual findings (CT 0.58 versus 0.79–0.86, MRI 0.35 versus 0.81–0.90), higher with CT versus MRI when rating osteophyte/hypertrophy (0.58 versus 0.35) and total grade facet arthropathy (0.54 versus 0.31), and generally similar at levels with versus levels without disc prosthesis. Conclusion - Interobserver agreement on facet arthropathy was moderate with CT and better with CT than with MRI. Disc prosthesis did not influence agreement. A more reliable grading of facet arthropathy requires a more consistent evaluation of osteophytes/hypertrophy

Adjacent Disc Degeneration After Lumbar Total Disc Replacement or Non-operative Treatment: A Randomized Study With Eight-year Follow-up

Study Design: A randomized controlled multicenter trial with 8-year follow-up. Objective: The aim of this study was to assess the long-term development of adjacent disc degeneration (ADD) after lumbar total disc replacement (TDR) or nonoperative treatment, and to analyze the association between ADD development and clinical outcome. Summary of Background Data: TDR was introduced as a motion-preserving alternative to spinal fusion, which has been reported to increase the risk of ADD. However, ADD may develop naturally regardless of any surgery, and no randomized study has assessed the long-term development of ADD after TDR versus nonoperative treatment. Methods: The study included 126 of the 173 patients with chronic low back pain (LBP) originally included in a randomized study comparing TDR with multidisciplinary rehabilitation. Magnetic resonance imaging (MRI) of the lumbar spine was performed before treatment and at 8-year follow-up. ADD was categorized as increased or not increased based on an evaluation of Modic changes, disc height reduction, disc contour, herniation size, nucleus pulposus signal, and posterior high intensity zones. We used a χ2 test or a Fisher exact test to compare crude proportions, and multiple linear regressions to analyze the association between increased ADD (yes/no) and change in Oswestry Disability Index (ODI) from pre-treatment to follow-up. Results: ADD increased (for at least one ADD variable) in 23 of 57 patients (40%) treated nonoperatively, and 29 of 69 patients (42%) treated with TDR (P = 0.86). We found no significant associations between ADD increase and the change in ODI. Conclusion: Increased ADD occurred with similar frequency after TDR and after nonoperative treatment, and was not related to the clinical outcome at 8-year follow-up. Level of Evidence: