1,720,996 research outputs found
Optimizing Offload Performance in Heterogeneous MPSoCs
No full textHeterogeneous multi-core architectures combine a few 'host' cores, optimized for single-thread performance, with many small energy-efficient 'accelerator' cores for data-parallel processing, on a single chip. Offloading a computation to the many-core acceleration fabric introduces a communication and synchronization cost which reduces the speedup attainable on the accelerator, particularly for small and fine-grained parallel tasks. We demonstrate that by co-designing the hardware and offload routines, we can increase the speedup of an offloaded DAXPY kernel by as much as 47.9%. Furthermore, we show that it is possible to accurately model the runtime of an offloaded application, accounting for the offload overheads, with as low as 1% MAPE error, enabling optimal offload decisions under offload execution time constraints
SARIS: Accelerating Stencil Computations on Energy-Efficient RISC-V Compute Clusters with Indirect Stream Registers
No full textStencil codes are performance-critical in many compute-intensive applications, but suffer from significant address calculation and irregular memory access overheads. This work presents SARIS, a general and highly flexible methodology for stencil acceleration using register-mapped indirect streams. We demonstrate SARIS for various stencil codes on an eight-core RISC-V compute cluster with indirect stream registers, achieving significant speedups of 2.72x, near-ideal FPU utilizations of 81%, and energy efficiency improvements of 1.58x over an RV32G baseline on average. Scaling out to a 256-core manycore system, we estimate an average FPU utilization of 64%, an average speedup of 2.14x, and up to 15% higher fractions of peak compute than a leading GPU code generator
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Right gastroepiploic artery graft: long-term clinical follow-up in 271 patients--experience of a single center
No full textBACKGROUND AND AIM: We present our experience in the use of right gastroepiploic
artery (rGEA). Long-term clinical results are reported. METHODS: From April 1994
to June 2005, 271 patients (257 males, mean age 56.2 +/- 7.1) underwent coronary
artery bypass grafting with the use of rGEA. Preoperative, perioperative, and
postoperative data were retrospectively collected and clinical results and
survival were examined. The end points of follow-up were death and recurrence of
cardiac events such as angina and myocardial infarction (MI). The mean follow-up
was 8.2 +/- 2.9 years. RESULTS: Left ventricular ejection fraction ranged from
0.20 to 0.68 (mean 0.55 +/- 0.7). The mean cardiopulmonary bypass time was 96.8
+/- 15.8 minutes and the mean cross-clamping time was 69.7 +/- 14.2 minutes. The
mean number of distal anastomosis was 3.3 +/- 0.7 (range 2 to 5). Early mortality
was 2.6% and postoperative MI occurred in three patients. There were 21 (7.9%)
late deaths and three of them (1.2%) were cardiac related. Actuarial
10-year-survival of all deaths, including in-hospital death, was 70.8%+/- 9.9%.
No abdominal complications occurred during or after rGEA harvesting. Seven
patients have been suffering of recurrence of angina. Angiography was performed
only on those patients with recurrent angina. CONCLUSION: The rGEA can be
considered as a valid arterial conduit, relatively easy to harvest, safe to use
with low perioperative risks, and good mid- and long-term results. The low early
and late rate mortality and the satisfactory clinical results are good reasons
for using routinely this conduit in selected patients
L-arginine effects on myocardial stress in cardiac surgery: preliminary results
No full textBACKGROUND: L-arginine in addition to cardioplegia stimulates the release of
nitric oxide and increases coronary blood flow, decreasing platelet activation
and leukocyte adhesion. The aim of our study was to determine the feasibility and
the efficacy of the addition of L-arginine to antegrade and retrograde blood
cardioplegia in reducing myocardial damage and stress. METHODS: Twenty-eight
consecutive patients who underwent coronary artery bypass grafting were
randomized to receive 7.5 g of L-arginine in 500 ml of cardioplegic solution. To
assess safety of use of L-arginine, hemodynamic evaluation was performed before
sternum opening, at sternum closure, and 1 hour after arrival in the intensive
care unit to measure cardiac index, systemic and pulmonary vascular resistances,
and pulmonary capillary wedge pressure. Moreover, transesophageal
echocardiography was performed to assess myocardial contractility. To determine
the effects on myocardial stress, blood samples were taken from the retrograde
coronary sinus catheter for lactate, interleukin (IL)-2 receptor, IL-6 and tumor
necrosis factor (TNF)-alpha levels. Serum samples (preoperatively, 2, 18 and 42
hours after aortic cross-clamping removal) were also analyzed to measure creatine
phosphokinase, creatine kinase-MB mass, cardiac troponin T, platelets, and
leukocytes. RESULTS: We found statistical differences for IL-2 receptor, IL-6,
TNF-alpha, platelets and leukocytes, in favor of the treated group, and
decreasing trends in creatine kinase-MB mass and troponin T levels. CONCLUSIONS:
The present study shows the positive effects of the addition of L-arginine to
cardioplegia. Reduced IL-2 receptor, IL-6 and TNF-alpha indicate a decrease in
myocardial stress. Safety of Larginine is related to lower values of systemic
vascular resistances and pulmonary capillary wedge pressure observed in group A
postoperatively that could improve the patient's outcome in terms of a reduced
need for inotropic support. Moreover, the decrease in platelet and leukocyte
count in the treated group might express a reduced no-reflow phenomenon and a
better reperfusion, limiting endothelial injury from oxygen radical production
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