PISM Performance Profiling - Analyse einer Eisschild Simulation

In der vorliegenden Masterarbeit wird der aktuelle Performancestand des Parallel Ice Sheet Model (PISM) evaluiert. Eine allgemeine Übersichtsanalyse ergibt, dass die Performance von PISM sowohl durch die Speicherbandbreite, also auch Netzwerkbandbreite und -latenz limitiert ist. Auf dieser Analyse aufbauend, werden ebenfalls mittels, sowohl automatisch generierten, als auch theoretisch hergeleiteten, Roofline Modellen, sowie Laufzeitmessungen einzelner Programmabschnitte die laufzeitkritischen Abschnitte identifiziert und analysiert. Für die herauskristallisierten Flaschenhälse und Hotspots, werden verschiedene Verbesserungsansätze dargelegt und diskutiert. Die detaillierte Analyse der Stressgleichungen ergibt beispielsweise eine mögliche Laufzeitreduzierung eben dieser um über 80 %. Anhand einer Implementierung wird die Umsetzbarkeit ausgewählter Verbesserungsansätze überprüft. Die Ergebnisse dieser Masterarbeit sind dabei von primärem Interesse für die PISM Entwickler. Das Vorgehen in dieser Arbeit ist exemplarisch für eine Performanceanalyse großer und kleiner Projekte und kann damit als Grundlage für weitere Analysen dienen, sodass die Masterarbeit auch für Leute interessant ist, die sich mit der Performance von wissenschaftlichem Programmcode auseinandersetzen

GPU-beschleunigte Support-Vector Machines

Data-Mining gewinnt immer mehr an Bedeutung, denn es stehen immer mehr Daten zur Verfügung. Um der stetig wachsenden Anzahl an Daten entgegenzuwirken, werden eine immer stärkere Hardware, bessere Algorithmen und optimierte Implementierungen benötigt. Es ist beispielsweise möglich mithilfe massiver Parallelität auf Grafikkarten die Rechenzeit zu verkürzen. Eine Möglichkeit Daten zu klassifizieren ist das überwachte maschinelle Lernen. Die Support-Vector Machine (SVM) ist eines dieser Verfahren. Sie erstellt ein Modell, worin die Trainingsdaten als Punkte im Raum interpretiert werden. Es werden diejenigen Datenpunkte gesucht, mit denen ein linearer Separator aufgestellt werden kann, der die Daten durch das breiteste Band voneinander trennt (large margin classifier). Anhand dieses gelernten Modells können dann neue Daten effizient klassifiziert werden. In dieser Arbeit wird eine Least Square Support Vektor Maschine implementiert. Bei der Least Squares Support Vektor Maschine werden nicht die wenigen Datenpunkte gesucht, die für die Separation wichtig sind (Support Vektoren), sondern bei allen Datenpunkten der proportionale Fehler bestimmt, und daraus die separierende Hyperebene abgeleitet. Die Least Squares Support Vektor Maschine wird mithilfe von NVIDIAs CUDA Parallel Programming Models für Grafikkarten implementiert und für NVIDIAs QUADRO GP100 optimiert. Dabei wurde explizit darauf geachtet, dass die GPU-Implementierung möglichst verzweigungsfrei ist. Außerdem wird die SoA Datenstruktur verwendet, und die Zugriffe über das Shared Memory optimiert. Damit konnte, bei ähnlicher Genauigkeit, auf der NVIDIAs QUADRO GP100 Grafikkarte, mit ca. 2,3 TFLOPS mit doppelter Genauigkeit, eine Laufzeitverbesserung um mehr als das 300-Fache gegenüber der gebräuchlichen CPU-Library for Support Vector Machines, LIBSVM, Implementierung gemessen werden

Lack of effect of pravastatin on cerebral blood flow or parenchymal volume loss in elderly at risk for vascular disease

<p><b>Background and Purpose:</b> Ageing is associated with a decline in cerebral blood flow. Animal studies have shown that cholesterol-lowering therapy with statins might preserve cerebral blood flow (CBF). We examined the effect of 40 mg pravastatin on the decline in CBF and brain volume in a subset of elderly subjects participating in the PROspective Study of Pravastatin in the Elderly at Risk (PROSPER) trial.</p> <p><b>Methods:</b> Randomization was not stratified according to whether or not subjects participated in the MRI substudy. In 391 men (n=226) and women (n=165) aged 70 to 82 years (mean±SD, 75±3.2), we measured total CBF (in mL/min) at baseline and after a mean±SD follow-up of 33±1.4 months with a gradient-echo phase-contrast MRI technique. Total CBF was defined as the summed flows in both internal carotid and vertebral arteries. Parenchymal volume (whole brain) was segmented with the use of in-house–developed semiautomatic software.</p> <p><b>Results:</b> Total CBF significantly declined in the placebo-allocated group, from 521±83 to 504±92 mL/min (P=0.0036) and in the pravastatin-allocated group from 520±94 to 506±92 mL/min (P=0.018). This decline was not significantly different between treatment groups (P=0.56). There was also a significant reduction in brain volume over time (P<0.001), which was not different between the treatment groups (P=0.47). When expressed per unit of parenchymal volume, the decline in CBF over time was no longer statistically significant.</p> <p><b>Conclusions:</b> Elderly people at risk for cerebral vascular disease had a significant decline in CBF with increasing age that was explained by a concomitant reduction in brain volume. Treatment with 40 mg pravastatin daily had no beneficial effect on total CBF.</p&gt

The effects of CLIL on mathematical content learning: A longitudinal study

Previous research has shown that content and language integrated learning (CLIL), an educational approach that offers content courses through more than one educational language, increases metalinguistic awareness. This improved insight into language structures is supposed to extend beyond the linguistic domain. In the present study, the question whether pupils who learn in a CLIL environment outperform their traditionally schooled peers in mathematics is investigated. In total, 107 pupils entered the study. All participants were in the first year of secondary education at a school in Ostend, in Flanders, the Dutch-speaking part of Belgium. Thirty-five pupils followed CLIL education in a foreign language (French) and 72 followed traditional education that was given in the native language (Dutch). All participants were tested using a mathematical test at the beginning of the year, after three months, and after ten months. The first measurement of the mathematical scores showed that the two groups did not differ. In accordance with our hypothesis, the CLIL group scored higher than the non-CLIL group after ten months. Surprisingly, an effect was also found after three months. To conclude, CLIL appears to have a positive impact on the mathematical performance of pupils even after a short period of time

White-matter development is different in bilingual and monolingual children : a longitudinal DTI study

Although numerous people grow up speaking more than one language, the impact of bilingualism on brain developing neuroanatomy is still poorly understood. This study aimed to determine whether the changes in the mean fractional-anisotropy (MFA) of language pathways are different between bilingual and monolingual children. Simultaneous-bilinguals, sequential-bilinguals and monolingual, male and female 10-13 years old children participated in this longitudinal study over a period of two years. We used diffusion tensor tractography to obtain mean fractional-anisotropy values of four language related pathways and one control bundle: 1-left-inferior-occipitofrontal fasciculus/IIFOF, 2-left-arcuate fasciculus/IAF/ISLF, 3-bundle arising from the anterior part of corpus-callosum and projecting to orbital lobe/AC-OL, 4-fibres emerging from anterior-midbody of corpus-callosum (CC) to motor cortices/AMB-PMC, 5-right-inferior-occipitofrontal fasciculus rIFOF as the control pathway unrelated to language. These values and their rate of change were compared between 3 groups. FA-values did not change significantly over two years for IAF/ISLF and AC-OL. Sequential- bilinguals had the highest degree of change in the MFA value of IIFOF, and AMBPMC did not present significant group differences. The comparison of MFA of IIFOF yielded a significantly higher FA-value in simultaneous bilinguals compared to monolinguals. These findings acknowledge the existing difference of the development of the semantic processing specific pathway between children with different semantic processing procedure. These also support the hypothesis that age of second language acquisition affects the maturation and myelination of some language specific white-matter pathways

L'éducation multilingue, l'apprentissage implicite et la didactique coopérative

Meertalig onderwijs in de zin van content and language integrated learning (CLIL), waarbij een deel van het curriculum wordt onderwezen in een doeltaal is in. De resultaten op het vlak van kennis van de doeltaal, de moedertaal, en van de leerstof, de positieve attitudes die ermee samengaan zowel als de cognitieve voordelen zijn dermate dat we kunnen spreken van een stille onderwijsrevolutie. De verklaringen van dit succes zijn, ten eerste, dat er sprake is van echt communicatief onderwijs wat zeer leerbevorderend werkt en, ten tweede, dat er sprake is van impliciet en coöperatief leren, wat ook het leerproces eveneens in ruime mate versterkt. Deze aanpak is m.a.w. veel meer dan een nieuwe aanpak van het taalonderwijs. Het is een innovatieve, blijvende en duurzame verandering

Both low circulating insulin-like growth factor-1 and high-density lipoprotein cholesterol are associated with hair loss in middle-aged women.

YesBackground: Multiple biomarkers have been associated with hair loss in women, but studies showed inconsistent results. Objective: We investigated the association between markers of cardiovascular disease risk (e.g., serum lipid levels and hypertension) and aging (e.g., 25-hydroxyvitamin D and insulin-like growth factor) with hair loss in a population of middle-aged women. Methods: In a random subgroup of 323 middle-aged women (mean age: 61.5 years) from the Leiden Longevity Study, hair loss was graded by three assessors using the Sinclair scale; women with a mean score higher than 1.5 were classified as cases with hair loss. Results: Every standard deviation increase in HDL cholesterol was associated with a 0.65 times lower risk (95% confidence interval [CI]: 0.46–0.91) of hair loss; for IGF-1 the risk was 0.68 times lower (95% CI: 0.48–0.97) per standard deviation increase, independent of the other studied variables. Women with both IGF-1 and HDL cholesterol levels below the median of the study population had a 3.47 times higher risk (95% CI: 1.30–9.25) of having hair loss. Limitations: The observational setting limits causal inference of the findings. Conclusion: Low HDL cholesterol and IGF-1 were associated with a higher risk of hair loss in women.This study was funded by the Innovation Oriented Research Program on Genomics (SenterNovem; IGE01014 and IGE5007), the Centre for Medical Systems Biology (CMSB), the Netherlands Genomics Initiative/Netherlands Organization for Scientific Research (05040202 and 050-060-810, NCHA), Unilever PLC and the European Union-funded Network of Excellence Lifespan (FP6 036894)

Investigating the frontoparietal network in mental calculation in primary school children - An fMRI study

The frontoparietal network activated during calculation processing is investigated in a pediatric population. Subjects assessed correctness of two and three operand equations. Besides traditional frontoparietal activation, clear activation of sites associated with error processing was observed

Dual Signaling of the Fas Receptor: Initiation of Both Apoptotic and Necrotic Cell Death Pathways

Murine L929 fibrosarcoma cells were transfected with the human Fas (APO-1/CD95) receptor, and the role of various caspases in Fas-mediated cell death was assessed. Proteolytic activation of procaspase-3 and -7 was shown by Western analysis. Acetyl-Tyr-Val-Ala-Asp-chloromethylketone and benzyloxycarbonyl-Asp(OMe)-Glu(OMe)-Val-Asp(OMe)-fluoromethylketone, tetrapeptide inhibitors of caspase-1– and caspase-3–like proteases, respectively, failed to block Fas-induced apoptosis. Unexpectedly, the broad-spectrum caspase inhibitors benzyloxycarbonyl-Val-Ala-Asp(OMe)-fluoromethylketone and benzyloxycarbonyl-Asp(OMe)-fluoromethylketone rendered the cells even more sensitive to Fas-mediated cell death, as measured after 18 h incubation. However, when the process was followed microscopically, it became clear that anti-Fas–induced apoptosis of Fas-transfected L929 cells was blocked during the first 3 h, and subsequently the cells died by necrosis. As in tumor necrosis factor (TNF)-induced necrosis, Fas treatment led to accumulation of reactive oxygen radicals, and Fas-mediated necrosis was inhibited by the oxygen radical scavenger butylated hydroxyanisole. However, in contrast to TNF, anti-Fas did not activate the nuclear factor κB under these necrotic conditions. These results demonstrate the existence of two different pathways originating from the Fas receptor, one rapidly leading to apoptosis, and, if this apoptotic pathway is blocked by caspase inhibitors, a second directing the cells to necrosis and involving oxygen radical production