| 1. |
- Beurskens, M. N. A., et al.
(författare)
-
Pedestal width and ELM size identity studies in JET and DIII-D; implications for ITER
- 2009
-
Ingår i: Plasma Physics and Controlled Fusion. - : IOP Publishing. - 0741-3335 .- 1361-6587. ; 51:12, s. 124051-
-
Tidskriftsartikel (refereegranskat)abstract
- The dependence of the H-mode edge transport barrier width on normalized ion gyroradius (rho* = rho/a) in discharges with type I ELMs was examined in experiments combining data for the JET and DIII-D tokamaks. The plasma configuration as well as the local normalized pressure (beta), collisionality (nu*), Mach number and the ratio of ion and electron temperature at the pedestal top were kept constant, while rho* was varied by a factor of four. The width of the steep gradient region of the electron temperature (T-e) and density (n(e)) pedestals normalized to machine size showed no or only a weak trend with rho*. A rho(1/2) or rho(1) dependence of the pedestal width, given by some theoretical predictions, is not supported by the current experiments. This is encouraging for the pedestal scaling towards ITER as it operates at lower rho* than existing devices. Some differences in pedestal structure and ELM behaviour were, however, found between the devices; in the DIII-D discharges, the n(e) and T-e pedestal were aligned at high rho* but the ne pedestal shifted outwards in radius relative to T-e as rho* decreases, while on JET the profiles remained aligned while rho* was scanned by a factor of two. The energy loss at an ELM normalized to the pedestal energy increased from 10% to 40% as rho* increased by a factor of two in the DIII-D discharges but no such variation was observed in the case of JET. The measured pedestal pressures and widths were found to be consistent with the predictions from modelling based on peeling-ballooning stability theory, and are used to make projections towards ITER
|
|
| 2. |
- Verhertbruggen, Y, et al.
(författare)
-
Developmental complexity of arabinan polysaccharides and their processing in plant cell walls
- 2009
-
Ingår i: The Plant Journal. - : Wiley-Blackwell. - 0960-7412 .- 1365-313X. ; 59:3
-
Tidskriftsartikel (refereegranskat)abstract
- Plant cell walls are constructed from a diversity of polysaccharide components. Molecular probes directed to structural elements of these polymers are required to assay polysaccharide structures in situ, and to determine polymer roles in the context of cell wall biology. Here, we report on the isolation and the characterization of three rat monoclonal antibodies that are directed to 1,5-linked arabinans and related polymers. LM13, LM16 and LM17, together with LM6, constitute a set of antibodies that can detect differing aspects of arabinan structures within cell walls. Each of these antibodies binds strongly to isolated sugar beet arabinan samples in ELISAs. Competitive-inhibition ELISAs indicate the antibodies bind differentially to arabinans with the binding of LM6 and LM17 being effectively inhibited by short oligoarabinosides. LM13 binds preferentially to longer oligoarabinosides, and its binding is highly sensitive to arabinanase action, indicating the recognition of a longer linearized arabinan epitope. In contrast, the binding of LM16 to branched arabinan and to cell walls is increased by arabinofuranosidase action. The presence of all epitopes can be differentially modulated in vitro using glycoside hydrolase family 43 and family 51 arabinofuranosidases. In addition, the LM16 epitope is sensitive to the action of β-galactosidase. Immunofluorescence microscopy indicates that the antibodies can be used to detect epitopes in cell walls, and that the four antibodies reveal complex patterns of epitope occurrence that vary between organs and species, and relate both to the probable processing of arabinan structural elements and the differing mechanical properties of cell walls.
|
|
| 3. |
- Alderman, J. McKee, et al.
(författare)
-
Neuroendocrine inhibition of glucose production and resistance to cancer in dwarf mice
- 2009
-
Ingår i: Experimental Gerontology. - : Elsevier BV. - 0531-5565 .- 1873-6815. ; 44:1-2, s. 26-33
-
Tidskriftsartikel (refereegranskat)abstract
- Pit1 null (Snell dwarf) and Proph1 null (Ames dwarf) mutant mice lack GH, PRL and TSH. Snell and Ames dwarf mice also exhibit reduced IGF-I, resistance to cancer and a longer lifespan than control mice. Endogenous glucose production during fasting is reduced in Snell dwarf mice compared to fasting control mice. In view of cancer cell dependence on glucose for energy, low endogenous glucose production may provide Snell dwarf mice with resistance to cancer. We investigated whether endogenous glucose production is lower in Snell dwarf mice during feeding. Inhibition of endogenous glucose production by glucose injection was enhanced in 12 to 14 month-old female Snell dwarf mice. Thus, we hypothesize that lower endogenous glucose production during feeding and fasting reduces cancer cell glucose utilization providing Snell dwarf mice with resistance to cancer. The elevation of circulating adiponectin, a hormone produced by adipose tissue, may contribute to the suppression of endogenous glucose production in 12 to 14 month-old Snell dwarf mice. We compared the incidence of cancer at time of death between old Snell dwarf and control mice. Only 18% of old Snell dwarf mice had malignant lesions at the time of death compared to 82% of control mice. The median ages at death for old Snell dwarf and control mice were 33 and 26 months, respectively. By contrast, previous studies showed a high incidence of cancer in old Ames dwarf mice at the time of death. Hence, resistance to cancer in old Snell dwarf mice may be mediated by neuroendocrine factors that reduce glucose utilization besides elevated adiponectin, reduced IGF-I and a lack of GH, PRL and TSH, seen in both Snell and Ames dwarf mice. Proteomics analysis of pituitary secretions from Snell dwarf mice confirmed the absence of GH and PRL, the secretion of ACTH and elevated secretion of Chromogranin B and Secretogranin II. Radioimmune assays confirmed that circulating Chromogranin B and Secretogranin II were elevated in 12 to 14 month-old Snell dwarf mice. In summary, our results in Snell dwarf mice suggest that the pituitary gland and adipose tissue are part of a neuroendocrine loop that lowers the risk of cancer during aging by reducing the availability of glucose.
|
|
| 4. |
- Balducci, C, et al.
(författare)
-
Negative impact and positive value in caregiving : Validation of the COPE index in a six-country sample of carers
- 2008
-
Ingår i: The Gerontologist. - 0016-9013 .- 1758-5341. ; 48:3, s. 276-286
-
Tidskriftsartikel (refereegranskat)abstract
- Purpose: The present study attempts to further validate the COPE Index on a large sample of carers drawn from six European countries. Design and Methods: We used a cross-sectional survey, with approximately 1,000 carers recruited in each of six countries by means of a common standard evaluation protocol. Our saturation recruitment of a designated quota of carers occurred by means of several channels, in identified geographical zones within countries. Interviews were carried out with primary informal carers by use of a common assessment tool. We subjected items of the COPE Index to principal component analysis and we assessed emergent components through the use of Cronbach's alpha reliability procedures. We examined factor components as summative scales for confirmatory correlations with caregiving and psychological variables. Results: Three components emerged, which we identified as the negative impact of caregiving, the positive value of caregiving, and the quality of support for caregiving. Internal consistency was good for negative impact and satisfactory for positive value and quality of support. Negative value was most consistently and strongly correlated with caregiving and psychological variables, although we did find diverse associations between these variables and the COPE Index subscales. Implications: The COPE Index is a brief, first-stage assessment of some sophistication that can enable health and social care professionals to develop appropriately targeted interventions to enhance the positive aspects of the caregiving experience and quality of support, as well as reduce the negative impacts of caregiving. Copyright 2008 by The Gerontological Society of America.
|
|
| 5. |
- Bhadauria, Major, et al.
(författare)
-
Accomodating diversity in CMPs with heterogeneous frequencies
- 2009
-
Ingår i: Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics). - Berlin, Heidelberg : Springer Berlin Heidelberg. - 1611-3349 .- 0302-9743. - 9783540929895 ; 5409 LNCS, s. 248-262
-
Konferensbidrag (refereegranskat)abstract
- Shrinking process technologies and growing chip sizes have profound effects on process variation. This leads to Chip Multiprocessors (CMPs) where not all cores operate at maximum frequency. Instead of simply disabling the slower cores or using guard banding (running all at the frequency of the slowest logic block), we investigate keeping them active, and examine performance and power efficiency of using frequency-heterogeneous CMPs on multithreaded workloads. With uniform workload partitioning, one might intuitively expect slower cores to degrade performance. However, with non-uniform workload partitioning, we find that using both low and high frequency cores improves performance and reduces energy consumption over just running faster cores. Thread scheduling and workload partitioning naturally play significant roles in these improvements. We find that using under-performing cores improves performance by 16% on average and saves CPU energy by up to 16% across the NAS and SPEC-OMP benchmarks on a quad-core AMD platform. Workload balancing via dynamic partitioning yields results within 5% of the overall ideal value. Finally, we show feasible methods to determine at run time whether using a heterogeneous configuration is beneficial. We validate our work through evaluation on a real CMP.
|
|
| 6. |
- Bhadauria, Major, et al.
(författare)
-
Understanding parsec performance on contemporary CMPS
- 2009
-
Ingår i: Proceedings of the 2009 IEEE International Symposium on Workload Characterization, IISWC 2009. - 9781424451562 ; , s. 98-107
-
Konferensbidrag (refereegranskat)abstract
- PARSEC is a reference application suite used in industry and academia to assess new Chip Multiprocessor (CMP) designs. No investigation to date has profiled PARSEC on real hardware to better understand scaling properties and bottlenecks. This understanding is crucial in guiding future CMP designs for these kinds of emerging workloads. We use hardware performance counters, taking a systems-level approach and varying common architectural parameters: number of out-of-order cores, memory hierarchy configu- rations, number of multiple simultaneous threads, number of memory channels, and processor frequencies. We find these programs to be largely compute-bound, and thus lim- ited by number of cores, micro-architectural resources, and cache-to-cache transfers, rather than by off-chip memory or system bus bandwidth. Half the suite fails to scale lin- early with increasing number of threads, and some applica- tions saturate performance at few threads on all platforms tested. Exploiting thread level parallelism delivers greater payoffs than exploiting instruction level parallelism. To re- duce power and improve performance, we recommend in- creasing the number of arithmetic units per core, increasing support for TLP, and reducing support for ILP.
|
|
| 7. |
- Bronevetsky, Greg, et al.
(författare)
-
Compiler-enhanced incremental checkpointing for openMP applications
- 2009
-
Ingår i: 23rd IEEE International Parallel and Distributed Processing Symposium, IPDPS 2009; Rome; Italy; 23 May 2009 through 29 May 2009. - 9781424437504
-
Konferensbidrag (refereegranskat)abstract
- As modern supercomputing systems reach the peta-flop performance range, they grow in both size and complexity. This makes them increasingly vulnerable to failures from a variety of causes. Checkpointing is a popular technique for tolerating such failures, enablingapplications to periodically save their state and restart computation after a failure. Although a many automated system-level checkpointing solutions are currently availableto HPC users, manual application-level checkpointing remains more popular due to its superior performance. This paper improves performance of automated checkpointing via a compiler analysis for incremental checkpointing.This analysis, which works with both sequential and OpenMP applications, reduces checkpoint sizes by as much as 80% and enables asynchronous checkpointing.
|
|
| 8. |
- Islam, Mafijul, 1975, et al.
(författare)
-
Cancellation of Loads that Return Zero Using Zero-Value Caches
- 2009
-
Ingår i: 23rd International Conference on Supercomputing, ICS'09; Yorktown Heights, NY; United States; 8 June 2009 through 12 June 2009. ; , s. 493-494
-
Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The speed gap between processor and memory continues to limit performance. To address this problem, we explore the potential of eliminating Zero Loads — loads accessing memory locations that contain the value “zero” — to improve performance and energy dissipation. Our study shows that such loads comprise as many as 18% of the total number of dynamic loads. We show that a significant fraction of zero loads ends up on the critical memory-access path in out-of-order cores. We propose a non-speculative microarchitectural technique — Zero-Value Cache (ZVC) — to capitalize on zero loads and explore critical design options of such caches. We show that with modest investment (typically a 512-byte structure), we can obtain speedups up to 32%. Most importantly, zero-value caches never cause performance loss.
|
|
| 9. |
- Islam, Mafijul, 1975, et al.
(författare)
-
Zero-Value Caches: Cancelling Loads that Return Zero
- 2009
-
Ingår i: Parallel Architectures and Compilation Techniques - Conference Proceedings, PACT. - 1089-795X. - 9780769537719 ; , s. 237-245
-
Rapport (övrigt vetenskapligt/konstnärligt)abstract
- The speed gap between processor and memory continues to limit performance. To address this problem, we explore the potential of eliminating Zero Loads — loads accessing memory locations that contain the value “zero” — to improve performance and energy dissipation. Our study shows that such loads comprise as many as 18% of the total number of dynamic loads. We show that a significant fraction of zero loads ends up on the critical memory-access path in out-of-order cores. We propose a non-speculative microarchitectural technique — Zero-Value Cache (ZVC) — to capitalize on zero loads and explore critical design options of such caches. We show that with modest investment (typically a 576-byte structure), we can obtain speedups up to 78% and reduce the overall energy dissipation up to 39%. Most importantly, zero-value caches never cause performance loss.
|
|
| 10. |
- Rabouille, C., et al.
(författare)
-
Comparison of hypoxia among four river-dominated ocean margins: The Changjiang (Yangtze), Mississippi, Pearl, and Rhone rivers
- 2008
-
Ingår i: Continental Shelf Research. - : Elsevier BV. - 0278-4343. ; 28:12, s. 1527-1537
-
Tidskriftsartikel (refereegranskat)abstract
- We examined the occurrence of seasonal hypoxia (O-2 < 2 mg l(-1)) in the bottom waters of four river-dominated ocean margins (off the Changjiang, Mississippi, Pearl and Rhone Rivers) and compared the processes leading to the depletion of oxygen. Consumption of oxygen in bottom waters is linked to biological oxygen demand fueled by organic matter from primary production in the nutrient-rich river plume and perhaps terrigenous inputs. Hypoxia occurs when this consumption exceeds replenishment by diffusion, turbulent mixing or lateral advection of oxygenated water. The margins off the Mississippi and Changjiang are affected the most by summer hypoxia, while the margins off the Rhone and the Pearl rivers systems are less affected, although nutrient concentrations in the river water are very similar in the four systems. Spring and summer primary production is high overall for the shelves adjacent to the Mississippi, Changjiang and Pearl (1-10g C m(-2) d(-1)), and lower off the Rhone River (< 1 g C m(-2) d(-1)), which could be one of the reasons of the absence of hypoxia on the Rhone shelf The residence time of the bottom water is also related to the occurrence of hypoxia, with the Mississippi margin showing a long residence time and frequent occurrences of hypoxia during summer over very large spatial scales, whereas the East China Sea (ECS)/Changjiang displays hypoxia less regularly due to a shorter residence time of the bottom water. Physical stratification plays an important role with both the Changjiang and Mississippi shelf showing strong thermohaline stratification during summer over extended periods of time, whereas summer stratification is less prominent for the Pearl and Rhone partly due to the wind effect on mixing. The shape of the shelf is the last important factor since hypoxia occurs at intermediate depths (between 5 and 50 m) on broad shelves (Gulf of Mexico and ECS). Shallow estuaries with low residence time such as the Pearl River estuary during the summer wet season when mixing and flushing are dominant features, or deeper shelves, such as the Gulf of Lion off the Rhone show little or no hypoxia. (c) 2008 Elsevier Ltd. All rights reserved.
|
|
