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91.
Chip-multiprocessor (CMP) architectures are a promising design alternative to exploit the ever-increasing number of transistors that can be put on a die. To deliver high performance on applications that cannot be easily parallelized, CMPs can use additional support for speculatively executing the possibly data-dependent threads of an application. For cross-thread dependences that must be handled dynamically, the threads can be made to synchronize and communicate either at the register level or at the memory level. In the past, it has been unclear whether the higher hardware cost of register-level communication is cost-effective. In this paper, we show that the wide-issue dynamic processors that will soon populate CMPs, make fast communication a requirement for high performance. Consequently, we propose an effective hardware mechanism to support communication and synchronization of registers between on-chip processors. Our scheme adds enough support to enable register-level communication without specializing the architecture toward speculation much. Finally, our scheme allows the system to achieve near ideal performance. 相似文献
92.
Carmen Munuera Josep Puigmartí‐Luis Markos Paradinas Luis Garzón David B. Amabilino Carmen Ocal 《Small (Weinheim an der Bergstrasse, Germany)》2009,5(2):214-220
Soft materials comprising low‐molecular‐weight organic molecules are attracting increasing interest because of their importance in the development of a number of emerging areas in nanoscience and technology, including molecular electronics, nanosystems for energy conversion, and devices in the widest sense. Their interaction with electrodes and their behavior under electric fields is a topic of vital significance for these areas, and about which very little is known. Here unprecedented evidence is presented for the controlled peeling of organic molecular material when a voltage is applied between the conducting system and the conducting probe of a scanning force microscope. The rate of removal of the material from the surface of the bulk conducting supramolecular material can be tuned. It depends on the potential applied and is initiated only above a threshold value of 200 mV. The results indicate the importance of electric fields on the stability and performance of conducting organic systems at the nanoscale. 相似文献
93.
There have been many proposals of shared memory systems, each one providing different types of memory coherence for interprocess communication. However, they have usually been defined using different formalisms. This makes it difficult to compare among them the different proposals put forward. In this paper we present a formal framework for specifying memory models with different coherency properties. We specify most of the known shared memory models using our framework, showing some of the relationships that hold among them. 相似文献
94.
As envisioned in 1990*, international space station Freedom (SSF) was to be a large, complex, multi-purpose manned facility with a 30-year design life. The presence of a crew and the size of the investment would require high reliability and availability for safety- and mission-critical systems, but even with these requirements satisfied, long life and complexity would make equipment failure and repair inevitable. Recognizing this fact, in 1990 NASA and its contractors performed a study of the maintainability of the then-current space station configuration. Based on well-founded predictions of equipment failure rates, life limits, maintenance rate factors, and repair times, maintenance on equipment outside the pressurized modules of the station alone would have absorbed more than 3000 crew hours per year, which was clearly prohibitive. The chief reason for this maintenance overload was not the unreliability of equipment; it was the sheer number of components present. This paper summarizes this study, and presents a number of design and operational concepts which promise to alleviate the maintenance overload, many of which have been adopted in the current design.The central recommendation was to think of Freedom as a long-term ‘facility’ analogous to a ground-based research laboratory or manufacturing plant, rather than as a ‘space mission’. This philosophy leads to placing as much emphasis on maintainability as reliability in design; rethinking conventional manned-spacecraft design rules such as ‘fail-op-fail-op-fail-safe,’ which contributed heavily to the complexity of the baseline configuration; prioritizing maintenance by time-to-effect as well as ‘criticality,’ and zero-basing systems to wring out excessive complexity while retaining acceptable performance and safety. 相似文献
95.
A new design of a BIC sensor for current testing static CMOS circuits is proposed. It is based on a lateral BJT device which is easy to incorporate in any standard CMOS process. The design diverts a fraction of the I
DDQ
current from the cell under test and a resistive component generates a voltage proportional to I
DDQ
. Additional features are the possibility of continuous measure of i
dd
and increased speed of this sensor compared with sensors based on the current integration principle. The design does not have substrate currents due to the parasitic vertical BJTs. Experimental work on the sensor is reported. 相似文献
96.
Esteve Fernández Anna Schiaffino Carme Borrell Joan Benach Carles Ariza Josep Maria Ramon Jorge Twose Manel Nebot Anton Kunst 《Nicotine & tobacco research》2006,8(1):29-36
Our objective was to examine social class and educational differences in long-term smoking cessation success among a cohort of smokers attending a specialized smoking clinic. We studied sustained abstinence after cessation among 1,516 smokers (895 men and 621 women) treated for smoking cessation between 1995 and 2001 at a university teaching hospital in the metropolitan area of Barcelona, Spain. We calculated 1-year and long-term (up to 8-year) abstinence probabilities by means of Kaplan-Meier curves and the hazard ratio of relapse by means of Cox regression, after adjusting for other predictors of relapse. Overall abstinence probability was .277 (95% CI = .254-.301). Men and women in social classes IV-V had significant hazard ratios of relapse after long-term follow-up (men: 1.36, 95% CI = 1.07-1.72; women: 1.60, 95% CI = 1.24-2.06), as compared with patients in social classes I-II. The same independent effect was observed for education: Men and women with primary or less than primary studies had higher hazard ratios of relapse (men: 1.75, 95% CI = 1.35-2.25; women: 1.92, 95% CI = 1.51-2.46), as compared with patients with a university degree. Similar estimates were obtained after adjustment for stage of change, Fagerstr?m score for nicotine dependence, and type of treatment. Patients of lower socioeconomic status are at higher risk of relapse, and this association is independent of other well-known predictors of relapse. Social differences have to be taken into account in the clinical setting when tailoring specific actions to treat smoking dependence. 相似文献
97.
A new scheme to alleviate contention in optical burst switching networks is proposed. It consists of preventively reserving resources in a node, to be used if resources are busy on the next hop node. The burst is sent back to the preceding node and then resent forward. Simulations are carried out to assess the feasibility of the proposed scheme. Its performance is compared with that of contention resolution based on deflection routing. 相似文献
98.
Edgar B. Montufar Tania Traykova Josep A. Planell Maria-Pau Ginebra 《Materials science & engineering. C, Materials for biological applications》2011,31(7):1498-1504
Hydroxyapatite foams are potential synthetic bone grafting materials or scaffolds for bone tissue engineering. A novel method to obtain injectable hydroxyapatite foams consists in foaming the liquid phase of a calcium phosphate cement. In this process, the cement powder is incorporated into a liquid foam, which acts as a template for macroporosity. After setting, the cement hardens maintaining the macroporous structure of the foam. In this study a low molecular weight surfactant, Polysorbate 80, and a protein, gelatine, were compared as foaming agents of a calcium phosphate cement. The foamability of Polysorbate 80 was greater than that of gelatine, resulting in higher macroporosity in the set hydroxyapatite foam and higher macropore interconnectivity. Gelatine produced less interconnected foams, especially at high concentrations, due to a higher liquid foam stability. However it increased the injectability and cohesion of the foamed paste, and enhanced osteoblastic-like cell adhesion, all of them important properties for bone grafting materials. 相似文献
99.
In this study, we present a method designed to generate dynamic holograms in holographic optical tweezers. The approach combines our random mask encoding method with iterative high-efficiency algorithms. This hybrid method can be used to dynamically modify precalculated holograms, giving them new functionalities-temporarily or permanently-with a low computational cost. This allows the easy addition or removal of a single trap or the independent control of groups of traps for manipulating a variety of rigid structures in real time. 相似文献
100.
Monica Coll Anna Fernandez-Falgueras Anna Iglesias Bernat del Olmo Laia Nogue-Navarro Adria Simon Alexandra Perez Serra Marta Puigmule Laura Lopez Ferran Pico Monica Corona Marta Vallverdu-Prats Coloma Tiron Oscar Campuzano Josep Castella Ramon Brugada Mireia Alcalde 《International journal of molecular sciences》2022,23(20)
Molecular screening for pathogenic mutations in sudden cardiac death (SCD)-related genes is common practice for SCD cases. However, test results may lead to uncertainty because of the identification of variants of unknown significance (VUS) occurring in up to 70% of total identified variants due to a lack of experimental studies. Genetic variants affecting potential splice site variants are among the most difficult to interpret. The aim of this study was to examine rare intronic variants identified in the exonic flanking sequence to meet two main objectives: first, to validate that canonical intronic variants produce aberrant splicing; second, to determine whether rare intronic variants predicted as VUS may affect the splicing product. To achieve these objectives, 28 heart samples of cases of SCD carrying rare intronic variants were studied. Samples were analyzed using 85 SCD genes in custom panel sequencing. Our results showed that rare intronic variants affecting the most canonical splice sites displayed in 100% of cases that they would affect the splicing product, possibly causing aberrant isoforms. However, 25% of these cases (1/4) showed normal splicing, contradicting the in silico results. On the contrary, in silico results predicted an effect in 0% of cases, and experimental results showed >20% (3/14) unpredicted aberrant splicing. Thus, deep intron variants are likely predicted to not have an effect, which, based on our results, might be an underestimation of their effect and, therefore, of their pathogenicity classification and family members’ follow-up. 相似文献