Enhancing the L1 Data Cache Design to Mitigate HCI

Over the lifetime of a microprocessor, the Hot Carrier Injection (HCI) phenomenon degrades the threshold voltage, which causes slower transistor switching and eventually results in timing violations and faulty operation. This effect appears when the memory cell contents flip from logic ‘0’ to ‘1’ and vice versa. In caches, the majority of cell flips are concentrated into only a few of the total memory cells that make up each data word. In addition, other researchers have noted that zero is the most commonly-stored data value in a cache, and have taken advantage of this behavior to propose data compression and power reduction techniques. Contrary to these works, we use this information to extend the lifetime of the caches by introducing two microarchitectural techniques that spread and reduce the number of flips across the first-level (L1) data cache cells. Experimental results show that, compared to the conventional approach, the proposed mechanisms reduce the highest cell flip peak up to 65.8%, whereas the threshold voltage degradation savings range from 32.0% to 79.9% depending on the application.This work has been supported by the Spanish Ministerio de Econom´ıa y Competitividad (MINECO), by FEDER funds through Grant TIN2012-38341-C04-01, by the Intel Early Career Faculty Honor Program Award, by a HiPEAC Collaboration Grant funded by the FP7 HiPEAC Network of Excellence under grant agreement 287759, and by the Engineering and Physical Sciences Research Council (EPSRC) through Grants EP/K026399/1 and EP/J016284/1.This is the author accepted manuscript. The final version is available from IEEE at http://dx.doi.org/10.1109/LCA.2015.2460736. The dataset associated with this article can be found on the repository at https://www.repository.cam.ac.uk/handle/1810/249006

On microarchitectural mechanisms for cache wearout reduction

Hot carrier injection (HCI) and bias temperature instability (BTI) are two of the main deleterious effects that increase a transistor's threshold voltage over the lifetime of a microprocessor. This voltage degradation causes slower transistor switching and eventually can result in faulty operation. HCI manifests itself when transistors switch from logic ''0'' to ''1'' and vice versa, whereas BTI is the result of a transistor maintaining the same logic value for an extended period of time. These failure mechanisms are especiall in those transistors used to implement the SRAM cells of first-level (L1) caches, which are frequently accessed, so they are critical to performance, and they are continuously aging. This paper focuses on microarchitectural solutions to reduce transistor aging effects induced by both HCI and BTI in the data array of L1 data caches. First, we show that the majority of cell flips are concentrated in a small number of specific bits within each data word. In addition, we also build upon the previous studies, showing that logic ''0'' is the most frequently written value in a cache by identifying which cells hold a given logic value for a significant amount of time. Based on these observations, this paper introduces a number of architectural techniques that spread the number of flips evenly across memory cells and reduce the amount of time that logic ''0'' values are stored in the cells by switchingThis work was supported in part by the Spanish Ministerio de Economía y Competitividad within the Plan E Funds under Grant TIN2015-66972-C5-1-R, in part by the HiPEAC Collaboration Grant funded by the FP7 HiPEAC Network of Excellence under Grant 287759, and in part by the Engineering and Physical Sciences Research Council under Grant EP/K 026399/1 and Grant EP/J016284/1

Flu viruses a lucky community and cosine graphs: the possibilities opened up by the use of a socio-political perspective to study learning in an undergraduate access course in mathematics

This is an Accepted Manuscript of an article published by Taylor & Francis in African Journal of Research in Mathematics, Science and Technology Education on 20 August 2013 available online: http://www.tandfonline.com/10.1080/10288457.2009.10740656.In this paper I present a perspective of mathematics education and learning, termed a 'sociopolitical perspective'. Classroom mathematical activity, in which certain ways of acting, behaving and knowing are given value, is located in a wider network of socio-political practices. Learning in mathematics is regarded as coming to participate in the discourse of the community that practises the mathematics. I argue that the use of a socio-political perspective allows the researcher and teacher to view classroom mathematical activity as a product of the network of socio-political practices in which it is located, rather than as a product of individual cognitive ability. I illustrate the use of this perspective by drawing on a study of learning in a first-year university access course in Mathematics at a South African university. Fairclough's method for critical discourse analysis, supplemented with work by Sfard and Morgan in mathematics education, was used to analyse both the text of a 'real world' problem in mathematics and a transcript representing the activity as a group of five students solved the problem. This analysis suggests that, despite containing traces of discourses from outside of mathematics, the problem text constructs the activity as solving a mathematical problem with features of a school mathematical word problem. When solving the problem the students draw on practices associated with school mathematics and their university mathematics course, some of which enable and others constrain their participation. For example, they refer to named functions learned at school, they have difficulty making productive links between the mathematical functions and the 'real world' context, and they have varied opportunities for mathematical talk in the group. The study identifies as key to the students' progress the presence of an authority (in this case a tutor) who can make explicit the ways of thinking, acting, and talking that are valued in the discourse of undergraduate mathematics, and who provides opportunities for mathematical talk

Synthesis of high ion exchange zeolites from coal fly ash

This study focuses on the synthesis at a pilot plant scale of zeolitic material obtained from the coal fly ashes of the Teruel and Narcea power plants in Spain. After the optimisation of the synthesis parameters at laboratory scale, the Teruel and Narcea fly ashes were selected as low and high glass fly ashes. The pilot plant scale experiments were carried out in a 10 m3 reactor of Clariant SA (Barcelona, Spain). The results allowed obtaining 1.1 and 2.2 tonnes of zeolitic material with 40 and 55% of NaP1 content, in two single batch experiments of 24 and 8 hours, for Teruel and Narcea fly ashes, respectively. The cation exchange capacities (CEC) of the final product reached 2.0 and 2.7 meq g-1 for Teruel and Narcea zeolitic material, respectively, which are very close to the usual values reached by the high quality natural zeolitic products. Finally, with the aim of testing possible applications of the commercial NaP1-IQE and pilot plant NaP1-Narcea zeolitic products in water decontamination, efficiency for metal uptake from waste waters from electroplating baths was investigate

Under-reporting bicycle accidents to police in the COST TU1101 international survey: Cross-country comparisons and associated factors

Police crash reports are often the main source for official data in many countries. However, with the exception of fatal crashes, crashes are often underreported in a biased manner. Consequently, the countermeasures adopted according to them may be inefficient. In the case of bicycle crashes, this bias is most acute and it probably varies across countries, with some of them being more prone to reporting accidents to police than others. Assessing if this bias occurs and the size of it can be of great importance for evaluating the risks associated with bicycling. This study utilized data collected in the COST TU1101 action “Towards safer bicycling through optimization of bicycle helmets and usage”. The data came from an online survey that included questions related to bicyclists' attitudes, behaviour, cycling habits, accidents, and patterns of use of helmets. The survey was filled by 8655 bicyclists from 30 different countries. After applying various exclusion factors, 7015 questionnaires filled by adult cyclists from 17 countries, each with at least 100 valid responses, remained in our sample. The results showed that across all countries, an average of only 10% of all crashes were reported to the police, with a wide range among countries: from a minimum of 0.0% (Israel) and 2.6% (Croatia) to a maximum of a 35.0% (Germany). Some factors associated with the reporting levels were type of crash, type of vehicle involved, and injury severity. No relation was found between the likelihood of reporting and the cyclist's gender, age, educational level, marital status, being a parent, use of helmet, and type of bicycle. The significant under-reporting – including injury crashes that do not lead to hospitalization – justifies the use of self-report survey data for assessment of bicycling crash patterns as they relate to (1) crash risk issues such as location, infrastructure, cyclists' characteristics, and use of helmet and (2) strategic approaches to bicycle crash prevention and injury reduction.Fil: Shinar, D.. Ben Gurion University of the Negev; IsraelFil: Valero Mora, Pedro. Universidad de Valencia; EspañaFil: van Strijp Houtenbos, M.. Institute For Road Safety Research; Países BajosFil: Haworth, N.. Queensland University of Technology; AustraliaFil: Schramm, A.. Queensland University of Technology; AustraliaFil: de Bruyne, G.. Universiteit Antwerp; BélgicaFil: Cavallo, V.. No especifíca;Fil: Chliaoutakis, J.. No especifíca;Fil: Pereira Dias, Joao. Instituto Superior Tecnico; PortugalFil: Ferraro, Ottavia Eleonora. Universita Degli Studi Di Pavia; ItaliaFil: Fyhri, Aslak. No especifíca;Fil: Sajatovic, Anika Hursa. No especifíca;Fil: Kuklane, Kalev. Lund University; SueciaFil: Ledesma, Ruben Daniel. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Psicología Básica, Aplicada y Tecnología. Universidad Nacional de Mar del Plata. Facultad de Psicología. Instituto de Psicología Básica, Aplicada y Tecnología.; ArgentinaFil: Calvé Mascarell, Oscar. Ben Gurion University of the Negev; IsraelFil: Morandi, A.. Universita Degli Studi Di Pavia; ItaliaFil: Muser, Markus. No especifíca;Fil: Otte, Diettmar. No especifíca;Fil: Papadakaki, M.. No especifíca;Fil: Sanmartín, J.. Universidad de Valencia; EspañaFil: Dulf, D.. No especifíca;Fil: Saplioglu, M.. No especifíca;Fil: Tzamalouka, Georgia. No especifíca

Beyond viral suppression of HIV – the new quality of life frontier

BACKGROUND: In 2016, the World Health Organization (WHO) adopted a new Global Health Sector Strategy on HIV for 2016–2021. It establishes 15 ambitious targets, including the ‘90-90-90’ target calling on health systems to reduce under-diagnosis of HIV, treat a greater number of those diagnosed, and ensure that those being treated achieve viral suppression. DISCUSSION: The WHO strategy calls for person-centered chronic care for people living with HIV (PLHIV), implicitly acknowledging that viral suppression is not the ultimate goal of treatment. However, it stops short of providing an explicit target for health-related quality of life. It thus fails to take into account the needs of PLHIV who have achieved viral suppression but still must contend with other intense challenges such as serious non-communicable diseases, depression, anxiety, financial stress, and experiences of or apprehension about HIV-related discrimination. We propose adding a ‘fourth 90’ to the testing and treatment target: ensure that 90 % of people with viral load suppression have good health-related quality of life. The new target would expand the continuum-of-services paradigm beyond the existing endpoint of viral suppression. Good health-related quality of life for PLHIV entails attention to two domains: comorbidities and self-perceived quality of life. CONCLUSIONS: Health systems everywhere need to become more integrated and more people-centered to successfully meet the needs of virally suppressed PLHIV. By doing so, these systems can better meet the needs of all of their constituents – regardless of HIV status – in an era when many populations worldwide are living much longer with multiple comorbidities

Modeling of the Sedative and Airway Obstruction Effects of Propofol in Patients with Parkinson Disease undergoing Stereotactic Surgery

BACKGROUND: Functional stereotactic surgery requires careful titration of sedation since patients with Parkinson disease need to be rapidly awakened for testing. This study reports a population pharmacodynamic model of propofol sedation and airway obstruction in the Parkinson disease population. METHODS: Twenty-one patients with advanced Parkinson disease undergoing functional stereotactic surgery were included in the study and received propofol target-controlled infusion to achieve an initial steady state concentration of 1 microg/ml. Sedation was measured using the Ramsay Sedation Scale. Airway obstruction was measured using a four-category score. Blood samples were drawn for propofol measurement. Individual pharmacokinetic profiles were constructed nonparametrically using linear interpolation. Time course of sedation and respiratory effects were described with population pharmacodynamic models using NONMEM. The probability (P) of a given level of sedation or airway obstruction was related to the estimated effect-site concentration of propofol (Ce) using a logistic regression model. RESULTS: The concentrations predicted by the target-controlled infusion system generally exceeded the measured concentrations. The estimates of C(50) for Ramsay scores 3, 4, and 5 were 0.1, 1.02, and 2.28 microg/ml, respectively. For airway obstruction scores 2 and 3, the estimates of C(50) were 0.32 and 2.98 microg/ml, respectively. Estimates of k(e0) were 0.24 and 0.5 1/min for the sedation and respiratory effects, respectively. CONCLUSIONS: The pharmacokinetic behavior of propofol in patients with Parkinson disease differs with respect to the population from which the model used by the target-controlled infusion device was developed. Based on the results from the final models, a typical steady state plasma propofol concentration of 0.35 microg/ml eliciting a sedation score of 3 with only minimal, if any, airway obstruction has been defined as the therapeutic target