A versatile content addressable memory architecture

In this paper, a novel configurable content addressable memory (CCAM) cell is proposed, to increase the flexibility of embedded CAMs for SoC employment. It can be easily configured as a Binary CAM (BiCAM) or Ternary CAM (TCAM) without significant penalty of power consumption or searching speed. A 64x128 CCAM array has been built and verified through simulation. ©2007 IEEE.

Packet classification by multi-level cutting of the classification space

Traditionally, the Internet provides only a “best-effort” service, treating all packets going to the same destination equally. However, providing differentiated services for different users based on their quality requirements is increasingly becoming a demanding issue. For this, routers need to have the capability to distinguish and isolate traffic belonging to different flows. This ability to determine the flow each packet belongs to is called packet classification. Technology vendors are reluctant to support algorithmic solutions for classification due to their nondeterministic performance. Although content addressable memories (CAMs) are favoured by technology vendors due to their deterministic high-lookup rates, they suffer from the problems of high-power consumption and high-silicon cost. This paper provides a new algorithmic-architectural solution for packet classification that mixes CAMs with algorithms based on multilevel cutting of the classification space into smaller spaces. The provided solution utilizes the geometrical distribution of rules in the classification space. It provides the deterministic performance of CAMs, support for dynamic updates, and added flexibility for system designers.

On The Energy-Efficiency of Byte-Addressable Non-Volatile Memory

Non-Volatile Memory (NVM) technology holds promise to replace SRAM and DRAM at various levels of the memory hierarchy. The interest in NVM is motivated by the difficulty faced in scaling DRAM beyond 22 nm and, long-term, lower cost per bit. While offering higher density and negligible static power (leakage and refresh), NVM suffers increased latency and energy per memory access. This paper develops energy and performance models of memory systems and applies them to understand the energy-efficiency of replacing or complementing DRAM with NVM. Our analysis focusses on the application of NVM in main memory. We demonstrate that NVM such as STT-RAM and RRAM is energy-efficient for memory sizes commonly employed in servers and high-end workstations, but PCM is not. Furthermore, the model is well suited to quickly evaluate the impact of changes to the model parameters, which may be achieved through optimization of the memory architecture, and to determine the key parameters that impact system-level energy and performance.

Prisons Memory Archive

Between 2006 and 2007, the Prisons Memory Archive (PMA) filmed participants, including former prisoners, prison staff, teachers, chaplains, visitors, solicitors and welfare workers back inside the Maze/Long Kesh Prison and Armagh Gaol. They shared the memory of the time spent in these prisons during the period of political violence from 1970 - 2000 in Northern Ireland, commonly known as the Troubles. Underpinning the overall methodology is co-ownership of the material, which gives participants the right to veto as well as to participate in the processes of editing and exhibiting their stories, so prioritising the value of co-authorship of their stories. The PMA adopted life-story interviewing techniques with the empty sites stimulating participants’ memory while they walked and talked their way around the empty sites. A third feature is inclusivity: the archive holds stories from across the full spectrum of the prison experience. A selection of the material, with accompanying context and links is available online www.prisonsmemoryarchive.com

Further Information:

The protocols of inclusivity, co-ownership and life-story telling make this collection significant as an initiative that engages with contemporary problems of how to negotiate narratives about a conflicted past in a society emerging out of violence. Inclusivity means that prison staff, prisoners, governors, chaplains, tutors and visitors have participated, relating their individual and collective experiences, which sit side by side on the PMA website. Co-ownership addresses the issues of ethics and sensitivity, allowing key constituencies to be involved. Life-story telling, based on oral history methodologies allows participants to be the authors of their own stories, crucial when dealing with sensitive issues from a violent past. The website hosts a selection of excerpts, e.g. the Armagh Stories page shows excerpts from 15 participants, while the Maze and Long Kesh Prison page offers interactive access to 24 participants from that prison. Using an interactive documentary structure, the site offers users opportunities to navigate their own way through the material and encourages them to hear and see the ‘other’, central to attempts at encouraging dialogue in a divided society. Further, public discussions have been held after screening of excerpts with community groups in the following locations - Belfast, Newtownabbey, Derry, Armagh, Enniskillen, London, Cork, Maynooth, Clones, and Monaghan. Extracts have been screened at international academic conferences in Valencia, Australia, Tartu, Estonia, Prague, and York. A dataset of the content, with description and links, is available for REF purposes.

What the newspapers say about medication adherence: a content analysis

Background: This study investigates the coverage of adherence to medicine by the UK and US newsprint media. Adherence to medicine is recognised as an important issue facing healthcare professionals and the newsprint media is a key source of health information, however, little is known about newspaper coverage of medication adherence.

Methods. A search of the newspaper database Nexis®UK from 2004-2011 was performed. Content analysis of newspaper articles which referenced medication adherence from the twelve highest circulating UK and US daily newspapers and their Sunday equivalents was carried out. A second researcher coded a 15% sample of newspaper articles to establish the inter-rater reliability of coding.

Results: Searches of newspaper coverage of medication adherence in the UK and US yielded 181 relevant articles for each country. There was a large increase in the number of scientific articles on medication adherence in PubMed® over the study period, however, this was not reflected in the frequency of newspaper articles published on medication adherence. UK newspaper articles were significantly more likely to report the benefits of adherence (p = 0.005), whereas US newspaper articles were significantly more likely to report adherence issues in the elderly population (p = 0.004) and adherence associated with diseases of the central nervous system (p = 0.046). The most commonly reported barriers to adherence were patient factors e.g. poor memory, beliefs and age, whereas, the most commonly reported facilitators to adherence were medication factors including simplified regimens, shorter treatment duration and combination tablets. HIV/AIDS was the single most frequently cited disease (reported in 20% of newspaper articles). Poor quality reporting of medication adherence was identified in 62% of newspaper articles.

Conclusion: Adherence is not well covered in the newspaper media despite a significant presence in the medical literature. The mass media have the potential to help educate and shape the public's knowledge regarding the importance of medication adherence; this potential is not being realised at present. © 2013 Goodfellow et al.; licensee BioMed Central Ltd.

Effect of Post-weld Heat-treatment on the Stress Corrosion Cracking Behaviour of Laser-welded Shape Memory NiTi Wires in Hanks’ Solution

In this study, the stress-corrosion cracking (SCC) behaviour of laser-welded NiTi wires before and after post-weld heat-treatment (PWHT) was investigated. The samples were subjected to slow strain rate testing (SSRT) under tensile loading in Hanks’ solution at 37.5 °C (or 310.5 K) at a constant anodic potential (200 mVSCE). The current density of the samples during the SSRT was captured by a potentiostat, and used as an indicator to determine the susceptibility to SCC. Fractography was analyzed using scanning-electron microscopy (SEM). The experimental results showed that the laser-welded sample after PWHT was immune to the SCC as evidenced by the stable current density throughout the SSRT. This is attributed to the precipitation of fine and coherent nano-sized Ni4Ti3 precipitates in the welded regions (weld zone, WZ and heat-affected zone, HAZ) after PWHT, resulting in (i) enrichment of TiO2 content in the passive film and (ii) higher resistance against the local plastic deformation in the welded regions.

Energy-Efficient In-Memory Data Stores on Hybrid Memory Hierarchies

Increasingly large amounts of data are stored in main memory of data center servers. However, DRAM-based memory is an important consumer of energy and is unlikely to scale in the future. Various byte-addressable non-volatile memory (NVM) technologies promise high density and near-zero static energy, however they suffer from increased latency and increased dynamic energy consumption.

This paper proposes to leverage a hybrid memory architecture, consisting of both DRAM and NVM, by novel, application-level data management policies that decide to place data on DRAM vs. NVM. We analyze modern column-oriented and key-value data stores and demonstrate the feasibility of application-level data management. Cycle-accurate simulation confirms that our methodology reduces the energy with least performance degradation as compared to the current state-of-the-art hardware or OS approaches. Moreover, we utilize our techniques to apportion DRAM and NVM memory sizes for these workloads.