On-stack replacement, distilled

On-stack replacement (OSR) is essential technology for adaptive optimization, allowing changes to code actively executing in a managed runtime. The engineering aspects of OSR are well-known among VM architects, with several implementations available to date. However, OSR is yet to be explored as a general means to transfer execution between related program versions, which can pave the road to unprecedented applications that stretch beyond VMs. We aim at filling this gap with a constructive and provably correct OSR framework, allowing a class of general-purpose transformation functions to yield a special-purpose replacement. We describe and evaluate an implementation of our technique in LLVM. As a novel application of OSR, we present a feasibility study on debugging of optimized code, showing how our techniques can be used to fix variables holding incorrect values at breakpoints due to optimizations

On the state of Latin American states: approaching the bicentenary

Praca recenzowana / Peer-reviewed paperWhat is the actual condition of the state in Latin America? Each contributor to this volume has been invited to answer this question by writing an interpretative essay from a specifically suggested angle: the origins of the state; government and society; economic growth; society and economy; nation-building; the indigenous population; political culture; international relations etc. It was the contributors’ decision which particular states to focus on in order to best illuminate the issues involved. Our main focus in the volume is on outlining some of the processes concerning the state now, two hundred years since the first declarations of independence. Along the way, we tackle both theoretical and normative issues. All the contributors to this volume share a long-cultivated multidisciplinary research interest in Latin America but the volume also reflects our disagreement on what we take the state to be as well as on the prevailing situation in Latin America. Each chapter reflects the views of its author all the way down to his choice of British or American English. As a result all chapters reflect the authors’ views on the contemporary state of the State in Latin America, as well as – why not say it – the authors’ identities. The book is aimed primarily at academics and students of the humanities and social sciences

Write-rationing garbage collection for hybrid memories

Emerging Non-Volatile Memory (NVM) technologies offer high capacity and energy efficiency compared to DRAM, but suffer from limited write endurance and longer latencies. Prior work seeks the best of both technologies by combining DRAM and NVM in hybrid memories to attain low latency, high capacity, energy efficiency, and durability. Coarse-grained hardware and OS optimizations then spread writes out (wear-leveling) and place highly mutated pages in DRAM to extend NVM lifetimes. Unfortunately even with these coarse-grained methods, popular Java applications exact impractical NVM lifetimes of 4 years or less. This paper shows how to make hybrid memories practical, without changing the programming model, by enhancing garbage collection in managed language runtimes. We find object write behaviors offer two opportunities: (1) 70% of writes occur to newly allocated objects, and (2) 2% of objects capture 81% of writes to mature objects. We introduce writerationing garbage collectors that exploit these fine-grained behaviors. They extend NVM lifetimes by placing highly mutated objects in DRAM and read-mostly objects in NVM. We implement two such systems. (1) Kingsguard-nursery places new allocation in DRAM and survivors in NVM, reducing NVM writes by 5x versus NVM only with wear-leveling. (2) Kingsguard-writers (KG-W) places nursery objects in DRAM and survivors in a DRAM observer space. It monitors all mature object writes and moves unwritten mature objects from DRAM to NVM. Because most mature objects are unwritten, KG-W exploits NVM capacity while increasing NVM lifetimes by 11x. It reduces the energy-delay product by 32% over DRAM-only and 29% over NVM-only. This work opens up new avenues for making hybrid memories practical

A multiplex marker set for microsatellite typing and sexing of sooty terns Onychoprion fuscatus

OBJECTIVES: Seabirds have suffered dramatic population declines in recent decades with one such species being the sooty tern Onychoprion fuscatus. An urgent call to re-assess their conservation status has been made given that some populations, such as the one on Ascension Island, South Atlantic, have declined by over 80% in three generations. Little is known about their population genetics, which would aid conservation management through understanding ecological processes and vulnerability to environmental change. We developed a multiplex microsatellite marker set for sooty terns including sex-typing markers to assist population genetics studies. RESULTS: Fifty microsatellite loci were isolated and tested in 23 individuals from Ascension Island. Thirty-one were polymorphic and displayed between 4 and 20 alleles. Three loci were Z-linked and two autosomal loci deviated from Hardy-Weinberg equilibrium. The remaining 26 autosomal loci together with three sex-typing makers were optimised in seven polymerase chain reaction plexes. These 26 highly polymorphic markers will be useful for understanding genetic structure of the Ascension Island population and the species as a whole. Combining these with recently developed microsatellite markers isolated from Indian Ocean birds will allow for assessment of global population structure and genetic diversity

Effect of creep on time-dependent behaviour of prestressed concrete integral abutment bridge

A parametric study was conducted to assess effect of creep on long term behaviour of prestressed concrete Integral Abutment Bridge (IAB). Varying backfill soil types were provided behind the bridge abutment and the interaction was modelled using linear springs. The effect of backfill soil type on the behaviour of the bridge was assessed through 75-year time-history simulations carried out in Commercial Finite Element Software (LUSAS). CEB-FIP 1990 creep model was used to analyse the linear viscoelastic behaviour of creep. The result has shown that creep and backfill soil type have a no severe effect on the behaviour of the bridge