With the advent of byte-addressable Non-Volatile Memory (NVMM), the need for a safe, scalable and high-performing memory allocator is inevitable. A slow memory allocator can bottleneck the entire application stack, while an unsecure memory allocator can render underlying systems and applications inconsistent upon program bugs or system failure. Unlike DRAM-based memory allocators, it is indispensable for an NVMM allocator to guarantee its heap metadata safety from both internal and external errors. An effective NVMM memory allocator should be 1) safe 2) scalable and 3) high performing. Unfortunately, none of the existing persistent memory allocators achieve all three requisites; critically, we also note: the de-facto NVMM allocator, Intel's Persistent Memory Development Kit (PMDK), is vulnerable to silent data corruption and persistent memory leaks as result of a simple heap overflow. We closely investigate the existing defacto NVMM memory allocators, especially PMDK, to study their vulnerability to metadata corruption and reasons for poor performance and scalability. We propose Poseidon, which is safe, fast and scalable. The premise of Poseidon revolves around providing a user application with per-CPU sub-heaps for scalability, while managing the heap metadata in a segregated fashion and efficiently protecting the metadata using a scalable hardware-based protection scheme, Intel's Memory Protection Keys (MPK). We evaluate Poseidon with a wide array of microbenchmarks and real-world benchmarks, noting: Poseidon outperforms the state-of-art allocators by a significant margin, showing improved scalability and performance, while also guaranteeing metadata safety. / Master of Science / Since the dawn of time, civilization has revolved around effective communication. From smoke signals to telegraphs and beyond, communication has continued to be a cornerstone of successful societies. Today, communication and collaboration occur, daily, on a global scale, such that even sub-second units of time are critical to successful societal operation. Naturally, many forms of modern communication revolve around our digital systems, such as personal computers, email servers, and social networking database applications. There is, thus, a never-ending surge of digital system development, constantly striving toward increased performance. For some time, increasing a system's dynamic random-access memory, or DRAM, has been able to provide performance gains; unfortunately, due to thermal and power constraints, such an increase is no longer feasible. Additionally, loss of power on a DRAM system causes bothersome loss of data, since the memory storage is volatile to power loss. Now, we are on the advent of an entirely new physical memory system, termed non-volatile main memory (NVMM), which has near identical performance properties to DRAM, but is operational in much larger quantities, thus allowing increased overall system speed. Alas, such a system also imposes additional requirements upon software developers; since, for NVMM, all memory updates are permanent, such that a failed update can cause persistent memory corruption. Regrettably, the existing software standard, led by Intel's Persistent Memory Development Kit (PMDK), is both unsecure (allowing for permanent memory corruption, with ease), low performance, and a bottleneck for multicore systems. Here, we present a secure, high performing solution, termed Poseidon, which harnesses the full potential of NVMM.

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京都大学 / 0048 / 新制・課程博士 / 博士(人間・環境学) / 甲第20460号 / 人博第810号 / 新制||人||194(附属図書館) / 28||人博||810(吉田南総合図書館) / 京都大学大学院人間・環境学研究科相関環境学専攻 / (主査)教授 田部 勢津久, 教授 加藤 立久, 教授 吉田 寿雄 / 学位規則第4条第1項該当 / Doctor of Human and Environmental Studies / Kyoto University / DFAM

Persistent memory (PM) is expected to augment or replace DRAM as main memory. PM combines byte-addressability with non-volatility, providing an opportunity to host byte-addressable data persistently. There are two main approaches for utilizing PM: either as memory mapped files or as persistent memory objects (PMOs). Memory mapped files require that programmers reconcile two different semantics (file system and virtual memory) for the same underlying data, and require the programmer use complicated transaction semantics to keep data crash consistent. To solve this problem, the first part of this dissertation designs, implements, and evaluates a new PMO abstraction that addresses these problems by hosting data in pointer-rich data structures without the backing of a filesystem, and introduces a new primitive, psync, that when invoked renders data crash consistent while concealing the implementation details from the programmer via shadowing. This new approach outperforms a state-of-the-art memory mapped design by 3.2 times depending on the workload. It also addresses the security of at-rest PMOs, by providing for encryption and integrity verification of PMOs. To do this, it performs encryption and integrity verification on the entire PMO, which adds an overhead of between 3-46% depending on the level of protection. The second part of this dissertation demonstrates how crash consistency, security, and integrity verification can be conserved while the overall overhead is reduced by decrypting individual memory pages instead of the entire PMO, yielding performance improvements compared to the original whole PMO design of 2.62 times depending on the workload. The final part of this dissertation improves the performance of PMOs even further by mapping userspace pages to volatile memory and copying them into PM, rather than directly writing to PM. Bundling this design with a stream buffer predictor to decrypt pages into DRAM ahead of time improves performance by 1.9 times.

Botnets are a pervasive threat to the Internet and its inhabitants. A botnet is a collection of infected machines that receive commands from the botmaster, a person, group or nation- state, to perform malicious actions. Instead of “cleaning” individual infections, one can sever the method of communication between a botmaster and her zombies by attempting a botnet takedown, which contains the botnet and its malicious actions. Unfortunately, takedowns are currently performed without technical rigor nor are there automated and independent means to measure success or assist in performing them. This dissertation focuses on understanding the criminal infrastructure that enables communication between a botmaster and her zombies in order to measure attempts at, and to perform, successful takedowns. We show that by interrogating malware and performing large-scale analysis of passively collected network data, we can measure if a past botnet takedown was successful and use the same techniques to perform more comprehensive takedowns in the future.

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Disease management along the boundaries of wildlife reserves is a growing conservation problem worldwide, as infected wildlife can migrate outside protected areas and pose a threat to livestock and human health. The bison Bison bison population in Yellowstone National Park has long been infected with Brucella abortus, the bacterium causing bovine brucellosis. Concern over migratory bison transmitting B. abortus to cattle herds on lands adjacent to Yellowstone has led to proposals for bison vaccination. Model simulations suggest that vaccination is unlikely to eradicate B. abortus from Yellowstone bison but could be an effective tool for reducing the level of infection and eliminating unpopular management practices such as lethal culling. The culling of Yellowstone bison to reduce the risk of brucellosis transmission to cattle is negatively affecting long-term bison conservation because of difficulties in diagnosing actively infected animals. Age-specific serology and B. abortus culture assays from slaughtered bison were used to develop a diagnostic tool to estimate whether particular animals are infective. Findings suggest that active B. abortus infection is age-dependent, which allows true infection probabilities to be estimated based on age and quantitative diagnostic tests. Active brucellosis infection was associated with below-average nutritional condition, with the intensity of B. abortus infection being influenced by seasonal reductions in dietary protein and energy. The reproductive strategy of Yellowstone bison is linked with the seasonal availability of food, which increases bison fitness but may have consequences for B. abortus infection. Seasonal food restriction may also influence the ability of vaccinated bison to recall protective immune responses when later exposed to B. abortus. The rate of fat metabolism was an important factor influencing cell-mediated responses. Thus, individual variation and the seasonal availability of food may reduce vaccine efficacy when vaccination is applied at the population level. Consequently, effective management practices will require a diverse range of integrated methods, which include maintaining separation of livestock and wildlife, managing habitat to reduce brucellosis transmission, and reducing disease prevalence in wildlife. The long-term success of these management practices will depend on sound science and support of the stakeholders involved.

<p>An extensive use of chemicals in countless consumer products has resulted in human exposure to several persistent organic pollutants (POPs). Sufficient knowledge about their chemical composition properties and environmental faith is required, to be able to proper risk assess and regulate the substances. Significant data gaps exist regarding knowledge of actual exposure to humans and toxicological effect data.</p><p>The objective of this thesis was to add human exposure data of a few POPs from four case studies. The analytes discussed in this thesis are polychlorinated dibenzo-p-dioxins and furans (PCDDs/PCDFs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecane (HBCDD).</p><p>Three European populations were studied. Milk was analysed from a group of women, who were accidentally exposed to high levels of 2,3,7,8-TetraCDD (TCDD) in Seveso, 1976. Still today, twice as high TCDD levels were recorded in the milk, compared to background concentrations. Serum was analysed from mothers and their infants from The Netherlands. Cord serum contained equal amounts of POPs as in mother’s blood, indicating non-hindered placenta transfer. Serum analysed from Swedish men and women with a high fish intake had elevated PCB and PCB metabolite (OH-PCB) levels. Additionally, butter was collected worldwide and shown to be a suitable matrix for dairy product survey of POPs.</p><p>The exposure levels in the four papers were compared to recently reported exposure levels in Europe. It is indicated in the thesis that the PCDDs/PCDFs and PCBs toxic equivalency (TEQ) levels are of concern, i.e. the ratio between threshold levels for adverse health effects and TEQ exposure levels is lower than requested margin of safety. Average levels of PBDE/HBCDD in the European population are estimated to be of no concern today, but for individuals with intakes at the 95th percentile are the current margins of safety small.</p>

Recruitment of American eels (Anguilla rostrata) to Lake Ontario has declined rapidly over the past few decades. The commercial yellow eel fishery in Lake Ontario was closed in 2004 due to a lack of eel abundance. Researchers have been attempting to ascertain the reasons for the decline, although thus far, without definitive answers. In this thesis, the question of chemical contamination is addressed as it relates to female eel spawner quality. Spatial concentration trends of halogenated persistent organic pollutants (POPs) are described in eels collected from across eastern Canada, as well as temporal concentration trends in eels collected from a historically important area of northeastern Lake Ontario, Canada. Chlorinated POPs in eels, namely, organochlorinated pesticides, polychlorinated biphenyls, polychlorinated dibenzo-p-dioxins and dibenzofurans are all significantly less than historic values which peaked in the 1960-70s. Measured concentrations of chlorinated POPs in eels from Lake Ontario have decreased by up to 3-fold over the past three decades, and exceeded toxicity thresholds historically for surrogate species (European eel and lake trout). Thus, chlorinated POPs may have had an effect on spawner quality. Concentrations of legacy POPs in eels were dependent on their origin, with eels from highly urbanized and industrialized areas having significantly higher concentrations than eels captured in less developed regions. Similar trends were observed for polybrominated diphenyl ethers and chlorinated norbornene flame retardants. A number of emerging brominated compounds were also measured in these eels by non-target analysis including bromophenols, bromobenzenes, and bromoanisoles. This thesis demonstrates that eels are an ideal species to investigate local sources of pollution, and provide chemical data that may be used in the future, when more toxicity information is available for eels, to assess the health risks posed by accumulated chemical contaminants. / Thesis (Ph.D, Chemistry) -- Queen's University, 2013-05-23 09:27:59.593

Previous studies have reported that deficits in attention are often a common complaint in individuals suffering from pain and attentional impairment in patients with pain has been demonstrated on a variety of neuropsychological measures. Much of the research to-date, however, has not taken into account extraneous factors that may contribute to observed cognitive deficits. Using the California Verbal Learning Test - II, attention and memory performance was examined in two clinical populations (pain and mild traumatic brain injury) while controlling for effort using the Word Memory Test. Controlling for effort led to different explanations of poor performance on attention variables. While mild deficits were expected, and could be accounted for by psychological factors (i.e. somatization), extremely poor performance was more likely related to poor effort. The findings of this study strongly support the necessity of measuring effort during neuropsychological and pain psychological evaluations.