bluuebunny/crossref_metadata_2025 huggingface dataset:
The Core Conclusions and Interpretation of Working Group II Contribution to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change
Authors: LI Xiucang , JIANG Tong , CHAO Qingchen , XU Hongmei , YUAN Jiashuang , LIN Erda
Published: June 2015

Intergovernmental Panel on Climate Change (IPCC) released the Working Group II contribution to the Fifth Assessment Report (WGII AR5) IPCC Climate Change 2014: Impacts, Adaptation, and Vulnerability in March 2014. This paper introduces and interprets this report, making well organization of the main conclusions, analyzing the new enlightenment to China's response to climate change. WGII AR5 focuses on the assessment and management of climate change risks. According to the latest scientific literature and evidences, this report elaborates climate change's broader impacts on water resource, food production, and other natural and human social systems since 2007 IPCC Fourth Assessment Report (AR4). Via the assessment of different areas, regions, and key risks in the future, the report indicates the risk level of climate change faced with the globe under different temperature rise; aiming at risk management, the report emphasizes the significance of promoting and establishing the sustainable development society with recovery capacity through adaptation and mitigation of climate change. As an important scientific basis for international community to recognize and cope with climate change, the publication of IPCC AR5 one after another will have a significant influence on Durban Platform negotiations on post-2020 international climate regime which have been in a difficult stage, and the 2014 United Nations climate change summit [IPCC. 2014. Climate Change 2014: Impact Adaptation, and Vulnerability. Contribution of Working Group II to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. United Kingdom and New York, NY, USA: Cambridge University Press].
Ubiquity symposium 'What is Computation?'
Authors: Wegner Peter
Published: June 2015

In this second article in the ACM Ubiquity symposium on 'What is computation?' Peter Wegner provides a history of the evolution of comptuation. --Editor
Edging Toward the Semantic Web
Authors: Andersen Espen
Published: June 2015

The evolution from an interactive Internet (often called Web 2.0) toward a more intelligent, semantic web will not happen as a result of dramatic new inventions or jointly agreed standards, but through a gradual evolution and recombination of existing technologies. To get to a Web 3.0, we will need to first create (and maybe be satisfied with) a Web 2.5, and that will happen through the gradual evolution of effective, user-based interaction protocols (based on user dialogues) and the use of queries as information passing mechanisms.
Algorithm 949
Authors: Fu Zhixing , Gatica Luis F. , Sayas Francisco-javier
Published: June 2015

In this article, we provide some MATLAB tools for efficient vectorized implementation of the Hybridizable Discontinuous Galerkin for linear variable coefficient reaction-diffusion problems in polyhedral domains. The resulting tools are modular and include enhanced structures to deal with convection-diffusion problems, plus several projection operators and the postprocessing implementation that is necessary to realize the superconvergence property of the method. Loops over the elements are exclusively local and, as such, have been parallelized.
Complex Root Finding Algorithm Based on Delaunay Triangulation
Authors: Kowalczyk Piotr
Published: June 2015

A simple and flexible algorithm for finding zeros of a complex function is presented. An arbitrary-shaped search region can be considered and a very wide class of functions can be analyzed, including those containing singular points or even branch cuts. The proposed technique is based on sampling the function at nodes of a regular or a self-adaptive mesh and on the analysis of the function sign changes. As a result, a set of candidate points is created, where the signs of the real and imaginary parts of the function change simultaneously. To verify and refine the results, an iterative algorithm is applied. The validity of the presented technique is supported by the results obtained in numerical tests involving three different types of functions.
Algorithm 950
Authors: Wittek Peter
Published: June 2015

A hierarchy of semidefinite programming (SDP) relaxations approximates the global optimum of polynomial optimization problems of noncommuting variables. Generating the relaxation, however, is a computationally demanding task, and only problems of commuting variables have efficient generators. We develop an implementation for problems of noncommuting variables that creates the relaxation to be solved by SDPA--a high-performance solver that runs in a distributed environment. We further exploit the inherent sparsity of optimization problems in quantum physics to reduce the complexity of the resulting relaxations. Constrained problems with a relaxation of order two may contain up to a hundred variables. The implementation is available in Python. The tool helps solve such as finding the ground state energy or testing quantum correlations.
Automatic Internationalization for Just In Time Localization of Web-Based User Interfaces
Authors: Leiva Luis A. , Alabau Vicent
Published: June 2015

The need to modify an application so that it can support different languages and cultural settings can appear once the application is finished and even in the market. This may introduce serious time delays and an increase in costs. We solve this problem for web-based software through JITL, a
post-hoc
method to automatically internationalize websites and web-based applications, without having to modify the source code. With JITL, users can pull resource strings out of an arbitrary website and perform on-demand localization tasks. Based on this novel capability, JITL enables a complete infrastructure for collecting, storing, sharing, and delivering website translations, which invokes a number of exciting scenarios. Our studies show that JITL leads to significant savings in terms of user effort and, in consequence, money. With JITL, now it is possible to localize what is needed, when it is needed.
Audio Musical Dice Game
Authors: Lin Yin-Tzu , Liu I-Ting , Jang Jyh-Shing Roger , Wu Ja-Ling
Published: June 2015

This article proposes a framework for creating user-preference-aware music medleys from users' music collections. We treat the medley generation process as an audio version of a musical dice game. Once the user's collection has been analyzed, the system is able to generate various pleasing medleys. This flexibility allows users to create medleys according to the specified conditions, such as the medley structure or the must-use clips. Even users without musical knowledge can compose medley songs from their favorite tracks. The effectiveness of the system has been evaluated through both objective and subjective experiments on individual components in the system.
Multi-Camera Coordination and Control in Surveillance Systems
Authors: Natarajan Prabhu , Atrey Pradeep K. , Kankanhalli Mohan
Published: June 2015

The use of multiple heterogeneous cameras is becoming more common in today's surveillance systems. In order to perform surveillance tasks, effective coordination and control in multi-camera systems is very important, and is catching significant research attention these days. This survey aims to provide researchers with a state-of-the-art overview of various techniques for multi-camera coordination and control (
MC
3
) that have been adopted in surveillance systems. The existing literature on
MC
3
is presented through several classifications based on the applicable architectures, frameworks and the associated surveillance tasks. Finally, a discussion on the open problems in surveillance area that can be solved effectively using
MC
3
and the future directions in
MC
3
research is presented
Cross-Platform Emerging Topic Detection and Elaboration from Multimedia Streams
Authors: Bao Bing-Kun , Xu Changsheng , Min Weiqing , Hossain Mohammod Shamim
Published: June 2015

With the explosive growth of online media platforms in recent years, it becomes more and more attractive to provide users a solution of emerging topic detection and elaboration. And this posts a real challenge to both industrial and academic researchers because of the overwhelming information available in multiple modalities and with large outlier noises. This article provides a method on emerging topic detection and elaboration using multimedia streams cross different online platforms. Specifically, Twitter, New York Times and Flickr are selected for the work to represent the microblog, news portal and imaging sharing platforms. The emerging keywords of Twitter are firstly extracted using aging theory. Then, to overcome the nature of short length message in microblog, Robust Cross-Platform Multimedia Co-Clustering (RCPMM-CC) is proposed to detect emerging topics with three novelties: 1) The data from different media platforms are in multimodalities; 2) The coclustering is processed based on a pairwise correlated structure, in which the involved three media platforms are pairwise dependent; 3) The noninformative samples are automatically pruned away at the same time of coclustering. In the last step of cross-platform elaboration, we enrich each emerging topic with the samples from New York Times and Flickr by computing the implicit links between social topics and samples from selected news and Flickr image clusters, which are obtained by RCPMM-CC. Qualitative and quantitative evaluation results demonstrate the effectiveness of our method.
An Optimizing Code Generator for a Class of Lattice-Boltzmann Computations
Authors: Pananilath Irshad , Acharya Aravind , Vasista Vinay , Bondhugula Uday
Published: June 2015

The Lattice-Boltzmann method (LBM), a promising new particle-based simulation technique for complex and multiscale fluid flows, has seen tremendous adoption in recent years in computational fluid dynamics. Even with a state-of-the-art LBM solver such as Palabos, a user has to still manually write the program using library-supplied primitives. We propose an automated code generator for a class of LBM computations with the objective to achieve high performance on modern architectures. Few studies have looked at time tiling for LBM codes. We exploit a key similarity between stencils and LBM to enable polyhedral optimizations and in turn time tiling for LBM. We also characterize the performance of LBM with the Roofline performance model. Experimental results for standard LBM simulations like Lid Driven Cavity, Flow Past Cylinder, and Poiseuille Flow show that our scheme consistently outperforms Palabos—on average by up to 3× while running on 16 cores of an Intel Xeon (Sandybridge). We also obtain an improvement of 2.47× on the SPEC LBM benchmark.
Creating 2+2 education pathways in cybersecurity
Authors: Hawthorne Elizabeth K.
Published: June 2015

It is a well-documented fact that there are not enough cybersecurity students in the post-secondary pipeline to defend and protect our nation's critical information networks.
Role-Based Process View Derivation and Composition
Authors: Zhao Xiaohui , Liu Chengfei , Yongchareon Sira , Kowalkiewicz Marek , Sadiq Wasim
Published: June 2015

The process view concept deploys a partial and temporal representation to adjust the visible view of a business process according to various perception constraints of users. Process view technology is of practical use for privacy protection and authorization control in process-oriented business management. Owing to complex organizational structure, it is challenging for large companies to accurately specify the diverse perception of different users over business processes. Aiming to tackle this issue, this article presents a role-based process view model to incorporate role dependencies into process view derivation. Compared to existing process view approaches, ours particularly supports runtime updates to the process view perceivable to a user with specific view merging operations, thereby enabling the dynamic tracing of process perception. A series of rules and theorems are established to guarantee the structural consistency and validity of process view transformation. A hypothetical case is conducted to illustrate the feasibility of our approach, and a prototype is developed for the proof-of-concept purpose.
Integrating security in the computer science curriculum
Authors: Siraj Ambareen , Taylor Blair , Kaza Siddarth , Ghafoor Sheikh
Published: June 2015

With increased focus on the global computing infrastructure's vulnerability to cyber-attacks - the time is right for security integration across the computer science curriculum to contribute to a cyber-ready workforce. The challenges to integrating security into computer science (CS) curriculum are significant---lack of faculty to teach security, a dearth of effective teaching resources, and little room to spare in CS curriculum. This article describes an initiative that aims to develop faculty expertise in cybersecurity, provide a library of resources for security education, and build a community of CS educators to prepare computing graduates to meet current and future cybersecurity challenges.
Chimera
Authors: Park Jason Jong Kyu , Park Yongjun , Mahlke Scott
Published: June 2015

The demand for multitasking on graphics processing units (GPUs) is constantly increasing as they have become one of the default components on modern computer systems along with traditional processors (CPUs). Preemptive multitasking on CPUs has been primarily supported through context switching. However, the same preemption strategy incurs substantial overhead due to the large context in GPUs. The overhead comes in two dimensions: a preempting kernel suffers from a long preemption latency, and the system throughput is wasted during the switch. Without precise control over the large preemption overhead, multitasking on GPUs has little use for applications with strict latency requirements.

In this paper, we propose Chimera, a collaborative preemption approach that can precisely control the overhead for multitasking on GPUs. Chimera first introduces streaming multiprocessor (SM) flushing, which can instantly preempt an SM by detecting and exploiting idempotent execution. Chimera utilizes flushing collaboratively with two previously proposed preemption techniques for GPUs, namely context switching and draining to minimize throughput overhead while achieving a required preemption latency. Evaluations show that Chimera violates the deadline for only 0.2% of preemption requests when a 15us preemption latency constraint is used. For multi-programmed workloads, Chimera can improve the average normalized turnaround time by 5.5x, and system throughput by 12.2%.
SD-PCM
Authors: Wang Rujia , Jiang Lei , Zhang Youtao , Yang Jun
Published: June 2015

Phase Change Memory (PCM) has better scalability and smaller cell size comparing to DRAM. However, further scaling PCM cell in deep sub-micron regime results in significant thermal based write disturbance (WD). Naively allocating large inter-cell space increases cell size from 4F
2
ideal to 12F
2
. While a recent work mitigates WD along word-lines through disturbance resilient data encoding, it is ineffective for WD along bit-lines, which is more severe due to widely adopted $\mu$Trench structure in constructing PCM cell arrays. Without mitigating WD along bit-lines, a PCM cell still has 8F2, which is 100% larger than the ideal. In this paper, we propose SD-PCM for achieving reliable write operations in super dense PCM. In particular, we focus on mitigating WD along bit-lines such that we can construct super dense PCM chips with 4F
2
cell size, i.e., the minimal for diode-switch based PCM. Based on simple verification-n-correction (VnC), we propose LazyCorrection and PreRead to effectively reduce VnC overhead and minimize cascading verification during write. We further propose (n:m)-Alloc for achieving good tradeoff between VnC overhead minimization and memory capacity loss. Our experimental results show that, comparing to a WD-free low density PCM, SD-PCM achieves 80% capacity improvement in cell arrays while incurring around 0-10% performance degradation when using different (n:m) allocators.
Freecursive ORAM
Authors: Fletcher Christopher W. , Ren Ling , Kwon Albert , van Dijk Marten , Devadas Srinivas
Published: June 2015

Oblivious RAM (ORAM) is a cryptographic primitive that hides memory access patterns as seen by untrusted storage. Recently, ORAM has been architected into secure processors. A big challenge for hardware ORAM schemes is how to efficiently manage the Position Map (PosMap), a central component in modern ORAM algorithms. Implemented naively, the PosMap causes ORAM to be fundamentally unscalable in terms of on-chip area. On the other hand, a technique called Recursive ORAM fixes the area problem yet significantly increases ORAM's performance overhead.

To address this challenge, we propose three new mechanisms. We propose a new ORAM structure called the PosMap Lookaside Buffer (PLB) and PosMap compression techniques to reduce the performance overhead from Recursive ORAM empirically (the latter also improves the construction asymptotically). Through simulation, we show that these techniques reduce the memory bandwidth overhead needed to support recursion by 95%, reduce overall ORAM bandwidth by 37% and improve overall SPEC benchmark performance by 1.27x. We then show how our PosMap compression techniques further facilitate an extremely efficient integrity verification scheme for ORAM which we call PosMap MAC (PMMAC). For a practical parameterization, PMMAC reduces the amount of hashing needed for integrity checking by >= 68x relative to prior schemes and introduces only 7% performance overhead.

We prototype our mechanisms in hardware and report area and clock frequency for a complete ORAM design post-synthesis and post-layout using an ASIC flow in a 32~nm commercial process. With 2 DRAM channels, the design post-layout runs at 1~GHz and has a total area of .47~mm2. Depending on PLB-specific parameters, the PLB accounts for 10% to 26% area. PMMAC costs 12% of total design area. Our work is the first to prototype Recursive ORAM or ORAM with any integrity scheme in hardware.
Kinetic Dependence Graphs
Authors: Hassaan Muhammad Amber , Nguyen Donald D. , Pingali Keshav K.
Published: June 2015

Task graphs or dependence graphs are used in runtime systems to schedule tasks for parallel execution. In problem domains such as dense linear algebra and signal processing, dependence graphs can be generated from a program by static analysis. However, in emerging problem domains such as graph analytics, the set of tasks and dependences between tasks in a program are complex functions of runtime values and cannot be determined statically. In this paper, we introduce a novel approach for exploiting parallelism in such programs. This approach is based on a data structure called the kinetic dependence graph (KDG), which consists of a dependence graph together with update rules that incrementally update the graph to reflect changes in the dependence structure whenever a task is completed.

We have implemented a simple programming model that allows programmers to write these applications at a high level of abstraction, and a runtime within the Galois system [15] that builds the KDG automatically and executes the program in parallel. On a suite of programs that are difficult to parallelize otherwise, we have obtained speedups of up to 33 on 40 cores, out-performing third-party implementations in many cases.
Monitoring and Debugging the Quality of Results in Approximate Programs
Authors: Ringenburg Michael , Sampson Adrian , Ackerman Isaac , Ceze Luis , Grossman Dan
Published: June 2015

Energy efficiency is a key concern in the design of modern computer systems. One promising approach to energy-efficient computation, approximate computing, trades off output accuracy for significant gains in energy efficiency. However, debugging the actual cause of output quality problems in approximate programs is challenging. This paper presents dynamic techniques to debug and monitor the quality of approximate computations. We propose both offline debugging tools that instrument code to determine the key sources of output degradation and online approaches that monitor the quality of deployed applications.

We present two offline debugging techniques and three online monitoring mechanisms. The first offline tool identifies correlations between output quality and the execution of individual approximate operations. The second tracks approximate operations that flow into a particular value. Our online monitoring mechanisms are complementary approaches designed for detecting quality problems in deployed applications, while still maintaining the energy savings from approximation.

We present implementations of our techniques and describe their usage with seven applications. Our online monitors control output quality while still maintaining significant energy efficiency gains, and our offline tools provide new insights into the effects of approximation on output quality.
Ziria
Authors: Stewart Gordon , Gowda Mahanth , Mainland Geoffrey , Radunovic Bozidar , Vytiniotis Dimitrios , Agullo Cristina Luengo
Published: June 2015

Software-defined radio (SDR) brings the flexibility of software to wireless protocol design, promising an ideal platform for innovation and rapid protocol deployment. However, implementing modern wireless protocols on existing SDR platforms often requires careful hand-tuning of low-level code, which can undermine the advantages of software. Ziria is a new domain-specific language (DSL) that offers programming abstractions suitable for wireless physical (PHY) layer tasks while emphasizing the pipeline reconfiguration aspects of PHY programming. The Ziria compiler implements a rich set of specialized optimizations, such as lookup table generation and pipeline fusion. We also offer a novel -- due to pipeline reconfiguration -- algorithm to optimize the data widths of computations in Ziria pipelines. We demonstrate the programming flexibility of Ziria and the performance of the generated code through a detailed evaluation of a line-rate Ziria WiFi 802.11a/g implementation that is on par and in many cases outperforms a hand-tuned state-of-the-art C++ implementation on commodity CPUs.
Mojim
Authors: Zhang Yiying , Yang Jian , Memaripour Amirsaman , Swanson Steven
Published: June 2015

Next-generation non-volatile memories (NVMs) promise DRAM-like performance, persistence, and high density. They can attach directly to processors to form non-volatile main memory (NVMM) and offer the opportunity to build very low-latency storage systems. These high-performance storage systems would be especially useful in large-scale data center environments where reliability and availability are critical. However, providing reliability and availability to NVMM is challenging, since the latency of data replication can overwhelm the low latency that NVMM should provide. We propose Mojim, a system that provides the reliability and availability that large-scale storage systems require, while preserving the performance of NVMM. Mojim achieves these goals by using a two-tier architecture in which the primary tier contains a mirrored pair of nodes and the secondary tier contains one or more secondary backup nodes with weakly consistent copies of data. Mojim uses highly-optimized replication protocols, software, and networking stacks to minimize replication costs and expose as much of NVMM?s performance as possible. We evaluate Mojim using raw DRAM as a proxy for NVMM and using an industrial NVMM emulation system. We find that Mojim provides replicated NVMM with similar or even better performance than un-replicated NVMM (reducing latency by 27% to 63% and delivering between 0.4 to 2.7X the throughput). We demonstrate that replacing MongoDB's built-in replication system with Mojim improves MongoDB's performance by 3.4 to 4X.
A Hardware Design Language for Timing-Sensitive Information-Flow Security
Authors: Zhang Danfeng , Wang Yao , Suh G. Edward , Myers Andrew C.
Published: June 2015

Information security can be compromised by leakage via low-level hardware features. One recently prominent example is cache probing attacks, which rely on timing channels created by caches. We introduce a hardware design language, SecVerilog, which makes it possible to statically analyze information flow at the hardware level. With SecVerilog, systems can be built with verifiable control of timing channels and other information channels. SecVerilog is Verilog, extended with expressive type annotations that enable precise reasoning about information flow. It also comes with rigorous formal assurance: we prove that SecVerilog enforces timing-sensitive noninterference and thus ensures secure information flow. By building a secure MIPS processor and its caches, we demonstrate that SecVerilog makes it possible to build complex hardware designs with verified security, yet with low overhead in time, space, and HW designer effort.
Temporally Bounding TSO for Fence-Free Asymmetric Synchronization
Authors: Morrison Adam , Afek Yehuda
Published: June 2015

This paper introduces a
temporally bounded total store ordering
(TBTSO) memory model, and shows that it enables
nonblocking fence-free
solutions to
asymmetric synchronization
problems, such as those arising in memory reclamation and biased locking.

TBTSO strengthens the TSO memory model by
bounding
the time it takes a store to drain from the store buffer into memory. This bound enables devising fence-free algorithms for asymmetric problems, which require a performance-critical
fast path
to synchronize with an infrequently executed
slow path
. We demonstrate this by constructing (1) a fence-free version of the
hazard pointers
memory reclamation scheme, and (2) a fence-free
biased lock
algorithm which is compatible with unmanaged environments as it does not rely on safe points or similar mechanisms.

We further argue that TBTSO can be implemented in hardware with modest modifications to existing TSO architectures. However, our design makes assumptions about proprietary implementation details of commercial hardware; it thus best serves as a starting point for a discussion on the feasibility of hardware TBTSO implementation. We also show how minimal OS support enables the adaptation of TBTSO algorithms to x86 systems.
Architectural Support for Cyber-Physical Systems
Authors: Lee Edward A.
Published: June 2015

Cyber-physical systems are integrations of computation, communication networks, and physical dynamics. Although time plays a central role in the physical world, all widely used software abstractions lack temporal semantics. The notion of correct execution of a program written in every widely-used programming language today does not depend on the temporal behavior of the program. But temporal behavior matters in almost all systems, and most particularly in cyber-physical systems. In this talk, I will argue that time can and must become part of the semantics of programs for a large class of applications. To illustrate that this is both practical and useful, we will describe a recent effort at Berkeley in the design and implementation of timing-centric software systems. Specifically, I will describe PRET machines, which redefine the instruction-set architecture (ISA) of a microprocessor to embrace temporal semantics. Such machines can be used in high-confidence and safety-critical systems, in energy-constrained systems, in mixed-criticality systems, and as a Real-Time Unit (RTU) that cooperates with a general-purpose processor to provide real-time services, in a manner similar to how a GPU provides graphics services.
More is Less, Less is More
Authors: Pang Jun , Dwyer Chris , Lebeck Alvin R.
Published: June 2015

Molecular-scale Network-on-Chip (mNoC) crossbars use quantum dot LEDs as an on-chip light source, and chromophores to provide optical signal filtering for receivers. An mNoC reduces power consumption or enables scaling to larger crossbars for a reduced energy budget compared to current nanophotonic NoC crossbars. Since communication latency is reduced by using a high-radix crossbar, minimizing power consumption becomes a primary design target. Conventional Single Writer Multiple Reader (SWMR) photonic crossbar designs broadcast all packets, and incur the commensurate required power, even if only two nodes are communicating.

This paper introduces power topologies, enabled by unique capabilities of mNoC technology, to reduce overall interconnect power consumption. A power topology corresponds to the logical connectivity provided by a given power mode. Broadcast is one power mode and it consumes the maximum power. Additional power modes consume less power but allow a source to communicate with only a statically defined, potentially non-contiguous, subset of nodes. Overall interconnect power is reduced if the more frequently communicating nodes use modes that consume less power, while less frequently communicating nodes use modes that consume more power. We also investigate thread mapping techniques to fully exploit power topologies. We explore various mNoC power topologies with one, two and four power modes for a radix-256 SWMR mNoC crossbar. Our results show that the combination of power topologies and intelligent thread mapping can reduce total mNoC power by up to 51% on average for a set of 12 SPLASH benchmarks. Furthermore performance is 10% better than conventional resonator-based photonic NoCs and energy is reduced by 72%.
Page Placement Strategies for GPUs within Heterogeneous Memory Systems
Authors: Agarwal Neha , Nellans David , Stephenson Mark , O'Connor Mike , Keckler Stephen W.
Published: June 2015

Systems from smartphones to supercomputers are increasingly heterogeneous, being composed of both CPUs and GPUs. To maximize cost and energy efficiency, these systems will increasingly use globally-addressable heterogeneous memory systems, making choices about memory page placement critical to performance. In this work we show that current page placement policies are not sufficient to maximize GPU performance in these heterogeneous memory systems. We propose two new page placement policies that improve GPU performance: one application agnostic and one using application profile information. Our application agnostic policy, bandwidth-aware (BW-AWARE) placement, maximizes GPU throughput by balancing page placement across the memories based on the aggregate memory bandwidth available in a system. Our simulation-based results show that BW-AWARE placement outperforms the existing Linux INTERLEAVE and LOCAL policies by 35% and 18% on average for GPU compute workloads. We build upon BW-AWARE placement by developing a compiler-based profiling mechanism that provides programmers with information about GPU application data structure access patterns. Combining this information with simple program-annotated hints about memory placement, our hint-based page placement approach performs within 90% of oracular page placement on average, largely mitigating the need for costly dynamic page tracking and migration.
Asymmetric Memory Fences
Authors: Duan Yuelu , Honarmand Nima , Torrellas Josep
Published: June 2015

There have been several recent efforts to improve the performance of fences. The most aggressive designs allow post-fence accesses to retire and complete before the fence completes. Unfortunately, such designs present implementation difficulties due to their reliance on global state and structures.

This paper's goal is to optimize both the performance and the implementability of fences. We start-off with a design like the most aggressive ones but without the global state. We call it Weak Fence or wF. Since the concurrent execution of multiple wFs can deadlock, we combine wFs with a conventional fence (i.e., Strong Fence or sF) for the less performance-critical thread(s). We call the result an Asymmetric fence group. We also propose a taxonomy of Asymmetric fence groups under TSO. Compared to past aggressive fences, Asymmetric fence groups both are substantially easier to implement and have higher average performance. The two main designs presented (WS+ and W+) speed-up workloads under TSO by an average of 13% and 21%, respectively, over conventional fences.
VARAN the Unbelievable
Authors: Hosek Petr , Cadar Cristian
Published: June 2015

With the widespread availability of multi-core processors, running multiple diversified variants or several different versions of an application in parallel is becoming a viable approach for increasing the reliability and security of software systems. The key component of such N-version execution (NVX) systems is a runtime monitor that enables the execution of multiple versions in parallel. Unfortunately, existing monitors impose either a large performance overhead or rely on intrusive kernel-level changes. Moreover, none of the existing solutions scales well with the number of versions, since the runtime monitor acts as a performance bottleneck.

In this paper, we introduce Varan, an NVX framework that combines selective binary rewriting with a novel event-streaming architecture to significantly reduce performance overhead and scale well with the number of versions, without relying on intrusive kernel modifications.

Our evaluation shows that Varan can run NVX systems based on popular C10k network servers with only a modest performance overhead, and can be effectively used to increase software reliability using techniques such as transparent failover, live sanitization and multi-revision execution.
Architectural Support for Dynamic Linking
Authors: Agrawal Varun , Dabral Abhiroop , Palit Tapti , Shen Yongming , Ferdman Michael
Published: June 2015

All software in use today relies on libraries, including standard libraries (e.g., C, C++) and application-specific libraries (e.g., libxml, libpng). Most libraries are loaded in memory and dynamically linked when programs are launched, resolving symbol addresses across the applications and libraries. Dynamic linking has many benefits: It allows code to be reused between applications, conserves memory (because only one copy of a library is kept in memory for all the applications that share it), and allows libraries to be patched and updated without modifying programs, among numerous other benefits. However, these benefits come at the cost of performance. For every call made to a function in a dynamically linked library, a trampoline is used to read the function address from a lookup table and branch to the function, incurring memory load and branch operations. Static linking avoids this performance penalty, but loses all the benefits of dynamic linking. Given its myriad benefits, dynamic linking is the predominant choice today, despite the performance cost. In this work, we propose a speculative hardware mechanism to optimize dynamic linking by avoiding executing the trampolines for library function calls, providing the benefits of dynamic linking with the performance of static linking. Speculatively skipping the memory load and branch operations of the library call trampolines improves performance by reducing the number of executed instructions and gains additional performance by reducing pressure on the instruction and data caches, TLBs, and branch predictors. Because the indirect targets of library call trampolines do not change during program execution, our speculative mechanism never misspeculates in practice. We evaluate our technique on real hardware with production software and observe up to 4% speedup using only 1.5KB of on-chip storage.
Chemical Approaches to Discovery and Study of Sources and Targets of Hydrogen Peroxide Redox Signaling Through NADPH Oxidase Proteins
Authors: Brewer Thomas F. , Garcia Francisco J. , Onak Carl S. , Carroll Kate S. , Chang Christopher J.
Published: June 2015

Hydrogen peroxide (H2O2) is a prime member of the reactive oxygen species (ROS) family of molecules produced during normal cell function and in response to various stimuli, but if left unchecked, it can inflict oxidative damage on all types of biological macromolecules and lead to cell death. In this context, a major source of H2O2 for redox signaling purposes is the NADPH oxidase (Nox) family of enzymes, which were classically studied for their roles in phagocytic immune response but have now been found to exist in virtually all mammalian cell types in various isoforms with distinct tissue and subcellular localizations. Downstream of this tightly regulated ROS generation, site-specific, reversible covalent modification of proteins, particularly oxidation of cysteine thiols to sulfenic acids, represents a prominent posttranslational modification akin to phosphorylation as an emerging molecular mechanism for transforming an oxidant signal into a dynamic biological response. We review two complementary types of chemical tools that enable (a) specific detection of H2O2 generated at its sources and (b) mapping of sulfenic acid posttranslational modification targets that mediate its signaling functions, which can be used to study this important chemical signal in biological systems.
Mechanisms of Methicillin Resistance in Staphylococcus aureus
Authors: Peacock Sharon J. , Paterson Gavin K.
Published: June 2015

Staphylococcus aureus is a major human and veterinary pathogen worldwide. Methicillin-resistant S. aureus (MRSA) poses a significant and enduring problem to the treatment of infection by such strains. Resistance is usually conferred by the acquisition of a nonnative gene encoding a penicillin-binding protein (PBP2a), with significantly lower affinity for β-lactams. This resistance allows cell-wall biosynthesis, the target of β-lactams, to continue even in the presence of typically inhibitory concentrations of antibiotic. PBP2a is encoded by the mecA gene, which is carried on a distinct mobile genetic element (SCCmec), the expression of which is controlled through a proteolytic signal transduction pathway comprising a sensor protein (MecR1) and a repressor (MecI). Many of the molecular and biochemical mechanisms underlying methicillin resistance in S. aureus have been elucidated, including regulatory events and the structure of key proteins. Here we review recent advances in this area.
A new approach for laboratory exercise of pathophysiology in China based on student-centered learning
Authors: Chen Jian , Zhou Junhai , Sun Li , Wu Qiuhui , Lu Huiling , Tian Jing
Published: June 2015

Student-centered learning is generally defined as any instructional method that purportedly engages students in active learning and critical thinking. The student-centered method of teaching moves the focus from teaching to learning, from the teachers' conveying course concepts via lecture to the understanding of concepts by students. The student-centered method has been used extensively in lecture courses in China; however, there is little evidence of its use in laboratory courses. The purpose of the present study was to describe the implementation of a student-centered method in a pathophysiology laboratory course. The use of student-centered learning strategies in an undergraduate laboratory course was well received by both students and teachers. Here, students had to take on responsibility for their own learning and, thus, became more accountable. Moreover, they reported increased active learning, skill development, information collection, and retention. In addition, mean scores for the quiz were significantly higher in the student-centered method compared with the traditional teaching method. The shift from teacher-centered delivery to a student-centered model led to a positive change, in which the learners drove the process and were guided, not directed, by the teacher.
Effect of an exercise and weight control curriculum: views of obesity among exercise science students
Authors: Richardson Laura A. , Fister Carrie L. , Ramlo Susan E.
Published: June 2015

Awareness of effective weight management strategies is necessary to prepare exercise science students for future work with obesity. Exercise science faculty members developed a course related to exercise as a therapeutic tool and options available for weight loss. The purpose of the present study was to investigate student views of weight management and obesity, which can be a difficult task using traditional methods such as Likert scale surveys. To investigate student views relative to the course content, Q methodology, which is a mixed-method research approach, was used at the beginning and end of the course. Students completed a Q sort, ranking 44 statements related to obesity in accordance to their own points of view. The pretest/posttest design enabled an opportunity to determine if course goals were accomplished and if student perceptions related to obesity were transformed. Factor analysis of precourse sorts revealed that students possessed a naïve singular view of weight-related concepts. Analysis of sorts at course completion resulted in a two-factor solution revealing changes in perspective; some students took on a health professional type of view, whereas others demonstrated antifat views. In conclusion, the findings revealed key variables that should be addressed in curricula involving therapeutic obesity interventions. An improved curriculum based on these results should better encourage students to develop a broad comprehension of multifactorial causes and treatment for weight management and obesity. Implementing the use of Q methodology may serve as a valuable asset to measure and evaluate subjectivity of obesity discrimination. Antifat attitudes among exercise science students may influence future clients' potential achievements.
Muscle transcriptome response to ACTH administration in a free-ranging marine mammal
Authors: Khudyakov Jane I. , Champagne Cory D. , Preeyanon Likit , Ortiz Rudy M. , Crocker Daniel E.
Published: June 2015

While much of our understanding of stress physiology is derived from biomedical studies, little is known about the downstream molecular consequences of adaptive stress responses in free-living animals. We examined molecular effectors of the stress hormones cortisol and aldosterone in the northern elephant seal, a free-ranging study system in which extreme physiological challenges and cortisol fluctuations are a routine part of life history. We stimulated the neuroendocrine stress axis by administering exogenous adrenocorticotropic hormone (ACTH) and examined the resultant effects by measuring corticosteroid hormones, metabolites, and gene expression before, during, and following administration. ACTH induced an elevation in cortisol, aldosterone, glucose, and fatty acids within 2 h, with complete recovery observed within 24 h of administration. The global transcriptional response of elephant seal muscle tissue to ACTH was evaluated by transcriptomics and involved upregulation of a highly coordinated network of conserved glucocorticoid (GC) target genes predicted to promote metabolic substrate availability without causing deleterious effects seen in laboratory animals. Transcriptional recovery from ACTH was characterized by downregulation of GC target genes and restoration of cell proliferation, metabolism, and tissue maintenance pathways within 24 h. Differentially expressed genes included several adipokines not previously described in muscle, reflecting unique metabolic physiology in fasting-adapted animals. This study represents one of the first transcriptome analyses of cellular responses to hypothalamic-pituitary-adrenal axis stimulation in a free-living marine mammal and suggests that compensatory, tissue-sparing mechanisms may enable marine mammals to maintain cortisol and aldosterone sensitivity while avoiding deleterious long-term consequences of stress.
Robust Hierarchical Control for Uncertain Multivariable Hexarotor Systems
Authors: Lin Wei , Liu Hao
Published: June 2015

Multirotor helicopter attracts more attention due to its increased load capacity and being highly maneuverable. However, these helicopters are uncertain multivariable systems, which pose a challenge for their robust controller design. In this paper, a robust two-loop control scheme is proposed for a hexarotor system. The resulted controller consists of a nominal controller and a robust compensator. The robust compensators are added to restrain the influences of uncertainties such as nonlinear dynamics, coupling, parametric uncertainties, and external disturbances. It is proven that the tracking errors are ultimately bounded with specified boundaries by choosing the parameters of the robust compensators. Simulation results on the hexarotor demonstrate the effectiveness of the proposed control method.
Simulation, Modeling, and Analysis of Soliton Waves Interaction and Propagation in CNN Transmission Lines for Innovative Data Communication and Processing
Authors: Borgese G. , Vena S. , Pantano P. , Pace C. , Bilotta E.
Published: May 2015

We present an innovative approach to study the interaction between oblique solitons, using nonlinear transmission lines, based on Cellular Neural Network (CNN) paradigm. A single transmission line consists of a 1D array of cells that interact with neighboring cells, through both linear and nonlinear connections. Each cell is controlled by a nonlinear Ordinary Differential Equation, in particular the Korteweg de Vries equation, which defines the cell status and behavior. Two typologies of CNN transmission lines are modelled: crisscross and ring lines. In order to solve KdV equations two different methods are used: 4th-order Runge-Kutta and Forward Euler methods. This is done to evaluate their accuracy and stability with the purpose of implementing CNN transmission lines on embedded systems such as FPGA and microcontrollers. Simulation/analysis Graphic User Interface platforms are designed to conduct numerical simulations and to display elaboration results. From this analysis it is possible both to identify the presence and the propagation of soliton waves on the transmission lines and to highlight the interaction between solitons and rich nonlinear dynamics. With this approach it is possible to simulate and develop the transmission and processing of information within large brain networks and high density sensor systems.
The Effect of Long-Term Intranasal Serotonin Treatment on Metabolic Parameters and Hormonal Signaling in Rats with High-Fat Diet/Low-Dose Streptozotocin-Induced Type 2 Diabetes
Authors: Derkach Kira V. , Bondareva Vera M. , Chistyakova Oxana V. , Berstein Lev M. , Shpakov Alexander O.
Published: June 2015

In the last years the treatment of type 2 diabetes mellitus (DM2) was carried out using regulators of the brain signaling systems. In DM2 the level of the brain serotonin is reduced. So far, the effect of the increase of the brain serotonin level on DM2-induced metabolic and hormonal abnormalities has been studied scarcely. The present work was undertaken with the aim of filling this gap. DM2 was induced in male rats by 150-day high-fat diet and the treatment with low dose of streptozotocin (25 mg/kg) on the 70th day of experiment. From the 90th day, diabetic rats received for two months intranasal serotonin (IS) at a daily dose of 20 μg/rat. The IS treatment of diabetic rats decreased the body weight, and improved glucose tolerance, insulin-induced glucose utilization, and lipid metabolism. Besides, it restored hormonal regulation of adenylyl cyclase (AC) activity in the hypothalamus and normalized AC stimulation byβ-adrenergic agonists in the myocardium. In nondiabetic rats the same treatment induced metabolic and hormonal alterations, some of which were similar to those in DM2 but expressed to a lesser extent. In conclusion, the elevation of the brain serotonin level may be regarded as an effective approach to treat DM2 and its complications.