bluuebunny/crossref_metadata_2025_split huggingface dataset:
Hardware support for fine-grained event-driven computation in Anton 2
Authors: Grossman J. P. , Kuskin Jeffrey S. , Bank Joseph A. , Theobald Michael , Dror Ron O. , Ierardi Douglas J. , Larson Richard H. , Schafer U. Ben , Towles Brian , Young Cliff , Shaw David E. 
Published: July 2013

Exploiting parallelism to accelerate a computation typically involves dividing it into many small tasks that can be assigned to different processing elements. An efficient execution schedule for these tasks can be difficult or impossible to determine in advance, however, if there is uncertainty as to when each task's input data will be available. Ideally, each task would run in direct response to the arrival of its input data, thus allowing the computation to proceed in a fine-grained event-driven manner. Realizing this ideal is difficult in practice, and typically requires sacrificing flexibility for performance.
In Anton 2, a massively parallel special-purpose supercomputer for molecular dynamics simulations, we addressed this challenge by including a hardware block, called the dispatch unit, that provides flexible and efficient support for fine-grained event-driven computation. Its novel features include a many-to-many mapping from input data to a set of synchronization counters, and the ability to prioritize tasks based on their type. To solve the additional problem of using a fixed set of synchronization counters to track input data for a potentially large number of tasks, we created a software library that allows programmers to treat Anton 2 as an idealized machine with infinitely many synchronization counters. The dispatch unit, together with this library, made it possible to simplify our molecular dynamics software by expressing it as a collection of independent tasks, and the resulting fine-grained execution schedule improved overall performance by up to 16% relative to a coarse-grained schedule for precisely the same computation.
Compiler directed write-mode selection for high performance low power volatile PCM
Authors: Li Qingan , Jiang Lei , Zhang Youtao , He Yanxiang , Xue Chun Jason 
Published: July 2013

Micro-Controller Units (MCUs) are widely adopted ubiquitous computing devices. Due to tight cost and energy constraints, MCUs often integrate very limited internal RAM memory on top of Flash storage, which exposes Flash to heavy write traffic and results in short system lifetime. Architecting emerging Phase Change Memory (PCM) is a promising approach for MCUs due to its fast read speed and long write endurance.
However, PCM, especially multi-level cell (MLC) PCM, has long write latency and requires large write energy, which diminishes the benefits of its replacement of traditional Flash. By studying MLC PCM write operations, we observe that writing MLC PCM can take advantages of two write modes --- fast write leaves cells in volatile state, and slow write leaves cells in non-volatile state. In this paper, we propose a compiler directed dual-write (CDDW) scheme that selects the best write mode for each write operation to maximize the overall performance and energy efficiency. Our experimental results show that CDDW reduces dynamic energy by 32.4%(33.8%) and improves performance by 6.3%(35.9%) compared with an all fast(slow) write approach.
Program performance spectrum
Authors: Chattopadhyay Sudipta , Chong Lee Kee , Roychoudhury Abhik 
Published: July 2013

Real-time and embedded applications often need to satisfy several non-functional properties such as timing. Consequently, performance validation is a crucial stage before the deployment of real-time and embedded software. Cache memories are often used to bridge the performance gap between a processor and memory subsystems. As a result, the analysis of caches plays a key role in the performance validation of real-time, embedded software. In this paper, we propose a novel approach to compute the cache performance signature of an entire program. Our technique is based on exploring the input domain through different path programs. Two paths belong to the same path program if they follow the same set of control flow edges but may vary in the iterations of loops encountered. Our experiments with several subject programs show that the different paths grouped into a path program have very similar and often exactly same cache performance.
Our path program exploration can be viewed as partitioning the input domain of the program. Each partition is associated with its cache performance and a symbolic formula capturing the set of program inputs which constitutes the partition. We show that such a partitioning technique has wide spread usages in performance prediction, testing, debugging and design space exploration.
Portable mapping of openMP to multicore embedded systems using MCA APIs
Authors: Wang Cheng , Chandrasekaran Sunita , Sun Peng , Chapman Barbara , Holt Jim 
Published: July 2013

Multicore embedded systems are being widely used in telecommunication systems, robotics, medical applications and more.While they offer a high-performance with low-power solution, programming in an efficient way is still a challenge. In order to exploit the capabilities that the hardware offers, software developers are expected to handle many of the low-level details of programming including utilizing DMA, ensuring cache coherency, and inserting synchronization primitives explicitly. The state-of-the-art involves solutions where the software toolchain is too vendor-specific thus tying the software to a particular hardware leaving no room-for portability.
In this paper we present a runtime system to explore mapping a high-level programming model, OpenMP, on to multicore embedded systems. A key feature of our scheme is that unlike the existing approaches that largely rely on POSIX threads, our approach leverages the Multicore Association (MCA) APIs as an OpenMP translation layer. The MCA APIs is a set of low-level APIs handling resource management, inter-process communications and task scheduling for multicore embedded systems. By deploying the MCA APIs, our runtime is able to effectively capture the characteristics of multicore embedded systems compared with the POSIX threads. Furthermore, the MCA layer enables our runtime implementation to be portable across various architectures. Thus programmers only need to maintain a single OpenMP code base which is compatible by various compilers, while on the other hand, the code is portable across different possible types of platforms. We have evaluated our runtime system using several embedded benchmarks. The experiments demonstrate promising and competitive performance compared to the native approach for the platform.
Look up!
Authors: Larus James R. 
Published: July 2013

The "Cloud" is a wonderfully expansive phrase used to denote computation and data storage centralized in a large datacenter and elastically accessed across a network. The concept is not new; web sites and business servers have run in datacenters for a long time. These, however, were specialized applications, outside of the mainstream of desktop programs. The past few years has seen enormous change as the mainstream shifts from a single computer to mobile devices and clusters of computers. Three factors are driving this change. 1) Mobile computing, where apps run on a size- and power-constrained device and would be far less interesting without backend systems to augment computation and storage capacity. 2) Big data, which uses clusters of computers to extract valuable information from vast amounts of unstructured data. 3) Inexpensive, elastic computing, pioneered by Amazon Web Services, which enables everyone to rapidly obtain and use many servers.
As a researcher from the language and compiler community, I firmly believe this sea change is at heart a programming problem. Cloud computing is far different from the environment in which most of today's languages and tools were developed, and few programmers have mastered its complexity. New challenges include pervasive parallelism, partial failure, high and variable communication latency, and replication for reliability and throughput.
Rely-guarantee references for refinement types over aliased mutable data
Authors: Gordon Colin S. , Ernst Michael D. , Grossman Dan 
Published: July 2013

Reasoning about side effects and aliasing is the heart of verifying imperative programs. Unrestricted side effects through one reference can invalidate assumptions about an alias. We present a new type system approach to reasoning about safe assumptions in the presence of aliasing and side effects, unifying ideas from reference immutability type systems and rely-guarantee program logics. Our approach, rely-guarantee references, treats multiple references to shared objects similarly to multiple threads in rely-guarantee program logics. We propose statically associating rely and guarantee conditions with individual references to shared objects. Multiple aliases to a given object may coexist only if the guarantee condition of each alias implies the rely condition for all other aliases. We demonstrate that existing reference immutability type systems are special cases of rely-guarantee references.
In addition to allowing precise control over state modification, rely-guarantee references allow types to depend on mutable data while still permitting flexible aliasing. Dependent types whose denotation is stable over the actions of the rely and guarantee conditions for a reference and its data will not be invalidated by any action through any alias. We demonstrate this with refinement (subset) types that may depend on mutable data. As a special case, we derive the first reference immutability type system with dependent types over immutable data.
We show soundness for our approach and describe experience using rely-guarantee references in a dependently-typed monadic DSL in Coq.
CLAP
Authors: Huang Jeff , Zhang Charles , Dolby Julian 
Published: July 2013

We present CLAP, a new technique to reproduce concurrency bugs. CLAP has two key steps. First, it logs thread local execution paths at runtime. Second, offline, it computes memory dependencies that accord with the logged execution and are able to reproduce the observed bug. The second step works by combining constraints from the thread paths and constraints based on a memory model, and computing an execution with a constraint solver.
CLAP has four major advantages. First, logging purely local execution of each thread is substantially cheaper than logging memory interactions, which enables CLAP to be efficient compared to previous approaches. Second, our logging does not require any synchronization and hence with no added memory barriers or fences; this minimizes perturbation and missed bugs due to extra synchronizations foreclosing certain racy behaviors. Third, since it uses no synchronization, we extend CLAP to work on a range of relaxed memory models, such as TSO and PSO, in addition to sequential consistency. Fourth, CLAP can compute a much simpler execution than the original one, that reveals the bug with minimal thread context switches. To mitigate the scalability issues, we also present an approach to parallelize constraint solving, which theoretically scales our technique to programs with arbitrary execution length.
Experimental results on a variety of multithreaded benchmarks and real world concurrent applications validate these advantages by showing that our technique is effective in reproducing concurrency bugs even under relaxed memory models; furthermore, it is significantly more efficient than a state-of-the-art technique that records shared memory dependencies, reducing execution time overhead by 45% and log size by 88% on average.
It's alive! continuous feedback in UI programming
Authors: Burckhardt Sebastian , Fahndrich Manuel , de Halleux Peli , McDirmid Sean , Moskal Michal , Tillmann Nikolai , Kato Jun 
Published: July 2013

Live programming allows programmers to edit the code of a running program and immediately see the effect of the code changes. This tightening of the traditional edit-compile-run cycle reduces the cognitive gap between program code and execution, improving the learning experience of beginning programmers while boosting the productivity of seasoned ones. Unfortunately, live programming is difficult to realize in practice as imperative languages lack well-defined abstraction boundaries that make live programming responsive or its feedback comprehensible.
This paper enables live programming for user interface programming by cleanly separating the rendering and non-rendering aspects of a UI program, allowing the display to be refreshed on a code change without restarting the program. A type and effect system formalizes this separation and provides an evaluation model that incorporates the code update step. By putting live programming on a more formal footing, we hope to enable critical and technical discussion of live programming systems.
Reasoning about nondeterminism in programs
Authors: Cook Byron , Koskinen Eric 
Published: July 2013

Branching-time temporal logics (e.g. CTL, CTL*, modal mu-calculus) allow us to ask sophisticated questions about the nondeterminism that appears in systems. Applications of this type of reasoning include planning, games, security analysis, disproving, precondition synthesis, environment synthesis, etc. Unfortunately, existing automatic branching-time verification tools have limitations that have traditionally restricted their applicability (e.g. push-down systems only, universal path quantifiers only, etc).
In this paper we introduce an automation strategy that lifts many of these previous restrictions. Our method works reliably for properties with non-trivial mixtures of universal and existential modal operators. Furthermore, our approach is designed to support (possibly infinite-state) programs.
The basis of our approach is the observation that existential reasoning can be reduced to universal reasoning if the system's state-space is appropriately restricted. This restriction on the state-space must meet a constraint derived from recent work on proving non-termination. The observation leads to a new route for implementation based on existing tools. To demonstrate the practical viability of our approach, we report on the results applying our preliminary implementation to a set of benchmarks drawn from the Windows operating system, the PostgreSQL database server, SoftUpdates patching system, as well as other hand-crafted examples.
Evaluation of the Effects of Different Surface Configurations on Stability of Miniscrews
Authors: Topcuoglu Tolga , Bicakci A. Altuğ , Avunduk M. Cihat , Sahin Inan Z. Deniz 
Published: July 2013

Introduction. The aim of this study was to analyze the effects of screw design and force application on the stability of miniscrews, using RTT, SEM, and histomorphometric analyses. Materials and Methods. Eighty cylindrical, self‐drilling, and Ti6Al4V alloy miniscrews (1,6 × 6 mm) were used. Four mini‐screws were inserted in fibulas of each rabbit, and 115 G of force was immediately applied. Four miniscrews were inserted in the other fibula, on which no force was applied. Eight weeks after insertion, osseointegration between miniscrew and the surrounding bone was evaluated by the histomorphometric analyses, SEM, and RTT. Kruskal‐Wallis and the paired t‐tests were used for statistical analysis. Results. Values obtained from Group I were significantly higher than those of the other loaded groups (P < .05). There were no differences in RTT scores among Groups II, III, and IV. Similar findings were also observed for unloaded mini‐screws. There was no significant difference between Groups I and IC, while the differences between loaded and unloaded controls for each miniscrew were statistically significant. Conclusions. Immediate loading of miniscrews does not impair screw stability. Also, the diameter of miniscrew and more frequent thread pitches have a positive effect on stability; however, length of miniscrews does not have a significant effect on the stability.
Blood Pressure and Cholesterol Control in Hypertensive Hypercholesterolemic Patients
Authors: Egan Brent M. , Li Jiexiang , Qanungo Suparna , Wolfman Tamara E. 
Published: July 2013

Background—
Hypertension doubles coronary heart disease (CHD) risk. Treating hypertension only reduces CHD risk ≈25%. Treating hypercholesterolemia in hypertensive patients reduces residual CHD risk >35%.

Methods and Results—
To assess progress in concurrent hypertension and hypercholesterolemia control, National Health and Nutrition Examination Surveys 1988 to 1994, 1999 to 2004, and 2005 to 2010 were analyzed. Hypertension was defined by blood pressure ≥140/≥90 mm Hg, current medication treatment, and 2-told hypertension status; blood pressure <140/<90 defined control. Hypercholesterolemia was defined by ATP III criteria based on 10-year CHD risk, low-density lipoprotein cholesterol (LDL-C), and non–high-density lipoprotein cholesterol; values below diagnostic thresholds defined control. Across surveys, 60.7% to 64.3% of hypertensives were hypercholesterolemic. From 1988 to 1994 to 2005 to 2010, control of LDL-C rose (9.2% [95% confidence interval (CI), 6.6%–11.9%] to 45.4% [95% CI, 42.6%–48.3%]), concomitant hypertension and LDL-C (5.0% [95% CI, 3.3%–6.7%] to 30.7% [95% CI, 27.9%–33.4%]), and combined hypertension, LDL-C, and non–high-density lipoprotein cholesterol (1.8% [95% CI, 0.4%–3.2%] to 26.9% [95% CI, 24.4%–29.5%]). By multivariable logistic regression, factors associated with concomitant hypertension, LDL-C, and non–high-density lipoprotein cholesterol control (odds ratio [95% CI]) were statin (10.7 [8.1–14.3]) and antihypertensive (3.32 [2.45–4.50]) medications, age (0.77 [0.69–0.88]/10-year increase), ≥2 healthcare visits/yr (1.90 [1.26-2.87]), black race (0.59 [0.44–0.80]), Hispanic ethnicity (0.62 [0.43–0.90]), cardiovascular disease (0.44 [0.34–0.56]), and diabetes mellitus (0.54 [0.42–0.70]).

Conclusions—
Despite progress, opportunities for improving concomitant hypertension and hypercholesterolemia control persist. Prescribing antihypertensive and antihyperlipidemic medications to achieve treatment goals, especially for older, minority, diabetic, and cardiovascular disease patients, and accessing healthcare at least biannually could improve concurrent risk factor control and CHD prevention.
Dynamics and Geometry of Extratropical Cyclones in the Upper Troposphere by a Neighbor Enclosed Area Tracking Algorithm
Authors: Inatsu Masaru , Amada Shotaro 
Published: July 2013

AbstractThis study shows that the morphological characteristics of upper-tropospheric extratropical eddies are closely related to the background flow in the Northern Hemisphere winter. Enclosed surfaces of 300-hPa relative vorticity are identified by using the neighbor enclosed area tracking algorithm, and the periphery of these surfaces are approximated by ellipses. Eddies are classified into five categories according to the approximate ellipse. Eddies having an oblateness of less than 0.6 are classified as near circle, or are otherwise classified as northeast–southwest (NE–SW), northwest–southeast (NW–SE), north–south, or west–east, according to the direction of the major axis. In the wintertime climatology, NE–SW-oriented cyclones are collocated with the jet stream, while NW–SE-oriented cyclones mostly reside north of the jet. In interannual variability, moreover, the frequency of NE–SW cyclones is slightly correlated with the Arctic Oscillation (AO) index, while the frequency of NW–SE cyclones is highly anticorrelated with the AO index. This is consistent with positive feedback between horizontally slanted eddies and background flow, as has been shown in many previous studies.
Changes in Twentieth-Century Extreme Temperature and Precipitation over the Western United States Based on Observations and Regional Climate Model Simulations*
Authors: Dulière Valérie , Zhang Yongxin , Salathé Eric P. 
Published: July 2013

Abstract
Trends in extreme temperature and precipitation in two regional climate model simulations forced by two global climate models are compared with observed trends over the western United States. The observed temperature extremes show substantial and statistically significant trends across the western United States during the late twentieth century, with consistent results among individual stations. The two regional climate models simulate temporal trends that are consistent with the observed trends and reflect the anthropogenic warming signal. In contrast, no such clear trends or correspondence between the observations and simulations is found for extreme precipitation, likely resulting from the dominance of the natural variability over systematic climate change during the period. However, further analysis of the variability of precipitation extremes shows strong correspondence between the observed precipitation indices and increasing oceanic Niño index (ONI), with regionally coherent patterns found for the U.S. Northwest and Southwest. Both regional climate simulations reproduce the observed relationship with ONI, indicating that the models can represent the large-scale climatic links with extreme precipitation. The regional climate model simulations use the Weather Research and Forecasting (WRF) Model and Hadley Centre Regional Model (HadRM) forced by the ECHAM5 and the Hadley Centre Climate Model (HadCM) global models for the 1970–2007 time period. Comparisons are made to station observations from the Historical Climatology Network (HCN) locations over the western United States. This study focused on temperature and precipitation extreme indices recommended by the Expert Team on Climate Change Detection Monitoring and Indices (ETCCDMI).
Extreme Flood Response: The June 2008 Flooding in Iowa
Authors: Smith James A. , Baeck Mary Lynn , Villarini Gabriele , Wright Daniel B. , Krajewski Witold 
Published: July 2013

Abstract
The authors examine the hydroclimatology, hydrometeorology, and hydrology of extreme floods through analyses that center on the June 2008 flooding in Iowa. The most striking feature of the June 2008 flooding was the flood peak of the Cedar River at Cedar Rapids (3964 m3 s−1), which was almost twice the previous maximum from a record of 110 years. The spatial extent of extreme flooding was exceptional, with more U.S. Geological Survey stream gauging stations reporting record flood peaks than in any other year. The 2008 flooding was produced by a sequence of organized thunderstorm systems over a period of two weeks. The authors examine clustering and seasonality of flooding in the Iowa study region and link these properties to features of the June 2008 flood event. They examine the environment of heavy rainfall in Iowa during June 2008 through analyses of composite rainfall fields (15-min time interval and 1-km spatial resolution) developed with the Hydro-NEXRAD system and simulations using the Weather Research and Forecasting Model (WRF). Water balance analyses of extreme flood response, based on rainfall and discharge observations from basins with extreme flooding, suggest that antecedent soil moisture plays a diminishing role in flood response as the return interval increases. Rainfall structure and evolution play a critical and poorly understood role in determining the scaling of flood response. As in other extreme flood studies, analyses of the Iowa flood data suggest that measurement errors can be significant for record discharge estimates.