bluuebunny/crossref_metadata_2025 huggingface dataset:
Interprocedural slicing of multithreaded programs with applications to Java
Authors: Nanda Mangala Gowri , Ramesh S.
Published: January 2007

Slicing is a well-known program reduction technique where for a given program
P
and a variable of interest
v
at some statement
P
in the program, a program slice contains those set of statements belonging to
P
that affect
v
. This article presents two algorithms for interprocedural slicing of concurrent programs--a
context-insensitive
algorithm and a
context-sensitive
algorithm. The context-insensitive algorithm is efficient and correct (it includes every statement that may affect the slicing criterion) but is imprecise since it may include certain extra statements that are unnecessary. Precise slicing has been shown to be undecidable for concurrent programs. However, the context-sensitive algorithm computes correct and reasonably precise slices, but has a worst-case exponential-time complexity. Our context-sensitive algorithm computes a closure of dependencies while ensuring that statements sliced in each thread belong to a
realizable
path in that thread.A realizable path in a thread with procedure calls is one that reflects the fact that when a procedure finishes, execution returns to the site of the most recently executed call in that thread. One of the novelties of this article is a practical solution to determine whether a given set of statements in a thread may belong to a realizable path. This solution is precise even in the presence of recursion and long call chains in the flow graph.The slicing algorithms are applicable to concurrent programs with shared memory, interleaving semantics, explicit wait/notify synchronization and monitors. We first give a solution for a simple model of concurrency and later show how to extend the solution to the Java concurrency model. We have implemented the algorithms for Java bytecode and give experimental results.
On minimizing materializations of array-valued temporaries
Authors: Rosenkrantz Daniel J. , Mullin Lenore R. , Hunt III Harry B.
Published: January 2007

We consider the analysis and optimization of code utilizing operations and functions operating on entire arrays. Models are developed for studying the minimization of the number of materializations of array-valued temporaries in basic blocks, each consisting of a sequence of assignment statements involving array-valued variables. We derive lower bounds on the number of materializations required, and develop several algorithms minimizing the number of materializations, subject to a simple constraint on allowable statement rearrangement. In contrast, we also show that when statement rearrangement is unconstrained, minimizing the number of materializations becomes NP-complete, even for very simple basic blocks.
minimUML
Authors: Turner Scott A. , Pérez-Quiñones Manuel A. , Edwards Stephen H.
Published: January 2007

In introductory computer science courses, the Unified Modeling Language (UML) is commonly used to teach basic object-oriented design. However, there appears to be a lack of suitable software to support this task. Many of the available programs that support UML focus on developing code and not on enhancing learning. Programs designed for educational use sometimes have poor interfaces or are missing common and important features such as multiple selection and undo/redo. Hence the need for software that is tailored to an instructional environment and that has all the useful and needed functionality for that specific task. This is the purpose of minimUML. It provides a minimum amount of UML, just what is commonly used in beginning programming classes, and a simple, usable interface. In particular, minimUML is designed to support abstract design while supplying features for exploratory learning and error avoidance. It supports functionality that includes multiple selection, undo/redo, flexible printing, cut and paste, and drag and drop. In addition, it allows for the annotation of diagrams, through text or free-form drawings, so students can receive feedback on their work. minimUML was developed with the goals of supporting ease of use, of supporting novice students, and of requiring no prior training for its use. This article presents the rationale behind the minimUML design, a description of the tool, and the results of usability evaluations and student feedback on the use of the tool.
A framework for CS1 closed laboratories
Authors: Soh Leen-Kiat , Samal Ashok , Nugent Gwen
Published: January 2007

Closed laboratories are becoming an increasingly popular approach to teaching introductory computer science courses, as they facilitate structured problem-solving and cooperation. However, most closed laboratories have been designed and implemented without embedded instructional research components for constant evaluation of the laboratories' effectiveness. As a result, it is not convenient to maintain and improve the laboratories over time so that they adapt to changing CS topics, curricula, and student needs. This article reports on an integrated framework for designing, implementing, and maintaining laboratories with embedded instructional research design. Although the activities reported here are part of our department-wide effort to cover CS0, CS1, and CS2, we focus here on the design and implementation of the labs for CS1.
Computer graphics instruction in VizClass
Authors: Grimes Douglas , Warschauer Mark , Hutchinson Tara , Kuester Falko
Published: January 2007

VizClass
is a university classroom environment designed to offer students in computer graphics and engineering courses up-to-date visualization technologies. Three digital whiteboards and a three-dimensional stereoscopic display provide complementary display surfaces. Input devices include touchscreens on the digital whiteboards, remote keyboards, data gloves, and hand-position sensors.We use observations, interviews, and surveys to examine the pedagogical impacts of VizClass for teaching and learning computer graphics and virtual reality. Preliminary findings include positive student and teacher attitudes and greater learner engagement in after-class collaborations.
Block algorithms for reordering standard and generalized Schur forms
Authors: Kressner Daniel
Published: January 2007

Block algorithms for reordering a selected set of eigenvalues in a standard or generalized Schur form are proposed. Efficiency is achieved by delaying orthogonal transformations and (optionally) making use of level 3 BLAS operations. Numerical experiments demonstrate that existing algorithms, as currently implemented in LAPACK, are outperformed by up to a factor of four.
The design and implementation of the MRRR algorithm
Authors: Dhillon Inderjit S. , Parlett Beresford N. , Vömel Christof
Published: January 2007

In the 1990's, Dhillon and Parlett devised the algorithm of multiple relatively robust representations (MRRR) for computing numerically orthogonal eigenvectors of a symmetric tridiagonal matrix
T
with O(n
2
) cost. While previous publications related to MRRR focused on theoretical aspects of the algorithm, a documentation of software issues has been missing. In this article, we discuss the design and implementation of the new MRRR version STEGR that will be included in the next LAPACK release. By giving an algorithmic description of MRRR and identifying governing parameters, we hope to make STEGR more easily accessible and suitable for future performance tuning. Furthermore, this should help users understand design choices and tradeoffs when using the code.
Algorithm 857
Authors: Su Hai-Jun , McCarthy J. Michael , Sosonkina Masha , Watson Layne T.
Published: January 2007

Globally convergent, probability-one homotopy methods have proven to be very effective for finding all the isolated solutions to polynomial systems of equations. After many years of development, homotopy path trackers based on probability-one homotopy methods are reliable and fast. Now, theoretical advances reducing the number of homotopy paths that must be tracked and handling singular solutions have made probability-one homotopy methods even more practical. POLSYS_GLP consists of Fortran 95 modules for finding all isolated solutions of a complex coefficient polynomial system of equations. The package is intended to be used on a distributed memory multiprocessor in conjunction with HOMPACK90 (Algorithm 777), and makes extensive use of Fortran 95-derived data types and MPI to support a general linear product (GLP) polynomial system structure. GLP structure is intermediate between the partitioned linear product structure used by POLSYS_PLP (Algorithm 801) and the BKK-based structure used by PHCPACK. The code requires a GLP structure as input, and although finding the optimal GLP structure is a difficult combinatorial problem, generally physical or engineering intuition about a problem yields a very good GLP structure. POLSYS_GLP employs a sophisticated power series end game for handling singular solutions, and provides support for problem definition both at a high level and via hand-crafted code. Different GLP structures and their corresponding Bezout numbers can be systematically explored before committing to root finding.
Improved efficiency for revocation schemes via Newton interpolation
Authors: Kogan Noam , Tassa Tamir
Published: January 2007

We present a novel way to implement the secret-sharing-based family of revocation schemes of Naor and Pinkas [2003]. The basic scheme of [Naor and Pinkas 2000] uses Shamir's polynomial secret-sharing to revoke up to
r
users, where
r
is the degree of the secret-sharing polynomial, and it is information theoretically secure against coalitions of up to
r
collaborators. The nonrevoked users use Lagrange interpolation in order to compute the new key. Our basic scheme uses a novel modification of Shamir's polynomial secret-sharing: The secret equals the leading coefficient of the polynomial (as opposed to the free coefficient as in the original scheme) and the polynomial is reconstructed by Newton interpolation (rather than Lagrange interpolation). Comparing our scheme to one variant of the Naor--Pinkas scheme, we offer revocation messages that are shorter by a factor of almost 2, while the computation cost at the user end is smaller by a constant factor of approximately 13/2. Comparing to a second variant of the Naor--Pinkas scheme, our scheme offers a reduction of
O
(
r
) in the computation cost at the user end, without affecting any of the other performance parameters. We then extend our basic scheme to perform multiround revocation for stateless and stateful receivers, along the lines offered by Naor and Pinkas [2000] and Kogan et al. [2003]. We show that using Newton rather than Lagrange interpolants enables a significantly more efficient transmission of the new revocation message and shorter response time for each round. Pay TV systems that implement broadcast encryption techniques can benefit significantly from the improved efficiency offered by our revocation schemes.
Minos
Authors: Crandall Jedidiah R. , Wu S. Felix , Chong Frederic T.
Published: January 2007

We present Minos, a microarchitecture that implements Biba's low water-mark integrity policy on individual words of data. Minos stops attacks that corrupt control data to hijack program control flow, but is orthogonal to the memory model. Control data is any data that is loaded into the program counter on control-flow transfer, or any data used to calculate such data. The key is that Minos tracks the integrity of all data, but protects control flow by checking this integrity when a program uses the data for control transfer. Existing policies, in contrast, need to differentiate between control and noncontrol data
a priori
, a task made impossible by coercions between pointers and other data types, such as integers in the C language. Our implementation of Minos for Red Hat Linux 6.2 on a Pentium-based emulator is a stable, usable Linux system on the network on which we are currently running a web server (http://minos.cs.ucdavis.edu). Our emulated Minos systems running Linux and Windows have stopped ten actual attacks. Extensive full-system testing and real-world attacks have given us a unique perspective on the policy tradeoffs that must be made in any system, such as Minos; this paper details and discusses these. We also present a microarchitectural implementation of Minos that achieves negligible impact on cycle time with a small investment in die area, as well as and minor changes to the Linux kernel to handle the tag bits and perform virtual memory swapping.
Evaluating trace cache energy efficiency
Authors: Co Michele , Weikle Dee A. B. , Skadron Kevin
Published: January 2007

Future fetch engines need to be energy efficient. Much research has focused on improving fetch bandwidth. In particular, previous research shows that storing concatenated basic blocks to form instruction traces can significantly improve fetch performance. This work evaluates whether this concatenating of basic blocks translates to significantenergy-efficiencygains. We compare processor performance and energy efficiency in trace caches compared to instruction caches. We find that, although trace caches modestly outperform instruction cache only alternatives, it is branch-prediction accuracy that really determines performance and energy efficiency. When access delay and area restrictions are considered, our results show that sequential trace caches achieve very similar performance and energy efficiency results compared to instruction cache-based fetch engines and show that the trace cache's failure to significantly outperform the instruction cache-based fetch organizations stems from the poorer implicit branch prediction from the next-trace predictor at smaller areas. Because access delay limits the theoretical performance of the evaluated fetch engines, we also propose a novel ahead-pipelined next-trace predictor. Our results show that an STC fetch organization with a three-stage, ahead-pipelined next-trace predictor can achieve 5--17% IPC and 29% ED2improvements over conventional, unpipelined organizations.
Chatting with teenagers
Authors: Grinter Rebecca E. , Palen Leysia , Eldridge Margery
Published: January 2007

In the last few years, teenagers have been on the forefront of adopting short message service (SMS), a mobile phone-based text messaging system, and instant messaging (IM), a computer-based text chat system. However, while teenage adoption of SMS had led to a series of studies examining the reasons for its popularity, IM use in the teenage population remains understudied. This omission becomes significant given the increasing interest in domestic computing among human-computer interaction (HCI) and computer-supported cooperative work (CSCW) researchers. Further, because of the dearth of empirical work on teenage use of IM, we find that IM and SMS are sometimes incorrectly assumed to share the same features of use. To address these concerns, we revisit our own studies of SMS and IM use and reexamine them in tandem with other published studies on teenage chat. We consider similarities and differences in styles of SMS and IM use and how chat technologies enable the pursuit of teenage independence. We examine how differences are born out of technological differences and financial cost structures. We discuss how SMS and IM are used in concert to provide increased awareness and to coordinate inter-household communications, and how privacy is regulated within the individual household as a means of maintaining these communications.
Navigating on handheld displays
Authors: Mehra Sumit , Werkhoven Peter , Worring Marcel
Published: January 2007

Handheld displays leave little space for the visualization and navigation of spatial layouts representing rich information spaces. The most common navigation method for handheld displays is
static peephole navigation
: The peephole is static and we move the spatial layout behind it (scrolling). A more natural method is
dynamic
peephole navigation: here, the spatial layout is static and we move the peephole across it. In the experiment reported here, we compared dynamic and static peephole navigation in otherwise similar conditions. Subjects viewed a spatial layout containing two lines on a static display screen. Only a part of the screen---the peephole---was visible. Subjects had to discriminate line length by either moving a dynamic peephole across a static layout of the lines or by moving a dynamic layout behind a static peephole. In both conditions, they used mouse-cursor control to move either the peephole or the lines.Results show significant differences in discrimination performance between conditions when lines are larger than the size of the peephole. Discrimination thresholds for static peephole navigation were 50--75% higher than for dynamic peephole navigation. Furthermore, static peephole navigation took 24% more time than dynamic peephole navigation.
The patent holder's dilemma
Authors: Abril Patricia S. , Plant Robert
Published: January 2007

The current patent process in many ways works against IT innovation by making the road to realization too dispiriting for today's independent inventors.
Semantic matching across heterogeneous data sources
Authors: Zhao Huimin
Published: January 2007

Discovering semantic correspondences is the key to semantic integration of data sources and ultimately to data integration across disparate databases.
Agile…and offshore
Authors: Armour Phillip G.
Published: January 2007

An interview with a new paradigm.
Recovering device drivers
Authors: Swift Michael M. , Annamalai Muthukaruppan , Bershad Brian N. , Levy Henry M.
Published: January 2007

This article presents a new mechanism that enables applications to run correctly when device drivers fail. Because device drivers are the principal failing component in most systems, reducing driver-induced failures greatly improves overall reliability. Earlier work has shown that an operating system can survive driver failures [Swift et al. 2005], but the applications that depend on them cannot. Thus, while operating system reliability was greatly improved, application reliability generally was not.To remedy this situation, we introduce a new operating system mechanism called ashadow driver. A shadow driver monitors device drivers and transparently recovers from driver failures. Moreover, it assumes the role of the failed driver during recovery. In this way, applications using the failed driver, as well as the kernel itself, continue to function as expected.We implemented shadow drivers for the Linux operating system and tested them on over a dozen device drivers. Our results show that applications and the OS can indeed survive the failure of a variety of device drivers. Moreover, shadow drivers impose minimal performance overhead. Lastly, they can be introduced with only modest changes to the OS kernel and with no changes at all to existing device drivers.
Using model checking to find serious file system errors
Authors: Yang Junfeng , Twohey Paul , Engler Dawson , Musuvathi Madanlal
Published: January 2007

This article shows how to use model checking to find serious errors in file systems. Model checking is a formal verification technique tuned for finding corner-case errors by comprehensively exploring the state spaces defined by a system. File systems have two dynamics that make them attractive for such an approach. First, their errors are some of the most serious, since they can destroy persistent data and lead to unrecoverable corruption. Second, traditional testing needs an impractical, exponential number of test cases to check that the system will recover if it crashes at any point during execution. Model checking employs a variety of state-reducing techniques that allow it to explore such vast state spaces efficiently.We built a system, FiSC, for model checking file systems. We applied it to four widely-used, heavily-tested file systems: ext3, JFS, ReiserFS and XFS. We found serious bugs in all of them, 33 in total. Most have led to patches within a day of diagnosis. For each file system, FiSC found demonstrable events leading to the unrecoverable destruction of metadata and entire directories, including the file system root directory “/”.
News 2.0
Authors: Stanik John
Published: January 2007

Fox and the Weasel
Unlocking Concurrency
Authors: Adl-Tabatabai Ali-Reza , Kozyrakis Christos , Saha Bratin
Published: January 2007

Multicore architectures are an inflection point in mainstream software development because they force developers to write parallel programs. In a previous article in Queue, Herb Sutter and James Larus pointed out, “The concurrency revolution is primarily a software revolution. The difficult problem is not building multicore hardware, but programming it in a way that lets mainstream applications benefit from the continued exponential growth in CPU performance.” In this new multicore world, developers must write explicitly parallel applications that can take advantage of the increasing number of cores that each successive multicore generation will provide.
The Virtualization Reality
Authors: Crosby Simon , Brown David
Published: January 2007

A number of important challenges are associated with the deployment and configuration of contemporary computing infrastructure. Given the variety of operating systems and their many versions—including the often-specific configurations required to accommodate the wide range of popular applications—it has become quite a conundrum to establish and manage such systems.
Review of "Hacking Exposed: Web Applications, 2nd edition by Joel Scambray, Mike Shema, and Caleb Sima," McGraw-Hill Osborne Media, 2006, $49.99, ISBN: 0072262990.
Authors: State Radu
Published: January 2007

Review of "Hacking Exposed: Web Applications, 2nd edition by Joel Scambray, Mike Shema, and Caleb Sima," McGraw-Hill Osborne Media, 2006, $49.99, ISBN: 0072262990.
Calendar
Authors: O'Hanlon Charlene
Published: January 2007

LISA (Large Installation System Administration) Conference
A state event detection algorithm for numerically simulating hybrid systems with model singularities
Authors: Esposito Joel M. , Kumar Vijay
Published: January 2007

This article describes an algorithm for detecting the occurrence of events, which signify discontinuities in the first derivative of the state variables, while simulating a set of nonsmooth differential equations. Such combined-discrete continuous systems arise in many contexts and are often referred to as hybrid systems, switched systems, or nonsmooth systems. In all cases, the state events are triggered at simulated times which generate states corresponding to the zeros of some algebraic “event” function. It has been noted that all existing simulators are prone to failure when these events occur in the neighborhood of model singularities---regions of the state space where the right-hand side of the differential equation is undefined. Such model singularities are often the impetus for using nonsmooth models in the first place. This failure occurs because existing algorithms blindly attempt to interpolate across singular regions, checking for possible events after the fact. The event detection algorithm described here overcomes this limitation using an approach inspired by feedback control theory. A carefully constructed extrapolation polynomial is used to select the integration step size by checking for potential future events, avoiding the need to evaluate the differential equation in potentially singular regions. It is shown that this alternate approach gives added functionality with little impact on the simulation efficiency.
An efficient single-pass trace compression technique utilizing instruction streams
Authors: Milenković Aleksandar , Milenković Milena
Published: January 2007

Trace-driven simulations have been widely used in computer architecture for quantitative evaluations of new ideas and design prototypes. Efficient trace compression and fast decompression are crucial for contemporary workloads, as representative benchmarks grow in size and number. This article presents Stream-Based Compression (SBC), a novel technique for single-pass compression of address traces. The SBC technique compresses both instruction and data addresses by associating them with a particular instruction stream, that is, a block of consecutively executing instructions. The compressed instruction trace is a trace of instruction stream identifiers. The compressed data address trace encompasses the data address stride and the number of repetitions for each memory-referencing instruction in a stream, ordered by the corresponding stream appearances in the trace. SBC reduces the size of SPEC CPU2000 Dinero instruction and data address traces from 18 to 309 times, outperforming the best trace compression techniques presented in the open literature. SBC can be successfully combined with general-purpose compression techniques. The combined SBC-gzip compression ratio is from 80 to 35,595, and the SBC-bzip2 compression ratio is from 75 to 191,257. Moreover, SBC outperforms other trace compression techniques when both decompression time and compression time are considered. This article also shows how the SBC algorithm can be modified for hardware implementation with very modest resources and only a minor loss in compression ratio.
Conversion of high-period random numbers to floating point
Authors: Doornik Jurgen A.
Published: January 2007

Conversion of unsigned 32-bit random integers to double precision floating point is discussed. It is shown that the standard practice can be unnecessarily slow and inflexible. It is argued that simulation experiments could benefit from making better use of the available precision.
Stable, circulation-preserving, simplicial fluids
Authors: Elcott Sharif , Tong Yiying , Kanso Eva , Schröder Peter , Desbrun Mathieu
Published: January 2007

Visual quality, low computational cost, and numerical stability are foremost goals in computer animation. An important ingredient in achieving these goals is the conservation of fundamental motion invariants. For example, rigid and deformable body simulation benefits greatly from the conservation of linear and angular momenta. In the case of fluids, however, none of the current techniques focuses on conserving invariants, and consequently, often introduce a visually disturbing numerical diffusion of
vorticity
. Just as important visually is the resolution of complex simulation domains. Doing so with regular (even if adaptive) grid techniques can be computationally delicate. In this article, we propose a novel technique for the simulation of fluid flows. It is designed to respect the defining differential properties, that is, the
conservation of circulation
along arbitrary loops as they are transported by the flow. Consequently, our method offers several new and desirable properties: Arbitrary simplicial meshes (triangles in 2D, tetrahedra in 3D) can be used to define the fluid domain; the computations involved in the update procedure are efficient due to discrete operators with small support; and it preserves
discrete circulation
, avoiding numerical diffusion of vorticity.
Volume and shape preservation via moving frame manipulation
Authors: Lipman Yaron , Cohen-Or Daniel , Gal Ran , Levin David
Published: January 2007

This article introduces a method for mesh editing that is aimed at preserving shape and volume. We present two new developments: The first is a minimization of a functional expressing a geometric distance measure between two isometric surfaces. The second is a local volume analysis linking the volume of an object to its surface curvature. Our method is based upon the moving frames representation of meshes. Applying a rotation field to the moving frames defines an isometry. Given rotational constraints, the mesh is deformed by an optimal isometry defined by minimizing the distance measure between original and deformed meshes. The resulting isometry nicely preserves the surface details, but when large rotations are applied, the volumetric behavior of the model may be unsatisfactory. Using the local volume analysis, we define a scalar field by which we scale the moving frames. Scaled and rotated moving frames restore volumetric properties of the original mesh, while properly maintaining the surface details. Our results show that even extreme deformations can be applied to meshes, with only minimal distortion of surface details and object volume.
Maintaining stream statistics over multiscale sliding windows
Authors: Jiao Yishan
Published: January 2007

In this article, we propose a new multiscale sliding window model which differentiates data items in different time periods of the data stream, based on a reasonable monotonicity of resolution assumption. Our model, as a well-motivated extension of the sliding window model, stands halfway between the traditional all-history and time-decaying models. We also present algorithms for estimating two significant data stream statistics---
F
0
and Jacard's similarity coefficient---with reasonable accuracies under the new model. Our algorithms use space logarithmic in the data stream size and linear in the number of windows; they support update time logarithmic in the number of windows and independent of the accuracy required. Our algorithms are easy to implement. Experimental results demonstrate the efficiencies of our algorithms. Our techniques apply to scenarios in which universe sampling is used.
The Sort-Merge-Shrink join
Authors: Jermaine Christopher , Dobra Alin , Arumugam Subramanian , Joshi Shantanu , Pol Abhijit
Published: January 2007

One of the most common operations in analytic query processing is the application of an aggregate function to the result of a relational join. We describe an algorithm called the
Sort-Merge-Shrink
(SMS)
Join
for computing the answer to such a query over large, disk-based input tables. The key innovation of the SMS join is that if the input data are clustered in a statistically random fashion on disk, then at all times, the join provides an online, statistical estimator for the eventual answer to the query as well as probabilistic confidence bounds. Thus, a user can monitor the progress of the join throughout its execution and stop the join when satisfied with the estimate's accuracy or run the algorithm to completion with a total time requirement that is not much longer than that of other common join algorithms. This contrasts with other online join algorithms, which either do not offer such statistical guarantees or can only offer guarantees so long as the input data can fit into main memory.
A perceptually based spectral model for isotropic textures
Authors: Holten Danny , Wijk Jarke J. Van , Martens Jean-Bernard
Published: January 2007

Color is routinely used to visualize interval and ordinal data, while texture is not. For color, a variety of perceptually based models is available, which can be used to convey data via straightforward mapping. The dimensionality of texture is less well understood and there are almost no perceptually based and validated models available to generate textures on demand. We present a perceptually based texture synthesis model for isotropic textures. The model uses additive synthesis of band-limited noise in the spectral domain, comparable to the RGB (red, green, blue) model for color. Via user experiments, we have derived a three-dimensional model to control the amplitudes per band in a perceptually intuitive way, comparable to the HSV (hue, saturation, value) model for color. The three dimensions used are contrast, spatial frequency, and spectral purity. Besides a mapping to the amplitudes, we have derived a mapping to a perceptually equidistant space. We show how such textures can be combined with color; applications are presented.
A reality check for tone-mapping operators
Authors: Ashikhmin Michael , Goyal Jay
Published: January 2007

A large number of high-quality tone-mapping operators is currently available. In addition to inherent practical value, comparing their performance is necessary to further advance the field and can provide better understanding of visual realism. In this paper, we show that it becomes very difficult to meaningfully judge relative performance of modern tone-mapping techniques with existing comparison methods and demonstrate that using real environments is crucial in such experiments. We report results of a new study comparing five recent tone-mapping techniques using this approach.
Visual calibration and correction for ambient illumination
Authors: Devlin Kate , Chalmers Alan , Reinhard Erik
Published: January 2007

Many applications require that an image will appear the same regardless of where or how it is displayed. However, the conditions in which an image is displayed can adversely affect its appearance. Computer monitor screens not only emit light, but can also reflect extraneous light present in the viewing environment. This can cause images displayed on a monitor to appear faded by reducing their perceived contrast. Current approaches to this problem involve measuring this ambient illumination with specialized hardware and then altering the display device or changing the viewing conditions. This is not only impractical, but also costly and time consuming. For a user who does not have the equipment, expertise, or budget to control these facets, a practical alternative is sought. This paper presents a method whereby the display device itself can be used to determine the effect of ambient light on perceived contrast, thus enabling the viewers themselves to perform visual calibration. This method is grounded in established psychophysical experimentation and we present both an extensive procedure and an equivalent rapid procedure. Our work is extended by providing a novel method of contrast correction so that the contrast of an image viewed in bright conditions can be corrected to appear the same as an image viewed in a darkened room. This is verified through formal validation. These methods are easy to apply in practical settings, while accurate enough to be useful.
Semantic role labeling of prepositional phrases
Authors: Ye Patrick , Baldwin Timothy
Published: January 2007

We propose a method for labelling prepositional phrases according to two different semantic role classifications, as contained in the Penn treebank and the CoNLL 2004 Semantic Role Labeling data set. Our results illustrate the difficulties in determining preposition semantics, but also demonstrate the potential for PP semantic role labelling to improve the performance of a holistic semantic role labelling system.
A transformational perspective into the core of an abstract class loader for the SSP
Authors: Winter Victor L. , Beranek Jason , Fraij Fares , Roach Steve , Wickstrom Greg
Published: January 2007

The SSP is a hardware implementation of a subset of the JVM for use in high-consequence embedded applications. In this context, a majority of the activities belonging to class loading, as it is defined in the specification of the JVM, can be performed statically. Static class loading has the net result of dramatically simplifying the design of the SSP, as well as increasing its performance. Because of the high consequence nature of its applications, strong evidence must be provided that all aspects of the SSP have been implemented correctly. This includes the class loader. This article explores the possibility of formally verifying a class loader for the SSP implemented in the strategic programming language TL. Specifically, an implementation of the core activities of an abstract class loader is presented and its verification in ACL2 is considered.
VISTA
Authors: Kulkarni Prasad , Zhao Wankang , Hines Stephen , Whalley David , Yuan Xin , Engelen Robert van , Gallivan Kyle , Hiser Jason , Davidson Jack , Cai Baosheng , Bailey Mark , Moon Hwashin , Cho Kyunghwan , Paek Yunheung
Published: January 2007

Software designers face many challenges when developing applications for embedded systems. One major challenge is meeting the conflicting constraints of speed, code size, and power consumption. Embedded application developers often resort to hand-coded assembly language to meet these constraints since traditional optimizing compiler technology is usually of little help in addressing this challenge. The results are software systems that are not portable, less robust, and more costly to develop and maintain. Another limitation is that compilers traditionally apply the optimizations to a program in a fixed order. However, it has long been known that a single ordering of optimization phases will not produce the best code for every application. In fact, the smallest unit of compilation in most compilers is typically a function and the programmer has no control over the code improvement process other than setting flags to enable or disable certain optimization phases. This paper describes a new code improvement paradigm implemented in a system called VISTA that can help achieve the cost/performance trade-offs that embedded applications demand. The VISTA system opens the code improvement process and gives the application programmer, when necessary, the ability to finely control it. VISTA also provides support for finding effective sequences of optimization phases. This support includes the ability to interactively get static and dynamic performance information, which can be used by the developer to steer the code improvement process. This performance information is also internally used by VISTA for automatically selecting the best optimization sequence from several attempted. One such feature is the use of a genetic algorithm to search for the most efficient sequence based on specified fitness criteria. We include a number of experimental results that evaluate the effectiveness of using a genetic algorithm in VISTA to find effective optimization phase sequences.
Offset assignment using simultaneous variable coalescing
Authors: Ottoni Desiree , Ottoni Guilherme , Araujo Guido , Leupers Rainer
Published: January 2007

The generation of efficient addressing code is a central problem in compiling for processors with restricted addressing modes, like digital signal processors (DSPs). Offset assignment (OA) is the problem of allocating scalar variables to memory, so as to minimize the need of addressing instructions. This problem is called simple offset assignment (SOA) when a single address register is available, and general offset assignment (GOA) when more address registers are used. This paper shows how variables' liveness information can be used to dramatically reduce the addressing instructions required to access local variables on the program stack. Two techniques that make effective use of variable coalescing to solve SOA and GOA are described, namely coalescing SOA (CSOA) and coalescing GOA (CGOA). In addition, a thorough comparison between these algorithms and others described in the literature is presented. The experimental results, when compiling MediaBench benchmark programs with the LANCE compiler, reveal a very significant improvement of the proposed techniques over the other available solutions to the problem.
Repetitive Activation of Glutamatergic Inputs Evokes a Long-Lasting Excitation in Rat Globus Pallidus Neurons In Vitro
Authors: Kaneda Katsuyuki , Kita Takako , Kita Hitoshi
Published: January 2007

External globus pallidus (GPe) neurons express abundant metabotropic glutamate receptor 1 (mGluR1) in their somata and dendrites and receive glutamatergic inputs mainly from the subthalamic nucleus. We investigated whether synaptically released glutamate could activate mGluR1s using whole cell and cell-attached recordings in rat brain slice preparations. Repetitive internal capsule stimulation evoked EPSPs followed by a slow depolarizing response (sDEPO) lasting 10–20 s. Bath application of both GABAA and GABAB receptor antagonists increased the amplitude of sDEPOs. A mixture of AMPA/kainate and N-methyl-d-aspartate receptor antagonists did not alter sDEPOs. The induction of sDEPOs was only partially mediated by mGluR1 because mGluR1 antagonists reduced but failed to completely block the responses. Voltage-clamp recordings revealed that slow inward currents sensitive to mGluR1 antagonist were larger at −60 than at −100 mV, whereas the currents insensitive to mGluR1 antagonist were larger at −100 than at −60 mV. In cell-attached recordings, repetitive internal capsule stimulation evoked long-lasting excitations in GPe neurons, which were also partially suppressed by mGluR1 antagonists. Application of a glutamate uptake inhibitor or an mGluR1 agonist significantly increased the spontaneous firing rate but decreased the excitations to repetitive stimulation. These results suggest that synaptically released glutamate can activate mGluR1, contributing to the induction of long-lasting excitation in GPe neurons and that background mGluR1 activation suppresses the slow mGluR1 responses. Thus mGluR1 may play important roles in the control of GPe neuronal activity.
Evolution and structural diversification of hyperpolarization-activated cyclic nucleotide-gated channel genes
Authors: Jackson Heather A. , Marshall Christian R. , Accili Eric A.
Published: January 2007

Hyperpolarization-activated cyclic nucleotide-gated (HCN) channels are members of the voltage-gated channel superfamily and play a critical role in cellular pace-making. Overall sequence conservation is high throughout the family, and channel functions are similar but not identical. Phylogenetic analyses are imperative to understand how these genes have evolved and to make informed comparisons of HCN structure and function. These have been previously limited, however, by the small number of available sequences, from a minimal number of species unevenly distributed over evolutionary time. We have now identified and annotated 31 novel genes from invertebrates, urochordates, fish, amphibians, birds, and mammals. With increased sequence numbers and a broader species representation, a more precise sequence comparison was performed and an evolutionary history for these genes was constructed. Our data confirm the existence of at least four vertebrate paralogs and suggest that these arose via three duplication and diversification events from a single ancestral gene. Additional lineage-specific duplications appear to have occurred in urochordate and fish genomes. Based on exon boundary conservation and phylogenetic analyses, we hypothesize that mammalian gene structure was established, and duplication events occurred, after the divergence of urochordates and before the divergence of fish from the tetrapod lineage. In addition, we identified highly conserved sequence regions that are likely important for general HCN functions, as well as regions with differences conserved among each of the individual paralogs. The latter may underlie more subtle isoform-specific properties that are otherwise masked by the high identity among mammalian orthologs and/or inaccurate alignments between paralogs.
Kinin Infusion Prevents Renal Inflammation, Apoptosis, and Fibrosis via Inhibition of Oxidative Stress and Mitogen-Activated Protein Kinase Activity
Authors: Chao Julie , Li Huey-Jiun , Yao Yu-Yu , Shen Bo , Gao Lin , Bledsoe Grant , Chao Lee
Published: January 2007

The progression of renal disease displays several characteristics, including proteinuria, apoptosis, inflammation, and fibrosis. In this study, we investigated the effect of long-term infusion of kinin in protection against salt-induced renal damage in Dahl salt-sensitive rats. Dahl salt-sensitive rats were fed a high-salt diet for 2 weeks and were then infused with bradykinin (500 ng/h) via subcutaneously implanted minipumps for 3 weeks. Kinin infusion attenuated salt-induced impaired renal function as evidenced by reduced proteinuria, serum creatinine, and blood urea nitrogen levels without apparent effect on blood pressure. Morphological analysis indicated that kinin administration reduced salt-induced glomerular sclerosis, tubular dilatation, luminal protein cast formation, and interlobular arterial thickness. Kinin also significantly lowered collagen I, III, and IV deposition and their mRNA levels. Moreover, kinin reduced interstitial monocyte/macrophage accumulation, as well as tubular cell apoptosis and caspase-3 activity. Protection of renal injury by kinin was associated with increased renal NO levels and reduced nicotinamide adenine dinucleotide/nicotinamide adenine dinucleotide phosphate oxidase activities and superoxide generation. Suppression of oxidative stress by kinin was accompanied by reduced transforming growth factor-β1 protein and mRNA levels, as well as decreased phosphorylation of mitogen-activated protein kinases. This is the first study to demonstrate that kinin infusion can directly protect against salt-induced renal injury without blood pressure reduction by inhibiting apoptosis, inflammation, and fibrosis via suppression of oxidative stress, transforming growth factor-β1 expression, and mitogen-activated protein kinase activation.
Left Ventricular Mass, Blood Pressure, and Lowered Cognitive Performance in the Framingham Offspring
Authors: Elias Merrill F. , Sullivan Lisa M. , Elias Penelope K. , D’Agostino Ralph B. , Wolf Philip A. , Seshadri Sudha , Au Rhoda , Benjamin Emelia J. , Vasan Ramachandran S.
Published: January 2007

The purpose of this study was to determine whether echocardiographic left ventricular mass is related to cognitive performance beyond casual blood pressure adjusting for the influence of other vascular risk factors. We used multivariable regression analyses to relate left ventricular mass assessed at a routine examination (1995–1998) to measures of cognitive ability obtained routinely (1998–2001) in 1673 Framingham Offspring Study participants (56% women; mean age: 57 years) free from stroke, transient ischemic attack, and dementia. We adjusted for the following covariates hierarchically: (1) age, education, sex, body weight, height, interval between left ventricular mass measurement and neuropsychological testing (basic model); (2) basic model+blood pressure+treatment for hypertension; and (3) basic model+blood pressure+treatment for hypertension+vascular risk factors and prevalent cardiovascular disease. For the basic model, left ventricular mass was inversely associated with abstract reasoning (similarities), visual-spatial memory and organization, and verbal memory. For the basic model+blood pressure+treatment for hypertension, left ventricular mass was inversely associated with similarities and visual-spatial memory and organization. For the basic+blood pressure+treatment for hypertension+risk factors+cardiovascular disease model, no significant associations were observed. Echocardiographic left ventricular mass is associated with cognitive performance beyond casual and time-averaged systolic blood pressure, but this association is attenuated and rendered nonsignificant with additional adjustment for cardiovascular risk factors and cardiovascular disease, thus suggesting that these variables play an important role in mediating the association between left ventricular mass and cognition.