bluuebunny/crossref_metadata_2025 huggingface dataset:
Quality technical information
Authors: Mandel Theo
Published: August 2005

Principles of information style and design have been around for years. Look at the shelf life of Strunk and White's classic The Elements of Style, published in 1959 and still a bestseller. Producing Quality Technical Information is a gem of a book, whose precise, bullet-style list of seven requirements and a checklist is now even more insightful in the fast-paced world of online information and the World-Wide Web. As a writer, I'm amazed how the IBM authors crystallized the essence of good information design in less than 100 pages. This commentary describes how the book's seven qualities and thirty individual requirements can easily and usefully be extrapolated to address key issues of interface design and usability for today's professional designers and developers.
Some reflections on the emergence of a profession
Authors: Grice Roger A.
Published: August 2005

Producing Quality Technical Information played a major role in the shift from product-oriented information to user-oriented information. It brought to a large community of technical communicators an awareness of the role that technical information should play: not a description of a technical product or process but, rather, a description of what people need to do to use the product or perform the process. This shift in focus -- from product to user -- led to many changes in our profession and in our professional careers. No longer mere documentors of what others had done, we emerged as professionals who added value and usability to the project on which we worked.
Static resource models for code-size efficient embedded processors
Authors: Zhao Qin , Mesman Bart , Basten Twan
Published: August 2005

Due to an increasing need for flexibility, embedded systems embody more and more programmable processors as their core components. Due to silicon area and power considerations, the corresponding instruction sets are often highly encoded to minimize code size for given performance requirements. This has hampered the development of robust optimizing compilers because the resulting irregular instruction set architectures are far from convenient compiler targets. Among other considerations, they introduce an interdependence between the tasks of instruction selection and scheduling. This so-called
phase coupling
is so strong that, in practice, instruction selection rather than scheduling is responsible for the quality of the schedule, which tends to disappoint. The lack of efficient compilation tools has also severely hampered the design space exploration of code-size efficient instruction sets, and correspondingly, their tuning to the application domain. In this article, we present an approach that reduces the need for explicit instruction selection by transferring constraints implied by the instruction set to static resource constraints. All resulting schedules are then guaranteed to correspond to a valid implementation with given instructions. We also demonstrate the suitability of this model to enable instruction set design (-space exploration) with a simple, well-understood and proven method long used in high-level synthesis (HLS) of ASICs. Experimental results show the efficacy of our approach.
Cool-Cache
Authors: Unsal Osman S. , Ashok Raksit , Koren Israel , Krishna C. Mani , Moritz Csaba Andras
Published: August 2005

The unique characteristics of multimedia/embedded applications dictate media-sensitive architectural and compiler approaches to reduce the power consumption of the data cache. Our goal is exploring energy savings for embedded/multimedia workloads without sacrificing performance. Here, we present two complementary media-sensitive energy-saving techniques that leverage static information. While our first technique is applicable to existing architectures, in our second technique we adopt a more radical approach and propose a new tagless caching architecture by reevaluating the architecture--compiler interface.Our experiments show that substantial energy savings are possible in the data cache. Across a wide range of cache and architectural configurations, we obtain up to 77% energy savings, while the performance varies from 14% improvement to 4% degradation depending on the application.
Power management for energy-aware communication systems
Authors: Schurgers Curt , Raghunathan Vijay , Srivastava Mani B.
Published: August 2005

System-level power management has become a key technique to render modern wireless communication devices economically viable. Despite their relatively large impact on the system energy consumption, power management for radios has been limited to shutdown-based schemes, while processors have benefited from superior techniques based on dynamic voltage scaling (DVS). However, similar scaling approaches that trade-off energy versus performance are also available for radios. To utilize these in radio power management, existing packet scheduling policies have to be thoroughly rethought to make them energy-aware, essentially opening a whole new set of challenges the same way the introduction of DVS did to CPU task scheduling. We use one specific scaling technique, dynamic modulation scaling (DMS), as a vehicle to outline these challenges, and to introduce the intricacies caused by the nonpreemptive nature of packet scheduling and the time-varying wireless channel.
An experimental study of online scheduling algorithms
Authors: Albers Susanne , Schröder Bianca
Published: August 2005

We present the first comprehensive experimental study of online algorithms for Graham's scheduling problem. Graham's scheduling problem is a fundamental problem in scheduling theory where a sequence of jobs has to be scheduled on
m
identical parallel machines so as to minimize the makespan. Graham gave an elegant algorithm that is (2-1/
m
)-competitive. Recently a number of new online algorithms were developed that achieve competitive ratios around 1.9. Since competitive analysis can only capture the worst case behavior of an algorithm a question often asked is: Are these new algorithms geared only towards a pathological case or do they perform better in practice, too?We address this question by analyzing the algorithms on various job sequences. In our actual tests, we analyzed the algorithms (1) on real world jobs and (2) on jobs generated by probability distributions. It turns out that the performance of the algorithms depends heavily on the characteristics of the respective work load. On job sequences that are generated by standard probability distributions, Graham's strategy is clearly the best. However, on the real world jobs the new algorithms often outperform Graham's strategy. Our experimental study confirms theoretical results in the sense that there are also job sequences in practice on which the new online algorithms perform better. Our study can help to inform practitioners about the new scheduling strategies as an alternative to Graham's algorithm.
Implementation of approximation algorithms for weighted and unweighted edge-disjoint paths in bidirected trees
Authors: Erlebach Thomas , Jansen Klaus
Published: August 2005

Given a set of weighted directed paths in a bidirected tree, the maximum weight edge-disjoint paths problem (MWEDP) is to select a subset of the given paths such that the selected paths are edge-disjoint and the total weight of the selected paths is maximized. MWEDP is
NP
- hard for bidirected trees of unbounded degree, even if all weights are the same (the unweighted case). Three different approximation algorithms are implemented: a known combinatorial (5/3 + ε)-approximation algorithm
A
1
for the unweighted case, a new combinatorial 2-approximation algorithm
A
2
for the weighted case, and a known (5/3 + ε)-approximation algorithm
A
3
for the weighted case that is based on linear programming. For algorithm
A
1
, it is shown how efficient data structures can be used to obtain a worst-case running-time of

O(m + n + 4
1/ε
√n ċ m)

for instances consisting of
m
paths in a tree with
n
nodes. Experimental results regarding the running-times and the quality of the solutions obtained by the three approximation algorithms are reported. Where possible, the approximate solutions are compared to the optimal solutions, which were computed by running CPLEX on an integer linear programming formulation of MWEDP.
Relational concept learning by cooperative evolution
Authors: Neri Filippo
Published: August 2005

Concept learning is a computationally demanding task that involves searching large hypothesis spaces containing candidate descriptions. Stochastic search combined with parallel processing provide a promising approach to successfully deal with such computationally intensive tasks.Learning systems based on distributed genetic algorithms (GA) were able to find concept descriptions as accurate as the ones found by state-of-the-art learning systems based on alternative approaches. However, genetic algorithms' exploitation has the drawback of being computationally demanding.We show how a suitable architectural choice, named cooperative evolution, allows to solve complex applications in an acceptable user waiting time and with a reasonable computational cost by using GA-based learning systems because of the effective exploitation of distributed computation. A variety of experimental settings is analyzed and an explanation for the empirical observations is proposed.
Caching and Scheduling for Broadcast Disk Systems
Authors: Liberatore Vincenzo
Published: August 2005

Unicast connections lead to performance and scalability problems when a large client population attempts to access the same data. Broadcast push and broadcast disk technology address the problem by broadcasting data items from a server to a large number of clients. Broadcast disk performance depends mainly on caching strategies at the client site and on how the broadcast is scheduled at the server site. An on-line broadcast disk paging strategy makes caching decisions without knowing future page requests or access probabilities. This paper gives new implementations of existing on-line algorithms and reports on extensive empirical investigations. The gray algorithm [Khanna and Liberatore 2000] always outperformed other on-line strategies on both synthetic and Web traces. Moreover, caching limited the skewness of broadcast schedules, and led to favor efficient caching algorithms over refined scheduling strategies when the cache was large.
Geometric Minimum Spanning Trees via Well-Separated Pair Decompositions
Authors: Narasimhan Giri , Zachariasen Martin
Published: August 2005

Let
S
be a set of
n
points in
ℜ

d

. We present an algorithm that uses the
well-separated pair decomposition and computes the minimum spanning
tree of
S
under any

L
p

or polyhedral
metric. A theoretical analysis shows that it has an expected
running time of
O(n
log
n
) for uniform point
distributions; this is verified experimentally. Extensive
experimental results show that this approach is practical. Under a
variety of input distributions, the resulting implementation is
robust and performs well for points in higher dimensional
space.
An Experimental Study of Dynamic Algorithms for Transitive Closure
Authors: Frigioni Daniele , Miller Tobias , Nanni Umberto , Zaroliagis Christos
Published: August 2005

We perform an extensive experimental study of several dynamic algorithms for transitive closure. In particular, we implemented algorithms given by Italiano, Yellin, Cicerone et al., and two recent randomized algorithms by Henzinger and King. We propose a fine-tuned version of Italiano's algorithms as well as a new variant of them, both of which were always faster than any of the other implementations of the dynamic algorithms. We also considered simple-minded algorithms that were easy to implement and likely to be fast in practice. Wetested and compared the above implementations on random inputs, on non-random inputs that are worst-case inputs for the dynamic algorithms, and on an input motivated by a real-world graph.
Tiny instruction caches for low power embedded systems
Authors: Gordon-Ross Ann , Cotterell Susan , Vahid Frank
Published: August 2005

Instruction caches have traditionally been used to improve software performance. Recently, several tiny instruction cache designs, including filter caches and dynamic loop caches, have been proposed to instead reduce software power. We propose several new tiny instruction cache designs, including preloaded loop caches, and one-level and two-level hybrid dynamic/preloaded loop caches. We evaluate the existing and proposed designs on embedded system software benchmarks from both the Powerstone and MediaBench suites, on two different processor architectures, for a variety of different technologies. We show on average that filter caching achieves the best instruction fetch energy reductions of 60--80%, but at the cost of about 20% performance degradation, which could also affect overall energy savings. We show that dynamic loop caching gives good instruction fetch energy savings of about 30%, but that if a designer is able to profile a program, preloaded loop caching can more than double the savings. We describe automated methods for quickly determining the best loop cache configuration, methods useful in a core-based design flow.
Compressing MIPS code by multiple operand dependencies
Authors: Lin Kelvin , Chung Chung-Ping , Shann Jean Jyh-Jiun
Published: August 2005

Intuitively, destination registers of some instructions have great possibilities to be used as the source registers of the immediately subsequent instructions. Such destination register/source register pairs have been exploited previously to improve code compression ratio [
compression ratio
= (
Dictionary Size
+
Encoded Program Size
)/
Original Program Size
]. This paper further examines the exploitation of both register and immediate operand dependencies to improve the compression ratio. A mapping tag is used to flag dependency relationships so that dependent operands can be omitted during compression. The compression ratio is enhanced by both the removal of dependent operands and the sharing of mapping tags between different types of dependencies and between different instructions. Simulation results show that the proposed method results in the best compression ratio achieved so far, giving average compression ratios of 33.8% for MediaBench benchmarks and 33.6% for SPEC95 benchmarks, both compiled for a MIPS R2000 processor.
Speculating to reduce unnecessary power consumption
Authors: Musoll Enric
Published: August 2005

The power consumption of current processors keeps increasing in spite of aggressive circuit design techniques and process shrinks. One of the reasons for this increase is the complexity of the microarchitecture required to achieve the performance that each processor generation demands. These techniques, such as branch prediction and on-chip level two caches, increase not only the power consumption of the committed instructions, but also the useless power associated with those block accesses that generate results that are not needed for the correct execution and commit of the instructions.In this work, the different accesses that a particular block receives are classified into four different components, based on whether the accesses are performed by instructions of the correct path or the wrong (mispredicted) path, and also based on whether the results of the accesses are needed or not for the correct execution of the instructions. Out of the four components, only one accounts for the useful accesses to the block, that is, accesses performed to correctly execute instructions that will be committed. The other three components account for the useless activity on the block. The simulations performed indicate that, if the useless power dissipation of a high-performance processor could be totally removed with no performance degradation, the overall processor power consumption would be reduced by as much as 65% compared to the same processor in which all the blocks are accessed every cycle.This work then proposes a microarchitectural technique that targets the reduction of the useless power dissipation. The technique consists of predicting whether the result of a particular block of logic will be useful in order to execute the instructions (no matter whether the instructions will be eventually committed or not). If it is predicted useless, then the block is disabled.A case example is presented where two blocks are predicted for low power: the on-chip L2 cache for instruction fetches and the branch target buffer (BTB). The IPC versus power-consumption design space is explored for a particular microprocessor architecture. Both the average and the peak power consumption are targeted. High-level estimations are done to show that it is plausible that the ideas described might produce a significant reduction in useless block accesses. As an example, 65% accesses to the L2 cache can be eliminated at a 0.2% IPC degradation, and about 5% accesses to the BTB can be saved at the penalty of 0.7% IPC reduction.
Liemandt Foundation launches hidden agenda contest
Authors: Davis Lauren
Published: August 2005

The Liemandt Foundation, a nonprofit family foundation focused on promoting technology-enabled education, launched on September 18, 2003 a college student video game development contest with a twist -- students are being challenged to build entertaining games that "secretly" teach middle school subjects.The contest, online at www.hiddenagenda.com, focuses on the notion of "stealth education" in gaming, pushing students to create primarily entertaining games that also teach science and math topics such as forces, statistics, or the solar system. Students have complete freedom in their game designs. They may work in teams of up to eight people, can build the games on and for any platform, and may use existing engines if they choose. Games will be judged in May 2004, with five finalist teams flying to Austin, Texas for their final shot at the $25,000 prize.Advising the contest are experts such as Ultima creator and gaming legend Richard Garriott and educational game visionary Marc Prensky, and the project is affiliated with the Digital Media Collaboratory at the University of Texas. "There is no doubt in my mind that college students can create the next breakthrough educational video game," says Garriott. Prensky agrees, "I look forward to watching these motivated and creative students break through the barriers of historically boring learning games." Among the many benefits of challenging college students to build the game is the notion that once these students enter the professional game development community, they will understand the importance and potential of stealth education.While all submitted games must fulfill teaching and technical requirements to be considered, final judging is based on 70% entertainment and 30% educational value. The uneven split in judging criteria is crucial. In the past, educational games have failed because no matter how well they taught, kids just weren't motivated to absorb information. Children will only learn from the games they want to play.
Interview with Roy E. Disney
Authors: Disney Roy E.
Published: August 2005

The legendary Alan Kay and Roy E. Disney have graciously
appeared on camera for interviews and joined the ACM Computers in
Entertainment magazine's editorial board. Alan and Roy are two of
the nicest people to talk to and work with. Alan talked about soft
fun versus hard fun, and his research on Squeak for enhancing and
amplifying learning in children's education. Roy told us about
educators versus entertainers, and his views on traditional and CGI
animations. The video clips of the interviews are available at
http://www.acm.org/pubs/cie/oct2003/index.html

Roy E. Disney is Vice Chairman of the Board of Directors of The
Walt Disney Company and chairman of Walt Disney Animation. He began
his entertainment industry career in 1953, working as an assistant
film editor on the "Dragnet" TV series. He joined The Walt Disney
Company in 1954 and served as assistant film editor on motion
pictures, including "The Living Desert" and "The Vanishing Prairie"
both Academy Award winners. As a writer and production associate,
Roy received an Academy Award nomination his work on the short
subject "Mysteries of the Deep" in 1959. More information is
available at
http://psc.disney.go.com/corporate/communications/bios/Disney.html
What video games have to teach us about learning and literacy
Authors: Gee James Paul
Published: August 2005

Good computer and video games like System Shock 2, Deus Ex, Pikmin, Rise of Nations, Neverwinter Nights, and Xenosaga: Episode 1 are learning machines. They get themselves learned and learned well, so that they get played long and hard by a great many people. This is how they and their designers survive and perpetuate themselves. If a game cannot be learned and even mastered at a certain level, it won't get played by enough people, and the company that makes it will go broke. Good learning in games is a capitalist-driven Darwinian process of selection of the fittest. Of course, game designers could have solved their learning problems by making games shorter and easier, by dumbing them down, so to speak. But most gamers don't want short and easy games. Thus, designers face and largely solve an intriguing educational dilemma, one also faced by schools and workplaces: how to get people, often young people, to learn and master something that is long and challenging--and enjoy it, to boot.
Digital game-based learning
Authors: Prensky Marc
Published: August 2005

Research published by University of Rochester neuroscientists C. Shawn Green and Daphne Bavelier has grabbed national attention for suggesting that playing "action" video and computer games has the positive effect of enhancing student's visual selective attention. But that finding is just one small part of a more important message that all parents and educators need to hear: Video games are not the enemy, but the best opportunity we have to engage our kids in real learning.
Modeling and validation of pipeline specifications
Authors: Mishra Prabhat , Dutt Nikil
Published: August 2005

Verification is one of the most complex and expensive tasks in the current Systems-on-Chip design process. Many existing approaches employ a bottom-up approach to pipeline validation, where the functionality of an existing pipelined processor is, in essence, reverse-engineered from its RT-level implementation. Our validation technique is complementary to these bottom-up approaches. Our approach leverages the system architect's knowledge about the behavior of the pipelined architecture, through architecture description language (ADL) constructs, and thus allows a powerful top-down approach to pipeline validation. The most important requirement in top-down validation process is to ensure that the specification (reference model) is golden. This paper addresses automatic validation of processor, memory, and coprocessor pipelines described in an ADL. We present a graph-based modeling that captures both structure and behavior of the architecture. Based on this model, we present algorithms to ensure that the static behavior of the pipeline is well formed by analyzing the structural aspects of the specification. We applied our methodology to verify specification of several realistic architectures from different architectural domains to demonstrate the usefulness of our approach.
Processor-memory coexploration using an architecture description language
Authors: Mishra Prabhat , Mamidipaka Mahesh , Dutt Nikil
Published: August 2005

Memory represents a major bottleneck in modern embedded systems in terms of cost, power, and performance. Traditionally, memory organizations for programmable embedded systems assume a fixed cache hierarchy. With the widening processor--memory gap, more aggressive memory technologies and organizations have appeared, allowing customization of a heterogeneous memory architecture tuned for specific target applications. However, such a processor--memory coexploration approach critically needs the ability to explicitly capture heterogeneous memory architectures. We present in this paper a language-based approach to explicitly capture the memory subsystem configuration, generate a memory-aware software toolkit, and perform coexploration of the processor--memory architectures. We present a set of experiments using our memory-aware architectural description language (ADL) to drive the exploration of the memory subsystem for the TI C6211 processor architecture, demonstrating cost, performance, and energy trade-offs.
Compiling with code-size constraints
Authors: Naik Mayur , Palsberg Jens
Published: August 2005

Most compilers ignore the problems of limited code space in embedded systems. Designers of embedded software often have no better alternative than to manually reduce the size of the source code or even the compiled code. Besides being tedious and error prone, such optimization results in obfuscated code that is difficult to maintain and reuse. In this paper, we present a step towards code-size-aware compilation. We phrase register allocation and code generation as an integer linear programming problem where the upper bound on the code size can simply be expressed as an additional constraint. The resulting compiler, when applied to six commercial microcontroller programs, generates code nearly as compact as carefully crafted code.
Welcome
Authors: Lee Newton
Published: August 2005

Welcome to the second issue of the ACM Computers In
Entertainment online magazine!

We continue the theme of Educating Children Through
Entertainment with a diversity of topics on virtual reality,
interactive theaters, storyrooms, playsets, and music. In
particular, we explore the educational value of entertainment and
the technology behind it.
Coming soon
Authors: Lee Newton
Published: August 2005

RoBallet: Creativity Can Be Hard Fun

Learning by Doing and Learning through Play: An Exploration of
Interactivity in Virtual Environments for Children

Tools for Children to Create Physical Interactive
StoryRooms

A Friendly Face in Robotics: Sony's AIBO Entertainment Robot as
an Educational Tool

Think science! Entertainment Education in Interactive
Theaters

When Children Reflect on their Own Playing Style: Experiments
with Continuator and and Children

Edutainmetn: A Case Study of Interactive CD-ROM Playsets

Development and Utilization of Asobiuta KARAOKE for Elementary
Music Education Available on the Internet

and more...
When children reflect on their own playing style
Authors: Pachet Francois , Addessi Anna Rita
Published: August 2005

The Continuator project concerns the study of interactive musical
systems that are able to learn musical styles. The Continuator
system was developed with the primary goal of designing new musical
instruments in the context of improvised music. The strong
subjective impressions created with the use of the system led us to
consider its use in a pedagogical context. This article describes
experiments conducted with the system and 3- to 5-year-old
children. We highlight several dimensions of the study pertaining
to music education, including attention span, spontaneous
development of playing modes, and capacity to listen analytically.
We describe very encouraging preliminary results and stress the
importance of using reflective interactive systems for triggering
musical interest in children and creating stimulating,
nonsupervised music learning environments. We conclude by setting
up our research in the context of the theory of flow as an optimal
experience.
Development and utilization of Asobiuta karaoke for elementary music education on the internet
Authors: Miyashita Homei
Published: August 2005

Asobiuta, Japanese traditional nursery rhymes, are now outdated,
but are extremely useful for the early-stages in music education
because they are very enjoyable and easy to remember without a
music score. We attempted to produce a karaoke animation program on
asobiuta that would be available on TV and the Internet. During the
creation process, we arranged these songs into popular music format
and designed the animation to resemble karaoke, so that children
could sing them by following the words on a video screen.
Adaptive scheduling server for power-aware real-time tasks
Authors: Mejia-Alvarez Pedro , Levner Eugene , Mossé Daniel
Published: August 2005

In this paper, we propose a novel scheduling framework for a dynamic real-time environment with energy constraints. This framework dynamically adjusts the CPU voltage/frequency so that no task in the system misses its deadline and the total energy savings of the system are maximized. In this paper, we consider only realistic, discrete-level speeds.Each task in the system consumes a certain amount of energy, which depends on a speed chosen for execution. The process of selecting speeds for execution while maximizing the energy savings of the system requires the exploration of a large number of combinations, which is too time consuming to be computed online. Thus, we propose an integrated heuristic methodology, which executes an optimization procedure in a low computation time. This scheme allows the scheduler to handle power-aware real-time tasks with low cost while maximizing the use of the available resources and without jeopardizing the temporal constraints of the system. Simulation results show that our heuristic methodology is able to generate power-aware scheduling solutions with near-optimal performance.
Dynamic adaptation for fault tolerance and power management in embedded real-time systems
Authors: Zhang Ying , Chakrabarty Krishnendu
Published: August 2005

Safety-critical embedded systems often operate in harsh environmental conditions that necessitate fault-tolerant computing techniques. In addition, many safety-critical systems execute real-time applications that require strict adherence to task deadlines. These embedded systems are also energy-constrained, since system lifetime is determined largely by the battery lifetime. In this paper, we investigate dynamic adaptation techniques based on checkpointing and dynamic voltage scaling (DVS) for fault tolerance and power management. We first present schedulability tests that provide the criteria under which checkpointing can provide fault tolerance and real-time guarantees. We then present an adaptive checkpointing scheme in which the checkpointing interval for a task is dynamically adjusted during execution, and checkpoints are inserted based not only on the available slack, but also on the occurrences of faults. Next, we combine adaptive checkpointing with DVS to achieve power reduction. Finally, we develop an adaptive checkpointing scheme for a set of multiple tasks in real-time systems. An offline preprocessing based on linear programming is used to determine the parameters that are provided as inputs to the online adaptive checkpointing procedure. Simulation results show that compared to previous methods, the proposed adaptive checkpointing approach increases the likelihood of timely task completion in the presence of faults. When combined with DVS, adaptive checkpointing also leads to considerable energy savings.
A learning algorithm for the longest common subsequence problem
Authors: Breimer Eric A. , Goldberg Mark K. , Lim Darren T.
Published: August 2005

We present an experimental study of a learning algorithm for the longest common subsequence problem,
LCS
. Given an arbitrary input domain, the algorithm learns an
LCS
-procedure tailored to that domain. The learning is done with the help of an oracle, which can be any
LCS
-algorithm. After solving a limited number of training inputs using an oracle, the learning algorithm outputs a new
LCS
-procedure.Our experiments demonstrate that, by allowing a slight loss of optimality, learning yields a procedure which is significantly faster than the oracle. The oracle used for the experiments is the
np
-procedure by Wu
et al.
, a modification of Myers' classical
LCS
-algorithm. We show how to scale up the results of learning on small inputs to inputs of arbitrary lengths. For the domain of two random 2-symbol inputs of length
n
, learning yields a program with 0.999 expected accuracy, which runs in
O
(
n
1.41
)-time, in contrast with
O
(
n
2
/log
n
) running time of the fastest theoretical algorithm that produces optimal solutions. For the domain of random 2-symbol inputs of length 100,000, the program runs 10.5 times faster than the
np
-procedure, producing 0.999- accurate outputs. The scaled version of the evolved algorithm applied to random inputs of length 1 million runs approximately 30 times faster than the
np
-procedure while constructing 0.999- accurate solutions. We apply the evolved algorithm to DNA sequences of various lengths by training on random 4-symbol sequences of up to length 10,000. The evolved algorithm, scaled up to the lengths of up to 1.8 million, produces solutions with the 0.998-accuracy in a fraction of the time used by the
np
.
Differences in Onset Latency of Macaque Inferotemporal Neural Responses to Primate and Non-Primate Faces
Authors: Kiani Roozbeh , Esteky Hossein , Tanaka Keiji
Published: August 2005

Neurons in the visual system respond to different visual stimuli with different onset latencies. However, it has remained unknown which stimulus features, aside from stimulus contrast, determine the onset latencies of responses. To examine the possibility that response onset latencies carry information about complex object images, we recorded single-cell responses in the inferior temporal cortex of alert monkeys, while they viewed >1,000 object stimuli. Many cells responded to human and non-primate animal faces with comparable magnitudes but responded significantly more quickly to human faces than to non-primate animal faces. Differences in onset latency may be used to increase the coding capacity or enhance or suppress information about particular object groups by time-dependent modulation.
Neuronal Prostacyclin Is an Autocrine Regulator of Arterial Baroreceptor Activity
Authors: Snitsarev Vladislav , Whiteis Carol A. , Chapleau Mark W. , Abboud Francois M.
Published: August 2005

We tested the hypothesis that neuronal prostacyclin is an autocrine regulator of arterial baroreceptor neuronal activity. In isolated rat aortic nodose baroreceptor neurons, mechanical stimulation depolarized 12 neurons by 13.1±3.4 mV and triggered action potentials in 5 of them, averaging 18.2±9.5 spikes. Current injections depolarized 21 neurons by 29.9±8.0 mV and triggered action potentials averaging 17.0±2.4 spikes. After a period of prolonged neuronal activation with pulses of 1 nA at 20 Hz for 1 minute, the action potential responses to mechanical stimulation and to current injections were first markedly suppressed (0.2±0.2 and 2.1±0.7 spikes, respectively) and then enhanced, reaching levels above control (29.0±8.0 and 21.7±2.6 spikes, respectively) over the subsequent 15 minutes. In contrast, there was no inhibition of the depolarizations caused by mechanical stimulation or current injections. The recovery and enhancement of action potentials, which reached 150±5.4% of control values at 15 minutes (n=13), were abrogated by 10 μmol/L of indomethacin and replaced by sustained inhibition for over 15 minutes. Carbacyclin (10 μmol/L) reversed the inhibition and restored action potential responses. Prostacyclin production by cultured nodose neurons was enhanced by arachidonic acid and electrical field stimulation and inhibited by indomethacin. We conclude that prostacyclin provides an autocrine feedback that restores and enhances the responsiveness of arterial baroreceptor neurons after their inhibition from excessive neuronal activation. We speculate that reduced synthesis of neuronal prostacyclin contributes to the resetting phenomenon and the suppressed activity of arterial baroreceptors in hypertension.
Role of SCN5A Y1102 Polymorphism in Sudden Cardiac Death in Blacks
Authors: Burke Allen , Creighton Wendy , Mont Erik , Li Ling , Hogan Susan , Kutys Robert , Fowler David , Virmani Renu
Published: August 2005

Background—

The Y1102 polymorphism of the cardiac sodium channel (SCN5A) gene has been found in 13% of black Americans. It has been linked to lethal arrhythmias in black families with ventricular tachycardia. The prevalence of the Y1102 polymorphism in a series of sudden death in blacks is unknown.

Methods and Results—

We investigated the incidence of the Y1102 polymorphism in a series of 289 sudden deaths in blacks by sequencing an amplified segment of DNA that contained the polymorphic site extracted from prospectively sampled frozen splenic tissue. The deaths were classified as noncardiac controls (n=107), cardiac arrhythmias with clear anatomic substrate (n=117), cardiac arrhythmias with no anatomic substrate except mild to moderate cardiac hypertrophy (n=40), and unexplained cardiac arrhythmias (n=25). Cause of death was determined after complete forensic autopsy and postmortem cardiac examination. The overall frequency of the Y1102 polymorphism was 9.0%. The frequency was 5.6% in noncardiac deaths, 4.3% in cardiac deaths with obvious anatomic substrate, 20.0% in arrhythmias with moderate hypertrophy, and 28% in unexplained arrhythmias. Adjusted for age and sex, the relative risk of an unexplained arrhythmic death was 8.4 (95% CI 2.1 to 28.6,
P
=0.001) with the Y1102 allele compared with noncardiac deaths. The relative risk for cardiac arrhythmias with mild cardiac hypertrophy was 4.9 (95% CI 1.3 to 13.4,
P
=0.01).

Conclusions—

The Y1102 allele is a risk factor in blacks for sudden cardiac death in the absence of obvious morphological findings or mild to moderate cardiomegaly.
C-Reactive Protein and Cerebral Small-Vessel Disease
Authors: van Dijk E. J. , Prins N. D. , Vermeer S. E. , Vrooman H. A. , Hofman A. , Koudstaal P. J. , Breteler M. M.B.
Published: August 2005

Background—

Inflammatory processes are involved in the development and consequences of atherosclerosis. Whether these processes are also involved in cerebral small-vessel disease is unknown. Cerebral white matter lesions and lacunar brain infarcts are caused by small-vessel disease and are commonly observed on MRI scans in elderly people. These lesions are associated with an increased risk of stroke and dementia. We assessed whether higher C-reactive protein (CRP) levels were related to white matter lesion and lacunar infarcts.

Methods and Results—

We based our study on 1033 participants of the population-based Rotterdam Scan Study for whom complete data on CRP levels were available and who underwent brain MRI scanning. Subjects were 60 to 90 years of age and free of dementia at baseline. Six hundred thirty-six subjects had a second MRI scan on average 3.3 years later. We used multivariate regression models to assess the associations between CRP levels and markers of small-vessel disease. Higher CRP levels were associated with presence and progression of white matter lesions, particularly with marked lesion progression (ORs for highest versus lowest quartile of CRP 3.1 [95% CI 1.3 to 7.2] and 2.5 [95% CI 1.1 to 5.6] for periventricular and subcortical white matter lesion progression, respectively). These associations persisted after adjustment for cardiovascular risk factors and carotid atherosclerosis. Persons with higher CRP levels tended to have more prevalent and incident lacunar infarcts.

Conclusions—

Inflammatory processes may be involved in the pathogenesis of cerebral small-vessel disease, in particular, the development of white matter lesions.
The Simulation of Moisture Processes in Climate Models and Climate Sensitivity
Authors: Hu Haijun , Oglesby Robert J. , Marshall Susan
Published: August 2005

General circulation models (GCMs) designed for projecting climatic change have exhibited a wide range of sensitivity. Therefore, projected surface warming with increasing CO2 varies considerably depending on which model is used. Despite notable advances in computing power and modeling techniques that have occurred over the past decade, uncertainties of model sensitivity have not been reduced accordingly. The sensitivity issue is investigated by examining two GCMs of very different modeling techniques and sensitivity, with attention focused on how moisture processes are treated in these models, how moisture simulations are affected by these processes, and how well these simulations compare to the observed and analyzed moisture field. Both GCMs predict increases of atmospheric moisture with doubled CO2, but the increment predicted by one model is substantially higher (approximately twice) than that predicted by the other. This same difference is seen in responses of the boundary layer diffusive moistening rate. Calculations with a radiative–convective model indicate that the differences in predicted equilibrium atmospheric moisture, including both column amount and vertical distribution, have contributed to the largest differences in model sensitivity between the two models. We argue that in order for climate models to be credible for prediction purposes, they must possess credible skills of simulating surface and boundary layer processes, which likely holds the key to overall moisture performance, its response to external forcing, and in turn to model sensitivity.
The Linear Response of ENSO to the Madden–Julian Oscillation
Authors: Zavala-Garay J. , Zhang C. , Moore A. M. , Kleeman R.
Published: August 2005

The possibility that the tropical Pacific coupled system linearly amplifies perturbations produced by the Madden–Julian oscillation (MJO) is explored. This requires an estimate of the low-frequency tail of the MJO. Using 23 yr of NCEP–NCAR reanalyses of surface wind and Reynolds SST, we show that the spatial structure that dominates the intraseasonal band (i.e., the MJO) also dominates the low-frequency band once the anomalies directly related to ENSO have been removed. This low-frequency contribution of the intraseasonal variability is not included in most ENSO coupled models used to date. Its effect in a coupled model of intermediate complexity has, therefore, been studied. It is found that this “MJO forcing” (τMJO) can explain a large fraction of the interannual variability in an asymptotically stable version of the model. This interaction is achieved via linear dynamics. That is, it is the cumulative effect of individual events that maintains ENSOs in this model. The largest coupled wind anomalies are initiated after a sequence of several downwelling Kelvin waves of the same sign have been forced by τMJO. The cumulative effect of the forced Kelvin waves is to persist the (small) SST anomalies in the eastern Pacific just enough for the coupled ocean–atmosphere dynamics to amplify the anomalies into a mature ENSO event. Even though τMJO explains just a small fraction of the energy contained in the stress not associated with ENSO, a large fraction of the modeled ENSO variability is excited by this forcing. The characteristics that make τMJO an optimal stochastic forcing for the model are discussed. The large zonal extent is an important factor that differentiates the MJO from other sources of stochastic forcing.
Indian Ocean Climate and Dipole Variability in Hadley Centre Coupled GCMs
Authors: Spencer Hilary , Sutton Rowan T. , Slingo Julia M. , Roberts Malcolm , Black Emily
Published: August 2005

Prediction of Indian Ocean interannual variability may be limited by the systematic biases in coupled GCMs or by a lack of resolution of the processes involved. In particular, little is known about the impact of ocean resolution on simulated climate variability. The simulation of Indian Ocean climate and dipole is investigated in Hadley Centre coupled models with different horizontal and vertical ocean resolutions.

The mean state of the Indian Ocean is found to improve only slightly when horizontal resolution is increased from 1.25° to ⅓° and when vertical resolution is increased from 20 to 40 vertical levels due to a small reduction of the Maritime Continent warm bias. However, improvements in the simulation of the dipole are more substantial. All versions of the model realistically simulate dipole onset between April and June, peak in September to October, and then rapidly decay between October and January. The SST anomalies are accompanied by realistic equatorial easterly wind anomalies with thermocline shoaling in the east and deepening in the southwest.

In the model with the 1.25° ocean and 20 vertical levels, the dipoles do not terminate completely but persist through the austral summer and then frequently reinvigorate the following year. This unrealistic behavior is eliminated when the ocean vertical resolution is increased from around 20 m in the thermocline to 10 m in the whole of the top 135 m and when Java is represented (even at 1.25° resolution). It is hypothesized that the improvement is due to the resolution of the separation between the thermocline and the surface and also due to the small reduction of the Maritime Continent warm bias.
Anti-lipid phosphate phosphohydrolase-3 (LPP3) antibody inhibits bFGF- and VEGF-induced capillary morphogenesis of endothelial cells
Authors: Wary Kishore K , Humtsoe Joseph O
Published: August 2005

Background

Angiogenesis, or the remodeling of existing vasculature serves as a lifeline to nourish developing embryos and starved tissues, and to accelerate wound healing, diabetic retinopathy, and tumor progression. Recent studies indicate that angiogenesis requires growth factor activity as well as cell adhesion events mediated by α5β1 and αvβ3 integrins. We previously demonstrated that human lipid phosphate phosphohydrolase-3 (LPP3) acts as a cell-associated ligand for α5β1 and αvβ3 integrins. Here, we test the hypothesis that an anti-LPP3 antibody can inhibit basic fibroblast growth factor (bFGF)-and vascular endothelial growth factor (VEGF)-induced capillary morphogenesis of endothelial cells (ECs).

Results

We report that bFGF and VEGF up-regulate LPP3 protein expression in ECs. Immunoprecipitation analyses show that LPP3 is a cell surface protein and undergoes N-glycosylation. Fluorescent activated cell sorting (FACS) data suggest that anti-LPP3-RGD detects native neoepitope on the surface of activated ECs. Moreover, we demonstrate LPP3 protein expression in tumor endothelium alongside VEGF. The embedding of ECs into three-dimensional type I collagen in the presence of bFGF and VEGF induce capillary formation. Importantly, we show that the addition of an anti-LPP3 antibody specifically and significantly blocks bFGF- and VEGF-induced capillary morphogenesis of ECs.

Conclusion

These data suggest that activated ECs as well as tumor endothelium express LPP3 protein. In an in vitro assay, the anti-LPP3-RGD specifically blocks bFGF and VEGF induced capillary morphogenesis of ECs. Our results, therefore, suggest a role for LPP3 in angiogenesis.