Papers.

Preserving XML queries during schema evolution

In XML databases, new schema versions may be released as frequently as once every two weeks. This poster describes a taxonomy of changes for XML schema evolution. It examines the impact of those changes on schema validation and query evaluation. Based on that study, it proposes guidelines for XML schema evolution and for writing queries in such a way that they continue to operate as expected across evolving schemas.

Characterization of national Web domains

Properties and mechanisms of self-organizing MANET and P2P systems

THE SOCIAL NETWORK OF CONTEMPORARY POPULAR MUSICIANS

Rate-distortion optimized multimedia communication in networks

Superconducting microbolometers for time-resolved terahertz spectroscopy

Optical infrared flame detection system with neural networks

A model for an infrared (IR) flame detection system using artificial neural networks (ANN) is presented. The joint time-frequency analysis (JTFA) in the form of a Short-Time Fourier Transform (STFT) is used for extracting relevant input features for a set of ANNs. Each ANN is trained using the backpropagation conjugate-gradient (CG) method to distinguish all hydrocarbon flames from a particular type of environmental nuisance and background noise. Signal saturation caused by the increased intensity of IR sources at closer distances is resolved by an adjustable gain control. A classification scheme with trained ANN connection weights was implemented on a digital signal processor for use in an industrial hydrocarbon flame detector.

Recent progress in the development of INCITS W1.1: appearance-based image quality standards for printers

In September 2000, INCITS W1 (the U.S. representative of ISO/IEC JTC1/SC28, the standardization committee for office equipment) was chartered to develop an appearance-based image quality standard.^(1),(2) The resulting W1.1 project is based on a proposal⁽⁴⁾ that perceived image quality can be described by a small set of broad-based attributes. There are currently five <i>ad hoc</i> teams, each working towards the development of standards for evaluation of perceptual image quality of color printers for one or more of these image quality attributes. This paper summarizes the work in progress of the teams addressing the attributes of Macro-Uniformity, Color Rendition, Text and Line Quality and Micro-Uniformity.

Economic approximate models for backscattered electrons

The Monte Carlo method is widely used to simulate the signal from a scanning electron microscope. Although the results closely match the actual signal, the method is inherently slow due to the repeated calculation of random trajectories. The authors re-examine the alternative approach of using an approximate model to describe the signal. The authors develop a progressive approximate model which describes the spatial probability distribution of an electron along its entire path. The model also includes information about the angular and energy distribution of the electron. The model is compared to the Monte Carlo method by determining the yield of backscattered electrons as the beam is scanned across a step feature. For this simple feature the model-based approach computes the signal approximately two orders of magnitude faster.

Balanced Overlay Networks (BON): An Overlay Technology for Decentralized Load Balancing

We present a novel framework, called balanced overlay networks (BON), that provides scalable, decentralized load balancing for distributed computing using large-scale pools of heterogeneous computers. Fundamentally, BON encodes the information about each node's available computational resources in the structure of the links connecting the nodes in the network. This distributed encoding is self-organized, with each node managing its in-degree and local connectivity via random-walk sampling. Assignment of incoming jobs to nodes with the most free resources is also accomplished by sampling the nodes via short random walks. Extensive simulations show that the resulting highly dynamic and self-organized graph structure can efficiently balance computational load throughout large-scale networks. These simulations cover a wide spectrum of cases, including significant heterogeneity in available computing resources and high burstiness in incoming load. Prior analytical results show BON's scalability for truly large-scale networks; under certain ideal conditions, the network structure converges to Erdos-Renyi (ER) random graphs. Our simulation results, however, show that the algorithm does much better, and the structures seem to approach the ideal case of d-regular random graphs. We also make a connection between highly-loaded BON and the well-known ball-bin randomized load balancing framework.

Asynchronous Distributed Averaging on Communication Networks

On Rate-Distortion Models for Natural Images and Wavelet Coding Performance

Enabling Real-Time Querying of Live and Historical Stream Data

Improving ICE Service Selection in a P2P System using the Gradient Topology

Towards simulation of electromagnetics and beam physics at the petascale

Under the support of the U.S. DOE SciDAC program, SLAC has been developing a suite of 3D parallel finite- element codes aimed at high-accuracy, high-fidelity electromagnetic and beam physics simulations for the design and optimization of next-generation particle accelerators. Running on the latest supercomputers, these codes have made great strides in advancing the state of the art in applied math and computer science at the petascale that enable the integrated modeling of electromagnetics, self-consistent Particle-In-Cell (PIC) particle dynamics as well as thermal, mechanical, and multi-physics effects. This paper will present 3D results of trapped mode calculations in an ILC cryomodule and the modeling of the ILC Sheet Beam klystron, shape determination of superconducting RF (SCRF) cavities and multipacting studies of SCRF HOM couplers, as well as PIC simulation results of the LCLS RF gun.

Parallel finite element particle-in-cell code for simulations of space-charge dominated beam-cavity interactions

Over the past years,SLAC's Advanced Computations Department (ACD) has developed the parallel finite element (FE) particle-in-cell code Pic3P (Pic2P) for simulations of beam-cavity interactions dominated by space- charge effects. As opposed to standard space-charge dominated beam transport codes, which are based on the electrostatic approximation,Pic3P (Pic2P) includes space-charge, retardation and boundary effects as it self-consistently solves the complete set of Maxwell-Lorentz equations using higher-order FE methods on conformal meshes. Use of efficient, large-scale parallel processing allows for the modeling of photoinjectors with unprecedented accuracy, aiding the design and operation of the next-generation of accelerator facilities. Applications to the Linac Coherent Light Source (LCLS) RF gun are presented.

An End-to-End Solution to Scalable Unstructured P2P Networking

An End-to-End Solution to Scalable Unstructured P2P Networking

Design of high-yield defect-tolerant self-assembled nanoscale memories

Incorporating Performance Testing in Test-Driven Development

Performance design and performance testing are necessarily different from functional test case design. A rigorous test-driven design methodology isn't practical for all performance measurement. A test-first approach to performance provides some advantages in a TDD environment. Experience with applying early performance testing in a TDD framework for a device-driver development project provides insight into the test-first approach. The results show a trend of performance improvement throughout the development life cycle, and better performance compared to an earlier release. Lessons learned include the benefit of having a performance architect on the development team and of tracking performance measurements throughout the development life cycle.This article is part of a special issue on test-driven development.

Service-Oriented E-Learning Platforms: From Monolithic Systems to Flexible Services

Distinctive Features of the Argentinian Web

New Stochastic Algorithms for Scheduling Ads in Sponsored Search

New Stochastic Algorithms for Scheduling Ads in Sponsored Search

Distinctive Features of the Argentinian Web

New Stochastic Algorithms for Scheduling Ads in Sponsored Search

Distinctive Features of the Argentinian Web

A Structured ASIC Design Approach Using Pass Transistor Logic

Decentralized Dynamic Host Configuration in Wide-Area Overlays of Virtual Workstations

Automatic Structuring of IT Problem Ticket Data for Enhanced Problem Resolution

Infrared Flame Detection System Using Multiple Neural Networks

A model for an infrared (IR) flame detection system using multiple artificial neural networks (ANN) is presented. The present work offers significant improvements over our previous design (Huseynov et al., 2005). Feature extraction only in the relevant frequency band using joint time-frequency analysis yields an input to a series of conjugate-gradient (CG) method-based ANNs. Each ANN is trained to distinguish all hydrocarbon flames from a particular type of environmental nuisance and ambient noise. Signal saturation caused by the increased intensity of IR sources at closer distances is resolved by adjustable gain control.

Aspect-Oriented Design in Java/AspectJ and Ruby

The ProgrammableWeb: Agile, Social, and Grassroot Computing

Web services, the semantic Web, and Web 2.0 are three somewhat separate movements trying to make the Web a programmable substrate. While each has achieved some level of success on their own right, it is becoming apparent that the grassroot approach of the Web 2.0 is gaining greater success than the other two. In this paper we analyze each movement, briefly describing its main traits, and outlining its primary assumptions. We then frame the common problem of achieving a programmable Web within the context of distributed computing and software engineering and then attempt to show why Web 2.0 is closest to give a pragmatic solution to the problem and will therefore likely continue to have the most success while the other two only have cursory contributions.

An analysis and design methodology for belief sharing in large groups

Finding Questions to Your Answers

Auditing a Batch of SQL Queries

Challenges on Distributed Web Retrieval

Fault Tolerance in Multiprocessor Systems Via Application Cloning

Toggle Equivalence Preserving (TEP) Logic Optimization

On Complexity of Internal and External Equivalence Checking

Optimal Media Communication in Capacity Constrained Networks

Predicting Future High-Cost Patients: A Real-World Risk Modeling Application

On the Sustained Use of a Test-Driven Development Practice at IBM

Test-driven development (TDD) is an agile practice that is widely accepted and advocated by most agile methods and methodologists. In this paper, we report on a post hoc analysis of the results of an IBM team who has sustained use of TDD for five years and over ten releases of a Java-implemented product. The team worked from a design and wrote tests incrementally before or while they wrote code and, in the process, developed a significant asset of automated tests. The IBM team realized sustained quality improvement relative to a pre-TDD project and consistently had defect density below industry standards. As a result, our data indicate that the TDD practice can aid in the production of high quality products. This quality improvement would compensate for the moderate perceived productivity losses. Additionally, our data indicates that the use of TDD may decrease the degree to which code complexity increases as software ages, as measured by cyclomatic complexity metric.

Age-dependent decay in the landscape

The picture of the "multiverse" arising in diverse cosmological scenarios involves transitions between metastable vacuum states. It was pointed out by Krauss and Dent that the transition rates decrease at very late times, leading to a dependence of the transition probability between vacua on the age of each vacuum region. I investigate the implications of this non-Markovian, age-dependent decay on the global structure of the spacetime in landscape scenarios. I show that the fractal dimension of the eternally inflating domain is precisely equal to 3, instead of being slightly below 3 in scenarios with purely Markovian, age-independent decay. I develop a complete description of a non-Markovian landscape in terms of a nonlocal master equation. Using this description I demonstrate by an explicit calculation that, under some technical assumptions about the landscape, the probabilistic predictions of our position in the landscape are essentially unchanged, regardless of the measure used to extract these predictions. I briefly discuss the physical plausibility of realizing non-Markovian vacuum decay in cosmology in view of the possible decoherence of the metastable quantum state.

Attractor scenarios and superluminal signals in k-essence cosmology

Cosmological scenarios with k-essence are invoked in order to explain the observed late-time acceleration of the universe. These scenarios avoid the need for fine-tuned initial conditions (the "coincidence problem") because of the attractor-like dynamics of the k-essence field φ. It was recently shown that all k-essence scenarios with Lagrangians p=L(X)/φ^2, necessarily involve an epoch where perturbations of φpropagate faster than light (the "no-go theorem"). We carry out a comprehensive study of attractor-like cosmological solutions ("trackers") involving a k-essence scalar field φand another matter component. The result of this study is a complete classification of k-essence Lagrangians that admit asymptotically stable tracking solutions, among all Lagrangians of the form p=K(φ)L(X) . Using this classification, we select the class of models that describe the late-time acceleration and avoid the coincidence problem through the tracking mechanism. An analogous "no-go theorem" still holds for this class of models, indicating the existence of a superluminal epoch. In the context of k-essence cosmology, the superluminal epoch does not lead to causality violations. We discuss the implications of superluminal signal propagation for possible causality violations in Lorentz-invariant field theories.

A far-infrared Fourier transform spectrometer with an antenna-coupled niobium bolometer

The Anti-Apoptotic Protein PEA-15 Is a Tight Binding Inhibitor of ERK1 and ERK2, Which Blocks Docking Interactions at the D-Recruitment Site

Expanding the Repertoire of an ERK2 Recruitment Site: Cysteine Footprinting Identifies the D-Recruitment Site as a Mediator of Ets-1 Binding

A monadic, functional implementation of real numbers

Introduction to Quantum Effects in Gravity (book)