bluuebunny/crossref_metadata_2025 huggingface dataset:
Compilation of wind data for the Upper Atmosphere Research Satellite (UARS) Reference Atmosphere Project
Authors: Swinbank R. , Ortland D. A.
Published: October 2003

The aim of the UARS (Upper Atmosphere Research Satellite) Reference Atmosphere Project (URAP) is to provide a comprehensive zonal mean reference description of the stratosphere using measurements from instruments on board the UARS. A data set has been produced which describes the monthly zonal mean zonal winds from the surface to the upper mesosphere. Wind measurements from the High Resolution Doppler Imager (HRDI) were combined with results from the Met Office stratospheric data assimilation system. Balanced winds derived from the URAP temperature data set were used to bridge the gap between the stratospheric winds and HRDI mesospheric winds.
Fault creep and microseismicity on the Hayward fault, California: Implications for asperity size
Authors: Gans Christine R. , Furlong Kevin P. , Malservisi Rocco
Published: October 2003

The Hayward fault is documented to undergo significant creep, with some patches accommodating 50% or more of the long‐term fault displacement. In spite of this, the fault has also experienced moderate to large earthquakes. By comparing the patterns of microseismicity observed on the fault with models of fault zone creep, we can investigate the long‐term displacement/deformation history of the fault in terms of the relative roles of aseismic creep, fault slip accommodated through microseismicity, and strain accumulation (slip deficit). We find that microseismicity on the Hayward fault produces a negligible percentage of the seismic moment dissipated on the fault. Combining seismicity with our fault creep models allows us to calculate the size of asperities on the creeping fault. For small asperities associated with repeating earthquakes on the Hayward fault, the rupture areas of these asperities range from 20 to 60 m2.
Local-pooled-error test for identifying differentially expressed genes with a small number of replicated microarrays
Authors: Jain Nitin , Thatte Jayant , Braciale Thomas , Ley Klaus , O'Connell Michael , Lee Jae K.
Published: October 2003

Motivation: In microarray studies gene discovery based on fold-change values is often misleading because error variability for each gene is heterogeneous under different biological conditions and intensity ranges. Several statistical testing methods for differential gene expression have been suggested, but some of these approaches are underpowered and result in high false positive rates because within-gene variance estimates are based on a small number of replicated arrays.

Results: We propose to use local-pooled-error (LPE) estimates and robust statistical tests for evaluating significance of each gene's differential expression. Our LPE estimation is based on pooling errors within genes and between replicate arrays for genes in which expression values are similar. We have applied our LPE method to compare gene expression in naïve and activated CD8+ T-cells. Our results show that the LPE method effectively identifies significant differential-expression patterns with a small number of replicated arrays.

Availability: The methodology is implemented with S-PLUS and R functions available at http://hesweb1.med.virginia.edu/bioinformatics
Phosphadioxirane: A Peroxide from an Ortho-Substituted Arylphosphine and Singlet Dioxygen
Authors: Ho David G. , Gao Ruomei , Celaje Jeff , Chung Ha-Yong , Selke Matthias
Published: October 2003

We prepared the primary adduct for the reaction of singlet dioxygen (
1
O
2
) with an arylphosphine by using the sterically hindered arylphosphine tris(
o
-methoxyphenyl)phosphine. The resulting phosphadioxirane has a dioxygen molecule triangularly bound to the phosphorus atom. Olefin trapping experiments show that the phosphadioxirane can undergo nonradical oxygen atom–transfer reactions. Under protic conditions, two different intermediates are formed during the reaction of singlet dioxygen with tris(
o
-methoxyphenyl)phosphine, namely, the corresponding hydroperoxy arylphosphine and a hydroxy phosphorane. Experiments with other arylphosphines possessing different electronic and steric properties demonstrate that the relative stability of the tris(
o
-methoxyphenyl)phosphadioxirane is due to both steric and electronic effects.
Reflections on Lizard Diversity
Authors: Whiting Martin J.
Published: October 2003

Lizards
Windows to the Evolution of Diversity. by Eric R.Pianka and Laurie J. Vitt. University of California Press, Berkeley, 2003. 347 pp. $45, £29.95. ISBN 0-520-23401-4. Organisms and the Environment.

Pianka and Vitt's comprehensive introduction to the diversity of lizards highlights the reptiles' adaptations and their potential as model organisms for evolutionary and ecological studies.
The Lognormal-Like Distributions in the Linear Growth Equations
Authors: Pang Ning-Ning , Tzeng Wen-Jer
Published: October 2003

The distributions of the global interfacial widths, correlation functions, and the local interfacial widths of the growth process described by the one-dimensional Edward-Wilkinson equation are shown to be denumerable convolutions of exponential distributions. The same conclusions can also be extended to the distributions of the global interfacial widths for another linear growth equation, describing some super-rough growth processes, in both one- and two-dimensional cases. Most of these distributions display the lognormal-like behavior. We propose that the mechanism provided by the accumulation of exponential random variables may contribute to a lot of the lognormal-like behavior observed in the social and natural sciences.
Iterated Function System and Multifractal Analysis of Biological Sequences
Authors: Yu Zu-Guo , Anh Vo , Lau Ka-Sing
Published: October 2003

The fractal method has been successfully used to study many problems in physics, mathematics, engineering, finance, even in biology till now. In the past decade or so there has been a ground swell of interest in unravelling the mysteries of DNA. How to get more bioinformations from these DNA sequences is a challenging problem. The problem of classification and evolution relationship of organisms are the central problems in bioinformatics. And it is also very hard to predict the secondary and space structure of a protein from its amino acid sequence. In this paper, some recent results related these problems obtained through multifractal analysis and iterated function system (IFS) model are introduced.
AC Driven Directed Motion of Solitary Waves
Authors: Zolotaryuk Yaroslav , Christiansen Peter L. , Salerno Mario
Published: October 2003

We study the possibility of unidirectional motion of a topological soliton of a dissipative (continuous and discrete) Klein-Gordon equation driven by AC forces with certain broken symmetries and with zero mean. The role played by the temporal asymmetry of the system in establishing soliton DC motions which resemble usual soliton ratchets is emphasized. The dependence of the soliton velocity on the system parameters is studied.
Stability Analysis of a Nonlinear Plate in Mean Flow
Authors: Wu Sean F. , Zhu Jinshuo
Published: October 2003

A stability analysis of a nonlinear plate clamped to an infinite baffle in mean flow is given. The effect of structural nonlinearities induced by in-plane forces and shearing forces due to stretching of plate bending motion, and that of viscous damping are taken into account in the derivation of the plate equation. The plate flexural displacement is obtained by modal expansion based on Galerkin's method. The critical mean flow speeds at which local instabilities may occur are determined by Routh algorithm. The mechanisms that trigger the local instabilities are uncovered. The effect of structural nonlinearities, and that of plate aspect and plate length/thickness ratios on local instabilities are examined. Numerical examples of the transition from stable to locally unstable vibration, as the mean flow speed exceeds the critical values, are demonstrated. The results show that while the overall amplitude of the plate flexural displacement may be bounded when the mean flow speed exceeds the critical values, plate vibration may be locally unstable, jumping from one equilibrium position to another. Furthermore, the jumping may be random, and the plate vibration may seem chaotic. The results also show that viscous damping may stabilize plate flexural vibration and settle the plate in one of its equilibria.
Numerical Computations of Elastic Wave Equations
Authors: Lee Ding , Nagem Raymond J. , Resasco Diana C.
Published: October 2003

An improved numerical scheme is introduced for solving a set of three-dimensional parabolic elastic wave equations. The new scheme is based on the combination of an ordinary differential equation method and a finite difference scheme. A stability analysis of the numerical method is presented along with a numerical example in which computational accuracy is verified by comparison with an exact three-dimensional analytic solution.
On Boundary Conditions for Acoustic Computations in Non-Uniform Mean Flows
Authors: Dong Thomas Z.
Published: October 2003

Many acoustic problems involve acoustic wave radiation to the exterior field. A common approach in numerical simulations is to restrict the computational domain to a finite region with artificial boundaries. The so-called radiation or non-reflecting boundary conditions must be imposed at those artificial boundaries. Most existing non-reflecting boundary conditions are derived for computing disturbances propagating in a known uniform mean flow near the boundaries. In many applications such as the computation of jet noise or turbofan noise, the mean flow at an artificial boundary is non-uniform and unknown. The mean flow also needs to be computed in these cases. Incorrect computation of this mean flow at the boundary could directly affect the near field physics as well as the far field acoustics. In the present paper, a set of boundary conditions is proposed which focuses on computing the correct mean solution at an artificial boundary, while still maintaining the non-reflecting feature for the outgoing transient and acoustic waves.
Synchronization Phenomena in an Array of Population Dynamic Systems
Authors: Postnov D. E. , Balanov A. G. , Mosekilde E.
Published: October 2003

The paper applies continuation methods to examine fundFigureamental features of the complex dynamics that can arise in a cascaded system of population dynamic models. The individual model describes a bacterial population interacting with a population of viruses that attack the cells and exploit their reproductive system for their own replication. Coupling between the subsystems is brought about through a unidirectional flow of primary resources. In this way the individual subsystem is modulated by the varying nutrient concentration in the overflow from the upstream habitat.

Synchronization of a single subsystem to an external periodic forcing exhibits an unusual bifurcation structure with global bifurcations appearing already at the lowest forcing amplitudes. This peculiarity is also observed for autonomous systems of two and three coupled habitats. Finally, local and global synchronization phenomena are investigated for a chain of 20 coupled population pools.
Adaptive Agent-Driven Routing and Load Balancing in Communication Networks
Authors: Heusse Martin , Snyers Dominique , Guérin Sylvain , Kuntz Pascale
Published: October 2003

This paper presents an unified overview of a new family of distributed algortithms for routing and load balancing in dynamic communication networks. These new algorithms are described as an extension to the classical routing algorithms: they combine the ideas of online asynchronous distance vector routing with adaptive link state routing. Estimates of the current traffic condition and link costs are measured by sending routing agents in the network that mix with the regular information packets and keep track of the costs (e.g. delay) encountered during their journey. The routing tables are then regularly updated based on that information without any central control nor complete knowledge of the network topology. Two new algorithms are proposed here. The first one is based on round trip routing agents that update the routing tables by backtracking their way after having reached the destination. The second one relies on forward agents that update the routing tables directly as they move toward their destination. An efficient co-operative scheme is proposed to deal with asymmetric connections. All these methods are compared on a simulated network with various traffic loads; the robustness of the new algorithms to network changes is proved on various dynamic scenarii.
Long-Range Correlations in the Fossil Record and the Fractal Nature of Macroevolution
Authors: Solé Richard V. , Manrubia Susanna C. , Pérez-Mercader Juan , Benton Michael , Bak Per
Published: October 2003

Recent studies on the fossil record time series has suggested that there is consistent evidence for self-similarity i.e. long-range correlations with power-law behavior. The existence of such fractal strucutes means that, when looking at a given time frame, some basic properties remain the same if a change of scale is performed. In other words, there is no characteristic time scale, as we could expect if some type of periodic or other low-dimensional dynamics were present. A possible explanation for such long-range order is a dynamical process operating at all scales, as it is the case for systems in the neighborhood of critical points. In this paper these results are further explored by extending previous data analysis and examining the relevance of recent theoretical approaches to the statistical features of the fossil record. The presence of long-range correlations is shown through Hurst analysis using non-interpolated data series from the Fossil Record 2 database. As shown in previous studies, such correlations span over hundreds of millions of years and are compared with a simple model of large-scale evolution displaying self-organized criticality.
The performance of difference coding for sets and relational tables
Authors: Wu Wei Biao , Ravishankar Chinya V.
Published: October 2003

We characterize the performance of difference coding for compressing sets and database relations through an analysis of the problem of estimating the number of bits needed for storing the spacings between values in sets of integers. We provide analytical expressions for estimating the effectiveness of difference coding when the elements of the sets or the attribute fields in database tuples are drawn from the uniform and Zipf distributions. We also examine the case where a uniformly distributed domain is combined with a Zipf distribution, and with an arbitrary distribution. We present limit theorems for most cases, and probabilistic convergence results in other cases. We also examine the effects of attribute domain reordering on the compression ratio. Our simulations show excellent agreement with theory.
Counterexample-guided abstraction refinement for symbolic model checking
Authors: Clarke Edmund , Grumberg Orna , Jha Somesh , Lu Yuan , Veith Helmut
Published: October 2003

The state explosion problem remains a major hurdle in applying symbolic model checking to large hardware designs. State space abstraction, having been essential for verifying designs of industrial complexity, is typically a manual process, requiring considerable creativity and insight.In this article, we present an automatic iterative abstraction-refinement methodology that extends symbolic model checking. In our method, the initial abstract model is generated by an automatic analysis of the control structures in the program to be verified. Abstract models may admit erroneous (or "spurious") counterexamples. We devise new symbolic techniques that analyze such counterexamples and refine the abstract model correspondingly. We describe aSMV, a prototype implementation of our methodology in NuSMV. Practical experiments including a large Fujitsu IP core design with about 500 latches and 10000 lines of SMV code confirm the effectiveness of our approach.
Wang Tiles for image and texture generation
Authors: Cohen Michael F. , Shade Jonathan , Hiller Stefan , Deussen Oliver
Published: October 2003

We present a simple stochastic system for non-periodically tiling the plane with a small set of Wang Tiles. The tiles may be filled with texture, patterns, or geometry that when assembled create a continuous representation. The primary advantage of using Wang Tiles is that once the tiles are filled, large expanses of non-periodic texture (or patterns or geometry) can be created as needed very efficiently at runtime.Wang Tiles are squares in which each edge is assigned a color. A valid tiling requires all shared edges between tiles to have matching colors. We present a new stochastic algorithm to non-periodically tile the plane with a small set of Wang Tiles at runtime.Furthermore, we present new methods to fill the tiles with 2D texture, 2D Poisson distributions, or 3D geometry to efficiently create at runtime as much non-periodic texture (or distributions, or geometry) as needed. We leverage previous texture synthesis work and adapt it to fill Wang Tiles. We demonstrate how to fill individual tiles with Poisson distributions that maintain their statistical properties when combined. These are used to generate a large arrangement of plants or other objects on a terrain. We show how such environments can be rendered efficiently by pre-lighting the individual Wang Tiles containing the geometry.We also extend the definition of Wang Tiles to include a coding of the tile corners to allow discrete objects to overlap more than one edge. The larger set of tiles provides increased degrees of freedom.
Matchmaker
Authors: Kraevoy Vladislav , Sheffer Alla , Gotsman Craig
Published: October 2003

Texture mapping enhances the visual realism of 3D models by adding fine details. To achieve the best results, it is often necessary to force a correspondence between some of the details of the texture and the features of the model.The most common method for mapping texture onto 3D meshes is to use a planar parameterization of the mesh. This, however, does not reflect any special correspondence between the mesh geometry and the texture. The
Matchmaker
algorithm presented here forces user-defined feature correspondence for planar parameterization of meshes. This is achieved by adding positional constraints to the planar parameterization.
Matchmaker
allows users to introduce scores of constraints while maintaining a valid one-to-one mapping between the embedding and the 3D surface.
Matchmaker
's constraint mechanism can be used for other applications requiring parameterization besides texture mapping, such as morphing and remeshing.
Matchmaker
begins with an unconstrained planar embedding of the 3D mesh generated by conventional methods. It moves the constrained vertices to the required positions by matching a triangulation of these positions to a triangulation of the planar mesh formed by paths between constrained vertices. The matching triangulations are used to generate a new parameterization that satisfies the constraints while minimizing the deviation from the original 3D geometry.
Improving mid-tone quality of variable-coefficient error diffusion using threshold modulation
Authors: Zhou Bingfeng , Fang Xifeng
Published: October 2003

In this paper, we describe the use of threshold modulation to remove the visual artifacts contained in the variable-coefficient error-diffusion algorithm. To obtain a suitable parameter set for the threshold modulation, a cost function used for the search of optimal parameters is designed. An optimal diffusion parameter set, as well as the corresponding threshold modulation strength values, is thus obtained. Experiments over this new set of parameters show that, compared with the original variable-coefficient error-diffusion algorithm, threshold modulation can remove visual anomalies more effectively. The result of the new algorithm is an artifact-free halftoning in the full range of intensities. Fourier analysis of the experimental results further support this conclusion.
TreeJuxtaposer
Authors: Munzner Tamara , Guimbretière François , Tasiran Serdar , Zhang Li , Zhou Yunhong
Published: October 2003

Structural comparison of large trees is a difficult task that is only partially supported by current visualization techniques, which are mainly designed for browsing. We present TreeJuxtaposer, a system designed to support the comparison task for large trees of several hundred thousand nodes. We introduce the idea of "guaranteed visibility", where highlighted areas are treated as landmarks that must remain visually apparent at all times. We propose a new methodology for detailed structural comparison between two trees and provide a new nearly-linear algorithm for computing the best corresponding node from one tree to another. In addition, we present a new rectilinear Focus+Context technique for navigation that is well suited to the dynamic linking of side-by-side views while guaranteeing landmark visibility and constant frame rates. These three contributions result in a system delivering a fluid exploration experience that scales both in the size of the dataset and the number of pixels in the display. We have based the design decisions for our system on the needs of a target audience of biologists who must understand the structural details of many phylogenetic, or evolutionary, trees. Our tool is also useful in many other application domains where tree comparison is needed, ranging from network management to call graph optimization to genealogy.
Perceptual metrics for character animation
Authors: Reitsma Paul S. A. , Pollard Nancy S.
Published: October 2003

Motion capture data and techniques for blending, editing, and sequencing that data can produce rich, realistic character animation; however, the output of these motion processing techniques sometimes appears unnatural. For example, the motion may violate physical laws or reflect unreasonable forces from the character or the environment. While problems such as these can be fixed, doing so is not yet feasible in real time environments. We are interested in developing ways to estimate perceived error in animated human motion so that the output quality of motion processing techniques can be better controlled to meet user goals.This paper presents results of a study of user sensitivity to errors in animated human motion. Errors were systematically added to human jumping motion, and the ability of subjects to detect these errors was measured. We found that users were able to detect motion with errors, and noted some interesting trends: errors in horizontal velocity were easier to detect than errors in vertical velocity, and added accelerations were easier to detect than added decelerations. On the basis of our results, we propose a perceptually based metric for measuring errors in ballistic human motion.
Reanimating the dead
Authors: Kähler Kolja , Haber Jörg , Seidel Hans-Peter
Published: October 2003

Facial reconstruction for postmortem identification of humans from their skeletal remains is a challenging and fascinating part of forensic art. The former look of a face can be approximated by predicting and modeling the layers of tissue on the skull. This work is as of today carried out solely by physical sculpting with clay, where experienced artists invest up to hundreds of hours to craft a reconstructed face model. Remarkably, one of the most popular tissue reconstruction methods bears many resemblances with surface fitting techniques used in computer graphics, thus suggesting the possibility of a transfer of the manual approach to the computer. In this paper, we present a facial reconstruction approach that fits an anatomy-based virtual head model, incorporating skin and muscles, to a scanned skull using statistical data on skull / tissue relationships. The approach has many advantages over the traditional process: a reconstruction can be completed in about an hour from acquired skull data; also, variations such as a slender or a more obese build of the modeled individual are easily created. Last not least, by matching not only skin geometry but also virtual muscle layers, an animatable head model is generated that can be used to form facial expressions beyond the neutral face typically used in physical reconstructions.
Combining edges and points for interactive high-quality rendering
Authors: Bala Kavita , Walter Bruce , Greenberg Donald P.
Published: October 2003

This paper presents a new interactive rendering and display technique for complex scenes with expensive shading, such as global illumination. Our approach combines sparsely sampled shading (points) and analytically computed discontinuities (edges) to interactively generate high-quality images. The
edge-and-point
image is a new compact representation that combines edges and points such that fast, table-driven interpolation of pixel shading from nearby point samples is possible, while respecting discontinuities.The edge-and-point renderer is extensible, permitting the use of arbitrary shaders to collect shading samples. Shading discontinuities, such as silhouettes and shadow edges, are found at interactive rates. Our software implementation supports interactive navigation and object manipulation in scenes that include expensive lighting effects (such as global illumination) and geometrically complex objects. For interactive rendering we show that high-quality images of these scenes can be rendered at 8--14 frames per second on a desktop PC: a speedup of 20--60 over a ray tracer computing a single sample per pixel.
Instant architecture
Authors: Wonka Peter , Wimmer Michael , Sillion François , Ribarsky William
Published: October 2003

This paper presents a new method for the automatic modeling of architecture. Building designs are derived using split grammars, a new type of parametric set grammar based on the concept of shape. The paper also introduces an attribute matching system and a separate control grammar, which offer the flexibility required to model buildings using a large variety of different styles and design ideas. Through the adaptive nature of the design grammar used, the created building designs can either be generic or adhere closely to a specified goal, depending on the amount of data available.
Linear light source reflectometry
Authors: Gardner Andrew , Tchou Chris , Hawkins Tim , Debevec Paul
Published: October 2003

This paper presents a technique for estimating the spatially-varying reflectance properties of a surface based on its appearance during a single pass of a linear light source. By using a linear light rather than a point light source as the illuminant, we are able to reliably observe and estimate the diffuse color, specular color, and specular roughness of each point of the surface. The reflectometry apparatus we use is simple and inexpensive to build, requiring a single direction of motion for the light source and a fixed camera viewpoint. Our model fitting technique first renders a reflectance table of how diffuse and specular reflectance lobes would appear under moving linear light source illumination. Then, for each pixel we compare its series of intensity values to the tabulated reflectance lobes to determine which reflectance model parameters most closely produce the observed reflectance values. Using two passes of the linear light source at different angles, we can also estimate per-pixel surface normals as well as the reflectance parameters. Additionally our system records a per-pixel height map for the object and estimates its per-pixel translucency. We produce real-time renderings of the captured objects using a custom hardware shading algorithm. We apply the technique to a test object exhibiting a variety of materials as well as to an illuminated manuscript with gold lettering. To demonstrate the technique's accuracy, we compare renderings of the captured models to real photographs of the original objects.
Out-of-core compression for gigantic polygon meshes
Authors: Isenburg Martin , Gumhold Stefan
Published: October 2003

Polygonal models acquired with emerging 3D scanning technology or from large scale CAD applications easily reach sizes of several gigabytes and do not fit in the address space of common 32-bit desktop PCs. In this paper we propose an out-of-core mesh compression technique that converts such gigantic meshes into a streamable, highly compressed representation. During decompression only a small portion of the mesh needs to be kept in memory at any time. As full connectivity information is available along the decompression boundaries, this provides seamless mesh access for incremental in-core processing on gigantic meshes. Decompression speeds are CPU-limited and exceed one million vertices and two million triangles per second on a 1.8 GHz Athlon processor.A novel external memory data structure provides our compression engine with transparent access to arbitrary large meshes. This out-of-core mesh was designed to accommodate the access pattern of our region-growing based compressor, which - in return - performs mesh queries as seldom and as local as possible by remembering previous queries as long as needed and by adapting its traversal slightly. The achieved compression rates are state-of-the-art.
Hierarchical mesh decomposition using fuzzy clustering and cuts
Authors: Katz Sagi , Tal Ayellet
Published: October 2003

Cutting up a complex object into simpler sub-objects is a fundamental problem in various disciplines. In image processing, images are segmented while in computational geometry, solid polyhedra are decomposed. In recent years, in computer graphics, polygonal meshes are decomposed into sub-meshes. In this paper we propose a novel hierarchical mesh decomposition algorithm. Our algorithm computes a decomposition into the
meaningful components
of a given mesh, which generally refers to segmentation at regions of deep concavities. The algorithm also avoids over-segmentation and jaggy boundaries between the components. Finally, we demonstrate the utility of the algorithm in control-skeleton extraction.
Usability engineers
Authors: Downey Laura L.
Published: October 2003

Ever been expected to cover too many bases as a usability engineer? Ever had your management expect you to possess skills in way more areas than you thought was reasonable? Laura Downey illustrates the predicament with a lively tale of a girl called SUE (Super Usability Engineer).
---Elizabeth Buie
The elements of user experience
Authors: Deaton Mary
Published: October 2003

The Elements of User Experience: User-Centered Design for the Web

Jesse James Garrett

New Riders, 2003 ISBN 0735712026 $29.99
The future of peer-to-peer computing
Authors: Loo Alfred W.
Published: October 2003

An economical method for pumping up computing power by tapping into P2P systems using Web server technologies.
Open courseware and open source software
Authors: Baldi Stefan , Heier Hauke , Mehler-Bicher Anett
Published: October 2003

Learning from experience?
Policy management using access control spaces
Authors: Jaeger Trent , Zhang Xiaolan , Edwards Antony
Published: October 2003

We present the concept of an
access control space
and investigate how it may be useful in managing access control policies. An access control space represents the permission assignment state of a subject or role. For example, the set of permissions explicitly assigned to a role defines its
specified
subspace, and the set of constraints precluding assignment to that role defines its
prohibited
subspace. In analyzing these subspaces, we identify two problems: (1) often a significant portion of an access control space has unknown assignment semantics, which indicates that the policy is underspecified; and (2) often high-level assignments and constraints that are easily understood result in conflicts, where resolution often leads to significantly more complex specifications. We have developed a prototype system, called Gokyo, that computes access control spaces. Gokyo identifies the unknown subspace to assist system administrators in developing more complete policy specifications. Also, Gokyo identifies conflicting subspaces and enables system administrators to resolve conflicts in a variety of ways in order to preserve the simplicity of constraint specification. We demonstrate Gokyo by analyzing a Web server policy example and examine its utility by applying it to the SELinux example policy. Even for the extensive SELinux example policy, we find that only eight additional expressions are necessary to resolve Apache administrator policy conflicts.
Variable independence for first-order definable constraints
Authors: Libkin Leonid
Published: October 2003

Whenever we have data represented by constraints (such as order, linear, polynomial, etc.), running time for many constraint processing algorithms can be considerably lowered if it is known that certain variables in those constraints are independent of each other. For example, when one deals with spatial and temporal databases given by constraints, the projection operation, which corresponds to quantifier elimination, is usually the costliest. Since the behavior of many quantifier elimination algorithms becomes worse as the dimension increases, eliminating certain variables from consideration helps speed up those algorithms.While these observations have been made in the literature, it remained unknown when the problem of testing if certain variables are independent is decidable, and how to efficiently construct a new representation of a constraint-set in which those variables do not appear together in the same atomic constraints. Here we answer this question. We first consider a general condition that gives us decidability of variable independence; this condition is stated in terms of model-theoretic properties of the structures corresponding to constraint classes. We then show that this condition covers the domains most relevant to spatial and temporal applications. For some of these domains, including linear and polynomial constraints over the reals, we provide a uniform decision procedure that gives us tractability as well. For those constraints, we also present a polynomial-time algorithm for producing nice constraint representations.
Static analysis to support the evolution of exception structure in object-oriented systems
Authors: Robillard Martin P. , Murphy Gail C.
Published: October 2003

Exception-handling mechanisms in modern programming languages provide a means to help software developers build robust applications by separating the normal control flow of a program from the control flow of the program under exceptional situations. Separating the exceptional structure from the code associated with normal operations bears some consequences. One consequence is that developers wishing to improve the robustness of a program must figure out which exceptions, if any, can flow to a point in the program. Unfortunately, in large programs, this exceptional control flow can be difficult, if not impossible, to determine.In this article, we present a model that encapsulates the minimal concepts necessary for a developer to determine exception flow for object-oriented languages that define exceptions as objects. Using these concepts, we describe why exception-flow information is needed to build and evolve robust programs. We then describe Jex, a static analysis tool we have developed to provide exception-flow information for Java systems based on this model. The Jex tool provides a view of the actual exception types that might arise at different program points and of the handlers that are present. Use of this tool on a collection of Java library and application source code demonstrates that the approach can be helpful to support both local and global improvements to the exception-handling structure of a system.
MEGA---the maximizing expected generalization algorithm for learning complex query concepts
Authors: Chang Edward , Li Beitao
Published: October 2003

Specifying exact query concepts has become increasingly challenging to end-users. This is because many query concepts (e.g., those for looking up a multimedia object) can be hard to articulate, and articulation can be subjective. In this study, we propose a query-concept learner that learns query criteria through an intelligent sampling process. Our concept learner aims to fulfill two primary design objectives: (1) it has to be expressive in order to model most practical query concepts and (2) it must learn a concept quickly and with a small number of labeled data since online users tend to be too impatient to provide much feedback. To fulfill the first goal, we model query concepts in
k
-CNF, which can express almost all practical query concepts. To fulfill the second design goal, we propose our
maximizing expected generalization algorithm
(MEGA), which converges to target concepts quickly by its two complementary steps: sample selection and concept refinement. We also propose a divide-and-conquer method that divides the concept-learning task into
G
subtasks to achieve speedup. We notice that a task must be divided carefully, or search accuracy may suffer. Through analysis and mining results, we observe that organizing image features in a multiresolution manner, and minimizing intragroup feature correlation, can speed up query-concept learning substantially while maintaining high search accuracy. Through examples, analysis, experiments, and a prototype implementation, we show that MEGA converges to query concepts significantly faster than traditional methods.
On test data volume reduction for multiple scan chain designs
Authors: Reddy Sudhakar M. , Miyase Kohei , Kajihara Seiji , Pomeranz Irith
Published: October 2003

We consider issues related to the reduction of scan test data in designs with multiple scan chains. We propose a metric that can be used to evaluate the effectiveness of procedures for reducing the scan data volume. The metric compares the achieved compression to the compression which is intrinsic to the use of multiple scan chains. We also propose a procedure for modifying a given test set so as to achieve reductions in test data volume assuming a combinational decompressor circuit.
Test data compression using dictionaries with selective entries and fixed-length indices
Authors: Li Lei , Chakrabarty Krishnendu , Touba Nur A.
Published: October 2003

We present a dictionary-based test data compression approach for reducing test data volume in SOCs. The proposed method is based on the use of a small number of ATE channels to deliver compressed test patterns from the tester to the chip and to drive a large number of internal scan chains in the circuit under test. Therefore, it is especially suitable for a reduced pin-count and low-cost DFT test environment, where a narrow interface between the tester and the SOC is desirable. The dictionary-based approach not only reduces test data volume but it also eliminates the need for additional synchronization and handshaking between the SOC and the ATE. The dictionary entries are determined during the compression procedure by solving a variant of the well-known clique partitioning problem from graph theory. Experimental results for the ISCAS-89 benchmarks and representative test data from IBM show that the proposed method outperforms a number of recently-proposed test data compression techniques. Compared to the previously proposed test data compression approach based on selective Huffman coding with variable-length indices, the proposed approach generally provides higher compression for the same amount of hardware overhead.
A circuit level fault model for resistive bridges
Authors: Li Zhuo , Lu Xiang , Qiu Wangqi , Shi Weiping , Walker D. M. H.
Published: October 2003

Delay faults are an increasingly important test challenge. Modeling bridge faults as delay faults helps delay tests to detect more bridge faults. Traditional bridge fault models are incomplete because these models only model the logic faults or these models are not efficient to use in delay tests for large circuits. In this article, we propose a physically realistic yet economical resistive bridge fault model to model delay faults as well as logic faults. An accurate yet simple delay calculation method is proposed. We also enumerate all possible fault behaviors and present the relationship between input patterns and output behaviors, which is useful in ATPG. Our fault simulation results show the benefit of at-speed tests.
Objective quality ranking of computing journals
Authors: Katerattanakul Pairin , Han Bernard , Hong Soongoo
Published: October 2003

Citation analysis, which provides a clear picture of actual use of journals and their articles, is an effective way to determine a journal's influence.
Web service componentization
Authors: Yang Jian
Published: October 2003

Developing a framework for analyzing service composition reuse and specialization.
Song as a signal to negotiate a sexual conflict?
Authors: Verhulst Simon
Published: October 2003

Sexual conflict occurs when the optimal solution regarding e.g. a life history trait differs between co-operating individuals of different sex. When deciding a conflict is not instantaneous, some form of negotiation can be expected to evolve. In great tits, Parus major, a sexual conflict exists over the number of clutches that are reared, because the fitness costs of a second clutch are greater for females. A conflict is also likely to exist over investment in the first brood - each parent benefiting from a greater investment by the partner. Male great tits sing when rearing the first brood, and if acoustic signals play a role in the negotiation of a sexual conflict, a positive association between male song rate and maternal investment is predicted. In agreement with this hypothesis, maternal effort (in kJ/day) relative to paternal effort was positively correlated with male song rate. Furthermore, females were more likely to start a second clutch when their male had a high song rate, and high song rate was associated with shorter inter-clutch intervals. Song rate was higher when brood size was experimentally reduced and, independent of brood size manipulation, males with high song rate produced higher quality fledglings. These results indicate that song rate reflects the males' state, suggesting it may function as a handicap signal. Although song rate seems too low (<4% of time) for honesty to be maintained by production costs alone, signalling costs may be amplified by the fact that song appears restricted to the time when the male and female are both near the nest. To achieve a high song rate, the male may have to spend a large amount of time near the nest, thereby seriously restricting time available for other activities.
Gender, Age, and Crime/Deviance: A Challenge to Self-Control Theory
Authors: Tittle Charles R. , Ward David A. , Grasmick Harold G.
Published: October 2003

Focusing on gender and age variations and using various measures of self-control and of crime/deviance, the authors' provide additional evidence concerning the strongest implications of self-control theory—that self-control interprets the main demo-graphic facts about crime/deviance and is of approximately equal import for all sub-categories of individuals. On one hand, the results are strongly supportive of the theory, showing that some measures of self-control not only predict misbehavior but they interpret the associations between gender and age and measures of crime/deviance. On the other hand, self-control does not appear to predict misbehavior equally well among various subcategories of individuals, particularly not for age groups, even failing to predict misbehavior at all for some groupings. Moreover, sup-port for the strongest claims of the theory are not robust, varying depending on how self-control and crime/deviance are measured.
Replicating Sampson and Groves's Test of Social Disorganization Theory: Revisiting a Criminological Classic
Authors: Lowenkamp Christopher T. , Cullen Francis T. , Pratt Travis C.
Published: October 2003

Using data from the British Crime Survey conducted in 1982, Sampson and Groves provided a convincing test of social disorganization theory. Although macro-level theory was in the midst of a revival when this investigation appeared, no single article did more to polish the previously tarnished image of social disorganization theory than Sampson and Groves's analysis; in fact, this work has become a criminological classic. Subsequent research, however, has not systematically replicated this study. Questions thus remain as to whether Sampson and Groves uncovered enduring empirical realities or idiosyncratic relationships reflecting the time period from which the data were drawn. In this context, the current research seeks to replicate Sampson and Groves's findings with data from the 1994 British Crime Survey. Analyses of similar models with similar measures yield results consistent with social disorganization theory and consistent with the results presented by Sampson and Groves. Our study suggests, therefore, that the findings of the initial classic study were not artifactual but illuminated an underlying empirical pattern that has persisted over time.
New Directions in Social Disorganization Theory
Authors: Kubrin Charis E. , Weitzer Ronald
Published: October 2003

Social disorganization theory focuses on the relationship between neighborhood structure, social control, and crime. Recent theoretical and empirical work on the relationship between community characteristics and crime has led to important refinements of social disorganization theory, yet there remain some substantive and methodological deficiencies in this body of work. This article addresses these problems and charts some promising new directions in social disorganization theory.
Young and Elderly Type 2 Diabetic Patients Inhaling Insulin with the AERx® Insulin Diabetes Management System: A Pharmacokinetic and Pharmacodynamic Comparison
Authors: Henry Robert R. , Mudaliar Sunder , Chu Neelima , Kim Dennis , Armstrong Debra , Davis Trent T. , An Bob , Reinhardt Rickey R.
Published: October 2003

The objective of this study was to compare the pharmacokinetics (PK), pharmacodynamics (PD), and safety of inhaled insulin delivered by the AERx® iDMS in young and elderly patients with type 2 diabetes. Twenty‐seven young (18–45 years, inclusive) and 28 elderly ( 65 years) type 2 diabetic patients were enrolled in this study. A single inhalation of 1.57 mg (45 IU, effect comparable to 6 s.c. units) of regular human insulin was administered to each patient on each of 2 dosing days, and blood samples were drawn up to 360 minutes postdosing to generate the PK/PD curves. AUC (0–360 min) and Cmax values of inhaled insulin were comparable between young and elderly subjects (p = 0.476 for AUC(0–360 min) and p = 0.414 for Cmax). However, the elderly group had significantly less glucose reduction, as indicated by plasma glucose AOC(0–360) (area over the curve) values (p = 0.011). The intrasubject variability of inhaled insulin using the AERx® iDMS was similar for young and elderly subjects and was similar to what has previously been reported for soluble insulin administered subcutaneously. Inhaled insulin was well tolerated in these patients, and no changes in pulmonary function tests were observed. A single inhalation of insulin using the AERx® iDMS demonstrated comparable insulin PK profiles between the elderly and young type 2 patients but less glucose reduction in the elderly. Based on these results, elderly diabetic patients may need to inhale more insulin than young patients to achieve similar glycemic control. Long‐term clinical trials using the AERx® device will be useful to study age‐related differences.