bluuebunny/crossref_metadata_2025 huggingface dataset:
ROOM TEMPERATURE SILICON QUANTUM DEVICES
Authors: TSU RAPHAEL
Published: May 2003

Quantum mechanical devices utilize the wave nature of electrons for their operations whenever the electron mean-free-path exceeds the appropriate dimensions of the device structure. Some of the issues such as the tunneling time, the reduction of the dielectric constant and the drastic increase in the binding energy of dopants are discussed. Lacking an appropriate barrier for silicon, the majority of quantum devices are fabricated with compound semiconductors. In the past several years, certain schemes appeared, such as the resonant tunneling via nanoscale silicon particles imbedded in an oxide matrix, and the superlattice barrier for silicon consisting of several periods of Si/O. There appears some doubt about the tunneling nature of the former, and the possiblity of dielectric breakdowns. This article aims to show that dielectric breakdowns can occur under fabrication conditions without using a controlled forming process. The latter results in epitaxially grown silicon beyond the superlattice barrier region, free of stacking fault defects, and thus is potentially important for silicon based quantum devices as well as serving as an SOI (silicon on insulator), without ion-implantation damage and oxygen inclusion. The replacement of SOI by the epitaxially grown Si/O superlattice barrier should promote the effort in high speed and low power MOSFET devices.
SINGLE ELECTRON DEVICES
Authors: SMITH DORAN D.
Published: May 2003

In the mid 1980s Averin and Likharev predicted that with the use of ultrasmall tunnel junctions a time correlation of electron flow through a junction could be observed, and permit the measurement of the effect of a net charge of less than one electron on the junction. Both effects were soon experimentally verified, and since that time there has been an explosion of work in the filed of single electron devices. This chapter reviews the fundamental concepts behind the operation of such devices. it then describes some of the single electron effects studied in semiconductors. Superconducting devices are then constrasted to the semiconductor and the normal metal single electron devices. The details of some current applications are described, and a thumbnail sketch of current fabrication methods is given.
BLOCH ELECTRON DYNAMICS IN SPATIALLY HOMOGENEOUS ELECTRIC FIELDS
Authors: IAFRATE G. J. , REYNOLDS J. P. , HE J. , KRIEGER J. B.
Published: May 2003

The theory of Bloch electron dynamics in spatially homogeneous electric fields of arbitrary strength and time dependence is presented. In the formalism, the electric field is described through the use of the vector potential, and the instantaneous eigenstates of the Hamiltonian are used as basis stated to depict the Bloch dynamics and quantum properties. This approach leads to a natural indication of high- and low-filed limits, and allows for the inclusion of general band-structure effects and multiband coupling in the quantum dynamics. A variety of dc electric field effects, such as Bloch oscillations, Zener tunneling, and localization, and ac electric field effects, such as interband absorption, and phonon-assisted transport, will be discussed.
SCHRÖDINGER EQUATION MONTE CARLO: BRIDGING THE GAP FROM QUANTUM TO CLASSICAL TRANSPORT
Authors: REGISTER LEONARD F.
Published: May 2003

Schrödinger Equation and (based) Monte Carlo (SEMC), a simulation method designed to bridge the gap from quantum to classical transport, is described. This method provides a non-perturbative, current conserving quantum mechanical treatment of carriers, phonons, and their coupling, yet the SEMC algorithm is analogous to and compatible with that of semiclassical Monte Carlo (SMC). Indeed, SEMC allows carriers to be followed through a sequence of stochastically sampled scattering events. Phase breaking and energy dissipation for charge carriers within the Schrödinger-equation-based method are modeled via the exchange of probability among oscillator degrees of freedom, mimicing the true process of carrier-phonon scattering. Carrier-phonon coupling potentials for SEMC are obtained by Monte Carlo sampling of (the spatial correlation functions of) the true carrier-phonon coupling potentials. Illustrative results demonstrate SEMC's ability to provide both physically and quantitatively accurate modeling of, in particular, long-range polar-optical scattering, and to completely bridge the gap between phase-coherent and phase-incoherent transport.
RECENT DEVELOPMENTS ON ELECTRON-PHONON INTERACTIONS IN STRUCTURES FOR ELECTRONIC AND OPTOELECTRONIC DEVICES
Authors: DUTTA M. , STROSCIO M. A. , KIM K. W.
Published: May 2003

As device dimensions in electronic and optoelectronic devices are reduced, the characteristics and interactions of dimensionally-confined longitudinal-optical (LO) and acoustic phonons deviate substantially from those of bulk semiconductors. Furthermore, as würtzite materials are applied increasingly in electronic and optoelectronic devices it becomes more important to understand the phonon modes in such systems. This account emphasizes the properties of bulk optical phonons in würtzite structures, the properties of LO-phonon modes and acoustic-phonon modes arising in polar-semiconductor quantum wells, superlattices, quantum wires and quantum dots, with a variety of cross sectional geometries and, lastly, the properties of optical phonons in würtzite materials as predicted by the dielectric continuum model. Emphasis is placed on the dielectric continuum and elastic continuum models of bulk, confined and interface phonons. This article emphasizes device applications of confined phonons in GaAs-based systems and provides a brief discussion of carrier-LO-phonon interactions in bulk würtzite structures. This account also includes discussions on the use of metal-semiconductor heterointerfaces to reduce scattering and on the role of phonons in Fröhlich, deformation and piezoelectric interactions in electronic and optoelectronic structures; specific device applications high-lighted here include quantum cascade lasers, mesoscopic devices, thermoelectric devices and optically-pumped resonant intersubband lasers.
Si AND SiGe BIPOLAR ICs FOR 10 TO 40 Gb/s OPTICAL-FIBER TDM LINKS
Authors: REIN H.-M.
Published: May 2003

This paper gives an overview on very-high-speed ICs for optical-fiber systems with restriction to Si-based technologies. As a main aim, the circuit and system designer shall get an impression what operating speeds have already been achieved and, moreover, get a feeling for potential limitations. It is shown that all ICs in 10 Gb/s TDM systems can be fabricated in Si-bipolar production technologies, while for the speed-critical ICs in 20 Gb/s systems, present SiGe laboratory technologies are required if the circuit specifications, apart from the data rate, must remain unchanged. With uncritical circuits like time-division multiplexer (MUX) and demultiplexer (DEMUX), record data rates of 60 Gb/s systems were achieved with a SiGe laboratory technology, using an adequate mounting and measuring technique. Recent measuring results even showed that all ICs in a 40 Gb/s TDM system (i.e., also the speed-critical ones) can be realized in advanced SiGe technologies. However, compared to ICs in 10 and 20 Gb/s systems, some circuit specifications must be relaxed. This is possible by the use of optical amplifiers and improved opto-electronic components as well as by system modifications, which further make possible the elimination of some of the speed-critical circuits. It should be noted that all the experimental results presented are measured on mounted chips, using conventional wire bonding, and that most of the circuits have been used in experimental TDM links.
20–40 Gbit/s GaAs-HEMT CHIP SET FOR OPTICAL DATA RECEIVER
Authors: LAO Z. , LANG M. , HURM V. , WANG Z. , THIEDE A. , SCHLECHTWEG M. , BRONNER W. , KAUFEL G. , KÖHLER K. , HÜLSMANN A. , RAYNOR B. , JAKOBUS T.
Published: May 2003

Using our 0.2 and 0.3 μm AlGaAs/GaAs/AlGaAs quantum well HEMT technology, we have developed a chip set for 20–40 Gbit/s fiber-optical digital transmission systems. In this paper we describe nine analog and digital receiver ICs: a 22 GHz high-gain transimpedance amplifier, a 20 Gbit/s OEIC front-end optical receiver, a 25 Gbit/s automatic-gain-control amplifier, a limiting amplifier with a differential gain of 26 dB and a bandwidth of 27.7 GHz, a 20–40 Gbit/s clock recovery, a 20 Gbit/s low-power Master-Slave-D-Flipflop with 24 mW power dissipation, a parallel data decision and a 1:4 demultiplexer, both for bit rates of 40 Gbit/s, and a 30 GHz static frequency divider, respectively. All chips were characterized on wafers with 50 Ω coplanar test probes.
HBT ICs FOR OC-192 EQUIPMENT
Authors: SITCH JOHN , SURRIDGE ROBERT
Published: May 2003

Heterojunction bipolar transistor (HBT) integrated circuits are just beginning to appear on the commercial market, mostly as small-scale microwave and broadband parts. The high-speed portion of Nortel's OC-192 fiber communications product makes extensive use of this new technology, and this article describes the rationale for using HBT ICs in such a system, and the philosophy behind HBT IC introduction.
InP-HBT ICs FOR 40 Gb/s OPTICAL LINKS
Authors: MOKHTARI MEHRAN , WESTERGREN URBAN , WILLÉN BO , SWAHN THOMAS , WALDEN ROBERT
Published: May 2003

InP-based HBT technology has proven to be a strong candidate for ultra high speed electronic as well as optoelectronic integrated circuits. The cut-offs frequencies of the available devices exceed 100 GHz. To challenge the technology, a variety of circuits, suitable for a demonstrator for the 40 Gb/s fiber optical transmission system have been designed, fabricated, and tested. All the circuits show potential for 40 Gb/s applications. The electrical parts have been implemented in MSI/LSI AlInAs/InGaAs-HBT technology, while the monolithic optoelectronic receivers were realized in SSI- InP/InGaAs HBT technology. The verification of performance of the circuits have been mainly limited by available measurement equipment. All the electronic parts were operational with 3 volt supply voltage. All the circuits were fully functional after the first processing round. No redesign was necessary.
ULTRAHIGH fmax AlInAs/GaInAs TRANSFERRED-SUBSTRATE HETEROJUNCTION BIPOLAR TRANSISTORS FOR INTEGRATED CIRCUITS APPLICATIONS
Authors: AGARWAL BIPUL , PULLELA RAJASEKHAR , BHATTACHARYA UDDALAK , MENSA DINO , LEE QING-HUNG , SAMOSKA LORENE , GUTHRIE JAMES , RODWELL MARK
Published: May 2003

Transferred-substrate heterojunction bipolar transistors (HBTs) have demonstrated very high bandwidths and are potential candidates for very high speed integrated circuit (IC) applications. The transferred-substrate process permits fabrication of narrow and aligned emitter-base and collector-base junctions, reducing the collector-base capacitance and increasing the device f max . Unlike conventional double-mesa HBTs, transferred-substrate HBTs can be scaled to submicron dimensions with a consequent increase in bandwidth. This paper introduces the concept of transferred-substrate HBTs. Fabrication process in the AlInAs/GaInAs material system is presented, followed by DC and RF performance. A demonstration IC is shown along with some integrated circuits in development.
TUNNEL INJECTION LASERS
Authors: BHATTACHARYA PALLAB
Published: May 2003

Carrier heating in conventional quantum well lasers can lead to several deleterious effects and are related to the transport and thermalization characteristics of injected carriers. The properties of a quantum well laser in which the electrons are directly transported to the lasing subband by tunneling is described here. The resulting device — a tunnel injection laser — is shown to have negligible gain compression, superior high-temperature performance, lower Auger recombination and wavelength chirp, and better high frequency modulation characteristics when compared to conventional lasers. All these improvements are attributed to the reduction of hot-carrier population in the active region of the laser. Results are presented here for lasers made with GaAs — and InP — based heterostructure systems.
DEVICES CHARACTERISTICS OF LOW-THRESHOLD QUANTUM-DOT LASERS
Authors: ZHUKOV ALEXEY E. , USTINOV VICTOR M. , ALFEROV ZHORES I.
Published: May 2003

This paper addresses the issues associated with physics and technology of diode lasers based on self-organized quantum dots (QDs). Theoretically predicted advantages of a QD array as the active region of a semiconductor laser and basic principles of QD formation using self-organization phenomena are discussed. Special attention is paid to relationship between structural and electronic properties of QDs and laser characteristics. Recent ahcievements in controlling these parameters including the effects of vertical stacking, changing the matrix bandgap and the surface density of QDs are reviewed. The threshold and power characteristics of the state-of-the-art QD lasers are demonstrated.
OPTOELECTRONIC PROPERTIES OF STRAINED WURTZITE GaN QUANTUM-WELL LASERS
Authors: WANG JIN , JEON J. B. , KIM K. W. , LITTLEJOHN M. A.
Published: May 2003

Fundamental optical properties of strained wurtzite GaN quantum-well laser are calculated and evaluated near the threshold condition. The formalism is based on a self-consistent methodology that couples an envelope-function Hamiltonian for band structures with photon-carrier rate equations. Details of energy band structure, optical gain, and modulation response are studied comprehensively under the effects of strain-induced piezoelectric fields, bandgap renormalization, and the carrier capture processes. Comparisons between different approximations show that self-consistency is essential to accurately simulate pseudomorphically strained wurtzite GaN quantum-well lasers.
QUANTUM STATE ENGINEERING BASED ON ELECTROMAGNETIC ANALOGIES AND NUMERICAL METHODS FOR SEMICONDUCTOR INTERSUBBAND LASERS
Authors: ANEMOGIANNIS EMMANUEL , GLYTSIS ELIAS N. , GAYLORD THOMAS K.
Published: May 2003

The design of semiconductor intersubband lasers using quantum state engineering based on electromagnetic analogies is a relatively new area. There has been little systematic effort in this direction as yet. The use of these analogies allows laser researchers to apply tools and methodologies found in the mature field of electromagnetic optics. The purpose of this paper is to describe the procedures by which intersubband quantum-well semiconductor lasers (or detectores) may be designed using these methodologies.
ADVANCED SEMICONDUCTOR LASERS: PHONON ENGINEERING AND PHONON INTERACTIONS
Authors: DUTTA M. , STROSCIO M. A.
Published: May 2003

This account presents theoretical results on the tailoring of carrier scattering by polar-optical phonons in novel quantum-well lasers such as the tunneling injection laser and the quantum cascade laser. These scattering rates are tailored by engineering semiconductor heterostructures on a scale sufficiently small that both the phonon amplitudes and the phonon envelopes are modified by dimensional confinement. As background information on the properties of confined phonons, this account provides a brief survey of phonon confinement effects in dimensionally-confined structures.
ELEMENTARY EXCITATIONS AND OPTICAL ABSORPTION IN A POLYACENE CHAIN
Authors: AN Z. , WU C. Q.
Published: May 2003

Within a tight-binding Su–Schrieffer–Heeger model, the elementary excitations and optical absorption of a polyacene chain are investigated. The polyacene chain composed of a number of aromatic rings is considered as two strongly coupled polyacetylene chains with an open boundary condition. First of all we found an interchain-coupled neutral soliton in a pristine chain as a consequence of odd-number sites in each chain. There are two localized electronic states accompanying the soliton and appearing in the conduction and valence bands, respectively. Moreover, an injected electron or hole will induce a polaron-like deformation mixed with the interchain soliton, while two extra electrons or holes will result in three separate solitons, among which one is doubly charged and other two are neutral. The optical absorption due to these elementary excitations are obtained.
AC SUSCEPTIBILITIES IN Zn DOPED (Bi,Pb)(Sr,Ba):2223 SUPERCONDUCTOR
Authors: POP V.
Published: May 2003

AC susceptibility measurements as a function of temperature and amplitude of alternative magnetic field have been carried out on the samples (Bi,Pb)(Sr,Ba):2223 with Cu substituted by Zn at a concentration of x = 0.00, 0.02 and 0.05. The decrease of intergrain and intragrain critical temperatures with increasing x is in agreement with the increase of the residual resistivity. Using Muller critical state model and the linear dependence of Tp for the maximum of imaginary χ″(T) peak, as a function of AC field amplitude, the intergranular pining force density was obtained. The intergrain properties are more influenced than the intragrain ones.
INTERACTIONS IN ORDERED SURFACTANTS, POLYMERS AND COLLOIDS
Authors: HAUCK J. , MIKA K.
Published: May 2003

The surfactant structures are approximately given by the zero-potential surfaces of A + and B - atoms in circle or sphere packings. The Dirichlet domains of A atoms are connected by T1 channels to neighboring A domains in rod like structures with T1 = 2, or layered structures at increased T1 values. Micelles are usually isolated with T1 = 0 or 1 channels. Layered or rod like structures are formed at A–A attraction while isolated micelles are formed at repulsive A–A interactions. The rod like structures are similar to polymer chains of A = carbon atoms with T1 = 2 neighbors. The ordered micelle structures are observed for charged colloid particles A +.
THE SPECTRAL PROPERTIES OF THE FALICOV–KIMBALL MODEL IN THE WEAK-COUPLING LIMIT
Authors: FARKAŠOVSKÝ PAVOL
Published: May 2003

The f and d electron density of states of the one-dimensional Falicov–Kimball model are studied in the weak-coupling limit by exact diagonalization calculations. The resultant behaviors are used to examine the d electron gap (Δd), the f electron gap (Δf), and the fd electron gap (Δfd) as functions of the f level energy Ef and hybridization V. It is shown that the spinless Falicov–Kimball model behaves fully differently for zero and finite hybridization between f and d states. At zero hybridization the energy gaps do not coincide (Δd ≠ Δf ≠ Δfd), and the activation gap Δfd vanishes discontinuously at some critical value of the f level energy Efc. On the other hand, at finite hybridization all energy gaps coincide and vanish continuously at the insulator-metal transition point Ef = Efc. The importance of these results for a description of real materials is discussed.
NANOSTRUCTURED AND BULK AMORPHOUS Zr-BASED ALLOYS PREPARED BY MECHANICAL ALLOYING AND ARC MELTING
Authors: BASKOUTAS S. , LEMIS-PETROPOULOS P. , KAPAKLIS V. , KOVEOS Y. , POLITIS C.
Published: May 2003

We have produced powders of nanostructured and amorphous alloys as well as bulk amorphous alloys with composition Zr64Cu18Ni10Al8by mechanical alloying and by quenching arc melted melts in water cooled cooper dies, respectively. The alloys were investigated by X-ray diffraction as well as by thermal analysis in order to determine the structure and thermal properties. The mechanical alloyed amorphous powders and bulk amorphous cylinders show the same thermal and X-ray characteristics. For the amorphous powders, we find that the glass transition temperature Tgis 657 K and the crystallization temperature Txis 752 K. For bulk amorphous alloys with the same composition prepard by arc melting and liquid quenching Tgis 655 K and the Txis 725 K. Moreover for the bulk amorphous alloys the supercooled liquid region Δ Txgis 70 K, the reduced glass transition temperature tgis 0.557, the Lu–Liu parameter γ which represents the glass forming ability for bulk metallic glasses is 0.396 and experimentally the critical cooling rate Rctakes the value 7 K s-1.
WEAK DIAMOND AND OPEN COLORINGS
Authors: MOORE JUSTIN TATCH
Published: May 2003

The purpose of this article is to prove the relative consistency of certain statements about open colorings with 2ℵ0< 2ℵ1. In particular both OCA and the statement that every 1–1 function of size ℵ1is σ-monotonic are consistent with 2ℵ0< 2ℵ1. As a corollary we have that 2ℵ0< 2ℵ1does not admit a ℙmaxvariation (in the presence of an inaccessible cardinal).
INTERPRETING GROUPS INSIDE MODULAR STRONGLY MINIMAL HOMOGENEOUS MODELS
Authors: HYTTINEN TAPANI
Published: May 2003

A large homogeneous (not necessarily saturated) model M is strongly minimal, if any definable subset is either bounded or has bounded complement. In this case (M, bcl) is a pregeometry, where bcl denotes the bounded closure operation. In this paper, we show that if M is a large homogeneous strongly minimal structure and (M, bcl) is non-trivial and locally modular, then M interprets a group. In addition, we give a description of such groups.
Navigation patterns & usability of zoomable user interfaces
Authors: Hornbaek Kasper , Bederson Benjamin B. , Plaisant Catherine
Published: May 2003

The following abstracts are from recent issues and the forthcoming issue of ACM's
Transactions of Computer Human Interaction
(ToCHI). They are included here to alert
interactions'
readers to what research is being done in the field of Computer Human Interaction. The complete papers, when published, can be found in ACM's Digital Library at www.acm.org/pubs/contents/journals/tochi/
Like water for data flow
Authors: Davis Dineh M.
Published: May 2003

This issue's Whiteboard takes a bit of a different tack from past columns. Rather than exhorting us to follow process A or stop making mistake B, Dineh Davis immerses herself in the almost mystical idea of water as a metaphor for information. She envisions water as helping us understand and appreciate the diversity in humanity's relationships with information and its technology, enabling us to increase user participation in its development. Now, you may see some problems with this idea. But I'd say that they're, er, soluble.
---Elizabeth Buie
A logical framework for reasoning about access control models
Authors: Bertino Elisa , Catania Barbara , Ferrari Elena , Perlasca Paolo
Published: May 2003

The increased awareness of the importance of data protection has made access control a relevant component of current data management systems. Moreover, emerging applications and data models call for flexible and expressive access control models. This has led to an extensive research activity that has resulted in the definition of a variety of access control models that differ greatly with respect to the access control policies they support. Thus, the need arises for developing tools for reasoning about the characteristics of these models. These tools should support users in the tasks of model specification, analysis of model properties, and authorization management. For example, they must be able to identify inconsistencies in the model specification and must support the administrator in comparing the expressive power of different models. In this paper, we make a first step in this direction by proposing a formal framework for reasoning about access control models. The framework we propose is based on a logical formalism and is general enough to model discretionary, mandatory, and role-based access control models. Each instance of the proposed framework corresponds to a C-Datalog program, interpreted according to a stable model semantics. In the paper, besides giving the syntax and the formal semantics of our framework, we show some examples of its application. Additionally, we present a number of dimensions along which access control models can be analyzed and compared. For each dimension, we show decidability results and we present some examples of its application.
Instruction generation for hybrid reconfigurable systems
Authors: Kastner R. , Kaplan A. , Memik S. Ogrenci , Bozorgzadeh E.
Published: May 2003

Future computing systems need to balance flexibility, specialization, and performance in order to meet market demands and the computing power required by new applications. Instruction generation is a vital component for determining these trade-offs. In this work, we present theory and an algorithm for instruction generation. The algorithm profiles a dataflow graph and iteratively contracts edges to create the templates. We discuss how to target the algorithm toward the novel problem of instruction generation for hybrid reconfigurable systems. In particular, we target the Strategically Programmable System, which embeds complex computational units such as ALUs, IP blocks, and so on into a configurable fabric. We argue that an essential compilation step for these systems is instruction generation, as it is needed to specify the functionality of the embedded computational units. In addition, instruction generation can be used to create soft reconfigurable macros---tightly sequenced prespecified operations placed in the reconfigurable fabric.
E-commercializing business operations
Authors: Shi Xinping , Wright Philip C.
Published: May 2003

Want to incorporate the Internet into your business strategy? Be sure you have a sound business plan, a product that people (with enough money) want to buy, and management, employees, and contractors able to implement and use the technology.
Peer-to-peer prospects
Authors: Schoder Detlef , Fischbach Kai
Published: May 2003

The P2P design philosophy needs far more detail before we can appreciate a clear picture of its potential.
Introduction
Authors: Lethin Richard
Published: May 2003

Peer-to-Peer (P2P) computing has both technical and social components. Both these components share the attraction of distributed control, where computers operating as peers collaborate to achieve an end result without a central authority.
Comparing test sets and criteria in the presence of test hypotheses and fault domains
Authors: Hierons R. M.
Published: May 2003

A number of authors have considered the problem of comparing test sets and criteria. Ideally test sets are compared using a preorder with the property that test set
T
1
is at least as strong as
T
2
if whenever
T
2
determines that an implementation
p
is faulty,
T
1
will also determine that
p
is faulty. This notion can be extended to test criteria. However, it has been noted that very few test sets and criteria are comparable under such an ordering; instead orderings are based on weaker properties such as subsumes. This article explores an alternative approach, in which comparisons are made in the presence of a test hypothesis or fault domain. This approach allows strong statements about fault detecting ability to be made and yet for a number of test sets and criteria to be comparable. It may also drive incremental test generation.
Automated abstraction of class diagrams
Authors: Egyed Alexander
Published: May 2003

Designers can easily become overwhelmed with details when dealing with large class diagrams. This article presents an approach for automated abstraction that allows designers to "zoom out" on class diagrams to investigate and reason about their bigger picture. The approach is based on a large number of abstraction rules that individually are not very powerful, but when used together, can abstract complex class structures quickly. This article presents those abstraction rules and an algorithm for applying them. The technique was validated on over a dozen models where it was shown to be well suited for model understanding, consistency checking, and reverse engineering.
Exploiting hierarchical domain structure to compute similarity
Authors: Ganesan Prasanna , Garcia-Molina Hector , Widom Jennifer
Published: May 2003

The notion of similarity between objects finds use in many contexts, for example, in search engines, collaborative filtering, and clustering. Objects being compared often are modeled as sets, with their similarity traditionally determined based on set intersection. Intersection-based measures do not accurately capture similarity in certain domains, such as when the data is sparse or when there are known relationships between items within sets. We propose new measures that exploit a hierarchical domain structure in order to produce more intuitive similarity scores. We extend our similarity measures to provide appropriate results in the presence of multisets (also handled unsatisfactorily by traditional measures), for example, to correctly compute the similarity between customers who buy several instances of the same product (say milk), or who buy several products in the same category (say dairy products). We also provide an experimental comparison of our measures against traditional similarity measures, and report on a user study that evaluated how well our measures match human intuition.
Computational properties of metaquerying problems
Authors: Angiulli Fabrizio , Ben-Eliyahu-Zohary Rachel , Ianni Giovambattista , Palopoli Luigi
Published: May 2003

Metaquerying is a data mining technology by which hidden dependencies among several database relations can be discovered. This tool has already been successfully applied to several real-world applications, but only preliminary results about the complexity of metaquerying can be found in the literature. In this article, we define several variants of metaquerying that encompass, as far as we know, all the variants that have been defined in the literature. We study both the combined complexity and the data complexity of these variants. We show that under the combined complexity measure metaquerying is generally intractable (unless
P
=
NP
), lying sometimes quite high in the complexity hierarchies (as high as

NP
PP

), depending on the characteristics of the plausibility index. Nevertheless, we are able to single out some tractable and interesting metaquerying cases, whose combined complexity is LOGCFL-complete. As for the data complexity of metaquerying, we prove that, in general, it is within
TC
0
, but lies within
AC
0
in some simpler cases. Finally, we discuss the implementation of metaqueries by providing algorithms that answer them.
Adaptive brain interfaces
Authors: Millán José del R.
Published: May 2003

Users interact with physical devices through nothing more than the voluntary control of their own mental activity.
The new productivity paradox
Authors: Anderson Mark C. , Banker Rajiv D. , Ravindran Sury
Published: May 2003

High valuation multiples on IT spending suggest that companies are underinvesting in IT.
The rise and fall of an e-commerce program
Authors: Rob Mohammad
Published: May 2003

E-commerce may be here to stay, but how to teach it is still up for debate at many institutions.
Models of attention in computing and communication
Authors: Horvitz Eric , Kadie Carl , Paek Tim , Hovel David
Published: May 2003

Creating computing and communication systems that sense and reason about human attention by fusing together information from multiple streams.
Focusing on the essential
Authors: Baudisch Patrick , DeCarlo Doug , Duchowski Andrew T. , Geisler Wilson S.
Published: May 2003

Attentive displays address the need for rendering power and computer display resolution. The five examples presented here illustrate a common goal with very different approaches to achieving it.
Attuning notification design to user goals and attention costs
Authors: McCrickard D. Scott , Chewar C. M.
Published: May 2003

Why is the attentive user interface paradigm important for human-computer interaction? The human attention system is so sensitive to various methods of notification that traditional design involves too much compromise and guesswork.
Object-oriented programming of integrated circuits
Authors: Templeton Gary F.
Published: May 2003

New programming architecture is revolutionizing how programmers control hardware circuitry.
Mini-buckets
Authors: Dechter Rina , Rish Irina
Published: May 2003

This article presents a class of approximation algorithms that extend the idea of bounded-complexity inference, inspired by successful constraint propagation algorithms, to probabilistic inference and combinatorial optimization. The idea is to bound the dimensionality of dependencies created by inference algorithms. This yields a parameterized scheme, calledmini-buckets, that offers adjustable trade-off between accuracy and efficiency. The mini-bucket approach to optimization problems, such as finding the most probable explanation (MPE) in Bayesian networks, generates both an approximate solution and bounds on the solution quality. We present empirical results demonstrating successful performance of the proposed approximation scheme for the MPE task, both on randomly generated problems and on realistic domains such as medical diagnosis and probabilistic decoding.
Time-space trade-off lower bounds for randomized computation of decision problems
Authors: Beame Paul , Saks Michael , Sun Xiaodong , Vee Erik
Published: May 2003

We prove the first time-space lower bound trade-offs for randomized computation of decision problems. The bounds hold even in the case that the computation is allowed to have arbitrary probability of error on a small fraction of inputs. Our techniques are extension of those used by Ajtai and by Beame, Jayram, and Saks that applied to deterministic branching programs. Our results also give a quantitative improvement over the previous results.Previous time-space trade-off results for decision problems can be divided naturally into results for functions with
Boolean domain
, that is, each input variable is {0,1}-valued, and the case of
large domain
, where each input variable takes on values from a set whose size grows with the number of variables.In the case of Boolean domain, Ajtai exhibited an explicit class of functions, and proved that any deterministic Boolean branching program or RAM using space
S
=
o
(
n
) requires superlinear time
T
to compute them. The functional form of the superlinear bound is not given in his paper, but optimizing the parameters in his arguments gives
T
= Ω(
n
log log
n
/log log log
n
) for
S
=
O
(
n
1-ϵ
). For the same functions considered by Ajtai, we prove a time-space trade-off (for randomized branching programs with error) of the form
T
= Ω(
n
√ log(
n/S
)/log log (
n/S
)). In particular, for space
O
(
n
1-ϵ
), this improves the lower bound on time to Ω(
n
√ log
n
/log log
n
).In the large domain case, we prove lower bounds of the form
T
= Ω(
n
√ log(
n/S
)/log log (
n/S
)) for randomized computation of the element distinctness function and lower bounds of the form
T
= Ω(
n
log (
n/S
)) for randomized computation of Ajtai's Hamming closeness problem and of certain functions associated with quadratic forms over large fields.
A complete problem for statistical zero knowledge
Authors: Sahai Amit , Vadhan Salil
Published: May 2003

We present the first complete problem for SZK, the class of promise problems possessing statistical zero-knowledge proofs (against an honest verifier). The problem, called Statistical Difference, is to decide whether two efficiently samplable distributions are either statistically close or far apart. This gives a new characterization of SZK that makes
no reference to interaction or zero knowledge
.We propose the use of complete problems to unify and extend the study of statistical zero knowledge. To this end, we examine several consequences of our Completeness Theorem and its proof, such as:---A way to make every (honest-verifier) statistical zero-knowledge proof very communication efficient, with the prover sending only one bit to the verifier (to achieve soundness error 1/2).---Simpler proofs of many of the previously known results about statistical zero knowledge, such as the Fortnow and Aiello--Hεstad upper bounds on the complexity of SZK and Okamoto's result that SZK is closed under complement.---Strong closure properties of SZK that amount to constructing statistical zero-knowledge proofs for complex assertions built out of simpler assertions already shown to be in SZK.---New results about the various measures of "knowledge complexity," including a collapse in the hierarchy corresponding to knowledge complexity in the "hint" sense.---Algorithms for manipulating the statistical difference between efficiently samplable distributions, including transformations that "polarize" and "reverse" the statistical relationship between a pair of distributions.
Constraint-based approach for automatic hinting of digital typefaces
Authors: Shamir Ariel
Published: May 2003

The rasterization process of characters from digital outline fonts to bitmaps on displays must include additional information in the form of
hints
beside the shape of characters in order to produce high quality bitmaps. Hints describe constraints on sizes and shapes inside characters and across the font that should be preserved during rasterization. We describe a novel, fast and fully automatic method for adding those
hints
to characters. The method is based on identifying hinting situations inside characters. It includes gathering global font information and linking it to characters, defining a set of constraints, sorting them, and converting them to hints in any known hinting technology (PostScript, TrueType or other). Our scheme is general enough to be applied on any language and on complex scripts such as Chinese Japanese and Korean. Although still inferior to expert manual hinting, our method produces high quality bitmaps which approach this goal. The method can also be used as a solid base for further hinting refinements done manually.
Perceptually-driven decision theory for interactive realistic rendering
Authors: Dumont Reynald , Pellacini Fabio , Ferwerda James A.
Published: May 2003

In this paper we introduce a new approach to realistic rendering at interactive rates on commodity graphics hardware. The approach uses efficient perceptual metrics within a decision theoretic framework to optimally order rendering operations, producing images of the highest visual quality within system constraints. We demonstrate the usefulness of this approach for various applications such as diffuse texture caching, environment map prioritization and radiosity mesh simplification. Although here we address the problem of realistic rendering at interactive rates, the perceptually-based decision theoretic methodology we introduce can be usefully applied in many areas of computer graphics.
Universal, ubiquitous, user-interface design for the disabled and elderly
Authors: Marcus Aaron
Published: May 2003

User-interface design seeks to improve all human-computer communication and interaction. Increasingly, challenges for the disabled and elderly must be met. Experience gained can help solve fundamental challenges for the general population of users. A recent international conference in Japan, "Universal Design," catalogues both the accomplishments and work to be done in this worldwide arena.
Building a successful e-business
Authors: Farhoomand Ali F. , Ng Pauline S. P. , Conley William L.
Published: May 2003

The company famous for transporting goods from anywhere to anywhere around the globe has used its impressive information infrastructure to expand into a channel logistics business.
Using e-CRM for a unified view of the customer
Authors: Pan Shan L. , Lee Jae-Nam
Published: May 2003

Applying detailed knowledge of the customer to a larger business domain.
Folk computing
Authors: Jain Ramesh
Published: May 2003

Communicating through the natural human senses, not just theusual text and images, experiential environments can serve even the illiterate and impoverished in the remotest human societies.
DRM and privacy
Authors: Cohen Julie E.
Published: May 2003

How should the law respond to DRM restrictions that invade user privacy?
Computation beyond turing machines
Authors: Wegner Peter , Goldin Dina
Published: May 2003

Seeking appropriate methods to model computing and human thought.
Information technology and economic performance
Authors: Dedrick Jason , Gurbaxani Vijay , Kraemer Kenneth L.
Published: May 2003

For many years, there has been considerable debate about whether the IT revolution was paying off in higher productivity. Studies in the 1980s found no connection between IT investment and productivity in the U.S. economy, a situation referred to as the
productivity paradox
. Since then, a decade of studies at the firm and country level has consistently shown that the impact of IT investment on labor productivity and economic growth is significant and positive. This article critically reviews the published research, more than 50 articles, on computers and productivity. It develops a general framework for classifying the research, which facilitates identifying what we know, how well we know it, and what we do not know. The framework enables us to systematically organize, synthesize, and evaluate the empirical evidence and to identify both limitations in existing research and data and substantive areas for future research.The review concludes that the productivity paradox as first formulated has been effectively refuted. At both the firm and the country level, greater investment in IT is associated with greater productivity growth. At the firm level, the review further concludes that the wide range of performance of IT investments among different organizations can be explained by complementary investments in organizational capital such as decentralized decision-making systems, job training, and business process redesign. IT is not simply a tool for automating existing processes, but is more importantly an enabler of organizational changes that can lead to additional productivity gains.In mid-2000, IT capital investment began to fall sharply due to slowing economic growth, the collapse of many Internet-related firms, and reductions in IT spending by other firms facing fewer competitive pressures from Internet firms. This reduction in IT investment has had devastating effects on the IT-producing sector, and may lead to slower economic and productivity growth in the U.S. economy. While the turmoil in the technology sector has been unsettling to investors and executives alike, this review shows that it should not overshadow the fundamental changes that have occurred as a result of firms' investments in IT. Notwithstanding the demise of many Internet-related companies, the returns to IT investment are real, and innovative companies continue to lead the way.
View planning for automated three-dimensional object reconstruction and inspection
Authors: Scott William R. , Roth Gerhard , Rivest Jean-François
Published: May 2003

Laser scanning range sensors are widely used for high-precision, high-density three-dimensional (3D) reconstruction and inspection of the surface of physical objects. The process typically involves planning a set of views, physically altering the relative object-sensor pose, taking scans, registering the acquired geometric data in a common coordinate frame of reference, and finally integrating range images into a nonredundant model. Efficiencies could be achieved by automating or semiautomating this process. While challenges remain, there are adequate solutions to semiautomate the scan-register-integrate tasks. On the other hand, view planning remains an open problem---that is, the task of finding a suitably small set of sensor poses and configurations for specified reconstruction or inspection goals. This paper surveys and compares view planning techniques for automated 3D object reconstruction and inspection by means of active, triangulation-based range sensors.
Remark on algorithm 659
Authors: Joe Stephen , Kuo Frances Y.
Published: May 2003

An algorithm to generate Sobol' sequences to approximate integrals in up to 40 dimensions has been previously given by Bratley and Fox in Algorithm 659. Here, we provide more primitive polynomials and "direction numbers" so as to allow the generation of Sobol' sequences to approximate integrals in up to 1111 dimensions. The direction numbers given generate Sobol' sequences that satisfy Sobol's so-called Property A.
Induced well-distributed sets in Riemannian spaces
Authors: Wenzel Lothar , Rajagopal Ram , Nair Dinesh
Published: May 2003

The concept of Riemannian geometries is used to construct induced homogeneous point sets on manifolds that are based on well-distributed point sets in unit cubes of an appropriately chosen Euclidean space. These well-distributed point sets in unit cubes are based on standard low-discrepancy sequences. The approach is algorithmic, that is, the methods developed in this article have been implemented and tested. Applications in image processing, graph theory and measurement-based exploration are presented.
A transformational approach to binary translation of delayed branches
Authors: Ramsey Norman , Cifuentes Cristina
Published: May 2003

A binary translator examines binary code for a source machine and generates code for a target machine. Understanding what to do with delayed branches in binary code can involve tricky case analyses, for example, if there is a branch instruction in a delay slot. This article presents a disciplined method for deriving such case analyses. The method identifies problematic cases, shows the translations for the nonproblematic cases, and gives confidence that all cases are considered. The method supports such common architectures as SPARC, MIPS, and PA-RISC, and it should apply to any tool that analyzes machine instructions. We begin by writing a very simple interpreter for the source machine's code. We then transform the interpreter into an interpreter for a target machine without delayed branches. To maintain the semantics of the program being interpreted, we simultaneously transform the sequence of source-machine instructions into a sequence of target-machine instructions. The transformation of the instructions becomes our algorithm for binary translation.
Eliminating synchronization bottlenecks using adaptive replication
Authors: Rinard Martin C. , Diniz Pedro C.
Published: May 2003

This article presents a new technique, adaptive replication, for automatically eliminating synchronization bottlenecks in multithreaded programs that perform atomic operations on objects. Synchronization bottlenecks occur when multiple threads attempt to concurrently update the same object. It is often possible to eliminate synchronization bottlenecks by replicating objects. Each thread can then update its own local replica without synchronization and without interacting with other threads. When the computation needs to access the original object, it combines the replicas to produce the correct values in the original object. One potential problem is that eagerly replicating all objects may lead to performance degradation and excessive memory consumption.Adaptive replication eliminates unnecessary replication by dynamically detecting contention at each object to find and replicate only those objects that would otherwise cause synchronization bottlenecks. We have implemented adaptive replication in the context of a parallelizing compiler for a subset of C++. Given an unannotated sequential program written in C++, the compiler automatically extracts the concurrency, determines when it is legal to apply adaptive replication, and generates parallel code that uses adaptive replication to efficiently eliminate synchronization bottlenecks.In addition to automatic parallelization and adaptive replication, our compiler also implements a lock coarsening transformation that increases the granularity at which the computation locks objects. The advantage is a reduction in the frequency with which the computation acquires and releases locks; the potential disadvantage is the introduction of new synchronization bottlenecks caused by increases in the sizes of the critical sections. Because the adaptive replication transformation takes place at lock acquisition sites, there is a synergistic interaction between lock coarsening and adaptive replication. Lock coarsening drives down the overhead of using adaptive replication, and adaptive replication eliminates synchronization bottlenecks associated with the overaggressive use of lock coarsening.Our experimental results show that, for our set of benchmark programs, the combination of lock coarsening and adaptive replication can eliminate synchronization bottlenecks and significantly reduce the synchronization and replication overhead as compared to versions that use none or only one of the transformations.