bluuebunny/crossref_metadata_2025_split huggingface dataset:
Design and evaluation of algorithms for image retrieval by spatial similarity
Authors: Gudivada Venkat N. , Raghavan Vijay V. 
Published: July 2002

Similarity-based retrieval of images is an important task in many image database applications. A major class of users' requests requires retrieving those images in the database that are spatially similar to the query image. We propose an algorithm for computing the spatial similarity between two symbolic images. A symbolic image is a logical representation of the original image where the image objects are uniquely labeled with symbolic names. Spatial relationships in a symbolic image are represented as edges in a weighted graph referred to as spatial-orientation graph. Spatial similarity is then quantified in terms of the number of, as well as the extent to which, the edges of the spatial-orientation graph of the database image conform to the corresponding edges of the spatial-orientation graph of the query image.
The proposed algorithm is robust in the sense that it can deal with translation, scale, and rotational variances in images. The algorithm has quadratic time complexity in terms of the total number of objects in both the database and query images. We also introduce the idea of quantifying a system's retrieval quality by having an expert specify the expected rank ordering with respect to each query for a set of test queries. This enables us to assess the quality of algorithms comprehensively for retrieval in image databases. The characteristics of the proposed algorithm are compared with those of the previously available algorithms using a testbed of images. The comparison demonstrated that our algorithm is not only more efficient but also provides a rank ordering of images that consistently matches with the expert's expected rank ordering.
Attribute grammar paradigms—a high-level methodology in language implementation
Authors: Paakki Jukka 
Published: July 2002

Attribute grammars are a formalism for specifying programming languages. They have been applied to a great number of systems automatically producing language implementations from their specifications. The systems and their specification languages can be evaluated and classified according to their level of application support, linguistic characteristics, and degree of automation.
A survey of attribute grammar-based specification languages is given. The modern advanced specification languages extend the core attribute grammar model with concepts and primitives from established programming paradigms. The main ideas behind the developed attribute grammar paradigms are discussed, and representative specification languages are presented with a common example grammar. The presentation is founded on mapping elements of attribute grammars to their counterparts in programming languages. This methodology of integrating two problem-solving disciplines together is explored with a classification of the paradigms into structured, modular, object-oriented, logic, and functional attribute grammars. The taxonomy is complemented by introducing approaches based on an implicit parallel or incremental attribute evaluation paradigm.
A visual interface for a database with version management
Authors: Davison Jay W. , Zdonik Stanley B. 
Published: July 2002

This paper describes a graphical interface to an experimental database system which incorporates a built-in version control mechanism that maintains a history of the database development and changes. The system is an extension of ISIS [6], Interface for a Semantic Information System, a workstation-based, graphical database programming tool developed at Brown University. ISIS supports a graphical interface to a modified subset of the Semantic Data Model (SDM) [7]. The ISIS extension introduces a transaction mechanism that interacts with the version control facilities.
A series of version control support tools have been added to ISIS to provide a notion of history to user-created databases. The user can form new versions of three types of ISIS objects: a class definition object (a type), the set of instances of a class (the content), and an entity. A version-viewing mechanism is provided to allow for the comparison of various object versions. Database operations are grouped together in atomic units to form transactions, which are stored as entities in the database. A sample session demonstrates the capabilities of version and transaction control during the creation and manipulation of database objects.
Knowledge compilation and theory approximation
Authors: Selman Bart , Kautz Henry 
Published: July 2002

Computational efficiency is a central concern in the design of knowledge representation systems. In order to obtain efficient systems, it has been suggested that one should limit the form of the statements in the knowledge base or use an incomplete inference mechanism. The former approach is often too restrictive for practical applications, whereas the latter leads to uncertainty about exactly what can and cannot be inferred from the knowledge base. We present a third alternative, in which knowledge given in a general representation language is translated (compiled) into a tractable form—allowing for efficient subsequent query answering.
We show how propositional logical theories can be compiled into Horn theories that approximate the original information. The approximations bound the original theory from below and above in terms of logical strength. The procedures are extended to other tractable languages (for example, binary clauses) and to the first-order case. Finally, we demonstrate the generality of our approach by compiling concept descriptions in a general frame-based language into a tractable form.
Minimizing stall time in single and parallel disk systems
Authors: Albers Susanne , Garg Naveen , Leonardi Stefano 
Published: July 2002

We study integrated prefetching and caching problems following the work of Cao et al. [1995] and Kimbrel and Karlin [1996]. Cao et al. and Kimbrel and Karlin gave approximation algorithms for minimizing the total elapsed time in single and parallel disk settings. The total elapsed time is the sum of the processor stall times and the length of the request sequence to be served.
We show that an optimum prefetching/caching schedule for a single disk problem can be computed in polynomial time, thereby settling an open question by Kimbrel and Karlin. For the parallel disk problem, we give an approximation algorithm for minimizing stall time. The solution uses a few extra memory blocks in cache. Stall time is an important and harder to approximate measure for this problem. All of our algorithms are based on a new approach which involves formulating the prefetching/caching problems as linear programs.
The conversion of limited-entry decision tables to optimal and near-optimal flowcharts
Authors: Verhelst M. 
Published: July 2002

Two new algorithms for deriving optimal and near-optimal flowcharts from limited entry decision tables are presented. Both take into account rule frequencies and the time needed to test conditions. One of the algorithms, called the optimum-finding algorithm, leads to a flowchart which truly minimizes execution time for a decision table in which simple rules are already contracted to complex rules. The other one, called the optimum-approaching algorithm, requires many fewer calculations but does not necessarily produce the optimum flowchart. The algorithms are first derived for treating decision tables not containing an ELSE-rule, but the optimum-approaching algorithm is shown to be equally valid for tables including such a rule.
Both algorithms are compared with existing ones and are applied to a somewhat large decision table derived from a real case. From this comparison two conclusions are drawn. (1) The optimum-approaching algorithm will usually lead to better results than comparable existing ones and will not require more, but usually less, computation time. (2) In general, the greater computation effort needed for applying the optimum-finding algorithm will not be justified by the small reduction in execution time obtained.
Software
Authors: Gold Charles L. , Goodman Seymour E. , Walker Benjamin G. 
Published: July 2002

The control of computer technology exports, for both hardware and software, is being actively debated in government and industry circles. At the request of the U.S. Department of Defense, the Computer Network Critical Technology Expert Group (CNCTEG) was established with the support of the Electronics Industries Association and the Computer Business Equipment Manufacturers Association. The task of the CNCTEG was to assess critical technologies associated with computer networks, and to make recommendations regarding the control of the export of such technologies. The formulation of a reasonable export control policy for software has remained a particularly difficult matter that has frustrated both the U.S. government and industry. This article presents the CNCTEG's initial recommendations for the export control of software.
This material is presented in the belief that open, active discussion among members of the information processing community will be helpful in advancing the development of a sound national policy regarding the export of software products and know-how.
Pictorial pattern recognition and the phase problem of x-ray crystallography
Authors: Lesk Arthur M. 
Published: July 2002

The availability of interactive, three-dimensional, computer graphics systems coupled to powerful digital computers encourages the development of algorithms adapted to this environment. Pictorial pattern recognition techniques make possible a number of approaches to X-ray structure determination based on molecular model building, i.e. the use of chemical information to frame “structural hypotheses” which can computationally be tested and refined by reference to the experimental data.Application of standard pattern recognition algorithms is hindered by the fact that the cross-correlation between a model and the correct structure cannot be computed because of a fundamental incompleteness in the measured data. However, it is possible to compute an upper bound to such a cross-correlation. A simple example demonstrates that this information can be the basis of a technique for structure determination that can make effective use of an interactive graphics system.Model building by cross-correlations has intrinsic advantages over usual crystallographic techniques based on the autocorrelation or Patterson function, especially for large structures. This is significant, for crystallography of biological macromolecules has been and will continue to be a field of intense interest.
Index ranges for matrix calculi
Authors: Bayer R. , Witzgall C. 
Published: July 2002

The paper describes a scheme for symbolic manipulation of index expressions which arise as a by-product of the symbolic manipulation of expressions in the matrix calculi described by the authors in a previous paper. This scheme attempts program optimization by transforming the original algorithm rather than the machine code.
The goal is to automatically generate code for handling the tedious address calculations necessitated by complicated data structures. The paper is therefore preoccupied with “indexing by position.” The relationship of “indexing by name” and “indexing by position” is discussed.
Degree of multiprogramming in page-on-demand systems
Authors: Wallace V. L. , Mason D. L. 
Published: July 2002

A simple stochastic model is described which offers a base for understanding the relationship between the number of programs permitted to share memory (the degree of multiprogramming), drum traffic rates, and central processing unit utilization in page-on-demand, multiprogrammed, time-shared computer systems. The model preserves, as a key feature, the property of page-demand statistics which implies a “burst” of page demands at the beginning of any job or quantum execution.
The model, a Markov chain, is analyzed numerically and the results are presented graphically for a wide range of key environment-descriptive parameters. Implications of the results to time-shared system design and programming are discussed, and a calculation of the optimal degree of multiprogramming for a wide range of parameters is presented graphically.
Polyphase sorting with overlapped rewind
Authors: McAllester R. L. 
Published: July 2002

A variation of the polyphase merge technique of sorting is described which permits one tape at a time to be rewound while the merge is continued on the remaining tapes. The result is the overlapping of a major portion of the rewind time.
The technique should be considered whenever a sort is written to operate on five or more tapes that cannot be read backwards. The savings of the overlap method appear to increase as the number of available tapes is increased.
THE LYMAN ALPHA FOREST IN THE SPECTRA OF QUASISTELLAR OBJECTS
Authors: Rauch Michael 
Published: July 2002

▪ Abstract  Observations of redshifted Lyman α (Lyα) forest absorption in the spectra of quasistellar objects (QSOs) provide a highly sensitive probe of the distribution of gaseous matter in the universe. Over the past two decades, optical spectroscopy with large ground-based telescopes, and more recently ultraviolet (UV) spectroscopy from space, have yielded a wealth of information on what appears to be a gaseous, photoionized intergalactic medium (IGM), partly enriched by the products of stellar nucleosynthesis, residing in coherent structures over many hundreds of kiloparsecs. Recent progress with cosmological hydro-simulations based on hierarchical structure formation models has led to important insights into the physical structures giving rise to the forest. If these ideas are correct, a truly inter- and protogalactic medium [at high redshift (z ∼ 3), the main repository of baryons] collapses under the influence of dark matter gravity into flattened or filamentary structures, which are seen in absorption against background QSOs. With decreasing redshift, galaxies forming in the denser regions may contribute an increasing part of the Lyα absorption cross section. Comparisons between large data samples from the new generation of telescopes and artificial Lyα forest spectra from cosmological simulations promise to become a useful cosmological tool.
X-Ray Properties of Groups of Galaxies
Authors: Mulchaey John S. 
Published: July 2002

▪ Abstract  ROSAT observations indicate that approximately half of all nearby groups of galaxies contain spatially extended X-ray emission. The radial extent of the X-ray emission is typically 50–500 h−1100 kpc or approximately 10–50% of the virial radius of the group. Diffuse X-ray emission is generally restricted to groups that contain at least one early-type galaxy. X-ray spectroscopy suggests the emission mechanism is most likely a combination of thermal bremsstrahlung and line emission. This interpretation requires that the entire volume of groups be filled with a hot, low-density gas known as the intragroup medium. ROSAT and ASCA observations indicate that the temperature of the diffuse gas in groups ranges from approximately 0.3 keV to 2 keV. Higher temperature groups tend to follow the correlations found for rich clusters between X-ray luminosity, temperature, and velocity dispersion. However, groups with temperatures below approximately 1 keV appear to fall off the cluster LX-T relationship (and possibly the LX-σ and σ-T cluster relationships, although evidence for these latter departures is at the present time not very strong). Deviations from the cluster LX-T relationship are consistent with preheating of the intragroup medium by an early generation of stars and supernovae. There is now considerable evidence that most X-ray groups are real, physical systems and not chance superpositions or large-scale filaments viewed edge-on. Assuming the intragroup gas is in hydrostatic equilibrium, X-ray observations can be used to estimate the masses of individual systems. ROSAT observations indicate that the typical mass of an X-ray group is ∼1013 h−1100 M[Formula: see text] out to the radius to which X-ray emission is currently detected. The observed baryonic masses of groups are a small fraction of the X-ray determined masses, which implies that groups are dominated by dark matter. On scales of the virial radius, the dominant baryonic component in groups is likely the intragroup medium.
MARS 2000
Authors: Albee Arden L. 
Published: July 2002

Twenty years after the Viking Mission, Mars is again being scrutinized in the light of a flood of information from spacecraft missions to Mars, the Hubble Space Telescope, and the SNC meteorites. This review provides an overview of the current understanding of Mars, especially in light of the data being returned from the Mars Global Surveyor Mission. Mars does not now have a global magnetic field, but the presence of crustal anomalies indicates that a global field existed early in Martian history. The topography, geodetic figure, and gravitational field are known to high precision. The northern hemisphere is lower and has a thinner and stronger crust than the southern hemisphere.The global weather and the thermal structure of the atmosphere have been monitored for more than a year. Surface-atmosphere interaction has been investigated by observations of surface features, polar caps, atmospheric dust, and condensate clouds. The surface has been imaged at very high resolution and spectral measures have been obtained to quantify surface characteristics and geologic processes. Many questions remain unanswered, especially about the earliest period of Mars’ history.
Models of the Posterior Parietal Cortex Which Perform Multimodal Integration and Represent Space in Several Coordinate Frames
Authors: Xing Jing , Andersen Richard A. 
Published: July 2002

Abstract
Many neurons in the posterior-parietal cortex (PPC) have saccadic responses to visual and auditory targets. The responses are modulated by eye position and head position. These findings suggest that PPC integrates multisensory inputs and may provide information about saccadic targets represented in different coordinate frames. In addition to an eye-centered output representation, PPC may also project to brain areas which contain head-centered and body-centered representations of the space. In this report, possible coordinate transformations in PPC were examined by comparing several sets of models of PPC, each having different representations in the output layer: (i) an eye-centered map only; (ii) a head-centered map only; (iii) an eye-centered map and a head-centered map; and (iv) an eye-centered map, a head-centered map, and a body-centered map. These output maps correctly encoded saccades to visual and auditory targets through training. The units in the hidden layers of the models exhibited the following properties: (1) The units had gain fields (GFs) for eye position, and also for head position if the model had a body-centered output representation; (2) As the result of the GF and the nonlinear activation function of the units, the hidden layers often employed “intermediate” coding, e.g., the hidden units coded targets partially in eye-centered coordinates and, partially, in head-centered coordinates; (3) Different types of coordinate transformations in these models were carried out by different relationships between the receptive fields (RFs) and the GFs of the hidden units; and (4) The properties of PPC neurons are in better accordance with the hidden units of the models that had multiple-output representations than the models that had only one single-output representation. In conclusion, the results show that the GF is an effective mechanism for performing coordinate transformations. The models also suggest that neurons with intermediate coding are to be expected in the process of coordinate transformations.
Motor Cortical Activity during Interception of Moving Targets.
Authors: Port Nicholas L. , Kruse Wolfgang , Lee Daeyeol , Georgopoulos Apostolos P. 
Published: July 2002

Abstract
The single-unit activity of 831 cells was recorded in the arm area of the motor cortex of tow monkeys while the monkeys intercepted a moving visual stimulus (interception task) or remained immobile during presentation of the same moving stimulus (no-go task). The moving target traveled on an oblique path from either lower corner of a screen toward the vertical meridian, and its movement time (0.5,1.0, or 1.5 sec) and velocity profile (accelerating, decelerating, or constant velocity) were pseudorandomly varied. The moving target had to be intercepted within 130 msec of target arrival at an interception point. By comparing motor cortical activity at the single-neuron tasks, we tested whether information about parameters of moving target is represented in the primary motor cortex to generate appropriate motor responses. A substantial number of neurons displayed modulation of their activity during the no-go task, and this activity was often affected by the stimulus parameters. These results suggest a role of motor cortex in specifying the timing of movement initiation based on information about target motion. In addition, there was a lack of systematic relation between the onset times of neural activity in the interception and no-go task, suggesting that processing of information concerning target motion and generation of hand movement occurs in parallel. Finally, the activity in the most motor cortical neurons was modulated according to an estimate of the time-to-target interception, raising the possibility that time-to-interception may be coded in the motor cortical activity.
When You Find Yourself in a Hole, Stop Digging: Comments on Earth Systems Engineering
Authors: Friedman Robert M. 
Published: July 2002

SummaryIn an earlier “Forum” article in this journal, Brad Allenby outlined his views of a new approach to managing the unintended consequences of human activity, “earth systems engineering.” He argues that we must develop the tools, institutions, and moral and ethical systems to allow us to “assume an active management role for most global systems.” I believe this to be a significant departure from a core concept of industrial ecology: learning from ecosystems how the natural world operates to be able to more effectively design and manage coupled human‐natural systems. Such lessons are more likely to lead away from tightly managed, centralized approaches, and favor approaches with as little intervention as feasible. More important, I believe that we are far less likely to learn how to implement earth systems engineering than simpler approaches, hence less likely to minimize environmental damage.
Sense Organs and the Activity of Sensation in Aristotle
Authors: Magee Joseph 
Published: July 2002

AbstractAmid the ongoing debate over the proper interpretation of Aristotle's theory of sense perception in the De Anima, Steven Everson has recently presented a well-documented and ambitious treatment of the issue, arguing in favor of Richard Sorabji's controversial position that sense organs literally take on the qualities of their proper objects. Against the interpretation of M. F. Burnyeat, Everson and others make a compelling case the Aristotelian account of sensation requires some physical process to occur in sense organs. A detailed examination of the interpretation by Everson and Sorabji of Aristotle's theory, however, shows that their reading cannot be the correct one, since it involves many textual and philosophical difficulties. Their interpretation, for instance, would require abandoning Aristotle's requirement that only a transparent substance is suitable matter for an eye. Likewise, their understanding of the Aristotle's doctrine of sensation as the reception of form without matter in DA 2.12 cannot be reconciled with other texts of his from On Generation and Corruption. An analysis of these texts, as well as DA 2.7 and De Sensu 6 on the roles of light and the transparent medium in vision, show that, for Aristotle, the physical processes which sense organs undergo are not standard qualitative changes (i.e. alterations), but activities or the actualizations of potencies in the material constituents of living animal bodies.