bluuebunny/crossref_metadata_2025_split huggingface dataset:
Liver Regeneration Enhanced by Orally Administered Ursodesoxycholic Acid is Mediated by Immunosuppression in Partially Hepatectomized Rats
Authors: Liu Lili , Sakaguchi Takeo , Cui Xing , Shirai Yoshio , Nishimaki Tadashi , Hatakeyama Katsuyoshi 
Published: July 2002

The relationship of liver regeneration to immunoactivity was examined after ursodesoxycholic acid (UDCA) administration to partially (about 66%) hepatectomized rats. The UDCA was given orally. Liver regeneration was evaluated by the hepatocyte mitotic index (MI) and immunoactivity by natural killer cell (NK) activity in the blood. When UDCA 12.5 mg/kg/day was administered, a significant increase in the MI was observed 2 and 3 days after hepatectomy, and the MI response 2 days after hepatectomy tended to be dose-dependent in the range of 0–25 mg/kg/day. NK activity was decreased 2 days after hepatectomy when UDCA was given, and a significant correlation between MI and NK activity was obtained. The increase in MI and decrease in NK activity was blocked completely or partially (respectively) by interleukin-2 administration. It was also noted that UDCA did not affect serum parameters indicating liver and kidney function. These findings suggest that liver regeneration can be modified by orally administered UDCA through a change in immunoactivity.
RECENT ADVANCES IN STRUCTURE SOLUTION FROM POWDER DIFFRACTION DATA
Authors: NEUMANN M. A. , LEUSEN F. J. J. , ENGEL G. E. , WILKE S. , CONESA-MORATILLA C. 
Published: July 2002

Crystal structure determination frequently is a prerequisite for the rational understanding of the solid state properties of new materials. Even though single crystal diffractometry is the method of choice when it comes to crystal structure determination, this approach is often impractical because of the difficulties involved in growing single crystals of appropriate size. High quality powder samples, on the other hand, are much easier to obtain. Using direct-space structure solution techniques, increasingly complex crystal structures can nowadays be solved directly from powder diffraction data. Combined with easy-to-use tools for model building and visualization as well as molecular mechanics and first principles Density Functional Theory (DFT) calculations, crystal structure solution from powder diffraction data is becoming a routine task. To illustrate the applicability of direct-space Monte Carlo techniques to the crystal structure solution of organic and inorganic compounds, a variety of structure solutions with the Powder Solve algorithm are presented. Recent advances include the determination of a preferred orientation correction during the structure solution search and the use of parallel tempering, a newly implemented global search algorithm. As a complementary technique, first principles DFT calculations have been used successfully to validate structure solutions and to aid the subsequent Rietveld refinement.
SIMULATION AND VISUALIZATION OF CNN DYNAMICS
Authors: HÄNGGI MARTIN , MOSER SIMON , PFAFFHAUSER ERIC , MOSCHYTZ GEORGE S. 
Published: July 2002

A new simulator for Cellular Neural Networks (CNNs) is presented. In contrast to other simulators, the CNN cells are visualized in a grid structure, the values of input and states being represented by colors. Input and initial images can easily be generated and changed even while the integration of the system is in progress, and an oscilloscope function allows the quantitative study of CNN transients, thus providing insight into the dynamics of the network. For those who are new to the world of CNNs, a series of predefined templates set and demonstrations are available, which makes the simulator a valuable educational tool. Advanced users and CNN expert can examine manually-entered and parametrized templates and carry out experiments in a very broad spectrum of CNN theory and applications, including quantitative behavior, robustness aspects, settling time, state limitations, different output functions and numerical integration methods. The simulator is written in Java and publicly available on WWW and will run on any Web browser of the newer generations.
LEARNING ITERATIVE IMAGE RECONSTRUCTION IN THE NEURAL ABSTRACTION PYRAMID
Authors: BEHNKE SVEN 
Published: July 2002

Successful image reconstruction requires the recognition of a scene and the generation of a clean image of that scene. We propose to use recurrent neural networks for both analysis and synthesis. The networks have a hierarchical architecture that represents images in multiple scales with different degrees of abstraction. The mapping between these representations is mediated by a local connection structure. We supply the networks with degraded images and train them to reconstruct the originals iteratively. This iterative reconstruction makes it possible to use partial results as context information to resolve ambiguities. We demonstrate the power of the approach using three examples: superresolution, fill-in of occluded parts, and noise removal/contrast enhancement. We also reconstruct images from sequences of degraded images.
Transaction chopping
Authors: Shasha Dennis , Llirbat Francois , Simon Eric , Valduriez Patrick 
Published: July 2002

Chopping transactions into pieces is good for performance but may lead to nonserializable executions. Many researchers have reacted to this fact by either inventing new concurrency-control mechanisms, weakening serializability, or both. We adopt a different approach. We assume a user who
—has access only to user-level tools such as (1) choosing isolation degrees 1ndash;4, (2) the ability to execute a portion of a transaction using multiversion read consistency, and (3) the ability to reorder the instructions in transaction programs; and
—knows the set of transactions that may run during a certain interval (users are likely to have such knowledge for on-line or real-time transactional applications).

Given this information, our algorithm finds the finest chopping of a set of transactions TranSet with the following property:
If the pieces of the chopping execute serializably, then TranSet executes serializably
. This permits users to obtain more concurrency while preserving correctness. Besides obtaining more intertransaction concurrency, chopping transactions in this way can enhance intratransaction parallelism.

The algorithm is inexpensive, running in
O(n×(e+m))
time, once conflicts are identified, using a naive implementation, where
n
is the number of concurrent transactions in the interval,
e
is the number of edges in the conflict graph among the transactions, and
m
is the maximum number of accesses of any transaction. This makes it feasible to add as a tuning knob to real systems.
Locking granularity revisited
Authors: Ries Daniel R. , Stonebraker Michael R. 
Published: July 2002

Locking granularity refers to the size and hence the number of locks used to ensure the consistency of a database during multiple concurrent updates. In an earlier simulation study we concluded that coarse granularity, such as area or file locking, is to be preferred to fine granularity such as individual page or record locking.
However, alternate assumptions than those used in the original paper can change that conclusion. First, we modified the assumptions concerning the placement of the locks on the database with respect to the accessing transactions. In the original model the locks were assumed to be well placed. Under worse case and random placement assumptions when only very small transactions access the database, fine granularity is preferable.
Second, we extended the simulation to model a lock hierarchy where large transactions use large locks and small transactions use small locks. In this scenario, again under the random and worse case lock placement assumptions, fine granularity is preferable if all transactions accessing more than 1 percent of the database use large locks.
Finally, the simulation was extended to model a “claim as needed” locking strategy together with the resultant possibility of deadlock. In the original study all locks were claimed in one atomic operation at the beginning of a transaction. The claim as needed strategy does not change the conclusions concerning the desired granularity.
An Analysis of Some Graph Theoretical Cluster Techniques
Authors: Augustson J. Gary , Minker Jack 
Published: July 2002

Several graph theoretic cluster techniques aimed at the automatic generation of thesauri for information retrieval systems are explored. Experimental cluster analysis is performed on a sample corpus of 2267 documents. A term-term similarity matrix is constructed for the 3950 unique terms used to index the documents. Various threshold values,
T
, are applied to the similarity matrix to provide a series of binary threshold matrices. The corresponding graph of each binary threshold matrix is used to obtain the term clusters.

Three definitions of a cluster are analyzed: (1) the connected components of the threshold matrix; (2) the maximal complete subgraphs of the connected components of the threshold matrix; (3) clusters of the maximal complete subgraphs of the threshold matrix, as described by Gotlieb and Kumar.
Algorithms are described and analyzed for obtaining each cluster type. The algorithms are designed to be useful for large document and index collections. Two algorithms have been tested that find maximal complete subgraphs. An algorithm developed by Bierstone offers a significant time improvement over one suggested by Bonner.

For threshold levels
T
≥ 0.6, basically the same clusters are developed regardless of the cluster definition used. In such situations one need only find the connected components of the graph to develop the clusters.
Application of the Diffusion Approximation to Queueing Networks I: Equilibrium Queue Distributions
Authors: Kobayashi Hisashi 
Published: July 2002

The practical value of queueing theory in engineering applications such as in computer modeling has been limited, since the interest in mathematical tractability has almost always led to an oversimplified model. The diffusion process approximation is an attempt to break away from the vogue in queueing theory.
The present paper introduces a vector-valued normal process and its diffusion equation in order to obtain an approximate solution to the joint distribution of queue lengths in a general network of queues. In this model, queueing processes of various service stations which interact with each other are approximated by a vector-valued Wiener process with some appropriate boundary conditions. Some numerical examples are presented and compared with Monte Carlo simulation results. A companion paper, Part II, discusses transient solutions via the diffusion approximation.
Glypnir—a programming language for Illiac IV
Authors: Lawrie D. H. , Layman T. , Baer D. , Randal J. M. 
Published: July 2002

GLYPNIR is one of the earliest existing languages designed for programming the Illiac IV computer. The syntax of the language is based on ALGOL 60, but has been extended to allow the programmer explicitly to specify the parallelism of his algorithm in terms of 64-word vectors.
This paper describes the characteristics, goals, and philosophy of the language, and discusses some of the problems associated with parallel computer architectures.
Algorithm 682: Talbot's method of the Laplace inversion problems
Authors: Murli A. , Rizzardi M. 
Published: July 2002

We describe a FORTRAN implementation, and some related problems, of Talbot's method which numerically solves the inversion problem of almost arbitrary Laplace transforms by means of special contour integration.
The basic idea is to take into account computer precision to derive a special contour where integration will be carried out.
FROM CHEMISTRY TO BIOCHEMISTRY TO CATALYSIS TO MOVEMENT
Authors: Jencks William P. 
Published: July 2002

Mechanisms of chemical reactions can often be predicted by determining the dependence of the lifetime of reaction intermediates on the structure of the reactants. When there is no lifetime in the presence of another reactant or catalyst the reaction proceeds through an enforced concerted mechanism. Noncovalent binding interactions between enzymes and their substrates provide a major contribution to catalysis by decreasing entropy and by destabilizing the ground state relative to the transition state, as well as by covalent and noncovalent chemical interactions with the substrate. Movement in biological systems, such as muscle contraction and the active transport of ions, is generally brought about through a series of alternating chemical and vectorial steps that involve a series of changes in the specificity for catalysis of the chemical and vectorial reactions. These changes divide the overall reaction into segments so that neither the chemical nor the vectorial reaction will be completed unless the other is also completed.
ENVIRONMENTAL ECOLOGY OF CRYPTOSPORIDIUM AND PUBLIC HEALTH IMPLICATIONS
Authors: Rose Joan B. 
Published: July 2002

▪ Abstract  Cryptosporidium has become the most important contaminant found in drinking water and is associated with a high risk of waterborne disease particularly for the immunocompromised. There have been 12 documented waterborne outbreaks in North America since 1985; in two of these (Milwaukee and Las Vegas) mortality rates in the immunocompromised ranged from 52% to 68%. The immunofluorescence antibody assay (IFA) using epifluorescence microscopy has been used to examine the occurrence of Cryptosporidium in sewage (1 to 120 oocysts/liter), filtered secondary treated wastewater (0.01 to 0.13 oocysts/liter), surface waters (0.001 to 107 oocysts/liter), groundwater (0.004 to 0.922 oocysts/liter) and treated drinking water (0.001 to 0.72 oocysts/liter). New rules are being developed (Information Collection Rule and Enhanced Surface Water Treatment Rule) to obtain more occurrence data for drinking water systems for use with new risk assessment models. Public health officials should consider a communication program to physicians treating the immunocompromised, nursing homes, develop a plan to evaluate cases of cryptosporidiosis in the community, and contribute to the development of public policies that limit contamination of source waters, improve water treatment, and protect public health.
A NATIONAL STRATEGY FOR RESEARCH AND DEVELOPMENT:Lessons from England
Authors: Black Nick 
Published: July 2002

▪ Abstract  Increasing concern about the state of basic and clinical research in England during the 1980s led to an influential parliamentary review. Surprisingly, the review recommended the strengthening of public health and health services research through the establishment of a research and development (R&D) program for the National Health Service (NHS). The program that started in 1991 was unique in that it was fully integrated into the management structure of the NHS. No country had ever attempted such an ambitious approach. While a review of the first five years of the program reveals many achievements, it also raises several concerns: Debate about the philosophy and aims of the program continues; the need to maintain political support requires constant attention; policy changes in other areas need to be accommodated; central control of a national, coordinated R&D program has to be guarded; methods of priority setting need to be enhanced; insufficient human resources to run the program have to be contended with; and the program needs to be rigorously evaluated. Other countries with a unified health system could learn much from the English experience. Countries with pluralist systems might benefit from specific parts of the experience.
No Right to Speak? The Relationship between Object Naming and Semantic Impairment:Neuropsychological Evidence and a Computational Model
Authors: Ralph M. A. Lambon , McClelland J. L. , Patterson K. , Galton C. J. , Hodges J. R. 
Published: July 2002

Abstract
The processes required for object naming were addressed in a study of patients with semantic dementia (a selective decline of semantic memory resulting from progressive temporal lobe atrophy) and in a computational model of single-word production. Although all patients with semantic dementia are impaired in both single-word production and comprehension, previous reports had indicated two different patterns: (a) a parallel decline in accuracy of naming and comprehension, with frequent semantic naming errors, suggesting a purely semantic basis for the anomia and (b) a dramatic progressive anomia. Longitudinal data for 16 patients with semantic dementia reflected these two profiles, but with the following additional important specifications: (1)despite a few relatively extreme versions of one or other profile, the full set of cases formed a continuum in the extent of anomia for a given degree of degraded comprehension; (2) the degree of disparity between these two abilities was associated with relative asymmetry in laterality of atrophy: a parallel decline in the two measures characterized patients with greater right-than left-temporal atrophy, while disproportionate anomia occurred with a predominance of atrophy in the left-temporal lobe. In an implemented computational model of naming, semantic representations were distributed across simulated left-and right-temporal regions, but the semantic units on the left were more strongly connected to left-lateralized phonological representations. Asymmetric damage to semantic units reproduced the longitudinal patient profiles of naming relative to comprehension, plus additional characteristics of the patients' naming performance. On the basis of both the neuropsychological and computational evidence, we propose that semantic impairment alone can account for the full range of word production deficits described here.
An Electrophysiological Analysis of the Time Course of Conceptual and Syntactic Encoding during Tacit Picture Naming
Authors: Schmitt Bernadette M. , Schiltz Kolja , Zaake Wanda , Kutas Marta , Münte Thomas F. 
Published: July 2002

Abstract
A central question in psycholinguistic research is when various types of information involved in speaking (conceptual/ semantic, syntactic, and phonological information) become available during the speech planning process. Competing theories attempt to distinguish between parallel and serial models. Here, we investigated the relative time courses of conceptual and syntactic encoding in a tacit picture-naming task via event-related brain potential (ERP) recordings. Participants viewed pictures and made dual-choice go/no-go decisions based on conceptual features (whether the depicted item was heavier or lighter than 500 g) and syntactic features (whether the picture's German name had feminine or masculine syntactic gender). In support of serial models of speech production, both the lateralized readiness potential, or LRP (related to response preparation), and the N200 (related to response inhibition) measures indicated that conceptual processing began approximately 80 msec earlier than syntactic processing.
Automatic and Controlled Processing of Melodic Contour and Interval Information Measured by Electrical Brain Activity
Authors: Trainor Laurel J. , McDonald Kelly L. , Alain Claude 
Published: July 2002

Abstract
Most work on how pitch is encoded in the auditory cortex has focused on tonotopic (absolute) pitch maps. However, melodic information is thought to be encoded in the brain in two different “relative pitch” forms, a domain-general contour code (up/down pattern of pitch changes) and a music-specific interval code (exact pitch distances between notes). Event-related potentials were analyzed in nonmusicians from both passive and active oddball tasks where either the contour or the interval of melody—final notes was occasionally altered. The occasional deviant notes generated a right frontal positivity peaking around 350 msec and a central parietal P3b peaking around 580 msec that were present only when participants focused their attention on the auditory stimuli. Both types of melodic information were encoded automatically in the absence of absolute pitch cues, as indexed by a mismatch negativity wave recorded during the passive conditions. The results indicate that even in the absence of musical training, the brain is set up to automatically encode music-specific melodic information, even when absolute pitch information is not available.
Efficient Event-Driven Simulation of Large Networks of Spiking Neurons and Dynamical Synapses
Authors: Mattia Maurizio , Giudice Paolo Del 
Published: July 2002

A simulation procedure is described for making feasible large-scale simulations of recurrent neural networks of spiking neurons and plastic synapses. The procedure is applicable if the dynamic variables of both neurons and synapses evolve deterministically between any two successive spikes. Spikes introduce jumps in these variables, and since spike trains are typically noisy, spikes introduce stochasticity into both dynamics. Since all events in the simulation are guided by the arrival of spikes, at neurons or synapses, we name this procedure event-driven. The procedure is described in detail, and its logic and performance are compared with conventional (synchronous) simulations. The main impact of the new approach is a drastic reduction of the computational load incurred upon introduction of dynamic synaptic efficacies, which vary organically as a function of the activities of the pre- and postsynaptic neurons. In fact, the computational load per neuron in the presence of the synaptic dynamics grows linearly with the number of neurons and is only about 6% more than the load with fixed synapses. Even the latter is handled quite efficiently by the algorithm. We illustrate the operation of the algorithm in a specific case with integrate-and-fire neurons and specific spike-driven synaptic dynamics. Both dynamical elements have been found to be naturally implementable in VLSI. This network is simulated to show the effects on the synaptic structure of the presentation of stimuli, as well as the stability of the generated matrix to the neural activity it induces.
A Virtual Environment Testbed for Training Laparoscopic Surgical Skills
Authors: Tendick Frank , Downes Michael , Goktekin Tolga , Cavusoglu Murat Cenk , Feygin David , Wu Xunlei , Eyal Roy , Hegarty Mary , Way Lawrence W. 
Published: July 2002

With the introduction of minimally invasive techniques, surgeons must learn skills and procedures that are radically different from traditional open surgery. Traditional methods of surgical training that were adequate when techniques and instrumentation changed relatively slowly may not be as efficient or effective in training substantially new procedures. Virtual environments are a promising new medium for training. This paper describes a testbed developed at the San Francisco, Berkeley, and Santa Barbara campuses of the University of California for research in understanding, assessing, and training surgical skills. The testbed includes virtual environments for training perceptual motor skills, spatial skills, and critical steps of surgical procedures. Novel technical elements of the testbed include a four-DOF haptic interface, a fast collision detection algorithm for detecting contact between rigid and deformable objects, and parallel processing of physical modeling and rendering. The major technical challenge in surgical simulation to be investigated using the testbed is the development of accurate, real-time methods for modeling deformable tissue behavior. Several simulations have been implemented in the testbed, including environments for assessing performance of basic perceptual motor skills, training the use of an angled laparoscope, and teaching critical steps of the cholecystectomy, a common laparoscopic procedure. The major challenges of extending and integrating these tools for training are discussed.