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PubMed2004

The simultaneous evolution of author and paper networks.

There has been a long history of research into the structure and evolution of mankind's scientific endeavor. However, recent progress in applying the tools of science to understand science itself has been unprecedented because only recently has there been access to high-volume and high-quality data sets of scientific output (e.g., publications, patents, grants) and computers and algorithms capable of handling this enormous stream of data. This article reviews major work on models that aim to capture and recreate the structure and dynamics of scientific evolution. We then introduce a general process model that simultaneously grows coauthor and paper citation networks. The statistical and dynamic properties of the networks generated by this model are validated against a 20-year data set of articles published in PNAS. Systematic deviations from a power law distribution of citations to papers are well fit by a model that incorporates a partitioning of authors and papers into topics, a bias for authors to cite recent papers, and a tendency for authors to cite papers cited by papers that they have read. In this TARL model (for topics, aging, and recursive linking), the number of topics is linearly related to the clustering coefficient of the simulated paper citation network.

Authorship↗
PubMed2000

Biopsy versus resection for malignant glioma.

BACKGROUND: Patients with isolated supratentorial brain tumours, presumed to be primary on imaging, have two surgical management options - biopsy or resection. Surgical opinions appear to be equally divided when considering the relative risks and benefits of these two procedures. OBJECTIVES: To estimate the clinical effectiveness of radical surgical resection compared to simple biopsy in patients with malignant glioma. SEARCH STRATEGY: Electronic database searches of COCHRANE CONTROLLED TRIALS REGISTER (including the Cochrane Cancer Network Specialised Register of Trials), MEDLINE, CANCERLIT, EMBASE, BIOSIS and SCIENCE CITATION INDEX. Hand searching the references of all identified studies; hand searching the Journal of Neuro-Oncology over the previous 10 years, including all conference abstracts; personal communication. SELECTION CRITERIA: Randomised and clinical controlled trials were included if they compared biopsy to resection, or looked at effect of extent of resection on survival, time to progression or quality of life, for malignant glioma patients of all ages. DATA COLLECTION AND ANALYSIS: Studies were to be identified, critically appraised and data extracted by the author (SEM). For dichotomous data, Peto odds ratios (OR) with 95% confidence intervals (CI) were hoped to have been estimated. Normal continuous data were to have been summated using the weighted mean difference (WMD). MAIN RESULTS: The electronic database search yielded 2100 citations. Of these, two articles were identified for possible inclusion, however both were excluded. The hand search and personal communication were similarly unproductive. No studies were included in the review and no data was synthesised. REVIEWER'S CONCLUSIONS: Given that no qualifying studies were identified and because this is an important issue, both in terms of patient risk and benefit and health economics, the author feels it important to conduct a randomised controlled trial in this subject.

Biopsy↗
PubMed1998

Role of the SEAMEO TROPMED Network in health human resources development. Southeast Asian Ministers of Education Organization. Tropical Medicine and Public Health.

The Southeast Asian Ministers of Education Organization (SEAMEO) is a chartered international organization for the promotion of regional cooperation in education, science, technology and culture. The Regional Tropical Medicine and Public Health Network (TROPMED) operates through four specialized Centers in Indonesia, Malaysia, the Philippines and Thailand, with a coordinating unit, the TROPMED Central Office in Bangkok, Thailand. In line with the overall mission of SEAMEO, the role of TROPMED is to promote health and to prevent or control disease, thus improving the quality of life of people in the Asia-Pacific Region. Toward this end, SEAMEO TROPMED serves to facilitate the strengthening of national and institutional capabilities in research and training through postgraduate academic programs; short-term training courses; scientific fora; publications and information dissemination and as such, has been in the mainstream of health human resources development since its inception in 1967. To date, a total of 3,353 TROPMED alumni have benefited from training in 26 regular course offerings; of these, 1,596 were females and 1,757, males. From 1991 to 1995, a total of 434 key health personnel have attended short-term training courses, with increasing attendance from Cambodia, Lao PDR and Vietnam. TROPMED's effectiveness comes from the collective strength of and the spirit of cooperation among its host institutions and partners. Faced with a health scenario of both developing and developed economies, SEAMEO TROPMED aims to further its role as an international forum for health development thus, addressing the need for effective strategies for health sector reform and advocacy of relevant health, environmental and development policies through its various programs and activities.

Asia, Southeastern↗
PubMed1998

Use of a constraint satisfaction network model for the evaluation of the methadone treatments of drug addicts.

Constraint Satisfaction Networks were used by Semeion, a Research Center of Science of Communication, in order to analyze drug-addict patient data files, provided by the Jerusalem Methadone Treatment Center. The short and partial analysis carried out in this article is presented to show how this high technology can be a support for treatment staff in order to improve the quality and the timeliness of the necessary intervention with patients. One of the problems for which the networks could offer support is, for example, the individuation or "matching" of the most suitable therapy for the patient during the treatment planning phase. In this field the networks need to analyze data files of patients in therapy at different centers, with the results collected after many years of observation. What follows, obviously, only has demonstrative values.

Adult↗
PubMed2004

High-frequency ventilation versus conventional ventilation for treatment of acute lung injury and acute respiratory distress syndrome.

BACKGROUND: High-frequency ventilation is often used to treat patients with acute lung injury (ALI) or acute respiratory distress syndrome (ARDS) but the effect of this treatment on clinical outcomes has not been well established. OBJECTIVES: The objective of this review is to examine the effect of high-frequency ventilation compared with conventional ventilation as a therapy for ALI or ARDS in children (1 to 17 years old) and adults in order to quantify its effect on patient outcome (mortality, morbidity and other relevant outcomes). SEARCH STRATEGY: We searched the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, issue 4, 2002), MEDLINE (1966 to October Week 5, 2002), EMBASE (1980 to Week 51, 2002), World Wide Web (www.controlled-trials.com, ARDS clinical network), and used Cited Reference Search (Web of Science 1988 to 2002, for specific reference lists of articles). We also contacted authors from each included trial, as well as manufacturers of high-frequency ventilators and other researchers in the field. SELECTION CRITERIA: Randomized controlled clinical trials of children and adults comparing treatment using high-frequency ventilation with conventional ventilation for patients diagnosed with ALI or ARDS. DATA COLLECTION AND ANALYSIS: Two reviewers independently assessed trial quality and extracted data. Study authors were contacted for additional information. MAIN RESULTS: Two trials met the inclusion criteria for this review. One trial recruited children (including some children less than one year old) (n = 58) and the other recruited adults (n = 148). Both trials used a high-frequency oscillatory ventilator as the intervention and included variable use of lung-volume recruitment strategies. The intervention groups showed a trend towards lower 30 day mortality (children relative risk (RR) 0.83, 95% confidence interval (CI) 0.43 to 1.62; adults RR 0.72, 95% CI 0.50 to 1.03), although neither study showed a statistically significant difference. Similarly, there was no statistically significant difference between the intervention and control groups for 'Total length of ventilator days' (WMD) -2.00, 95% CI -18.36 to 14.36; and WMD 2.00, 95% CI -6.55 to 10.55 for the child and adult trials respectively). The studies used only proxies to measure long-term quality of life. There was a statistically significant reduction in the risk of requiring supplemental oxygen amongst survivors at 30 days in the paediatric study (RR 0.36, 95% CI 0.14 to 0.93). REVIEWER'S CONCLUSIONS: There is not enough evidence to conclude whether high-frequency ventilation reduces mortality or long-term morbidity in patients with ALI or ARDS; further trials are needed.

Adolescent↗
PubMed2006

Proteome informatics II: bioinformatics for comparative proteomics.

The present review attempts to cover the most recent initiatives directed towards representing, storing, displaying and processing protein-related data suited to undertake "comparative proteomics" studies. Data interpretation is brought into focus. Efforts invested into analysing and interpreting experimental data increasingly express the need for adding meaning. This trend is perceptible in work dedicated to determining ontologies, modelling interaction networks, etc. In parallel, technical advances in computer science are spurred by the development of the Web and the growing need to channel and understand massive volumes of data. Biology benefits from these advances as an application of choice for many generic solutions. Some examples of bioinformatics solutions are discussed and directions for on-going and future work conclude the review.

Algorithms↗
PubMed2005

A software solution for the control of visual behavioral experimentation.

Psychophysical and neurophysiological research requires precise control of experimental devices for the purpose of delivering stimuli and monitoring behavioral and neural responses. This has previously been accomplished by complex, often proprietary, programmable systems, interfacing with a limited range of hardware. We have developed a software solution entirely within the Matlab environment that can achieve high-speed control of experimental and behavioral variables. We make this Wake-Forest Visual Experimentation (WaVE) software freely available under the GNU public license, and demonstrate how to customize it to individual laboratory needs. WaVE takes advantage of existing Matlab libraries and toolboxes to present visual stimuli, collect experimental data, update behavioral variables, and communicate with other computers. Although we have developed it for use in a Windows-based Personal Computer, the portability of the Matlab code makes possible its customization for use in a variety of other systems. We present simulation results showing sub-millisecond sampling rate and updating precision, running on single-processor, desktop PCs. The WaVE software offers a simple, flexible and powerful solution that compares favorably with many of its costly alternatives.

Animals↗
PubMed2003

Neural connections that compute.

The UK's Foresight Cognitive Systems Project brings together researchers in the life sciences and physical sciences to see where they can learn from one another and to debate, and plan, the future of research in cognitive systems. The project, a part of the UK government's Foresight initiative, sets out to identify potential opportunities for the economy or society from new science and technology. Through a series of research reviews, the project has created 'snap shots' of research in cognitive systems. A major conference in Bristol in September will consider series of research manifestos created by interdisciplinary groups.

Cognition↗
PubMed1997

Variational Approach to Unsupervised Learning Algorithms of Neural Networks.

Variational approach in pattern recognition basing on a mean risk functional is applied to unsupervised learning algorithms for neural networks. The paper summarizes main statements and results of the approach: a structure of mean risk functionals relevant for the problem of grouping the multivariate data; optimum conditions; recurrent algorithms of stochastic approximation type for minimization of the functionals; and conditions ensuring convergence of the algorithms to appropriate solutions. Basing on this theory a general scheme is proposed and it allows to obtain neural networks whose adaptation laws arise as the recurrent unsupervised learning algorithms for suitably selected mean risk functionals. The well known Grossberg networks, counter-propagation networks, and Kohonen self-organizing networks are among them. Moreover the new variants of unsupervised-learning neural structures can be derived as it is demonstrated in the paper. The developed mathematical means can serve for theoretical justification of using such neural networks in data processing systems. Copyright 1997 Elsevier Science Ltd. All Rights Reserved.

Journal Article↗
PubMed1997

Training Dynamics and Neural Network Performance.

We use an analysis of a simple model of recurrent network dynamics to gain qualitative insights into the training dynamics of feedforward multilayer perceptrons (MLPs) used for classification. These insights suggest changes to the training methods used for MLPs that improve network performance significantly. In previous work, the probabilistic neural network (PNN) was shown to provide better zero-reject error performance on character and fingerprint classification problems than radial basis function and MLP-based neural network methods. We will show that performance equal to or better than PNN can be achieved with a single three-layer MLP by making fundamental changes in the network optimization strategy. These changes are: 1) use of neuron activation functions, which reduce the probability of singular Jacobians; 2) use of successive regularization to constrain the volume of the minimized weight space; 3) use of Boltzmann pruning to constrain the dimension of the weight space; 4) use of Prior class probabilities to normalize all error calculations, so that statistically significant samples of rare but important classes can be included without distorting the error surface. All four of these changes are made in the inner loop of a conjugate gradient optimization iteration and are intended to simplify the training dynamics of the optimization. On handprinted digits and fingerprint classification problems these modifications improve error-reject performance by factors between 2 and 4, and reduce network size by 40-60%. Copyright 1997 Elsevier Science Ltd.

Journal Article↗
PubMed1997

Estimates of the Number of Hidden Units and Variation with Respect to Half-Spaces.

We estimate variation with respect to half-spaces in terms of "flows through hyperplanes". Our estimate is derived from an integral representation for smooth compactly supported multivariable functions proved using properties of the Heaviside and delta distributions. Consequently we obtain conditions which guarantee approximation error rate of order O by one-hidden-layer networks with n sigmoidal perceptrons. Copyright 1997 Elsevier Science Ltd.

Journal Article↗
PubMed1997

Network Synthesis through Data-Driven Growth and Decay.

AN ALGORITHM FOR ADDITION AND DELETION (ADDEL) OF RESOURCES DURING LEARNING IS DEVELOPED TO ACHIEVE TWO GOALS: (1) to find feed-forward multilayer networks that are as small as possible, (2) to find an appropriate structure for such small networks. These goals are accomplished by operating alternately between an adding phase and a deleting phase while learning the given input-output associations. The adding phase develops a crude structure by filling in resources (connections, units and layers) at a virtual multilayer network with a maximum of L possible layers. The deleting phase then removes any unnecessary connections to obtain a refined structure. The additions and deletions are done based on a sensitivity measure and a corresponding probability rule so that only the synapses which are most effective in reducing the output error are preserved. A generalization error estimated from a validation set is used to control the alternation between the two learning phases and the termination of learning. Simulations, including handwritten digit recognition, demonstrate that the algorithm is effective in finding an appropriate network structure for a small network which can generalize well. The algorithm is used to investigate when the size of a network is important for generalization. Copyright 1997 Elsevier Science Ltd.

Journal Article↗
PubMed2004

[The "rehabilitation sciences" research funding programme: research findings -- implementation -- impact and perspectives].

In 1998, the German Federal Ministry of Education and Research (BMBF) and the German pension insurance scheme established a funding programme for research in rehabilitation. This "Rehabilitation Sciences" research funding programme comprises eight regional research networks for eight years in two periods (1998-2002, 2001-2005). In our paper we review the findings of the first funding period in five of the research fields: patient education, need for and access to rehabilitation, vocational training in medical rehabilitation to enhance return to work, comorbid mental disorders in patients with somatic diseases, and gender differences. Several activities aimed at transferring research findings into practice are outlined. Finally, the impact of the funding programme is summarized and perspectives for further funding are given.

Chronic Disease↗
PubMed1987

Temporal and social contexts of heroin-using populations. An illustration of the snowball sampling technique.

Snowball sampling is a method that has been used in the social sciences to study sensitive topics, rare traits, personal networks, and social relationships. The method involves the selection of samples utilizing "insider" knowledge and referral chains among subjects who possess common traits that are of research interest. It is especially useful in generating samples for which clinical sampling frames may be difficult to obtain or are biased in some way. In this paper, snowball samples of heroin users in two Dutch cities have been analyzed for the purpose of providing descriptions and limited inferences about the temporal and social contexts of their lifestyles. Two distinct heroin-using populations have been discovered who are distinguished by their life cycle stage. Significant contextual explanations have been found involving the passage from adolescent peer group to criminal occupation, the functioning of network "knots" and "outcroppings," and the frequency of social contact. It is suggested that the snowball sampling method may have utility in studying the temporal and social contexts of other populations of clinical interest.

Activities of Daily Living↗
PubMedDate not supplied

Hub-based simulation and graphics hardware accelerated visualization for nanotechnology applications.

The Network for Computational Nanotechnology (NCN) has developed a science gateway at nanoHUB.org for nanotechnology education and research. Remote users can browse through online seminars and courses, and launch sophisticated nanotechnology simulation tools, all within their web browser. Simulations are supported by a middleware that can route complex jobs to grid supercomputing resources. But what is truly unique about the middleware is the way that it uses hardware accelerated graphics to support both problem setup and result visualization. This paper describes the design and integration of a remote visualization framework into the nanoHUB for interactive visual analytics of nanotechnology simulations. Our services flexibly handle a variety of nanoscience simulations, render them utilizing graphics hardware acceleration in a scalable manner, and deliver them seamlessly through the middleware to the user. Rendering is done only on-demand, as needed, so each graphics hardware unit can simultaneously support many user sessions. Additionally, a novel node distribution scheme further improves our system's scalability. Our approach is not only efficient but also cost-effective. Only a half-dozen render nodes are anticipated to support hundreds of active tool sessions on the nanoHUB. Moreover, this architecture and visual analytics environment provides capabilities that can serve many areas of scientific simulation and analysis beyond nanotechnology with its ability to interactively analyze and visualize multivariate scalar and vector fields.

Computer Graphics↗
PubMed2007

Attention genes.

A major problem for developmental science is understanding how the cognitive and emotional networks important in carrying out mental processes can be related to individual differences. The last five years have seen major advances in establishing links between alleles of specific genes and the neural networks underlying aspects of attention. These findings have the potential of illuminating important aspects of normal development and its pathologies. We need to learn how genes and experience combine to influence the structure of neural networks and the efficiency with which they are exercised. Methods for addressing these issues are central to progress in the decade ahead.

Animals↗
PubMedDate not supplied

[Cyberspace and the negotiation of meaning: the social aspects of implementing digital communications networks in public health academic institutions].

This article analyzes social aspects in the incorporation of new information and communications technologies in public health academic institutions. To demarcate the study of these processes and demonstrate the close relationship between their social and technical aspects, the study employs concepts pertaining to "intellectual technologies" and a "critical theory of technology". Theoretical and methodological elements are identified to approach the implementation dynamics of electronic networks in public health institutions, through a discourse analysis of their social actors and the various meanings they attribute to such dynamics Considering discourse as an expression of the relations created during these implementation dynamics, the study seeks a proposal for the ways by which these relations might influence the social and technical dimensions of digital networks.

Computer Communication Networks↗