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PubMed1997

Discovering Neural Nets with Low Kolmogorov Complexity and High Generalization Capability.

Many neural net learning algorithms aim at finding "simple" nets to explain training data. The expectation is that the "simpler" the networks, the better the generalization on test data (--> Occam's razor). Previous implementations, however, use measures for "simplicity" that lack the power, universality and elegance of those based on Kolmogorov complexity and Solomonoff's algorithmic probability. Likewise, most previous approaches (especially those of the "Bayesian" kind) suffer from the problem of choosing appropriate priors. This paper addresses both issues. It first reviews some basic concepts of algorithmic complexity theory relevant to machine learing, and how the Solomonoff-Levin distribution (or universal prior) deals with the prior problem. The universal prior leads to a probabilistic method for finding "algorithmically simple" problem solutions with high generalization capability. The method is based on Levin complexity (a time-bounded generalization of Kolmogorov complexity) and inspired by Levin's optimal universal search algorithm. For a given problem, solution candidates are computed by efficient "self-sizing" programs that influence their own runtime and storage size. The probabilistic search algorithm finds the "good" programs (the ones quickly computing algorithmically probable solutions fitting the training data). Simulations focus on the task of discovering "algorithmically simple" neural networks with low Kolmogorov complexity and high generalization capability. It is demonstrated that the method, at least with certain toy problems where it is computationally feasible, can lead to generalization results unmatchable by previous neural network algorithms. Much remains to be done, however, to make large scale applications and "incremental learning" feasible. Copyright 1997 Elsevier Science Ltd.

Journal Article↗
PubMed2005

Entangled networks, synchronization, and optimal network topology.

A new family of graphs, entangled networks, with optimal properties in many respects, is introduced. By definition, their topology is such that it optimizes synchronizability for many dynamical processes. These networks are shown to have an extremely homogeneous structure: degree, node distance, betweenness, and loop distributions are all very narrow. Also, they are characterized by a very interwoven (entangled) structure with short average distances, large loops, and no well-defined community structure. This family of nets exhibits an excellent performance with respect to other flow properties such as robustness against errors and attacks, minimal first-passage time of random walks, efficient communication, etc. These remarkable features convert entangled networks in a useful concept, optimal or almost optimal in many senses, and with plenty of potential applications in computer science or neuroscience.

Animals↗
PubMed2001

Nutrition education and promotion in primary schools.

Health promotion with school-age children can enhance knowledge about nutrition and change eating habits when health workers, schools, and communities work together for a common goal. A range of options need to be considered when designing an effective and appropriate school-based program.

Australia↗
PubMed2002

The inflammatory network.

In the last few years the findings on allergic inflammation have improved, particularly in cellular signaling. Now we know that cytokines and other mediators are a network able to regulate the allergic inflammation (and inflammation in general). The new findings are important not only for basic science but also for the development of new therapeutic approaches to allergic diseases.

Humans↗
PubMed2005

[New field for the clinical laboratory].

As for clinical inspections, new developments in response to contemporary needs are required during the current rapid medical reforms. Blood inspections now relate to advanced medical fields (such as transplantation, and regeneration medicine), and high skills in these technologies will be in demand from now on. Because of this, it is important to learn the most advanced life engineering technology and to promote blood transfusion inspection, genetic inspection, and so on to enrich it. In particular, bioinfomatics is the field which should be actively advanced because of the tailor-made medical realization, it requires statistical techniques and genome information control studies. Additionally participation in clinical trials (CRC) becomes possible for the execution of the clinical research. These advances are opening up new opportunities in hospitals not only for business expansion as centers for clinical test inspections but also in medicine manufacture, and food company and related inspections. Furthermore, as information network-making that makes the most of medical information and information technology is developed, along with development of the health science field, it is expected that inspection coordinators who build up the relations with hospitals and the area's medical fields will part in the future medical treatment team. Therefore, the maintenance of an educational environment where these skills can be attained is a pressing need so that it may be developed as a new medical field.

Clinical Laboratory Techniques↗
PubMed2005

[Strategies of medical self-authorization in early modern medicine: the example of Volcher Coiter (1534-1576)].

Based on the example of Volcher Coiter--a town physician at Nuremberg and one of the leading anatomists in early modern medicine--, this essay points out that the authoritative status of contemporary physicians mainly was predicated on an interplay of self-fashioning and outside perception. It provides ample evidence that Coiter made use of several characteristic rhetorical and discourse-related strategies of self-authorisation such as the participation in social networks, a highly convincing technique of self-fashioning by emphasizing particular erudition, the presentation of academic medicine as a science authorised by god and the concurrent devaluation of non-academic healers. Furthermore, graphic and visual strategies of self-authorisation could be ascertained: Coiter took care for a premium typography of his books. He also used his talent as a graphic artist in his books to visualise his medical concepts. Moreover, the so-called 'Nuremberg Portrait' of Coiter served to illustrate his outstanding authority.

Credentialing↗
PubMed2005

The flexible evolutionary anchorage-dependent Pardee's restriction point of mammalian cells: how its deregulation may lead to cancer.

Living cells oscillate between the two states of quiescence and division that stand poles apart in terms of energy requirements, macromolecular composition and structural organization and in which they fulfill dichotomous activities. Division is a highly dynamic and energy-consuming process that needs be carefully orchestrated to ensure the faithful transmission of the mother genotype to daughter cells. Quiescence is a low-energy state in which a cell may still have to struggle hard to maintain its homeostasis in the face of adversity while waiting sometimes for long periods before finding a propitious niche to reproduce. Thus, the perpetuation of single cells rests upon their ability to elaborate robust quiescent and dividing states. This led yeast and mammalian cells to evolve rigorous Start [L.H. Hartwell, J. Culotti, J. Pringle, B.J. Reid, Genetic control of the cell division cycle in yeast, Science 183 (1974) 46-51] and restriction (R) points [A.B. Pardee, A restriction point for control of normal animal cell proliferation, Proc. Natl. Acad. Sci. U. S. A. 71 (1974) 1286-1290], respectively, that reduce deadly interferences between the two states by enforcing their temporal insulation though still enabling a rapid transition from one to the other upon an unpredictable change in their environment. The constitutive cells of multi-celled organisms are extremely sensitive in addition to the nature of their adhering support that fluctuates depending on developmental stage and tissue specificity. Metazoan evolution has entailed, therefore, the need for exceedingly flexible anchorage-dependent R points empowered to assist cells in switching between quiescence and division at various times, places and conditions in the same organism. Programmed cell death may have evolved concurrently in specific contexts unfit for the operation of a stringent R point that increase the risk of deadly interferences between the two states (as it happens notably during development). But, because of their innate flexibility, anchorage-dependent R points have also the ability to readily adjust to a changing structural context so as to give mutated cells a chance to reproduce, thereby encouraging tumor genesis. The Rb and p53 proteins, which are regulated by the two products of the Ink4a-Arf locus [C.J. Sherr, The INK4a/ARF network in tumor suppression, Nat. Rev., Mol. Cell Biol. 2 (2001) 731-737], govern separable though interconnected pathways that cooperate to restrain cyclin D- and cyclin E-dependent kinases from precipitating untimely R point transit. The expression levels of the Ink4a and Arf proteins are especially sensitive to changes in cellular shape and adhesion that entirely remodel at the time when cells shift between quiescence and division. The Arf proteins further display an extremely high translational sensitivity and can activate the p53 pathway to delay R point transit, but, only when released from the nucleolus, 'an organelle formed by the act of building a ribosome' [T. Mélèse, Z. Xue, The nucleolus: an organelle formed by the act of building a ribosome, Curr. Opin. Cell Biol. 7 (1995) 319-324]. In this way, the Ink4a/Rb and Arf/p53 pathways emerge as key regulators of anchorage-dependent R point transit in mammalian cells and their deregulation is, indeed, a rule in human cancers. Thus, by selecting the nucleolus to mitigate cell cycle control by the Arf proteins, mammalian cells succeeded in forging a highly flexible R point enabling them to match cell division with a growth rate imposed by factors controlling nucleolar assembling, such as nutrients and adhesion. It is noteworthy that nutrient control of critical size at Start in budding yeast has been shown recently to be governed by a nucleolar protein interaction network [P. Jorgensen, J.L. Nishikawa, B.-J. Breitkreutz, M. Tyers, Systematic identification of pathways that couple cell growth and division in yeast, Science 297 (2002) 395-400].

ADP-Ribosylation Factors↗
PubMed1996

Unity in diversity: toward a common professional vision of health sciences librarianship.

A redefinition of librarianship is necessary to respond to the ever-changing environment. Librarians must view their profession more broadly, because they are part of a network of relationships. To meet these challenges, health information professionals must commit to spending the time necessary to engage in both professional and personal growth.

Computer Communication Networks↗
PubMed2004

Potential assessment of a neural network model with PCA/RBF approach for forecasting pollutant trends in Mong Kok urban air, Hong Kong.

The forecasting of air pollutant trends has received much attention in recent years. It is an important and popular topic in environmental science, as concerns have been raised about the health impacts caused by unacceptable ambient air pollutant levels. Of greatest concern are metropolitan cities like Hong Kong. In Hong Kong, respirable suspended particulates (RSP), nitrogen oxides (NOx), and nitrogen dioxide (NO2) are major air pollutants due to the dominant usage of diesel fuel by commercial vehicles and buses. Hence, the study of the influence and the trends relating to these pollutants is extremely significant to the public health and the image of the city. The use of neural network techniques to predict trends relating to air pollutants is regarded as a reliable and cost-effective method for the task of prediction. The works reported here involve developing an improved neural network model that combines both the principal component analysis technique and the radial basis function network and forecasts pollutant tendencies based on a recorded database. Compared with general neural network models, the proposed model features a more simple network architecture, a faster training speed, and a more satisfactory prediction performance. The improved model was evaluated with hourly time series of RSP, NOx and NO2 concentrations monitored at the Mong Kok Roadside Gaseous Monitory Station in Hong Kong during the year 2000 and proved to be effective. The model developed is a potential tool for forecasting air quality parameters and is superior to traditional neural network methods.

Air Pollutants↗
PubMed2002

Adjusting to progress: interactions between the National Library of Medicine and health sciences librarians, 1961-2001.

Most health sciences librarians would agree that the National Library of Medicine's (NLM's) leadership and its services have been highly beneficial to the field, but this does not prevent specific NLM actions--or lack of action--from being perceived as annoying or infuriating. Over the past forty years, NLM's interactions with health sciences librarians have been affected by significant additions to NLM's mission and services, the expansion of NLM's direct user groups, and the growing range of possible relationships between health sciences librarians and NLM. The greatest friction between NLM and health services librarians occurs when there is a fundamental change in the way NLM carries out its mission-a change that adds to the web of relationships that link librarians and NLM and prompts corresponding changes in the way other libraries do business. Between 1961 and 2001, there were two such fundamental changes: the implementation of the National Network of Libraries of Medicine and the development and promotion of services targeted toward individual health professionals. On a lesser scale, each new service that connects NLM and health sciences librarians is another potential source of irritation, ready to flare up when the service is interrupted, changed, or eliminated. Other factors--including strong personalities, mistakes, and poor communication--add to, but do not cause, the intermittent problems between NLM and its most longstanding and engaged user group. These problems are in essence the price we pay for the leadership and vision of NLM's directors and for NLM's success in developing excellent services and in enhancing them based on advice from librarians and other users.

History, 20th Century↗
PubMed1995

Twenty-first-century science.

Scientific life is changing in fundamental ways as the twenty-first century approaches. Advances in technology are changing methods of scientific communications and dissemination of information, while diminishing resources lead to stabilization, politicization, increased public oversight, and the potential for significant downsizing. Libraries can foster the crucial interdisciplinary connections necessary to forge a new vision of scholarship.

Computer Communication Networks↗
PubMed2000

Hybrid Petri net representation of gene regulatory network.

It is important to provide a representation method of gene regulatory networks which realizes the intuitions of biologists while keeping the universality in its computational ability. In this paper, we propose a method to exploit hybrid Petri net (HPN) for representing gene regulatory networks. The HPN is an extension of Petri nets which have been used to represent many kinds of systems including stochastic ones in the field of computer sciences and engineerings. Since the HPN has continuous and discrete elements, it can easily handle biological factors such as protein and mRNA concentrations. We demonstrate that, by using HPNs, it is possible to translate biological facts into HPNs in a natural manner. It should be also emphasized that a hierarchical approach is taken for our construction of the genetic switch mechanism of lambda phage which is realized by using HPNs. This hierarchical approach with HPNs makes easier the arrangement of the components in the gene regulatory network based on the biological facts and provides us a prospective view of the network. We also show some computational results of the protein dynamics of the lambda phage mechanism that is simulated and observed by implementing the HPN on a currently available tool.

Bacteriophage lambda↗