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PubMed1997

[Internet--a new informational and communication environment for medicine].

Availability of information and easy communication in a global network have made today's internet a prerequisite for scientific work and research in many disciplines. Internet has also become an important tool in many fields of applied science. The article presents examples how Internet influences development of medical science and practice: types of information available are presented, as well as some possibilities how the communication and information environment of the global Internet can be used for medicine.

Computer Communication Networks↗
PubMed2005

Social context, sexual networks, and racial disparities in rates of sexually transmitted infections.

BACKGROUND: Social context (demographic, socioeconomic, macroeconomic, and sociopolitical features of the environment) influences the epidemiology and consequences of individual behaviors that affect health outcomes. This article examines the role of social context in heterosexual networks that facilitate the spread of human immunodeficiency virus (HIV) infection and other sexually transmitted infections (STIs), particularly in relation to persistent racial disparities in rates of STIs in the United States. METHODS: Review of the medical, public health, and social science literature. RESULTS: Contextual factors, such as poverty, discrimination, epidemiology of illicit drug use in the community, ratio of men to women, incarceration rates, and racial segregation, influence sexual behavior and sexual networks directly and indirectly through a variety of mechanisms. Disparities in these contextual features likely contribute substantially to the persistence of marked racial disparities in rates of STIs. CONCLUSIONS: Given the importance of contextual factors and the sharply contrasting social contexts for blacks and whites, exclusive emphasis on individual risk factors and determinants is unlikely to produce solutions that will significantly decrease HIV rates among blacks. Effective HIV prevention in this population will require multidisciplinary research to address the contextual factors that promote patterns of sexual networks that facilitate transmission of STIs.

Adolescent↗
PubMed2001

Ecology. Tropical forest diversity--the plot thickens.

Also see the archival list of Science's Compass: Enhanced Perspectives ECOLOGY:Enhanced: Tropical Forest Diversity--The Plot Thickens David F. R. P. Burslem, Nancy C. Garwood, Sean C. Thomas Ecologists have long pondered why tropical forests contain such a huge number of species and what factors might be responsible for maintaining this diversity. In a Perspective, Burslem and colleagues discuss unique data sets from the forest dynamics plots (FDP) network, which shed light on the factors responsible for tropical forest diversity. D. F. R. P. Burslem is in the Department of Plant and Soil Science, University of Aberdeen, Aberdeen AB24 3UU, UK. E-mail: d.burslem@abdn.ac.uk. N. C. Garwood is in the Department of Botany, Natural History Museum, London SW7 5BD, UK. E-mail: ncg@nhm.ac.uk. S. C. Thomas is in the Faculty of Forestry, University of Toronto, Toronto M5S 3B3, Canada. E-mail: sc.thomas@utoronto.ca

Ecosystem↗
PubMed2000

Development of a System to Provide Full, Real-time Remote Control of a Scanning Electron Microscope across the Second Generation Internet: The Teaching SEM.

The development and makeup of a real-time full remote control system for the University of Michigan, Department of Materials Science and Engineering Teaching SEM is described. The instrument was initially controlled via the campus local area Ethernet network and cable TV network. The latest implementation employs Fast Ethernet, Asynchronous Transfer Mode (ATM) networks, and moving picture experts group (MPEG) video encoding to effect the remote control via the computer network alone. Remote control demonstrations from Washington, DC, Dearborn, MI, and Emerson School, Ann Arbor, MI are described.

Journal Article↗
PubMed2005

Formate binding near the redox-active tyrosineD in photosystem II: consequences on the properties of tyrD.

Formate and phosphate affect substantially the rate of tyrosine D (TyrD) oxidation and the stability of the radical TyrD* in Photosystem II [Hienerwadel R, Boussac A, Breton J and Berthomieu C (1996) Biochemistry 35: 15447-15460]. This observation prompted us to analyze the influence of formate and phosphate on the environment of TyrD using FTIR spectroscopy. The nu (CO) IR mode of TyrD* at 1503 cm-1 remains unchanged whatever the buffer used at pH 6 and whether formate is present or not in the sample. Similarly, the main IR mode of reduced TyrD remains at approximately 1250 cm-1 in all tested conditions. We thus conclude that formate does not modify the hydrogen-bonded interactions of TyrD and TyrD* with neighbouring D2His189 and D2Gln164. In the TyrD-state, an IR mode of formate significantly different from that observed in solution, is detected using 13C-formate, showing that formate forms a strong electrostatic interaction within PS II. The presence of formate affects also IR bands that may be assigned to an arginine side chain. Upon TyrD* formation, formate does not protonate but its binding interaction weakens. A proton uptake by Mes or phosphate buffer is detected, which is not observed when BisTris is used as a buffer. In these latter conditions, IR bands characteristic of the protonation of a carboxylate group of the protein are detected instead. The present IR data and the recent structural model of the TyrD environment proposed by Ferreira KN, Iverson TM, Maghlaoui K, Barber J and Iwata S [(2004) Science 303: 1831-1838], suggest that the proton released upon TyrD* formation is shared within a hydrogen bonding network including D2Arg294, and CP47Glu364 and that perturbation of this network by formate - possibly binding near D2Arg294 - substantially affects the properties of TyrD.

Amino Acid Sequence↗
PubMed1988

Scientific investigations at a lunar base.

Scientific investigations to be carried out at a lunar base can have significant impact on the location, extent, and complexity of lunar surface facilities. Among the potential research activities to be carried out are: (1) Lunar Science: Studies of the origin and history of the Moon and early solar system, based on lunar field investigations, operation of networks of seismic and other instruments, and collection and analysis of materials; (2) Space Plasma Physics: Studies of the time variation of the charged particles of the solar wind, solar flares and cosmic rays that impact the Moon as it moves in and out of the magnetotail of the Earth; (3) Astronomy: Utilizing the lunar environment and stability of the surface to emplace arrays of astronomical instruments across the electromagnetic spectrum to improve spectral and spatial resolution by several orders of magnitude beyond the Hubble Space Telescope and other space observatories; (4) Fundamental physics and chemistry: Research that takes advantage of the lunar environment, such as high vacuum, low magnetic field, and thermal properties to carry out new investigations in chemistry and physics. This includes material sciences and applications; (5) Life Sciences: Experiments, such as those that require extreme isolation, highly sterile conditions, or very low natural background of organic materials may be possible; and (6) Lunar environmental science: Because many of the experiments proposed for the lunar surface depend on the special environment of the Moon, it will be necessary to understand the mechanisms that are active and which determine the major aspects of that environment, particularly the maintenance of high-vacuum conditions. From a large range of experiments, investigations and facilities that have been suggested, three specific classes of investigations are described in greater detail to show how site selection and base complexity may be affected: (1) Extended geological investigation of a complex region up to 250 kilometers from the base requires long range mobility, with transportable life support systems and laboratory facilities for the analysis of rocks and soil. Selection of an optimum base site would depend heavily on an evaluation of the degree to which science objectives could be met. These objectives could include lunar cratering, volcanism, resource surveys or other investigations; (2) An astronomical observatory initially instrumented with a VLF radio telescope, but later expanding to include other instruments, requires site preparation capability, "line shack" life support systems, instrument maintenance and storage facilities, and sortie mode transportation. A site perpetually shielded from Earth is optimum for the advanced stages of a lunar observatory; (3) an experimental physics laboratory conducting studies requiring high vacuum facilities and heavily instrumented experiments, is not highly dependent on lunar location, but will require much more flexibility in experiment operation and EVA capability, and more sophisticated instrument maintenance and fabrication facilities.

Astronomical Phenomena↗
PubMed1996

A Decomposition Principle for Complexity Reduction of Artificial Neural Networks.

A decomposition principle is developed for systematic determination of the dimensionality and the connections of Hopfield-type associative memory networks. Given a set of high dimensional prototype vectors of given memory objects, we develop decomposition algorithms to extract a set of lower dimensional key features of the pattern vectors. Every key feature can be used to build an associative memory with the lowest complexity, and more than one key feature can be simultaneously used to build networks with higher recognition accuracy. In the latter case, we further propose a "decomposed neural network" based on a new encoding scheme to reduce the network complexity. In contrast to the original Hopfield network, the decomposed networks not only increase the network's storage capacity, but also reduce the network's connection complexity from quadratic to linear growth with the network dimension. Both theoretical analysis and simulation results demonstrate that the proposed principle is powerful. Copyright 1996 Elsevier Science Ltd

Journal Article↗
PubMed2000

North and South: bridging the information gap.

Information exchange is critical for development of health systems. The information needs of less-developed countries are especially challenging, but many factors inhibit free flow of knowledge. There is much talk about how technical fixes--such as the internet--might fill this information gap. Yet few attempts have been made to ask clinical investigators who work in resource-poor regions for their views on these difficulties and the possible solutions. The messages reported here, from a survey of Lancet editorial advisors, suggest that information, research, and publication capacities are intimately linked. Investigators, publishers, editors, and editorial organisations all have important parts to play in solving this global information poverty.

Africa↗
PubMed2006

Direct measurement of the impact of impaired erythrocyte deformability on microvascular network perfusion in a microfluidic device.

The ability of red blood cells (RBCs, erythrocytes) to deform and pass through capillaries is essential for continual flow of blood in the microvasculature, which ensures an adequate supply of oxygen and nutrients, prompt removal of metabolic waste products, transport of drugs and hormones, and traffic of circulating cells to and from all living tissues. This paper presents a novel tool for evaluating the impact of impaired deformability of RBCs on the flow of blood in the microvasculature by directly measuring perfusion of a test microchannel network with dimensions and topology similar to the real microcirculation. The measurement of microchannel network perfusion is compared with RBC filtration -- a conventional assay of RBC deformability. In contrast to RBC filterability, network perfusion depends linearly on RBC deformability modulated by graded exposure to glutaraldehyde, showing a higher sensitivity to small changes of deformability. The direct measurement of microchannel network perfusion represents a new concept for the field of blood rheology and should prove beneficial for basic science and clinical applications.

Erythrocyte Deformability↗
PubMed1998

[Biological calculation methods and their application in pharmaceutical science].

This article gives an introduction to certain mathematical methods, that were developed with biological processes as model. Three methods are described: clustering and the more recently developed genetic algorithms and neural nets. Mainly the last two methods were applied first outside the medical and biological domain but are now used also in the medical and pharmaceutical sciences. There are many applications in the drug discovery field, but these methods are also becoming increasingly important in other domains of the pharmaceutical sciences (such as pharmaceutical technologies).

Algorithms↗
PubMedDate not supplied

[Connectionist models of memory].

Even if computer science, at its birth, had strong links with the neurosciences, it is today mainly oriented toward efficiency and robustness. For example, memory in a computer has few relationships with memory in a living being. Nevertheless, some domains in computer science are interested in this kind of modelling. In particular, connectionism, whose goal is to elaborate artificial neural networks, uses a formalism for its calculus inspired from calculus in the brain. Different kinds of memory that can be emulated by artificial neural networks, inspired by statistics or biology, are presented here. Their relationships with human memory are discussed together with their tentative interest for the biologist or the therapist.

Humans↗