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PubMed2005

Processing of conflicting cues in an attention-shift paradigm studied with fMRI.

We investigated the effects of conflicting cues in visual attention on brain function, based on a modified version of the Posner cue-target paradigm. The classic paradigm utilizes either a peripheral or centrally placed cue that involuntary or voluntary results in a shift of attention to the cued side. The modified paradigm involves presenting both a peripheral and central cue at the same time, but where the two cues convey conflicting information regarding direction of attention. Functional magnetic resonance imaging (fMRI) were used to record neuronal activation in localized brain areas and networks when the subjects performed the attention task. We hypothesized that the 'exogenous invalid/endogenous valid' condition would activate the anterior attention system to a larger extent than the 'exogenous valid/endogenous invalid' condition, reflecting a need for top-down information processing in this condition. The results for performance data showed that the peripheral cue took precedence over the centrally placed cue when the two cues were in conflict, since reaction times were significantly longer in the "exogenous invalid/endogenous valid" condition. The fMRI data showed an increase in activation in the visual cortex, the left parietal lobule, and in the left cingulate gyrus in both the exogenous valid/endogenous invalid and exogenous invalid/endogenous valid conditions. For the exogenous invalid/endogenous valid condition, there were, in addition, significant activations also in the inferior and middle frontal gyri, and in the precentral gyrus. We interpret these findings as reflecting that these brain areas particularly involved in top-down modulation of attention that interferes with a bottom-up, exogenous-driven effect.

Adult↗
PubMed2000

Twenty year follow-up of a cohort based in general practices in 24 British towns.

BACKGROUND: A national prospective study of cardiovascular disease (CVD) was set up in 1978 to explain the reasons for the marked geographical variation in CVD rates in Great Britain. A total of 7735 males, aged 40-59 years (born between 1919 and 1939) randomly selected from one general practice age-sex register in each of 24 towns, responded to a screening invitation from their general practitioner (GP) and were examined in 1978-1980. We describe the methods used and the contact maintained after following a cohort for 20 years. METHODS: The established system of patient registration with a GP was used for tracing and maintaining contact with a low-mobility cohort through local area health authority networks and the National Health Service Central Register. RESULTS: By 31 December 1997, there were 1856 recorded deaths (14 known to have occurred abroad), 66 emigrations/ living overseas/lost from follow-up. In addition, 1500 study subjects had registered with new GPs who, every 2 years, provided information on both fatal and non-fatal cardiovascular events to complement information supplied by the original practices. Information was obtained on all cardiovascular events and deaths for 99.5 per cent of the surviving sample. Questionnaires mailed to surviving subjects 5 years after recruitment (1983-1985) and again in November 1992 and 1996 were returned by 98, 90 and 88 per cent, respectively, providing information on lifestyle changes, new cardiovascular symptoms and new diagnoses. CONCLUSION: Using the NHSCR framework for primary care registration procedures, maximum follow-up has been maintained. Brief and structured enquiry forms have gained and maintained co-operation from subjects and their GPs with considerable success. Mortality reporting from dual sources identified 5 per cent more cases.

Adult↗
PubMed1993

infoRAD: computers for clinical practice and education in radiology. Teleradiology, information transfer, and PACS: implications for diagnostic imaging in the 1990s.

Picture archiving and communication systems (PACS) provide image viewing at diagnostic, reporting, consultation, and remote workstations; archival on magnetic or optical media by means of short- or long-term storage devices; communications by means of local or wide area networks or public communication services; and integrated systems with modality interfaces and gateways to health care facilities and departmental information systems. Research indicates three basic needs for image and report management: (a) improved communication and turnaround time between radiologists and other imaging specialists and referring physicians, (b) fast reliable access to both current and previously obtained images and reports, and (c) space-efficient archival support. Although PACS considerations are much more complex than those associated with single modalities, the same basic purchase criteria apply. These criteria include technical leadership, image quality, throughput, life cost (eg, initial cost, maintenance, upgrades, and depreciation), and total service. Because a PACS takes much longer to implement than a single modality, the customer and manufacturer must develop a closer working relationship than has been necessary in the past.

Computer Systems↗
PubMed2005

Quantum key distribution over a fiber-optic channel by means of pulse position modulation.

New methods are proposed for extending the range of fiber-optic one-way quantum key distribution (QKD), inspired by classical optical communication formats. A new time-domain technique based on pulse position modulation (PPM) is combined with differential phase-shift keying to optically implement a six-state protocol. Finally, some recently proposed PPM schemes are critically reviewed and applied to synthesize a new QKD asymmetric optical realization, applicable to local or metropolitan area networks.

Journal Article↗
PubMed2005

Information infrastructure for emergency medical services.

The pre-hospital emergency medical and public safety information environment is nearing a threshold of significant change. The change is driven in part by several emerging technologies such as secure, high-speed wireless communication in the local and wide area networks (wLAN, 3G), Geographic Information Systems (GIS), Global Positioning Systems (GPS), and powerful handheld computing and communication services, that are of sufficient utility to be more widely adopted. We propose a conceptual model to enable improved clinical decision making in the pre-hospital environment using these change agents.

Emergency Medical Services↗
PubMedDate not supplied

[Organization of neocortical neuronal networks].

Multiple unit activity in deep layers of the frontal and motor cortices was recorded by chronically implanted semimicroelectrodes in waking cats with different levels of food motivation. From four to seven neuronal spike trains were selected from the recorded multiunit activity. Interactions between neighbouring neurons in the motor and frontal areas of the neocortex (within the local neuronal networks) and between the neurons of these areas (distributed neuronal networks) were estimated by means of statistical crosscorrelation analysis of spike trains within the range of delays from 0 to 100 ms. Neurons in the local networks were divided in two subgroups: the neurons with higher spike amplitudes with the dominance of divergent connections and neurons with lower spike amplitudes with the dominance of convergent connections. Strong monosynaptic connections (discharges with a delay of less than 2 ms) between the neurons with high- and low-amplitude spikes formed the background of the local networks. Connections between low-amplitude neurons in the frontal cortex and high-amplitude neurons in the motor cortex dominated in the distributed networks. A 24-hour food deprivation predominantly altered the late interneuronal crosscorrelations with time delays within the range of 2-100 ms in both local and distributed networks.

Animals↗
PubMed2005

Searchability of networks.

We investigate the searchability of complex systems in terms of their interconnectedness. Associating searchability with the number and size of branch points along the paths between the nodes, we find that scale-free networks are relatively difficult to search, and thus that the abundance of scale-free networks in nature and society may reflect an attempt to protect local areas in a highly interconnected network from nonrelated communication. In fact, starting from a random node, real-world networks with higher order organization like modular or hierarchical structure are even more difficult to navigate than random scale-free networks. The searchability at the node level opens the possibility for a generalized hierarchy measure that captures both the hierarchy in the usual terms of trees as in military structures, and the intrinsic hierarchical nature of topological hierarchies for scale-free networks as in the Internet.

Journal Article↗
PubMed2003

From DRG databases to an epidemiological observatory for colorectal cancer in a French small area oncology network.

Following a request from the local health authority, we have organised the permanent linkage of DRG/MBDS databases from different tertiary care hospitals from Saint-Etienne urban area. To made anonymous the MBDS, we used the asymmetric hashing and encrypting software developed and registered by the University hospital of Dijon. In each hospital, the selection of acute care stay MBDS is performed on the presence of at least one malignant tumour ICD code. The output is an anonymous but personal 20,000 patients register. We are presenting the method to estimate the incidence of colorectal cancer (CRC) cured between 1996 and 2000 from DRG databases of four hospitals and checking the validity against the figures coming from a cancer registry. Among the 1953 CRC patients observed, 156 patients have followed a CRC surgical excising in 1999. The DRG activity of the 4 observatory hospitals is 33.5% of the total hospital activity for people of the area recorded by the 1999 regional DRG PMSI data bases. The estimation of the incidence is 465 for 1999, the estimation of the same incidence by applying the incidence rate by sex and age from the Isère cancer register to the population of the Loire area, is 504. The under estimation is 7.7% with the observatory method. It is rather difficult to check an estimation by another estimation but in France the evaluation of oncology care strategies is impeded by the lack of cancer registries. The conclusion of this study is a good feasibility and acceptability of the linking procedure when used with a clear healthcare goal. The use of DRG data bases within an oncology network by linking the mandatory MBDS data bases gives the opportunity to share some clinical data between healthcare professionals.

Colorectal Neoplasms↗
PubMed2001

Local level sustainability policies in the Baltic Sea area: Local Agenda 21 within the Union of the Baltic Cities network.

Local Agenda 21 (LA21) processes have 2 central goals. i) On the basis of some of the empirical evidence in this study, the primary goal is to improve democratic (environmental) policy-making processes in such a manner that a larger share of the population will be able to participate in planning and decision making and will also be able to understand the consequences of these decisions. ii) The LA21 processes seek to improve (at least indirectly) the broadly defined environmental situation locally in a manner that takes into account both the local and the global contexts. The first part of this article discusses the concept and methods of LA21 and sheds light on the different action areas that are central to the Baltic LA21 processes. In addition, the study will describe and display the LA21 situation within one network of cities, the Union of the Baltic Cities (UBC). Networking, including transfer of information, models and ideas, has been among the main tools for the diffusion of LA21 ideas especially into newly democratized societies. Finally, the article will conclude with an overall assessment of the LA21 situation on the Baltic rim.

Baltic States↗
PubMed2006

Exploring photosynthesis evolution by comparative analysis of metabolic networks between chloroplasts and photosynthetic bacteria.

BACKGROUND: Chloroplasts descended from cyanobacteria and have a drastically reduced genome following an endosymbiotic event. Many genes of the ancestral cyanobacterial genome have been transferred to the plant nuclear genome by horizontal gene transfer. However, a selective set of metabolism pathways is maintained in chloroplasts using both chloroplast genome encoded and nuclear genome encoded enzymes. As an organelle specialized for carrying out photosynthesis, does the chloroplast metabolic network have properties adapted for higher efficiency of photosynthesis? We compared metabolic network properties of chloroplasts and prokaryotic photosynthetic organisms, mostly cyanobacteria, based on metabolic maps derived from genome data to identify features of chloroplast network properties that are different from cyanobacteria and to analyze possible functional significance of those features. RESULTS: The properties of the entire metabolic network and the sub-network that consists of reactions directly connected to the Calvin Cycle have been analyzed using hypergraph representation. Results showed that the whole metabolic networks in chloroplast and cyanobacteria both possess small-world network properties. Although the number of compounds and reactions in chloroplasts is less than that in cyanobacteria, the chloroplast's metabolic network has longer average path length, a larger diameter, and is Calvin Cycle -centered, indicating an overall less-dense network structure with specific and local high density areas in chloroplasts. Moreover, chloroplast metabolic network exhibits a better modular organization than cyanobacterial ones. Enzymes involved in the same metabolic processes tend to cluster into the same module in chloroplasts. CONCLUSION: In summary, the differences in metabolic network properties may reflect the evolutionary changes during endosymbiosis that led to the improvement of the photosynthesis efficiency in higher plants. Our findings are consistent with the notion that since the light energy absorption, transfer and conversion is highly efficient even in photosynthetic bacteria, the further improvements in photosynthetic efficiency in higher plants may rely on changes in metabolic network properties.

Arabidopsis↗
PubMed2000

Security model for picture archiving and communication systems.

The modern information revolution has facilitated a metamorphosis of health care delivery wrought with the challenges of securing patient sensitive data. To accommodate this reality, Congress passed the Health Insurance Portability and Accountability Act (HIPAA). While final guidance has not fully been resolved at this time, it is up to the health care community to develop and implement comprehensive security strategies founded on procedural, hardware and software solutions in preparation for future controls. The Virtual Radiology Environment (VRE) Project, a landmark US Army picture archiving and communications system (PACS) implemented across 10 geographically dispersed medical facilities, has addressed that challenge by planning for the secure transmission of medical images and reports over their local (LAN) and wide area network (WAN) infrastructure. Their model, which is transferable to general PACS implementations, encompasses a strategy of application risk and dataflow identification, data auditing, security policy definition, and procedural controls. When combined with hardware and software solutions that are both non-performance limiting and scalable, the comprehensive approach will not only sufficiently address the current security requirements, but also accommodate the natural evolution of the enterprise security model.

Computer Communication Networks↗
PubMed1993

Music, the brain and Ravel.

Understanding the functional organization of the cerebral structures underlying receptive and expressive musical processes is confronted with a wide variety of difficulties inherent in the artistic and subjective nature of the musical experience. Yet clarifying the relationships between music and the brain is a legitimate goal of neuroscientific research. One approach toward this goal is based on new developments of brain imaging techniques, and recent investigations indicate that the realization of musical abilities such as sight-reading and piano performance relies on a distributed neural network comprising locally specialized cortical areas. Another approach is concerned with the study of musicians, like Maurice Ravel, who have been affected by brain damage. An analysis of their deficits helps to uncover some properties of music-brain relationships, to identify the essential questions raised by these deficits, and to clarify the neurofunctional anatomy of musical abilities. The understanding of the neurocognitive bases of musical functions is still at an early stage, but recent progress in cognitive and neurofunctional research opens the way to more systematic studies than had so far been possible.

Cerebral Cortex↗
PubMed1991

Clinical experience in the use of photostimulable phosphor radiographic systems.

The experience with CR systems gained at the three institutions described in this report demonstrates numerous advantages over the conventional screen-film system. These include: (1) a reduction in the radiation exposure delivered to the patient (25% to 50%); (2) a decrease in the number of repeat examinations needed, especially in portable units where technical difficulties are common with screen-film examinations; this is attributable to the linear, wider dynamic range of CR systems compared with screen-film combinations; (3) the capability to archive electronically all images by means of a digital optical storage system; (4) automatic electronic setting of the laser scanner for the latitude and sensitivity on each image; (5) the digital images are available for transmission to all image display workstations on a local or wide-area network; and (6) the ability to adjust interactively the display parameters to best depict images and pathology as well as salvage technically suboptimal examinations. Several disadvantages of CR systems compared with conventional screen-film examinations have also been identified.(ABSTRACT TRUNCATED AT 250 WORDS)

Humans↗
PubMed1998

The evolution of health-care records in the era of the Internet.

Health-care records are evolving as the rationale for their automation becomes ever more persuasive. Promoting that evolution are local and wide-area networking as they demonstrate that computer-based medical and health records will be more than mere electronic versions of the traditional paper record. System integration has emerged as a key element in the reinvention of environments for patient data management and health promotion. The ability to achieve the future vision of integrated health records depends in part on current research initiatives related to the role of the global information infrastructure in supporting health and health care.

Computer Literacy↗
PubMed2002

Clinical networks for nursing research.

As a central feature of national research and development strategies, clinical effectiveness emphasizes the importance of rigorous experimental research in nursing. It is naïve to assume that over-worked practitioners, with little research training and supervision, can undertake this type of research. Traditional approaches to research support rely on the practitioner registering for a higher degree and academic supervision. This assumes that the responsibility for research lies with practice, with higher education adopting a reactive stance in supporting research and development in nursing. The literature demonstrates a growing number of innovative models for facilitating nursing research. These, however, tend to focus on single appointments with limited and predefined access to clinical areas and patient populations. This article details a new initiative from the Clinical Nursing Practice Research Unit (CNPRU) that aims to support programmatic research in nursing practice through Clinical Networks for Nursing Research. Our research strategy is to contribute to the development of nursing science by facilitating effective collaboration between clinicians and higher education in core clinical specialties, including stroke rehabilitation, diabetes, mental health and community nursing. Each researcher has developed networks with a number of clinical areas, locally, regionally or nationally, through seminars, conferences or newsletters, to link practitioners and generate answerable research questions. Network communications also rely heavily on the establishment of interactive websites. This strategy has resulted in a number of collaborative, evaluative studies including clinical trials in rehabilitation, diabetic nursing and primary care.

Clinical Nursing Research↗
PubMed1992

PACS mini refresher course. Wide area network strategies for teleradiology systems.

Teleradiology systems require the use of wide area networks (WANs). Design and implementation of a WAN depend on the number of images to be transmitted, desired digital image throughput (based on signaling rate), and cost of the communications link. Image transmission load must be estimated before the communications link can be selected. Communications links used in WANs include T-1 carrier point-to-point service, digital service (DS)-1 dial-up service, DS-3 point-to-point service, DS-0 dial-up service, digital microwave, fiberoptic local loop carriers, and metropolitan area networks (MANs). Depending on the distance between sites, T-1 service may be less costly than DS-1 service; however, for distances more than 200 miles, DS-1 service can be less expensive and more flexible. Both of these services and DS-0 service have lower signaling rates than DS-3 service, which is the fastest and most expensive link. Microwave and fiberoptic links are less expensive but have distance limitations of 14 and 30 miles, respectively. MANs are still being developed but hold the promise of higher signaling rates at lower costs.

Computer Communication Networks↗
PubMed1985

Localization of cell surface glycoproteins in membrane domains associated with the underlying filament network.

To visualize the localization of cell surface constituents in relation to the plasma membrane-associated filament network, we developed a method based on a combination of immunogold labeling and dry-cleaving. For labeling we used trinitrophenyl-derivatized ligand, anti-TNP antibodies, and protein A-coated colloidal gold. Dry-cleaving (Mesland, D. A. M., H. Spiele, and E. Roos, 1981, Exp. Cell Res., 132: 169-184) involves cleavage of lightly fixed critical point-dried cells by means of adhesive tape. Since cells cleave close to the cell surface, the remaining layer is thin enough to be examined in transmission electron microscopy. Using this method, we studied concanavalin A-binding constituents on the medium-facing surface of H35 hepatoma cells. The distribution of the gold particles, which was partly dispersed and partly patchy, coincided strikingly with membrane-associated filaments, and label was virtually absent from areas overlying openings in the filament network. In stereo pairs we observed the label to be localized to areas of somewhat enhanced electron density at the plane of the membrane. These areas were interconnected in a pattern congruent with the filament network. Preliminary observations on wheat germ agglutinin receptors on the hepatoma cells as well as concanavalin A receptors on isolated hepatocytes yielded comparable results. It thus appears that surface glycoproteins, although seemingly randomly distributed as observed in thin sections, may actually be localized to particular membrane domains associated with underlying filaments.

Actin Cytoskeleton↗