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PubMed1998

Experience with PACS in an ATM/Ethernet switched network environment.

Legacy local area network (LAN) technologies based on shared media concepts are not adequate for the growth of a large-scale picture archiving and communication system (PACS) in a client-server architecture. First, an asymmetric network load, due to the requests of a large number of PACS clients for only a few main servers, should be compensated by communication links to the servers with a higher bandwidth compared to the clients. Secondly, as the number of PACS nodes increases, the network throughout should not measurably cut production. These requirements can easily be fulfilled using switching technologies. Here asynchronous transfer mode (ATM) is clearly one of the hottest topics in networking because the ATM architecture provides integrated support for a variety of communication services, and it supports virtual networking. On the other hand, most of the imaging modalities are not yet ready for integration into a native ATM network. For a lot of nodes already joining an Ethernet, a cost-effective and pragmatic way to benefit from the switching concept would be a combined ATM/Ethernet switching environment. This incorporates an incremental migration strategy with the immediate benefits of high-speed, high-capacity ATM (for servers and high-sophisticated display workstations), while preserving elements of the existing network technologies. In addition, Ethernet switching instead of shared media Ethernet improves the performance considerably. The LAN emulation (LANE) specification by the ATM forum defines mechanisms that allow ATM networks to coexist with legacy systems using any data networking protocol. This paper points out the suitability of this network architecture in accordance with an appropriate system design.

Local Area Networks↗
PubMed2003

A force-controlled planar haptic device for movement control analysis of the human arm.

This paper describes the design and application of a haptic device to study the mechanical properties of the human arm during interaction with compliant environments. Estimates of the human endpoint admittance can be obtained by recording position deviations as a result of force perturbations. Previous studies attempted to estimate the impedance by recording force as a result of position perturbations, but these experiments do not require a feasible task of human beings. A general problem of force-controlled haptic devices is the occurrence of contact instability, especially where a small virtual mass is required. This negative effect is reduced by the use of a lightweight but stiff manipulator and a robust servo-based admittance controller. The virtual admittance is accurate to at least 13 Hz, attaining a minimum virtual mass of 1.7 kg (isotropic, without damping and stiffness). The properties of known test loads were estimated with an accuracy higher than 98%, up to 20 Hz. The application of the manipulator is evaluated by an experiment with a subject performing a position maintenance task. With this device it is possible to study the adaptability of the neuromuscular system to a variety of environments, enabling a new and functional approach to human motion research.

Adult↗
PubMed1999

Healing of the patellar tendon donor defect created after central-third patellar tendon autograft harvest. A long-term histological evaluation in the lamb model.

Patellar tendon donor defect (PTDD) healing after patellar tendon autograft (PTA), was evaluated in 12 lambs (24 knees), by means of conventional histology, immunohistochemistry and image analysis. The results of this study indicate that the PTDD is replaced by a tissue that does not assume the histological characteristics of a normal patellar tendon. Both the Hoffa fat pad (HFP) and the paratenon play an important role in the healing process, although qualitative and quantitative chronological differences were found, which supports the concept of a "two-time process". The HFP initiates the repair process, and is the main active proliferative tissue compartment during the first week. Once the process is established, the paratenon and, in particular, its synovial lining, starts proliferative activity and virtually substitutes that of the HFP, which rapidly loses activity in a few days. Moreover, donor-site morbidity after PTA could be the result of histological changes in the patellar tendon and environs in only a few cases. We have found inflammatory and neural changes in the refilled PTDD that could explain the anterior knee pain after PTA. Likewise, we have observed loss of Golgi corpuscles in the refilled PTDD, which could lead to proprioceptive loss after ACL reconstruction with PTA. Finally, we have observed shrinkage of the PTDD scar that could contribute to the etiopathogenia of a patella infera.

Animals↗
PubMed1982

Prolyl 4-hydroxylase activity in relation to the oxidation state of enzyme-bound iron. The role of ascorbate in peptidyl proline hydroxylation.

In agreement with others (Myllylä, R., Kuutti-Savolainen, E.-R. and Kivirikko, K.I. (1978) Biochem. Biophys. Res. Commun. 83, 441-448), it was found that, in the absence of ascorbate, prolyl 4-hydroxylase (prolyl-glycyl-peptide, 2-oxoglutarate:oxygen oxidoreductase (4-hydroxylating), EC 1.14.11.2) catalyses the hydroxylation of peptidyl proline, stoicheiometrically coupled to the oxidative decarboxylation of 2-oxoglutarate, at a high initial rate. Under these conditions the enzyme becomes inactivated by at least 90% within 1 min in the presence of 400 microM 2-oxoglutarate, in the presence or absence of the peptide substrate (Pro-Pro-Gly)10. The enzyme can be partly reactivated by ascorbate, but not by Fe2+. Addition of a stoicheiometric amount of iron to the enzyme gives rise to a small EPR signal at g = 4.3, which is typical of a high-spin d 5 ion in a rhombic environment. After subsequent incubation for 30 s at 37 degrees C in the presence of 2-oxoglutarate, the amplitude of the EPR signal at g = 4.3 increases 3-4-fold and corresponds to virtually all of the iron added. In addition, an EPR signal at g = 2.0 is formed under these conditions. The signal at g = 4.3 decreases after subsequent addition of ascorbate. It is concluded that in the presence of 2-oxoglutarate enzyme-bound Fe2+ is rapidly converted to Fe3+, leading to inactivation of the enzyme. Enzyme-bound Fe3+ can be reduced again by ascorbate, thus reactivating the enzyme, or, in the absence of 2-oxoglutarate, by Fe2+.

Animals↗
PubMed2005

Spatial decisions in rats based on the geometry of computer-generated patterns.

Animals often demonstrate the ability to use the geometric configuration of multiple landmarks for orientation in the environment. We developed a new behavioral task using a computer screen for presentation of visual stimuli allowing the rats to make navigational decisions in real space according to the geometric configuration of external virtual patterns (designed as a possible representation of this space). The rats were placed in a Skinner box with four nosing holes in the transparent front wall through which the computer screen was visible. They were trained in successive phases: first the visual stimulus displayed on the screen directly marked the rewarded nosing hole, then the displayed stimuli were reduced in size or displaced, thus disconnected from the response space. The results suggested that rats were able to use the geometric configuration of stimuli presented on the computer screen for navigational decisions in real space.

Animals↗
PubMed1998

Solar ultraviolet and the evolutionary history of cyanobacteria.

On the basis of photobiological, evolutionary, paleontological, paleoenvironmental and physiological arguments, a time course for the role of solar ultraviolet radiation (UVR, wavelengths below 400 nm) in the ecology and evolution of cyanobacteria is proposed in which three main periods can be distinguished. An initial stage, before the advent of oxygenic photosynthesis, when high environmental fluxes of UVC (wavelengths below 280 nm) and UVB (280-320 nm) may have depressed the ability of protocyanobacteria to develop large populations or restricted them to UVR refuges. A second stage lasting between 500 and 1500 Ma (million years), started with the appearance of true oxygen-evolving cyanobacteria and the concomitant formation of oxygenated (micro)environments under an oxygen free-atmosphere. In this second stage, the age of UV, the overall importance of UVR must have increased substantially, since the incident fluxes of UVC and UVB remained virtually unchanged, but additionally the UVA portion of the spectrum (320-400 nm) suddenly became biologically injurious and extremely reactive oxygen species must have formed wherever oxygen and UVR spatially coincided. The last period began with the gradual oxygenation of the atmosphere and the formation of the stratospheric ozone shield. The physiological stress due to UVC all but disappeared and the effects of UVB were reduced to a large extent. Evidence in support of this dynamics is drawn from the phylogenetic distribution of biochemical UV-defense mechanisms among cyanobacteria and other microorganisms. The specific physical characteristics of UVR and oxygen exposure in planktonic, sedimentary and terrestrial habitats are used to explore the plausible impact of UVR in each of the periods on the ecological distribution of cyanobacteria.

Amino Acids↗
PubMed2001

Village poultry production systems in the central highlands of Ethiopia.

Participatory rural appraisal (PRA), supported by checklists and intensive case studies on individual households, was carried out in three villages at three different altitudes in the central highlands of Ethiopia. The chicken production system in each village is described and the problems are discussed. More than 60% of the families kept chickens, and in most cases the women owned and managed the birds and controlled the cash from the sales. The production systems followed were mainly low-input and small-scale, with 7-10 mature birds per household, reared in the back yards with inadequate housing, feeding and health care. The average egg production per clutch was 15-20, with 3-4 clutches per year. The mean number of eggs set per bird was 12.9 +/- 2.2 (n = 160), depending on the size of the bird and season, and the hatching rate was 80.9% +/- 11.1%, range 44%-100% (n = 160). Poultry meat and eggs were generally accepted and appreciated in all three villages. In addition to the small amount of cash income they provide, scavenging chickens have nutritional, cultural and social functions. The flock composition, price of poultry and poultry products, disease outbreaks and hatching of chicks were strongly affected by season. Disease was cited as the most important problem by most of the members of the community, followed by predation, lack of feed, poor housing, insufficient water and parasites. Disease periodically decimated the flocks, and consequently, about 50% of the eggs produced were incubated in order to replace the birds that had died. The major source of loss in the system was the high mortality of chicks (61%) that occurred between hatching and the end of brooding at 8 weeks of age. The system was characterized by no or few inputs and a low output level. The major input was the cost of foundation stock, but after that virtually no cost was involved. The major source of feed for the birds was from the scavenging feed resource base, which comprised table leftovers, small grain supplements and anything edible from the immediate environment.

Animal Feed↗
PubMed1999

Characterisation of workers' exposure in a Russian nickel refinery.

In support of a feasibility study of reproductive and developmental health among females employed in the Monchegorsk (Russia) nickel refinery, personal exposure and biological monitoring assessments were conducted. The inhalable aerosol fraction was measured and characterised by chemical speciation and particle-size distribution measurements. Unexpected findings were that: (i), pyrometallurgical working environments had significant levels of water-soluble nickel; (ii), significant exposure to cobalt occurred for the nickel workers; (iii), particles of size corresponding to the thoracic and respirable fractions appeared to be virtually absent in most of the areas surveyed. The water-soluble fraction is judged to be primarily responsible for the observed urinary nickel and cobalt concentrations. It is concluded relative to current international occupational-exposure limits for nickel in air, and because of the high nickel concentrations observed in urine, that the Monchegorsk nickel workers are heavily exposed. The implication of this finding for follow-up epidemiological work is alluded to.

Adult↗
PubMed2000

Mechanism of kappa B DNA binding by Rel/NF-kappa B dimers.

The DNA binding of three different NF-kappaB dimers, the p50 and p65 homodimers and the p50/p65 heterodimer, has been examined using a combination of gel mobility shift and fluorescence anisotropy assays. The NF-kappaB p50/p65 heterodimer is shown here to bind the kappaB DNA target site of the immunoglobulin kappa enhancer (Ig-kappaB) with an affinity of approximately 10 nm. The p50 and p65 homodimers bind to the same site with roughly 5- and 15-fold lower affinity, respectively. The nature of the binding isotherms indicates a cooperative mode of binding for all three dimers to the DNA targets. We have further characterized the role of pH, salt, and temperature on the formation of the p50/p65 heterodimer-Ig-kappaB complex. The heterodimer binds to the Ig-kappaB DNA target in a pH-dependent manner, with the highest affinity between pH 7.0 and 7.5. A strong salt-dependent interaction between Ig-kappaB and the p50/p65 heterodimer is observed, with optimum binding occurring at monovalent salt concentrations below 75 mm, with binding becoming virtually nonspecific at a salt concentration of 200 mm. Binding of the heterodimer to DNA was unchanged across a temperature range between 4 degrees C and 42 degrees C. The sensitivity to ionic environment and insensitivity to temperature indicate that NF-kappaB p50/p65 heterodimers form complexes with specific DNA in an entropically driven manner.

Amino Acid Substitution↗
PubMed2000

The Centre for Minimal Access Surgery--teaching for tomorrow.

The Centre for Minimal Access Surgery (CMAS) was established as a state-of-the-art multidisciplinary technological education and research centre for minimal access surgical techniques. Up-to-date training models were obtained to facilitate skill acquisition. Among these were the Minimal Access Therapy trainer and the Body Form Simulator, which provide simulations of the human form on which students can practise operative procedures. The CMAS also acquired the MIST Virtual Reality system, a computer program that facilitates the acquisition of laparoscopy skills. Finally, the CMAS compiled a multimedia library of resources. While many skills can be gained in these synthetic and didactic environments, they cannot provide all the preparation necessary to practise competently. To facilitate the realtime observation of surgical procedures and the telementoring process, the CMAS has commissioned the development of an integrated videoconferencing system that permits the high-quality, rapid transfer of multi-feed video and audio data of surgical procedures from an operating room to the classroom.

General Surgery↗
PubMed2006

Tscope: A C library for programming cognitive experiments on the MS windows platform.

Tscope is a C/C+ + programming library designed for programming experiments that run on Windows 2000/XP. It is intended for a public of experimental psychologists with moderate programming skills, who are accustomed to writing their own experimental programs for DOS but have not made the step to Windows-based programming yet. It provides molecular functions for graphics, sound, timing, randomization, and response registration. Together with ANSI-C standard library functions and the powerful C syntax, this set of functions gives the experimenter the opportunity to program virtually any experiment one can come up with. Tscope is completely based on free software, is distributed under the GNU General Public License, and is available at expsy.ugent.be/tscope. An integrated development environment for compiling and running Tscope programs is also freely available.

Cognition↗
PubMed2004

[Acclimatization of salmon Oncorhynchus gorbuscha (Walbaum) in the European north: data from restriction analysis of mtDNA].

Pink salmon spawners introduced into the White Sea basin (the Umba River) were compared to the spawners from the basin of the Sea of Okhotsk (the Ola River) using restriction analysis of two fragments of mitochondrial DNA (mtDNA). One of the fragments included genes ND5/ND6, the other, the cytochrome b gene and the control region. It was found that mtDNA variation and diversity at the earlier examined nuclear allozyme genes significantly decreased in the odd broodline of pink salmon 8 years after the introduction. The haplotype diversity in the even broodline was considerably lower than in the odd broodline exhibiting virtually no change two generations after the introduction. Based on the results obtained, a possible role of these changes in adaptation of White Sea pink salmon from the odd broodline to the new environment is discussed.

Adaptation, Physiological↗
PubMed2004

Communication and information needs and barriers: an international collaboration model.

This future vision paper describes the emerging issue of multicultural medical informatics teams. In an increasingly networked healthcare environment, the rise of global teams has come to the forefront, calling for an increased understanding of various cultural norms. Team members may reside in other countries and be known to others only virtually. Concomitantly, the team dynamics of physically present members may be impacted by international factors such as culture of origin.

Communication↗
PubMed2002

An immersive simulation system for provoking and analyzing cataplexy.

Cataplexy, a sudden loss of voluntary muscle control, is one of the hallmark symptoms of narcolepsy, a sleep disorder characterized by excessive daytime sleepiness. Cataplexy is usually triggered by strong, spontaneous emotions, such as laughter, surprise, fear or anger, and is more common in times of stress. The Sleep Disorders Unit and the Biomedical Imaging Resource at Mayo Clinic are developing interactive display technology for reliably inducing cataplexy during clinical monitoring. The use of immersive displays may help bypass patient defenses, and game-like "unreality" allows introduction of surprising, threatening, or humorous elements, with little risk of offending patients. The project is referred to as the "Cataplexy/Narcolepsy Activation Program", or CatNAP. We have developed an automobile driving simulation to allow the introduction of humorous, surprising, or stress-inducing events and objects as the patient attempts to navigate a simulated vehicle through a virtual town. The patient wears a stereoscopic head-mounted display, by which he views the virtual town through the windows of his simulated vehicle. The vehicle is controlled via a driving simulator steering wheel and pedal cluster. The patient is instructed to drive his vehicle to another location in town, given initial directions and street signs. As he attempts to accomplish the task, various objects, sounds or conditions occur which may distract, startle, frustrate or cause laughter; responses which may trigger a cataplectic episode. The patient can be monitored by reflex tests and EMG recordings during the driving experience. An evaluation phase with volunteer patients previously diagnosed with cataplexy has been completed. The goal of these trials was to gain insight from the volunteers as to improvements that could be made to the simulation. All patients that participated in the evaluation phase have been under a physician's care for a number of years and control their cataplexy with medication. We believe this is a novel and innovative approach to a difficult problem. CatNAP is a compelling example of the potentially effective application of virtual reality technology to an important clinical problem that has resisted previous approaches. Preliminary results suggest that an immersive simulation system like CatNAP will be able to reliably induce cataplexy in a controlled environment. The project is continuing through a final stage of refinement prior to conducting a full clinical study.

Automobile Driving↗
PubMed2005

Linking human anatomy to knowledge bases: a visual front end for electronic medical records.

A new concept of a visual electronic medical record is presented based on developments ongoing in the Defense Advanced Research Projects Agency Virtual Soldier Project. This new concept is based on the holographic medical electronic representation (Holomer) and on data formats being developed to support this. The Holomer is being developed in two different visualization environments, one of which is suitable for prototyping the visual electronic medical record. The advantages of a visual approach as a front end for electronic medical records are discussed and specific implementations are presented.

Humans↗
PubMed1988

A Virtual Notebook for biomedical work groups.

During the past several years, Baylor College of Medicine has made a substantial commitment to the use of information technology in support of its corporate and academic programs. The concept of an Integrated Academic Information Management System (IAIMS) has proved central in our planning, and the IAIMS activities that we have undertaken with funding from the National Library of Medicine have proved to be important extensions of our technology development. Here we describe our Virtual Notebook system, a conceptual and technologic framework for task coordination and information management in biomedical work groups. When fully developed and deployed, the Virtual Notebook will improve the functioning of basic and clinical research groups in the college, and it currently serves as a model for the longer-term development of our entire information management environment.

Computer Communication Networks↗
PubMed2005

osni.info-Using free/libre/open source software to build a virtual international community for open source nursing informatics.

Many health informatics organizations seem to be slow to take up the advantages of dynamic, web-based technologies for providing services to, and interaction with, their members; these are often the very technologies they promote for use within healthcare environments. This paper aims to introduce some of the many free/libre/open source (FLOSS) applications that are now available to develop interactive websites and dynamic online communities as part of the structure of health informatics organizations, and to show how the Open Source Nursing Informatics Working Group (OSNI) of the special interest group in nursing informatics of the International Medical Informatics Association (IMIA-NI) is using some of these tools to develop an online community of nurse informaticians through their website, at . Some background introduction to FLOSS applications is used for the benefit of those less familiar with such tools, and examples of some of the FLOSS content management systems (CMS) being used by OSNI are described. The experiences of the OSNI will facilitate a knowledgeable nursing contribution to the wider discussions on the applications of FLOSS within health and healthcare, and provides a model that many other groups could adopt.

Database Management Systems↗
PubMed2003

The genesis of neurosurgery and the evolution of the neurosurgical operative environment: part II--concepts for future development, 2003 and beyond.

The future development of the neurosurgical operative environment is driven principally by concurrent development in science and technology. In the new millennium, these developments are taking on a Jules Verne quality, with the ability to construct and manipulate the human organism and its surroundings at the level of atoms and molecules seemingly at hand. Thus, an examination of currents in technology advancement from the neurosurgical perspective can provide insight into the evolution of the neurosurgical operative environment. In the future, the optimal design solution for the operative environment requirements of specialized neurosurgery may take the form of composites of venues that are currently mutually distinct. Advances in microfabrication technology and laser optical manipulators are expanding the scope and role of robotics, with novel opportunities for bionic integration. Assimilation of biosensor technology into the operative environment promises to provide neurosurgeons of the future with a vastly expanded set of physiological data, which will require concurrent simplification and optimization of analysis and presentation schemes to facilitate practical usefulness. Nanotechnology derivatives are shattering the maximum limits of resolution and magnification allowed by conventional microscopes. Furthermore, quantum computing and molecular electronics promise to greatly enhance computational power, allowing the emerging reality of simulation and virtual neurosurgery for rehearsal and training purposes. Progressive minimalism is evident throughout, leading ultimately to a paradigm shift as the nanoscale is approached. At the interface between the old and new technological paradigms, issues related to integration may dictate the ultimate emergence of the products of the new paradigm. Once initiated, however, history suggests that the process of change will proceed rapidly and dramatically, with the ultimate neurosurgical operative environment of the future being far more complex in functional capacity but strikingly simple in apparent form.

Forecasting↗