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At least 595 records · Page 33Linked to original sources
PubMed2001

Real-time three-dimensional echocardiography: an overview.

Conventional echocardiography and its representation of the heart in a two-dimensional format only provide partial information about cardiac function. Real-time three-dimensional echocardiography is a recently developed technique based on the design of an ultrasound transducer with a matrix array that instantaneously acquires the image contained in a pyramidal volume. The simultaneous display of multiple tomographic images allows the anatomically correct examination of any structure contained within the volumetric image. Software and technologies based on high performance computers designed for graphic handling of three-dimensional images permit the rapid mapping of the volumetric image and provide possibilities beyond those of the echograph. Using this methodology, it is possible to simultaneously visualize multiple superimposed planes in an interactive manner. Real-time three-dimensional echocardiography also allows a quantitative assessment of cardiac volumes, ventricular mass, and myocardium with contraction and/or perfusion abnormalities. This technique thus expands the abilities of non-invasive cardiology and may open new doors for the evaluation of cardiac disease.

Algorithms↗
PubMed2006

Design, synthesis and activity against Toxoplasma gondii, Plasmodium spp., and Mycobacterium tuberculosis of new 6-fluoroquinolones.

This paper reports on the rational design of a series of new 6-fluoroquinolones by QSAR analysis against Toxoplasma (T.) gondii, their synthesis, their biological evaluation against T. gondii and Plasmodium (P.) spp., and their effect on Mycobacterium (M.) tuberculosis DNA gyrase and growth inhibition. Of the 12 computer-designed 8-ethyl(or methoxy)- and 5-ethyl-8-methoxy-6-fluoroquinolones predicted to be active against T. gondii, we succeeded in the synthesis of four 6-fluoro-8-methoxy-quinolones. The four 6-fluoro-8-methoxy-quinolones are active on T. gondii but only one is as active as predicted. One of these four compounds appears to be an antiparasitical drug of great potential with inhibitory activities comparable to or higher than that of trovafloxacin, gatifloxacin, and moxifloxacin. They also inhibit DNA supercoiling by M. tuberculosis gyrase with an efficiency comparable to that of the most active quinolones but are poor inhibitors of M. tuberculosis growth.

Animals↗
PubMed1993

Assessment of the current computer literacy and future computer needs of emergency medicine residents and faculty.

The purpose of this study was to assess the current computer literacy and future computer needs of emergency medicine residents and faculty to aid in developing a computer literacy curriculum. All emergency medicine residents and full-time faculty from a random sample of emergency medicine residencies were mailed questionnaires assessing current computer familiarity and future computer needs. Twenty-one residencies were surveyed; 15 resident and 17 faculty questionnaires were returned. Thirty-seven percent (116 of 314) faculty and 29% (135 of 470) resident questionnaires were completed and returned. Eighty percent (12 of 15) of residencies had a designated computer for resident use; 93% (14 of 15) had a computer for use in the emergency department. Forty-seven percent of residents owned their own computer; 68% of faculty had a computer in their home, and 52% had computers in their office. Less than 30% of residents and faculty had formal computer training. Residents and faculty rated the current familiarity and future needs for various software applications on a five-point scale. Data were analyzed using the Wilcoxon-Rank Sum Test. Residents and faculty had the most anticipated need for word processing, graphics, literature searching, data base, and patient management programs. Future computer need was rated significantly higher than current computer familiarity in all computer application areas (P < or = .0002). It seems that emergency medicine residents and faculty have adequate access to computers, but minimal computer training. Residents and faculty have a high anticipated need for various basic computer applications.(ABSTRACT TRUNCATED AT 250 WORDS)

Computer Literacy↗
PubMed2000

Miniaturised ultrasonic aspiration handpiece for increased applicability.

OBJECTIVE: At present, ultrasonic aspiration is routinely used in several fields of surgery, especially in brain and spinal micro-surgery for tumour removal. In order to broaden the access to difficult surgical sites, it is important to design highly miniaturised but still efficient handpieces. The internal resonant system, always made of high-grade materials, must be optimally dimensioned. Normally this is done semi-empirically, by successively improving the design during many iterative test steps. This method however involves several additional difficulties when the degree of miniaturisation increases. For example, small transducer weights exacerbate heat-dissipation problems and make design optimisation important. METHODS: To resolve these problems we have produced modelling software that makes it possible to simulate and automatically tune each individual interacting section of the design before it is actually manufactured, thereby assuring optimal efficiency. RESULTS: Using a new mini-handpiece, designed via the software, two cases of dissection of acoustic neurinomas were successfully performed. CONCLUSION: Using conventional physical steps for improving ultrasonic aspiration handpieces, several problems arise when the grade of miniaturisation increases, due to increasing demands. We have designed computer software for handpiece simulation. Using this model it has been possible to manufacture a highly efficient miniaturised handpiece.

Equipment Design↗
PubMed2003

Indirect solid free form fabrication of local and global porous, biomimetic and composite 3D polymer-ceramic scaffolds.

Precise control over scaffold material, porosity, and internal pore architecture is essential for tissue engineering. By coupling solid free form (SFF) manufacturing with conventional sponge scaffold fabrication procedures, we have developed methods for casting scaffolds that contain designed and controlled locally porous and globally porous internal architectures. These methods are compatible with numerous bioresorbable and non-resorbable polymers, ceramics, and biologic materials. Phase separation, emulsion-solvent diffusion, and porogen leaching were used to create poly(L)lactide (PLA) scaffolds containing both computationally designed global pores (500, 600, or 800 microm wide channels) and solvent fashioned local pores (50-100 microm wide voids or 5-10 microm length plates). Globally porous PLA and polyglycolide/PLA discrete composites were made using melt processing. Biphasic scaffolds with mechanically interdigitated PLA and sintered hydroxyapatite regions were fabricated with 500 and 600 microm wide global pores. PLA scaffolds with complex internal architectures that mimicked human trabecular bone were produced. Our indirect fabrication using casting in SFF molds provided enhanced control over scaffold shape, material, porosity and pore architecture, including size, geometry, orientation, branching, and interconnectivity. These scaffolds that contain concurrent local and global pores, discrete material regions, and biomimetic internal architectures may prove valuable for multi-tissue and structural tissue interface engineering.

Biomechanical Phenomena↗
PubMed1996

Clinical effects of anticoagulant therapy in suspected acute myocardial infarction: systematic overview of randomised trials.

OBJECTIVES: Most randomised trials of anticoagulant therapy for suspected acute myocardial infarction have been small and, in some, aspirin and fibrinolytic therapy were not used routinely. A systematic overview (meta-analysis) of their results is needed, in particular to assess the clinical effects of adding heparin to aspirin. DESIGN: Computer aided searches, scrutiny of reference lists, and inquiry of investigators and companies were used to identify potentially eligible studies. On central review, 26 studies were found to involve unconfounded randomised comparisons of anticoagulant therapy versus control in suspected acute myocardial infarction. Additional information on study design and outcome was sought by correspondence with study investigators. SUBJECTS: Patients with suspected acute myocardial infarction. INTERVENTIONS: No routine aspirin was used among about 5000 patients in 21 trials (including half of one small trial) that assessed heparin alone or heparin plus oral anticoagulants, and aspirin was used routinely among 68,000 patients in six trials (including the other half of one small trial) that assessed the addition of intravenous or high dose subcutaneous heparin. MAIN OUTCOME MEASUREMENTS: Death, reinfarction, stroke, pulmonary embolism, and major bleeds (average follow up of about 10 days). RESULTS: In the absence of aspirin, anticoagulant therapy reduced mortality by 25% (SD 8%; 95% confidence interval 10% to 38%; 2P = 0.002), representing 35 (11) fewer deaths per 1000. There were also 10 (4) fewer strokes per 1000 (2P = 0.01), 19 (5) fewer pulmonary emboli per 1000 (2P < 0.001), and non-significantly fewer reinfarctions, with about 13 (5) extra major bleeds per 1000 (2P = 0.01). Similar sized effects were seen with the different anticoagulant regimens studied. In the presence of aspirin, however, heparin reduced mortality by only 6% (SD 3%; 0% to 10%; 2P = 0.03), representing just 5 (2) fewer deaths per 1000. There were 3 (1.3) fewer reinfarctions per 1000 (2P = 0.04) and 1 (0.5) fewer pulmonary emboli per 1000 (2P = 0.01), but there was a small non-significant excess of stroke and a definite excess of 3 (1) major bleeds per 1000 (2P < 0.0001). CONCLUSIONS: The clinical evidence from randomised trials dose not justify the routine addition of either intravenous or subcutaneous heparin to aspirin in the treatment of acute myocardial infarction (irrespective of whether any type of fibrinolytic therapy is used).

Anticoagulants↗
PubMed2002

An ergonomic evaluation comparing desktop, notebook, and subnotebook computers.

OBJECTIVE: To evaluate and compare the postures and movements of the cervical and upper thoracic spine, the typing performance, and workstation ergonomic factors when using a desktop, notebook, and subnotebook computers. DESIGN: Repeated-measures design. SETTING: A motion analysis laboratory with an electromagnetic tracking device. PARTICIPANTS: A convenience sample of 21 university students between ages 20 and 24 years with no history of neck or shoulder discomfort. INTERVENTION: Each subject performed a standardized typing task by using each of the 3 computers. MAIN OUTCOME MEASURES: Measurements during the typing task were taken at set intervals. RESULTS: Cervical and thoracic spines adopted a more flexed posture in using the smaller-sized computers. There were significantly greater neck movements in using desktop computers when compared with the notebook and subnotebook computers. The viewing distances adopted by the subjects decreased as the computer size decreased. Typing performance and subjective rating of difficulty in using the keyboards were also significantly different among the 3 types of computers. CONCLUSIONS: Computer users need to consider the posture of the spine and potential risk of developing musculoskeletal discomfort in choosing computers.

Adult↗
PubMed2006

Computer inference of network of ecological interactions from sampling data.

Both direct and indirect ecological interactions may occur in an ecosystem with large numbers of taxa. Traditional food web technique is a popular tool to measure the quality and health of the environment. Much of works must be done before constructing a food web for an ecosystem especially with many taxa. This food web is generally specific for some ecological interactions and fixed for a set of given species. It is therefore not an effective method for dynamic and prompt assessment of environment. Ecological interactions and their interactive intensity may be detected by sampling biological taxa in the field and by detecting various between-taxa distances or similarities. Network may clearly exhibit the complex interactions among biological taxa. Statistic tests on various distance or similarity measures and computer designs are required to infer the {network. We develop an algorithm and software to infer the network of direct or indirect ecological interactions in ecosystem. It is a prompt and effective tool in monitoring and assessment of the environment. A redundant network may be inferred and drawn by computer based on the statistic tests on sampling data or the pathway information given in HTML file. Dominant taxa may be found in the network. In total of 16 distance and similarity measures, including Euclidean distance, Manhattan distance, Pearson correlation, partial correlation, point correlation, linkage coefficients, Jaccard coefficient etc., are provided to detect taxa pairs with significant parametric or nonparametric similarities, based on randomization tests and ordinary statistic tests. Criteria to use distance and similarity measures are discussed.

Algorithms↗
PubMed1988

[Experiences with an anesthesia protocol written by computer].

Since December 1983, we have used a computer system for charting and data logging in cardiac and thoracic anesthesia. These computers, designed as stand-alone units, were developed at our hospital based on Motorola 6809 microprocessor systems. All measurements derived from anesthetic monitoring, ventilator, and heart-lung machine are automatically sampled at regular intervals and stored for later data management. Laboratory results are automatically received from the hospital computer system. The user communicates with the system via a terminal and a keyboard; this also facilitates the entering of all comments, medications, infusions, and fluid losses. All data are continuously displayed on an A3 format anesthetic chart using a multi-pen, flat-bed plotter. The operation of the system has proved to be simple and needs less time than charting by hand, while the result, the display on the chart, is far clearer and more complete than any handwritten document. Up to now 3,200 operations (corresponding to 12,500 anesthetic h) have been documented. The failure rate of the system, defined as an interruption of the documentation for more than 30 min is 2.1%. Further development of the system is discussed. A data base for processing the stored data has been developed and is being tested at present.

Anesthesia, General↗
PubMed1997

MR equipment acquisition strategies: low-field or high-field scanners.

Magnetic resonance (MR) field strength is one of the key aspects to consider when purchasing MR equipment. Other aspects include the gradient system, coil design, computer and pulse sequence availability, purchase cost, local reimbursement policies, and current opinion within the medical community. Our objective here is to evaluate the decision-influencing aspects of the MR market, with a focus on some specific areas such as high resolution studies, examination times, special techniques, instrumentation, open design magnets, costs and reimbursement policies, academic and industrial interests, contrast media, clinical efficacy, and finally, clinicians' preferences. Certainly the advantage of high-field is a higher signal-to-noise ratio and improved resolution. With a high-field unit, higher spatial resolution images and higher temporal resolution images can be obtained. Typical imaging times needed to produce clinically diagnostic images are about 3 times longer at 0.1 T than at 1.0 or 1.5 T. High-field-related advanced techniques, such as functional imaging, spectroscopy and microscopy, may become clinically useful in the near future. As long as there is an unlimited demand for MR examinations, it appears financially profitable to run a high-field system, despite the associated higher costs. However, if demand for MR becomes saturated, low-field systems will cause less financial strain on the reimbursement organisation and service provider. Recent emphasis on cost containment, the development of interventional techniques, the increased use of MR for patients in intensive care and operating suites, the deployment of magnets in office suites, and the development of new magnet configurations, all favour the supplementary use of low-field systems. Hence, MR units of all field strengths have a role in radiology.

Costs and Cost Analysis↗
PubMed2007

An experiment on the social facilitation of gambling behavior.

Research and theory regarding the social facilitation effect generates the expectation that the presence of other gamblers (or co-actors) in a gaming venue is likely to intensify individual gambling behavior and magnify losses. Fifty male and 66 female participants (116 total) played a computer-simulated electronic gaming machine with a fixed winning sequence, followed by an indefinite losing sequence. Measures of the intensity of gambling behavior included the final payout (a direct measure of losses), average bet-size, number of trials played, and the speed of play. Some participants received false feedback from the computer designed to suggest that other gamers in adjacent rooms were playing and sometimes winning at the same game. Persons who received both sight and sound information, including winning bells and instant messages regarding the wins of other (fake) players, placed more bets and lost more money compared to the other conditions with less information.

Adult↗
PubMed2004

Unilateral posterior crossbite and chin deviation: is there a correlation?

A retrospective study evaluating the clinical discernment of chin deviations in general, and especially in relation to unilateral posterior crossbite (UPXB), was carried out to determine whether (1) there is a correlation between UPXB and clinically discernible chin deviation, (2) there are differences between the judgement of professional dental observers and laymen, (3) visual assessment of chin deviation compares well with computer-assisted assessment and (4) how large a chin deviation should be before it is noticed. The experimental group consisted of 72 patients (30 males and 42 females, average age 14.5 years) with a UPXB. A control group of 72 subjects without a UPXB was matched for age and sex. In addition, one computer-designed face was added with chin deviations of 0, 2, 4, 6 and 8 mm to the left. The full-face slides of all subjects were shown twice, with an interval of 2 weeks, to an audience of seven orthodontists, ten dental students and five laymen judging by eye. A computer-assisted assessment was carried out by one observer, in order to create a standardized comparison to visual scoring. Inter-observer examination of visual scoring showed moderate agreement (kappa = 0.48). When comparing the computer-assisted and visual scores, the intra-class correlation coefficient (ICC) was 0.87. There were no major differences between professional observers and laymen, although the latter gave significantly more responses in the direction opposite to the crossbite. In 70.3 per cent (on average) of the subjects with a crossbite, a deviation in the same direction as the crossbite was noticed visually. The majority of the observers observed a chin deviation of at least 4 mm.

Adolescent↗
PubMed1998

Computer-assisted analysis of fetal movements in intrauterine growth retardation (IUGR).

A quantitative analysis of various fetal activities (mouth, eye and gross body movements) was made in 10 IUGR human fetuses. The aim of the study was to see whether IUGR fetuses move differently to normal fetuses. Each real-time ultrasound recording lasted 1 h and the analysis of various activities was carried out during replay of video recordings by means of a specially designed computer program. The following aspects have been investigated: (1) incidence, duration and interval for each of the fetal activities described; (2) the relationship between incidence, duration and interval for each single activity; (3) the correlations between the different activities. The results were compared with a group of 10 fetuses from normal pregnancies. On quantitative evaluation no clear effects due to uncomplicated IUGR could be detected except for median duration of eye movements, which turned out to be longer in the IUGR group. The evaluation of correlations between the characteristics (incidence, duration and interval) of each activity showed a positive correlation between incidence and duration of mouthing movements in the IUGR group, not found in the normal group. The study of the correlation between different fetal activities has shown an inverse correlation between mouthing and other activities in the normal fetuses, not found in the IUGR group. We conclude that in mildly affected fetuses with no evidence of hypoxia, there are no quantitative differences compared to normal fetuses in terms of the motility studied. The only differences found were in relation to the performance of such activities and they could reflect a dysfunction of the central nervous system resulting from a metabolic disturbance.

Eye Movements↗
PubMed2003

Computer-generated holograms of three-dimensional objects synthesized from their multiple angular viewpoints.

Synthesizing computer-generated holograms (CGHs) of a general three-dimensional (3D) object is usually a heavy computational task. We propose and demonstrate a new algorithm for computing CGHs of 3D objects. In our scheme, many different angular projections of computer-designed 3D objects are numerically processed to yield a single two-dimensional complex matrix. This matrix is equivalent to the complex amplitude of a wave front on the rear focal plane of a spherical lens when the object is located near the front focal point and illuminated by a plane wave. Therefore the computed matrix can be used as a CGH after it is encoded to a real positive-valued transparency. When such CGH is illuminated by a plane wave, a 3D real image of the objects is constructed. The number of computer operations are equivalent to those of a two-dimensional Fourier CGH. Computer and optical constructions of 3D objects, both of which show the feasibility of the proposed approach, are described.

Journal Article↗
PubMed2001

Rational Redesign of Inhibitors of Furin/kexin Processing Proteases.

Furin/kexin processing proteases catalyze the proteolysis of large protein precursors involved in many biological processes, such as zymogen activation, peptide hormone synthesis, viral protein processing and receptor maturation, making them potential targets for therapeutic agents. Herein, homology modeling and weighted evolutionary tracing were combined to investigate the interactionmechanism of furin/kex2 with eglin C mutants. The model structures showed that there were many acidic residues in the furin (kex2) binding interface, contributing to specificity for multiple basic residues of their corresponding substrates or inhibitors. Besides, some rational explanations were presented for the different inhibitor/substrate specificity of the furin/kexin members by combining the model structures with results of evolutionary tracing. Based on these analyses,an attempt was made to rationally redesign the eglin C by interface engineering with heterogeneous self-consistent ensemble optimization to improve its inhibitory specificity on furin/kex2. With the model complex structures of furin/kex2 and eglin C variants as structural templates, the P(1), P(2) and P(4) of eglin C were redesigned, respectively. The design results show that both furin and kex2 favored basic residues at P(1), P(2) and P(4) in eglin C, in good agreement with the experimental data. The detection of many specific residues in S' part of furin/kexin sequences made possible designing inhibitors with high specific binding to furin and kex2, respectively. As for furin, the best inhibitor designed was eglin C-P(2)'Glu-P(3)'Asp-P(4)'Arg (only these three positions were shown), while the best eglin C variant for kex2 designed was P(2)'Arg-P(3)'Arg-P(4)'Glu. The structures show that furin and kex2 form distinct interactions with these two eglin C variants. Herein, a strategy was proposed that combine homology modeling, evolutionary tracing and rational interface redesign to investigate enzyme-inhibitor interactions and inhibitor engineering. This computational design gives some rational guidance to further experimental inhibitor engineering.

Journal Article↗
PubMed1975

[A computer-directed measuring device to analyse pathological gaits].

The clinical observation of the walk is still the only current way to define the limp, but is obviously quite a rough valuation. Taking advantage of previous studies and recent improvements in electronics, the authors have built a measuring unit-including a computer-designed for daily clinical use. This unit provides in a few minutes the variations of the ground reaction to the human body during the walk, and the displacement of the point to which this reaction is applied. Seven to ten patients per hour may be examined, including previous analysis of the results by the computer.

Computers↗
PubMed2005

On the design of computer-based models for integrated environmental science.

The current research agenda in environmental science is dominated by calls to integrate science and policy to better understand and manage links between social (human) and natural (nonhuman) processes. Freshwater resource management is one area where such calls can be heard. Designing computer-based models for integrated environmental science poses special challenges to the research community. At present it is not clear whether such tools, or their outputs, receive much practical policy or planning application. It is argued that this is a result of (1) a lack of appreciation within the research modeling community of the characteristics of different decision-making processes including policy, planning, and (2) participation, (3) a lack of appreciation of the characteristics of different decision-making contexts, (4) the technical difficulties in implementing the necessary support tool functionality, and (5) the socio-technical demands of designing tools to be of practical use. This article presents a critical synthesis of ideas from each of these areas and interprets them in terms of design requirements for computer-based models being developed to provide scientific information support for policy and planning. Illustrative examples are given from the field of freshwater resources management. Although computer-based diagramming and modeling tools can facilitate processes of dialogue, they lack adequate simulation capabilities. Component-based models and modeling frameworks provide such functionality and may be suited to supporting problematic or messy decision contexts. However, significant technical (implementation) and socio-technical (use) challenges need to be addressed before such ambition can be realized.

Computer Simulation↗