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At least 991 records · Page 55Linked to original sources

PubMed2000

A methodology for development of configurable remote access measurement system

A configurable remote access measurement system (CRAMS) is designed using an object oriented methodology (OOM) and implemented using the integration of an object oriented language, JAVA, a relational database management system, MS-ACCESS, and an instrumentation software package (LabVIEW). OOM is a powerful technique that is used to manage the complexity of large systems. It allows for easy maintenance and upgrading of the developed systems. The main focus of this paper is to present a detailed procedure for the analysis, design and implementation of CRAMS. The functionality of CRAMS is demonstrated by creating a remotely accessible laboratory environment using a set of programmable and virtual instruments connected to a PC server.

Journal Article↗

PubMedDate not supplied

Ca2+ signaling and calcium binding chaperones of the endoplasmic reticulum.

The endoplasmic reticulum is a centrally located organelle which affects virtually every cellular function. Its unique luminal environment consists of Ca(2+) binding chaperones, which are involved in protein folding, post-translational modification, Ca(2+) storage and release, and lipid synthesis and metabolism. The environment within the lumen of the endoplasmic reticulum has profound effects on endoplasmic reticulum function and signaling, including apoptosis, stress responses, organogenesis, and transcriptional activity. Calreticulin, a major Ca(2+) binding (storage) chaperone in the endoplasmic reticulum, is a key component of the calreticulin/calnexin cycle which is responsible for the folding of newly synthesized proteins and glycoproteins and for quality control pathways in the endoplasmic reticulum. The function of calreticulin, calnexin and other endoplasmic reticulum proteins is affected by continuous fluctuations in the concentration of Ca(2+) in the endoplasmic reticulum. Thus, changes in Ca(2+) concentration may play a signaling role in the lumen of the endoplasmic reticulum as well as in the cytosol. Recent studies on calreticulin-deficient and transgenic mice have revealed that calreticulin and the endoplasmic reticulum may be upstream regulators in the Ca(2+)-dependent pathways that control cellular differentiation and/or organ development.

Animals↗

PubMed2002

Signal transduction pathways in human spermatozoa.

Following ejaculation, sperm functions are regulated by interactions with the environment found in the female genital tract. Here spermatozoa become 'capacitated' (i.e. they acquire the capability of completing the acrosome reaction and successfully fertilizing the egg), through a series of surface and intracellular transformations occurring during a process known as capacitation. The limited number of spermatozoa that eventually reach the oocyte must then cross the surrounding cumulus cells before contacting the zona pellucida, undergoing the acrosome reaction and finally fertilizing the oocyte. All the interactions between sperm and their diverse environments are mediated by intracellular signaling pathways. Virtually all the signaling systems known to operate in somatic cells, with the exception of those implying nuclear activity, have been found in spermatozoa, although in some cases the function(s) of the pathway has not been clearly proved.

Calcium Signaling↗

PubMed1996

Situational smoke toxicity testing: hazard assessment as the 'front end' of a smoke toxicity test.

Traditionally, the toxic potency of the smoke from a material or product is part of the assessment of the fire hazard in a given scenario. The assessment also requires a knowledge of virtually all the details of the fire environment and, until they are identified, a 'safe' or 'acceptable' level of smoke toxicity is a term without meaning. This paper suggests a method of using the knowledge of these factors to simplify smoke toxicity testing. Faster, cheaper, and better-targeted smoke toxicity tests would result if the rest of the hazard assessment were carried out first. This is accomplished by determining or specifying all the relevant fire properties except the toxic potency, identifying the other environmental conditions (such as those typical of an aircraft cabin interior) and the desired tenability limits (such as the minimum necessary escape time), and then solving the equations for the buildup of toxic conditions in terms of the single remaining unknown, the toxic potency. The result is the greatest toxic potency which would meet the requirements of the analysis. In this approach, a material or product is acceptable if its smoke is no more toxic then the computed result and unacceptable if it is not. It would not be necessary to obtain an EC50 (product concentration which will cause an effect in half the animals) or dose-response profile, only the response at whatever dose is dictated by the analysis. Two sample cases are presented to illustrate the technique.

Administration, Inhalation↗

PubMed2003

Collaborative environment for clinical reasoning and distance learning sessions.

BACKGROUND: The medical curriculum has changed with the adoption of the student-centered learning paradigm. Clinical reasoning learning (CRL) is used in order to develop and improve students' clinical reasoning and problem-solving skills. PURPOSE: We have observed that, in complement to traditional CRL sessions, students commonly consult resources available on the internet. Based on this observation, our objective is to create computer tools to coordinate CRL sessions at distance, integrating these electronic resources at every step of the reasoning process. MATERIAL AND METHODS: In order to create the system, we elaborated an object-oriented model of a computer-supported collaborative learning environment. The proposed system includes a local web-server to store electronic resources and a relational database to store their electronic addresses (urls). JAVA was used as the programming language. RESULTS: We developed a set of cooperative platform-independent tools. This environment includes a communication tool. Multimedia data exchange is possible. Information is shared thanks to an electronic notepad and whiteboard tools. PERSPECTIVES: This learning environment will be integrated in the French Virtual Medical University project, and is intended to be used for undergraduate, internships, residency or continuing medical education.

Computers, Handheld↗

PubMed1997

Density Functional Study of the Primary Photoprocesses of Manganese Pentacarbonyl Chloride (MnCl(CO)(5)).

Density functional calculations have been performed on the ground and excited states of MnCl(CO)(5) in order to explain the photochemistry of MX(CO)(5) complexes (M = Mn, Re; X = Cl, Br, I). As found earlier for Mn(2)(CO)(10) (Inorg. Chem. 1996, 35, 2886), the e(g)-type unoccupied 3d orbitals in the pseudooctahedral environment are located rather high in the virtual orbital spectrum, and the corresponding ligand-field (LF) excitations are more than 1 eV above the lowest excitations. Potential energy curves (PECs) nevertheless show that the lowest excited states, which involve transitions to the Mn-Cl sigma orbital at equilibrium geometry, are dissociative for axial and equatorial CO loss. The mechanism is again, as in Mn(2)(CO)(10), a strongly avoided crossing of the lowest excited state (a(1,3)E) with the higher dissociative LF states (different ones for CO(ax) and CO(eq) dissociation) which rapidly descend upon Mn-CO bond lengthening. In spite of the lowest excitation being to the Mn-Cl sigma-orbital, Mn-Cl homolysis cannot occur out of the lowest excited state. The photochemical behavior of Mn(2)(CO)(10), MnH(CO)(5), and MnCl(CO)(5) is compared. The mechanisms of CO loss are found to be very similar, but there is a large difference with respect to the breaking of the sigma bond (Mn-Mn, Mn-H, or Mn-Cl). Only in the case of Mn(2)(CO)(10), the lowest broad absorption band contains the sigma --> sigma excitation and leads to sigma bond breaking.

Journal Article↗

PubMed2003

A virtual reality system for neurobehavioral and functional MRI studies.

We are developing a VR system of integrated software and hardware for scientific research and clinical application. The system is sufficiently flexible and broad-based in appeal that neurobehavioral researchers from a variety of disciplines might be interested in using it for basic research and clinical studies. The system runs on a standard Windows-based personal computer with a high-performance graphics card. Options allow a head-mounted display, dataglove, simultaneous physiological monitoring or use within neuroimaging machines such as magnetic resonance imaging (MRI) scanners. Currently, the software consists of a virtual world of nearly a dozen interconnected environments that the subject can freely navigate. Additional environments can be built and easily added to the application. A startup interface provides menus for selecting characters and objects that a researcher might want to put at specific locations within the simulation. Interactivity is provided for many typical objects such as doors, chairs and money. There are more than 50 characters in the world, most of them animated or interactive. All movements and actions of the subject within the world are tracked and recorded to an Excel spreadsheet for data analysis. Overlay maps are available as navigational aids. Concurrent physiological data can be acquired on up to 16 channels. The system provides synchronization of the VR simulation with physiological recordings and functional MR images. A spatial navigation memory task was performed with the integrated VR/fMRI system, and some pilot data is presented that shows robust activation in multiple cortical areas appropriate to the task.

Brain↗

PubMed1995

Culture of preimplantation embryos: facts and artifacts.

Mammalian preimplantation embryos normally develop within the protected environment of the female reproductive tract, which virtually precludes studies on embryogenesis in situ. Information must therefore be derived from experiments on cultured embryos. Consequently, studies on the epigenetic regulation of embryogenesis have long been interwoven with efforts to formulate culture media capable of sustaining normal development. In this review, comparative information on epigenetic regulation of embryo development is discussed, including information on energy substrate and amino acid preferences of embryos. Advantages of simple versus complex culture media, and of substituting serum albumin or synthetic macromolecules for serum, are discussed. Some potential pitfalls of co-culture are described. Culture appears to induce anomalies in embryo metabolism, which may derive from disturbed intracellular pH. Rationales for selecting endpoints to evaluate the outcome of experiments are considered, including incorporation of timing of embryo development into the analysis. Poor experimental design and/or data analysis can detract from or even negate the value of data obtained from embryo culture; examples are examined to help correct this problem. All of these points are discussed with a view to using data on the needs of embryos for making improvements in the design of culture media, so that higher yields and increased viability of embryos are achieved.

Animals↗

PubMedDate not supplied

Does fitness erode in the absence of selection? An experimental test with Tribolium.

In the absence of natural selection, average fitness in the population is expected to decline due to the accumulation of deleterious mutations. Replicate populations of flour beetles (Tribolium confusum) were maintained for 22 generations in the virtual absence of selection (random mating, favorable environment, excess of food, and mortality of only 3%). Larva-to-adult survivorship rates were similar in the stock population and selection-free populations. In contrast, starvation resistance of adult beetles from selection-free populations was significantly reduced (by more than 2% per generation). When tested in the favorable environment, beetles in one selection-free population had significantly slower development and smaller sizes of females than beetles from the stock population. Since such changes in these fitness components are usually maladaptive, they indicate possible erosion of fitness under relaxed selection at the rate of 0.1-0.2% per generation. No fitness erosion was detectable in the second selection-free population.

Animals↗

PubMed1997

Joint kinematics simulation from medical imaging data.

A method for joint kinematics simulation is described. Kinematics parameters are determined from the relative displacement of marker sets placed on anatomical landmarks of surface models generated from medical imaging contour data. The landmarks are identified manually on fingers in multiple positions. A mathematical algorithm was then used to ascertain the kinematics axes of motion of the fingers. Once these axes are located, they are used as the base of a real time interactive simulation of the finger. The entire simulation was accomplished in a high-resolution graphics environment. A full complement of interactive tools (virtual dials and buttons controlled via mouse) was used to enhance the user interface. The development of the system, the model and the advantages and disadvantages of the method are discussed.

Arthrography↗

PubMed1999

An architecture for bridging between research and practical use in health informatics.

Health informatics is a true interdisciplinary research discipline combining computer engineering, health science and fields dealing with organisation and communication issues. Much of the research published within the area has a common goal: to develop optimal information systems for better access to relevant data, information, and knowledge in the health care sector. As a respond to existing discontinuity between research and practical use, we present an architecture for an interdisciplinary virtual organisation promoting synergy across health informatics environments including research, industry, clinical, and educational settings. A set of key lessons learned from a practical implementation of the architecture are reported.

Computer Communication Networks↗

PubMed2005

Emotional and performance attributes of a VR game: a study of children.

In this paper we present the results of a study to determine the effect and efficacy of a Virtual Reality game designed to elicit movements of the upper extremity. The study is part of an on-going research effort to explore the use of Virtual Reality as a means of improving the effectiveness of therapy for children with motor impairments. The current study addresses the following questions: 1. Does a VR game requiring repetitive motion sufficiently engage a child? 2. Are there detrimental physiological or sensory side-effects when a child uses an HMD-based VR? 3. Are the movements produced by a child while playing a VR game comparable to movements produced when carrying out a similar task in the real-world? Based on study results, the enjoyment level for the game was high. ANOVA performed on the results for physical well-being pre- and post-VR showed no overall ill-effects as perceived by the children. Playing the game did not effect proprioception based on pre- and post-VR test scores. Motion data show similar, but not identical, overall movement profiles for similar tasks performed in the real and virtual world. Motor learning occurs in both environments, as measured by time to complete a game cycle.

Child↗

PubMed1988

Selecting patients when resources are limited: a study of US medical directors of kidney dialysis and transplantation facilities.

This study reports and discusses responses of 453 medical directors of renal dialysis and transplantation facilities to detailed patient selection questionnaires. The questionnaires examine selection criteria being used today as well as those which would be employed were resources to remain or become scarce relative to need. Selection criteria examined (and the number of directors supporting them when resources are limited) are: qualitative prognosis, psychological stability, likelihood of medical benefit, quantitative prognosis, medical benefit (virtually all); willingness, age (very large majority); unique moral duties, disproportionate resources, environment, progress of science, social value (majority); ability to pay, random selection, constituency (very large minority); sex (virtually none). Qualitative prognosis, quantitative prognosis, medical benefit, ability to pay, and especially age are the criteria employed today whose influence would increase if resources are further limited. Some of the ethical implications of various criteria are discussed.

Eligibility Determination↗

PubMed2006

Spatial knowledge of children with spina bifida in a virtual large-scale space.

The spatial knowledge of 18 children with spina bifida and 18 healthy control children (matched according to sex, age, and verbal IQ) was investigated in a computer-simulated environment. All children had to learn a route through a virtual floor system containing 18 landmarks. Controlling for cognitive abilities, the results revealed that children with spina bifida showed impaired route knowledge but not an impaired landmark knowledge. Thus the results suggest that children with spina bifida are not impaired in all large-scale abilities similarly. The impairments of the children with spina bifida are more accentuated in more behaviour based measurements, which indicates a relation to the reduced mobility of the children with spina bifida.

Child↗

PubMed1983

[Animal feed additives, veterinary drugs and the environment].

The use of feed additives and veterinary drugs is an established feature in current animal production practices. Having been administered to the animals, these compounds are excreted virtually in toto in the faeces and urine, thus reaching the environment (soil, surface water) in their initial form and/or in the form of metabolites. In the present paper, the extent of environmental pollution by residues of feed additives and animal drugs, the resulting problems and the requirements of the authorities as regards the collection of information on the environmental impact of this type of compounds, are briefly reviewed. Finally, some instances of studies done in this field are presented.

Animal Feed↗

PubMed1999

The digital library: an oxymoron?

"Virtual libraries" and "digital libraries" have become stock phrases of our times. But what do they really mean? While digital refers to a new form of document encoding and must be approached from that perspective, virtual resonates with aspects that modern philosophy treats with benign neglect at best. The word virtual harbors the notion of potential, and therein lies its hidden strength. Although strong commercial interests try to use the shift to a digital environment to redefine the political economy of knowledge, and thus virtualize libraries into a state of almost complete impotence, all hope is not lost. Librarians of virtualized libraries may well discover that they have re-empowered institutions if they place human interaction at the heart of their operations. In other words, rather than envisioning themselves as knowledge bankers sitting on treasure vaults of knowledge, they should see themselves as "hearts" dynamizing human communities. They should also see themselves as an essential part of these communities, and not as external repositories of knowledge. In this fashion, they will avoid the fate of becoming an oxymoron.

Forecasting↗

PubMedDate not supplied

New frontiers in design synthesis.

The Intelligent Synthesis Environment (ISE), which is one of the major strategic technologies under development at NASA centers and the University of Virginia, is described. One of the major objectives of ISE is to significantly enhance the rapid creation of innovative affordable products and missions. ISE uses a synergistic combination of leading-edge technologies, including high performance computing, high capacity communications and networking, human-centered computing, knowledge-based engineering, computational intelligence, virtual product development, and product information management. The environment will link scientists, design teams, manufacturers, suppliers, and consultants who participate in the mission synthesis as well as in the creation and operation of the aerospace system. It will radically advance the process by which complex science missions are synthesized, and high-tech engineering Systems are designed, manufactured and operated. The five major components critical to ISE are human-centered computing, infrastructure for distributed collaboration, rapid synthesis and simulation tools, life cycle integration and validation, and cultural change in both the engineering and science creative process. The five components and their subelements are described. Related U.S. government programs are outlined and the future impact of ISE on engineering research and education is discussed.

Astronauts↗

PubMedDate not supplied

Contrasting influence of the living environment and gender on systemic hypertension in Saudi population of Gassim, Saudi Arabia.

In a cross-sectional total population survey of Faizia East Primary Health District of Buraidah, which is divided into an "urban" and "rural" sections, casual blood pressure was recorded in 5671 subjects. 2222 (910 males) were adults (> 19 years). 3299 (1561 males) were between 3-18 years, making the paediatric/adolescent cohort of the population. The rest were below 3 years and were not included for calculations in this report. For adults, HPN was defined as > or = 140/90 mm Hg and P/A it was > or = 95th percentile for the age cohorts 3-5, 6-9, 10-12, 13-15 and 16-18 years as recommended by The Task Force for Blood Pressure Control in Children (1987). Each of the three subsets of HPN were derived from these basic definitions without modification. In the adults population, overall prevalence (S/DHPN + ISHPN + IDHPN) was 23.58% (524/2222) and gender prevalence was marginal in favour of males (25.71 vs 22.1% for males and females respectively; OR: 1.22, chi square = 3.89; p = 0.05; CI: 1.00 < OR < 1.49). By contrast, overall HPN prevalence in P/A was 10.64% (351/3299) and in all the age cohorts, girls were very significantly more hypertensive than boys. Overall figures were 13.06 vs 7.94% respectively for girls and boys; OR: 0.57; chi square = 22.65; p < 0000019; CI: 0.45 < OR < 0.73. Only in severe HPN (> or = 99th percentile) in 16-18 year age cohort did male preponderance become obvious. When the influence of the living environment was examined, in adult population (urban: 40,001; rural: 1670 subjects), for all age cohorts the rural environment which is largely inhabited by the unsophisticated Bedouins living close to their livestock, significantly predisposed to HPN as compared to the urban setting. Overall figures are 19.95 vs 32.60%, urban vs rural respectively: OR: 0.52; chi square = 40.4; p < 0.000000; CI: 0.42 < OR < 0.64. On the other hand, in the P/A population (2301 urban, 998 rural) for the age cohorts 3-5 and 6-9 years the urban environment significantly predisposed to HPN. At 10-12 years the prevalence was virtually even (12.65 vs 12.71%; OR: 0.99; p: NS). Thereafter, i.e. 13-15, 16-18 year cohorts, the rural environment became more dominant, just like the adult pattern. In other words whatever the factors in the unsophisticated Bedouin "rural" setting which predisposes to HPN does not become operative until after childhood--after 12 years. This contrasting gender and environmental influence in our study population seems unique, being reported for the first time. It may be pointing us in new direction in the elucidation of the pathogenesis of HPN and should deserve further studies.

Adolescent↗