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PubMedDate not supplied

[The carbon dioximeter: a device for quantifying the carbon dioxide released from effervescent pharmaceuticals].

Since effervescent pharmaceuticals are more sensitive to ambient humidity during the manufacturing process and storage, the strict control of their carbon dioxide content becomes a prerequisite to guarantee their physicochemical stability. Indirect gravimetry is a simple and precise method that consists in taking the weight before and after the effervescent reaction allowing to determine the released amount of carbon dioxide. Some authors have used it with devices that lead to longer analysis times and poor accuracy of measurements (due to the excess of released carbon dioxide). The device that we have built (proposed name "CARBONDIOXIMETER") is very easy to set up, and yields quick, accurate, precise and reproducible results. An assay takes three minutes in an acidic medium and five minutes in carbon dioxide free water). Moreover, through the interconnection of scales, registration and treatment of the results can be performed by a printer or a computer. Thus, the "Carbondioximeter" is contributing to the control of physicochemical stability of effervescent pharmaceuticals during the manufacturing process and storage.

Carbon Dioxide↗

PubMed1995

Digital chest radiography at the University of Chicago: present status and future plans.

Storage-phosphor computed radiography and film digitization systems have been in routine clinical use at the University of Chicago for several years. During this time we have implemented numerous modifications including techniques for scatter reduction, image processing enhancements and display systems to improve the image quality and utility of these devices. We have also evaluated the image quality and functionality of digital systems relative to conventional screen-film radiography. In this paper, we review our experience and summarize our impressions. In addition, we summarize our plans for a rapid transition into picture archiving and communication systems, with hardcopy interpretation being phased out for most modalities over the next 2 to 5 years.

Chicago↗

PubMed2004

Brain-computer interface design for asynchronous control applications: improvements to the LF-ASD asynchronous brain switch.

The low-frequency asynchronous switch design (LF-ASD) was introduced as a direct brain-computer interface (BCI) technology for asynchronous control applications. The LF-ASD operates as an asynchronous brain switch (ABS) which is activated only when a user intends control and maintains an inactive state output when the user is not meaning to control the device (i.e., they may be idle, thinking about a problem, or performing some other action). Results from LF-ASD evaluations have shown promise, although the reported error rates are too high for most practical applications. This paper presents the evaluation of four new LF-ASD designs with data collected from individuals with high-level spinal cord injuries and able-bodied subjects. These new designs incorporated electroencephalographic energy normalization and feature space dimensionality reduction. The error characteristics of the new ABS designs were significantly better than the LF-ASD design with true positive rate increases of approximately 33% for false positive rates in the range of 1%-2%. The results demonstrate that the dimensionality of the LF-ASD feature space can be reduced without performance degradation. The results also confirm previous findings that spinal cord-injured subjects can operate ABS designs to the same ability as able-bodied subjects.

Adult↗

PubMed1989

Distributed computer system for capture, analysis and display of biological data.

A distributed real-time computer system has been developed to automate the collection, analysis and display of biological (pharmacological) data. It comprises a series of laboratory interface devices (CED 1401/1609) connected to a micro-VAX II via multiple IEEE-488 buses. The micro-VAX II is integrated to the main site computers using Ethernet running DECnet. The micro-VAX II system supports a multi-user, multipreparation and multitasking environment and it provides rapid transfer, storage, analysis and display of data. The system saves the pharmacologists from the manual analysis of their data, typically saving them four days of analysis per experiment and has improved both the quality of data detected and their subsequent analysis. Also, the development of a standard data capture procedure on common hardware along with the modular design of application software has almost quartered project development times.

Computer Communication Networks↗

PubMed2000

Clinical Consequences of New Insights in the Pathophysiology of Disorders of Iron and Heme Metabolism.

This review examines the clinical consequences for the practicing hematologist of remarkable new insights into the pathophysiology of disorders of iron and heme metabolism. The familiar proteins of iron transport and storage-transferrin, transferrin receptor, and ferritin-have recently been joined by a host of newly identified proteins that play critical roles in the molecular management of iron homeostasis. These include the iron-regulatory proteins (IRP-1 and -2), HFE (the product of the HFE gene that is mutated in most patients with hereditary hemochromatosis), the divalent metal transporter (DMT1), transferrin receptor 2, ceruloplasmin, hephaestin, the "Stimulator of Fe Transport" (SFT), frataxin, ferroportin 1 and others. The growing appreciation of the roles of these newly identified proteins has fundamental implications for the clinical understanding and laboratory evaluation of iron metabolism and its alterations with iron deficiency, iron overload, infection, and inflammation. In Section I, Dr. Brittenham summarizes current concepts of body and cellular iron supply and storage and reviews new means of evaluating the full range of body iron stores including genetic testing for mutations in the HFE gene, measurement of serum ferritin iron, transferrin receptor, reticulocyte hemoglobin content and measurement of tissue iron by computed tomography, magnetic resonance imaging and magnetic susceptometry using superconducting quantum interference device (SQUID) instrumentation. In Section II, Dr. Weiss discusses the improved understanding of the molecular mechanisms underlying alterations in iron metabolism due to chronic inflammatory disorders. The anemia of chronic disorders remains the most common form of anemia found in hospitalized patients. The network of interactions that link iron metabolism with cellular immune effector functions involving pro- and anti-inflammatory cytokines, acute phase proteins and oxidative stress is described, with an emphasis on the implications for clinical practice. In Section III, Dr. Brissot and colleagues discuss how the diagnosis and management of hereditary hemochromatosis has changed following the identification of the gene, HFE, that is mutated in most patients with hereditary hemochromatosis, and the subsequent development of a genotypic test. The current understanding of the molecular effects of HFE mutations, the usefulness of genotypic and phenotypic approaches to screening and diagnosis and recommendations for management are summarized.

Journal Article↗

PubMed2004

An efficient rhythmic component expression and weighting synthesis strategy for classifying motor imagery EEG in a brain-computer interface.

The recognition of mental states during motor imagery tasks is crucial for EEG-based brain-computer interface research. We have developed a new algorithm by means of frequency decomposition and weighting synthesis strategy for recognizing imagined right- and left-hand movements. A frequency range from 5 to 25 Hz was divided into 20 band bins for each trial, and the corresponding envelopes of filtered EEG signals for each trial were extracted as a measure of instantaneous power at each frequency band. The dimensionality of the feature space was reduced from 200 (corresponding to 2 s) to 3 by down-sampling of envelopes of the feature signals, and subsequently applying principal component analysis. The linear discriminate analysis algorithm was then used to classify the features, due to its generalization capability. Each frequency band bin was weighted by a function determined according to the classification accuracy during the training process. The present classification algorithm was applied to a dataset of nine human subjects, and achieved a success rate of classification of 90% in training and 77% in testing. The present promising results suggest that the present classification algorithm can be used in initiating a general-purpose mental state recognition based on motor imagery tasks.

Algorithms↗

PubMed2000

Computers in imaging and health care: now and in the future.

Early picture archiving and communication systems (PACS) were characterized by the use of very expensive hardware devices, cumbersome display stations, duplication of database content, lack of interfaces to other clinical information systems, and immaturity in their understanding of the folder manager concepts and workflow reengineering. They were implemented historically at large academic medical centers by biomedical engineers and imaging informaticists. PACS were nonstandard, home-grown projects with mixed clinical acceptance. However, they clearly showed the great potential for PACS and filmless medical imaging. Filmless radiology is a reality today. The advent of efficient softcopy display of images provides a means for dealing with the ever-increasing number of studies and number of images per study. Computer power has increased, and archival storage cost has decreased to the extent that the economics of PACS is justifiable with respect to film. Network bandwidths have increased to allow large studies of many megabytes to arrive at display stations within seconds of examination completion. PACS vendors have recognized the need for efficient workflow and have built systems with intelligence in the management of patient data. Close integration with the hospital information system (HIS)-radiology information system (RIS) is critical for system functionality. Successful implementation of PACS requires integration or interoperation with hospital and radiology information systems. Besides the economic advantages, secure rapid access to all clinical information on patients, including imaging studies, anytime and anywhere, enhances the quality of patient care, although it is difficult to quantify. Medical image management systems are maturing, providing access outside of the radiology department to images and clinical information throughout the hospital or the enterprise via the Internet. Small and medium-sized community hospitals, private practices, and outpatient centers in rural areas will begin realizing the benefits of PACS already realized by the large tertiary care academic medical centers and research institutions. Hand-held devices and the Worldwide Web are going to change the way people communicate and do business. The impact on health care will be huge, including radiology. Computer-aided diagnosis, decision support tools, virtual imaging, and guidance systems will transform our practice as value-added applications utilizing the technologies pushed by PACS development efforts. Outcomes data and the electronic medical record (EMR) will drive our interactions with referring physicians and we expect the radiologist to become the informaticist, a new version of the medical management consultant.

Computers↗

PubMed2005

DNA as a programmable viscoelastic nanoelement.

The two strands of a DNA molecule with a repetitive sequence can pair into many different basepairing patterns. For perfectly periodic sequences, early bulk experiments of Pörschke indicate the existence of a sliding process, permitting the rapid transition between different relative strand positions. Here, we use a detailed theoretical model to study the basepairing dynamics of periodic and nearly periodic DNA. As suggested by Pörschke, DNA sliding is mediated by basepairing defects (bulge loops), which can diffuse along the DNA. Moreover, a shear force f on opposite ends of the two strands yields a characteristic dynamic response: An outward average sliding velocity v approximately 1/N is induced in a double strand of length N, provided f is larger than a threshold fc. Conversely, if the strands are initially misaligned, they realign even against an external force f < fc. These dynamics effectively result in a viscoelastic behavior of DNA under shear forces, with properties that are programmable through the choice of the DNA sequence. We find that a small number of mutations in periodic sequences does not prevent DNA sliding, but introduces a time delay in the dynamic response. We clarify the mechanism for the time delay and describe it quantitatively within a phenomenological model. Based on our findings, we suggest new dynamical roles for DNA in artificial nanoscale devices. The basepairing dynamics described here is also relevant for the extension of repetitive sequences inside genomic DNA.

Base Pairing↗

PubMed2004

Quicktime virtual reality technology in light microscopy to support medical education in pathology.

The new computer-based interactive technologies in medicine, such as virtual reality (VR), have revolutionized education. The use of virtual microscopic images would be invaluable in the training of cyto-histopathologists. However, due to the vast amount of digital information on a scanned, conventional cyto-histological slide, which is enormous by current data storage standards, these systems are expensive and not widely used in pathological medicine. The authors propose an inexpensive system based on quicktime virtual reality (QTVR) technology (by Apple Computers Inc.), which accommodates a wide area of a slide at high magnification, generating a 'virtual slide' which makes it possible to navigate by conventional input devices. Commercial softwares that stitch consecutive, adjacent images of cyto-histological preparations onto a QTVR panorama were used. QTVR files have the ability to stand on their own as self-contained, multimedia applications and also have the ability to generate multinode scenes by means of 'hot spots'. QTVR 'movies' can be played on Macintosh or Windows platforms, and on major web browsers. Virtual slides by QTVR is an inexpensive system of high educational value, which allows the creation of multimedia databases of cyto-histological preparations that can exist on an internet server or can be distributed on removable media.

Databases as Topic↗

PubMed1985

[Computerized report of anesthesia in real time].

The computerized report of anesthesia (C.R.A.) is an equivalent of the document filled out by the anesthesiologist, linked to a multicriteria research program giving the opportunity to study connections between different performances of anesthesia. To obtain these results, the authors are introducing a microcomputerized system in real time, including a microcomputer (capacity 64 kO), a visual display monitor (80 column format), two floppy disks controllers and a printer. Through a "menu", there is an access to the following functions: identity, patient story, drug prescriptions, anesthetics used, chronology of administration, monitoring of parameters, incidents/accidents, multicriteria research, editing of the C.R.A. The operational realisation shows that this computerized system offers storage capacity and allows a retrospective analysis of anesthesia. As it is inexpensive and easy to use, it may become a very important device in every-day practice.

Anesthesia, General↗

PubMed1998

PACS and CR implementation in a level I trauma center emergency department.

Implementation of a picture archive and communication system (PACS) at a large teaching hospital is an expensive and daunting endeavor. The approach taken at the University of Alabama Hospitals has been to assemble an institution-wide system through focused integration of smaller mini-PACS. Recently a mini-PACS using Computed Radiography (CR) has been placed in the Emergency Department (ED) of a Level I Trauma Center completely replacing conventional screen-film radiography. This area of the hospital produces approximately 250 images per day and provided many challenging requirements: the need for rapid radiography; providing good image quality for difficult examinations with potentially uncooperative patients; reproduction of lost films to maintain availability of images to multiple consulting teams; and frequently unknown patient demographics. The PACS includes both vendor-supplied and in-house developed devices for image storage, distribution, and display. Digital images are produced using two photo-stimulable phosphor CR systems. Currently, all radiographic examinations are acquired digitally with production of a hard copy film as well as electronic distribution via the PACS. Interpretation of images is done primarily via hard copy with a goal of transition to soft copy interpretation. This paper discusses the functional requirements of the PACS and solutions to workflow issues arising in the ED.

Alabama↗

PubMed2005

Identification of the defective transmission devices using the wavelet transform.

In this paper, a system is described that uses the wavelet transform to automatically identify the particular failure mode of a known defective transmission device. The problem of identifying a particular failure mode within a costly failed assembly is of benefit in practical applications. In this system, external acoustic sensors, instead of intrusive vibrometers, are used to record the acoustic data of the operating transmission device. A skilled factory worker, who is unfamiliar with statistical classification, helps to determine the feature vector of the particular failure mode in the feature extraction process. In the automatic identification part, an improved learning vector quantization (LVQ) method with normalizing the inputting feature vectors is proposed to compensate for variations in practical data. Some acoustic data, which are collected from the manufacturing site, are utilized to test the effectiveness of the described identification system. The experimental results show that this system can identify the particular failure mode of a defective transmission device and find out the causes of failure successfully.

Acoustics↗

PubMed2005

Touch a screen or turn a knob: choosing the best device for the job.

Input devices enable users to interact with systems. In two experiments, we assessed whether and how task demands and user age influenced task performance for a direct input device (touch screen) and an indirect input device (rotary encoder). In Experiment 1, 40 younger (18-28 years) and 40 middle-aged to older adults (51-65 years) performed tasks using controls such as sliders, up/down buttons, list boxes, and text boxes while using a system. The optimal input device to facilitate performance was dependent on the task being performed and the age of the user. In Experiment 2, touch screen use was assessed for 20 younger (19-23 years) and 20 older adults (51-70 years). Task demands were manipulated through button size, movement distance, direction, and type of movement. Performance was moderated by the age of the user and by task demands. Actual or potential applications of this research include guidance for the optimal selection of input devices for different user populations and task characteristics.

Adolescent↗

PubMed1989

Image management and communication systems: a new challenge in radiology.

The spectacular advances in diagnostic imaging technologies, such as CT, MRI, and NM, have improved the quality of radiological diagnosis. On the other hand, the vast amount of image data produced by these digital modalities have created unique problems in managing the information. The increased use of digital imaging systems has set the stage for the development of comprehensive medical image and information management systems for large medical facilities. These image management and communication systems (IMACS) vary, depending on imaging, display and output devices connected, network configurations used, and storage devices available. This paper will discuss the important technical aspects in developing an IMACS network, imaging devices ideally suited for connection to an IMACS, integration with computerized hospital and radiology information systems, performance issues, clinical acceptance and specific implementation experience.

Computer Communication Networks↗

PubMed1991

Electronic system for digital acquisition of rotational panoramic radiographs.

A prototype system for digital panoramic imaging of the maxillofacial complex has been developed. In this system x-ray film is replaced by an electronic sensor that delivers the image information to a computer for storage in digital format. The images, which are similar to conventional panoramic radiographs, are displayed on a high-resolution video monitor and may be stored on optical disk for future use. Hard-copy output is also available. The present prototype system has been installed on an Orthopantomograph model OP10 panoramic x-ray machine is programmed for operation with this machine, but in principle the system can be installed on any such device. The system may be incorporated into the design of future panoramic x-ray systems or may be used to retrofit panoramic x-ray systems now using photographic film to record the radiographic image. Greater sensitivity of electronic sensors should make possible a reduction of x-ray dose to the patient, compared with film-based systems.

Analog-Digital Conversion↗

PubMed2005

Space-dependent color gamut mapping: a variational approach.

Gamut mapping deals with the need to adjust a color image to fit into the constrained color gamut of a given rendering medium. A typical use for this tool is the reproduction of a color image prior to its printing, such that it exploits best the given printer/medium color gamut, namely the colors the printer can produce on the given medium. Most of the classical gamut mapping methods involve a pixel-by-pixel mapping and ignore the spatial color configuration. Recently proposed spatial-dependent approaches for gamut mapping are either based on heuristic assumptions or involve a high computational cost. In this paper, we present a new variational approach for space-dependent gamut mapping. Our treatment starts with the presentation of a new measure for the problem, closely related to a recent measure proposed for Retinex. We also link our method to recent measures that attempt to couple spectral and spatial perceptual measures. It is shown that the gamut mapping problem leads to a quadratic programming formulation, guaranteed to have a unique solution if the gamut of the target device is convex. An efficient numerical solution is proposed with promising results.

Algorithms↗

PubMed2004

Development of a protocol for cryopreservation of hepatocytes for use in bioartificial liver systems.

Porcine hepatocytes are considered the cell type of choice for bioartificial liver and cell transplantation techniques in support of patients with liver failure. A protocol for cryopreservation of hepatocytes that function adequately after thawing would allow on-demand usage and long-term storage. We conducted experiments to evaluate the freeze rate, concentration of hepatocytes during storage, and the effect of a pre-incubation step prior to freezing on cryopreserved hepatocytes isolated from 15 porcine livers. Cell return, attachment, LDH leakage, bilirubin conjugation, and lignocaine metabolism were tested to assess the effects of the interventions. No significant differences were found between a computer-controlled freeze rate, the Nalgene propan-2-ol device, or simply using -20 degrees C and -80 degrees C freezers. Trials at a range of hepatocyte concentrations did not produce significant differences. Pre-incubation did not confer any advantage to the thawed hepatocytes. In conclusion, porcine hepatocytes can be cryopreserved using a simple method of temperature reduction at a concentration of 5x10(6) hepatocytes/ml. Such hepatocytes can potentially be used for bioartificial livers; however, further investigation is required to explain the large cell losses that occur during cryopreservation.

Animals↗

PubMed2004

Giant room-temperature magnetoresistance in single-crystal Fe/MgO/Fe magnetic tunnel junctions.

The tunnel magnetoresistance (TMR) effect in magnetic tunnel junctions (MTJs) is the key to developing magnetoresistive random-access-memory (MRAM), magnetic sensors and novel programmable logic devices. Conventional MTJs with an amorphous aluminium oxide tunnel barrier, which have been extensively studied for device applications, exhibit a magnetoresistance ratio up to 70% at room temperature. This low magnetoresistance seriously limits the feasibility of spintronics devices. Here, we report a giant MR ratio up to 180% at room temperature in single-crystal Fe/MgO/Fe MTJs. The origin of this enormous TMR effect is coherent spin-polarized tunnelling, where the symmetry of electron wave functions plays an important role. Moreover, we observed that their tunnel magnetoresistance oscillates as a function of tunnel barrier thickness, indicating that coherency of wave functions is conserved across the tunnel barrier. The coherent TMR effect is a key to making spintronic devices with novel quantum-mechanical functions, and to developing gigabit-scale MRAM.

Computers↗