896 research outputs found
Continuous intravascular blood gas monitoring: development, current techniques, and clinical use of a commercial device
This review focuses on the development, current techniques, and clinical use of continuous intravascular blood gas monitoring (CIBM) devices in anaesthesia and intensive care. The operating principles, range of application, performance, limitations, costs, and impact on patient treatment and outcome, are discussed. Studies of early and currently available CIBM devices were analysed. At present, the Paratrend 7+® (PT7+®) for adults and Neotrend™ (NT™) for newborns are the only commercially available CIBM systems. The PT7+® contains three optical sensors to measure Po2, Pco2 and pH, as well as a thermocouple to measure temperature. The NT™ is a modification of the PT7+® to continuously monitor Po2, Pco2, pH and temperature in newborns. Under laboratory conditions, good performance over a wide range of blood gas values was observed with the Paratrend 7® (PT7®). Performance in the clinical setting was not as satisfactory, especially for Po2 values. However, the performance and accuracy of CIBM devices appear to be sufficient for clinical use and they are being used clinically in selected patient groups. Several factors affecting the performance of CIBM are considered. Br J Anaesth 2003: 91; 397-40
Continuous intravascular blood gas monitoring: development, current techniques, and clinical use of a commercial device
This review focuses on the development, current techniques, and clinical use of continuous intravascular blood gas monitoring (CIBM) devices in anaesthesia and intensive care. The operating principles, range of application, performance, limitations, costs, and impact on patient treatment and outcome, are discussed. Studies of early and currently available CIBM devices were analysed. At present, the Paratrend 7+® (PT7+®) for adults and Neotrend™ (NT™) for newborns are the only commercially available CIBM systems. The PT7+® contains three optical sensors to measure Po2, Pco2 and pH, as well as a thermocouple to measure temperature. The NT™ is a modification of the PT7+® to continuously monitor Po2, Pco2, pH and temperature in newborns. Under laboratory conditions, good performance over a wide range of blood gas values was observed with the Paratrend 7® (PT7®). Performance in the clinical setting was not as satisfactory, especially for Po2 values. However, the performance and accuracy of CIBM devices appear to be sufficient for clinical use and they are being used clinically in selected patient groups. Several factors affecting the performance of CIBM are considered. Br J Anaesth 2003: 91; 397-40
Präoperative Nüchternzeiten: Sicht der Patienten
Zusammenfassung: Hintergrund: Mit dem Ziel der subjektiven perioperativen Qualitätsverbesserung scheint es wünschenswert, die präoperativen Nüchternzeiten im Rahmen der als sicher geltenden Grenzen so kurz als möglich zu halten. Diese Maßnahmen sollten mit einer messbaren Verminderung von präoperativem Hunger und Durst einhergehen und v.a. in einer Verbesserung der präoperativen Befindlichkeit resultieren. Welchen Einfluss Durst und Hunger aus Patientensicht auf den präoperativen Komfort haben, ist jedoch weit gehend unbekannt. Ziel dieser Studie war es, das Ausmaß der Beeinträchtigung der Patienten durch eine traditionelle Nüchternheitsregelung abzuschätzen. Patienten und Methoden: Ein Kollektiv von 412Patienten der "American-Society-of-Anesthesiologists"- (ASA-)RisikoklassenI und II, das sich einem kleineren chirurgischen Eingriff unterzog, wurde mithilfe eines Fragebogens zum Ausmaß und Stellenwert von präoperativem Durst und Hunger befragt. Ergebnisse: Es hatten 33% der Patienten mäßigen oder starken Durst, 19% mäßigen bis starken Hunger. Von den Befragten möchten 47% vor der Operation noch trinken, 72% hätten gern noch ein leichtes Frühstück eingenommen. Die mittlere Nüchternzeit war 12,8±3,4h für Flüssigkeiten und 15,5±4,4h für Essen. Durst wurde von 3,3% und Hunger von 0,8% der Patienten als Hauptgrund für die Beeinträchtigung des präoperativen Wohlbefindens genannt. Das lange Warten (8,5%), Nervosität (6,5%) und Angst (4,8%) wurden am häufigsten genannt. Die Antworten waren unabhängig von der Zeitdauer der präoperativen Nüchternheit. Schlussfolgerung: Der Patientenkomfort ist durch eine traditionelle Nüchternheitsregelung beeinträchtigt, und Minimierung der präoperativen Nüchternzeiten wird von den Patienten gewünscht. Anstrengungen mit dem Ziel der Reduktion von präoperativer Angst und Nervosität bergen jedoch zusätzliches großes Potenzial für eine Steigerung der perioperativen Behandlungsqualität aus Sicht der Patiente
APPLICABILITY OF A FULL BODY INERTIAL MEASUREMENT SYSTEM FOR KINEMATIC ANALYSIS OF THE DISCUS THROW
The aim of the study was the application of a full body inertial measurement system (IMS) for a kinematic analysis of the discus throw and the evaluation of its applicability. For this purpose, one male sports student performed three discus throws equipped with the IMS. All trials were additionally filmed by high-speed video. The results indicate that perfor-mance-relevant information can be obtained regarding the temporal coordination of the body segments and body joint angles. Limitations exist for the accurate detection of the last foot contact related instant and the discus release instant by solely using the IMS data
A coproduct structure on the formal affine Demazure algebra
In the present paper we generalize the coproduct structure on nil Hecke rings
introduced and studied by Kostant-Kumar to the context of an arbitrary
algebraic oriented cohomology theory and its associated formal group law. We
then construct an algebraic model of the T-equivariant oriented cohomology of
the variety of complete flags.Comment: 28 pages; minor revision of the previous versio
Empirical comparison of high gradient achievement for different metals in DC and pulsed mode
For the SwissFEL project, an advanced high gradient low emittance gun is
under development. Reliable operation with an electric field, preferably above
125 MV/m at a 4 mm gap, in the presence of an UV laser beam, has to be achieved
in a diode configuration in order to minimize the emittance dilution due to
space charge effects. In the first phase, a DC breakdown test stand was used to
test different metals with different preparation methods at voltages up to 100
kV. In addition high gradient stability tests were also carried out over
several days in order to prove reliable spark-free operation with a minimum
dark current. In the second phase, electrodes with selected materials were
installed in the 250 ns FWHM, 500 kV electron gun and tested for high gradient
breakdown and for quantum efficiency using an ultra-violet laser.Comment: 25 pages, 13 figures, 5 tables. Follow up from FEL 2008 conference
(Geyongju Korea 2008) New Title in JVST A (2010) : Vacuum breakdown limit and
quantum efficiency obtained for various technical metals using DC and pulsed
voltage source
Towards semantic web mining
Semantic Web Mining aims at combining the two fast-developing research areas Semantic Web and Web Mining. The idea is to improve, on the one hand, the results of Web Mining by exploiting the new semantic structures in the Web; and to make use of Web Mining, on the other hand, for building up the Semantic Web. This paper gives an overview of where the two areas meet today, and sketches ways of how a closer integration could be profitable
Getting the phase consistent: The importance of phase description in balanced steady-state free precession MRI of multicompartment systems
Purpose: Determine the correct mathematical phase description for balanced
steady-state free precession (bSSFP) signals in multicompartment systems.
Theory and Methods: Based on published bSSFP signal models, two distinct phase
descriptions can be formulated: one predicting the presence and the other
predicting the absence of destructive interference effects in multicompartment
systems. Numerical simulations of bSSFP signals of water and acetone were
performed to evaluate the predictions of these two distinct phase descriptions.
For experimental validation, bSSFP profiles were measured at 3T using
phase-cycled bSSFP acquisitions performed in a phantom containing mixtures of
water and acetone, which replicates a system with two signal components.
Localized single voxel MRS was performed at 7T to determine the relative
chemical-shift of the acetone-water mixtures. Results: Based on the choice of
phase description, the simulated bSSFP profiles of water-acetone mixtures
varied significantly, either displaying or lacking destructive interference
effects, as predicted theoretically. In phantom experiments, destructive
interference was consistently observed in the measured bSSFP profiles of
water-acetone mixtures, an observation which excludes the phase description
that predicts an absence of destructive interference. The connection between
the choice of phase description and predicted observation enables an
unambiguous experimental identification of the correct phase description for
multicompartment bSSFP profiles, which is consistent with Bloch equations.
Conclusion: The study emphasizes that consistent phase descriptions are crucial
for accurately describing multi-compartment bSSFP signals, as incorrect phase
descriptions result in erroneous predictions.Comment: Submitted to Magn. Reson. Me
Quantitative Concept Analysis
Formal Concept Analysis (FCA) begins from a context, given as a binary
relation between some objects and some attributes, and derives a lattice of
concepts, where each concept is given as a set of objects and a set of
attributes, such that the first set consists of all objects that satisfy all
attributes in the second, and vice versa. Many applications, though, provide
contexts with quantitative information, telling not just whether an object
satisfies an attribute, but also quantifying this satisfaction. Contexts in
this form arise as rating matrices in recommender systems, as occurrence
matrices in text analysis, as pixel intensity matrices in digital image
processing, etc. Such applications have attracted a lot of attention, and
several numeric extensions of FCA have been proposed. We propose the framework
of proximity sets (proxets), which subsume partially ordered sets (posets) as
well as metric spaces. One feature of this approach is that it extracts from
quantified contexts quantified concepts, and thus allows full use of the
available information. Another feature is that the categorical approach allows
analyzing any universal properties that the classical FCA and the new versions
may have, and thus provides structural guidance for aligning and combining the
approaches.Comment: 16 pages, 3 figures, ICFCA 201
On the high-density expansion for Euclidean Random Matrices
Diagrammatic techniques to compute perturbatively the spectral properties of
Euclidean Random Matrices in the high-density regime are introduced and
discussed in detail. Such techniques are developed in two alternative and very
different formulations of the mathematical problem and are shown to give
identical results up to second order in the perturbative expansion. One method,
based on writing the so-called resolvent function as a Taylor series, allows to
group the diagrams in a small number of topological classes, providing a simple
way to determine the infrared (small momenta) behavior of the theory up to
third order, which is of interest for the comparison with experiments. The
other method, which reformulates the problem as a field theory, can instead be
used to study the infrared behaviour at any perturbative order.Comment: 29 page
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