Search results for "VOLUME"
showing 10 items of 1932 documents
Problems in Precise Measurement of Tidal Volumes
1998
Respiratory gas flows and volumes can conveniently be measured by pneumo-tachography.3 However, the pneumotachographic signal depends on gas temperature, humidity, and composition, and therefore the achievable precision of measurement is limited to about 5–10%2,8 — which is not sufficient for determining the human ventilation distribution with satisfactory accuracy.6,7,5 As a — potentially more accurate — alternative, a plethysmographic method may be used in which the tested subject breathes out of and into bags that are suspended in a large tank of constant volume (Figure 1). Volume V and pressure P in the system (consisting of tank, tubings, valves, and the subject) are related via Boyle-…
Musica y significado
2000
This article discusses both classical theories of musical meaning, the imitative one and the expressive one, wich share a referentialist idea of meaning. It also criticizes the sintacticist choice of formalism as well. Opposite to all these views, the paper outlines an explanation of musical meaning inspired in the later linguistic philosophy o Wittgenstein. El artículo discute las clásicas teorías imitativa y expresiva del significado de la música, que comparten una noción referencialista del significado, y critica asimismo la alternativa sintacticista del formalismo. Frente a estas posiciones, propone una explicación del significado de la música inspirada en la filosofía del lenguaje del …
Advances in the Testing of the Hydro-mechanical Behaviour of Shales
2013
The paper presents some of the advanced experimental techniques and apparatuses that have been developed by the authors for testing the hydromechanical behaviour of shales. A methodology established for the analysis of the water retention behaviour in non-isochoric conditions is introduced; the method allows for the determination of the main drying and wetting paths in addition to the volume change response upon total suction variations. A high-pressure oedometric cell is then presented; the apparatus allows for the analysis of the transition from the pre-yield behaviour to the normally consolidated state. The analysis of the settlement versus time curves yields information on the permeabil…
Electromechanical coupling in anodic niobium oxide: Electric field-induced strain, internal stress, and dielectric response
2012
Seemingly, contradictory results have been reported so far for electrostriction in anodic oxides. Furthermore, no definitive agreement could be obtained with theory. In this paper, in situ techniques are combined to elucidate electrostriction in anodic niobium oxide. The dependence of strain, internal stress, and dielectric constant on the electric field is measured by, respectively, spectroscopic ellipsometry, curvature, and impedance measurements. The through-thickness strain is tensile and proportional to the square of the electric field. The in-plane internal stress is compressive and proportional to the square of the electric field at low field values. The internal stress is predicted …
Oxygenation Status of Rhabdomyosarcoma Spheroids with Different Stages of Differentiation
1994
Multicellular tumor spheroids with regional heterogeneities of proliferation and substrate concentrations have been investigated recently to study the biological properties of small tumor nodules prior to onset of vascularization (for reviews see: Mueller-Klieser, 1987; Sutherland, 1988).
Bestimmung des Verteilungsvolumens von intrahepatisch injizierten Kontrastmittellösungen: Voruntersuchungen zur intratumoralen Gentherapie
2002
PURPOSE Determination of the intrahepatic distribution volume of two contrast media (CM) by CT-guided application in an ex-vivo and an in-vivo model (pig liver). MATERIAL AND METHODS In pig livers ex-vivo and in-vivo, 131 CT-guided injections of two different CM (Imagopaque(R), Visipaque(R)) were performed using catheters and cannula with and without side-holes and documented by spiral CT. The distribution pattern was assessed visually: interstitial, subcapsular, vascular/tubular, the distribution volume was quantified using a density mask (thresholds 70/400 HE). RESULTS Purely interstitial applications were achieved more frequently in-vivo than ex-vivo (p = 0.001). There were no relevant d…
Retention–property relationships of anticonvulsant drugs by biopartitioning micellar chromatography
2001
Epilepsy may be considered as a group of disorders with only one thing in common: the fact that recurrent anomalous electrochemical phenomena appear in the central nervous system. Different classes of drugs are included under the generic term of anticonvulsant drugs. All of them work by decreasing discharge propagation in different ways. Biopartitioning micellar chromatography (BMC) is a mode of reversed-phase liquid chromatography, which can be used as an in vitro system to model the biopartitioning process of drugs when there are no active processes. In this paper, relationships between the BMC retention data of anticonvulsant drugs, their pharmacokinetics (oral absorption, protein bindin…
Physiological pharmacokinetic model for ceftazidime disposition in the rat and its application to prediction of plasma concentrations in humans
1993
Abstract A physiological pharmacokinetic model for the disposition of ceftazidime in the rat was developed. The model is composed of 10 compartments which represent most of the organs and tissues of the body. Ceftazidime concentration-time profiles in the organs and tissues represented in the model were simulated and compared with the observed concentration-time data after i.v. administration of 5 and 20 mg of antibiotic. The model gave an acceptable description of the observed data. The steady-state volume of distribution and total clearance of ceftazidime in healthy humans predicted from data obtained in the rat (0.21 l/kg and 113 ml/min, respectively) were similar to the values reported …
Retention pharmacokinetic and pharmacodynamic parameter relationships of antihistamine drugs using biopartitioning micellar chromatography
2001
Abstract Antihistamines are drugs which act by competitive inhibition of the H1 or H2 histamine receptors. Little has been known about their clinical pharmacokinetics and biological responses until the last few years. In this paper, we propose quantitative retention–activity relationship, QRAR, models based on the retention data of antihistamines in a biopartitioning micellar chromatography (BMC) system using a Brij35 mobile phase for describing pharmacokinetic parameters such as half-life and volume of distribution, or the pharmacodynamic parameters, therapeutic plasma levels, lethal doses and drug-receptor dissociation constant. The predictive ability of these models is statistically vali…
Pharmacokinetics of the cannabinoid receptor ligand [18 F]MK-9470 in the rat brain - Evaluation of models using microPET
2018
PURPOSE The positron emission tomography ligand [18 F]MK-9470 is an inverse agonist that binds reversibly and with high affinity to the cannabinoid type 1 receptor. Due to its slow brain kinetics, care is required in the definition of its dissociation rates from the receptor. The goal of this study was to investigate pharmacokinetic analysis methods using an arterial input function. METHODS Five Sprague-Dawley rats received injections of 13 to 25 MBq of [18 F]MK-9470 and were scanned over a period of 90 min. Arterial blood samples were collected throughout the scan. Data were analyzed using four different compartmental models: a reversible one-tissue model, reversible two tissue models with…