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[en] Random walks of molecular motors, which bind to and unbind from cytoskeletal filaments, are studied theoretically. The bound and unbound motors undergo directed and nondirected motion, respectively. Motors in open compartments exhibit anomalous drift velocities. Motors in closed compartments generate stationary nonequilibrium states with spatially varying densities of the motor concentrations and currents. ''Traffic jams'' on the filaments lead to a maximum of the motor current at an optimal motor concentration. Quantitative estimates based on experimental data for bound motors indicate that these transport phenomena are accessible to experiments
[en] The several types of biological compartments are studied such as monocompartmental system, one-compartment balanced system irreversible fluxes, two closed compartment system, three compartment systems, catenary systems and mammilary systems
[pt]Estudam-se os varios tipos de compartimentos biologicos, a saber: sistema monocompartimental, sistema de um compartimento em equilibrio, fluxos irreversiveis, sistema a dois compartimentos fechados, sistemas de tres compartimentos, sistemas catenarios e sistemas mamilares
[en] Purpose: To evaluate the tibiotalar joint capacity and the localisation, frequency and amount of extravasation in patients with extraarticular contrast material leakage into adjacent synovial compartments on ankle magnetic resonance (MR) arthrography. Materials and methods: Sites of extravasation were determined in the ankle MR arthrograms of 69 patients. Thirty-four patients without extraarticular contrast material leakage into locations unrelated to the injection path were included as a control group. Volumetric measurements of extraarticular contrast material leakage and the tibiotalar joint capacity were performed on a three dimensional (3D) volume measurement workstation. Results: Extravasation of contrast material occurred through the anterior, posterior, and anterolateral recesses of the tibiotalar joint. The most common site of extravasation was along the flexor hallucis longus tendon synovium (24.6%). The amount of extravasation was significantly higher in patients with ankle osteochondritis dissecans (OCD) than in patients with a different diagnosis (p = 0.039). Loose bodies were detected in all OCD’s patients with insufficient tibiotalar joint distention. Conclusions: Connections between the ankle joint and neighboring synovial compartments can decrease the diagnostic value of ankle MR arthrography examinations due to inadequate joint distention. Large injection volumes should be used for ankle MR arthrography of patients with OCD (especially OCD’s patients with loose body) and impingement syndrome.
[en] Most calorimeter systems used in particle physics experiments are longitudinally subdivided into several compartments. The intercalibration of these compartments is highly non-trivial, as a result of two effects: 1) The dependence of the calorimeter response on the type (and energy) of the showering particle, and 2) The depth dependent sampling fraction of showers.The problems arising from this are illustrated with examples from the scientific literature. I also review some of the methods applied in practice to calibrate segmented calorimeters, and discuss the (lack of) merit of these methods
[en] Coupling both thermography and bio-Impedance, some biophysical acupuncture mechanisms are statically studied on a small population of 18 subjects. Results show that a possible way of understanding acupuncture, in an electrical way, should be to consider ionic flux redistribution between vascular and extra cell compartments. This is a two steps mechanism. The first one is starting with needles insertion and the second one is lasting with more intensity after removing them from skin.
[en] Two kinds of tracer method are used to estimate the lung water pools differing by the tracer intake and the sector observed. Airborne intake gives an estimate of the tissues irrigated by the lung and bronchial circulation, whereas vascular intake only shows the sectors perfused by the lung flow. Either of these methods is suitable for a general or regional analysis. In general methods the tracer is followed at the lung exit on expired air for the first method, on peripheral arterial blood for the second. Regional methods imply partial or whole-lung external detection systems
[fr]Deux types de methodes permettent une estimation des compartiments eau pulmonaire a l'aide de traceurs. Elles different par l'entree du traceur et le secteur observe. L'entree aerienne permet une estimation des tissus irrigues par la circulation pulmonaire et bronchique, alors que l'entree vasculaire ne voit que les secteurs perfuses par la circulation pulmonaire. L'une ou l'autre de ces methodes se pretent a une analyse globale ou regionale. Dans les methodes globales le traceur est suivi a la sortie du poumon, sur l'air expire pour la premiere methode, sur le sang arteriel peripherique pour la seconde. Les methodes regionales impliquent des systemes de detection externe partiels, ou de l'ensemble du poumon
[en] An experiment was carried out to provide a data set specifically designed to allow the development of a model to describe the dynamic behaviour of radiocaesium in sheep tissue. A single intraruminal dose of 134CsCl was given to each of 15 Scottish Blackface ewes, aged 1-2 years. Radiocaesium activity concentrations were measured at various time intervals after dosing in blood, faeces and urine and, after slaughter, in a range of tissues and digestive tract contents. A first order compartment model was developed comprising nine compartments representing various organs and tissues in the body. Rate constants for the model were obtained by optimisation to the experimental results. A limited validation of the model was carried out by using it to calculate tissue transfer coefficients (Ff and biological half-lives (T0.5) of radiocaesium in sheep. The values generated compare favourably with published figures. Applications for the model and constraints on its usage are examined along with possibilities for further development. (Author)
[en] A simple method is proposed to calculate the accumulation of activities in the preferential organs of deposition and in the routes of excretion, applicable to different intake rates, in an attempt to improve dose calculation using bioassay data. The method was proved reliable after several tests. (author)
[en] A conventional single compartment model cannot simulate reasonably the migration phenomenon of contaminants through unsaturated zone, due to the intrinsic unrealistic assumption of the compartment model that contaminants entering a compartment are immediately and uniformly mixed. Although, a multi-compartments model, in which even physically identical layer is divided into multiple compartments, may be used for explaining the retardation of contaminant mass flux along with increasing number of compartments, its numerical modeling is usually time-consuming and appropriate analytical solutions have not been reported yet. In order to improve the conventional compartment models on contaminant migration through unsaturated zone, a series of analytical solutions for multi-compartments model were derived and a generalized constraint under which the results from multi-compartments model can be simply approximated by single compartment model was proposed. The simplified approximation method was verified by a simple numerical analysis on the constraint under hypothetical conditions. It was also proved that the influent contaminant transfer rate from the bulk unsaturated zone can be generally represented into a time-dependent nominal transfer rate rather than a constant. In addition, the nominal transfer rate turned out to be very sensitive to the contaminant transfer rate between compartments in unsaturated zone, but to be almost insensitive to the transfer rate from contaminated zone