Search results for "imulation"
showing 10 items of 7271 documents
Bivariate nonlinear prediction to quantify the strength of complex dynamical interactions in short-term cardiovascular variability.
2005
A nonlinear prediction method for investigating the dynamic interdependence between short length time series is presented. The method is a generalization to bivariate prediction of the univariate approach based on nearest neighbor local linear approximation. Given the input and output series x and y, the relationship between a pattern of samples of x and a synchronous sample of y was approximated with a linear polynomial whose coefficients were estimated from an equation system including the nearest neighbor patterns in x and the corresponding samples in y. To avoid overfitting and waste of data, the training and testing stages of the prediction were designed through a specific out-of-sampl…
Teachers' instructional scaffolding in an innovative information and communication technology-based history learning environment
2002
Abstract The nature of the role assumed by the teacher is crucial in the promotion of successful learning and collaboration in Information and Communication Technologybased (ICT-based) environments. The aim of this study was to examine how teachers with different conceptions of their teacher roles use different types of instructional scaffolding while working in an innovative learning environment. Our further aim was finding out how instructional scaffolding is related to learning activities of different kinds. The study was carried out at two secondary schools with a shared network-based learning environment. The results showed that teachers with different conceptions of the teacher's role…
Physiological and agonistic behavioural response of Procambarus clarkii to an acoustic stimulus
2012
Summary This study examined the effects of an acoustic stimulus on the haemolymph and agonistic behaviour of the red swamp crayfish Procambarus clarkii. The experiment was conducted in a tank equipped with a video recording system using 6 groups (3 control and 3 test groups) of five adult crayfish (30 specimens in total). After one hour of habituation, the behaviour of the crayfish was monitored for two hours. During the second hour, the animals in the test groups were exposed to a linear sweep (frequency range 0.1-25 kHz; peak amplitude 148 dBrms re 1 µPa at 12 kHz) acoustic stimulus for 30 minutes. Exposure to the noise produced significant variations in haemato-immunological parameters a…
A multicompartment model for open-loop control of glucose in insulin-dependent diabetics
1990
This paper describes a model that has been developed for individually adjusted therapy management in insulin-dependent diabetics. The multicompartment model considers all relevant aspects of glucose kinetics and its dependence on insulin. The structure of the model reflects that of the physiological system. Its parameters can be classified into (a) general parameters that are independent of the individual, (b) classifying parameters that are related systematically to the individual, and (c) distinguishing parameters. Classifying parameters allow a very convenient adjustment to relevant features of the individual like sex, age, body weight and length. The model can be employed in open-loop c…
Acute changes of systemic parameters in tumour-bearing rats, and of tumour glucose, lactate, and ATP levels upon local hyperthermia and/or hyperglyca…
1991
Arterial blood pressure and relevant parameters of the arterial blood (O2 and CO2 tensions, pH, haematocrit, serum electrolytes and osmolality) were determined in tumour-bearing rats upon local hyperthermia (HT) and/or hyperglycaemia (HG). Tumour heating was performed in a saline bath (44 degrees C) for 120 min; hyperglycaemia was induced by i.v. infusion of 40% glucose solution for 150 min [blood glucose levels: 35-40 mM during heating; total amount of glucose: 1.19 g/100 g body wt.; infusion rates: 0.31 ml (100 g body wt.)-1 min-1 for 2 min, 0.02 ml (100 g body wt.)-1 min-1 for 88 min, and 0.01 ml (100 g body wt.)-1 min-1 for 60 min]. Immediately after treatment, glucose, lactate and ATP …
Real-time estimation of plasma insulin concentration from continuous glucose monitor measurements
2015
Continuous glucose monitors can measure interstitial glucose concentration in real time for closed-loop glucose control systems, known as artificial pancreas. These control systems use an insulin feedback to maintain plasma glucose concentration within a narrow and safe range, and thus to avoid health complications. As it is not possible to measure plasma insulin concentration in real time, insulin models have been used in literature to estimate them. Nevertheless, the significant interand intra-patient variability of insulin absorption jeopardizes the accuracy of these estimations. In order to reduce these limitations, our objective is to perform a real-time estimation of plasma insulin co…
Obesity interferes with the orosensory detection of long-chain fatty acids in humans
2014
Background: The association between the orosensory detection of lipids, preference for fatty foods, and body mass index (BMI; in kg/m 2 ) is controversial in humans. Objective: We explored the oral lipid-sensing system and the orosensory-induced autonomic reflex system in lean and obese subjects. Design: Lean (BMI: 19 to ,25; n = 30) and obese (BMI .30; n = 29) age-matched men were enrolled. Their oral threshold sensitivity to linoleic acid (LA) was determined by using a 3-alternative forced-choice ascending procedure, and their eating habits were established by the analysis of 4 consecutive 24-h food-consumption diaries. The effect of brief oral lipid stimulations on plasma triglyceride [(…
The effects of cold and glucagon on lipolysis, glycogenolysis and oxygen consumption in young chicks.
1973
Abstract 1. 1. To study the possible role of glucagon in avian thermoregulation the effects of cold exposure and glucagon on lipolysis, glycogenolysis and oxygen consumption were measured in young chicks. 2. 2. Cold exposure (+10°C) and glucagon injection (0·3 mg/kg, i.p. at +30°C) both caused a marked increase in the plasma FFA and a decrease in the liver glycogen content. 3. 3. It is suggested that glucagon possibly acts in the avian thermoregulation by producing at least lipolysis and glycogenolysis during cold exposure.
Altered cellular magnesium responsiveness to hyperglycemia in hypertensive subjects.
2001
Abstract — — Previous studies by our group have identified ionic aspects of insulin resistance in hypertension, in which cellular responses to insulin were influenced by the basal intracellular ionic environment—the lower the cytosolic free magnesium (Mg i ), the less Mg i increased following insulin stimulation. To investigate whether this ionic insulin resistance represents a more general abnormality of cellular responsiveness in hypertension, we studied Mg i responses to nonhormonal signals such as hyperglycemia (15 mmol/L) and used 31 P-nuclear magnetic resonance (NMR) spectroscopy to measure Mg i in erythrocytes from normal (NL, n=14) and hypertensive (HTN, n=12) subjects before and 3…
In-vitro and Ex-vivo Inhibition of Blood Platelet Aggregation by Naftazone
1996
Abstract Because of the considerable interest in the role of platelets and antiplatelet therapy in cardiovascular disease, including the aggregation of platelets to each other during arterial thrombosis and atherogenesis, we have studied the effect of naftazone (Etioven), an original vasculotropic drug on platelet aggregation. Rat and human platelets were prepared and incubated in-vitro with different concentrations of naftazone. We found that naftazone inhibited both platelet secretion and aggregation in platelet-rich plasma (PRP) and washed platelets after stimulation with thrombin or ADP. Rats were also treated intraperitoneally for five days with various naftazone doses (0.125-10 mg kg−…