The ancient Lake Albano tunnel: origins and considerations regarding the hydraulic regulation achieved

2007 ◽  
Vol 7 (1) ◽  
pp. 269-276
Author(s):  
R. Drusiani ◽  
P. Bersani ◽  
P. Penta
Keyword(s):  
Mathematical Model ◽  
Ancient Lake ◽  
Model Simulations ◽  
Volcanic Lakes ◽  
Colli Albani ◽  
Atmospheric Phenomena

A brief description of the geomorphological, historical, and archaeological aspects of the Colli Albani area, where the volcanic lakes of Albano and Nemi are situated, is followed by an examination on the problem of the policies of lake Albano regulation, by means of an ancient tunnel dating at least to the 5th century BC. In particular, it is investigated how, in the presence of even severe atmospheric phenomena, it was possible to control fluctuations in the level of the lake on the banks of which there were large settlements. Mathematical model simulations indicate the effectiveness of the ancient tunnel in achieving these objectives.

Ouabain modulation of cellular calcium stores and signaling

2007 ◽  
Vol 293 (5) ◽  
pp. F1518-F1532 ◽  
Author(s):  
Aurélie Edwards ◽  
Thomas L. Pallone
Keyword(s):  
Mathematical Model ◽  
Sarcoplasmic Reticulum ◽  
Active Transport ◽  
Intracellular Localization ◽  
Calcium Stores ◽  
Model Simulations ◽  
Store Depletion ◽  
Intracellular Ca ◽  
Atpase Inhibition ◽  
Predominant Effect

Ouabain-like factors modulate intracellular Ca2+ concentrations and Ca2+ stores. Recently, a role for Na+-K+-ATPase Na+ transport inhibition as a pivotal event in ouabain signaling was questioned (Kaunitz JD. Am J Physiol Renal Physiol 290: F995–F996, 2006). In the present study, we used a mathematical model of Ca2+ trafficking in cytoplasm and subplasmalemmal microdomains to simulate the pathways through which ouabain can affect Ca2+ signaling: inhibition of active transport by Na+-K+-ATPase α1- and α2-isoforms, activation of inositol trisphosphate (IP3) production, and increased IP3 receptor (IP3R) conductance. A fundamental prediction is that Na+-K+-ATPase inhibition favors sarcoplasmic reticulum Ca2+ store loading, whereas Src-mediated increases in IP3 production and IP3R sensitization favor store depletion. The model predicts that α2-isoform inhibition generates a peak-and-plateau pattern of cytosolic Ca2+ concentration ([Ca2+]cyt) elevation, whereas α1-isoform inhibition yields a monophasic rise. The effects of ouabain-mediated increases in IP3 production or IP3R conductance on [Ca2+]cyt depend on their relative distributions between cellular microdomains and the bulk cytoplasm. Simulations suggest that the intracellular localization of IP3 production is a pivotal determinant of the changes in compartmental Ca2+ concentrations that can be induced by ouabain. As a consequence of sequestration of the ouabain-sensitive α2-isoform into microdomains, inhibition of the α2-isoform in rodents is not predicted to significantly affect cytosolic Na+ concentration. Model simulations support the hypothesis that ouabain can enhance agonist-evoked [Ca2+]cyt transients when its predominant effect is to inhibit α2-isoform Na+ transport and, thereby, increase Ca2+ loading into sarcoplasmic reticulum stores.

Analysis of anticancer efficiency of combined fractionated radiotherapy and antiangiogenic therapy via mathematical modelling

2018 ◽  
Vol 33 (4) ◽  
pp. 225-242 ◽  
Author(s):  
Maxim B. Kuznetsov ◽  
Vladimir V. Gubernov ◽  
Andrey V. Kolobov
Keyword(s):  
Mathematical Model ◽  
Antiangiogenic Therapy ◽  
Combined Treatment ◽  
Palliative Therapy ◽  
Nutrient Deprivation ◽  
Curative Effect ◽  
Model Simulations ◽  
Fractionated Radiotherapy ◽  
Spatially Distributed ◽  
Preclinical And Clinical Studies

Abstract One of the relatively new modalities in treatment of cancer is antiangiogenic therapy (AAT), which stops the formation of new blood vessels, thus leading to nutrient deprivation of a tumor. It has been discovered that it can cause transient alleviation of intratumoral hypoxia, which has induced interest in investigation of its combination with radiotherapy (RT), since presence of oxygen stimulates efficiency of the latter. Preclinical and clinical studies have shown ambiguous results concerning such combined treatment, indicating a need for theoretical investigation. For that purpose, we have developed a spatially-distributed mathematical model of tumor growth and combined RT with AAT. Model simulations in a physiologically justified range of parameters suggest that outcome of addition of AAT to RT should depend on the tumor radiosensitivity: under its low values, when RT de facto serves as a palliative therapy, inclusion of AAT may prolong patient’s survival; however, under high tumor radiosensitivity, AAT may compromise curative effect of RT.

scholarly journals FPtool a software tool to obtain in silico genotype-phenotype signatures and fingerprints based on massive model simulations

2018 ◽  
Author(s):  
Guido Santos ◽  
Julio Vera
Keyword(s):  
Mathematical Model ◽  
In Silico ◽  
Software Tool ◽  
Biochemical Network ◽  
Qualitative Behaviour ◽  
Model Simulations

Fptool is an intuitive tool that provides to the user a preliminary fingerprint of the behaviour simulated by a mathematical model of a biochemical network when comparing two biological scenarios defined by the user. Here we present the tool and we applied to an already published mathematical model of lung legionella infection. The fingerprint obtained correlates with the results obtained in the original article. This tool is optimal for the users that would like to obtain a fast and preliminary view of the qualitative behaviour of a mathematical model before deciding for more elaborate analyses.

MATHEMATICAL MODELLING OF MACROPHAGE DYNAMICS IN TUMOURS

1999 ◽  
Vol 09 (04) ◽  
pp. 513-539 ◽  
Author(s):  
MARKUS R. OWEN ◽  
JONATHAN A. SHERRATT
Keyword(s):  
Mathematical Model ◽  
Tumour Growth ◽  
Reaction Diffusion ◽  
Model Simulations ◽  
Spatial Dimensions ◽  
Immune Response To Cancer ◽  
Macrophage Chemotaxis ◽  
Numerical Bifurcation ◽  
Spatiotemporal Oscillations ◽  
Dynamical Origin

Macrophages form an important part of the immune response to cancer. In this paper, we present a mathematical model of reaction–diffusion form, which represents the influx of macrophages into a small avascular tumour, and their dynamics within the tumour as it grows. The model predicts that, despite their ability to selectively kill tumour cells, macrophages are unable to prevent tumour growth. However, significant effects on the form of the tumour are predicted, including in particular the formation of spatial patterns. When the model is extended to include macrophage chemotaxis, these patterns can in some cases bifurcate to give irregular spatiotemporal oscillations, and the authors present a detailed numerical bifurcation study which suggests a novel dynamical origin for these oscillations. Finally, we present results of model simulations in two spatial dimensions.

scholarly journals Pump-and-Treat remediation of groundwater contaminated by hazardous waste: can it really be achieved?

2013 ◽  
Vol 3 (1) ◽  
pp. 1-10 ◽  
Keyword(s):  
Experimental Data ◽  
Mathematical Model ◽  
Hazardous Waste ◽  
Chemical Properties ◽  
Water Soluble ◽  
Hazardous Wastes ◽  
Model Simulations ◽  
Pump And Treat ◽  
Small Parts

Pump-and-treat (P&T) is one of the most common methods for remediation of groundwater contaminated by hazardous wastes. However, this method suffers from serious disadvantages, due a series of subsurface processes. Using experimental data and mathematical model simulations, the role of sorption/ desorption and dissolution of non-aqueous phase liquids on the effectiveness of P&T remediation was examined. The results showed that the remediation of groundwater depends directly on the physical/ chemical properties of the contaminants and the hydrogeology of the site. With the exception of water-soluble contaminants occupying relatively small parts of relatively homogeneous and water-permeable geologic media, the remediation of groundwater contaminated by hazardous waste using P&T is, for all practical purposes, impossible and prohibitively expensive.

Short-term control of cardiovascular function: estimation of control parameters in healthy humans

1996 ◽  
Vol 270 (2) ◽  
pp. H651-H660 ◽  
Author(s):  
K. Toska ◽  
M. Eriksen ◽  
L. Walloe
Keyword(s):  
Mathematical Model ◽  
Arterial Pressure ◽  
Closed Loop ◽  
Cardiovascular Responses ◽  
Pressure Control ◽  
Open Loop ◽  
Control Parameters ◽  
Short Term ◽  
Model Simulations ◽  
Healthy Humans

In a previous study, we recorded short-term cardiovascular responses after a steep increase in arterial pressure in healthy humans [Am. J. Physiol. 266 (Heart Circ. Physiol. 35): H199-H211, 1994]. The aim of the present study was to develop a mathematical model of the baroreflex control of arterial pressure, to use this model with the previously recorded data to estimate unknown parameters in the reflex control loop, and then to analyze the overall open- and closed-loop performance of the system by model simulations with use of individual sets of optimal parameters. The mathematical model consists of a heart, a linear elastic arterial reservoir, and two parallel resistive vascular beds. The arterial baroreflex loop is modeled by two separate time domain processing objects, each with its own gain, time constant, and delay, to simulate the action of a sympathetic signal to the peripheral vascular bed and a parasympathetic signal to the heart. In repeated model simulations, the control parameters in the model were systematically adjusted by an automated algorithm that minimized the deviations between the time courses of the cardiovascular variables simulated by the model and the previously recorded responses in each individual. In all 10 subjects, the short-term cardiovascular responses were adequately simulated by using individual sets of parameters in the model. Open-loop transfer functions for arterial pressure control were obtained by using the individual sets of optimal model parameters in new simulation runs. Open-loop gain for arterial pressure control at nearly zero frequency (steady state) was between 0.9 and 4. Model simulations also indicated an underdampened response at 0.05-0.07 Hz in the closed-loop situation in four subjects, corresponding to peaks in the mean arterial pressor power spectra obtained from separate recordings of spontaneous variations in the resting situation.

Water supply of Bologna (Italy) by Roman aqueduct: history, morphology and hydraulic, from ancient time to nowadays

2010 ◽  
Vol 10 (4) ◽  
pp. 554-560
Author(s):  
Renato Drusiani ◽  
Giancarlo Leoni ◽  
Danilo Demaria ◽  
Nicoletta Lembo
Keyword(s):  
Mathematical Model ◽  
Drinking Water ◽  
Water Supply ◽  
Water Level ◽  
3D Model ◽  
Working Condition ◽  
New Era ◽  
Model Simulations ◽  
Ancient Time ◽  
Tunnel Section

A brief description of the geomorphological, historical, and archaeological aspects of the ancient Bononia (now Bologna) supply by means of an ancient tunnel made by Romans at the beginning of the new, era and its evolution to a nowadays when it's already used (13%) to assure drinking water supply of Bologna Town. Recent exploration of the tunnel has permitted to obtain most data of ancient water level signs and size of tunnel section in the different conditions. New data obtained by this exploration allow to build a CAD 3D model of the tunnel and in this way it was possible to calculate the realistic flow of the ancient tunnel. Mathematical model simulations indicate the effectiveness of the ancient tunnel in achieving these objectives in working condition and during the periodical maintenance.

scholarly journals Sleepiness is a signal to go to bed: data and model simulations

SLEEP ◽  
2021 ◽  
Author(s):  
Tamar Shochat ◽  
Nayantara Santhi ◽  
Paula Herer ◽  
Derk-Jan Dijk ◽  
Anne C Skeldon
Keyword(s):  
Mathematical Model ◽  
Individual Variation ◽  
Time Course ◽  
Mixed Model ◽  
Circadian Regulation ◽  
Subjective Measure ◽  
Model Simulations ◽  
Sleep Timing ◽  
Subjective Sleepiness ◽  
Sleep Drive

Abstract Study Objectives Assess the validity of a subjective measure of sleepiness as an indicator of sleep drive by quantifying associations between intra-individual variation in evening sleepiness and bedtime, sleep duration, and next morning and subsequent evening sleepiness, in young adults. Methods Sleep timing and sleepiness were assessed in 19 students in late autumn and late spring on a total of 771 days. Karolinska Sleepiness Scales (KSS) were completed at half-hourly intervals at fixed clock times starting four hours prior to participants’ habitual bedtime, and in the morning. Associations between sleepiness and sleep timing were evaluated by mixed model and non-parametric approaches and simulated with a mathematical model for the homeostatic and circadian regulation of sleepiness. Results Intra-individual variation in evening sleepiness was very large, covering four or five points on the 9-point KSS scale, and was significantly associated with subsequent sleep timing. On average, a one point higher KSS value was followed by 20 min earlier bedtime, which led to 11 min longer sleep, which correlated with lower sleepiness next morning and following evening. Associations between sleepiness and sleep timing were stronger in early compared to late sleepers. Model simulations indicated that the directions of associations between sleepiness and sleep timing are in accordance with their homeostatic and circadian regulation, even though much of the variance in evening sleepiness and details of its time course remain unexplained by the model. Conclusion Subjective sleepiness is a valid indicator of the drive for sleep which, if acted upon, can reduce insufficient sleep.

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