Physiolibrary is a free open-source Modelica library designed for modeling human physiology. It is accessible on the Modelica Libraries web page at https://www.modelica.org/libraries. This library contains basic physical laws governing human physiology, usable for cardiovascular circulation, metabolic processes, nutrient distribution, thermoregulation, gases transport, electrolyte regulation, water distribution, hormonal regulation and pharmacological regulation.

ABSTRACT. 14C activity of dissolved inorganic carbon (DIC) in water and in recent tufa samples in several karst areas of Yugoslavia and Czechoslovakia was measured. Groundwater from 11 karst springs were measured for their isotopic content (14C, 3H, 13C), chemical composition (HCO3, Cat+, Mgt+) and physico-chemical properties (temperature, pH). Seasonal variations of the 14C activity of DIC in two karst springs in Plitvice Lakes area, Yugoslavia, were measured systematically from 1979 -1987.14C activity of recent tufa samples from several locations downstream were also measured. The activity of DIC in karst spring water in both countries ranged from 63-87 pMC, which is attributed to differences in geologic structure of the recharge area, topsoil thickness and composition. Grouping of 1 C activities of DIC ca (82±4)% is evident. Tritium activity at all the springs indicated short mean residence time (1-10 yr). Concentration of HCO3, Caz+ and Mg2+ in spring water varied with geomorphology. '4C activity of streamwater and recent tufa increased downstream from karst springs due to the exchange between atmospheric CO2 and DIC.

BackgroundSimulators used in teaching are interactive applications comprising a mathematical model of the system under study and a graphical user interface (GUI) that allows the user to control the model inputs and visualize the model results in an intuitive and educational way. Well-designed simulators promote active learning, enhance problem-solving skills, and encourage collaboration and small group discussion. However, creating simulators for teaching purposes is a challenging process that requires many contributors including educators, modelers, graphic designers, and programmers. The availability of a toolchain of user-friendly software tools for building simulators can facilitate this complex task.ObjectiveThis paper aimed to describe an open-source software toolchain termed Bodylight.js that facilitates the creation of browser-based client-side simulators for teaching purposes, which are platform independent, do not require any installation, and can work offline. The toolchain interconnects state-of-the-art modeling tools with current Web technologies and is designed to be resilient to future changes in the software ecosystem.MethodsWe used several open-source Web technologies, namely, WebAssembly and JavaScript, combined with the power of the Modelica modeling language and deployed them on the internet with interactive animations built using Adobe Animate.ResultsModels are implemented in the Modelica language using either OpenModelica or Dassault Systèmes Dymola and exported to a standardized Functional Mock-up Unit (FMU) to ensure future compatibility. The C code from the FMU is further compiled to WebAssembly using Emscripten. Industry-standard Adobe Animate is used to create interactive animations. A new tool called Bodylight.js Composer was developed for the toolchain that enables one to create the final simulator by composing the GUI using animations, plots, and control elements in a drag-and-drop style and binding them to the model variables. The resulting simulators are stand-alone HyperText Markup Language files including JavaScript and WebAssembly. Several simulators for physiology education were created using the Bodylight.js toolchain and have been received with general acclaim by teachers and students alike, thus validating our approach. The Nephron, Circulation, and Pressure-Volume Loop simulators are presented in this paper. Bodylight.js is licensed under General Public License 3.0 and is free for anyone to use.ConclusionsBodylight.js enables us to effectively develop teaching simulators. Armed with this technology, we intend to focus on the development of new simulators and interactive textbooks for medical education. Bodylight.js usage is not limited to developing simulators for medical education and can facilitate the development of simulators for teaching complex topics in a variety of different fields.

Recently, mathematical models of human integrative physiology, derived from Guyton’s classic 1972 model of the circulation, have been used to investigate potential mechanistic abnormalities mediating salt-sensitivity and salt-induced hypertension. We performed validation testing of two of the most evolved derivatives of Guyton’s 1972 model, QCP-2005 and HumMod-3.0.4, to determine if the models accurately predict sodium balance and hemodynamic responses of normal subjects to increases in salt intake within the real-life range of salt intake in humans. Neither model, nor the 1972 Guyton model, accurately predicts the usual changes in sodium balance, cardiac output, and systemic vascular resistance that normally occur in response to clinically realistic increases in salt intake. Furthermore, although both contemporary models are extensions of the 1972 Guyton model, testing revealed major inconsistencies between model predictions with respect to sodium balance and hemodynamic responses of normal subjects to short-term and long-term salt loading. These results demonstrate significant limitations with the hypotheses inherent in Guyton models regarding the usual regulation of sodium balance, cardiac output and vascular resistance in response to increased salt intake in normal salt-resistant humans. Accurate understanding of the normal responses to salt loading is a prerequisite for accurately establishing abnormal responses to salt loading. Accordingly, the present results raise concerns about the interpretation of studies of salt sensitivity with the various Guyton models. These findings indicate a need for continuing development of alternative models that incorporate mechanistic concepts of blood pressure regulation fundamentally different from those in the 1972 Guyton model and its contemporary derivatives.

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The integrative model of human physiology connects individual physiological subsystems into a single unit. They are enormous (contain thousands of variables) and represent a formalized description of interconnected physiological regulations. The issue of formalization of physiological systems became part of a series of international projects (e.g. the worldwide program "PHYSIOME", or the European program "VIRTUAL PHYSIOLOGICAL HUMAN"). The development of large-scale models of human physiology was facilitated by a new generation (i.e. equation-based) of simulation environments, especially by the Modelica language. These models can be used to explain the causal relations of the pathogenesis of many diseases. They can be applied in the evaluation of clinical trials and they can also be used in the core of sophisticated medical simulators.

We studied the structure and development of the Holocene floodplain of the Labe (Elbe) River by radiocarbon dating sections of the upper and middle courses of the river. We focused on geomorphological and sedimentological conditions, mineralogy and the chemical composition of sediments. We established the stratigraphy of the Holocene deposits of the floodplain. The results of our investigation of fluvial sediments imply that several abrupt changes in temperature and precipitation occurred during the Holocene. These changes led to intervals of hydrological disequilibrium, which caused the formation of two Holocene terraces and a contemporaneous floodplain. The lower terrace was flooded and covered with sediments upon which the recent floodplain formed. During the Holocene, there were four periods during which large tree trunks were deposited in the fluvial sediments, indicating periods of extensive flooding. The supposition that these events were of more global scale is supported by the results of investigations made on the Holocene floodplains of other regions.

The present paper introduces a recently developed tool for building web-based simulators called Bodylight.js. Simulators are applications composed of a mathematical model and a graphical user interface that allows the user to easily interact with the model and visualize the results. A modelica model is first exported to FMI with sources, transcompiled into JavaScript and WebAssembly and connected to a GUI, comprised of graphical animations created in Adobe Animate and elements that allow to control the input model such as sliders, buttons, etc. A physiological e-learning application explaining the function of a nephron-the basic functional unit of kidneys-is presented later as a use-case. The model was developed primarily as a teaching aid for use in courses of physiology for medical students at our university. Purpose of this work is to describe the new Bodylight.js tool and to prove its usability by building the medium-complex e-learning kidney simulator. The simulator helps medical students to better understand renal function at the very basic level.