A qualitative approach to cell growth modeling and simulation forcancer chemotherapy

A qualitative model of cell growth that is based on qualitative process theory is presented. The model can be used to analyze the effects of the interaction of antiproliferative drugs on cells when the effects of each specific drug are known, which is useful when designing multidrug protocols for optimal cancer treatment. This model encompasses both structural and behavioral aspects. This makes it suitable for drawing conclusions about differences among different types of cell growth and about system behavior under different situations. adding some significant options with respect to closed-form cell cycle models. Moreover, qualitative modeling, unlike closed-form modeling, allows causal explanations of events: in this respect, the qualitative simulation presented-based on reasoning in terms of processes, individual views. and history limits-makes causes of specific behaviors even clearer than qualitative simulation based on constraints. This model is able to adapt to the amount of information supplied by the user: if this is scarce (only relating to the cell cycle phase on which each drug acts), the model will produce a simulation in which only cell cycle phase information for the combination is present; if the information supplied is more detailed, the simulation output will be more detailed as well     

Practical Applicability and Limitations of the Elastic Modulus Degradation Technique for Damage Measurements in Ductile Metals

Abstract: The use of damage models require a number of material parameters the identification of which should be made, when possible, based on direct measures of the damage that develops in the material. Among the possible experimental techniques to measure the occurrence of ductile damage in metals, the measure of the damage through the degradation of the material Young’s modulus has been indicated as one of the more effective technique and used by several authors. In this paper, this technique is critically reviewed highlighting the number of issues that may affect the measure of damage. In particular, the attention is focused in the case where damage process initiates at the onset necking and develops in the post‐necking regime where stress, strain and damage are no longer uniform in the gauged section. Since geometry variations alter the reference base length for both stress and strain definition, a procedure based on the use of finite element simulation is proposed in order to account for this effect on the measure of the stiffness loss. The procedure has been applied to two class of metals: a high strength steel and high purity copper.     

Electrical Noise and Transport Properties of Graphene

We present a study of the noise properties of single-layer exfoliated graphene as a function of gate bias. A tunnel/trap model is presented based on the interaction of graphene electrons with the underlying substrate. The model incorporates trap position, energy, and barrier height for tunneling into a given trap—along with the band-structure of the graphene—and is in good accord with the general characteristics of the data.     

Radical scavenging activity, anti-bacterial and mutagenic effects of cocoa bean Maillard reaction products with degree of roasting

Raw, pre-roasted and roasted Cocoa samples were separated into four different molecular weight fractions (> 30, 30-10, 10-5 and < 5 kDa) with ultrafiltration and tested for their antibacterial, mutagenic, as well as their radical-scavenging effects. Radical-scavenging effects were tested with electro paramagnetic resonance spectroscopy, anti-mutagenicity in the Salmonella microsome assay (with and without metabolic activation), and antibacterial effects by incubating the fractions with several strains of Bifidobacteria, Enterobacter and Escherichia, and observing their growth. The radical-scavenging activity and reducing substance concentrations increased, particularly in the 5-10-kDa roasted fraction. Chromaticity testing elucidated that the 10-5-kDa fraction was one of the darkest fractions. The Salmonella microsome assay showed neither mutagenic nor anti-mutagenic effects in any of the samples at any of the different concentrations applied when using TA98, TA100 and TA102. All fractions reduced the growth of pathogenic bacteria, in particular at the highest concentration of 100 microg/mL; however, the same trends were also observed for Bifidobacteria.     

Expert systems for cancer chemotherapy

In the present paper we describe BREASTCAN and NEWCHEM, two expert systems for the characterization of optimal adjuvant cancer therapies. The purpose of BREASTCAN is to support physicians in the postoperative breast cancer therapy, on the basis of currently used therapy protocols. It was developed in Prolog and positively validated, referring to the chemotherapies used by oncologists for some patients in the National Cancer Institute in Milan. NEWCHEM is a system oriented to the development of new cancer therapies, based on pharmaco-cell kinetic modeling and the newest molecular knowledge about neoplastic process. The system is being built and at first it will be validated by experiments on mice. Our aim with NEWCHEM is to extend our knowledge base and our rules to incorporate also all the modt advanced knowledge at the molecular and cellular level, both theoretical and experimental, to make readily accessible to the health-community a system was the present state of the art allows.     

A Virtual Reality Experiment on Flashing Lights at Emergency Exit Portals for Road Tunnel Evacuation

A virtual reality (VR) experiment with 96 participants was carried out to provide recommendations on the design of flashing lights at emergency exit portals for road tunnel emergency evacuation. The experiment was carried out in a Cave Automatic Virtual Environment laboratory. A set of variables was investigated, namely (1) colour of flashing lights, (2) flashing rate, (3) type of light source, (4) number and layout of the lights on the portal. Participants were immersed in a VR road tunnel emergency evacuation scenario and they were then asked to rank different portal designs using a questionnaire based on the Theory of Affordances. Results show that green or white flashing lights perform better than blue lights. A flashing rate of 1 and 4 Hz performed better than a flashing rate of 0.25 Hz. A light emitting diode light source performed better than single and double strobe lights. The three layouts of the lights under consideration performed similarly.     

Approximate closed‐form solution for the dynamical analysis of short bearings with couple stress fluid

The film forces in journal bearings may cause self‐exciting oscillations under particular operating conditions; if the amplitude of these oil‐whirl oscillations becomes too large, it may involve unsafe machinery dynamics. Thus, there is a need to understand the dynamic characteristics of the journal bearings evaluating the performances of the couple stress lubricants used to minimise the friction losses in steady operating conditions. The purpose of this paper was to illustrate a method to formulate with closed‐form solutions the non‐steady fluid film forces, and the stiffness and damping coefficients for ‘short’ liquid‐lubricated couple stress journal bearings, assuming the micro‐continuum Stokes' model. It is shown that the model allows the advantage of minimising the computational time required for the non‐linear dynamic analysis of couple stress journal bearings without any significant loss of accuracy, while the analytical form of the solution involves a better readability of the parameter effects on the system unsteady behaviour. Copyright © 2007 John Wiley & Sons, Ltd.