A Dynamic P53-MDM2 Model with Time Delay

Specific activator and repressor transcription factors which bind to specific regulator DNA sequences, play an important role in gene activity control. Interactions between genes coding such transcription factors should explain the different stable or sometimes oscillatory gene activities characteristic for different tissues. Starting with the model P53-MDM2 described into [6] and the process described into [5] we developed a new model of this interaction. Choosing the delay as a bifurcation parameter we study the direction and stability of the bifurcating periodic solutions. Some numerical examples are finally given for justifying the theoretical results.Comment: 16 pages, 12 figure

Digital ulcers predict a worse disease course in patients with systemic sclerosis

Objective: Systemic sclerosis (SSc) is a systemic autoimmune disease with high morbidity and significant mortality. There is a great need of predictors that would allow risk stratification of patients with SSc and ultimately initiation of treatment early enough to ensure optimal clinical results. In this study, we evaluated whether a history of digital ulcers (HDU) at presentation may be a predictor of vascular outcomes and of overall clinical worsening and death in patients with SSc. Methods: Patients from the EULAR Scleroderma Trials and Research (EUSTAR) database, satisfying at inclusion the 1980 American College of Rheumatology classification criteria for SSc, who had a follow-up of at least 3 years since baseline or who have died, were included in the analysis. HDU at presentation as a predictor of disease worsening or death was evaluated by Cox proportional hazards regression analysis. Results :3196 patients matched the inclusion criteria (male sex 13.2%, 33.4% diffuse subset). At presentation, 1092/3196 patients had an HDU (34.1%). In multivariable analysis adjusting for age, gender and all parameters considered potentially significant, HDU was predictive for the presence of active digital ulcers (DUs) at prospective visits (HR (95% CI)): 2.41(1.91 to 3.03), p<0.001, for an elevated systolic pulmonary arterial pressure on heart ultrasound (US-PAPs):1.36 (1.03 to 1.80), p=0.032, for any cardiovascular event (new DUs, elevated US-PAPs or LV failure):3.56 (2.26 to 5.62), p<0.001, and for death (1.53 (1.16 to 2.02), p=0.003). Conclusions :In patients with SSc, HDU at presentation predicts the occurrence of DUs at follow-up and is associated with cardiovascular worsening and decreased survival

Virtual Reality and Anxiety Disorders Treatment: Evolution and Future Perspectives

Virtual reality (VR) is a technology that allows the simulation of different real-life situations on a tridimensional computer-generated environment where the user can interact with the environment as if he/she were the real world. VR has potential as an exposure technique for treating anxiety disorders because VR and real objects have similar characteristics, which creates the illusion that the user is immersed and engaged with objects in the real world. Regarding the efficacy of using virtual reality exposure-based therapy (VR-EBT), for more than two decades, there has been sufficient empirical evidence regarding VR-EBT for treating anxiety disorders. Finally, this chapter ends with some directions and perspectives for future VR-EBT developments and treatments protocols

Hopf Bifurcation Analysis of Pathogen-Immune Interaction Dynamics With Delay Kernel

The aim of this paper is to study the steady states of the mathematical models with delay kernels which describe pathogen-immune dynamics of infectious diseases. In the study of mathematical models of infectious diseases it is important to predict whether the infection disappears or the pathogens persist. The delay kernel is described by the memory function that reflects the influence of the past density of pathogen in the blood and it is given by a nonnegative bounded and normated function k defined on [ 0, ∞ ). By using the coefficient of the kernel k, as a bifurcationparameter, the models are found to undergo a sequence of Hopf bifurcation. The direction and the stability criteria of bifurcation periodic solutions are obtained by applying the normal form theory and the center manifold theorems. Some numerical simulation examples for justifying the theoretical results are also given

A Dynamic Economic Model with Discrete Time and Consumer Sentiment

The paper describes a dynamical economic model with discrete time and consumer sentiment in the deterministic and stochastic cases. We seek to demonstrate that consumer sentiment may create fluctuations in the economical activities. The model possesses a flip bifurcation and a Neimark-Sacker bifurcation, after which the stable state is replaced by a (quasi) periodic motion. We associate the difference stochastic equation to the model by randomizing the control parameter d and by adding one stochastic control. Numerical simulations are made for the deterministic and stochastic models, for different values of the control parameter d

Cyber-therapy ::the use of artificial intelligence in psychological practice

Cyber Therapy is a research project based on the relationship between Computer Science and Psychology. We are working on post-traumatic stress disorder (PTSD) due to severe traffic accidents using a virtual reality driving simulator and ECG, EDA and breathing sensors. With the help of virtual reality (VR) our goal is to build one software that can process the user’s biofeedback signals - heart rate, body temperature, state of tension, etc. - in real time, to make the phobic stimulus autonomous. To this purpose, we developed a platform capable of adapting the phobic stimulus based on the user’s biofeedback signals. We believe that this human-computer integrated system could be useful to patients as it would allow them to face fear autonomously, and to the psychotherapist, as it would allow a real time - physiologically based - knowledge of fear symptoms severity able to promote a timely and more appropriate program of intervention