Serum lactate as a prognostic factor in coronary artery bypass graft operation by on pump method

Background: Lactic acidosis in cardiac surgical patients is a manifestation of systemic inflammation and excess pro-inflammatory cytokine production. This investigation was designed to integrate basic concepts about lactate acidosis with a clinically used of serum lactate in patients under coronary artery bypass surgery (CABG) by on pump method. Methods: From August to September 2012, 15 patients scheduled for routine cardiac surgery entered to our sample and followed up two weeks. Lactate concentration in arterial blood sample was studied. Method of surgery duration of cardiopulmonary bypass, aorta cross clamp timing, hemodynamic parameters, inotrope dosage and patient outcome were documented. The data were collected and analyzed. Results: The mean age of the patients was 62±14 years. The patients with a poor outcome had significantly higher lactate levels in ABG samples (p0.05). The PH of ABG samples did not generally correlate with the ABG lactate concentration (r=0.116, p=0.68). Increased lactate concentration was reliably associated with patient hemodynamic parameters, inotrope dosage, duration of on pump time and aorta cross clamp time. Conclusion: This study demonstrates a correlation between serum lactate levels and patient prognosis after CABG surgery by on pump method

The occurrence of riddled basins and blowout bifurcations in a parametric nonlinear system

In this paper, a two parameters family $F_{\beta_1,\beta_2}$ of maps of the plane living two different subspaces invariant is studied. We observe that, our model exhibits two chaotic attractors $A_i$, $i=0,1$, lying in these invariant subspaces and identify the parameters at which $A_i$ has a locally riddled basin of attraction or becomes a chaotic saddle. Then, the occurrence of riddled basin in the global sense is investigated in an open region of $\beta_1\beta_2$-plane. We semi-conjugate our system to a random walk model and define a fractal boundary which separates the basins of attraction of the two chaotic attractors, then we describe riddled basin in detail. We show that the model undergos a sequence of bifurcations: "a blowout bifurcation", "a bifurcation to normal repulsion" and "a bifurcation by creating a new chaotic attractor with an intermingled basin". Numerical simulations are presented graphically to confirm the validity of our results.Comment: 26 pages, 15 figure

Development of fuzzy anti-roll bar controller for improving vehicle stability

The main objective of this paper is to develop active control mechanism based on fuzzy logic controller (FLC) for improving vehicle path following, roll and handling performances simultaneously. At the first stage, 3DOF vehicle model which includes yaw rate, lateral velocity (lateral dynamic) and roll angle (roll dynamic) are developed. The controller produces optimal moment to increase stability and roll margin of vehicle by receiving the steering angle as an input and vehicle variables as a feedback signal. The effectiveness of proposed controller and vehicle model are evaluated during fishhook and single lane-change maneuvers. Simulation results demonstrate that FLC by reducing roll angle, lateral velocity and acceleration, vehicle roll resistance and handling properties are improved. Finally the sensitivity and robustness analysis of developed controller for varying longitudinal speeds are investigated

Synthesis and Characterization of Acrylamide-Based Anionic Copolymer and Investigation of Solution Properties

The copolymer of acrylamide (AM) and 2-acrylamido-2-methyl-1-propane sulfonic acid (AMPS) was synthesized through radical solution polymerization by potassium persulfate as initiator. By changing the AMPS feed ratio from 10 to 70%, and keeping other reaction conditions constant, different copolymers were synthesized. The techniques of Fourier transform infrared (FTIR) and nuclear magnetic resonance (1H- 13C-NMR) spectroscopy were used for identification of functional groups and confirmation of copolymers’ structure. Intrinsic and apparent viscosity of samples were measured in aqueous sodium chloride solution under standard conditions. The anionic degree of copolymers was determined by back titration method and by 13C-NMR spectroscopy. Molecular weight of copolymers was determined by the Mark-Houwink relationship. The measured molecular weight of samples showed that we have acquired a high molecular weight product. The effect of different range of shear rates on solution viscosity was evaluated. The copolymer solutions showed non-Newtonian shear thinning behavior. The performance of copolymers with respect to shear resistance and molecular weight was evaluated from industry application standpoint