Generic substitution policy,an incentive approach

Generic substitution policy has been adopted in several countries in order to control health expenditures. Using a model based on incentives, this work aims to analyze the response of doctors and pharmaceutical companies to the implementation of this policy. It is shown that after the implementation of GSP, the effort of doctor’s convincing the patient to take generics increase or decrease depending on his level of concern for patient well-being; pharmaceutical companies decrease the amount of detailing and the market share of generics tends to increase.     

Global stability analysis of parametrically excited cylindrical shells through the evolution of basin boundaries

In the present study, the large-amplitude vibrations and stability of a perfect circular cylindrical shell subjected to axial harmonic excitation in the neighborhood of the lowest natural frequencies are investigated. Donnell's shallow shell theory is used and the shell spatial discretization is obtained by the Ritz method. An efficient low-dimensional model presented in previous publications is used to discretize the continuous system. The main purpose of this work is to discuss the use of basins of attraction as a measure of the reliability and safety of the structure. First, the nonlinear behavior of the conservative system is discussed and the basin structure and volume is understood from the topologic structure of the total energy and its evolution as a function of the system parameters. Then, the behavior of the forced oscillations of the harmonically excited shell is analyzed. First the stability boundaries in force control space are obtained and the bifurcation events connected with these boundaries are identified. Based on the bifurcation diagrams, the probability of parametric instability and escape are analyzed through the evolution and erosion of basin boundaries within a prescribed control volume defined by the manifolds. Usually, basin boundaries become fractal. This together with the presence of catastrophic subcritical bifurcations makes the shell very sensitive to initial conditions, uncertainties in system parameters, and initial imperfections. Results show that the analysis of the evolution of safe basins and the derivation of appropriate measures of their robustness is an essential step in the derivation of safe design procedures for multiwell systems.     

Probing the transition from hydrophilic to hydrophobic solvation with atomic scale resolution

Picosecond and femtosecond X-ray absorption spectroscopy is used to probe the changes of the solvent shell structure upon electron abstraction of aqueous iodide using an ultrashort laser pulse. The transient L(1,3) edge EXAFS at 50 ps time delay points to the formation of an expanded water cavity around the iodine atom, in good agreement with classical and quantum mechanical/molecular mechanics (QM/MM) molecular dynamics (MD) simulations. These also show that while the hydrogen atoms pointed toward iodide, they predominantly point toward the bulk solvent in the case of iodine, suggesting a hydrophobic behavior. This is further confirmed by quantum chemical (QC) calculations of I(-)/I(0)(H(2)O)(n=1-4) clusters. The L(1) edge sub-picosecond spectra point to the existence of a transient species that is not present at 50 ps. The QC calculations and the QM/MM MD simulations identify this transient species as an I(0)(OH(2)) complex inside the cavity. The simulations show that upon electron abstraction most of the water molecules move away from iodine, while one comes closer to form the complex that lives for 3-4 ps. This time is governed by the reorganization of the main solvation shell, basically the time it takes for the water molecules to reform an H-bond network. Only then is the interaction with the solvation shell strong enough to pull the water molecule of the complex toward the bulk solvent. Overall, much of the behavior at early times is determined by the reorientational dynamics of water molecules and the formation of a complete network of hydrogen bonded molecules in the first solvation shell.     

Thermal analysis characterization of PAAm-<Emphasis Type="Italic">co</Emphasis>-MC hydrogels

This paper reports the thermal characterization of polyacrylamide-co-methylcellulose hydrogels and the constituent monomers (acrylamide and methylcellulose). Polymeric materials can be used to produce hydrogels, which can be natural, synthetic, or a mixture. The hydrogels described here were obtained by free radical polymerization, in the presence of N,N′-methylene-bis-acrylamide as a cross-linker agent. Four acrylamide concentrations were used for the synthesis of hydrogels: 3.6, 7.2, 14.7, and 21.7% (w/v). The materials so obtained were analyzed by TG, DTG, DSC, and FT-IR. The TG curves of acrylamide and methylcellulose showed three mass loss events. In DSC curves, the acrylamide exhibited one melting peak at 84.5 °C, and methylcellulose indicated one exothermic event. Nevertheless, acrylamide was considered more stable than methylcellulose. The TG curves of the hydrogels exhibited three mass loss events, and on the DSC curves, three endothermic events were observed. It was verified that the different acrylamide proportions influenced the thermic behavior of hydrogels, and that the authors considered the 7.2% hydrogel a promising drug carrier system. The absorption bands were well defined, confirming the presence of the functional groups in the samples.     

Azaphenanthrene alkaloids with antitumoral activity from Anaxagorea dolichocarpa Sprague & Sandwith (Annonaceae)

Phytochemical investigation of Anaxagorea dolichocarpa Sprague & Sandwith led to isolation of three azaphenanthrene alkaloids: eupolauramine, sampangine and imbiline 1. Their chemical structures were established on the basis of spectroscopic data from IR, HR-ESI-MS, NMR (including 2D experiments) and comparison with the literature. Sampangine and imbiline 1 are being described in the Anaxagorea genus for the first time. Eupolauramine and sampangine show concentration-dependent antitumoral activity in leukemic cells K562 with IC(50) of 18.97 and 10.95 μg/mL, respectively.     

NeXSPheRIO results on elliptic flow at RHIC and connection with thermalization

Elliptic flow at RHIC is computed event by event with NeXSPheRIO. Reasonable agreement with experimental results on v ₂(η) is obtained. Various effects are studied as well: reconstruction of impact parameter direction, freeze-out temperature, equation of state (with or without crossover), emission mechanism.     

Optimal discrete Morse functions for 2-manifolds

Morse theory is a powerful tool in its applications to computational topology, computer graphics and geometric modeling. It was originally formulated for smooth manifolds. Recently, Robin Forman formulated a version of this theory for discrete structures such as cell complexes. It opens up several categories of interesting objects (particularly meshes) to applications of Morse theory. Once a Morse function has been defined on a manifold, then information about its topology can be deduced from its critical elements. The main objective of this paper is to introduce a linear algorithm to define optimal discrete Morse functions on discrete 2-manifolds, where optimality entails having the least number of critical elements. The algorithm presented is also extended to general finite cell complexes of dimension at most 2, with no guarantee of optimality.