This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient cond...This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.展开更多
Nonextensive statistical mechanics as in Tsallis formalism was used in this study, along with the dynamical Hamiltonian rod-like DNA model and the maximum entropy criteria for Tsallis’ entropy, so as to obtain length...Nonextensive statistical mechanics as in Tsallis formalism was used in this study, along with the dynamical Hamiltonian rod-like DNA model and the maximum entropy criteria for Tsallis’ entropy, so as to obtain length distribution of plasmid fragments, after irradiation with very high doses, assuming that the system reaches metaequilibrium. By intensively working out the Grand Canonical Ensemble (used to take into account the variation of the number of base pairs) a simplified expression for Fragment Size Distribution Function (FSDF) was obtained. This expression is dependent on two parameters only, the Tsallis q value and the minimal length of the fragments. Results obtained from fittings to available experimental data were adequate and the characteristic behavior of the shortest fragments was clearly documented and reproduced by the model, a circumstance never verified from theoretical distributions. The results point to the existence of an entropy which characterizes fragmentation processes and depending only on the q entropic index.展开更多
We consider a Lagrangian to describe gravity using a nonlinear term depending on the Gauss-Bonnet topological invariant. We examine the conditions for a bouncing and the existence of an ulterior accelerated phase of t...We consider a Lagrangian to describe gravity using a nonlinear term depending on the Gauss-Bonnet topological invariant. We examine the conditions for a bouncing and the existence of an ulterior accelerated phase of the universe. The original concept of Einstein's first paper on cosmology was to modify the equations that control the gravitational metric. Based on this, several authors have proposed different formalisms to modify general relativity. Herein, a function of the topological invariant is used in a homogeneous and isotropic cosmological model. First, a case with the topological invariant as a constant is thoroughly examined, yielding specific constraints on the evolution of the Hubble parameter. Subsequently, we study a function of the topological invariant squared. In an empty space-time scenario, the term that modifies Einstein's equations functions as an effective geometrical density, and we map regions in the phase space in which the effective pressure is positive or negative. This results in non-trivial integral solutions such as cyclic stages of acceleration and deceleration of the scale factor in the model, among other behaviors. We add cosmic dust to the system, and for certain classes of solutions, we observe that the minimum positive value of the Hubble parameter is limited by the cosmic dust matter density. If this matter density reaches zero, the minimum value of the Hubble parameter also reaches zero.展开更多
Maxwell electrodynamics in the fixed Minkowski space-time background can be described in an equivalent way in a curved Riemannian geometry that depends on the electromagnetic field and that we call the electromagnetic...Maxwell electrodynamics in the fixed Minkowski space-time background can be described in an equivalent way in a curved Riemannian geometry that depends on the electromagnetic field and that we call the electromagnetic metric（e-metric for short）. After showing such geometric equivalence we investigate the possibility that new processes dependent on the e-metric are allowed. In particular, for very high values of the field, a direct coupling of uncharged particles to the electromagnetic field may appear.展开更多
文摘This paper shows the blood flow control （FwC） performance to adjust rotational speed of an ICBP （implantable centrifugal blood pump） in order to provide an adequate flow to left ventricle in different patient conditions. ICBP is a totally implantable LVAD （left ventricular assist device） with ceramic bearings developed for long term circulatory assistance. FwC uses PI （proportional-integral） control to adjust rotational speed in order to provide blood flow. FwC does not use sensor for feedback, as there is an estimation system to provide blood flow measurement. Control strategy has being studied in a HCS （hybrid cardiovascular simulator） as a tool that allows the physical connection of ICBP during evaluation. In addition, HCS allows changes of some cardiovascular parameters in order to simulate specific heart disease： ejection fraction （10-25%） and heart rate （50-110 bpm）. FwC was able to adjust blood flow with steady error less than 2%. Results demonstrated that FwC is adequate to LVAD control irL different left ventricle failure conditions.
文摘Nonextensive statistical mechanics as in Tsallis formalism was used in this study, along with the dynamical Hamiltonian rod-like DNA model and the maximum entropy criteria for Tsallis’ entropy, so as to obtain length distribution of plasmid fragments, after irradiation with very high doses, assuming that the system reaches metaequilibrium. By intensively working out the Grand Canonical Ensemble (used to take into account the variation of the number of base pairs) a simplified expression for Fragment Size Distribution Function (FSDF) was obtained. This expression is dependent on two parameters only, the Tsallis q value and the minimal length of the fragments. Results obtained from fittings to available experimental data were adequate and the characteristic behavior of the shortest fragments was clearly documented and reproduced by the model, a circumstance never verified from theoretical distributions. The results point to the existence of an entropy which characterizes fragmentation processes and depending only on the q entropic index.
文摘We consider a Lagrangian to describe gravity using a nonlinear term depending on the Gauss-Bonnet topological invariant. We examine the conditions for a bouncing and the existence of an ulterior accelerated phase of the universe. The original concept of Einstein's first paper on cosmology was to modify the equations that control the gravitational metric. Based on this, several authors have proposed different formalisms to modify general relativity. Herein, a function of the topological invariant is used in a homogeneous and isotropic cosmological model. First, a case with the topological invariant as a constant is thoroughly examined, yielding specific constraints on the evolution of the Hubble parameter. Subsequently, we study a function of the topological invariant squared. In an empty space-time scenario, the term that modifies Einstein's equations functions as an effective geometrical density, and we map regions in the phase space in which the effective pressure is positive or negative. This results in non-trivial integral solutions such as cyclic stages of acceleration and deceleration of the scale factor in the model, among other behaviors. We add cosmic dust to the system, and for certain classes of solutions, we observe that the minimum positive value of the Hubble parameter is limited by the cosmic dust matter density. If this matter density reaches zero, the minimum value of the Hubble parameter also reaches zero.
基金Supported by Conselho Nacional de Desenvolvimento Científico e Tecnológico(CNPq)FAPERJ(Fundao do Amparo Pesquisa do Rio de Janeiro)+1 种基金FINEP(Financiadora de Estudos e Projetos)Coordenao do Aperfeioamento do Pessoal do Ensino Superior(CAPES)
文摘Maxwell electrodynamics in the fixed Minkowski space-time background can be described in an equivalent way in a curved Riemannian geometry that depends on the electromagnetic field and that we call the electromagnetic metric（e-metric for short）. After showing such geometric equivalence we investigate the possibility that new processes dependent on the e-metric are allowed. In particular, for very high values of the field, a direct coupling of uncharged particles to the electromagnetic field may appear.
