Loewner integer-order approximation of MIMO fractional-order systems

A state–space integer–order approximation of commensurate–order systems is obtained using a data–driven interpolation approach based on Loewner matrices. Precisely, given the values of the original fractional–order transfer function at a number of generalised frequencies, a descriptor–form state–space model matching these frequency response values is constructed from a suitable Loewner matrix pencil, as already suggested for the reduction of high–dimensional integer–order systems. Even if the stability of the resulting integer–order system cannot be guaranteed, such an approach is particularly suitable for approximating (infinite–dimensional) fractional–order systems because: (i) the order of the approximation is bounded by half the number of interpolation points, (ii) the procedure is more robust and simple than alternative approximation methods, and (iii) the procedure is fairly flexible and often leads to satisfactory results, as shown by some examples discussed at the end of the article. Clearly, the approximation depends on the location, spacing and number of the generalised interpolation frequencies but there is no particular reason to choose the interpolation frequencies on the imaginary axis, which is a natural choice in integer–order model reduction, since this axis does not correspond to the stability boundary of the original fractional–order system

Efficiency of the fused magnesium potassium phosphate for soybean.

Abstract: The use of ground natural rocks (in natura) containing K was evaluated for the cultivation of rice (NEPTUNE et al., 1980), corn (Siqueira et al., 1985) and more recently in corn, soybeans and mil- let (Resende et al., 2006), whose agronomic results were not satisfactory. However, when the potassic rock is fused at high temperatures and calcare- ous is added, you get the product known as fused magnesium potassium phosphate (TK) with K availability increased. In a study to evaluate the fused magnesi- um potassium phosphate in corn, there was an in- crease in the production of dry matter and higher K accumulation accumulation in plants (FAQUIN et al., 1987) mass. High agronomic efficiency of this source was also observed for Marandu-grass with equivalent or su- perior results when compared to KCI. No study, however, was con- ducted to assess the efficacy of fused magnesium potassium phosphate in providing K for soybean, which is recognized for its strategic importance in the Brazilian agribusiness. In light of the above, this study aimed to assess the efficacy of the fused magnesium potas- sium phosphate as a source of potassium for soy- bean

Administração de azul de metileno no choque anafilático induzido por composto 48/80: estudo hemodinâmico em suínos

PURPOSE: To verify if the methylene blue (MB) administration prevents and/or reverses the compound 48/80 (C48/80)-induced anaphylactic shock in pigs. METHODS: Female Dalland pigs were anesthetized and had the hemodynamic parameters recorded during the necessary time to administer some drugs and observe their effect. The animals were randomly assigned to one of the five groups: 1) control; 2) MB: the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 3) C48/80: the animals received a bolus injection of C48/80 (4 mg/kg); 4) C48/80+MB: the animals received a bolus injection of C48/80 (4 mg/kg) and 10 minutes after the C48/80 administration the animals received a bolus injection of MB (2 mg/kg) followed by continuous infusion of MB (2.66 mg/Kg/h delivered by syringe infusion pump); 5) MB+C48/80: the animals received a bolus injection of MB (2 mg/kg) and 3 minutes later they received a bolus injection of C48/80 (4 mg/kg). RESULTS: The intravenous infusion of MB alone caused no changes in the mean arterial pressure (MAP) showing that the administered MB dose was safe in this experimental model. The C48/80 was effective in producing experimental anaphylactic shock since it was observed a decrease in both MAP and cardiac output (CO) after its administration. The MB did not prevent or reverse the C48/80-induced anaphylactic shock in this model. In fact, the MAP of the animals with anaphylactic shock treated with MB decreased even more than the MAP of the animals from the C48/80 group. On the other hand, the C48/80-induced epidermal alterations disappeared after the MB infusion. CONCLUSION: Despite our data, the clinical manifestations improvement brings some optimism and does not allow excluding the MB as a possible therapeutic option in the anaphylactic shock.OBJETIVO: Verificar se a administração de azul de metileno (AM) previne e/ou reverte o choque anafilático induzido por composto 48/80 (C48/80) em suínos. MÉTODOS: Porcos fêmeas Dalland foram anestesiados e tiveram os parâmetros hemodinâmicos registados durante o tempo necessário para administrar algumas drogas e observar seu efeito. Os animais foram aleatoriamente destribuídos em um dos cinco grupos: 1) controle, 2) AM: os animais receberam uma injeção em bolus de AM (2mg/kg), seguido de infusão contínua de AM (2,66mg/Kg /h por bomba de infusão de seringa); 3) C48/80: os animais receberam uma injeção em bolus de C48/80 (4mg/kg); 4) C48/80 + AM: os animais receberam uma injeção em bolus de C48/80 (4mg/kg) e 10 minutos após a administração de C48/80 os animais receberam uma injeção em bolus de AM (2mg/kg), seguido de infusão contínua de AM (2,66mg/kg/h por bomba de infusão de seringa); 5) AM+C48/80: os animais receberam uma injeção em bolus de AM (2mg/kg) e três minutos depois, receberam uma injeção em bolus de C48/80 (4mg/kg). RESULTADOS: A infusão intravenosa de AM não causou mudanças na pressão arterial média (PAM), mostrando que a dose de AM administrada foi segura neste modelo experimental. O C48/80 foi eficaz na indução do choque anafilático experimental, uma vez que foi observada redução na PAM e débito cardíaco (DC), após a sua administração. O AM não preveniu ou reverte o choque anafilático induzido por C48/80 neste modelo. Na verdade, a PAM dos animais com choque anafilático tratados com AM diminuiu mais do que o PAM dos animais do grupo C48/80. Por outro lado, as alterações epidérmicas induzidas pelo C48/80 desapareceu após a infusão do AM. CONCLUSÃO: Apesar dos resultados a melhora clínica das manifestações anafiláticas permite considerar a possibilidade do azul de metileno como opção terapêutica no tratamento do choque anafilático.(FAEPA) Faculdade de Medicina de Ribeirão Preto da Universidade de São Paulo (USP) - Fundação de Apoio ao Ensino, Pesquisa e Assistência do Hospital das Clínica

Optostimulation of striatonigral terminals in substantia nigra induces dyskinesia that increases after L‐DOPA in a mouse model of Parkinson's disease

Background and Purpose: L-DOPA-induced dyskinesia (LID) remains a major complication of L-DOPA therapy in Parkinson's disease. LID is believed to result from inhibition of substantia nigra reticulata (SNr) neurons by GABAergic striatal projection neurons that become supersensitive to dopamine receptor stimulation after severe nigrostriatal degeneration. Here, we asked if stimulation of direct medium spiny neuron (dMSN) GABAergic terminals at the SNr can produce a full dyskinetic state similar to that induced by L-DOPA. Experimental Approach: Adult C57BL6 mice were lesioned with 6-hydroxydopamine in the medial forebrain bundle. Channel rhodopsin was expressed in striatonigral terminals by ipsilateral striatal injection of adeno-associated viral particles under the CaMKII promoter. Optic fibres were implanted on the ipsilateral SNr. Optical stimulation was performed before and 24 hr after three daily doses of L-DOPA at subthreshold and suprathreshold dyskinetic doses. We also examined the combined effect of light stimulation and an acute L-DOPA challenge. Key Results: Optostimulation of striatonigral terminals inhibited SNr neurons and induced all dyskinesia subtypes (optostimulation-induced dyskinesia [OID]) in 6-hydroxydopamine animals, but not in sham-lesioned animals. Additionally, chronic L-DOPA administration sensitised dyskinetic responses to striatonigral terminal optostimulation, as OIDs were more severe 24 hr after L-DOPA administration. Furthermore, L-DOPA combined with light stimulation did not result in higher dyskinesia scores than OID alone, suggesting that optostimulation has a masking effect on LID. Conclusion and Implications: This work suggests that striatonigral inhibition of basal ganglia output (SNr) is a decisive mechanism mediating LID and identifies the SNr as a target for managing LID.Fil: Keifman, Ettel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; Argentina. Consejo Superior de Investigaciones Científicas; EspañaFil: Ruiz De Diego, Irene. Consejo Superior de Investigaciones Científicas; EspañaFil: Pafundo, Diego Esteban. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Paz, Rodrigo Manuel. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Solís, Oscar. Consejo Superior de Investigaciones Científicas; EspañaFil: Murer, Mario Gustavo. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Houssay. Instituto de Fisiología y Biofísica Bernardo Houssay. Universidad de Buenos Aires. Facultad de Medicina. Instituto de Fisiología y Biofísica Bernardo Houssay; ArgentinaFil: Moratalla, Rosario. Consejo Superior de Investigaciones Científicas; Españ

Some considerations on nonminimality, ill-conditioning, and instability of Pad\ue9 approximants

Critical conditions of model simplification are pointed out and investigated. In particular, the problem of setting up an rth order model for an nth order system (with r<n) using the Pad\ue9 technique is considered. The different situations of model uniqueness, non-existence, and non-minimality are classified according to the ranks of Hankel matrices formed from the original system Markov parameters (for example, the MacLaurin expansion coefficients of its transfer function). The case is then analysed where the reduced-order model parameters are given by an ill-conditioned set of equations so that small changes in the original system cause large variations of the model. Finally, the problem of reduced-order model instability is investigated and its relation to the ill-conditioned situation is pointed out