The effects of age on onset and recovery from atracurium, rocuronium and vecuronium blockade

Elderly patients may show an age-related decline in physiologic functions, which may be responsible for the prolonged duration of some neuromuscular blocking agents. Previous studies have yielded conflicting results as to the effects of these drugs in the elderly. METHODS: After obtaining informed consent and approval of the Ethics Committee, we compared onset and recovery times of single IV doses of atracurium, rocuronium, and vecuronium given to 108 patients divided into three groups according to age (18-50, 51-64, > or = 65 years). Following oxazepam premedication and fentanyl and thiopentone induction, patients were randomly allocated to receive atracurium, rocuronium or vecuronium (0.5, 0.6, or 0.1 mg/kg, respectively) in < or = 0.8 vol.% enflurane (end-tidal)-nitrous oxide anaesthesia. Muscular relaxation was assessed by electromyographic (EMG) recording of the adductor pollicis muscle after supramaximal single-twitch stimulation of the ulnar nerve every 10 s. Onset time and recovery to 25%, 75% and 90% of twitch control values (DUR25, 75, 90) were recorded. Creatinine clearance predicted from serum creatinine (Ccr) was correlated with recovery from neuromuscular block. RESULTS: Onset time was not different among groups or relaxants. The results showed a prolonged duration of action for atracurium (DUR75, DUR90), rocuronium (DUR25, DUR75), and vecuronium (DUR25) in the elderly. A number of patients did not reach DUR75 or DUR90. There was a significant relationship between age and failure to return to control values during recovery from neuromuscular block, especially after atracurium and rocuronium. Ccr showed a negative correlation with age for all relaxants, but a negative significant correlation between Ccr and recovery was found only for rocuronium. CONCLUSIONS: This study suggests that onset time for atracurium, rocuronium and vecuronium is not age-dependent. Recovery was prolonged in the elderly for all three relaxants. This effect appears to be secondary to changes in body composition and function accompanying the aging process. Neither atracurium nor vecuronium depends significantly on the kidney for elimination, but the negative correlation between Ccr and rocuronium suggests an appreciable role for the kidney in the elimination of this relaxant. The long recovery times observed in this study could also be related to enflurane anaesthesia. We suggest that failure of EMG responses to return to baseline values during recovery from neuromuscular block may be related to age, especially for atracurium and rocuronium.     

Support vector machines for surrogate modeling of electronic circuits

In electronic circuit design, preliminary analyses of the circuit performances are generally carried out using time-consuming simulations. These analyses should be performed as fast as possible because of the strict temporal constraints on the industrial sector time to market. On the other hand, there is the need of precision and reliability of the analyses. For these reasons, there is more and more interest toward surrogate models able to approximate the behavior of a device with a high precision making use of a limited set of samples. Using suitable surrogate models instead of simulations, it is possible to perform a reliable analysis in less time. In this work, we are going to analyze how the surrogate models given by the support vector machine (SVM) perform when they are used to approximate the behavior of industrial circuits that will be employed in consumer electronics. The SVM is also compared to the surrogate models given by the response surface methodology using a commercial software currently adopted for this kind of applications.     

What-You-Prescribe-Is-What-You-Get orthotropic hyperelasticity

We present a model for incompressible finite strain orthotropic hyperelasticity using logarithmic strains. The model does not have a prescribed shape. Instead, the energy function shape and the material data of the model are obtained solving the equilibrium equations of the different experiments. As a result the model almost exactly replicates the given experimental data for all six tests needed to completely define our nonlinear orthotropic material. We derive the constitutive tensor and demonstrate the efficiency of the finite element implementation for complex loading situations.     

Natural Majorization of the Quantum Fourier Transformation in Phase-Estimation Algorithms

We prove that majorization relations hold step by step in the Quantum Fourier Transformation (QFT) for phase-estimation algorithms. Our result relies on the fact that states which are mixed by Hadamard operators at any stage of the computation only differ by a phase. This property is a consequence of the structure of the initial state and of the QFT, based on controlled-phase operators and a single action of a Hadamard gate per qubit. The detail of our proof shows that Hadamard gates sort the probability distribution associated to the quantum state, whereas controlled-phase operators carry all the entanglement but are immaterial to majorization. We also prove that majorization in phase-estimation algorithms follows in a most natural way from unitary evolution, unlike its counterpart in Grover's algorithm. PACS: 03.67.-a, 03.67.Lx     

Active and reactive power control of a VSC-HVdc

Voltage source converter-based HVdc (VSC-HVdc) systems have the ability to rapidly control the transmitted active power, and also to independently exchange reactive power with transmissions systems. Due to these characteristics, VSC-HVdcs with a suitable control scheme can offer an alternative means to enhance transient stability, to improve power oscillations damping, and to provide voltage support. In this paper, a VSC-HVdc is represented by a simple model, referred to as the injection model. Based on this model, an energy function is developed for a multi-machine power system including VSC-HVdcs. Furthermore, based on Lyapunov theory (control Lyapunov function) and small signal analysis (modal analysis), various control strategies for transient stability and damping of low-frequency power oscillations are derived.     

Life Review Therapy Using Autobiographical Retrieval Practice for Older Adults With Depressive Symptomatology.

The aim of this study was to examine the efficacy of life review based on autobiographical retrieval practice for treating depressed older adults. Forty-three adults aged 65-93 with clinically significant depressive symptomatology and no dementia were randomly assigned to treatment or to no treatment. The results indicated significant differences between experimental and control groups after 4 weeks of autobiographical retrieval practice. At posttest, those in the treatment condition showed fewer depressive symptoms, less hopelessness, improved life satisfaction, and retrieval of more specific events. The findings suggest that practice in autobiographical memory for specific events may be among the components of life review that account for its effectiveness and could be a useful tool in psychotherapy with older adults. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Birefringence: calculation of refracted ray paths in biaxial crystals

The phenomenon of birefringence may be observed when light arrives at an anisotropic crystal surface and refracts through it, causing the incident light ray to split into two rays; these become polarized in mutually orthogonal directions, and two images are formed. The principal goal of this paper is the study of the directional issues involved in the behavior of light when refracting through a homogeneous, non-participating medium, including both isotropic and anisotropic media (uniaxial and, for the first time, biaxial). The paper focuses on formulating and solving the non-linear algebraic system that is obtained when the refraction process is simulated using the geometric model of Huygens. The main contribution focuses on the case of biaxial media. In the case of uniaxial media, we rely on symbolic calculus techniques to formulate and solve the problem.     

Streptococcus pneumoniae isolated from a paediatric population: changes in 10 years

Susceptibility to penicillin, cefotaxime, erythromycin and chloramphenicol, as well as serotypes of 100 Streptococcus pneumoniae strains isolated between 1984 and 1985, were compared to those of the same number of strains isolated between 1994 and 1995. The strains were obtained in Hospital Sant Joan de Déu, Barcelona, and were thought to be the cause of a variety of infectious diseases in paediatric patients attending this centre. Minimal inhibitory concentrations (MICs) of penicillin were higher in strains of the second period (51% of resistant strains during the first period vs 61% during the second one), as were those of cefotaxime (12% vs 18%) and erythromycin (6% vs 36%), while chloramphenicol MICs showed a light decrease (65% vs 46%). Serotypes 6, 19 and 23 were the most prevalent. Five new serotypes (4, 10, 18, 22 and 31) were detected in 10 penicillin-susceptible strains during the second period. Because of the increase in resistance to antibiotics commonly used in the treatment of systemic and localized infections, therapeutic alternatives must be studied and suggested in order to offer oral and percutaneous treatment for our children's infections caused by pneumococci.     

Structural changes in marinated fillets of gilthead sea bream (Sparus aurata L.) during vacuum storage at refrigerated temperature

Fillets of Sparus aurata were marinated in a mixture of salt (5.5%) and citric acid (48.9 g/kg) for 1 h, then vacuum packed and refrigerated for 1, 5, 16, and 21 d. Structural and ultrastructural parameters were evaluated in 6 specimens per time period. At day 1, the preservative solution appeared among the muscle fibers, thus increasing the interfibrillar spaces; cytoplasmic organelles were swollen and the sarcolemma-endomysium appeared very altered and electron-dense. At 5 to 10 d, the marinade solution had penetrated into the muscle fibers. The subsarcolemmal and intermyofibrillar spaces were dilated and granular lines of electron-dense material appeared among the fibers. From 16 d, broad interfibrillar spaces were occupied by granular material derived from denatured sarcolemma-endomysium and denatured myofibrils. Sarcomeres were already altered from initial stages, mainly at the I-band level. The Z-line also appeared disrupted. Such alterations were more severe from 10 d on, such that most of the sarcomeres showed disintegration of myofilaments.