1000 resultados para Especialidade da via
Resumo:
In this paper, the minimum-order stable recursive filter design problem is proposed and investigated. This problem is playing an important role in pipeline implementation sin signal processing. Here, the existence of a high-order stable recursive filter is proved theoretically, in which the upper bound for the highest order of stable filters is given. Then the minimum-order stable linear predictor is obtained via solving an optimization problem. In this paper, the popular genetic algorithm approach is adopted since it is a heuristic probabilistic optimization technique and has been widely used in engineering designs. Finally, an illustrative example is sued to show the effectiveness of the proposed algorithm.
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This paper presents cost-effectiveness analyses (CEAs) of plasma collection via two alternative methods: whole blood collection (WBC) and erythroplasmapheresis collection (EPC). The objective of the study is to provide an answer to the question 'What is the least-cost method of plasma production'. This question is answered, both from the viewpoint of the blood collection agency (using financial CEA) and from that of 'society' as a whole (using economic CEA). We employ detailed financial data and economic survey data for collections made by a blood collection agency and to WBC and EPC donors in Brisbane, Australia. The results indicate that, despite the superior yield provided by EPC, WBC is actually more cost-effective. This result is robust to thorough sensitivity analysis and arises regardless of whether an economic or financial perspective is taken. We conclude that, ceteris paribus, the cost of recruiting new plasma donors would need to be quite substantial for marginal investments in EPC to be considered cost-effective. Crown Copyright (C) 2002 Published by Elsevier Science Ltd. All rights reserved.
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Superhyperfine interactions in inhomogeneously broadened paramagnetic centers are observed using a single high-turn-angle microwave pulse. The free induction signal that follows the hole-burning pulse exhibits oscillations that are distinct from the oscillatory free induction decay observable in some inhomogeneously broadened systems. It contains frequencies characteristic of the superhyperfine splittings, together with a zero frequency component. Experimental examples of the effect in both orientationally disordered (powdered) and structurally disordered (glassy) systems are presented and compared with the conceptually similar Fourier transform electron paramagnetic resonance detected nuclear magnetic resonance experiment, together with numerical simulations. (C) 2003 American Institute of Physics.
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The recently discovered cyclotides kalata B1 and kalata B2 are miniproteins containing a head-to-tail cyclized backbone and a cystine knot motif, in which disulfide bonds and the connecting backbone segments form a ring that is penetrated by the third disulfide bond. This arrangement renders the cyclotides extremely stable against thermal and enzymatic decay, making them a possible template onto which functionalities can be grafted.We have compared the hydrodynamic properties of two prototypic cyclotides, kalata B1 and kalata B2, using analytical ultracentrifugation techniques. Direct evidence for oligomerization of kalata B2 was shown by sedimentation velocity experiments in which a method for determining size distribution of polydisperse molecules in solution was employed. The shape of the oligomers appears to be spherical. Both sedimentation velocity and equilibrium experiments indicate that in phosphate buffer kalata B1 exists mainly as a monomer, even at millimolar concentrations. In contrast, at 1.6 mM, kalata B2 exists as an equilibrium mixture of monomer (30%), tetramer (42%), octamer (25%), and possibly a small proportion of higher oligomers. The results from the sedimentation equilibrium experiments show that this self-association is concentration dependent and reversible. We link our findings to the three-dimensional structures of both cyclotides, and propose two putative interaction interfaces on opposite sides of the kalata B2 molecule, one involving a hydrophobic interaction with the Phe(6), and the second involving a charge-charge interaction with the Asp(25) residue. An understanding of the factors affecting solution aggregation is of vital importance for future pharmaceutical application of these molecules.
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KM+ is a mannose-binding lectin from Artocarpus integrifolia that induces interleukin (IL)-12 production by macrophages and protective T helper I immune response against Leishmania major infection. in this study, we performed experiments to evaluate the therapeutic activity of jackfruit KM+ (jfKM(+)) and its recombinant counterpart (rKM(+)) in experimental paracoccidioidomycosis. To this end, jfKM(+) or rKM(+) was administered to BALB/c mice 10 days after infection with Paracoccidiodes brasiliensis. Thirty days postinfection, lungs from the KM+-treated mice contained significantly fewer colony-forming units and little to no organized granulomas compared to the controls. In addition, lung homogenates from the KM+-treated mice presented higher levels of nitric oxide, IL-12, interferon-gamma, and tumor necrosis factor-a, whereas higher levels of IL-4 and IL-10 were detected in the control group. With mice deficient in IL-12, Toll-like receptor (TLR) 2, TLR4, or TLR adaptor molecule MyD88, we demonstrated that KM+ led to protection against P. brasiliensis infection through IL-12 production, which was dependent on TLR2. These results demonstrated a beneficial effect of KM+ on the severity of P. brasiliensis infection and may expand its potential use as a novel immunotherapeutic molecule.
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Reactions of the model acylium ion (CH3)(2)N-C+=O with acyclic, exocyclic, and Spiro acetals of the general formula (RO)-O-1-(CRR4)-R-3-OR2-upole mass spectrometry. Characteristic intrinsic reactivities were observed for each of these classes of acetals. The two most Characteristic intrinsic reactivities were observed for each of these classes of acetals. The two most common reactions observed were hydride and alkoxy anion [(RO-)-O-1 and (RO-)-O-2] abstraction. Other specific reactions were also observed: (a) a secondary polar [4(+) + 2] cycloaddition for acetals bearing alpha,beta-unsaturated R-3 or R-4 substituents and (b) OH- abstraction for exocyclic and spiro acetals. These structurally diagnostic reactions, in conjunction with others observed previously for cyclic acetals, are shown to reveal the class of the acetal molecule and its ring type and substituents and to permit their recognition and distinction from other classes of isomeric molecules.
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A new solution route for the obtainment of highly pure luminescent rare-earth orthophosphates in hydrothermal conditions was developed. By starting from soluble precursors (lanthanide tripolyphosphato complexes. i.e. with P(3)O(10)(5) as a complexing agent and as in orthophosphate source) and by applying surfactants in a water/toluene medium, the precipitations are confined to reverse micelle structures, thus yielding nanosized and homogeneous orthophosphates The method was employed to obtain lanthanide-activated lanthanum phosphates, which can be applied as red (LaPO(4):Eu(3+)), green (LaPO(4):Ce(3+), Tb(3+)) and blue (LaPO(4):Tm(3+)) phosphors The produced materials were analyzed by powder X-ray diffractometry, scanning electron microscopy, infrared spectroscopy and luminescence spectroscopy (emission, excitation, lifetimes and chromaticity coordinates) (C) 2009 Elsevier B V All rights reserved
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We have shown previously that nitric oxide (NO) controls platelet endothelial cell adhesion molecule (PECAM-1) expression on both neutrophils and endothelial cells under physiological conditions. Here, the molecular mechanism by which NO regulates lipopolysaccharide (LPS)-induced endothelial PECAM-1 expression and the role of interleukin (IL)-10 on this control was investigated. For this purpose, N-(G)-nitro-L-arginine methyl ester (L-NAME; 20 mg/kg/day for 14 days dissolved in drinking water) was used to inhibit both constitutive (cNOS) and inducible nitric oxide (iNOS) synthase activities in LPS-stimulated Wistar rats (5 mg/kg, intraperitoneally). This treatment resulted in reduced levels of serum NO. Under this condition, circulating levels of IL-10 was enhanced, secreted mainly by circulating lymphocytes, dependent on transcriptional activation, and endothelial PECAM-1 expression was reduced independently on reduced gene synthesis. The connection between NO, IL-10 and PECAM-1 expression was examined by incubating LPS-stimulated (1 mu g/ml) cultured endothelial cells obtained from naive rats with supernatant of LPS-stimulated lymphocytes, which were obtained from blood of control or L-NAME-treated rats. Supernatant of LPS-stimulated lymphocytes obtained from L-NAME-treated rats, which contained higher levels of IL-10, reduced LPS-induced PECAM-1 expression by endothelial cells, and this reduction was reversed by adding the anti-IL-10 monoclonal antibody. Therefore, an association between NO, IL-10 and PECAM-1 was found and may represent a novel mechanism by which NO controls endothelial cell functions.
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1. Intracellular recordings were made from neurones in the rat otic ganglion in vitro in order to investigate their morphological, physiological and synaptic properties. We took advantage of the simple structure of these cells to test for a possible role of calcium influx via nicotinic acetylcholine receptors during synaptic transmission. 2. Cells filled with biocytin comprised a homogeneous population with ovoid somata and sparse dendritic trees. Neurones had resting membrane potentials of -53 +/- 0.7 mV (n = 69), input resistances of 112 + 7 M Omega, and membrane time constants of 14 +/- 0.9 ms (n = 60). Upon depolarization, all cells fired overshooting action potentials which mere followed by an apamin-sensitive after-hyperpolarization (AHP). In response to a prolonged current injection, all neurones fired tonically. 3. The repolarization phase of action potentials had a calcium component which was mediated by N-type calcium channels. Application of omega-conotoxin abolished both the repolarizing hump and the after-hgrperpolarization suggesting that calcium influx via N-type channels activates SK-type calcium-activated potassium channels which underlie the AHP. 4. The majority (70%) of neurones received innervation from a single preganglionic fibre which generated a suprathreshold excitatory postsynaptic potential mediated by nicotinic acetylcholine receptors. The other 30% of neurones also had one or more subthreshold nicotinic inputs. 5. Calcium influx via synaptic nicotinic receptors contributed to the AHP current, indicating that this calcium has access to the calcium-activated potassium channels and therefore plays a role in regulating cell excitability.
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Izenman and Sommer (1988) used a non-parametric Kernel density estimation technique to fit a seven-component model to the paper thickness of the 1872 Hidalgo stamp issue of Mexico. They observed an apparent conflict when fitting a normal mixture model with three components with unequal variances. This conflict is examined further by investigating the most appropriate number of components when fitting a normal mixture of components with equal variances.
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We propose a simple modification of the experimental scheme employed by Brune rt ni. [Phys. Rev. Lett. 79, 4887 (1996)] for the generation and detection of a Schrodinger cat state, in which the decoherence of the cat state can be significantly slowed down using an appropriate feedback.
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Although acquisition of anti-pertussis antibodies by the newborn via placental transfer has been demonstrated, a subsequent recrudescence of pertussis infection is often observed, particularly in infants. The present study investigated the passive transfer of anti-pertussis IgG and IgA antibodies to term newborns and their ability to neutralize bacterial pathogenicity in an in vivo experimental model using mice intracerebrally challenged with viable Bordetella pertussis. Forty paired samples of maternal/umbilical cord sera and colostrum were obtained. Anti-pertussis antibodies were analysed by immunoenzymatic assay and by Immunoblotting. Antibody neutralizing ability was assessed through intracerebral B. pertussis challenges in mice. Anti-pertussis IgG titres were equivalent in both maternal and newborn sera (medians = 1:225 and 1:265), with a transfer rate of 118%. The colostrum samples had variable specific IgA titres (median = 1:74). The immunoblotting assays demonstrated identical recognition profiles of paired maternal and newborn serum pools but different bacterial recognition intensities by colostrum pools. In the animal model, significant differences were always observed when the serum and colostrum samples and pools were compared with the positive control (P < 0.05). Unlike samples with lower anti-pertussis titres, samples with high titres showed protective capacities above 50%. Pertussis-absorbed serum and colostrum pools protected 30% of mice and purified IgG antibodies protected 65%. Both pooled and single-sample protective abilities were correlated with antibody titres (P < 0.01). Our data demonstrated the effectiveness of anti-pertussis antibodies in bacterial pathogenesis neutralization, emphasizing the importance of placental transfer and breast-feeding in protecting infants against respiratory infections caused by Bordetella pertussis.
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Olm MA, Kogler JE Jr, Macchione M, Shoemark A, Saldiva PH, Rodrigues JC. Primary ciliary dyskinesia: evaluation using cilia beat frequency assessment via spectral analysis of digital microscopy images. J Appl Physiol 111: 295-302, 2011. First published May 5, 2011; doi:10.1152/japplphysiol.00629.2010.-Ciliary beat frequency (CBF) measurements provide valuable information for diagnosing of primary ciliary dyskinesia (PCD). We developed a system for measuring CBF, used it in association with electron microscopy to diagnose PCD, and then analyzed characteristics of PCD patients. 1 The CBF measurement system was based on power spectra measured through digital imaging. Twenty-four patients suspected of having PCD (age 1-19 yr) were selected from a group of 75 children and adolescents with pneumopathies of unknown causes. Ten healthy, nonsmoking volunteers (age >= 17 yr) served as a control group. Nasal brush samples were collected, and CBF and electron microscopy were performed. PCD was diagnosed in 12 patients: 5 had radial spoke defects, 3 showed absent central microtubule pairs with transposition, 2 had outer dynein arm defects, 1 had a shortened outer dynein arm, and 1 had a normal ultrastructure. Previous studies have reported that the most common cilia defects are in the dynein arm. As expected, the mean CBF was higher in the control group (P < 0.001) and patients with normal ultrastructure (P < 0.002), than in those diagnosed with cilia ultrastructural defects (i.e., PCD patients). An obstructive ventilatory pattern was observed in 70% of the PCD patients who underwent pulmonary function tests. All PCD patients presented bronchial wall thickening on chest computed tomography scans. The protocol and diagnostic techniques employed allowed us to diagnose PCD in 16% of patients in this study.