Transport Barkhausen-like noise in uniaxially pressed Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) ceramic samples

We report on the detection of the transport Barkhausen-like noise (TBN) in polycrystalline samples of Bi(1.65)Pb(0.35)Sr(2)Ca(2) Cu(3)O(10+delta) (Bi-2223) which were subjected to different uniaxial compacting pressures. The transport Barkhausen-like noise was measured when the sample was subjected to an ac triangular-shape magnetic field (f similar to 1 Hz) with maximum amplitude B(max) approximate to 5.5 mT, in order to avoid the flux penetration within the superconducting grains. Analysis of the TBN signal, measured for several values of excitation current density, indicated that the applied magnetic field in which the noise signal first appears, B(a)(t(i)), is closely related to the magnetic-flux pinning capability of the material. The combined results are consistent with the existence of three different superconducting levels within the samples: (i) the superconducting grains; (ii) the superconducting clusters; and (iii) the weak-links. We finally argue that TBN measurements constitute a powerful tool for probing features of the intergranular transport properties in polycrystalline samples of high-T(c) superconductors. (C) 2010 Elsevier B.V. All rights reserved.

Experimental and theoretical study of transport properties in uniaxially pressed (Bi, Pb)(2)Sr(2)Ca(2)Cu(3)O(10+delta) ceramic samples

Experimental and theoretical studies on the magnetic field dependence of the electrical resistance R(B(a)) and the transport noise (TN) in polycrystalline high-T(c) superconductors subjected to different uniaxial compacting pressures were conducted. X-ray diffraction rocking curves were performed in different surfaces of the samples in order to investigated the degree of texture The results indicated an improvement of the degree of texture with increasing the uniaxial compacting pressure In theoretical simulations of the data, the polycrystalline superconductors were described as a series-parallel array of Josephson devices The intergranular magnetic field is described within the framework of the intragranular flux-trapping model and the distribution of the grain-boundary angles is assumed to follow the Rayleigh statistical function The proposed model describes well the experimental magnetoresistance R(B(a)) data We have found that the behavior of the R(B(a)) curves changes appreciably when different uniaxially compacting pressures are applied to the sample and such a changes are reproduced by the model when different grain-boundary angles distributions are used In addition, changes in the R(B(a)) dependence have their counterparts in the experimental transport noise signals (C) 2009 Elsevier B.V. All rights reserved

Effect of changing data collection parameters on statistical motor unit number estimates

The effect of number of samples and selection of data for analysis on the calculation of surface motor unit potential (SMUP) size in the statistical method of motor unit number estimates (MUNE) was determined in 10 normal subjects and 10 with amyotrophic lateral sclerosis (ALS). We recorded 500 sequential compound muscle action potentials (CMAPs) at three different stable stimulus intensities (10–50% of maximal CMAP). Estimated mean SMUP sizes were calculated using Poisson statistical assumptions from the variance of 500 sequential CMAP obtained at each stimulus intensity. The results with the 500 data points were compared with smaller subsets from the same data set. The results using a range of 50–80% of the 500 data points were compared with the full 500. The effect of restricting analysis to data between 5–20% of the CMAP and to standard deviation limits was also assessed. No differences in mean SMUP size were found with stimulus intensity or use of different ranges of data. Consistency was improved with a greater sample number. Data within 5% of CMAP size gave both increased consistency and reduced mean SMUP size in many subjects, but excluded valid responses present at that stimulus intensity. These changes were more prominent in ALS patients in whom the presence of isolated SMUP responses was a striking difference from normal subjects. Noise, spurious data, and large SMUP limited the Poisson assumptions. When these factors are considered, consistent statistical MUNE can be calculated from a continuous sequence of data points. A 2 to 2.5 SD or 10% window are reasonable methods of limiting data for analysis. Muscle Nerve 27: 320–331, 2003

Detection of cytomegalovirus in urine of HIV-infected patients by DNA-DNA hybridization comparison with virus isolation, immunofluorescence and immunoperoxidase

Immunofluorescence and immunoperoxidase test directed against early viral antigens, and DNA-DNA hybridization were compared with viral isolation for their abilities to detect Cytomegalovirus (CVM) in the urine of 89 HIV infected patients. From the 100 urine samples collected, 70 were found positive by at least one method. Considering viral isolation as the "gold standard" technique, immunofluorescence and immunoperoxidase had a sensitivity of 92.3% and88% respectively, with a specificity in both cases of 95%. DNA-DNA hybridization showed a sensitivity of 90% but with lower (60%) specificity. All of the three assays were effective in detecting CVM from urine and the technical advantage of each is discussed.

Dengue 2 virus enhancement in asthmatic and non asthmatic individual

During the 1981 dengue hemorrhagic fever/dengue shock syndrome (DHF/DSS) Cuban epidemic, bronchial asthma (BA) was frequently found as a personal or family antecedent in dengue hemorragic fever patients. Considering that antibody dependent enhancement (ADE) plays an important role in the etiopathogenic mechanism of DHF/DSS, we decide to study the Dengue 2 virus (D2V) capability of replication in peripheral blood leukocytes (PBL) from asthmatic patients and healthy persons. In 90% of asthmatic patients and 53.8% of control group it was obtained PBL with a significant D2V enhancing activity (X² p < 0.01). Power enhancement was higher in asthmatic group. This is the first in vitro study relating BA and the dengue 2 virus immuno enhancement. The results obtained support the role of BA as a risk factor for DHF/DSS as already described on epidemiological data.

Temperature Dependence of the Intergranular Critical Current Density in Uniaxially Pressed Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) Samples

We have studied the normal and superconducting transport properties of Bi(1.65)Pb(0.35)Sr(2)Ca(2)Cu(3)O(10+delta) (Bi-2223) ceramic samples. Four samples, from the same batch, were prepared by the solid-state reaction method and pressed uniaxially at different compacting pressures, ranging from 90 to 250 MPa before the last heat treatment. From the temperature dependence of the electrical resistivity, combined with current conduction models for cuprates, we were able to separate contributions arising from both the grain misalignment and microstructural defects. The behavior of the critical current density as a function of temperature at zero applied magnetic field, J (c) (T), was fitted to the relationship J (c) (T)ae(1-T/T (c) ) (n) , with na parts per thousand 2 in all samples. We have also investigated the behavior of the product J (c) rho (sr) , where rho (sr) is the specific resistance of the grain-boundary. The results were interpreted by considering the relation between these parameters and the grain-boundary angle, theta, with increasing the uniaxial compacting pressure. We have found that the above type of mechanical deformation improves the alignment of the grains. Consequently the samples exhibit an enhance in the intergranular properties, resulting in a decrease of the specific resistance of the grain-boundary and an increase in the critical current density.

Intergranular properties of uniaxially pressed YBa(2)Cu(3)O(7-delta) ceramic samples

We performed measurements of electrical resistivity as a function of temperature, rho(T), in polycrystalline samples of YBa(2)Cu(3)O(7-delta) (Y-123) subjected to different uniaxial compacting pressures. We observed by using X-ray diffractometry that samples have a very similar composition. Most of the identified peaks are related to the superconducting Y-123 phase. Also, from the X-ray diffraction patterns performed, in powder and pellet samples, we estimated the Lotgering factor along the (00l) direction, F((00l)). The results indicate that F((00l)) increases from 0.13 to 0.16. From electrical resistivity measurements as a function of temperature, we were able to separate contributions arising from both the grain misalignment and microstructural defects. We found appreciable degradation in the normal-state transport properties of samples with an increase in uniaxial compacting pressure. It seems that this type of behavior is associated with an increase in the influence of microstructural defects at the intergranular level. The experimental results are analyzed in the framework of a current conduction model of granular samples.

Territorialidade e plano diretor em São José do Rio Preto

Pós-graduação em Geografia - IGCE

Consolidation of Bi-2223 superconducting powders by spark plasma sintering

The spark plasma sintering (SPS) technique, by using a compacting pressure of 50 MPa, was used to consolidate pre-reacted powders of Bi1.65Pb0.35Sr2Ca2Cu3O10+delta (Bi-2223). The influence of the consolidation temperature, T-D, on the structural and electrical properties has been investigated and compared with those of a reference sample synthesized by the traditional solid-state reaction method and subjected to the same compacting pressure. From the X-ray diffraction patterns, performed in both powder and pellet samples, we have found that the dominant phase is the Bi-2223 in all samples but traces of the Bi2Sr2CaCu2O8+x (Bi-2212) were identified. Their relative density were similar to 85% of the theoretical density and the temperature dependence of the electrical resistivity, rho(T), indicated that increasing T-D results in samples with low oxygen content because the SPS is performed in vacuum. Features of the rho(T) data, as the occurrence of normal-state semiconductor-like behavior of rho(T) and the double resistive superconducting transition, are consistent with samples comprised of grains with shell-core morphology in which the shell is oxygen deficient. The SPS samples also exhibited superconducting critical current density at 77 K, J(c)(77K), between 2 and 10A/cm(2), values much smaller than similar to 22A/cm(2) measured in the reference sample. Reoxygenation of the SPS samples, post-annealed in air at different temperatures and times, was found to improve their microstructural and transport properties. Besides the suppression of the Bragg peaks belonging to the Bi-2212 phase, the superconducting properties of the post-annealed samples and particularly J(c)(77K) were comparable or better than those corresponding to the reference sample. Post-annealed samples at 750 degrees C for 5min exhibited J(c)(77K) similar to 130A/cm(2) even when uniaxially pressed at only 50 MPa. (C) 2012 American Institute of Physics. [http://dx.doi.org/10.1063/1.4768257]

Flux-Line-Lattice Melting and Upper Critical Field of Bi1.65Pb0.35Sr2Ca2Cu3O10+delta Ceramic Samples

We have conducted magnetoresistance measurements rho(T,H) in applied magnetic fields up to 18 T in Bi1.65Pb0.35Sr2Ca2Cu3O10+delta ceramic samples which were subjected to different uniaxial compacting pressures. The anisotropic upper critical fields H (c2)(T) were extracted from the rho(T,H) data, yielding and the out-of-plane superconducting coherence length xi (c) (0)similar to 3 . We have also estimated and xi (ab) (0) similar to 90 . In addition to this, a flux-line-lattice (FLL) melting temperature T (m) has been identified as a second peak in the derivative of the magnetoresistance d rho/dT data close to the superconducting transition temperature. An H (m) vs. T phase diagram was constructed and the FLL boundary lines were found to obey a temperature dependence H (m) ae(T (c) /T-1) (alpha) , where alpha similar to 2 for the sample subjected to the higher compacting pressure. A reasonable value of the Lindemann parameter c (L) similar to 0.29 has been found for all samples studied.

A large animal model of spinal muscular atrophy and correction of phenotype.

OBJECTIVES Spinal muscular atrophy (SMA) is caused by reduced levels of survival motor neuron (SMN) protein, which results in motoneuron loss. Therapeutic strategies to increase SMN levels including drug compounds, antisense oligonucleotides, and scAAV9 gene therapy have proved effective in mice. We wished to determine whether reduction of SMN in postnatal motoneurons resulted in SMA in a large animal model, whether SMA could be corrected after development of muscle weakness, and the response of clinically relevant biomarkers. METHODS Using intrathecal delivery of scAAV9 expressing an shRNA targeting pig SMN1, SMN was knocked down in motoneurons postnatally to SMA levels. This resulted in an SMA phenotype representing the first large animal model of SMA. Restoration of SMN was performed at different time points with scAAV9 expressing human SMN (scAAV9-SMN), and electrophysiology measurements and pathology were performed. RESULTS Knockdown of SMN in postnatal motoneurons results in overt proximal weakness, fibrillations on electromyography indicating active denervation, and reduced compound muscle action potential (CMAP) and motor unit number estimation (MUNE), as in human SMA. Neuropathology showed loss of motoneurons and motor axons. Presymptomatic delivery of scAAV9-SMN prevented SMA symptoms, indicating that all changes are SMN dependent. Delivery of scAAV9-SMN after symptom onset had a marked impact on phenotype, electrophysiological measures, and pathology. INTERPRETATION High SMN levels are critical in postnatal motoneurons, and reduction of SMN results in an SMA phenotype that is SMN dependent. Importantly, clinically relevant biomarkers including CMAP and MUNE are responsive to SMN restoration, and abrogation of phenotype can be achieved even after symptom onset.

Problèmes actuels de l'économique /

"Numéro spécial de la Revue de métaphysique et de morale (avril-juin 1921)."

Motor unit number estimation - A Bayesian approach

All muscle contractions are dependent on the functioning of motor units. In diseases such as amyotrophic lateral sclerosis (ALS), progressive loss of motor units leads to gradual paralysis. A major difficulty in the search for a treatment for these diseases has been the lack of a reliable measure of disease progression. One possible measure would be an estimate of the number of surviving motor units. Despite over 30 years of motor unit number estimation (MUNE), all proposed methods have been met with practical and theoretical objections. Our aim is to develop a method of MUNE that overcomes these objections. We record the compound muscle action potential (CMAP) from a selected muscle in response to a graded electrical stimulation applied to the nerve. As the stimulus increases, the threshold of each motor unit is exceeded, and the size of the CMAP increases until a maximum response is obtained. However, the threshold potential required to excite an axon is not a precise value but fluctuates over a small range leading to probabilistic activation of motor units in response to a given stimulus. When the threshold ranges of motor units overlap, there may be alternation where the number of motor units that fire in response to the stimulus is variable. This means that increments in the value of the CMAP correspond to the firing of different combinations of motor units. At a fixed stimulus, variability in the CMAP, measured as variance, can be used to conduct MUNE using the "statistical" or the "Poisson" method. However, this method relies on the assumptions that the numbers of motor units that are firing probabilistically have the Poisson distribution and that all single motor unit action potentials (MUAP) have a fixed and identical size. These assumptions are not necessarily correct. We propose to develop a Bayesian statistical methodology to analyze electrophysiological data to provide an estimate of motor unit numbers. Our method of MUNE incorporates the variability of the threshold, the variability between and within single MUAPs, and baseline variability. Our model not only gives the most probable number of motor units but also provides information about both the population of units and individual units. We use Markov chain Monte Carlo to obtain information about the characteristics of individual motor units and about the population of motor units and the Bayesian information criterion for MUNE. We test our method of MUNE on three subjects. Our method provides a reproducible estimate for a patient with stable but severe ALS. In a serial study, we demonstrate a decline in the number of motor unit numbers with a patient with rapidly advancing disease. Finally, with our last patient, we show that our method has the capacity to estimate a larger number of motor units.

Análise imunoistoquímica após terapia fotodinâmica com cloro-alumínio ftalocianina em tecidos gengivais de humanos

Although photodynamic therapy have been used as a useful tool over the past 30 years in oncology, few clinical trials have been conducted in dentistry. Photodynamic therapy (PDT) uses non - toxic photosensitizers and selective which are administered in target cells followed by local application of visible light, producing reactive oxygen species capable of causing cell death by apoptosis or necrosis, injured the local vasculature, and exert important effects on the im mune system. New generations of photosensitizing agents, such as nanoparticulate phthalocyanines, has shown excellent results in antitumor and antibacterial activity . In this context, the present work constitutes the first clinical protocol of local appli cation of nanoemulsion chloro - aluminum phthalocyanine (AlClFc) followed by irradiation in human gingiva, and analyzed descriptively and comparatively , by means of immunohistochemistry , the expression of RANK , RANKL , OPG and VEGF in a split - mouth model . Eight healthy volunteers with clinical indication for extraction were included in the study . Seven days before the extraction, was injected in the gingiva of participants, 5 μ M of nanoemulsion AlClFc followed by irra diation with diode laser (660nm , 7 J/cm2 ), the contralateral side was used as control. Tissue specimens were removed seven days after the TFD is performed. Tissues sample were divided into two groups (test and con trol groups) for histological and immunohistochemical analysis. Patients were monitored at days, 0, 7, 14 and 30 to assess adverse effects of the therapy. Vascular alterations were seen in gingival samples that received PDT. Areas of edema and vascular con gestion, and intense vascularization were viewed . Additionally, dystrophic calcification in subepithelial region were observed in the test group. The results showed a similar pattern of immunostaining scores of RANK, RANKL and VEGF between the test and co ntrol groups, with no statistically significant difference (p = 0.317, p = 0.777, p = 0 .814, respectively). RANK and RANKL exhibited weak or absent immunostaining in most specimens analyzed. There was n o immunostaining for OPG. VEGF showed moderate to stro ng immunostaining in specimens from the test group. In addition, the clinical study showed that therapy was well tolerated by all patients. Adverse effects were short - time and completely reversible. Taken together, the results presented in this study showe d that PDT mediated by nanoemulsion containing AlClPc is safe for clinical application in gingival tissue and suggests that a strong immunostaining for VEGF after therapy .