Técnica de bombeio e prova para medidas de absorção de estado excitado e de emissão estimulada, em materiais sólidos dopados com íons terras raras

Rare earth ion doped solid state materials are the most important active media of near-infrared and visible lasers and other photonic devices. In these ions, the occurrence of Excited State Absorptions (ESA), from long lived electronic levels, is commonplace. Since ESA can deeply affect the efficiencies of the rare earth emissions, evaluation of these transitions cross sections is of greatest importance in predicting the potential applications of a given material. In this paper a detailed description of the pump-probe technique for ESA measurements is presented, with a review of several examples of applications in Nd3+, Tm3+ and Er3+ doped materials.

The relationship between stem vessel parameters and the development of strata in the early stages of secondary forest succession in Amazonia

In order to compare the development of strata in the early stages of secondary forest succession with vessel parameters of the tree species, a forest inventory was carried out in 4-year (Q1: 48 m2), 11-year (Q2: 400 m2) and 20-year (Q3: 400 m2) forests and vessel parameters were investigated from stem cross sections of 18 species obtained in Q2. Thirty three species (21 families), 77 species (35 families), 39 species (20 families) were found in Ql, Q2, Q3, respectively. The percentage of dead individuals, dead stems and the percentage of individuals with multiple stems increased with time after clear cutting. Also, the total D2H of Q3 was 26.1 times that of Q1, and the development of strata started in Q2 and Q3. The image analysis of vessel size, area and number of vessels revealed that species which reach the forest canopy had a large D2H value, vessel diameter and area, while species which remain near the forest floor had smaller ones. Poecilanthe effusa (Huber) Ducke is an example of the latter case, with a large number of individuals and abundant sprouting of new stems from stumps, but with high mortality.

Ultrastructural aspects of spermatogonesis in Metamicrocotyla macracantha (Alexander, 1954) Koratha, 1955 (Monogenea; Microcotylidae)

Ultrastructural aspects of spermatogenesis, spermiogenesis and of the mature spermatozoon of a microcotylid monogenean Metamicrocotyla macracantha parasite from Mugil liza, are described. The irregularly-shaped spermatogonia divides by successive mitoses, forming the primary spermatocytes, identified by the presence of synaptonemal complexes in their nuclei. The spermatids formed by meiotic cell divisions of the secondary spermatocytes, differentiate into a mature spermatozoon. Cross sections of the head and the middle region of mature spermatozoa show the nucleus with strong condensed chromatin, the mitochondria with short cristae, peripheral microtubules and two axonemes with a 9+1 pattern, confirming the characteristics of this genus.

Prevalence and pathology of the nematode Heterakis gallinarum, the trematode Paratanaisia bragai, and the protozoan Histomonas meleagridis in the turkey, Meleagris gallopavo

The prevalence of infection and associated pathology induced by two helminth and one protozoan species infecting Brazilian turkeys are reported. The intestinal nematode Heterakis gallinarum appeared with a prevalence of 70% in the infected birds, without gross lesions when not associated to the protozoan Histomonas meleagridis. Histological findings in the ceca were represented by the presence of H. gallinarum worms, intense chronic diffuse inflammatory processes with mononuclear and polymorphonuclear (heterophils) leucocyte infiltrations. The prevalence of the protozoan H. meleagridis associated to H. gallinarum was of 2.5% and microscopic examination revealed a severe inflammatory process in the liver and cecum with the presence of small clear areas with round eosinophilic parasites. Gross lesions were absent in turkeys infected with the renal digenetic trematode Paratanaisia bragai; the parasite was prevalent in 20% of the cases and cross-sections of the kidneys showed a remarkable distension of the collecting ducts with several worms in the lumen. The walls of the ducts presented a discrete heterophilic infiltrate among mononuclear cells.

Cálculo ab initio de intensidades Raman dinâmicas utilizando a teoria da resposta linear

In this paper a methodology for the computation of Raman scattering cross-sections and depolarization ratios within the Placzek Polarizability Theory is described. The polarizability gradients are derived from the values of the dynamic polarizabilities computed at the excitation frequencies using ab initio Linear Response Theory. A sample application of the computational program, at the HF, MP2 and CCSD levels of theory, is presented for H2O and NH3. The results show that high correlated levels of theory are needed to achieve good agreement with experimental data.

O método das trajectórias clássicas: colisões coplanares do tipo A+BC

The general methodology of classical trajectories as applied to elementary chemical reactions of the A+BC type is presented. The goal is to elucidate students about the main theoretical features and potentialities in applying this versatile method to calculate the dynamical properties of reactive systems. Only the methodology for two-dimensional (2D) case is described, from which the general theory for 3D follows straightforwardly. The adopted point of view is, as much as possible, that of allowing a direct translation of the concepts into a working program. An application to the reaction O(¹D)+H2->O+OH with relevance in atmospheric chemistry is also presented. The FORTRAN codes used are available through the web page www.qqesc.qui.uc.pt.

Are alveolar bone changes a determinant factor for "cara inchada" in cattle?

In order to study possible alterations of the skeleton which might play a role in the pathogenesis of the periodontitis of "cara inchada" in young cattle, ribs from 20 affected calves, 2 to 10 months old, were examined. Electrolytically decalcified longitudinal sections of the costochondral junction and cross sections through the corpus costae, stained with Haematoxylin-Eosin, were studied. In five calves, longitudinal sections of the proximal humerus were examined as well. The status of mineralization was checked by microradiograms. Systemic alteration of the skeleton due to disturbances of mineral metabolism could not be shown in any of the animals. In seven 2 to 4 months old calves, no bone changes were found. The reduced osteogenesis in six 3 to 5 months old calves and the reduced osteogenesis and diminished chondral growth in seven 5 to 10 months old calves are therefore a consequence of the disease. The results show that the development of the alveolar bone was not defective, so this cannot be a determinant factor for the development of the periodontitis of "cara inchada" in cattle.

Regenerated rat skeletal muscle after periodic contusions

In the present study we evaluated the morphological aspect and changes in the area and incidence of muscle fiber types of long-term regenerated rat tibialis anterior (TA) muscle previously submitted to periodic contusions. Animals received eight consecutive traumas: one trauma per week, for eight weeks, and were evaluated one (N = 8) and four (N = 9) months after the last contusion. Serial cross-sections were evaluated by toluidine blue staining, acid phosphatase and myosin ATPase reactions. The weight of injured muscles was decreased compared to the contralateral intact one (one month: 0.77 ± 0.15 vs 0.91 ± 0.09 g, P = 0.03; four months: 0.79 ± 0.14 vs 1.02 ± 0.07 g, P = 0.0007, respectively) and showed abundant presence of split fibers and fibers with centralized nuclei, mainly in the deep portion. Damaged muscles presented a higher incidence of undifferentiated fibers when compared to the intact one (one month: 3.4 ± 2.1 vs 0.5 ± 0.3%, P = 0.006; four months: 2.3 ± 1.6 vs 0.3 ± 0.3%, P = 0.007, respectively). Injured TA evaluated one month later showed a decreased area of muscle fibers when compared to the intact one (P = 0.003). Thus, we conclude that: a) muscle fibers were damaged mainly in the deep portion, probably because they were compressed against the tibia; b) periodic contusions in the TA muscle did not change the percentage of type I and II muscle fibers; c) periodically injured TA muscles took four months to reach a muscle fiber area similar to that of the intact muscle.

Abnormalities of hippocampal signal intensity in patients with familial mesial temporal lobe epilepsy

Mesial temporal lobe epilepsy (MTLE) is associated with hippocampal atrophy and hippocampal signal abnormalities. In our series of familial MTLE (FMTLE), we found a high proportion of hippocampal abnormalities. To quantify signal abnormalities in patients with FMTLE we studied 152 individuals (46 of them asymptomatic) with FMTLE. We used NIH-Image® for volumetry and signal quantification in coronal T1 inversion recovery and T2 for all cross-sections of the hippocampus. Values diverging by 2 or more SD from the control mean were considered abnormal. T2 hippocampal signal abnormalities were found in 52% of all individuals: 54% of affected subjects and 48% of asymptomatic subjects. T1 hippocampal signal changes were found in 34% of all individuals: 42.5% of affected subjects and 15% of asymptomatic subjects. Analysis of the hippocampal head (first three slices) revealed T2 abnormalities in 73% of all individuals (74% of affected subjects and 72% of asymptomatic subjects) and T1 abnormalities in 59% (67% of affected subjects and 41% of asymptomatic subjects). Affected individuals had smaller volumes than controls (P < 0.0001). There was no difference in hippocampal volumes between asymptomatic subjects and controls, although 39% of asymptomatic patients had hippocampal atrophy. Patients with an abnormal hippocampal signal (133 individuals) had smaller ipsilateral volume, but no linear correlation could be determined. Hippocampal signal abnormalities in FMTLE were more frequently found in the hippocampal head in both affected and asymptomatic family members, including those with normal volumes. These results indicate that subtle abnormalities leading to an abnormal hippocampal signal in FMTLE are not necessarily related to seizures and may be determined by genetic factors.

Effect of salbutamol on innervated and denervated rat soleus muscle

The objective of the present investigation was to perform a 14-day time-course study of treatment with salbutamol, a ß2 adrenoceptor agonist, on rat soleus muscle in order to assess fiber type selectivity in the hypertrophic response and fiber type composition. Male Wistar rats were divided into four groups: control (N = 10), treated with salbutamol (N = 30), denervated (N = 30), and treated with salbutamol after denervation (N = 30). Salbutamol was injected intraperitoneally in the rats of the 2nd and 4th groups at a concentration of 0.3 mg/kg twice a day for 2 weeks. The muscles were denervated using the crush method with pean. The animals were sacrificed 3, 6, 9, 12, and 14 days after treatment. Frozen cross-sections of soleus muscle were stained for myosin ATPase, pH 9.4. Cross-sectional area and percent of muscle fibers were analyzed morphometrically by computerized image analysis. Treatment with salbutamol induced hypertrophy of all fiber types and a higher percentage of type II fibers (21%) in the healthy rat soleus muscle. Denervation caused marked atrophy of all fibers and conversion from type I to type II muscle fibers. Denervated muscles treated with salbutamol showed a significantly larger cross-sectional area of type I muscle fibers, 28.2% compared to the denervated untreated muscle. Moreover, the number of type I fibers was increased. These results indicate that administration of salbutamol is able to induce changes in cross-sectional area and fiber type distribution in the early phase of treatment. Since denervation-induced atrophy and conversion from type I to type II fibers were improved by salbutamol treatment we propose that salbutamol, like other ß2 adrenoceptor agonists, may have a therapeutic potential in improving the condition of skeletal muscle after denervation.

An immunohistochemical, clinical and electroneuromyographic correlative study of the neural markers in the neuritic form of leprosy

The nerve biopsies of 11 patients with pure neuritic leprosy were submitted to routine diagnostic procedures and immunoperoxidase staining with antibodies against axonal (neurofilament, nerve growth factor receptor (NGFr), and protein gene product (PGP) 9.5) and Schwann cell (myelin basic protein, S-100 protein, and NGFr) markers. Two pairs of non-adjacent histological cross-sections of the peripheral nerve were removed for quantification. All the fascicles of the nerve were examined with a 10X-ocular and 40X-objective lens. The immunohistochemistry results were compared to the results of semithin section analysis and clinical and electroneuromyographic data. Neurofilament staining was reduced in 100% of the neuritic biopsies. NGFr positivity was also reduced in 81.8%, PGP staining in 100% of the affected nerves, S100 positivity in 90.9%, and myelin basic protein immunoreactivity in 90.9%. Hypoesthesia was associated with decreased NGFr (81.8%) and PGP staining (90.9%). Reduced potential amplitudes (electroneuromyographic data) were found to be associated with reduced PGP 9.5 (63.6%) and nerve fiber neurofilament staining (45.4%) by immunohistochemistry and with loss of myelinated fibers (100%) by semithin section analysis. On the other hand, the small fibers (immunoreactive dots) seen amid inflammatory cells continued to be present even after 40% of the larger myelinated fibers had disappeared. The present study shows an in-depth view of the destructive effects of leprosy upon the expression of neural markers and the integrity of nerve fiber. The association of these structural changes with the clinical and electroneuromyographic manifestations of leprosy peripheral neuropathy was also discussed.

Stretch-induced nerve injury: a proposed technique for the study of nerve regeneration and evaluation of the influence of gabapentin on this model

The rat models currently employed for studies of nerve regeneration present distinct disadvantages. We propose a new technique of stretch-induced nerve injury, used here to evaluate the influence of gabapentin (GBP) on nerve regeneration. Male Wistar rats (300 g; n=36) underwent surgery and exposure of the median nerve in the right forelimbs, either with or without nerve injury. The technique was performed using distal and proximal clamps separated by a distance of 2 cm and a sliding distance of 3 mm. The nerve was compressed and stretched for 5 s until the bands of Fontana disappeared. The animals were evaluated in relation to functional, biochemical and histological parameters. Stretching of the median nerve led to complete loss of motor function up to 12 days after the lesion (P<0.001), compared to non-injured nerves, as assessed in the grasping test. Grasping force in the nerve-injured animals did not return to control values up to 30 days after surgery (P<0.05). Nerve injury also caused an increase in the time of sensory recovery, as well as in the electrical and mechanical stimulation tests. Treatment of the animals with GBP promoted an improvement in the morphometric analysis of median nerve cross-sections compared with the operated vehicle group, as observed in the area of myelinated fibers or connective tissue (P<0.001), in the density of myelinated fibers/mm2 (P<0.05) and in the degeneration fragments (P<0.01). Stretch-induced nerve injury seems to be a simple and relevant model for evaluating nerve regeneration.