966 resultados para PASSIVE MARGIN
Resumo:
Abundance and composition of marine benthic communities have been relatively well studied in the SE Brazilian coast, but little is known on patterns controlling the distribution of their planktonic larval stages. A survey of larval abundance in the continental margin, using a Multi-Plankton Sampler, was conducted in a cross-shelf transect off Cabo Frio (23 degrees S and 42 degrees W) during a costal upwelling event. Hydrographic conditions were monitored through discrete CDT casts. Chlorophyll-a in the top 100 m of the water column was determined and changes in surface chlorophyll-a was estimated using SeaWiFS images. Based on the larval abundances and the meso-scale hydrodynamics scenario, our results suggest two different processes affecting larval distributions. High larval densities were found nearshore due to the upwelling event associated with high chlorophyll a and strong along shore current. On the continental slope, high larval abundance was associated with a clockwise rotating meander, which may have entrapped larvae from a region located further north (Cabo de Sao Tome, 22 degrees S and 41 degrees W). In mid-shelf areas, our data suggests that vertical migration may likely occur as a response to avoid offshore transport by upwelling plumes and/or cyclonic meanders. The hydrodynamic scenario observed in the study area has two distinct yet extremely important consequences: larval retention on food-rich upwelling areas and the broadening of the tropical domain to southernmost subtropical areas. (C) 2009 Elsevier B.V. All rights reserved.
Resumo:
Changes in the Brazilian continental margin`s oceanic productivity and circulation over the last 27,000 years were reconstructed based on sedimentological and microfaunal analyses. Our results suggest that oceanic paleoproductivity and the supply of terrigenous sediments to the Brazilian continental margin were higher during the Last Glacial Maximum (LGM) than during the Holocene. These changes may have been primarily influenced by significant sea level fluctuations that have occurred since the late Pleistocene. During the LGM, the lower sea level, higher productivity and lower sea-surface paleotemperatures may have been the result of the offshore displacement of the main flow of the Brazil Current. However, during the Holocene, the warm waters of the Brazil Current were displaced toward the coast. This displacement contributed to the increase in water temperature and prevented an increase in oceanic productivity. The decrease in terrigenous supply since the LGM could be related to the increase of the extension of the continental shelf and/or drier climatic conditions.
Resumo:
Sedimentological and benthic foraminifera analyses carried out on a core (length 4.15 in, collected at 22 degrees 56`31 `` S and 41 degrees 58`48 `` W, at a water depth of 43 in) sampled from the inner shelf of Cabo Frio, southeastern Brazilian continental margin, allowed identification of different hydrodynamic and productivity regimes related to sea-level fluctuations and/or climatic changes, during the last 9.4 ka cal BP. Prior to 7.0 ka cal BP, a less intense hydrodynamic and lower productivity regime occurred at lower sea levels and under drier climatic conditions. Between 7.0 and 5.0 ka cal BP, relatively stronger local oceanic circulation and relatively high productivity were observed, in a scenario of rising sea levels and more humid conditions. From 5.0 to 3.0 ka cal BP, bottom currents weakened and input of nutrients increased, with productivity levels similar to the previous phase at lower sea level and in a drier climate. From 3.0 ka cal BP up to the present, stronger hydrodynamic conditions and a higher productivity regime are linked to the establishment of the upwelling process in Cabo Frio. From 2.5 ka cal BP to the present, upwelling enhancement has been recognized, resulting from the combined action of NE winds and the intensification of the meandering pattern of the Brazil Current (BC). (C) 2008 Elsevier Ltd and INQUA. All rights reserved.
Resumo:
Introduction: HMG-CoA reductase inhibitors are the most frequently prescribed drugs for treatment of lipid imbalance, but they have side effects, such as myopathy. Our aim was to assess the effect of simvastatin on the inflammatory process induced by skeletal muscle injury. Methods: Rats were divided into experimental groups [control group, simvastatin (20 mg/kg) group, group treated with simvastatin (20 mg/kg) and subjected to injury, and group subjected to injury only]. Histological analysis and analyses of creatine kinase activity and C-reactive protein were performed. Results: Animals treated with simvastatin exhibited significantly greater morphological and structural skeletal muscle damage in comparison to the control group and injured animals without treatment. Conclusions: Although simvastatin has a small anti-inflammatory effect in the early stage after a muscle strain injury, the overall picture is negative, as simvastatin increases the extent of damage to muscle morphology. Further studies are needed. Muscle Nerve 46: 908-913, 2012
Resumo:
Carvalho, FLP, Carvalho, MCGA, Simao, R, Gomes, TM, Costa, PB, Neto, LB, Carvalho, RLP, and Dantas, EHM. Acute effects of a warm-up including active, passive, and dynamic stretching on vertical jump performance. J Strength Cond Res 26(9): 2447-2452, 2012-The purpose of this study was to examine the acute effects of 3 different stretching methods combined with a warm-up protocol on vertical jump performance. Sixteen young tennis players (14.5 +/- 2.8 years; 175 +/- 5.6 cm; 64.0 +/- 11.1 kg) were randomly assigned to 4 different experimental conditions on 4 successive days. Each session consisted of a general and specific warm-up, with 5 minutes of running followed by 10 jumps, accompanied by one of the subsequent conditions: (a) Control Condition (CC)-5 minutes of passive rest; (b) Passive Stretching Condition (PSC)-5 minutes of passive static stretching; (c) Active Stretching Condition (ASC)-5 minutes of active static stretching; and (d) Dynamic Stretching Condition (DC)-5 minutes of dynamic stretching. After each intervention, the subjects performed 3 squat jumps (SJs) and 3 countermovement jumps (CMJs), which were measured electronically. For the SJ, 1-way repeated measures analysis of variance (CC x PSC x ASC x DC) revealed significant decreases for ASC (28.7 +/- 4.7 cm; p = 0.01) and PSC (28.7 +/- 4.3 cm; p = 0.02) conditions when compared with CC (29.9 +/- 5.0 cm). For CMJs, there were no significant decreases (p > 0.05) when all stretching conditions were compared with the CC. Significant increases in SJ performance were observed when comparing the DC (29.6 +/- 4.9 cm; p = 0.02) with PSC (28.7 +/- 4.3 cm). Significant increases in CMJ performance were observed when comparing the conditions ASC (34.0 +/- 6.0 cm; p = 0.04) and DC (33.7 +/- 5.5 cm; p = 0.03) with PSC (32.6 +/- 5.5 cm). A dynamic stretching intervention appears to be more suitable for use as part of a warm-up in young athletes.
Resumo:
Colostrum intake in newborn goat kids is essential for the acquisition of immunoglobulins (Ig) and influencing development of gastrointestinal mucosa. The present study investigated small intestine structure in the postnatal goat kid fed lyophilized bovine colostrum, an alternative source of antibodies to small ruminants, or goat colostrum using scanning electron microscopy technique. At 0,7 and 14 h of life 15 male newborns received 5% of body weight of lyophilized bovine colostrum (LBC) and 14 goat colostrum (GC), both with 55 mg/mL of IgG. Samples of duodenum, medium jejunum and ileum were collected at 18, 36 and 96 h of life. Three animals were sampled at birth without colostrum intake (0 h). The enteric tissues were analyzed for villi density (villi/cm(2)) and morphological characteristics. The villi density did not differ between treatment, sampling time and intestinal segments (P>0.05). The morphological characteristics were not different between LBC and GC in all segments. Duodenal villi were fingerlike, thick and short, and with different heights. Duodenal folds could also be verified. Frequent anastomoses in all sampling times were observed in this segment. In the jejunum, fingerlike villi, thin and thick, of different heights were observed in all sampling times as well as leaf-shaped villi. Vacuoles with colostrum were observed in the jejunum of goats sampled at 18 h of life. In ileum, fingerlike villi were observed in all sampling times. At 0 and 96 h of life, thick and low villi were verified while at 18 and 36 h the villi showed different heights and widths. At all sampling times, regularly cell extrusion processes were observed with grouped cells at the apex of the ileum villi and with isolated cells along the villi. In the first 4 days of goat kids' life the small intestine structure was unaffected by different sources of colostrum, goat or lyophilized bovine, and by the replacement of fetal enterocytes, which are able to absorb macromolecules, by adult-type ones. (C) 2011 Elsevier B.V. All rights reserved.
Resumo:
Introduction: The ankle sprain is one of the most common injuries in athletes. Direct evaluation of the ligament laxity can be obtained through the objective measurement of extreme passive inversion and eversion movements, but there are few studies on the use of the evaluation of the passive resistive torque of the ankle to assess the capsule and ligaments resistance. Objective: The aim of this study was to compare the inversion and eversion passive torque in athletes with and without ankle sprains history. Method: 32 female basketball and volleyball athletes (16.06 +/- 0.8 years old; 67.63 +/- 8.17 kg; 177.8 +/- 6.47 cm) participated in this study. Their ankles were divided into two groups: control group (29), composed of symptom-free ankles, and ankle sprain group, composed of ankles which have suffered injury (29). The resistive torque at maximum passive ankle movement was measured by the isokinetic dynamometer and the muscular activity by electromyography system. The athletes performed 2 repetitions of inversion and eversion movement at 5, 10 and 20 degrees/s and the same protocol only at maximum inversion movement. Results: The resistive passive torque during the inversion and eversion was lower in the ankle sprain group. This group also showed lower torques at the maximum inversion movement. No differences were observed between inversion and eversion movement. Conclusions: Ankle sprain leads to lower passive torque, indicating reduction of the resistance of the lateral ankle ligaments and mechanical laxity.
Resumo:
Enzyme activity of protein and carbohydrate degradation in small intestinal mucosa was investigated in goat kids fed with lyophilized bovine and goat colostrum. At 0,7 and 14 h of life 15 male newborns received 5% of body weight of lyophilized bovine colostrum and 14 goat colostrum, both with 55 mg/mL of IgG. Duodenum, jejunum and ileum samples were collected at 18,36 and 96 h of life. Three animals were sampled at birth, without colostrum intake. Activity of aminopeptidase N and A, dipeptidil peptidase IV, lactase, maltase and sucrase was determined as one international unit per gram of tissue. Intracellular enzymatic activity of acid phosphatase was observed by histochemistry in tissue section. Only the activity of aminopeptidase A in the ileum was affected by treatment, with a greater value for LBC than for GC (P < 0.05). The aminopeptidase N activity was the highest at 36 h in the duodenum (P < 0.05) and lowest at 96 h in the jejunum (P < 0.05). Dipeptidil peptidase IV activity was highest at 36 h in the duodenum (P < 0.05), lowest at 96 h in the jejunum (P < 0.05) and higher at 36 h than at 96 h in the ileum (P < 0.05). Aminopeptidase A activity in the ileum was highest at 36 h (P < 0.05), followed by 18 and 96 h of life (P < 0.05). Lactase activity in the duodenum increased from 18 to 36 h and from 36 to 96 h in the jejunum (P < 0.05). Maltase activity increased only in the duodenum from 18 to 96 h (P < 0.05). Sucrase activity in the jejunum decreased from 18 to 36 h and from 36 to 96 h in the ileum (P < 0.05). At birth, activity of most enzymes was similar to that at later times (P < 0.05). Histochemistry analyses showed a higher frequency of lysosomes with acid phosphatase activity in the duodenum, especially at 36 h of life. In the jejunum, the presence of lysosomes with acid phosphatase activity was the highest at 96 h, followed by 36 and 18 h of life. In the ileum, all samples showed low presence of lysosomes with acid phosphatase activity. These results indicate that lyophilized bovine colostrum, as a heterologous source of antibodies or nutrients, is a possible alternative management tool for goats. The present work also suggests that in the first 4 days of life, enzyme activity in the intestinal epithelium of goats is still not fully stimulated, which is an important characteristic for these animals that depend on macromolecule absorption to acquire passive protection after birth. (C) 2012 Elsevier B.V. All rights reserved.
Resumo:
Background: The reduction of the pelvic floor muscles (PFM) strength is a major cause of stress urinary incontinence (SUI). Objective: To compare active and passive forces, and vaginal cavity aperture in continent and stress urinary incontinent women. Method: The study included a total of thirty-two women, sixteen continent women (group 1 - G1) and sixteen women with SUI (group 2 - G2). To evaluate PFM passive and active forces in anteroposterior (sagittal plane) and left-right directions (frontal plane) a stainless steel specular dynamometer was used. Results: The anteroposterior active strength for the continent women (mean +/- standard deviation) (0.3 +/- 0.2 N) was greater compared to the values found in the evaluation of incontinent women (0.1 +/- 0.1 N). The left-right active strength (G1=0.43 +/- 0.1 N; G2=0.40 +/- 0.1 N), the passive force (G1=1.1 +/- 0.2 N; G2=1.1 +/- 0.3 N) and the vaginal cavity aperture (G1=21 +/- 3 mm; G2=24 +/- 4 mm) did not differ between groups 1 and 2. Conclusion: The function evaluation of PFM showed that women with SUI had a lower anteroposterior active strength compared to continent women.
Resumo:
PURPOSE. We previously demonstrated that most eyes have regionally variable extensions of Bruch's membrane (BM) inside the clinically identified disc margin (DM) that are clinically and photographically invisible. We studied the impact of these findings on DM- and BM opening (BMO)-derived neuroretinal rim parameters. METHODS. Disc stereo-photography and spectral domain optical coherence tomography (SD-OCT, 24 radial B-scans centered on the optic nerve head) were performed on 30 glaucoma patients and 10 age-matched controls. Photographs were colocalized to SD-OCT data such that the DM and BMO could be visualized in each B-scan. Three parameters were computed: (1) DM-horizontal rim width (HRW), the distance between the DM and internal limiting membrane (ILM) along the DM reference plane; (2) BMO-HRW, the distance between BMO and ILM along the BMO reference plane; and (3) BMO-minimum rim width (MRW), the minimum distance between BMO and ILM. Rank-order correlations of sectors ranked by rim width and spatial concordance measured as angular distances between equivalently ranked sectors were derived. RESULTS. The average DM position was external to BMO in all quadrants, except inferotemporally. There were significant sectoral differences among all three rim parameters. DM- HRW and BMO-HRW sector ranks were better correlated (median rho = 0.84) than DM- HRW and BMO-MRW (median rho = 0.55), or BMO-HRW and BMO-MRW (median rho = 0.60) ranks. Sectors with the narrowest BMO-MRW were infrequently the same as those with the narrowest DM-HRW or BMO-HRW. CONCLUSIONS. BMO-MRW quantifies the neuroretinal rim from a true anatomical outer border and accounts for its variable trajectory at the point of measurement. (Invest Ophthalmol Vis Sci. 2012;53:1852-1860) DOI:10.1167/iovs.11-9309
Resumo:
Motor imagery, passive movement, and movement observation have been suggested to activate the sensorimotor system without overt movement. The present study investigated these three covert movement modes together with overt movement in a within-subject design to allow for a fine-grained comparison of their abilities in activating the sensorimotor system, i.e. premotor, primary motor, and somatosensory cortices. For this, 21 healthy volunteers underwent functional magnetic resonance imaging (fMRI). In addition we explored the abilities of the different covert movement modes in activating the sensorimotor system in a pilot study of 5 stroke patients suffering from chronic severe hemiparesis. Results demonstrated that while all covert movement modes activated sensorimotor areas, there were profound differences between modes and between healthy volunteers and patients. In healthy volunteers, the pattern of neural activation in overt execution was best resembled by passive movement, followed by motor imagery, and lastly by movement observation. In patients, attempted overt execution was best resembled by motor imagery, followed by passive movement and lastly by movement observation. Our results indicate that for severely hemiparetic stroke patients motor imagery may be the preferred way to activate the sensorimotor system without overt behavior. In addition, the clear differences between the covert movement modes point to the need for within-subject comparisons. (C) 2012 Elsevier Inc. All rights reserved.
Resumo:
Objective: To characterize optic nerve head (ONH) anatomy related to the clinical optic disc margin with spectral domain-optical coherence tomography (SD-OCT). Design: Cross-sectional study. Participants: Patients with open-angle glaucoma with focal, diffuse, and sclerotic optic disc damage, and age-matched normal controls. Methods: High-resolution radial SD-OCT B-scans centered on the ONH were analyzed at each clock hour. For each scan, the border tissue of Elschnig was classified for obliqueness (internally oblique, externally oblique, or nonoblique) and the presence of Bruch's membrane overhanging the border tissue. Optic disc stereophotographs were co-localized to SD-OCT data with customized software. The frequency with which the disc margin identified in stereophotographs coincided with (1) Bruch's membrane opening (BMO), defined as the innermost edge of Bruch's membrane; (2) Bruch's membrane/border tissue, defined as any aspect of either outside BMO or border tissue; or (3) border tissue, defined as any aspect of border tissue alone, in the B-scans was computed at each clock hour. Main Outcome Measures: The SD-OCT structures coinciding with the disc margin in stereophotographs. Results: There were 30 patients (10 with each type of disc damage) and 10 controls, with a median (range) age of 68.1 (42-86) years and 63.5 (42-77) years, respectively. Although 28 patients (93%) had 2 or more border tissue configurations, the most predominant one was internally oblique, primarily superiorly and nasally, frequently with Bruch's membrane overhang. Externally oblique border tissue was less frequent, observed mostly inferiorly and temporally. In controls, there was predominantly internally oblique configuration around the disc. Although the configurations were not statistically different between patients and controls, they were among the 3 glaucoma groups. At most locations, the SD-OCT structure most frequently identified as the disc margin was some aspect of Bruch's membrane and border tissue external to BMO. Bruch's membrane overhang was regionally present in the majority of patients with glaucoma and controls; however, in most cases it was not visible as the disc margin. Conclusions: The clinically perceived disc margin is most likely not the innermost edge of Bruch's membrane detected by SD-OCT. These findings have important implications for the automated detection of the disc margin and estimates of the neuroretinal rim. Financial Disclosure(s): Proprietary or commercial disclosure may be found after the references. Ophthalmology 2012;119:738-747 (C) 2012 by the American Academy of Ophthalmology.
Models of passive and active dendrite motoneuron pools and their differences in muscle force control
Resumo:
Motoneuron (MN) dendrites may be changed from a passive to an active state by increasing the levels of spinal cord neuromodulators, which activate persistent inward currents (PICs). These exert a powerful influence on MN behavior and modify the motor control both in normal and pathological conditions. Motoneuronal PICs are believed to induce nonlinear phenomena such as the genesis of extra torque and torque hysteresis in response to percutaneous electrical stimulation or tendon vibration in humans. An existing large-scale neuromuscular simulator was expanded to include MN models that have a capability to change their dynamic behaviors depending on the neuromodulation level. The simulation results indicated that the variability (standard deviation) of a maintained force depended on the level of neuromodulatory activity. A force with lower variability was obtained when the motoneuronal network was under a strong influence of PICs, suggesting a functional role in postural and precision tasks. In an additional set of simulations when PICs were active in the dendrites of the MN models, the results successfully reproduced experimental results reported from humans. Extra torque was evoked by the self-sustained discharge of spinal MNs, whereas differences in recruitment and de-recruitment levels of the MNs were the main reason behind torque and electromyogram (EMG) hysteresis. Finally, simulations were also used to study the influence of inhibitory inputs on a MN pool that was under the effect of PICs. The results showed that inhibition was of great importance in the production of a phasic force, requiring a reduced co-contraction of agonist and antagonist muscles. These results show the richness of functionally relevant behaviors that can arise from a MN pool under the action of PICs.
Resumo:
Synchronous distributed generators are prone to operate islanded after contingencies, which is usually not allowed due to safety and power-quality issues. Thus, there are several anti-islanding techniques; however, most of them present technical limitations so that they are likely to fail in certain situations. Therefore, it is important to quantify and determine whether the scheme under study is adequate or not. In this context, this paper proposes an index to evaluate the effectiveness of anti-islanding frequency-based relays commonly used to protect synchronous distributed generators. The method is based on the calculation of a numerical index that indicates the time period that the system is unprotected against islanding considering the global period of analysis. Although this index can precisely be calculated based on several electromagnetic transient simulations, a practical method is also proposed to calculate it directly from simple analytical formulas or lookup tables. The results have shown that the proposed approach can assist distribution engineers to assess and set anti-islanding protection schemes.
Resumo:
Abstract Background Air pollution in São Paulo is constantly being measured by the State of Sao Paulo Environmental Agency, however there is no information on the variation between places with different traffic densities. This study was intended to identify a gradient of exposure to traffic-related air pollution within different areas in São Paulo to provide information for future epidemiological studies. Methods We measured NO2 using Palmes' diffusion tubes in 36 sites on streets chosen to be representative of different road types and traffic densities in São Paulo in two one-week periods (July and August 2000). In each study period, two tubes were installed in each site, and two additional tubes were installed in 10 control sites. Results Average NO2 concentrations were related to traffic density, observed on the spot, to number of vehicles counted, and to traffic density strata defined by the city Traffic Engineering Company (CET). Average NO2concentrations were 63μg/m3 and 49μg/m3 in the first and second periods, respectively. Dividing the sites by the observed traffic density, we found: heavy traffic (n = 17): 64μg/m3 (95% CI: 59μg/m3 – 68μg/m3); local traffic (n = 16): 48μg/m3 (95% CI: 44μg/m3 – 52μg/m3) (p < 0.001). Conclusion The differences in NO2 levels between heavy and local traffic sites are large enough to suggest the use of a more refined classification of exposure in epidemiological studies in the city. Number of vehicles counted, traffic density observed on the spot and traffic density strata defined by the CET might be used as a proxy for traffic exposure in São Paulo when more accurate measurements are not available.