67 resultados para 13200-039


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Clock signal distribution in telecommunication commercial systems usually adopts a master-slave architecture, with a precise time basis generator as a master and phase-locked loops (PLLs) as slaves. In the majority of the networks, second-order PLLs are adopted due to their simplicity and stability. Nevertheless, in some applications better transient responses are necessary and, consequently, greater order PLLs need to be used, in spite of the possibility of bifurcations and chaotic attractors. Here a master-slave network with third-order PLLs is analyzed and conditions for the stability of the synchronous state are derived, providing design constraints for the node parameters, in order to guarantee stability and reachability of the synchronous state for the whole network. Numerical simulations are carried out in order to confirm the analytical results. (C) 2009 Elsevier B.V. All rights reserved.

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Despite its outstanding position, the Brazilian citriculture is established on a very limited pool of varieties that limits its expansion and restricts the fruit availability throughout the year. This situation determines the urgent necessity of developing alternative scion and rootstock cultivars, with good performance under local conditions. `Folha Murcha` sweet orange (Citrus sinensis (L.) Osbeck) is a late-harvest cultivar, suitable both for the juice processing industry and the fresh fruit market, being described as tolerant to citrus canker (Xanthomonas citri subsp. citri Schaad et al.), and less affected by citrus variegated chlorosis (Xylella fastidiosa Wells et al.). A study was conducted in Bebedouro, Sao Paulo State, Brazil, to evaluate the horticultural performance of `Folha Murcha` sweet orange budded onto 12 rootstocks: the citrandarin `Changsha` mandarin (Citrus reticulata Blanco) x Poncirus trifoliata `English Small`: the hybrid `Rangpur` lime (Citrus limonia Osbeck) x `Swingle` citrumelo (P. trifoliata (L.) Raf x Citrus paradisi Macfad.); the trifoliates (P. trifoliata (L.) Raf.)`Rubidoux`, `FCAV`, and `Flying Dragon` (P. trifoliata var. monstrosa); the `Sun Chu Sha Kat` mandarin (C. reticulata Blanco); the `Sunki` mandarin (Citrus sunki (Hayata) Hart. ex. Tanaka); the `Rangpur` limes (C. limonia Osbeck) `Cravo Limeira` and `Cravo FCAV`; `Carrizo` citrange (C. sinensis x P. trifoliata), `Swingle` citrumelo (P. trifoliata x C. paradisi), and `Orlando` tangelo (C. paradisi x Citrus tangerina cv. `Dancy`). The experimental grove was planted in 2001, using a 7 m x 4 m spacing, in a randomized block design, with five replications and two plants per plot. No supplementary irrigation was applied. Fruit yield, canopy volume, tree tolerance to drought and to citrus variegated chlorosis, and fruit quality were assessed for each rootstock. Trees grafted onto the `Flying Dragon` trifoliate were smaller in size, but had largest yield efficiency when compared to those grafted onto other rootstocks. Lower alternate bearing index was observed on trees budded onto `Cravo FCAV` `Rangpur` lime. Both `Rangpur` lime rootstocks and the `Sunki` mandarin induced higher tree tolerance to drought. The `Flying Dragon` trifoliate induced better fruit quality and higher tolerance to citrus variegated chlorosis (CVC) to `Folha Murcha` trees. A cluster multivariate analysis identified three groups of rootstocks with similar effects on `Folha Murcha` tree performance. Among the 12 evaluated rootstocks, the `Flying Dragon` trifoliate has a unique effect on plant growth, tolerance to drought and CVC, fruit yield and fruit quality of `Folha Murcha` trees, and may be better suited for high-density plantings. (C) 2011 Elsevier B.V. All rights reserved.

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By allowing the estimation of forest structural and biophysical characteristics at different temporal and spatial scales, remote sensing may contribute to our understanding and monitoring of planted forests. Here, we studied 9-year time-series of the Normalized Difference Vegetation Index (NDVI) from the Moderate Resolution Imaging Spectroradiometer (MODIS) on a network of 16 stands in fast-growing Eucalyptus plantations in Sao Paulo State, Brazil. We aimed to examine the relationships between NDVI time-series spanning entire rotations and stand structural characteristics (volume, dominant height, mean annual increment) in these simple forest ecosystems. Our second objective was to examine spatial and temporal variations of light use efficiency for wood production, by comparing time-series of Absorbed Photosynthetically Active Radiation (APAR) with inventory data. Relationships were calibrated between the NDVI and the fractions of intercepted diffuse and direct radiation, using hemispherical photographs taken on the studied stands at two seasons. APAR was calculated from the NDVI time-series using these relationships. Stem volume and dominant height were strongly correlated with summed NDVI values between planting date and inventory date. Stand productivity was correlated with mean NDVI values. APAR during the first 2 years of growth was variable between stands and was well correlated with stem wood production (r(2) = 0.78). In contrast, APAR during the following years was less variable and not significantly correlated with stem biomass increments. Production of wood per unit of absorbed light varied with stand age and with site index. In our study, a better site index was accompanied both by increased APAR during the first 2 years of growth and by higher light use efficiency for stem wood production during the whole rotation. Implications for simple process-based modelling are discussed. (C) 2009 Elsevier B.V. All rights reserved.

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Pothomorphe umbellata is a native plant widely employed in the Brazilian popular medicine. This plant has been shown to exert a potent antioxidant activity on the skin and to delay the onset and reduce the incidence of UVB-induced skin damage and photoaging. The aim of this work was to optimize the appearance, the centrifuge stability and the permeation of emulsions containing R umbellata (0. 1% 4-nerolidylchatecol). Experimental design was used to study ternary mixtures models with constraints and graphical representation by phase diagrams. The constraints reduce the possible experimental domain, and for this reason, this methodology offers the maximum information while requiring the minimum investment. The results showed that the appearance follows a linear model, and that the aqueous phase was the principal factor affecting the appearance; the centrifuge stability parameter followed a mathernatic quadratic model and the interactions between factors produced the most stable emulsions; skin permeation was improved by the oil phase, following a linear model generated by data analysis. We propose as optimized P. umbellata formulation: 68.4% aqueous phase, 26.6% oil phase and 5.0% of self-emulsifying phase. This formulation displayed an acceptable compromise between factors and responses investigated. (c) 2007 Elsevier B.V. All rights reserved.

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Adsorption of Ni(2+), Zn(2+) or Pb(2+) by dry biomass of Arthrospira (Spirulina) platensis and Chlorella vulgaris was studied as a function of contact time and initial metal concentration. The zero point of charge calculated for these biosorbents (pH(zpc) 4.0 and 3.4, respectively) and additional pH tests suggested the use of pH in the range 5.0-5.5 for the experiments. The equilibrium isotherms were evaluated in terms of maximum sorption capacity and sorption affinity. The pseudo first and second order kinetic models were considered to interpret the experimental data, and the latter best described the adsorption system. Both the Freundlich and Langmuir models were shown to well describe the sorption isotherms, thus suggesting an intermediate mono/multilayer sorption mechanism. Compared to A. platensis (q(e) = 0.354, 0.495 and 0.508 mmol g(-1) for Ni(2+), Pb(2)+ and Zn(2+), respectively), C. vulgaris behaved as a better biosorbent because of higher equilibrium sorption capacity (q(e) = 0.499, 0.634 and 0.664 mmol g(-1), respectively). The removal efficiency decreased with increasing metal concentration, pointing out a passive adsorption process involving the active sites on the surface of the biomasses. The FT-IR spectroscopy evidenced that ions removal occurred mainly by interaction between metal and carboxylate groups present on both the cell walls. (C) 2011 Elsevier B.V. All rights reserved.

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This study investigated the effects of atorvastatin on ABCB1 and ABCC1 mRNA expression on peripheral blood mononuclear cells (PBMC) and their relationship with gene polymorphisms and lowering-cholesterol response. one hundred and thirty-six individuals with hypercholesterolemia were selected and treated with atorvastatin (10 mg/day/4 weeks). Blood samples were collected for serum lipids and apolipoproteins measurements and DNA and RNA extraction. ABCB1 (C3435T and G2677T/A) and ABCC1 (G2012T) gene polymorphisms were identified by polymerase chain reaction-restriction (PCR)-RFLP and mRNA expression was measured in peripheral blood mononuclear cells by singleplex real-time PCR. ABCB1 polymorphisms were associated with risk for coronary artery disease (CAD) (p < 0.05). After atorvastatin treatment, both ABCB1 and ABCC1 genes showed 50% reduction of the mRNA expression (p < 0.05). Reduction of ABCB1 expression was associated with ABCB1 G2677T/A polymorphism (p = 0.039). Basal ABCB1 mRNA in the lower quartile (<0.024) was associated with lower reduction rate of serum low-density lipoprotein (LDL) cholesterol (33.4 +/- 12.4%) and apolipoprotein B (apoB) (17.0 +/- 31.3%) when compared with the higher quartile (>0.085: LDL-c = 40.3 +/- 14.3%; apoB = 32.5 +/- 10.7%; p < 0.05). ABCB1 substrates or inhibitors did not affect the baseline expression, while ABCB1 inhibitors reversed the effects of atorvastatin on both ABCB1 and ABCC1 transporters. In conclusion, ABCB1 and ABCC1 mRNA levels in PBMC are modulated by atorvastatin and ABCB1 G2677T/A polymorphism. and ABCB1 baseline expression is related to differences in serum LDL cholesterol and apoB in response to atorvastatin. (C) 2008 Elsevier Inc. All rights reserved.

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A method for the determination of artemether (ART) and its main metabolite dihydroartemisinin (DHA) in plasma employing liquid-phase microextraction (LPME) for sample preparation prior to liquid chromatography-tandem mass spectrometry (LC-MS-MS) was developed. The analytes were extracted from 1 nil, of plasma utilizing a two-phase LPME procedure with artemisinin as internal standard. Using the optimized LPME conditions, mean absolute recovery rates of 25 and 32% for DHA and ART, respectively, were achieved using toluene-n-octanol (1:1, viv) as organic phase with an extraction time of 30 min. After extraction, the analytes were resolved within 5 min using a mobile phase consisting of methanol-ammonium acetate (10 mmol L(-1) pH 5.0, 80:20. v/v) on a laboratory-made column based on poly(methyltetradecylsiloxane) attached to a zirconized-silica support. MS-MS detection was employed using an electrospray interface in the positive ion mode. The method developed was linear over the range of 5-1000 ng mL(-1) for both analytes. Precision and accuracy were within acceptable levels of confidence (<15%). The assay was applied to the determination of these analytes in plasma from rats treated with ART. The two-phase LPME procedure is affordable and the solvent consumption was very low compared to the traditional methods of sample preparation. (C) 2010 Elsevier B.V. All rights reserved.

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Dehydroepiandrosterone (DHEA) enhances immune responses against a wide range of viral, bacterial, and parasitic pathogens. In a previous study, we reported that administration of DHEA significantly decreased the numbers of blood parasites in Trypanosoma cruzi experimental infection. The present study was undertaken to determine the effectiveness of DHEA in reducing the severity of acute phase T cruzi infection of male and female Wistar rats. Animals were treated subcutaneously with 40 mg/kg body weight/day of DHEA. The concentration of nitric oxide (NO) was determined in spleen peritoneal cavity. Interleukin-2 (IL-2) and interferon-gamma (IFN-gamma) were determined in the sera of uninfected and infected animals. DHEA treatment augments NO production for both sexes after in vitro LPS treatment for uninfected animals. Infection triggered enhanced NO levels although not significant. IL-2 and IFN-gamma were detectable in higher concentrations in treated and infected rats of both genders when compared to untreated controls. These data suggest that DHEA may have a potent immunoregulatory function that can affect the course of T cruzi infection. (c) 2008 Elsevier B.V. All rights reserved.

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The squat lobster Pleuroncodes monodon is one of the most common and abundant galatheid species in the deepwater fishery of Pacific coast of America. In contrast with Peru and Chile, the red squat lobster is not commercially exploited in Costa Rica. Here we estimated the size of sexual maturity and analysed egg production in P. monodon from the Pacific of Costa Rica; the results might be important for an adequate management strategy when initiating a sustainable fishery of this resource in Costa Rica. Analyses of allometric growth revealed that females and males reached their morphological sexual maturity at 26.9 and 30.4 mm CL. respectively. The percentage of immature females captured in the present study (54%) suggests that almost half of females are able to reproduce before they are caught. Egg production was positively correlated with body size; females that measured between 24.1 and 29.0 mm CL contributed roughly 90% to the offspring production of the population. Females from Costa Rica had a considerably lower average egg volume (0.039 mm(3)) and higher fecundity (9810) than females from Chile. In comparison to other American galatheids P. monodon from Costa Rica produces numerous but small eggs, a typical strategy of species with a prolonged larval development. An analysis between our results and information published about P. monodon from Chile also revealed differences in the size-frequency distribution shape of both populations. The non-exploited character of the Costa Rican P. monodon population and a latitudinal (temperature-related) cline in body size might be associated with these differences. (C) 2010 Elsevier B.V. All rights reserved.

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The antichromatin antibody (aCT) has been described as a useful marker for lupus nephropathy. The relevance of its nephritogenic potential may be appropriately evaluated in the context of renal histopathology. Therefore, the present study investigated the relationship of aCT with a particular histopathologic class of lupus nephritis (LN). Seventy-eight consecutive patients with systemic lupus erythematosus (ACR criteria) and active nephritis who underwent renal biopsy from 1999 to 2004 and with available frozen serum sample obtained at the time of biopsy were selected. aCT was measured by ELISA, and anti-dsDNA was measured by indirect immunofluorescence (IIF) and by ELISA. All renal biopsies were revised in a blinded manner by the same expert renal pathologist. Charts were extensively reviewed for demographic and renal features obtained at the time of biopsy. The prevalence of aCT (>= 20 U) was 59% with a mean titer of 74.3 +/- 38.7U. Both aCT-positive and aCT-negative groups of patients had similar age, gender distribution, duration of lupus, and duration of renal disease. Anti-dsDNA was detected by IIF in 29.5% and by ELISA in 42.3% of the patients. Concomitant presence of both antibodies was observed in 63% (29/46) [anti-dsDNA by ELISA] and 45.6% (21/46) [anti-dsDNA by IIF] of the patients. Lower serum levels of C3 (73% vs. 40%, P=0.0058) and C4 (82% vs. 46.7%, P=0.0021) were more commonly observed in aCT >= 20 U patients compared to the aCT-negative group. It is important to note that the use of a higher cut-off value (>= 40 U) for aCT test revealed a predominance of class IV LN (58% vs. 33%, P=0.039) in aCT >= 40 U compared to aCT<40 U group. The mean levels of proteinuria, serum albumin, and creatinine were markedly altered but were comparable in both groups (P >= 0.05). One fourth (26.3%) of the 19 patients with class IV LN and aCT >= 40 U had no detectable anti-dsDNA (ELISA). These data suggest that high-titer aCT seems to be a valuable biomarker for proliferative class IV of LN.

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Background: The antiatherogenic functions of high density lipoprotein (HDL-C) include its role in reverse cholesterol transport, but to what extent the concentration of HDL-C interferes with the whole-body cholesterol metabolism is unknown. Therefore, we measured markers of body cholesterol synthesis (desmosterol and lathosterol) and of intestinal cholesterol absorption (campesterol and beta-sitosterol) in healthy subjects that differ according to their plasma HDL-C concentrations. Methods: Healthy participants presented either low HDL-C (<40 mg/dl, n = 33,17 male and 16 female) or high HDL-C (>60 mg/dl, n = 33, 17 male and 16 female), BMI <30 kg/m(2), were paired according to age and gender, without secondary factors that might interfere with their plasma lipid concentrations. Plasma concentrations of non-cholesterol sterols were measured by the combined GC-MS analysis. Results: Plasma desmosterol did not differ between the two groups; however, as compared with the high HDL-C participants, the low HDL-C participants presented higher concentration of lathosterol and lower concentration of the intestinal cholesterol absorption markers campesterol and beta-sitosterol. Conclusion: Plasma concentrations of HDL, and not the activities of LCAT and CETP that regulate the reverse cholesterol transport system, correlate with plasma sterol markers of intestinal cholesterol absorption directly, and of cholesterol synthesis reciprocally. (C) 2010 Elsevier B.V. All rights reserved.

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The aim of this study was to analyze vitamin D levels and their association with bone mineral density and body composition in primary antiphospholipid syndrome. For this cross-sectional study 23 premenopausal women with primary antiphospholipid syndrome (Sapporo criteria) and 23 age- and race-matched healthy controls were enrolled. Demographic, anthropometric, clinical and laboratorial data were collected using clinical interview and chart review. Serum 25-hydroxyvitamin D levels, parathormone, calcium and 24-hour urinary calcium were evaluated in all subjects. Bone mineral density and body composition were studied by dual X-ray absorptiometry. The mean age of patients and controls was 33 years. Weight (75.61 [20.73] vs. 63.14 [7.34] kg, p=0.009), body mass index (29.57 [7.17] vs. 25.35 [3.37] kg, p=0.014) and caloric ingestion (2493 [1005.6] vs. 1990 [384.1] kcal/day, p=0.03) were higher in PAPS than controls. All PAPS were under oral anticoagulant with INR within therapeutic range. Interestingly, biochemical bone parameters revealed lower levels of 25-hydroxyvitamin D [21.64 (11.26) vs. 28.59 (10.67) mg/dl, p=0.039], serum calcium [9.04 (0.46) vs. 9.3 (0.46) mg/dl, p=0.013] and 24-hour urinary calcium [106.55 (83.71) vs. 172.92 (119.05) mg/d, p=0.027] in patients than in controls. Supporting these findings, parathormone levels were higher in primary antiphospholipid syndrome than in controls [64.82 (37.83) vs. 44.53 (19.62) pg/ml, p=0.028]. The analysis of osteoporosis risk factors revealed that the two groups were comparable (p>0.05). Lumbar spine, femoral neck, total femur and whole body bone mineral density were similar in both groups (p>0.05). Higher fat mass [28.51 (12.93) vs. 20.01 (4.68) kg, p=0.005] and higher percentage of fat [36.08 (7.37) vs. 31.23 (4.64)%, p=0.010] were observed in PAPS in comparison with controls; although no difference was seen regarding lean mass. In summary, low vitamin D in primary antiphospholipid syndrome could be secondary to higher weight and fat mass herein observed most likely due to adipocyte sequestration. This weight gain may also justify the maintenance of bone mineral density even with altered biochemical bone parameters. Lupus (2010) 19, 1302-1306.

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Background Heart failure and diabetes often occur simultaneously in patients, but the prognostic value of glycemia in chronic heart failure is debatable. We evaluated the role of glycemia on prognosis of heart failure. Methods Outpatients with chronic heart failure from the Long-term Prospective Randomized Controlled Study Using Repetitive Education at Six-Month Intervals and Monitoring for Adherence in Heart Failure Outpatients (REMADHE) trial were grouped according to the presence of diabetes and level of glycemia. All-cause mortality/heart transplantation and unplanned hospital admission were evaluated. Results Four hundred fifty-six patients were included (135 [29.5%] female, 124 [27.2%] with diabetes mellitus, age of w50.2 +/- 11.4 years, and left-ventricle ejection fraction of 34.7% +/- 10.5%). During follow-up (3.6 +/- 2.2 years), 27 (5.9%) patients were submitted to heart transplantation and 202 (44.2%) died; survival was similar in patients with and without diabetes mellitus. When patients with and without diabetes were categorized according to glucose range (glycemia <= 100 mg/dL [5.5 mmol/L]), as well as when distributed in quintiles of glucose, the survival was significantly worse among patients with lower levels of glycemia. This finding persisted in Cox proportional hazards regression model that included gender, etiology, left ventricle ejection fraction, left ventricle diastolic diameter, creatinine level and beta-blocker therapy, and functional status (hazard ratio 1.45, 95% CI 1.09-1.69, P = .039). No difference regarding unplanned hospital admission was found. Conclusion We report on an inverse association between glycemia and mortality in outpatients with chronic heart failure. These results point to a new pathophysiologic understanding of the interactions between diabetes mellitus, hyperglycemia, and heart disease. (Am Heart J 2010; 159: 90-7.)

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Long latency auditory evoked potentials (LLAEP) alterations in individuals with tinnitus are suggestive of dysfunction in the central auditory pathways at a cortical level. Aim: to characterize the LLAEP in individuals with and without tinnitus exposed to occupational noise. Method: Cross-sectional contemporary cohort, prospective study. Sixty subjects exposed to occupational noise, ranging in age from 29 to 50 years underwent LLAEP assessment; 30 of them had tinnitus complaint and 30 did not have tinnitus. Results: we observed significant statistical difference regarding the mean values of latencies of waves N1 (p<0.001), P2 (p=0.002) and P300 (p=0.039) when we compared individuals with and without tinnitus. In individuals with tinnitus we also noticed a greater number of altered results concerning components N1 (60%) and P2 (66.7%), although only component P2 presented significant statistical difference (p=0.010). For the LLAEP, the latency increase was the only type of alteration found (p=1.000). We found a greater association between bilateral tinnitus and bilateral alteration for all components N1(73%), P2(73%) and P300(50%). Conclusion: It is relevant to study LLAEP in individuals with tinnitus exposed to high occupational sound pressure levels.

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Background & Aims: Treatment with peginterferon alfa and ribavirin produces a sustained virologic response (SVR) in approximately 60% of hepatitis C virus (HCV)-infected patients. Alternate options are needed for patients who relapse or do not respond to therapy. Methods: This prospective, international, multicenter, open-label study evaluated efficacy and safety of peginterferon alfa-2b (1.5 mu g/kg/wk) plus weight-based ribavirin (800-1400 mg/day) in 2333 chronic HCV-infected patients with significant fibrosis/cirrhosis whose previous interferon alfa/ribavirin therapy failed. Patients with undetectable HCV-RNA at treatment week (TW) 12 received 48 weeks of therapy; patients with detectable HCV-RNA at TW12 could enter maintenance studies at TW18; 188 patients with low/detectable HCV-RNA at TW12 continued therapy at the investigator`s request. Results: Overall, 22% of the patients attained SVR (56% with undetectable HCV-RNA and 12% with low/detectable HCV-RNA at TW12). SVR was better in relapsers (38%) than nonresponders (14%), regardless of previous treatment, and in patients previously treated with interferon-alfa/ribavirin (25%) than peginterferon alfa-ribavirin (17%). Predictors of response in patients with undetectable HCV-RNA at TW12 were genotype (2/3 vs 1, respectively; odds ratio [OR] 2.4; P < .0001), fibrosis score (F2 vs F4; OR, 2.2; F3 vs F4; OR, 1.7; P < .0001), and baseline viral load (<= 600,000 vs >600,000 IU/mL; OR, 1.4; P = .0223). These factors plus previous treatment and response were overall predictors of SVR. Safety was similar among fibrosis groups. Conclusions: Peginterferon alfa-2b plus weight-based ribavirin is effective and safe in patients who failed interferon alfa/ribavirin therapy. Genotype, baseline viral load, and fibrosis stage were predictors of response.