Efectos del tamaño de anzuelo sobre capturas y tallas del perico Coryphaena hippurus

Se evidenció alta selección interespecífica del espinel superficial experimental, al capturar 130 ejemplares de perico Coryphaena hippurus (87,8%) del total de 148 especímenes que incluyeron 8 especies entre peces, tortugas y cefalópodos; como pesca incidental se registró 1 enganche por lance de tortugas (verde Chelonia mydas y amarilla Caretta caretta). El anzuelo más eficiente para la captura de esta especie, fue el de menor calibre (Nº 6) que capturó 24,6%, el menos eficiente fue el Nº 5 (16,9%); sin embargo, mediante el ANOVA de dos vías se estableció que no existía efecto del tamaño de anzuelo sobre el número de ejemplares capturados (p= 0,963). Los anzuelos no evidenciaron una selección de tallas, al no establecerse diferencias significativas entre distribución de tallas (p= 0,538), excepto para los anzuelos Nº 2 y 6 (p= 0,084), al identificarse diferencia por efecto del tamaño de anzuelo. Las longitudes medias estimadas fueron 119,7 cm, 116,8 cm, 118,3 cm, 115,0 cm y 113,7 cm, para los anzuelos Nº 2, 3, 4, 5 y 6, respectivamente. El tamaño de anzuelo mostró un fuerte efecto sobre el tipo de enganche (p= 0,002), presentándose con mayor frecuencia los enganches en la agalla (53,1%) y boca (44,6%). Generalmente los enganches en la agalla son ocasionados por los anzuelos grandes (Nº 2 y 3), mientras que los de boca son realizados por los anzuelos más pequeños (Nº 5 y 6). La captura por unidad de esfuerzo (CPUE) global del longline experimental fue 1,2 ejemplares de perico para un esfuerzo de 1000 anzuelos por hora, lo que representa la tercera parte de la CPUE estimada para la flota comercial.

A new method to measure rolling resistance in treadmill cycling.

The purpose of this study was to evaluate a new method of measuring rolling resistance in treadmill cycling and to establish its sensitivity and reproducibility. One participant was asked to keep a bicycle in equilibrium on a treadmill without pedalling at a constant speed of 5.56 m x s(-1), which was held in place in the front by a dynamometer. For each condition, the method consisted of 11 measurements of the force required to hold the cycle at different treadmill slopes (0-10%, increment 1%). The coefficient of rolling resistance was calculated based on the forces applied to the bicycle in equilibrium. To test the sensitivity of the method, the bicycle was successively equipped with three tyre types (700 x 28, 700 x 23, 700 x 22) and inflation pressure was set at 150, 300, 600, 900, and 1100 kPa. To test the reproducibility of the method, a second experimenter repeated all measurements done with the 700 x 23 tyres. The method was sensitive enough to detect an effect of both tyre type and inflation pressure (P < 0.001: two-way ANOVA). The measurement of the coefficient of rolling resistance by two separate experimenters resulted in a small bias of 0.00029 (95% CI, -0.00011 to 0.00068). In conclusion, the new method is sensitive and reliable, as well as being simple and affordable.

The relationship between a short measure of health status and physical activity in a workplace population.

Many interventions promoting physical activity (PA) are effective in preventing disease onset, and although studies have found a positive relationship between health-related quality of life (HRQL) and PA, most of these studies have focused on older adults and those with chronic conditions. Less is known regarding the association between PA level and HRQL among healthy adults. Our objective was to analyse the relationship between PA level and HRQL among a sample of 573 employees aged 20-68 taking part in a workplace intervention to promote PA. Measures included HRQL (using a single item) and PA (i.e. Godin Leisure-Time Questionnaire). The Modified Canadian Aerobic Fitness Test (MCAFT) was also completed by 10% of the employees. MET-minute scores (assessing energy expenditure over one week) were compared across HRQL categories using ANOVA. A multiple linear regression analysis was conducted to further examine the relationship between HRQL and PA, controlling for potential covariates. Participants in the higher health status categories were found to report higher levels of energy expenditure (one-way ANOVA, p < 0.001). In the multiple linear regression model, each unit increase in health status level translated in a mean increase of 356 MET-minutes in energy expenditure (p < 0.001). This single-item assessment of health status explained six percent of the variance in energy expenditure. The study concludes that higher energy expenditure through PA among an adult workplace population is positively associated with increased health status, and it also suggests that a single-item HRQL measure is suitable for community- and population-based studies, reducing response burden and research costs.

Características químicas do lixo de formigueiros de Atta sexdens rubropilosa (Hymenoptera: Formicidae) mantidos com diferentes substratos

As saúvas (Atta spp.) estão amplamente distribuídas pelo continente Sul-Americano e são consideradas importantes componentes do ecossistema neotropical. Diversos estudos têm demonstrado o efeito de formigueiros no enriquecimento do solo e na facilitação ao estabelecimento de espécies vegetais. Possivelmente o enriquecimento do solo seja devido ao acúmulo de matéria orgânica decomposta em câmaras de descarte (lixo) no interior das colônias. Entretanto, pouco se sabe sobre a composição química do lixo de formigas cortadeiras. O objetivo do presente trabalho foi comparar os teores de nutrientes do lixo produzido por colônias de Atta sexdens rubropilosa Forel (Hymenoptera: Formicidae), em laboratório, mantidas com folhas de duas espécies de plantas. Os tratamentos foram dois tipos de substrato (Acalypha sp. ou Bauhinia sp.), repetidos quatro vezes. Oito colônias foram divididas em dois grupos (n = 4), e cada grupo foi mantido com apenas um tratamento. Após 30 dias de experimento, as amostras de folhas e lixo foram secas em estufa (70 ºC) e submetidas à digestão ácida, para determinação das concentrações de N, P, K, S, Ca e Mg. Diferenças nas concentrações dos macronutrientes entre os tratamentos (lixo ou folha) foram comparadas por meio de ANOVA e teste T. As concentrações de nutrientes no lixo foram sempre maiores do que nas folhas, independentemente da espécie cortada. Folhas de Acalypha sp. apresentaram concentrações significativamente maiores do que folhas de Bauhinia sp. com relação aos teores de P, Ca, Mg e S; entretanto, as concentrações do lixo em todos os formigueiros foram muito próximas, indicando incorporação adicional de nutrientes por meio do fungo, excreções e, ou, cadáveres no lixo. Esses resultados indicam que, independentemente do substrato cortado, o lixo produzido apresenta maiores concentrações de nutrientes do que as folhas, sendo importante locus de reciclagem de nutrientes no ecossistema. O lixo pode ser uma das principais razões para o aumento da concentração de nutrientes em solos de formigueiros.

Effect of antiviral therapy on circulating cytokeratin-18 fragments in patients with chronic hepatitis C.

Hepatocellular apoptosis plays a major role in the pathogenesis of chronic hepatitis C. It can be measured noninvasively by determining the circulating levels of cytokeratin-18 fragments. We hypothesized that the effect of antiviral therapy on this parameter will be different in patients with a sustained virological response, relapse (REL) and nonresponse (NR). We quantified cytokeratin-18 fragments in plasma of patients participating in the Swiss Hepatitis C cohort, who received antiviral therapy without stopping because of sides effects. A total of 315 patients were included, 183 with a sustained response, 64 with NR and 68 who relapsed. Mean levels ±SD of circulating cytokeratin-18 fragments before therapy were 174 ± 172 U/L for responsders, 188 ± 145 for nonresponders and 269 ± 158 U/L for patients who relapsed. The values were significantly higher in the REL group (ANOVA P < 0.006). A sustained response was associated with a significant improvement of the plasma levels (94 ± 92 U/L, paired test P < 0.000001), whereas there was no improvement in the nonresponder group (183 ± 158 U/L) and in the relapser group (158 ± 148 U/L). There was a weak correlation between alanine aminotransferase (ALT) and cytokeratin-18 fragment levels (r² = 0.35, P < 0.000001) before therapy but not after therapy and none with hepatitis C virus (HCV) viremia. Successful antiviral therapy results in a significant decrease in circulating levels of cytokeratin-18 fragments arguing for a reduction in hepatocellular apoptosis after clearance of the HCV. Baseline cytokeratin-18 fragment levels are higher in relapsers. Correlations with ALT are weak, suggesting that these two tests measure different but related processes.

Effects of long-term estrogen replacement therapy in postmenopausal women with coronary risk factors

Objective: Hormone replacement therapy (HRT) with estrogen alone or in concert with progesterone may exert beneficial effects on coronary endothelium-dependent vasomotion in postmenopausal women without traditional coronary risk factors. We aimed to evaluate the effect of HRT on coronary vasomotor function in postmenopausal women with traditional coronary risk factors such as hypertension, hypercholesterolemia and smoking as compared to those without HRT. Methods: Combining N-13 ammonia with PET, myocardial blood flow (MBF) was measured in ml/g/min at rest, during cold pressor test (CPT, reflecting predominantly endothelium-dependent vasomotion)and during pharmacologic vasodilation (representing predominantly endothelium-independent vasomotion) in 48 postmenopausal women with various coronary risk factors during a mean follow up (FU) of 20_9 months. postmenopausal women wer grouped according to HRT: group 1 with HRT (n_18), group 2 without HRT (n_18) and group 3 with HRT at baseline but not at FU (n_12). Results: during FU, HRT did not significantly affect lipid profile and plasma glucose levels. At baseline resting MBF was similar between groups (Table).After the FU, in group 2 and 3 the endothelium-related increase in MBF from rest to CPT (_ MBF) was significantly less than at baseline (*p_0.05) (Table). Conversely, in group 1 _MBF to CPT at FU was not significantly different from the baseline study. The group comparison of CPT-induced _MBF in group 2 and group 3 after the FU period was significantly different from group 1 (p_0.006 by ANOVA). Finally, in all three groups, hyperemic MBFs during pharmacologic vasodilation did not differ significantly between baseline and FU (Table). Conclusion: In postmenopausal women with coronary risk factors, HRT may counterbalance the adverse effects of traditional coronary risk factors on endothelium-dependent coronary vasomotion. Consequently, in addition to standard management of coronary risk factors, HRT may exert beneficial effects on the coronary endothelium that may delay the progression of coronary artery disease in postmenopausal women.

Colêmbolos (Hexapoda: Collembola) como bioindicadores de qualidade do solo em áreas com Araucaria angustifolia

Não existem informações sobre a diversidade de colêmbolos associados às florestas com Araucaria angustifolia (Bert.) O. Kuntze no Brasil. Este estudo teve o objetivo de avaliar o potencial da diversidade de famílias de colêmbolos como bioindicadores da qualidade do solo e para separar diferentes áreas com araucária, utilizando atributos químicos e microbiológicos do solo como variáveis explicativas. O estudo foi realizado em quatro áreas: 1. floresta nativa com predominância de araucária (NF); 2. reflorestamento de araucária (R); 3. reflorestamento de araucária submetido a incêndio acidental (RF); e 4. pastagem natural com araucárias nativas e ocorrência de incêndio acidental (NPF). Na captura dos organismos, utilizaram-se dez armadilhas, distribuídas ao acaso em cada área, nos mesmos pontos de coleta dos atributos químicos e microbiológicos do solo. O número de colêmbolos de cada família, extraído por armadilhas (abundância), o índice de diversidade de Shannon (H) e a riqueza de famílias foram submetidos à Análise de Variância (ANOVA). A abundância de cada família de Collembola foi submetida à Análise de Componentes Principais (ACP). Considerando as quatro áreas, foram identificadas oito famílias de colêmbolos (Brachystomellidae, Entomobryidae, Hypogastruridae, Isotomidae, Katiannidae, Paronellidae, Sminthuridae e Tomoceridae). A diversidade de famílias de colêmbolos foi maior nas áreas NF e R, em comparação com as áreas RF e NPF. Os atributos químicos e microbiológicos do solo foram eficientes como variáveis explicativas, pois auxiliaram na interpretação das modificações das famílias de colêmbolos. A ACP mostrou que a identificação ao nível de família de Collembola é suficiente para separar as áreas estudadas, além de indicar quais foram as famílias de colêmbolos mais associadas a cada área, o que possibilita sua utilização como bioindicadores de intervenções antrópicas, bem como da qualidade do solo.

Transient Ischemic Dilation (TID) ratio measurement during Rb-82 cardiac PET: Comparison between three different software packages.

Background: TIDratio indirectly reflects myocardial ischemia and is correlated with cardiacprognosis. We aimed at comparing the influence of three different softwarepackages for the assessment of TID using Rb-82 cardiac PET/CT. Methods: Intotal, data of 30 patients were used based on normal myocardial perfusion(SSS<3 and SRS<3) and stress myocardial blood flow 2mL/min/g)assessed by Rb-82 cardiac PET/CT. After reconstruction using 2D OSEM (2Iterations, 28 subsets), 3-D filtering (Butterworth, order=10, ωc=0.5), data were automatically processed, and then manually processed fordefining identical basal and apical limits on both stress and rest images.TIDratio were determined with Myometrix®, ECToolbox® and QGS®software packages. Comparisons used ANOVA, Student t-tests and Lin concordancetest (ρc). Results: All of the 90 processings were successfullyperformed. TID ratio were not statistically different between software packageswhen data were processed automatically (P=0.2) or manually (P=0.17). There was a slight, butsignificant relative overestimation of TID with automatic processing incomparison to manual processing using ECToolbox® (1.07 ± 0.13 vs 1.0± 0.13, P=0.001)and Myometrix® (1.07 ± 0.15 vs 1.01 ± 0.11, P=0.003) but not using QGS®(1.02 ±0.12 vs 1.05 ± 0.11, P=0.16). The best concordance was achieved between ECToolbox®and Myometrix® manual (ρc=0.67) processing.Conclusion: Using automatic or manual mode TID estimation was not significantlyinfluenced by software type. Using Myometrix® or ECToolbox®TID was significantly different between automatic and manual processing, butnot using QGS®. Software package should be account for when definingTID normal reference limits, as well as when used in multicenter studies. QGS®software seemed to be the most operator-independent software package, whileECToolbox® and Myometrix® produced the closest results.

Viabilidade técnica do uso de receptores GPS de navegação para fins de amostragem sistemática de solo

Os receptores de navegação do sistema de posicionamento global (GPS), comumente utilizados pelo setor agrícola, em geral, apresentam precisão posicional < 10,0 m. Em uma amostragem sistemática de solos, as subamostras deverão ser coletadas num raio não superior a 3 m do ponto central georreferenciado. A presente nota técnica visou confrontar a precisão e exatidão desse tipo de equipamento com a necessidade exigida em amostragem sistematizada de solo. Uma área com aproximadamente 17 ha, no campus I da Universidade de Passo Fundo, foi levantada com três receptores GPS de navegação e Estação Total-ET (controle). Pontos centrais de quadrículas de 2 ha, gerados pelo programa Campeiro®, foram locados no campo com os mesmos equipamentos. Sobre esses pontos, materializados no campo, foram novamente tomadas as suas coordenadas, com auxílio da estação total. Assim, as coordenadas X e Y foram submetidas à ANOVA, confrontando-se as médias obtidas pela ET com as dos receptores de GPS pela diferença honesta significativa do teste de Tukey (p < 0,01). Quanto à exatidão, calcularam-se, por Pitágoras, as distâncias lineares entre os pontos gerados pelos GPS e pela ET, assumindo-se não exatas quando ultrapassaram os 3 m de raio preconizado pelo Manual de Adubação e Calagem do Rio Grande do Sul e de Santa Catariana para coleta de solo. A exatidão das coordenadas dos receptores GPS variou de -10 m a +3 m para X e de -4 m a +7 m para Y. Apenas um ponto central dos oito locados com os receptores de GPS de navegação no centro das quadrículas apresentou exatidão compatível com a exigida pela prática. Isso indica que esse tipo de equipamento, com baixa precisão e exatidão, não deve ser utilizado para amostragem sistematizada de solos.

Implications of the variability in soil penetration resistance for statistical analysis

Soil penetration resistance (PR) is a measure of soil compaction closely related to soil structure and plant growth. However, the variability in PR hampers the statistical analyses. This study aimed to evaluate the variability of soil PR on the efficiency of parametric and nonparametric analyses in indentifying significant effects of soil compaction and to classify the coefficient of variation of PR into low, medium, high and very high. On six dates, the PR of a typical dystrophic Red Ultisol under continuous no-tillage for 16 years was measured. Three tillage and/or traffic conditions were established with the application of: (i) no chiseling or additional traffic, (ii) additional compaction, and (iii) chiseling. On each date, the nineteen PR data (measured at every 1.5 cm to a depth of 28.5 cm) were grouped in layers with different thickness. In each layer, the treatment effects were evaluated by variance (ANOVA) and Kruskal-Wallis analyses in a completely randomized design, and the coefficients of variation of all analyses were classified (low, intermediate, high and very high). The ANOVA performed better in discriminating the compaction effects, but the rejection rate of null hypothesis decreased from 100 to 80 % when the coefficient of variation increased from 15 to 26 %. The values of 15 and 26 % were the thresholds separating the low/intermediate and the high/very high coefficient variation classes of PR in this Ultisol.

A Laboratory Investigation into the Effects of the Aggregated Related Facts of Critical VMA in Asphalt Paving Mixtures, June 2000

This report summarizes research conducted at Iowa State University on behalf of the Iowa Department of Transportation, focusing on the volumetric state of hot-mix asphalt (HMA) mixtures as they transition from stable to unstable configurations. This has raditionally been addressed during mix design by meeting a minimum voids in the mineral aggregate (VMA) requirement, based solely upon the nominal maximum aggregate size without regard to other significant aggregate-related properties. The goal was to expand the current specification to include additional aggregate properties, e.g., fineness modulus, percent crushed fine and coarse aggregate, and their interactions. The work was accomplished in three phases: a literature review, extensive laboratory testing, and statistical analysis of test results. The literature review focused on the history and development of the current specification, laboratory methods of identifying critical mixtures, and the effects of other aggregate-related factors on critical mixtures. The laboratory testing involved three maximum aggregate sizes (19.0, 12.5, and 9.5 millimeters), three gradations (coarse, fine, and dense), and combinations of natural and manufactured coarse and fine aggregates. Specimens were compacted using the Superpave Gyratory Compactor (SGC), conventionally tested for bulk and maximum theoretical specific gravities and physically tested using the Nottingham Asphalt Tester (NAT) under a repeated load confined configuration to identify the transition state from sound to unsound. The statistical analysis involved using ANOVA and linear regression to examine the effects of identified aggregate factors on critical state transitions in asphalt paving mixtures and to develop predictive equations. The results clearly demonstrate that the volumetric conditions of an HMA mixture at the stable unstable threshold are influenced by a composite measure of the maximum aggregate size and gradation and by aggregate shape and texture. The currently defined VMA criterion, while significant, is seen to be insufficient by itself to correctly differentiate sound from unsound mixtures. Under current specifications, many otherwise sound mixtures are subject to rejection solely on the basis of failing to meet the VMA requirement. Based on the laboratory data and statistical analysis, a new paradigm to volumetric mix design is proposed that explicitly accounts for aggregate factors (gradation, shape, and texture).

hMMP9 as predictive factor for response and progression free survival in breast cancer patients treated with bevacizumab and pegylated liposomal doxorubicin (PLD)

Background: The anti-angiogenic drug, bevacizumab (Bv), is currently used in the treatment of different malignancies including breast cancer. Many angiogenesis-associated molecules are found in the circulation of cancer patients. Until now, there are no prognostic or predictive factors identified in breast cancer patients treated with Bv. We present here the first results of the prospective monitoring of 6 angiogenesis-related molecules in the peripheral blood of breast cancer patients treated with a combination of Bv and PLD in the phase II trial, SAKK 24/06. Methods: Patients were treated with PLD (20 mg/m2) and Bv (10 mg/kg) on days 1 and 15 of each 4-week cycle for a maximum of 6 cycles, followed by Bv monotherapy maintenance (10 mg/m2 q2 weeks) until progression or severe toxicity. Plasma and serum samples were collected at baseline, after 2 months of therapy, then every 3 months and at treatment discontinuation. Enzyme-linked immunosorbent assays (Quantikine, R&D Systems and Reliatech) were used to measure the expression levels of human vascular endothelial growth factor (hVEGF), placental growth factor (hPlGF), matrix metalloproteinase 9 (hMMP9) and soluble VEGF receptors hsVEGFR-1, hsVEGFR-2 and hsVEGFR-3. The log-transformed data (to reduce the skewness) for each marker was analyzed using an analysis of variance (ANOVA) model to determine if there was a difference between the mean of the subgroups of interest (where α = 0.05). The untransformed data was also analyzed in the same manner as a "sensitivity" check. Results: 132 blood samples were collected in 41 out of 43 enrolled patients. Baseline levels of the molecules were compared to disease status according to RECIST. There was a statistically significant difference in the mean of the log-transformed levels of hMMP9 between responders [CR+PR] versus the mean in patients with PD (p-value=0.0004, log fold change=0.7536), and between patients with disease control [CR+PR+SD] and those with PD (p-value=<0.0001, log fold change=0.81559), with the log-transformed level of hMMP9 being higher for the responder group. The mean of the log-transformed levels of hsVEGFR-1 was statistically significantly different between patients with disease control [CR+PR+SD] and those with PD (p-value=0.0068, log fold change=-0.6089), where the log-transformed level of hsVEGFR-1 was lower for the responder group. The log-transformed level of hMMP9 at baseline was identified as a significant prognostic factor in terms of progression free survival (PFS): p-value=0.0417, hazard ratio (HR)=0.574 with a corresponding 95% confidence interval (0.336 - 0.979)). No strong correlation was shown either between the log-transformed levels of hsVEGF, hPlGF, hsVEGFR-2 or hsVEGFR-3 and clinical response or the occurrence of severe toxicity, or between the levels of the different molecules. Conclusions: Our results suggest that baseline plasma level of the matrix metalloproteinase, hMMP9, could predict tumor response and PFS in patients treated with a combination of Bv and PLD. These data justify further investigation in breast cancer patients treated with anti-angiogenic therapy.

Relationships between microbial activity and soil physical and chemical properties in native and reforested Araucaria angustifolia forests in the state of São Paulo, Brazil

Araucaria angustifolia (Bert.) O. Kuntze is the main component of the Mixed Ombrophilous forest and, in the State of São Paulo, it is associated with a high diversity of soil organisms, essential for the maintenance of soil quality, making the conservation of this ecosystem a major and pressing challenge. The objective of this study was to identify the physical and chemical properties that are most closely correlated with dehydrogenase enzyme activity, basal respiration and microbial biomass under native (NF) and replanted (RF) Araucaria angustifolia forests in three regions of the state of São Paulo, in winter and summer. The main differentiating factors between the areas were also determined. Each forest was represented by three true replications; at each site, from around the araucaria trees, 15 soil samples (0-20 cm) were collected to evaluate the soil physical, chemical and microbiological properties. At the same points, forest litter was sampled to assess mass and chemical properties. The following microbiological properties were evaluated: microbial biomass carbon (MBC), basal respiration (CO2-C), metabolic quotient (Q: CO2), dehydrogenase enzyme activity (DHA) as well as the physical properties (moisture, bulk density, macroporosity and total porosity), soil chemical properties [pH, organic carbon (org-C), P, Ca, K, Mg, Al, H+Al], litter dry mass, and C, N and S contents. The data were subjected to analysis of variance (TWO-WAY: ANOVA). A Canonical Discriminant Analysis (CDA) and a Canonical Correlation Analysis (CCA) were also performed. In the soil under NF, the values of K, P, soil macroporosity, and litter dry mass were higher and Q: CO2 and DHA lower, regardless of the sampling period, and DHA was lower in winter. In the RF areas, the levels of moisture, porosity and Q: CO2 were higher in both sampling periods, and DHA was higher in winter. The MBC was only higher under NF in the summer, while the litter contents of C, N and S were greater in winter. In winter, CCA showed a high correlation of DHA with CO2-C, pH and H+Al, while in the summer org-C, moisture, Mg, pH and litter C were more associated with DHA and CO2-C. The CDA indicated H+Al, available P, total porosity, litter S content, and soil moisture as the most discriminating variables between NF and RF, but moisture was the most relevant, in both seasons and CO2-C only in winter. The combined analysis of CCA and CDA showed that the contribution of the microbiological variables to a differentiation of the areas was small at both samplings, which may indicate that the period after reforestation was long enough to allow an almost complete recovery of the microbial activity.

Nitrogênio, carbono e compactação do solo como fatores limitantes do processo de recuperação de matas ciliares

A recuperação de áreas de floresta, principalmente de matas ciliares, tornou-se fator-chave para a adequação ambiental da agricultura, com o propósito de proteger os recursos hídricos e a biota. Entretanto, o cultivo agrícola tradicional, além de ter alterado a ciclagem de nutrientes com a perda de matéria orgânica, biomassa e atividade microbiana, causou também a compactação do solo, o que influencia a posterior implantação de reflorestamentos. O objetivo deste trabalho foi identificar quais atributos do solo (físicos, químicos e microbiológicos) mais influenciam o teor de C, N, P e umidade da serapilheira em áreas de mata ciliar com diferentes idades de recuperação (20, 10 e cinco anos), em comparação com uma área nativa (NT). A partir da ANOVA e dos testes de médias (Duncan) e correlação (Pearson), foram verificados quais atributos acompanham o tempo de recuperação e qual a relação entre eles. A análise multivariada de partição da inércia a partir da análise de redundância (pRDA) foi feita a fim de identificar quais atributos do solo foram mais importantes para discriminar entre as áreas, com base nos teores de C, N, P e umidade da serapilheira encontrados nessas áreas. Maior relação C/N da serapilheira foi encontrada nas áreas de 20 (26,8) e de cinco (29,9) anos. Entre os atributos microbiológicos avaliados, observou-se que a respiração basal do solo (C-CO2), o carbono da biomassa microbiana (CBM) e a atividade das enzimas desidrogenase e urease foram diretamente proporcionais ao aumento da idade das áreas. O C e N totais do solo, o N-NO3, o nitrogênio da biomassa microbiana (NBM), a atividade das enzimas desidrogenase e urease, bem como a macroporosidade correlacionaram-se positivamente e a microporosidade, negativamente, com o C e N da serapilheira. A partir da pRDA, o NBM e o carbono total do solo foram os atributos mais importantes para explicar o teor de N e C da serapilheira; a explicação compartilhada foi mais da metade de toda a explicação observada ou 28,2 %. A melhoria das condições físicas do solo e a adição de matéria orgânica que resultam na formação de uma serapilheira mais rica em N pode ser uma forma de melhorar as condições microbiológicas e químicas do solo e de acelerar o processo de recuperação.

Pediatric CT: how to compare the Present DRL Values? : 12.10

Purpose: To determine dose thresholds, in term of CTDIvol, where subtle anatomical structures of pediatric CT images becomes no more detectable and compare them to the most recent Reference Dose Levels (DRL) proposed in the UK, Germany and Switzerland. Materials and methods: A GE LightSpeed-Ultra scanner (MSCT 8 slices) was used to perform chest and abdomen acquisitions on 8 patients (age range 2 to 16 years old) to provide a set of gold standard images. Dose reductions were then simulated by introducing image noise on raw data to provide simulated CT images with CTDIvol ranging from 2 to 22 mGy. All images were reviewed and scored independently by four experienced radiologists using the VGA methodology (Visual Grading Analysis) to determine the dose threshold where a significant loss of normal anatomy conspicuity appeared. Data were analyzed with ANOVA and Tukey HSD tests, a p >0.05 was considered to be significant. Results: No significant difference in VGA scoring appeared for CTDIvol leading to image noise levels lower than 10 and 25 HU for respectively abdominal and chest acquisitions. These data can thus be used to set the AEC (automatic exposure control) system of units having similar noise properties than the GE LightSpeed-Ultra used in this study. The present DRLs proposed for pediatric CT acquisitions are compatible with an excellent image quality level. Conclusion: The differences of DRL values proposed in Europe for pediatric acquisitions are marginal and assure a very good image quality level. The results of this study allow to further optimize the acquisition protocol by giving Noise Index value to set the AEC device.