Respective Coefficients Of Variation Research Articles

DRIS I: elaboración de los índices DRIS en el cultivo de palma de aceite

Nutritional diagnosis based on foliar tissue analysis is an efficient tool for detecting nutritional imbalances and aiding in the fertilizer recommendation process. Therefore, the objective of this study was to use this information to implement the Diagnosis and Recommendation Integrated System (DRIS), a method that uses the relationships between nutrients and their respective coefficients of variation in a high-productivity population, establishing the norms. In this study, DRIS norms and indices were developed for the oil palm crop, specifically the IRHO hybrid, in the central palm region of Colombia. A total of 113 samples were taken, of which 28 were considered representative of the population with high yields in fresh palm fruit production, exceeding 32.9 tons per hectare. The selection of DRIS norms was based on the criteria of the highest variance ratio and the "R" value criterion. The decreasing order of deficiency constraints for foliar tissue concentrations is Fe>Zn>S>P>Cl>Mg>B>Na>K>Ca>Cu=Mn>N, with Iron and Zinc being the limiting elements due to deficiency, and Nitrogen due to excess. Small changes in sulfur concentrations have a significant impact on yield.

Intra-observer reproducibility and inter-observer agreement of Fels skeletal age assessments among male tennis players 8–16 years

BackgroundSkeletal age (SA) is an estimate of biological maturity status that is commonly used in sport-related medical examinations. This study considered intra-observer reproducibility and inter-observer agreement of SA assessments among male tennis players.MethodsSA was assessed with the Fels method in 97 male tennis players with chronological ages (CA) spanning 8.7–16.8 years. Radiographs were evaluated by two independent trained observers. Based on the difference between SA and CA, players were classified as late, average or early maturing; if a player was skeletally mature, he was noted as such as an SA is not assigned.ResultsThe magnitude of intra-individual differences between repeated SA assessments were d = 0.008 year (observer A) and d = 0.001 year (observer B); the respective coefficients of variation were 1.11% and 1.75%. Inter-observer mean differences were negligible (t = 1.252, p = 0.210) and the intra-class correlation coefficient was nearly perfect (ICC = 0.995). Concordance of classifications of players by maturity status between observers was 90%.ConclusionFels SA assessments were highly reproducible and showed an acceptable level of inter-observer agreement between trained examiners. Classifications of players by skeletal maturity status based on assessments of the two observers were highly concordant, though not 100%. The results highlight the importance of experienced observers in skeletal maturity assessments.

The spread of rhizoctoniosis in potato plantings in the conditions of the North-West of the Russian Federation with a heterogeneous content of nutrients in the soil

Rhizoctoniosis is one of the most common and harmful diseases of potatoes in the North-West of Russia. The degree of its manifestation depends on many factors, including the content of basic nutrients in the soil. In the Leningrad region the effect of prolonged application of organic and mineral fertilizers on the degree and nature of the manifestation of rhizoctoniosis was studied in potato variety Meteor in forage and field crop rotations. By the results of the detailed accounting carried out in 2022 including observation of all potato plantings (43406 in total) it was determined that rhizoctoniosis damage had random distribution character in field crop rotation and focal distribution in forage crop rotation. This conclusion was confirmed by respective coefficients of variation (79 and 87 %) and aggregation (1.0 and 1.5). Spatial heterogeneity of plants damaged by rhizoctoniosis was visualized on digital maps compiled with GIS AFI and Surfer 11 while grouping the data into elementary sections. There was sufficient influence of cultivation and fertilization of different levels on rhizoctoniosis spread. The influence of cultivation was weak and statistically significant only in forage crop rotation, where there was an increase of rhizoctoniosis damage of potato plants (by 1.7-2.5 times compared to low cultivated soil). Under mineral fertilizers application there was a decrease of rhizoctoniosis damage of potato plants both in field crop rotation (by 1.1-1.7 times compared to variant without fertilizers application), and in forage crop rotation (by 1.1-1.3 times). Complex influence of soil cultivation and fertilization of potato plantings caused a decrease of rhizoctoniosis damage of potato tubers by 1.9 and 2.0 times in field and forage crop rotations, respectively.

Agricultural yield, food nutrition and dietary energy supply in Nigeria: Evidence from nationally representative data

Producing sufficient food to satisfy nutritional needs is imperative for building a prosperous society. This study examined trends in agricultural yields, water and sanitation services, and nutrition indices in Nigeria. Secondary data from the FAO-FAOSTAT (2000–2020) were utilized and analyzed using descriptive statistics, the respective coefficients of variation and determination, the Mann-Kendall trend test, the Pearson correlation and multivariate regression for statistical inferences. The results show trends for data on several variables. GDP per capita and population numbers were positively correlated with the number of children under five years of age who were stunted, and the proportion of population and number of people using safely managed and at least basic drinking water and sanitation services. A major result was the significant positive relationship between cassava yield and number of children under five who were stunted. Also, there was the negative influence of population numbers on cassava and maize yields. If not attended to, the outcomes of these relationships are expected to exacerbate nutrition insecurity and stunting in children under five. An improvement in the national indices on agricultural yields and nutrition security is imperative for the accelerated attainment by 2030 of the national nutrition security targets and the SDGs.

Sexual dimorphism in morphological characteristics of two Nigerian indigenous goat breeds

Themorphological traits of 594 indigenous goats comprised of 316 and 279 Red Sokoto goat (RSG) and West African dwarf (WAD) goats, respectively, were measured to determine the presence or otherwise of sexual dimorphism in the morphological characteristics of the two indigenous goats. The morphological traitsmeasured were body length (BL), withers height (WH), rumps height (RH), heart girth (HG), body depth (BD), tail length (TL), head length (HL), head width (HW), ear length (EL), and horn length (HL). Also recorded were body weight (BW) and sex of each animal.The data collected were analysed using descriptive statistics and analysis of variance of fixed effect of sex on themorphological characteristics. The result revealed the presence of marked sexual dimorphism in morphological characteristics of both the RSG and WAD goats. The adult females were significantly (P< 0.05-0.01) heavier and larger in size than the males. The respective coefficients of variation (CV) between breeds were high in most of the morphological traits suggesting high heterogeneity, an indication of the amount of opportunity available for improving the breeds through selection.

Three-dimensional US for Quantification of Volumetric Blood Flow: Multisite Multisystem Results from within the Quantitative Imaging Biomarkers Alliance.

Background Quantitative blood flow (QBF) measurements that use pulsed-wave US rely on difficult-to-meet conditions. Imaging biomarkers need to be quantitative and user and machine independent. Surrogate markers (eg, resistive index) fail to quantify actual volumetric flow. Standardization is possible, but relies on collaboration between users, manufacturers, and the U.S. Food and Drug Administration. Purpose To evaluate a Quantitative Imaging Biomarkers Alliance-supported, user- and machine-independent US method for quantitatively measuring QBF. Materials and Methods In this prospective study (March 2017 to March 2019), three different clinical US scanners were used to benchmark QBF in a calibrated flow phantom at three different laboratories each. Testing conditions involved changes in flow rate (1-12 mL/sec), imaging depth (2.5-7 cm), color flow gain (0%-100%), and flow past a stenosis. Each condition was performed under constant and pulsatile flow at 60 beats per minute, thus yielding eight distinct testing conditions. QBF was computed from three-dimensional color flow velocity, power, and scan geometry by using Gauss theorem. Statistical analysis was performed between systems and between laboratories. Systems and laboratories were anonymized when reporting results. Results For systems 1, 2, and 3, flow rate for constant and pulsatile flow was measured, respectively, with biases of 3.5% and 24.9%, 3.0% and 2.1%, and -22.1% and -10.9%. Coefficients of variation were 6.9% and 7.7%, 3.3% and 8.2%, and 9.6% and 17.3%, respectively. For changes in imaging depth, biases were 3.7% and 27.2%, -2.0% and -0.9%, and -22.8% and -5.9%, respectively. Respective coefficients of variation were 10.0% and 9.2%, 4.6% and 6.9%, and 10.1% and 11.6%. For changes in color flow gain, biases after filling the lumen with color pixels were 6.3% and 18.5%, 8.5% and 9.0%, and 16.6% and 6.2%, respectively. Respective coefficients of variation were 10.8% and 4.3%, 7.3% and 6.7%, and 6.7% and 5.3%. Poststenotic flow biases were 1.8% and 31.2%, 5.7% and -3.1%, and -18.3% and -18.2%, respectively. Conclusion Interlaboratory bias and variation of US-derived quantitative blood flow indicated its potential to become a clinical biomarker for the blood supply to end organs. © RSNA, 2020 Online supplemental material is available for this article. See also the editorial by Forsberg in this issue.

Bearing Capacity of Transversely Prestressed Concrete Deck Slabs

The Netherlands has a large number of thin, transversely prestressed concrete bridge decks, cast in-situ between flanges of prestressed concrete girders dating back to the 1960s and 1970s. These bridges are critical in shear when analyzed using EN 1992-1-1:2005; however, in reality, they show no significant signs of distress, possibly because of residual bearing (punching shear) capacity arising from compressive membrane action. Since these bridges are old, it is an astute approach to check whether they can be used for a few more decades, provided they are safe and reliable against modern traffic loads. The results could then be applied to a wider range of structures, especially in developing countries facing economic constraints. A prototype bridge was selected and experimental, numerical and theoretical approaches were used to investigate its bearing capacity. Respective coefficients of variation of 11% and 9% were obtained when the experimental and the finite element analysis punching loads were compared with the theoretical results. This led to the conclusion that the existing transversely prestressed concrete bridge decks still have sufficient bearing capacity and considerable cost savings can be made if compressive membrane action is considered in the analysis.

Precision of Optic Nerve Head and Retinal Nerve Fiber Layer Parameter Measurements by Spectral-domain Optical Coherence Tomography.

The aim of this study was to assess the repeatability and reproducibility (R&R) of Bruch membrane opening based on minimum rim width (BMO-MRW), minimum rim area (BMO-MRA) and peripapillary retinal nerve fiber layer thickness (RNFLT) with the Spectralis optical coherence tomography (Heidelberg Engineering) for normal and glaucoma subjects. Precise measurement of these parameters can support detection of structural glaucomatous damage and progression. This cross-sectional study included 16 healthy controls and 16 patients with glaucoma. One eye was randomly selected and included in this study. Subjects underwent 1 baseline and 3 follow-up measurements, using 3 different Spectralis optical coherence tomography devices in randomized order, each operated by a single operator. Outcome measures were global and sectorial averages of BMO-MRW and BMO-MRA, and of peripapillary RNFLT obtained from 12/14/16-degree circle scans. Coefficients of variation (COV) were calculated and a mixed-effects analysis of variance was performed to compare R&R between devices. COVs of global and sectorial BMO-MRW measurement under repeatability conditions ranged from 0.51% to 1.7% (normal, 0.62% to 1.3%; glaucoma, 0.64% to 2.3%). Respective COVs under reproducibility conditions ranged from 0.89% to 1.9% (normal, 0.77% to 2.8%; glaucoma, 1.1% to 2.6%). COVs of global and sectorial RNFLT measurements under repeatability conditions ranged from 0.5% to 2.8%. Respective COVs under reproducibility conditions ranged from 1.6% to 3.5%. For R&R, the COVs of measured parameters were by trend higher for glaucoma eyes compared with normal controls. The BMO-MRW measurement system has an excellent precision taking into account that major and minor corrections of segmentation have to be done by the examiner before evaluation.

Rainfall and Temperature in the Limpopo River Basin, Southern Africa: Means, Variations, and Trends from 1979 to 2013

Understanding temporal and spatial characteristics of regional climate is essential for decision making in water resource management. Established statistical and GIS techniques were used to evaluate annual and seasonal variations of rainfall and temperature in time and space from 1979 to 2013 in the Limpopo River Basin (LRB). Annual means of rainfall in the LRB varied between 160 and 1109 mm, generally from west to east of the basin during the study period. Annual minimum and maximum temperature ranged from 8 °C in the south to 20 °C in the east of the basin, and 23 °C in the south of the basin to 32 °C in the east. The respective coefficients of variation (CVs) of these variables showed an inverse pattern to the annual values, with rainfall having high CV values (28% to 70% from east to west of the basin) compared to temperature CV values. Seasonal variations followed similar patterns as annual variations for the individual variables examined. Trend analysis showed upward trends for both annual and seasonal rainfall in most parts of the basin, except for the winter season which showed a decreasing trend. Analysis of minimum temperature on an annual basis and for the winter season and spring season shows upward trends during the study period over the whole basin while minimum temperature for summer and autumn showed decreasing trends. Maximum temperature, by contrast, showed decreasing trends on an annual, summer, autumn, and spring basis but an increasing trend for winter during the study period in most parts of the basin.

3B.02

Objective: Some studies suggested that ambulatory blood pressure (ABP) variability may provide useful information beyond that of average ABP levels. This study investigated the relationship between central ABP variability and target-organ damage in young individuals in whom the central-peripheral blood pressure discrepancy might be considerable. Design and method: Apparently healthy adolescents and young adults referred for elevated blood pressure and healthy volunteers (age 12–26 years) were subjected to: (i) 24-hour monitoring of central ABP using a noninvasive brachial cuff-based oscillometric device (Mobil-O-Graph 24 h PWA); (ii) 24-hour pulse wave velocity (PWV) monitoring (Mobil-O-Graph 24 h PWA); (iii) echocardiographic determination of left ventricular mass index (LVMI); (iv) measurement (ultrasonography) of the common carotid intima-media thickness (IMT). The standard deviation (SD) of ABP (24-hour weighted/awake/asleep), as well as the respective coefficients of variation (CV) were used for assessing variability. Results: The study included 68 individuals (mean age 18.7 ± 4.7 years, 52 males, body mass index [BMI] 24.5 ± 4.7 kg/m2, 24 volunteers, 15 with hypertension [24-hour peripheral ABP >=95th percentile for adolescents or >=130/80 mmHg for adults]). LVMI was correlated with 24-hour/awake/asleep central systolic ABP (r=0.50/0.49/0.40, all p < 0.01), as well as with 24-hour weighted/awake/asleep SD of central systolic ABP (r = 0.40/0.37/0.30, all p < 0.05), whereas no association was observed for the respective CV. IMT was correlated with 24-hour/awake/asleep central pulse pressure (PP) (r = 0.37/0.33/0.27, all p < 0.05), 24-hour weighted/awake/asleep SD of central PP (r = 0.43/0.40/0.36, all p < 0.01) and the respective CV (r = 0.28/0.26/0.25, all p < 0.05). Regarding 24-hour PWV, there was a significant association with 24-hour/awake/asleep central systolic ABP (r = 0.94/0.88/0.84, all p < 0.001) and 24-hour weighted/awake/asleep SD of central PP (r = 0.48/0.51/0.25, all p < 0.05), but not with the respective CV. In multivariate regression analyses (independent variables: age, gender, BMI, central ABP and SD/CV of ABP values), LVMI and 24-hour PWV were determined by BMI, age, and 24-hour central systolic ABP, and IMT by male gender and 24-hour weighted SD of central PP. Conclusions: In young individuals, 24-hour central ABP variability appears to be associated only with early carotid damage when accounting for ABP levels, whereas LVMI and PWV are mainly determined by average ABP levels.

Using a postcolumn-infused internal standard for correcting the matrix effects of urine specimens in liquid chromatography–electrospray ionization mass spectrometry

Matrix effects (MEs) are a major problem affecting the quantitative accuracy of liquid chromatography–electrospray ionization mass spectrometry (LC–ESI-MS) when analyzing complicated samples. While analyzing urine specimens, the wide diversity of endogenous materials and different urine concentrations may result in inaccurate quantification. In this study, we propose a postcolumn-infused internal standard (PCI-IS) strategy for universal correction of MEs in urine specimens. MEs can be effectively corrected by dividing the target analyte signal intensity by the PCI-IS intensity. To evaluate the performance of PCI-IS, we used 6 benzodiazepine (BZD) drugs in 5 different concentrations of urine matrixes as a test model. The divergence of the BZD drug signal responses in 5 different urine matrixes was expressed using their respective coefficients of variation (CV) to evaluate the efficiency of using PCI-IS in correcting matrix effects. The CV of the BZD drug signal intensities in these 5 different concentrations of the urine matrixes were reduced from 10 to 30% to less than 10% when the PCI-IS correction method was employed. When the PCI-IS method was used to correct the 6 BZDs in 25 real human urine samples, over 90% of the test results exhibited quantification errors of less than 20%, and all of the test results had quantification errors of less than 30%. These results demonstrate that the PCI-IS method can resolve the problem of inaccurate quantification that arises from the diversity of urine specimens. The PCI-IS method is particularly useful for clinical analysis or forensic toxicology to improve the quantification accuracy in an economical way.

Aluminum-based winter wheat biomass and grain yield spatial variability in arable soils: concept and field test

The paper outlines a concept related to selecting a site for experimental purposes. Selection of an experimental plot most frequently relies on performing visual evaluation of a given site, followed by the establishment of a field trial. In general, the question of geochemical variability is ‘intentionally’ postponed! Verification of this approach has been undertaken, testing such parameters as soil pH and exchangeable aluminum (Alex) versus spatial (investigated area, 12 672 m2) and downward (sampling depths, i.e., 0-20, 20-40 and 40-60 cm) distribution. Winter wheat biomass at tillering (BBCH29) and grain yield at harvest (BBCH99) were additionally considered. The results have revealed that pH values fluctuated between 3.6 and 4.4 with respective coefficients of variation (CV) ranging from 3.10 to 5.92%. The concentrations of Alex ranged from 38.0 to 144.9 mg kg –1, corresponding to CV within 28.34 and 44.03%. The variograms and geostatistical maps have demonstrated the spatial as well as downward variability of these parameters. The spatial distribution of plant biomass followed quite closely the exchangeable aluminum (Alex) levels, which implies that natural soil parameters such as Alex are not easily compensated for by agricultural practices, for instance nitrogen application. The spatial grain yield – Alex dependence which emerged at harvest confirmed the variability observed at tillering (BBCH29). Thus, the spatial variability of pH, Alex and wheat biomass as well as grain yields (BBCH99) verified the approach to selecting an experimental site. It was demonstrated that selection of a research site on the basis of its appearance and shape alone may lead to misinterpretation of experimental results.

Assessment of methods for prediction of notch and size effects at the fatigue limit based on test data by Böhm and Magin

A variety of methods are available for the assessment of notch and size effects in fatigue. The purpose of the present investigation is to rank such methods according to their predictive capability. Smooth and notched fatigue limits for 26 different specimen geometries investigated by Böhm and Magin serve as a basis for this ranking. The quality of predictions is expressed in terms of their respective coefficients of variation, COV, for the 26 specimen geometries. COV is 16% for the peak-stress approach and ranges from 12% to 10% for the theories of Peterson, Neuber and critical distances. The stress gradient, the weakest-link and the highly-stressed-volume (V90) theories yield the best predictions with COV in the range from 8% to 6%.

Factorial and Doehlert Design Used as Optimization Procedures for the Direct Determination of Lead in Whole Blood Samples by Graphite Furnace Atomic Absorption Spectrometry

In this work, the direct determination of lead in whole blood samples by graphite furnace atomic absorption spectrometry is proposed. The samples were diluted 1:9 with HNO3 and Triton® X-100, both 0.2% v/v. Multivariate optimization was made to evaluate the pyrolysis and atomization temperatures and the use of a chemical modifier. The method allowed lead determination with a curve ranging from 0 to 6.0 μg dL−1. Recovery studies presented results from 88 to 109%. The LOD and the characteristic mass were 0.21 μg dL−1 and 7.4 pg, respectively. Intra- and inter-assay studies showed respective coefficients of variation of 4.2 and 8.9%.

Variability of selected trace elements of different meat cuts determined by ICP-MS and DRC-ICPMS

The aim of this study was to determine the levels of cadmium, lead, iron, zinc, selenium, manganese, copper and molybdenum in different cuts of beef, pork, lamb, chicken and foal collected from supermarkets and butcheries in Switzerland. The concentrations of manganese, copper, molybdenum, zinc, iron, selenium, cadmium and lead were determined by inductively coupled plasma mass spectrometry (ICP-MS) after microwave digestion. Mean values and their respective coefficients of variation were calculated from the measured concentrations. The concentrations found for cadmium and lead ranged from 0.6 to 3.9 μg/100 g and 1.0 to 2.1 μg/100 g, respectively. Concentrations ranged between 0.5 and 3.3 mg/100 g for iron, 0.7 and 5.1 mg/100 g for zinc, 9 and 44 μg/100 g for selenium, 3.1 and 16.7 μg/100 g for manganese, 0.3 and 132 μg/100 g for copper and 0.9 and 3.2 μg/100 g for molybdenum. Differences found for the concentrations in meat from different species as well as between the individual meat cuts were notable for iron, zinc, selenium and copper. Manganese concentrations were found to vary unsystematically within muscles and species. Molybdenum concentrations were higher in chicken meat in comparison with the mammalian meats. The highest coefficients of variation were found for manganese (13% to 142%) and copper (13% to 224%), while the lowest was found for zinc (4% to 45%). In conclusion, in order to provide an accurate overview and to be able to calculate reliable dietary intakes, it is important to include the variability in food composition data.

A simple spectrophotometric method for the determination of methyldopa using p-chloranil in the presence of Hydrogen Peroxide

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of methyldopa in pharmaceutical formulations. The method is based on the reaction between tetrachloro-p-benzoquinone (p-chloranil) and methyldopa, accelerated by hydrogen peroxide (H2O2), producing a violet-red compound (λmax = 535 nm) at ambient temperature (25.0 ± 0.2 0C). Experimental design methodologies were used to optimize the measurement conditions. Beer’s law is obeyed in a concentration range from 2.10 x 10-4 to 2.48 x 10-3 mol L-1 (r = 0.9997). The limit of detection was 7.55 x 10-6 mol L-1 and the limit of quantification was 2.52 x 10-5 mol L-1. The intraday precision and interday precision were studied for 10 replicate analyses of 1.59 x 10-3 mol L-1 methyldopa solution and the respective coefficients of variation were 0.7 and 1.1 %. The proposed method was successfully applied to the determination of methyldopa in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in the formulations. The results obtained by the proposed method were favorably compared with those given by the Brazilian Pharmacopoeia procedure at 95 % confidence level.

A simple spectrophotometric method for the determination of methyldopa using p-chloranil in the presence of hydrogen peroxide

A simple, rapid and sensitive spectrophotometric method has been developed for the determination of methyldopa in pharmaceutical formulations. The method is based on the reaction between tetrachloro-p-benzoquinone (p-chloranil) and methyldopa, accelerated by hydrogen peroxide (H2O2), producing a violet-red compound (λmax = 535 nm) at ambient temperature (25.0 ± 0.2 ºC). Experimental design methodologies were used to optimize the measurement conditions. Beer's law is obeyed in a concentration range from 2.10 x 10-4 to 2.48 x 10-3 mol L-1 (r = 0.9997). The limit of detection was 7.55 x 10-6 mol L-1 and the limit of quantification was 2.52 x 10-5 mol L-1. The intraday precision and interday precision were studied for 10 replicate analyses of 1.59 x 10-3 mol L-1 methyldopa solution and the respective coefficients of variation were 0.7 and 1.1 %. The proposed method was successfully applied to the determination of methyldopa in commercial brands of pharmaceuticals. No interferences were observed from the common excipients in the formulations. The results obtained by the proposed method were favorably compared with those given by the Brazilian Pharmacopoeia procedure at 95 % confidence level.

Determinação do período de coleta total de excretas para estimativa dos valores de energia metabolizável em frangos de corte

O efeito do período de coleta total das excretas na estimativa da energia metabolizável [aparente (EMA) e corrigida para nitrogênio retido (EMAn)] foi avaliado em frangos de corte de 19 a 23 dias de idade. O delineamento experimental foi composto de cinco tratamentos (1, 2, 3, 4 e 5 dias de coleta total de excretas), com seis repetições, em blocos casualizados, totalizando 300 pintos de corte para a ração-teste e 300 para a ração-referência. A ração-teste foi obtida pela substituição de 40% da ração-referência por milho. Depois de quatro dias para adaptação dos frangos, iniciou-se a coleta das excretas por períodos de 1, 2, 3, 4 ou 5 dias subseqüentes, o que constituiu os tratamentos. Os dados foram avaliados por meio de análise de variância, pelo procedimento GLM do SAS (2001), e as médias foram comparadas pelo teste Tukey. Os valores médios de energia metabolizável para o milho, com base na matéria natural, nos períodos de coleta de 1, 2, 3, 4 e 5 dias, com seus respectivos coeficientes de variação (%), para EMA (kcal/kg) foram 3.814 (7,26), 3.511 (5,32), 3.563 (2,51), 3.512 (1,31) e 3.489 (1,00) e, para EMAn (kcal/kg), 3.709 (6,68), 3.434 (4,85), 3.482 (2,31), 3.438 (1,11) e 3.423 (1,03), respectivamente. O período de coleta total de excretas de quatro dias é suficiente para gerar dados de EM do milho de igual confiabilidade aos apresentados com cinco dias.

On the use of soil hydraulic conductivity functions in the field

The estimation of soil water fluxes using the Darcy–Buckingham flux-gradient approach is, after a century of use, still problematic under field conditions. Two features of the soil hydraulic conductivity ( K) function are the main causes of failure, first the exponential character of the K versus soil water content ( θ) relations, which lead to large variations in K for minimal variations of θ. Due to this, the level of precision of field measurements of θ and the spatial variability of θ itself, make the deterministic estimation of soil water fluxes unfeasible using this approach. Secondly, the spatial variability of the parameters of the K( θ) relations also contribute heavily to errors in soil water flux estimation from site to site. In a coffee crop water balance experiment, soil water fluxes below the root zone were estimated over one year, comparing the use of a soil hydraulic conductivity function obtained in the field, with an indirect climatologic approach in which the deep drainage is estimated from a water balance excess. Five replicates gave the possibility of calculating variances of both forms of calculation and their respective coefficients of variation (CV). Results show that CVs of the estimates made through the Darcy–Buckingham approach varied from 78 to 122%, in comparison to 8–23 for the indirect climatologic approach. It is therefore concluded that Darcy–Buckingham approach used deterministically under field conditions does not yield consistent results.

Simultaneous determination of zonisamide, carbamazepine and carbamazepine-10,11-epoxide in infant serum by high-performance liquid chromatography

This study developed a simple method for the simultaneous determination of zonisamide (ZNS), carbamazepine (CBZ) and its active metabolite, carbamazepine-10,11-epoxide (CBZE) in infant serum using reversed-phase high-performance liquid chromatograph (HPLC). The method involves a single-step protein precipitation procedure that uses no solid-phase or liquid–liquid extraction. The HPLC separation was carried out on a Cadenza CD-C18 column (3 μm, 4.6 mm × 150 mm) with potassium phosphate buffer (pH 4.6; 25 mM)–methanol–acetonitrile (65:20:15 (v/v/v)) as a mobile phase at a 1.0 ml/min flow rate: ZNS was detectable using a UV detector at 235 nm, and both CBZ and CBZE were at 215 nm. The quantification limits were established in accordance with each therapeutic range at 2.5 μg/ml for ZNS, 0.5 μg/ml for CBZ, and 0.25 μg/ml for CBZE. The respective coefficients of variation were 1.3–6.0% and 2.2–7.7% for the intra- and inter-assay.