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The increase in urban runoff brought about by a rise in impermeable surfaces has triggered the alteration and pollution of many aquatic systems. The overall goal of this research was to design a 'Sustainable Urban Drainage System' (SUDS) for the retention of heavy metals from a car park consisting of mixing autochthonous soil (70%) with sand (30%) to improve the hydrological conductivity and adsorption capacity. To quantify the retention of metals we characterize the adsorption kinetics and isotherms of the soil mixture and perform dynamic experiments. The proposed methodology allowed us to work out the amount of heavy metal retention by the adsorbent and the retention mechanisms. The retention capacity of the adsorbent mixture was as follows: Cr3+ ≈ Cu2+ ≫ Zn2+ > Ni2+ > Cd2+. Chromium and copper ions were mainly retained by precipitation, whereas zinc, nickel and cadmium were retained by ionic exchange with calcium ions that saturate the soil colloids. The soil mixture buffered pH was found to change when fed with an acid solution of metallic ions.

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Cercopithifilaria bainae is a nematode belonging to the family Onchocercidae that parasitizes the subcutaneous tissue of dogs. Its transmission occurs through the tick Rhipicephalus sanguineus and its geographical distribution overlaps that of this vector. The present study reports the detection of microfilaremia by C. bainae in an eight-year-old male dog that presented anorexia, hyperthermia, motor incoordination, mydriasis, a nodule in the left testicle and concomitant infection by Ehrlichia sp. Blood samples were analyzed using microscopy, PCR and DNA sequencing. Microfilariae measuring 150±5.5µm in length and 7±1.8µm in width were retrieved. The DNA sequence exhibited 98% identity with C. bainae sequences available in Genbank. This is the first report of microfilaremia by C. bainae in a dog in the central western region of Brazil.(AU)

Cercopithifilaria bainae é um nematoide pertencente à família Onchocercidae, que parasita o tecido subcutâneo de cães. Sua transmissão ocorre pelo carrapato Rhipicephalus sanguineus, e sua distribuição geográfica se sobrepõe ao espalhamento desse vetor. O presente estudo relata a detecção de microfilaremia por C. bainae em um cão macho de oito anos que apresentava anorexia, hipertermia, incoordenação motora, midríase e nódulo no testículo esquerdo e infecção concomitante por Ehrlichia sp. A coleta de sangue foi realizada, e o material analisado por meio dos exames de microscopia, PCR e sequenciamento de DNA. Microfilárias medindo 150±5,5µm de comprimento e 7±1,8µm de largura foram recuperadas. A sequência de DNA obtida mostrou 98% de identidade com sequências de C. bainae disponíveis no Genbank. Este é o primeiro relato de microfilaremia de C. bainae em um cão na região Centro-Oeste do Brasil.(AU)

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Ehrlichia infections in cattle are frequent in Africa but have also been reported in Brazil and North America. This paper reports natural infection by Ehrlichia sp. associated with Babesia bigemina and Anaplasma marginale in a calf in the municipality of Campo Grande, state of Mato Grosso do Sul, Brazil, presenting polioencephalomalacia. The molecular evidence, based on a fragment of the dsb gene, indicates a species of Ehrlichia genetically related to Ehrlichia canis and other species of the genus found in the tick Rhipicephalus (Boophilus) microplus and a calf from Brazil (99 to 100% identity). It was not possible to associate the clinical signs with Ehrlichia infection due to co-infections and histological evidence of another disease. However, the circulation of the bacteria in bovines in Brazilian Cerrado was confirmed and more attention should be given to clinical suspicion of tick-borne pathogens in cattle to clarify the pathogenic potential of Ehrlichia sp.(AU)

Infecções por Ehrlichia em bovinos são frequentes na África, mas também foram relatadas no Brasil e na América do Norte. Este artigo relata uma infecção natural por Ehrlichia sp. associado a Babesia bigemina e Anaplasma marginale em um bezerro, no município de Campo Grande, Mato Grosso do Sul, Brasil, o qual apresentava polioencefalomalácia. A evidência molecular, baseada em um fragmento do gene dsb, indica uma espécie de Ehrlichia geneticamente relacionada a Ehrlichia canis e outras espécies do gênero encontradas no carrapato Rhipicephalus (Boophilus) microplus e em um bezerro do Brasil (99 a 100% de identidade). Não foi possível associar os sinais clínicos à infecção por Ehrlichia devido a coinfecções e evidências histológicas de outra doença. No entanto, a circulação da bactéria em bovinos no Cerrado brasileiro foi confirmada, e mais atenção deve ser dada à suspeita clínica de patógenos transmitidos por carrapatos em bovinos para esclarecer o potencial patogênico de Ehrlichia sp.(AU)

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The kinetics of several representative hybrid precursors were studied via 29Si NMR: three alkyl precursors, methyltriethoxysilane, ethyltriethoxysilane, and propyltriethoxysilane; as well as two unsaturated radicals, vinyltriethoxysilane and phenyltriethoxysilane. The reaction rate is related to the chemical shift of 29Si in the NMR spectra, which gives information about the electronic density of the Si atoms and the inductive effects of substituents. The concentration of the precursors decreased exponentially with time, and the intermediate products of hydrolysis and the beginning of the condensation reactions showed curves characteristic of sequential reactions, with a similar distribution of the species as a function of the fractional conversion. For all of the precursors, condensation started when the most hydrolyzed species reached a maximum concentration of 0.30 M, when the precursor had run out. A prediction following the developed mathematical model fits the experimental results in line with a common pathway described by eight parameters.

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There are different magnetic resonance techniques and models to quantify liver iron concentration. T2 relaxometry methods evaluate the iron concentration in the myocardium, and they are able to discriminate all the levels of iron overload in the liver. Signal intensity ratio methods saturate with high levels of liver overload and can not assess iron concentration in the myocardium but they are more accessible and are very standardized. This article reviews, in different clinical scenarios, when Magnetic Resonance must be used to assess iron overload in the liver and myocardium and analyzes the current challenges to optimize the aplication of the technique and to be it included in the clinical guidelines.

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A range of artificial molecular systems has been created that can exhibit controlled linear and rotational motion. In the further development of such systems, a key step is the addition of communication between molecules in a network. Here, we show that a two-dimensional array of dipolar molecular rotors can undergo simultaneous rotational switching when applying an electric field from the tip of a scanning tunnelling microscope. Several hundred rotors made from porphyrin-based double-decker complexes can be simultaneously rotated when in a hexagonal rotor network on a Cu(111) surface by applying biases above 1 V at 80 K. The phenomenon is observed only in a hexagonal rotor network due to the degeneracy of the ground-state dipole rotational energy barrier of the system. Defects are essential to increase electric torque on the rotor network and to stabilize the switched rotor domains. At low biases and low initial rotator angles, slight reorientations of individual rotors can occur, resulting in the rotator arms pointing in different directions. Analysis reveals that the rotator arm directions are not random, but are coordinated to minimize energy via crosstalk among the rotors through dipolar interactions.

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We evaluated the effect of different treatment protocols against gastrointestinal nematodes in Nelore beef cattle during the growing phase in the municipality of Terenos, MS, in central Brazil from May 2013 to April 2014 and from May 2014 to April 2015. Ninety-six Nelore calves were kept on Brachiaria brizantha grass during each trial period and were distributed into six experimental groups (replicate paddocks for each group) based on live weight and the number of eggs per gram of feces (EPG): T1 (control)-treated in May, July and September with a saline solution; T2-treated in May and November with 700 µg/kg doramectin; T3-treated in May (doramectin), July (4.7 mg/kg levamisole phosphate) and September (doramectin); T4-treated in May (doramectin), July (200 µg/kg moxidectin) and September (doramectin); T5-treated in May (doramectin), August (levamisole phosphate) and November (doramectin) and T6-treated in May (doramectin), August (moxidectin) and November (doramectin). The calves were weighed and feces were collected (for faecal culture and EPG counts) from calves every 28 days, concomitantly with the collection of forage samples. The efficacies of doramectin, moxidectin and levamisole were low, at 69.2, 65.9 and 69.4% in the first and 13.8, 92.6, and 76.5% in the second experimental periods, respectively, but only the untreated animals lost weight during the dry season. Final weight gains did not differ significantly (p>0.05) among the animals in T2 (120.8 kg), T3 (131.4 kg), T4 (131.2 kg) and T5 (134.4 kg). T6 was the only group with a significantly higher final weight gain (140.9 kg) compared to the protocol with two annual dosages (T2). The weight gain was 31.9% higher in T6 than in the untreated animals (T1). None of the protocols affected the number of larvae on the pasture. Body weight was significantly and negatively (r=-0.65) correlated with EPG counts, which were significantly lower in June (T2, T3, T4 and T6), August (T3), September (T5 and T6), October (T5) and November (T5 and T6). Haemonchus, Cooperia, Trichostrongylus and Oesophagostomum were identified. Treatments in May and November, the most common practice in Brazil, did not increase the final weight gain, so an additional and intermediate treatment during the dry season (August) is recommended.

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BACKGROUND: The autonomic behavior of growth-restricted fetuses at different evolving hemodynamic stages has not been fully elicited. AIM: To analyze the respiratory sinus arrhythmia (RSA) of growth-restricted fetuses that despite this severe condition show normal Doppler hemodynamics. SUBJECTS: 10 growth-restricted fetuses (FGR group) with normal arterial pulsatility indices (umbilical, uterine, middle cerebral, ductus venosus and aortic isthmus), and 10 healthy fetuses (Control group), 32-37weeks of gestation. METHOD: B-mode ultrasound images for visualizing fetal breathing movements (FBM) or breathing akinesis (FBA), and the simultaneous RR-interval time series from maternal abdominal ECG recordings were obtained. The root-mean-square of successive differences of RR-intervals (RMSSD) was considered as a RSA-related parameter among the instantaneous amplitude of the high-frequency component (AMPHF) and its corresponding instantaneous frequency (IFHF), both computed by using empirical mode decomposition. Mean fetal heart-periods and RSA-related parameters were assessed during episodes of FBM and FBA in 30s length windows. RESULTS: FGR and Control groups presented RSA-related fluctuations during FBM and FBA. Also, both groups showed significant higher (p<0.001) values for the mean heart-period, RMSSD and AMPHF during FBM. No-significant differences (p>0.05) were found for the IFHF regardless of breathing activity (FBM vs. FBA). CONCLUSION: Growth-restricted fetuses without evident hemodynamic compromise exhibit a preserved autonomic cardiovascular regulation, characterized by higher values of RSA and mean heart-period in the presence of FBM. This physiological response reflects a compensatory strategy that may contribute to preserve blood flow redistribution to vital organs.

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Neither breakpoints (BPs) nor epidemiological cutoff values (ECVs) have been established for Candida spp. with anidulafungin, caspofungin, and micafungin when using the Sensititre YeastOne (SYO) broth dilution colorimetric method. In addition, reference caspofungin MICs have so far proven to be unreliable. Candida species wild-type (WT) MIC distributions (for microorganisms in a species/drug combination with no detectable phenotypic resistance) were established for 6,007 Candida albicans, 186 C. dubliniensis, 3,188 C. glabrata complex, 119 C. guilliermondii, 493 C. krusei, 205 C. lusitaniae, 3,136 C. parapsilosis complex, and 1,016 C. tropicalis isolates. SYO MIC data gathered from 38 laboratories in Australia, Canada, Europe, Mexico, New Zealand, South Africa, and the United States were pooled to statistically define SYO ECVs. ECVs for anidulafungin, caspofungin, and micafungin encompassing ≥97.5% of the statistically modeled population were, respectively, 0.12, 0.25, and 0.06 µg/ml for C. albicans, 0.12, 0.25, and 0.03 µg/ml for C. glabrata complex, 4, 2, and 4 µg/ml for C. parapsilosis complex, 0.5, 0.25, and 0.06 µg/ml for C. tropicalis, 0.25, 1, and 0.25 µg/ml for C. krusei, 0.25, 1, and 0.12 µg/ml for C. lusitaniae, 4, 2, and 2 µg/ml for C. guilliermondii, and 0.25, 0.25, and 0.12 µg/ml for C. dubliniensis. Species-specific SYO ECVs for anidulafungin, caspofungin, and micafungin correctly classified 72 (88.9%), 74 (91.4%), 76 (93.8%), respectively, of 81 Candida isolates with identified fks mutations. SYO ECVs may aid in detecting non-WT isolates with reduced susceptibility to anidulafungin, micafungin, and especially caspofungin, since testing the susceptibilities of Candida spp. to caspofungin by reference methodologies is not recommended.

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Objetivo. Valorar la sobrecarga férrica mediante el cálculo del valor T2* en el hígado y el miocardio en los pacientes con hemocromatosis secundaria. Evaluar la correlación de los valores obtenidos con los niveles de ferritina en sangre y la concentración de hierro hepático (CHH) calculada mediante resonancia magnética (RM), y la correlación de los valores T2* entre sí. Material y métodos. Se incluyeron 16 pacientes (13 varones y 3 mujeres), evaluados entre los años 2008 y 2009, con una edad media de 61 años. Quince eran pacientes politransfundidos y uno estaba diagnosticado de anemia sideroblástica hereditaria. Se estudió la ferritina en sangre, la CHH por RM, la función cardíaca mediante RM y el valor T2* mediante secuencias multieco en el hígado (TR/TE1/ΔTE/n°ecos/α: 21/1,18/1.0/20/35°) y el miocardio (26/1,04/0.8/30/60°). Se realizó el análisis de correlación-regresión de los valores T2* cardíaco y hepático con los valores de ferritina y CHH, y entre sí. Resultados. Trece pacientes mostraron valores de ferritina superiores a 1.000 ng/ml (mediana/mínimo/máximo: 1.762/294/3.785 ng/ml). Trece pacientes presentaron CHH elevada, mayor de 80 μmol/g (mediana/mínimo/máximo: 125,4/41,2/241,5 μmol/g). En todos los casos la función cardíaca estaba preservada. En 15 pacientes el valor T2* hepático fue menor de 6,3 ms. Solo en un caso, el valor T2*miocárdico fue menor de 20 ms. Se observó una alta correlación para los valores T2*hepático/CHH (r: -0,912). La correlación fue estadísticamente significativa para T2* hepático/ferritina (r: -0,541). La correlación T2*miocárdico/ferritina, T2*miocárdico/CHH y T2*miocárdico/T2*hepático no fue estadísticamente significativa. Conclusión. Los valores T2* hepático muestran una alta correlación con la CHH y una correlación estadísticamente significativa con la ferritina. No se observó correlación entre los valores T2* miocárdico y la ferritina en sangre, la CHH, ni con el valor T2* hepático (AU)

Objective: To determine whether there is iron overload by calculating the T2* value in the liver and myocardium in patients with secondary haemochromatosis. To analyse the correlation of the values obtained with the iron levels in blood, with the liver iron concentration (LIC) calculated using magnetic resonance (MR) imaging, and the correlation between them. Material and methods: A total of 16 patients (13 males, 3 females), with a mean age of 61 years, were included and evaluated in the years 2008 and 2009. Fifteen of them had received multiple transfusions, and one was diagnosed with hereditary sideroblastic anaemia. The measurements included, blood ferritin, LIC by MRI, cardiac function using MRI and the T2* value by means of multi-echo sequences in the liver (TR/TE1/ TE/No of echos/ : 21/1,18/1.0/20/35◦) and myocardium (26/1.04/0.8/30/60◦). A correlation-regression analysis was performed by comparing the cardiac and liver T2* values with the ferritin, LIC and between each of them. Results: A total of 13 patients had ferritin values greater than 1000 ng/ml (median/minimum/maximum: 1762/294/3785 ng/ml). An increased LIC greater than 80 mol/g (median/minimum/maximum: 125.4/41.2/241.5 mol/g) was observed in 13 patients. In all cases cardiac function was conserved, and in 15 cases the liver T2* value was less than 6.3 ms. The myocardium T2* value was less than 20 ms. in only one case. A high correlation was observed between the liver T2* values and the LIC (r: -0.912). The correlation was statistically significant between the liver T2* value and ferritin (r: -0.541). The correlations between myocardium T2* and ferritin, myocardium T2* and LIC, and myocardium T2* and liver T2* were not statistically significant. Conclusions: The liver T2* showed a high correlation with LIC and a statistically significant correlation with ferritin. No association was observed between the myocardium T2* values and ferritin in blood, the LIC or the liver T2* value (AU)

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OBJECTIVE: To determine whether there is iron overload by calculating the T2* value in the liver and myocardium in patients with secondary haemochromatosis. To analyse the correlation of the values obtained with the iron levels in blood, with the liver iron concentration (LIC) calculated using magnetic resonance (MR) imaging, and the correlation between them. MATERIAL AND METHODS: A total of 16 patients (13 males, 3 females), with a mean age of 61 years, were included and evaluated in the years 2008 and 2009. Fifteen of them had received multiple transfusions, and one was diagnosed with hereditary sideroblastic anaemia. The measurements included, blood ferritin, LIC by MRI, cardiac function using MRI and the T2* value by means of multi-echo sequences in the liver (TR/TE1/ΔTE/No of echos/α: 21/1,18/1.0/20/35°) and myocardium (26/1.04/0.8/30/60°). A correlation-regression analysis was performed by comparing the cardiac and liver T2* values with the ferritin, LIC and between each of them. RESULTS: A total of 13 patients had ferritin values greater than 1000ng/ml (median/minimum/maximum: 1762/294/3785ng/ml). An increased LIC greater than 80µmol/g (median/minimum/maximum: 125.4/41.2/241.5µmol/g) was observed in 13 patients. In all cases cardiac function was conserved, and in 15 cases the liver T2* value was less than 6.3ms. The myocardium T2* value was less than 20ms. in only one case. A high correlation was observed between the liver T2* values and the LIC (r:-0.912). The correlation was statistically significant between the liver T2* value and ferritin (r:-0.541). The correlations between myocardium T2* and ferritin, myocardium T2* and LIC, and myocardium T2* and liver T2* were not statistically significant. CONCLUSIONS: The liver T2* showed a high correlation with LIC and a statistically significant correlation with ferritin. No association was observed between the myocardium T2* values and ferritin in blood, the LIC or the liver T2* value.

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The design of artificial molecular machines often takes inspiration from macroscopic machines. However, the parallels between the two systems are often only superficial, because most molecular machines are governed by quantum processes. Previously, rotary molecular motors powered by light and chemical energy have been developed. In electrically driven motors, tunnelling electrons from the tip of a scanning tunnelling microscope have been used to drive the rotation of a simple rotor in a single direction and to move a four-wheeled molecule across a surface. Here, we show that a stand-alone molecular motor adsorbed on a gold surface can be made to rotate in a clockwise or anticlockwise direction by selective inelastic electron tunnelling through different subunits of the motor. Our motor is composed of a tripodal stator for vertical positioning, a five-arm rotor for controlled rotations, and a ruthenium atomic ball bearing connecting the static and rotational parts. The directional rotation arises from sawtooth-like rotational potentials, which are solely determined by the internal molecular structure and are independent of the surface adsorption site.

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We evaluated the effect of fetal respiratory movements (RM) on the heart rate (HR) fractal dynamics.Abdominal ECG recordings were collected from low-middle-risk pregnant woman at rest. Mean gestational age was 34.8 ± 3.7 weeks. Ultrasound images were simultaneously acquired determining if RM were exhibited by fetuses. 13 pairs of HR series were compared. Each pair included 5 min of data from the same fetus either during the manifestation of RM or when there was no persistent indication of them. Detrended fluctuation analysis was applied to these series for obtaining the scaling exponent α1. HR series were also assessed using the conventional parameters RMSSD and HF power.The main findings of this contribution were the lack of significant changes in the scaling exponent α1 of fetal HR fluctuations as a result of RM. By contrast, HF power and RMSSD did show significant changes associated with the manifestation of fetal RM (p < 0.001 and p < 0.05, respectively). Yet the scaling exponent was the only parameter showing a significant relationship with the particular frequency of fetal RM (r s  = 0.6, p < 0.03). Given the invariability of α1 regarding the manifestation of fetal RM, we consider that the HR short-term fractal properties are convenient for assessing the cardiovascular prenatal regulation.

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The interpretation of heart rate patterns obtained by fetal monitoring relies on the definition of a baseline, which is considered as the running average heart rate in the absence of external stimuli during periods of fetal rest. We present a study along gestation of the baseline's fluctuations, in relation to fractal and nonlinear properties, to assess these fluctuations according with time-varying attracting levels introduced by maturing regulatory mechanisms. A low-risk pregnancy was studied weekly from the 17th to 38th week of gestation during long-term recording sessions at night (>6 h). Fetal averaged pulse rate samples and corresponding baseline series were obtained from raw abdominal ECG ambulatory data. The fractal properties of these series were evaluated by applying detrended fluctuation analysis. The baseline series were also explored to evaluate nonlinear properties and time ordering by applying the scaling magnitude and sign analyses. Our main findings are that the baseline shows fractal and even nonlinear anticorrelated fluctuations. This condition was specially the case before mid-gestation, as revealed by α values near to unit, yet becoming significantly more complex after 30 weeks of gestation as indicated by α(mag) values >0.5. The structured (i.e. not random) fluctuations and particular nonlinear changes that we found thus suggest that the baseline provides on itself information concerning the functional integration of cardiac regulatory mechanisms.

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Research is a systematic process designed to answer a question. This is the starting point of the whole project and specifically formulates a problem observed in the analysis of the reality. The answer to this attempts to clarify an uncertainty in our knowledge. The conceptual hypothesis is the theoretical answer to the question set out. The operational hypothesis is the particular form that which sets out to demonstrate the conceptual hypothesis. The objectives are the justification for conducting the research. They help to define what it attempts to obtain, and what answers it will give to the formulated questions. It must show a clear and consistent relationship with the description of the problem and, specifically, with the questions and/or hypothesis that are to be resolved.

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Early treatment by thyroid hormone in congenital hypothyroidism (CH) prevents for mental retardation, but the autonomic condition could well remain impaired. The aim of this study was to get insights about the cardiovascular regulation of CH children by analysing their heart rate variability (HRV) data. RR-interval data of 34 early treated CH children, 24 to 48 months of age, were collected at rest in a clinical environment. In all these cases, CH resulted from an abnormal development of thyroid gland. Data from 29 age matched-controls were also collected in a scholar environment. Short time series were then analysed in time and frequency domains. Detrended fluctuation analysis (DFA) was also applied to obtain the scaling exponent α(1). We found that the HRV obtained from children with CH is diminished as suggested by statistical differences (p<0.05) in the following parameters: RMSDD, pNN20, total power, LF and HF. However, no significant differences were found in the LF/HF ratio, the central frequencies of the LF and HF bands, as well as in α(1). Given that the significant differences were basically reflected in static parameters rather than in the frequency distribution or scale-invariant behaviour of the studied data, we consider that the analysis points toward the effect of treatment on rising heart rate by the thyroid hormone, and not necessarily toward any residual autonomic dysfunction, as the dominant underlying cause of the diminished HRV exhibited by CH children.

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Aiming to detect the stage of gestation where dynamical changes of the RR fluctuations may occur, we assessed short-term fluctuations of low risk pregnant women. Ninety six, 10min ECG recordings were collected along gestation (7 to 39 weeks). Corresponding RR fluctuations series were analysed to obtain the RMSSD, α(1), α(1(mag)) and α(1(sign)) parameters. Four groups covering first, second and last trimesters of gestation were conformed. No significant changes in α(1), which was close to unit, and α(1(sign)) among gestational groups were identified. But, in accordance with previous findings, we did find a significant reduction of RMSSD along gestation, and significant short-term changes that indicate a higher degree of nonlinearity after about 26 weeks of gestation (α(1(mag))>0.5)). These results suggest that the short-term heart rate dynamics of low risk pregnant women do not become compromised during gestation, despite the increased haemodynamic demands and other ongoing adaptations. Yet the complexity of the mechanisms involved in the cardiac regulation of pregnant women does seem to increase from mid-pregnancy, possibly owing to new short-term control influences or to modifications regardless the strength of the regulatory interactions.

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We studied 10 minutes segments of heartbeat interval fluctuations from 18 young women in labor with normal outcome of pregnancy. Data of each studied case were classified into two distinct groups. One group involving segments where the uterine activity was observable (three or more contractions in ten minutes), and the other group of reference having segments with fewer uterine activity or not presenting contractions at all. For comparison, we also included segments collected during the last trimester of gestation prior to labor from a third group of women. Corresponding RR interval series were analyzed to estimate RR(mean), RMSSD, α(1), α(1(MAG)) and α(1(SIGN)) parameters. No significant differences among groups were identified in RMSSD, α(1) and α(1(MAG)) Nevertheless, α(1(SIGN)) did present significant differences in comparison with the last trimester results (p<0.007), revealing a subtle change in the temporal organization of maternal RR series during labor. Results of these parameters then suggest that during labor, despite preserving a concomitant non-linear influence, the maternal short-term autonomic cardiac regulation behaves with less antagonism.

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The analysis of heart rate fluctuations, or heart rate variability (HRV), may be applied to explore children's neurodevelopment. However, previous studies have reported poor reliability (repeatability) of HRV measures in children at rest and during light exercise. Whether the reliability can be improved by controlling variables such as physical activity, breathing rate and tidal volume, or by selecting non-conventional techniques for analysing the data remains as an open question. We evaluated the short-term repeatability of RR-interval data from medicated children with congenital hypothyroidism (CH). The alpha(1) exponents, obtained by detrended fluctuation analysis (DFA), from the data of 21 children collected at two different sessions were compared. Elapsed days between sessions were 59 +/- 33, and data were obtained during 10 min, trying to restrict the children's activity while being seated. We found statistical agreement between the means of alpha(1) exponents for each session (p = 0.94) and no bias with a low-coefficient variation (9.1%); an intraclass correlation coefficient ri = 0.48 ([0.14 0.72], 95% confidence interval) was also estimated. These findings, which were compared with results obtained by conventional time and frequency techniques, indicate the existence of agreement between the alpha(1) exponents obtained at each session, thereby providing support concerning the repeatability of HRV data as analysed by DFA in children with congenital hypothyroidism. Of particular interest was also the agreement found by using the central frequency of the high-frequency band and the parameter pNN20, both showing better or similar ri than alpha(1) (0.77 [0.57 0.89] and 0.51 [0.17 0.74], respectively), yet considerably better repeatability than other conventional time and frequency parameters.

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