Hydrological trade-offs due to different land covers and land uses in the Brazilian Cerrado

Farmland expansion in the Brazilian Cerrado, considered one of the largest agricultural frontiers in the world, has the potential to alter water fluxes on different spatial scales. Despite some large-scale studies being developed, there are still few investigations in experimental sites in this region. Here, we investigate the water balance components in experimental plots and the groundwater table fluctuation in different land covers: wooded Cerrado, sugarcane, pasture and bare soil. Furthermore, we identify possible water balance trade-offs due to the different land covers. This study was developed between 2012 and 2016 in the central region of the state of São Paulo in southern Brazil. Hydrometeorological variables, groundwater table, surface runoff and other water balance components were monitored inside experimental plots containing different land covers; the datasets were analyzed using statistical parameters; and the water balance components uncertainties were computed. Replacing wooded Cerrado by pastureland and sugarcane shifts the overland flow (up to 42&thinsp;mm&thinsp;yr−1) and the water balance residual (up to 504&thinsp;mm&thinsp;yr−1) and may affect groundwater table behavior. This fact suggests significant changes in the water partitioning in a transient land cover and land use (LCLU) system, as the evapotranspiration is lower (up to 719&thinsp;mm&thinsp;yr−1) in agricultural land covers than in the undisturbed Cerrado. We recommend long-term observations for continuing the evaluations initiated in this study, mainly because there are few basic studies on tropical environments at the hillslope scale and more assessments are needed for a better understanding of the real field conditions. Such efforts should be made to reduce uncertainties, validate the water balance hypothesis and catch the variability of hydrological processes.</p

EFFECT OF CORTISOL TREATMENT ON HORMONAL RELATIONSHIPS IN CONGENITAL ADRENAL HYPERPLASIA

The temporal relationship between administration of cortisol and serum 17Α-hydroxyprogesterone was investigated in five patients aged 9-19 years with congenital adrenal hyperplasia due to 21-hydroxylase deficiency. There was marked variability in the 17Α-hydroxyprogesterone response (determined hourly for 24 h) of individual patients to administration of cortisol. Mean concentration was less than 0.030 Μmol/l in one patient but 0.519Μ mol/l in another. Levels were higher in all patients while off treatment, and were greatest in those with salt-losing adrenal hyperplasia. Growth hormone secretion was not suppressed by treatment with cortisol. Withdrawal of cortisol for 3 days resulted in a significant decrease in the mean serum FSH/LH ratio and a rise in serum testosterone in all subjects. Episodic release of gonadotrophins persisted in the adolescent patients.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/75713/1/j.1365-2265.1977.tb02002.x.pd

Performance of evaporation estimation methods compared with standard 20 m2 tank

ABSTRACT The low reliability of evaporation estimates in reservoirs challenges the management of water resources, especially when drought occurs. The evaporation rates measured in buried tanks (20 m2 evaporimeters) are close to that of lakes. However, there are few studies in Brazil using long data sets with this type of tank. In this context, this study aimed to evaluate evaporation estimates of free water surface using the method of Penman (1948) and other five empirical equations in comparison with data from a 20 m2 tank observed during 10 years. The annual relationship between rainfall and evaporation was 1.0, showing variations in dry years (0.7) and rainy years (1.3). Among all evaluated methods, Linacre (1993) shows the best performance. Camargo et al. (1999) has very good estimates using air temperature as input variable and is a simple and reliable alternative when data are missing

Precocious pubarche: Experience in 173 cases Pubarquia precoz: Experiencia en 173 casos

Background: Precocious pubarche (PP), defined as the development of sexual pubic hair before 8 years of age in females and before 9 years in males, is usually a benign condition but it can also be the first sign of an underlying disease. Aim: To analyze the etiology and perform a short term follow up in a cohort of patients with PP. Material and methods: A group of 173 patients (158 females) consulted for PP with a mean age of 7.4±0.1 years. These patients were followed between 15 to 60 months. Anthropometric measurements, bone age, serum levels of total testosterone, 17 OH progesterone (17 OHP) and dehydroepiandrosterone sulphate (DHEAS) were evaluated. Results: Mean birth weight and length was 3024.1±50.5 g and 48.5±0.3 cm, respectively. Ten percent of children were small for gestational age at birth. Bone age was accelerated by 1.1±0.01 years. One hundred and twelve patients were classified as having idiopathic PP (64.7%; 105 females), 29 as central precocious puberty (16.8%; only