Estimativa da Partição de Energia na Superfície a Partir de Séries Meteorológicas de Temperatura e Umidade Específica do Ar

Neste trabalho, é proposto um método simples de estimativa da razão entre os fluxos turbulentos de calor sensível (H) e latente (LE) e da altura da camada limite planetária (CLP), utilizando séries meteorológicas de temperatura (T) e umidade específica do ar (q). De forma geral, o método desenvolvido reproduziu satisfatoriamente a evolução diária de T e q, o que faz deste método promissor para estimativas da partição de energia em superfície, bem como da altura da CLP. No entanto, é necessária a validação do método a partir de medidas de H e LE, assim como alguns ajustes devem ser feitos

Estimativa da Partição de Energia na Superfície

This paper is a complementary analysis to method development, which proposes to estimate the energy partition on the surface by Bowen ratio method and height of convective boundary layer on the monthly scale based on the average temporal evolution of the variables air temperature and specific humidity. The basic hypothesis is that the evolution of these quantities is controlled solely by the convergence of surface fluxes of sensible and latent heat. This assumption is valid for monthly scale and in regions of middle latitudes away from the coast. Thus, it is assumed that the advective terms of the balance equation of these quantities in the convective boundary layer, the prefrontal situations and post-frontal have opposite sign. Therefore, using for a longer time scale than the typical scale of the passage of synoptic systems, the cancellation terms of hypothesis can be tested. In this study, the method is applied to the region of Santa Maria, where it is assumed that the conditions allowing despise the advective terms in monthly scale are valid. When testing the method on different time scales: 5,10,15,20 and 30 days, smaller errors temperature and specific humidity were for 15 and 30 days, while the sensible heat and latent heat fluxes showed lower relative errors at 20 and 30 days, respectively.Este trabalho é uma análise complementar ao método em desenvolvimento, que propõe estimar a partição de energia na superfície pelo método da razão de Bowen e a altura da camada limite convectiva na escala mensal baseando-se na evolução temporal média das variáveis temperatura e umidade específica do ar. A hipótese básica é que a evolução dessas quantidades é controlada unicamente pela convergência dos fluxos superficiais de calor sensível e calor latente. Essa suposição é válida para escala mensal e em regiões de latitudes médias afastadas da costa. Dessa forma, presume-se que os termos advectivos, da equação de balanço dessas quantidades na camada limite convectiva, nas situações pré-frontais e pós-frontais apresentam sinal oposto. Assim, utilizando-se para uma escala temporal mais longa que a escala típica da passagem dos sistemas sinóticos, a hipótese de cancelamento dos termos pode ser testada. Inicialmente, o método é aplicado para a região de Santa Maria, onde é assumido que as condições que permitem desprezar os termos advectivos em escala mensal são válidas. Ao testar o método em diferentes escalas temporais: 5,10,15,20 e 30 dias, os menores erros de temperatura e umidade específica do ar foram para 15 e 30 dias, enquanto que os fluxos de calor sensível e de calor latente apresentaram menores erros relativos em 20 e 30 dias, respectivamente

Glutamato induz radioresistência em glioblastomas humanos

Os glioblastomas (GBMs) são os tumores cerebrais mais agressivos. Além disso, apresentam resistência intrínseca à radioterapia. Considerando que a maior liberação de glutamato tem relação com a agressividade dos GBMs, investigamos a participação do glutamato na resposta à radioterapia em GBMs cultivados a partir de amostras obtidas por ressecção cirúrgica. Para tal, culturas de UGBM1 e UGBM2 foram tratados com 2, 5 e 10 Gy de radiação ionizante na presença ou não de glutamato (5 mM), DNQX (500 μM) ou BSO (25 μ M). Nossos resultados mostraram que o glutamato diminuiu a sensibilidade dos dois cultivos à radioterapia, cujo efeito foi inibido pelo DNQX e BSO. Estes achados sugerem que a ação protetora induzida pelo glutamato à radioterapia em GBMs ocorre via receptores de AMPA e GSH

Planetary boundary layer evolution over the Amazon rainforest in episodes of deep moist convection at the Amazon Tall Tower Observatory

In this study, high-frequency, multilevel measurements, performed from late October to mid-November of 2015 at a 80m tall tower of the Amazon Tall Tower Observatory (ATTO) project in the central state of Amazonas, Brazil, were used to diagnose the evolution of thermodynamic and kinematic variables as well as scalar fluxes during the passage of outflows generated by deep moist convection (DMC). Outflow associated with DMC activity over or near the tall tower was identified through the analysis of storm echoes in base reflectivity data from an S-band weather radar at Manaus, combined with the detection of gust fronts and cold pools utilizing tower data. Four outflow events were selected, three of which took place during the early evening transition or nighttime hours and one during the early afternoon. Results show that the magnitude of the drop in virtual potential temperature and changes in wind velocity during outflow passages vary according to the type, organization, and life cycle of the convective storm. The nocturnal events had well-defined gust fronts with moderate decreases in virtual potential temperature and increases in wind speed. The early afternoon event lacked a sharp gust front and only a gradual drop in virtual potential temperature was observed, probably because of weak or undeveloped outflow. Sensible heat flux (H) increased at the time of the gust front arrival, which was possibly due to the sinking of colder air. This was followed by a prolonged period of negative H, associated with enhanced nocturnal negative H in the wake of the storms. In turn, increased latent heat flux (LE) was observed following the gust front, owing to drier air coming from the outflow; however, malfunctioning of the moisture sensors during rain precluded a better assessment of this variable. Substantial enhancements of turbulent kinetic energy (TKE) were observed during and after the gust front passage, with values comparable to those measured in grass fire experiments, evidencing the highly turbulent character of convective outflows. The early afternoon event displayed slight decreases in the aforementioned quantities in the passage of the outflow. Finally, a conceptual model of the time evolution of H in nocturnal convective outflows observed at the tower site is presented. © Author(s) 2020

Influence of Atmospheric Stability on the flow dynamics within and above a dense Amazonian forest

This study provides a detailed analysis of the influence of atmospheric stratification on the flow dynamics above and within a dense forest for a 19-days campaign at the Amazon Tall Tower Observatory (ATTO) site. Observations taken at seven levels within and above the forest along an 81-meter and a 325-meter towers allow a unique investigation of the vertical evolution of the turbulent field in the roughness sublayer and in the surface layer above it. Five different stability classes were defined on the basis of the behavior of turbulent heat, momentum and CO2 fluxes and variance ratio as a function of h/L stability parameter (where h is the canopy height and L is the Obukhov length). The novelty is the identification of a ‘super-stable’ (SS) regime (h/L>3) characterized by extremely low wind speeds, the almost completely suppression of turbulence and a clear dominance of submeso motions both above and within the forest. The obtained data classification was used to study the influence of atmospheric stratification on the vertical profiles of turbulent statistics. The spectral characteristics of coherent structures and of submeso motions (that may influence the energy and mass exchange above the Amazon forest) have been analyzed by wavelet analyses. The role of the main structures in momentum, heat and CO2 transport at the different levels inside and above the forest and in different diabatic conditions was thoroughly investigated through multiresolution and quadrant analyses. In unstable and neutral stability, the flow above the canopy appears modulated by ejections, whereas downward and intermittent sweeps dominate the transport inside the canopy. In the roughness sublayer (z £ 2h) the coherent structures dominating the transport within and above the canopy have a characteristic temporal scale of about 100 sec, whereas above this layer the transport is mainly driven by larger scale convection (temporal scale of about 15 min). In stable conditions the height of roughness sublayer progressively decreases with increasing stability reaching the minimum value (z<1.35h) in the SS regime. Above the canopy the flow is clearly dominated by ejections but characterized by a higher intermittency mainly in SS conditions. On the other hand, the rapid shear stress absorption in the highest part of the vegetation produces a less clear dominance of sweeps and a less defined role of odd and even quadrants inside the canopy in the transport of momentum, heat and CO2. In the weakly stable regime (0.1

Vertical propagation of submeso and coherent structure in a tall and dense amazon forest in different stability conditions. PART II: Coherent structures analysis

Observations of the vertical structure of the turbulent flow in different stability regimes above and within the Amazon Forest at the Amazon Tall Tower Observatory (ATTO) site have been presented in Part I. Here, the influence of stability on the inception and development of coherent structures is investigated. According to the mixing-layer analogy the coherent vortices that dominate the turbulent flows at the canopy-atmosphere interface are generated by hydrodynamical instabilities triggered by an inflection in the vertical profile of the mean wind speed at or near the canopy top. The coherent motions time, and separation length scale, , depend on the shear length scale, , close to the canopy top. The present analysis studies the characteristics of , and in the five stability regimes defined in Part I. The behaviour of with stability is evaluated and parameterized. increases with decreasing stability, presenting two asymptotes for large unstable and stable stratification and a linear behaviour close to neutral stratification. Coherent structures and their timescale are detected with an original method based on the autocorrelation functions of 5-min subsets of turbulent quantities. The vertical time scale is larger in neutral conditions and decreases for both increasing and decreasing stability. At the canopy top the separation length scale presents a linear dependence on , whose slope is maximum in neutral conditions and decreases departing from neutrality. An original parameterization of the dependence of this slope on , where is the canopy height and is the Obukhov length, is shown. Combining the parameterizations, the dependence of the separation length scale is finally presented. has a maximum for slightly unstable conditions, linearly decreases towards neutral and weakly stable stratifications and then it tends to zero for very intense unstable and stable stratifications

Oxidative stress in Niemann-Pick type C patients : a protective role of N-butyl-deoxynojirimycin therapy

Niemann-Pick type C (NPC) is a rare neurodegenerative disorder biochemically characterized by the accumulation of cholesterol and glycosphingolipids in late endosomes and lysosomes of the affected patients. N-butyl-deoxynojirimycin is the only approved drug for patients with NPC disease. It inhibits glycosphingolipid synthesis, therefore reducing intracellular lipid storage. Although the mechanisms underlying the neurologic damage in the NPC disease are not yet well established, in vitro and in vivo studies suggest an involvement of reactive species in the pathophysiology of this disease. In this work we aimed to evaluate parameters of lipid and protein oxidation, measured by thiobarbituric acid-reactive species (TBA-RS) and protein carbonyl formation, respectively, as well as the enzymatic and non-enzymatic antioxidant defenses in plasma, erythrocytes and fibroblasts from NPC1 patients, at diagnosis and during treatment with N-butyl-deoxynojirimycin. We found a significant increase of TBA-RS in plasma and fibroblasts, as well as increased protein carbonyl formation and decreased total antioxidant status (TAS) in plasma of untreated NPC1 patients as compared to the control group. In addition, erythrocyte glutathione peroxidase (GSH-Px) activity was increased, whereas CAT and SOD activities were normal in these patients. We also observed that patients treated with N-butyl-deoxynojirimycin normalized plasma TBA-RS and TAS, as well as erythrocyte GSH-Px activity. Taken together, the present data indicate that oxidative stress is increased in patients with NPC1 disease and that treatment with N-butyl-deoxynojirimycin is able to confer protection against this pathological process