1,961 research outputs found
Use of MODIS Sensor Images Combined with Reanalysis Products to Retrieve Net Radiation in Amazonia
In the Amazon region, the estimation of radiation fluxes through remote sensing techniques is hindered by the lack of ground measurements required as input in the models, as well as the difficulty to obtain cloud-free images. Here, we assess an approach to estimate net radiation (Rn) and its components under all-sky conditions for the Amazon region through the Surface Energy Balance Algorithm for Land (SEBAL) model utilizing only remote sensing and reanalysis data. The study period comprised six years, between January 2001–December 2006, and images from MODIS sensor aboard the Terra satellite and GLDAS reanalysis products were utilized. The estimates were evaluated with flux tower measurements within the Large-Scale Biosphere-Atmosphere Experiment in Amazonia (LBA) project. Comparison between estimates obtained by the proposed method and observations from LBA towers showed errors between 12.5% and 16.4% and 11.3% and 15.9% for instantaneous and daily Rn, respectively. Our approach was adequate to minimize the problem related to strong cloudiness over the region and allowed to map consistently the spatial distribution of net radiation components in Amazonia. We conclude that the integration of reanalysis products and satellite data, eliminating the need for surface measurements as input model, was a useful proposition for the spatialization of the radiation fluxes in the Amazon region, which may serve as input information needed by algorithms that aim to determine evapotranspiration, the most important component of the Amazon hydrological balance
Analysis of Precipitation and Evapotranspiration in Atlantic Rainforest Remnants in Southeastern Brazil from Remote Sensing Data
The Atlantic Rainforest has been intensely devastated since the beginning of the colonization of Brazil, mainly due to wood extraction and urban and rural settlement. Although the Atlantic Rainforest has been reduced and fragmented, its remnants are important sources of heat and water vapor to the atmosphere. The present study aimed to characterize and to analyze the temporal dynamics of precipitation and evapotranspiration in the Atlantic Rainforest remnants in São Paulo state, southeastern Brazil, for the period from January 2000 to December 2010. To achieve this, global precipitation and evapotranspiration data from TRMM satellite and MOD16 algorithm as well as forest remnant maps produced by SOS Mata Atlântica Foundation and Brazilian National Institute for Space Research (INPE) were used. Results found in this study demonstrated that the use of remote sensing was an important tool for analyzing hydrological variables in Atlantic Rainforest remnants, which can contribute to better understand the interaction between tropical forests and the atmosphere, and for generating input data necessary for surface models coupled to atmospheric general circulation models
Effects of land‐cover changes on the partitioning of surface energy and water fluxes in Amazonia using high‐resolution satellite imagery
Spatial variability of surface energy and water fluxes at local scales is strongly controlled by soil and micrometeorological conditions. Thus, the accurate estimation of these fluxes from space at high spatial resolution has the potential to improve prediction of the impact of land‐use changes on the local environment. In this study, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) and Large‐Scale Biosphere‐Atmosphere Experiment in Amazonia (LBA) data were used to examine the partitioning of surface energy and water fluxes over different land‐cover types in one wet year (2004) and one drought year (2005) in eastern Rondonia state, Brazil. The spatial variation of albedo, net radiation (Rn), soil (G) and sensible (H) heat fluxes, evapotranspiration (ET), and evaporative fraction (EF) were primarily related to the lower presence of forest (primary [PF] or secondary [SF]) in the western side of the Ji‐Parana River in comparison with the eastern side, located within the Jaru Biological Reserve protected area. Water limitation in this part of Amazonia tends to affect anthropic (pasture [PA] and agriculture [AG]) ecosystems more than the natural land covers (PF and SF). We found statistically significant differences on the surface fluxes prior to and ~1 year after the deforestation. Rn over forested areas is ~10% greater in comparison with PA and AG. Deforestation and consequent transition to PA or AG increased the total energy (~200–400%) used to heat the soil subsurface and raise air temperatures. These differences in energy partitioning contributed to approximately three times higher ET over forested areas in comparison with nonforested areas. The conversion of PF to AG is likely to have a higher impact in the local climate in this part of Amazonia when compared with the change to PA and SF, respectively. These results illustrate the importance of conserving secondary forest areas in Amazonia.Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/151879/1/eco2126_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/151879/2/eco2126.pd
Methods to Evaluate Land-Atmosphere Exchanges in Amazonia Based on Satellite Imagery and Ground Measurements
During the last three decades, intensive campaigns and experiments have been conducted for acquiring micrometeorological data in the Amazonian ecosystems, which has increased our understanding of the variation, especially seasonally, of the total energy available for the atmospheric heating process by the surface, evapotranspiration and carbon exchanges. However, the measurements obtained by such experiments generally cover small areas and are not representative of the spatial variability of these processes. This chapter aims to discuss several algorithms developed to estimate surface energy and carbon fluxes combining satellite data and micrometeorological observations, highlighting the potentialities and limitations of such models for applications in the Amazon region. We show that the use of these models presents an important role in understanding the spatial and temporal patterns of biophysical surface parameters in a region where most of the information is local. Data generated may be used as inputs in earth system surface models allowing the evaluation of the impact, both in regional as well as global scales, caused by land-use and land-cover changes
Fatal septic shock due to a disseminated chronic form of paracoccidioidomycosis in an aged woman
Once rare, septic shock (SS) due to disseminated fungal infections has been increasingly reported due to a growing number of immunocompromised patients, but remains rare in non-immune-compromised individuals. In paracoccidioidomycosis, it has been described in only three patients with the severe, acute form of the disease. We describe the development of a refractory, fatal septic shock due to a severe disseminated chronic form of paracoccidioidomycosis in an older woman without any other microbial insults. A striking event in the evolution of her case was the severe depletion of lymphocytes from the peripheral blood and lymphoid organs. Lymphocyte depletion due to apoptosis is described in the late phase of sepsis and can contribute both to immunosuppression and the progression of SS. The possible mechanisms involved in the induction of SS in the chronic form of paracoccidioidomycosis are discussed
Speckle tracking echocardiographic deformation indices in Chagas and idiopathic dilated cardiomyopathy : incremental prognostic value of longitudinal strain
Background Chagas cardiomyopathy (CDC) is associated with a poor prognosis compared to other car-diomyopathies. Speckle tracking echocardiography (STE), which provides direct assessment of myocardial fiber deformation, may be useful in predicting prognosis. Objective This study assessed STE in CDC and compared with idiopathic cardiomyopathy (IDC), and also examined the incremental prognostic information of STE over left ventricular ejection fraction (LVEF) in these patients. Methods We enrolled 112 patients, age of 56.7 ± 11.8 years, 81 with CDC and 31 with IDC. STE indices were obtained at baseline in all patients. The endpoint was a composite of death, hospitalization for heart failure, or need for heart transplantation. Results Patients with IDC had worse LV systolic function compared to CDC, with LVEF of 34.5% vs 41.3%, p = 0.004, respectively. After adjustment for LVEF, there were no differences in STE values between CDC and IDC. During a median follow-up of 18.2 months (range, 11 to 22), 26 patients met the composite end point (24%). LV longitudinal strain was a strong predictor of adverse events, incremental to LVEF and E/e’ ratio (HR 1.463, 95% CI 1.130–1.894; p = 0.004). The risk of cardiac events increased significantly in patients with GLS > - 12% (log-rank p = 0.035). Conclusions STE indices were abnormal in patients with dilated cardiomyopathy, without differences between CDC and IDC. LV longitudinal strain was a powerful predictor of outcome, adding prognostic information beyond that provided by LVEF and E/e’ ratio
Non-deterministic reef fish community assembly in an upwelling-influenced transitional subprovince of the southwestern Atlantic
There are two major theories for setting up ecological communities, the Niche Theory and the Neutral Theory. Both seek to explain the main factors that form a community, which is a great challenge, since each community has its particularities and the environment has different ways to manifest. We devised a process-oriented study that sought to establish the role of environmental niche driven by coastal upwelling in the assembly of reef fish communities from exposed and sheltered environments a few kilometers apart, in the region of Arraial do Cabo (southwestern Atlantic). A multivariate hierarchical generalized linear mixed model fitted with Bayesian inference was applied to abundance and presence-absence data from visual census, together with environmental data from satellite and reanalysis. We found a stronger contribution of random effects to abundance variance with 24% for sites and 20.7% for sheltered vs. exposed locations, and weaker environmental effects with 7.1% for surface chlorophyll-a concentration (SCC) and 5.4% for sea surface temperature (SST). Environmental effects had a stronger contribution in the presence-absence model, with 20.1% for SCC and 14.6% for SST. The overall influence of the upwelling environment across all species was negative, e.g., Gymnothorax moringa and Canthigaster figueiredoi showing negative responses to SCC and Parablennius pilicornis and Malacoctenus delalandii to SST. The joint action of migration-niche mechanisms is inferred from the dominance of spatio-temporal structure, limited influence of life history traits and phylogeny, explaining around 95% of species niches in the abundance model. Our results bring new evidence for the importance of different filters for community assembly other than the environment, such as phylogenetic history and dispersal. We also discuss the balance between niche (environment) and neutral (stochasticity) processes for the assembly of reef fish communities in a tropical-subtropical transition zone
Regional lung recruitability during pneumoperitoneum depends on chest wall elastance - A mechanical and computed tomography analysis in rats
Laparoscopic surgery has been increasingly used as an alternative to open surgery for its well-known post-operative benefits. However, it is associated to intra-operative respiratory impairment (Valenza et al., 2010). Mechanical ventilation management is a challenge for the anesthetist in this scenario of intra-abdominal hypertension, because it is not clear how the modification of the ventilation parameters affects the different components of the respiratory system.
The respiratory system is composed of two elastic elements in series: the lung and the chest wall. The latter, in turn, is made up of two parallel components: the rib cage and the diaphragm, which is also part of the abdominal wall. Disregarding airflow resistances, the positive pressure applied to the respiratory system during mechanical ventilation distends all these elements. How the applied pressure is distributed within the respiratory system depends on the compliance of each single element (Cortes-Puentes et al., 2015) and its distribution within the lungs depends on the compliance of the lung zones, i.e., regional compliance (Mutoh et al., 1991; Lowhagen et al., 2010)
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