972 resultados para interstitial atom
Resumo:
The formation of electric potential over lunar magnetized regions is essential for understanding fundamental lunar science, for understanding the lunar environment, and for planning human exploration on the Moon. A large positive electric potential was predicted and detected from single point measurements. Here, we demonstrate a remote imaging technique of electric potential mapping at the lunar surface, making use of a new concept involving hydrogen neutral atoms derived from solar wind. We apply the technique to a lunar magnetized region using an existing dataset of the neutral atom energy spectrometer SARA/CENA on Chandrayaan-1. Electrostatic potential larger than +135 V inside the Gerasimovic anomaly is confirmed. This structure is found spreading all over the magnetized region. The widely spread electric potential can influence the local plasma and dust environment near the magnetic anomaly.
Resumo:
BACKGROUND Pulmonary fibrosis may result from abnormal alveolar wound repair after injury. Hepatocyte growth factor (HGF) improves alveolar epithelial wound repair in the lung. Stem cells were shown to play a major role in lung injury, repair and fibrosis. We studied the presence, origin and antifibrotic properties of HGF-expressing stem cells in usual interstitial pneumonia. METHODS Immunohistochemistry was performed in lung tissue sections and primary alveolar epithelial cells obtained from patients with usual interstitial pneumonia (UIP, n = 7). Bone marrow derived stromal cells (BMSC) from adult male rats were transfected with HGF, instilled intratracheally into bleomycin injured rat lungs and analyzed 7 and 14 days later. RESULTS In UIP, HGF was expressed in specific cells mainly located in fibrotic areas close to the hyperplastic alveolar epithelium. HGF-positive cells showed strong co-staining for the mesenchymal stem cell markers CD44, CD29, CD105 and CD90, indicating stem cell origin. HGF-positive cells also co-stained for CXCR4 (HGF+/CXCR4+) indicating that they originate from the bone marrow. The stem cell characteristics were confirmed in HGF secreting cells isolated from UIP lung biopsies. In vivo experiments showed that HGF-expressing BMSC attenuated bleomycin induced pulmonary fibrosis in the rat, indicating a beneficial role of bone marrow derived, HGF secreting stem cells in lung fibrosis. CONCLUSIONS HGF-positive stem cells are present in human fibrotic lung tissue (UIP) and originate from the bone marrow. Since HGF-transfected BMSC reduce bleomycin induced lung fibrosis in the bleomycin lung injury and fibrosis model, we assume that HGF-expressing, bone-marrow derived stem cells in UIP have antifibrotic properties.
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Effects of Combined Bevacizumab and Paclitaxel on Tumor Interstitial Fluid Pressure in a Preclinical Breast Cancer Model by Ricardo H. Alvarez Several mechanisms of cell resistance are often accountable for unsuccessful chemotherapy against cancer. Another reason, which has received increased attention, is the inefficient transport of anticancer drugs into tumor tissue. These impaired transports of chemotherapy into the tumor have been attributed to abnormal microvasculature and to pathologically increased tumor hypertension also called: interstitial fluid pressure (IFP). The pathophysiological processes leading to elevated tumor IFP are poorly understood. Here, in a preclinical breast cancer model, it is argued that a condition of raised IFP is a major factor in preventing optimal access of systemically administered chemotherapy agents. In our experimental model, we used a GILM2 human breast cancer in xenografts; mice were treated with different doses of paclitaxel –a widely used antimicrotubular agent, and bevacizumab –monoclonal antibody against vascular endothelial growth factor (VEGF). The proposed research project is designed to test the hypothesis that paclitaxel in combination with bevacizumab decreases the tumor IPF by restoring tumor permeability and increasing chemotherapy delivery. We demonstrated that the combination of paclitaxel and bevacizumab produced greater tumor control than either agent given alone and this combination reduced the IFP, producing an increment of 75% of apoptosis compared with the control arm. In addition, the intra-tumor paclitaxel quantification by liquid chromatography/Mass Spectrometry (LC/MS) demonstrated that lower dose of both agents showed a synergistic effect compared with high dose of treatment, where there is no significantly increase of paclitaxel into the tumor. These preclinical results are likely to have broad implications for the utility of anti-angiogenic therapies alone and in combination with chemotherapeutic agents.
Resumo:
We report on the realization of Atom Trap Trace Analysis for39Ar and its first application to dating of groundwater samples. The presented system achieves an atmospheric39Ar count rate as high as 3.58 ± 0.10 atoms/h allowing for the determination of the39Ar concentration in less than a day. We demonstrate that the measured count rates are proportional to the39Ar concentration by intercomparison with Low-Level Counting results and by measurements on prepared argon samples with defined concentration. For a geophysical application, we degas three different groundwater samples and gas chromatographically extract the argon. The39Ar ages inferred from the count rates extend over the accessible dating range and are in agreement with the Low-Level Counting results as well as with complementary isotope data.
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Pulmonary lipofibroblasts are thought to be involved in lung development, regeneration, vitamin A storage, and surfactant synthesis. Most of the evidence for these important functions relies on mouse or rat studies. Therefore, the present study was designed to investigate the presence of lipofibroblasts in a variety of early postnatal and adult mammalian species (including humans) to evaluate the ability to generalize functions of this cell type for other species. For this purpose, lung samples from 14 adult mammalian species as well as from postnatal mice, rats, and humans were investigated using light and electron microscopic stereology to obtain the volume fraction and the total volume of lipid bodies. In adult animals, lipid bodies were observed only, but not in all rodents. In all other species, no lipofibroblasts were observed. In rodents, lipid body volume scaled with body mass with an exponent b = 0.73 in the power law equation. Lipid bodies were not observed in postnatal human lungs but showed a characteristic postnatal increase in mice and rats and persisted at a lower level in the adult animals. Among 14 mammalian species, lipofibroblasts were only observed in rodents. The great increase in lipid body volume during early postnatal development of the mouse lung confirms the special role of lipofibroblasts during rodent lung development. It is evident that the cellular functions of pulmonary lipofibroblasts cannot be transferred easily from rodents to other species, in particular humans.
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The Interstellar Boundary Explorer (IBEX) observes the IBEX ribbon, which stretches across much of the sky observed in energetic neutral atoms (ENAs). The ribbon covers a narrow (~20°-50°) region that is believed to be roughly perpendicular to the interstellar magnetic field. Superimposed on the IBEX ribbon is the globally distributed flux that is controlled by the processes and properties of the heliosheath. This is a second study that utilizes a previously developed technique to separate ENA emissions in the ribbon from the globally distributed flux. A transparency mask is applied over the ribbon and regions of high emissions. We then solve for the globally distributed flux using an interpolation scheme. Previously, ribbon separation techniques were applied to the first year of IBEX-Hi data at and above 0.71 keV. Here we extend the separation analysis down to 0.2 keV and to five years of IBEX data enabling first maps of the ribbon and the globally distributed flux across the full sky of ENA emissions. Our analysis shows the broadening of the ribbon peak at energies below 0.71 keV and demonstrates the apparent deformation of the ribbon in the nose and heliotail. We show global asymmetries of the heliosheath, including both deflection of the heliotail and differing widths of the lobes, in context of the direction, draping, and compression of the heliospheric magnetic field. We discuss implications of the ribbon maps for the wide array of concepts that attempt to explain the ribbon's origin. Thus, we present the five-year separation of the IBEX ribbon from the globally distributed flux in preparation for a formal IBEX data release of ribbon and globally distributed flux maps to the heliophysics community.
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We present the observations of energetic neutral atoms (ENAs) produced at the lunar surface in the Earth's magnetotail. When the Moon was located in the terrestrial plasma sheet, Chandrayaan-1 Energetic Neutrals Analyzer (CENA) detected hydrogen ENAs from the Moon. Analysis of the data from CENA together with the Solar Wind Monitor (SWIM) onboard Chandrayaan-1 reveals the characteristic energy of the observed ENA energy spectrum (the e-folding energy of the distribution function) ∼100 eV and the ENA backscattering ratio (defined as the ratio of upward ENA flux to downward proton flux) <∼0.1. These characteristics are similar to those of the backscattered ENAs in the solar wind, suggesting that CENA detected plasma sheet particles backscattered as ENAs from the lunar surface. The observed ENA backscattering ratio in the plasma sheet exhibits no significant difference in the Southern Hemisphere, where a large and strong magnetized region exists, compared with that in the Northern Hemisphere. This is contrary to the CENA observations in the solar wind, when the backscattering ratio drops by ∼50% in the Southern Hemisphere. Our analysis and test particle simulations suggest that magnetic shielding of the lunar surface in the plasma sheet is less effective than in the solar wind due to the broad velocity distributions of the plasma sheet protons.
Resumo:
Over the last decade, a plethora of computer-aided diagnosis (CAD) systems have been proposed aiming to improve the accuracy of the physicians in the diagnosis of interstitial lung diseases (ILD). In this study, we propose a scheme for the classification of HRCT image patches with ILD abnormalities as a basic component towards the quantification of the various ILD patterns in the lung. The feature extraction method relies on local spectral analysis using a DCT-based filter bank. After convolving the image with the filter bank, q-quantiles are computed for describing the distribution of local frequencies that characterize image texture. Then, the gray-level histogram values of the original image are added forming the final feature vector. The classification of the already described patches is done by a random forest (RF) classifier. The experimental results prove the superior performance and efficiency of the proposed approach compared against the state-of-the-art.