436 research outputs found

    CDS wide slit time-series of EUV coronal bright points

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    Wide slit (90" x 240" ) movies of four Extreme Ultraviolet coronal bright points (BPs) obtained with the Coronal Diagnostic Spectrometer (CDS) on board the Solar and Heliospheric Observatory (SoHO) have been inspected. The wavelet analysis of the He I 584.34 Å, O V 629.73 Å and Mg VII/IX 368 Å time-series confirms the oscillating nature of the BPs, with periods ranging between 600 and 1100 s. In one case we detect periods as short as 236 s. We suggest that these oscillations are the same as those seen in the chromospheric network and that a fraction of the network bright points are most likely the cool footpoints of the loops comprising coronal bright points. These oscillations are interpreted in terms of global acoustic modes of the closed magnetic structures associated with BPs

    Cryopreservation of encapsulated apices of sugarcane : effect of freezing procedure and histology

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    SUMMARY: The effect of sucrose concentration during the pregrowth treatment and of the freezing procedure on the survival of encapsulated apices of 6 sugarcane varieties was investigated. The optimal sucrose concentration was 0.75M. Survival was noted with both rapid freezing by direct immersion in liquid nitrogen and slow freezing using a programmable freezer but it was generally higher &er rapid cooling. Important genotypic variation was observed for both parameters studied. Histological examination revealed that cells were slightly harmed during pregrowth and freezing. Apices could withstand freezing as a whole. Direct regrowth of cryopreserved apices occurred within 3 days after thawing

    A Langevin Canonical Approach to the Study of Quantum Stochastic Resonance in Chiral Molecules

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    A Langevin canonical framework for a chiral two-level system coupled to a bath of harmonic oscillators is used within a coupling scheme different from the well-known spin-boson model to study the quantum stochastic resonance for chiral molecules. This process refers to the amplification of the response to an external periodic signal at a certain value of the noise strength, being a cooperative effect of friction, noise, and periodic driving occurring in a bistable system. Furthermore, from this stochastic dynamics within the Markovian regime and Ohmic friction, the competing process between tunneling and the parity violating energy difference present in this type of chiral systems plays a fundamental role. This mechanism is finally proposed to observe the so-far elusive parity-violating energy difference in chiral molecules.Helen Clara Peñate-Rodríguez and Germån Rojas-Lorenzo acknowledge a scientific project from InSTEC. Pedro Bargueño acknowledge the support from the Faculty of Science and Vicerrectoría de Investigaciones of Universidad de Los Andes, Bogotå, Colombia. Salvador Miret-Artés acknowledges a grant with Ref. FIS2014-52172-C2-1-P from the Ministerio de Economía y Competitividad (Spain). We acknowledge support by the CSIC Open Access Publication Initiative through its Unit of Information Resources for Research (URICI)

    c-Jun N terminal kinase modulates NOX-4 derived ROS production and myofibroblasts differentiation in human breast stromal cells

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    BACKGROUND: Hard consistency, developed under the influence of tumor cell factors, is a characteristic feature of a breast tumor. Activation of resident fibroblasts leading to a myofibroblast phenotype is the principal feature that orchestrates this fibrotic process. The aim of this study was to assess the effects induced by TGF-ÎČ1, a growth factor abundantly present in tumor microenvironment, on the molecular mechanisms that mediate myofibroblastic differentiation of normal human mammary fibroblasts. METHODS: We used an immortalized fibroblastic cell line derived from normal mammary tissue (RMF-EG cells) to study the effect of TGF-ÎČ1 in the expression of α-SMA and CTGF as markers of myofibroblastic differentiation. The influence of redox status and JNK activity on TGF-ÎČ1-induced transcriptional activity was measured by a luciferase reporter assay. We also used a shRNA approach to evaluate the influence of NOX4 in myofibroblastic differentiation. RESULTS: TGF-ÎČ1 stimulates the expression of myofibroblast markers α-SMA and CTGF. Using a NOX inhibitor (DPI) and cells expressing a shRNA for NOX4, we demonstrated that TGF-ÎČ1 promotes an oxidative environment that favors myofibroblastic differentiation. We also found that activation of c-Jun N-terminal kinase is required for TGF-ÎČ1-dependent expression of CTGF, NOX4 and α-SMA. CONCLUSIONS: Human mammary stromal fibrosis, evaluated by the expression of early and late markers as CTGF and α-SMA, depends on the activation of JNK signaling pathway. Our results show that JNK activation is an early event that precedes the increase in ROS levels leading to myofibroblastic differentiation and tumor fibrosis, suggesting that inhibition of JNK may be used a method to interrupt the development of tumor desmoplasia

    The structure and dynamics of a bright point as seen with Hinode, SoHO and TRACE

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    Our aim is to determine the plasma properties of a coronal bright point and compare its magnetic topology extrapolated from magnetogram data with its appearance in X-ray images. We analyse spectroscopic data obtained with EIS/Hinode, Ca II H and G-band images from SOT/Hinode, UV images from TRACE, X-ray images from XRT/Hinode and high-resolution/high-cadence magnetogram data from MDI/SoHO. The BP comprises several coronal loops as seen in the X-ray images, while the chromospheric structure consists of tens of small bright points as seen in Ca II H. An excellent correlation exists between the Ca II BPs and increases in the magnetic field, implying that the Ca II H passband is a good indicator for the concentration of magnetic flux. Doppler velocities between 6 and 15 km/s are derived from the Fe XII and Fe XIII lines for the BP region, while for Fe XIV and Si VII they are in the range from -15 to +15 km/s. The coronal electron density is 3.7x10^9 cm^-3. An excellent correlation is found between the positive magnetic flux and the X-ray light-curves. The remarkable agreement between the extrapolated magnetic field configuration and some of the loops composing the BP as seen in the X-ray images suggests that a large fraction of the magnetic field in the bright point is close to potential. The close correlation between the positive magnetic flux and the X-ray emission suggests that energy released by magnetic reconnection is stimulated by flux emergence or cancellation.Comment: 10 pages with 11 figures. Accepted in Astronomy and Astrophysic

    Prognostic significance of infarct size and location: The case of insular stroke

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    The prognostic relevance of strokes in different locations is debated. For example, insular strokes have been associated with increased mortality, but this association could reflect their greater severity. In two independent cohorts of patients with supratentorial ischemic stroke (n = 90 and 105), we studied the prognostic consequences of lesion size and location using voxel-based lesion-symptom mapping before and after volume control, which better accounts for total lesion volume. Strokes affecting the insula were larger than non-insular strokes (28 vs 2cc and 25 vs 3cc, p < 0.001 in both cohorts). A number of supratentorial areas (mainly in the left hemisphere), including the insula, were associated with poor functional outcome in both cohorts before (4014 voxels) and after volume control (1378 voxels), while the associations with death were greatly reduced after volume control (from 8716 to 325 voxels). Exploratory analyses suggested that the method of lesion volume quantification, the National Institutes of Health Stroke Scale hemispheric bias and patient selection can result in false associations between specific brain lesions and outcomes. In conclusion, death in the first months after stroke is mainly explained by large infarct volumes, whereas lesions of specific supratentorial structures, mostly in the left hemisphere, also contribute to poor functional outcomes

    SCREENING OF STATIC CULTURE AND COMPARISON OF BATCH AND CONTINUOUS CULTURE FOR THE TEXTILE DYE BIOLOGICAL DECOLORIZATION BY Phanerochaete chrysosporium

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    Abstract -The production of manganese dependent peroxidase (MnP) by Phanerochaete chrysosporium and the level of decolorization of 13 dyes were evaluated using static and agitated batch cultures and continuous cultures. A screening carried out under static conditions showed that the oxidative system has a certain affinity for azoic structures. For concentrations of 100 mg l -1 of Acid Black 1, Reactive Black 5, Reactive Orange 16 and Acid Red 27, decolorization percentages higher than 90% were obtained. In batch cultures with Acid Black 1 and Reactive Black 5 a significant increment in primary post-metabolism biomass was observed. For these last two dyes, it was possible to explore the response of the continuous system during 32 to 47 days, with concentrations between 25 to 400 mg l -1 , obtaining decolorization percentages greater than 70% for 400 mg l -1

    The Magnetic Topology of Coronal Mass Ejection sources

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    In an attempt to test current initiation models of coronal mass ejections (CMEs), with an emphasis on the magnetic breakout model, we inspect the magnetic topology of the sources of 26 CME events in the context of their chromospheric and coronal response in an interval of approximately nine hours around the eruption onset. First, we perform current-free (potential) extrapolations of photospheric magnetograms to retrieve the key topological ingredients, such as coronal magnetic null points. Then we compare the reconnection signatures observed in the high cadence and high spatial resolution of the Transition Region And Coronal Explorer (TRACE) images with the location of the relevant topological features. The comparison reveals that only seven events can be interpreted in terms of the breakout model, which requires a multi-polar topology with pre-eruption reconnection at a coronal null. We find, however, that a larger number of events (twelve) can not be interpreted in those terms. No magnetic null is found in six of them. Seven other cases remain difficult to interpret. We also show that there are no systematic differences between the CME speed and flare energies of events under different interpretations.Comment: Accepted for publication in Ap
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