2,354 research outputs found
On the ultraviolet signatures of small scale heating in coronal loops
Studying the statistical properties of solar ultraviolet emission lines could
provide information about the nature of small scale coronal heating. We expand
on previous work to investigate these properties. We study whether the
predicted statistical distribution of ion emission line intensities produced by
a specified heating function is affected by the isoelectronic sequence to which
the ion belongs, as well as the characteristic temperature at which it was
formed. Particular emphasis is placed on the strong resonance lines belonging
to the lithium isoelectronic sequence. Predictions for emission lines observed
by existing space-based UV spectrometers are given. The effects on the
statistics of a line when observed with a wide-band imaging instrument rather
than a spectrometer are also investigated. We use a hydrodynamic model to
simulate the UV emission of a loop system heated by nanoflares on small,
spatially unresolved scales. We select lines emitted at similar temperatures
but belonging to different isoelectronic groups: Fe IX and Ne VIII, Fe XII and
Mg X, Fe XVII, Fe XIX and Fe XXIV. Our simulations confirm previous results
that almost all lines have an intensity distribution that follows a power-law,
in a similar way to the heating function. However, only the high temperature
lines best preserve the heating function's power law index (Fe XIX being the
best ion in the case presented here). The Li isoelectronic lines have different
statistical properties with respect to the lines from other sequences, due to
the extended high temperature tail of their contribution functions. However,
this is not the case for Fe XXIV which may be used as a diagnostic of the
coronal heating function. We also show that the power-law index of the heating
function is effectively preserved when a line is observed by a wide-band
imaging instrument rather than a spectromenter
Plasma Diagnostics and Magnetic Complexity of a Post-Flare Active Region with Hinode/XRT: Spatial and Temporal Evolution
Flares are localized phenomena in active regions, but the magnetic and plasma responses may propagate to a larger area. In this work we investigate the temporal evolution of a flare in an active region with particular attention to the morphological details, and to the temperature and emission measure diagnostics allowed by Hinode/XRT
On the nature of prominence emission observed by SDO/AIA
The Prominence-Corona Transition Region (PCTR) plays a key role in the
thermal and pressure equilibrium of solar prominences. Our knowledge of this
interface is limited and several major issues remain open, including the
thermal structure and, in particular, the maximum temperature of the detectable
plasma. The high signal-to-noise ratio of images obtained by the Atmospheric
Imaging Assembly (AIA) on NASA's Solar Dynamics Observatory clearly show that
prominences are often seen in emission in the 171 and 131 bands. We investigate
the temperature sensitivity of these AIA bands for prominence observation, in
order to infer the temperature content in an effort to explain the emission.
Using the CHIANTI atomic database and previously determined prominence
differential emission measure distributions, we build synthetic spectra to
establish the main emission-line contributors in the AIA bands. We find that
the Fe IX line always dominates the 171 band, even in the absence of plasma at
> 10^6 K temperatures, while the 131 band is dominated by Fe VIII. We conclude
that the PCTR has sufficient plasma emitting at > 4 10^5 K to be detected by
AIA.Comment: accepted Ap
use of the electronic nose on products of cinta senese pigs
The use of a quartz microbalance based (QMB) electronic nose for feed traceability of fresh and cured fat of Cinta Senese pigs has been evaluated. Thirty-three pigs were fed different feeding during fattening: "three months chestnut" (3-CH), "1 month chestnut" (1-CH) "fed commercial feedstuff" (0-CH). Fresh fat and cured lard of each animal were analysed. Overall data set was analysed by factorial analysis to test if the instruments allowed a satisfactory pattern separation among groups. Afterwards, on the three factors generated by factorial analysis, a GLM procedure was applied to estimate effects such as: feeding type, operative temperature, day of analysis, order within day, layer of the subcutaneous fat. The results showed a clear separation according to feeding regimen in fresh fat only, especially between 1-CH and 0-CH, but also a strong effect of the other sources of variability. Concerning this, the date of analysis had a significant effect on each factor generated by factorial analysis that invalidated the discrimination obtained
Linomide blocks angiogenesis by breast carcinoma vascular endothelial growth factor transfectants.
The blocking of angiogenesis provides a novel therapeutic target to inhibit tumour spreading. In this study, we investigated the effect of linomide on angiogenesis induced in vivo by highly angiogenic breast carcinoma cells. The rabbit cornea was used to assess neovascular growth in the absence of a tumour mass. MCF-7 cells stably transfected with the cDNA encoding for vascular endothelial growth factor 121 (VEGF121) (V12 clone) were used to elicit a potent VEGF-dependent corneal angiogenesis. After tumour cell implant, albino rabbits received 100 mg kg(-1) day(-1) linomide for 5 consecutive days. Daily observation of neovascular progression indicated that linomide blocked angiogenesis. The antiangiogenic effect of linomide was apparent within 48 h from the beginning of the treatment and was both angiosuppressive and angiostatic. The block of neovascular growth lasted over 10 days from treatment suspension, and preformed vessels, which had regressed, remained dormant, suggesting the persistence of unfavourable conditions for capillary progression. Linomide (50-200 microg ml[-1]) was not cytotoxic in vitro on resting capillary endothelial cells but blocked endothelial cell replication induced by VEGF. Our data indicate that linomide can efficiently and persistently block VEGF-dependent angiogenesis in vivo in the absence of a growing tumour mass. These data suggest that linomide could be a chemopreventive drug in breast cancer patients and a valuable tool in clinical settings in which metastatic spreading occurs in the absence of a detectable tumour mass
The IkB kinase inhibitor nuclear factor-kB essential modulator–binding domain peptide for inhibition of balloon injury-induced neointimal formation
Objective—The activation of nuclear factor-kB (NF-kB) is a crucial step in the arterial wall’s response to injury. The
identification and characterization of the NF-kB essential modulator– binding domain (NBD) peptide, which can block
the activation of the IkB kinase complex, have provided an opportunity to selectively abrogate the inflammation-induced
activation of NF-kB. The aim of the present study was to evaluate the effect of the NBD peptide on neointimal
formation.<br></br>
Methods and Results—In the rat carotid artery balloon angioplasty model, local treatment with the NBD peptide (300
microg/site) significantly reduced the number of proliferating cells at day 7 (by 40%; P<0.01) and reduced injury-induced neointimal formation (by 50%; P<0.001) at day 14. These effects were associated with a significant reduction of NF-kB activation and monocyte chemotactic protein-1 expression in the carotid arteries of rats treated with the peptide. In addition, the NBD peptide (0.01 to 1 micromol/L) reduced rat smooth muscle cell proliferation, migration, and invasion in
vitro. Similar results were observed in apolipoprotein E-/-, mice in which the NBD peptide (150 microg/site) reduced wire-induced neointimal formation at day 28 (by 47%; P<0.01).<br></br>
Conclusion—The NBD peptide reduces neointimal formation and smooth muscle cell proliferation/migration, both effects
associated with the inhibition of NF-kB activation
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