889 research outputs found
Novel antibodies against RCD-8 as a tool to study processing bodies
Aim. To develop the model system for processing bodies (PBs) state monitoring and accomplish it in the future as a possible read-out of mTOR activity in mammalian cells. Methods. In course of this study we raised polyclonal antibodies against one of the PBs scaffold proteins – RCD-8 and employed cell imaging technique. Results. It has been shown that the obtained antibodies recognize the intracellular structures, namely PBs. The detected protein co-localized with known marker of PBs – DCP1a, and partly with marker of SGs – CPEB. Conclusions. Based on changes of PBs number and size in cells after exposure to known inductors or inhibitors of PB formation we prove the specificity of generated antibodies and possibility of their application for studies on the processing bodies dynamics controlled by mTOR-dependent signalin
Improved Constraints on the Preferential Heating and Acceleration of Oxygen Ions in the Extended Solar Corona
We present a detailed analysis of oxygen ion velocity distributions in the
extended solar corona, based on observations made with the Ultraviolet
Coronagraph Spectrometer (UVCS) on the SOHO spacecraft. Polar coronal holes at
solar minimum are known to exhibit broad line widths and unusual intensity
ratios of the O VI 1032, 1037 emission line doublet. The traditional
interpretation of these features has been that oxygen ions have a strong
temperature anisotropy, with the temperature perpendicular to the magnetic
field being much larger than the temperature parallel to the field. However,
recent work by Raouafi and Solanki suggested that it may be possible to model
the observations using an isotropic velocity distribution. In this paper we
analyze an expanded data set to show that the original interpretation of an
anisotropic distribution is the only one that is fully consistent with the
observations. It is necessary to search the full range of ion plasma parameters
to determine the values with the highest probability of agreement with the UVCS
data. The derived ion outflow speeds and perpendicular kinetic temperatures are
consistent with earlier results, and there continues to be strong evidence for
preferential ion heating and acceleration with respect to hydrogen. At
heliocentric heights above 2.1 solar radii, every UVCS data point is more
consistent with an anisotropic distribution than with an isotropic
distribution. At heights above 3 solar radii, the exact probability of isotropy
depends on the electron density chosen to simulate the line-of-sight
distribution of O VI emissivity. (abridged abstract)Comment: 19 pages (emulateapj style), 13 figures, ApJ, in press (v. 679; May
20, 2008
Transition Region Emission and Energy Input to Thermal Plasma During the Impulsive Phase of Solar Flares
The energy released in a solar flare is partitioned between thermal and
non-thermal particle energy and lost to thermal conduction and radiation over a
broad range of wavelengths. It is difficult to determine the conductive losses
and the energy radiated at transition region temperatures during the impulsive
phases of flares. We use UVCS measurements of O VI photons produced by 5 flares
and subsequently scattered by O VI ions in the corona to determine the 5.0 <
log T < 6.0 transition region luminosities. We compare them with the rates of
increase of thermal energy and the conductive losses deduced from RHESSI and
GOES X-ray data using areas from RHESSI images to estimate the loop volumes,
cross-sectional areas and scale lengths. The transition region luminosities
during the impulsive phase exceed the X-ray luminosities for the first few
minutes, but they are smaller than the rates of increase of thermal energy
unless the filling factor of the X-ray emitting gas is ~ 0.01. The estimated
conductive losses from the hot gas are too large to be balanced by radiative
losses or heating of evaporated plasma, and we conclude that the area of the
flare magnetic flux tubes is much smaller than the effective area measured by
RHESSI during this phase of the flares. For the 2002 July 23 flare, the energy
deposited by non-thermal particles exceeds the X-ray and UV energy losses and
the rate of increase of the thermal energy.Comment: 20 pages, 3 figures To appear in Ap
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Moving toward multilateral mechanisms for the fuel cycle
Multilateral mechanisms for the fuel cycle are seen as a potentially important way to create an industrial infrastructure that will support a renaissance and at the same time not contribute to the risk of nuclear proliferation. In this way, international nuclear fuel cycle centers for enrichment can help to provide an assurance of supply of nuclear fuel that will reduce the likelihood that individual states will pursue this sensitive technology, which can be used to produce nuclear material directly usable nuclear weapons. Multinational participation in such mechanisms can also potentially promote transparency, build confidence, and make the implementation of IAEA safeguards more effective or more efficient. At the same time, it is important to ensure that there is no dissemination of sensitive technology. The Russian Federation has taken a lead role in this area by establishing an International Uranium Enrichment Center (IUEC) for the provision of enrichment services at its uranium enrichment plant located at the Angarsk Electrolysis Chemical Complex (AECC). This paper describes how the IUEe is organized, who its members are, and the steps that it has taken both to provide an assured supply of nuclear fuel and to ensure protection of sensitive technology. It also describes the relationship between the IUEC and the IAEA and steps that remain to be taken to enhance its assurance of supply. Using the IUEC as a starting point for discussion, the paper also explores more generally the ways in which features of such fuel cycle centers with multinational participation can have an impact on safeguards arrangements, transparency, and confidence-building. Issues include possible lAEA safeguards arrangements or other links to the IAEA that might be established at such fuel cycle centers, impact of location in a nuclear weapon state, and the transition by the IAEA to State Level safeguards approaches
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