21,849 research outputs found
Method and apparatus for securing to a spacecraft Patent
Method and apparatus for connecting two spacecraft with probe of one inserted in rocket engine nozzle of other spacecraf
On the electrical double layer contribution to the interfacial tension of protein crystals
We study the electrical double layer at the interface between a protein
crystal and a salt solution or a dilute solution of protein, and estimate the
double layer's contribution to the interfacial tension of this interface. This
contribution is negative and decreases in magnitude with increasing salt
concentration. We also consider briefly the interaction between a pair of
protein surfaces.Comment: 6 pages, 3 figures, revtex
Continuum feedback control of a Rayleigh- Taylor type instability
Continuum feedback control of Rayleigh-Taylor instabilit
Observation and Modeling of Coronal "Moss" With the EUV Imaging Spectrometer on Hinode
Observations of transition region emission in solar active regions represent
a powerful tool for determining the properties of hot coronal loops. In this
Letter we present the analysis of new observations of active region moss taken
with the Extreme Ultraviolet Imaging Spectrometer (EIS) on the \textit{Hinode}
mission. We find that the intensities predicted by steady, uniformly heated
loop models are too intense relative to the observations, consistent with
previous work. To bring the model into agreement with the observations a
filling factor of about 16% is required. Furthermore, our analysis indicates
that the filling factor in the moss is nonuniform and varies inversely with the
loop pressure
Constraints on the Heating of High Temperature Active Region Loops: Observations from Hinode and SDO
We present observations of high temperature emission in the core of a solar
active region using instruments on Hinode and SDO. These multi-instrument
observations allow us to determine the distribution of plasma temperatures and
follow the evolution of emission at different temperatures. We find that at the
apex of the high temperature loops the emission measure distribution is
strongly peaked near 4 MK and falls off sharply at both higher and lower
temperatures. Perhaps most significantly, the emission measure at 0.5 MK is
reduced by more than two orders of magnitude from the peak at 4 MK. We also
find that the temporal evolution in broad-band soft X-ray images is relatively
constant over about 6 hours of observing. Observations in the cooler SDO/AIA
bandpasses generally do not show cooling loops in the core of the active
region, consistent with the steady emission observed at high temperatures.
These observations suggest that the high temperature loops observed in the core
of an active region are close to equilibrium. We find that it is possible to
reproduce the relative intensities of high temperature emission lines with a
simple, high-frequency heating scenario where heating events occur on time
scales much less than a cooling time. In contrast, low-frequency heating
scenarios, which are commonly invoked to describe nanoflare models of coronal
heating, do not reproduce the relative intensities of high temperature emission
lines and predict low-temperature emission that is approximately an order of
magnitude too large. We also present an initial look at images from the SDO/AIA
94 A channel, which is sensitive to Fe XVIII.Comment: Movies are available at
http://tcrb.nrl.navy.mil/~hwarren/temp/papers/active_region_core/ Paper has
been refereed and revise
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