15,713 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
Transition region and chromospheric signatures of impulsive heating events. II. Modeling
Results from the Solar Maximum Mission showed a close connection between the hard X-ray (HXR) and transition
region (TR) emission in solar flares. Analogously, the modern combination of RHESSI and IRIS data can inform
the details of heating processes in ways that were never before possible. We study a small event that was observed
with RHESSI, IRIS, SDO, and Hinode, allowing us to strongly constrain the heating and hydrodynamical properties
of the flare, with detailed observations presented in a previous paper. Long duration redshifts of TR lines observed
in this event, as well as many other events, are fundamentally incompatible with chromospheric condensation on a
single loop. We combine RHESSI and IRIS data to measure the energy partition among the many magnetic strands
that comprise the flare. Using that observationally determined energy partition, we show that a proper
multithreaded model can reproduce these redshifts in magnitude, duration, and line intensity, while simultaneously
being well constrained by the observed density, temperature, and emission measure. We comment on the
implications for both RHESSI and IRIS observations of flares in general, namely that: (1) a single loop model is
inconsistent with long duration redshifts, among other observables; (2) the average time between energization of
strands is less than 10 s, which implies that for a HXR burst lasting 10 minutes, there were at least 60 strands
within a single IRIS pixel located on the flare ribbon; (3) the majority of these strands were explosively heated with
an energy distribution well described by a power law of slope »-1.6; (4) the multi-stranded model reproduces the
observed line profiles, peak temperatures, differential emission measure distributions, and densities
Seed Yield Prediction Models of Four Common Moist-Soil Plant Species in Texas
Seed production by moist-soil plant species often varies within and among managed wetlands and on larger landscapes. Quantifying seed production of moist-soil plants can be used to evaluate wetland management strategies and estimate wetland energetic carrying capacity, specifically for waterfowl. In the past, direct estimation techniques were used, but due to excessive personnel and time costs, other indirect methods have been developed. Because indirect seed yield models do not exist for moist-soil plant species in east-central or coastal Texas, we developed direct and indirect methods to model seed production on regional managed wetlands. In September 2004 and 2005, we collected Echinochloa crusgalli (barnyard grass), E. walterii (wild millet), E. colona (jungle rice), and Oryza sativa (cultivated rice) for phytomorphological measurements and seed yield modeling. Initial simple linear and point of origin regression analyses demonstrate strong relationships (P \u3c 0.001) among phytomorphological and dot grid methods in predicting seed production for all four species. These models should help regional wetland managers evaluate moist-soil management success and create models for seed production for other moist-soil plants in this region
Distribution of the second virial coefficients of globular proteins
George and Wilson [Acta. Cryst. D 50, 361 (1994)] looked at the distribution
of values of the second virial coefficient of globular proteins, under the
conditions at which they crystallise. They found the values to lie within a
fairly narrow range. We have defined a simple model of a generic globular
protein. We then generate a set of proteins by picking values for the
parameters of the model from a probability distribution. At fixed solubility,
this set of proteins is found to have values of the second virial coefficient
that fall within a fairly narrow range. The shape of the probability
distribution of the second virial coefficient is Gaussian because the second
virial coefficient is a sum of contributions from different patches on the
protein surface.Comment: 5 pages, including 3 figure
On-demand microwave generator of shaped single photons
We demonstrate the full functionality of a circuit that generates single
microwave photons on demand, with a wave packet that can be modulated with a
near-arbitrary shape. We achieve such a high tunability by coupling a
superconducting qubit near the end of a semi-infinite transmission line. A dc
superconducting quantum interference device shunts the line to ground and is
employed to modify the spatial dependence of the electromagnetic mode structure
in the transmission line. This control allows us to couple and decouple the
qubit from the line, shaping its emission rate on fast time scales. Our
decoupling scheme is applicable to all types of superconducting qubits and
other solid-state systems and can be generalized to multiple qubits as well as
to resonators.Comment: 10 pages, 7 figures. Published versio
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