Metabolite-driven mechanisms reveal chemical ecology of Lehmann Lovegrass (Eragrostis lehmanniana) invasion in North American semi-arid ecosystems
Not provided.
Life Sciences & Biomedicine - Other Topics↗
Engineering topics
Arnold, A.
Publications and source records attributed to Arnold, A..
Fungal endophytes of the invasive grass Eragrostis lehmanniana shift metabolic expression in response to native and invasive grasses
Not provided.
Environmental Sciences & Ecology↗
Superconducting radio frequency photoinjectors for CW-XFEL
A dependable and consistent electron source is a crucial requirement for the achievement of high-power free electron lasers (FELs). Over the past two decades, it has been demonstrated that photoinjectors based on SRF technology (SRF guns) are suitable for continuous wave (CW) beam generation. SRF guns possess both the high accelerating field gradients of normal conducting RF photoinjectors and the low power dissipation thanks to mature SRF cavity technology, and therefore have the potential to provide the high-brightness, high-current beams required for CW-XFELs. After the demonstration of the first SRF gun in Dresden-Rossendorf, several SRF gun programs based on different approaches have achieved promising progress and even succeeded in routine operation. SRF guns are expected to play an important role in XFEL facilities in the near future. In this paper, we give an overview of design concepts, important parameters and development status of the worldwide SRF gun projects.
47 OTHER INSTRUMENTATION↗
Experimental confirmation of efficient island divertor operation and successful neoclassical transport optimization in Wendelstein 7-X
We present recent highlights from the most recent operation phases of Wendelstein 7-X, the most advanced stellarator in the world. Stable detachment with good particle exhaust, low impurity content, and energy confinement times exceeding 100 ms, have been maintained for tens of seconds. Pellet fueling allows for plasma phases with reduced ion-temperature-gradient turbulence, and during such phases, the overall confinement is so good (energy confinement times often exceeding 200 ms) that the attained density and temperature profiles would not have been possible in less optimized devices, since they would have had neoclassical transport losses exceeding the heating applied in W7-X. This provides proof that the reduction of neoclassical transport through magnetic field optimization is successful. W7-X plasmas generally show good impurity screening and high plasma purity, but there is evidence of longer impurity confinement times during turbulence-suppressed phases.
neoclassical optimization↗
Observation of the development of individual clear air convective cells
A series of radar observations has been used to monitor the development of clear air convective cells. It is suggested that an airfield may be a source of such cells. The cells first appear at a distance of about 11 km, and are observed to be produced every four minutes. The emergence of separate cells supports the bubble theory of convection. After reaching maximum height, a typical decrease of 100-200 m occurs. Various methods used to estimate convective cell energy yield values of 10 to the 12th, 4 x 10 to the 11th, and 10 to the 11th J.
Arnold, A.↗
Radar derived spatial statistics of summer rain. Volume 1: Experiment description
An experiment was performed at Wallops Island, Virginia, to obtain a statistical description of summer rainstorms. Its purpose was to obtain information needed for design of earth and space communications systems in which precipitation in the earth's atmosphere scatters or attenuates the radio signal. Rainstorms were monitored with the high resolution SPANDAR radar and the 3-dimensional structures of the storms were recorded on digital tape. The equipment, the experiment, and tabulated data obtained during the experiment are described.
Katz, I.↗
Simultaneous observations of clear air convection by a pulse radar, an FM-CW radar, an acoustic sounder, and an instrumented aircraft
Explore the source record for details and available documents.
Arnold, A.↗
Vertical velocity structure and geometry of clear air convective elements
The paper discusses observations of individual convective elements with a high-power narrow-beam scanning radar, an FM-CW radar, and an acoustic sounder, including the determination of the vertical air velocity patterns of convective structures with the FM-CW radar and acoustic sounder. Data are presented which link the observed velocity structure and geometrical patterns to previously proposed models of boundary layer convection. It is shown that the high-power radar provides a clear three-dimensional picture of convective cells and fields over a large area with a resolution of 150 m, where the convective cells are roughly spherical. Analysis of time-height records of the FM-CW radar and acoustic sounder confirms the downdraft-entrainment mechanism of the convective cell. The Doppler return of the acoustic sounder and the insect-trail slopes on FM-CW radar records are independent but redundant methods for obtaining the vertical velocity patterns of convective structures.
Rowland, J. R.↗
Clear air convection - A close look at its evolution and structure
A unique experiment using advanced remote and direct sensing techniques was designed to investigate the detailed evolution and structure of clear-air convection. The measurements involved a high-power, narrow-beam pulse radar, a frequency modulated, continuous wave radar, an acoustic echo sounder, and instrumented aircraft. The various probing methods when used together complement each other and give a compatible and comprehensive description of the spatial and temporal evolution of clear-air convection.
Richter, J. H.↗