نتایج جستجو برای: beaming angle
تعداد نتایج: 131315 فیلتر نتایج به سال:
AbstructThe electrostatic-accelerator free-electron laser (EA-FEL) operating at mm wavelength is considered as a source for energy transfer through the atmosphere to a high altitude p~at~orm. The high average power and high efficiency attainable from appropriately designed EA-FEL make it a suitable candidate as an efficient source of mm-waves for power beaming from a ground station. Various asp...
Simultaneous observations of AKR emission using the four-spacecraft Cluster array were used to make the first direct measurements of the angular beaming patterns of individual bursts. By comparing the spacecraft locations and AKR burst locations, the angular beaming pattern was found to be narrowly confined to a plane containing the magnetic field vector at the source and tangent to a circle of...
I suggest that the beaming factor in bright ULXs varies as b ∝ ṁ, where ṁ is the Eddington ratio for accretion. This is required by the observed universal Lsoft ∝ T −4 relation between soft–excess luminosity and temperature, and is reasonable on general physical grounds. The beam scaling means that all observable properties of bright ULXs depend essentially only on the Eddington ratio ṁ, and th...
Three models of a flat universe of coupled matter and dark energies with different low-redshift parameterizations of the dark energy equation of state are considered. The dark energy is assumed to vary with time like the trace of the energy-momentum tensor of cosmic matter. In the radiation-dominated era the models reduce to standard cosmology. In the matter-dominated era they are, for modern v...
Background Circulating tumor DNA (ctDNA) is a potential source for tumor genome analysis. We explored the concordance between the mutational status of RAS in tumor tissue and ctDNA in metastatic colorectal cancer (mCRC) patients to establish eligibility for anti-epidermal growth factor receptor (EGFR) therapy. Patients and methods A prospective-retrospective cohort study was carried out. Tumo...
If gamma ray bursts are highly collimated, radiating into only a small fraction of the sky, the energy requirements of each event may be reduced by several (up to 4–6) orders of magnitude, and the event rate increased correspondingly. The large Lorentz factors (Γ ∼ 100) inferred from GRB spectra imply relativistic beaming of the gamma rays into an angle ∼ 1/Γ. We are at present ignorant of whet...
A brief overview of the concept of power laser beaming in space and its applications are presented. A direct solar-pumped iodine laser with the iodide t C & l lasant is described as an example of the power laser system.
Unified schemes for active galaxies: a clue from the missing Fanaroff-Riley type I quasar population
We link the lack of FR I type structure among quasars to the void of radio loud quasars below a critical disk luminosity of ∼ 10 erg/sec in the PG sample. We argue that the opening angle of the obscuring torus in radio loud quasars depends on the power of the central engine, approaching the jet’s beaming angle near the FR I/FR II break. Consequently, low power radio quasars would either be clas...
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