884 research outputs found
The hard X-ray burst spectrometer event listing, 1980 - 1985
This event listing is a comprehensive reference for the hard X-ray bursts detected with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission from the time of launch on February 14, 1980 to September 1985. Over 8000 X-ray events were detected in the energy range from 30 to approx. 500 keV with the vast majority being solar flares. The listing includes the start time, peak time, duration and peak rate of each event
The hard X-ray burst spectrometer event listing 1980, 1981 and 1982
A comprehensive reference for the hard X-ray bursts detected with the Hard X-Ray Burst Spectrometer on the Solar Maximum Mission for the time of launch on February 14, 1980 to March 1983 is provided. Over 6300 X-ray events were detected in the energy range from 30 to approx 500 keV with the vast majority being solar flares. The listing includes the start time, peak time, duration and peak rate of each event
The complete Hard X Ray Burst Spectrometer event list, 1980-1989
This event list is a comprehensive reference for all Hard X ray bursts detected with the Hard X Ray Burst Spectrometer on the Solar Maximum Mission from the time of launch on Feb. 14, 1980 to the end of the mission in Dec. 1989. Some 12,776 events were detected in the energy range 30 to 600 keV with the vast majority being solar flares. This list includes the start time, peak time, duration, and peak rate of each event
The hard X-ray burst spectrometer event listing 1980-1987
This event listing is a comprehensive reference for the Hard X-ray bursts detected with the Hard X-ray Burst Spectrometer on the Solar Maximum Mission from the time of launch 14 February 1980 to December 1987. Over 8600 X-ray events were detected in the energy range from 30 to approx. 600 keV with the vast majority being solar flares. The listing includes the start time, peak time, duration and peak rate of each event
The low-frequency response in the surface superconducting state of ZrB single crystal}
The large nonlinear response of a single crystal ZrB to an ac field
(frequency 40 - 2500 Hz) for has been observed. Direct
measurements of the ac wave form and the exact numerical solution of the
Ginzburg-Landau equations, as well as phenomenological relaxation equation,
permit the study of the surface superconducting states dynamics. It is shown,
that the low frequency response is defined by transitions between the
metastable superconducting states under the action of an ac field. The
relaxation rate which determines such transitions dynamics, is found.Comment: 7 pages, 11 figure
Grasses continue to trump trees at soil carbon sequestration following herbivore exclusion in a semiarid African savanna
Although studies have shown that mammalian herbivores often limit aboveground carbon storage in savannas, their effects on belowground soil carbon storage remain unclear. Using three sets of long‐term, large herbivore exclosures with paired controls, we asked how almost two decades of herbivore removal from a semiarid savanna in Laikipia, Kenya affected aboveground (woody and grass) and belowground soil carbon sequestration, and determined the major source (C3 vs. C4) of belowground carbon sequestered in soils with and without herbivores present. Large herbivore exclusion, which included a diverse community of grazers, browsers, and mixed‐feeding ungulates, resulted in significant increases in grass cover (~22%), woody basal area (~8 m2/ha), and woody canopy cover (31%), translating to a ~8.5 t/ha increase in aboveground carbon over two decades. Herbivore exclusion also led to a 54% increase (20.5 t/ha) in total soil carbon to 30‐cm depth, with ~71% of this derived from C4 grasses (vs. ~76% with herbivores present) despite substantial increases in woody cover. We attribute this continued high contribution of C4 grasses to soil C sequestration to the reduced offtake of grass biomass with herbivore exclusion together with the facilitative influence of open sparse woody canopies (e.g., Acacia spp.) on grass cover and productivity in this semiarid system
A microfabricated sensor for thin dielectric layers
We describe a sensor for the measurement of thin dielectric layers capable of
operation in a variety of environments. The sensor is obtained by
microfabricating a capacitor with interleaved aluminum fingers, exposed to the
dielectric to be measured. In particular, the device can measure thin layers of
solid frozen from a liquid or gaseous medium. Sensitivity to single atomic
layers is achievable in many configurations and, by utilizing fast, high
sensitivity capacitance read out in a feedback system onto environmental
parameters, coatings of few layers can be dynamically maintained. We discuss
the design, read out and calibration of several versions of the device
optimized in different ways. We specifically dwell on the case in which
atomically thin solid xenon layers are grown and stabilized, in cryogenic
conditions, from a liquid xenon bath
Magnus and Iordanskii Forces in Superfluids
The total transverse force acting on a quantized vortex in a superfluid is a
problem that has eluded a complete understanding for more than three decades.
In this letter I propose a remarkably simple argument, somewhat reminiscent of
Laughlin's beautiful argument for the quantization of conductance in the
quantum Hall effect, to define the superfluid velocity part of the transverse
force. This term is found to be . Although
this result does not seem to be overly controversial, this thermodynamic
argument based only on macroscopic properties of the superfluid does offer a
robust derivation. A recent publication by Thouless, Ao and Niu has
demonstrated that the vortex velocity part of the transverse force in a
homogeneous neutral superfluid is given by the usual form . A combination of these two independent results and the required
Galilean invariance yields that there cannot be any transverse force
proportional to the normal fluid velocity, in apparent conflict with
Iordanskii's theory of the transverse force due to phonon scattering by the
vortex.Comment: RevTex, 1 Encapsulated Postscript figur
Spin and orbital states in La1.5 Sr0.5 CoO4 studied by electronic structure calculations
Electronic structure of the layered perovskite La1.5Sr0.5CoO4 with a checkerboard Co2+/Co3+ charge order is studied, using the local-spin-density approximation plus Hubbard U calculations including also the spin-orbit coupling and multiplet effect. Our results show that the Co2+ ion is in a high spin state (HS, t(2g)(5)e(g)(2)) and Co3+ low spin state (LS, t(2g)(6)). Due to a small Co2+ t(2g) crystal field splitting, the spin-orbit interaction produces an orbital moment of 0.26 mu(B) and accounts for the observed easy in-plane magnetism. Moreover, we find that the Co3+ intermediate spin state (IS, t(2g)(5)e(g)(1)) has a multiplet splitting of several tenths of eV and the lowest-lying one is still higher than the LS ground state by 120 meV, and that the Co3+ HS state (t(2g)(4)e(g)(2)) is more unstable by 310 meV. Either the IS or HS Co3+ ions would give rise to a wrong magnetic order and anisotropy
Rydberg Wave Packets are Squeezed States
We point out that Rydberg wave packets (and similar ``coherent" molecular
packets) are, in general, squeezed states, rather than the more elementary
coherent states. This observation allows a more intuitive understanding of
their properties; e.g., their revivals.Comment: 7 pages of text plus one figure available in the literature, LA-UR
93-2804, to be published in Quantum Optics, LaTe
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