9,702 research outputs found
Absolute 1* quantum yields for the ICN A state by diode laser gain versus absorption spectroscopy
Absolute I* quantum yields were measured as a function of wavelength for room temperature photodissociation of the ICN A state continuum. The temperature yields are obtained by the technique of time-resolved diode laser gain-versus-absorption spectroscopy. Quantum yields are evaluated at seven wavelengths from 248 to 284 nm. The yield at 266 nm is 66.0 +/- 2% and it falls off to 53.4 +/- 2% and 44.0 +/- 4% at 284 and 248 respectively. The latter values are significantly higher than those obtained by previous workers using infrared fluorescence. Estimates of I* quantum yields obtained from analysis of CN photofragment rotational distributions, as discussed by other workers, are in good agreement with the I* yields. The results are considered in conjunction with recent theoretical and experimental work on the CN rotational distributions and with previous I* yield results
Resolving the radio nebula around beta Lyrae
In this paper we present high spatial resolution radio images of the puzzling
binary system beta Lyrae obtained with MERLIN at 5 GHz. We find a nebula
surrounding the binary with a brightness temperature of 11000+-700K
approximately 40AU across. This definitively confirms the thermal origin of the
radio emission, which is consistent with emission from the wind of the B6-8II
component (mass loss of order of 10^-7 Msun per year), ionized by the radiation
field of the hotter companion. This nebula, surrounding the binary, is the
proof that beta Layrae evolved in a non-conservative way, i. e. not all the
mass lost by the primary is accretted by the secondary, and present
measurements indicate that almost 0.015Msun had been lost from the system since
the onset of the Roche lobe overflow phase. Moreover, the nebula is aligned
with the jet-like structures inferred from recent optical measurements,
indicating a possible connection among them.Comment: 5 pages, 2 figures. Accepted for publication in A&
cFFR as an alternative to FFR: please do not contrast simplicity!
info:eu-repo/semantics/publishedVersio
Ohio's statewide land use inventory: An operational approach for applying LANDSAT data to state, regional and local planning programs
The programmatic, technical, user application, and cost factors associated with the development of an operational, statewide land use inventory from LANDSAT data are described. The LANDSAT multispectral data are subjected to geometrical and categorical processing to produce map files for each of the 200 fifteen (15) minute quads covering Ohio. Computer compatible tapes are rescanned to produce inventory tapes which identify eight (8) Level I land use categories and a variety of Level II categories. The inventory tapes are processed through a series of ten (10) software programs developed by the State of Ohio. The net result is a computerized inventory which can be displayed in map or tabular form for various geographic units, at a variety of scales and for selected categories of usage. The computerized inventory data files are applied to technical programs developed by the various state agencies to be used in state, regional, and local planning programs
Experimental evaluation of the operating temperature impact on solid oxide anode-supported fuel cells
The Cooper Pair Pump as a Quantized Current Source
A new charge quantization in a phase-polarized Cooper Pair Pump (CPP) is
proposed, based on the topological properties of its Hamiltonian ground state
over a three-dimensional parameter space . The charge is quantized
using a set of path in covering the surface of a torus, and is a
multiple of the integer Chern index of this surface. This quantization is
asymptotic but the pumped charge converges rapidly to the quantized value with
the increase in the path frequency. The topological nature of the current makes
this CPP implementation an excellent candidate for a metrological current
standard.Comment: 4 PRL page
Attosecond spectroscopy reveals alignment dependent core-hole dynamics in the ICl molecule.
The removal of electrons located in the core shells of molecules creates transient states that live between a few femtoseconds to attoseconds. Owing to these short lifetimes, time-resolved studies of these states are challenging and complex molecular dynamics driven solely by electronic correlation are difficult to observe. Here, we obtain few-femtosecond core-excited state lifetimes of iodine monochloride by using attosecond transient absorption on iodine 4d-16p transitions around 55 eV. Core-level ligand field splitting allows direct access of excited states aligned along and perpendicular to the ICl molecular axis. Lifetimes of 3.5 ± 0.4 fs and 4.3 ± 0.4 fs are obtained for core-hole states parallel to the bond and 6.5 ± 0.6 fs and 6.9 ± 0.6 fs for perpendicular states, while nuclear motion is essentially frozen on this timescale. Theory shows that the dramatic decrease of lifetime for core-vacancies parallel to the covalent bond is a manifestation of non-local interactions with the neighboring Cl atom of ICl
Two-color ionization of hydrogen by short intense pulses
Photoelectron energy spectra resulting by the interaction of hydrogen with
two short pulses having carrier frequencies, respectively, in the range of the
infrared and XUV regions have been calculated. The effects of the pulse
duration and timing of the X-ray pulse on the photoelectron energy spectra are
discussed. Analysis of the spectra obtained for very long pulses show that
certain features may be explained in terms of quantum interferences in the time
domain. It is found that, depending on the duration of the X-ray pulse, ripples
in the energy spectra separated by the infrared photon energy may appear.
Moreover, the temporal shape of the low frequency radiation field may be
inferred by the breadth of the photoelectron energy spectra.Comment: 12 pages, 8 figure
Replica bounds for diluted non-Poissonian spin systems
In this paper we extend replica bounds and free energy subadditivity
arguments to diluted spin-glass models on graphs with arbitrary, non-Poissonian
degree distribution. The new difficulties specific of this case are overcome
introducing an interpolation procedure that stresses the relation between
interpolation methods and the cavity method. As a byproduct we obtain
self-averaging identities that generalize the Ghirlanda-Guerra ones to the
multi-overlap case.Comment: Latex file, 15 pages, 2 eps figures; Weak point revised and
corrected; Misprints correcte
Numerical modeling of the rheological characteristic of olive paste under different conditioning treatments: Traditional malaxation, high-frequency ultrasound and microwave
Olive paste, a mixture of olive oil, vegetation water and solid particles, have a complex rheological behavior. Its viscosity (μ) cannot be considered as constant and depends on several parameters. The olive paste changes its rheological characteristics from the inlet to the outlet of the olive oil extraction line because of temperature increase and variation in fluid composition (i.e., solid-liquid m). A numerical analysis was carried out using different mathematical models to predict the apparent viscosity of olive paste as a function of the solids and olive oil volume fractions. Experimental trials were carried out processing the olive paste using different techniques: traditional malaxing (TM), the use of megasound (MS) and the use of microwaves (MW). The collected data consisted of apparent viscosity values, the related shear strain rates and the composition of the olive paste. These data were interpolated using a power law model whose parameters were determined by means of a linear regression in a bi-logarithmic scale at each step of the olive milling process. As a result of comparison with the experimental data, the different models were found to be quite effective for describing the relative viscosity behavior and the obtained solid volume fraction obtained after the three different processing methods confirms the best behavior of the MS technique. As a final consideration, the results of this work represent another step toward full comprehension of the physical characteristics of the olive paste finalizes to improve the solid-liquid separation in olive oil centrifugal decanters
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