8,737 research outputs found
Theoretical and experimental assessment of the non-linear scattering functions for the cad of non-linear microwave circuits
The Non-Linear Scattering Functions have been theoretically defined and experimentally measured for the linear-equivalent design of non-linear circuits in arbitrary large signal conditions. Non-linear measures and simulations have been compared, with good agreement. Linear CAD concepts can therefore be extended to non-linear circuits in a rigorous way
High-field irreversible moment reorientation in the antiferromagnet FeTe
Magnetization measurements have been performed on single-crystalline
FeTe in pulsed magnetic fields up to 53 T
and temperatures from 4.2 to 65 K. At K, a non-reversible reorientation
of the antiferromagnetic moments is observed at T as the pulsed
field is on the rise. No anomaly is observed at during the fall of the
field and, as long as the temperature is unchanged, during both rises and falls
of additional field pulses. The transition at is reactivated if the
sample is warmed up above the N\'{e}el temperature K and cooled
down again. The magnetic field-temperature phase diagram of FeTe in
is also investigated. We present the temperature
dependence of , as well as that of the antiferromagnetic-to-paramagnetic
borderline in temperatures above 40 K.Comment: 5 pages, 4 figure
Nanosized patterns as reference structures for macroscopic transport properties and vortex phases in YBCO films
This paper studies the striking correlation between nanosized structural
patterns in YBCO films and macroscopic transport current. A nanosized network
of parallel Josephson junctions laced by insulating dislocations is almost
mimicking the grain boundary structural network. It contributes to the
macroscopic properties and accounts for the strong intergranular pinning across
the film in the intermediate temperature range. The correlation between the two
networks enables to find out an outstanding scaling law in the (Jc,B) plane and
to determine meaningful parameters concerning the matching between the vortex
lattice and the intergranular defect lattice. Two asymptotic behaviors of the
pinning force below the flux flow regime are checked: the corresponding vortex
phases are clearly individuated.Comment: 4 pages, 4 figure
Recommended from our members
Shocks and PDRs in an intermediate mass star forming globule: the case of IC1396N
The dark globule IC1396N is a typical example of a star formation process induced by radiation driven implosion due to the strong UV field from a nearby O6 star. The IRAS source embedded in the globule and its associated molecular outflow have been observed with the Long Wavelength Spectrometer (LWS) on ISO revealing an extremely rich spectrum including: CO rotational lines from J=14-13 up to J=28-27, rotational lines from ortho-H2O, OH lines involving the first four rotational levels of both ladders, atomic (OI 63μm, OI 145μm) and ionic (CII 157μm, OIII 52μm, OIII 88μm) lines. A complex picture arises, where an externally illuminated PDR coexists with strong C-shocks within IC1396N and whose origin is not clear
Baseband Predistortion Lineariser Using Direct Spline Computation
A baseband predistorter is presented. Key features of the predistorter resides in the use of cubic splines interpolation to generate predistorted input data to the power amplifier, resulting in a reduction of computational effort with respect to traditional polynomial interpolators. Simulated behaviour of the proposed scheme is presented, demonstrating the effectiveness of the approach
Can Ptilinopus greyii (Columbidae) Disperse Seeds in New Caledonia’s Dry Forests?
v. ill. 23 cm.QuarterlyConservation of endangered habitats of South Pacific islands is partially dependent on activity of seed dispersers. In consuming fruits, animals can spread seeds from parent plants to distant sites, thus contributing to plant regeneration and colonization of new sites. In the dry forests of New Caledonia, the red-bellied fruit-dove, Ptilinopus greyii, is a potential disperser of many fleshyfruited species. Trials with a captive bird showed that gut passage enhanced seed germination for Diospyros fasciculosa and Mimusops elengi but not for Vitex cf. collina, compared with whole fruits. Gut passage did not shorten duration of seed dormancy, which is consistent with evidence of a simple deinhibition effect for D. fasciculosa and M. elengi. Minimum Retention Time (MRT) of seeds in the gut differed significantly between the three tree species, from a mean of 17.4 min for D. fasciculosa to a mean of 52.4 min for M. elengi. These times are longer than observed foraging times in fruiting trees, potentially making this fruit-dove an effective seed disperser
Recommended from our members
High-J CO line emission from young stellar objects: from ISO to FIRST
we present the CO pure rotational spectrum at high J (Jup14) obtained with the Long Wavelength Spectrometer (LWS) on board of the ISO satellite towards molecular outflows exciting sources in nearby star formation regions. The physical conditions, derived using an LVG model for the line emission, indicate the presence of warm and dense gas, probably shock excited. The model fits show that often the bulk of this CO emission is expected in the spectral range that will be covered by FIRST, indicating the potentiality of this satellite to trace the warm component of gas emission in young stellar objects
Strong-coupling analysis of scanning tunneling spectra in BiSrCaCuO
We study a series of spectra measured in the superconducting state of
optimally-doped Bi-2223 by scanning tunneling spectroscopy. Each spectrum, as
well as the average of spectra presenting the same gap, is fitted using a
strong-coupling model taking into account the band structure, the BCS gap, and
the interaction of electrons with the spin resonance. After describing our
measurements and the main characteristics of the strong-coupling model, we
report the whole set of parameters determined from the fits, and we discuss
trends as a function of the gap magnitude. We also simulate angle-resolved
photoemission spectra, and compare with recent experimental results.Comment: Published versio
Recommended from our members
ISO-LWS grating spectroscopy: the case of R CrA star forming region
We present the far infrared spectra of the R CrA star forming region obtained with ISO-LWS. We collected a pointed observation on the Herbig Ae star R CrA and a raster scan covering the surrounding region, where HH100 (with its exciting source) and the pre-Main Sequence star T CrA are located. The OI 63μm and the CII 158μm lines have been detected in all the pointed positions, with a ratio consistent with PDR excitation. CO rotational lines (between Jup=14 and Jup=19) are detected on R CrA; from their intensities we derived, using a LVG model, the density and temperature of the emitting region. Other molecular transitions (OH and H2O) have been detected on the investigated objects; the derived cooling of all the molecular species is in agreement with C-shock as the likely excitation mechanism. The continuum emission of R CrA peaks around 100μm (as expected for a Herbig star) while the other sources (T CrA, HH100) show increasing continua up to ~200μm, indicating that they are probably less evolved sources
- …