24,245 research outputs found
Sm-Nd isotopic systematics of the ancient Gneiss complex, southern Africa
In order to shed some new light on the question of the absolute and relative ages of the Ancient Gneiss Complex and Onverwacht Group, a Sm-Nd whole-rock and mineral isochron study of the AGC was begun. At this point, the whole-rock study of samples from the Bimodal Suite selected from those studied for their geochemical characteristics by Hunter et al., is completed. These results and their implications for the chronologic evolution of the Kaapvaal craton and the sources of these ancient rocks are discussed
New broad 8Be nuclear resonances
Energies, total and partial widths, and reduced width amplitudes of 8Be
resonances up to an excitation energy of 26 MeV are extracted from a coupled
channel analysis of experimental data. The presence of an extremely broad J^pi
= 2^+ ``intruder'' resonance is confirmed, while a new 1^+ and very broad 4^+
resonance are discovered. A previously known 22 MeV 2^+ resonance is likely
resolved into two resonances. The experimental J^pi T = 3^(+)? resonance at 22
MeV is determined to be 3^-0, and the experimental 1^-? (at 19 MeV) and 4^-?
resonances to be isospin 0.Comment: 16 pages, LaTe
Proteins of developing, mature and germinating seeds of phaseolus vulgaris
A number of methods have been used to extract, purify and characterise the major storage proteins of dry seeds of Phaseolus vulgaris L. cv. 'Seafarer'. Four fractions, which together account for the majority of the proteins solubilised by alkaline salt extractants and separated by pulyacrylamide gel electrophoresis, ' are described. The predominant protein, accounting for about 60% of the total protein content of the seed, is a vicilin-like protein, and is composed of two subunits, with molecular weights 50,000 and 47,000. A second protein fraction, prepared by zonal isoelectric precipitation, is a legumin-like protein; a third fraction was found to agglutinate erythrocytes. Amino acid compositions are presented for these protein fractions and their identity with storage proteins prepared in previous studies is discussed. The fourth fraction was not characterised. The protein content of protein bodies prepared by two methods was compared; the method of preparation was found to have a significant effect on the apparent distribution of both storage proteins and trypsin inhibitor activity. Variations in the distribution of storage proteins within the cotyledon are also described. The formation of storage protein during seed development and its subsequent mobilisation during seed germination was followed by SDS gel electrophoresis. Changes in proteolytic activity during germination were determined and attempts were made to identify the in vivo location of storage protein hydrolysis and the possible effect of endogenous inhibitors on this process
Superconducting and normal-state properties of the noncentrosymmetric superconductor Re6Zr
We systematically investigate the normal and superconducting properties of
non-centrosymmetric ReZr using magnetization, heat capacity, and
electrical resistivity measurements. Resistivity measurements indicate
ReZr has poor metallic behavior and is dominated by disorder. ReZr
undergoes a superconducting transition at K. Magnetization measurements give a lower critical
field, mT. The
Werthamer-Helfand-Hohenberg model is used to approximate the upper critical
field T which is close to
the Pauli limiting field of 12.35 T and which could indicate singlet-triplet
mixing. However, low-temperature specific-heat data suggest that ReZr is
an isotropic, fully gapped s-wave superconductor with enhanced electron-phonon
coupling. Unusual flux pinning resulting in a peak effect is observed in the
magnetization data, indicating an unconventional vortex state.Comment: 11 pages, 7 figures, 2 table
Probing the superconducting ground state of the noncentrosymmetric superconductors CaTSi3 (T = Ir, Pt) using muon-spin relaxation and rotation
The superconducting properties of CaTSi3 (where T = Pt and Ir) have been
investigated using muon spectroscopy. Our muon-spin relaxation results suggest
that in both these superconductors time-reversal symmetry is preserved, while
muon-spin rotation data show that the temperature dependence of the superfluid
density is consistent with an isotropic s-wave gap. The magnetic penetration
depths and upper critical fields determined from our transverse-field muon-spin
rotation spectra are found to be 448(6) and 170(6) nm, and 3800(500) and
1700(300) G, for CaPtSi3 and CaIrSi3 respectively. The superconducting
coherence lengths of the two materials have also been determined and are 29(2)
nm for CaPtSi3 and 44(4) nm for CaIrSi3.Comment: 6 pages, 7 figure
Time-reversal symmetry breaking in noncentrosymmetric superconductor Re6Hf:further evidence for unconventional behaviour in the alpha-Mn family of materials
The discovery of new families of unconventional superconductors is important
both experimentally and theoretically, especially if it challenges current
models and thinking. By using muon spin relaxation in zero-field, time-reversal
symmetry breaking has been observed in Re6Hf. Moreover, the temperature
dependence of the superfluid density exhibits s-wave superconductivity with an
enhanced electron-phonon coupling. This, coupled with the results from
isostructural Re6Zr, shows that the Re6X family are indeed a new and important
group of unconventional superconductors.Comment: 5 pages, 2 figures Accepted Physical Review B, Rapid Communicatio
TM digital image products for applications
Computer compatible tapes (CCTs) of LANDSAT 4 thematic mapper (TM) digital image products are compared and reviewed. The following tape formats are discussed: (1) raw band-sequential data (CCT-BT); (2) calibrated data (CCT-AT); and (3) geometrically resampled data (CCT-PT). Each format represents different steps in the process of producing fully corrected TM data. The CCT-BT images are uncorrected radiometrically or geometrically, CCT-AT data are radiometrically calibrated, and CCT-PT images are both radiometrically and geometrically corrected
TM digital image products for applications
The image characteristics of digital data generated by LANDSAT 4 thematic mapper (TM) are discussed. Digital data from the TM resides in tape files at various stages of image processing. Within each image data file, the image lines are blocked by a factor of either 5 for a computer compatible tape CCT-BT, or 4 for a CCT-AT and CCT-PT; in each format, the image file has a different format. Nominal geometric corrections which provide proper geodetic relationships between different parts of the image are available only for the CCT-PT. It is concluded that detector 3 of band 5 on the TM does not respond; this channel of data needs replacement. The empty bin phenomenon in CCT-AT images results from integer truncations of mixed-mode arithmetric operations
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