9,144 research outputs found
Hardware simulation of Ku-band spacecraft receiver and bit synchronizer, volume 1
A hardware simulation which emulates an automatically acquiring transmit receive spread spectrum communication and tracking system and developed for use in future NASA programs involving digital communications is considered. The system architecture and tradeoff analysis that led to the selection of the system to be simulated is presented
Hardware simulation of KU-band spacecraft receiver and bit synchronizer, phase 2, volume 1
The acquisition behavior of the PN subsystem of an automatically acquiring spacecraft receiver was studied. A symbol synchronizer subsystem was constructed and integrated into the composite simulation of the receiver. The overall performance of the receiver when subjected to anomalies such as signal fades was evaluated. Potential problems associated with PN/carrier sweep interactions were investigated
Assortative human pair-bonding for partner ancestry and allelic variation of the dopamine receptor D4 (DRD4) gene
The 7R allele of the dopamine receptor D4 gene has been associated with attention-deficit hyperactivity disorder and risk taking. On the cross-population scale, 7R allele frequencies have been shown to be higher in populations with more of a history of long-term migrations. It has also been shown that the 7R allele is associated with individuals having multiple-ancestries. Here we conduct a replication of this latter finding with two independent samples. Measures of subjects’ ancestry are used to examine past reproductive bonds. The individuals’ history of inter-racial/ancestral dating and their feelings about this are also assessed. Tentative support for an association between multiple ancestries and the 7R allele were found. These results are dependent upon the method of questioning subjects about their ancestries. Inter-racial dating and feelings about inter-racial pairing were not related to the presence of the 7R allele. This might be accounted for by secular trends that might have substantively altered the decision-making process employed when considering relationships with individuals from different groups. This study provides continued support for the 7R allele playing a role in migration and/or mate choice patterns. However, replications and extensions of this study are needed and must carefully consider how ancestry/race is assessed
Diffusional Relaxation in Random Sequential Deposition
The effect of diffusional relaxation on the random sequential deposition
process is studied in the limit of fast deposition. Expression for the coverage
as a function of time are analytically derived for both the short-time and
long-time regimes. These results are tested and compared with numerical
simulations.Comment: 9 pages + 2 figure
Probing nuclear skins and halos with elastic electron scattering
I investigate the elastic electron scattering off nuclei far from the
stability line. The effects of the neutron and proton skins and halos on the
differential cross sections are explored. Examples are given for the charge
distribution in Sn isotopes and its relation to the neutron skin. The neutron
halo in Li and the proton halo in B are also investigated.
Particular interest is paid to the inverse scattering problem and its
dependence on the experimental precision. These studies are of particular
interest for the upcoming electron ion colliders at the GSI and RIKEN
facilities.Comment: 27 pages, 9 figures, accepted for publication in J. Phys.
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