60 research outputs found
Characterization of the seismic environment at the Sanford Underground Laboratory, South Dakota
An array of seismometers is being developed at the Sanford Underground
Laboratory, the former Homestake mine, in South Dakota to study the properties
of underground seismic fields and Newtonian noise, and to investigate the
possible advantages of constructing a third-generation gravitational-wave
detector underground. Seismic data were analyzed to characterize seismic noise
and disturbances. External databases were used to identify sources of seismic
waves: ocean-wave data to identify sources of oceanic microseisms, and surface
wind-speed data to investigate correlations with seismic motion as a function
of depth. In addition, sources of events contributing to the spectrum at higher
frequencies are characterized by studying the variation of event rates over the
course of a day. Long-term observations of spectral variations provide further
insight into the nature of seismic sources. Seismic spectra at three different
depths are compared, establishing the 4100-ft level as a world-class low
seismic-noise environment.Comment: 29 pages, 16 figure
Half-Life Systematics across the N=126 Shell Closure:Role of First-Forbidden Transitions in the beta Decay of Heavy Neutron-Rich Nuclei
This Letter reports on a systematic study of β-decay half-lives of neutron-rich nuclei around doubly magic ^{208}Pb. The lifetimes of the 126-neutron shell isotone ^{204}Pt and the neighboring ^{200-202}Ir, ^{203}Pt, ^{204}Au are presented together with other 19 half-lives measured during the "stopped beam" campaign of the rare isotope investigations at GSI collaboration. The results constrain the main nuclear theories used in calculations of r-process nucleosynthesis. Predictions based on a statistical macroscopic description of the first-forbidden β strength reveal significant deviations for most of the nuclei with N<126. In contrast, theories including a fully microscopic treatment of allowed and first-forbidden transitions reproduce more satisfactorily the trend in the measured half-lives for the nuclei in this region, where the r-process pathway passes through during β decay back to stability
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SDS induced conformational changes in the combining site of anti-trinitrophenyl antibodies. A kinetic study
The conformational stability of the combining sites of high affinity anti-TNP antibodies in the presence of SDS has been investigated by using several novel fluorescent and spectroscopic probes. Kinetic studies employing these probes along with circular dichroism measurements indicate that the binding of SDS monomer to hydrophobic sites on the antibody molecule causes a very rapid increase in the accessibility of the combining site to water. The loss in the ability of these antibodies to bind hapten in SDS solution appears to depend upon much slower conformational transitions; however, the presence of bound homologous hapten is observed to enhance the resistance of the anti-TNP combining site to denaturation by SDS
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