527 research outputs found
Diffusive hidden Markov model characterization of DNA looping dynamics in tethered particle experiments
In many biochemical processes, proteins bound to DNA at distant sites are
brought into close proximity by loops in the underlying DNA. For example, the
function of some gene-regulatory proteins depends on such DNA looping
interactions. We present a new technique for characterizing the kinetics of
loop formation in vitro, as observed using the tethered particle method, and
apply it to experimental data on looping induced by lambda repressor. Our
method uses a modified (diffusive) hidden Markov analysis that directly
incorporates the Brownian motion of the observed tethered bead. We compare
looping lifetimes found with our method (which we find are consistent over a
range of sampling frequencies) to those obtained via the traditional
threshold-crossing analysis (which can vary depending on how the raw data are
filtered in the time domain). Our method does not involve any time filtering
and can detect sudden changes in looping behavior. For example, we show how our
method can identify transitions between long-lived, kinetically distinct states
that would otherwise be difficult to discern
Time-odd components in the mean field of rotating superdeformed nuclei
Rotation-induced time-odd components in the nuclear mean field are analyzed
using the Hartree-Fock cranking approach with effective interactions SIII,
SkM*, and SkP. Identical dynamical moments are obtained for
pairs of superdeformed bands Tb(2)--Dy(1) and
Gd(2)--Tb(1). The corresponding relative alignments strongly
depend on which time-odd mean-field terms are taken into account in the
Hartree-Fock equations.Comment: 23 pages, ReVTeX, 6 uuencoded postscript figures include
Spin-rotor Interpretation of Identical Bands and Quantized Alignment in Superdeformed A 190 Nuclei
The ``identical'' bands in superdeformed mercury, thallium, and lead nuclei
are interpreted as examples of orbital angular momentum rotors with the weak
spin-orbit coupling of pseudo- symmetries and supersymmetries.Comment: 15 pages, revtex 3.0, 7 figures available upon request from
[email protected]
Relative \u3csup\u3e235\u3c/sup\u3eU(\u3cem\u3en,γ\u3c/em\u3e) and (\u3cem\u3en,f\u3c/em\u3e) Cross Sections From \u3csup\u3e235\u3c/sup\u3eU(\u3cem\u3ed,pγ\u3c/em\u3e) and (\u3cem\u3ed,pf\u3c/em\u3e)
The internal surrogate ratio method allows for the determination of an unknown cross section, such as (n,γ), relative to a better-known cross section, such as (n,f), by measuring the relative exit-channel probabilities of a surrogate reaction that proceeds through the same compound nucleus. The validity of the internal surrogate ratio method is tested by comparing the relative γ and fission exit-channel probabilities of a 236U∗ compound nucleus, formed in the 235U(d,p) reaction, to the known 235U(n,γ) and (n,f) cross sections. A model-independent method for measuring the γ-channel yield is presented and used
Gd-149:What's confirmed? What's new?
A long run performed with EUROGAM II allowed remeasuring the Gd-149 superdeformed (SD) band 1. The Delta I = 4 bifurcation in band 1 is confirmed and two resolved gamma-ray transitions linking the SD band 1 and the normal deformed states have been observed
Gd-149:What's confirmed? What's new?
A long run performed with EUROGAM II allowed remeasuring the Gd-149 superdeformed (SD) band 1. The Delta I = 4 bifurcation in band 1 is confirmed and two resolved gamma-ray transitions linking the SD band 1 and the normal deformed states have been observed
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