111 research outputs found
A new median-based formula for the Black-Scholes-Merton Theory
The Black-Scholes-Merton (BSM) theory for price variation has been well
established in mathematical financial engineering. However, it has been
recognized that long-term outcomes in practice may divert from the
Black-Scholes formula, which is the expected value of the stochastic process of
price changes. While the expected value is expected for the long-run average of
infinite realizations of the same stochastic process, it may give an erroneous
picture of nearly every realization when the probability distribution is
skewed, as is the case for prices. Here we propose a new formula of the BSM
theory, which is based on the median of the stochastic process. This formula
makes a more realistic prediction for the long-term outcomes than the current
Black-Scholes formula
DSIF contributes to transcriptional activation by DNA-binding activators by preventing pausing during transcription elongation
The transcription elongation factor 5,6-dichloro-1-β-d-ribofuranosylbenzimidazole (DRB) sensitivity-inducing factor (DSIF) regulates RNA polymerase II (RNAPII) processivity by promoting, in concert with negative elongation factor (NELF), promoter-proximal pausing of RNAPII. DSIF is also reportedly involved in transcriptional activation. However, the role of DSIF in transcriptional activation by DNA-binding activators is unclear. Here we show that DSIF acts cooperatively with a DNA-binding activator, Gal4-VP16, to promote transcriptional activation. In the absence of DSIF, Gal4-VP16-activated transcription resulted in frequent pausing of RNAPII during elongation in vitro. The presence of DSIF reduced pausing, thereby supporting Gal4-VP16-mediated activation. We found that DSIF exerts its positive effects within a short time-frame from initiation to elongation, and that NELF does not affect the positive regulatory function of DSIF. Knockdown of the gene encoding the large subunit of DSIF, human Spt5 (hSpt5), in HeLa cells reduced Gal4-VP16-mediated activation of a reporter gene, but had no effect on expression in the absence of activator. Together, these results provide evidence that higher-level transcription has a stronger requirement for DSIF, and that DSIF contributes to efficient transcriptional activation by preventing RNAPII pausing during transcription elongation
Spin Wave Instability of Itinerant Ferromagnet
We show variationally that instability of the ferromagnetic state in the
Hubbard model is largely controlled by softening of a long-wavelength spin-wave
excitation, except in the over-doped strong-coupling region where the
individual-particle excitation becomes unstable first. A similar conclusion is
drawn also for the double exchange ferromagnet. Generally the spin-wave
instability may be regarded as a precursor of the metal-insulator transition.Comment: 11 pages, 8 figure
Physical Phenomenology of Phyllotaxis
We propose an evolutionary mechanism of phyllotaxis, regular arrangement of
leaves on a plant stem. It is shown that the phyllotactic pattern with the
Fibonacci sequence has a selective advantage, for it involves the least number
of phyllotactic transitions during plant growth
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