2,169 research outputs found
Study of excitation transfer in laser dye mixtures by direct measurement of fluorescence lifetime
By directly measuring the donor fluorescence lifetime as a function of acceptor concentration in the laser dye mixture Rhodamine 6G-Cresyl violet, we found that the Stern-Volmer relation is obeyed, from which the rate of excitation transfer is determined. The experimental results indicate that the dominant mechanism responsible for the efficient excitation transfer is that of resonance transfer due to long range dipole-dipole interaction
Temporal constraints of the word blindness posthypnotic suggestion on Stroop task performance
The present work investigated possible temporal constraints on the posthypnotic word blindness
suggestion effect. In a completely within-subjects and counterbalanced design 19 highly suggestible
individuals performed the Stroop task both with and without a posthypnotic suggestion that they
would be unable to read the word dimension of the Stroop stimulus, both when response–stimulus
interval (RSI) was short (500 ms) or equivalent to previous studies (3500 ms). The suggestion
reduced Stroop interference in the short RSI condition (54 vs. 6 ms) but not in the long RSI condition
(52 vs. 56 ms), and did not affect Stroop facilitation. Our results suggest that response to the
suggestion involves reactive top-down control processes that persist only if levels of activation can
be maintained
Application of the ex-Gaussian function to the effect of the word blindness suggestion on Stroop task performance suggests no word blindness
The aim of the present paper was to apply the ex-Gaussian function to data reported by Parris et al. (2012) given its utility in studies involving the Stroop task. Parris et al. showed an effect of the word blindness suggestion when Response-Stimulus Interval (RSI) was 500 ms but not when it was 3500 ms. Analysis revealed that: (1) The effect of the suggestion on interference is observed in μ, supporting converging evidence indicating the suggestion operates over response competition mechanisms; and, (2) Contrary to Parris et al. an effect of the suggestion was observed in μ when RSI was 3500 ms. The reanalysis of the data from Parris et al. (2012) supports the utility of ex-Gaussian analysis in revealing effects that might otherwise be thought of as absent. We suggest that word reading itself is not suppressed by the suggestion but instead that response conflict is dealt with more effectively. © 2013 Parris, Dienes and Hodgson
Modularity and 4D-2D spectral equivalences for large-N gauge theories with adjoint matter
In recent work, we demonstrated that the confined-phase spectrum of
non-supersymmetric pure Yang-Mills theory coincides with the spectrum of the
chiral sector of a two-dimensional conformal field theory in the large-
limit. This was done within the tractable setting in which the gauge theory is
compactified on a three-sphere whose radius is small compared to the strong
length scale. In this paper, we generalize these observations by demonstrating
that similar results continue to hold even when massless adjoint matter fields
are introduced. These results hold for both thermal and -twisted
partition functions, and collectively suggest that the spectra of large-
confining gauge theories are organized by the symmetries of two-dimensional
conformal field theories.Comment: 51 pages, LaTeX, 3 figure
Kaluza-Klein States versus Winding States: Can Both Be Above the String Scale?
When closed strings propagate in extra compactified dimensions, a rich
spectrum of Kaluza-Klein states and winding states emerges. Since the masses of
Kaluza-Klein states and winding states play a reciprocal role, it is often
believed that either the lightest Kaluza-Klein states or the lightest winding
states must be at or below the string scale. In this paper, we demonstrate that
this conclusion is no longer true for compactifications with non-trivial shape
moduli. Specifically, we demonstrate that toroidal compactifications exist for
which all Kaluza-Klein states as well as all winding states are heavier than
the string scale. This observation could have important phenomenological
implications for theories with reduced string scales, suggesting that it is
possible to cross the string scale without detecting any states associated with
spacetime compactification.Comment: 8 pages, LaTeX, no figure
Dark Matter and Dark Forces from a supersymmetric hidden sector
We show that supersymmetric "Dark Force" models with gravity mediation are
viable. To this end, we analyse a simple string-inspired supersymmetric hidden
sector model that interacts with the visible sector via kinetic mixing of a
light Abelian gauge boson with the hypercharge. We include all induced
interactions with the visible sector such as neutralino mass mixing and the
Higgs portal term. We perform a detailed parameter space scan comparing the
produced dark matter relic abundance and direct detection cross sections to
current experiments.Comment: 40 pages, 11 figures comprising 21 plots. 4Mb total size. v2: figures
and references updated; typos removed; some extra explanations added. Matches
version published in PR
Adventures in Thermal Duality (II): Towards a Duality-Covariant String Thermodynamics
In a recent companion paper, we observed that the rules of ordinary
thermodynamics generally fail to respect thermal duality, a symmetry of string
theory under which the physics at temperature T is related to the physics at
the inverse temperature 1/T. Even when the free energy and internal energy
exhibit the thermal duality symmetry, the entropy and specific heat are defined
in such a way that this symmetry is destroyed. In this paper, we propose a
modification of the traditional definitions of these quantities, yielding a
manifestly duality-covariant thermodynamics. At low temperatures, these
modifications produce "corrections" to the standard definitions of entropy and
specific heat which are suppressed by powers of the string scale. These
corrections may nevertheless be important for the full development of a
consistent string thermodynamics. We find, for example, that the
string-corrected entropy can be smaller than the usual entropy at high
temperatures, suggesting a possible connection with the holographic principle.
We also discuss some outstanding theoretical issues prompted by our approach.Comment: 31 pages, 6 figures, 1 conversatio
- …