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Sex-related differences in chromatic sensitivity
Generally women are believed to be more discriminating than men in the use of colour names and this is often taken to imply superior colour vision. However, if both X-chromosome linked colour deficient males (~8%) and females (<1%) as well as heterozygote female carriers (~15%) are excluded from comparisons, then differences between men and women in red-green colour discrimination have been reported as not being significant (e.g., Pickford, 1944; Hood et al., 2006). We re-examined this question by assessing the performance of 150 males and 150 females on the Colour Assessment and Diagnosis (CAD) test (Rodriguez-Carmona, 2005). This is a sensitive test that yields small colour detection thresholds. The test employs direction-specific, moving, chromatic stimuli embedded in a background of random, dynamic, luminance contrast noise. A four-alternative, forced-choice procedure is employed to measure the subjectâs thresholds for detection of colour signals in 16 directions in colour space, while ensuring that the subject cannot make use of any residual luminance contrast signals. In addition, we measured the Rayleigh anomaloscope matches in a subgroup of 111 males and 114 females. All the age-matched males (30.8 ± 9.7) and females (26.7 ± 8.8) had normal colour vision as diagnosed by a battery of conventional colour vision tests. Females with known colour deficient relatives were excluded from the study. Comparisons between the male and female groups revealed no significant differences in anomaloscope midpoints (p=0.709), but a significant difference in matching ranges (p=0.040); females on average tended to have a larger mean range (4.11) than males (3.75). Females also had significantly higher CAD thresholds than males along the red-green (p=0.0004), but not along the yellow-blue discrimination axis. The differences between males and females in red-green discrimination may be related to the heterozygosity in X-linked cone photopigment expression common among females
Co-expression of C9orf72 related dipeptide-repeats over 1000 repeat units reveals age- and combination-specific phenotypic profiles in Drosophila
A large intronic hexanucleotide repeat expansion (GGGGCC) within the C9orf72 (C9orf72-SMCR8 Complex Subunit) locus is the most prevalent genetic cause of both Frontotemporal Dementia (FTD) and Motor Neuron Disease (MND). In patients this expansion is typically hundreds to thousands of repeat units in length. Repeat associated non-AUG translation of the expansion leads to the formation of toxic, pathological Dipeptide-Repeat Proteins (DPRs). To date there remains a lack of in vivo models expressing C9orf72 related DPRs with a repeat length of more than a few hundred repeats. As such our understanding of how physiologically relevant repeat length DPRs efect the nervous system in an ageing in vivo system remains limited. In this study we generated Drosophila models expressing DPRs over 1000 repeat units in length, a known pathological length in humans. Using these models, we demonstrate each DPR exhibits a unique, age-dependent, phenotypic and pathological profle. Furthermore, we show co-expression of specifc DPR combinations leads to distinct, age-dependent, phenotypes not observed through expression of single DPRs. We propose these models represent a unique, in vivo, tool for dissecting the molecular mechanisms implicated in disease pathology, opening up new avenues in the study of both MND and FTD
The Impact of new Execution Venues on European Equity Marketsâ Liquidity â The Case of Chi-X
With the Markets in Financial Instruments Directive in effect since November 2007, new trading venues have emerged in European equities trading, among them Chi-X. This paper analyzes the impact of this new market entrant on the home market as well as on consolidated liquidity of French blue chip equities, newly tradable on Chi-X. Our findings suggest that owing to this new competition the home marketâs liquidity has enhanced. This is apparently due to the battle for order flow which results in narrower spreads and increased market depth. These results imply that overall liquidity in a virtually consolidated order book is in the French case higher than without the new competitor
On inversions and Doob -transforms of linear diffusions
Let be a regular linear diffusion whose state space is an open interval
. We consider a diffusion which probability law is
obtained as a Doob -transform of the law of , where is a positive
harmonic function for the infinitesimal generator of on . This is the
dual of with respect to where is the speed measure of
. Examples include the case where is conditioned to stay above
some fixed level. We provide a construction of as a deterministic
inversion of , time changed with some random clock. The study involves the
construction of some inversions which generalize the Euclidean inversions.
Brownian motion with drift and Bessel processes are considered in details.Comment: 19 page
B-->pi and B-->K transitions in standard and quenched chiral perturbation theory
We study the effects of chiral logs on the heavy-->light pseudoscalar meson
transition form factors by using standard and quenched chiral perturbation
theory combined with the static heavy quark limit. The resulting expressions
are used to indicate the size of uncertainties due to the use of the quenched
approximation in the current lattice studies. They may also be used to assess
the size of systematic uncertainties induced by missing chiral log terms in
extrapolating toward the physical pion mass. We also provide the coefficient
multiplying the quenched chiral log, which may be useful if the quenched
lattice studies are performed with very light mesons.Comment: 33 pages, 8 PostScript figures, version to appear in PR
Searching for chiral logs in the static-light decay constant
Using the clover fermion action in unquenched QCD with pion masses as low as
420 MeV, we look for evidence for chiral logs in the static-light decay
constant. There is some evidence for a chiral log term, if the original static
theory of Eichten and Hill is used. However, the more precise data from the
static action of the ALPHA collaboration do not show any evidence for
non-linear dependence of the static-light decay constant on the light quark
mass. We make some comments on the connection between chiral perturbation
theory for decay constants of the pion and static-light meson
Lattice Calculation of Heavy-Light Decay Constants with Two Flavors of Dynamical Quarks
We present results for , , , and their ratios in
the presence of two flavors of light sea quarks (). We use Wilson light
valence quarks and Wilson and static heavy valence quarks; the sea quarks are
simulated with staggered fermions. Additional quenched simulations with
nonperturbatively improved clover fermions allow us to improve our control of
the continuum extrapolation. For our central values the masses of the sea
quarks are not extrapolated to the physical , masses; that is, the
central values are "partially quenched." A calculation using "fat-link clover"
valence fermions is also discussed but is not included in our final results. We
find, for example,
MeV, , MeV, and , where in each case the first error is
statistical and the remaining three are systematic: the error within the
partially quenched approximation, the error due to the missing strange
sea quark and to partial quenching, and an estimate of the effects of chiral
logarithms at small quark mass. The last error, though quite significant in
decay constant ratios, appears to be smaller than has been recently suggested
by Kronfeld and Ryan, and Yamada. We emphasize, however, that as in other
lattice computations to date, the lattice quark masses are not very light
and chiral log effects may not be fully under control.Comment: Revised version includes an attempt to estimate the effects of chiral
logarithms at small quark mass; central values are unchanged but one more
systematic error has been added. Sections III E and V D are completely new;
some changes for clarity have also been made elsewhere. 82 pages; 32 figure
Phenology, caudex growth and age estimation of Cyathea corcovadensis (Raddi) Domin (Cyatheaceae) in a subtropical forest in southern Brazil
On post-Lie algebras, Lie--Butcher series and moving frames
Pre-Lie (or Vinberg) algebras arise from flat and torsion-free connections on
differential manifolds. They have been studied extensively in recent years,
both from algebraic operadic points of view and through numerous applications
in numerical analysis, control theory, stochastic differential equations and
renormalization. Butcher series are formal power series founded on pre-Lie
algebras, used in numerical analysis to study geometric properties of flows on
euclidean spaces. Motivated by the analysis of flows on manifolds and
homogeneous spaces, we investigate algebras arising from flat connections with
constant torsion, leading to the definition of post-Lie algebras, a
generalization of pre-Lie algebras. Whereas pre-Lie algebras are intimately
associated with euclidean geometry, post-Lie algebras occur naturally in the
differential geometry of homogeneous spaces, and are also closely related to
Cartan's method of moving frames. Lie--Butcher series combine Butcher series
with Lie series and are used to analyze flows on manifolds. In this paper we
show that Lie--Butcher series are founded on post-Lie algebras. The functorial
relations between post-Lie algebras and their enveloping algebras, called
D-algebras, are explored. Furthermore, we develop new formulas for computations
in free post-Lie algebras and D-algebras, based on recursions in a magma, and
we show that Lie--Butcher series are related to invariants of curves described
by moving frames.Comment: added discussion of post-Lie algebroid
Supersymmetry and Electroweak breaking from extra dimensions at the TeV-scale
We analyze some features of the role that extra dimensions, of radius in
the TeV range, can play in the soft breaking of supersymmetry and the
spontaneous breaking of electroweak symmetry. We use a minimal model where the
gauge and Higgs sector of the MSSM are living in the bulk of five dimensions
and the chiral multiplets in a four-dimensional boundary. Supersymmetry is
broken in the bulk by the Scherk-Schwarz mechanism and transmitted to the
boundary by radiative corrections. The particle spectrum is completely
predicted as a function of a unique -charge. The massless sector corresponds
to the pure Standard Model and electroweak symmetry is radiatively broken with
a light Higgs weighing \simlt 110 GeV. The -problem is solved and
Higgsinos, gauginos and heavy Higgses acquire masses . Chiral
sfermions acquire radiative squared-masses . The effective
potential is explicitly computed in the bulk of extra dimensions and some
cosmological consequences can be immediately drawn from it. Gauge coupling
running and unification is studied in the presence of Scherk-Schwarz
supersymmetry breaking. The unification is similar to that in the
supersymmetric theory.Comment: 27 pages, Latex, 7 figures. Minor change
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