12,401 research outputs found
Hodge numbers for the cohomology of Calabi-Yau type local systems
We use Higgs cohomology to determine the Hodge numbers of the first
intersection cohomology group of a local system V arising from the third direct
image of a family of Calabi-Yau 3-folds over a smooth, quasi-projective curve.
We give applications to Rhode's families of Calabi-Yau 3-folds without MUM.Comment: Some signs corrected. This article draws heavily from arXiv:0911.027
Extrapolation of K to \pi\pi decay amplitude
We examine the uncertainties involved in the off-mass-shell extrapolation of
the decay amplitude with emphasis on those aspects that
have so far been overlooked or ignored. Among them are initial-state
interactions, choice of the extrapolated kaon field, and the relation between
the asymptotic behavior and the zeros of the decay amplitude. In the inelastic
region the phase of the decay amplitude cannot be determined by strong
interaction alone and even its asymptotic value cannot be deduced from
experiment. More a fundamental issue is intrinsic nonuniqueness of off-shell
values of hadronic matrix elements in general. Though we are hampered with
complexity of intermediate-energy meson interactions, we attempt to obtain a
quantitative idea of the uncertainties due to the inelastic region and find
that they can be much larger than more optimistic views portray.Comment: 16 pages with 5 eps figures in REVTE
Workshop on Mapping out a CCAFS R4D Agenda and Strategy for Southeast Asia
Taking off from the convergence meeting of CGIAR Centers and selected
partners in December 2013, this regional workshop to mapped out a CCAFS
R4D agenda and strategy for Southeast Asia (SEA). The region was added to
the CCAFS portfolio (East Africa, West Africa, South America, South Asia) in
order to make the program fully global
Pinguicula rosmarieae Casper, Bussmann & T.Henning (Lentibulariaceae), a new butterwort from the Amotape-Huancabamba Zone (northern Peru)
The insectivorous genus Pinguicula occurs along the whole Andean mountain chain from Colombia-Venezuela in the north to Tierra del Fuego in the south with a short interruption in the Peruvian-Chilean desert range. This paper describes a new and striking species of Pinguicula that occurs in the south-eastern part of the Amotape-Huancabamba Zone in north Peru. It grows either as a lithophyte on moist rocks or as an epiphyte on Polylepis multijuga Pilg. in the wet highlands of the Cordillera Central. Pinguicula rosmarieae Casper, Bussmann & T.Henning, sp. nov. is clearly distinguished by a basal rosette of ovate-obovate leaves spread out flat on the ground and especially by a two-partite corolla with a straight uniform tube-spur complex, two features unknown from other Andean Pinguicula species. The morphological similarity to P. calyptrata Kunth is discussed and the habitat and distribution of P. rosmarieae are characterised
Analytical results for O(\alpha_s) radiative corrections to e+ e- -> tbar t(pol.) up to a given gluon energy cut
We determine the O(\alpha_s) radiative corrections to polarized top quark
pair production in e+ e- -annihilations with a specified gluon energy cut. We
write down fully analytical results for the unpolarized and polarized
O(\alpha_s) cross sections e+ e- -> tbar t (G) and e+ e- -> tbar t(pol.) (G)
including their polar orientation dependence relative to the beam direction. In
the soft gluon limit we recover the usual factorizing form known from the soft
gluon approximation. In the limit when the gluon energy cut takes its maximum
value we recover the totally inclusive unpolarized and polarized cross sections
calculated previously. We provide some numerical results on the cut-off
dependence of the various polarized and unpolarized cross sections and discuss
how the exact results numerically differ from the approximate soft-gluon
results.Comment: 49 pages in LaTeX, including 17 encapsulated PostScript figure
Euclidean versus hyperbolic congestion in idealized versus experimental networks
This paper proposes a mathematical justification of the phenomenon of extreme
congestion at a very limited number of nodes in very large networks. It is
argued that this phenomenon occurs as a combination of the negative curvature
property of the network together with minimum length routing. More
specifically, it is shown that, in a large n-dimensional hyperbolic ball B of
radius R viewed as a roughly similar model of a Gromov hyperbolic network, the
proportion of traffic paths transiting through a small ball near the center is
independent of the radius R whereas, in a Euclidean ball, the same proportion
scales as 1/R^{n-1}. This discrepancy persists for the traffic load, which at
the center of the hyperbolic ball scales as the square of the volume, whereas
the same traffic load scales as the volume to the power (n+1)/n in the
Euclidean ball. This provides a theoretical justification of the experimental
exponent discrepancy observed by Narayan and Saniee between traffic loads in
Gromov-hyperbolic networks from the Rocketfuel data base and synthetic
Euclidean lattice networks. It is further conjectured that for networks that do
not enjoy the obvious symmetry of hyperbolic and Euclidean balls, the point of
maximum traffic is near the center of mass of the network.Comment: 23 pages, 4 figure
CCAFS Theory of Change facilitation guide
The CGIAR Research Program on Climate Change, Agriculture and Food Security (CCAFS) has in total produced two facilitation guides to support the development of Impact Pathways and project Monitoring and Evaluation (M&E) for result-based management. The "CCAFS Theory of Change facilitation guide" is the original, and more comprehensive guide, and was developed in June 2014. The updated version is more easy-to-use and stripped down version of the original facilitation guide, called "Revised CCAFS Theory of Change Facilitation Guide", from late 2014. The Annex belongs to the original version.
The updated version can be found here: http://hdl.handle.net/10568/5687
Functional modulation of the transient outward current Ito by KCNE beta-subunits and regional distribution in human non-failing and failing hearts
Objectives: The function of Kv4.3 (KCND3) channels, which underlie the transient outward current I,, in human heart, can be modulated by several accessory subunits such as KChIP2 and KCNE1-KCNE5. Here we aimed to determine the regional expression of Kv4.3, KChIP2, and KCNE mRNAs in non-failing and failing human hearts and to investigate the functional consequences of subunit coexpression in heterologous expression systems.
Methods: We quantified mRNA levels for two Kv4.3 isoforms, Kv4.3-S and Kv4.3-L, and for KChIP2 as well as KCNE1-KCNE5 with real-time RT-PCR. We also studied the effects of KCNEs on Kv4.3 + KChIP2 current characteristics in CHO cells with the whole-cell voltage-clamp method.
Results: In non-failing hearts, low expression was found for KCNE1, KCNE3, and KCNE5, three times higher expression for KCNE2, and 60 times higher for KCNE4. Transmural gradients were detected only for KChIP2 in left and right ventricles. Compared to non-failing tissue, failing hearts showed higher expression of Kv4.3-L and KCNE1 and lower of Kv4.3-S, KChIP2, KCNE4, and KCNE5. In CHO cells, Kv4.3 + KChIP2 currents were differentially modified by co-expressed KCNEs: time constants of inactivation were shorter with KCNE1 and KCNE3-5 while time-to-peak was decreased, and V-0.5 of steady-state inactivation was shifted to more negative potentials by all KCNE subunits. Importantly, KCNE2 induced a unique and prominent 'overshoot' of peak current during recovery from inactivation similar to that described for human I-to while other KCNE subunits induced little (KCNE4,5) or no overshoot.
Conclusions: All KCNEs are expressed in the human heart at the transcript level. Compared to It. in native human myocytes, none of the combination of KChIP2 and KCNE produced an ideal congruency in current characteristics, suggesting that additional factors contribute to the regulation of the native I-to channel
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