A combined amplitude analysis is performed for the decays B^{0}→Dover ¯^{0}D_{s}^{+}π^{-} and B^{+}→D^{-}D_{s}^{+}π^{+}, which are related by isospin symmetry. The analysis is based on data collected ...by the LHCb detector in proton-proton collisions at center-of-mass energies of 7, 8, and 13 TeV. The full data sample corresponds to an integrated luminosity of 9 fb^{-1}. Two new resonant states with masses of 2.908±0.011±0.020 GeV and widths of 0.136±0.023±0.013 GeV are observed, which decay to D_{s}^{+}π^{+} and D_{s}^{+}π^{-} respectively. The former state indicates the first observation of a doubly charged open-charm tetraquark state with minimal quark content csover ¯udover ¯, and the latter state is a neutral tetraquark composed of csover ¯uover ¯d quarks. Both states are found to have spin-parity of 0^{+}, and their resonant parameters are consistent with each other, which suggests that they belong to an isospin triplet.
Many hypotheses, either sex‐related or environment‐related, have been proposed to explain sexual size dimorphism in birds. Two populations of blue tits provide an interesting case study for testing ...these hypotheses because they live in contrasting environments in continental France and in Corsica and exhibit different degree of sexual size dimorphism. Contrary to several predictions, the insular population is less dimorphic than the continental one but neither the sexual selection hypothesis nor the niche variation hypothesis explain the observed patterns. In the mainland population it is advantageous for both sexes to be large, and males are larger than females. In Corsica, however, reproductive success was greater for pairs in which the male was relatively small, i.e. pairs in which sexual size dimorphism is reduced. The most likely explanation is that interpopulation differences in sexual size dimorphism are determined not by sex‐related factors, but by differences in sex‐specific reproductive roles and responses to environmental factors. Because of environmental stress on the island as a result of food shortage and high parasite infestations, the share of parents in caring for young favours small size in males so that a reduced sexual size dimorphism is not the target of selection but a by‐product of mechanisms that operate at the level of individual sexes.
A molecular phylogeny based on DNA/DNA hybridization revealed that the Sylvia‐Parisoma complex is monophyletic and includes three main groups of species, the “mid‐European” warblers, the genus ...Parisoma, and the “eu‐Mediterranean” Sylvia species sensu stricto. The latter can be assigned to three main clusters, a “West‐Mediterranean” group, a “Central‐Mediterranean group”, and an “East‐Mediterranean” group. The radiation of the whole complex is much more ancient than formerly believed. It started ca 12–13 Ma ago and the ancestors of the main extant groups differentiated during the Pliocene. Only speciation events within the “eu‐Mediterranean” lineages occurred during the Pleistocene. The paleoclimatical and paleoecological history of the Mediterranean region is too complicated to provide any evidence for direct relationships between past events and evolutionary steps of these taxa which did not leave any reliable fossil record. However, some major speciation events may be related to well documented climatical crises as well as paleobotanical data. The largely man‐induced extension of matorrals over several millenia presumably extended the range of several species that were formerly much more restricted, which complicates reconstruction of the spatio‐temporal course of speciation.
Geographically separated populations may diverge genetically in response to differing environmental conditions. Two populations of blue tits (Parus caeruleus L., 1758) that inhabit distinct valleys ...in northern Corsica are exposed to extreme differences in food abundance and parasite loads and show differences in nestling mass and hematocrit levels at fledging. We used partial cross-fostering coupled with experimental manipulation of parasite loads to test the hypothesis that between-population differences in nestling mass and hematocrit reflect adaptive genetic responses to differing parasite prevalence. Although asymptotic mass and hematocrit were strongly affected by variation in parasite loads and caterpillar abundance, we did not detect any significant genetic (population of origin) effect or genotype-environment interaction. We conclude that in these populations of blue tits, asymptotic mass and hematocrit are phenotypically plastic traits that are primarily set by environmental conditions during the sensitive growth phase.
A
bstract
A combination of measurements sensitive to the
CP
violation angle
γ
of the Cabibbo-Kobayashi-Maskawa unitarity triangle and to the charm mixing parameters that describe oscillations between
...D
0
and
D
¯
0
mesons is performed. Results from the charm and beauty sectors, based on data collected with the LHCb detector at CERN’s Large Hadron Collider, are combined for the first time. This method provides an improvement on the precision of the charm mixing parameter
y
by a factor of two with respect to the current world average. The charm mixing parameters are determined to be
x
=
0.400
−
0.053
+
0.052
%
and
y
=
0.630
−
0.030
+
0.033
%
. The angle
γ
is found to be
γ
=
65.4
−
4.2
+
3.8
°
and is the most precise determination from a single experiment.
The Ξ_{c}^{+}K^{-} mass spectrum is studied with a sample of pp collision data corresponding to an integrated luminosity of 3.3 fb^{-1}, collected by the LHCb experiment. The Ξ_{c}^{+} is ...reconstructed in the decay mode pK^{-}π^{+}. Five new, narrow excited Ω_{c}^{0} states are observed: the Ω_{c}(3000)^{0}, Ω_{c}(3050)^{0}, Ω_{c}(3066)^{0}, Ω_{c}(3090)^{0}, and Ω_{c}(3119)^{0}. Measurements of their masses and widths are reported.
The quantum numbers of the X(3872) meson are determined to be J(PC)=1(++) based on angular correlations in B(+)→X(3872)K(+) decays, where X(3872)→π(+)π(-)J/ψ and J/ψ→μ(+)μ(-). The data correspond to ...1.0 fb(-1) of pp collisions collected by the LHCb detector. The only alternative assignment allowed by previous measurements J(PC)=2(-+) is rejected with a confidence level equivalent to more than 8 Gaussian standard deviations using a likelihood-ratio test in the full angular phase space. This result favors exotic explanations of the X(3872) state.
OBJECTIVES The relation betweem serum lipids and ischaemic stroke remains controversial. Studies of lipid related risk factors in cerebrovascular disease have varied greatly in their findings and ...also in their definition of the cerebrovascular end points. Serum lipids are thought to interact with the pathogenesis of stroke through an atherosclerosis mechanism. Stroke in young patients have been shown to be related to non-atherosclerotic causes most of the time. The aim was to determine the serum lipid profile and the vascular risk factors for ischaemic stroke in a series of patients under 45 with an ischaemic stroke and to compare them with a series of controls of the same age. METHODS Ninety four consecutive patients with ischaemic stroke were compared with 111 controls of the same age recruited from a regional electoral list. Vascular risk factors were recorded and serum lipid profile was determined in all of them. RESULTS Multivariate analyses showed that low HDL cholesterol, male sex, smoking, hypertension, and oral contraceptives were risk factors for intracerebral arterial occlusion. CONCLUSION Low HDL cholesterol was the only serum lipid index to be associated to an increased risk of stroke in this population. Low HDL cholesterol must be considered in the care management of young patients regardless of the detectable presence of atherosclerosis.
Resonant structures in B^{0}→ψ^{'}π^{-}K^{+} decays are analyzed by performing a four-dimensional fit of the decay amplitude, using pp collision data corresponding to 3 fb^{-1} collected with the ...LHCb detector. The data cannot be described with K^{+}π^{-} resonances alone, which is confirmed with a model-independent approach. A highly significant Z(4430)^{-}→ψ^{'}π^{-} component is required, thus confirming the existence of this state. The observed evolution of the Z(4430)^{-} amplitude with the ψ^{'}π^{-} mass establishes the resonant nature of this particle. The mass and width measurements are substantially improved. The spin parity is determined unambiguously to be 1^{+}.
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