997 research outputs found
Maturation Trends Suggestive of Rapid Evolution Preceded the Collapse of Northern Cod
Northern cod, comprising populations of Atlantic cod (Gadus morhua) off southern Labrador and eastern Newfoundland, supported major fisheries for hundreds of years. But in the late 1980s and early 1990s, northern cod underwent one of the worst collapses in the history of fisheries. The Canadian government closed the directed fishing for northern cod in July 1992, but even after a decade-long offshore moratorium, population sizes remain historically low. Here we show that, up until the moratorium, the life history of northern cod continually shifted towards maturation at earlier ages and smaller sizes. Because confounding effects of mortality changes and growth-mediated phenotypic plasticity are accounted for in our analyses, this finding strongly suggests fisheries-induced evolution of maturation patterns in the direction predicted by theory. We propose that fisheries managers could use the method described here as a tool to provide warning signals about changes in life history before more overt evidence of population decline becomes manifest
Maternal Influenza Infection During Pregnancy Impacts Postnatal Brain Development in the Rhesus Monkey
Background: Maternal infection with influenza and other pathogens during pregnancy has been associated with increased risk for schizophrenia and neurodevelopmental disorders. In rodent studies, maternal inflammatory responses to influenza affect fetal brain development. However, to verify the relevance of these findings to humans, research is needed in a primate species with more advanced prenatal corticogenesis. Methods: Twelve pregnant rhesus monkeys were infected with influenza, A/Sydney/5/97 (H3N2), 1 month before term (early third trimester) and compared with 7 control pregnancies. Nasal swabs and blood samples confirmed viral shedding and immune activation. Structural magnetic resonance imaging was conducted at 1 year; behavioral development and cortisol reactivity were also assessed. Results: Maternal infections were mild and self-limiting. At birth, maternally derived influenza-specific immunoglobulin G was present in the neonate, but there was no evidence of direct viral exposure. Birth weight and gestation length were not affected, nor were infant neuromotor, behavioral, and endocrine responses. However, magnetic resonance imaging analyses revealed significant reductions in cortical gray matter in flu-exposed animals. Regional analyses indicated the largest gray matter reductions occurred bilaterally in cingulate and parietal areas; white matter was also reduced significantly in the parietal lobe. Conclusions: Influenza infection during pregnancy affects neural development in the monkey, reducing gray matter throughout most of the cortex and decreasing white matter in parietal cortex. These brain alterations are likely to be permanent, given that they were still present at the monkey-equivalent of older childhood and thus might increase the likelihood of later behavioral pathology
Cosmological Creation of D-branes and anti-D-branes
We argue that the early universe may be described by an initial state of
space-filling branes and anti-branes. At high temperature this system is
stable. At low temperature tachyons appear and lead to a phase transition,
dynamics, and the creation of D-branes. These branes are cosmologically
produced in a generic fashion by the Kibble mechanism. From an entropic point
of view, the formation of lower dimensional branes is preferred and
brane-worlds are exponentially more likely to form than higher dimensional
branes. Virtually any brane configuration can be created from such phase
transitions by adjusting the tachyon profile. A lower bound on the number
defects produced is: one D-brane per Hubble volume.Comment: 30 pages, 5 eps figures; v2 more references added; v3 section 4
slightly improve
Fish Spawning Aggregations: Where Well-Placed Management Actions Can Yield Big Benefits for Fisheries and Conservation
Marine ecosystem management has traditionally been divided between fisheries management and biodiversity conservation approaches, and the merging of these disparate agendas has proven difficult. Here, we offer a pathway that can unite fishers, scientists, resource managers and conservationists towards a single vision for some areas of the ocean where small investments in management can offer disproportionately large benefits to fisheries and biodiversity conservation. Specifically, we provide a series of evidenced-based arguments that support an urgent need to recognize fish spawning aggregations (FSAs) as a focal point for fisheries management and conservation on a global scale, with a particular emphasis placed on the protection of multispecies FSA sites. We illustrate that these sites serve as productivity hotspots - small areas of the ocean that are dictated by the interactions between physical forces and geomorphology, attract multiple species to reproduce in large numbers and support food web dynamics, ecosystem health and robust fisheries. FSAs are comparable in vulnerability, importance and magnificence to breeding aggregations of seabirds, sea turtles and whales yet they receive insufficient attention and are declining worldwide. Numerous case-studies confirm that protected aggregations do recover to benefit fisheries through increases in fish biomass, catch rates and larval recruitment at fished sites. The small size and spatio-temporal predictability of FSAs allow monitoring, assessment and enforcement to be scaled down while benefits of protection scale up to entire populations. Fishers intuitively understand the linkages between protecting FSAs and healthy fisheries and thus tend to support their protection
Measurements of exclusive B_s^0 decays at the Y(5S) resonance
Several exclusive decays are studied using a 1.86 fb-1 data sample
collected at the Y(5S) resonance with the Belle detector at the KEKB asymmetric
energy e^+ e^- collider. In the decay mode we find 10
candidates and measure the corresponding branching fraction. Combining
the B_s^0 -> D_s^{(*)-} \pi^+, B_s^0 -> D_s^{(*)-} \rho^+, B_s^0 -> J/\psi \phi
and B_s^0 -> J/\psi \eta decay modes, a significant signal is observed.
The ratio \sigma (e^+ e^- -> B_s^* \bar{B}_s^*) / \sigma (e^+ e^- -> B_s^{(*)}
\bar{B}_s^{(*)}) = (93^{+7}_{-9} \pm 1)% is obtained at the Y(5S) energy,
indicating that meson production proceeds predominantly through the
creation of pairs. The and meson masses are
measured to be M(B_s^0)=(5370 \pm 1 \pm 3)MeV/c^2 and M(B_s^*)=(5418 \pm 1 \pm
3)MeV/c^2. Upper limits on the B_s^0 -> \gamma \gamma, B_s^0 -> \phi \gamma,
B_s^0 -> K^+ K^- and B_s^0 -> D_s^{(*)+} D_s^{(*)-} branching fractions are
also reported.Comment: 9 pages, 5 figures, published in Phys. Rev. D76, 012002 (2007
Measurement of the near-threshold cross section using initial-state radiation
We report measurements of the exclusive cross section for , where or , in the center-of-mass energy range from the threshold to with initial-state radiation. The
analysis is based on a data sample collected with the Belle detector with an
integrated luminosity of 673 .Comment: Presented at EPS07 and LP07 conferences, published in PRD(RC
Observation of Ds1(2536)+ -> D+pi-K+ and angular decomposition of Ds1(2536)+ -> D*+K0S
Using 462/fb of e+e- annihilation data recorded by the Belle detector, we
report the first observation of the decay Ds1(2536)+ -> D+pi-K+. The ratio of
branching fractions B(Ds1+ -> D+pi-K+)/B(Ds1+ -> D*+K0) is measured to be
(3.27+-0.18+-0.37)%. We also study the angular distributions in the Ds1(2536)+
-> D*+K0S decay and measure the ratio of D- and S-wave amplitudes. The S-wave
dominates, with a partial width of Gamma_S/Gamma_total=0.72+-0.05+-0.01.Comment: Submitted to Phys.Rev.D 16 pages, 6 figures, 3 table
Improved measurement of CP-violating parameters in rho+rho- decays
We present a measurement of the CP-violating asymmetry in rho+rho- decays
using 535 million BBbar pairs collected with the Belle detector at the KEKB
e+e- collider. We measure CP-violating coefficients A = 0.16 +- 0.21(stat) +-
0.07 (syst) and S = 0.19 +- 0.30(stat) +- 0.07 (syst}. These values are used to
determine the unitarity triangle angle phi_2 using an isospin analysis; the
solution consistent with Standard Model lies in the range 53 < phi_2 < 114 deg.
at 90 C.L.Comment: 6 pages, 4 figures, presented at JPS/DPF 2006 (Added KEK, BELLE
preprint numbers, submitted to PRD(RC)
Search for new charmonium states in the processes e+ e- --> J/psi D(*) D(*) at sqrt{s} ~ 10.6 GeV
We present a study of the X(3940) state in the process e+e- -> J/psi D* Dbar.
The X(3940) mass and width are measured to be (3942 +7 -6 +- 6)MeV/c^2 and
Gamma=(37 + 26 - 15 +- 8 MeV. In the process e+e- -> J/psi D* D*bar we have
observed another charmonium-like state, which we denote as X(4160), in the
spectrum of invariant masses of D*+ D*- combinations. The X(4160) parameters
are M= 4156 + 25 - 20 +- 15 MeV/c^2 and Gamma = 139 + 111 -61 +- 21 MeV. The
analysis is based on a data sample with an integrated luminosity of 693 /fb
recorded near the Upsilon(4S) resonance with the Belle detector at the KEKB e+
e- asymmetric-energy collider.Comment: 7 pages, 2 figures Contribution paper for conferences EPS2007 and
Lepton Photon 2007, Belle-Conference-070
Fit for what?: towards explaining Battlegroup inaction
The thrust of this paper concerns the case of the European Battlegroup (BG) non-deployment in late 2008, when the United Nations requested European military support for the United Nations Organisation Mission peacekeeping force in the Democratic Republic of the Congo (DRC). The argument is built on the fact that when, in official documents, the EU approaches the European security and ESDP/CSDP's military crisis management policy and interventions, it makes strong references to the United Nations and the UN Charter Chapter VII's mandate of restoring international peace and security. Such references make it seem that supporting the UN when it deals with threats and crises is a primary concern of the EU and the member states. These allusions lead to the main contention of this paper, that there is much ambivalence in these indications. The paper develops its argument from one key hypothesis; namely, that the non-deployment of a European BG in the DRC, at the end of 2008, constitutes a useful case study for detecting a number of ambiguities of the EU in respect of its declarations in the official documents establishing the European military crisis management intervention structure
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