Effect of increased CO₂ and iron levels on the marine plankton food web during a mesocosm experiment

A mesocosm experiment was carried out in the Raunefjord (Norway) during 25 days, to investigate the interactive effects of increased CO2 and iron availability on the plankton community. The seawater carbonate system in the mesocosms was manipulated to achieve two different CO2 levels, corresponding to the present (390 ppmv, LC) and to levels predicted for year 2100 (900 ppmv, HC), in combination with ambient and increased dissolved Fe (dFe) concentrations in a full factorial design. We observed a shift in the plankton community structure, initially dominated by picoeukaryotes and small nanoeukaryotes, changing to an Emiliania huxleyi dominated bloom. E. huxleyi and Synechococcus were the most sensitive organisms to changes in CO2 and Fe levels, being negatively affected by increased CO2 and favoured by high dFe levels. Picoeukaryotes, large nanoplankton, viruses and ciliates abundances were not affected by changes in CO2 or dFe levels. Bacterial abundance showed a significant positive response to high CO2 but it was unaffected by dFe. Total mesozooplankton abundances did not change significantly. The relevance of these results within the global change scenario will be discussed.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Multifrequency and multifunction antennas based on single printed technology partially filled with metamaterial structures

The Radiofrequency Group from the Escuela Politécnica Superior of the Carlos III University from Madrid have been working in printed antennas for a long time. Recently the new technology of metamaterials has opened new possibilities in the development of multifrequency antennas with different radiation patterns to be used simultaneously for several applications (i.e. different mobile services and GPS or Galileo

Improved determination of Heavy Quarkonium magnetic dipole transitions in pNRQCD

We compute the magnetic dipole transitions between low lying Heavy Quarkonium states in a model independent way. We use the weak-coupling version of the effective field theory named potential NRQCD with the static potential exactly incorporated in the leading order Hamiltonian. The precision we reach is $k_{\gamma}^3/m^2\times{\cal O}(\alpha_s^2,v^2)$ and $k_{\gamma}^3/m^2\times{\cal O}(v^4)$ for the allowed and forbidden transitions respectively. We also resum the large logarithms associated to the heavy quark mass scale. The specific transitions considered in this paper are the following: $\Upsilon(1S) \to \eta_b(1S)\,\gamma$, $J/\psi(1S) \to \eta_c(1S)\,\gamma$, $h_b(1P) \to \chi_{b0,1}(1P)\,\gamma$, $\chi_{b2}(1P) \to h_b(1P)\,\gamma$, $\Upsilon(2S) \to \eta_b(2S)\,\gamma$, $\Upsilon(2S) \to \eta_b(1S)\,\gamma$ and $\eta_b(2S)\to\Upsilon(1S)\,\gamma$. The effect of the new power counting is found to be large and the exact treatment of the soft logarithms of the static potential makes the factorization scale dependence much smaller. The convergence for the $b\bar b$ ground state is quite good, and also quite reasonable for the $c\bar c$ ground state and the $b\bar b$ 1P state. For all of them we give solid predictions. For the 2S decays the situation is less conclusive, yet our results are perfectly consistent with existing data, as the previous disagreement with experiment for the $\Upsilon(2S) \to \eta_b(1S)\,\gamma$ decay fades away. We also profit to compute some expectation values like the electromagnetic radius, r^2, or p^2. We find r^2 to be nicely convergent in all cases, whereas the convergence of p^2 is typically worse.Comment: 42 pages, 15 figures. Numbering of references on figure 9 has been correcte

The nature of the X(3915)/X(3930)X(3915)/X(3930) resonances from a coupled-channels approach

The positive parity $\chi_{cJ}(2P)$ charmonium states are expected to lie around the 3.9 GeV/$c^2$ energy region, according to the predictions of quark models. However, a plethora of states with difficult assignment and unconventional properties have been discovered over the years, i.e., the $X(3872)$, $X(3940)$, $Y(3940)$, $X(3915)$, $X(3860)$ and the $X(3930)$ resonances, which complicates the description of this intriguing region. In this work we analyze the $0^{++}$ and $2^{++}$ sectors, employing a coupled-channels formalism successfully applied to the $1^{++}$ sector, where the $X(3872)$ was described as a $D\bar D^\ast+h.c.$ molecule with a sizable $c\bar c$ $(2^3P_1)$ component. This coupled-channels formalism is based on a widely-used Constituent Quark Model, which describes the quark-quark interactions, and the $^3P_0$ quark pair creation mechanism, used to couple the two and four quark sectors. The recent controversy about the quantum numbers of the $X(3915)$ state, the properties of the $X(3930)$ one and the nature of the new $X(3860)$ resonance are analyzed in a unified theoretical framework, being all the parameters completely constrained from previous calculations in the low-lying heavy quarkonium phenomenology.Comment: 6 pages, 2 tables. XVII International Conference on Hadron Spectroscopy and Structure - Hadron201