Measurement of the Bottom-Strange Meson Mixing Phase in the Full CDF Data Set

We report a measurement of the bottom-strange meson mixing phase \beta_s using the time evolution of B0_s -> J/\psi (->\mu+\mu-) \phi (-> K+ K-) decays in which the quark-flavor content of the bottom-strange meson is identified at production. This measurement uses the full data set of proton-antiproton collisions at sqrt(s)= 1.96 TeV collected by the Collider Detector experiment at the Fermilab Tevatron, corresponding to 9.6 fb-1 of integrated luminosity. We report confidence regions in the two-dimensional space of \beta_s and the B0_s decay-width difference \Delta\Gamma_s, and measure \beta_s in [-\pi/2, -1.51] U [-0.06, 0.30] U [1.26, \pi/2] at the 68% confidence level, in agreement with the standard model expectation. Assuming the standard model value of \beta_s, we also determine \Delta\Gamma_s = 0.068 +- 0.026 (stat) +- 0.009 (syst) ps-1 and the mean B0_s lifetime, \tau_s = 1.528 +- 0.019 (stat) +- 0.009 (syst) ps, which are consistent and competitive with determinations by other experiments.Comment: 8 pages, 2 figures, Phys. Rev. Lett 109, 171802 (2012

Shade-induced response and recovery of the seagrass Posidonia sinuosa

The effect of shading on the seagrass Posidonia sinuosa Cambridge et Kuo was investigated to identify mechanisms that prolong its survival during periods of low light and permit its subsequent recovery. We also tested whether the responses were consistent in plants growing at different depths. Shade treatments were low (LS; 70 – 100% of ambient Photosynthetic Photon Flux Density), medium (MS; 12 – 39%) and heavy (HS; 5 – 4%) at the shallow (3 – 4 m) site, whilst the deep (7 – 8 m) site had no HS treatment. HS at the shallow and MS at the deep site were below minimum light requirements (MLR) for the long-term survival of P. sinuosa. Physiological, morphological and growth attributes were repeatedly measured during 198 d of shade treatments and a subsequent 384 d recovery period at ambient PPFD. Shoot density declined by 82% within 105 d under HS treatment, though 6% of shoots remained after 198 d. We estimate that complete shoot loss in HS would have taken 2 years. Rhizome sugar concentrations declined to 32 – 52% of the controls at the end of the most severe shading treatments but after shoot loss, sugar concentrations declined more slowly or increased, suggesting a return to positive carbon balance. In the treatments below MLR, shading induced changes in physiological, morphological and growth characteristics, including reduced leaf length and width, reduced δ13C and photosynthetic adaptation to low light (increased α, reduced Ek and ETRmax), though not consistently. After removal of shading, photosynthetic characteristics became more typical of high light adaptation, possibly induced by greater light penetration through the thinned canopy, including reversal of the changes in α, Ek and ETRmax and induction of non-photochemical quenching. Carbohydrate concentrations increased to ambient concentrations within 115 d at ambient PPFD. Recovery of shoot density was slow, remaining significantly reduced in the MS and HS treatments after 384 d recovery. Shoot density at the end of shading is an important determinant of the rate seagrass meadows will recover and we estimated that the moderately and heavily shaded meadows would require 3.5 to 5 years to recover

Effects of dredging on critical ecological processes for marine invertebrates, seagrasses and macroalgae, and the potential for management with environmental windows using Western Australia as a case study

Dredging can have significant impacts on benthic marine organisms through mechanisms such as sedimentation and reduction in light availability as a result of increased suspension of sediments. Phototrophic marine organisms and those with limited mobility are particularly at risk from the effects of dredging. The potential impacts of dredging on benthic species depend on biological processes including feeding mechanism, mobility, life history characteristics (LHCs), stage of development and environmental conditions. Environmental windows (EWs) are a management technique in which dredging activities are permitted during specific periods throughout the year; avoiding periods of increased vulnerability for particular organisms in specific locations. In this review we identify these critical ecological processes for temperate and tropical marine benthic organisms; and examine if EWs could be used to mitigate dredging impacts using Western Australia (WA) as a case study. We examined LHCs for a range of marine taxa and identified, where possible, their vulnerability to dredging. Large gaps in knowledge exist for the timing of LHCs for major species of marine invertebrates, seagrasses and macroalgae, increasing uncertainty around their vulnerability to an increase in suspended sediments or light attenuation. We conclude that there is currently insufficient scientific basis to justify the adoption of generic EWs for dredging operations in WA for any group of organisms other than corals and possibly for temperate seagrasses. This is due to; 1) the temporal and spatial variation in the timing of known critical life history stages of different species; and 2) our current level of knowledge and understanding of the critical life history stages and characteristics for most taxa and for most areas being largely inadequate to justify any meaningful EW selection. As such, we suggest that EWs are only considered on a case-by-case basis to protect ecologically or economically important species for which sufficient location-specific information is available, with consideration of probable exposures associated with a given mode of dredging