Role, importance and vulnerability of top predators on the Great Barrier Reef: a review

The purpose of this review is to evaluate the ecological role of predators on the Great Barrier Reef (GBR), their vulnerability to human activities and their contribution to ecosystem and economic values. Marine systems around the world are under increasing pressure, from the localised anthropogenic impacts of fishing and terrestrial run-off to the global pressures of climate change. There is concern over exploitation and declining numbers and biomass of large marine predators, worldwide and on the GBR. Understanding the role of predation and the consequences of predator loss is a priority for managers. To better understand the link between the protection of exploited fish stocks, the enhancement of the GBR’s overall resilience and the maintenance of ecosystem structure and function, this review seeks to answer the following questions:ID: 181

Identification of polymorphisms in reference barley genotypes based on the polymerase chain reaction

La technique de réplication #in vitro$ (PCR) peut être utilisée pour détecter du polymorphisme de l'ADN. Quatre génotypes de référence d'orge ont été évalués pour leur polymorphisme après amplification spécifique de séquence du génome nucléaire. La ségrégation de marqueurs impliquant une PCR a été observée à l'intérieur d'une descendance F5. L'intérêt des marqueurs utilisant la PCR comme marqueur génétique chez l'orge est discuté. (Résumé d'auteur

Shocks and PDRs in an intermediate mass star forming globule: the case of IC1396N

The dark globule IC1396N is a typical example of a star formation process induced by radiation driven implosion due to the strong UV field from a nearby O6 star. The IRAS source embedded in the globule and its associated molecular outflow have been observed with the Long Wavelength Spectrometer (LWS) on ISO revealing an extremely rich spectrum including: CO rotational lines from J=14-13 up to J=28-27, rotational lines from ortho-H2O, OH lines involving the first four rotational levels of both ladders, atomic (OI 63μm, OI 145μm) and ionic (CII 157μm, OIII 52μm, OIII 88μm) lines. A complex picture arises, where an externally illuminated PDR coexists with strong C-shocks within IC1396N and whose origin is not clear

High-J CO line emission from young stellar objects: from ISO to FIRST

we present the CO pure rotational spectrum at high J (Jup14) obtained with the Long Wavelength Spectrometer (LWS) on board of the ISO satellite towards molecular outflows exciting sources in nearby star formation regions. The physical conditions, derived using an LVG model for the line emission, indicate the presence of warm and dense gas, probably shock excited. The model fits show that often the bulk of this CO emission is expected in the spectral range that will be covered by FIRST, indicating the potentiality of this satellite to trace the warm component of gas emission in young stellar objects

A Concerted Variational Strategy for Investigating Rare Events

A strategy for finding transition paths connecting two stable basins is presented. The starting point is the Hamilton principle of stationary action; we show how it can be transformed into a minimum principle through the addition of suitable constraints like energy conservation. Methods for improving the quality of the paths are presented: for example, the Maupertuis principle can be used for determining the transition time of the trajectory and for coming closer to the desired dynamic path. A saddle point algorithm (conjugate residual method) is shown to be efficient for reaching a ``true'' solution of the original variational problem.Comment: 3 figures, accepted for publication in Journal of Chemical Physic

Upper limit for the D2H+ ortho-to-para ratio in the prestellar core 16293E (CHESS)

The H3+ ion plays a key role in the chemistry of dense interstellar gas clouds where stars and planets are forming. The low temperatures and high extinctions of such clouds make direct observations of H3+ impossible, but lead to large abundances of H2D+ and D2H+, which are very useful probes of the early stages of star and planet formation. The ground-state rotational ortho-D2H+ 111-000 transition at 1476.6 GHz in the prestellar core 16293E has been searched for with the Herschel/HIFI instrument, within the CHESS (Chemical HErschel Surveys of Star forming regions) Key Program. The line has not been detected at the 21 mK km/s level (3 sigma integrated line intensity). We used the ortho-H2D+ 110-111 transition and para-D2H+ 110-101 transition detected in this source to determine an upper limit on the ortho-to-para D2H+ ratio as well as the para-D2H+/ortho-H2D+ ratio from a non-LTE analysis. The comparison between our chemical modeling and the observations suggests that the CO depletion must be high (larger than 100), with a density between 5e5 and 1e6 cm-3. Also the upper limit on the ortho-D2H+ line is consistent with a low gas temperature (~ 11 K) with a ortho-to-para ratio of 6 to 9, i.e. 2 to 3 times higher than the value estimated from the chemical modeling, making it impossible to detect this high frequency transition with the present state of the art receivers.Comment: Accepted in A&